| Because the disadvantage result of bacterial regrowth,people have been began toconcern about the regrowth of bacteria in water distribution system.An example ofTianjin University distribution system,the paper studied the problem of bacterialregrowth and restraining measures in detail.Based on the analysis of the mechanism and influencing fators of bacterialregrowth, we established the testing scheme. In order to learn the potential trend ofgrowth,the paper extend the culture time of HPC and coliform to 72hr.After thecontinuous sampling and analysis,we obtained a lot of the data about the water qualityand knowed the water quality and the correlation among the water quality data.By analyzing characteristics of response variable and the applying conditions ofstatistical methods,the paper chose linear regression and Logistic Regression model.Itturned out that the former didn't achieve a real result.The Logistic Regression is fit forthe two level Response Variable (HPC) which is achieved by the SAS statisticalsoftware. Firstly, regarding primary water quality data as the explanatory variables,gain a single viable model (only including Fe) by the stepwise selection,which has aexcess precision of 90% when the determinant probability is supposed 0.5 or 0.85.Inorder to eliminate the co-linearity among water qualities, the paper applied thePrincipal Components Analysis(PCA) to the primary water quality data,then establishanother water quality prediction model,in which the three Principal Components areregarded as the explanatory variables. Compared to the former, the latter can moreaccurately embody the mechanism of bacterial regrowth and also have a goodprecision . In conclusion,considering the reasons of bacterial regrowth, the paper pointedout the significances of water quality pridictiont, and brought forward some measurespreventing bacterial regrowth, which involved enhancing water treatment ,controllingerosion ,flushing pipelines and reinforcing management etc.
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