Study On Groundwater Iron And Manganese Removal By Immobilized Bio-reactor

Eight strains of bacterium which can remove iron and manganese were seperated from quarts sand, rust and soil, they were Gallionella ferruginea and Leptothrix, respectively. The iron removal bacteria belonged to Gallionella ferruginea and the manganese removal bacteria belonged to Leptothrix.A running test was done with simulant low concentration iron and manganese groundwater by immobilizing the eight strains on the quarts sand filtering medium, the common quarts sand and common manganese sand filtering medium were used as contrast. The results showed that the effluent from the bio-reactor reached national discharge standards, manganese removal efficiency was 63.4% and iron removal efficiency was 74.4%, while in another reactor with the common quarts filtering medium inside, the manganese removal efficiency was 32.1% and iron emoval efficiency was 64.2%, and the reactor with manganese sand filtering medium inside, manganese removal efficiency was 65.1% and iron removal efficiency was 74.7%. The efficiency of bio-reactor was better than reactor with common quarts filtering medium and equivalent to the reactor with manganese sand filtering medium inside. Immobility of the microorganism would reach better efficiency in the process of iron and manganese removal of groundwater. Later, backwash intension to the filtering medium was tested, the backwash intension would be 16～18 L/s·m2, after backwash, the filtering medium didn't get obvious impulsion, though the biomass reduced.A practical test was done in Daqing, the results indicated the iron removal reached national standards soon and the manganese removal was not that better, the manganese in the effluent was 0.1-0.15 mg/L. The reasons of above results were the bacteria need a long time to adapt new conditions or the nutriment in the water were not enough.The research indicated that the bio-reactor with by immobilizing iron and manganese removal bacteria on the medium would reach the efficiency of reactor with. The results showed the quarts sand filtering medium could take place of manganese sand filtering medium, and that would save the cost.