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EMERGY EVALUATION OF WASTEWATER-DERIVED STRUVITE AS AN ALTERNATIVE TO CONVENTIONAL FERTILIZER FOR CROP PRODUCTION
Citation:
Theregowda, R., Xin Ma, AND J. Garland. EMERGY EVALUATION OF WASTEWATER-DERIVED STRUVITE AS AN ALTERNATIVE TO CONVENTIONAL FERTILIZER FOR CROP PRODUCTION. In Proceedings, 2019 WEF Nutrient Removal & Recovery Symposium, Minneapolis, MN, July 23 - 25, 2019. WEF, Alexandria, VA, 999, (2019).
Impact/Purpose:
This study compares the emergy inputs for nutrient recovery and different levels of nutrient removal technologies. It also builds upon the previous understanding of fertilizer production and expands the system boundaries to include the application of fertilizers in crop yields to considers of the fertilizer release rate, solubility, bioavailability, crop uptake, run-off rate and sheds light on the overall system efficiency. The system-level analysis will provide a more complete resource use evaluation of nutrient recovery, the alternative nutrient management strategy, and support of long-term sustainable agriculture production while minimize the overall environmental impacts to the society.
Description:
Nutrient recovery from wastewater can prevent eutrophication in receiving waters and potentially comply with regulatory nutrient limits in the effluent. At the same time, it can produce fertilizer as a revenue source for the WWTPs and the communities. From a system perspective, it would have positive environmental impacts by avoiding the energy and material spent during nitrogen fixation, upstream mining, refining, manufacture and transportation of phosphate fertilizers. With the concern of phosphate rock depletion in the next decade, there is an immediate need to make a significant reduction in phosphorus mining, especially for the production of agricultural fertilizers. Nitrogen availability for fertilizer production though inexhaustible, the production of ammonia from nitrogen fixation by Haber Bosch process has been considered to be highly energy-intensive. A previous study on emergy evaluation of struvite recovered from wastewater compared to the production of commercial diammonium phosphate (DAP) fertilizer has revealed that nutrient recovery is more sustainable in the same tonnage production, especially in conserving the non-renewable resource, phosphorus. This study builds upon the previous understanding of fertilizer production and expands the system boundaries to include the application of fertilizers in crop yields. It considers of the fertilizer release rate, solubility, bioavailability, crop uptake, run-off rate and sheds light on the overall system efficiency. To evaluate the fertilizer application in crop fields, data from the USDA Economic Research Service (ERS) ARMS tailored crop production practices was used to calculate the total phosphorus fertilizer applied per crop per year for a given state. The USEPA web-based interactive water quantity and quality modeling system Hydrological and Water Quality System (HAWQS) tool that employs Soil and Watershed Assessment Tool (SWAT) as the core-modeling engine was used to simulate non-point source pollutant loadings and runoff in the watershed scales identified via Hydrologic Unit Codes (HUCs). Soil pH was considered due to its effects on P availability during plant P uptake. The inherent slow release nature of the struvite implies that the amount required for the same level of crop production would be lower, which would lead to less runoff. The preliminary study results show that the optimum substitution of DAP with struvite can be potentially beneficial in terms of long-term sustainable agriculture production and the reduction of negative environmental impacts. The system-level analysis will provide a more complete resource use evaluation of nutrient recovery, the alternative nutrient management strategy, and support of long-term sustainable agriculture production while minimize the overall environmental impacts to the society.
URLs/Downloads:
EMERGY EVALUATION OF STRUVITE FROM WASTEWATER_FINAL V3.PDF (PDF, NA pp, 1708.983 KB, about PDF)https://www.e-wef.org/Store/ProductDetails.aspx?productId=70086887
