The Gyeonggi Provincial Government has requested the central government to establish its own regulatory standards for chlorine and sulfate levels, as concentrations of these ions in a stream receiving wastewater from SK Hynix's semiconductor plant in Icheon exceeded the recommended limits of the Food and Agriculture Organization (FAO).

Gyeonggi Province announced the findings during a press briefing held at the Gwanggyo provincial office on the 5th.

According to the province, the Gyeonggi Provincial Institute of Health and Environment conducted water quality tests on Jukdangcheon, which receives wastewater from the Icheon SK Hynix plant, across three dates: August 26, September 2, and September 3 of this year. The results showed that all nine items with established water quality standards, including Biochemical Oxygen Demand (BOD), were lower than domestic river water quality standards, indicating no abnormalities.

However, the concentrations of chlorine and sulfate ions were higher than those in the nearby Bokhacheon, which does not receive the wastewater.

At a point 0.4 kilometers downstream from the discharge outlet, the average concentration of chlorine ions was 731 mg/L and sulfate ions 1,561 mg/L. At 1.9 kilometers downstream, the average chlorine ion concentration measured 639 mg/L and sulfate ions 1,338 mg/L.

At 7.4 kilometers downstream, the average chlorine ion concentration was 513 mg/L and sulfate ions 1,060 mg/L, showing a tendency for concentrations to decrease further downstream.

In the nearby Bokhacheon, the average chlorine ion concentration was 71 mg/L and sulfate ions 32 mg/L, which were significantly lower than those in Jukdangcheon.

Chlorine and sulfate ions are components commonly dissolved in natural waters such as groundwater or river water and are not critically toxic substances. They are known to primarily affect water taste, cause pipe corrosion, and cause gastrointestinal irritation.

While South Korea has standards for drinking water—setting chlorine ions at 250 mg/L or less and sulfate ions at 200 mg/L or less—there are currently no standards for streams used as agricultural water.

Meanwhile, the FAO suggests general ranges of 355 mg/L for chlorine ions and 0 to 960 mg/L for sulfate ions in its irrigation water evaluation guidelines.

The reason Gyeonggi Province conducted this water quality survey on Jukdangcheon was to predict the impact that wastewater from the Yongin SK Hynix semiconductor plant will have on Gosam Reservoir.

Moon Hee-cheon, acting head of the Gyeonggi Provincial Institute of Health and Environment, stated, "There are currently no discharge standards. If chlorine and sulfate ion levels identical to those in Jukdangcheon flow into Gosam Reservoir starting February next year, research and effective wastewater management measures will be needed in preparation."

For now, Gyeonggi Province has recommended that the Ministry of Climate, Energy and Environment establish management standards and permitted discharge limits for chlorine and sulfate ions.

Additionally, the province plans to continuously monitor the water quality conditions of Gosam Reservoir and surrounding streams while working to ensure that permitted discharge limits for businesses regarding chlorine and sulfate ions are established early.

Previously, Gyeonggi Governor Choo Mi-ae issued administrative guidance to Samsung Electronics and SK Hynix on July 16, stating, "Like global semiconductor companies such as Taiwan's TSMC, we need to increase the process water reuse rate. Since the public supplies the water, companies must also actively engage in wastewater reduction and the development and investment in reuse technologies to increase the utilization ratio of process water at the Yongin semiconductor plant."

(Photo provided by Gyeonggi Provincial Government, Yonhap News)