Calcium peroxide induced mechanical disintegration in acidic environment for efficient biogas and biopolymer generation from paper mill sludge

Abstract

The proposed research envisioned to improve the accessibility of organics and hydrolysis of paper mill waste activated sludge for polyhydroxybutyrate production and anaerobic digestion. In order to fill this research gap an exploration has been made by adding lower dosage of calcium peroxide at acidic pH for the removal of exopolymeric substances thereby improving the disintegration efficacy. The results indicate that the calcium peroxide dosage of 0.06 g/g SS at pH 5 was optimum for floc fragmentation. The influence of floc fragmented sludge on disintegration by disperser shows the solubilization and solid decrement of 18.8% and 12.4% at the specific energy input of 4729.24 kJ/kg total solid. The impact of pretreated supernatant on polyhydroxybutyrate accumulation shows the maximum polyhydroxybutyrate content of 85.03 % while utilizing 60% (v/v) of pretreated sludge supernatant as a carbon source at 42 h. Subsequently, the settled sludge was directed towards an anaerobic biodegradability assay and found about 167 mL/g of chemical oxygen demand of biogas generation, which is higher than the crude sample (52 mL/g of chemical oxygen demand). The higher solubilization in pretreated sample reveals the easier accessibility of substrate by the microorganisms, thereby enhances bioenergy and valued product generation.