Immobilized and MgSO4 induced cost effective bacterial disintegration of waste activated sludge for effective anaerobic digestion.

In this study, an attempt was made to disintegrate waste activated sludge (WAS) in a cost-effective way. During the first phase of this study, effective break down of extracellular polymeric substance (EPS) was performed by deflocculating WAS with 0.1 g/g SS of MgSO4. Deflocculation rate was 92% with discharge rate of extractable EPS at 185 mg/L. In the second phase, effective bacterial cell disintegration was obtained at 36 h post treatment. Maximum solubilization of deflocculated sludge was approximately 21%, which was higher than that of flocculated sludge (14.2%) or the control (4.5%). Biodegradability studies were assessed through kinetic analysis by non-linear regression modeling. Results revealed that the deflocculated sludge had higher methane generation (at about 235.8 mL/gVs) compared to flocculated sludge (at 146.1 mL/gVs) or the control (at 34.8 mL/gVs). Cost assessment of the present work revealed that the net yield for each ton of the deflocculated sludge was about 32.99 USD.