The Role of Slurry Reflux in a Corn Stalk Continuous Anaerobic Digestion System: Performance and Microbial Community

Ling Zhao (), Yang Gao, Jiaxing Sun, Yanan Wang, Congxin Wang, Shuai Yu, Zhen Wang, Jingyang Li, Ronghou Liu and Wei Kou
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Ling Zhao: College of Engineering, Shenyang Agricultural University, Shenyang 110866, China
Yang Gao: College of Engineering, Shenyang Agricultural University, Shenyang 110866, China
Jiaxing Sun: College of Engineering, Shenyang Agricultural University, Shenyang 110866, China
Yanan Wang: College of Engineering, Shenyang Agricultural University, Shenyang 110866, China
Congxin Wang: College of Engineering, Shenyang Agricultural University, Shenyang 110866, China
Shuai Yu: College of Engineering, Shenyang Agricultural University, Shenyang 110866, China
Zhen Wang: College of Engineering, Shenyang Agricultural University, Shenyang 110866, China
Jingyang Li: College of Engineering, Shenyang Agricultural University, Shenyang 110866, China
Ronghou Liu: Biomass Energy Engineering Research Centre, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
Wei Kou: Department of Chemistry and Environmental Engineering, Yingkou Institute of Technology, Yingkou 115014, China

IJERPH, 2023, vol. 20, issue 3, 1-11

Abstract: Slurry reflux is a low-cost slurry reduction technology, which can solve the problem that a large amount of slurry cannot be completely consumed in a biogas plant. Anaerobic digestion (AD) of corn stalks with slurry reflux and non-reflux was compared and evaluated in continuous anaerobic digestion to clarify the effects of slurry reflux on AD with organic loading rate (OLR) variation. It was found that slurry reflux increased cumulative methane production and improved system stability. The average methane yield of the slurry reflux group was 224.19 mL/gVS, which was 41.35% higher than that of the non-reflux group. High-throughput sequencing results showed that slurry reflux increased the microbial community richness. The dominant microorganisms in the reflux group were in phylum Bacteroidetes, which have the capacity to degrade polymers, and Methanothrix , which is an aceticlastic methanogen. The relative abundances of Bacteroidetes and Methanothrix were 32.41% and 41.75%, respectively. Clostridium III and Saccharofermentans , which are related to syntrophic acetate oxidation and hydrolysis, were increased in relative abundance in the slurry reflux system. The increase of the OLR altered the main methane-producing pathway from the acetoclastic methanogenic pathway to the hydrogenotrophic methanogenic pathway in the AD system, and the slurry reflux can delay this trend. This study provided an effective way for the reduction and utilization of slurry in a biogas plant.

Keywords: slurry reflux; corn stalk; anaerobic digestion; methane; microbial community (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2023
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