Study On The Electrochemical Safe Disinfection For Reclaimed Water

At present, in the public water supply system, chlorination is the most widelyused disinfection process. However, disinfection by-products (DBPs) producing fromchlorination such as trihalomethanes (THMs) and haolacetic acids (HAAs) can makethe carcinogenic risk of water increase significantly. Since1970s, electrochemicalsafe disinfection technology has got more and more attention as a clean technology,which without adding chemicals, no secondary pollution, less area occupied, highdegree of automation, easy to combine with other technologies.The purpose of this study is expected to achieve the practical application ofelectrochemical technique on reclaimed-water recycling system with the base study ofelectrochemical water purification technology in the lab. The research contents are asfollow: the influence of different electrode material, water quality and operationcondition on disinfection efficiency in the static experimental study, and through theanalysis of disinfection by-products in the electrochemical disinfection andchlorination process to optimize the security of the electrochemical disinfectiontechnology.The results shows that electrochemical safe disinfection technology caneffectively remove the harmful microorganism in the water, to reach the reusestandard of state City sewage recycling City miscellaneous water quality（GB/T18920-2002）. The experimental results show that when the electrolytecontaining909.09mg/L chloride ions, at a current density of10mA/cm~2, usingTi/IrO2as anode, Fe as cathode, after electrolysis1min bacterial removal rate reached100%. In addition, disinfection efficiency almost remain the same when the pH valuein the range of6.0-8.0with a good performance; the influence of temperature ondisinfection efficiency is relatively complex, low temperature can produce moreactive chlorine, so it has higher disinfection efficiency. disinfection efficiency at6℃ is higher than30℃and20℃; Disinfection efficiency increases with increasingcurrent density, in the same water quality condition, the completely inactivated timewith the current density20mA/cm~2reduced83.33%than the completely inactivatedtime with the current density5mA/cm~2.The study of the amount of trichloromethane formation shows that when thechloride ion concentration is319mg/L in MBR effluent, the current density is10mA/cm~2, after30min electrolysis, the trichloromethane concentration is only43.62μg/L, which has reached the standard of trichloromethane in state drinkingwater health standards (GB5746-2006). And in the same water quality condition,when the amount of chlorine is2.5%, after30min, producing trichloromethaneconcentration is196.30μg/L, which almost3times of the electrochemical safedisinfection technology. It is a very grave threat for safety of water for consumers.