Theory And Optimal Calculation Of The Disinfection Pattern By Chlorine In The Water Supply System

The traditional disinfection destination is to keep the residual chlorine concentration in the water out of plant const during a period of time. The residual chlorine concentration of the water quality monitors in the water distribution networks will exceed the normal level for the traditional control mode. It will bring risk to the water quality safety. The software package was developed as an optimal control tool to disinfection control scheme by numerical simulation technology based on the TJ water distribution networks during the project"863".Chlorine is a widely used disinfectant in the water plant for it can restrict the bacteria activity and supply the safeguard for the water quality. But it will increase the risk to higer THMs concentration if the dose of chlorine is paranormal. At the same time it will make the users'nose discomfortable and make the cost of disinfection become high. So it is an important task to define the sound disinfection solution to ensure the wate quality safety in the distribution networks. The traditional control theory has greate difficulty to deal with the optimal disinfection problem for the work condition of the multi-source water distribution networks is complex and a time-delay and time-vary system.This paper suggests a method to optimal control the disinfection process from three stages based on the water distribution networks simulation. The first stage is to select the optimal water quality monitors in the networks. Three objective functions were brought forward to satisfy the water quality monitors standard. A dynamic node percent algorithm was brought forward to create the node information database.Data mining method was used to analysis the database to get the optimal location for the water quality monitors. The second stage is to bring forward the objective function to minimize the residual chlorine concentration fluctuation. A method of genetic algorithm combined with the EPANET toolkit was applicated to optimal the residual chlorine concentration of the water leaving the plant. At last booster disinfection method to bring forward to overcome the shortcoming of the once-disinfection in the huge city networks. Two objective fuction of economical and water quality performance was set. The multiobjective gentic algorithm combined with the EPANET toolkit was applied to optimal rehabilitate the booster station in the networks. The economical and accessible solution was brought forward to the distribution networks of the TJ city.The results show that the dynamic node percent information algorithm can resolve the difficulty of the time delay between the nodes in the networks. The difficulity can't be resolved by the methods based on the static hydraulic model. Genetic algorithm can define the sound solution for the multisource disinfection process. The fluctuation of the residual chlorine in the water quality monitors became little by optimizing the schedule the disinfection pattern of the plant. The method helps to decrease the total disinfectant amount. Optimal rehabilitation booster stations can decrease the total amount of the chlorine. The fluctuation degree of the chlorine concentration in the monitors in the networks will become less. The optimal rehalilitation can save the cost of producting the water and improve the water quality in the networks. At the same time it is easy to rehabilitate the networks by arranging the fund in step. The methodology in this paper is useful for the optimal water quality monitors layout, optimal disinfeciton schedule scheme and optimal rehabilitation disinfection system.