A New Strategy for Recovering Organic Substance from Industrial Wastewater Using Combined Chemical Enhanced Primary Treatment (CEPT) and Nitrification Filter

This study developed an integrated Chemical Enhanced Primary Treatment (CEPT) and nitrification filter (NF) system to optimize organic matter recovery from industrial wastewater toward carbon neutrality. Jar-test experiments determined optimal coagula-tion conditions using FeCl₃ (0.5 mM) and anionic polymer (0.5 mg/L), achieving removal efficiencies of 64% TCOD, 88% TP, and 79% TSS. The bench-scale CEPT-NF system oper-ated at varying hydraulic retention times (2–6 hours) and internal recycle ratios (50–100%). Optimal performance occurred at 100% recycle ratio and 4-hour HRT, achieving 80% TCOD removal compared to 62% without recycling. The nitrification filter achieved 95% NH₄+-N oxidation at 30°C with 5–6 hour HRT. The higher TCOD removal (80%) could be achieved in the CEPT-NF not only by continuous chemical coagulation but also by hetero-trophic assimilation of denitrification. Mass balance analysis showed significant green-house gas reduction potential, with CO₂ emissions decreasing from 1,482 to 225 tCO₂/year—a 6.6-fold reduction compared to conventional treatment. The CEPT-NF pro-cess enhanced organic matter recovery through chemical coagulation and biological deni-trification, addressing poor SCOD removal limitations of conventional primary precipita-tion.