Optimization Of Booster Chlorination System And Risk Analysis Of Water Quality In Water Distribution Network

Based on the existing researches of booster chlorination model, in this paper a multi-objective one-stage optimization model has been proposed, which enable locations of chlorine boosters to be optimized along with their dosages. This model targeted at narrowing the gap of chlorine concentrations among different regions of network and increasing the quantity of qualified water, the constraint is the percentage of qualified water, under which feasible solution is easier to get than the constraint of chlorine concentrations. Algorithm of NSGA-2 can be used to solve this model. The model was applied to a real network from southern China, calculations showed that using five chlorine boosters was best for the network and it could make up to 99.9% water qualified. Compared with source chlorination with 98.1% qualified water, booster chlorination could bring the network following advantages:provide more qualified water, reduce the dosage at source by 67%, improve the uniformity of chlorine concentration by 70.2%, cut down the total chlorine dosage by 33.4%, as well as reduce the average concentration of THMs and total THMs formation by 48.8% and 50.8% respectively. The above results prove that booster chlorination could optimize chlorine distribution in network and reduce total dosage of chlorine, moreover, it could improve security of drinking water.Outbreak of contamination may bring huge threats to the security of water. In this paper, variable chlorine decay coefficient was used to increase the accuracy of current pathogen intrusion simulation, and the results could be used to build risk assessment model, including water security and monitoring capacity analysis of network. Compared with source chlorination, 5 chlorine boosters could make the amount of contaminated water caused by 43.7% accidents reduced, water quality could recover greatly by raising chlorine dosage at boosters before contamination source was removed, besides, monitoring capacity of 55.8% nodes improved, and the network could discover 12.7% more accidents though monitoring capacity of some nodes decreased.These results indicate that booster chlorination can not only improve self-protection and monitoring capacity of water, but also make effective use of emergency measures.