Effluent treatment and its re-use for the Kriel Power Station

Abstract

Kriel Power Station generates effluent of about 5ml per day from different effluent streams of the pre-treatment plant. Currently the water is recovered into the effluent sump and pumped to the high level ash water sumps where a percentage is used for the ashing system while most water remains within the sump. There is a continuous intake of raw water to the cooling water (CW) system due to water losses through evaporation, effluent, leaks etc. Due to water scarcity in South Africa, Eskom embarked on a drive to save and protect water resources. A proposal is made through this research to recover most effluent into the CW system in order to save water and to reduce the disposal to the environment . CW system is chosen as the best opt ion for effluent recovery because there is more control over it on chemistry in terms of operation. Different technologies are discussed as options on how to recover effluent water; treat it up to acceptable Eskom Cooling Water Chemistry Standards and re-use it into the station's cooling water (CW) system. The study revealed savings of about R14.6 M per year if effluent could be reused in the CW instead of fresh raw water intake for make-up; which can be invested into initiating effluent recovery project.