Experimental Study Of BAF Reactor With Large Size Hollow Carriers For Scenic Water Treatment

Recently, biological aerated filter (BAF) is one of popular wastewater treatment techniques. Due to the low land require, high treatment efficiency and easy operation and management, BAF is suited to the small scale or advanced wastewater treatment.Considering the several characteristics of scenic water, such as low environmental capacity, difficult auto-recovery, low flow ability, serious entrophication problem and close loop from outside, a biological aerated filter (BAF) with large size hollow carriers is developed for advanced wastewater treatment. Compare with the conventional biological aerated filter, the filter is filled by the large particle size suspended polypropylene carrier, and is divided the aerated part and the non- aerated part by the bubblers. Through adjusting the ratio between the aerated part and non-aerated part, the optimal operating conditions were obtained; meanwhile, the treatment efficiency of filter and the mechanism of nitrogen removal were studied.During the experimental start-up period, the scenic water was served as influent, and the biofilm was incubated by the cultivatable pattern of adding sludge - aeration - consecutive flow. The experimental result has indicated that the effluent COD, ammonia nitrogen, turbidity and total nitrogen were 21mg/L, 0.43mg/L, 1.3NTU, and 4.0 mg/L, respectively, when the biological aerated filter (BAF) with large size hollow carriers ran at temperature of 21~27℃, hydraulic resident time of 2.5h, return radio of 1:1, air-liquid ratio of 2:1, the non-aerated and aerated part radio of 1:2. While shifting the non-aerated and aerated part radio from 2:1 to 1:1, even 2:1, there was a slight increase for effluent COD, ammonia nitrogen, and turbidity concentrations, which suggested the filter holds the high removal efficiency for above three factors. The fact total nitrogen removal efficiency went up from 34.8% to 40.43% and 43.18% indicated that the total nitrogen removal efficiency should be increased by elevates bubbler location, and enlarged the non-aerated radio.In addition, the filter was influenced by six main factors: location of return sludge, air-liquid ratio, return radio, temperature, the hydraulic load and organic...