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🇰🇷 South Korea /Environment & Climate

Nakdong River's 'Subflow Water' Shows Proven Water Quality Improvement

From Hankyoreh · () Korean

Translated from Korean, summarized and contextualized by DistantNews.

At a glance

News Documents & data Context piece
  • Experiments in South Korea have shown that filtering Nakdong River water through underground layers (subflow) significantly improves its quality, raising it to Grade 1b (good).
  • The subflow method reduced total organic carbon by up to 42%, total phosphorus by up to 69%, algal toxins by up to 86%, and turbidity by up to 95% compared to raw river water.
  • The Ministry of Climate, Energy and Environment plans to discuss supplying filtered subflow water to water treatment plants in Daegu and potentially other regions like Busan and Gyeongnam if ongoing experiments continue to yield positive results.

A pilot project in South Korea has demonstrated the effectiveness of 'subflow' water treatment in significantly improving the quality of the Nakdong River, a major waterway often plagued by severe pollution, including algal blooms. The experimental facility, operated for one month at the Musan Water Treatment Plant in Daegu, successfully upgraded the water quality from Grade 2 (slightly good) to Grade 1b (good).

Subflow water, which percolates through sand and gravel layers beneath the riverbed, acts as a natural filter. The Ministry of Climate, Energy and Environment reported that this filtration process led to substantial reductions in key pollutants. Specifically, total organic carbon (TOC) decreased by 33-42%, total phosphorus (T-P) by 66-69%, algal toxins (microcystin-LR) by 82-86%, and turbidity by 89-95% compared to the untreated river water.

Kim Ho-eun, Director of Water Use Policy at the Ministry, expressed optimism about the potential for cleaner tap water for citizens. "If the filtered subflow water is supplied to water treatment plants, citizens can use cleaner tap water than now," Kim stated. The ministry is scheduled to hold its first verification committee meeting on August 5th with water experts, Daegu city officials, and ministry representatives to discuss the experimental results and methods for securing sufficient water quantities.

Depending on the continued success of the experiments and the verification committee's findings, the ministry plans to discuss supplying subflow water to water treatment plants, starting with Daegu. Discussions are also underway to potentially expand this system to other regions, including Busan and Gyeongnam province. The ministry intends to publicly share the daily, weekly, and monthly water quality test results from the subflow experiments, along with the outcomes of the monthly verification committee meetings, on its website starting August 6th.

If the filtered subflow water is supplied to water treatment plants, citizens can use cleaner tap water than now.

— Kim Ho-eun, Director of Water Use PolicyHighlighting the potential benefit of the subflow water system for public water supply.
DistantNews Editorial

Originally published by Hankyoreh in Korean. Translated, summarized, and contextualized by our editorial team with added local perspective. Read our editorial standards.

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