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Treatment and Resource Recovery

Life Cycle Environmental Impacts of Wastewater-Derived Phosphorus Products: An Agricultural End-User Perspective
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Environmental Science & Technology

Cite this: Environ. Sci. Technol. 2022, 56, 14, 10289–10298
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https://doi.org/10.1021/acs.est.2c00353
Published July 7, 2022

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Abstract

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Recovering phosphorus from wastewater in more concentrated forms has potential to sustainably recirculate phosphorus from cities to agriculture. The environmental sustainability of wastewater-based phosphorus recovery processes or wastewater-derived phosphorus products can be evaluated using life cycle assessment (LCA). Many LCA studies used a process perspective to account for the impacts of integrating phosphorus recovery processes at wastewater treatment plants, while some used a product perspective to assess the impacts of producing wastewater-derived phosphorus products. We demonstrated the application of an end-user perspective by assessing life cycle environmental impacts of substituting half of the conventional phosphorus rock-based fertilizers used in three crop production systems with wastewater-derived phosphorus products from six recovery pathways (RPs). The consequential LCA results show that the substitution reduces global warming potential, eutrophication potential, ecotoxicity potential, and acidification potential of the assessed crop production systems in most RPs and scenarios. The end-user perspective introduced in this study can (i) complement with the process perspective and the product perspective to give a more holistic picture of environmental impacts along the “circular economy value chains” of wastewater-based resource recovery, (ii) enable systemwide assessment of wide uptake of wastewater-derived products, and (iii) draw attention to understanding the long-term environmental impacts of using wastewater-derived products.

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Synopsis

This study shows life cycle environmental benefits of the agricultural use of wastewater-derived phosphorus products from the end-user perspective instead of the typical wastewater treatment plant perspective.

Introduction

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Resource recovery from wastewater is gaining increasing attention, especially phosphorus recovery. (1−3) Phosphorus is essential for food production. Depleting phosphate rock reserves is becoming a driver for phosphorus recovery and reuse. (4) In wastewater treatment plants (WWTPs), precipitation of struvite and Ca–P from sludge digester liquors are well-developed and economically feasible phosphorus recovery technologies, while wet chemical extraction from sewage sludge and sludge ashes can achieve a higher recovery rate of the influent phosphorus load. (5) The recovered phosphorus products can potentially be used as fertilizers. (6) Recovering phosphorus at WWTPs also has the benefits of reducing the potential of eutrophication in effluent-receiving waters and saving maintenance costs from uncontrolled phosphorus precipitation. (7−9)
Life cycle assessment (LCA) has been used to evaluate the potential environmental impacts of various wastewater-based phosphorus recovery and reuse opportunities. (10,11) LCA can be used to compare technology alternatives, identify environmental hotspots, and understand environmental trade-offs. (12,13) For instance, Amann et al. (14) assessed the life cycle energy, global warming potential, and acidification potential of phosphorus recovery technologies from the liquid phase, sewage sludge, and sludge ashes. They found that recovery from the liquid phase (e.g., precipitation of struvite and Ca–P from sludge digester liquors) mostly has lower impacts on greenhouse gas (GHG) emissions and energy demand, though liquid phase recovery can only recover a fraction of the influent phosphorus load. In assessing both centralized and decentralized phosphorus recovery scenarios, Bradford-Hartke et al. (15) showed that chemical-based phosphorus recovery generally has a net environmental burden as the benefits from avoided fertilizers cannot offset the burdens from increased resource inputs.
Most LCA studies related to wastewater-based phosphorus recovery focus their assessments on the primary functionality of wastewater treatment or sludge disposal, that is, applying a process perspective (Figure 1), in which phosphorus recovery is considered as an additional functionality (i.e., avoiding the use of a phosphate rock-base fertilizer). While the process perspective (also called the waste management perspective) of assessing environmental impacts is useful for the design and operation of a WWTP and its recovery process, the end users of the recovered phosphorus products do not know the life cycle environmental impacts of applying these recovered products to their product systems. (11) Only few studies have quantified the environmental impacts of the wastewater-derived phosphorus products by applying a product perspective (Figure 1). Tonini et al. (16) and Hörtenhuber et al. (17) suggested that phosphorus products from incinerated sludge ashes have environmental advantages over conventional phosphate rock-based fertilizers. In this study, we extend the product perspective to an end-user perspective to investigate phosphorus recovery from the agricultural system’s point of view for the first time. To realize the total value of phosphorus recovery, end users must be considered early in the process of promoting phosphorus recovery. (7) This can be contributed by end-user perspective LCAs. The resource recovery implications of these perspectives (with different functional units) will be discussed in detail.

Figure 1

Figure 1. Process, product, and end-user perspectives of phosphorus recovery.

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This study assesses the life cycle environmental impacts of the agricultural use of wastewater-derived phosphorus products via six recovery pathways (RPs) in three crop production systems. Using phosphorus recovery as an example, this study demonstrates the application of the end-user perspective to develop a life cycle inventory and to understand the potential life cycle environmental consequences of substituting conventional inputs with recovered products at the end user’s product system. As more wastewater-derived products are becoming available, this perspective contributes toward understanding the potential systemic environmental consequences of a broader uptake of these products. The implications of conducting resource recovery LCA from an end-user perspective, compared to those from a process or product perspective, are discussed as well.

Materials and Methods

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Goal and Scope

The primary goal of this study is to assess life cycle environmental impacts of substituting conventional phosphate rock-based fertilizers with wastewater-derived phosphorus products in crop production systems from the end-user perspective (Figure 1). Applying the end-user perspective, the system boundary encompasses a crop production system and a WWTP integrated with phosphorus recovery. When conducting LCA for their own crops, crop producers would like to know when they apply wastewater-derived phosphorus products, how they could get the inventory for these recovered products, and what could be the potential environmental consequences of using these recovered products instead of conventional phosphate rock-based fertilizers.
Phosphorus products can be recovered via different RPs at municipal WWTPs (Figure 2). In this study, the treatment plant is a typical plant with an activated sludge water line, a sludge line with anaerobic digestion for biogas production, and a phosphorus recovery line. (18) Three major crop production systems are explored. For each crop, six RPs are compared based on a functional unit of producing 1 kg of that crop. The three crops are maize, rice, and wheat. Their cultivation using some of the wastewater-derived phosphorus products has been investigated in the literature. (19−23) In addition, the life cycle inventory of these crop production systems is available in the Ecoinvent life cycle inventory database. This study is based loosely on the U.S. context─(i) it uses the U.S. national average maize, rice, and wheat production systems from the Ecoinvent database, (24) (ii) it includes scenarios of typical sludge disposal methods in the U.S. (i.e., incineration, landfill, and land application), (25) and (iii) it uses the Tool for Reduction and Assessment of Chemicals and Other Environmental Impacts (TRACI 2.1) developed by the U.S. Environmental Protection Agency as the impact assessment method. (26)

Figure 2

Figure 2. Baseline pathways (BPn) without P recovery and six possible P recovery pathways (RP1–RP6), differing in the recovered phosphorus products (i.e., struvite, Ca–P, rhenania phosphate-like product, or single superphosphate-like product) and the possible inclusion of CEPT in the treatment line. For all RPs, the wastewater-derived phosphorus product was assumed to substitute half (1/2 ṁ) of the conventional phosphate rock-based fertilizers used in the baseline pathways (BPn). Besides, all RPs share the same baseline for the crop production system, while each RP has its baseline for the wastewater treatment system. Three crop production systems (i.e., maize, rice, and wheat) were considered.

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A “consequential” LCA approach (27) is used to assess the potential environmental impacts of the decision of substituting half of the conventional phosphate rock-based fertilizers with wastewater-derived phosphorus products, that is, whether applying the wastewater-derived phosphorus products would generally or conditionally lead to net environmental benefits or not. Half substitution is assumed because previous studies have shown that blending slow-releasing wastewater-derived phosphorus products with conventional phosphate rock-based fertilizers would not restrict early season growth. (19) Coproducts are being accounted for through system expansion (mainly biogas to avoid methane production).

Life Cycle Inventory

Pathways and Scenarios

A life cycle inventory was built for six RPs (RP1–RP6) and their associated baseline pathways (BPn, where n is from 1 to 6, respectively) (Figure 2). In RP1, struvite is precipitated through the addition of magnesium hydroxide to the digester supernatant. In RP2, Ca–P, in the form of tricalcium phosphate, is precipitated through the addition of calcium hydroxide to the digester supernatant. In practice, struvite and Ca–P are the most common phosphorus forms recovered in the water line. (28,29) In RP3, the sludge ashes from mono-incineration of digested sewage sludge undergoes a thermo-chemical treatment to yield a rhenania phosphate-like product. In RP5, the sludge ashes from mono-incineration of digested sewage sludge undergoes a chemical extraction process to yield single superphosphate and byproducts (i.e., calcium chloride and iron(III) chloride). Both RP4 and RP6 have the same recovery processes as RP3 and RP5, respectively, but RP4 and RP6 have chemically enhanced primary treatment (CEPT) in the water line to increase the phosphorus content in the sewage sludge. In practice, rhenania phosphate-like product and single superphosphate are common phosphorus forms recovered from the sludge ashes. (14,16)
Each RP has its associated baseline pathway. While all the RPs share the same baseline for the crop production system (i.e., the same phosphate rock-base fertilizer usage ṁ), each RP has its associated baseline for the wastewater treatment system (i.e., influent flowrate QRPn). Because the yields of the recovered phosphorus product differ across various RPs, different flowrates of the influent are needed to yield the recovered phosphorus product in each RP. Each RP substitutes half of the amount of the phosphate rock-based fertilizer (1/2 ṁ) with its wastewater-derived phosphorus product, while the influent flowrate of each RP is the same as that of its associated baseline pathway. An illustration of Figure 2 with numbers for a given scenario can be found in the Supporting Information (Figures S1 and S2).
Each pathway was modeled considering three different influent wastewater compositions [i.e., concentrations of P, N, chemical oxygen demand (COD), etc.], (30) three alternative sludge disposal methods (incineration, landfill, and land application), and three carbon intensity levels of grid electricity (low, medium, and high). For each crop, this results in 162 combinations of scenarios in total (i.e., 33 = 27 scenarios/pathway × 6 pathways). The baseline pathways have no phosphorus recovery, but they have phosphorus recycling in scenarios of land applications of the digested sewage sludge (i.e., in other scenarios, the digested sludge is either incinerated or landfilled). The defined scenarios represent local factors of resource recovery facilities. These local factors can potentially influence the “embodied” environmental impacts of the wastewater-derived phosphorus products.
While this study has a baseline pathway for both the WWTP system and the crop production system, a baseline is not a must for the crop production system because one may be more interested in absolute impacts (i.e., of using recovered products) instead of relative impacts (i.e., of substituting conventional fertilizers with recovered products).

Inventory Development Overview

The key steps of this life cycle inventory phase are (i) to use a plant-wide modeling simulation to develop water line, sludge line, and recovery line (WWTP) foreground inventories for the six RPs and associated baseline pathways (detailed in the following paragraphs), (ii) to use literature data to develop recovery line (post-WWTP) foreground inventories for the four ash-based RPs (RP3–RP6), (iii) to use literature data and the Ecoinvent database to develop the inventories for crop production systems under all pathways, and (iv) to connect the upstream WWTP system and the downstream crop production system. A detailed workflow can be found in Section S1 of the Supporting Information.
The life cycle inventory is based on a plant-wide modeling simulation using a modified version of the Benchmark Simulation Model No. 2 (BSM2-PSFe), (18) literature data, (16,31) and the Ecoinvent database (24) (Table 1).
Table 1. Overview of the Key Inventory
inventory category (Tables in the Supporting Information)key parameterssources
water and sludge lines (Tables S2–S4)energy use, chemical use, emissions to water, biogas yield, sludge yieldmodeling with BSM2-PSFe
recovery lines for RP1 and RP2 (Tables S2–S4)energy use, chemical use, recovery yieldmodeling with BSM2-PSFe
recovery lines for RP3, RP4, RP5, and RP6 (Tables S2–S4)energy use, chemical use, material use, recovery yieldliterature inventory
agronomic effectiveness (Table S5)phosphorus content, bioavailability factorliterature inventory
sludge disposal by incineration, landfill, and land application (Table S10)energy use, material use, emissions to soil, transportationliterature inventory
electricity supply with low, medium, or high GHG intensity (Table S11)electricity useEcoinvent database
crop production for maize, rice, and wheat (Table S6)substituted conventional fertilizersEcoinvent database
phosphate rock-based fertilizer supply (Table S11)consumption rateEcoinvent database
chemical and material supply (Table S11)consumption rateEcoinvent database

Water, Sludge, and Recovery Line Inventories

To model the dynamics of integrating phosphorus recovery into a WWTP, a plant-wide model was used. Plant-wide modeling and simulation is useful for evaluating the integration of resource recovery techniques in WWTPs. (32) In the literature, only a few LCA studies used plant-wide models to build their foreground inventories, (33) while most other LCA studies used static data from pilot-scale systems and multiple literature data sources. (34) Plant-wide modeling enables the exploration of many different recovery scenarios, the consideration of the interaction of recovery processes with the rest of the WWTPs, the analysis of the effects of recovery on the overall plant performance, and the monitoring of the effluent discharge level over the simulated period.
A modified version of BSM2-PSFe (18,35) was used to simulate the water line and the sludge line for the baseline pathways (BPn), the water line and the sludge line for all the RPs (RP1–RP6), and the recovery line (digester supernatant precipitation) for RP1 and RP2. BSM2 was designed for benchmarking the performance of WWTPs and testing control and operational strategies. BSM2-PSFe has the added capacity of modeling plant-wide phosphorus transformations. In this study, the results from steady-state simulations (1000 days) were used. The specific model outputs used for LCA include the electricity use; heating energy use; material use; biogas yield; struvite/Ca–P yield; sludge yield; and effluent P, N, and COD contents under various scenarios (i.e., influent pollutant concentration) and pathways (i.e., baseline, RP1 with struvite precipitation, RP2 with Ca–P precipitation, and RP4 and RP6 with CEPT). Since BSM2-PSFe does not model the downstream sludge disposal process, the recovery line for RP3–RP6 (sludge ash-based) was separately modeled with inventory from the literature. (15)

Other Inventories

The other key inventories include the maize grain production, rice (non-basmati) production, wheat grain production, sewage sludge disposal, bioavailability factor of recovered phosphorus products, electricity supply with three levels of the GHG emission intensity, phosphate rock-based fertilizer, and chemical and material use. They (together with any other background inventory) are taken from Ecoinvent 3.6, except for land application of the sludge (26) and bioavailability of recovered phosphorus products. (15)

Impact on Nitrogen Pathways

The studied phosphorus RPs have direct and indirect impacts on nitrogen pathways. Struvite (RP1) contributes nitrogen nutrient directly for crop production, and it helps avoid a small fraction of conventional nitrogen fertilizers used (12–25% for the three crop production systems). On the other hand, since one-third of all the baseline scenarios include land application of the digested sludge (where nitrogen recycling occurs), reducing the amount of this sludge (RP1 and RP2) or directing all this sludge to incineration for ash-based phosphorus recovery (RP3–RP6) means more conventional nitrogen fertilizer is needed to compensate for less nitrogen recycling.

Impact Assessment

TRACI 2.1 was used as the impact assessment method. (26) In this study, we focused on assessing four impact categories─global warming potential, eutrophication potential, ecotoxicity potential, and acidification potential. They are impact categories that are most commonly assessed in wastewater-based nutrient recycling LCA studies. (11) The LCA results are presented as the changes in impacts compared to those in the baseline scenarios.

Sensitivity and Uncertainty

Sensitivity analysis is a common step in LCA for interpreting results and for identifying priorities for improved inventory data collection or impact assessment. (11) It can be performed by testing key scenario assumptions one at a time. (16) In this study, sensitivity analysis is partly embedded in the scenario modeling, where in each RP, we have a result set of 27 scenarios instead of a single deterministic result. In particular, it gives indications of how sensitive the results are to the three factors─influent pollutant concentration, sludge disposal method, and carbon intensity of grid electricity.
For uncertainty analysis, a Monte Carlo simulation was performed on the maize production system by propagating parameter uncertainties (Table S17). The uncertainty analysis result is presented as the probability of each resource RP having a lower impact potential than the baseline pathway. This resonates the objective of understanding whether applying the wastewater-derived phosphorus products would generally or conditionally lead to net environmental benefits or not. The uncertainty analysis is given in the Supporting Information.

Results

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Life Cycle Environmental Impacts of Applying Wastewater-Derived Phosphorus Products

The LCA results are presented as the changes of life cycle environmental impacts compared to the baseline pathways (Figure 2). We assessed four common life cycle impact categories─global warming potential, eutrophication potential, ecotoxicity potential, and acidification potential.
Substituting half of the conventional phosphate rock-based fertilizers originally used in maize, rice, and wheat production systems with wastewater-derived phosphorus products from RP1, RP2, RP3, and RP4 reduces the assessed life cycle environmental impacts of these production systems in most scenarios [e.g., RP1 (wheat): 4–7% reduction in global warming potential, RP2 (wheat): 31–91% reduction in eutrophication potential]. The magnitude of change varies across the three crops. For instance, applying the rhenania phosphate-like product from RP4 could lead to 1–3 and 1–5% reduction in global warming potential for maize and wheat production, respectively. Essentially, the magnitude of change depends on the relative contribution of the fertilizer toward the overall life cycle environmental impact of a production system (i.e., having greater impacts on maize and wheat production systems).
RP3, RP5, and RP6 would increase global warming potential in all scenarios, while RP3 and RP6 are mostly favorable for reducing eutrophication potential and acidification potential. For RP5, the benefits of avoiding a conventional phosphorus rock-based fertilizer [plus calcium chloride and iron(III) chloride as byproducts] cannot outweigh the burdens of chemical inputs (mostly hydrochloric acid) and additional heating energy use for the recovery process. RP3 is particularly unfavorable for ecotoxicity potential because of the presence of heavy metals in the rhenania phosphate-like product, leading to emissions to soil, while RP4 generates a larger quantity of biogas (than RP3) which offsets the ecotoxicity impact of heavy metals. The use of a large quantity of chemicals in the recovery processes of RP5 and RP6 leads to their high ecotoxicity.
Eutrophication potential is the only impact category that is reduced in almost all pathways and scenarios. Plant-wide modeling shows that phosphorus recovery reduces the phosphorus content in the effluent and, therefore, its emissions to water. The recovery action diverts the phosphorus flow from the effluent phase to the recovered products.

Influences of Local Factors on the Life Cycle Environmental Impacts

The three local factors assessed include (i) the level of pollutants in the influent at the WWTP, (ii) whether the digested sewage sludge is originally disposed by incineration, landfill, or land application, and (iii) the level of carbon intensity of local grid electricity. Within the RPs, some have higher variations of impacts across scenarios (Figure 3). Some of these higher-variation pathways include RP4 and RP6 in global warming potential, RP1 and RP2 in eutrophication potential, and RP4 and RP6 in ecotoxicity potential. They could be explained by exploring the life cycle inventory. In the cases of RP4 and RP6 in global warming potential, these two pathways have a greater net reduction in electricity use compared to other RPs. (They are therefore more sensitive to the level of the carbon intensity of local grid electricity.)

Figure 3

Figure 3. Changes in the global warming potential, eutrophication potential, ecotoxicity potential, and acidification potential in three different crop production systems after substituting half of the conventional phosphate rock-based fertilizers with wastewater-derived phosphorus products from six different RPs compared to the baseline pathway. Within a RP for a given crop, each dot is a scenario─one of the 27 combinations of the influent pollutant concentration, sludge disposal method, and carbon intensity of grid electricity. RP1: struvite from the digester supernatant; RP2: Ca–P from the digester supernatant; RP3 and RP4: rhenania phosphate-like product from the incinerated sludge ashes (RP4 with CEPT); RP5 and RP6: single superphosphate from the incinerated sludge ashes (RP6 with CEPT).

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Within some RPs, the clustered dots indicate that one of those three local factors strongly influences the life cycle environmental impacts (e.g., the three clusters of dots for the global warming potential of RP3, the three clusters of dots for the eutrophication potential of RP1) (Figure 3). The level of pollutants in the influent at the WWTP is a strong determining factor for the eutrophication impacts. The original sewage sludge disposal approach has a strong influence on all the studied impact categories because of the very different sludge final disposal systems (Table S10) and the significant reduction in the amount of sludge destined for disposal in the recovery scenarios (particularly ash-based recovery in RP3–RP6) compared to the baseline (Figures S2 and S3). In contrast, the carbon intensity of grid electricity has a relatively insignificant influence. The breakdown of scenario results shown in Figure 3 is tabulated in the Supporting Information (Tables S12–S17).
The assessed scenarios represent only some of the local factors that could potentially influence the life cycle environment impacts “embodied” in the wastewater-derived phosphorus products. The results clearly imply that without an understanding of the “production system” of the wastewater-derived phosphorus products, end users are not capable of accounting for the life cycle environmental impacts of using these products.

Comparison with Previous Studies

Previous studies have assessed the life cycle environmental impacts of integrating phosphorus recovery to WWTPs (process perspective) (33,36−38) and of producing wastewater-derived phosphorus products (product perspective). (14−16,39,40) The difference in system boundaries in these studies usually makes the results not directly comparable across studies. (11) Nevertheless, product perspective studies are more comparable to the current study because both the product perspective and end user perspective emphasize on the recovered phosphorus products in their scope.
Some RPs assessed in this study were evaluated from a product perspective in the literature. In general, the results are consistent with those from the literature. For struvite recovery (like in RP1), Amann et al. (14) showed that this liquid-phase recovery process leads to lower global warming potential (−0.5 to −1.4 kgCO2eq/PE/a) and acidification potential (−5.4 to −11.5 gSO2eq/PE/a) compared to those of a reference system without phosphorus recovery and with mono-incineration of the sewage sludge (i.e., in our study, −0.0052 to −0.0096 kgCO2eq/ 1 kg maize and −0.044 to −0.071 gSO2eq/ 1 kg maize). In addition, Amann et al. (14) showed that Ca–P recovery (like in RP2) has higher global warming potential and acidification potential than the reference system. Linderholm et al. (39) suggested that an ash-based recovered phosphorus product (like in RP3) has a much higher global warming potential than the precipitated struvite (like in RP1). Tonini et al. (16) assessed a range of phosphorus recovery approaches from waste feedstock, including the recovery from municipal sewage sludge ashes as a rhenania phosphate-like product (like in RP3 and RP4) and single superphosphate (like in RP5 and RP6). Their study suggested that both products have a lower global warming potential, and a rhenania phosphate-like product has higher ecotoxicity compared to that of rock phosphate, while other impact categories are similar between these products and rock phosphate.

Discussion

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Resource Recovery Implications of LCA with Different Perspectives

LCAs of wastewater-based resource recovery could generally be categorized as the process perspective, the product perspective, and the end-user perspective (Figure 1). The process perspective (also called the waste management perspective) evaluates the integration of resource recovery processes into conventional WWTPs. This perspective often aims to quantify and optimize the influence of resource recovery processes on the overall environmental performance of WWTPs. The focus is on the primary functionality of wastewater treatment and sludge disposal. The product perspective shifts attention from WWTPs to wastewater-derived products. This perspective often aims to evaluate and compare potential environmental impacts of the wastewater-derived products derived from different recovery approaches. The end-user perspective extends on the product perspective. It centers on how the application of wastewater-derived products impacts the overall environmental performance of the end users’ product system (i.e., in this study, the end user is the agricultural sector using wastewater-derived phosphorus products). One major difference between the product perspective and the end-user perspective is that the product perspective typically credits the recovered phosphorus products for avoiding an assumed conventional phosphate-rocked fertilizer production, while the end-user perspective only implicitly considers this when there is a baseline of using a conventional fertilizer (i.e., it is not considered for a new crop production system).
This study demonstrates the application of the end-user perspective for developing a life cycle inventory and to conduct LCAs of “downstream” product systems that utilize wastewater-derived products as inputs. The end-user perspective can serve three major purposes.

Complementing with Process and Product Perspectives

The end-user perspective can complement with the process perspective and the product perspective to give a more holistic picture of environmental impacts along the “circular economy value chains” of wastewater-based resource recovery. For WWTPs or water resource recovery facilities (WRRFs), phosphorus recovery (like any other resource recovery) can be a trade-off between recovery efficiency, environmental impacts, and economic revenues from the final products. (41) The process/product perspective LCAs help WRRFs understand part of this trade-off.
On the other hand, the end users of wastewater-derived products are concerned with how the application of wastewater-derived products would influence the overall economic and environmental impacts of their product systems. The end-user perspective LCAs of wastewater-based resource recovery can be performed to address the environmental concern. To realize the total value of phosphorus recovery (and other forms of resource recovery as well), end users must be considered early in the process. (7) By engaging end users in the early stage, WRRFs will also benefit from having access to better downstream inventories to improve the quality of their process/product perspective LCAs. Ultimately, conducting a LCA with these three perspectives (i.e., three types of functional units) on the same system encompassing both the WRRF (i.e., producer) and the end user (i.e., consumer) can enable a more holistic understanding of the environmental consequences of resource recovery. It is because the end-user perspective could be used to answer different questions such as what could be the impacts of using these recovered phosphorus products instead of conventional phosphate rock-based fertilizers? How much would this recovered phosphorus product contribute to the environmental benefit or burden of my crop production system?

Understanding Systemwide Impacts of Using Wastewater-Derived Products

The end-user perspective is essential to evaluate systemwide environmental impacts of wide uptake of wastewater-derived products at downstream product systems. This type of evaluation cannot be achieved from the process/product perspective because WRRFs would mostly have limited information on which downstream inputs (e.g., conventional fertilizers) would eventually be substituted by the wastewater-derived products (e.g., wastewater-derived phosphorus products). In addition, end users would likely to have better knowledge on the expected or actual performance and the limitations of these wastewater-derived phosphorus products.
LCA has been widely used for assessing environmental impacts of producing different agricultural commodities. The use of fertilizers and nutrient losses (P and N) are major contributors to environmental impacts. (42) There are limited wastewater-derived product life cycle inventories that are transparent enough and directly useable by the agricultural sector. Using the end-user perspective could ensure that wastewater-derived product life cycle inventories are built with the end user in mind.
This study shows that all the studied RPs would reduce the amount of the sludge that was originally destined for landfill, incineration, or land application. As we modeled the baseline of sludge disposal in this study, the shift in the fate of the sludge has consequentially contributed to the results significantly. The fate of waste is not typically considered in the product perspective LCA. In order to better understand the systemwide impacts of circular economy, a better consideration of the fate of waste is needed.

Drawing More Attention to Long-Term Impacts and Effectiveness

The end-user perspective has an advantage of drawing more attention to the need of understanding the long-term environmental impacts and agronomic effectiveness of applying wastewater-derived phosphorus products (e.g., soil context, (43) phosphorus uptake, (21) and contaminants (44)). This long-term emission and effectiveness of these products is an important inventory, as identified by some field studies. (21,45) As more wastewater-derived products are made available, it becomes more important to understand the environmental impacts of the “use phase” and the “disposal phase” (for some type of products) of these products, instead of only the “production phase” that the process/product perspective focused on.

Future Outlook

Despite the value of end-user perspective LCA, it remains challenging for end users to derive inventories for the wastewater-derived products they use. This study shows that the LCA results can be sensitive to local factors of resource recovery facilities. For example, when the sewage sludge is diverted to mono-incineration for ash-based phosphorus recovery, the original destination of sludge disposal (i.e., landfill, incineration, or land application) can influence the results substantially. Other local factors such as the facility scale (10,46) and recovered product transport distance (47) are also potentially influential. Without a thorough understanding of the “upstream” resource recovery facility and the baseline system, the end users cannot robustly quantify the environmental impacts of their decision on using wastewater-derived products. This is especially critical when the original inputs to be substituted contribute a significant portion of life cycle environmental impacts of the end user’s product system. Therefore, WRRFs need to build transparent inventories in a way that is also useable by the end user.
Future LCA studies of the end-user perspective on phosphorus recovery can consider four areas of advancement. First, they can consider scenarios for which multiple wastewater-derived phosphorus products and other recovered products are produced. Second, they can address the data gap in the long-term crop-specific field performance (e.g., agronomic effectiveness and phosphorus leaching) of wastewater-derived phosphorus products to improve the overall quality of the life cycle inventory. (21,45) Third, national average maize, rice, and wheat production systems in the U.S. were used directly from the Ecoinvent database without any modifications. LCA of an actual crop production system using wastewater-derived phosphorus products would be very valuable. Fourth, while this study used a consequential approach (27) in developing the life cycle inventory, the end-user perspective does not constraint the choice of the LCA approach. Attributional approaches with different allocation methods could be tested for developing the inventory (e.g., without “zero burden assumption” for waste feedstock (47,48) or partitioning (49)).

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.2c00353.

  • Detailed method; life cycle inventory; impact assessment results; uncertainty analysis; and sensitivity analysis (PDF)

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Author Information

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  • Corresponding Author
  • Authors
    • Kimberly Solon - BioCo Research Group, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, Gent 9000, Belgium
    • Mingsheng Jia - BioCo Research Group, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, Gent 9000, Belgium;  Orcidhttps://orcid.org/0000-0002-5838-2262
    • Eveline I. P. Volcke - BioCo Research Group, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, Gent 9000, Belgium;  Orcidhttps://orcid.org/0000-0002-7664-7033
    • Jan Peter van der Hoek - Department of Water Management, Delft University of Technology, Stevinweg 1, Delft 2628 CN, The Netherlands;  Waternet, Korte Ouderkerkerdijk 7, Amsterdam 1096 AC, The Netherlands;  Orcidhttps://orcid.org/0000-0002-0674-388X
  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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K.L.L. and K.S. acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement nos. 707404 and 846316, respectively.

References

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This article references 49 other publications.

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    Human intervention in the global P cycle has mobilized nearly half a billion tons of the element from phosphate rock into the hydrosphere over the past half century. The resultant water pollution concerns have been the main driver for sustainable P use (including P recovery). However the emerging global challenge of P scarcity with serious implications for future food security, means P will also need to be recovered for productive reuse as a fertilizer in food prodn. to replace increasingly scarce and more expensive phosphate rock. Through an integrated and systems framework, this paper examines the full spectrum of sustainable P recovery and reuse options (from small-scale low-cost to large-scale high-tech.), facilitates integrated decision-making and identifies future opportunities and challenges for achieving global P security. Case studies are provided rather than focusing on a specific technol. or process. There is no single soln. to achieving a P-secure future: in addn. to increasing P use efficiency, P will need to be recovered and reused from all current waste streams throughout the food prodn. and consumption system (from human and animal excreta to food and crop wastes). There is a need for new sustainable policies, partnerships and strategic frameworks to develop renewable P fertilizer systems for farmers. Further research is also required to det. the most sustainable means in a given context for recovering P from waste streams and converting the final products into effective fertilizers, accounting for life cycle costs, resource and energy consumption, availability, farmer accessibility and pollution.
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    Melia, P. M.; Cundy, A. B.; Sohi, S. P.; Hooda, P. S.; Busquets, R. Trends in the recovery of phosphorus in bioavailable forms from wastewater. Chemosphere 2017, 186, 381– 395,  DOI: 10.1016/j.chemosphere.2017.07.089
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    Addressing food security issues arising from phosphorus (P) scarcity is described as one of the greatest global challenges of the 21st century. Dependence on inorg. phosphate fertilizers derived from limited geol. sources of P creates an urgent need to recover P from wastes and treated waters, in safe forms that are also effective agriculturally - the established process of P removal by chem. pptn. using Fe or Al salts, is effective for P removal but leads to residues with limited bioavailability and contamination concerns. One of the greatest opportunities for P recovery is at wastewater treatment plants (WWTPs) where the crystn. of struvite and Ca-P from enhanced biol. P removal (EBPR) sludge is well developed and already shown to be economically and operationally feasible in some WWTPs. However, recovery through this approach can be limited to <25% efficiency unless chem. extn. is applied. Thermochem. treatment of sludge ash produces detoxified residues that are currently utilized by the fertilizer industry; wet chem. extn. can be economically feasible in recovering P and other byproducts. The bioavailability of recovered P depends on soil pH as well as the P-rich material in question. Struvite is a superior recovered P product in terms of plant availability, while use of Ca-P and thermochem. treated sewage sludge ash is limited to acidic soils. These technologies, in addn. to others less developed, will be com. pushed forward by revised fertilizer legislation and foreseeable legislative limits for WWTPs to achieve discharges of <1 mg P/L.
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    Rufí-Salís, M.; Brunnhofer, N.; Petit-Boix, A.; Gabarrell, X.; Guisasola, A.; Villalba, G. Can wastewater feed cities? Determining the feasibility and environmental burdens of struvite recovery and reuse for urban regions. Sci. Total Environ. 2020, 737, 139783,  DOI: 10.1016/j.scitotenv.2020.139783
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    Phosphorus (P) resources are decreasing at an alarming rate due to global fertilizer use and insufficient nutrient recovery strategies. Currently, more circular approaches are promoted, such as recovering P from wastewater in the form of struvite. This is esp. attractive for urban areas, where there is a growing trend of local crop prodn. and large vols. of wastewater are treated in centralized wastewater treatment plants (WWTPs). This research aims to assess the tech. and environmental feasibility of applying a struvite recovery and reuse strategy to meet the P requirements to fertilize the agricultural fields of an urban region. To do so, we analyze the potential P recovery and the environmental impacts of integrating three recovery technologies (REM-NUT, Ostara and AirPrex) in the two biggest WWTPs of the Area Metropolitana de Barcelona. The results show that all technologies are able to recover between 5 and 30 times the amt. of P required to fertilize the agricultural area of the region annually (36.5 t). As can be expected, including P recovery technologies result in addnl. impacts per m3 of wastewater due to increased electricity consumption and chems. required for the struvite pptn. However, struvite recovery results in less eutrophication potential, esp. in the REM-NUT case, with an av. redn. of 5.4 times. On the other hand, Ostara, that recovers P from the digestate, had the lowest impacts (9 kgCO2eq/kgP), even compared to the prodn. of mineral.
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    In the modern economy, international value chains-prodn., use, and disposal of goods-have global environmental impacts. Life Cycle Assessment (LCA) aims to track these impacts and assess them from a systems perspective, identifying strategies for improvement without burden shifting. We review recent developments in LCA, including existing and emerging applications aimed at supporting environmentally informed decisions in policy-making, product development and procurement, and consumer choices. LCA constitutes a viable screening tool that can pinpoint environmental hotspots in complex value chains, but we also caution that completeness in scope comes at the price of simplifications and uncertainties. Future advances of LCA in enhancing regional detail and accuracy as well as broadening the assessment to economic and social aspects will make it more relevant for producers and consumers alike.
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    The environmental benefits and burdens of phosphorus recovery in four centralized and two decentralized municipal wastewater systems were compared using life cycle assessment (LCA). In centralized systems, phosphorus recovered as struvite from the solids dewatering liq. resulted in an environmental benefit except for the terrestrial ecotoxicity and freshwater eutrophication impact categories, with power and chem. use offset by operational savings and avoided fertilizer prodn. Chem.-based phosphorus recovery, however, generally required more resources than were offset by avoided fertilizers, resulting in a net environmental burden. In decentralized systems, phosphorus recovery via urine source sepn. reduced the global warming and ozone depletion potentials but increased terrestrial ecotoxicity and salinization potentials due to application of untreated urine to land. Overall, mineral depletion and eutrophication are well-documented arguments for phosphorus recovery; however, phosphorus recovery does not necessarily present a net environmental benefit. While avoided fertilizer prodn. does reduce potential impacts, phosphorus recovery does not necessarily offset the resources consumed in the process. LCA results indicate that selection of an appropriate phosphorus recovery method should consider both local conditions and other environmental impacts, including global warming, ozone depletion, toxicity, and salinization, in addn. to eutrophication and mineral depletion impacts.
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    Solon, K.; Flores-Alsina, X.; Kazadi Mbamba, C.; Ikumi, D.; Volcke, E. I. P.; Vaneeckhaute, C.; Ekama, G.; Vanrolleghem, P. A.; Batstone, D. J.; Gernaey, K. V.; Jeppsson, U.
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    The objective of this paper is to report the effects that control/operational strategies may have on plant-wide phosphorus (P) transformations in wastewater treatment plants (WWTP). The development of a new set of biol. (activated sludge, anaerobic digestion), physico-chem. (aq. phase, pptn., mass transfer) process models and model interfaces (between water and sludge line) were required to describe the required tri-phasic (gas, liq., solid) compd. transformations and the close interlinks between the P and the sulfur (S) and iron (Fe) cycles. A modified version of the Benchmark Simulation Model No. 2 (BSM2) (open loop) is used as test platform upon which three different operational alternatives (A1, A2, A3) are evaluated. Rigorous sensor and actuator models are also included in order to reproduce realistic control actions. Model-based anal. shows that the combination of an ammonium (SNHX) and total suspended solids (XTSS) control strategy (A1) better adapts the system to influent dynamics, improves phosphate (SPO4) accumulation by phosphorus accumulating organisms (XPAO) (41%), increases nitrification/denitrification efficiency (18%) and reduces aeration energy (Eaeration) (21%). The addn. of iron (XFeCl3) for chem. P removal (A2) promotes the formation of ferric oxides (XHFO-H, XHFO-L), phosphate adsorption (XHFO-H,P, XHFO-L,P), co-pptn. (XHFO-H,P,old, XHFO-L,P,old) and consequently reduces the P levels in the effluent (from 2.8 to 0.9 g P.m-3). This also has an impact on the sludge line, with hydrogen sulfide prodn. (GH2S) reduced (36%) due to iron sulfide (XFeS) pptn. As a consequence, there is also a slightly higher energy prodn. (Eproduction) from biogas. Lastly, the inclusion of a stripping and crystn. unit (A3) for P recovery reduces the quantity of P in the anaerobic digester supernatant returning to the water line and allows potential struvite (XMgNH4PO4) recovery ranging from 69 to 227 kg.day-1 depending on: (1) airflow (Qstripping); and, (2) magnesium (QMg(OH)2) addn. All the proposed alternatives are evaluated from an environmental and economical point of view using appropriate performance indexes. Finally, some deficiencies and opportunities of the proposed approach when performing (plant-wide) wastewater treatment modeling/engineering projects are discussed.
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    Hertzberger, A. J.; Cusick, R. D.; Margenot, A. J. Maize and soybean response to phosphorus fertilization with blends of struvite and monoammonium phosphate. Plant Soil 2021, 461, 547– 563,  DOI: 10.1007/s11104-021-04830-2
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    Maize and soybean response to phosphorus fertilization with blends of struvite and monoammonium phosphate
    Hertzberger, Allan J.; Cusick, Roland D.; Margenot, Andrew J.
    Plant and Soil (2021), 461 (1-2), 547-563CODEN: PLSOA2; ISSN:0032-079X. (Springer)
    Struvite (MgNH4PO4·6H2O), a low water soly. (<3%) mineral that is increasingly recovered from wastewater treatment plants, has potential to be used as a slow release ammonium phosphate fertilizer, esp. when blended with highly water sol. phosphorus (P) fertilizers such as monoammonium phosphate (MAP). Maize and soybean were fertilized using a gradient of struvite substitution for MAP, entailing five struvite: MAP blends in a factorial combination with struvite granule size (1.5, 3.0 mm diam.) and fertilizer placement (incorporation, banding). Crop biomass, and P and N uptake (total, concn.) were used to evaluate crop response, and post-harvest soil Mehlich-3 P was measured to assess sol. P loss risk. Maize biomass response was similar using up to 50% struvite and similar in soybean using up to 25% struvite. Total P uptake by maize was similar across 0-75% struvite blends, but significantly lower for 100% struvite. Maize apparent fertilizer P uptake and apparent fertilizer P uptake efficiency was greatest for 100% MAP. Despite differences in biomass, soybean apparent fertilizer P uptake and apparent P use efficiency were similar across struvite blends. Soybean P uptake was significantly greater when fertilized with 100% struvite than with 25 and 50% struvite. Inverse correlation of plant P and N concns. with biomass indicated a biomass diln. effect. Residual soil Mehlich-3 P decreased with increasing struvite substitution of MAP. Struvite:MAP blends (25-50% struvite) appear to lower sol. P loss risk compared to MAP without restricting early season (vegetative) growth of maize and soybean, and this can differ by crop species.
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    Anderson, R. S. Struvite Behavior and Effects as a Fertilizer-Phosphorus Source Among Arkansas Soils; University of Arkansas, 2020.
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    Effect of various types of thermochemical processing of sewage sludges on phosphorus speciation, solubility, and fertilization performance
    Steckenmesser, Daniel; Vogel, Christian; Adam, Christian; Steffens, Diedrich
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    Sewage sludge has one of the highest phosphorus (P) recovery potentials of all waste materials. Therefore, P-recycling from sewage sludge could contribute to closing the P-cycle. Recently, various thermal processes for P-recovery have been developed, but there is still a demand for information on the effect of different process parameters (e.g. additives and temp.) on P-speciation and esp. on the fertilization performance. In the present study, two common methods (low-temp. conversion at 400-500°C and thermochem. treatment at 950°C) were investigated and combined to produce highly bioavailable P-fertilizers from two different types of sewage sludge based on chem. phosphorus pptn. (Chem-P) and enhanced biol. phosphorus removal (Bio-P). The results of P-fractionation, X-ray diffraction anal., and pot expts. with maize showed that Bio-P sludges attain high P-plant-availability after treatment at low temps. (400°C). In contrast, Chem-P sludges can adequately be treated at higher temps. under reductive conditions with sodium additives to form highly bioavailable calcium-sodium-phosphate. Addnl., also highly heavy-metal contaminated sludges can be thermochem. treated at high temps. to achieve the legal requirements for fertilizers.
  23. 23
    Muys, M.; Phukan, R.; Brader, G.; Samad, A.; Moretti, M.; Haiden, B.; Pluchon, S.; Roest, K.; Vlaeminck, S. E.; Spiller, M. A systematic comparison of commercially produced struvite: Quantities, qualities and soil-maize phosphorus availability. Sci. Total Environ. 2021, 756, 143726,  DOI: 10.1016/j.scitotenv.2020.143726
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    23
    A systematic comparison of commercially produced struvite: Quantities, qualities and soil-maize phosphorus availability
    Muys, Maarten; Phukan, Rishav; Brader, Gunter; Samad, Abdul; Moretti, Michele; Haiden, Barbara; Pluchon, Sylvain; Roest, Kees; Vlaeminck, Siegfried E.; Spiller, Marc
    Science of the Total Environment (2021), 756 (), 143726CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
    Prodn. of struvite (MgNH4PO4·6H2O) from waste streams is increasingly implemented to recover phosphorus (P), which is listed as a crit. raw material in the European Union (EU). To facilitate EU-wide trade of P-contg. secondary raw materials such as struvite, the EU issued a revised fertilizer regulation in 2019. A comprehensive overview of the supply of struvite and its quality is presently missing. This study aimed: (i) to det. the current EU struvite prodn. vols., (ii) to evaluate all legislated physicochem. characteristics and pathogen content of European struvite against newly set regulatory limits, and (iii) to compare not-regulated struvite characteristics. It is estd. that in 2020, between 990 and 1250 ton P are recovered as struvite in the EU. Struvite from 24 European prodn. plants, accounting for 30% of the 80 struvite installations worldwide was sampled. Three samples failed the physicochem. legal limits; one had a P content of <7% and three exceeded the org. carbon content of 3% dry wt. (DW). Mineralogical anal. revealed that six samples had a struvite content of 80-90% DW, and 13 samples a content of >90% DW. All samples showed a heavy metal content below the legal limits. Microbiol. analyses indicated that struvite may exceed certain legal limits. Differences in morphol. and particle size distribution were obsd. for struvite sourced from digestate (rod shaped; transparent; 82 mass% < 1 mm), dewatering liquor (spherical; opaque; 65 mass% 1-2 mm) and effluent from upflow anaerobic sludge blanket reactor processing potato wastewater (spherical; opaque; 51 mass% < 1 mm and 34 mass% > 2 mm). A uniform soil-plant P-availability pattern of 3.5-6.5 mg P/L soil/d over a 28 days sampling period was obsd. No differences for plant biomass yield were obsd. In conclusion, the results highlight the suitability of most struvite to enter the EU fertilizer market.
  24. 24
    Wernet, G.; Bauer, C.; Steubing, B.; Reinhard, J.; Moreno-Ruiz, E.; Weidema, B. The ecoinvent database version 3 (part I): overview and methodology. Int. J. Life Cycle Assess. 2016, 21, 1218– 1230,  DOI: 10.1007/s11367-016-1087-8
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    Miller-Robbie, L.; Ulrich, B. A.; Ramey, D. F.; Spencer, K. S.; Herzog, S. P.; Cath, T. Y.; Stokes, J. R.; Higgins, C. P. Life cycle energy and greenhouse gas assessment of the co-production of biosolids and biochar for land application. J. Cleaner Prod. 2015, 91, 118– 127,  DOI: 10.1016/j.jclepro.2014.12.050
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    Life cycle energy and greenhouse gas assessment of the co-production of biosolids and biochar for land application
    Miller-Robbie, Leslie; Ulrich, Bridget A.; Ramey, Dotti F.; Spencer, Kathryn S.; Herzog, Skuyler P.; Cath, Tzahi Y.; Stokes, Jennifer R.; Higgins, Christopher P.
    Journal of Cleaner Production (2015), 91 (), 118-127CODEN: JCROE8; ISSN:0959-6526. (Elsevier Ltd.)
    The co-prodn. and co-application to land of biochar and biosolids may make conventional wastewater treatment more sustainable; therefore, this study provides a first life cycle evaluation of the co-location of a pyrolysis (biochar prodn.) plant with a municipal wastewater treatment plant. Life cycle energy use and greenhouse gas emissions are evaluated for the co-prodn. of these two materials. Three US national scenarios are included: biosolids only produced and disposed of as is the current common practice in the US (landfilled, incinerated, and land applied); biosolids only produced but not land applied; and co-prodn. of biosolids and biochar and their disposal as currently practiced. A case study is also presented with slightly different disposal practices. Large contributors to life cycle greenhouse gas emissions are from the disposal of biosolids in landfills and incinerators, making alternatives like land application attractive for mitigating greenhouse gas emissions. The addn. of biochar prodn. adds little to the overall energy use but provides substantial (26%) redn. in greenhouse gas emissions for the national case, largely due to the recalcitrant carbon storage in biochar. Because biochar prodn. is an energy pos. process, incorporation of the energy co-products into the plant is explored for producing high quality Class A biosolids. The addn. of biochar to biosolids is shown to be more sustainable from a co-prodn. standpoint. This study contributes a benchmark anal. in evaluating the co-prodn. of biochar and biosolids for potential environmental, economic, and health benefits and the results are useful for utility planning.
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    Bare, J. TRACI 2.0: The tool for the reduction and assessment of chemical and other environmental impacts 2.0. Clean Technol. Environ. Policy 2011, 13, 687– 696,  DOI: 10.1007/s10098-010-0338-9
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    TRACI 2.0: the tool for the reduction and assessment of chemical and other environmental impacts 2.0
    Bare, Jane
    Clean Technologies and Environmental Policy (2011), 13 (5), 687-696CODEN: CTEPAI; ISSN:1618-954X. (Springer)
    A review with 85 refs. TRACI 2.0, the Tool for the Redn. and Assessment of Chem. and other environmental Impacts 2.0, has been expanded and developed for sustainability metrics, life cycle impact assessment, industrial ecol., and process design impact assessment for developing increasingly sustainable products, processes, facilities, companies, and communities. TRACI 2.0 allows the quantification of stressors that have potential effects, including ozone depletion, global warming, acidification, eutrophication, tropospheric ozone (smog) formation, human health criteria-related effects, human health cancer, human health noncancer, ecotoxicity, and fossil fuel depletion effects. Research is going on to quantify the use of land and water in a future version of TRACI. The original version of TRACI released in August 2002 (Bare et al. J Ind Ecol 6:49-78, 2003) has been used in many prestigious applications including: the US Green Building Council's LEED Certification (US Green Building Council, Welcome to US Green Building Council, 2008), the National Institute of Stds. and Technol.'s BEES (Building for Environment and Economic Sustainability) (Lippiatt, BEES 4.0: building for environmental and economic sustainability tech. manual and user guide, 2007) which is used by US EPA for Environmentally Preferable Purchasing (US Environmental Protection Agency, Environmentally Preferable Purchasing (EPP), 2008d), the US Marine Corps' EKAT (Environmental Knowledge and Assessment Tool) for military and nonmilitary uses (US Marine Corps, Environmental knowledge and assessment tool (EKAT): first time user's guide, 2007), and within numerous college curriculums in engineering and design departments.
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    Finnveden, G.; Hauschild, M. Z.; Ekvall, T.; Guinée, J.; Heijungs, R.; Hellweg, S.; Koehler, A.; Pennington, D.; Suh, S. Recent developments in Life Cycle Assessment. J. Environ. Manage. 2009, 91, 1– 21,  DOI: 10.1016/j.jenvman.2009.06.018
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    Recent developments in Life Cycle Assessment
    Finnveden Goran; Hauschild Michael Z; Ekvall Tomas; Guinee Jeroen; Heijungs Reinout; Hellweg Stefanie; Koehler Annette; Pennington David; Suh Sangwon
    Journal of environmental management (2009), 91 (1), 1-21 ISSN:.
    Life Cycle Assessment is a tool to assess the environmental impacts and resources used throughout a product's life cycle, i.e., from raw material acquisition, via production and use phases, to waste management. The methodological development in LCA has been strong, and LCA is broadly applied in practice. The aim of this paper is to provide a review of recent developments of LCA methods. The focus is on some areas where there has been an intense methodological development during the last years. We also highlight some of the emerging issues. In relation to the Goal and Scope definition we especially discuss the distinction between attributional and consequential LCA. For the Inventory Analysis, this distinction is relevant when discussing system boundaries, data collection, and allocation. Also highlighted are developments concerning databases and Input-Output and hybrid LCA. In the sections on Life Cycle Impact Assessment we discuss the characteristics of the modelling as well as some recent developments for specific impact categories and weighting. In relation to the Interpretation the focus is on uncertainty analysis. Finally, we discuss recent developments in relation to some of the strengths and weaknesses of LCA.
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    De-Bashan, L. E.; Bashan, Y. Recent advances in removing phosphorus from wastewater and its future use as fertilizer (1997-2003). Water Res. 2004, 38, 4222– 4246,  DOI: 10.1016/j.watres.2004.07.014
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    Recent advances in removing phosphorus from wastewater and its future use as fertilizer (1997-2003)
    de-Bashan, Luz E.; Bashan, Yoav
    Water Research (2004), 38 (19), 4222-4246CODEN: WATRAG; ISSN:0043-1354. (Elsevier B.V.)
    A review. Large quantities of phosphate present in wastewater is one of the main causes of eutrophication that neg. affects many natural water bodies, both fresh water and marine. It is desirable that water treatment facilities remove phosphorus from the wastewater before they are returned to the environment. Total removal or at least a significant redn. of phosphorus is obligatory, if not always fulfilled, in most countries. This comprehensive review summarizes the current status in phosphorus-removal technologies from the most common approaches, like metal pptn., constructed wetland systems, adsorption by various microorganisms either in a free state or immobilized in polysaccharide gels, to enhanced biol. phosphorus removal using activated sludge systems, and several innovative engineering solns. As chem. pptn. renders the ppts. difficult, if not impossible, to recycle in an economical industrial manner, biol. removal opens opportunities for recovering most of the phosphorus and beneficial applications of the product. This review includes the options of struvite (ammonium magnesium phosphate) and hydroxyapatite formation and other feasible options using, the now largely regarded contaminant, phosphorus in wastewater, as a raw material for the fertilizer industry. Besides updating our knowledge, this review critically evaluates the advantage and difficulties behind each treatment and indicates some of the most relevant open questions for future research.
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    Cornel, P.; Schaum, C. Phosphorus recovery from wastewater: Needs, technologies and costs. Water Sci. Technol. 2009, 59, 1069– 1076,  DOI: 10.2166/wst.2009.045
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    Phosphorus recovery from wastewater: needs, technologies and costs
    Cornel, P.; Schaum, C.
    Water Science and Technology (2009), 59 (6), 1069-1076CODEN: WSTED4; ISSN:0273-1223. (IWA Publishing)
    A review. Phosphorus is an essential, yet limited resource, which cannot be replaced by any other element. This is why there are increasing efforts to recycle phosphorus contained in wastewater. It involves the recovery of phosphorus and, normally, the sepn. of phosphates from harmful substances. Phosphorus can be recovered from wastewater, sewage sludge, as well as from the ash of incinerated sewage sludge, and can be combined with phosphorus removal in most cases. The phosphorus recovery rate from the liq. phase can reach 40 to 50% at the most, while recovery rates from sewage sludge and sewage sludge ash can reach up to 90%. There are various methods which can be applied for phosphorus recovery. Up to now, there is limited experience in industrial-scale implementation. The costs for recovered phosphate exceed the costs for phosphate from rock phosphate by several times. For German conditions, the specific addnl. costs of wastewater treatment by integrating phosphorus recovery can be estd. at euro2-6 per capita and year.
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    Solon, K.; Lam, K. L.; Jia, M.; Volcke, E. I. P. Benchmarking of phosphorus recovery strategies from wastewater. In preparation.
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    Alanya, S.; Dewulf, J.; Duran, M. Comparison of Overall Resource Consumption of Biosolids Management System Processes Using Exergetic Life Cycle Assessment. Environ. Sci. Technol. 2015, 49, 9996– 10006,  DOI: 10.1021/acs.est.5b03124
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    Comparison of overall resource consumption of biosolids management system processes using exergetic life cycle assessment
    Alanya, Sevda; Dewulf, Jo; Duran, Metin
    Environmental Science & Technology (2015), 49 (16), 9996-10006CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    This study focused on the evaluation of biosolids management systems (BMS) from a natural resource consumption point of view. Addnl., the environmental impact of the facilities was benchmarked using Life Cycle Assessment (LCA) to provide a comprehensive assessment. This is the first study to apply a Cumulative Exergy Extn. from the Natural Environment (CEENE) method for an in-depth resource use assessment of BMS where two full-scale BMS and seven system variations were analyzed. CEENE allows better system evaluation and understanding of how much benefit is achievable from the products generated by BMS, which have valorization potential. LCA results showed that environmental burden is mostly from the intense electricity consumption. The CEENE anal. further revealed that the environmental burden is due to the high consumption of fossil and nuclear-based natural resources. Using Cumulative Degree of Perfection, higher resource-use efficiency, 53%, was obsd. in the PTA-2 where alk. stabilization rather than anaerobic digestion is employed. However, an anaerobic digestion process is favorable over alk. stabilization, with 35% lower overall natural resource use. The most significant redn. of the resource footprint occurred when the output biogas was valorized in a combined heat and power system.
  32. 32
    Solon, K.; Volcke, E. I. P.; Spérandio, M.; Van Loosdrecht, M. C. M. Resource recovery and wastewater treatment modelling. Environ. Sci.: Water Res. Technol. 2019, 5, 631– 642,  DOI: 10.1039/c8ew00765a
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    Resource recovery and wastewater treatment modelling
    Solon, Kimberly; Volcke, Eveline I. P.; Sperandio, Mathieu; van Loosdrecht, Mark C. M.
    Environmental Science: Water Research & Technology (2019), 5 (4), 631-642CODEN: ESWRAR; ISSN:2053-1419. (Royal Society of Chemistry)
    Traditional wastewater treatment plants (WWTPs) are increasingly regarded as water resource recovery facilities (WRRFs), reflecting the value of water, nutrients, energy and other resources, besides ensuring the required effluent quality. Resource recovery techniques involve biochem., phys. and physico-chem. processes, and even previously unexploited biol. conversions. Biopolymer and bioplastic prodn. also reveal the remarkable potential present in our microbial cultures. Models have demonstrated their usefulness to optimize WWTP operation to achieve better effluent quality at lower costs; they also constitute a useful tool to support the transition of WWTPs into WRRFs that maximize the valorization of products recovered from wastewater. In this paper, the extent to which the new techniques and unit processes applied for resource recovery could be modelled with conventional activated sludge models (ASMs) and addnl. modeling challenges being faced are discussed while providing recommendations of potential approaches to address current modeling research gaps.
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    Bisinella de Faria, A. B.; Spérandio, M.; Ahmadi, A.; Tiruta-Barna, L. Evaluation of new alternatives in wastewater treatment plants based on dynamic modelling and life cycle assessment (DM-LCA). Water Res. 2015, 84, 99– 111,  DOI: 10.1016/j.watres.2015.06.048
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    Evaluation of new alternatives in wastewater treatment plants based on dynamic modelling and life cycle assessment (DM-LCA)
    Bisinella de Faria, A. B.; Sperandio, M.; Ahmadi, A.; Tiruta-Barna, L.
    Water Research (2015), 84 (), 99-111CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
    With a view to quantifying the energy and environmental advantages of Urine Source-Sepn. (USS) combined with different treatment processes, five wastewater treatment plant (WWTP) scenarios were compared to a ref. scenario using Dynamic Modeling (DM) and Life Cycle Assessment (LCA), and an integrated DM-LCA framework was thus developed. Dynamic simulations were carried out in BioWin in order to obtain a realistic evaluation of the dynamic behavior and performance of plants under perturbation. LCA calcns. were performed within Umberto using the Ecoinvent database. A Python interface was used to integrate and convert simulation data and to introduce them into Umberto to achieve a complete LCA evaluation comprising foreground and background processes. Comparisons between steady-state and dynamic simulations revealed the importance of considering dynamic aspects such as nutrient and flow peaks. The results of the evaluation highlighted the potential of the USS scenario for nutrient recovery whereas the Enhanced Primary Clarification (EPC) scenario gave increased biogas prodn. and also notably decreased aeration consumption, leading to a pos. energy balance. Both USS and EPC scenarios also showed increased stability of plant operation, with smaller daily avs. of total nitrogen and phosphorus. In this context, USS and EPC results demonstrated that the coupled USS + EPC scenario and its combinations with agricultural spreading of N-rich effluent and nitritation/anaerobic deammonification could present an energy-pos. balance with resp. 27% and 33% lower energy requirements and an increase in biogas prodn. of 23%, compared to the ref. scenario. The coupled scenarios also presented lesser environmental impacts (redn. of 31% and 39% in total endpoint impacts) along with effluent quality well within the specified limits. The marked environmental performance (redn. of global warming) when nitrogen is used in agriculture shows the importance of future research on sustainable solns. for nitrogen recovery. The contribution anal. of midpoint impacts also showed hotspots that it will be important to optimize further, such as plant infrastructure and direct N2O emissions.
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    Sena, M.; Hicks, A. Life cycle assessment review of struvite precipitation in wastewater treatment. Resour., Conserv. Recycl. 2018, 139, 194– 204,  DOI: 10.1016/j.resconrec.2018.08.009
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    Flores-Alsina, X.; Solon, K.; Kazadi Mbamba, C.; Tait, S.; Gernaey, K. V.; Jeppsson, U.; Batstone, D. J. Modelling phosphorus (P), sulfur (S) and iron (Fe) interactions for dynamic simulations of anaerobic digestion processes. Water Res. 2016, 95, 370– 382,  DOI: 10.1016/j.watres.2016.03.012
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    Modelling phosphorus (P), sulfur (S) and iron (Fe) interactions for dynamic simulations of anaerobic digestion processes
    Flores-Alsina, Xavier; Solon, Kimberly; Kazadi Mbamba, Christian; Tait, Stephan; Gernaey, Krist V.; Jeppsson, Ulf; Batstone, Damien J.
    Water Research (2016), 95 (), 370-382CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
    This paper proposes a series of extensions to functionally upgrade the IWA Anaerobic Digestion Model No. 1 (ADM1) to allow for plant-wide phosphorus (P) simulation. The close interplay between the P, sulfur (S) and iron (Fe) cycles requires a substantial (and unavoidable) increase in model complexity due to the involved three-phase physico-chem. and biol. transformations. The ADM1 version, implemented in the plant-wide context provided by the Benchmark Simulation Model No. 2 (BSM2), is used as the basic platform (A0). Three different model extensions (A1, A2, A3) are implemented, simulated and evaluated. The first extension (A1) considers P transformations by accounting for the kinetic decay of polyphosphates (XPP) and potential uptake of volatile fatty acids (VFA) to produce polyhydroxyalkanoates (XPHA) by phosphorus accumulating organisms (XPAO). Two variant extensions (A2,1/A2,2) describe biol. prodn. of sulfides (SIS) by means of sulfate reducing bacteria (XSRB) utilizing hydrogen only (autolithotrophically) or hydrogen plus org. acids (heterorganotrophically) as electron sources, resp. These two approaches also consider a potential hydrogen sulfide (ZH2S) inhibition effect and stripping to the gas phase (GH2S). The third extension (A3) accounts for chem. iron (III) (SFe3+) redn. to iron (II) (SFe2+) using hydrogen (SH2) and sulfides (SIS) as electron donors. A set of pre/post interfaces between the Activated Sludge Model No. 2d (ASM2d) and ADM1 are furthermore proposed in order to allow for plant-wide (model-based) anal. and study of the interactions between the water and sludge lines. Simulation (A1 - A3) results show that the ratio between sol./particulate P compds. strongly depends on the pH and cationic load, which dets. the capacity to form (or not) pptn. products. Implementations A1 and A2,1/A2,2 lead to a redn. in the predicted methane/biogas prodn. (and potential energy recovery) compared to ref. ADM1 predictions (A0). This redn. is attributed to two factors: (1) loss of electron equiv. due to sulfate (SSO4) redn. by XSRB and storage of XPHA by XPAO; and, (2) decrease of acetoclastic and hydrogenotrophic methanogenesis due to ZH2S inhibition. Model A3 shows the potential for iron to remove free SIS (and consequently inhibition) and instead promote iron sulfide (XFeS) pptn. It also reduces the quantities of struvite (XMgNH4PO4) and calcium phosphate (XCa3(PO4)2) that are formed due to its higher affinity for phosphate anions. This study provides a detailed anal. of the different model assumptions, the effect that operational/design conditions have on the model predictions and the practical implications of the proposed model extensions in view of plant-wide modeling/development of resource recovery strategies.
  36. 36
    Sena, M.; Seib, M.; Noguera, D. R.; Hicks, A. Environmental impacts of phosphorus recovery through struvite precipitation in wastewater treatment. J. Cleaner Prod. 2021, 280, 124222,  DOI: 10.1016/j.jclepro.2020.124222
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    Environmental impacts of phosphorus recovery through struvite precipitation in wastewater treatment
    Sena, Madeline; Seib, Matthew; Noguera, Daniel R.; Hicks, Andrea
    Journal of Cleaner Production (2021), 280 (Part_1), 124222CODEN: JCROE8; ISSN:0959-6526. (Elsevier Ltd.)
    Wastewater treatment currently focuses on removing phosphorus (P) and nitrogen (N) due to their potential to cause eutrophication in bodies of water. With growing concern for the longevity of global phosphate rock stores, however, there is now interest in recovering these nutrients. One method for recovering P and N is through the pptn. of struvite (magnesium ammonium phosphate) which also helps control unwanted struvite pptn. in pipes and on other surfaces at the treatment plant lessening a challenging maintenance problem, and produces a valuable alternative fertilizer product. A potential concern is that the environmental impacts struvite recovery creates through the use of addnl. chems. and energy are not offset by its benefits. A life cycle assessment (LCA) case study of the full-scale wastewater treatment plant (WWTP) in Madison, WI USA was used to assess the environmental tradeoffs of struvite recovery in wastewater treatment. When only the struvite recovery system was considered, a portion of the environmental impact categories considered showed an overall environmental cost, while others showed a benefit, due to the phosphorus recovered. When the full scale WWTP was considered, there was an overall environmental impact to treating the wastewater, as there was prior to the struvite system deployment. However, due to the addnl. benefit of the struvite recovery, the overall environmental impacts of the WWTP are similar.
  37. 37
    Mavhungu, A.; Foteinis, S.; Mbaya, R.; Masindi, V.; Kortidis, I.; Mpenyana-Monyatsi, L.; Chatzisymeon, E. Environmental sustainability of municipal wastewater treatment through struvite precipitation: Influence of operational parameters. J. Cleaner Prod. 2021, 285, 124856,  DOI: 10.1016/j.jclepro.2020.124856
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    Environmental sustainability of municipal wastewater treatment through struvite precipitation: Influence of operational parameters
    Mavhungu, Avhafunani; Foteinis, Spyros; Mbaya, Richard; Masindi, Vhahangwele; Kortidis, Ioannis; Mpenyana-Monyatsi, Lizzy; Chatzisymeon, Efthalia
    Journal of Cleaner Production (2021), 285 (), 124856CODEN: JCROE8; ISSN:0959-6526. (Elsevier Ltd.)
    The environmental sustainability of wastewater treatment through phosphate (P) and ammonia (N) chem. pptn. (struvite) was examd. using the life cycle assessment methodol. Thermally activated (calcined) cryptocryst. magnesite was used towards struvite formation and four process parameters (contact time, magnesite dosage, initial wastewater pH and temp.) were studied. Raising wastewater's temp. to promote ammonia stripping was found to be environmentally unsound. Magnesite dosage and contact time were identified as environmental hotspots, but not pH. In terms of environmental relevance, when using ReCiPe 2016 life cycle impact assessment method, the human health damage category was mostly affected, followed by resource availability, while ecosystems category was affected to a much lesser extent. Environmental impacts were grossly attributed to South Africa's fossil fuel-dependent energy mix, suggesting that renewable energy could largely improve the system's environmental performance. The optimal conditions, from the environmental perspective, were found to be 0.2 g L-1 feed dosage and 10 min mixing, at ambient temp. and pH (total environmental footprint 60.9μPt per treated L of wastewater). To improve N removal efficacy, which is desirable in real-world applications, higher feed dosages and mixing durations are required, albeit at the expense of environmental sustainability (e.g. the 180 min and 16 g L-1 environmental footprint sharply rises to 1.87μPt L-1). The net impact approach revealed that the avoided environmental impacts on the midpoint impact categories freshwater and marine eutrophication grossly outweigh the corresponding environmental impacts of the treatment process. Results suggest that when using a low contact time and magnesite dosage, struvite pptn. could act as a fast, efficient, and environmentally friendly pretreatment step to practically remove P and grossly reduce N from wastewater. On the other hand, with higher feed dosages and mixing durations, struvite pptn. could act as a promising secondary wastewater treatment method with an overall low environmental footprint. Overall, results complement the existing body of knowledge on the techno-economic performance of such systems and provide insight to decision- and policy-makers to sustainably scale up the process, at village- or industrial-level, in rural South Africa, Lesotho, and further afield.
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    Sørensen, B. L.; Dall, O. L.; Habib, K. Environmental and resource implications of phosphorus recovery from waste activated sludge. Waste Manage. 2015, 45, 391– 399,  DOI: 10.1016/j.wasman.2015.02.012
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    Environmental and resource implications of phosphorus recovery from waste activated sludge
    Sorensen Birgitte Lilholt; Dall Ole Leinikka; Habib Komal
    Waste management (New York, N.Y.) (2015), 45 (), 391-9 ISSN:.
    Phosphorus is an essential mineral resource for the growth of crops and thus necessary to feed the ever increasing global population. The essentiality and irreplaceability of phosphorus in food production has raised the concerns regarding the long-term phosphorus availability and the resulting food supply issues in the future. Hence, the recovery of phosphorus from waste activated sludge and other waste streams is getting huge attention as a viable solution to tackle the potential availability issues of phosphorus in the future. This study explores the environmental implications of phosphorus recovery from waste activated sludge in Denmark and further elaborates on the potential availability or scarcity issue of phosphorus today and 2050. Life cycle assessment is used to assess the possibility of phosphorus recovery with little or no environmental impacts compared to the conventional mining. The phosphorus recovery method assessed in this study consists of drying process, and thermal gasification of the waste activated sludge followed by extraction of phosphorus from the ashes. Our results indicate that the environmental impacts of phosphorus recovery in an energy efficient process are comparable to the environmental effects from the re-use of waste activated sludge applied directly on farmland. Moreover, our findings conclude that the general recommendation according to the waste hierarchy, where re-use of the waste sludge on farmland is preferable to material and energy recovery, is wrong in this case. Especially when phosphorus is a critical resource due to its life threatening necessity, lack of substitution options and potential future supply risk originating due to the high level of global supply concentration.
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    Linderholm, K.; Tillman, A.-M.; Mattsson, J. E. Life cycle assessment of phosphorus alternatives for Swedish agriculture. Resour., Conserv. Recycl. 2012, 66, 27– 39,  DOI: 10.1016/j.resconrec.2012.04.006
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    Egle, L.; Rechberger, H.; Krampe, J.; Zessner, M. Phosphorus recovery from municipal wastewater: An integrated comparative technological, environmental and economic assessment of P recovery technologies. Sci. Total Environ. 2016, 571, 522– 542,  DOI: 10.1016/j.scitotenv.2016.07.019
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    Phosphorus recovery from municipal wastewater: An integrated comparative technological, environmental and economic assessment of P recovery technologies
    Egle, L.; Rechberger, H.; Krampe, J.; Zessner, M.
    Science of the Total Environment (2016), 571 (), 522-542CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
    Several technologies have been developed in recent years to recover wastewater P. However, these technologies target different P-contg. flows in wastewater treatment plants (effluent, digester supernatant, sewage sludge, and sewage sludge ash), use diverse engineering approaches and differ greatly with respect to P recycling rate, potential of removing or destroying pollutants, product quality, environmental impact and cost. This work compares 19 relevant P recovery technologies by considering their relations with existing wastewater and sludge treatment systems. A combination of different methods, such as material flow anal., damage units, ref. soil method, annuity method, integrated cost calcn. and a literature study on soly., fertilizing effects and handling of recovered materials, is used to evaluate the different technologies with respect to tech., ecol. and economic aspects. With regard to the manifold origins of data an uncertainty concept considering validity of data sources is applied. This anal. revealed that recovery from flows with dissolved P produces clean and plant-available materials. These techniques may even be beneficial from economic and tech. perspectives under specific circumstances. However, the recovery rates (max. 25%) relative to the wastewater treatment plant influent are relatively low. The approaches that recover P from sewage sludge apply complex technologies and generally achieve effective removal of heavy metals at moderate recovery rates (∼40-50% relative to the WWTP input) and comparatively high costs. Sewage sludge ash is the most promising P source, with recovery rates of 60-90% relative to the wastewater P. The costs highly depend on the purity requirements of the recycled products but can be kept comparatively low, esp. if synergies with existing industrial processes are exploited.
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    Santos, A. F.; Almeida, P. V.; Alvarenga, P.; Gando-Ferreira, L. M.; Quina, M. J. From wastewater to fertilizer products: Alternative paths to mitigate phosphorus demand in European countries. Chemosphere 2021, 284, 131258,  DOI: 10.1016/j.chemosphere.2021.131258
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    Alternative paths to mitigate phosphorus demand from wastewater to fertilizer products in European countries
    Santos, Andreia F.; Almeida, Patricia V.; Alvarenga, Paula; Gando-Ferreira, Licinio M.; Quina, Margarida J.
    Chemosphere (2021), 284 (), 131258CODEN: CMSHAF; ISSN:0045-6535. (Elsevier Ltd.)
    A review. Phosphorus (P) is a non-renewable resource, irreplaceable for life and food prodn., and currently considered a Crit. Raw Material to the European Union (EU). Due to concerns about the rate of consumption and limited reserves in countries with sensitive geopolitical contexts, it is urgent to recover P from urban and industrial flows. Indeed, the municipal wastewater treatment plants (WWTP) are considered relevant sources with several hot spots, esp. sewage sludge with estd. recovery efficiencies of >80%. The most promising recovery strategies are based on thermal treatments (e.g., incineration of sludge) following by wet-chem. or thermo-chem. leaching, pptn., and adsorption. The direct application of sludge on soil is no longer a primary route for P reintegration in the value-chain for countries as Switzerland, Germany, and The Netherlands. In fact, Switzerland and Austria paved the way for implementing P recovery legislation, focusing on recovery from raw sewage sludge or ashes. Indeed, industrial technologies with sludge ash as input show high recovery efficiencies (Ashdec and Leachphos with 98 and 79%) and lower environmental impacts, whereas Pearl technol. has about 12% recovery efficiency with wastewater as input. After all, struvite emerges as the most recovered product with recent access to the internal market of EU fertilisers and similar growth performance compared to triple-super-phosphate. However, several studies leave open the possibility of introducing loaded adsorbents with P as soil amendments as a new alternative to conventional desorption. Briefly, P recovery should be a compromise between efficiency, environmental impacts, and economic revenues from the final products.
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    Nemecek, T.; Jungbluth, N.; i Canals, L. M.; Schenck, R. Environmental impacts of food consumption and nutrition: where are we and what is next?. Int. J. Life Cycle Assess. 2016, 21, 607– 620,  DOI: 10.1007/s11367-016-1071-3
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    Trimmer, J. T.; Margenot, A. J.; Cusick, R. D.; Guest, J. S. Aligning Product Chemistry and Soil Context for Agronomic Reuse of Human-Derived Resources. Environ. Sci. Technol. 2019, 53, 6501– 6510,  DOI: 10.1021/acs.est.9b00504
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    Aligning Product Chemistry and Soil Context for Agronomic Reuse of Human-Derived Resources
    Trimmer, John T.; Margenot, Andrew J.; Cusick, Roland D.; Guest, Jeremy S.
    Environmental Science & Technology (2019), 53 (11), 6501-6510CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Recovering human-derived nutrients from sanitation systems can offset inorg. fertilizer use and improve access to agricultural nutrients in resource-limited settings, but the agronomic value of recovered products depends upon product chem. and soil context. Products may exacerbate already-compromised soil conditions, offer benefits beyond nutrients, or have reduced efficacy depending on soil characteristics. Using global spatial modeling, we evaluate the soil suitability of seven products (wastewater, sludge, compost, urine, ammonium sulfate, ammonium struvite, potassium struvite) and integrate this information with local recovery potential of each product from sanitation systems that will need to be installed to achieve universal coverage (referred to here as "newly-installed sanitation"). If product recovery and reuse are colocated, the quantity and suitability of nutrient reuse was variable across countries. For example, alk. products (e.g., struvite) may be particularly beneficial when applied to acidic soils in Uganda but potentially detrimental in the southwestern United States. Further, we illustrate discrepancies across soil data sets and highlight the need for locally accurate data, knowledge, and interpretation. Overall, this study demonstrates soil context is crit. to comprehensively characterize the value proposition of nutrient recovery, and it provides a foundation for incorporating soil suitability into local and global sanitation decision-making.
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    Muys, M.; Phukan, R.; Brader, G.; Samad, A.; Moretti, M.; Haiden, B.; Pluchon, S.; Roest, K.; Vlaeminck, S. E.; Spiller, M. A systematic comparison of commercially produced struvite: Quantities, qualities and soil-maize phosphorus availability. Sci. Total Environ. 2021, 756, 143726,  DOI: 10.1016/j.scitotenv.2020.143726
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    A systematic comparison of commercially produced struvite: Quantities, qualities and soil-maize phosphorus availability
    Muys, Maarten; Phukan, Rishav; Brader, Gunter; Samad, Abdul; Moretti, Michele; Haiden, Barbara; Pluchon, Sylvain; Roest, Kees; Vlaeminck, Siegfried E.; Spiller, Marc
    Science of the Total Environment (2021), 756 (), 143726CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
    Prodn. of struvite (MgNH4PO4·6H2O) from waste streams is increasingly implemented to recover phosphorus (P), which is listed as a crit. raw material in the European Union (EU). To facilitate EU-wide trade of P-contg. secondary raw materials such as struvite, the EU issued a revised fertilizer regulation in 2019. A comprehensive overview of the supply of struvite and its quality is presently missing. This study aimed: (i) to det. the current EU struvite prodn. vols., (ii) to evaluate all legislated physicochem. characteristics and pathogen content of European struvite against newly set regulatory limits, and (iii) to compare not-regulated struvite characteristics. It is estd. that in 2020, between 990 and 1250 ton P are recovered as struvite in the EU. Struvite from 24 European prodn. plants, accounting for 30% of the 80 struvite installations worldwide was sampled. Three samples failed the physicochem. legal limits; one had a P content of <7% and three exceeded the org. carbon content of 3% dry wt. (DW). Mineralogical anal. revealed that six samples had a struvite content of 80-90% DW, and 13 samples a content of >90% DW. All samples showed a heavy metal content below the legal limits. Microbiol. analyses indicated that struvite may exceed certain legal limits. Differences in morphol. and particle size distribution were obsd. for struvite sourced from digestate (rod shaped; transparent; 82 mass% < 1 mm), dewatering liquor (spherical; opaque; 65 mass% 1-2 mm) and effluent from upflow anaerobic sludge blanket reactor processing potato wastewater (spherical; opaque; 51 mass% < 1 mm and 34 mass% > 2 mm). A uniform soil-plant P-availability pattern of 3.5-6.5 mg P/L soil/d over a 28 days sampling period was obsd. No differences for plant biomass yield were obsd. In conclusion, the results highlight the suitability of most struvite to enter the EU fertilizer market.
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    Degryse, F.; Baird, R.; da Silva, R. C.; McLaughlin, M. J. Dissolution rate and agronomic effectiveness of struvite fertilizers – effect of soil pH, granulation and base excess. Plant Soil 2017, 410, 139– 152,  DOI: 10.1007/s11104-016-2990-2
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    Dissolution rate and agronomic effectiveness of struvite fertilizers - effect of soil pH, granulation and base excess
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    Aims: Struvite (MgNH4PO4.6H2O) recovered from wastewater can be used as fertilizer. The agronomic effectiveness of struvite has mostly been evaluated using ground fertilizer mixed through soil. However, fertilizers are most commonly applied in granular form in the field. In this study, we assessed the dissoln. and effectiveness of different struvites when applied in granular or powd. form. Methods: Phosphorus (P) diffusion in soil, detd. using a visualization technique and chem. analyses, and P uptake by 6-wk old wheat was compared for sol. fertilizer (monoammonium phosphate, MAP), a com. struvite and three synthesized struvites with different excess MgO, in both granular and ground form. Results: Ground struvite mixed through soil quickly dissolved and its agronomic effectiveness was similar to that of MAP. For pure granular struvite, the granule dissoln. rate ranged from circa 0.03 mg d-1 in alk. soil to 0.43 mg d-1 in acidic soil. Excess base in the struvite fertilizer reduced its dissoln. rate. The P uptake by wheat followed the order MAP > > struvite ≥ control (no P), with no significant difference between the control and the struvite treatment in alk. soil. Conclusions: Both fertilizer characteristics (particle size, excess base) and soil pH strongly affect the dissoln. rate of struvite and hence its agronomic effectiveness.
  46. 46
    Diaz-Elsayed, N.; Rezaei, N.; Guo, T.; Mohebbi, S.; Zhang, Q. Wastewater-based resource recovery technologies across scale: A review. Resour., Conserv. Recycl. 2019, 145, 94– 112,  DOI: 10.1016/j.resconrec.2018.12.035
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    Pradel, M.; Aissani, L. Environmental impacts of phosphorus recovery from a “product” Life Cycle Assessment perspective: Allocating burdens of wastewater treatment in the production of sludge-based phosphate fertilizers. Sci. Total Environ. 2019, 656, 55– 69,  DOI: 10.1016/j.scitotenv.2018.11.356
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    Environmental impacts of phosphorus recovery from a "product" Life Cycle Assessment perspective: Allocating burdens of wastewater treatment in the production of sludge-based phosphate fertilizers
    Pradel, Marilys; Aissani, Lynda
    Science of the Total Environment (2019), 656 (), 55-69CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
    Since phosphorus (P) is a non-renewable element essential for life, it is extremely important to explore any potential supply of P, including that recovered from human excreta and urban wastewater. This study aimed to assess, using Life Cycle Assessment (LCA), whether recovering dissipated P by producing sludge-based phosphate fertilizer can be a suitable method to reduce P depletion. Environmental impacts of four scenarios of prodn. of sludge-based phosphate fertilizers were compared to those of prodn. of triple super phosphate, a mineral phosphate fertilizer used as a ref. scenario. The novelty of this study was to est. environmental impacts of sludge-based phosphate fertilizer prodn. using a "product" LCA perspective instead of a "waste" LCA perspective. Consequently, upstream prodn. of sludge was considered by allocating part of the environmental burdens of wastewater treatment to sludge prodn. Life Cycle Impact Assessment was performed using the CML-IA characterization method. Results indicated that sludge-based phosphate fertilizers appeared less environmentally friendly than mineral phosphate fertilizers, due to the contribution of the upstream burden of sludge prodn. and P recovery. Finally, although P recovery helps preserve the mineral P resource, the overall assessment remains unfavorable for sludge-based products due to the low yields of P recovery, low P concn. of the sludge and the large amts. of energy and reactants needed to recover the P.
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    Pradel, M.; Lippi, M.; Daumer, M.-L.; Aissani, L. Environmental performances of production and land application of sludge-based phosphate fertilizers-a life cycle assessment case study. Environ. Sci. Pollut. Res. 2020, 27, 2054– 2070,  DOI: 10.1007/s11356-019-06910-4
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    Environmental performances of production and land application of sludge-based phosphate fertilizers-a life cycle assessment case study
    Pradel, Marilys; Lippi, Mathilde; Daumer, Marie-Line; Aissani, Lynda
    Environmental Science and Pollution Research (2020), 27 (2), 2054-2070CODEN: ESPLEC; ISSN:0944-1344. (Springer)
    Phosphorus (P) is a non-renewable resource extd. from phosphate rock to produce agricultural fertilizers. Since P is essential for life, it is important to preserve this resource and explore alternative sources of P to reduce its criticality. This study aimed to assess whether fertilizing with sludge-based phosphate fertilizers (SBPF) can be a suitable alternative to doing so with fertilizers produced from phosphate rock. Environmental impacts of prodn. and land application of SBPF from four recovery processes were compared to those of two ref. scenarios: triple super phosphate (TSP) and sewage sludge. To avoid bias when comparing scenarios, part of the environmental burden of wastewater treatment is allocated to sludge prodn. The CML-IA method was used to perform life cycle impact assessment. Results highlighted that prodn. and land application of SBPF had higher environmental impacts than those of TSP due to the large amts. of energy and reactants needed to recover P, esp. when sludge had a low P concn. Certain environmental impacts of prodn. and land application of sewage sludge were similar to those of SBPF. Sensitivity anal. conducted for cropping systems highlighted variability in potential application rates of sewage sludge or SBPF. Finally, because they contain lower contents of heavy metals than sewage sludge or TSP, SBPF are of great interest, but they require more mineral fertilizers to supplement their fertilization than sewage sludge. Thus, SBPF have advantages and disadvantages that need to be considered, since they may influence their use within fertilization practices.
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  • Abstract

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    Figure 1

    Figure 1. Process, product, and end-user perspectives of phosphorus recovery.

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    Figure 2

    Figure 2. Baseline pathways (BPn) without P recovery and six possible P recovery pathways (RP1–RP6), differing in the recovered phosphorus products (i.e., struvite, Ca–P, rhenania phosphate-like product, or single superphosphate-like product) and the possible inclusion of CEPT in the treatment line. For all RPs, the wastewater-derived phosphorus product was assumed to substitute half (1/2 ṁ) of the conventional phosphate rock-based fertilizers used in the baseline pathways (BPn). Besides, all RPs share the same baseline for the crop production system, while each RP has its baseline for the wastewater treatment system. Three crop production systems (i.e., maize, rice, and wheat) were considered.

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    Figure 3

    Figure 3. Changes in the global warming potential, eutrophication potential, ecotoxicity potential, and acidification potential in three different crop production systems after substituting half of the conventional phosphate rock-based fertilizers with wastewater-derived phosphorus products from six different RPs compared to the baseline pathway. Within a RP for a given crop, each dot is a scenario─one of the 27 combinations of the influent pollutant concentration, sludge disposal method, and carbon intensity of grid electricity. RP1: struvite from the digester supernatant; RP2: Ca–P from the digester supernatant; RP3 and RP4: rhenania phosphate-like product from the incinerated sludge ashes (RP4 with CEPT); RP5 and RP6: single superphosphate from the incinerated sludge ashes (RP6 with CEPT).

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  • References

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      Cordell, D.; Rosemarin, A.; Schroeder, J. J.; Smit, A. L.
      Chemosphere (2011), 84 (6), 747-758CODEN: CMSHAF; ISSN:0045-6535. (Elsevier Ltd.)
      Human intervention in the global P cycle has mobilized nearly half a billion tons of the element from phosphate rock into the hydrosphere over the past half century. The resultant water pollution concerns have been the main driver for sustainable P use (including P recovery). However the emerging global challenge of P scarcity with serious implications for future food security, means P will also need to be recovered for productive reuse as a fertilizer in food prodn. to replace increasingly scarce and more expensive phosphate rock. Through an integrated and systems framework, this paper examines the full spectrum of sustainable P recovery and reuse options (from small-scale low-cost to large-scale high-tech.), facilitates integrated decision-making and identifies future opportunities and challenges for achieving global P security. Case studies are provided rather than focusing on a specific technol. or process. There is no single soln. to achieving a P-secure future: in addn. to increasing P use efficiency, P will need to be recovered and reused from all current waste streams throughout the food prodn. and consumption system (from human and animal excreta to food and crop wastes). There is a need for new sustainable policies, partnerships and strategic frameworks to develop renewable P fertilizer systems for farmers. Further research is also required to det. the most sustainable means in a given context for recovering P from waste streams and converting the final products into effective fertilizers, accounting for life cycle costs, resource and energy consumption, availability, farmer accessibility and pollution.
    5. 5
      Melia, P. M.; Cundy, A. B.; Sohi, S. P.; Hooda, P. S.; Busquets, R. Trends in the recovery of phosphorus in bioavailable forms from wastewater. Chemosphere 2017, 186, 381– 395,  DOI: 10.1016/j.chemosphere.2017.07.089
      5
      Trends in the recovery of phosphorus in bioavailable forms from wastewater
      Melia, Patrick M.; Cundy, Andrew B.; Sohi, Saran P.; Hooda, Peter S.; Busquets, Rosa
      Chemosphere (2017), 186 (), 381-395CODEN: CMSHAF; ISSN:0045-6535. (Elsevier Ltd.)
      Addressing food security issues arising from phosphorus (P) scarcity is described as one of the greatest global challenges of the 21st century. Dependence on inorg. phosphate fertilizers derived from limited geol. sources of P creates an urgent need to recover P from wastes and treated waters, in safe forms that are also effective agriculturally - the established process of P removal by chem. pptn. using Fe or Al salts, is effective for P removal but leads to residues with limited bioavailability and contamination concerns. One of the greatest opportunities for P recovery is at wastewater treatment plants (WWTPs) where the crystn. of struvite and Ca-P from enhanced biol. P removal (EBPR) sludge is well developed and already shown to be economically and operationally feasible in some WWTPs. However, recovery through this approach can be limited to <25% efficiency unless chem. extn. is applied. Thermochem. treatment of sludge ash produces detoxified residues that are currently utilized by the fertilizer industry; wet chem. extn. can be economically feasible in recovering P and other byproducts. The bioavailability of recovered P depends on soil pH as well as the P-rich material in question. Struvite is a superior recovered P product in terms of plant availability, while use of Ca-P and thermochem. treated sewage sludge ash is limited to acidic soils. These technologies, in addn. to others less developed, will be com. pushed forward by revised fertilizer legislation and foreseeable legislative limits for WWTPs to achieve discharges of <1 mg P/L.
    6. 6
      Harder, R.; Wielemaker, R.; Larsen, T. A.; Zeeman, G.; Öberg, G. Recycling nutrients contained in human excreta to agriculture: Pathways, processes, and products. Crit. Rev. Environ. Sci. Technol. 2019, 49, 695– 743,  DOI: 10.1080/10643389.2018.1558889
      There is no corresponding record for this reference.
    7. 7
      Mayer, B. K.; Baker, L. A.; Boyer, T. H.; Drechsel, P.; Gifford, M.; Hanjra, M. A.; Parameswaran, P.; Stoltzfus, J.; Westerhoff, P.; Rittmann, B. E. Total Value of Phosphorus Recovery. Environ. Sci. Technol. 2016, 50, 6606– 6620,  DOI: 10.1021/acs.est.6b01239
      7
      Total Value of Phosphorus Recovery
      Mayer, Brooke K.; Baker, Lawrence A.; Boyer, Treavor H.; Drechsel, Pay; Gifford, Mac; Hanjra, Munir A.; Parameswaran, Prathap; Stoltzfus, Jared; Westerhoff, Paul; Rittmann, Bruce E.
      Environmental Science & Technology (2016), 50 (13), 6606-6620CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      A review is given. P is a crit., geog. concd., nonrenewable resource necessary to support global food prodn. In excess (e.g., due to runoff or wastewater discharges), P is also a primary cause of eutrophication. To reconcile the simultaneous shortage and overabundance of P, lost P flows must be recovered and reused, alongside improvements in P-use efficiency. While this motivation is increasingly being recognized, little P recovery is practiced today, as recovered P generally cannot compete with the relatively low cost of mined P. Therefore, P is often captured to prevent its release into the environment without beneficial recovery and reuse. However, addnl. incentives for P recovery emerge when accounting for the total value of P recovery. This article provides a comprehensive overview of the range of benefits of recovering P from waste streams, i.e., the total value of recovering P. This approach accounts for P products, as well as other assets that are assocd. with P and can be recovered in parallel, such as energy, N, metals and minerals, and water. P recovery provides valuable services to society and the environment by protecting and improving environmental quality, enhancing efficiency of waste treatment facilities, and improving food security and social equity. The needs to make P recovery a reality are also discussed, including business models, bottlenecks, and policy and education strategies.
    8. 8
      van der Hoek, J. P.; Struker, A.; de Danschutter, J. E. M. Amsterdam as a sustainable European metropolis: integration of water, energy and material flows. Urban Water J. 2017, 14, 61– 68,  DOI: 10.1080/1573062x.2015.1076858
      8
      Amsterdam as a sustainable European metropolis: integration of water, energy and material flows
      van der Hoek, J. P.; Struker, A.; de Danschutter, J. E. M.
      Urban Water Journal (2017), 14 (1), 61-68CODEN: UWJRAU; ISSN:1573-062X. (Taylor & Francis Ltd.)
      Amsterdam has the ambition to develop as a competitive and sustainable European metropolis. The flows of energy, water and resources within the urban environment have a large potential to contribute to this ambition. Through a transition from a linear usage of resources and waste prodn. towards a sustainable management of urban resources with circular flows of resources, the sustainability of cities can be increased. This Urban Harvesting Concept may be applied in Amsterdam. The challenge is how to operationalize this concept in practice. For two municipal companies in Amsterdam, Waternet (responsible for the water management) and AEB (the waste-to-energy company), initiatives were identified on how to do this. The focus is on water, energy, waste and material flows. Circular flows result in economic benefits and sustainability benefits, either expressed as Ecopoints or CO2-emissions. The integration of these flows is esp. beneficial.
    9. 9
      Rufí-Salís, M.; Brunnhofer, N.; Petit-Boix, A.; Gabarrell, X.; Guisasola, A.; Villalba, G. Can wastewater feed cities? Determining the feasibility and environmental burdens of struvite recovery and reuse for urban regions. Sci. Total Environ. 2020, 737, 139783,  DOI: 10.1016/j.scitotenv.2020.139783
      9
      Can wastewater feed cities Determining the feasibility and environmental burdens of struvite recovery and reuse for urban regions
      Rufi-Salis, Marti; Brunnhofer, Nadin; Petit-Boix, Anna; Gabarrell, Xavier; Guisasola, Albert; Villalba, Gara
      Science of the Total Environment (2020), 737 (), 139783CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
      Phosphorus (P) resources are decreasing at an alarming rate due to global fertilizer use and insufficient nutrient recovery strategies. Currently, more circular approaches are promoted, such as recovering P from wastewater in the form of struvite. This is esp. attractive for urban areas, where there is a growing trend of local crop prodn. and large vols. of wastewater are treated in centralized wastewater treatment plants (WWTPs). This research aims to assess the tech. and environmental feasibility of applying a struvite recovery and reuse strategy to meet the P requirements to fertilize the agricultural fields of an urban region. To do so, we analyze the potential P recovery and the environmental impacts of integrating three recovery technologies (REM-NUT, Ostara and AirPrex) in the two biggest WWTPs of the Area Metropolitana de Barcelona. The results show that all technologies are able to recover between 5 and 30 times the amt. of P required to fertilize the agricultural area of the region annually (36.5 t). As can be expected, including P recovery technologies result in addnl. impacts per m3 of wastewater due to increased electricity consumption and chems. required for the struvite pptn. However, struvite recovery results in less eutrophication potential, esp. in the REM-NUT case, with an av. redn. of 5.4 times. On the other hand, Ostara, that recovers P from the digestate, had the lowest impacts (9 kgCO2eq/kgP), even compared to the prodn. of mineral.
    10. 10
      Diaz-Elsayed, N.; Rezaei, N.; Ndiaye, A.; Zhang, Q. Trends in the environmental and economic sustainability of wastewater-based resource recovery: A review. J. Cleaner Prod. 2020, 265, 121598,  DOI: 10.1016/j.jclepro.2020.121598
      10
      Trends in the environmental and economic sustainability of wastewater-based resource recovery: A review
      Diaz-Elsayed, Nancy; Rezaei, Nader; Ndiaye, Awa; Zhang, Qiong
      Journal of Cleaner Production (2020), 265 (), 121598CODEN: JCROE8; ISSN:0959-6526. (Elsevier Ltd.)
      A review. Wastewater is rich with valuable resources available for recovery. Although the resource recovery process can enable the offset of freshwater withdrawals, fertilizer prodn., and the use of fossil fuels, it comes at a cost. This review focuses on the environmental and economic impacts of recovering water, energy, and nutrients from wastewater. Specifically, life cycle assessments and life cycle cost analyses were reviewed to identify trends in wastewater-based resource recovery systems. Process conditions were found to have a significant influence on impacts in some instances. For example, the operating temp. for incineration could lower or eliminate N2O emissions altogether, while the flow rate and cold water temp. resulted in heat transfer efficiencies for thermal energy recovery systems ranging from ∼12% to 92%. Economies of scale were largely present in the processing of wastewater and biosolids, however, the re-distribution of reclaimed water exhibited diseconomies of scale as water networks increased in service size. This led to some studies exhibiting lower impacts for centralized systems, while others favored decentralization. Nonetheless, when averaged and categorized by scale, the greenhouse gas emissions for large-scale water reclamation systems (280 kg CO2-eq/person-year) was significantly lower than medium- and small-scale systems (4600 and 23740 kg CO2-eq/person-year, resp.). Future research is recommended in analyzing understudied technologies (e.g., environmental assessments of thermal energy recovery systems and wastewater-based hydropower technologies), investigating spatial-temporal contexts, and optimizing wastewater systems with multiple forms of resource recovery technologies across varied scales.
    11. 11
      Lam, K. L.; Zlatanović, L.; van der Hoek, J. P. Life cycle assessment of nutrient recycling from wastewater: A critical review. Water Res. 2020, 173, 115519,  DOI: 10.1016/j.watres.2020.115519
      11
      Life cycle assessment of nutrient recycling from wastewater: A critical review
      Lam, Ka Leung; Zlatanovic, Ljiljana; van der Hoek, Jan Peter
      Water Research (2020), 173 (), 115519CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
      A review. Recovering resources from wastewater systems is increasingly being emphasized. Many technologies exist or are under development for recycling nutrients such as nitrogen and phosphorus from wastewater to agriculture. Planning and design methodologies are needed to identify and deploy the most sustainable solns. in given contexts. For the environmental sustainability dimension, life cycle assessment (LCA) can be used to assess environmental impact potentials of wastewater-based nutrient recycling alternatives, esp. nitrogen and phosphorus recycling. This review aims to evaluate how well the LCA methodol. has been adapted and applied for assessing opportunities of wastewater-based nutrient recycling in the form of monomineral, multimineral, nutrient soln. and org. solid. We reviewed 65 LCA studies that considered nutrient recycling from wastewater for agricultural land application. We synthesized some of their insights and methodol. practices, and discussed the future outlook of using LCA for wastewater-based nutrient recycling. In general, more studies suggested pos. environmental outcomes from wastewater-based nutrient recycling, esp. when chem. inputs are minimised, and source sepn. of human excreta is achieved. The review shows the need to improve methodol. consistency (e.g., multifunctionality, fertiliser offset accounting, contaminant accounting), ensure transparency of inventory and methods, consider uncertainty in comparative LCA context, integrate up-to-date cross-disciplinary knowledge (e.g., agriculture science, soil science) into LCA models, and consider the localised impacts of recycled nutrient products. Many opportunities exist for applying LCA at various scales to support decisions on wastewater-based nutrient recycling - for instance, performing "product perspective" LCA on recycled nutrient products, integrating "process perspective" LCA with other systems approaches for selecting and optimizing individual recovery processes, assessing emerging nutrient recovery technologies and integrated resource recovery systems, and conducting systems anal. at city, national and global level.
    12. 12
      Guest, J. S.; Skerlos, S. J.; Barnard, J. L.; Beck, M. B.; Daigger, G. T.; Hilger, H.; Jackson, S. J.; Karvazy, K.; Kelly, L.; Macpherson, L.; Mihelcic, J. R.; Pramanik, A.; Raskin, L.; Van Loosdrecht, M. C. M.; Yeh, D.; Love, N. G. A new planning and design paradigm to achieve sustainable resource recovery from wastewater. Environ. Sci. Technol. 2009, 43, 6126– 6130,  DOI: 10.1021/es9010515
      12
      A New Planning and Design Paradigm to Achieve Sustainable Resource Recovery from Wastewater
      Guest, Jeremy S.; Skerlos, Steven J.; Barnard, James L.; Beck, M. Bruce; Daigger, Glen T.; Hilger, Helene; Jackson, Steven J.; Karvazy, Karen; Kelly, Linda; Macpherson, Linda; Mihelcic, James R.; Pramanik, Amit; Raskin, Lutgarde; Van Loosdrecht, Mark C. M.; Yeh, Daniel; Love, Nancy G.
      Environmental Science & Technology (2009), 43 (16), 6126-6130CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Fraught with hazards requiring diligent attention, new wastewater treatment techniques protect public health, improve ecosystem quality, and are a crit. contributor to global sustainability. Yet sustainable water systems can only be fully realized if the general public and the water industry begin thinking about wastewater differently. This article discusses a paradigm shift from wastewater to resource water. Topics covered include: wastewater as a renewable resource (water, energy, and material recovery; resource recovery systems [RRS]; barriers to successfully implement RRS); the pursuit of sustainability in water management (environmental and ecol., economic, and social assessments; resolving decision-making trade-offs); changes and the path forward (stakeholder participation in planning and design, transition toward sustainability); and appendixes (proposed guiding principles to design sustainable RRS applied to water; challenges and future technologies in RRS).
    13. 13
      Hellweg, S.; Milà i Canals, L. Emerging approaches, challenges and opportunities in life cycle assessment. Science 2014, 344, 1109– 1113,  DOI: 10.1126/science.1248361
      13
      Emerging approaches, challenges and opportunities in life cycle assessment
      Hellweg, Stefanie; Mila i Canals, Llorenc
      Science (Washington, DC, United States) (2014), 344 (6188), 1109-1113CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      In the modern economy, international value chains-prodn., use, and disposal of goods-have global environmental impacts. Life Cycle Assessment (LCA) aims to track these impacts and assess them from a systems perspective, identifying strategies for improvement without burden shifting. We review recent developments in LCA, including existing and emerging applications aimed at supporting environmentally informed decisions in policy-making, product development and procurement, and consumer choices. LCA constitutes a viable screening tool that can pinpoint environmental hotspots in complex value chains, but we also caution that completeness in scope comes at the price of simplifications and uncertainties. Future advances of LCA in enhancing regional detail and accuracy as well as broadening the assessment to economic and social aspects will make it more relevant for producers and consumers alike.
    14. 14
      Amann, A.; Zoboli, O.; Krampe, J.; Rechberger, H.; Zessner, M.; Egle, L. Environmental impacts of phosphorus recovery from municipal wastewater. Resour., Conserv. Recycl. 2018, 130, 127– 139,  DOI: 10.1016/j.resconrec.2017.11.002
      There is no corresponding record for this reference.
    15. 15
      Bradford-Hartke, Z.; Lane, J.; Lant, P.; Leslie, G. Environmental Benefits and Burdens of Phosphorus Recovery from Municipal Wastewater. Environ. Sci. Technol. 2015, 49, 8611– 8622,  DOI: 10.1021/es505102v
      15
      Environmental Benefits and Burdens of Phosphorus Recovery from Municipal Wastewater
      Bradford-Hartke, Zenah; Lane, Joe; Lant, Paul; Leslie, Gregory
      Environmental Science & Technology (2015), 49 (14), 8611-8622CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      The environmental benefits and burdens of phosphorus recovery in four centralized and two decentralized municipal wastewater systems were compared using life cycle assessment (LCA). In centralized systems, phosphorus recovered as struvite from the solids dewatering liq. resulted in an environmental benefit except for the terrestrial ecotoxicity and freshwater eutrophication impact categories, with power and chem. use offset by operational savings and avoided fertilizer prodn. Chem.-based phosphorus recovery, however, generally required more resources than were offset by avoided fertilizers, resulting in a net environmental burden. In decentralized systems, phosphorus recovery via urine source sepn. reduced the global warming and ozone depletion potentials but increased terrestrial ecotoxicity and salinization potentials due to application of untreated urine to land. Overall, mineral depletion and eutrophication are well-documented arguments for phosphorus recovery; however, phosphorus recovery does not necessarily present a net environmental benefit. While avoided fertilizer prodn. does reduce potential impacts, phosphorus recovery does not necessarily offset the resources consumed in the process. LCA results indicate that selection of an appropriate phosphorus recovery method should consider both local conditions and other environmental impacts, including global warming, ozone depletion, toxicity, and salinization, in addn. to eutrophication and mineral depletion impacts.
    16. 16
      Tonini, D.; Saveyn, H. G. M.; Huygens, D. Environmental and health co-benefits for advanced phosphorus recovery. Nat. Sustain. 2019, 2, 1051– 1061,  DOI: 10.1038/s41893-019-0416-x
      There is no corresponding record for this reference.
    17. 17
      Hörtenhuber, S. J.; Theurl, M. C.; Möller, K. Comparison of the environmental performance of different treatment scenarios for the main phosphorus recycling sources. Renew. Agric. Food Syst. 2019, 34, 349– 362,  DOI: 10.1017/s1742170517000515
      There is no corresponding record for this reference.
    18. 18
      Solon, K.; Flores-Alsina, X.; Kazadi Mbamba, C.; Ikumi, D.; Volcke, E. I. P.; Vaneeckhaute, C.; Ekama, G.; Vanrolleghem, P. A.; Batstone, D. J.; Gernaey, K. V.; Jeppsson, U. Plant-wide modelling of phosphorus transformations in wastewater treatment systems: Impacts of control and operational strategies. Water Res. 2017, 113, 97– 110,  DOI: 10.1016/j.watres.2017.02.007
      18
      Plant-wide modelling of phosphorus transformations in wastewater treatment systems: Impacts of control and operational strategies
      Solon, K.; Flores-Alsina, X.; Kazadi Mbamba, C.; Ikumi, D.; Volcke, E. I. P.; Vaneeckhaute, C.; Ekama, G.; Vanrolleghem, P. A.; Batstone, D. J.; Gernaey, K. V.; Jeppsson, U.
      Water Research (2017), 113 (), 97-110CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
      The objective of this paper is to report the effects that control/operational strategies may have on plant-wide phosphorus (P) transformations in wastewater treatment plants (WWTP). The development of a new set of biol. (activated sludge, anaerobic digestion), physico-chem. (aq. phase, pptn., mass transfer) process models and model interfaces (between water and sludge line) were required to describe the required tri-phasic (gas, liq., solid) compd. transformations and the close interlinks between the P and the sulfur (S) and iron (Fe) cycles. A modified version of the Benchmark Simulation Model No. 2 (BSM2) (open loop) is used as test platform upon which three different operational alternatives (A1, A2, A3) are evaluated. Rigorous sensor and actuator models are also included in order to reproduce realistic control actions. Model-based anal. shows that the combination of an ammonium (SNHX) and total suspended solids (XTSS) control strategy (A1) better adapts the system to influent dynamics, improves phosphate (SPO4) accumulation by phosphorus accumulating organisms (XPAO) (41%), increases nitrification/denitrification efficiency (18%) and reduces aeration energy (Eaeration) (21%). The addn. of iron (XFeCl3) for chem. P removal (A2) promotes the formation of ferric oxides (XHFO-H, XHFO-L), phosphate adsorption (XHFO-H,P, XHFO-L,P), co-pptn. (XHFO-H,P,old, XHFO-L,P,old) and consequently reduces the P levels in the effluent (from 2.8 to 0.9 g P.m-3). This also has an impact on the sludge line, with hydrogen sulfide prodn. (GH2S) reduced (36%) due to iron sulfide (XFeS) pptn. As a consequence, there is also a slightly higher energy prodn. (Eproduction) from biogas. Lastly, the inclusion of a stripping and crystn. unit (A3) for P recovery reduces the quantity of P in the anaerobic digester supernatant returning to the water line and allows potential struvite (XMgNH4PO4) recovery ranging from 69 to 227 kg.day-1 depending on: (1) airflow (Qstripping); and, (2) magnesium (QMg(OH)2) addn. All the proposed alternatives are evaluated from an environmental and economical point of view using appropriate performance indexes. Finally, some deficiencies and opportunities of the proposed approach when performing (plant-wide) wastewater treatment modeling/engineering projects are discussed.
    19. 19
      Hertzberger, A. J.; Cusick, R. D.; Margenot, A. J. Maize and soybean response to phosphorus fertilization with blends of struvite and monoammonium phosphate. Plant Soil 2021, 461, 547– 563,  DOI: 10.1007/s11104-021-04830-2
      19
      Maize and soybean response to phosphorus fertilization with blends of struvite and monoammonium phosphate
      Hertzberger, Allan J.; Cusick, Roland D.; Margenot, Andrew J.
      Plant and Soil (2021), 461 (1-2), 547-563CODEN: PLSOA2; ISSN:0032-079X. (Springer)
      Struvite (MgNH4PO4·6H2O), a low water soly. (<3%) mineral that is increasingly recovered from wastewater treatment plants, has potential to be used as a slow release ammonium phosphate fertilizer, esp. when blended with highly water sol. phosphorus (P) fertilizers such as monoammonium phosphate (MAP). Maize and soybean were fertilized using a gradient of struvite substitution for MAP, entailing five struvite: MAP blends in a factorial combination with struvite granule size (1.5, 3.0 mm diam.) and fertilizer placement (incorporation, banding). Crop biomass, and P and N uptake (total, concn.) were used to evaluate crop response, and post-harvest soil Mehlich-3 P was measured to assess sol. P loss risk. Maize biomass response was similar using up to 50% struvite and similar in soybean using up to 25% struvite. Total P uptake by maize was similar across 0-75% struvite blends, but significantly lower for 100% struvite. Maize apparent fertilizer P uptake and apparent fertilizer P uptake efficiency was greatest for 100% MAP. Despite differences in biomass, soybean apparent fertilizer P uptake and apparent P use efficiency were similar across struvite blends. Soybean P uptake was significantly greater when fertilized with 100% struvite than with 25 and 50% struvite. Inverse correlation of plant P and N concns. with biomass indicated a biomass diln. effect. Residual soil Mehlich-3 P decreased with increasing struvite substitution of MAP. Struvite:MAP blends (25-50% struvite) appear to lower sol. P loss risk compared to MAP without restricting early season (vegetative) growth of maize and soybean, and this can differ by crop species.
    20. 20
      Anderson, R. S. Struvite Behavior and Effects as a Fertilizer-Phosphorus Source Among Arkansas Soils; University of Arkansas, 2020.
      There is no corresponding record for this reference.
    21. 21
      Römer, W.; Steingrobe, B. Fertilizer effect of phosphorus recycling products. Sustainability 2018, 10, 1166,  DOI: 10.3390/su10041166
      There is no corresponding record for this reference.
    22. 22
      Steckenmesser, D.; Vogel, C.; Adam, C.; Steffens, D. Effect of various types of thermochemical processing of sewage sludges on phosphorus speciation, solubility, and fertilization performance. Waste Manage. 2017, 62, 194– 203,  DOI: 10.1016/j.wasman.2017.02.019
      22
      Effect of various types of thermochemical processing of sewage sludges on phosphorus speciation, solubility, and fertilization performance
      Steckenmesser, Daniel; Vogel, Christian; Adam, Christian; Steffens, Diedrich
      Waste Management (Oxford, United Kingdom) (2017), 62 (), 194-203CODEN: WAMAE2; ISSN:0956-053X. (Elsevier Ltd.)
      Sewage sludge has one of the highest phosphorus (P) recovery potentials of all waste materials. Therefore, P-recycling from sewage sludge could contribute to closing the P-cycle. Recently, various thermal processes for P-recovery have been developed, but there is still a demand for information on the effect of different process parameters (e.g. additives and temp.) on P-speciation and esp. on the fertilization performance. In the present study, two common methods (low-temp. conversion at 400-500°C and thermochem. treatment at 950°C) were investigated and combined to produce highly bioavailable P-fertilizers from two different types of sewage sludge based on chem. phosphorus pptn. (Chem-P) and enhanced biol. phosphorus removal (Bio-P). The results of P-fractionation, X-ray diffraction anal., and pot expts. with maize showed that Bio-P sludges attain high P-plant-availability after treatment at low temps. (400°C). In contrast, Chem-P sludges can adequately be treated at higher temps. under reductive conditions with sodium additives to form highly bioavailable calcium-sodium-phosphate. Addnl., also highly heavy-metal contaminated sludges can be thermochem. treated at high temps. to achieve the legal requirements for fertilizers.
    23. 23
      Muys, M.; Phukan, R.; Brader, G.; Samad, A.; Moretti, M.; Haiden, B.; Pluchon, S.; Roest, K.; Vlaeminck, S. E.; Spiller, M. A systematic comparison of commercially produced struvite: Quantities, qualities and soil-maize phosphorus availability. Sci. Total Environ. 2021, 756, 143726,  DOI: 10.1016/j.scitotenv.2020.143726
      23
      A systematic comparison of commercially produced struvite: Quantities, qualities and soil-maize phosphorus availability
      Muys, Maarten; Phukan, Rishav; Brader, Gunter; Samad, Abdul; Moretti, Michele; Haiden, Barbara; Pluchon, Sylvain; Roest, Kees; Vlaeminck, Siegfried E.; Spiller, Marc
      Science of the Total Environment (2021), 756 (), 143726CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
      Prodn. of struvite (MgNH4PO4·6H2O) from waste streams is increasingly implemented to recover phosphorus (P), which is listed as a crit. raw material in the European Union (EU). To facilitate EU-wide trade of P-contg. secondary raw materials such as struvite, the EU issued a revised fertilizer regulation in 2019. A comprehensive overview of the supply of struvite and its quality is presently missing. This study aimed: (i) to det. the current EU struvite prodn. vols., (ii) to evaluate all legislated physicochem. characteristics and pathogen content of European struvite against newly set regulatory limits, and (iii) to compare not-regulated struvite characteristics. It is estd. that in 2020, between 990 and 1250 ton P are recovered as struvite in the EU. Struvite from 24 European prodn. plants, accounting for 30% of the 80 struvite installations worldwide was sampled. Three samples failed the physicochem. legal limits; one had a P content of <7% and three exceeded the org. carbon content of 3% dry wt. (DW). Mineralogical anal. revealed that six samples had a struvite content of 80-90% DW, and 13 samples a content of >90% DW. All samples showed a heavy metal content below the legal limits. Microbiol. analyses indicated that struvite may exceed certain legal limits. Differences in morphol. and particle size distribution were obsd. for struvite sourced from digestate (rod shaped; transparent; 82 mass% < 1 mm), dewatering liquor (spherical; opaque; 65 mass% 1-2 mm) and effluent from upflow anaerobic sludge blanket reactor processing potato wastewater (spherical; opaque; 51 mass% < 1 mm and 34 mass% > 2 mm). A uniform soil-plant P-availability pattern of 3.5-6.5 mg P/L soil/d over a 28 days sampling period was obsd. No differences for plant biomass yield were obsd. In conclusion, the results highlight the suitability of most struvite to enter the EU fertilizer market.
    24. 24
      Wernet, G.; Bauer, C.; Steubing, B.; Reinhard, J.; Moreno-Ruiz, E.; Weidema, B. The ecoinvent database version 3 (part I): overview and methodology. Int. J. Life Cycle Assess. 2016, 21, 1218– 1230,  DOI: 10.1007/s11367-016-1087-8
      There is no corresponding record for this reference.
    25. 25
      Miller-Robbie, L.; Ulrich, B. A.; Ramey, D. F.; Spencer, K. S.; Herzog, S. P.; Cath, T. Y.; Stokes, J. R.; Higgins, C. P. Life cycle energy and greenhouse gas assessment of the co-production of biosolids and biochar for land application. J. Cleaner Prod. 2015, 91, 118– 127,  DOI: 10.1016/j.jclepro.2014.12.050
      25
      Life cycle energy and greenhouse gas assessment of the co-production of biosolids and biochar for land application
      Miller-Robbie, Leslie; Ulrich, Bridget A.; Ramey, Dotti F.; Spencer, Kathryn S.; Herzog, Skuyler P.; Cath, Tzahi Y.; Stokes, Jennifer R.; Higgins, Christopher P.
      Journal of Cleaner Production (2015), 91 (), 118-127CODEN: JCROE8; ISSN:0959-6526. (Elsevier Ltd.)
      The co-prodn. and co-application to land of biochar and biosolids may make conventional wastewater treatment more sustainable; therefore, this study provides a first life cycle evaluation of the co-location of a pyrolysis (biochar prodn.) plant with a municipal wastewater treatment plant. Life cycle energy use and greenhouse gas emissions are evaluated for the co-prodn. of these two materials. Three US national scenarios are included: biosolids only produced and disposed of as is the current common practice in the US (landfilled, incinerated, and land applied); biosolids only produced but not land applied; and co-prodn. of biosolids and biochar and their disposal as currently practiced. A case study is also presented with slightly different disposal practices. Large contributors to life cycle greenhouse gas emissions are from the disposal of biosolids in landfills and incinerators, making alternatives like land application attractive for mitigating greenhouse gas emissions. The addn. of biochar prodn. adds little to the overall energy use but provides substantial (26%) redn. in greenhouse gas emissions for the national case, largely due to the recalcitrant carbon storage in biochar. Because biochar prodn. is an energy pos. process, incorporation of the energy co-products into the plant is explored for producing high quality Class A biosolids. The addn. of biochar to biosolids is shown to be more sustainable from a co-prodn. standpoint. This study contributes a benchmark anal. in evaluating the co-prodn. of biochar and biosolids for potential environmental, economic, and health benefits and the results are useful for utility planning.
    26. 26
      Bare, J. TRACI 2.0: The tool for the reduction and assessment of chemical and other environmental impacts 2.0. Clean Technol. Environ. Policy 2011, 13, 687– 696,  DOI: 10.1007/s10098-010-0338-9
      26
      TRACI 2.0: the tool for the reduction and assessment of chemical and other environmental impacts 2.0
      Bare, Jane
      Clean Technologies and Environmental Policy (2011), 13 (5), 687-696CODEN: CTEPAI; ISSN:1618-954X. (Springer)
      A review with 85 refs. TRACI 2.0, the Tool for the Redn. and Assessment of Chem. and other environmental Impacts 2.0, has been expanded and developed for sustainability metrics, life cycle impact assessment, industrial ecol., and process design impact assessment for developing increasingly sustainable products, processes, facilities, companies, and communities. TRACI 2.0 allows the quantification of stressors that have potential effects, including ozone depletion, global warming, acidification, eutrophication, tropospheric ozone (smog) formation, human health criteria-related effects, human health cancer, human health noncancer, ecotoxicity, and fossil fuel depletion effects. Research is going on to quantify the use of land and water in a future version of TRACI. The original version of TRACI released in August 2002 (Bare et al. J Ind Ecol 6:49-78, 2003) has been used in many prestigious applications including: the US Green Building Council's LEED Certification (US Green Building Council, Welcome to US Green Building Council, 2008), the National Institute of Stds. and Technol.'s BEES (Building for Environment and Economic Sustainability) (Lippiatt, BEES 4.0: building for environmental and economic sustainability tech. manual and user guide, 2007) which is used by US EPA for Environmentally Preferable Purchasing (US Environmental Protection Agency, Environmentally Preferable Purchasing (EPP), 2008d), the US Marine Corps' EKAT (Environmental Knowledge and Assessment Tool) for military and nonmilitary uses (US Marine Corps, Environmental knowledge and assessment tool (EKAT): first time user's guide, 2007), and within numerous college curriculums in engineering and design departments.
    27. 27
      Finnveden, G.; Hauschild, M. Z.; Ekvall, T.; Guinée, J.; Heijungs, R.; Hellweg, S.; Koehler, A.; Pennington, D.; Suh, S. Recent developments in Life Cycle Assessment. J. Environ. Manage. 2009, 91, 1– 21,  DOI: 10.1016/j.jenvman.2009.06.018
      27
      Recent developments in Life Cycle Assessment
      Finnveden Goran; Hauschild Michael Z; Ekvall Tomas; Guinee Jeroen; Heijungs Reinout; Hellweg Stefanie; Koehler Annette; Pennington David; Suh Sangwon
      Journal of environmental management (2009), 91 (1), 1-21 ISSN:.
      Life Cycle Assessment is a tool to assess the environmental impacts and resources used throughout a product's life cycle, i.e., from raw material acquisition, via production and use phases, to waste management. The methodological development in LCA has been strong, and LCA is broadly applied in practice. The aim of this paper is to provide a review of recent developments of LCA methods. The focus is on some areas where there has been an intense methodological development during the last years. We also highlight some of the emerging issues. In relation to the Goal and Scope definition we especially discuss the distinction between attributional and consequential LCA. For the Inventory Analysis, this distinction is relevant when discussing system boundaries, data collection, and allocation. Also highlighted are developments concerning databases and Input-Output and hybrid LCA. In the sections on Life Cycle Impact Assessment we discuss the characteristics of the modelling as well as some recent developments for specific impact categories and weighting. In relation to the Interpretation the focus is on uncertainty analysis. Finally, we discuss recent developments in relation to some of the strengths and weaknesses of LCA.
    28. 28
      De-Bashan, L. E.; Bashan, Y. Recent advances in removing phosphorus from wastewater and its future use as fertilizer (1997-2003). Water Res. 2004, 38, 4222– 4246,  DOI: 10.1016/j.watres.2004.07.014
      28
      Recent advances in removing phosphorus from wastewater and its future use as fertilizer (1997-2003)
      de-Bashan, Luz E.; Bashan, Yoav
      Water Research (2004), 38 (19), 4222-4246CODEN: WATRAG; ISSN:0043-1354. (Elsevier B.V.)
      A review. Large quantities of phosphate present in wastewater is one of the main causes of eutrophication that neg. affects many natural water bodies, both fresh water and marine. It is desirable that water treatment facilities remove phosphorus from the wastewater before they are returned to the environment. Total removal or at least a significant redn. of phosphorus is obligatory, if not always fulfilled, in most countries. This comprehensive review summarizes the current status in phosphorus-removal technologies from the most common approaches, like metal pptn., constructed wetland systems, adsorption by various microorganisms either in a free state or immobilized in polysaccharide gels, to enhanced biol. phosphorus removal using activated sludge systems, and several innovative engineering solns. As chem. pptn. renders the ppts. difficult, if not impossible, to recycle in an economical industrial manner, biol. removal opens opportunities for recovering most of the phosphorus and beneficial applications of the product. This review includes the options of struvite (ammonium magnesium phosphate) and hydroxyapatite formation and other feasible options using, the now largely regarded contaminant, phosphorus in wastewater, as a raw material for the fertilizer industry. Besides updating our knowledge, this review critically evaluates the advantage and difficulties behind each treatment and indicates some of the most relevant open questions for future research.
    29. 29
      Cornel, P.; Schaum, C. Phosphorus recovery from wastewater: Needs, technologies and costs. Water Sci. Technol. 2009, 59, 1069– 1076,  DOI: 10.2166/wst.2009.045
      29
      Phosphorus recovery from wastewater: needs, technologies and costs
      Cornel, P.; Schaum, C.
      Water Science and Technology (2009), 59 (6), 1069-1076CODEN: WSTED4; ISSN:0273-1223. (IWA Publishing)
      A review. Phosphorus is an essential, yet limited resource, which cannot be replaced by any other element. This is why there are increasing efforts to recycle phosphorus contained in wastewater. It involves the recovery of phosphorus and, normally, the sepn. of phosphates from harmful substances. Phosphorus can be recovered from wastewater, sewage sludge, as well as from the ash of incinerated sewage sludge, and can be combined with phosphorus removal in most cases. The phosphorus recovery rate from the liq. phase can reach 40 to 50% at the most, while recovery rates from sewage sludge and sewage sludge ash can reach up to 90%. There are various methods which can be applied for phosphorus recovery. Up to now, there is limited experience in industrial-scale implementation. The costs for recovered phosphate exceed the costs for phosphate from rock phosphate by several times. For German conditions, the specific addnl. costs of wastewater treatment by integrating phosphorus recovery can be estd. at euro2-6 per capita and year.
    30. 30
      Solon, K.; Lam, K. L.; Jia, M.; Volcke, E. I. P. Benchmarking of phosphorus recovery strategies from wastewater. In preparation.
      There is no corresponding record for this reference.
    31. 31
      Alanya, S.; Dewulf, J.; Duran, M. Comparison of Overall Resource Consumption of Biosolids Management System Processes Using Exergetic Life Cycle Assessment. Environ. Sci. Technol. 2015, 49, 9996– 10006,  DOI: 10.1021/acs.est.5b03124
      31
      Comparison of overall resource consumption of biosolids management system processes using exergetic life cycle assessment
      Alanya, Sevda; Dewulf, Jo; Duran, Metin
      Environmental Science & Technology (2015), 49 (16), 9996-10006CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      This study focused on the evaluation of biosolids management systems (BMS) from a natural resource consumption point of view. Addnl., the environmental impact of the facilities was benchmarked using Life Cycle Assessment (LCA) to provide a comprehensive assessment. This is the first study to apply a Cumulative Exergy Extn. from the Natural Environment (CEENE) method for an in-depth resource use assessment of BMS where two full-scale BMS and seven system variations were analyzed. CEENE allows better system evaluation and understanding of how much benefit is achievable from the products generated by BMS, which have valorization potential. LCA results showed that environmental burden is mostly from the intense electricity consumption. The CEENE anal. further revealed that the environmental burden is due to the high consumption of fossil and nuclear-based natural resources. Using Cumulative Degree of Perfection, higher resource-use efficiency, 53%, was obsd. in the PTA-2 where alk. stabilization rather than anaerobic digestion is employed. However, an anaerobic digestion process is favorable over alk. stabilization, with 35% lower overall natural resource use. The most significant redn. of the resource footprint occurred when the output biogas was valorized in a combined heat and power system.
    32. 32
      Solon, K.; Volcke, E. I. P.; Spérandio, M.; Van Loosdrecht, M. C. M. Resource recovery and wastewater treatment modelling. Environ. Sci.: Water Res. Technol. 2019, 5, 631– 642,  DOI: 10.1039/c8ew00765a
      32
      Resource recovery and wastewater treatment modelling
      Solon, Kimberly; Volcke, Eveline I. P.; Sperandio, Mathieu; van Loosdrecht, Mark C. M.
      Environmental Science: Water Research & Technology (2019), 5 (4), 631-642CODEN: ESWRAR; ISSN:2053-1419. (Royal Society of Chemistry)
      Traditional wastewater treatment plants (WWTPs) are increasingly regarded as water resource recovery facilities (WRRFs), reflecting the value of water, nutrients, energy and other resources, besides ensuring the required effluent quality. Resource recovery techniques involve biochem., phys. and physico-chem. processes, and even previously unexploited biol. conversions. Biopolymer and bioplastic prodn. also reveal the remarkable potential present in our microbial cultures. Models have demonstrated their usefulness to optimize WWTP operation to achieve better effluent quality at lower costs; they also constitute a useful tool to support the transition of WWTPs into WRRFs that maximize the valorization of products recovered from wastewater. In this paper, the extent to which the new techniques and unit processes applied for resource recovery could be modelled with conventional activated sludge models (ASMs) and addnl. modeling challenges being faced are discussed while providing recommendations of potential approaches to address current modeling research gaps.
    33. 33
      Bisinella de Faria, A. B.; Spérandio, M.; Ahmadi, A.; Tiruta-Barna, L. Evaluation of new alternatives in wastewater treatment plants based on dynamic modelling and life cycle assessment (DM-LCA). Water Res. 2015, 84, 99– 111,  DOI: 10.1016/j.watres.2015.06.048
      33
      Evaluation of new alternatives in wastewater treatment plants based on dynamic modelling and life cycle assessment (DM-LCA)
      Bisinella de Faria, A. B.; Sperandio, M.; Ahmadi, A.; Tiruta-Barna, L.
      Water Research (2015), 84 (), 99-111CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
      With a view to quantifying the energy and environmental advantages of Urine Source-Sepn. (USS) combined with different treatment processes, five wastewater treatment plant (WWTP) scenarios were compared to a ref. scenario using Dynamic Modeling (DM) and Life Cycle Assessment (LCA), and an integrated DM-LCA framework was thus developed. Dynamic simulations were carried out in BioWin in order to obtain a realistic evaluation of the dynamic behavior and performance of plants under perturbation. LCA calcns. were performed within Umberto using the Ecoinvent database. A Python interface was used to integrate and convert simulation data and to introduce them into Umberto to achieve a complete LCA evaluation comprising foreground and background processes. Comparisons between steady-state and dynamic simulations revealed the importance of considering dynamic aspects such as nutrient and flow peaks. The results of the evaluation highlighted the potential of the USS scenario for nutrient recovery whereas the Enhanced Primary Clarification (EPC) scenario gave increased biogas prodn. and also notably decreased aeration consumption, leading to a pos. energy balance. Both USS and EPC scenarios also showed increased stability of plant operation, with smaller daily avs. of total nitrogen and phosphorus. In this context, USS and EPC results demonstrated that the coupled USS + EPC scenario and its combinations with agricultural spreading of N-rich effluent and nitritation/anaerobic deammonification could present an energy-pos. balance with resp. 27% and 33% lower energy requirements and an increase in biogas prodn. of 23%, compared to the ref. scenario. The coupled scenarios also presented lesser environmental impacts (redn. of 31% and 39% in total endpoint impacts) along with effluent quality well within the specified limits. The marked environmental performance (redn. of global warming) when nitrogen is used in agriculture shows the importance of future research on sustainable solns. for nitrogen recovery. The contribution anal. of midpoint impacts also showed hotspots that it will be important to optimize further, such as plant infrastructure and direct N2O emissions.
    34. 34
      Sena, M.; Hicks, A. Life cycle assessment review of struvite precipitation in wastewater treatment. Resour., Conserv. Recycl. 2018, 139, 194– 204,  DOI: 10.1016/j.resconrec.2018.08.009
      There is no corresponding record for this reference.
    35. 35
      Flores-Alsina, X.; Solon, K.; Kazadi Mbamba, C.; Tait, S.; Gernaey, K. V.; Jeppsson, U.; Batstone, D. J. Modelling phosphorus (P), sulfur (S) and iron (Fe) interactions for dynamic simulations of anaerobic digestion processes. Water Res. 2016, 95, 370– 382,  DOI: 10.1016/j.watres.2016.03.012
      35
      Modelling phosphorus (P), sulfur (S) and iron (Fe) interactions for dynamic simulations of anaerobic digestion processes
      Flores-Alsina, Xavier; Solon, Kimberly; Kazadi Mbamba, Christian; Tait, Stephan; Gernaey, Krist V.; Jeppsson, Ulf; Batstone, Damien J.
      Water Research (2016), 95 (), 370-382CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)
      This paper proposes a series of extensions to functionally upgrade the IWA Anaerobic Digestion Model No. 1 (ADM1) to allow for plant-wide phosphorus (P) simulation. The close interplay between the P, sulfur (S) and iron (Fe) cycles requires a substantial (and unavoidable) increase in model complexity due to the involved three-phase physico-chem. and biol. transformations. The ADM1 version, implemented in the plant-wide context provided by the Benchmark Simulation Model No. 2 (BSM2), is used as the basic platform (A0). Three different model extensions (A1, A2, A3) are implemented, simulated and evaluated. The first extension (A1) considers P transformations by accounting for the kinetic decay of polyphosphates (XPP) and potential uptake of volatile fatty acids (VFA) to produce polyhydroxyalkanoates (XPHA) by phosphorus accumulating organisms (XPAO). Two variant extensions (A2,1/A2,2) describe biol. prodn. of sulfides (SIS) by means of sulfate reducing bacteria (XSRB) utilizing hydrogen only (autolithotrophically) or hydrogen plus org. acids (heterorganotrophically) as electron sources, resp. These two approaches also consider a potential hydrogen sulfide (ZH2S) inhibition effect and stripping to the gas phase (GH2S). The third extension (A3) accounts for chem. iron (III) (SFe3+) redn. to iron (II) (SFe2+) using hydrogen (SH2) and sulfides (SIS) as electron donors. A set of pre/post interfaces between the Activated Sludge Model No. 2d (ASM2d) and ADM1 are furthermore proposed in order to allow for plant-wide (model-based) anal. and study of the interactions between the water and sludge lines. Simulation (A1 - A3) results show that the ratio between sol./particulate P compds. strongly depends on the pH and cationic load, which dets. the capacity to form (or not) pptn. products. Implementations A1 and A2,1/A2,2 lead to a redn. in the predicted methane/biogas prodn. (and potential energy recovery) compared to ref. ADM1 predictions (A0). This redn. is attributed to two factors: (1) loss of electron equiv. due to sulfate (SSO4) redn. by XSRB and storage of XPHA by XPAO; and, (2) decrease of acetoclastic and hydrogenotrophic methanogenesis due to ZH2S inhibition. Model A3 shows the potential for iron to remove free SIS (and consequently inhibition) and instead promote iron sulfide (XFeS) pptn. It also reduces the quantities of struvite (XMgNH4PO4) and calcium phosphate (XCa3(PO4)2) that are formed due to its higher affinity for phosphate anions. This study provides a detailed anal. of the different model assumptions, the effect that operational/design conditions have on the model predictions and the practical implications of the proposed model extensions in view of plant-wide modeling/development of resource recovery strategies.
    36. 36
      Sena, M.; Seib, M.; Noguera, D. R.; Hicks, A. Environmental impacts of phosphorus recovery through struvite precipitation in wastewater treatment. J. Cleaner Prod. 2021, 280, 124222,  DOI: 10.1016/j.jclepro.2020.124222
      36
      Environmental impacts of phosphorus recovery through struvite precipitation in wastewater treatment
      Sena, Madeline; Seib, Matthew; Noguera, Daniel R.; Hicks, Andrea
      Journal of Cleaner Production (2021), 280 (Part_1), 124222CODEN: JCROE8; ISSN:0959-6526. (Elsevier Ltd.)
      Wastewater treatment currently focuses on removing phosphorus (P) and nitrogen (N) due to their potential to cause eutrophication in bodies of water. With growing concern for the longevity of global phosphate rock stores, however, there is now interest in recovering these nutrients. One method for recovering P and N is through the pptn. of struvite (magnesium ammonium phosphate) which also helps control unwanted struvite pptn. in pipes and on other surfaces at the treatment plant lessening a challenging maintenance problem, and produces a valuable alternative fertilizer product. A potential concern is that the environmental impacts struvite recovery creates through the use of addnl. chems. and energy are not offset by its benefits. A life cycle assessment (LCA) case study of the full-scale wastewater treatment plant (WWTP) in Madison, WI USA was used to assess the environmental tradeoffs of struvite recovery in wastewater treatment. When only the struvite recovery system was considered, a portion of the environmental impact categories considered showed an overall environmental cost, while others showed a benefit, due to the phosphorus recovered. When the full scale WWTP was considered, there was an overall environmental impact to treating the wastewater, as there was prior to the struvite system deployment. However, due to the addnl. benefit of the struvite recovery, the overall environmental impacts of the WWTP are similar.
    37. 37
      Mavhungu, A.; Foteinis, S.; Mbaya, R.; Masindi, V.; Kortidis, I.; Mpenyana-Monyatsi, L.; Chatzisymeon, E. Environmental sustainability of municipal wastewater treatment through struvite precipitation: Influence of operational parameters. J. Cleaner Prod. 2021, 285, 124856,  DOI: 10.1016/j.jclepro.2020.124856
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      Environmental sustainability of municipal wastewater treatment through struvite precipitation: Influence of operational parameters
      Mavhungu, Avhafunani; Foteinis, Spyros; Mbaya, Richard; Masindi, Vhahangwele; Kortidis, Ioannis; Mpenyana-Monyatsi, Lizzy; Chatzisymeon, Efthalia
      Journal of Cleaner Production (2021), 285 (), 124856CODEN: JCROE8; ISSN:0959-6526. (Elsevier Ltd.)
      The environmental sustainability of wastewater treatment through phosphate (P) and ammonia (N) chem. pptn. (struvite) was examd. using the life cycle assessment methodol. Thermally activated (calcined) cryptocryst. magnesite was used towards struvite formation and four process parameters (contact time, magnesite dosage, initial wastewater pH and temp.) were studied. Raising wastewater's temp. to promote ammonia stripping was found to be environmentally unsound. Magnesite dosage and contact time were identified as environmental hotspots, but not pH. In terms of environmental relevance, when using ReCiPe 2016 life cycle impact assessment method, the human health damage category was mostly affected, followed by resource availability, while ecosystems category was affected to a much lesser extent. Environmental impacts were grossly attributed to South Africa's fossil fuel-dependent energy mix, suggesting that renewable energy could largely improve the system's environmental performance. The optimal conditions, from the environmental perspective, were found to be 0.2 g L-1 feed dosage and 10 min mixing, at ambient temp. and pH (total environmental footprint 60.9μPt per treated L of wastewater). To improve N removal efficacy, which is desirable in real-world applications, higher feed dosages and mixing durations are required, albeit at the expense of environmental sustainability (e.g. the 180 min and 16 g L-1 environmental footprint sharply rises to 1.87μPt L-1). The net impact approach revealed that the avoided environmental impacts on the midpoint impact categories freshwater and marine eutrophication grossly outweigh the corresponding environmental impacts of the treatment process. Results suggest that when using a low contact time and magnesite dosage, struvite pptn. could act as a fast, efficient, and environmentally friendly pretreatment step to practically remove P and grossly reduce N from wastewater. On the other hand, with higher feed dosages and mixing durations, struvite pptn. could act as a promising secondary wastewater treatment method with an overall low environmental footprint. Overall, results complement the existing body of knowledge on the techno-economic performance of such systems and provide insight to decision- and policy-makers to sustainably scale up the process, at village- or industrial-level, in rural South Africa, Lesotho, and further afield.
    38. 38
      Sørensen, B. L.; Dall, O. L.; Habib, K. Environmental and resource implications of phosphorus recovery from waste activated sludge. Waste Manage. 2015, 45, 391– 399,  DOI: 10.1016/j.wasman.2015.02.012
      38
      Environmental and resource implications of phosphorus recovery from waste activated sludge
      Sorensen Birgitte Lilholt; Dall Ole Leinikka; Habib Komal
      Waste management (New York, N.Y.) (2015), 45 (), 391-9 ISSN:.
      Phosphorus is an essential mineral resource for the growth of crops and thus necessary to feed the ever increasing global population. The essentiality and irreplaceability of phosphorus in food production has raised the concerns regarding the long-term phosphorus availability and the resulting food supply issues in the future. Hence, the recovery of phosphorus from waste activated sludge and other waste streams is getting huge attention as a viable solution to tackle the potential availability issues of phosphorus in the future. This study explores the environmental implications of phosphorus recovery from waste activated sludge in Denmark and further elaborates on the potential availability or scarcity issue of phosphorus today and 2050. Life cycle assessment is used to assess the possibility of phosphorus recovery with little or no environmental impacts compared to the conventional mining. The phosphorus recovery method assessed in this study consists of drying process, and thermal gasification of the waste activated sludge followed by extraction of phosphorus from the ashes. Our results indicate that the environmental impacts of phosphorus recovery in an energy efficient process are comparable to the environmental effects from the re-use of waste activated sludge applied directly on farmland. Moreover, our findings conclude that the general recommendation according to the waste hierarchy, where re-use of the waste sludge on farmland is preferable to material and energy recovery, is wrong in this case. Especially when phosphorus is a critical resource due to its life threatening necessity, lack of substitution options and potential future supply risk originating due to the high level of global supply concentration.
    39. 39
      Linderholm, K.; Tillman, A.-M.; Mattsson, J. E. Life cycle assessment of phosphorus alternatives for Swedish agriculture. Resour., Conserv. Recycl. 2012, 66, 27– 39,  DOI: 10.1016/j.resconrec.2012.04.006
      There is no corresponding record for this reference.
    40. 40
      Egle, L.; Rechberger, H.; Krampe, J.; Zessner, M. Phosphorus recovery from municipal wastewater: An integrated comparative technological, environmental and economic assessment of P recovery technologies. Sci. Total Environ. 2016, 571, 522– 542,  DOI: 10.1016/j.scitotenv.2016.07.019
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      Phosphorus recovery from municipal wastewater: An integrated comparative technological, environmental and economic assessment of P recovery technologies
      Egle, L.; Rechberger, H.; Krampe, J.; Zessner, M.
      Science of the Total Environment (2016), 571 (), 522-542CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
      Several technologies have been developed in recent years to recover wastewater P. However, these technologies target different P-contg. flows in wastewater treatment plants (effluent, digester supernatant, sewage sludge, and sewage sludge ash), use diverse engineering approaches and differ greatly with respect to P recycling rate, potential of removing or destroying pollutants, product quality, environmental impact and cost. This work compares 19 relevant P recovery technologies by considering their relations with existing wastewater and sludge treatment systems. A combination of different methods, such as material flow anal., damage units, ref. soil method, annuity method, integrated cost calcn. and a literature study on soly., fertilizing effects and handling of recovered materials, is used to evaluate the different technologies with respect to tech., ecol. and economic aspects. With regard to the manifold origins of data an uncertainty concept considering validity of data sources is applied. This anal. revealed that recovery from flows with dissolved P produces clean and plant-available materials. These techniques may even be beneficial from economic and tech. perspectives under specific circumstances. However, the recovery rates (max. 25%) relative to the wastewater treatment plant influent are relatively low. The approaches that recover P from sewage sludge apply complex technologies and generally achieve effective removal of heavy metals at moderate recovery rates (∼40-50% relative to the WWTP input) and comparatively high costs. Sewage sludge ash is the most promising P source, with recovery rates of 60-90% relative to the wastewater P. The costs highly depend on the purity requirements of the recycled products but can be kept comparatively low, esp. if synergies with existing industrial processes are exploited.
    41. 41
      Santos, A. F.; Almeida, P. V.; Alvarenga, P.; Gando-Ferreira, L. M.; Quina, M. J. From wastewater to fertilizer products: Alternative paths to mitigate phosphorus demand in European countries. Chemosphere 2021, 284, 131258,  DOI: 10.1016/j.chemosphere.2021.131258
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      Alternative paths to mitigate phosphorus demand from wastewater to fertilizer products in European countries
      Santos, Andreia F.; Almeida, Patricia V.; Alvarenga, Paula; Gando-Ferreira, Licinio M.; Quina, Margarida J.
      Chemosphere (2021), 284 (), 131258CODEN: CMSHAF; ISSN:0045-6535. (Elsevier Ltd.)
      A review. Phosphorus (P) is a non-renewable resource, irreplaceable for life and food prodn., and currently considered a Crit. Raw Material to the European Union (EU). Due to concerns about the rate of consumption and limited reserves in countries with sensitive geopolitical contexts, it is urgent to recover P from urban and industrial flows. Indeed, the municipal wastewater treatment plants (WWTP) are considered relevant sources with several hot spots, esp. sewage sludge with estd. recovery efficiencies of >80%. The most promising recovery strategies are based on thermal treatments (e.g., incineration of sludge) following by wet-chem. or thermo-chem. leaching, pptn., and adsorption. The direct application of sludge on soil is no longer a primary route for P reintegration in the value-chain for countries as Switzerland, Germany, and The Netherlands. In fact, Switzerland and Austria paved the way for implementing P recovery legislation, focusing on recovery from raw sewage sludge or ashes. Indeed, industrial technologies with sludge ash as input show high recovery efficiencies (Ashdec and Leachphos with 98 and 79%) and lower environmental impacts, whereas Pearl technol. has about 12% recovery efficiency with wastewater as input. After all, struvite emerges as the most recovered product with recent access to the internal market of EU fertilisers and similar growth performance compared to triple-super-phosphate. However, several studies leave open the possibility of introducing loaded adsorbents with P as soil amendments as a new alternative to conventional desorption. Briefly, P recovery should be a compromise between efficiency, environmental impacts, and economic revenues from the final products.
    42. 42
      Nemecek, T.; Jungbluth, N.; i Canals, L. M.; Schenck, R. Environmental impacts of food consumption and nutrition: where are we and what is next?. Int. J. Life Cycle Assess. 2016, 21, 607– 620,  DOI: 10.1007/s11367-016-1071-3
      There is no corresponding record for this reference.
    43. 43
      Trimmer, J. T.; Margenot, A. J.; Cusick, R. D.; Guest, J. S. Aligning Product Chemistry and Soil Context for Agronomic Reuse of Human-Derived Resources. Environ. Sci. Technol. 2019, 53, 6501– 6510,  DOI: 10.1021/acs.est.9b00504
      43
      Aligning Product Chemistry and Soil Context for Agronomic Reuse of Human-Derived Resources
      Trimmer, John T.; Margenot, Andrew J.; Cusick, Roland D.; Guest, Jeremy S.
      Environmental Science & Technology (2019), 53 (11), 6501-6510CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Recovering human-derived nutrients from sanitation systems can offset inorg. fertilizer use and improve access to agricultural nutrients in resource-limited settings, but the agronomic value of recovered products depends upon product chem. and soil context. Products may exacerbate already-compromised soil conditions, offer benefits beyond nutrients, or have reduced efficacy depending on soil characteristics. Using global spatial modeling, we evaluate the soil suitability of seven products (wastewater, sludge, compost, urine, ammonium sulfate, ammonium struvite, potassium struvite) and integrate this information with local recovery potential of each product from sanitation systems that will need to be installed to achieve universal coverage (referred to here as "newly-installed sanitation"). If product recovery and reuse are colocated, the quantity and suitability of nutrient reuse was variable across countries. For example, alk. products (e.g., struvite) may be particularly beneficial when applied to acidic soils in Uganda but potentially detrimental in the southwestern United States. Further, we illustrate discrepancies across soil data sets and highlight the need for locally accurate data, knowledge, and interpretation. Overall, this study demonstrates soil context is crit. to comprehensively characterize the value proposition of nutrient recovery, and it provides a foundation for incorporating soil suitability into local and global sanitation decision-making.
    44. 44
      Muys, M.; Phukan, R.; Brader, G.; Samad, A.; Moretti, M.; Haiden, B.; Pluchon, S.; Roest, K.; Vlaeminck, S. E.; Spiller, M. A systematic comparison of commercially produced struvite: Quantities, qualities and soil-maize phosphorus availability. Sci. Total Environ. 2021, 756, 143726,  DOI: 10.1016/j.scitotenv.2020.143726
      44
      A systematic comparison of commercially produced struvite: Quantities, qualities and soil-maize phosphorus availability
      Muys, Maarten; Phukan, Rishav; Brader, Gunter; Samad, Abdul; Moretti, Michele; Haiden, Barbara; Pluchon, Sylvain; Roest, Kees; Vlaeminck, Siegfried E.; Spiller, Marc
      Science of the Total Environment (2021), 756 (), 143726CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
      Prodn. of struvite (MgNH4PO4·6H2O) from waste streams is increasingly implemented to recover phosphorus (P), which is listed as a crit. raw material in the European Union (EU). To facilitate EU-wide trade of P-contg. secondary raw materials such as struvite, the EU issued a revised fertilizer regulation in 2019. A comprehensive overview of the supply of struvite and its quality is presently missing. This study aimed: (i) to det. the current EU struvite prodn. vols., (ii) to evaluate all legislated physicochem. characteristics and pathogen content of European struvite against newly set regulatory limits, and (iii) to compare not-regulated struvite characteristics. It is estd. that in 2020, between 990 and 1250 ton P are recovered as struvite in the EU. Struvite from 24 European prodn. plants, accounting for 30% of the 80 struvite installations worldwide was sampled. Three samples failed the physicochem. legal limits; one had a P content of <7% and three exceeded the org. carbon content of 3% dry wt. (DW). Mineralogical anal. revealed that six samples had a struvite content of 80-90% DW, and 13 samples a content of >90% DW. All samples showed a heavy metal content below the legal limits. Microbiol. analyses indicated that struvite may exceed certain legal limits. Differences in morphol. and particle size distribution were obsd. for struvite sourced from digestate (rod shaped; transparent; 82 mass% < 1 mm), dewatering liquor (spherical; opaque; 65 mass% 1-2 mm) and effluent from upflow anaerobic sludge blanket reactor processing potato wastewater (spherical; opaque; 51 mass% < 1 mm and 34 mass% > 2 mm). A uniform soil-plant P-availability pattern of 3.5-6.5 mg P/L soil/d over a 28 days sampling period was obsd. No differences for plant biomass yield were obsd. In conclusion, the results highlight the suitability of most struvite to enter the EU fertilizer market.
    45. 45
      Degryse, F.; Baird, R.; da Silva, R. C.; McLaughlin, M. J. Dissolution rate and agronomic effectiveness of struvite fertilizers – effect of soil pH, granulation and base excess. Plant Soil 2017, 410, 139– 152,  DOI: 10.1007/s11104-016-2990-2
      45
      Dissolution rate and agronomic effectiveness of struvite fertilizers - effect of soil pH, granulation and base excess
      Degryse, Fien; Baird, Roslyn; da Silva, Rodrigo C.; McLaughlin, Mike J.
      Plant and Soil (2017), 410 (1-2), 139-152CODEN: PLSOA2; ISSN:0032-079X. (Springer)
      Aims: Struvite (MgNH4PO4.6H2O) recovered from wastewater can be used as fertilizer. The agronomic effectiveness of struvite has mostly been evaluated using ground fertilizer mixed through soil. However, fertilizers are most commonly applied in granular form in the field. In this study, we assessed the dissoln. and effectiveness of different struvites when applied in granular or powd. form. Methods: Phosphorus (P) diffusion in soil, detd. using a visualization technique and chem. analyses, and P uptake by 6-wk old wheat was compared for sol. fertilizer (monoammonium phosphate, MAP), a com. struvite and three synthesized struvites with different excess MgO, in both granular and ground form. Results: Ground struvite mixed through soil quickly dissolved and its agronomic effectiveness was similar to that of MAP. For pure granular struvite, the granule dissoln. rate ranged from circa 0.03 mg d-1 in alk. soil to 0.43 mg d-1 in acidic soil. Excess base in the struvite fertilizer reduced its dissoln. rate. The P uptake by wheat followed the order MAP > > struvite ≥ control (no P), with no significant difference between the control and the struvite treatment in alk. soil. Conclusions: Both fertilizer characteristics (particle size, excess base) and soil pH strongly affect the dissoln. rate of struvite and hence its agronomic effectiveness.
    46. 46
      Diaz-Elsayed, N.; Rezaei, N.; Guo, T.; Mohebbi, S.; Zhang, Q. Wastewater-based resource recovery technologies across scale: A review. Resour., Conserv. Recycl. 2019, 145, 94– 112,  DOI: 10.1016/j.resconrec.2018.12.035
      There is no corresponding record for this reference.
    47. 47
      Pradel, M.; Aissani, L. Environmental impacts of phosphorus recovery from a “product” Life Cycle Assessment perspective: Allocating burdens of wastewater treatment in the production of sludge-based phosphate fertilizers. Sci. Total Environ. 2019, 656, 55– 69,  DOI: 10.1016/j.scitotenv.2018.11.356
      47
      Environmental impacts of phosphorus recovery from a "product" Life Cycle Assessment perspective: Allocating burdens of wastewater treatment in the production of sludge-based phosphate fertilizers
      Pradel, Marilys; Aissani, Lynda
      Science of the Total Environment (2019), 656 (), 55-69CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
      Since phosphorus (P) is a non-renewable element essential for life, it is extremely important to explore any potential supply of P, including that recovered from human excreta and urban wastewater. This study aimed to assess, using Life Cycle Assessment (LCA), whether recovering dissipated P by producing sludge-based phosphate fertilizer can be a suitable method to reduce P depletion. Environmental impacts of four scenarios of prodn. of sludge-based phosphate fertilizers were compared to those of prodn. of triple super phosphate, a mineral phosphate fertilizer used as a ref. scenario. The novelty of this study was to est. environmental impacts of sludge-based phosphate fertilizer prodn. using a "product" LCA perspective instead of a "waste" LCA perspective. Consequently, upstream prodn. of sludge was considered by allocating part of the environmental burdens of wastewater treatment to sludge prodn. Life Cycle Impact Assessment was performed using the CML-IA characterization method. Results indicated that sludge-based phosphate fertilizers appeared less environmentally friendly than mineral phosphate fertilizers, due to the contribution of the upstream burden of sludge prodn. and P recovery. Finally, although P recovery helps preserve the mineral P resource, the overall assessment remains unfavorable for sludge-based products due to the low yields of P recovery, low P concn. of the sludge and the large amts. of energy and reactants needed to recover the P.
    48. 48
      Pradel, M.; Lippi, M.; Daumer, M.-L.; Aissani, L. Environmental performances of production and land application of sludge-based phosphate fertilizers-a life cycle assessment case study. Environ. Sci. Pollut. Res. 2020, 27, 2054– 2070,  DOI: 10.1007/s11356-019-06910-4
      48
      Environmental performances of production and land application of sludge-based phosphate fertilizers-a life cycle assessment case study
      Pradel, Marilys; Lippi, Mathilde; Daumer, Marie-Line; Aissani, Lynda
      Environmental Science and Pollution Research (2020), 27 (2), 2054-2070CODEN: ESPLEC; ISSN:0944-1344. (Springer)
      Phosphorus (P) is a non-renewable resource extd. from phosphate rock to produce agricultural fertilizers. Since P is essential for life, it is important to preserve this resource and explore alternative sources of P to reduce its criticality. This study aimed to assess whether fertilizing with sludge-based phosphate fertilizers (SBPF) can be a suitable alternative to doing so with fertilizers produced from phosphate rock. Environmental impacts of prodn. and land application of SBPF from four recovery processes were compared to those of two ref. scenarios: triple super phosphate (TSP) and sewage sludge. To avoid bias when comparing scenarios, part of the environmental burden of wastewater treatment is allocated to sludge prodn. The CML-IA method was used to perform life cycle impact assessment. Results highlighted that prodn. and land application of SBPF had higher environmental impacts than those of TSP due to the large amts. of energy and reactants needed to recover P, esp. when sludge had a low P concn. Certain environmental impacts of prodn. and land application of sewage sludge were similar to those of SBPF. Sensitivity anal. conducted for cropping systems highlighted variability in potential application rates of sewage sludge or SBPF. Finally, because they contain lower contents of heavy metals than sewage sludge or TSP, SBPF are of great interest, but they require more mineral fertilizers to supplement their fertilization than sewage sludge. Thus, SBPF have advantages and disadvantages that need to be considered, since they may influence their use within fertilization practices.
    49. 49
      Sfez, S.; De Meester, S.; Vlaeminck, S. E.; Dewulf, J. Improving the resource footprint evaluation of products recovered from wastewater: A discussion on appropriate allocation in the context of circular economy. Resour., Conserv. Recycl. 2019, 148, 132– 144,  DOI: 10.1016/j.resconrec.2019.03.029
      There is no corresponding record for this reference.

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