Emergency Treatment Measures For Organic Micro-pollution And Sudden Pollution Of Petroleum And Phenol In Source Water

With the acceleration of urbanization process in China, the demand of domesticwater is increasing. Also, because most parts of China use the reservoir water as sourcewater, inter-annual rainfall changes can easily lead to supply shortages of domesticwater, which often compel us to use alternate source water to meet the needs of the city.In southern China, water supply plant usually selected nearby lake as alternate sourcewater, but organic micro-pollution and possible sudden pollution problems can not beignored.This subject is carried out according to the problem we have to face with whenusing alternate source water. Studying emegency treatment method which based on thecombination of powdered activated carbon, advanced oxidation technology andconventional treatment process to solve the problem referred above, determining theoptimal operating parameters.Conventional water treatment processes have relatively obvious removal abilityof CODMnand UV254, but due to the high background values, the values of CODMnandUV254are still very high after the treatment process of coagulation and precipitation.Pilot tests showed that the removal efficiency of petroleum was up to50%whenutilizing conventional treatment processes to treat the0.5mg·L-1petroleum pollution.Conventional treatment processes don’t have obvious removal ability of phenolpollution, even though the dosage of coagulant is100mg·L-1, the remaining phenol inraw water is still up to160μg·L-1when the original concentration of phenol is100timesthe limit.When combined with conventional treatment process, a substantial raise of CODMnremoval efficiency needs the dosage of powdered activated carbon reaching20mg·L-1.The proposed dosing position of powdered activated carbon are at the initial stages ofcoagulation and flocculation stage. Freundlich adsorpion isotherm is more suitable forcharacterizing the relationship of adsorption capacity and adsorption processesequilibrium concentration when utilizing the powdered activated carbon dealing withpetroleum and phenol contamination. The adsorption rate of petroleum conforms to thepseudo first-order kinetics, while the adsorption rate of phenol conforms to the pseudosecond-order kinetics. When the dosage of powdered activated carbon is fixed, theadsorption capacity increases accompanying with the concentration increase of phenol.The removal rate of phenol does not change significantly when the dosage of powderedactivated carbon is10~20mg·L-1. In the trial of ozone oxidation, the value of CODMndeclines initially, then arises and finally declines. Referring to the removal efficiency ofCODMn, O3/UV is better than ozone oxidation alone, while ozone oxidation alone isbetter than O3/H2O2. Ozone oxidation process has significant effect on the removal of phenol. When the dosage of ozone is5.52mg·L-1, phenol polluted water which exceeds10to100times will drop to the limit. While the dosage of phenol is among0~5.52mg·L-1, the production of bromate and formaldehyde is within the limit.Combined process O3/UV+PAC+powdered activated carbon can make the value ofCODMndrop from6mg·L-1to3mg·L-1or so, the cost of treating a ton of water is about0.164yuan; combined process powdered activated carbon+PAC can make effluentpetroleum concentration down to0.3mg·L-1or less when the initial concentration ofpetroleum is1.5mg·L-1, the cost of treating a ton of water is about0.164yuan;combined process O3+powdered activated carbon+PAC responds effectively to thephenol pollution which exceeds100times the limit, effluent phenol concentration is2μg·L-1or less, the cost of treating a ton of water is about0.448yuan.