Influence of Chemical Conditioning on Electroosmotic Dewatering Behavior for Activated Sludge

Abstract

Applying electroosmosis to sludge dewatering practically, methods for improving electroosmotic dewatering must be explored. The influence of initial pH, adding Al2 (SO4)3 dose and ash content in sludge on electroosmotic dewatering behavior was investigated. The results show that acid or alkaline environment is unfavorable for electroosmotic dewatering, especially initial pH of sludge closing to the isoelectric point, electroosmotic dewatering behaves worst. With increasing Al2(SO4)3 coagulant-aid dose, the decreasing rate of water content becomes slower gradually during electroosmotic dewatering. Besides, higher ash content in sludge has a better effect on vaccum filtration, but slightly impact on electroosmotic dewatering. When ash content increases to 69.9% from 52.4%, final water content reduces to 64.3% from 78.3% using vaccum filtration, and the decreasing amount of water content by electroosmotic dewatering ranges from 16.5% to 12.3%.