Study On The Biological Contact Oxidation Pretreatment Process Of Micropolluted Source Water

At present raw water has been increasing polluted. The conventional water purification system (CWPS) can't remove the pollutants including the dissolved organic matter, NH4+-N and NO2--N in the raw drinking source water, especially the disinfection by-products and are becoming unfit to the polluter raw water. Therefore the biological water purification process developed very fast in removing the pollutants in raw water. The biological contact oxidation process (BCOP) has been extensively taken seriously and followed with interest all over the world in that it has a series of advantages including the low cost of running, high efficiency, stable running and convenient management. The pilot research has been conducted in the Miyun reservoir plant on the water treatment of polluted raw water by the optimal combination system of the BCOP using elastic stereo packing with the follow-up CWPS in order that the pollutants in the raw water can be removed efficiently.The polluted raw water from Miyun reservoir in Beijing has been treated by theBCOP-flocculation-active carbon filtration system. The results show that thebiological column 1 has a removal efficiency of 18.7%~58.3%, 32%~73%, 43%~63%, 6-20% for turbidity, NH4+-N, NO2--N, DBPs precursor respectively under the condition of raw water turbidity 0.48-5.80NTU,NH4+-N 0.01~0.32mg/L, N02--N 0.003~0.050mg/L, CODMn 0.96-3.37, chroma 5 and HRT 1.325h. Biological column 2 has the removal efficiency of 12.4%~56.2%,5~48%for turbidity and DBPs precursor under the condition that HRT is 1.57h. Increasing the NH4+-N concentration of influent in column 2,NH4+-Nremoval efficiency is 26%~97%.The main factors affecting the pollutant removal efficiency of the BCOP have been analyzed and discussed briefly in the article.The mechanism of pollutant removal by the BCOP in pretreating the micropolluted raw water has been analyzed and studied. The biofilm on the packing plays the main role in removing the pollutants in the raw water treatment. The primary microbes in the biofilm are malnourished bacterium. The purification includes the biofilm adsorption, biological flocculation, biodegradation of organic and notable nitrification etc.The research results show the optimal combination of the BCOP with the CWPS is an economical, high-efficient and feasible process in treating the polluted raw water. The combination process has a good application prospect in the pollutant removal of drinking source water in China.