Study On Enhanced Coagulation Of Fe(Ⅱ)&Mn(Ⅱ) Removal From Drinking Water By Peroxidation Technology

Iron and manganese element are two of the most common heavy metal elementsin ground surface, which is also necessary for human beings. Iron and manganesepollution of drinking water source is a worldwide problem, especially in a lot ofcities in the north of China, where taking undergroundwater as drinking water areoften found the iron and manganese of exceeding standard. In recent years, thequality of undergroundwater of the north cities or areas is rapidly deteriorated, plusiron and manganese exceed standard badly, which brought the threat to the use ofresidents’ drinking water safety siriously. In2007, our country carried out the newdrinking water health standards(GB5749-2006), in which iron and manganese indrinking water standards were adjusted to0.3mg/L and0.1mg/L, and it demandshigher requirement to the technology in cleansing drinking water of removing Fe andMn.Coagulation sedimentation is the traditional way of removing Fe&Mnindrinking water, but for now this kind of method is hard to meet the requirements ofnational standards to remove Fe and Mn. Undergroundwater Fe&Mn element oftenstates at a low price in the form of Fe (Ⅱ) and Mn (Ⅱ).If these two kinds of metalelements are proceeded for pre oxidation treatment, it would make the removalefficiency increased. This thesis choose the potassium permanganate and hydrogenperoxide, potassium ferrate and chlorine dioxide as four kinds of strong oxidizer ofiron and manganese removal experiment by alone or combinationally, and study theeffect of different conditions on the removal rate, the last to assess the method andthe selection of oxidant.The results show that the effect of Fe&Mn removal by chlorine dioxide isrelatively good under the circumstance of7.0~8.0pH and3min peroxidation time,which can totally meet the drinking water standards. But its oxidation by-productschlorite (ClO-2) may bring secondary pollution risk. So studies combined thechlorine dioxide and potassium permanganate, hydrogen peroxide, potassium ferrateto the experiment of iron and manganese removal. It found that the oxidation abilityof hydrogen peroxide is not enough to meet the requirement of Mn removal, and theother two kinds of oxidants can take a better removal effect.The experiment resultsshowed that when the throwing ratio of Chlorine dioxide combined with potassium permanganate, potassium ferrate reached1.0and1.33,the effects off removing Feand Mn is the best, and the risk of second pollution decrease the most. Consequently,for now it has good prospects to this kind of oxidant preoxidation technology forpractical engineering.