Sedimentation Process Mathematical Model And Simulation Applications

At present, along with?the acceleration of urbanization,industrialization in china, the amount of domestic sewage and industrial wastewater rapidly increased ,which makes the water resource relatively insufficient. The Lack of clean water not only become a bottleneck to the development of China's economy,but also has effected on people's daily use of water. Therefore, it is particularly important to improve the sewage treatment rate. While the secondary clarifier is an important part of the sewage treatment process ,the enhance of it's efficiency is helpful to improve the water quality and treatment efficiency. However, the secondary clarifier operation rules of the time-varying, nonlinear and complex nature makes it impossible to fully understand the law of the system operation. This paper studied the mathematical model of the secondary clarifier and used simulation models to understand the sedimentation tank internal variation of concentration with time in order to better guide the practical design and operation of clarifier.First, we have a brief review of secondary clarifier model's historical development. From the conceptual model,empirical model to the widely used one-dimensional layer-type model at present. One-dimensional layer-type model is discussed from mathematical point. according to comparsion to the traditional one-dimensional model, simulation model is established based on its original model. The new model does not need to set a critical concentration to control effects between the layers and the simulation result is more constant. Its greatest advantage is that there is no so many specific assumptions, which remains a lot of space for the model's improvement in the future.Visual Studio 2008 is used as a simulation platform to develop the simulation software based on the fixed algorithm . Because the velocity function has a great impact on the simulation results, simulation model is selected through the review and analysis of the velocity model. In this paper, velocity model is selected between single-exponential function proposed by Vesilind and the double-exponential function proposed by Takacs.Comparison to the experimental data and simulated data is done to test the effectiveness of the model. Proper velocity model is chosen to better guide the sedimentation tank operation. At last summarizes the main fruition of the work ,and pointed out that the direction of further development.