Effect of thermal pretreatment on the physical and chemical properties of municipal biomass waste

The effects of thermal pretreatment on the physical and chemical properties of three typical municipal biomass wastes (MBWs), kitchen waste (KW), vegetable/fruit residue (VFR), and waste activated sludge (WAS) were investigated. The results show that thermal pretreatment at 175 °C/60 min significantly decreases viscosity, improves the MBW dewatering performance, as well as increases soluble chemical oxygen demand, soluble sugar, soluble protein, and especially organic compounds with molecular weights >10 kDa. For KW, VFR and WAS, 59.7%, 58.5% and 25.2% of the organic compounds can be separated in the liquid phase after thermal treatment. WAS achieves a 34.8% methane potential increase and a doubled methane production rate after thermal pretreatment. In contrast, KW and VFR show 7.9% and 11.7% methane decrease because of melanoidin production.

► Thermal pretreatment (TP) of three municipal biomass wastes was examined.
► TP significantly decreases viscosity and improves dewatering performance.
► TP increases soluble organic compounds, especially with molecular weights >10 kDa.
► Waste activated sludge achieves a 34.8% methane increase after TP.
► Melanoidins produced during TP have negative effect on methane production.