Technical evaluation and optimization of biological aerated filter (BAF) treating micro-polluted source water at low temperature

In this study, polyethylene and zeolite, as media in two-stage biological aerated filters (BAF), were evaluated for simultaneous removal of ammonia nitrogen and organics in micro-polluted water under low temperature conditions. For specific source water, the contaminants removal characteristics are evaluated by single-factor experiment to determine the suitable pH, air-water ratio (AWR) and hydraulic load ratio (HLR). Ammonia nitrogen and permanganate index in BAFs were promoted effectively with pH = 7~8, AWR = 1.0:1.0~2.0:1.0, HLR = 1~4 m³/(m^2·h), low pollution loads and a temperature of 10°C. Based on the response surface analysis, the optimum parameters were as follows: pH of 7.94, AWR of 1.41:1.0 and HLR of 1.39 m³/(m^2·h), for simultaneous removal of ammonia nitrogen and permanganate index, their removal rates were respectively 59.76% and 18.16%. BAF has a great advantage in emergency treatment of low temperature micro-polluted water, and response surface analysis can be used to optimize operating parameters.