Research On Water Supply System Daily Quality Maintain Based On Chlorine Decay

Urban water supply network system undertakes the vital task that transportingdrinking water from water treatment plant to customer. Due to years of operation,anomalous annularity mixture will grow up along pipe wall, which is defined ‘growthring’ by the researcher. It is the mixture of precipitate, erosion, biofilm and dirty thathaving major impact on water quality. While drinking water flows in the networksystem, it is not the pipeline wall where directly contact with drinking water, but thegrowth ring. Various kinds of reactions will occur when drinking water contact withgrowth ring, and the reactions have directly influence on water quality. Therefore,studying water quality variation in the supply system, establishing reasonable analysissystem of water quality, then adopt necessary measures to improve water quality, whichhas significant investigation meaning.This study focus on water quality analysis and estimation using the parametersresidual chlorine and node water age. We analyse the characteristic of node water age,and come up with the concept of residual chlorine water age that combine residualchlorine with wate age. Then we can use it to evaluate water quality.Sanitary conditions of old pipe are usually undesirability. Rate of residual chlorinedecay is going to be speed up because residual chlorine will react with dirty, erosion,biofilm and precipitate on the pipe wall. We try to come up with the concept of residualchlorine decay equivalent coefficient, it bases on the rate of residual chlorine decay onboth old pipe and new pipe. Meantime, we establish the computing principle of residualchlorine decay equivalent coefficient. Then we take a case network for example toexplain the computing method and its revised method. As the concept said, decayequivalent coefficient must be a value that greater than1. Moreover, value of decayequivalent coefficient the larger, the worse quality condition it is. Finally, we establish apipe quality condition evaluate system based on residual chlorine decay equivalentcoefficient. The system ranges the pipe quality condition from grade1to4.We introduce several measures of water quality maintain that can be adopted inwater supply network in service, scuh as pipe cleaning technique, changing for new pipe,terminal water discharging, pipe internal coating, optimal operation control and so on. Then we discuss the advantage, disadvantage and application condition of each method.Finally, we take a town water supply network in northeast China as a study case.Residual chlorine decay equivalent coefficient of all pipes is calculated on thefoundation of accuracy hydraulic and quality simulation. Moreover, pipes and nodeswhich quality condition below standard are found out by node water age and residualchlorine decay equivalent coefficient. We develop appropriate measures to maintainwater quality after precise quality analysis.