| O3-BAC process exist two serious problems in the application, the ozone dosagecontrol is arbitrary which is not conducive to save energy and guarantee water quality.Beside, BAC filter offers a more suitable condition for breeding aquatic microzoons，which will get through the BAC filter in the southern humid areas.This study wasbased on the climate and water conditions of Pearl River downstream. And it wasabout the optimization ozone dosage for the Ozone-Biological Activated Carbon（O3-BAC） process. The experimental include: study on the qualitative andquantitative relationship between pre-ozone and coagulation aid and algae killing.Comparative study on treating pollutants effect and ozone consumption betweenconventional O3-BAC and mid-positioning O3-BAC. Study the main role ofpost-ozone in water treatment process. The disinfection effect for microorganisms andmicrozoons by ozone. Research developed a process for treating micro-polluted water,with pre-ozonation, main-ozonation，post-ozonation and combine with aeratedbiological activated carbon process, which applied in the depth of the treatmentprocess of the water supply. Study shows:（1）For Shunde waterway II?III class water source,0.5mg/L was the optimalpre-ozone dosage. The turbidity of sedimentation tank reduces most, algae ould not bedetected in sand filter, and ensured the normal operation of the follow-up process.（2）When ozone dosage was between0.5?2.0mg/L, ozone actual consumptionand utilization rate were higher in mid-positioning O3-BAC process with the sameozone dosage, and with the same ozone dosage the treating effect for pollutants ofmid-positioning O3-BAC process was superior to conventional O3-BAC process.（3）For easily biodegradable organics （CODMn） and ammonia nitrogen, throughthe aeration increase dissolved oxygen and mass transfer eiffciency could get betterremoval eiffciency than ozonation. When concentration of CODMn or ammonianitrogen is high, it was recommended to adopt aeration activated carbon filter,through aeration instead of adding ozone to provide oxygen to the carbon filter. As forUV254kind of macromolecular refractory organics aeration could not increaseremoval rate of UV254obviously. Ozonation can improve removal effect of UV254,when refractory organics concentration is high or by sudden pollution, should adoptmid-positioning O3-BAC process and add ozone to deal with.（4）Disinfection with ozone and kept residual O3more than0.2mg/L and maintain10minutes for reaction, microorganism could be killed include thosewithstrong chlorine resistance microzoons，such as Chironomid Larvae, Cyclop andNematode.（5）In the optimization processes, the value of all kinds of disinfectionby-products of eflluent are lower than the limit of drinking water sanitary standard.UMU test results were negative, elffuent water is safe.（6）Developed a process for micro-polluted water, with pre-ozonation,main-ozonation，post-ozonation and combine with aerated biological activated carbonprocess. The operating mode for different water source depend on water quality andtest results. |
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