Activated carbon-based hot water-assisted backwashing system for active disinfection of Chironomus riparius larvae

Abstract

The presence of midge larvae in tap water is a critical issue for the environmental health of water sources, as well as for water quality and safety. Although methods such as ozone treatment, coagulation and chemical applications have been attempted as primary removal methods, they have not yet succeeded in completely eradicating larvae. This study identified the use of hot water for filter backwashing as an effective method for fully eliminating larvae in water treatment facilities. Despite its apparent simplicity, this approach has not been previously explored for larval disinfection. We developed a bench-scale system that utilizes activated carbon and hot water-assisted backwashing. Our research shows that filter backwashing can achieve total disinfection of Chironomus riparius larvae at 45 °C in just 3 min. Furthermore, a cost assessment was conducted to determine the cost efficiency of the designed system for implementation in water treatment facilities. An economic evaluation based on the Bucheon Water Treatment Plant (with a daily flow capacity of 600,000 m³) revealed an additional cost of $3.65 per 1000 m³ of water to ensure effective larval control. This study provides an efficient and environmentally sustainable solution for removing midge larvae from water treatment facilities.