Tea Polyphenol Disinfection Dose Control And Microbial Community Analysis Of Pipeline Network

With the progress of human society,the quality of drinking water has been paid more and more attention.However,with the rapid development of the city and the increasing number of population,the service area of the water plant is also gradually expanded,and the load of the water supply network is increasing.This directly increases the retention time of water in the pipe,which in turn increases the risk of re-growth of pathogenic microorganisms in the water.With the development of science and technology,drinking water purification technology has also experienced three stages:the first generation of drinking water purification technology with coagulation,precipitation,filtration and chlorine disinfection,the second generation of drinking water purification technology with depth treatment as the focus,and the third generation of drinking water purification technology with membrane treatment as the representative.However,the current practical application of membrane treatment and related studies have found that due to the existence of working pressure and the small cell size during the growth period of microorganisms,some microorganisms will leak into the filtered water through the ultrafiltration membrane,resulting in membrane leakage,resulting in a certain risk of biosecurity in the filtered water.The existing conventional disinfection methods such as chlorine disinfection,chloramine disinfection,ozone disinfection,ultraviolet disinfection have certain limitations.The efficient green disinfection method with less byproducts,extensive antibacterial activity and continuous disinfection ability of tea polyphenols can be applied to the disinfection of ultrafiltration effluent.In order to provide theoretical support for the practical application of disinfection of tea polyphenols,this paper analyzed the water quality of ultrafiltration effluent under different dosage of tea polyphenols,determined the optimal dosage of tea polyphenols,and carried out the chemical kinetic equation fitting for the decay process of tea polyphenols within 48 h to determine the specific decay process of tea polyphenols within 48 h.The ultrafiltration outlet pipe network was simulated,the control amount of the end of the tea polyphenol disinfection pipe network was defined,and the morphological characteristics of the pipe wall biofilm and the microbial population structure in the water at different monitoring points of the pipe network were analyzed.In the dosage test of tea polyphenol disinfectant,it was determined by tabletop test that the optimal dosage of tea polyphenol applied to ultrafiltration effluent disinfection was 5mg/L.The decay process of tea polyphenols at this dosage conforms to the zero-order kinetic equation,and the reaction rate constant of tea polyphenols is k=0.06942（mg/（L·h））,with a half-life of 36.2 h.The attenuation kinetics equation was fitted to calculate the attenuation of tea polyphenols to 1.58 mg/L after 48 h.Considering the experimental results,in order to ensure the continuous disinfection effect of tea polyphenols,1.5mg/L tea polyphenol allowance at the end of pipe network is appropriate.The concentration of tea polyphenols in water was correlated with COD_Mn,indicating that tea polyphenols were the main source of COD_Mnin water.However,the dosage of tea polyphenol disinfection did not lead to excessive COD_Mnin water.In biofilm and the population structure in water,the morphological and structural characteristics of the biofilm and the distribution of microorganisms in the biofilm at the monitoring points with different concentrations of tea polyphenols in the pipe network were obtained through the joint observation of a variety of microscopes,and the growth rules of the biofilm were summarized.Through high-throughput sequencing of water samples from different monitoring sites,the dominant microbial species of each monitoring site at the level of phylum,class,order,family and genus were identified,and the differences of microbial populations at each monitoring site were analyzed to clarify the bacteriostatic characteristics of tea polyphenol disinfection at the level of microbial cells.The risk of microbial regrowth after disinfection and the possible presence of specific disinfection-damaging bacteria were revealed to provide directions for the next research.