Masters Theses and Dissertations

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Ecosystem services for crop protection in bean fields in Moshi rural, along the slopes of Mt. Kilimanjaro Northern Tanzania
(2016-02) Ndakidemi, Baltazar
The natural ecosystem, in and around bean fields potentially offer beneficial services that assist bean productivity. This study was conducted to investigate the distribution of beneficial invertebrates and plants and their conducive environmental conditions in bean fields in Moshi rural, along the slopes of Mt. Kilimanjaro Northern Tanzania. Four farms were chosen on the basis of four factors which were elevation, crop diversity (mixed crop farming), forestation level (farming in grasslands, woodlands and bush land areas), and cropping intensity (most land converted to farming with little bush land, farm-fallow mosaic, small areas of farming with mostly bush/fallow land). Beneficial insects were collected monthly using pan traps. Five traps were placed in the crop plants and the other five traps were placed in the field margin. The insects collected were identified to the functional group level. Plants found associated with beneficial insects were also collected for identification. Monitoring of the insects’ visits to plants was done and photos were taken. It was observed that elevation, time of the year (month), field margin plant species, rainfall and temperature affected the type, richness and diversity of invertebrate communities. There are great spatio-temporal differences in invertebrates’ groups associated with ecosystems services delivery, particularly pollination and pest management functions. The results indicated that there was significant difference (P ≤ .05) among sites in terms of the abundance and richness of invertebrates present. Rainfall and temperature had a potential influence on invertebrates’ groups. In most cases, the highest populations of insects were found in the field margins and edges (P ≤ .05). From this study it can be recommend that it is essential to preserve field margins and edges, cultivate plant species that attract beneficial insects and devise agro-environment strategies to support them.
Constraints and opportunities for coffee productivity on the slopes of mt. Kilimanjaro in the face of climate change
(2016-04) Petro, Abel
Limited scientific information on decreasing productivity of Arabica coffee (Coffea arabica L.) in Tanzania has been observed. Poor agricultural practices, pests, diseases and climate change are among important factors limiting coffee production. This study assessed how the coffee yield gap was influenced by pests, diseases and agricultural practices. Data were collected through interview, measurements and observations methods. Data collected cover demonstration plots and control plots. Results of the analysis show that, coffee banana plus other shade trees is mostly practiced system. Plots were affected by pests and diseases across the altitude gradient. However, the demonstration plots were performing better with mean yield of 807 kg ha-1 and range from 35 to 1800 kg ha-1 as compared to control plots, which had a mean yield of 550 kg ha-1 and range from 18 to 1800 kg ha-1. Large yield gap was partly attributed to the incidence of red spider mite (Tetranychus urticae) and interaction effects of coffee berry disease (Colletotrium caffeanum) and coffee thrips (Diarthrothrips coffeae). Poor agricultural practices especially decreased shade trees density and banana mats density, interactions effects of mulching and weeding and weeding and replanting of coffee trees contributed to the substantial yield gap. In addition mulching, irrigation and shade trees and management are best opportunities to mitigate current global rise in temperature. Thus, it can be concluded that, priorities such as adaptation measures of climate change, pests and diseases control and improved agricultural practices such weeding, fertilizer application, mulching and pruning are recommended to enhance coffee yield.
The use of pesticidal plants as environmental friendly Practice for field and storage pests’ management in Common beans and cowpeas
(2016-04) Mkindi, Angela
Infestation caused by insect pests on legumes has been witnessed to cause losses in the fields during cultivation as well as during storage. Use of pesticidal plants is seen as an alternative option although it is not used widely. Fresh leaf extracts of Tephrosia vogelii, Vernonia amygdalina, Tithonia diversifolia and Lantana camara were evaluated for their efficacy against field insect pests (Aphids (Aphis fabae), Bean leaf beetle(Ootheca bennigseni), Flower (blister) beetles (Mylabris sp), Caterpillars (Anticarsia gemmatalis and Pod suckers) and beneficial insects (Spiders (Araneae), Lady Bird beetles (Coccinella septempunctata), Lacewings(Chrysopidae) and Robbefly (Asilidae)) in common beans (Phaseolus vulgaris L) and Callosobruchus maculatuson stored cowpeas (Vigna unguiculata). Pesticidal plants extracts were prepared in concentrations of (0.1%, 1% and 10% w/v). Weekly spraying of the extracts was done preceded by insects’ assessment one day before each spray. Yield of common beans and persistence of compounds from plants solutions was also evaluated. Pesticidal plants powders were tested on stored cowpea against C.maculatus. The pesticidal plants showed a significant (P ≤ 0.05) ability to reduce insect pests as well as favouring presence of predators and natural enemies in the field. Leaf extracts of T.vogelii was found the most active in the control of field as well as storage insect pests and again contributing to the growth and yield of common beans. Effectiveness of T.vogelii was the highest against C.maculatus by exhibiting less infestation by adult insects, less oviposition and low damage. In this study pesticidal plants were observed to be active against common insects’ pests when compared with untreated. Their effects against beneficial insects and natural enemies were observed to be lower compared with synthetic pesticide treatment.
Risk of heavy metals exposure through consumption of rice from Kahama and Geita districts
(2016-04) Simon, Fides
Heavy metals exposure is associated with various human health problems. This research aimed at determining the levels of heavy metals in paddy soils and in polished rice from villages around the artisanal gold mining areas in Kahama and Geita districts. It also intended to assess the risk of human exposures of heavy metals through rice consumption around the artisanal gold mining areas in Kahama and Geita districts, Tanzania. Twenty soil samples were collected from paddy fields and 20 polished rice samples grown from those fields were taken from the farmers. An additional 20 polished rice samples were collected from farmers in other villages from the same districts. Information about rice cultivation practices and rice consumption were collected from 40 farmers that were randomly selected, 20 from each of the two districts; Kahama and Geita districts, in which the mining areas are located. Chromium (Cr), copper (Cu), zinc (Zn), Mercury (Hg), cadmium (Cd), nickel (Ni), lead (Pb) and arsenic (As) were determined in the soil and rice samples using Energy Dispersive X–ray Florescence spectrometer. Heavy metals exposure through rice consumption, for each of the forty farmers, was determined using deterministic approach. In all the soil samples, concentrations of Cd and Cr were found to be above the maximum limits of 1 mg/kg and 100 mg/kg, respectively, as set by Tanzania Bureau of Standards (TBS). Concentrations of Pb and Cd in all the rice samples were above the maximum limits set by Codex Alimentarius Commission. Forty percent of the farmers consumed rice at least once daily with per capita consumption of 66.8 g per day for Geita district and 74.0 g per day for Kahama district. According to Joint FAO/WHO Expert Committee on Food Additives (JECFA), the estimated daily intake (EDI) for Cd was found to be above tolerable daily intake (TDI) for 95% of all population in both Kahama and Geita districts while the estimated daily intakes (EDIs) for As, Zn and Cu in both Kahama and Geita population were below the TDIs. The results also showed that sites which are closer to the mining activities had higher heavy metal concentration in both rice and soils compared to the sites further away from the mining activity.
Theoretical study of structural and thermodynamic properties of gaseous metal hydrides m2xh4 (m = li, na; x = be, mg)
(2016-04) Shomari, Awadhi
This study aimed to explore the properties of the complex hydrides which seem to be the promising candidates for hydrogen storage materials. The geometrical structure, vibrational spectra and thermodynamic characteristics of the gaseous complex hydrides, MXH3 and M2XH4 (M = Li, Na; X = Be, Mg) and the subunits LiH, NaH, Li2H+, Li2H+, Li2H2, Na2H2, BeH2, MgH2, MgH3−, BeH3− have been investigated. Quantum chemical methods of density functional theory and second order Moller−Plesset perturbation theory have been applied. According to the calculations, three isomers of M2XH4 have been proved to exist, polyhedral of C2v symmetry; two−cycled, D2d and hexagonal shape, C2v. For M2BeH4 polyhedral isomer was found to have the lowest energy and for M2MgH4 was cyclic hexagonal configuration. The abundance of the isomers in vapour was evaluated and the hexagonal isomer was observed to prevail in vapour both for beryllium and magnesium complexes. For smaller hydrides, MXH3, the cyclic equilibrium structure (C2v) was shown to exist, another possible configuration, the linear one (C∞v) was found to be of much higher energy (~130 kJ mol–1). Different pathways of gas−phase and heterophase dissociation reactions were examined; the enthalpies of formation of the complex hydrides were found; 105 ± 26 (LiBeH3), 63 ± 37 (Li2BeH4), 121 ± 27 (NaBeH3), 117 ± 39 (Na2BeH4), 114 ± 13 (LiMgH3), 113 ±12 (Li2MgH4), 162 ± 11 (NaMgH3), and 175 ± 26 (Na2MgH4) (in kJ mol 1). The assessment of thermal stability of the hydrides was done through Gibbs free energies for heterophase decomposition.
Inhibition of aluminium corrosion using carica papaya extracts in acidic media (sulphuric acid and phosphoric acid)
(NM-AIST, 2017-12) Kasuga, Baruku
Corrosion inhibition of aluminium using Carica papaya leaves extracts in 1M H2SO4 and IM H3PO4 was investigated under different temperatures (30, 40 and 500C) and concentrations (from 20-100 v/v %). The inhibitor was found to work by being adsorbed onto the aluminium surface, hence preventing the corrosion of the metal by forming a film that acted like a barrier to the direct contact between the metal and the acids. Gravimetric analysis (Weight loss method) as the main methodology was used throughout the investigation. From the data collected, inhibition efficiency values, adsorption isotherms, kinetic and thermodynamic parameters concerning the adsorption processes were determined; all of these give out important clues on the working ability of the inhibitor. Characterization was also applied using Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FT-IR) spectroscopy. SEM was used to determine the adsorption ability of inhibitor by investigating aluminium coupons through surface profile analysis. The FT-IR machine was used to determine functional groups of the phytochemicals found in C. papaya leaves, inhibitor prepared and those participated in adsorption. Carica papaya leaves extract was found to have a maximum inhibition efficiency of 71.67 % and 56.02 % in H2SO4 and H3PO4 respectively, at the optimal concentration which ranges from 60 to 80 v/v % in both of the media used. Results obtained in this study give hope to corrosion engineers that C. papaya is among of the plants on which its extracts can be used to develop a commercialized natural corrosion inhibitor. This is possible because it has phytochemicals with active functional groups to develop inhibitive properties.
Synthesis of mesoporous carbon from non-biodegradable plastic bags for water purification: methylene blue removal
(NM-AIST, 2017-12) Henry, Kazula
In the present work, the mesoporous carbon materials with pore diameter of 14.2 nm and specific surface areas of 15.18 (m2g-1) identified by Brunauer, Emmett, and Teller (BET) were synthesized from non-biodegradable plastic bags (LDPE) wastes using hard template technique with alpha-manganese (IV) oxide by optimizing plastic scraps to α-MnO2 mass ratio i.e. 1:1, 1:2, and 1:3 and temperature between 400°C and 600°C for each sample. Powder X-ray diffraction (XRD) identified the morphological structural order and textural properties of mesoporous carbon to be amorphous. α-MnO2 as template was prepared following literature procedure by redox titration under reflux heating for 24 h. The mesoporous carbon materials were tested for efficiency on Methylene Blue dye removal whereby samples obtained from plastic scraps to α-MnO2 mass ratios of 1:1, 1:2 and 1:3 at a temperature of 400°C and 600°C were used. Mesoporous carbon from plastic scraps to α- MnO2 mass ratio 1:1 at 600 °C suited for further adsorption experiments in batch technique due to its lower absorbance of 0.143 as compared to the rest samples of plastic scraps to α- MnO2 mass ratio. The Langmuir and Freundlich models were used to analyze the equilibrium data that described how mesoporous carbon interacts with Methylene Blue in aqueous solution in adsorption process. Results revealed that the isotherm data fitted Langmuir model with maximum dye adsorption of 1.644 mg/g at 80°C than Freundlich model whereby, the mesoporous carbon material adsorbed over 80% of the Methylene Blue dye in less than 35 min. The results provided evidence that mesoporous carbon is effective for the removal of dyes from aqueous dye solutions and industrial effluents. Also, the work provides another technique to plastic bags recycling into useful material-mesoporous carbon for industrial dye removal by adsorption.
Investigation of combination effect of natural dye (crocetin) and synthetic dye (indoline d205) for dye sensitized solar cells application
(NM-AIST, 2019-02) Msangi, Abdala
Dye-sensitized solar cells (DSSCs) are reckoned as emerging next-generation solar cells of a high potency. Co-sensitization of dyes facilitates widening of the light absorption range of a sensitizer and is one of possible options to improve overall DSSC performance. In this work, an effect of combination of the natural crocetin dye and synthetic metal free indoline D205 dye was studied. Molecular design of a complex formed from the individual dyes was attempted. The structures, vibrational and electronic spectra of the species were computed by DFT and TD-DFT B3LYP5 methods with mid-sized basis sets. The UV-vis absorption spectra were measured for individual dyes and their mixtures in chloroform solutions. Electron density distribution of the frontier molecular orbitals and energy levels alignment were used for analysis of the electronic spectra and mechanism of transitions. The results indicated that the designed complex can be considered as a potential candidate for DSSCs application with improved properties compared to the individual dyes.
Theoretical and experimental studies of combination of synthetic dye (indoline d131) and natural dye (lawsone) for dye sensitized solar cells applications
(NM-AIST, 2019-02) Madili, Nyanda
Dye sensitized solar cells (DSSCs) convert visible sunlight to electricity using a wide band semiconductor. The DSSCs have attracted many researchers due to their environmental friendliness, low manufacturing cost and simple fabrication process. In the DSSCs, a sensitizer captures sunlight, injects electrons onto the semiconductor and becomes regenerated by electrolyte (redox mediator). Main challenges facing sensitizers relate to dye degradation, low efficiency, as well as high price and toxicity of some dyes. Co-sensitization of dyes which broaden the absorption spectrum of the sensitizer is among the different methods used to enhance the DSSCs efficiency. In this work, the theoretical design of complex molecule (C45H32N2O4) through combination (esterification reaction) of the natural dye lawsone (C10H6O3) and synthetic metal free indoline dye D131 (C35H28N2O2) was performed. The molecular structures, vibration and electronic absorption spectra, excitation energies, and electron transitions of individual dyes and complex molecule were investigated using density functional theory (DFT) and time-dependent (TD-DFT) methods with B3LYP5 functional and 3-21G, 6-31G and 6-31G(d,p) basis sets. For the complex formation reaction, enthalpy, entropy and Gibbs free energy were calculated; the results predicted the reaction to be endothermic and non-spontaneous. Electron density distribution of the frontier and adjacent molecular orbitals and energy levels alignment were used for analysis of the electronic spectra and mechanism of transitions. The results indicated that the designed complex molecule satisfied the requirements for good photosensitizer for DSSCs. The UV-Vis absorption spectra of the individual dyes and their mixture in chloroform solution were measured using spectrophotometer. The solution of the dyes mixture was prepared by combination of the 2.95×10–5 M indoline D131 and 1.15×10–4 M lawsone dye solutions in the ratio of 1:1. Generally despite the slight dissimilarities, the observed bands in the spectrum of the mixture corresponded to those of the individual dyes. Also DSSCs were fabricated using TiO2 electrode with active area of 36 mm2. The DSSCs’ performance was tested at outdoor conditions. The power conversion efficiency (PCE) of the DSSC with lawsone was 0.05%, indoline D131 2.8% and mixture of dyes 0.5%. Thus the PCE of the cell with natural dye was increased in ten times when the synthetic dye added. Combination of naural lawsone dye and indoline dye resulted into wider absorption range compared to those of the individual dyes.
Water quality variation and pollutants transformation in the Nadosoito dam of Arkatani village, Monduli district
(NM-AIST, 2019-02) Eliakimu, Naziel
The study aimed at assessing seasonal dynamics of water quality parameters, transformation of selected pollutants and seasonal diversity of selected microorganisms (Cyanobacteria) in Nadosoito dam of Arkatani Village, Monduli district, Arusha Tanzania. The study aimed at establishing the treatability of the dam water using Inclined Plate Settler (IPS) coupled with settling tank and a constructed wetland, from January to September 2017 capturing the wet months and the driest month. Analysis was carried out as per standard methods for the examination of water and wastewater (APHA 2012). High values of COD, from <0.7 to 87 mg/l, and turbidity, from 204 to 53 300 NTU, were recorded. Turbidity and TSS were highest at the onset of rainfall, and generally declined from the wet to the dry season. The highest levels for both were due to loading materials into the dam. Ammonia concentrations ranged from 0.14 to 270 mg/l and nitrate-nitrogen from 0.6 to 1715 mg/l; they were highest towards the end of wet season in april, while NO2-N was highest (290 mg/l) in the dry season (September). There was a notably high value of Phycocyanin (PC) pigment (19.85 to 495 μg/l) unique to cyanobacteria, well above the WHO alert level of 30 μg/l. PC is associated with a variety of toxins affecting humans and animals. Possible sources of pollutants include; animals’ droppings/urine and runoff from farms applying fertilisers. The results of this study suggest that water treatment systems must be designed to take care of the worst influent water quality conditions.
Removal of hydrogen sulfide and ammonia from biogas using Oldoinyo Lengai Volcanic ash
(NM-AIST, 2019-02) Kandola, Isack
Oldoinyo Lengai mountain located in Northern Tanzania is the only active natrocarbonatite volcano with unusually alkali-rich natrocarbonatites which are not found elsewhere in the world. Volcanic ash formed earlier during eruptions was collected from different sites along the mountain, and its potency to adsorb hydrogen sulfide (H2S) and ammonia (NH3) from biogas was investigated. The samples were calcinated at different temperatures (550–850 °C) and were characterized by X-ray fluorescence, scanning electron microscopy and X-ray diffraction techniques. The on-site adsorption experiments were conducted at the biogas digester at ambient conditions. The calcinated ash was packed into the reactor bed, biogas allowed to pass through the adsorbent, and the inlet and outlet concentrations of H2S and NH3 were measured. The height of the site where the adsorbent was taken from, calcination temperature, biogas flowrate and mass of the adsorbent were variable parameters and found to influence greatly on the efficiency of H2S and NH3 removal. The efficiency increased with calcination temperature raise and mass of adsorbent and decreased with flowrate increase. The samples collected from the top site of the mountain and calcinated at 850 °C exhibited the best sorption performance (SC) of 1.0 g of S/100 g of adsorbent when the mass of adsorbent of 1 g and the biogas flowrate of 0.002 m3/min were used as standard parameters for this study. Chemisorption of H2S was confirmed via bornite and hexahydrite, while CO2, confirmed via trona, pirssonite and nahcolite while NH3 was detected by gas analyzer.
Removal of heavy metals from water by capacitive deionization electrode materials derived from chicken feathers
(NM-AIST, 2019-03) Alfredy, Tusekile
Capacitive deionization (CDI) is an emerging desalination technology based on the principle of electrical double layer capacitors. When the voltage is applied to the surface of the electrodes, electrodes become oppositely charged and ions are adsorbed onto the electrode surfaces under the presence of the electric field, thus producing a purified stream of water. Once the electrodes are saturated with ions, adsorbed ions can desorb from the surface of the electrodes when the applied voltage is reversed or removed. Electrode materials play an important role in CDI performance. To date, the porous carbon derived from biomass shows a competitive advantage in CDI practical applications because of their low production costs, availability, good electrical conductivity, large specific surface areas, and environmental compatibility. In this study a high surface area porous carbons were synthesized from chicken feathers through pyrolysis and KOH activation; the KOH: CF ratio (R) and activation temperature (Ta) were variable parameters. The carbon samples synthesized were characterized by SEM, FTIR spectroscopy and nitrogen adsorption-desorption isotherms at 77 K and desalination experiments were performed by using potentiostat/galvanostat. All samples except the untreated carbon exhibited type IV isotherms demonstrating the existence of mesopores. The lead (Pb2+) removal test was performed with a CDI cell containing the fabricated carbon electrode and 100 mgL-1 Pb (NO3)2 solution; the sample prepared with the ratio R of 1:1 and Ta = 800 K exhibited higher Pb2+ removal efficiency of 81% and electro sorption capacity of 4.1 mgg-1 at the electrode potential 1.2 V and flow rate 5 mLmin-1. Therefore, chicken feather derived carbon (CF) is considered a promising CDI electrode material for the removal of heavy metals from wastewater.
Optimization of biogas production process in solid state digesters: option for minimizing deforestation in dry areas
(NM-AIST, 2019-03) Mahushi, Debora
Questionnaire survey, satellite images of 1987, 1997, 2002 and 2017 were used to assess energy sources, demand and the impact of fuel wood use to forest cover changes in Meru and Mwanga districts. The major energy sources identified in the study areas included cow dung cake, fire wood, charcoal, biogas and liquefied petroleum gas. The total energy demand consumed from these sources were 1400, 6289, 724 and 21 kg per day per total sampled households respectively. The area covered with forest in Meru district was found to be 1510, 1723, 1612 and 1327 ha for 1987, 1997, 2002 and 2017, respectively. Area covered with forest in Mwanga was 31 705, 31 988, 17 939 and 30 960 ha for 1987, 1997, 2002 and 2017 respectively. A batch study to verify the appropriate and optimal mixing ratio of feedstocks was also done. The mixing ratios of cow dung to water ranged from 2:1, 3:1 and 4:1. Total solids determined were 120, 150 and 170 mg/g of fresh sample for the ratios 2:1, 3:1 and 4:1, respectively. Biogas yield for 2:1, 3:1 and 4:1 were 21.4, 22.7 and 46.4 mL/gVS, respectively. These results showed a promising future of the technology which can be adopted by all solid state digester users living in dry areas. Lastly, fuel wood consumption is a real threat to forest, however, use of renewable energy such as biogas could save forest degradation.
Evaluation of rice husk ash and vermiculite materials in the production of ceramic tiles
(NM-AIST, 2019-03) Abeid, Said
The challenging issues in ceramic tiles are low mechanical strength, thermal discomfort and high production costs. Apart from strength the technical functions of floor tiles based on thermal insulation is very important in buildings with human occupation where thermal comfort is required. The objective of this work was to investigate the potential of rice husk ash (RHA) and vermiculite materials in production of ceramic tiles. Initially, a typical ceramic body composed of the mixture of vermiculite and RHA batched with clay, feldspar, quartz and kaolin was prepared. Ceramic bodies were then obtained from this ceramic mixture by pressing samples at a forming pressure of 35 MPa. These bodies were then fired at 1180°C in a laboratory furnace and finally the changes in the physical and mechanical properties caused by the introduction of vermiculite and RHA were tested and evaluated. The chemical composition of the raw samples was analysed by X-ray fluorescence (XRF) while the phase composition was investigated using X-ray diffraction (XRD). The morphology of the powdered samples was studied by using Scanning electron microscopy (SEM). The bulk density and open porosity of the sintered ceramic bodies were evaluated using Archimedes ‘principle while the flexural rupture strength was determined by the three point bending test method. The major chemical compounds in vermiculite raw sample were SiO2, Al2O3 and Fe2O3 while RHA sample was found to contain mainly SiO2. From the XRD analysis, vermiculite sample had crystalline vermiculite while RHA sample had amorphous silica at low temperature below 900oC and crystallized (tridymite) above 900oC. The results from physical, mechanical and thermal properties tests show that with addition of vermiculite and RHA, the percentage of porosity, water absorption, linear shrinkage and thermal insulation capacity were increasing while the bulk density, bending strength, thermal conductivity and effusivity of the fired ceramic bodies decreased. Among the studied compositions apart from the reference sample, tile bodies made from blend containing 20 wt. % vermiculite, 5 wt. % RHA and fired at 1180oC were found to have the best properties for the production of ceramic tiles. For this combination the values for water absorption, porosity, and linear shrinkage, bulk density, bending strength, thermal conductivity and effusivity were 7.60 %, 12.08 %, 3.29 %, 1.88 g/cm3, 18.54 MPa, 0.82 W/m.K, and 1284.33 W1/2/m2K4 respectively. These values were close to the required standards for wall and floor tiles applications. This is an indication that vermiculite and RHA are suitable raw materials for the production of ceramic tiles with a required strength and thermal comfort.
Performance analysis of standalone solar PV panel: case study of Arusha, Tanzania
(NM-AIST, 2019-03) John, Nickson
The purpose of this study was to carry out experimental and theoretical performance analysis of standalone solar Photovoltaic (PV) panel in tropical region. The study concentrated on the influence of poor PV panel positioning especially on the gap between the PV and roof, simulation, and over-shading. Three polycrystalline silicon panels of 100 watts each were selected from different manufacturers in local market. The panels were placed on a simple developed structure of corrugated metal sheet (CMS) roof; solar irradiance, gap between roof and PV panels, and temperature of the panels were the parameters affecting the PV system performance which were monitored. The monitored experimental parameters were used as the variable inputs for the Matlab simulation. In addition, foliage and opaque materials were used for outdoor shading experiments; the shading covered the area between ~3% and ~100% of the PV cells. In the view of findings, the PVs’ extra heat was originating from CMS roof vicinity. The highest temperature attained by the PV panel when it was directly mounted on the roof was 74.5 °C when the ambient temperature was 32 °C. The PVs’ temperature dropped by ~5-9 °C while output power increased by ~5-11% when the gap enlarged from 0 to 50 cm at irradiance of 820 ± 10 Wm-2. Experimental and simulated I-V curves were in good correlation hence validating the findings. Shading caused less energy harvested; the diminution depended on size of shaded cells and available irradiance; the results showed that even small shade can bring the system with no power generated. For common shading, the panels were able to generate a reasonable maximum power (111 to 136 watts) when shaded up to 22 % whilst slightest ranged between 5 watts to 22 watts when shading was 58% and above.
Biodiesel production from parinari curatellifolia seeds oil using basic heterogeneous catalyst derived from tamarindus indica fruit shells
(NM-AIST, 2019-03) Nabora, Christian
Biodiesel is an alternative fuel to mineral diesel. It is produced from abundant and easily available renewable resources of animal fats and vegetable oil. However, the cost of oil feedstock is the major obstacle towards production and commercialization of biodiesel. In this study, an economical and environmental friendly heterogeneous catalyst derived from Tamarindus indica fruit shells (TIFSs) was prepared by calcination method, and it was used in transesterification of Parinari curatellifolia seeds oil (PCSO) to produce biodiesel. The seeds were characterized by having high oil content 36.2%, which makes the feedstock a reasonable candidate for biodiesl production. The catalyst was prepared by calcination of TIFSs at 800 °C in muffle furnace for 3 hours to obtain Tamarindus indica fruit shells ash (TIFSA), a heterogeneous catalyst. Various techniques were used to analyze physicochemical properties of TIFSA. The catalyst exhibits high basic strength (pH>9.7), with the mesoporous structure of pore diameter d = 3.2 nm, high specific area 378.2 m2/g, pore volume of 0.203 cm3/g and CaO crystals as a major active phase of the catalyst. The calcinated catalyst TIFSA was tested in the production of biodiesel through transesterification process using PCSO to obtain Parinari curatellifolia methyl ester (PCUME). During production, the best operating parameters were 5% wt. catalyst loading, 2 hours reaction time and 9:1 methanol to oil molar ratio with the maximum yield of 96.2%. In addition, the catalyst was easily separated and reused again four more times with biodiesel yield above 74%. Furthermore, the produced biodiesel was analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) and composed mainly of unsaturated acids 63.6% and saturated acid 36.39%. Also, fuel properties of produced PCUME were investigated as per ASTM methods and compared to ASTM D6751 standard limits and mineral diesel. Most of the determined fuel properties were observed to be in good agreement with the global standards. Therefore, Parinari curatellifolia seeds oil and Tamarindus indica fruit shell are ideal feedstock for low-cost biodiesel and catalyst production respectively.
Evaluation of dielectric and mechanical strength of high voltage porcelain insulators made from Tanzania ceramic materials
(NM-AIST, 2019-03) Ngayakamo, Blasius
The study has evaluated the dielectric and mechanical strength of high voltage porcelain insulators made from Tanzania local ceramic raw materials. The ceramic raw materials involved were; Pugu Kaolin Same clay, vermiculite, and feldspar. The chemical, mineralogical phases and microstructural characterization of the ceramic raw materials was carried out using the X-ray fluorescence (XRF), X-ray diffraction (XRD), and Scanning electron microscopy (SEM) techniques respectively. The XRF characterization revealed that vermiculite deposit has a higher content of hematite (Fe2O3) compared to other three deposits. Its use for porcelain insulators production can be ruled out unless it is beneficiated as it may affect the composition of the glassy phase at high firing temperature. The X-ray diffraction (XRD) patterns of the raw materials showed that Pugu kaolin and Same clay contain mineral clay kaolinite, quartz and tridymite. Kaolinite is a source of alumina while quartz, and tridymite are sources of silicon dioxide (SiO2) whereas with fluxing oxides (K2Oand Na2O) promote the formation of glassy and mullite phases during the sintering process. Both phases promote densification and vitrification which improve the mechanical and dielectric properties of porcelain insulators. The porcelain samples were made by varying the composition of Pugu kaolin, Same clay, vermiculite, and feldspar. Sixteen porcelain samples with dimensions 160 mm x 40 mm x 10 mm were fabricated by using the dry pressing method. The dried rectangular samples were sintered at 1200 to 1250 °C for 1.5 hrs at the ramp rate of 100C/min. The SEM micrographs showed the progressive change in densification of the porcelain samples during sintering process confirming that densification took place at 12500C. The mechanical and dielectric strength of each porcelain sample was investigated. The porcelain sample with composition, 20 wt% Pugu kaolin, 20 wt% Same clay, and 20 wt% vermiculite and 40 wt% feldspars sintered at 12500C gave the highest dielectric strength of 61.3 kV/mm, bending strength of 30.54 MPa and low water absorption value of 0.36% which satisfied the main requisite properties for high voltage porcelain insulators production. The study showed that, a high-quality high voltage porcelain insulator can be achieved from locally sourced ceramic raw materials from Tanzania.
Risks of sanitation facilities to groundwater pollution in Babati town, Tanzania
(NM-AIST, 2019-03) Pantaleo, Peter A.
Despite of its importance for human consumption groundwater resource is under threat of overexploitation and pollutions. The study to assess the risks of sanitation facilities to groundwater pollution was carried out in the small town of Babati in Manyara, Tanzania. The identification of all the wells in the vicinity of town and their proximity within 60 m radius to each recorded. Water sampling from the selected wells was done and the tests for nitrate, nitrites, total phosphorus, Phosphates, Chemical oxygen demand, fluorides and microbial (Fecal and Total coliforms) levels performed. Methods used included Diazotization, Cadmium reduction, Ascorbic acid, ion selective membrane and membrane filtration (MF) for nitrites, phosphates, fluorides and microbes respectively. Geographic information System (GIS) was used to geo-reference the water sources and water quality data were analyzed by using OriginPro8 SR0 v8.0724 software. The results revealed higher fecal coliform in shallow wells both used bucket and pumps to draw water. The maximum mean level of FC was 85.81CFU/100 mg/l and NO3 was 65.48 mg-NO3/l. Boreholes indicated lower nitrate levels than National and WHO standards and were all free of fecal coliforms. Other parameters were all within recommended limits for all wells tested. The evaluation of the potential contamination pathways revealed that the shallow well depth mean value was 10.40±0.30 m (N=366 P˂0.05), 70% were unlined and 19% were uncovered. About 74% of the wells were within 30m of sanitation facilities, of which 60% were traditional pit latrines. The findings reveal that most shallow wells (64%) are polluted and the aquifer of Babati classified as a moderately vulnerable to contaminations. The results showed a very high risk in some parts of Kiongozi in Maisaka ward and some other parts in Babati and Bagara wards. Most location of the locations found with shallowest well depths also indicated the increased risk of groundwater pollution (Fig. 17). Therefore it is prudent that the community avoids relying on shallow wells and boiling of domestic water before consumption. Authority should also seek for a simple and affordable way/strategy to that will improve sanitation facility designs, distributions. Also to establish adequate regulations to overcome environmental contamination challenges, persistence pollutant chemicals and resistance antibiotics through drinking water sources in developing countries like Tanzania.
Simulation, performance analysis and improvements of solar farm installation in Tanzania
(NM-AIST, 2019-04) Haji, Mohammed
With the environmental advantages of solar energy, the use of solar photovoltaic (PV) in electricity generation is encouraged by Tanzanian governments, however, the number of institutions that are benefiting from installing grid-connected PV system and the electricity being generated are not clearly documented. Thus, in this study simulation, performance analysis and improvements of grid connected and standby PV system at Karume Institute of Science and Technology (KIST, Zanzibar) as well as Nelson Mandela African Institution of Science and Technology NM-AIST, Arusha) have been carried out. The analysis utilizes the power load data from the two different locations in Tanzania. The data (current and voltages) were obtained using the data loggers and the outputs such as power and energy were calculated. In addition, HOMER (Hybrid Optimization Model for Electric Renewables) software developed by the National Renewable Energy Laboratory (NREL), Department of Energy, United States of America was used to design and evaluate technical-performance and financial- options for off-grid and on-grid power systems for remote, stand-alone and distributed generation applications. Therefore, in this study, the distance from the roof to the panel, reflection and inclination angles were observed to have significant impact on the performance of PV panels. High performance was recorded when the distance from the roof to the panel was 20 cm and the reflection and inclination angles were 45° and 20° respectively at KIST. The spacing provided good natural cooling of the panel while at the optimal reflection and inclination angles the solar intensity was improved due to the decreased angle of incidence. Additionally, the HOMER simulated results indicated that PV and grid combination at KIST exhibited the saving of 39.8% of the total energy consumption per day as compared to when only grid power is used, the cost of energy was reduced from $0.1877 to $0.113. In the other hand, the combination of grid, battery and PV systems at NM-AIST recorded the saving of 50.5% of energy usage per day, the cost of energy was reduced from $0.22 849 to $0.113.
Sources and hydro-geochemical characteristics of lake Duluti waters, Tanzania
(NM-AIST, 2019-11) Mduma, Nancy P.
Water chemistry, and stable isotopes of oxygen and hydrogen ( 18O and 2H), were used collectively to characterize and quantify Lake Duluti (L. Duluti) – groundwater interaction. Physico-chemical parameters including temperature, pH, electrical conductivity, dissolved oxygen, total dissolved solids, alkalinity, major cations and anions were used to determine chemical characteristics of the lake and to assess its relationship with groundwater sources. Furthermore, water balance approaches were used to estimate surrounding ground-water exchange with L. Duluti and addressing the role of groundwater on lake hydrological system. Physico-chemical parameters results showed abundance of major cations and anions in the lake water in the following order Na+ >Ca2+>K + >Mg2+ and HCO3 - >Cl- >F- >SO4 2- >NO3 - respectivelly. Water in L. Duluti was found to be of predominantly Na-HCO3 type while that from springs and boreholes was of the Ca-HCO3 and Ca-Na-HCO3-types, respectively. Isotopic results indicated that evaporation-induced isotopic enrichment prevailed in L. Duluti and contributed significantly to water loss from the lake. The isotopic composition of oxygen (δ 18O) of lake water averaged sigma notation(‰) of 6.1 ‰ while that of well/boreles and spings averaged -1.2 ‰ and -2.1 ‰ respectively. Similarly, the isotopic composition of hydrogen (δD) of lake water averaged 24.2 ‰ while that of well/boreles and spings averaged -12.9 ‰ and -12.2 ‰ respectively. Stable isotope calculations suggested that L. Duluti loses water to the aquifer and it is more recharged by the groundwater relative to precipitation and surface runoff. Groundwater inflow to the lake is approximately 2 430 960 meter cubic per year (m 3 /yr) while lake water discharge to groundwater is 2 902 620 m 3 /yr. The lake is recharged through precipitation by 612 000 m 3 /yr. Hence, groundwater plays a major role in the hydrological system of L. Duluti. Based on these findings from the study, there is more groundwater outflow than inflow, hence citing of boreholes in the area should be properly done so as to maintain the state of the lake or groundwater aquifers. In the long run, pumping water from the lake may also introduce more groundwater inflows and less outflows. The findings in this research are of assistance to policy makers and management personnel to make use of the information provided for better management of the lake water. The information will also enable the Arusha water supply and sewerage authority to know the hydrological state of L. Duluti.

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