Enhanced anaerobic degradation of 2,4,6-trichlorophenol through electrochemical advanced oxidation pretreatment

Industrial wastewater containing 2,4,6-trichlorophenol (TCP) presents significant treatment challenges due to its high biological resistance and toxicity. This study developed a novel approach by combining electrochemical advanced oxidation process (eAOP) and anaerobic digestion (AD) to address these issues. The effects of TCP concentration (500 or 100 ppm), electrolyte type (NaCl or Na 2 SO 4 ), and electrolysis degree (0 %, 70 %, or 100 %) on TCP removal, biomethane production, and volatile fatty acid (VFA) profiles were evaluated. Results showed that eAOP pretreatment with 70 % TCP degradation in Na 2 SO 4 significantly improved biodegradability at high TCP levels, enabling complete TCP removal by AD within 10 days. Although eAOP pretreatment in NaCl achieved a faster degradation and less energy consumption, more chlorinated transformation products (TPs) were produced, which could be more toxic than the parent pollutant. This combined process also mitigated the inhibitory effects of TCP on methanogenesis during AD. The study highlights a promising strategy for enhancing the biodegradation of toxic chlorophenols in industrial wastewater. • eAOP is a promising pretreatment of anaerobic digestion. • eAOP mitigates the toxicity and improves the biodegradability of TCP. • eAOP pretreatment improves biomethane production and mitigates VFA accumulation. • eAOP in Na 2 SO 4 leads to less toxic transformation products of TCP compared to NaCl.