Abstract
Water pollution is now a serious problem in closed water areas and drinking water sources. Thus, a new wastewater treatment system for high efficiency removing organic matter should be established soon. In the present study, biological treatment using ozone (Ozone-Bio treatment process) was examined for removal of refractory organics in an advanced night soil treatment system. The results of continuous experiments with actual secondary effluents from night soil treatment plants indicated this method superior to various conventional processes.
The removal rate of refractory organics (COD) was over 90% and this is sufficient for treating water under 20 mg CODMn/l that is an aim of the treated water quality. The performance is much higher than that of conventional ozone processes. Tri-halo-methane precursors (THMFP) appeared to be removed selectively from total organics. Refractory organics were removed by direct oxidization in ozonation, and biological decomposition in the biological activated carbon (BAC) process after improvement of organics biodegradability by ozonation. For greater efficiency, a portion of the biological process effluent must be re circulated, and the ozone dosage and circulation ratio may possibly be very important factors in the operation of this process. Running cost of this process was found less than for conventional activatedcarbon adsorption.
