Seoul City Achieves Water Quality Indicators Exceeding Phase 1 Total Pollution Load Management in Han River

Exceeded Ministry of Environment Targets by 51% for Total Phosphorus (T-P) and 32% for Biochemical Oxygen Demand (BOD)

[Asia Economy Reporter Lim Cheol-young] On the 6th, the Seoul Metropolitan Government announced that both indicators showing the water quality of the Han River, ‘Total Phosphorus (T-P)’ and ‘Biochemical Oxygen Demand (BOD),’ have exceeded the target values set by the Ministry of Environment.

The concentration of ‘Total Phosphorus (T-P)’ in the water was 0.114 mg/L, lower than the target of 0.236 mg/L, exceeding the target by 51%. The ‘Biochemical Oxygen Demand (BOD)’ was measured at 2.8 mg/L, lower than the target of 4.1 mg/L, exceeding the target by 32%. The lower the values of these two indicators, the more improved the water pollution level, indicating cleaner water quality.

In particular, based on 2017, both indicators showed a trend of gradual improvement with values lower than the targets. BOD improved from 4.5 mg/L in 2016 to 3.8 mg/L in 2017, then continued to decrease to 3.0 mg/L in 2018, 2.8 mg/L in 2019, and 2.8 mg/L in 2020. T-P decreased from 0.288 mg/L in 2016 to 0.236 mg/L in 2017, 0.149 mg/L in 2018, 0.126 mg/L in 2019, and 0.114 mg/L in 2020.

The improvement in Han River water quality is the result of Seoul’s multifaceted policies to reduce water pollution alongside the implementation of the Total Water Pollution Load Management system. Seoul has concurrently implemented policies such as stricter water discharge standards at four water reclamation centers, installation of CSOs (Combined Sewer Overflow) retention tanks with a capacity of 46,000 tons, and water quality monitoring through 82 measurement networks.

Seoul has also established and operates a total of 82 ‘Han River tributary mesh-type water quality monitoring networks’ to quickly detect water quality changes and take immediate action when problems arise. Since May 2018, Seoul has been collaborating with district offices to comprehensively monitor the water quality of tributaries flowing into the Han River.

First, the water discharge quality standards at the four water reclamation centers in Seoul are managed more strictly than the standards under the Sewerage Act (BOD 10 mg/L or less). The discharge levels were lowered to 5.9 mg/L at Jungnang, 6.3 mg/L at Seonam, and 7.0 mg/L each at Tancheon and Nanji. Non-point source pollution entering rivers during rainfall is also intensively managed. The ‘CSOs retention tank,’ which temporarily stores high-concentration sewage (rainwater + wastewater) during the initial rainfall and sends it to the water reclamation center after the rain stops, was completed and put into operation in 2019 at Yangpyeong No.1 detention basin, with two additional tanks currently under construction.

Following the completion of the first phase, Seoul plans to establish the second phase (2021?2030) Total Water Pollution Load Management implementation plan in the second half of this year. To achieve the 2030 target water quality set by the Ministry of Environment, Seoul intends to discover various water quality improvement measures to transform the water environment into a clean and safe habitat for diverse fish species.

Meanwhile, Seoul will release the ‘Integrated Water Quality Index,’ which allows citizens to intuitively check the water quality status, through the ‘Water Circulation Information Disclosure System (http://swo.seoul.go.kr)’ in the second half of this year. It was jointly developed by the Health and Environment Research Institute and the University of Seoul. The index expresses river pollution levels with red for very poor and blue for very good, making it easy to check water quality.

Applying the ‘Integrated Water Quality Index’ to evaluate 58 water quality measurement points across seven water systems in 2020, five points including Baeguncheon were rated ‘Very Good,’ and 48 points including Dobongcheon were rated ‘Good.’ All rivers showed satisfactory water quality of ‘Normal’ or better.

Choi Jin-seok, Director of the Water Circulation Safety Bureau of Seoul, said, “Seoul will do its best to achieve the second phase total load management target water quality by installing total phosphorus treatment facilities at four water reclamation centers and additionally constructing CSOs retention tanks underground at Eungbong detention basin and Hwikyung detention basin.”

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