Study On Water Quality Variation During Transportation And Distribution Of Reclaimed Water In Different Materials Pipeline

With the increasing shortage of water resources,the reuse of recycled water is considered to be the most economical and practical way to solve the problem of water shortage.Piline transmission and distribution of reclaimed water is an indisnsable process for the reuse of reclaimed water.The water quality of reclaimed water will change during the piline transmission and distribution process,and the stability of the water quality will be affected.Therefore,the research on the water quality changes of the reclaimed water in the piline is provided to provide reference for ensuring the safety and stability of the reclaimed water in the transportation process.In this study,the self-made rotating ndant reactor was used to simulate the hydraulic conditions in the real piline.When the recycled water was transported in the cast iron,stainless steel and PE,the water quality change rule of the recycled water was analyzed.The initial pH,ammonia nitrogen,The influence of TOC,residual chlorine concentration and other factors on the decay law of residual chlorine,as well as the influence of different water quality factors on the changes of pH,ammonia,TOC,UV₂₅₄,total iron and turbidity in the process of reclaimed water transmission and distribution.At the same time,in view of the corrosion phenomenon of ductile iron pis during the transmission and distribution of reclaimed water,the surface characteristics of the surface of the ductile iron and the corrosion products were analyzed.Research indicates:?1?The residual chlorine concentration of the reclaimed water decreases with the increase of residence time during the transmission and distribution process.The decay law of residual chlorine can be fitted with first-order decay kinetics and improved first-order decay kinetic models.The fitting results show that the total residual chlorine decay rate decreases with the increase of the initial ammonia nitrogen concentration and initial pH,and increases with the increase of the initial TOC concentration;the free residual chlorine decay rate decreases with the increase of the initial residual chlorine concentration.Under the same initial residual chlorine concentration,the decay rate of free residual chlorine in the three systems is: cast iron> stainless steel> PE.Under the same initial conditions,the total residual chlorine decay rate in the three systems The size is: cast iron> stainless steel> PE.?2?Under different initial conditions,the changes of water quality during the transmission and distribution of recycled water are as follows:The change of pH in the process of reclaimed water transmission and distribution for 192 h showed an upward trend as a whole,and finally became weakly alkaline.The effects of different initial conditions on pH are: the higher the initial pH,the smaller the pH increase;the higher the initial ammonia nitrogen concentration,the greater the pH increase;the greater the initial TOC concentration,the smaller the pH increase;In the stainless steel and PE system,the initial residual chlorine concentration increases,and the pH increase increases.In the cast iron system,the initial residual chlorine concentration increases,and the pH increase decreases.Ammonia,TOC and UV₂₅₄ showed a general downward trend during the regenerated water transmission and distribution for 192 h.Different initial conditions can affect the changes of ammonia nitrogen,TOC and UV₂₅₄.The lower the initial pH,the lower the ammonia nitrogen,TOC,UV₂₅₄ decrease;for the cast iron system,the higher the initial ammonia concentration,the lower the TOC and UV₂₅₄ decrease,for the stainless steel and PE system,the higher the initial ammonia concentration,The higher the decrease of TOC and UV₂₅₄;the higher the initial TOC concentration,the lower the decrease of ammonia;the higher the initial residual chlorine concentration,the higher the decrease of ammonia,TOC,UV₂₅₄.?3?The changes of turbidity and total iron in the stainless steel system and the PE system during the test for 192 h were not large,and different initial conditions did not affect the changes in turbidity and total iron.The cast iron system corroded during the test and the total iron was released during the test.The lower the pH,the higher the initial residual chlorine concentration,the higher the initial ammonia nitrogen concentration,the higher the total iron release...