Research Repository :: Browsing by Author "Katima, Jamidu H. Y."

Browsing by Author "Katima, Jamidu H. Y."

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Comparison of Escherichia Coli KO11 and Saccharomyces Cerevisiae ATCC 96581 in Fermenting Pinus Patula Hydrolysate Pretreated at Different Steam Explosion Severity
(2012) Chacha, Nyangi; Dyrset, Nils; Mtui, Godliving; Katima, Jamidu H. Y.; Mrema, Godwill
Bioconversion of wood residues to biofuels such as ethanol is one of the feasible initiatives towards production of renewable energy. This work compares the effectiveness of Escherichia coli KO11 and Saccharomyces cerevisiae ATCC 96581 in fermenting Pinus patula (pine) hydrolysate pretreated by acid-catalyzed steam explosion. The results show no significant difference in terms of the ethanol yield when E. coli KO11 and S. cerevisiae ATCC 96581 were used. The maximum ethanol concentration obtained in test tubes fermentation were 18.30 and 19.41 g/l for E. coli KO11 and S. cerevisiae ATCC 96581, respectively, from samples pretreated at 225°C/5 min. The ethanol yields obtained using bioreactors for samples pretreated at 225°C, 0.5% SO2, and 5 min, were 21.30 and 19.63 g/l for E. coli and S. cerevisiae, respectively. Overall, ethanol yields were higher in bioreactors than in test tubes for both strains. In comparison, S. cerevisiae consumed the substrate faster than E. coli, thus making S. cerevisiae the most preferred strain in fermentation of hydrolysates from steam pretreated P. patula.
Effect of Diffusional Mass Transfer on the Performance of Horizontal Subsurface Flow Constructed Wetlands in Tropical Climate Conditions
(2011) Njau, Karoli N.; Gastory, L; Eshton, Bilha; Katima, Jamidu H. Y.; Minja, Rwaichi J. A.; Kimwaga, Richard; Shaaban, M.
The effect of mass transfer on the removal rate constants of BOD₅, NH₃, NO₃ and TKN has been investigated in a Horizontal Subsurface Flow Constructed Wetland (HSSFCW) planted with Phragmites mauritianus. The plug flow model was assumed and the inlet and outlet concentrations were used to determine the observed removal rate constants. Mass transfer effects were studied by assessing the influence of interstitial velocity on pollutant removal rates in CW cells of different widths. The flow velocities varied between 3-46 m/d. Results indicate that the observed removal rate constants are highly influenced by the flow velocity. Correlation of dimensionless groups namely Reynolds Number (Re), Sherwood Number (Sh) and Schmidt Number (Sc) were applied and log-log plots of rate constants against velocity yielded straight lines with values β = 0.87 for BOD₅, 1.88 for NH₃, 1.20 for NO₃ and 0.94 for TKN. The correlation matched the expected for packed beds although the constant β was higher than expected for low Reynolds numbers. These results indicate that the design values of rate constants used to size wetlands are influenced by flow velocity. This paper suggests the incorporation of mass transfer into CW design procedures in order to improve the performance of CW systems and reduce land requirements.
Effects of Substrate Concentrations on the Growth of Heterotrophic Bacteria and Algae in Secondary Facultative Ponds
(Elsevier, 2003) Kayombo, S.; Mbwette, T. S. A.; Katima, Jamidu H. Y.; Jørgensen, S. E.
This paper presents the effect of substrate concentration on the growth of a mixed culture of algae and heterotrophic bacteria in secondary facultative ponds (SFPs) utilizing settled domestic sewage as a sole source of organic carbon. The growth of the mixed culture was studied at the concentrations ranging between 200 and 800 mg COD/l in a series of batch chemostat reactors. From the laboratory data, the specific growth rate (m) was determined using the modified Gompertz model. The maximum specific growth rate (mmax) and half saturation coefficients (Ks) were calculated using the Monod kinetic equation. The maximum observed growth rate (mmax) for heterotrophic bacteria was 3.8 day 1 with Ks of 200 mg COD/l. The mmax for algal biomass based on suspended volatile solids was 2.7 day 1 with Ks of 110 mg COD/l. The mmax of algae based on the chlorophyll-a was 3.5 day 1 at Ks of 50 mg COD/l. The observed specific substrate removal by heterotrophic bacteria varied between the concentrations of substrate used and the average value was 0.82 (mg COD/mg biomass). The specific substrate utilization rate in the bioreactors was direct proportional to the specific growth rate. Hence, the determined Monod kinetic parameters are useful for the definition of the operation of SFPs.
Environmental Impact Assessment: For Whose Needs?
(2008) Katima, Jamidu H. Y.
Tanzania, like many other developing countries, is keen to attract foreign investments to foster the country’s socioeconomic development. However, the competition among developing countries to attract foreign investment preference has in many cases sacrificed policies geared towards sustainable development for short-term economic gains. With the intention of conserving the global environment, the multinational financing institutions have made it mandatory that all development projects should be subjected to EIA before they can be funded. Is this sustainable? This case study suggests that an effective (and sustainable) EIA regime is dependent on, among other things: • the government’s political will; • effective environmental legislation; • institutional support; • proper development objectives; and • trained personnel. Unfortunately, many of these factors are not in place in Tanzania (and probably not in place in most developing countries). This has led in many cases to frustration on the part of environmental impact assessors, governmental advisors and the public at large. Because of economic considerations some projects have been given a go ahead despite negative assessment and public outcry. In some cases, projects have been assessed positively even though the negative impacts are obviously overwhelming, which may be due to the fact that the investor is paying for the assessment and thus may influence the outcome of the assessment process. This case study examines the prawn project, which was subjected to EIA, rejected by the review team and approved for implementation by the government. The paper poses a question: For whose needs is the EIA conducted? The investor? The government? The assessor? The environment? The public?
Factors Influencing Catalytic Wet Peroxide Oxidation of Maleic Acid in Aqueous Phase over Copper/Micelle Templated Silica-3-Aminopropyltrimethoxysilane Catalyst
(2009) Daniel, Lilian; Katima, Jamidu H. Y.
Catalytic wet peroxide oxidation (CWPO) of initial maleic acid feed concentration (0.005 to 0.03 M) was carried out in a temperature range of 20-50°C, on micelle templated silica-3-aminopropyltrimethoxysilane (MTS-AMP) supported copper catalyst. The influence of various operating parameters such as initial feed concentration of maleic acid, temperature, catalyst loading and the stability of the catalyst were investigated. CWPO reactions were performed in a stirred batch reactor at an atmospheric pressure in the presence of H₂O₂ as an oxidant. Total conversion of maleic acid into acetic acid was obtained under mild conditions (i.e. atmospheric pressure and 40°C). Blank experiments showed no measurable maleic acid conversion (i.e. only ∼0.5% conversion of initial maleic acid), indicating that a significant oxidation reaction of maleic acid is enhanced by the presence of a catalyst. Copper on micelle templated silica-3-aminopropyltrimethoxysilane catalyst therefore was found to be suitable for aqueous phase oxidation of maleic acid with 100% of maleic acid conversion.
Joint Action on Climate Change: African Countries -Part of the Problem or Part of the Solution?
(2015) Katima, Jamidu H. Y.; Pritchard, Colin L.
Climate change and the associated global warming are a major challenge in the world today: extreme weather events such as flood and droughts; food insecurity and famine; disease etc. are reported to be exacerbated by the climate change. Greenhouse gas (GHG) emission is considered to be responsible for this change. On one hand, it is believed that the weakest economies (the majority of sub-Saharan countries) and disadvantaged poorest people are more vulnerable to impacts of climate change. On the other hand Sub-Saharan Africa contributes about 3% to GHG emissions, with per capita GHG emission standing at about 2.3 tCO2e compared to about 24.1 tCO2e for North America. Mechanisms that have been put in place to mitigate climate change, such as the Clean Development Mechanism, have not significantly benefitted Africa. This paper discusses the inadequacies of the existing mechanisms to mitigate climate change in the African context. It argues that currently Africa is neither part of the problem nor part of the solution. This, therefore, calls for a separate mechanism for Africa in the next round of climate negotiations.
Kinetics of Malonic Acid Degradation in Aqueous Phase over Pt/Graphite Catalyst
(2005) Masende, Z. P. G.; Kuster, B. F. M.; Ptasinski, K. J.; Janssen, F. J. J. G.; Katima, Jamidu H. Y.; Schoutena, J. C.
This work aims at describing quantitatively the catalytic decarboxylation of malonic acid over a 5.0 wt.% Pt/graphite catalyst. The study was carried out using a slurry phase continuous flow stirred slurry reactor (CSTR) at a temperature range of 120–160 °C and at a reactor pressure of 1.8 MPa. The conversion of malonic acid during catalytic oxidation was found to proceed via decarboxylation to CO2 and acetic acid, and also oxidation to CO2 and H2O. No indication of deactivation of the platinum catalyst was observed at a maximum residual oxygen pressure in the reactor up to 150 kPa. A reaction mechanism involving elementary steps has been suggested to explain the decarboxylation and oxidation of malonic acid. A kinetic model that accounts for both non-catalysed and catalysed decarboxylation of malonic acid has been developed and validated. The non-catalysed reaction is first order in malonic acid. The activation energies and adsorption enthalpies have been determined. The model is able to describe the experimental data adequately.
Modifying Plant Oils for Use as Fuel in Rural Contexts Tanzania: Techno-Economic Analysis
(Open Journal of Modelling and Simulation, 2014-04) Mlay, Happiness; Katima, Jamidu H. Y.; Minja, Rwaichi J.A.
Techno-economic analysis of a small-scale Modified Plant Oil (MPO) production plant that has an annual production capacity of 15,072,741 kg of MPO (batch process) was carried out to estimate the capital and operating costs of a plant. The analysis was done by using a computer model that was designed and simulated with an aid of SuperPro Designer (Version 4.32) software. The specified feedstock was crude Jatropha oil (JO) and the main product was MPO. The major processes involved were degumming, neutralisation and blending. Degumming involved the removal of gums or phospholipids, and two methods were used: water degumming and acid degumming, whereas blending involved mixing of degummed or purified JO with natural gas condensate (NGC) modifier to lower the viscosity of JO. From techno-economic analysis of the process, it was found that the total capital investment of a plant was about US $ 10,222,000 and the predicted unit production cost of MPO was US $ 1.315/kg at a value of US $ 1.0/kg of JO. The economic feasibility of MPO production was found to be highly influenced by the price of feedstock, which contributed about 95% of the total annual production cost. The relationship between plant throughput and unit cost of producing MPO showed that unit production cost was very sensitive to production rate at low annual throughputs. The MPO cost showed a direct linear relationship with the cost of JO, with a change of US $ 0.50/kg of MPO in MPO cost in every change of US $ 0.50/kg of JO in JO price. The process technology simulated was found to be economically viable and can be implemented in rural setting, taking into consideration Tanzania’s rural situation.
Plant Oils Blends as Alternative Fuels for Low -and Medium Speed Diesel Engines: Natural Gas Condensate Utilization
(2015-04) Mlay, Happiness; Katima, Jamidu H. Y.; Minja, Rwaichi J. A.
Platinum Catalysed Wet Oxidation of Phenol in a Stirred Slurry Reactor: A Practical Operation Window
(Elsevier, 2003) Masende, Z. P. G.; Kuster, B. F. M.; Ptasinski, Krzysztof J.; Janssen, Frans J. J. G.; Katima, Jamidu H. Y.; Schouten, J. C.
The catalytic performance of graphite supported platinum (5 wt.%) catalyst in liquid phase oxidation has been studied using a continuous flow stirred tank slurry reactor (CSTR) in order to determine the proper operation window. The study was carried out in a temperature range of 120–180 °C and in a total pressure range of 1.5–2.0 MPa. Other operational variables employed were oxygen partial pressure (0.01–0.8 MPa), initial phenol feed concentration (0.005–0.07 M), and catalyst concentration from 1 to 10 kg m−3. It was found that the extent of oxygen coverage on the platinum surface determines the reaction pathway and selectivity to CO2 and H2O. Complete oxidation of phenol to CO2 and H2O could be achieved at 150 °C when the reaction proceeds within the range of weight specific oxygen loads of 0.15–0.35 mol s−1 kgPt−1 and at stoichiometric oxygen excess in the range of 0–80%. The activity of the platinum catalyst remained high when the residual partial pressure of oxygen in the reactor was kept below 150 kPa. Higher residual oxygen partial pressure resulted into deactivation of the platinum catalyst (over-oxidation), which was temporary and could be reversed at reducing conditions. The formation of p-benzoquinone, followed by the formation of polymeric products was also favoured at higher oxygen load, which resulted into permanent deactivation of the platinum catalyst (poisoning). While the platinum surface was vulnerable to poisoning by carbonaceous compounds when insufficient oxygen was used, a fully reduced platinum surface favoured the formation of acetic and succinic acids which are difficult to oxidize. Higher temperatures can enhance the activity of the platinum catalyst, while at lower temperatures catalyst deactivation occurs with increased formation of polymeric products and lower selectivity to CO2 and H2O. In order to maintain the catalyst within the proper operation window, a CSTR is the preferred reactor.
Pumice Soil: A Potential Wetland Substrate for Treatment of Domestic Wastewater
(IWA Publishing, 2003) Njau, Karoli N.; Minja, Rwaichi J. A.; Katima, Jamidu H. Y.
Laboratory and fieldwork studies were carried out to evaluate the potential of pumice soil for use as a wetland substrate in wastewater treatment. The composition of pumice soil was analysed by x-ray fluorescence (XRF) and x-ray diffraction (XRD) techniques. Adsorption kinetic studies were carried out in a semi-batch recycle system. Fieldwork tests were carried out on Subsurface Flow Constructed Wetland (SSFCW) cells planted with Phragmites mauritianus and Vetiveria zizanioides. The results have shown that pumice soil composition contains among other elements Al, Ca, Fe and Mg, which are positive indicators for phosphorus adsorption. The main minerals observed by XRD were augite, hematite, and sodium titanium silicate. Phosphorus adsorption kinetics have shown that phosphorus is adsorbed on pumice soil following first order kinetics and the adsorption was highly influenced by mass transfer. Approximately 3% of the phosphorus was removed by plant uptake.
The Role and Benefits of Public Interest Organizations in Chemicals Management and How Potential Capacity Constraints of Relevant Groups can be Addressed
(2014) Smith, Mariann L.; Katima, Jamidu H. Y.; Co-Chairs, IPEN
Government and regulatory agency decisions made with the involvement of civil society are much more likely to be put into practice successfully.i Experience shows that it is very difficult to manage or mitigate the impacts of chemicals and hazardous waste without the ability to communicate effectively and equitably involve all those concerned with the issue. Public interest, public health and labour based NGOs have an essential role to play in effective chemical management if the 2020 goal set at WSSD is to be achieved. However, this is not only an issue of obvious benefits, it is also a right enshrined in the Bahia Declaration on Chemical Safety, that is, communities have the “right to participate meaningfully in decisions about chemical safety that affect them.”ii The growing acceptance of public participation in chemical policy making and management is also dependent on developing adequate capacity to support the involvement of civil society. This paper will provide a summary of the role that NGOs play in effective chemical management, with particular focus on capacity building activities and will draw on case studies of effective participation and capacity building models.
Support and Dispersion Effects on Activity of Platinum Catalysts during Wet Oxidation of Organic Wastes
(Springer Link, 2005) Masende, Z. P. G.; Kuster, B. F. M.; Ptasinski, Krzysztof J.; Janssen, Frans J. J. G.; Katima, Jamidu H. Y.; Schouten, J. C.
Catalytic activity of platinum catalysts such as Pt/graphite, Pt/TiO2, Pt/Al2O3, and Pt/active carbon was studied using a slurry phase CSTR. Three model reactions, namely, phenol, maleic acid, and malonic acid oxidation were investigated in the temperature range from 120 to 170 C and at a total reactor pressure of 1.7 MPa. Platinum on graphite was found to be most suitable for aqueous phase oxidation of phenol, maleic acid, and malonic acid. Complete conversion for both phenol oxidation as well as maleic acid oxidation to CO2 was observed with Pt/graphite at stoichiometric oxygen excess close to 0% and at 150 C. Deactivation due to over-oxidation is gradual for Pt/graphite with a metal dispersion of 5.3% as compared to Pt/TiO2, Pt/Al2O3 and Pt/AC, which have metal dispersions of 15.3%, 19.5% and 19.0%, respectively. It was further found that in the presence of Pt/graphite catalyst and oxygen, malonic acid reaction proceeds via non-catalysed decarboxylation, and catalytic decarboxylation to CO2 and acetic acid, and catalytic oxidation to CO2 and H2O. Acetic acid was found to be difficult to oxidise at temperatures below 200 C.
Use of Coupled Dynamic Roughing Filters and Subsurface Horizontal Flow Constructed Wetland System as Appropriate Technologyfor Upgrading Waste Stabilisation Ponds Effluents in Tanzania
(2004) Kimwaga, Richard; Mashauri, Damas A.; Mbwette, T. S. A.; Katima, Jamidu H. Y.; Jørgensen, S. E.
As a part of a comprehensive evaluation of post-treatment techniques for upgrading Waste Stabilization Pond (WSP) effluents, coupled Dynamic Roughing Filters (DyRF) and Subsurface Horizontal Flow Constructed Wetland System (HSSFCW) system was evaluated in Tanzania. Coupled DyRF and HSSFCW were considered as cheaper and yet effective and appropriate alternative technology for upgrading WSP effluents in tropical environments like Tanzania. The main objective of the study was to determine the performance treatment of coupled DyRF and HSSFCW for upgrading WSP effluents with respect to organic compounds (TSS and BOD5) and pathogen (FC). A pilot of coupled DyRF and HSSFCW was constructed at the outlet of the Maturation WSP at the University of Dar es Salaam, Tanzania. The study was carried out in a 2.2 m × 0.7 m × 0.7 m deep DyRF as a first stage, using three different fractions of gravel ranging from 8mm to 32mm, from the top to the bottom respectively. In the second stage, a HSSFCW planted with Phragmites Mauritianus with 0.6-m wide, 1.75-m long and 0.6 - m deep was used. The DyRF – HSSFCW system achieved TSS load reduction by 89.35% which is 15.97 gTSS/m2/day, while BOD5 load reduction by 84.47% which is 9.29 gBOD5/m2/day was achieved. The FC mean removal rate of 99.99 % was also achieved. By achieving mean effluent TSS (12.63  4.12 mg/l), BOD5 (14.12  3.84 mg/l), and mean effluent FC concentrations of 790 FC/100ml it was concluded that application of coupled DyRF and HSSFCW in the tropics can be considered technically one of the most appropriate technology for upgrading WSP effluents.
Waste Stabilization Ponds and Constructed Wetlands Design Manual Acknowledgement
(2005) Kayombo, S.; Mbwette, T. S. A.; Katima, Jamidu H. Y.; Ladegaard, N.; Jørgensen, S. E.
Waste Stabilization Ponds (WSP) and Constructed Wetlands (CW) have proven to be effective alternatives for treating wastewater, and the construction of low energy-consuming ecosystems that use natural processes, in contrast to complex high-maintenance treatment systems, will hopefully lead to more ecologically-sustainable wastewater treatment in the future. CWs and WSPs also have the capability of meeting the demand for a high percentage removal of pathogenic organisms, compared to conventional technologies. CWs and WSPs combined, and joined with other technologies, may be important for even more improved performance of water cleaning systems. WSP’s and CW’s are now well-established methods for wastewater treatment in tropical climates. Their many advantages include: simplicity, low cost, low maintenance, low energy consumption, robustness, and sustainability. While WSPs are most commonly used for treating domestic wastewaters, they are also successfully used for treating industrial wastewater, including water that contains agro-industrial wastes. One of the potential advantages of using constructed wetlands is that they do not allow mosquitoes to breed (sub-surface flow wetland). The process of designing WSPs and wetlands, and predicting their performance, is improving rapidly as we gain more experience with these systems.
Wastewater Treatment for Pollution Control
(2012) Nzabuheraheza, F. D.; Katima, Jamidu H. Y.; Njau, K. N.; Kayombo, S.; Niyigena, N. A.
Performance of a Dynamic Roughing Filter (DRF) coupled with a Horizontal Subsurface Flow Constructed Wetland (HSSFCW) in the treatment of a wastewater was studied in tropical conditions. The results show that in HSSFCW planted with Cyperus papyrus and Phragmites mauritianus in series, the removal rates of TDS, TSS, COD and BOD5 were 72.07%, 80.01%, 81.22% and 78.37%, respectively, while in the second HSSFCW planted with Cyperus papyrus only, the removal rates were 71.00%, 79.00%, 73.76 and 75.78%, respectively. HSSFCW planted with mixed macrophytes, performed better than a HSSFCW planted with single macrophyte. This was attributed to synergetic effects of Cyperus horizontal roots and Phragmites vertical plant roots weaved and entangled in cell 1 providing a good filter mat and a better bacterial attachment. Thus the use of two macrophytes planted in series was recognized to be responsible for better performance of HSSFCW cell 1 in pollutants removal from wastewater.

Browsing by Author "Katima, Jamidu H. Y."

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