Analysis Of Water Quality And Quantity In Intercepting Pipes In Xi’an

The research was conducted referring to the Xi’an urban sewage pipe network, tofind the changing rules of water quality and quantity in intercepting main pipes in Xi’an.Three aspects has been analyzed-the sewage quality change, poisonous and harmfulgases and sediment features. The change rules of sewage water quality and quantity inpipes were studied by using pipeline robot and sonar imaging technology, combinedwith gas on-line monitoring, tiny electrodes, scanning electron microscopy (SEM) andPCR–DGGE. In addition, the influence of bad weather was also considered, such asheavy raining days.The results show that the variation of water quality in separate system of sewagepipe network was greater than that in combined systems. In combined systems, theCOD, TN and NO3-N decreased respectively26.7mg/L,6.5mg/L and0.8mg/L.However, TP along the path in the whole process of was not obvious, and NH3-N alongthe path was growing by an average of2.3mg/L per kilometer. In separate systems, thechanges were greater: the COD, TN and NO3-N decreased respectively38.6mg/L,7.2mg/L and3.1mg/L. Variation of TP in the whole way was still not obvious, and NH3-Nwas also a growing trend, rising by an average of3.1mg/L per kilometer. Comparedwith combined systems, the separate systems seems to be more better-the thickerbiofilm, more bacteria categories, and solider structure of biological membrane. Inaddition, toxic or harmful gases were existed in two kinds of sewage pipe networksystem, such as H2S, CH4and CO, etc.The sediment siltation phenomenon existed in some area of Xi’an sewage pipe network system. The situation in combined systems was a little worse than that inseparate systems. Research shows that the siltation was formed because of water insewage pipe flowing into main pipes system in rectangular angle when the velocity wasless than0.6m/s.