Effect of Dispersion Treatment on Dairy Waste Activated Sludge to Hasten the Production of Biogas

Abstract

The solubilization potential of biological pre-treatment for waste activated sludge (WAS) is limited due to the floc structure of the WAS. Extra polymeric substances (EPS) are responsible for floc formation. In this investigation, an attempt has been made to disturb the floc structure of WAS by removing EPS with a disperser. In the first stage, the disperser treatment released 242 mg/L of soluble EPS when operated at 3,000 rpm for a duration of 50 s and caused deflocculation of WAS. In the second stage, deflocculated sludge was subjected to bacterial pre-treatment to assess the effect of floc disruption. During bacterial pre-treatment, it was found that deflocculated sludge produced higher organic solubilization of 23.9% and a reduction in suspended solids of 19.1% when compared to control (10.2 and 8.7%, respectively). Biogas yields were recorded of 220 mL/g COD in deflocculated sludge and 93 mL/g COD in flocculated sludge. From the above, it is evident that deflocculation effectively enhanced bacterial pre-treatment, leading to more solubilization and biogas production.