Research Of Combined Effects Of Ozone-coagulation For Drinking Water Treatment

With the increasing problem of environmental pollution and the increasingly stringent water quality standards, conventional coagulation technology has not met the requirements of water quality and safety. Conventional Water Treatment Process consist of coagulation, sedimentation, filtration and disinfection. In order to meet the pressing environmental, more and more sewage treatment plants use pre-ozonation technology for treating drinking water. Ozone can remove the chrominance and odor, and also can change the nature of the organic matter in water, making it easier to remove in subsequent processing, but ozonation of follow-up coagulation process is not clear.This paper studies the impact of using ozone pre-oxidation, enhanced coagulation and ozone-coagulation to the removal of water pollutants. Simulate natural bodies of water and wastewater were the studying object, different basicity polyaluminum chloride (PAC1) and polymerization of ferric chloride (PFC) were used as coagulant, using the method of combining the static beaker tests and dynamic simulation. The detection of water quality indicators, organic compounds by GC-MS analysis, compared the treatment effect of the different processes on the water, studied the interaction between ozone pre-oxidation and enhanced coagulation, preliminary study of the mechanism of ozone-coagulation associated with removal of organic pollutants in water. The following conclusions are summarized:(1) Ozonation of Simulate natural body of water, coagulated the ozonation water with different basicity of PACI and PFC as coagulant, within similar role of coagulant dose, PACI (B=0) the role of water compared with PACI (B=2) the role of water, the turbidity removal efficiency higher than4.47%, the removal rate of UV254is higher than31.89%; PFC (B=0) the role of water compared with the PFC (B=2) the role of water, the turbidity removal rate higher than24.34%, the removal rate of UV254is higher than12.11%, the effect of two coagulant, algae can be removed completely, the removal efficiency of Chl-a more than95%. The results show that basicity (B=0) coagulant, its effect is better than the basicity (B=2) coagulant.(2) Ozonation and coagulation alone treated water samples respectively, The turbidity and DOC removal rate were lower than the water samples treated by coagulation after ozone pre-oxidation. ozonation of treated water by coagulation, when the ozone concentration of3mg·L-1, the coagulant dose of3mg·L-1, turbidity dropped to the lowest value of0.736NTU, DOC concentration dropped to the lowest value of0.9mg·L-1, turbidity and DOC removal rate higher than the ozone concentration of1mg·L-1, the coagulant dose of3mg·L-1action over the water samples. The results show that the significant effect of the kind of water turbidity and DOC removal by coagulation after ozone pre-oxidation.(3) Application the usage of ozone pre-oxidation, enhanced coagulation and ozone-coagulation integration to process the simulated chemical wastewater, through the water by GC-MS detection, it can be seen that the original water is majority of BTEX, alcohols and esters, also contained a number of alkanes, alcohols and acids. Separate coagulation treated water samples, detected in the vast majority of organic matter; Ozonation of treated water samples, BTEX, alkanes, alcohols, esters were not detected; Ozone-coagulation combined with treatment, its organic species significantly changed, only detected some alcohols (and)esters. Description of ozone-coagulation associated with a significant deal with the removal of the vast majority of organic matter in the simulation of chemical industrial wastewater, which is obviously superior to the single coagulation, ozone oxidation.(4) The effect of ozone strong oxidation the damage to the long chain of refractory organics in water, to make them break down into smaller molecular weight organic, these organisms can promote the further conduct of the coagulation, main performance in the following aspects:firstly, the ozone will destroy the organic matter in groups, reduce the organic matter in surface charge density, and reduce the complexation of organic matter with iron and aluminum ion; secondly, ozone formatted positively charged intermediates in the decomposition process, which can play in the role of neutralization of organic matter in surface charge. Subsequent coagulation process, organic molecules can be removed through the flocculants adsorption precipitation, low molecular weight dissolved organic matter is oxidative degradation, so that complex organic compounds to be further reduced.