Masters Degrees (DBMB)

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Browsing Masters Degrees (DBMB) by Subject "Acetone"

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    Application of bioaugmentation to improve nitrification at the Gammams Wastewater Treatment Plant
    (University of Namibia, 2017) Kavikairiua, Ngajozikue Kuhepa
    Namibia is among the driest countries in the world, and with the current drought that the country is experiencing, there is a greater need to provide drinking water not only to Windhoek, but the greater Nation at large. The Gammams Wastewater Treatment Plant, which is responsible for treating domestic and some industrial wastewater, regularly experiences toxic pluses that result in the inhibition of nitrification in the activated sludge process, leading to poor removal of ammonia. This is of great concern as the final effluent of the plant is used downstream for the production of potable water. The aims of this study were firstly to isolate and identify the nitrifying bacteria in the activated sludge system. Secondly, it was to test the inhibition capabilities of three test chemicals and thirdly to test the percentage recovery attainable by bioremediation using a fresh sample of activated sludge and by bioaugmentation using pure strains of Nitrosomonas and Nitrobacter. Sampling was performed once off for the growing on culture media, which was then used for molecular experimentation. Samples were then collected once a week for a duration of 9 weeks for the inhibition experiments, and then once off for the remediation and bioaugmentation experiments. Inhibition was carried out using acetone, toluene and brake fluid at concentrations of 5 ml/L, 10 ml/L and 50 ml/L, respectively. The test chemical that produced the highest inhibition percentage was then used in the remediation and bioaugmentation experiments. Pure cultures of Nitrosomonas and Nitrobacter were used in the bioaugmentation experiment, whereas the remediation experiment used a fresh sample from the aerated basins. Toluene at 50 ml/L produced the highest inhibition percentage (484%), while acetone at 5 ml/L produced the lowest inhibition percentage (17%). Culturing on solid media resulted in little growth, compared to growth that was obtained on the samples that were cultured on broth, which produced visible growth in suspension. These colonies were then used for the extraction of DNA for molecular identification of the variety of microorganisms present in the activated sludge basins at the GWWTP. The identity of the isolates was similar to that of Weissella species, Francisella species as well as Pseudomonas species. A 33.7% percentage recovery was attained through remediation, while the bioaugmentation experiment attained a percentage recovery of 35.8%.
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    Development of a “greener” hplc-uv method for the analysis of reducing sugars in apple juice and indigenous fruits using acetone as an alternative solvent
    (University of Namibia, 2023) Iyambula, Aina K
    Chromatographic techniques can be made more environmentally friendly, i.e., “greener”, by a number of different strategies. One approach is to replace the toxic mobile phase solvents such as acetonitrile with greener alternatives. Acetone, in particular, has proven to be a suitable alternative to acetonitrile, since the two solvents have similar physicochemical properties, including solubility, miscibility and viscosity properties. However, due to acetone’s high ultraviolet (UV) cut–off wavelength (330 nm), it normally cannot be used as a mobile phase solvent when performing high performance liquid chromatography (HPLC) analysis with UV detection. In this study, a reversed-phase HPLC–UV method using acetone-containing mobile phase was developed for the determination of reducing sugars in apple juice and two indigenous fruits, Berchemia discolor and Hyphaene petersiana. Pre-column derivatisation of analytes via reductive amination with p-aminobenzoic acid ethyl ester (ABEE) was performed to enable photometric detection at 307 nm. The method was directly compared to a method that utilised acetonitrile-containing mobile phase. Although the detection wavelength of the ABEE derivatives is below the UV cut–off wavelength of acetone, it is high enough above acetone’s absorbance maximum (~280 nm) to enable satisfactory detection of the derivatives. Hence, the method compared well with the acetonitrile method, providing similar resolution and selectivity, as well as sufficient sensitivity to facilitate the quantitation of glucose and fructose in all the fruits and juice investigated in this study. Although the method was only validated in terms of precision, linearity, limit of detection and quantitation but no other aspects such as accuracy, it shows potential to be used as a greener alternative for sugar analysis for laboratories that only have access to HPLC–UV instruments