Authors: Xiangqian Chu Guangxue Wu Jiaquan Wang ZhenHu Hu
Publish Date: 2015/08/25
Volume: 22, Issue: 24, Pages: 20143-20153
Abstract
Dry anaerobic digestion of sewage sludge can recover biogas as energy however its low C/N ratio limits it as a single substrate in the anaerobic digestion Rice straw is an abundant agricultural residue in China which is rich in carbon and can be used as carbon source In the present study the performance of dry codigestion of sewage sludge and rice straw was investigated under mesophilic 35 °C and thermophilic 55 °C conditions The operational factors impacting dry codigestion of sewage sludge and rice straw such as C/N ratio moisture content and initial pH were explored under mesophilic conditions The results show that low C/N ratios resulted in a higher biogas production rate but a lower specific biogas yield low moisture content of 65 resulted in the instability of the digestion system and a low specific biogas yield Initial pH ranging 70–90 did not affect the performance of the anaerobic digestion The C/N ratio of 26–291 moisture content of 70–80 and pH 70–90 resulted in good performance in the dry mesophilic codigestion of sewage sludge and rice straw As compared with mesophilic digestion thermophilic codigestion of sewage sludge and rice straw significantly enhanced the degradation efficiency of the substrates and the specific biogas yield p 005 at the conditions of C/N ratio 261 moisture content 80 and natural initial pH Although high concentrations of ammonia–nitrogen NH4–N 1500 mg/kg wet weight were formed during thermophilic digestion there was no obvious inhibition occurred The results indicated that rice straw can be used as carbon source for the dry codigestion of sewage sludge under mesophilic and thermophilic conditions
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