| Pollution incidents of the taste and odor compounds(T&O)in drinking water occured frequently recently.The typical T&O of 2-methylisoborneol(2-MIB)and Geosmin(GSM)have been widely concerned.Some researchs on the removal of T&O have already been carried out,but most of them focued on only a single method,being short of systematic comparison of different methods and especially lacking of the practical operation.In this dissertation,the removal effect of five methods containing aerated stripping method,coagulation precipitation method,KMn O 4 pre-oxidation method and ozone oxidation method were studied and the optimal method was selected.On this basis,pilot studies were further carried out in two respects: one is emergency measures in water treatment plant and another is enhancement of daily treatment process.The removal efficiencies of 2-MIB and GSM were compared by several processes including aeration,coagulation and sedimentation,KMn O 4 preoxidation,ozone oxidation,powdered activated carbon(PAC)adsorption and granular activated carbon(GAC)filtration.The results showed that ozone oxidation,PAC adsorption and GAC filtration could remove 2-MIB and GSM effectively.Based on results above,systematic optimization were carried out for the selected method.For ozone oxidation,the dosage of ozone,p H and reaction time had a great effect on removal rate of 2-MIB and GSM.Under the condition of 2 mg/L of ozone,15 min of reaction time and the p H of 7,the removal rate of both 2-MIB and GSM could reach 80%.The removal rate of 2-MIB and GSM were up to 90% under the conditions of 20 mg/L of PAC and 30 min of adsorption time.For GAC,2 L of water could be treated well with per gram of coconut shell GAC by RSSCT,when the concentration of 2-MIB and GSM were 100 ng/L.On the basis of beaker test and the pilot experiment were carried out for the enhancement daily treatment process and emergency control measures in water supply plant.For the enhancement daily process,adding ozonation+GAC filter unit was benifit for the removal of 2-MIB and GSM.40 days continuous operation experiments showed that the concentration of 2-MIB and GSM in the effluent were less than 10 ng/L stablely when the influent 2-MIB and GSM were 100 ng/L,and all of the remaining conventional parameters satisfied the drinking water standard.For emergency control measures in water supply plant,the addition of PAC to the raw water was the best way for T&O control.In case of 100 ng/L of 2-MIB and GSM,the dosage of PAC was 30 mg/L and the reaction time was 40 min.Foll owed by subsequent conventional treatment processes,the concentration of two odorants in the effluent could be controlled under 10 ng/L. |
