Research Of Urban Reclaimed Water Network For Chlorine Decay Variation And Influential Factors

As far as we known, our country is shortage in water resources. The recycling ofurban reclaimed water can save fresh water resources. Research the changing ofreclaimed water has significant academic value and the upper practical meaning toimproving the reliability of urban reclaimed water. Disinfection is not only the lasttreatment process, but is the most important part. Disinfection can not only killpathogenic microorganism，in a certain extent, still can ensure the network waterquality safety. However, at present there was less research about the change ofresidual chlorine decay in reclaimed water network. Most studies still continue to usethe basic theory of drinking water. So it is necessary to explore the renewable waterresidual chlorine decay laws.This research comprehensive discusses the recycled water residual chlorinedecay laws through the static and dynamic experiments. In the static experiments theresidual chlorine decay process of the network main body water is divided into twostages. The two stages are divided by2h.2hours of residual chlorine decay processfor the first stage, The rest time for the second stage. It was found that the first stageof the residual chlorine decay coefficient than the second stage of the residual chlorineattenuation coefficient. Results show that chlorine decay has positive correlation withfactors such as: temperature, the initial chlorine concentration, TOC. The ammoniaconcentration has negative correlation with chlorine decay coefficient. Moreover, inthe pilot test we studied residual chlorine decay changes in three different pipes——cast iron pipe with cement mortar, cast iron pipes without cement mortar, PE pipes.Chlorine decay in cast iron pipes without cement mortar was the most between castiron pipes with cement mortar and PE pipes. Chlorine decay in cast iron pipes withcement mortar was more same with PE pipes. In the pilot scale the test residualchlorine attenuation coefficient has positive correlation with the initial chlorideconcentration, flow velocity in dynamic test. The water quality indicators meet therequirements of the agreement by water.Experiment analyzed the actual network pressure and the distribution of residualchlorine combined with the simulation results of EPANET. Combined with simulationresults also analyzed the distribution of residual chlorine and pressure in the network.At the same time, the field sampling analysis indicated that changes between the residual chlorine and turbidity, pH, Escherichia coli. The experiment certificated theaccuracy of EPANET. At last, we put forward four suggestions about the water qualitysecurity of network based on the experiment results.