Thermo-oxidative pretreatment of municipal waste activated sludge for volatile sulfur compounds removal and enhanced anaerobic digestion

Thermo-oxidative pretreatment of municipal waste activated sludge was conducted using thermal pretreatment at 60 °C in presence of 0.6 mg H2O2 + 1.5 mg FeCl2/mg S2− as oxidants with the objective of achieving sludge disintegration for enhancing anaerobic digestion as well as to remove volatile sulfur compounds generation potential in biogas in continuous anaerobic digestion. For the pretreated feed digester, the hydrogen sulfide (H2S) and dimethyl sulfide (DMS) concentrations in biogas significantly decreased by an average of 75%, and 40%, respectively, while methanethiol (MT) removal efficiency was statistically insignificant compared to the control digester. Compared to the control, overall TSS and VSS removal efficiency were 10% and 11% higher for the pretreated feed digester operated at 10 days solid residence time (SRT), and methane production rate (L CH4/Day) increased by ∼20%. The simulation results using BioWin® suggest that the thermo-oxidative pretreatment has significantly increased the hydrolysis rate by 30% with higher methane production rate compared to the control digester.

► Combined thermo-oxidative pretreatment of waste activated sludge reduces odor in bio-gas in continuous digestion.
► Pretreatment reduces odor precursors such as bound protein and fatty acids in sludge.
► Predictive capability of a simpler anaerobic digestion model BioWin is established.