Chitosan-Fe3O4 composites enhance anaerobic digestion of liquor wastewater under acidic stress

Acid stress in the anaerobic digestion process of liquor wastewater leads to low anaerobic treatment efficiency. Herein, chitosan-Fe3O4 was prepared, and its effects on anaerobic digestion processes under acid stress were studied. Results showed that chitosan-Fe3O4 increased the methanogenesis rate of anaerobic digestion of acidic liquor wastewater by 1.5-2.3 times and accelerated the restoration of acidified anaerobic systems. The analysis of sludge characteristics showed that chitosan-Fe3O4 promoted the secretion of proteins and humic substances in extracellular polymeric substances and increased the electron transfer activity of the system by 71.4%. Microbial community analysis indicated that chitosan-Fe3O4 enriched the abundance of Peptoclostridium, and Methanosaeta participated in direct interspecies electron transfer. Chitosan-Fe3O4 could promote the direct interspecies electron transfer pathway to maintain stable methanogenesis. These methods and results regarding the use of chitosan-Fe3O4 could be referred to for improving the efficiency of anaerobic digestion of high concentration organic wastewater under acid inhibition.