Study On Emergency Of Manganese Removal In Raw Water Through Pre-oxidation

In recent years,pollution caused by the seasonal and sudden exceeding of the content of managanese is common in many regions of China.Each year,from June to September,and December to February,there will be a phenomenon of the seasonal exceeding of the content of managanse for the raw water in certain city of the South.Among which,the concentration of managanse is 0.51⁰.71mg/L.The conventional water treatment did well to the removal of Fe²⁺,but not Mn²⁺.To solve this problem,through preoxidation,this research first oxidated the dissolved Mn²⁺ into suspended MnO₂.m H₂ O,then sedimentated that through coagulation and sedimentation,thus achiving the goal of emergent removal of managanse.This experiment mainly focused on the performance of iron and managanse by preo-xidatant of KMn O₄,Potassium peroxymonosulfate,Na Cl O.Through the analysis of the influence of the dosage of oxidants,PH,preoxidation time,the concentration of Mn²⁺,the concentration of Fe²⁺,organics on the effect of managanese removal of preoxidation,to determined the technological parameter of manganese mechanism of various oxidants.Results showed that coagulating sedimentation combined with preoxidation responded well to the removal of and Mn²⁺.Exclusive coagulation sedimentation responded well to yhe removal of Fe²⁺,but not Mn²⁺.Exclusive pre-oxidation of KMnO₄,Na Cl O and powdered activated carbon absorption,Potassium peroxymonosulfate preoxidation and powdered activated carbon absorption went well with the removal of managanese.The comprehensive effect of preoxidation of the three oxidants was as follows:KMnO₄>Potassium peroxymonosulfate>Na Cl O.The experiment assumed the manganese concentration of raw water as 0.5mg/L.Given the quality of the raw water,the dosage of KMnO₄ was 0.7mg/L,the preoxidation time was 3min,the removal rate of manganese was higher than98.00%.When Na Cl O is used as Pre-oxidant,the available chlorine dosage of Na Cl O was 2mg/L,the preoxidation time was10 min,the dosage of powdered activated carbon was 7mg/L,the removal rate of manganese was 89.24%.When Potassium peroxymonosulfate is used as pre-oxidant,the available chlorine dosage of Potassium peroxymonosulfate was 3mg/L,the pre-oxidation time was 8min,the dosage of powdered activated carbon was 5mg/L,the removal rate of manganese was 92.48%.The fluctuation of PH?6.5⁷.6?of raw water,the concentration of Fe²⁺?less than1.0mg/L?,the existence of certain organism was of little influence on the managanese removal effect of various oxidizing agents.After the pretreatment of oxidizing agent,the concentration of iron in the effulent and the managanese after sedimentation could meet the Standards for Drinking Water Quality.Characterized by high efficiency and promptness,the emergent manganese removal measures of preoxidation did not change the enhancement of water treatment structures,which was of high application value in response to contamination caused by seasonal and sudden exceeding of the content of iron and manganese in surface water.