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1. Integrating dairy manure for enhanced resource recovery at a WRRF: Environmental life cycle and pilot‐scale analyses

   https://doi.org/10.1002/wer.1574  

   Bryant, Casey ; Coats, Erik R. ( April 2021 , Water Environment Research)

   The Twin Falls, Idaho wastewater treatment plant (WWTP), currently operates solely to achieve regulatory permit compliance. Research was conducted to evaluate conversion of the WWTP to a water resource recovery facility (WRRF) and to assess the WRRF environmental sustainability; process configurations were evaluated to produce five resources—reclaimed water, biosolids, struvite, biogas, and bioplastics (polyhydroxyalkanoates, PHA). PHA production occurred using fermented dairy manure. State‐of‐the‐art biokinetic modeling, performed using Dynamita's SUMO process model, was coupled with environmental life cycle assessment to quantify environmental sustainability. Results indicate that electricity production via combined heat and power (CHP) was most important in achieving environmental sustainability; energy offset ranged from 43% to 60%, thereby reducing demand for external fossil fuel‐based energy. While struvite production helps maintain a resilient enhanced biological phosphorus removal (EBPR) process, MgO₂production exhibits negative environmental impacts; integration with CHP negates the adverse consequences. Integrating dairy manure to produce bioplastics diversifies the resource recovery portfolio while maintaining WRRF environmental sustainability; pilot‐scale evaluations demonstrated that WRRF effluent quality was not affected by the addition of effluent from PHA production. Collectively, results show that a WRRF integrating dairy manure can yield a diverse portfolio of products while operating in an environmentally sustainable manner.

   Wastewater carbon recovery via anaerobic digestion with combined heat/power production significantly reduces water resource recovery facility (WRRF) environmental emissions.

   Wastewater phosphorus recovery is of value; however, struvite production exhibits negative environmental impacts due to MgO₂production emissions.

   Bioplastics production on imported organic‐rich agri‐food waste can diversify the WRRF portfolio.

   Dairy manure can be successfully integrated into a WRRF for bioplastics production without compromising WRRF performance.

   Diversifying the WRRF products portfolio is a strategy to maximize resource recovery from wastewater while concurrently achieving environmental sustainability.

    

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2. Soybean growth and production as affected by struvite as a phosphorus source in eastern Arkansas

   https://doi.org/10.1002/csc2.20852  

   Omidire, Niyi S. ; Brye, Kristofor R. ; English, Leah ; Kekedy‐Nagy, Laszlo ; Greenlee, Lauren ; Popp, Jennie ; Roberts, Trenton L. ( January 2023 , Crop Science)

   Struvite (MgNH₄PO₄·6H₂O) has been precipitated from liquid waste streams to recover valuable nutrients, such as phosphorus (P) and nitrogen (N), that can be used as an alternative fertilizer‐P source. Because prior research has focused on greenhouse studies, it is necessary to expand struvite evaluations to the field‐scale to include row‐crop responses. The objective of this field study was to evaluate the effects of two struvite materials (electrochemically precipitated struvite, ECST; and chemically precipitated struvite, CPST) relative to other common fertilizer‐P sources (diammonium phosphate, DAP; triple superphosphate, TSP; rock phosphate, RP; and monoammonium phosphate, MAP) on soybean [Glycine max(L.) Merr.] response and economics in two consecutive growing seasons in a P‐deficient, silt‐loam soil (Aquic Fraglossudalfs) in eastern Arkansas. Averaged across years, soybean aboveground tissue P uptake was largest (P < .05) from ECST (28.4 kg ha⁻¹), which was similar to CPST (26.7 kg ha⁻¹) and TSP (25.9 kg ha⁻¹) and was smallest from RP (21.4 kg ha⁻¹). In 2019, seed yield was largest (P < .05) from ECST (4.1 Mg ha⁻¹), which was similar to DAP, CPST, RP, TSP, and MAP, and was smallest from the unamended control (3.6 Mg ha⁻¹). In 2020, seed yield was numerically greatest from CPST (2.8 Mg ha⁻¹) and was numerically smallest from ECST (2.2 Mg ha⁻¹). Results showed that wastewater‐recovered struvite materials have the potential to be a viable, alternative fertilizer‐P source for soybean production in a P‐deficient, silt‐loam soil, but further work is needed to confirm struvite's cost effectiveness.

    

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3. Immobilized phosphate‐binding protein can effectively discriminate against arsenate during phosphate adsorption and recovery

   https://doi.org/10.1002/wer.1498  

   Venkiteshwaran, Kaushik ; Wells, Erin ; Mayer, Brooke K. ( December 2020 , Water Environment Research)

   There is a strong impetus to establish a circular phosphorus economy by securing internally renewable phosphate (P_i) resources for use as agricultural fertilizers. Reversible P_iadsorption technologies such as ion exchange can remove and recover P_ifrom water/wastewater for reuse. However, existing reversible adsorbents cannot effectively discriminate against arsenate (As(V)) due to the similarity between As(V) and P_ichemical structure. If As(V) is co‐recovered with P_i, the value of the recovered products for agricultural reuse is low. The objective of this study was to construct an immobilized phosphate‐binding protein (PBP)‐based P_iremoval and recovery system and analyze its selectivity for P_iadsorption in the presence of As(V). A range of conditions was tested, including independent, sequential, and simultaneous exposure of the two oxyanions to immobilized PBP (PBP resin). The purity of the recovered P_iproduct was assessed after inducing controlled desorption of the adsorbed oxyanions at high pH (pH 12.5). P_iconstituted more than 97% of the adsorbed oxyanions in the recovered product, even when As(V) was initially present at twofold higher concentrations than P_i. Therefore, PBP resin has potential to selectively remove P_i, as well as release high‐purity P_ifree of As(V) contamination suitable for subsequent agricultural reuse.

   Existing reversible phosphate (P_i) adsorbents cannot effectively discriminate against arsenate (As(V)) due to the similarity in their chemical structure.

   Co‐recovery of As(V) with P_ican reduce the recovered product's reuse as a fertilizer.

   An immobilized phosphate‐binding protein (PBP)‐based system can be highly selective for P_ieven in the presence of As(V).

   P_iconstituted more than 97% of the recovered product, even when As(V) was present at 2‐fold higher concentrations than P_i.

   Immobilized PBP offers advantages over existing P_iadsorbents by providing high‐purity P_iproducts free of As(V) contamination for reuse.

    

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4. Enhanced adsorption and slow release of phosphate by dolomite–alginate composite beads as potential fertilizer

   https://doi.org/10.1002/wer.1122  

   Huang, Yu‐Xi ; Liu, Meng‐Jie ; Chen, Shi ; Jasmi, Irfan Iskandar ; Tang, Yuanzhi ; Lin, Shihong ( May 2019 , Water Environment Research)

   The recovery and reuse of phosphorus (P) from wastewater treatment process is a critical and viable target for sustainable P utilization. This study explores a novel approach of integrating ultrafine mineral particles into hydrogel matrixes for enhancing the capacity of phosphate adsorption. Dolomite‐alginate (DA) hydrogel beads were prepared by integrating ball‐milled, ultrafine dolomite powders into calcium cross‐linked alginate hydrogel matrix. The adsorption isotherms followed a Langmuir–Freundlich adsorption model with higher specific adsorption capacity than those reported in literature. The kinetics of phosphate adsorption suggest that the adsorption is diffusion controlled. Investigation of adsorption capacity at differentpHshowed a maximum adsorption capacity in thepHrange of 7–10. Lastly, we demonstrated that theDAbeads are capable of slowly releasing most of the adsorbed phosphate, which is an important criterion for them to be an effective phosphorous fertilizer. This study, usingDAcomposite hydrogel as an example, demonstrates a promising strategy of immobilizing ultrafine mineral adsorbents into biocompatible hydrogel matrix for effective recovery of phosphorous resource from wastewater.

   Integration of dolomite and alginate hydrogel beads is demonstrated using ball milling.

   Ball milling process increases the specific adsorption capacity of dolomite on phosphorus.

   Adsorption isotherms, kinetics, andpHeffects of the dolomite–alginate beads are investigated.

   The dolomite–alginate beads can be used as slow‐release phosphorus fertilizer.

    

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5. Transition metal-doped MgO nanoparticles for nutrient recycling: an alternate Mg source for struvite synthesis from wastewater

   https://doi.org/10.1039/D0EN00660B  

   Silva, Manoj ; Murzin, Vadim ; Zhang, Lihua ; Baltrus, John ; Baltrusaitis, Jonas ( November 2020 , Environmental Science: Nano)

   null (Ed.)

   Nutrient nitrogen (N) and phosphorus (P) recovery from wastewater is an important challenge for enhanced environmental sustainability. Herein we report the synthesis and properties of mesoporous MgO nanoparticles doped with copper (Cu), iron (Fe), and zinc (Zn) as an alternative low-solubility high-abundance magnesium (Mg) source for crystalline struvite precipitation from nutrient-laden wastewater. Undoped MgO was shown to have the fastest phosphate (PO 4 3− ) adsorption kinetics with a k 2 value of 0.9 g g −1 min −1 at room temperature. The corresponding rate constant decreased for Cu–MgO (0.175 g g −1 min −1 ), Zn–MgO (0.145 g g −1 min −1 ), and Fe–MgO (0.02 g g −1 min −1 ). Undoped MgO resulted in the highest PO 4 3− removal at 94%, while Cu–MgO, Fe–MgO, and Zn–MgO resulted in 90%, 66% and 66%, respectively, under equivalent reaction conditions. All dopants resulted in the production of struvite as the main product with the incorporation of the transition metals into the struvite crystal lattice. X-ray absorption spectroscopy (XAS) showed that the majority of the Cu, Fe, and Zn were primarily in the +2, +3, and +2 oxidation states, respectively. XAS also showed that the Cu atoms exist in elongated octahedral coordination, while Fe was shown to be in octahedral coordination. Zn was shown to be in a complex disordered environment with octahedral sites coexisting with the majority of the tetrahedral sites. Finally, X-ray photoelectron spectroscopy data suggest a two-fold struvite surface enrichment with dopant metals, with Cu exhibiting an interesting new local binding structure. The dopant concentrations utilized were consistent with those found in natural Mg minerals, suggesting that (a) utilizing natural mineral periclase as the Mg source for struvite production can result in struvite formation, albeit at the expense of the reaction kinetics and overall yields, while also (b) supplying essential micronutrients, such as Zn and Cu, necessary for balanced nutrient uptake. 

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