Efficiency Of Water Treatment Of Qingyuan Reservoir By Ozonation And Powdesred Activated Carbon Process And Controlling Of Chlorine Disinfection By-products

In this study,the dissolved organic matter(DOM)removal and disinfection by-product(DBP)reduce as a function of ozonation and powdered activated carbon(PAC)adsorption were researched in Qingyuan Reservoir water located in Shandong province.In order to achieve a better water treatment effection,we explore the optimum coagulant dosage,the optimum adsorption conditions and the optimum ozonation time according to UV254 and DOM removal of the raw water.The three-dimensional excitation and emission matrix(3 DEEM fluorescence spectroscopy was used to analysis the physicochemical properties changes of DOM.As to disinfection experiment,both carbonaceous DBP(C-DBP)and nitrogenous DBP(N-DBP)formation and speciation were analyzed.The influence of chlorine dose,contact time on DBP formation and speciation were also studied to optimize the disinfection conditions to minimize the DBP formation.Reservoir water intended for drinking water supply was treated by(?)coagulation(CT);(?)coagulation combined with adsorption(CT-C);(?)coagulation,ozonation and subsequent adsorption(CT-O3-C);(?)pre-ozonation,coagulation,and subsequent adsorption(O3-CT-C);.Influences of four treatment processes on C-DBPs and N-DBPs concentration,species,THM formation potential,THMs formation kinetics and bromine incorporation factor(BIF)were analyzed.The main results were summarized as follows:(1)Coagulation could remove organic matter from Qingyuan Reservoir water,but the effect is limited.In the process of polyaluminium chloride(PAC1)dosing increased from 0 mg/L to 12 mg/L,dissolved organic carbon(DOC)removal rate was lower than 50%.PAC adsorption obviously improved the DOM removal and the optimum PAC dosage was 1.0 mg/L.The CT-C could improve the removal efficiency of DOC to more than 80%.The pre-ozone was effective for oxidizing NOM with double bonds and aromatic structure to simple compounds but do not eliminate thoroughly from the water.There was linear relationship between ozonation time and UV254 removal.The addition of ozone could improve the organic matter removal rate by 10%further.CT-O3-C has the best organic matter Removal efficiency among the four combined processes.(2)Disinfection experiment showed that the extension of disinfection time will increase the concentration of most C-DBPs and N-DBPs.Trichloromethane(TCM)and Dichloroacetonitrile(DCAN)were the dominant species of the C-DBP and N-DBP respectively.With the increase of disinfection time,the concentration of other brominated THMs(Br-THMs)increased and the proportion of TCM decreased.TCAN is unstable N-DBP which would hydrolysis with the extension of disinfection time.The increase of Chlorine dosage improved the yields of chlorinated DBPs(Cl-DBPs)and reduced the concentration of brominated DBPs(Br-DBPs)in C-DBPs.While chlorine dosage had slight influence on N-DBPsyield in this study.(3)The combination of CT-C could remove more than 70%THMs and 93%HANs precursors,while the removal rates were only 10.5%and 45%for CT.The added ozone reduced the concentration of total THMs,increased the HAN hydrolysis rates,lowered the yields of HANs further,but improved trihalomethane formation potential(THMFP)and increased the Br-THMs which have a higher toxicity.The increased bromine incorporation factor(BIF)showed that the addition of ozone enhanced the combined ability of organic matter with bromine.(4)THMs formation kinetics parameters illustrated 25.6%THMs precursors could react with chlorine and produce THMs in a short time,which was defined as fast reaction DOM.The traditional coagulation treatment and PAC adsorption could removed the fast reaction DOM easily.CT-C has the minimum TTHM yield coefficient indicating the CT-C had better removal effect on DOM which combination with chlorine easily.