Mechanism Of Pathogenic Microorganism Inactivation By Electrocatalytic Membrane

The spread of water-borne diseases caused by microbial pollution of water sources has seriously affected human health.The effective method to inactivate pathogenic microorganisms in water has become an important research direction to improve water quality conditions.Common disinfection technologies include ultraviolet,chlorination,ozone,ultrasound,and electrochemistry,which have disadvantages such as low efficiency,high energy consumption,and generation of disinfection by-products.Therefore,efficient and environment-friendly disinfection technology has become a research hotspot.Electrocatalytic membrane technology is an advanced oxidation technology that combines the physical separation of membranes with electrocatalytic oxidation technology.As so far,electrocatalytic membranes have been studied more in the aspects of organic matter degradation and electrochemical synthesis,but less in the inactivation of pathogenic microorganisms,especially the inactivation mechanism remains to be elucidated.In this paper,Escherichia coli and MS₂ bacteriophage were used to simulate pathogenic bacteria and viruses in water.The mechanism of pathogenic microorganism inactivation by electrocatalytic membrane was studied by analyzing the damage to proliferation and culture capacity,peripheral structure,and metabolic capacity.（1）Study on the mechanism of bacteria inactivation by the electrocatalytic membrane.Under the direct-current electric field,the electrocatalytic membrane produces reactive oxygen species such as·OH and ¹O₂ that impair the culturability of E.coli,which can effectively inactivate bacteria.The inactivation effect of E.coli increases with the increase of current density and decreased with the increase of the flow rate.When the current density was up to 75 m A·cm^-2 and the liquid flow rate was 3.0m L·min^-1,the inactivation rate of E.coli reached 4.10-log.SEM and TEM observations showed that the surface structure of E.coli processed by the electrocatalytic membrane was damaged.The bacteria collapsed and atrophied,fragmented and cross-linked.The cell wall and membrane of E.coli were damaged with the cytoplasm,organelles,and other intracellular substances flowing out.Further observation under the laser confocal microscope by co-staining with PI and SGI dyes showed that the cell membrane permeability of E.coli increased continuously with the increase of current density.Resazurin reduction experiments showed that the bacterial cell reductase was destroyed by electrocatalytic membrane oxidation,and the percentage of E.coli with metabolic capacity dropped to 32.4%.The study indicated that the electrocatalytic membrane process mainly inactivates bacteria by destroying their culturability,peripheral structure,and metabolic capacity.（2）Study on the mechanism of virus inactivation by the electrocatalytic membrane.The electrocatalytic membrane has a good removal effect on viruses.Under the conditions of a current density of 75 m A·cm^-2 and a liquid flow rate of 3.0 m L·min^-1,the removal rate of MS₂ phage reaches 3.77-log.The results of TEM showed that the MS₂ phage lost its normal spherical shape where the surface appeared hollow,wrinkled,broken and deformed,indicating that the morphological structure was damaged.The capsid protein of the MS₂ phage processed by the electrocatalytic membrane was destroyed.The total protein content decreased by 63.0%and the TOC of the MS₂ phage water sample decreased by 25.5%after the electrocatalytic membrane treatment.It indicated that the electrocatalytic membrane can mineralize MS₂ phage and destroyed its structure and composition.Thus,electrocatalytic membranes inactivate viruses by impairing their infectivity and destroying surface capsid proteins’structure and composition.In summary,the electrocatalytic membrane has a good inactivation effect on pathogenic microorganisms.It can destroy the proliferation and culture ability,morphological structure,cell membrane integrity,and metabolism ability of bacteria,and destroy the infection ability of viruses and the structure of surface capsid proteins.composition,thus the pathogenic microorganism cannot carry out normal life activities and become inactive.