濟州地域 下水處理水 再利用을 위한 政策 方案

Abstract

In this study, to propose a water reuse system suitable for Jeju, we reviewed water treatment technologies being implemented in sewage treatment plants in Jeju, which turn wastewater into water for agricultural purposes. Thus, in this study, we reviewed related literatures, quantitatively and qualitatively surveyed the water discharged from the sewage treatment plants, examined the status of the water reuse system that has been partially used, and analyzed the agricultural environment for the discussion of the technical and political measures to introduce the applicable water reuse system and extensively implement water reuse projects. The analysis of the agricultural environment in the Jeju Special Self-Governing Province indicated that the area was extremely vulnerable to drought or rainless periods, by the nature of upland farming. The area of Hangyeong-myeon in the western part of Jeju is known to experience drought every 2 ～ 3 years. In Jeju, the optimal amount of groundwater drilling was 1,709,935 ㎥/day and the drilling rate was 96.6% as of the end of 2007. This suggests that the groundwater drilling might have reached the limit of the resource. The drilling rate reached 178 ～ 190%, particularly, in the western area, including Aeweol, Hangyeong and Daejeong, indicating that the drilling rate significantly exceeded the optimal drilling rate. As the concentration of Cl- in the treated sewage was higher in Jeju than in inland areas, it was unfit to be used without reclaiming. To decrease the concentration of Cl-, the combined sewer system needs to be modified into a separated sewer system to prevent the incoming seawater from seeping through the collecting pipes. Stronger measures must also be considered, for example, by imposing relatively high fees for the usage of sewage facilities on seafood restaurants with a fish tank and aquariums, which usually discharge seawater into the sewer. Jeju requires a customized water reuse system that filters, desalinates and sterilizes the treated sewage to optimize the concentration of Cl- for the proper reclamation of the treated sewage. The desalinated water can be used to artificially recharge the groundwater to prevent the contamination of incoming seawater, or it can be used to water the neighboring golf course during the winter when less water is used for agriculture. To extensively implement the water reuse projects, strong determination is needed to establish and promote the water reclamation plan in administrative, economic, legal and technical aspects. The optimal measures shall be presented based on the interrelation between such aspects, and full support shall be given to the stage of facilitating the water reclamation.