Enhancement of biochemical methane potential from excess sludge with low organic content by mild thermal pretreatment

• Published in: Biochemical engineering journal 2013-01, Vol.70 (15), p.127-134
• Main Authors: Yan, Yuanyuan, Chen, Hanlong, Xu, Wenying, He, Qunbiao, Zhou, Qi
• Format: Article
• Language: English
• Subjects: adenosine; adenosine 5′-triphosphate; adenosine triphosphate; anaerobic digestion; Anaerobic processes; Biogas; Biological and medical sciences; Biological treatment of sewage sludges and wastes; Biotechnology; energy; Environment and pollution; Enzyme activity; enzymes; Excess sludge; Fundamental and applied biological sciences. Psychology; Industrial applications and implications. Economical aspects; methane; methane production; methanogens; sludge; solubilization; temperature; Waste treatment
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2012.10.011

► Soluble organic content from sludge increased gradually with mild temperature. ► Biochemical methane potential was greatly enhanced by mild thermal pretreatment. ► General microbial activity was improved by mild thermal pretreatment. ► Activities of key enzymes were heightened by mild thermal pretreatment. ► An increase of methanogen amount was observed due to mild thermal pretreatment. Excess sludge with low organic content always led to the failure of anaerobic digestion for methane production. Recently, the mild thermal pretreatment, which is usually operated at temperatures below 120°C, has drawn much attention due to less energy consumption and no chemical addition. In this study the effect of mild thermal pretreatment (50–120°C) on the solubilization and methane potential of excess sludge with a low concentration of organic matters was investigated. Experimental results showed that the concentration of soluble organic matters increased gradually with temperature during the mild thermal pretreatment of excess sludge. Biochemical methane potential experiments demonstrated that the potential of methane production from excess sludge was greatly enhanced by mild thermal pretreatment, and under the conditions of pretreatment temperature 100°C and digestion time 20 d the methane yield was as high as 142.6±2.5mL/g of volatile solids. Mechanism investigation on the enhancement of methane production from excess sludge exhibited that the consumptions of sludge protein and carbohydrate, the adenosine 5′-triphosphate content of anaerobic microorganisms, the activities of key enzymes related to anaerobic digestion, and the amount of methanogens were all improved by mild thermal pretreatment, in correspondence with the production of methane.