| Comparasion and selection of process scheme is one of most important stages in the construct of wastewater treatment plant, which decides investment cost, running cost, effluent quality, operation supervision and so on. In the fact, because of no forming a complete set of evaluation method, cost of budget estimate and subjective know of designer are crucial factors of election of process scheme in the feasibility study of our country.By inducting Analytic Hierarchy Process (AHP), an optimized evaluation model ofplanning of wastewater treatment plant is established. Comparing with current selection of process scheme which is decided by economic datd, the model can reflect objectly complete influence of system factors and make evaluation result more reasonable, which offer better scientific reference for selection of control scheme of pollution source.The model was applied to comparasion and selection of process scheme of central china pharmaceutial to co.ltd wasterwater treatment plant . The level of adult degree of process ,capital cost and treatment cost was bigger than that of operation supervision and effluent staility, and the level of floor space and removal of N and P was the smallest. The result of optimized selection was as follows : hydrolytic acidification-biological contact oxidation processes were the best scheme, and UASB processes were second.Huazhong Pharmaceutical Co., Ltd. plant is located in Wuhan Hi-tech Development Zone, covering an area of about 39,600 square meters and construction area of 22,000 square meters, of which the production area of 11,800 square meters is factory building. It is built with integrated preparation workshop, pills shop, smash plant, extraction plant, warehouse and etc. After the completion of this project, the wastewater mainly for each workshop process wastewater, equipment wash wastewater, sewage workers and boiler, air drainage, and the maximum production capacity is 300m3/d. According to the relevant provisions of the State, the engineering construction needs to build another sewage treatment plant to process the waste water which is from production and life. It will do no harm to the environment when it meets the standard of emission.When we design and evaluate the alternatives, we determine the wastewater treatment process selection principle and the general layout of wastewater treatment plants. And then we choose four biochemical treatment scheme which is mainly for the process "Coagulation + acidification + CASS", the process "A/O (anoxic / aerobic) biological nitrogen removal", the process "sequencing batch reactor (SBR)", and the process "up flow anaerobic sludge blanket reactor (UASB)". Each program includes technical characteristics, operating cycle, process flow and the main structure. Finally, we focused on solving problems like the environmental protection wastewater treatment plant, safety and fire issues.When we choose the wastewater treatment scheme, we found that AHP is the best way to do this because the use of AHP is a new, simple and functional way to solve the complex social, economic and scientific management problems. And we choose them based on the basic steps of AHP and the main formula. First, it is necessary to establish an evaluation system of index which consists of goal, rule, and program level.The treated pharmaceutical waste water meets the standards of the "Integrated Wastewater Discharge Standard", and the whole process occurred in the lowest cost, which is the overall goal. The evaluation consists 7 items: technology maturity, project investment, operating costs, floor space, operations management, water stability, and phosphorus and nitrogen removal effectiveness. Program level includes: the biochemical treatment scheme which is mainly for the "Coagulation + acidification + CASS", the "A/O (anoxic / aerobic) biological nitrogen removal", the "sequencing batch reactor (SBR)" and the "upflow anaerobic sludge blanket reactor (UASB)".It can be seen from the results of the calculation that the process maturity, engineering, the weight of process maturity, engineering, investment and operating costs is the highest, the weight of the stability and operational management of water second butt the weight of the area and lowest.We draw the following conclusions according to the comparison of the process that "Coagulation + acidification + CASS" Process compared with the other three treatment process is the best process of good maturity, little investment, low operating costs and good stability of effluent. We also discovered that the process which mainly for the "Coagulation + acidification + CASS" biochemical treatment process is the best choice.So far, the curatorial wastewater treatment technology domestic is not mature and has high investment and cost. To find more practical, effective, low cost pharmaceutical wastewater treatment, we need further comparative research. Based on new thought and technology, we should put forward new development and the best technique for the curatorial wastewater treatment.The paper will provide reference to selection and design of processes scheme of wastewater treatment plant.
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