Abstract
This research focused on the impacts of environmental policies on the conservation and improvement of urban river water quality in Mongolia. Wastewater contaminated by heavy metal (chromium) from the thriving tanning industry has been recognized as a problem in Ulaanbaatar, the capital of Mongolia, and a facility for pretreatment of chromium-contaminated wastewater was introduced in 2016. To verify the impact of this facility on the water quality of the urban area surrounding the Tuul River, and to assess the current status of potential water pollution, a long-term survey (2014－2018) was conducted using data from 10 monitoring points located upstream and downstream of the wastewater discharge point. Results showed that the concentrations of inorganic nitrogen, phosphorus, and organic matter (biochemical oxygen demand and chemical oxygen demand) were extremely low at points upstream of the point of wastewater discharge from the treatment plant in Ulaanbaatar. Downstream of the point of wastewater discharge, the chromium concentration decreased following commissioning of the pretreatment facility, indicating that the facility is effective. However, concentrations of organic matter, inorganic nitrogen, and phosphorus increased rapidly, indicating inadequate treatment at the plant, especially in winter. Therefore, new treatment measures are necessary and the formulation of appropriate environmental effluent discharge standards and safety standards are required for proper operation of wastewater treatment plants in extremely cold regions.
