Browsing by Author "Manyele, Samwel V."

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    A Kinetic Study of Anaerobic Biodegradation of Food and Fruit Residues during Biogas Generation Using Initial Rate Method
    (Scientific Research, 2013) William, Wanasolo; Manyele, Samwel V.; Makunza, John K.
    A kinetic study of biogas production from Urban Solid Waste (USW) generated in Dar es Salaam city (Tanzania) is presented. An experimental bioreactor simulating mesophilic conditions of most USW landfills was developed. The goal of the study was to generate the kinetic order of reaction with respect to biodegradable organic waste and use it to model biogas production from food residues mixed with fruit waste. Anaerobic biodegradation was employed under temperature range of 28˚C - 38˚C. The main controls were leachate recirculation and pH adjustments to minimize acid inhibitory effects and accelerate waste biodegradation. The experimental setup was comprised of three sets of bioreactors. A biodegradation rate law in differential form was proposed and the numerical values of kinetic order and rate constant were determined using initial rate method as 0.994 and 0.3093 mol0.006·day−1, respectively. Results obtained were con-sistent with that found in literature and model predictions were in reasonable agreement with experimental data.
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    Regression Modeling and Analysis of Factor-Interactive Effect on Anaerobic Biodegradation Process for Biogas Generation
    (2014) William, Wanasolo; Manyele, Samwel V.; Makunza, John K.
    In this study, regression modeling and analysis of factor-interactive effect on anaerobic biodegradation process (ABP) of food residues mixed with fruit-waste is presented. An experimental anaerobic digester simulating mesophilic conditions of most urban solid waste dumpsites was developed. The goal was to carry out regression modeling on anaerobic biodegradation process for biogas generation. The main-and interactive-effects of initial-pH, ash-loading and leachate-level were investigated. Response surface methodology with miscellaneous 3-level factorial design was employed. A second-order polynomial regression equation was generated that predicted biogas generation rate (BGR). Results indicated that within the experimental range of factors applied there was a single factor significant effect of initial-pH and ash-loading on ABP while leachate-level single effect was observed to be insignificant (α < 0.05). The two factor interactive-effects of initial-pH/ash-loading and leachate-level/ash-loading were found to be significant while that of initial-pH/leachate-level interactions was not significant. Verification tests yielded maximum BGR values that were in good agreement with predicted values thereby validating the regression model.
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    The Study of Kinetic Properties and Analytical Pyrolysis of Coconut Shells
    (Hindawi Publishing Corporation, 2015) Said, Mahir M.; John, Geoffrey R.; Mhilu, Cuthbert F.; Manyele, Samwel V.
    The kinetic properties of coconut shells during pyrolysis were studied to determine its reactivity in ground form. The kinetic parameterswere determined by using thermogravimetric analyser.The activation energywas 122.780 kJ/mol.The pyrolysis products were analyzed using pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The effects of pyrolysis temperature on the distribution of the pyrolytic products were assessed in a temperature range between 673K and 1073K.The set time for pyrolysis was 2 s. Several compoundswere observed; theywere grouped into alkanes, acids, ethers and alcohols, esters, aldehydes and ketones, furans and pyrans, aromatic compounds, and nitrogen containing compounds.The product compositions varied with temperature in that range. The highest gas proportion was observed at high temperature while the acid proportion was observed to be highest in coconut shells, thus lowering the quality of bio-oil. It has been concluded that higher pyrolysis temperature increases the amount of pyrolysis products to a maximumvalue. It has been recommended to use coconut shell for production of gas, instead of production of bio-oil due to its high proportion of acetic acid.