The Experiment On The Influence Of Reclaimed Water Chlorination On Water Quality And Pipeline Corrosion

The security of reclaimed water in network has become the key factor for itscontinued development, and disinfection is the first premise for the safe use ofreclaimed water. Chlorine disinfection in the application of water supply in ourcountry has been widely applied, it is a mature technology, but the project time ofrecycled water reuse is very short. What impact on reclaimed water quality withdifferent chlorine concentration, and whether the increasing chlorine concentrationwill accelerate the reclaimed water effect on corrosion of pipe are still unknown.Based on cast iron pipe with cement mortar lining of nodular test device, the staticimmersion test and the dynamic simulation experiment were carried out with differentinitial concentration of chlorine to research the influence of chlorine decay. Chlorinedecay models of reclaimed water in the experimental pipelines fitting by matlabsimulation function, the decay law of water samples in the experiment of parallel firstorder model, and has good correlation property. Initial chlorine concentration isproportional to the attenuation coefficient k1and k2value, so as the ratio of fastreaction. Analysis the quality indexes of water with different amount of initialchlorine, such as TOC, turbidity, total iron content, and it is concluded that: the initialamount of chlorine affect the change of total iron concentration, the more the initialamount of chlorine, the higher the total iron content in water samples, there was littletie between initial chlorine quantity and the changing rule of the TOC and theturbidity; When residual chlorine concentration is higher, the TOC and total ironconcentration reduced. When residual chlorine concentration is reduced to less than0.1mg/L, the concentration TOC and total iron concentration recovered, but theresidual chlorine content has no direct relationship with the change of turbidity; fromprotection of residual chlorine for water quality standards and maintain the networkperspective, the appropriate chlorine concentration is8mg/L in reclaimed water; thehigh consumption of chlorine reclaimed water problems, determine the mainconsumption of chlorine substance for the consumption of chlorine was soluble COD(mainly including-OH and double bond in organic matter), rather than the nitratenitrogen. It is suggested that the concentration of ozone is increased to more than5mg/L, to ensure good contact with ozone and water samples, add some oxidant, and solve the problem for sewage plant effluent COD standard from the upstream.In order to research the corrosion of reclaimed water to cement mortar lining andcast iron materials. Based on the study of the second Fick diffusion law of concrete,the recommended parameters of the chloride ion diffusion model for cast iron pipewith cement mortar lining were put forward. On account of the study of the surfacemorphology of standard cast iron bolt analysis: reclaimed water corrosion effect foruniform corrosion of cast iron materials, not pitting corrosion, the corrosion productswere most iron oxide on surface, and part of the product of sulfur bacteria effect; therewas a great difference that substrate surface element difference, the location of thesevere corrosion is found that the existence of chlorine, chlorine ion has strongpenetration capatuty, it is likely to be joined in corrosion. Adopting electrochemicalmethod and weight-loss test method research of reclaimed water after chlorinecorrosion rate of cast iron material, the influence of the analysis, cast iron willgradually form corrosion product layer in recycled water, in the late may protectivecast iron materials; chlorine can reduce the corrosion rate of reclaimed water for castiron material, the reason is the chlorine can inhibit microbial erosion of cast iron.