Ecological Characteristics Of Chironomid Larvae And Study On Its Removal In Water Treatment Process

As a consequense of eutrophication, Chironomid larvae excessively propagates in water sources, such as reservoir and fresh lake, which induced the 1st instar larvae of Chironomid in source water to enter drinking water treatment system. Several researchers reported that Chironomid larvae is difficult to inactivate using free chlorine at concentrations commonly used in drinking water utilities. In addition, the 1st instar larvae can easily penetrate sand filter and then goes into waterworks reservoir and municipal service pipe due to its motility. Although there are no indications that these organisms pose a threat to public health, their presence is still not appreciated because most people associate the organisms with low hygiene.This study attempted to settle the danger of Chironomid larvae as to ensure drinking water security by two approaches: one is to research on physiology and ecology of Chironomid larvae in order to provide basis data for the forecast of Chironomid larvae and service to the departments of water supply for solving breaking-out of Chironomid larvae; the other is to effectively remove Chironomid larvae from water by strengthening water treatment process as to attain the radical solution for the problem of Chironomid larvae.The result showed that the dominant species in water source and drinking water treatment system was Chironomus kiiensis. Development, growth, survivor and reproduction of the experimental populations of Chironomus kiiensis were observed at 18℃, 22℃, 26℃, 30℃and 34℃respectively. It was found that under 18～34℃the developmental duration decreased while the developmental rate increased linearly with temperature. The relationship between the developmental rate and temperature were further described with five regression equations, which could be applied to predict occurrence period and effective accumulative temperature. The development threshold temperature and effective accumulative temperature for whole generation were 6.68℃and 742.97 day-degrees, respectively. The the generation survival rate, fecundity and population trend index attained their respective maximun values at 26℃. In the tested temperature range, both intrinsic rate of increase (rm) and finite rate of...