Application Of Chlorine Dioxide Disinfection In Wastewater Treatment Plants

The State Environmental Protection Administration and the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China promulgated Standard for Pollutant Emission of Wastewater Treatment Plants in Towns and Cities (GB18918-2002) On Dec. 24^th, 2002. In the standard, the pathogenic microorganisms of fecal coliform bacteria were designated as a basic control index, requiring that city wastewater must undergo disinfection treatment. After comparing the three disinfection methods of ozone, ultraviolet radiation and chlorine dioxide, chlorine dioxide is chosen as the disinfection method for the secondary effluent water of Jizhuangzi Wastewater Treatment Plant. This research topic proceeds from the application of new technology and identification of the optimal operational mode in order to provide a new mode for disinfection of effluent water of large-sized city wastewater treatment plants. Meanwhile, the research also makes clear the concentration, contact time, operational cost of chlorine dioxide used in large-sized city wastewater treatment plants as well as its influences on effluent water. Through the orthogonal experiment, it is found that the concentration and effective contact time of disinfection are { 2.805g/m3, 2.920 g/m³} and {297s, 303s} respectively and that the direct cost is {0.0171Yuan/m³,0.0178 Yuan/m³} . It is also found that use of chlorine dioxide in disinfection can not only reduce the amount of fecal coliform bacteria, but also lower the concentration of BOD₅ and COD_cr in the water, but it can increase the level of ammonia nitrogen in the water.