Study On Use Of Strengthening Coagulation-flocculation And Biological Contact Oxidation For Slight-polluted Source Water

At present source water has been increasing polluted. The conventional water purification system (CWPS) can not remove the polluates including the dissolved organic matter, NH₄⁺-N and NO₂^--N in the raw drinking source 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 effficiency, stable running and convenient management. In the article we put to test on the branch of Changjiang River, Zhengshui River in Hengyang by conjunctive use of strengthening coagulation-flocculation(SCF) and BCOP.The experiment use the potassium permanganate (KMnO₄) and the hydrophilic suspending plastic filler. Because KMnO₄ has strong oxidation, it can oxidize the high molecular weight(HMW) organic matter into low molecular weight(LMW) organic matter. The microbes on hydrophilic suspending plastic fillers can eat away the LWM organic matter. In the study, under the controlled conditions: water temperature 16.8～30.5℃, turbidity 7.78～33.41 NTU, COD_Mn 2.40～8.36 mg/L,UV₂₅₄ 0.035～0.075cm^-1,NH₄⁺-N density 0.26～2.22 mg/L and add KMnO₄ 0.2～0.8mg/L, polyacry ferric sulfate (PFS) 20-30mg/L, polyacry lamide(PAM) 0.1mg/L, biologic filler addition rate 42% and reaction time 80min, it demonstrated that the conjunction could effectively remove turbidity, COD_Mn,UV₂₅₄ and NH₄⁺-N, the corresponding removal percent reached 38.68～94.76%,25.45～67.14%,9.77～40% and 22～65%. We analyse the principle of the coagulation and the influencing factor on BCOP.We also analyse the principle of BCOP. The microbes play a role in the biodegradation of BCOP. The microbes on the filler main depende on adsorpion, biologic flocculation, biologic degradation and nitration to remove the polluates. The research results show the optimal combination of the SCF and the BCOP is an economical, high-efficient and feasible process in treating the polluted source water. The combination process has a good application prospect in the slight pollutant removal of drinking source water in China.