A three step approach for removing organic matter from South African water sources and treatment plants

作者：Nkambule T I; Krause R W M; Haarhoff J; Mamba B B^*

来源：Physics and Chemistry of the Earth, 2012, 50-52: 132-139.

DOI：10.1016/j.pce.2012.08.009

• Biodegradable dissolved organic carbon
• Disinfection by-products
• Fluorescence excitation-emission matrices
• Humic substances
• Natural organic matter

The high variability in the levels and composition of natural organic matter (NOM) in South-African water sources in different regions means that no single treatment process can be prescribed for each water treatment plant operating in the country. In order to remove NOM from water in a water treatment train, the composition of the NOM in the source water must be taken into account, especially as it may not necessarily be uniform since the composition is dependent on local environmental situation. The primary objective of this study was to characterise the NOM present in South African source waters through an extensive sampling of representative water types across the country and then develop a rapid NOM characterisation protocol. Water samples were thus collected from eight different water treatment plants located throughout the country at different sites of their water treatment trains. Raw water samples, the intermediate samples before filtration and water samples before disinfection were collected at these drinking water treatment plants. The fluorescence excitation-emission matrices (FEEMs), biodegradable dissolved organic carbon (BDOC), ultraviolet (UV) characterisation (200-900 nm) and dissolved organic carbon (DOC) analysis were used to characterise the NOM in the water samples. The FEEM and UV results revealed that the samples were composed mainly of humic substances with a high UV-254 absorbance, while some samples had marine humic substances and non-humic substances. The sample's DOC results were within the range of 3.25-21.44 mg C/L, which was indicative of the varying nature of the NOM composition in the regions where samples were obtained. The BDOC fraction of the NOM, on the other hand, ranged from 20% to 65%, depending on the geographical location of the sampling site. It is evident from the results obtained that the NOM composition varied per sampling site which would eventually have a bearing on its treatability. The various water treatment processes employed at the different treatment plants were able to effectively reduce NOM, as evidenced by a percentage DOC removal of between 11% and 85%. The highest DOC removal was achieved at the treatment plants that had highly humic and coloured raw water sources.

• 出版日期2012