Effect of low-temperature for the treatment of municipal wastewater in a full-scale BAF

The impact of temperature on nitrification in biological aerated filter (BAF), process was studied in order to improve the nitrification performance in municipal wastewater treatment. When the water temperature dropped, the nitrification performance obviously deteriorated. Effects of important process variables such as DO concentration and backwash period to nitrification performance were investigated when the water temperature dropped from 23 degrees C to 9 degrees C. The study shown that by raising the DO concentration to enhance nitrification performance was not available in low water temperature environment and by extending the backwash period to enhance nitrification was available. The effluent NH4-N concentration reduced from 8mg/L to 6.5mg/L, when the backwash period extended from 48 hours to 65 hours and the the effluent concentration of SS and head loss were all in a permissible range.