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Browsing Articles by Author "Gumbo, Jabulani Ray"

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    Geochemical and Mineralogical Characterization of Gold Mine Tailings for the Potential of Acid Mine Darinage in the Sabie-Pilgrim's Rest Goldfields, South Africa
    (2017-11-28) Lusunzi, Rudzani; Gumbo, Jabulani Ray; Yibas, Bisrat; Novhe, Obed
    The environmental hazards arising from active and abandoned mine tailings are a cause for concern. We report on the presence of mineral-related environmental hazards in both Glynn Lydenburg and Nestor mine tailings, approximately 6 km apart and located in the Mpumalanga Province of South Africa. Based on XRD, shows a wide range of minerals: pyritic sulphide, quartz and mica. The XRF results showed that quartz was the dominant oxide in both the mine tailings; followed by Fe2O3 and Al2O3. Furthermore, trace elements, such as As, Cr, Cu, Pb, V and Zn, were also found which are hazardous to the environment.
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    The Presence of Toxic and Non-Toxic Cyanobacteria in the Sediments of the Limpopo River Basin: Implications for Human Health
    (MDPI, 2018-07-03) Magonono, Murendeni; Oberholster, Paul Johan; Shonhai, Addmore; Makumire, Stanley; Gumbo, Jabulani Ray
    The presence of harmful algal blooms (HABs) and cyanotoxins in drinking water sources poses a great threat to human health. The current study employed molecular techniques to determine the occurrence of non-toxic and toxic cyanobacteria species in the Limpopo River basin based on the phylogenetic analysis of the 16S rRNA gene. Bottom sediment samples were collected from selected rivers: Limpopo, Crocodile, Mokolo, Mogalakwena, Nzhelele, Lephalale, Sand Rivers (South Africa); Notwane (Botswana); and Shashe River and Mzingwane River (Zimbabwe). A physical-chemical analysis of the bottom sediments showed the availability of nutrients, nitrates and phosphates, in excess of 0.5 mg/L, in most of the river sediments, while alkalinity, pH and salinity were in excess of 500 mg/L. The FlowCam showed the dominant cyanobacteria species that were identified from the sediment samples, and these were the Microcystis species, followed by Raphidiopsis raciborskii, Phormidium and Planktothrix species. The latter species were also confirmed by molecular techniques. Nevertheless, two samples showed an amplification of the cylindrospermopsin polyketide synthetase gene (S3 and S9), while the other two samples showed an amplification for the microcystin/nodularin synthetase genes (S8 and S13). Thus, these findings may imply the presence of toxic cyanobacteria species in the studied river sediments. The presence of cyanobacteria may be hazardous to humans because rural communities and farmers abstract water from the Limpopo river catchment for human consumption, livestock and wildlife watering and irrigation.
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    The treatment of dye wastewater using natural South African magnesite
    (OMICS International, 2017-07-22) Ngulube, Tholiso; Gumbo, Jabulani Ray; Masindi, Vhahangwele; Maity, Arjun
    Discharging industrial colored wastewaters into aqueous environments can cause adverse effects on aquatic life due to the toxic nature of synthetic dyes. The present study aimed to evaluate the efficiency of using natural South African magnesite to remove an anionic dye from aqueous systems. The natural nanosorbent was characterized by Transmission Electron Microscopy, Fourier Transform Infra-Red and X-ray Diffraction analysis. Various important parameters namely contact time, initial concentration of dyes, magnesite dosage, solution temperature and solution pH were optimized to achieve maximum adsorption capacity. The XRD results revealed that raw magnesite contains magnesite, periclase, dolomite and quartz as the crystalline phases. Optimum conditions were observed to be 60 min of agitation, 0.1 g dosage of magnesite per 50 mL of aqueous solution, 40 mg/L initial dye concentration and room temperature. Removal of DR81 from aqueous solution was observed to be independent of initial pH of the aqueous solution. The adsorption ratio toward 40 mg/L of DR81 was 96.27%. The results indicate that natural South African magnesite is an efficient material for the removal of DR81. The magnesite, due to high accessibility, low cost and non-toxicity can be considered a good replacement option of other high cost materials used to treat colored wastewater especially in developing countries like South Africa