Research On Efficacy And Mechanism Of Arsenic Removal By Biological Iron And Manganese Removal Filter

In recent years, arsenic contamination in ground waters attract more and more attention, many countries and regions have met the problem of arsenic contamination in drinking water, and this problem also harass our country. Chronic exposure to arsenic contaminated drinking water can result in serious health problem, so new technique for inadequate, effective arsenic removal is dire needed. Because As, Fe²⁺, Mn²⁺often coexisted in groundwaters, biological iron and manganese removal filter have advantages on iron and manganese removal in groundwaters , so the main content of this research is efficacy and mechanism of biological iron and manganese removal filter application on arsenic removal, aiming at guidance on project. The main content of this research dispart to three parts, the first is adsorption of biological iron and manganese oxides, the research measure is adsorption captive test.The second part is efficacy of biological iron and manganese removal filter application on arsenic removal, the treatment process was based on a pilot scale biological filter column. The last is mechanism of biological iron and manganese removal filter application on arsenic removal, the research measure is biological filter column combine with characterization of biological precipitation products performed by XPS. The adsorption experiment of biological iron and manganese oxides shows that the biological iron and manganese oxides have good adsorption capacity, the maximal adsorption capacities of As(III) and As(V)were 563.24μg/g,303.47μg/g, respectively.The adsorption process can mostly accomplish in 30 minnutes. The greatest adsorption occurred under acidic conditions. phosphate was the greatest competitor with arsenic for adsorptive sites on the adsorbent.The experiment of biological filter column shows that, biological iron and manganese removal filter has good efficiency on both As(III) and As(V) removal.When the initial concentration around 200μg/L, the residual arsenic concentration was below the limit of arsenic in drinking water(10μg/L),and the removal of iron and manganese was not declined.The main arsenic removal was take place in above bio-filter. In experiment condiation, the filtration velocity was 5m/h,the initial concentration of As(III) can reach 200μg/L, the initial concentration of As(V) can exceed 200μg/L. In minutes after backwashing, the arsenic and iron can not reach the limit in drinking water.The experiment of mechanism shows that, microorganism and manganese oxides can both oxidate As(III) to As(V), iron oxides have good adsorption capacity on arsenic, the microorganism along with its secretion, iron and manganese oxides, organic substance in bio-filter form bio-membrane and microbe-sludge,they has high surface area and well adsorption capacity, and exhibit important function on arsenic rimoval.So the arsenic removal can attribute to integration results of the above actions.