Synergic Removal on Chironomus kiiensis larvae in Urban Water Source with Pre-Oxidation

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 work, the quantitative experimental studies were carried out on removal of Chironomus kiiensis larvae in raw water by coagulation-sedimentation process. The coagulation jar test showed that the Chironomus kiiensis larvae could be partially removed from water by coagulation-sedimentation process. Based on it, removal effect of pre-oxidation combined with coagulation-sedimentation process on Chironomus kiiensis larvae was evaluated. The results showed that chlorine dioxide pre-oxidation possessed better removal performance than prechlorinion, and Chironomus kiiensis larvae in the raw water could be completely removed by chlorine dioxide pre-oxidation in combination with the coagulation-sedimentation process at chlorine dioxide dosage of 0.8mg/L. The pH in the range of 6-8 did not affect the inactivation efficiency of chlorine dioxide, whereas pH 10 resulted in around 10% decrease in removal rate. Meanwhile, the removal rate of Chironomus kiiensis larvae improved with the temperature increasing within the range investigated of 15-30°C. The removal rate was reduced by 6.7% when temperature reduced from 30°C to 15°C.