The Research Of Two-stage BAF In Water Treatment In The Residential Areas

Since 1990s,the wastewater emissions of China's urban began to increase multiply, in order to alleviate the shortage of water resources,searching for an appropriate technology of sewage treatment is an urgent task. Biological Aerated Filter(BAF)is a newly developed process which is used for the wastewater treatment in recent years, and it integrated solids separation as well as secondary or tertiary biological treatment in one unit .BAF has advantages of less land occupied,high treatment efficiency,on requirement for secondary settling tanks highter capacity for absorbing shockload and cost savings.According to the BAF's characteristic of lower pollutants concentration,great biodegradability and easy to handle,it fully meet the requirements of community wastewater treatment.In order to investigate the two-stage BAF (up-flow&down-flow)process,a series of experiments had been carried out on the reactor.In this tentative, experimental water come from the cafeteria and student apartments of Wuhan University of Technology.The aim of the work was to verify experimentally the suitability of the two-stage BAF and ascertain the relationgship between removal efficiency and performance of reactor.In order to quicken the culturing process of bioflim, the biofilter wae inoculated with activated sludge form A-O pool of Wastewater Treatment Plant of Wuhan University of Technolog.The objective of the experiment is to study the influence of ration of gas to liguid,influent hydraulic loading volumetric loading and temperature.The correlativity between performance and filter medium height hao been studied too.The results show:the performence of the two-stage biological aerated filter for sewage treatment is excellent.Under the hydraulic rate of 3.0m3 / (m2 ? h), the average inlet concentration of COD,NH3-N is 312.49mg/L,25.47 mg/L,the average removal percent for COD,NH3-N is 86.43%,82.4% respectively,the average effluent concentration of COD,NH3-N is 42.41mg/L,5.31 mg/L. Under the hydraulic rate of 3.0m3 / (m2 ? h), the removal efficiency of COD,NH3-N have positive correlation with the height of filter medium, up to 60～70% of COD was degraded in the up-flow BAF.The relationship between the performence of recator and backwashing was also determined. Under this experiment, the appropriate impulse backwash parameter was air and water backwash.Test results showed that the two-stage biological aerated filter had the good effect of organic and nitrogen removal and it was suitable for the domestic sewage treatment and wastewater advanced treatment.