Study On The System Of Post-project Assessment Using In The Xi’an No.4Wastewater Treatment Plant

In recent years, the government increased the investment for water pollutioncontrol, accelerated the construction of urban wastewater treatment plants. As a publicworks, the post-project assessment of wastewater treatment plants is necessary.Post-project assessment can reveal problems in the project construc tion process, analyzethe reason and lessons learned to improve future decision-making level and design levelof the project, management level and efficiency of investment, and enhance the sense ofresponsibility. On the basis of the main content and indicators of domestic andinternational post-project assessment, study the post-project assessment theory andmethod. Based on Xi’an No.4Wastewater Treatment Plant project data collection andthe actual process operating results analysis summarize the various stages of work. Tomake a specific assessment content, the establishment of a wastewater treatment plantproject assessment index system for the future government investment of similarprojects to provide a reference. The study results show that:（1） Throughthe analysis of the No.4Wastewater Treatment Plant project process, putforward the content and assessment index of the wastewater treatment plantpost-project assessment, using the analytic hierarchy process to determine theweight of each evaluation index, establishing post-project assessment system ofwastewater treatment plant.（2） The No.4Wastewater Treatment Plant of Xi’anCity in accordance with nationaland local requirements, makes scientific and high efficiency decisions,construction cost control in the investment budget. Design process to determinethe reasonable scale. The water quality indicators in addition to COD, SS and TP concentration is1.3times than the original design value, the rest of theindicators are in accordance with the design value;（3） The inverted A2/O process are stable, the major pollutants COD, BOD5,NH3-N,TN, TP, SS the average removal rate were90.6%、94.3%、96.6%、74%、53.5%、92.4%, except TP, all the water quality indicators of effluent meetDischarge Standard of Pollutants for Municipal Wastewater Treatment Plant;（4） Organic matter content of the sludge produced in the process is326.73g/kg, totalnitrogen content is40.87g/kg, total phosphorus content is10.69g/kg. Thecontent of sludge heavy metal elements such as Cu, Zn, Pb, N i, Hg, As is lessthan landscaping the muddy (GB/23486-2009) limits. The plant sludge throughhigh temperature compost applied to urban landscaping and shelter forestconstruction;（5） Device configuration is reasonable, energy consumption below average.Operating costs is0.377yuan per ton(excluding depreciation), lower than thepreliminary design of the project0.46yuan per ton;（6） After the running of the wastewater treatment plant does not adversely affect theenvironment, open channel water pollutants concentration decreasedabout7.62~55.05%. Taken effective noise reduction and deodorant measures, noadverse impact on the surrounding environment;（7） This project overall evaluation score is2.456points, the post-project assessmentresults shows that this project was successful.