Electrochemical Disinfection Of Effluent From Decentralized Domestic Sewage Treatment Facility

With the rapid development of rural economy,the demand for water resources is increasing day by day.However,the low treatment rate of domestic sewage in rural areas brings risks to the environment and human health.In order to improve the quality of ecological environment,the irrigation and reuse of rural domestic sewage can not only reduce the pollution to the environment caused by direct discharge of rural domestic sewage without treatment,but also save the cost of water resources and long-distance water transfer.The reuse irrigation of rural domestic sewage is faced with the pollution problem of pathogenic microorganisms in the water environment.Pathogenic microorganisms will enter farmland with sewage and then enter human body from crops.In addition to spreading diseases,they may carry antibiotic resistance genes,increase drug resistance and threaten human health,so it is necessary to disinfect rural sewage before irrigation.Due to the weak economic strength of rural areas,small scale of sewage treatment,scattered layout,the cost of regular injection of disinfectants is high and the operation and management is not convenient,in order to achieve the unattended disinfection goal,it is necessary to choose a simple operation and maintenance,suitable for dispersed sewage disinfection process.Therefore,for the distributed treatment of rural domestic sewage,this paper adopts the electrochemical disinfection technology,which is convenient in operation and management and can generate disinfectants in situ,so that it can meet the Farmland Irrigation Water Quality Standard（GB 5084-2021）.In this paper,the disinfection effect of electrochemical disinfection and traditional disinfection technology was compared.It is proposed to strengthen the electrochemical cathode reaction to produce hydrogen peroxide and other strong oxidant disinfection,so that the electrochemical disinfection can kill bacteria in the water body with low chlorine concentration and low conductivity.In order to improve the disinfection effect of cathode,a new electrode was prepared by using spinel ferrite and carbon nanotubes.The killing efficiency and removal mechanism of Escherichia coli in water by electrochemistry were investigated.The operation conditions were optimized and the effect of electrochemistry on disinfection and antibiotic removal of actual sewage was evaluated.The main research results are as follows:（1）The disinfection effect of three conventional disinfection technologies was compared:potassium bisulfite disinfection>sodium hypochlorite disinfection>ultraviolet disinfection.The electrochemical and conventional disinfection technology after optimization of cathode can effectively kill bacteria,and the residence time is only 15 minutes.The influence factors of electrochemical disinfection technology were also studied:the disinfection effect of different current density was compared 5m A/cm²,2m A/cm²,0.2m A/cm²,the higher the current density,the better the disinfection effect;The higher conductivity of1300μs/cm>600μs/cm>10μs/cm was more conducive to killing pathogenic microorganisms.Air flow rate 0.7L/min>0.2L/min>0L/min,increasing the air flow rate can improve the concentration of dissolved oxygen in water,the better the disinfection effect;The disinfection effect of different electrolytes was compared with sodium chloride solution>sodium sulfate solution>tap water>potassium nitrate solution.The higher concentration of Cl^-was more conducive to killing bacteria.（2）Three modified cathodes were prepared:Carbon nanotube modified graphite felt,spinel-type ferrite modified nickel foam,spinel-type ferrite-carbon nanotube modified nickel foam,and compared with titanium plate,iridium titanium tantalum titanium,graphite felt and nickel foam,the disinfection effect of spinel-type ferrite-carbon nanotube modified nickel foam electrode was optimized,and its physical characterization and chemical properties were studied.By X-ray diffraction and X-ray photoelectron spectroscopy,it is found that spinel-type ferrite-carbon nanotubes have higher spinel-type ferrites,carbon diffraction peaks and larger peaks of cobalt,indicating that their loading material properties are stronger.Cyclic voltammetry and linear sweep voltammetry also found that the modified electrode has a wider potential window,a higher oxygen evolution potential,and a larger electroactivation area,which can promote the electron transfer process,improve the electrocatalytic performance,conducive to the generation of more H₂O₂,·OH and other active substances,improve the electrochemical disinfection effect.