The Application Study On EHYBFAS Technology Used For The Modification Of Bujihe Wastewater Treatment Plant

With the rapid development of economy and demand to the environment quality, more and more existing and to-be-built wastewater treatment plants(WWTPs) are being urged to increase treatment capacity and to improve performance for pollutants removal. To meet these demands, the novel enhanced hybrid submerged biofilm-activated sludge (EHYBFAS) system was put forward on the basis of analyzing the original coagulation-flocculation-sedimentation system in Bujihe WWTP which was operated no effect on water quality of discharge and even could not meet the second criterion of water discharge, the effluent of it can contaminates Bujihe. At the same time, according to the theoretical analyses and pilot studies on the pollutants removal characteristics in the hybrid biofilm-activated sludge system, It was decided that the Bujihe WWTP could be reconstructed from the original system into the EHYBFAS system. It was to be expected that some theoretical and technical support could be provided for upgrading existing overloading WWTPs and improving efficiency of biological nitrogen and phosphorus removal.Based on adding biology padding and tiny hole aeration fine, the original process was reconstructed into the novel process of EHYBFAS, the designed parameters are shown as follows: BOD-SS load of 0.15kg/kg.d,MLSS in EHYBFAS reactor varied from 1500mg/l to 2000mg/l during the operation period, gas water ratio of 6:1 to 10:1,and DO in anoxic EHYBFAS reactor is kept less than 0.5mg/l,while that in aerobic reactor varied from 1.0 in the front part to 5mg/l, pH value of 6.5～8.5. The total HRT of the EHYBFAS reactor is 3.5h, in which the HRT in anoxic basins 3h,The rest (later parter) of the horizontal sedimentation basins is 1.3h.On the condition of description above, after 3 month operation, the average BOD5 removal was 86%, the average COD removal was 83%, the average TP removal was 86%, the average SS removal was 94%, the average NH3-N removal was 79%, the average TN removal was 54%,The effluent concentration of all the pollutants well meet the discharge standard 1B.Because the system can realize the separation of three"RT"s(BfRT, SRT and HRT) from each other ,by means of which sludge retention time(SRT)was separated from hydraulic retention time(HRT),and suspended sludge retention time(SRT)separated from attached biofilm retention time(BfRT) in the EHYBFAS system, As a result, sludge retention time can be reduced properly to improve phosphorus removal without affecting nitrifiers growth in biofilm with much longer retention time that is beneficial to the growth and multiplication of nitrifers, which are helpful to nitrification and de-nitrification of nitrifers. Therefore, both high phosphorus and nitrogen removals can be achieved in the EHYBFAS system.Applying EHYBFAS process to the modification and argument of existing old assembly is one kind of competent and new processes for sewage treatment concerning China condition, both technically and economically. This new process application is helpful for increasing wastewater quality as well as reducing treatment costs, possessing significant meaning for the development of environmental undertaking.