Browsing by Author "Legonda, I."

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    Carbon monoxide exposure during cooking in households: A case of Dar es Salaam city, Tanzania
    (Journal of Environmental Science and Engineering, 2013) Legonda, I.; Marsh, R.; Mkilaha, I.; Griffiths, A.
    Exposure to CO (carbon monoxide) during cooking in households using LPG (liquefied petroleum gas), natural gas and charcoal as fuels has been conducted. The study aimed at assessing the indoor air quality in order to address potential hazardsassociated with CO. Carbon monoxide concentrations and flame temperature were measured at an interval of 1 min for 1 h using COand thermometer data loggers respectively. While the CO concentration from LPG and natural gas were found below 26 ppm for 1 h,as recommended by WHO (World Health Organization) standards, the average CO concentration from charcoal exceeded the standard limit. In addition closing the kitchen door during cooking increased the CO concentration from 26-295 ppm to 92-597 ppm. According to WHO, the observed CO concentrations from charcoal stove highlights questionable life support atmosphere. It can therefore be suggested that switching to LPG or natural gas from charcoal will reduce CO exposure to persons during cooking.
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    The effect of particles size on biogas production
    (2016) Nalinga, Y.; Legonda, I.
    The study on the effect of particles size on biogas produc-tion has been conducted. Substrates consisted of pre-treated water hyacinth with drying and grounded to fine particles of (0.001and0.05mm) and chopped water hyacinth to small particles of (1.0 and2.5 mm). The reactor digesters were operated atmesophilic temperature ranges of 25 °C to 32 °C with retention time of 23 days. Results showed that highest biogas production occurred with the most finely grounded substrate (0.001 mm) which recorded 0.39liters of biogas with 70 % CH4 followed by the grounded particles of 0.05 mm yields 0.34 liters with 66% CH4 .while the lowest bio-gas production was observed from the chopped particles of 2.5 mm producing 0.24 liters of biogas with 55% CH4. Fur-ther observation revealed that methane yields increased by 21% when the substrates were pre-treated by grinding into very fine particles compared with the chopped substrate. The results suggest that small particle size favours methane yield.
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    Experimental investigation on biogas production from anaerobic co-digestion of water hyacinth and fish waste
    (2016) Nalinga, Y.; Legonda, I.
    Co-digestion of various wastes and biomass feedstock has been shown to improve the digestibility of the materials and biogas yield. In this study,the co-digestion of water hyacinth and fish waste was studied at different mixing proportions. The anaerobic digestion was carried out in batch digester reactors sized 500 ml and were charged to 10 % of total vol-ume. Co-digestion was conducted for a retention period of 21days in mesophilic temperature ranging 25.3 °C to 33.4 °C. The research revealed that the highest biogas production was observed from the combination of FW:WH, at 1:2 ratio. The maximum biogas recorded was 0.56 literswith compo-sition of 73.3 % CH4. Furthermore, the water hyacinth also recorded0.46 literswith the composition of 70 % CH4which suggesteconomical feasibility. The overall results showed that blending water hyacinth with fish waste had significant improvement on the biogas yield.
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    Standardizing defluoridation of community waters using bone char
    (2017) Mbabaye, G. K.; Mtalo, F.; Minja, R. J.; Legonda, I.
    Different bone char (BC) preparation methods affect the physical chemical properties and therefore the capacity to remove fluoride. Fluoride removal capacities of BC prepared at three controlled temperatures, with particle grain sizes of 250–500 μm, 500–1,000 μm and 1,000–1,800 μm were determined in column experiments with an initial fluoride concentration of 8.55 mg/L. The sorbent was calcined at 400°C, 500°C and 600°C. BC calcined at 400°C had better fluoride removal performance compared to those calcined at 500°C and 600°C due to decreased pore volume and surface area as the calcination temperature was increased. There was a reduced mass transfer effect to the adsorption sites in pores as the BC particle size was increased. The equilibrium adsorptions Langmuir and Freundlich isotherms were tested. For the Langmuir equilibrium adsorption isotherm, maximum monolayer coverage (Q) was determined to be 3.512 mg/g, and the value of the separation factor (r) obtained was 0.1394 indicating favorable adsorption as it lies between 0 and 1. The Freundlich governing equilibrium adsorption isotherm model gave a value of 1/n equal to 0.445. This indicates a favorable adsorption process, since the bond energies increase with surface density of the adsorbent.