Sustainable treatment of municipal sewage sludge

The main purpose of this thesis was to realize sustainable utilization of municipal sewage sludge. Previous sludge disposal methods were introduced, including landfill, incineration, ocean dumping and agricultural land use. Due to the harmful substances in sludge, these methods will harm the environment when used. Sludge can be used as a substrate to produce hydrogen and biogas. This thesis introduces three methods of hydrogen production: anaerobic fermentation, plasma gasification and supercritical water gasification. Anaerobic digestion is used to produce biogas. These methods can reduce the cost of hydrogen production from sludge and improve the hydrogen production rate. Hydrogen production by anaerobic fermentation has certain requirements for substrates, and sludge needs to be cofermented with other substrates to maintain the yield. The advantage of plasma gasification is sludge volume reduction, which can reach 41.19 %. The average hydrogen production rate of supercritical water gasification method is the highest when the conditions higher than 374 °C and 22.1 MPa. Supercritical water is used as gasification medium to produce hydrogen