Abstract
Ph.D.
Natural Organic Matter (NOM) consists of a highly variable mixture of products found in various types of water and soils, formed as a result of decomposition of plant and animal material into water. NOM is a precursor for the formation of disinfection by-products (DBPs) during water disinfection. It causes undesirable colour, taste and odour in water. The reduction of NOM affects the capacity of other treatment processes to remove organic micro-pollutants or inorganic species that may be present in the water.
The differing levels and composition of NOM in South African water sources in different regions suggests that a water treatment strategy by a treatment plant should address the issues relating to specific NOM and its treatability. Therefore, in order to reduce NOM from water in a water treatment train, the composition of the NOM in the source water must be taken into account, since its composition at any given time may depend on the local prevailing conditions. The primary objective of this study was therefore to characterize NOM present in South African source waters through extensive sampling of representative water types at identified regions in the country and develop a rapid NOM characterization protocol.
Water samples were thus collected from eight different water treatment plants broadly located within the five major source water types of South Africa between the periods of February 2010 to June 2011 in five sampling rounds. The sampling campaigns were planned and timed in order to accommodate the dry and the rainy seasons. The water treatment plants sampled were: Loerie (L) Water Treatment Plant, Midvaal (M) Water Treatment Plant, Olifantsvlei (O) Wastewater Treatment Plant, Plettenberg Bay (P) Water Treatment Plant, Rietvlei (R) Water Treatment Plant, Umzoniana (U) Water Treatment Plant, Vereeniging (V) Water Treatment Plant, and the Wiggins (W) Water Treatment Plant. The L water is from a small impoundment, which is fed from the Kouga Dam. The M water is pumped from the Vaal River.