Study On Biological Aerated Filter For Phosphorus And Nitrogen Removal

Biological Aerated Filter(BAF) treats domestic sewage, with high capacity and load, less land occupying, automatic control. Yundang wastewater treatment plant of Xiamen City uses two-segment BIOFOR Biological Aerated Filter to treat domestic sewage of mainland of Xiamen and a spot of industrial wastewater. it can implement the requirements of the removal of nitrogen and phosphorus ,and the tail water meets a B standard of the water quality of cities and towns sewage treatment plant pollutant discharge standards(GB18918-2002).In this paper, the removal of various pollutants are analyzed by Biological Aerated, and the emphasis is on the nitrogen and phosphorus removal performance of Biological Aerated Filter. All index of water quality, including CODCr, BOD5, ammonia, nitrogen, phosphorus, SS, and so on, are able to achieve 65.21 %, 88.74 %, 86.33 %, 34.8 %, 41.02 % and 79.30 %from the operation. Especially, CODCr, BOD5, ammonia and SS even are better than an A standard.The pre-denitrification technology is applied in BIOFOR Biological Aerated Filter to realize nitrogen transfer into air. In a condition of recycle ratio of 1:1, 22.8℃,and sufficient providing of alkalinity, the carbon in denitrification is the key. When the BOD5/TKN is below 1.44, is up to20, but the total average nitrogen can decrease below 15.32 mg/L when adding methanol increases the ratio of BOD5/TKN. The influence factor of the removal of nitrogen, such as substrate concentration , organic loading and operation of the filter performance, are also done an analysis in the paper.According to the Biological Aerated Filter tectonic features, we choose ferric chloride to precipitate the phosphate in sewage with discharging sludge phosphorus. A comparative analysis of the effectiveness of drug phosphorus removal, the pre-effective is on the effect of the preprositive and post ,the result is that preprositive removal phosphorus is better than the post , corresponding to the removal rate of increasing16.97% to 43.82 %.There are two back-washing methods about Biofilter ,one is the ordinary washing and the other is forceful back-washing .back-washing cycle is increasing with the filting time, the pool cycle for the DN is 13h, CN is 47h in general, DN pool during 10.67h of filting after back-washing can reach a higher quality, the removal of CODCr and SS concentration relative increase 1.11 mg/L and 1.48 mg/L; washing flow and gas flow are 2600 m3/h and100 m3/h in DN.Finally, this article is derived Biological Aerated Filter degradation of organic pollutants dynamic model, the DN is ce = co e ?204.075θ,and the CN is ce = co e ?87.609θ.