Study On Water Quality Model Of Water Distribution Network Of Non-Traditional Water Source

At present, the researches concerned with drinking water’ chemical stability andbiological stability have been carried extensively worldwide, but the attention paid onthe water quality stability of anti-traditional water source is far from enough. Thispaper studies reclaimed water’s biological stability and desalinated water’s chemicalstability according to the water quality characteristic of reclaimed water anddesalinated water.Firstly, this paper analyses the differences of residual chorine decay betweenreclaimed water and drinking water through the experiments. The residual chlorinedecay of reclaimed water is divided into two phases: high velocity phage at chlorinefeeding stage and low velocity phage after that, both of which are fist-order reactionmodel. Then, taking a reclaimed water distribution network for example, a residualchlorine decay model is set up, which is first-order reaction kinetics equation. Themodel is verified by monitoring data and the result shows that simulation value hasgood agreement with monitoring data. On the basis of the residual chlorine decaymodel, optimal disinfection is studied and optimizing model of chlorine allocation isestablished which draws a conclusion that the optimal disinfection in distributionnetwork has a remarkable advantage on both water quality and economy comparedwith chlorine dosing only in water supply plant.Secondly, the desalinated water’s chemical stability after entering different oldmunicipal pipe network is investigated by two pilot systems of two different pipematerials in laboratory. The best mixing ratio of desalinated water and drinking wateris found when desalinated water is used as supplement source of drinking water. Staticexperiments are done to research the effect of water quality factors on iron release.The factors include pH value, alkalinity, chlorine ion and sulphate ion concentrationetc. Therefore, iron release velocity statistic model is built using total regression,stepwise regression and major constituent analysis methods. Stepwise regressionmodel is chosen to forecast the iron release velocity because of its better modelprecision and mechanism significance compared with the other two models.Consequently, stepwise regression model is applied to judge water’s chemical stability and the iron release velocity index VI is put forward.Finally, the residual chlorine decay model and iron release velocity model isrespectively evaluated and applied in actual reclaimed water distribution network anddesalinated water mixed with drinking water distribution network with EPANET. Theresults show that simulation values have good agreement with monitoring data.Therefore the two models can be used in actual network systems.