Articoli di riviste: "Flotation – South Africa"

1

Haarhoff, Johannes, e Lucas R. J. van Vuuren. "Design parameters for dissolved air flotation in South Africa". Water Science and Technology 31, n. 3-4 (1 febbraio 1995): 203–12. http://dx.doi.org/10.2166/wst.1995.0530.

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Dissolved air flotation has been used in South Africa for more than 25 years in the field of water and waste-water treatment, with practically all the development and verification done locally. This substantial body of knowledge and experience was recently condensed into a document titled A South African Design Guide for Dissolved Air Flotation. A general literature survey was combined with a detailed survey of 26 dissolved air flotation plants operating in Southern Africa, to arrive at suggested design parameters. Two broad categories of applications were covered in the guidelines - those of water clarification, and of activated sludge thickening. A clear trend emerged from the data collected. Drinking water clarification plants were generally designed within a fairly narrow range of the most design parameters, and the perception of operators and managers was that these clarification plants performed very efficiently. Sludge thickening plants, on the other hand, showed considerable variability in terms of most design parameters, and the general perception of its efficiency consequently varied from highly positive to negative. The paper includes summaries of the ranges of the actually surveyed design parameters, the suggested design values and a comparison with typical design values available from other countries.

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Afolabi, Ayo Samuel, Ambali Saka Abdulkareem e Edison Muzenda. "Effect of Flotation Parameters on Recovery of South Africa Nickel Sulphide Ore". Applied Mechanics and Materials 260-261 (dicembre 2012): 961–68. http://dx.doi.org/10.4028/www.scientific.net/amm.260-261.961.

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This study investigated the effects of flotation parameters on the recovery of low grade nickel sulphide ore. The parameters investigated are the particle size, flotation time, temperature and pH of the pulp. The analyses of the results obtained showed that particle size, pH, and flotation time had significant effects on the recovery of nickel sulphide ore. The particle size distribution showed that the breakage rate increased in coarse particles and decreased with reduction in particle size. The optimum particle size was found to be 87% passing 75 µm with the highest nickel recovery of 35% at 15 minutes while 68, 79, and 97% passing 75 µm produced nickel recovery of 15, 20 and 16% respectively. The maximum nickel recovery of 35% was achieved at pH of 10.5 which indicated that the nickel sulphide ore has good floatability at alkaline pH range. It was also observed that the recovery of nickel increased with flotation time and the highest recovery was obtained at flotation time of 15 minutes.

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O'Connor, C. T., e R. C. Dunne. "The practice of pyrite flotation in South Africa and Australia". Minerals Engineering 4, n. 7-11 (gennaio 1991): 1057–69. http://dx.doi.org/10.1016/0892-6875(91)90083-8.

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4

Officer, J., J. A. Ostrowski e P. J. Woollard. "The design and operation of conventional and novel flotation systems on a number of impounded water types". Water Supply 1, n. 1 (1 gennaio 2001): 63–69. http://dx.doi.org/10.2166/ws.2001.0008.

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This paper describes the design of conventional Dissolved Air Flotation (DAF) systems, and the novel Counter Current Dissolved Air Flotation Filtration (COCODAFF®) process. The operation and performance of these plants on a variety of water types in the United Kingdom and South Africa is also described. The advantages of flotation processes for the treatment of impounded waters either high in colour, or with a high concentration of algae, is discussed. Other topics covered in this paper are hydraulic flocculation, and the application of Finite Element Analysis (FEA), to the design of flotation plants. It is concluded that the COCODAFF® process offers a number of advantages over conventional DAF systems.

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5

Aleksandrova, Tatyana, e Cyril О’Connor. "Processing of platinum group metal ores in Russia and South Africa: current state and prospects". Journal of Mining Institute 244 (30 luglio 2020): 462–73. http://dx.doi.org/10.31897/pmi.2020.4.9.

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The presented study is devoted to a comparative review of the mineral raw material base of platinum group metals (PGMs) and technologies of their processing in South Africa and Russia, the largest PGM producers. Mineralogical and geochemical classification and industrial value of iron-platinum and platinum-bearing deposits are presented in this work. The paper also reviews types of PGM ore body occurrences, ore processing methods (with a special focus on flotation processes), as well as difficulties encountered by enterprises at the processing stage, as they increase recovery of the valuable components. Data on mineralogical features of PGM deposits, including the distribution of elements in the ores, are provided. The main lines of research on mineralogical features and processing of raw materials of various genesis are identified and validated. Sulfide deposits are found to be of the highest industrial value in both countries. Such unconventional PGM sources, as black shale, dunites, chromite, low-sulfide, chromium and titanomagnetite ores, anthropogenic raw materials, etc. are considered. The main lines of research that would bring into processing non-conventional metal sources are substantiated. Analysis of new processing and metallurgical methods of PGM recovery from non-conventional and industrial raw materials is conducted; the review of existing processing technologies for platinum-bearing raw materials is carried out. Technologies that utilize modern equipment for ultrafine grinding are considered, as well as existing reagents for flotation recovery; evaluation of their selectivity in relation to platinum minerals is presented. Basing on the analysis of main technological processes of PGM ore treatment, the most efficient schemes are identified, i.e.,gravity and flotation treatment with subsequent metallurgical processing.

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Dzvinamurungu, Thomas, Derek Hugh Rose, Karel Stephanus Viljoen e Antoine Floribert Mulaba-Bafubiandi. "A Process Mineralogical Evaluation of Chromite at the Nkomati Nickel Mine, Uitkomst Complex, South Africa". Minerals 10, n. 8 (12 agosto 2020): 709. http://dx.doi.org/10.3390/min10080709.

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A process mineralogical study based on three texturally and mineralogically different chromite-bearing ore types at the Nkomati nickel mine was undertaken, with focus on chromite. Chromite is a by-product of the Ni-Cu-Co-PGE ore at Nkomati Nickel mine. These being the PCMZ_MG (medium-grade Ni-Cu sulphide silicate ore with disseminated chromite), PCMZ_HG (high-grade Ni-Cu sulphide silicate ore containing disseminated chromite) and MCHR (massive chromite unit) ore types. These were processed using benchtop flotation followed by gravity concentration using a shaking table at different grind sizes. Quantitative mineralogical data was obtained using a 600F Mineral Liberation Analyser for the unprocessed and processed ores at three selected target grinds. The Mineral Liberation Analyser data indicated that increased milling does not relate to increased chromite grades and recoveries, particularly for the disseminated PCMZ type ores based on laboratory-scale gravity concentration. The recovery is controlled largely by the chromite chemistry. The results also showed that the MCHR samples that underwent a pre-flotation stage before gravity separation had better Cr2O3 grades (45% to 47%) and recoveries (52% to 61%) than MCHR ore that did not undergo a pre-flotation stage, which recorded grades ranging from 44% to 46% and recoveries ranging from 43% to 60%. This holds promise for the blending of MCHR ores with the PCMZ ores. The PCMZ ores also displayed better Cr2O3 grades and recoveries at coarser grinds. The optimal target grind to process all three ore types is a P80 of 75 μm, which is the current grind size employed at Nkomati Nickel mine. Due to the low nickel price and grade the Nkomati Nickel mine is currently under care and maintenance.

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Mhonde, Ngoni, Mariette Smart, Kirsten Corin e Nora Schreithofer. "Investigating the Electrochemical Interaction of a Thiol Collector with Chalcopyrite and Galena in the Presence of a Mixed Microbial Community". Minerals 10, n. 6 (19 giugno 2020): 553. http://dx.doi.org/10.3390/min10060553.

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High microbial cell counts have been recorded in sewage waters employed as process water in mineral beneficiation plants across the world. The presence of these microbes can negatively impact flotation performance through mineral passivation, although some microbes improve flotation performance as investigated in various bio-flotation studies. The current study aims to understand the electrochemical behaviour of minerals in the presence of a sodium ethyl xanthate (SEX) collector and microbes originating from a sulphide ore processing plant in South Africa. The electrochemical response was correlated to observe flotation performance. Mixed potential measurements were conducted in parallel to microflotation tests, to assess the hydrophilicity or hydrophobicity induced on sulphide minerals adapted to microbe-laden synthetic plant water. Sulphide minerals’ mixed potentials and interactions of SEX with sulphide minerals were dramatically reduced in the presence of the mixed microbial community (MMC). The observations were correlated with poor flotation efficacy noted in microflotation tests. These fundamental results shed light on how the adsorption of thiol collectors on sulphide minerals is adversely affected by microbes, prompting a discussion on flotation process monitoring when mineral beneficiation is conducted using microbe-laden water.

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8

O’Connor, Cyril, e Tatiana Alexandrova. "The Geological Occurrence, Mineralogy, and Processing by Flotation of Platinum Group Minerals (PGMs) in South Africa and Russia". Minerals 11, n. 1 (7 gennaio 2021): 54. http://dx.doi.org/10.3390/min11010054.

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Russia and South Africa are the world’s leading producers of platinum group elements (PGEs). This places them in a unique position regarding the supply of these two key industrial commodities. The purpose of this paper is to provide a comparative high-level overview of aspects of the geological occurrence, mineralogy, and processing by flotation of the platinum group minerals (PGMs) found in each country. A summary of some of the major challenges faced in each country in terms of the concentration of the ores by flotation is presented alongside the opportunities that exist to increase the production of the respective metals. These include the more efficient recovery of minerals such as arsenides and tellurides, the management of siliceous gangue and chromite in the processing of these ores, and, especially in Russia, the development of novel processing routes to recover PGEs from relatively low grade ores occurring in dunites, black shale ores and in vanadium-iron-titanium-sulphide oxide formations.

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O’Connor, Cyril, e Tatiana Alexandrova. "The Geological Occurrence, Mineralogy, and Processing by Flotation of Platinum Group Minerals (PGMs) in South Africa and Russia". Minerals 11, n. 1 (7 gennaio 2021): 54. http://dx.doi.org/10.3390/min11010054.

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Abstract (sommario):

Russia and South Africa are the world’s leading producers of platinum group elements (PGEs). This places them in a unique position regarding the supply of these two key industrial commodities. The purpose of this paper is to provide a comparative high-level overview of aspects of the geological occurrence, mineralogy, and processing by flotation of the platinum group minerals (PGMs) found in each country. A summary of some of the major challenges faced in each country in terms of the concentration of the ores by flotation is presented alongside the opportunities that exist to increase the production of the respective metals. These include the more efficient recovery of minerals such as arsenides and tellurides, the management of siliceous gangue and chromite in the processing of these ores, and, especially in Russia, the development of novel processing routes to recover PGEs from relatively low grade ores occurring in dunites, black shale ores and in vanadium-iron-titanium-sulphide oxide formations.

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10

Giesekke, E. W., e P. J. Harris. "The role of polyoxyethylene alkyl ethers in apatite flotation at foskor, phalaborwa (South Africa)". Minerals Engineering 7, n. 11 (novembre 1994): 1345–61. http://dx.doi.org/10.1016/0892-6875(94)00075-1.

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11

Corin, Kirsten, Belinda McFadzean, Natalie Shackleton e Cyril O’Connor. "Challenges Related to the Processing of Fines in the Recovery of Platinum Group Minerals (PGMs)". Minerals 11, n. 5 (18 maggio 2021): 533. http://dx.doi.org/10.3390/min11050533.

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In order to increase the recovery of PGMs by flotation, it is necessary to optimise the liberation of the key minerals in which the platinum group elements (PGEs) are contained which include sulphides, arsenides, tellurides, and ferroalloys among others, while at the same time ensuring the optimal depression of gangue minerals. In order to achieve this, comminution circuits usually consist of two or three stages of milling, in which the first stage is autogeneous, followed by ball milling. Further liberation is achieved in subsequent stages using ultra-fine grinding. Each comminution stage is followed by flotation in the so-called MF2 or MF3 circuits. While this staged process increases overall recoveries, overgrinding may occur, hence creating problems associated with fine particle flotation. This paper presents an overview of the mineralogy of most of the more significant PGM ores processed in South Africa and the various technologies used in comminution circuits. The paper then summarises the methodology used in flotation circuits to optimise recovery of fine particles in terms of the collectors, depressants, and frothers used. The effect of entrainment, slimes coating, changes in rheology caused by the presence of a significant amount of fines and of chromite recovery is addressed.

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12

Cowan, J. A. C., F. MacTavish, C. J. Brouckaert e E. P. Jacobs. "Membrane Treatment Strategies for Red Meat Abattoir Effluents". Water Science and Technology 25, n. 10 (1 maggio 1992): 137–48. http://dx.doi.org/10.2166/wst.1992.0243.

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In water-scarce South Africa there is pressure on water-intensive industries to conserve water, and at the same time to reduce the organic and salinity concentrations discharged in effluents back (indirectly) to the water resources. These requirements are usually contradictory: effective water conservation will generally lead to more concentrated effluents, motivating the need, in some cases, for effluent pretreatment before discharge. Wide-ranging effluent pretreatment trials have been carried out at a number of red meat abattoirs over the past few years, under funding from the Water Research Commission. Fat removal, screening and dissolved air flotation (DAF) trials have confirmed the usefulness of such processes, but results from treatment with membranes have been both exciting and promising. These treatment techniques have now been lifted from the research phase into commercial application on small scale (25 m3/d) using full size modules. The South African Abattoir Corporation, as the major representative of the industry in South Africa, has undertaken to assess the value of membrane treatment processes as a part of a number of effluent treatment strategies. This paper describes the experiences and future potential for abattoir effluent treatment by membrane processes. Ultrafiltration will consistently remove 90% COD, 85% phosphate from the effluent, and provide a relatively non-fouling feed for reverse osmosis which produces a high quality reusable water for abattoir use. Indicative costing shows the costs of membrane treatment compare favourably with anaerobic digestion as an alternative, and even to municipal effluent tariffs.

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13

Mishra, G., K. S. Viljoen e H. Mouri. "Influence of mineralogy and ore texture on pentlandite flotation at the Nkomati nickel mine, South Africa". Minerals Engineering 54 (dicembre 2013): 63–78. http://dx.doi.org/10.1016/j.mineng.2013.04.009.

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de Wet, F. J., J. L. Barnard e G. Saayman. "Baviaanspoort Wastewater Reclamation Plant". Water Science and Technology 25, n. 4-5 (1 febbraio 1992): 169–76. http://dx.doi.org/10.2166/wst.1992.0492.

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The lack of sufficient new water resources has encouraged the indirect use of wastewater in the Pretoria-Witwatersrand-Vereeniging area of South Africa with an estimated population of 8 million and which is situated at a high altitude. Effluents must comply with nitrogen and phosphate standards, as well as COD and SS. The solution was to construct a BNR plant with a follow-up of flotation to treat not only the new extensions but also the older plants for SS removal as well as for standby chemical removal of phosphates. The plant has now been in operation for a year and the results are given in the text.

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Kweinor Tetteh, Emmanuel, e Sudesh Rathilal. "Evaluating Pre- and Post-Coagulation Configuration of Dissolved Air Flotation Using Response Surface Methodology". Processes 8, n. 4 (25 marzo 2020): 383. http://dx.doi.org/10.3390/pr8040383.

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The effects of coagulation-dissolved air flotation (DAF) process configuration was studied on oil refinery wastewater. The configuration was done in two ways: acid-coagulation-DAF (pre-treatment) and acid-DAF-coagulation (post-treatment). Two different cationic and polymeric organic coagulants were employed in this study to compare their treatability performance with the two aforementioned configurations. All the coagulants applied before the DAF were found to be effective, with over 85% more contaminant removal efficiency than their post-treatment. Alum, being the most cost-effective coagulant, was then employed with response surface methodology (RSM) to obtain the optimum conditions. These include a coagulant dosage of 100 mg/L, air saturator pressure of 375 kPa and air–water ratio of 10% vol/vol corresponding to a desirability of 92% for the removal of oily pollutants from a local South Africa oil refinery’s wastewater. With the response quadratic models that were developed, the optimum conditions were tested experimentally, which were consistent with the models predicted results at a 95% confidence level.

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Maganga, Gael Darren, Linda Bohou Kombila, Larson Boundenga, Ivan Cyr Moussadji Kinga, Judicael Obame-Nkoghe, Herve Tchoffo, Oubri Bassa Gbati e Julius Awah-Ndukum. "Diversity and prevalence of gastrointestinal parasites in farmed pigs in Southeast Gabon, Central Africa". December-2019 12, n. 12 (dicembre 2019): 1888–96. http://dx.doi.org/10.14202/vetworld.2019.1888-1896.

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Background and Aim: Gastrointestinal infestations caused by intestinal parasites are the most important diseases and the most common in pigs in the tropics. These parasites are often associated with a huge economic loss. This study aimed to assess the diversity and prevalence of gastrointestinal parasites in farmed pigs from Haut-Ogooue Province, in South East Gabon. Materials and Methods: From March 2018 to July 2018, 156 samples of pig feces collected from nine different farms were analyzed under light microscopy. The identification of eggs, cysts, and oocysts in fecal samples was done using two qualitative techniques: Flotation and sedimentation. Results: After examination, the results obtained revealed an overall infestation level of 98.7% (154/156). We found ten parasite types with infestation levels that varied from species: Balantidium coli (120/156), Oesophagostomum spp. (100/156), Isospora suis (102/156), Ancylostoma spp. (17/156), Trichostrongylus spp. (28/156), Hyostrongylus spp. (13/156), Strongyloides spp. (7/156), Ascaris suum (8/156), Globocephalus spp. (1/156), and spirurida (1/156). The study of risk factors revealed that factors such as sex, age, and physiological condition may influence the diversity and level of infestation of animals by gastrointestinal parasites. Conclusion: For better prevention of parasitism in these farms, it would be interesting to implement health monitoring and to ensure good hygiene. Finally, further studies would be needed to better evaluate the distribution of these parasites in Gabon and the involvement of these animals in the transmission cycle of parasitic zoonoses.

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Ngobeni, Walter Amos, e Gregory Hangone. "The effect of using sodium di-methyl-dithiocarbamate as a co-collector with xanthates in the froth flotation of pentlandite containing ore from Nkomati mine in South Africa". Minerals Engineering 54 (dicembre 2013): 94–99. http://dx.doi.org/10.1016/j.mineng.2013.04.027.

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Fagan-Endres, Marijke A., e Susan T. L. Harrison. "South African Coal Tailings Bioflotation for Desulphurization Using Mycobacterium phlei". Solid State Phenomena 262 (agosto 2017): 613–16. http://dx.doi.org/10.4028/www.scientific.net/ssp.262.613.

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The large cost of the flotation reagents used in the first-of a two-stage desulphurization flotation process, developed for the treatment of South African waste coal ultrafine tailings, has motivated the investigation of Mycobacterium phlei as an alternative coal bioflotation reagent. Attachment experiments were used to confirm that the microbe attaches to South African coal selectively over pyrite or gangue material present in the coal. Subsequent small scale batch floats using M. phlei successfully showed that the bioflotation process can upgrade and desulphurize the coal tailings feed, and delivered approximately the same concentrate yields as the optimised chemical flotation conditions (37 – 39%). However, a projected financial feasibility analysis that assessed the incorporation of the M. phlei into the two-stage flotation process found that the bioflotation process was not profitable due to the very large flow rate of cells required (2×1016 cells/ton coal) and the associated additional equipment and growth media component costs.

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HOLT, S. T. VON, e J. P. FRANZIDIS. "Column Flotation of a South African Cooking Coal". Coal Preparation 14, n. 3-4 (gennaio 1994): 147–66. http://dx.doi.org/10.1080/07349349408905231.

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Botha, François D., e Brian Mcenaney. "Chemical Activation of a South African Coal using Phosphoric Acid". Adsorption Science & Technology 10, n. 1-4 (marzo 1993): 181–92. http://dx.doi.org/10.1177/0263617499010001-417.

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The potential of a South African coal, Bosjesspruit, as a precursor for a phosphoric acid-activated carbon has been assessed using the adsorption of nitrogen at 77 K and mercury porosimetry. Column cleaning of the coal by froth flotation reduced the ash content from 22 to 12 wt.% and caused maceral separtion, resulting in an intertinite-rich product. Reaction of the column-cleaned coal with phosphoric acid in the range 450–550°C produced an activated carbon which was dominantly microporous. The notional BET surface area of the coal reached a maximum of 600 m2/g at a reaction temperature of 550°C.

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Deglon, D. A., D. Egya-mensah e J. P. Franzidis. "Review of hydrodynamics and gas dispersion in flotation cells on South African platinum concentrators". Minerals Engineering 13, n. 3 (marzo 2000): 235–44. http://dx.doi.org/10.1016/s0892-6875(00)00003-0.

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Moimane, T. M., K. C. Corin e J. G. Wiese. "The effect of varying pulp reagent chemistry on the flotation performance of a South African PGM ore". Minerals Engineering 95 (settembre 2016): 155–60. http://dx.doi.org/10.1016/j.mineng.2016.07.002.

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Chiodza, Kudzai G., Susan T. L. Harrison e Marijke A. Fagan-Endres. "Algal Lipids as Biocollector for Recovery of Coal from Fine Coal Waste by Froth Flotation". Minerals 10, n. 1 (16 gennaio 2020): 70. http://dx.doi.org/10.3390/min10010070.

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Raw algal lipids (RALs) and their derivatives (fatty acid methyl esters; FAMEs) were investigated as biocollectors for the recovery of coal from ash-rich fine coal waste by froth flotation. Testing was done on fine coal discards from two South African sites—a high ash (50%), high sulphur (5.7%) sample and a lower ash (26%), low sulphur (0.91%) sample. The yield and recovery of combustibles on using biocollectors was similar to, or better than, with oleic acid, a polar collector demonstrated as a good collector in previous research. The RALs and FAMEs reduced the ash and sulphur content of the combustible fraction of the high ash-high sulphur sample to between 23–28% and 1.9–3.3%, respectively. The chemical modification of RALs to FAMEs provided potential for improving the selectivity of the recovery of combustibles. It also resulted in a change of the optimum operating pH, with RALs yielding better results at the natural pH of the sample (pH 2.7), while FAMEs performed best at pH 7.

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Kweinor Tetteh, E., S. Rathilal e K. Robinson. "Treatment of industrial mineral oil wastewater – effects of coagulant type and dosage". Water Practice and Technology 12, n. 1 (1 marzo 2017): 139–45. http://dx.doi.org/10.2166/wpt.2017.021.

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The use of coagulants is essential in the diverse disciplines of conventional water and wastewater treatment. This work aimed to select an economic and effective coagulant, to minimize the cost of treatment and the oil droplet content of the water, thus enhancing the efficiency of a local South African oil refinery effluent plant recovering water and oil for reuse by treating the industrial mineral oil wastewater. A standard dissolved air flotation jar test preceded evaluation of four coagulants, viz. aluminum sulfate (Alum), aluminum chloride, ferric sulfate and ferric chloride. Chemical oxygen demand, soap oil and grease, total suspended solids and turbidity were determined as water quality parameters to check coagulant efficiency. Removal of over 70% was achieved for each parameter. The results obtained at pH 5 and coagulant dose of 50 mg/L showed that alum was the best pretreatment coagulant for destabilizing and minimizing oil droplets in water, due to its trivalent cationic nature. It was also economically viable.

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"Design parameters for dissolved air flotation in South Africa". Water Science and Technology 31, n. 3-4 (1995). http://dx.doi.org/10.1016/0273-1223(95)00218-c.

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Lobetti, R. G. "Survey of the incidence, diagnosis, clinical manifestations and treatment of Spirocerca lupi in South Africa : research communication". Journal of the South African Veterinary Association 71, n. 1 (10 luglio 2000). http://dx.doi.org/10.4102/jsava.v71i1.676.

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A questionnaire survey of 716 veterinary practices was undertaken to determine the incidence of Spirocerca lupi in dogs in South Africa. In total, 49 %of the questionnaires were returned, indicating a possible incidence of 28 %. Fewer than 4 cases per year were recorded by 82 %of the respondents; 4-12 by 14 %; 12-24 by 3 %; and more than 48 by only 1 %. No seasonal incidence was reported by 48 %of the respondents. Large breeds were considered to be at greater risk by 43 % of respondents. No specific age or sex was identified to be at higher risk. The most common complaints by owners and clinical findings were vomition (46 %), weight loss (27 %), coughing (21 %) or regurgitation (20 %), although 14 %of respondents reported no abnormal clinical findings. Diagnostic methods used were radiology (74 %), endoscopy (27 %), post mortem examination (34 %) and faecal flotation (4 %). Complications associated with S. lupi were reported by 76 % of respondents, which included oesophageal neoplasia (41 %), hypertrophic osteopathy (38 %) and acute haemothorax (30 %). Specific treatments were used by 58 % of the respondents, whereas 42 % of the respondents either used no treatment (72 %) or recommended euthanasia (28 %). Of the treatment group, 52 % used ivermectin, 27 % doramectin, 13 % other deworming drugs (benzimidazoles, nitroscanate), and 8 % used disophenol. Sixty-three percent of the respondents considered their treatment ineffective, whereas 31 % considered it effective, and 6 % were unsure. The overall mortality rate was high.

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Lobetti, Remo. "Follow-up survey of the prevalence, diagnosis, clinical manifestations and treatment of Spirocerca lupi in South Africa". Journal of the South African Veterinary Association 85, n. 1 (24 febbraio 2014). http://dx.doi.org/10.4102/jsava.v85i1.1169.

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Spirocercosis is an important disease in South Africa. The object of this study was to determine if there had been a change in the prevalence, clinical manifestations and treatment of Spirocerca lupi over a 14-year period. A questionnaire was sent to 577 veterinary practices throughout South Africa in 2012. Of responders, 76% indicated that S. lupi occurred in their area, whilst 24% indicated that it did not; 84% considered S. lupi not to be a new phenomenon, whereas 16% considered it to be new. Monthly or seasonal distribution of the disease was not reported, and 76% of responders reported it to occur in no specific breed of dog, whereas 24% reported a breed risk, most considering large breeds to be at greater risk. No specific age or sex was identified as at higher risk. Common owner complaints were vomiting, weight loss, cough, or regurgitation. Reported clinical findings tended to mirror the clinical signs reported by owners. Most common diagnostic methods used were radiology, endoscopy, faecal flotation, and post mortem examination. Forty-four percent did not report seeing asymptomatic cases, 40% reported asymptomatic cases and 16% did not know. Associated complications were reported by 85% of responders, and included oesophageal neoplasia, hypertrophic osteopathy and acute haemothorax. Four different drugs were used as therapy: doramectin, ivermectin, milbemycin and Advocate®, with 9% of the responders using a combination of these four; 85% considered treatment to be effective and 15% ineffective. Treatment was considered more effective if the disease was diagnosed early and there were no complications. Two important conclusions were that more cases are being seen and that efficacy of therapy has increased, with a decrease in the mortality rate.

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Janse van Rensburg, Shalene, Sandra Barnard e Marina Krüger. "The feasibility of wastewater recycling that includes residue from dissolved air flotation within a drinking water treatment plant: case study of Midvaal Water Company, South Africa". Water SA 45, n. 3 July (31 luglio 2019). http://dx.doi.org/10.17159/wsa/2019.v45.i3.6732.

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When purifying water for potable use, wastewater is generated, due to the class of the water treatment plant and the quality of the source water. Midvaal Water Company recycled wastewater that included residue from the dissolved air flotation (DAF), sedimentation and filtration processes in an attempt to save water and reduce costs. The aim of this study was to determine functionality and water quality of such a wastewater recycling system. Samples were collected for analysis, at the sections that contributed to the total wastewater system as well as after various treatment processes. The water quality of these samples was determined, as well as the incidences of water quality failures of the final water, to establish whether the recycle stream that enters the plant together with the source water had any impact on the water quality after the different treatment processes. Data were grouped into periods prior to, during and after recycling to enable comparisons. The water quality of the recycle stream was poorer than that of the source water from the Vaal River with regard to the mean values for total chlorophyll, suspended solids, turbidity and dissolved organic carbon, but the sedimentation process of the wastewater system improved the wastewater quality by drastically reducing total chlorophyll, suspended solids and turbidity. The risk-defined compliance for the final water was excellent (≥95%), despite aluminium, turbidity and total chlorophyll failures of the final water quality during the recycling period. Total chlorophyll was identified as the largest risk during wastewater recycling, especially after the filtration process. It is evident from the data that wastewater recycling, which included wastewater from the DAF, into the main inlet stream of the water treatment plant proved to be effective, based on compliance with national legislation, and had no detrimental impact on overall treatment processes or final water quality.

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Tetteh, E. Kweinor, e S. Rathilal. "Effects of a polymeric organic coagulant for industrial mineral oil wastewater treatment using response surface methodology (RSM)". Water SA 44, n. 2 April (25 aprile 2018). http://dx.doi.org/10.4314/wsa.v44i2.02.

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Abstract (sommario):

In this study, treatment of a local South African oil refinery effluent using a coagulation flotation process is designed using response surface methodology (RSM). A Box-Behnken design (BBD) implementing the RSM is applied to evaluate the effects and interactions of three operating parameters, viz., pH, coagulant dosage and flotation time, on the treatment of mineral oil wastewater (MOW). Polyacrylamide (Zetag-FS/A50), which is a water-soluble compound, is applied to enhance the adsorption mechanism and intermolecular bridging to minimise the amount of oil droplets. In addition, due to the monomeric nature and the charge density of the Zetag-FS/A50, its efficiency was evaluated to serve as an alternative coagulant for the pretreatment of the MOW. The removal of chemical oxidation demand (COD), soap oil and grease (SOG), total suspended solids (TSS) and turbidity from the MOW were used as the response variables for the coagulation flotation process. This was done with a standard dissolved air flotation jar test. The results show that the actual COD, SOG, TSS and turbidity percentage removal at optimised conditions with a coagulant dosage of 50 mg/L were 82%, 83%,70% and 83% respectively, while the predicted response was 92%, 96%, 73% and 87% for COD, SOG, TSS and turbidity, respectively. The analysis of variance (ANOVA) showed that the proposed models are significant at a 95% confidence level. A quadratic model was generated for response variables COD and SOG, while TSS and turbidity produced a linear model. The models fitted well with the experimental data with correlation coefficients (actual R2) of 0.94 for COD, 0.91 for SOG, 0.81 for TSS, and 0.75 for turbidity. The outcome of the study shows that the RSM has merit to optimise and identify the most important factor to control and the Zetag-FS/A50 coagulant has the potential to adsorb the oil droplets in order to enhance the treatment efficiency of the process.

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