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Open Access
A seeded ambient temperature ferrit process for the treatment of AMD waters: Magnetite formation in the presence and absence of calcium ions under steady state operation
(2003) Morgan, B E; Lahav, O; Hearne, G; Loewenthal, R E
An ambient temperature ferrite process has been developed for the removal of iron and non-ferrous metals from AMD waters. The process involves the controlled formation of magnetite (Fe3 O4 ) that has the capacity to substitute divalent and trivalent cations as part of the lattice, thus forming a stable easy-to-separate ferrite. This paper reports on continuous operations of the process in the absence and presence of Ca2+, which is well known to impede ferrite formation. In the first instance, the process involves the precipitation of hydroxy-metals at pH 10.5 and their subsequent adsorption onto magnetite seed in a contact stabilisation reactor. Second, liquid-solid separation is effected and the solid fraction is subsequently treated in an oxidising reactor in which a fraction of the ferrous species is oxidised to an intermediate ferric precipitate. Finally, both ferrous and ferric species undergo crystalchemical processing and are incorporated into stable magnetite. Results indicate that Ca2+ interference can be overcome by maintaining a high ratio of precipitated ferrous species to dissolved Ca2+. It was found that in order to attain the required high Fe2+:Ca2+ ratio, the solid ferrous-hydroxy species concentration in the oxidation reactor should be maintained at above 1 200 mg Fe/l. Ferrous to calcium ratios greater than 3 were found to favour magnetite formation. In the absence of Ca2+, a solid ferroushydroxy species concentration of approximately 500 mg/l was sufficient for magnetite formation. Operating the process at ferroushydroxy concentrations of lower than 1 200 and 500 mg/l in the presence and absence of calcium respectively enhanced the formation of other iron oxides, primarily goethite. In all experiments the iron concentration in the effluent was less than 1 mg/l, the sludge volume index (SVI) extremely low (< 4 ml/g) and the percentage of ferrous-hydroxy species in the sludge can be reduced to about 1%. These features, together with the potential to incorporate heavy metals into a stable compound, make the process very promising for AMD treatment.
Open Access
African penguins Spheniscus demersus recolonise a formerly abandoned nesting locality in Namibia
(2003) Roux, J-P; Kemper, J; Bartlett, P A; Dyer, B M; Dundee, B L
African Penguins Spheniscus demersus disappeared from Neglectus Islet probably between 1885 and 1952. Visiting birds were only noted rarely before the mid 1990s, but since 1995 penguin numbers on the islet have increased and breeding was first confirmed in 2001. Neglectus Islet is the only formerly abandoned nesting locality to be recolonised by African Penguins in Namibia. Although the population is still very small (estimated at around 11 breeding pairs), the re-establishment of this breeding locality is important for the conservation of the African Penguin, which is considered to be Critically Endangered in Namibia.
Open Access
Beyond the Brother: Radical Freedom
(2008) Barnard-Naude, A J
In his decision in Ferreira v Levin NO, Justice Ackermann - inspired by Berlin - appears to favour the negative conception of freedom. Yet at the same time Ackermann insists that 'a broad and generous interpretation of freedom does not deny or preclude the constitutionally valid, and indeed essential, role of state intervention in the economic as well as the civil and political spheres.'
Open Access
Conflict reduction in cross-functional projects in South African automotive firms
(2008) Mueller, T; Parker, H; Ross, A
Purpose: The purpose of this article is to explore whether certain organisational control mechanisms can reduce conflict associated with cross-functional projects. Methodology: This is an exploratory study and individuals who had recently engaged in a cross-functional process improvement or change implementation project at automotives firm in South Africa were surveyed. The information collected from the survey was analysed using exploratory factor analysis and correlation analysis. Findings: The results of this study indicate that of the three control mechanisms examined, formalisation in project structure had the strongest association with a reduction in conflict. Reward systems that reward both the team as well as the individual were also found to have a significant association with a reduction in conflict. Use of performance measurement systems aimed at achieving strategic alignment did not have an association with conflict reduction in the organisation. Implications: These findings yield the following implications for management practice. Firstly managers need to be conscious that initiatives such as process improvement projects that require individuals from different functions to work together can often result in conflict. Secondly, this conflict can be reduced by formalizing roles and responsibilities and decreasing ambiguity in the project. Thirdly, design of reward systems that incentivise both the cross-functional team as well as the individual can also help to reduce conflict. Contribution and value: This study has shed light on the role of certain organisational control mechanisms on reducing conflict associated with cross-functional projects. It has also contributed to our understanding of how formalisation in project structure influences conflict in comparison to how performance measurement and reward systems influence conflict.
Open Access
Dignity and the Political Right to Freedom
(2008) Fagan, Anton
In the case of Ferreira v Levin NO, Justice Laurie Ackermann seemed to make the assumption that the political right to freedom is best explained, and its content therefore best determined, by the fact that all human beings have dignity. That is, he seemed to assume that dignity and the fact that human beings necessarily possess it provide the key to an understanding of the political right to freedom. This is, I think, an assumption made by many. The aim of this essay is to question its validity.
Open Access
Fullscale implementation of external nitrification biological nutrient removal in the Daspoort Water Care Works
(2004) Muller, A W; Wentzel, M C; Saayman, G B; Van de Merwe, S A; Esterhuyse, C M; Snyman, J S; Ekama, G A
In the external nitrification (EN) biological nutrient removal (BNR) activated sludge (AS) system, the nitrification process is removed from the main BNRAS system to a fixed media system external to the AS system (Hu et al., 2003). The ENBNRAS system provides considerable advantages over the conventional BNRAS system, e.g. reduced bioreactor volumes, secondary settling tank surface area and oxygen demand. Further, the ENBNRAS system provides opportunity for substantial system intensification. The performance and characterization of the ENBNRAS system has been successfully demonstrated at lab-scale (Hu et al., 2000, Sötemann et al., 2002), but has not yet been tested in full-scale implementation. In collaboration between the City of Tshwane Metropolitan Municipality (CTMM) and the University of Cape Town, ENBNR activated sludge is being implemented at fullscale at the Daspoort Waste Water Treatment Works (DWWTW) in Central Pretoria, South Africa. This paper describes the preliminary design of this full-scale plant and initial implementation.
Open Access
Growth and life habits of the Triassic cynodont Trirachodon, inferred from bone histology
(2004) Botha, Jennifer; Chinsamy, Anusuya
Growth pattern and lifestyle habits of the Triassic non−mammalian cynodont Trirachodon are deduced from bone histol−ogy and cross−sectional geometry. Several skeletal elements of Trirachodon were examined in order to document histological changes during ontogeny, as well as histovariability in the skeleton. The bone histology of all the elements consists of a moderately vascularized, periodically interrupted, fibro−lamellar bone tissue. This suggests that the overall growth of Trirachodon was probably rapid during the favourable season, but decreased or ceased during the unfavourable season. As the environment is thought to have been semi−arid with seasonal rainfall, it is possible that Trirachodon was sensitive to such environmental fluctuations. Some inter−elemental histovariability was noted where the number and prominence of growth rings varied. Limb bone cross−sectional geometry revealed a relatively thick bone wall and sup−ports earlier proposals that Trirachodon was fossorial.
Open Access
Knowledge and attitudes in the rural Western Cape towards pesticides in water sources
(2004) Dalvie, Mohamed A; London, Leslie; Mbuli, Simphiwe; Cairncross, Eugene
There is a need for pesticide water monitoring in South Africa and for community awareness with regard to chemical contamination of rural water sources. The results of two descriptive studies in the rural Western Cape are reported. One assessed water usage and the knowledge, attitudes and practices in relation to water of farm residents (229 participants from 60 farms) in the Slanghoek Valley, Hex River Valley and Grabouw (KAP) and the other (monitoring capacity survey), investigated water usage and the capacities of rural communities (63 farm residents from 16 farms in three local authorities and 8 environmental health officers (EHOs) from 7 local authorities) to conduct monitoring of pesticides in rural water sources. Most farm residents in both surveys identified protected sources such as groundwater from springs and boreholes (30 to 60%), and water from mountain dams (40 to 65%), as the most important sources for drinking and other domestic purposes. Many (> 40%), however, also reported farm dams. For use in the field (both drinking and other), potentially contaminated sources (river, subsurface drains, dams) were more frequently reported. Forty-eight percent of participants also reported swimming in farm dams. Other water sources reported included municipal, rain and canal water. In the monitoring capacity survey, 27 % reported using untapped water. About a third of respondents in the KAP survey reported living within 10 m of the nearest site of spraying and many used pesticides at home for pest control (41%) and in the garden (33%). While almost all participants (> 90%) in both surveys were aware that pesticides and polluted water could be harmful, many did not identify health effects (20%) especially chronic effects (91%) or reported no training (37%) in health effects. In all 7 districts surveyed in the monitoring capacity survey, water sources on farms are tested by EHOs. Only 3 (37%) respondents felt that there were enough persons conducting water monitoring in their area. Only 1 respondent reported that pesticides were monitored, and only in request to a complaint. Three state laboratories, that did not have the analytical capacity to conduct routine pesticide water monitoring at low (< 0.1 mg/l) detection limits, were identified as conducting water analyses. The study found that farm residents in the Western Cape are potentially exposed to pesticides through various environmental routes including water. This emphasises the need to monitor water for pesticides in the Western Cape, but in order to do this, human and laboratory resources and capacities to conduct routine pesticide water monitoring need to be increased.
Open Access
Modelling organic material in activated sludge systems
(2004) Ekama, G A; Wentzel, M C
A simple predictive model for the activated sludge reactor inorganic suspended solids (ISS) concentration is presented. It is based on the accumulation of influent ISS in the reactor and an ordinary heterotrophic organism (OHO) ISS content (fiOHO) of 0.15 mg ISS/mgOHOVSS and a variable phosphate accumulating organism (PAO) ISS content (fiPAO) proportional to their P content (fXBGP). The model is validated with data from 21 investigations conducted over the past 15 years on 30 aerobic and anoxic-aerobic nitrification denitrification (ND) systems and 18 anaerobic-anoxic-aerobic ND biological excess P removal (BEPR) systems variously fed artificial and real wastewater and operated from 3 to 20 d sludge age. The predicted reactor VSS/TSS ratio reflects the observed relative sensitivity to sludge age, which is low, and to BEPR, which is high. For effective use of the model for design, two significant issues require attention: measurement of the influent ISS concentration, which is not commonly done in wastewater characterisation analyses; and estimating a priori the P content of PAOs (fXBGP), which can vary considerably depending on the extent of anoxic P uptake BEPR that takes place in the system. Some guidance on selection of the mixed liquor VSS/TSS ratio for design is given.
Open Access
Peer assessment: A complementary instrument to recognise individual contributions in IS student group projects
(2005) Scott, Elsje; van der Merwe, Nata; Smith, Derek
This paper discusses peer assessment as a component of the assessment strategy used for Information Systems student group projects at a South African university. The value of peer assessment and the contribution to the real-life experience offered by group projects, will be discussed. It will also illustrate how this process adds value by enhancing deep learning. Its value as a complementary assessment instrument in a multiple assessment strategy and how the results of peer assessment are used to recognise individual contributions to group performance will be illustrated. The use of peer assessment as an instrument for both informal formative assessment and formal summative assessment will be described. To perform the peer assessment specific instruments were designed and used throughout the lifecycle of the course.
Open Access
Strangeness excitation functions and transition from baryonic to mesonic freeze-out
(2009) Cleymans, Jean; Oeschler, Helmut; Redlich, Krzysztof; Wheaton, Spencer
The sharp peak in the K+/π+ ratio in relativistic heavy-ion collisions is discussed in the framework of the Statistical Model. In this model a rapid change is expected as the hadronic gas undergoes a transition from a baryon-dominated to a meson-dominated gas. The maximum in the Λ/π ratio is well reproduced by the Statistical Model, but the change in the K+/π+ ratio is somewhat less pronounced than the one observed by the NA49 collaboration. The calculated smooth increase of the K−/π− ratio and the shape of the Ξ−/π+ and Ω−/π+ ratios exhibiting maxima at different incident energies is consistent with the presently available experimental data. We conclude that the measured particle ratios with 20 − 30% deviations agree with a hadronic freeze-out scenario. These deviations seem to occur just in the transition from baryon-dominated to meson-dominated freeze-out.
Open Access
Technology in neurology
(2003) Lee Pan, Edward B
Promising developments in clinical neurophysiology over the last 10 years have been largely eclipsed by the dramatic evolution of magnetic resonance imaging (MRI). One exception has been encephalography (video EEG) monitoring and, of course, research in clinical neurophysiology knows no bounds. Neurosurgery has had major developments and some of these areas have involved neurophysiological co-operation such as neurophysiological sampling and stimulation in extrapyramidal movement disorders, especially Parkinson's disease. Overall, as in the rest of medical technology, digitisation and computerisation have gradually replaced all analogue systems and as the industry matured, many proprietary systems have migrated to commercial standards, particularly versions of the Windows operating systems. This development in technology has had tangible benefits in overlap with office software, ease of handling large amounts of data and increasing confidence in improved reliability and manipulation of signals. However, this technological benefit is a double-edged sword and apart from the more familiar problems common to many small computer systems, digital systems are capable of distorting or hiding signals without the unwary operator being aware of this. An example would be suspicious looking 'sharp waves' (potentially epileptogenic) on the EEG, which are the result of a noisy (bad) signal unwittingly being filtered by innocuous sounding switches ('muscle filters'). Despite the advanced technology, basic principles of a clean source of signal are still essential. Neurophysiological studies have not been exclusive to neurology and with important developments in cardiology and anaesthetics, there is greater overlap in some of the technology underlying these fields. At the same time, there has been a move to train clinical technologists who are capable of moving between even more disparate fields such as renal (dialysis) to respiratory (lung functions) to neurology. Unfortunately, the numbers of clinical technologists' posts, and hence members, have dropped significantly and such developments may be more necessary than originally planned.The training centres for clinical technology have also been drastically reduced, further hampering new recruits.
Open Access
The measurement and reduction of urban litter entering stormwater drainage systems: Paper 2 - Strategies for reducing the litter in stormwater drainage systems
(2004) Marais, Mark; Armitage, Neil
A previous South African study looked at the removal of litter from the drainage systems once it was already there. Yet the litter problem cannot be addressed in an effective and sustainable manner without an effective integrated catchmentwide litter management strategy. This strategy should include planning controls, source controls, and structural controls. The main focus of this paper is the source control of urban litter. It reviews international and local practice, and reports on the results of a two-year monitoring programme conducted in nine pilot catchments covering a range of different land uses, socio-economic levels and population densities in the City of Cape Town. It proposes preliminary guidelines for the reduction of urban litter loads entering the drainage system by dealing with litter pollution at its source.

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