| In recent years, because of industrial, agricultural and urban pollution, the quality of drinking water sources is becoming worse and worse. Though conventional water treatment has played an important role in past years, it is now found ill-fitted because of increasing mutagens and carcinogens in chlorinated water. So how to reduce chlorination disinfection by-products (DBFs) has been greatly concerned. In this text, we discussed the effectiveness and mechanism of Os/GAC technics in removing natural organic matters (NOM) and disinfection by-products precursors.Ozonation coupled with granular activated carbon adsorption (CVGAC technics) is proved to have a good effect in dealing with low organic polluted raw water. It shows distinct advantage in reducing NOM and disinfection by-products precursors when compared with conventional water treatment, OB and GAC single technics.The quality of effluent water depends on ozone dose, carbon adsorption time and the character of raw water. The analyses of samples show results: there is a best ozone dose for a particular raw water which varies with the quality of water; the removal ratios of all indexes increase with prolonged carbon adsorption time before 15-25 minutes; Os/GAC technics can apply stably under different water quality conditions(CODMn 4-8).However, when source water is seriously polluted by organics, the concentration of CODMn can't meet the drinking water regulations using one-stage Os/GAC technics. Increasing ozone dose or prolonging carbon adsorption time is proved to have little effect. On the basis of mechanism of Os/GAC technics, we put forward two-stage CVGAC technics which not only make CODMn up to dar, but also greatly reduce disinfection by-products precursors. |
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