The Influence of Natural Organic Matter in the Power Generation Industry of South Africa: The Eskom Perspective

Gerhard Gericke1, Heena Madhav1, Kelly Whitehead1, Savia S. Marais2, Titus A. M. Msagati3, Bhekie B. Mamba3, and Thabo T. I. Nkambule2

1. Eskom RT&D (Water and Applied Chemistry), South Africa

2. Rand Water (Process Technology Department), South Africa

3. Nanotechnology and Water Sustainability Research Unit, University of South Africa, College of Science, Engineering and Technology, South Africa

Abstract: The focus of this paper is on the influence of natural organic matter (NOM) in the Eskom power generation plants of South Africa and the strides taken by the Eskom power utility to deal with the challenges presented by the occurrence of NOM. A review of recent literature concludes the impact of NOM on power plant chemistry and the detrimental impact of NOM in the power industry was highlighted. This paper concludes the research programme that was established by Eskom to identify and address the organics presents in the raw water and their impact on power plant operation. Characterization of South African raw water sources was done by extensively sampling eight different water treatment plants (waste and potable water treatment) located within the five major source water types in South Africa. The NOM composition of all the samples was studied first by applying conventional (industrial) techniques (UV, DOC, SUVA-254 and bulk water parameters). NOM characterization was further conducted using advanced techniques (BDOC, PRAM and FEEM) which were aimed at developing rapid assessment protocols. The treatability and removal of the NOM in a water treatment train was investigated by determining the character and composition of the NOM samples taken at various stages of the water treatment process. Identification of NOM in Eskom Identification of NOM in Eskom raw water supplies was performed by making use of LC-OCD and SUVA-254 to determine the treatability of the water from the various catchments supplying the Eskom power plants. The use of nanotechnology for the removal or reduction of NOM was pursued by synthesizing and applying Pd-modified N-co-doped TiO2 for the photocatalytic degradation of NOM fractions. The results presented in this study clearly demonstrated the high variability of NOM at the South African Water Treatment Plants. The nitrogen, palladium co-doped TiO2, through photodegradation, effectively removed NOM (up to 96%) when compared to commercial TiO2.

Key words: cooling water, liquid chromatography organic carbon detector, natural organic matter, nanotechnology, photodegradation, power generation