Research On Grow Ring Composition Of Water Supply Network And Microbal Characteristic

The growth ring of the pipeline is a mixture of precipitates,corrosive substances,sticky dirt and biofilm.The growth rings can easily deteriorate the water quality that has reached the standards,causing secondary pollution of the water supply system.Therefore,the corrosion of metal pipes in water supply networks is studied.Based on the analysis of the components of the growth rings in the water supply pipes and the research on the mechanism of EPS formation,it is of great significance for urban safe water supply and ensuring people's normal life.In this paper,the composition of the growth rings in the water supply network is studied.The growth rings are divided into three layers in the longitudinal direction of the section.The TOC in the growth ring was measured and the TOC in the grown ring sample was found to be 2.31%.The morphology,specific surface area and pore size of each layer of the growth ring were observed.The pore size of the surface layer,the intermediate layer and the corrosion layer of the growth ring was between 17.000 ?-3000.000 ?.The BET specific surface areas of the surface layer,the intermediate layer,and the etching layer of the growth ring were: 97.2687 m 2 /g,63.11173 m 2 /g,53.4781 m 2 /g,respectively.The specific surface area distribution,pore size distribution,and pore volume distribution of BJH adsorption and desorption decrease in the order of the surface layer,the intermediate layer,and the corrosion layer.The metal contaminants in the growth rings were measured.The main metal contaminants in the growth rings were: iron,lead,zinc,chromium,cadmium,and manganese.The iron content reached 642,500 ug/g.The main components of the growth ring were analyzed.The main components of the growth ring were goethite and hematite.The contents of both were 76.93% and 23.07%,respectively,and the goethite content was nearly 3 times the content of the pyrite.The type and content of trace elements in the growth rings were analyzed by X-ray fluorescence spectrometry.The main elements in the growth rings were oxygen and iron,accounting for 24.032% and 29.334%,respectively,close to 1:1.The polysaccharide content in the extracellular polymeric substances in the growth ring was 1.852 mg/ml and the protein content was 1.274 mg/ml.Using molecular microbiology technology,microbiological population structure of the microorganisms in each layer of the growth ring was studied at the level of gates,classes,orders,families,and genera.Heterotrophic bacteria and purebred iron bacteria were isolated from the growth rings,and materials were prepared for subsequent experiments.The three most common organic substances in drinking water,methylene chloride,chloroform and dibutyl phthalate,were selected for the study.The extracellular polymeric substances secreted by iron bacteria and heterotrophic bacteria were used as research subjects to analyze the influence of the most common organic pollutants in water on the extracellular polymer excreted by the selected iron bacteria and heterotrophic bacteria at different concentrations.Due to the oligotrophic environment in the water supply network,the concentration of dichloromethane,chloroform,and dibutyl phthalate in the three organic substances added to the water during the experiment is very low.Therefore,in the extracellular polymers secreted by iron bacteria and heterotrophic bacteria,Both the polysaccharide content,the protein content and the total amount of the extracellular polymeric substances are relatively low.The effects of three organic substances,methylene chloride,chloroform and dibutyl phthalate,on the secretion of extracellular polymers from iron bacteria and heterotrophic bacteria,with the increase of the concentration of organic substances in the water,the content of polysaccharides and protein content and the total amount of the extracellular polymeric substances showed an increasing trend.