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Investigation of biogas production potential of three different sludges after thermal hydrolysis

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2019
Arı Akdemir, Ece.
Biogas production through anaerobic digestion using biological sludge is one the sustainable approaches. Hydrolysis is the first and rate limiting step during anaerobic digestion. For enhancement of hydrolysis of sludge, it is feasible to investigate pre-treatment before anaerobic digestion process. In this research, biogas and methane production potentials of municipal wastewater treatment plants sludge, membrane bioreactor sludge and organized industrial district sludge were investigated using small scale laboratory anaerobic digesters to enhance the rate limiting step through thermal hydrolysis. Sludge was pre-treated using thermal hydrolysis with different durations and temperatures. To obtain optimum anaerobic digestion triplicate BMP reactors were operated. The results of this study showed that, the methane production performance of biological sludge can be enhanced with thermal hydrolysis operated at low pressure. There is an optimum exposure time for effective thermal hydrolysis process. The results show that sludge pretreated at 127oC for 60 minutes produced the highest gas volume and improved methane to carbon dioxide ratio, in biogas. For the municipal sludge (sludge from Tatlar WWTP). Methane content of biogas was 50%, 57% and 59% for non-processed, 30 minutes thermally hydrolyzed and 60 minutes thermally hydrolyzed operation, respectively. For the domestic sludge from MBR wastewater treatment process %53, %56, and %59 methane gas was obtained in biogas for non-processed, 30 minutes thermally hydrolyzed and 60 minutes thermally hydrolyzed operation, respectively. Methane generation of MBR, MBR127/60 and MBR90/30 were 53%, 59% and 56% respectively. For organized industrial district wastewater sludge %50, %55 and %58 methane was obtained for non-processed, 30 minutes thermally hydrolyzed and 60 minutes thermally hydrolyzed operation, respectively. Non-pretreated sludge had had the lowest methane percentage in biogas for all sludge types.