"Incheon Tap Water Midge Larvae Leakage from Activated Carbon Filter"

Source: Ministry of Environment, Hangang River Basin Environmental Office

[Asia Economy Reporter Moon Chaeseok] The final investigation into the incident of chironomid larvae contamination in Incheon tap water that occurred in early last month concluded that the larvae originated from activated carbon in the water purification plant.

The Hangang River Basin Environmental Office and Incheon Metropolitan City announced on the 28th that the "Joint Expert Precision Investigation Team on Tap Water Larvae" released the final investigation results regarding the chironomid larvae contamination incident at the Gongchon and Bupyeong water purification plants.

Earlier, on the 10th, the investigation team announced interim results stating that the chironomid larvae contamination in Incheon tap water was caused by leakage from the granular activated carbon adsorption beds at the Gongchon and Bupyeong water purification plants.

The team confirmed that when windows are open or ventilation systems are stopped, adult chironomids can enter if people access the area, and that the activated carbon beds provide an environment where larvae can survive.

Additional investigations found traces of leakage from the activated carbon beds. This was evidenced by fine activated carbon particles found on the bodies and epidermis of chironomid larvae that inhabited the activated carbon beds and leaked into supply systems such as reservoirs.

Although the incident occurred in Incheon, the investigation team emphasized that similar incidents could happen at other facilities with similar operations and proposed comprehensive short- and long-term countermeasures.

As short-term measures that can be implemented within a few months, they recommended installing double doors and insect-proof facilities at water purification plants to completely block the entry of adult chironomids and other wildlife.

For water purification plants operating open-type activated carbon beds, they suggested installing openable covers on top of the beds and, as an emergency measure, securely fixing insect screens without gaps.

To prevent larvae leakage, they proposed operational improvements such as temporarily implementing backwash cycles of the activated carbon beds within 7 days and increasing backwash speed during the peak chironomid breeding season from April to September.

They also recommended continuous monitoring of the tap water supply system and facilities if chironomid larvae are still found in the activated carbon beds.

Source: Ministry of Environment, Hangang River Basin Environmental Office

The investigation team also recommended that Incheon City improve facilities and increase staffing.

This was because the team confirmed that Incheon City had operated its water supply business with a focus on cost reduction before 2018 and had fewer water supply personnel per population served compared to other metropolitan cities.

The team suggested that the Ministry of Environment prepare, distribute, and regularly update the "Water Supply Design Standards," "Water Supply Facility Maintenance Manuals," and advanced water treatment facility maintenance manuals for local governments to prevent recurrence of larvae incidents.

The investigation team stated that they plan to submit the final investigation report to the Ministry of Environment, which will review it and establish comprehensive countermeasures.

A representative of the investigation team said, "Although the official activities of the investigation team conclude with this final result announcement, follow-up measures such as establishing countermeasures for short- and long-term tasks and policy proposals will be continuously pursued in cooperation with the government."

This content was produced with the assistance of AI translation services.