Does residual H2O2 result in inhibitory effect on enhanced anaerobic digestion of sludge pretreated by microwave-H2O2 pretreatment process?
2017
Liu, Jibao | Jia, Ruilai | Wang, Yawei | Wei, Yuansong | Zhang, Junya | Wang, Rui | Cai, Xing
This study investigated the effects of residual H₂O₂ on hydrolysis-acidification and methanogenesis stages of anaerobic digestion after microwave-H₂O₂ (MW-H₂O₂) pretreatment of waste activated sludge (WAS). Results showed that high sludge solubilization at 35–45 % was achieved after pretreatment, while large amounts of residual H₂O₂ remained and refractory compounds were thus generated with high dosage of H₂O₂ (0.6 g H₂O₂/g total solids (TS), 1.0 g H₂O₂/g TS) pretreatment. The residual H₂O₂ not only inhibited hydrolysis-acidification stage mildly, such as hydrolase activity, but also had acute toxic effect on methanogens, resulting in long lag phase, low methane yield rate, and no increase of cumulative methane production during the 30-day BMP tests. When the low dosage of H₂O₂ at 0.2 g H₂O₂/g TS was used in MW-H₂O₂ pretreatment, sludge anaerobic digestion was significantly enhanced. The cumulative methane production increased by 29.02 %, but still with a lag phase of 1.0 day. With removing the residual H₂O₂ by catalase, the initial lag phase of hydrolysis-acidification stage decreased from 1.0 to 0.5 day.
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