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Effects of different yellow-storage pretreatments on the dry anaerobic digestion characteristics of rice straw
Received:September 21, 2020  
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KeyWord:rice straw;dry anaerobic digestion;pretreatment;carbon-nitrogen ratio(C/N) ;biogas production
Author NameAffiliationE-mail
WANG Zhen-qi State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China  
ZHANG Min State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China  
SHEN Gen-xiang State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China shengx@saes.sh.cn 
WANG Chen School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China  
QIAN Xiao-yong State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China  
NI Yuan-zhi State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China  
ZHANG Xin-liang State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China  
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Abstract:
      The aim of this study was to improve the biogas production efficiency of rice straw in a dry anaerobic digestion system with a high C/N ratio in a water source reservoir area in the Yangtze River Delta, using a self-made automatic stainless-steel digester. We explored the effects of different yellow-storage pretreatments on the dry anaerobic digestion efficiency, change in feed structure, and rice straw degradation. Results showed that at a C/N ratio of 50, the diluted alkaline pretreatment with 8 mg·L-1 Ca(OH) 2 and microbial pretreatment with 20-times diluted biogas slurry gave the highest biogas yields of 407 L·kg-1 VS and 397 L·kg-1 VS(dry matter), respectively. These were 1.64 times and 1.59 times higher than the yields of CK, respectively, and achieved 80%~115% of the yield generated under optimal C/N conditions. Our results indicated that appropriate pretreatment options could eliminate the inefficiency resulting from insufficient nitrogen sources. Both pretreatment methods improved the cellulose degradation efficiency by decomposing the wax layer, particulate, and filamentous matter on the rice straw surface. The results indicated that diluted alkaline pretreatment buffered the inhibition effects of acidification on gas production, while slurry treatment significantly increased the methane content of biogas at the initial stage of digestion. However, pretreatment duration using the microbial method with slurry was 4 times longer than that of the diluted alkaline method. Therefore, under engineering conditions, the choice of pretreatment option should be guided by actual needs.