Aspects of waste management and pollution control in Olkaria geothermal field, Kenya

Abstract

The Olkaria geothermal field, located within the Hell´s Gate national park in the eastern branch of the African rift system in Kenya, has been under exploitation for over 20 years. The greatest environmental challenge has been the large volume of waste geothermal fluids and effluents generated during the exploration and utilisation processes. In this paper the results of an attempt to characterize geothermal and associated waste materials and emissions in terms of their origin, quantity, chemical content, and environmental behaviour, are presented. The basic principles and waste management criteria for the categories identified are reviewed. Closely related aspects of pollution control in the Olkaria region through a monitoring programme for geothermal chemical components and trace elements of environmental significance that arise from the geothermal wastes (Zn, Cd, Pb, Cu, Li, Ba, and F), are described. The results indicate that concentration levels of trace elements Zn, Cd, Cu and Ba in geothermal well discharge water, wastewater, effluents, and condensates are below the international health optimum limits which is not the case for Pb, Li and F. The concentration levels of all the elements except F in potable water sources in the vicinity of the exploited area are within acceptable limits. Soil and vegetation show a small enrichment in the elements but the levels are still far below limits above which contamination is declared. Sound management is needed of the geothermal waste fluids and ...