Applying natural treatment systems for the improvement of the quality of river water

In 2001, the Taiwan Environmental Protection Administration, Taiwan Water Resources Agency, and Kaohsiung County Government jointly initiated an artificial wetland project by constructing a 120-ha multi-function wetland to improve the water quality and the ecosystems of the environment surrounding Kaoping River. The finished constructed wetland is located next to the famous old Kaoping River Rail Bridge at Kaohsiung County, and thus, it is named Kaoping River Rail Bridge Constructed Wetland. The major flowflow comes from the local drainage systems containing untreated domestic, agricultural, and industrial wastewater, and treated industrial wastewater from a paper mill. Based on the quarterly investigation results of water samples taken from 2008 to 2009, more than 96% of total coliforms (TC), 48% of biochemical oxygen demand (BOD), and 40% of nutrients (e.g., total nitrogen, total phosphorus) were removed with the help of the constructed wetland system. Thus, the wetland system has a significant effect on the improvement of the water quality and is capable of removing most of the pollutants from the local drainage system before they are discharged into Kaoping River. The Kaoping River Rail Bridge Constructed Wetland has become one of the most successful multi-function constructed wetlands in Taiwan. The experience obtained from this project will be helpful in designing similar natural water treatment systems for the improvement of the river water quality for other river basins.