The Impacts of Geothermal Fluid Discharge on Surface Water Quality with Emphasis on Arsenic

Geothermal energy is known to be a clean and renewable energy resource. However, geothermal fluid has significant impacts on surface water quality when disposed in an uncontrolled manner due to the high concentrations of numerous dissolved constituents and the elevated thermal content. The geothermal fluid in western Anatolia typically contains high concentrations of arsenic, boron, and lithium that are toxic to human and plant life. A river system in western Anatolia, Turkey, receives uncontrolled waste geothermal fluid discharge from three fields and is thermally and chemically contaminated. A one-dimensional water quality model is developed to assess the extent and strength of geothermal pollution in the river system. The calibrated and verified model results revealed that although both the point and nonpoint sources of contamination are influential in the water quality degradation, point discharges of waste geothermal fluid were responsible for dramatic increases in the contaminant concentrations and water temperature in the river. The model was later used to analyze the potential measures to improve the degraded water quality and compare the effectiveness of structural and nonstructural mitigation scenarios.