Journal of Korean Society of Agricultural Engineers ISSN:1738-3692(Print) 2093-7709(Online) 한국농공학회논문집

An Absorbent Biofilter System (ABS) combined with the recirculation process was investigated for the feasible application in additional removing of organics (BOD, SS) as well as nutrients (TN, TP) from small Community wastewater in Korea. Polyurethane biofilter media with high porosity and large surface area were used for the aerobic system. A part of treated wastewater was recirculated into the anoxic septic tank to promote removal of nutrients. The concentrations of BOD and SS of treated wastewater satisfied the regula-tions for small on-site wastewater treatment facility (10 mg/L) during the overall experimental period. The effluent concentrations of BOD and SS were decreased with enhancement of removal efficiencies of 95.7 and 96.7%. The nitrogen and phosphorus removal efficiencies by the recirculation increased to 52.9% and 43.2% in average during the overall experimental period, respectively. With the improvement, these values were increased as much as additional 42 and 18% compared with those of non-recirculation. The rates of nitrification and denitrification were enhanced showing 65~77% and 42~92%, respectively. The described process modification is a low cost and effective method of enhancing nitrogen and phosphorus removal, especially on existing systems without changing major design components of a treatment facility.