Improving methane production and 4-chlorophenol removal in anaerobic digestion of corn straw by adding Phanerochaete chrysosporium and biochar under microaerobic conditions

Abstract

The stable lignocellulose structure in the straw is the main obstacle for methane production during its anaerobic digestion, and the residual chlorophenols in the straw further increase the difficulty. In this study, the anaerobic digestion of corn straw containing 4-chlorophenol was enhanced by the addition of Phanerochaete chrysosporium and biochar. The results revealed that P. chrysosporium significantly increased the soluble COD concentration and total COD removal efficiency in the anaerobic digestion of corn straw, which initially contained a small amount of residual oxygen (4.1–4.5 mg/L). The accumulative methane production of the P. chrysosporium-coupled biochar (PC-BC) group and the PC group with P. chrysosporium alone were 232.9 ± 3.0 mL and 201.7 ± 5.1 mL, respectively, which were significantly higher than the control group (19.4 ± 1.0 mL) with the sterilized P. chrysosporium. The presence of biochar increased 4-CP removal rate to 93.3 %, which was 15.2 % higher than the control. Additionally, FTIR analysis indicated that the addition of P. chrysosporium and biochar enhanced the decomposition of lignocellulose structure. Moreover, the sludge capacitance and electron transfer capacity were highest in the PC-BC group. Also, microbial community analysis showed that biochar could enrich dechlorinating bacteria (e.g., Sedimentibacter) and electroactive microorganisms, which further enhanced dechlorination and methanogensis.