Browsing by Author "Nel, Jaco"

Now showing 1 - 3 of 3
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    Comparison of CO2 capture by ex-situ accelerated carbonation and in in-situ naturally weathered coal fly ash
    (Elsevier, 2013) Muriithi, Grace N.; Petrik, Leslie; Fatoba, Olanrewaju O.; M. Gitari, Wilson; Doucet, Frederic J.; Nel, Jaco; Nyale, Sammy M.; Chuks, Paul E.
    Natural weathering at coal power plants ash dams occurs via processes such as carbonation, dissolution, co-precipitation and fluid transport mechanisms which are responsible for the long-term chemical, physical and geochemical changes in the ash. Very little information is available on the natural carbon capture potential of wet or dry ash dams. This study investigated the extent of carbon capture in a wet-dumped ash dam and the mineralogical changes promoting CO2 capture, comparing this natural phenomenon with accelerated ex-situ mineral carbonation of fresh fly ash (FA). Significant levels of trace elements of Sr, Ba and Zr were present in both fresh and weathered ash. However Nb, Y, Sr, Th and Ba were found to be enriched in weathered ash compared to fresh ash. Mineralogically, fresh ash is made up of quartz, mullite, hematite, magnetite and lime while weathered and carbonated ashes contained additional phases such as calcite and aragonite. Up to 6.5 wt % CO2 was captured by the fresh FA with a 60% conversion of calcium to CaCO3 via accelerated carbonation (carried out at 2 h, 4Mpa, 90 o C, bulk ash and a S/L ratio of 1). On the other hand 6.8 wt % CO2 was found to have been captured by natural carbonation over a period of 20 years of wet disposed ash. Thus natural carbonation in the ash dumps is significant and may be effective in capturing CO2.
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    Investigating the natural groundwater recharge and discharge processes of the Saldanha Bay aquifer systems along the West Coast of South Africa
    (University of the Western Cape, 2022) Parker, Aqeela; Nel, Jaco
    Saldanha Bay Local Municipality is partially dependent on groundwater as part of its bulk water supply as surface water resources in the area are extremely limited and fully allocated. Due to this, there is lots of pressure on the groundwater resources by industrial development and residential growth. Despite studies being conducted on these aquifer systems since 1976, they are still poorly understood, especially with regard to their recharge and discharge processes. This study aimed at providing better insight and understanding of the natural groundwater recharge and discharge processes to assist in the better management of groundwater resources in the Saldanha Bay Local Municipality area.
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    The use of stable isotopes to identify surface water–groundwater interaction in the Kruger National Park, South Africa
    (South African Water Research Commission, 2023) Petersen, Robin; Nel, Jaco; Strydom, T
    The role of groundwater, in general, is often overlooked in freshwater ecosystem management policies and in the management of South Africa’s flagship conservation area, the Kruger National Park (KNP). To address this gap, a generalised conceptual model of surface water–ground water (sw–gw) interactions in the southern and central regions of the KNP was developed. To do this, stable isotope ratios (δ18O and δ2H) of groundwater, rainfall and surface water were used to determine the extent to which the base flow of perennial, seasonal and ephemeral streams on different geologies (granite vs. basalt) is driven by rainfall or groundwater.