Investigation of As, Mn and Fe fixation inside the aquifer during groundwater exploitation in the experimental system imitated natural conditions

Abstract

Water-dissolved oxygen was supplied into anaerobic aquifer , which oxidized Fe(II), Mn(II) and trivalent arsenic and changed them into undissolved solid matter through hydrolysis, precipitation, co-precipitation and adsorption processes. The experiment was carried out on the column imitated a bore core of anaerobic aquifer with water phase containing Fe(II), Mn(II), As(III) concentration of 45.12 mg/L, 14.52 mg/L, 219.4 μg/L, respectively and other ions similarly composition in groundwater. After 6 days of air supply, concentration of iron reduced to 0.38 mg/L, manganese to 0.4 mg/L, arsenic to 9.8 μg/L (equivalent 99.16% of iron, 97.25% of manganese and 95.53% of arsenic fixed), and for other ions, the concentration changed almost according to general principles. Ion phosphate and silicate strongly influenced on arsenic removal but supported iron and manganese precipitation from water phase. Based on the experimental results, new model of groundwater exploitation was proposed.