Simultaneous recovery of ammonium, phosphorus and potassium from swine wastewater using batch reactor

Abstract

The purpose of this study was to clarify the effects of mixing intensity on the quality of treated water and the recovery of fertilizers when N, P, and K were simultaneously recovered from swine wastewater at high pH using a batch recovery system. Experiments were performed using a batch reactor. The sedimentation velocity was almost constant when the between of 20 to 70 sec^-1, but the sedimentation velocity decreased at the mixing intensity over 70 sec^-1. The SS concentration was as small as 120 mg/L at the maximum, and the solid-liquid separation was sufficient. At a mixing intensity of 31 sec ^-1 or less, the total concentrations of P and N in the treated water satisfied the drainage standards. The recovery rate of N as fertilizer increased but recovery rate of K as fertilizer decreased with increasing mixing intensity. The average recovery of the sum of N and K was maximum (92%) at a mixing intensity of 31 sec^-1. The recovery rate of P as fertilizer was 100% regardless of the mixing intensity. From the viewpoints of both water treatment and resource recovery, the optimum mixing intensity was 31 sec^-1.