Browsing by Author "Ngonyani, Consolatha Joachim"

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    Study of nutrient pollutants and their impacts on the water quality of the mindu reservoir in Morogoro municipality
    (University of Dar es Salaam, 2003) Ngonyani, Consolatha Joachim
    The study on Mindu Reservoir, whose 50% of its waters has been plagued by aquatic weeds, involved the physicochemical parameters characterization. Sampling and determination of both water and sediment samples followed the standard techniques. The parameters pH, EC, DO, NTU and NO3" were determined in situ, using a portable field probe (by HANNA instruments). Water samples were analyzed for TN, TP, HCO3', SO42', Cl' and NO3' (APHA 1985). Filtered water samples were analyzed for Ca and Mg using AAS. The FE-spectrophotometer was used for K and Na determinations. As the average value for P-PO,*3’ was found to be above the eutrophication level, the N: P ratios average value at 8.51 ± 4.3 suggested a Redfield behavior of nutrients with nitrogen being a limiting one. XRD-mineralogical determination on the sediments indicated that the dominant clay minerals are kaolinite and illite. The CEC values measured > 48 cmol (+)/kg clay, are high enough for the sorption of nutrients and pollutants. The PCA showed five factors that explain processes influencing the water characteristics. Therefore Mindu Reservoir is classified as eutrophic with calcium magnesium bicarbonate type of water. Both River inflows overlay flows and sediments forms the mode of nutrient transport with the later behaving as a sink of nutrients. The evaporation, bio-geo-chemical and N fixation processes along with macrophyte productivity, supports the hypotheses that physical-bio-geo-chemical processes influence the spatial distribution of major ion in the Reservoir. A detailed multidisciplinary study that captures more than one year cycle was recommended, to capture inter seasonal variability, and for the sequestration of nutrients in various trophic levels.
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    Utilization of sisal bole juice – inulin as an alternative chemical feedstock in citric acid production
    (Unversity of Dar es Salaam, 2010) Ngonyani, Consolatha Joachim
    Tanzanian Sisal industry is characterised by a severe biomass production for wastage that is (2:98) product to waste ratio. Among the waste, 100% of plant residues in a form of sisal boles, that are made of hydrolysable-fermentable sugars are slashed and burned thus causing environmental emission concerns. The present study on utilization of sisal bole juice-inulin as an alternative chemical feedstock in citric acid production was divided into three parts. The first part involved the isolation and characterisation of the Aspergillusniger fungal strains generic to sisal boles for citric acid production using sisal inulin hydrolysate-fructose. A high biodiversity of microorganism with industrial potential were isolated and identified, including the best performer A. niger (BYF KT) fungal strain which was used in citric acid fermentation studies. The second part involved the extraction and hydrolysis of inulin sugars from sisal boles. HPLC analysis revealed that sisal boles had total sugar concentrations values between (26.4±0.24 and 26.9±0.31 g/100ml) with the corresponding fructose values between (24.9±0.02 and 25.6±0.03 g/100ml). Hydrolysis experiments were performed by cooking at temperature range of 30-132oC and pH range of 2-5. The effects of initial conditions (pH and temperature) were evaluated using 22 full factorial designs (FFD), with varying levels of pH and temperature. The factorial fit and the analysis of variance (ANOVA), indicated that initial conditions for both pH and temperature significantly affected hydrolysates-fructose yield, at confidence interval (CI) of 95%. The optimum hydrolysates yields value of 97.2% (82.4%fructose) was obtained by cooking at temperature 110±5oC ~ (115oC) and pH 3. The third set of experiments involved 10l pilot scale fermentation of sisal inulinhydrolyisates-fructose using A. niger (BYF KT) generic to sisal, at initial fructose concentration range of 102-203 g/l, pH range 2-5 and nutrients additives values coded between -1 and 1. The effects of initial hydrolysate-fructose concentration, pH and nutrients additives were evaluated using a 23 full factorial design (FFD), with varying levels of initial hydrolysates-fructose concentration, pH and nutrients additives; The factorial fit and (ANOVA) for citric acid yield, indicated that initial hydrolysate-fructose concentration and pH significantly effected citric acid yield, at confidence interval (CI) of 95%, while nutrients additives was not significantly affecting the yields. Results for pilot scale fermentation of 203g/l sisal juice hydrolysate-fructose, in absence of nutrients additive and pH 5 produced highest yields value of 46.66% (103.15±13.08 g/l). On the contrary, minimum citric acid yield value of 9.51% (9.70±2.40 g/l) was obtained at low initial fructose concentration of 102 g/l, pH 2 and with nutrient additions. The current findings supported that sisal inulin has a great potential use as an alternative feedstock in citric acid production, adding value to sisal industry and could be one way of dealing with waste management.