Performance of a small on-site wastewater treatment system using absorbentbiofilter for Korean rural community

The feasibility of an absorbent biofilter system was examined for rural was tewater treatment in Korea. Hydraulic loading rates varied fi om 50 to 250 cm/day. Effluent of the septic tank was fed into the absorbent biofilter, a nd small ventilation fan was provided to supply air at the rate of 250 L/mi n to aerate the biofilter. The biofilter system demonstrated high removal r ates for BOD5 and TSS at the loading rate of 150 cm/day, generally meeting the Korean effluent water quality standard of 20 mg/L applicable to both. T he nutrient removal was less satisfactory than the results of BOD5 and TSS, but it was within the expected range of biological treatment processes. Co nsidering the abnormally high influent concentration of nutrients during th e experiment, better performance results could have been obtained if ordina ry domestic wastewater was used. The treatment efficiency decreased during low temperature period in winter, thus enhancement of the system applicable to all seasonal temperature ranges is recommended. The system performance was not significantly affected by the hydraulic Loading up to 150 cm/day, w hich is far more than the loading limit of the sand filter systems. Mainten ance requirement was minimal, and no problems with noise, odor, flies or sl udge arose. Since the biofilter system can be operated at a distance, opera tion in remote rural area and multi-system connected to one control office might be advantageous to the rural area. Overall, considering the cost-effe ctiveness, stable performance, and minimum maintenance, the biofilter syste m was thought to be a competitive alternative to treat wastewater in Korean rural communities.