关键词: 二氧化氯, 自由氯, 电解, 污水消毒

Abstract: Combinations of chlorine dioxide and chlorine by mechanically mixing are finding potential applications in drinking water and urban reuse disinfection to achieve maximum disinfection and minimum toxicity simultaneously. However, transportation and reservation of chlorine dioxide and chlorine may threat to environmental safety. Therefore, site preparation methods are necessary for field use. At present, preparation methods of associated chlorine dioxide-free chlorine disinfectant include chemical reduction of sodium chlorate and electrolysis of sodium chloride. And the content of chlorine dioxide is usually below 30%. To extend the preparation method of associated chlorine dioxide-free chlorine disinfectant, the electrolysis of sodium chloride (NaCl) was followed by chemical oxidation of sodium chlorite(NaClO2) with membrane-free plate electrode reactor. The content of ClO2 in the compound disinfectants can be controlled. The effect of current density(A), mass ratio of NaClO2:NaCl(B), electrolysis time(C) on concentration and mass percentage of ClO2, free chlorine, ClO2- and ClO3- was investigated systematically. With the current density of 41.67~83.33A.m-2，mass ratio of NaClO2 and NaCl at 1:3~3:3，reaction time at 5~15min, the mass percentage of chlorine dioxide(ClO2) and free chlorine reached 70% and 20% in the compound solution. The free chlorine yield was mainly affected by factors C and A, the ClO2 was significantly influenced by factors C and B, and the by-products of ClO2- and ClO3- were greatly impacted by factor A. The total coliforms of urban sewage reached 105 ~ 108 cfu.L-1 after secondary treatment and before disinfection. The disinfected effluent after 30min contact time with ClO2 dosage of 4mg.L-1 and free chlorine of 1.20mg.L-1 above, complied with water quality standard for urban miscellaneous consumption GB / T18920-2002. In addition, the use of disinfectants was reduced, as well as the generation of ClO2-. Some fundamental insights into the preparation of associated chlorine dioxide-free chlorine disinfectants support its further application in safe urban reuse.

Key words: chlorine dioxide；free chlorine Cl2, electrolysis；wastewater disinfection