Engineering demonstration of micro-polluted water pretreatment with high-rate up-flow biological aerated filter

Problems of seasonal ammonia nitrogen (NH₃-N) and organic micro-pollution in drinking-water source have recently become common in cities of China, thus biological pretreatment process is helpful. The water flow of high-rate up-flow biological aerated filter (HUBAF) demonstration project was 735 thousand ton per day, there were 20 filters, sharing a common aeration system and an air-water combined up and down flow backwashing system, and each one with 11 meters long, 9 meters wide and 7.3 meters high. During Jar. to Mar. 2011, NH₃-N was 0.443-2.222 mg/L in raw water, and was 0.01-0.43 mg/L in effluent of pretreatment which was all below 0.5 mg/L. COD_Mn was 1.84-6.06 mg/L in raw water, all below 2.00 mg/L. The highest Fe and Mn concentration in raw water was 1.16 and 0.22 mg/L, while that in waterworks effluent was 0.05 and 0.03 mg/L. Using large particle ceramic filter media, the average removal amount of turbidity was only about 2.5 NTU and the head loss was 39.4-48.1 cm after steady. The project investment was 113.4 Yuan per ton of water, and the operation cost was about 0.04 Yuan per ton of water. Project demonstration shows HUBAF has stronger resistance of impact loading, higher NH₃-N nitration rate and better removal of Fe and Mn than the other biological pretreatment technologies which have entered into production such as elastic packing-contact oxidation technology and suspended ball fluidized technology. HUBAF is a biological enhancement to conventional treatment system, forming a new process, which is in the same level with "O3-BAF" advanced process in water purification.