| With the rapid development of social economy,water pollution control has received more extensive attention,and the effective removal of PPCPs pollution is a difficult problem in current research.Sewage treatment plants are an important place to remove PPCPs pollution,but the existing conventional processes are difficult to efficiently remove traces of refractory organics such as antibiotics and psychotropic drugs.Chlorinebased oxidants are commonly used disinfectants in sewage plants,and the advanced oxidation process combined with the chlorine disinfection process and vacuum ultraviolet is an emerging PPCPs treatment technology,and this process does not require new structures and has strong applicability.The hydroxyl radicals and chlorine radicals produced by the vacuum ultraviolet/chlorine advanced oxidation technology have strong oxidizing ability,which can meet the water quality improvement and disinfection needs of sewage plants while solving the problem of PPCPs pollution.Using carbamazepine(CBZ)typical anti-epileptic drugs as PPCPs model pollutants,a vacuum ultraviolet/chlorine advanced oxidation system was constructed.It is intended to use the strong oxidizing active substances in the system to achieve high-efficiency removal of trace PPCPs pollution while removing COD in sewage to improve the effluent quality of sewage treatment plants.The synergy of vacuum ultraviolet and chlorine to remove CBZ was studied,and the test results showed that the VUV system and chlorine have a better ability to remove CBZ synergistically.The single factor test method was used to optimize the experimental conditions of vacuum ultraviolet/chlorine technology to remove CBZ.The optimal reaction conditions were p H=6,chlorine dosage was 8 mg/L,CBZ initial concentration was 30 μM,and circulating flow rate was 80 h/L,the removal effect of CBZ is the best,and the removal rate exceeds 99.5% in 16 minutes of reaction.Research on influencing factors shows that sulfate ions and bicarbonate ions in the water have little effect on the removal of CBZ from the vacuum ultraviolet/chlorine system,but nitrate ions,chloride ions,reaction temperature,and natural organic matter in the water have a strong weakening effect on the reaction.By monitoring the consumption of free chlorine in different reaction processes,it is found that the consumption of free chlorine in the vacuum ultraviolet/chlorine system is mainly caused by ultraviolet light excitation and the reaction with pollutants and degradation products is relatively weak.Through free radical quenching experiments,it was found that the oxidation and direct photolysis of HO· and Cl· existed in the system.Through the competitive degradation test,it is found that the main effect of the system is HO·oxidation.With the increase of p H,the contribution of HO·oxidation increases,the contribution of Cl·oxidation decreases,and the contribution of direct photolysis does not change much.In order to improve the engineering applicability of this technology,this paper prepared CBZ solution and high COD simulated sewage with the effluent from the secondary sedimentation tank of a sewage plant,and discussed the applicability of the vacuum ultraviolet/chlorine technology in the secondary sedimentation tank.The test showed that when The dosage of chlorine is 8 mg/L,and the reaction is 30 minutes.The VUV/chlorine advanced oxidation technology can remove 95.3% of the CBZ in the effluent of the secondary sedimentation tank;this technology has a good removal effect on the simulated sewage COD,and the COD concentration is 63.6 mg /L is reduced to44.2 mg/L,and the removal rate is 30.5%,which can meet the COD limit of Class A standard in the "Emission Standard for Pollutants for Urban Wastewater Treatment Plants"(GB18918-2002).The VUV/chlorine advanced oxidation technology has applications Potential for upgrading and upgrading of wastewater treatment plants. |
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