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No description available.

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No description available.

Mining industry has been identified as the main sustenance of the South African economy, however the negative impacts of the industry on the ecological systems cannot be over emphasized due to the released waste which is mostly heavy metals into the environment. The study evaluated six heavy metal (A1, Cu, Fe, Ni, Pb and Cr) contents in a tailings dam from a specific mine site. Two sets of samples for the investigation were measured, that is, one in year 2012 and the other in year 2013. In the year 2012, the sample set was only taken at a distance profile of 500 meters from the foot of the dam, whereas the sample set taken in the year 2013 was for the 500 and 1500 meter distance profiles from the foot of the dam. The year 2012 and 2013 sample sets for the 500m distance profile were sampled very similarly to each other. A kilogram of each sample was taken as per grid format. The samples at varied depths were taken at 0-cm depth for the top layer, 20cm depth for the second layer, and 30cm depth for the third layer. The samples for the surface varied distance were taken at 1 m, 2m, 3m, and 4m away from each 500m and 1500 sampling points. The 2012 samples were analysed using characterization methods namely ICP MS and The 2013 samples were analysed using the ICP OES. The comparison of the field results for the six heavy metals studied (A1, Fe, Pb, Cu, Ni and Cr) was performed using statistical analytical methods, namely ANOVA. The statistical analysis results for heavy metals (A1, Fe, Pb, Cu, Ni and Cr) from sample and 2013 revealed that the group means are not significantly different from each other which means that there is no significant difference in (A1, Fe, Pb, Cu, Ni and Cr) concentrations with respect to both depth and distance. The observations from both 2012 and 2013 indicate the results of the samples are in agreement. In addition, the comparative average concentrations of the three results obtained reach the same conclusion that the tailing dam probably does not introduce considerable or significant amounts of these metals (A1, Fe, Pb, Cu, Ni and Cr) into the surrounding soils. / Chemical Engineering / M. Tech. (Chemical Engineering)

published_or_final_version / Ecology and Biodiversity / Master / Master of Philosophy

Biosorption is a property of certain type of inactive, microbial biomass to bind and concentrate heavy metals from even very dilute aqueous solutions. Biomass exhibits this property, acting just as a chemical substance, as an ion exchanger of biological origin. It is particularly the cell wall structure of certain algae that is found responsible for this phenomenon. In these experiments, the rate and extent for removal of copper is subjected to parameters such as pH, initial metal concentration, biosorbent size, contact time, temperature and the ability of the biomass to be regenerated in sorption-desorption experiments. The metal adsorption was found to be rapid within 25 minutes. The maximum copper uptake of 30 mg of copper / g of biomass has been observed, in the following conditions: 100 mg / L, 0.1 g of biomass, pH 4 and at temperature of 25°C. From this study, it was found that copper uptake is increasing with increase in pH, with optimum being pH 4. Copper uptake increases substantially from 0 to 25 minutes. Metal biosorption behaviour of raw seaweed Sargassum in six consecutive sorptiondesorption cycles were also investigated in a packed-bed column, during a continuous removal of copper from a 35 mg/l aqueous solution at pH 4. The sorption and desorption was carried out for an average of 85 and 15 hours, respectively, representing more than 40 days of continuous use of the biosorbent. The weight loss ofbiomass after this time was 13.5%. The column service time decreased from 25 hrs in the first cycle to 10 hrs for the last cycle. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2005.

M.Sc. (Zoology) / The production of nanoparticles started as early as 1990s (Alkilany & Murphy, 2010). Nanoparticles are utilised in a range of products such as electronics, optics, textiles, medical, devices, cosmetics, food packaging, water treatment technology, fuel cells, catalysts, biosensors and agents for environmental remediation (Handy et al., 2008). Unlike natural particles, which dissolve or aggregate and are often temporary in the environment, engineered nanoparticles (ENPs) maybe persistent due to the stabilization properties of their capping agent (surfactant or organic material). Thus, there is growing concern about the production and fate of ENPs in the environment (Handy et al., 2008).As ENPs pass through the water system they become exposed to different salinities, ionic concentrations and pH changes (Lapresta-Fernández et al., 2012). During this process the ENPs are degraded, transported, altered and accumulated in various ways. Nanoparticles have been found to aggregate in various organelles, for example endocytotic vesicles (Elsaesser & Howard, 2011; Lapresta-Fernández et al., 2012), cytoplasm and the perinuclear region (Mirkin et al., 2010). This can take place via ingestion, endocytosis and or by diffusion (Nowack & Bucheli, 2007). The major question is are NPs toxic and are they more toxic than their metal salts? While bulk gold is distinguished as a chemically inert and a non-toxic substance, (Alkilany & Murphy, 2010) GNPs may be toxic due to their different physicochemical properties such as small particle size, configuration, charge and specific surface area and easy surface alterations (Cho et al., 2009; Goodman et al., 2004; Lapresta-Fernández et al., 2012)...

Mining industry has been identified as the main sustenance of the South African economy, however the negative impacts of the industry on the ecological systems cannot be over emphasized due to the released waste which is mostly heavy metals into the environment. The study evaluated six heavy metal (A1, Cu, Fe, Ni, Pb and Cr) contents in a tailings dam from a specific mine site. Two sets of samples for the investigation were measured, that is, one in year 2012 and the other in year 2013. In the year 2012, the sample set was only taken at a distance profile of 500 meters from the foot of the dam, whereas the sample set taken in the year 2013 was for the 500 and 1500 meter distance profiles from the foot of the dam. The year 2012 and 2013 sample sets for the 500m distance profile were sampled very similarly to each other. A kilogram of each sample was taken as per grid format. The samples at varied depths were taken at 0-cm depth for the top layer, 20cm depth for the second layer, and 30cm depth for the third layer. The samples for the surface varied distance were taken at 1 m, 2m, 3m, and 4m away from each 500m and 1500 sampling points. The 2012 samples were analysed using characterization methods namely ICP MS and The 2013 samples were analysed using the ICP OES. The comparison of the field results for the six heavy metals studied (A1, Fe, Pb, Cu, Ni and Cr) was performed using statistical analytical methods, namely ANOVA. The statistical analysis results for heavy metals (A1, Fe, Pb, Cu, Ni and Cr) from sample and 2013 revealed that the group means are not significantly different from each other which means that there is no significant difference in (A1, Fe, Pb, Cu, Ni and Cr) concentrations with respect to both depth and distance. The observations from both 2012 and 2013 indicate the results of the samples are in agreement. In addition, the comparative average concentrations of the three results obtained reach the same conclusion that the tailing dam probably does not introduce considerable or significant amounts of these metals (A1, Fe, Pb, Cu, Ni and Cr) into the surrounding soils. / Chemical Engineering / M. Tech. (Chemical Engineering)

A research project submitted to the Faculty of Sciences, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Environmental Sciences (Coursework and Research Report). Johannesburg, 2016. / Paenibacillus castaneae isolated from acid mine decant (Gauteng, South Africa) was previously shown to tolerate high concentrations of lead (Pb). The ability of the bacterium to tolerate/resist other heavy metals is probable and suggests a role for P. castaneae as a biosorbent for their removal from contaminated wastewaters. The current study aimed at determining whether the bacterium is also resistant to other common metal contaminants specifically, zinc (Zn) and nickel (Ni), found in South African wastewaters for biosorption by P. castaneae. Additionally, the influence of the external factors pH and competing cations on the uptake of these metals by the bacterium was evaluated. Specific rates of metal uptake (Q) were calculated indirectly from quantifying (by spectroscopy) the residual ion concentrations post exposure to 3 mM metal after various treatments. P. castaneae was found to tolerate Zn but showed vulnerability towards Ni. In a binary metal system, the bacterium showed a preferential metal uptake in the order Zn>>Co> Mn with a highest Q of 26 mg Zn/g biosorbent biomass recorded in the presence of Mn at pH 7. On the contrary, in a multimetal complex solution, the order of preference shifted to Co>>Zn with no absorption of Mn at the same pH. The results indicate that both pH and the presence of cations have an effect on the uptake of Zn by P. castaneae that could favour or inhibit its biosorption. The present study confirms the ability of P. castaneae to remove additional metals such as Zn, Mn and Co. These findings further suggest the potential of P. castaneae as a biosorbent for greener clean-up strategies of contaminated water facilities around Gauteng in the way of bioremediation. Keywords: P. castaneae, biosorption, specific metal uptake, zinc, lead, nickel / LG2017