Browsing by Author "Mamvura, T.A."

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    Optimisation of using a blend of plant based natural and synthetic coagulants for water treatment: ( Moringa Oleifera-Cactus Opuntia-Alum Blend)
    (2020) Gandiwa, B.I.; Moyo, L.B.; Ncube, S.; Mamvura, T.A.; Hlabangana, N.
    The research presents a comparative study on the effectiveness of blending plant based natural coagulants (Cactus Opuntia and Moringa Oleifera extracts) and a synthetic coagulant (aluminium sulphate or alum) in treatment of raw water. The low production rates of natural coagulants has derailed their commercialization this has driven the idea of blending synthetic coagulants which is envisaged to be the more appropriate means of application in this study. To measure the effectiveness of the coagulant, the following parameters were measured; turbidity, pH, conductivity and total alkalinity. The simplex lattice experimental design was applied using Minitab Software to obtain the optimal coagulant blend. The models were validated by statistical analysis which showed that the model was sufficient and no further modeling was required. The optimization results showed that a combination of alum, Moringa Oleifera and Cactus Opuntia in proportions of 13%, 42.6% and 44.4%, respectively with a total coagulant dosage of 45mg/L gave the best overall results with the resultant water having a turbidity, pH, conductivity and total alkalinity of 2.7 NTU, 6.99, 308 µS/cm and 137.7mg/L respectively. These physiochemical parameters are within required limits for potable water as per WHO guidelines. From the results, it was concluded that aluminum sulphate (alum) can be successfully blended with natural plantbased coagulants for raw water treatment.
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    Optimization of pulp production from groundnut shells using chemical pulping at low temperatures
    (2020) Musekiwa, P.; Moyo, L.B.; Mamvura, T.A.; Danha, G.; Simate, G.S.; Hlabangana, N.
    Paper production through chemical pulping has been identified as one of the ideal avenues of exploring the uses of groundnut shells as they are rich in cellulose. Ideally, the cellulose can be used to synthesize fibres that can be converted into useful paper products. In this study, chemical pulping was the chosen process for liberating the fibres as it is effective in dissolving lignin embedded within the cellulose. In addition, the fibres produced have superior physical properties compared to mechanical pulping. It is imperative that optimal conditions are identified for the chemical treatment process, in order to ensure that energy and chemical consumption are minimized. All these measures are aimed at reducing production costs and make chemical pulping economically viable, as compared to the mechanical pulping process which is less costly. Response surface methodology (RSM) was used in this study to evaluate the effect of three independent variables (cooking time, temperature, and sulphidity) on pulp yield and kappa number. These parameters are critical in the chemical pulping process and the optimal conditions obtained were 180 min, 100 C and 23.6 wt.%, respectively. At the optimal conditions, the pulp yield was 64.39wt% with a kappa number of 19.5. The results showed that all parameters investigated, had a statistically significant effect on the production of pulp. The increased cooking time was efficient in ensuring complete impregnation of the groundnut shells with chemicals for pulping and ensuring that the dissolution of lignin is not selective and does not result in dead spots inherently compromising the quality of the pulp. On the other hand, lower temperatures limited the peeling effect due to hydrolysis of carbohydrates which increased pulp yield due to a higher cellulose retention. Consequently, this contributed towards obtaining pulp that is well cooked, has a low bleach consumption and a higher quality.