Study On Biological Aerated Filter For Treatment Of City Drinking Water

West River water diversion project is under construction in Guangzhou. Water plant upgrade transformation is still needed for ammonia nitrogen and organic micro-pollution to ensure that the quality of water supply achieves"drinking water health standards"(GB 5749-2006) and"Drinking Water Quality Standards"(CJ 94-2005) after the project. In addition, the water of West Pearl River channel which will be enabled when there are some problems of West River also need the biological pretreatment in order to ensure water quality compliance gradually. In this paper, the effect of biological aerated filter (UBAF) + bioaugmentation conventional treatment process and measures for emergency pollution in flood season were studed.The experimental results show that:1. As to the West River raw water, the bioaugmentation conventional treatment process following the biological aerated filter (UBAF) pretreatment can achieve water quality targets. For the flood season, the conventional treatment process effluent ammonia nitrogen,CODMn was not able to achieve water quality goals. The ammonia nitrogen value of conventional water treatment process was 0.564~0.619mg/L when raw water is 0.891~0.984mg/L; the conventional treatment process effluent CODMn was 1.85~2.38mg/L when raw water was 4.48~6.24mg/L.2. The removal efficiency of CODMn of UBAF + bioaugmentation conventional treatment process is 23% than the single"conventional treatment", and it can further improve drinking water taste and reduce disinfection by-products, helping improve the guaranteed rate to"Drinking Water Quality Standards"(CJ94-2005) . In the case of CODMn of UBAF + bioaugmentation conventional treatment process is 1.69~1.77mg/L when the raw water is 3.18~3.26mg/L, there was risk that CODMn was not able to achieve water quality goals if conventional treatment process was only used at this time.3. UBAF + bioaugmentation conventional treatment process is suitable for low ammonia nitrogen source water, and is effective for the 1.0~2.0mg/L ammonia nitrogen pollution in a short time (24h). UBAF effluent ammonia was 0.2~0.47mg/L and UBAF + bioaugmentation conventional treatment process was 0.01~0.14mg/L when the raw water was 1.05~2.26mg/L.The tests of adding ammonium indicate that UBAF effluent ammonia was 0.22~0.93mg/L and UBAF + bioaugmentation conventional treatment process was 0.06~0.46mg/L when the raw water was 3.01~3.98mg/L.When the raw water ammonia were 1.0mg/L and 2.0mg/L or so, UBAF + bioaugmentation conventional treatment process 3h and 10h, respectively, the value of the effluent ammonia nitrogen was under 0.5mg/L, and the UBAF effluent ammonia nitrogen was under 0.5mg/L after 5h and 12h when the removal rate could reach 50%.4. According to the different raw water quality characteristics of the West River in flood season and dry season, the results of removal efficiency of gas water ratio and sludge return showed that: when UBAF gas-water ratio was 0.3~0.5:1 and its follow-up settling tank sludge recycle ratio was 10% in the flood season, ammonia nitrogen, nitrite nitrogen and turbidity removal were better and the removal rate of CODMn had increased more than 23%; when the concentration of ammonia and other pollutants were lower case in the dry season, the removal rate of CODMn had increased 4.9% as UBAF was no aeration.5.The filter head loss of UBAF was 10.4 ~ 24.5cm. The backwash mode is combined with air and water ,which is that the first air impact is 3 min,gas flushing intensity 20L/(m2·s),then the joint gas and water washed is 5 min, gas flushing intensity 15L/(m2·s), wash intensity 8L/(m2.s). The head loss of UBAF get better recovery after backwashing.The backwash cycle of UBAF can be 1 to 2 days in the flood period and 6 to 7 days in the dry season.