Experimental Research On Secondary Effluent Treatment By BAF-UF Combined Process

Biological aerated filter(BAF) is a new technology of sewage treatment developed from the general biofilter on the basis of the filter water supply at the 80's at the end of the 20th century. Until now it has been widely popular in Europe, America, Japan and other developed countries, A large number of sewage treatment plants have used this technology in the world. Ultra-filtration is in general as the depth of biological and chemical processing technology after the secondary sewage treatment, which is mainly used to remove the part of fine particles that biochemical treatment process can not get rid of, By use of ultra-filtration technology the defects can be avoid on flocculation, sedimentation , tedious filtration units, big fluctuant removal effect and high cost running of the traditional advanced treatment technology.In this work BAF and ultrafiltration technology are combined organicly to play fully the synergistic effect .The combined process can not only effectively remove COD_cr, NH₃-N, SS, but also colority and turbidity removal rate are also high from secondary effluent, ultimately a stable, high-quality reuse water can be received.Study on using BAF process to treat secondary effluent from wastewater treatment plant is carried out. The results show the hydraulic loading changing impact is greater than the impact of organic loading changing on removing pollutants in BAF,There are the optimal filter height for different pollutants in BAF.A combined process of upflow biological aerated filter and ultrafiltration (BAF-UF) is used to treat secondary effluent of Xi'an Dengjiacun wastewater treatment plant for reuse in this paper. The removal rates of COD_cr, NH₃-N concentration, color and turbidity from secondary effluent are analyzed by using BAF-UF combined process The results show the total average removal rates of COD_cr, NH₃-N concentration, color and turbidity by combined process reaches 60%, 92%, 50% and 99%, respectively. The results indicated that BAF-UF combined process can remove pollutants from the secondary effluent effectively. As pretreatment of UF membrane process, BAF process can reduce the membrane fouling significantly.The effluent water quality indicators from BAF-UF combined process are compared with the urban sewage water recycling water quality standards .The results indicated the effluent water quality from combined process can compeletly meet the urban sewage water recycling urban miscellaneous, landscape and industrial use water recycling quality standards, And the effluents can be used as renewable water sources of urban greening cities, vehicle washing, entertainment, environmental landscape.