Effects of Thermal Pretreatment and High-Solids on Anaerobic Digestion of Sewage Sludge
This study examined the effects of thermal pretreatment of excess sludge and high-solids influent on the anaerobic digestion of sewage sludge. The thermal pretreatment (130℃ and 1 hour) improved VS destruction and gas production by several percent, but color intensity of digested sludge was enhanced. The performance of anaerobic digesters were depressed by the increased concentration of influent sewage sludge, especially at TS 9-10% influent. The ammonia concentration of the digested sludge was not very high so that physical accessibility of microorganisms to sewage sludge appears to be responsible. This is supported by a batch test, in which the coagulant for sludge thickening delayed the gas production.