Experiment On The Purification Efficiency And DO Demand Of Compound Micro-polluted Groundwater With Contact Oxidation Filtration

Due to the geographical reasons,part of the north region groundwater which contains excess iron and manganese.This years,industrial and domestic sewage discharge groundwater polluted by ammonia nitrogen and organics,gradually formed the Compound Micro-polluted Groundwater,it becomes even more difficult for water purification.Therefore,it has become an uegent problem to explore the economic and efficient processing method.We can find from a wide range of study on compound micro-polluted groundwater purification that filter material combinations,filter thickness,temperature,filtration velocity and DO content are the main factors influencing the purification effect.So,to get the best operation parameters for filter chamber,it need to comprehensive analysis of influencing factors in order to realize the removal of iron,manganese,ammonia nitrogen and organics at the same time in the contact oxidation filter chamber and maintain an efficiency and stability purification ability.From the parallel contrast experiment of four filter column systems under different aeration intensity to analyze the purification effect of contact oxidation filtration method to deal with compound micro-polluted groundwater.The combination of each group is manganese-ceramsite-manganese sand,the grain size of manganese sand and ceramsite is 1.25-1.60mm,the filtering layers of filter columns at all levels are all 0.5m and 1.5m in total.The aeration intensity of four filter column are respectively dropping aeration(1#),the second stage increase aeration device(2#),second-thrid stage increase aeration device(3#)and three stage increase aeration device(4#).Four columns started with 2m/h filter speed,during the experiment,according to the purification effect of each filter column and increased the filter velocity to 3m/h,4m/h,5m/h,6m/h.The experiment lasted for 334d.Four columns introduced the same water quality,using FeSO4·7H20,MnSO4·H2O,NH4CL,organic matter to simulate the micro-polluted groundwater,the composition of organic matter were humic acid,urea,starch.The average water quality were as follows:1.34?2.55mg/L for Fe,2.17?3.78mg/L for Mn,2.83-4.74mg/L for NH4+-N,1.26?6.09 for CODMn.The removal of Mn2+ was the most difficult,and Fe2+ was easiest,the order of the standard were Fe2+,NH4+-N,Mn2+(the CODMn had a low degree of overweight,and it's easy to meet the standard).The standard time of each group respectively:219d for 1#,170d for 2#,3#,4#.The DO consumption of each group while standard time respectively:11.09mg/L for 1#,11.12mg/L for 2#,12.19mg/L for 3#11.93mg/L for 4#.The study shown,increased the aeration intencity could enhance the purification ability of the filter column system.When the temperature was above 20 ?,the effective purification filter speed of 1#could achieve 2m/h,DO consumption was 11.01mg/L.2#could achieve 4m/h,DO consumption was 15.27mg/L.3#and 4#could achieve 6m/h,DO consumption were respectively 15.73 mg/L,15.81 mg/L.When the temperature down to 12??15?,the purify ability of each group has been affected,effluent concentration of each index increased,and the Mn,NH4+-N of 1#,2#,3#were not up to standard,but 3#could recover soon and met the standard.The Mn,NH4+-N concentration in the effluent of 4#had a trace increase,but still meet the standard.It shown that,the influence of temperature on the purification effect would be reduced in situations where plenty of DO and mature filter system.The purification effect of 4#was the best.Under 6m/h filter speed,average concentration of Fe,Mn,NH4+-N are 0.09mg/L,0.01mg/L,0.24mg/L.It has a low influent concentration of organic matter for 2.40mg/L,average ramoval rate of CODMn was 83.19%,effluent concentration was 0.40mg/L under 6m/h.Under 6m/h,3#met the standard and average concentration of Fe,Mn,NH4+-N were 0.14mg/L,0.03mg/L,0.34mg/L.Average ramoval rate of CODMn were 75.42%,effluent concentration was 0.66mg/L.Increased aeration device contributed to rise the removal space of Mn and NH4+-N.1#needed 1.5m filter thickness under 2m/h filter speed.2#needed 1.5m filter thickness under 4m/h filter speed.3#needed 1.5m filter thickness under 6m/h filter speed.4#needed 1.2m filter thickness under 6m/h filter speed.Within a certain range,increased the filter velocity would increase the flow of water to deal with in unit time,so that,the DO consumption would increase.Continue to increase the filter velocity when filter column system reach the efficient purification ability,the DO consumption would decrease due to the HRT became short.The DO consumption of 1#in the condition of 2m/h,3m/h,4m/h were respectively 11.01mg/L,12.52mg/L,12.21mg/L.3#in the condition of 2m/h,4m/h,5m/h,6m/h were respectively 12.68mg/L,15.36mg/L,16.46mg/L,15.73mg/L.