| Arsenic is one of the toxic pollutants in water.Arsenic pollution in drinking water has become a serious problem on a global scale,increasingly threatening human health.Ammonium,iron,manganese and arsenic often coexist in groundwater.Fe-Mn binary oxide as an adsorbent removing arsenic combines with strong adsorbability of iron oxide and oxidability of manganese oxide,with the characteristic of simple and easy-to-operate process,environmentally friendly,economy etc.In this paper,the operating effect of removing ammonium,iron,manganese and arsenic（V）individually and simultaneously in groundwater by the contact oxidation filter was studied.The influence of water condition and operating parameters on the removal efficiency of arsenic was also analyzed.The mechanism of arsenic removal by the contact oxidation filter was studied combining the material characterization of active Fe-Mn bimetal oxide filter before and after the adsorption,the adsorption characteristic and influencing factors in lab-scale.These studies have provided technical support in the application of the contact oxidation filter used to remove pollutants in groundwater.The main component of the active Fe-Mn bimetal oxide filter of the contact oxidation filter was iron and manganese.It was granular and porous,providing abundant contact area for pollutants adsorpting on the surface.The filter had a good ability of removing arsenic（V）、iron、manganese and ammonium individually,showing a powerful resistance to impact load,while it also can simultanously remove these four pollutants in an effective way.The presence of iron and manganese can improve the removal efficiency of arsenic（V）and the filter can have stable removal capacity of coexisting with high iron or manganese concentration load.With water p H increased,the removal efficiency slightly decreased.But in the condition of high arsenic groundwater（p H is 7.18.7）,the filter remained good ability of arsenic（V）adsorption.The influent arsenic（V）load or filter speed increased,the filter depth reaching the standard increased.But the effluent arsenic（V）concentration can meet the required standard under the pilot-scale experiments,showing a powerful resistance to impact load.There were no significant differences of the form of active Fe-Mn bimetal oxide filter of the contact oxidation filter before and after the adsoption.The active Fe-Mn bimetal oxide filter composed of iron and mangenese,containing arsenic after adsorption,indicating its ability to remove arsenic（V）.The main crystal structure was（Ca,Mg）Mn14O27 · XH2 O,without changing before and after reaction with arsenic（V）,while it formed a new As-O bond after the adsoption.The active Fe-Mn bimetal oxide filter was a uniform property adsorbent,and had a high saturated adsorption capacity towards arsenic（V）.The adsoption process was fast and belonged to chemisorption.Intragranular diffusion was not the only process controlling the reaction.The adsorption capacities and Zeta potential decreased as p H value grew.The presence of CO32-obviously inhibited the adsorption.With the increase of the active Fe-Mn bimetal oxide filter dosage,the arsenic（V）removal rate increased and the adsorption capacity decreased. |
