Experimental Research of Low-temperature, High Concentration Iron and Manganese in Groundwater by Bio-filter Purification

A pilot-scale biological filter was constructed to purify high concentration of iron and manganese simultaneously from low-temperature (5-6℃) groundwater in a water supply plant. Results show that the corresponding functional oxidizing bacteria can be acclimated sufficiently in low-temperature and the biological filter can realize quick start-up by means of adjusting process parameters(the backwash strength)appropriately and inoculating matured materials, the backwash supernatant returned to the filter, the start-up time is two months only, while the filtration rate is 6 m/h.The ideal operating parameters for stable operation of the filter column are:the filtration rates (4-7 m/h), the backwashing period (24, 36, and 48 h), the backwashing intensity (8, 10, and 12 L/(s·m²)), and the backwashing time is 4-5 minutes. Further analysis, the variation of iron, manganese removal along the filter show that the iron is removed mainly in the depth of 0-400 mm and the manganese is removed mainly in the depth of 0-900 mm, The manganese removal zone moves down first and then moves up. Under this contition, the thickness of the filter layer is optimized, and the optimum filter layer thickness is 1 200-1 300 mm when the filtration rates is 5-6 m/h.