Biological Removal of Iron, Manganese and Ammonia Nitrogen from Low-Temperature Groundwater Using Biological Aerated Filter

Biological aerated filter (BAF) was used to treat low -temperature groundwater containing iron and high concentrations of manganese and ammonia nitrogen. The influence factors on biological oxidation such as operating parameters and time, concentrations of raw water and backwashing were investigated. The research results showed that the biological oxidation of iron and manganese has achieved steady state, while nitrification process is affected by hydraulic loading, and that iron, manganese and ammonia nitrogen could be removed simultaneously under the hydraulic loading of 3 m³/(m²·h) and with the air-water ratio being 3, when the iron inlet concentration is low. Significant removals of ammonia nitrogen was observed in the range of 85-90% after the long-term operation. The biological oxidation of both ammonia nitrogen and manganese would be restricted by higher inlet concentrations of ammonia or iron. The removals of iron, manganese and ammonia nitrogen are restored the effect of the stable operation at 150min after backwashing.