Determination of sediment quality in the Nyl River system, Limpopo Province, South Africa
- Authors: Greenfield, R. , van Vuren, J.H.J. , Wepener, V.
- Date: 2007
- Subjects: Nylsvley (South Africa) , Wetland management - South Africa - Nylsvley , Sediment quality - Souh Africa - Nyl River , Nyl River (Limpopo Province, South Africa)
- Type: Article
- Identifier: uj:5438 , ISSN 0378-4738 , http://hdl.handle.net/10210/12992
- Description: The importance of wetland management and conservation is becoming more and more prevalent in the world today. It is thus important to determine baseline contamination values for wetlands to assist in making informed management decisions. Sediment from the Nyl River flood plain in the dry Limpopo Province was analysed using sequential extraction and ICP-MS to determine baseline metal concentrations, and bioavailability thereof. Eight heavy metal (Cu, Cd, Cr, Al, As, Zn, Mn, Pb) concentrations were determined and compared to sediment quality guideline values to assess sediment quality. Fractionation of the elements was also noted to assess the bioavailability of the metals. The results indicated that the sediment is of a fair quality in comparison to the sediment quality guideline values. They also indicate that the metals will only become available in the presence of strong reducing agents as most of the metal concentrations were recorded in the 4th and 5th fractions obtained from the Tessier sequential extraction of the sediment samples. The study concluded that the sediment is of a fair quality and that it poses little potential threat to the system.
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Treatability of South African surface waters by activated carbon
- Authors: Lobanga, K.P , Haarhoff, J. , Van Staden, S.J.
- Date: 2013
- Subjects: Activated carbon , Natural organic matter , Surface water , Ultraviolet absorbance
- Type: Article
- Identifier: uj:4834 , ISSN 0378-4738 , http://hdl.handle.net/10210/12480
- Description: Natural organic matter (NOM) in water resources for drinking purposes can be removed by different methods, including activated carbon adsorption. Due to the variability of NOM in natural waters, both in terms of its nature and its concentration, a study was undertaken to investigate NOM removal for a wide range of South African surface waters, sampled at different periods, by the use of granular activated carbon (GAC). NOM removal was assessed by measuring the ultraviolet (UV) absorbance at 3 wavelengths, namely, 254 nm (UV254), 272 nm (UV272) and 300 nm (UV300). A comparison of data between the three wavelengths showed that any of the three wavelengths can be used to assess NOM removal by GAC, which is well described by the Freundlich equilibrium equation. A treatment target of 40% removal of initial UV254 absorbance was considered. It was observed that, although the GAC dosage was generally a function of the initial UV254 absorbance, differences existed between waters. This suggests that GAC usage rate is not only a function of the initial UV absorbance but also of the NOM composition, indicating a need for improved NOM characterisation. Comparison between the UV absorbance and dissolved organic carbon (DOC) data suggested that for some waters UV254 absorbance can be used as a rapid substitute for DOC. Finally, the high GAC dosage rates required for the target criterion revealed that the process is inadequate for use at the initial stage of raw water treatment; GAC adsorption should be used at later stages of drinking water treatment.
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