Hydrothermal process for extracting phosphate from animal manure

Abstract

To mitigate the risk of the secured supply of phosphate rock, increasing attention has been paid to phosphorus (P) recovery from untapped secondary resources. Animal manure is one of the most important secondary resources for P in light of the large quantity and high P content. This chapter describes the hydrothermal technology to efficiently extract P from animal manure. Laboratory experiments showed that the hydrothermal treatment of pig manure at 180 ° C under the oxygen partial pressure of 1 MPa could increase the P extractability by approximately 150% compared to the untreated control. Under this condition, the concentration of P in the eluate reached up to 114 mg/L. The kinetics of extracting P from pig manure by the hydrothermal technology could be given by the first-order reaction equation.