Comparisons Of A~2/O And MBR Technologies For Municipal Sewage Treatment

When A²/O and MBR technologies are combined with hydrolytic acidification bio-treatment, high removal rate of carbon, nitrogen and phosphorus will be achieved , especially for medium pollution of municipal sewage.The second-period project of combined treatment for sewage was discussed over two years. In the workable research report, two selected technologies are just based on improvement of A²/O and MBR technologies. Both of their pre-treatment are added with anaerobic hydrolytic process.But for the sewage treatment facilities with such a big investment, lacking of experimental data will makes unacceptable risk. In order to make effluent quality steady and meet the water standard, determination and validation of rationality and reliability are needed for the technical routing and parameters. In a word, to do the pilot test for validation is quite necessary.The parameters of each optimized technology are studied and the treatment result of A²/O and MBR are compared. This thesis designed and made each pilot test equipment, and then testified them through experiment.Pilot test includes four stages which are apparatus pre-operation test, sludge cultivation, determination of better work conditions and test under better conditions. At each stage, the amount of inflow water and COD_Cr are designed. And various effluent water indexes of COD_Cr, BOD₅, SS, PO₄^3--P, NH₄⁺-N, etc for two technologies are determined. Further more, Whether the selected parameters were appropriate were tested, such as internal reflux ratio、sludge recirculation ratio, sludge age、hydraulic retention time. And whether effluent water quality meets the expected water standard was also tested.The results of pilot test show that under good working conditions, the effluent water quality can meet the expected water standard. MBR is better than A²/O for both the quality and stability of effluent water. By estimating and comparing the cost of each technology, this thesis concluded that the total cost of MBR is higher than A²/O. Although the fixed assets investment of MBR is lower but its operating expense is much higher than MBR. So A²/O is more economical for this project. A²/O has required denitrification and dephosphorization function, is more reliable, economic, convenient, and can meet the requirement of energy saving and cost reduction.