| In accordance with the instructions of the urban sewage treatment work in the "12th Five-Year "Plan, China will continue to accelerate the construction of sewage treatment plants, focus on promoting the building of the towns sewage treatment facilities. Meanwhile the existing wastewater treatment plant using the old process would mention standard upgrade. According to the requirements of the State Environmental Protection Ministry, the effluent quality by sewage treatment plant, which was along the Fen River Basin in Shanxi Province,should be the implementation of urban sewage treatment plant emission standards (GB18918-2002) in an A standard. Therefore, the study, development, promotion, suitable for small-scale water and effluent treatment process to achieve high standards would be particularly important for the development and construction of urban sewage treatment plant in Shanxi Province.The horizontal plug-flow of A2/O biofilm composite process is of A2/O process and biofilm process configuration is a plug-flow anaerobic-anoxic(plus filler)-aerobic (plus filler), ie A/O process on the basis of the anoxic and aerobic tanks laid a fixed packing, the study took sewage treatment plant of a county in Shanxi Province as the research object, Purposing to inspect the the A2/O-biofilm composite process operating performance.The first phase of the design size for the sewage treatment plant was5000m3/d, the main design parameters as fellows:bioreactor volume of2600m3,The volume ratio of the anaerobic, anoxic and oxic pool were1:2.5:3.5, the hydraulic retention time were10.4h,the MLSS were3500mg/L, biological solids retention time was7.2d. The load of the filler contact for BOD were0.7kgBOD5/(m3·d), the load of the filler contact for NH3-N were0.45kgNH3-N/(m3·d), filler volume in anoxic, oxic pool were517m3,741m3.Sludge reflux ratio were50~80%,and mixture liquid reflux ratio was100~400%.During the entire time of experiment,the influent water of sewage t reatment plant were600m3/d-1860m3d,and the average of the influ ent water was1040m3/d.The influent quality as follows:CODcr=154mg/L-768mg/L,BOD5=68mg/L-323mg/L,SS=76mg/L-643mg/L,NH3-N=18.23mg/L-69.17mg/L,TN=40.22mg/L-75.20mg/L,TP=2.60mg/L-7.80mg/L,pH=7.0-7.6.Operating parameters of the experimental period as follows:MLSS=2.0g/L-6.0g/L,and sludge reflux ratio was about100%,mixture liquid reflux ratio was240%-330%.The DO in oxic pool was1.5mg/L-7.0mg/L.The effluent quality as follows:CODcr=35.86mg/L,BOD5=9.41mg/L,SS=10.75mg/L,NH3-N=6.61mg/L,TN=12.23mg/L,TP=1.43mg/L.The average removal of various pollutants as follows:CODcr=90.13%,BOD5=93.23%,SS=92.96%,NH3-N=85.61%,TN=77.56%,TP=69.09%.By monitoring the influent and effluent concentration of the CODCr, BOD5,SS,NH3-N,TN,TP conventional indicators on the sewage treatment plant, and Combining with the actual influent quality, flow and removal effect,we analyzed and discussed performance and characteristics on the A2/O-biofilm composite process.Through this paper mainly studied the removal efficiency of the A2/O-biofilm composite process on the CODCr, BOD5,SS,NH3-N,TN,TP conventional indicators,and influencing factors. Then analyzed the flow and distribution characteristics of the composite process, this work Summarized the performance and features of the A2/O-biofilm composite process. The conclusions as following:(1) During normal operation,the average removal ratio of COD was89.5%,the average removal ratio of BOD was92.8%,the average removal ratio of TN was80%,the average removal ratio of NH3-N was90%,the average removal ratio of TP was69%.(2) The organic matter and nitrogen removal ratio was high, when the MLSS maintain the most appropriate in the3.0-4.0g/L; the gas-water ratio of12:1.(3) Four-month average into the water1161.35m3/d in this wastewater treatment plan, then total energy consumption in fact was8.89kw·h/m3. However, total energy consumption in design was2.74kw·h/m3. The actual working conditions in the water flow is too small, resulting in the entire process in a high-energy state. |
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