Sono-Thermal Pretreatment of Waste Activated Sludge for Enhanced Anaerobic Digestion and Volatile Sulfur Compounds Control in Biogas

摘要

The impact of sono-thermal pretreatment combining ultrasound and conventional heatingas a pretreatment process for municipal waste activated sludge prior to anaerobic digestion isevaluated in terms of sludge solubilization, solids reduction, biogas production, volatile sulfurcompounds concentrations in biogas, dewaterability of digested sludge, and economic feasibilityof the pretreatment process. A total of nine combined sono-thermal pretreatments wereconducted using three different ultrasound specific energy inputs (1000, 5000, and 10,000 kJ kg~(-1)TSS~(-1)) and thermal pretreatment temperatures (50, 70 and 90℃). Results of pretreatment haveshown that the sono-thermal pretreatments have significantly reduced VSS after pretreatmentranging from 29%-38%. A maximum of 30% increase in methane production was observed forthree pretreatment at 90℃ followed by ultrasound pretreatment at 10,000 kJ kg~(-1)TSS~(-1) specificenergy input. Economic assessment suggests that combination of low temperature thermalpretreatment at 50℃ and low specific energy input at 1000 kJ kg~(-1) TSS~(-1) is economically morefeasible compared to ultrasound pretreatment alone.