Disinfection for Removal of Zooplankton with Chlorine Dioxide

The disinfection effect of Copepod of zooplankton with chlorine dioxide was compared with that of chlorine. The experimental results showed that chlorine dioxide was more effective to kill Copepod. Copepod was completely killed by 1.0mg/L of chlorine dioxide for contacting 30 min but the required dosage were about 2.0mg/L of liquid chlorine. The body structure variety of Copepod indicated that the direct oxidation on structure surface was the main reason for chlorine dioxide causing the death of Copepod. As for chlorine, disinfection of Copepod mainly depended on hypochlorous acid (HOCl) permeation to destroy inner cellular protein. The exterior factors of organic precursors and temperature had a negative influence on disinfection rate of Copepod. There was high oxidizability and prone selectivity to kill Copepod during chlorine dioxide. Therefore, the disinfection effect of chlorine dioxide may be less influenced by extraneous factors than that of chlorine. The GC-MS examination showed that the sort and amount of organic substances in treated water by chlorine dioxide were less than that by chlorination.