Study on simultaneous biological removal of iron

manganese and ammonia in a simulated groundwater involving iron and manganese and pollutant ammonia-nitrogen was carried out in biological aerated filter with dual layer ceramic material.The influence of the flow rate on the removal of iron

manganese and ammonia and the change of their concentrations along the depth of the filter were measured.The results show that if flow rates increase suddenly only after 2—3 d culture for the filter

the concentrations of iron

manganese and ammonia at exit of the filter can be lower than that of the National Drinking Water Standard.It is found that when flow rates of the simulated contaminated groundwater increase from 0.74 m·h-1 to 3.0 m·h-1，the filter depth to meet the National Drinking Water Standard is only 0.75 m for concentrations of iron and ammonia in water

but it increases from 0.75 m to 1.60 m for the concentration of manganese.