Impacts of river snails rice noodle ingredients addition on the kitchen waste anaerobic digestion performances, microbial communities and metabolic pathways

With the rapid development of the river snails rice noodle industry, the treatment of the wastewater generated in the production of river snails rice noodle has attracted people's attention. This study investigated the performance of the anaerobic digestion of kitchen waste with river snails rice noodle ingredients, including key enzyme activities, microbial community distribution and metabolic pathways in the anaerobic reactor. The average chemical oxygen demand removal efficiencies were 92.5% and 88.7% when 130 g and 260 g river snails rice noodle ingredients were added in the anaerobic reactor, respectively. Acetate kinase activity of the sludge decreased during anaerobic digestion, but increased at 35 degrees C on days 55. The river snails rice noodle ingredients inhibited the growth of Proteobacteria and the expression of methane metabolism. An increase in temperature promoted the presence of Bacteroidetes and Methanothrix (increased by 3.95% and 2.64% respectively). The later stage of experiment demonstrated an increase in the glycolysis rate-limiting enzymes ATP-dependent phosphofructokinase and pyruvate kinase. It was illustrated that the addition of river snails rice noodle ingredients inhibited the processing capacity of the anaerobic digestion reactor, and the increase of operating temperature of anaerobic reactor alleviated the inhibition of higher content river snails rice noodle ingredients on anaerobic digestion process. It was provided valuable basic information for the future study of treatment of river snails rice noodle wastewater.