Research On Enhanced Removal Of Thallium In Drinking Water Based On Tradtional Water Supply Process

In recent years, the accident pollution of water resources are occured frequently,espcially heavy metals pollution in the water resource having a signnificate flunence ondrinking water quality. Howerver, quite a kind of hevay metal could not be treated qulitifiedby the current processes in water plants. It’s very important for us to find an efficient andsafety method to treat the raw water polluted by the trace of heavy metalsIn this study we aimed to sovle the probable exsisted pollution by thallium in raw water.The measures of pretreatment and enhanced coagulation were carried out to improve theremoval effeciency of the thallium by the traditional clarification processes. The removalability of the convention process was investigated and so does its influencing factors. Theunion process combined potassium permanganate (KMnO4) with power activited carbon(PAC) was presented on the bass of the regular process. The influencing factors of the unionprocess for thallium removal were studied. We also investigated the removal effects on theother oxidants and carried out the productive experiment in the final. The followings are themain results and conclusions.(1) Researching the effect of current process on removal thallium, results showed thatonly little of thaliium was removed by the current treatment processes and the outflow watercould not meet the drinking water standard demand. The influencing factors, such as pH valueand dosage of coagulant, were researched and the results showed that the removal efficiencieswere improved by the increasing dosage of coagulant and pH value.(2) The feasibility of removal capability of thallium by union process combined KMnO4and PAC was investigated in this study. Results showed that thallium was effectively removedby combined KMnO4and PAC, and the effect of thallium removal was higher than that justonly of them. Results of the orthonogal experiments of the union process showed that KMnO4might have a significant impact on the removal efficiency of thallium. Two processes wereobtained from the orthonogal experiment—the optimal process and economy process. Theformer had the ability to treat the raw water with thallium lower than1.24μg/L, while thelater was0.64μg/L. The mechanism of removal thallium by KMnO4was preliminaryresearched. Results indicated that KMnO4couldn’t convert thallous ions to thallic ions in the neutral or alkaline conditions. It was the newly formed manganese dioxide (MnO2), thereduzate of KMnO4, played an important role on the elimination of thallium and it couldremove the thallium of the simulated solution from0.4μg/L to0.003μg/L.(3) The removal effects of hydrogen oxide, sodium hypochlorite and ozone werereseached. Resluts showed that the treatment effect of ozone was better than others under thesame dosages. When ozone dosage was4mg/L, it could treat the raw water with concentrationof thallium of0.455μg/L qualified. The removal effeciencies of two of the three oxidants werebetter than one of them.(4)The small scale productive experiments were acrried out bass on the results of staticexperiments.Results showed that just adding KMnO4, chlorine or adjusting pH value had littleinfluence on the removal of trace thallium in the raw water. Howerver such as dosage KMnO4and adjusting pH or dosage KMnO4and chlorine had improved the removal effeciency ofthallium.