Assessment of Struvite as an Alternative Sources of Fertilizer-Phosphorus for Flood-Irrigated Rice

Abstract

Phosphorus (P) recovery from wastewaters as struvite (MgNH4PO4·6H2O) may be a viable alternative fertilizer-P source for agriculture. The objective of this study was to evaluate the economic and environmental implications of struvite as a fertilizer-P source for flood-irrigated rice (Oryza sativa) relative to other commonly used commercially available fertilizer-P sources. A field study was conducted in 2019 and 2020 to evaluate the effects of wastewater-recovered struvite (chemically precipitated struvite (CPST) and electrochemically precipitated struvite (ECST)) on rice yield response in a P-deficient, silt–loam soil in eastern Arkansas relative to triple superphosphate, monoammonium and diammonium phosphate, and rock phosphate. A life cycle assessment methodology was used to estimate the global warming potentials associated with rice produced with the various fertilizer-P sources. Life cycle inventory data were based on the field trials conducted with and without struvite application for both years. A partial budget analysis showed that, across both years, net revenues for ECST and CPST were 1.4 to 26.8% lower than those associated with the other fertilizer-P sources. The estimated greenhouse gas emissions varied between 0.58 and 0.70 kg CO2 eq kg rice−1 from CPST and between 0.56 and 0.81 kg CO2 eq kg rice−1 from ECST in 2019 and 2020, respectively, which were numerically similar to those for the other fertilizer-P sources in 2019 and 2020. The similar rice responses compared to commercially available fertilizer-P sources suggest that wastewater-recovered struvite materials might be an alternative fertilizer-P-source option for flood-irrigated rice production if struvite can become price-competitive to other fertilizer-P sources.

Identifying and testing adaptive management options to increase river catchment system resilience using a Bayesian Network model

“…Willingness for collaborative working across different sectors is evident in the recovery of struvite to potentially improve crop growth 76,77 and achieve similar yields for some crops compared to other fertiliser sources 63 . Struvite recovery encourages a circular economy model by reducing the risk of global market volatility in rock phosphate scarcity increasing fertiliser costs 78 and reducing travel miles compared to imported sources.…”

Scalable Production of Peptides for Enhanced Struvite Formation via Expression on the Surface of Genetically Engineered Microbes

“…Struvite (MgNH 4 PO 4 ·6H 2 O) is a slow-release fertilizer that readily precipitates at basic pH according to the following equation: Mg 2 + + NH 4 + + H n PO 4 3 − n + 6 H 2 O → MgNH 4 PO 4 · 6 H 2 O + n H + where n = 0, 1, or 2 depending on the solution pH . Struvite precipitation is an attractive way to recover excess phosphate from waste streams, − with life cycle assessment and budget analysis studies showing the process to be economically viable when combined with recovery of other products. − Phosphate is a particularly important nutrient, as nearly all phosphate applied as fertilizer is sourced from mined phosphate rocka resource that is dwindling and expected to cause supply issues by the end of the century …”

“… 1 Struvite precipitation is an attractive way to recover excess phosphate from waste streams, 2 − 5 with life cycle assessment and budget analysis studies showing the process to be economically viable when combined with recovery of other products. 6 − 9 Phosphate is a particularly important nutrient, as nearly all phosphate applied as fertilizer is sourced from mined phosphate rock—a resource that is dwindling and expected to cause supply issues by the end of the century. 10 …”

Circular Economy Model Through Phosphorus Recovery to Obtain Struvite from Sewage Sludge

“…Struvite is a white mineral with a crystalline and pyramidal orthorhombic structure. Also, generally, it is easy to recover and valuable as a slowrelease fertilizer [18][19][20]. Current ways of recovering phosphorus in the form of struvite are mainly carried out in the liquid fraction resulting from anaerobic sludge digestion since it concentrates large amounts of P-PO4 3-and N-NH4 + generated by the microorganisms involved in the biological process.…”

“…The stirring speed and time or temperature parameters also affect the process, but they are kept constant in this work. Furthermore, to consider obtaining struvite on an industrial scale, other parameters specific to the formation and growth of crystalline structures must be regarded to get specific particle sizes [18,20]. However, these factors have yet to be considered in this work since it has been intended to demonstrate the technical feasibility of phosphorus recovery in the form of struvite.…”