The Oxidizing Removal of the Fourth Instar Larvae of Chironomus Kiiensis in Drinking Water

Chironomus kiiensis larvae which cannot be exterminated by conventional disinfection process propagates prolifically in eutrophic water body, and it therefore turns to be a potential problem encountered in drinking water quality. In this paper, the quantitative experimental studies were carried out on inactivation of the fourth instar larvae of Chironomus kiiensis in the raw water using oxidants, such as chlorine (Cl₂), chlorine dioxide (ClO₂) and ozone (O₃). The results showed that ozone and chlorine dioxide can be selected as effective oxidants for inactivation Chironomus kiiensis larvae because of their strong inactivation abilities. In addition, mortality of the fourth instar larvae of Chironomus kiiensis after pre-oxidation followed by coagulating-sedimentation process was investigated. The results showed that the 4th instar larvae of Chironomus kiiensis in the raw water could deposit with floccules followed by coagulating-sedimentation process, and sedimentation water was not affected by Chironomus kiiensis larvae. The fourth instar larvae of Chironomus kiiensis would die in 6h with the chlorine dioxide dose of 2.0mg/L. And the excessive propagation of Chironomus kiiensis larvae could be controlled effectively in sedimentation tank by chlorine dioxide pre-oxidation.