Study On Comparison Of Advanced Treatment Between Ozone-BAC And Microaeration-BAC Processes

Both Ozone-BAC and Microaeration-BAC processes have been worldwidely applied at home and abroad, however, there are still lack of enough pilot-scale experience in term of applying these two processes in the raw water from upreaches of Huangpu River. A special study was conducted in our lab in order to compare the process of "Conventional treatment + Ozone-BAC" with the other process of "Conventional treatment + Microaerotion- BAC".The removal of many water quality parameters by the conventional process and the GAC column during the period of biofilm culturing were mainly discussed in this paper. Several influencing factors during the biofilm culturing are also researched while some optimal operating parameters for the processes of Ozone-BAC and Mircoareation-BAC were determined through the experiment. According to the monitors of water quality parameters to both processes for more than one year, many factors influencing the removal of pollutants by BAC were analyzed. At last, the removal of both processes were systematically compared during the long-term operating of BAC.The main research achievements of this paper include: The removal of NH3-N by the conventional treatment process is greatly enhanced after the bio-pretreatment process, however, the removal of COD_Mn and UV₂₅₄ by the conventional process improves nothing. The correlation between NH3-N influent concentration and removal efficiency of NH3-N by BAC could be fit into quadratic function and the peak removal efficiency of NH3-N occurred at the NH3-N influent concentration of 1.5 mg/L. The mass transfer efficiency of ozone was subject to the gas/water ratio and the mass concentration of ozone in the ozonated gas, while the operating effect of BAC was subject to many factors, consisting of temperature, influent pollutants concentration, EBCT(empty bed contact time) and effective ozone dosage. Under 2.0 mg/L of effective ozone dosage and 10 min of ozone tower contact time and EBCT, the mean removal efficiency of 30.17%, 43.33% and 21.43% were obtained forCODMn, UV254 and DOC respectively by Ozone-BAC process, while the mean removal efficiency of 17.22 %, 20.13 % and 11.96 % were obtained by CODMn, UV254 and DOC respectively for Mircoareation-BAC process. The mean removal efficiency of 35.57% and 42.47% were obtained for THMFP and HAAFP respectively for Ozone-BAC process while the mean removal efficicency of 17.38% and 12.91% were obtained for THMFP and HAAFP respectively for Microaeration-BAC process. The results from UV scanning of each units process effluents showed that ozone-BAC process removed more pollutants which adsorb UV light than BAC process. At last, Analysis was made on the variation of molecular weight distribution region (MW) of UV254 in different unit processe effluents and the experimental results showed that BAC was more effective for the removal of UV254 with MW lower than 3 KDa while a great complementary removal of UV254 with different MW was attained only by ozone-BAC process. In all, Ozone-BAC process improves the final water quality better than Microaeration-BAC process in term of the raw water of Huangpu River.