Research On The Reaction And Decay Model Of Chlorine Combined Chlorine Dioxide In Water Distribution Network

Water is the basic element of human life, while water supply network is the bridge connecting the users and the water treatment plant that produce high quality drinking water. However, the drinking water quality often become deteriorated due to the residual microorganisms in water, pipe biofilms, disinfection by-products and other factors in the process of transmission and distribution in water supply networks. Therefore, it is very important for human health and safety to ensure drinking water quality security. In this thesis, the mechanism and kinetics using chlorine and chlorine dioxide togethor in water distribtuin network, the water distribtuion network water quality model under the effect of chlorine combined chlorine dioxide and the optimal desinfection dosage and boostering station allocation in water network is researched theoretically and analyzed in depth. The effect of the synergy of chlorine and chlorine dioxide on the drinking water quality security and the optimal boostering stations allocation in water distribution is also presented. And the effective measures to protect drinking water quality security is also proposed.The disinfection of drinking water play important role on protection drinking water quality security. Although the chlrine, chlorine dioxide, chloramine, and ozone disinfectants have been widely used, all these disinfectants exist some limitations. The mechanism and kinetics of chlorine and chlorine dioxide in water network are researched by jar test, static pipeline test, dynamic pipeline test, and file test. The factors of pH, temperature, total organic carbon, pipe meterial, pipe diameter, pipe service year are analized for the synergy of chlorine and chlorine dioxide. The kinetics and mechanism of the reaction between chlorine and chlorine dioxide are built. The main task of this experiment was to investigate whether the combination of the two disinfectants maintains their advantages and decrease their disadvantages. The optimal dosage ratio between chlorine and chlorine dioxide was selected by beaker and pipeline test with different water qualtiy at different dosage ratio. The results showed that the combination produced a relatively stable high residual of both disinfectants due to the synergy of chlorine and chlorine dioxide, reduced the concentration of the undesirable chlorite ion, while increasing the concentration of chlorine dioxide.The traditional water quality model can simulate only single substance. In order to overcome this limitations, a new water quality model to calculate chlorine and chlorine dioxide at the same time was proposed. The concentration of chlorine, chlorine dioxide, chlorite and chlorate are calculated using the mechanism and kinetics of chlorine and chlorine dioxide disinfectant in the drinking water in the process of transmission to achieve a variety of substance analysis in water distribution networks. The traditional model assumes that the chemical species, such chlorine and chlorine dioxide, will travel down the length of a pipe with the same average velocity as the carrier fluid while at the same time reacting (either growing or decaying) at some given rate. This means only advective transport within a pipe occur, while longitudinal dispersion is usually not considered. The flow rate is prone to be stagnated at the end of a water distribution network with large-scale and complexity topology in China. Therefore, the water quality component diffusion model is introduced to the improved water quality model in this thesis in order to complete traditional water quality model. The overall change in concentration of chlorine and chlorine dioxide is described by combining these three effects in water distribution netwok water quality model, leading to the advection diffusion reaction equation. And this new water quality is solved with Lagrangian method. A large scale water distribution network in Northeast China is selcted as an example, in which the concentrations of chlorine and chlorien dioxide disinfectants and other related substances are calulated.The stochastic programming model to the optimal location of booster disinfection station is propesed in this paper. chlorination of water supply pipe network halfway point of. Firstly, water quality in water distribution network was evaluated by comprehensive evaluation method, by which the booster disinfection stations are located in a large range. Then, the accurate location are calculate by hybrid genetic algorithm is used to optimize the booster disinfection stations. The uncertainty of the hydraulic and the water quality model is also introduced to the optimal location of booster disinfection station In order to realize the interactive water quality control, a real-time simulation model of water distribution network is established. A water distribution network real time simulation model is proposed based on OPC communication of SCADA system, by which the operation infromation of water distribution network is gained in real time , and the state-of–the-art of water distribution network is simualted. The water quality interactive control of water distribution network is achieved by real-time simulation of chlorine and chlorine dioxide concentration through the water distribution network. Water supply network to achieve real-time interactive simulation of water quality control. A large water network is selected as an example, for which the optimal location of the booster disinfection station is researched and a water quality interactive control model of chlorine and chlorine dioxided is built to control disinfectant dosing.