Hunan Wastewater Treatment Plant, Lengshuijiang, Hunan Province

The Hunan wastewater treatment plant is located in Lengshuijiang, a city in Hunan province, China. It serves a population of approximately 232,000, classifying it as a medium-to-large agglomeration under Chinese wastewater management frameworks. The plant is situated along the Zi River basin, which flows into Dongting Lake and ultimately the Yangtze River. As a facility serving over 200,000 people, the plant is expected to meet China's Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants (GB 18918-2002), which mandates secondary treatment with nutrient removal for sensitive water bodies. Chinese regulations require robust infrastructure for agglomerations of this scale. The plant discharges treated effluent into the Zi River, a tributary of the Yangtze River system. This water body supports local agriculture, fisheries, and downstream ecosystems, including Dongting Lake, a critical wetland for migratory birds. Proper treatment is essential to prevent eutrophication and protect aquatic biodiversity in this densely populated region.

The plant discharges into the Zi River, which flows into Dongting Lake and then the Yangtze River. Dongting Lake is a vital freshwater lake that supports diverse aquatic life and serves as a key stopover for migratory birds along the East Asian-Australasian Flyway. The region's intensive agriculture and industrial activity downstream make effective nutrient removal critical to prevent algal blooms and maintain water quality.