${session.getAttribute("locale")} 5 The zonation of coastal dune plants in relation to sand burial, resource availability and physiological adaptation Wed 12 May 2021 23:59:16 SAST ]]> Thermal, spectroscopic and x-ray diffraction studies of copper(II) 1,2,4,5-Benzenetetracarboxylates and copper(II) oxalate a study of metal-organic frameworks Wed 12 May 2021 23:17:08 SAST ]]> A case for institutional investigations in economic research methods with reference to South Africa's agricultural sector Wed 12 May 2021 23:09:31 SAST ]]> A bioinorganic study of some cobalt(II) Schiff base complexes of variously substituted hydroxybenzaldimines Wed 12 May 2021 23:07:36 SAST ]]> Biosorption of precious metals from synthetic and refinery wastewaters by immobilized saccharomyces cerevisiae Wed 12 May 2021 22:26:49 SAST ]]> Studies directed towards the synthesis of chromone carbaldehyde-derived HIV-1 protease inhibitors Wed 12 May 2021 22:26:11 SAST ]]> "The struggle of memory against forgetting" contemporary fictions and rewriting of histories Wed 12 May 2021 22:20:43 SAST ]]> Identification and characterization of novel oncology related platinum complexes using chromatographic and mass spectrometric techniques Wed 12 May 2021 22:19:58 SAST ]]> The separation of platinum and gold from an industrial feed solution Wed 12 May 2021 20:17:48 SAST ]]> Melatonin and anticancer therapy interactions with 5-Fluorouracil Wed 12 May 2021 19:48:45 SAST ]]> Towards understanding the mechanism of dimerisation of Saccharomyces cerevisiae eukaryotic translation initiation factor 5A Wed 12 May 2021 19:32:33 SAST ]]> Journalists' perceptions of their roles and identities with regard to the new partnership for Africa's development Wed 12 May 2021 19:09:43 SAST ]]> "A complex and delicate web" : a comparative study of selected speculative novels by Margaret Atwood, Ursula K. Le Guin, Doris Lessing and Marge Piercy Wed 12 May 2021 19:04:36 SAST ]]> The feeding and spatial ecologies of the large carnivore guild on Kwandwe Private Game Reserve Wed 12 May 2021 18:57:17 SAST ]]> An interpretive inquiry into girls' educational choices and aspirations: a case study of Murang'a district, Kenya Wed 12 May 2021 18:22:44 SAST ]]> Bioprocess development for removal of nitrogenous compounds from precious metal refinery wastewater 10,000 mg/I), numerous metals and high concentrations of those metals (> 20 mg/l of platinum group metals) in the wastewater are the main challenges for biological removal of nitrogenous compounds from PMR wastewater. Nitrogenous compounds such as NH₄⁺-N and N0₃-N are strong metal ligands, which make it difficult to recover metals from the wastewater. Therefore, a bioprocess was developed for removal of nitrogenous compounds from carefully simulated PMR wastewater. A preliminary investigation of metal wastewater was carried out to determine its composition and physico-chemical properties, the ability to nitrify and denitrify under different pH conditions and denitrification with different carbon Source compounds and amounts. Even at pH 4, nitrification could be carried out. A suitable hydraulic retention time was found to be 72 hours. There was no significant difference between sodium acetate and sodium lactate as carbon sources for denitrification. Based on these results, a reactor comparison study was carried out using simulated PMR wastewater in three types of reactors: continuously stirred tank reactor (CSTR), packed-bed reactor (PBR) and airlift suspension reactor (ALSR). These reactors were fed with 30 mg/l of Rh bound in an NH₄⁺ based compound (Claus salt: pentaaminechlororhodium (III) dichloride). Total nitrogen removal efficiencies of > 68 % , > 79 % and > 45 % were obtained in the CSTR, PBR and ALSR, respectively. Serially connected CSTR-PBR and PBR-CSTR reactor configurations were then studied to determine the best configuration for maximum removal of nitrogenous compounds from the wastewater. The PBR-CSTR configuration gave consistent biomass retention and automatic pH control in the CSTR. Ammonium removal efficiencies > 95 % were achieved in both reactors. As poor nitrate removal was observed a toxicity study was carried out using respirometry and the half saturation inhibition coefficients for Pt, Pd, Rh and Ru were found to be 15.81, 25.00, 33.34 and 39.25 mg/l, respectively. A mathematical model was developed to describe the nitrogen removal in PMR wastewater using activated sludge model number 1 (ASMl), two step nitrification and metal toxicity. An operational protocol was developed based on the literature review, experimental work and simulation results. The optimum reactor configuration under the set conditions (20 mg/I of Rh and < 100 mg/I of NH₄⁺-N) was found to be PBR-CSTR-PBR process, which achieved overall NH₄⁺-N and N0₃⁻-N removal efficiencies of > 90 % and 95 %, respectively. Finally, a rudimentary microbial characterisation was carried out on subsamples from the CSTR and PBRsecondary. It was found that the CSTR biomass consisted of both rods and cocci while PBRsecondary consisted of rods only. Based on these experimental works, further research needs and recommendations were made for optimisation of the developed bioprocess for removal of nitrogenous compounds from PMR wastewater.]]> Wed 12 May 2021 18:01:58 SAST ]]> The solvent-free approach versus the use of ionic liquids in the synthesis of ferrocenes Wed 12 May 2021 17:59:22 SAST ]]> South Africa and Malaysia: identity and history in South-South relations Wed 12 May 2021 17:54:35 SAST ]]> An adaptive approach for optimized opportunistic routing over Delay Tolerant Mobile Ad hoc Networks Wed 12 May 2021 17:37:46 SAST ]]> The impact of the identification process and the corporate social responsibility process on the effectiveness of multi-racial advertising in South Africa Wed 12 May 2021 17:28:54 SAST ]]> Fungal remediation of winery and distillery wastewaters using Trametes pubescens MB 89 and the enhanced production of a high-value enzyme therein Wed 12 May 2021 17:27:51 SAST ]]> The role of discourse in the constitution of radiographic knowledge: a critical realist account Wed 12 May 2021 17:15:03 SAST ]]> A stable isotope approach to trophic ecology resolving food webs in intertidal ecosystems Wed 12 May 2021 17:13:36 SAST ]]> Application of dermal microdialysis and tape stripping methods to determine the bioavailability and/or bioequivalence of topical ketoprofen formulations Wed 12 May 2021 16:50:45 SAST ]]> Reconstructing ionospheric TEC over South Africa using signals from a regional GPS network Wed 12 May 2021 16:48:40 SAST ]]> Studies in marine diterpene chemistry Wed 12 May 2021 16:47:09 SAST ]]> South African public private partnership (PPP) projects Wed 12 May 2021 16:32:25 SAST ]]> The rhizosphere as a bioprocess environment for the bioconversion of hard coal Wed 12 May 2021 16:20:08 SAST ]]> Science teachers' transformative and continuous professional development : a journey towards capacity-building and reflexive practice Thu 13 May 2021 12:10:01 SAST ]]> Effects of coastal topography on physiology, behaviour and genetics of indigenous (Perna perna) and invasive (Mytilus galloprovincialis) mussels Thu 13 May 2021 07:22:04 SAST ]]> The ecology and conservation of Mackinder's eagle owls (Bubo capensis mackinderi) in central Kenya in relation to agricultural land-use and cultural attitudes Thu 13 May 2021 07:07:20 SAST ]]> Plant aphid interactions : effects of diuraphis noxia and rhopalosiphum padi on the structure and function of the transport systems of leaves of wheat and barley Thu 13 May 2021 06:35:28 SAST ]]> Purification, characterisation and application of inulinase and transferase enzymes in the production of fructose and oligosaccharides Thu 13 May 2021 06:32:05 SAST ]]> Synthetic, spectrometric and computer modelling studies of novel ATP analogues Thu 13 May 2021 06:22:18 SAST ]]> Development of a novel in situ CPRG-based biosensor and bioprobe for monitoring coliform β-D-Galactosidase in water polluted by faecal matter Thu 13 May 2021 06:01:30 SAST ]]> Solar cycle effects on GNSS-derived ionospheric total electron content observed over Southern Africa Thu 13 May 2021 05:54:01 SAST ]]> Floating sulphur biofilms structure, function and biotechnology Thu 13 May 2021 05:51:33 SAST ]]> Changing words and worlds?: a phenomenological study of the acquisition of an academic literacy Thu 13 May 2021 05:38:28 SAST ]]> Queens, pseudoqueens and laying workers reproductive competition in the Cape Honeybee (Apis mellifera capensis Eschscholtz) Thu 13 May 2021 05:15:23 SAST ]]> Information technology support for transformation in higher educational institutions in South Africa Thu 13 May 2021 05:09:19 SAST ]]> ATP mimics as glutamine synthetase inhibitors : an exploratory synthetic study Thu 13 May 2021 05:07:50 SAST ]]> Novel aspects of platinum-amine coordination compounds: their chemistry and anticancer application Thu 13 May 2021 05:01:05 SAST ]]> Towards the bioremediation of the hypertrophic Swartkops Solar Salt-works Thu 13 May 2021 04:26:18 SAST ]]> Camphor derivatives in asymmetric synthesis: a synthetic, mechanistic and theoretical study Thu 13 May 2021 04:19:31 SAST ]]> Managing conflict across cultures, values and identities: a case study in the South African automotive industry Thu 13 May 2021 04:05:58 SAST ]]> Molecular characterization of the Hsp70/Hsp90 organizing protein (Hop) phosphorylation, subcellular localization and interaction with Hsp90 Thu 13 May 2021 03:32:29 SAST ]]> Novel camphor derivatives as potential asymmetric alkylation auxiliaries Thu 13 May 2021 03:30:44 SAST ]]> Effects of temperature on the development, behaviour and geography of blowflies in a forensic context Thu 13 May 2021 03:30:02 SAST ]]> The effects of elephants at low densities and after short occupation time on the ecosystems of the Eastern Cape Province, South Africa Thu 13 May 2021 02:40:27 SAST ]]> Assembly of Omegatetravirus virus-like particles in the yeast Saccharomyces cerevisiae Thu 13 May 2021 01:44:19 SAST ]]> On the optical characterization of photovoltaic devices Thu 13 May 2021 01:07:53 SAST ]]> Harvesting strategies of fuelwood and kraalwood users at Machibi : identifying the driving factors and feedbacks Thu 13 May 2021 00:31:56 SAST ]]> Phytoplankton chlorophyll a concentration and community structure in two temporarily open/closed estuaries in the Eastern Cape, South Africa 20 μm) accounted for > 65 percent of the Chl a, whereas during closed mouth conditions they accounted for about 55 percent of the Chl a biomass. Chlorophytes became the dominant taxon in the dry summer months but were replaced by cryptophytes and dinoflagellates during the wet season. When nutrient concentrations were low during low flow conditions in the Van Stadens Estuary mixotrophic microphytoplankton became an important fraction of the water column together with phototrophic dinoflagellates and cryptophytes. In the Maitland large sized chlorophytes were the dominant taxa in late spring and summer seasons and made up more than 80 percent of the cell numbers. In the Maitland before the floods in 2002 cyanophytes were the dominant group in late spring contributing more than 75 percent in cell abundance. Data from the short-term study in the Van Stadens Estuary showed similarities and differences in the Chl a response to increased river inflow. High river inflow initially reduced Chl a biomass followed by a recovery period of a couple of days compared to a 8 – 10 week recovery period in studies monitored over seasonal and annual temporal scales. The responses may be dissimilar but help to illustrate that there are similar response patterns to environmental forcing necessary to support phytoplankton biomass at different temporal scales. This study has demonstrated that flooding events caused by strong river flow cause breaching of the mouth, a reduction in salinity and marked nutrient input. Although the causes of flooding can be similar in both estuaries the resultant effects are varied and can alter the ability of the estuary to retain water. This study was able to demonstrate that the supply of macronutrients from the catchment was strongly correlated with rainfall (R2 = 0.67) and that phytoplankton growth mainly depended on an allochthonous source of macronutrients although internal supplies could be critical at times in controlling microalgal biomass.]]> Thu 13 May 2021 00:22:20 SAST ]]>