Phosphorus Recovery from Anaerobic Co-Digestion of Waste Activated Sludge and Food Waste: Effect on Molar Ratio of Mg/Ca and Mg, Ca, Fe/P

Abstract

The aim of the study was to evaluate the effect of mixing ratios and Hydraulic Reaction Time (HRT) on Phosphorus (P) recovery from waste activated sludge through pretreatment of anaerobic co-digestion to chemical precipitation processes. P recovery efficiency was improved in association with an increase of HRT. Molar ratios were carried out using Anaerobic Co-Digestion. The results showed that the molar ratios, improvement of recoverably were simultaneously achieved. Compared with anaerobic digestion pretreatment system, the molar ratios of Mg/Ca, Mg/P, Ca/P and Fe/P were observed in the anaerobic co-digestion pretreatment system. At 7, 10, 15 and 20, P was recovered into solid precipitates at 2-8%, 19-29%, 39-52%, and 40-72%, respectively with a P content in solid of about 0.8-1.4%, 0.9-2%, 1-7%, and 7-11%, P dry weight which is superior to commercial fertilizer (8.80% P). Results therefore indicate that recoverable P from urinal wastewater can be effectively used to produce fertilizer for agricultural cultivation by common ion precipitation and adsorption processes.