Research On Optimum Design Of Activated Sludge Nutrient Removal Process

Activated sludge mathematical model has been widely utilized as a powerful tool in the management and rebuilt of wastewater treatment plants and simulation and optimization for design programmes of newly built wastewater treatment plant overseas. However, in China the actual design process is often based on experience data, and there always are problems that design parameter data are limited or actual data of wastewater treatment plants are not available, as a result the design process are carried out under a certain blindness and are difficult to optimize. The purpose of this paper was utilizing activated sludge mathematical model to optimize design of nitrogen and phosphorus removal in urban sewage plant. Under the premise of meeting the requirements to standards of the effluent, the design results would reduce the costs of infrastructure and operating, apply theory to guide practice, enhance the efficiency of urban sewage treatment plant.At first, utilizing study platform ASM2D to constitute A2O sewage treatment process simulation mode and calibrate it at the base of parameter sensitivity analysis, then three operation parameters—return ratio of supernatant fluid, DO and SRT—are researched with calibrated model, as a result these parameters may be adjusted in relation to design data.Secondly, this article gave a detailed demonstration of how to constitute a sewage treatment system optimum design model made of target function,mainbody and restriction conditions ,and three design method—the tradtional activied sludge process design method, the test method and the optimization algorithms methods—were evaluated by use of targe function of optimum model, The results showed that, A, B sewage treatment plant designed with optimization method save 19.7194 million yuan for traditional design methods respectively, and 2095.72, cost savings rate of 11.83% and 22.83%, optimization of the design method for the test algorithm to save 9111100 yuan and 1292.96 million, cost savings rate of 5.84% and 15.43%.Finally, analysing the sensitivity of the parameters in optimum model and acquiring its influence to results of optimum design as a result that the the sensitivity of different types of parameters varies greatly: the parameters of the objective function have the greatest impact on design results, the greatest sensitivity to -99.02 per cent, followed by influent components, to achieve maximum sensitivity of 16.06%, different design standards for the total cost of the system have an important impact, with the decline in emission standards, the total cost also will be reduced by the amount of 9.1746 million yuan, respectively, and 6.2591 million yuan.