Recovering phosphorus as a coproduct from corn dry grind plants: A techno-economic evaluation

Background and objectives The coproduct of ethanol industry, dried distiller's grains with solubles (DDGS), has phosphorus content in excess of the animal diet requirement, which leads to excess P in manure and causes environmental concerns. The objective of this study is to determine the technical and economic feasibility of recovering this excess P as a coproduct. Findings The amount of P was observed to reduce from 9.26 to 3.25 mg/g (db) of DDGS, which is consistent with the animal diet requirement of 3-4 mg P/g animal diet. For an existing dry grind plant of 40 million gallon ethanol capacity, an additional fixed cost of $5.7 million was estimated, with an operating cost increase of $1.29 million/year. Conclusions The total phosphorus recovered from the plant was estimated as 1,676 kg P/day, with an estimated operating cost of $2.33/kg P recovered. Significance and novelty Approximately 37 million MT of DDGS is produced annually as animal food containing excess P, which is a serious concern for the environment. This study provides with an economically feasible solution to recover the excess P as a coproduct, which has a potential to be used as fertilizer on more than 56,000 acres of land annually, growing corn and soybean.