Browsing by Author "Wolfaardt, Gideon"

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    Economic risks due to declining water quality in the Breede River catchment
    (South African Water Research Commission, 2018-07-03) Cullis, James D. S.; Rossouw, Nico; Du Toit, Geoff; Petrie, Daniel; Wolfaardt, Gideon; De Clercq, Willem; Horn, Annabel
    Water is a critical resource necessary to support social and economic development. Economic growth and, in particular, the growth of urban and peri-urban areas, however results in declining water quality which threatens water-dependent industries. In developing countries this is a particular concern due to the rapid rate of urbanisation and the limited financial resources and technical capabilities to adequately maintain and upgrade wastewater treatment works. This is particularly relevant in catchments with a high dependence on export-orientated agriculture. This study considered water quality risks in the Breede River catchment as an area which experiences significant urban and peri-urban growth, focusing on economic risks associated with declining water quality, estimates of the costs needed to rehabilitate existing wastewater treatment works, and alternative strategies such as the use of artificial wetlands, the rehabilitation and protection of natural wetlands, as well as the clearing of invasive alien plants. A major conclusion is that the financial risk associated with a declining economy and social instability outweighs the costs that will be needed for rehabilitation of existing treatment plants. Together with more pronounced fluctuations in precipitation anticipated with climate change, these risks due to declining water quality are likely to increase in future with continued urban and peri-urban growth.
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    Surface-attached sulfonamide containing quaternary ammonium antimicrobials for textiles and plastics
    (Royal Society of Chemistry, 2019) Caschera, Alexander; Mistry, Kamlesh B.; Bedard, Joseph; Ronan, Evan; Syed, Moiz A.; Khan, Aman U.; Lough, Alan J.; Wolfaardt, Gideon; Foucher, Daniel A.
    With the risks associated with healthcare-associated infections and the rise of antibiotic resistant microorganisms, there is an important need to control the proliferation of these factors in hospitals, retirement homes and other institutions. This work explores the development and application of a novel class of sulfonamide-based quaternary ammonium antimicrobial coatings, anchored to commercially and clinically relevant material surfaces. Synthesized in high yields (60–97%), benzophenone-anchored antimicrobials were spray-coated and UV grafted onto plastic surfaces, while silane-anchored variants were adhered to select textiles via dip-coating. Surface modified samples were characterised by advancing contact angle, anionic dye staining, X-ray photoelectron spectroscopy and atomic force microscopy. After verifying coating quality through the above characterization methods, microbiological testing was performed on batch samples in conditions that simulate the natural inoculation of surfaces and objects (solid/air) and water containers (solid/liquid). Using the previously established Large Drop Inoculum (LDI) protocol at solid/air interfaces, all treated samples showed a full reduction (105–107 CFU) of viable Arthrobacter sp., S. aureus, and E. coli after 3 h of contact time. Additional testing of the walls of plastic LDPE vials treated with a UV-cured sulfonamide antimicrobial at a solid/liquid interface using the newly developed Large Reservoir Inoculum (LRI) protocol under static conditions revealed a complete kill (>106 reduction) of Gram-positive Arthrobacter sp., and a partial kill (>104 reduction) of Gram-negative E. coli within 24–48 h of contact.