Masters Theses and Dissertations

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Optimal design and analysis of a grid- connected hybrid renewable energy system using homer pro: a case study of Tumbatu island, Zanzibar
(NM-AIST, 2024-08) Said, Thani
This study addresses the issue of quality electricity access on Tumbatu Island in Tanzania, with a specific focus on enhancing the high-voltage (HV) transmission line. While many studies concentrate on low-voltage (LV) transmission lines, HV lines play a crucial role and merit more attention. Therefore, the objective of the study is to improve the voltage profile of the HV transmission line through a hybrid energy system comprising solar PV, wind turbines, and batteries. This effort begins with an analysis of the total power demand and consumption, which are essential for designing an effective energy system. The study employs HOMER Pro to simulate various hybrid system configurations. The simulation findings indicate that integrating solar PV, wind turbines, and HV lines leads to a significant enhancement in the voltage profile, raising it from 29.6 kV to 31.23 kV during peak demand. This solution demonstrates the highest economic viability, boasting the lowest Net Present Cost (NPC) of USD 4 003 851 and a relatively short payback period (PB) of 3.79 years. Implementing this hybrid system not only meets the island's energy needs but also contributes to global pollution reduction and minimizes electricity costs for the population of Tumbatu Island. Furthermore, it addresses the demand for clean energy, emphasizing its role in achieving sustainable and accessible electricity in Sub-Saharan Africa and beyond
Fluoride and pathogens removal from water using combined electrocoagulation-inline-electrolytic disinfection process
(NM-AIST, 2024-08) Njau, Oscar
The consecutive removal of fluoride (defluoridation) and pathogens (disinfection) in drinking water through combined electrocoagulation-inline-electrolytic disinfection (EC–ECl2) process with aluminum and dimension-stable mixed oxide electrodes was reported in this study. Laboratory trials have been conducted on the effects of flow rate, initial pH, current density, and supporting electrolytes for defluoridation and disinfection processes. The results have shown that with a flow rate of 10 L/h, initial pH of 6, the current density of 9.4 mA/cm2 (EC cell) and 3.1 mA/cm2 (ECl2 cell), supporting electrolyte concentration of 165 mg/L, and electrolysis time of 50 min, a defluoridation rate of 88% (initial concentration of 12.3 mg/L) and complete disinfection (initial fecal coliforms of 19,700 colony-forming units per 100 mL (CFU/100 mL)) can be reached. The final concentration of fluoride and pathogens in treated water was 1.44 mg/L and 0 CFU/100 mL, which are within the acceptable limit of the World Health Organization and the Tanzania Bureau of Standards of 1.5 mg/L and 0 CFU/100 mL, respectively. The EC–ECl2 system is a promising approach for consecutive defluoridation and disinfection of water to save millions from fluorosis and waterborne diseases. However, optimization potential with regard to energy efficiency and system complexity were identified.
Assessment of Mpanda groundwater contamination and the effectiveness of the baobab seeds-derived biochar for iron removal from groundwater
(NM-AIST, 2024-08) Mkelemi, Magdalena
Groundwater in Mpanda District, Tanzania, faces excessive iron content, causing a reddish brown colouration due to oxidized iron species. The present study evaluated Mpanda groundwater contamination and the effectiveness of baobab seeds-derived biochar for iron removal from groundwater. First, the physicochemical quality of groundwater was investigated. Nineteen boreholes were randomly selected for assessment, with samples collected in rainy and dry seasons. The study revealed significant variations in groundwater quality both between seasons and among boreholes. Temperature, total dissolved solids, electrical conductivity, lead, iron and manganese exceeding World Health Organization and Tanzania Bureau of Standards limits in some boreholes; necessitating water treatment for human use. Second, the effectiveness of baobab seeds-derived biochar for iron removal from groundwater was assessed. Baobab seeds, were sun-dried, oven dried at 105 ºC, carbonized at 700 ºC, and ground into fine powder. The influence of pH, time, temperature and dose of biochar on the iron removal from groundwater was assessed. Six 1000 mL beakers were filled with groundwater and adsorbent doses of 0.6 g/L, 1.2 g/L, 1.8 g/L, 2.4 g/L, and 3.0 g/L were added into five beakers with the sixth serving as a control. The highest removal efficiency of iron was observed within 5.0-8.0 pH range. Over time, the removal efficiency increased to 87% at 120 minutes and 3.0 g dose, with an initial iron concentration of 5.88 mg/L and residual concentration of 0.76 mg/L. Baobab seeds-derived biochar showed promising efficiency in removing iron ions and is recommended for sustainable iron removal from groundwater.
Design of an evaporative cooling system integrated with ultraviolet light for preservation of fruits and vegetables at variable tropical weather conditions: a case study of Arusha, Tanzania
(NM-AIST, 2024-07) Gunda, John
Problems with fruits and vegetables spoiling after harvest are particularly acute in tropical regions. This research presents the design, construction, and performance assessment of a solar-powered evaporative cooling storage system incorporating ultraviolet radiation (UV) to preserve foods susceptible to spoilage. Local materials, including sisal, sponge, and bricks, were used to construct the cooling chamber with a UV bulb. We measured the system's efficiency in both sunny and overcast tropical weather conditions by looking at how much air temperature was reduced, how much relative humidity was increased, and how much electricity was used for evaporative cooling. According to research, fruits and vegetables may be kept fresh for much longer after activating the UV light. This method may keep perishable goods for up to 21 days under UV light and 9 days without. An average temperature drop of 5.0℃ and an increase in relative humidity result from active system operation on sunny days. In contrast, the cooling effect is minimal on overcast days, leading to a relative humidity rise of 18% and a temperature drop of around 3.5℃. Based on these results, a solar-powered evaporative cooling system with UV radiation treatment might be a good way to reduce tropical post-harvest losses.
Naturally occurring metal oxides from rocks as capacitive deionization electrode materials for antibacterial activities
(NM-AIST, 2024-01) Alphonce, Furaha
The availability of clean and safe drinking water remains a prominent challenge in most parts of the world. Drinking water should be free from harmful microorganisms, salt as well as other organic and inorganic contaminants that need attention as they have health impacts on human beings. In the present study, naturally occurring metal oxides from rocks embedded in activated carbon (AC/MO) electrodes were evaluated for desalination and anti-bacterial activities against gram-negative (Escherichia coli) and gram-positive (Salmonella aureus) bacteria using capacitive deionization (CDI) technique. The AC/MO electrodes were fabricated for desalination and disinfection of natural and synthetic water with the CDI method. The AC/MO electrode materials were characterized by Scanning Electron Microscope (SEM), Energy Dispersive X-Ray (EDX), X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), and Fourier-Transform-Infrared spectroscopy (FTIR), and Transmission Electron Microscope (TEM) which affirm the formation of disinfecting electrode materials. The desalination and disinfection CDI experiments were conducted by carrying out batch mode laboratory CDI system using natural water collected from the Nduruma stream (natural water) while applying a potential difference of 1.2V for 4 h. It was found that the AC/MO CDI electrodes achieved 100 ± 0.42% E. coli and 60 ± 0.53% S. aureus bacteria removal and 46.85 ± 0.49% salt removal efficiency. The bacterial disinfection mechanism is through the CDI process and physical adsorption. Therefore, this study presents the AC/MO electrode material which can be considered as an appreciable anti-bacterial agent for the CDI performance
The removal of arsenic from synthetic solution using a sand filter coupled with zero valent iron
(NM-AIST, 2024-07) Edward, Daniel
Contamination of groundwater with arsenic (As) poses a serious risk to public health, demanding the development of effective remediation technology. This study investigated the use of sand filters coupled with of zero-valent iron (ZVI) for removal of arsenic from synthetic solutions as the function of ZVI dosage and contact time. ZVI materials, including iron wool, iron fillings, and iron nails, were investigated and compared for their efficacy in removing As from synthetic solutions. The experiment employed synthetic solutions spiked with As compounds (set to be 1000 µg/L) to simulate contaminated groundwater scenarios. The concentrations of As in the influent and effluent samples were used to calculate the efficiency. The findings indicate that all three forms of ZVI tested exhibited significant As removal capabilities. Iron wool, iron fillings, and iron nails demonstrated varying efficiencies, likely influenced by their surface area, reactivity, and specific surface chemistry. According to the findings, iron wool-containing sand filter was more effective at removing As than iron filings and iron nails. As removal efficiency increased with increase in ZVI dose. The results show that As can effectively be removed from water in the first 48h. The highest removal efficiency was 99.6% and the lowest removal efficiency was 82.7%. These results suggest that ZVI materials could be promising candidates for practical applications in As-contaminated groundwater treatment systems. This study contributes valuable insights into the use of inexpensive and widely available ZVI materials for As remediation, highlighting their potential as sustainable solutions for addressing water quality challenges.
Effect of irrigation water cut-off position along furrows on water saving and productivity
(NM-AIST, 2024-08) Banda, Benjamin
Despite being widely practised technique by smallholder farmers, cut-off technique continues to register low productivity and has not been adequately investigated to improve the status quo. This study aimed to investigate the scenarios to improve water use efficiency and productivity for the cut-off irrigation technique. Three cut-off treatments where water supply was stopped with the advance phases reaching 75%, 80% and 90% of furrow length were investigated with eight irrigation events. The crop grown under these scenarios was maize. Soil analysisshowed that in all the three subplots, the soils were sandy loam with an average of 69% sand and 31% silt. The initial soil moisture content was 14% and other corresponding moisture properties were 33.5 mm/hr infiltration rate, 9% permanent wilting point and 12% available moisture. Mean application efficiencies with significant differences (P<0.05) of 70%, 66.4% and 63% were achieved for the 75%, 80% and 90% length treatments respectively. Corresponding uniformities and water productivities of 90%, 89.9%, 89.2% and 1.54 kg/m3 , 1.38 kg/m3 , 1.18 kg/m3 respectively were obtained with no significant difference (P>0.05). The results demonstrated the 75% c u t - o f f has the potential of saving water of up to 26% without compromising water productivity. It is recommended therefore that the 75% cut-off position of water supply be promoted among the smallholder farmers and that research studies should now be carried out for less than 75% cut-offs
The hydrochemical evolution and water balance of the emakat lake in the northern crater highland of Tanzania
(NM-AIST, 2023-07) Lucas, Godwin
This study aimed to ascertain the hydrochemical evolution and water balance of Emakat Lake, of the Empakaai Crater. Water and rock samples were collected from the lake and springs on the inner and outer crater rims, and at the foot of the Empakaai Crater. The results showed that the lake is a highly alkaline (pH > 10) and saline (electrical conductivity (EC) = 28,860 - 29,460 μs/cm) with the concentration of total dissolved solids (TDS) ranging from14,432 to 14723 mg/L. Springs exhibited lower pH (6.85 - 8.69), EC (562 - 1584 μs/cm) and TDS (276 - 1016 mg/L). The dominant ions in Emakat Lake were Na+ and CO3 2-+HCO3 - which occupy about 80% and 85% of the cation and anion phases with ion distribution of Na+ > K+ > Ca2+ > Mg2+ and (CO3 2- + HCO3 - ) > Cl- >SO4 2- > F- > NO3- > PO4 3- . Piper, chloro-alkaline indices, Chadha, and Gibbs plots revealed that Na-K-HCO3 water type dominated Emakat Lake, and a majority of springs exhibited mixing characteristic water type. Base ion-exchange dominated the hydrochemical evolution of both lake and springs, influenced by evaporation and water-rock interaction for the lake and springs respectively. The water balance of Emakat Lake was highly influenced by groundwater flow which accounted for 49% of the inflow and 56% of the outflow. This suggest that Emakat Lake plays a major role in the hydrological system in the area alongside the springs which are the sources of the major rivers of Engaruka and Engaresero.
Investigating the potential of producing eco-friendly liquid biofertilizer from domestic wastewater
(NM-AIST, 2023-08) Muga, Elly
Water bodies experience environmental challenges such as eutrophication due to poor management of domestic wastewater in developing countries. Meanwhile, the explosion in population of the world has resulted in a 1.8 percent annual increase in demand for fertilizers that contain important nutrients. Although domestic wastewater contains nutrients (nitrogen, phosphorus, and potassium) that can be used in agriculture, its recovery is still a challenge. Some of the potential methods, such as the use of struvite precipitate in recovering nutrients from wastewater, are not only costly but also introduce a second pollutant into the ecosystem. The ion exchange method can recover phosphorus from wastewater; however, its effectiveness is limited by the presence of competing anions, such as sulfates. Freeze concentration method is one of the potential techniques for recovering nutrients from wastewater. However, its optimal condition such as temperature and time in recovering nutrients from domestic wastewater is not well known by researchers. In this study, method of freeze concentration was studied to establish its optimal condition in recovering nitrate nitrogen and phosphate nutrients from domestic wastewater processed in anaerobic digester. Frozen liquid and unfrozen concentrated liquid are produced. The effect of freezing temperature from -10°C to -80°C, freezing time from 1 hour to 8 hours and energy consumption on the nutrient recovery were investigated. Freezing temperature of -20°C, cooling time of 7 hours and energy consumption of 0.197 kWh/L resulted in the highest nitrate-nitrogen and phosphate nutrient recovery value of 1.114 and 4.667 respectively at the inlet of anaerobic digester 1, 1.325 and 4.975 respectively at the outlet of anaerobic digester 1, 1.099 and 4.859 respectively at the inlet of anaerobic digester 2, 1.132 and 4.755 respectively at the outlet of anaerobic digester 2 and for gravel filter at the outlet the values where 1.111 and 4.861 respectively. This study shows that, when the freeze concentration method is used with the right temperature, time, and energy, a significant amount of nutrients may be recovered from domestic wastewater that can be used as biofertilizer.
Influence of duct configurations on the performance of solar-assisted heat pump dryer for drying tobacco leaves
(NM-AIST, 2023-08) Suleiman, Salum
nadequate storage facilities and preservation techniques lead to a decrease in the quality of agricultural products. Application of modern processing techniques has reduced post-harvest losses of agricultural crops. Drying was done to lower the moisture content for preservation. Tobacco drying requires massive amounts of wood, which has negative effects on the environment such as pollution, deforestation, and desertification. In the present study, a solar- assisted heat pump dryer (SAHPD) has been designed, fabricated and tested its performances as an alternative drying technology for tobacco leaves. The hot air generated from the solar collector and condenser unit of the heat pump was used as a source of heat in the drying chamber. In this study, we investigated thermal performance of three duct configurations of the SAHPD system (open, partially closed and completely closed) to establish the best configuration for drying tobacco leaves where did not conducted before. The average drying temperature was found to be 66, 64 and 60°C; the coefficient of performance of the heat pump was 3.4, 3.2 and 3.0; the heat energy contribution from the condenser was 98.7, 98.5 and 98.3%; and electrical energy consumption was 2.3, 2.8 and 2.6 kWh, for the open, partially and completely closed systems, respectively. Based on these results, the open system demonstrated the best performance. According to the study's findings, SAHPD has been shown to be an energy-efficient method of drying tobacco leaves and environmentally friendly as opposed to the conventional use of wood fuel, which results in environmental pollution, desertification, and deforestation. Future studies should focus on inclusive investigation of the life cycle and technoeconomic
A quantity-quality tradeoff: Water quality and poverty assessment of drinking water sources in Southern Tanzania
(NM-AIST, 2023-06) Maungu, Nancy
Regardless of being essential for human survival, access to potable water is still a problem in many rural African communities with increasing exposure to waterborne illnesses. This study aimed at establishing accessible quality water sources in 5 drinking water sources in rural southern Tanzania. The water quality index (WQI) and water poverty index (WPI) were utilized to grade and measure the water quality and water stress respectively. The 26 households participated in a socioeconomic survey to gauge the water accessibility in relation to four WPI factors viz., preference, accessibility (distance), quality, and seasonal availability. Results from the WPI computed data revealed that all the investigated water sources possessed poor quality with 222.5 and 112 for surface water and shallow wells (>50 excellent, <300 unsuitable). The WPI scores for shallow wells were safer than surface water at 45.7 as contrasted to 33.8 for surface water (0- poorest levels, 100-best levels). This study concluded that, in this area, shallow wells have more secure water in terms of quality and accessibility. Health data from Milola ward showed high occurrences of water borne diseases. This study recommends urgent water treatment intervention by the responsible stakeholders to avail clean, reliable, and accessible drinking water for vulnerable communities.
Experimental investigation of the variation in the potential of selected natural rocks as thermal energy storage materials
(NM-AIST, 2023-08) Kakoko, Lilian
Fossil fuels cause greenhouse gas emissions and are perceived to deplete, hence the use of renewable energy is considered crucial. These renewables include the use of solar thermal energy in concentrated solar power (CSP) generation and solar drying applications. However, solar energy is intermittent, thus solved by incorporating thermal energy storage (TES) to store heat energy for future use. However, the most common weaknesses in TES materials are high cost of investment, environmentally unfriendly and are not locally available. Using natural rocks is recommended as they are readily available, affordable and efficient TES materials for solar drying applications at 40-75 °C and concentrated solar power generation at 500-600°C. Despite its generational use in thermal applications, soapstone rock has not been studied as a TES material. Moreover, site specificity has not been investigated in spite of being stated to affect the potential of rocks in TES. Therefore, this study investigates the potential of soapstone rock as a TES material, and the influence of the geological-tectonic settings. In the present study, experimental characterization of selected natural rocks namely soapstone and granite, was done to investigate their thermal properties at 20-950°C. Conclusively, soapstone rock from the Craton geo-tectonic setting had the best properties and it had the highest young’s modulus, thermal capacity, thermal conductivity and had a weight loss of only 0.75 % at 900°C. At high temperatures, it did not show visible fracture. Moreover, soapstone and granite from the Craton and Usagaran geo-tectonic settings exhibit significant differences
Rheological and physicochemical analysis of non- edible oils used for biodiesel production
(NM-AIST, 2023-07) Zakaria, Francisca
The knowledge of the physicochemical and rheological flow characteristics of biodiesel feedstock is used for quality control in production, storage and transportation processes. Moreover, the knowledge is applied in redesigning and optimizing facilities that can be used for manufacturing, storage and transportation of the fuel. Non-edible oils analysed in the present study were Cashew Nut Shell Liquid (CNSL), Castor Oil (CO), croton megalocarpus oil (CMO), podocarpus usambarensis oil (PUO) and Thevetia peruviana oil (TPO). Free fatty acid, acid value, saponification value, peroxide value, iodine value, specific gravity and moisture content were determined by following the recommended Association of Official Analytical Chemists (AOAC) methods of analysing physicochemical characteristics. Physicochemical results show that all the selected non-edible vegetable oils with an exception of CNSL, do not require any further treatment. However, due to high Free Fatty Acid (FFA) content in CNSL, direct biodiesel production from the feedstock would be a challenge hence further treatment to reduce the acidity of the feedstock is essential. Rheological flow parameters were analysed using VT-550 Thermo Haake Viscotester monitored by a Rheowin Job manager. The pre-set parameters in the Viscotester were the shear rate and temperature. The shear rate was increased uniformly from 5 𝑠−1 –100 𝑠−1 in 60 seconds at 30-60˚C. Regardless of the analysis temperature, all oils exhibited Newtonian flow behavior, indicating that the viscosity of the oil remained uniform at a constant temperature. The experimental data were fitted into rheological models: Newton, Bingham, Oswald de Waele (power-law), and Herschel Bulkley using Rheowin data evaluation software. The results revealed that Newton and Oswald de Waele models were appropriate to represent the flow behaviour of the oils with the fit of R2 ≥ 0.990.
Impacts of irrigation water quality, associated soils characteristics and on-farm practices on paddy yields
(NM-AIST, 2022-07) Mpanda, Fridolin
In this study, the impacts of irrigation water quality, soil characteristics and on-farm practices on paddy yields were investigated. Standard spectroscopy and spectrometry methods were used to analyze irrigation water and irrigated soil samples. The irrigation water had sodium adsorption (SAR) values ranging from 0 to 3. The corresponding electrical conductivity (EC) values were between 0.2 and 0.7 dS/m and accounted for 14% of all samples hence posing slight to moderate infiltration problem. Neither sodium nor chloride levels were high enough to cause toxicity problems in the irrigation water. For boron, 54% of the samples was found to have moderate toxicity whereas ~14% of the samples indicated severe boron toxicity in the irrigation water. For bicarbonate, about 86 and 14% of the irrigation water indicated slight-to moderate and severe potential detrimental effect to plant growth, respectively. The trace elements Fe2+, Zn2+, Cu2+, Mn2+, B, As, Cd, Cr2+, Pb2+, Ni2+, and Al3+ in the irrigation water samples were too low to cause any harmful effect. Although soil EC (0.2 to 1.9dS/m), organic carbon (OC) (0.1 to 2.4%) and pH (6.0 to 8.5) indicated favorable levels, there were significant variations in soil Fe (2.6 to 169.5 mg/kg) and Zn (3.9 to 204.1 mg/kg). The mean value of Fe in soils was 19.8 mg/kg. Soils indicated signs of Fe-deficiency. High variabilities were also found in the total N (86 to 2155 mg/kg) content of the studied paddy soils. The levels of phosphorus (Olson P, mean 224.2 ± 149.4 mg/kg) were found to be too high compared to what is reported as normal in similar studies. There might be unsustainable and excessive application of P-containing inputs in the studied area. Furthermore, a low soil K content was observed in the analyzed soil samples. The present study recommends that regular control of irrigation water HCO3 - , EC and controlling soil pH levels as well as adoption of standard on-farm practices following of crop calendar, proper application of fertilizers. Availability of extension officers to advice farmers is highly recommended.
Water use and crop water productivity in farmer managed irrigation schemes across agro ecological zones of usa river catchment
(NM-AIST, 2021-11) Haymale, Humuri
The Usa River Catchment is the potential area dealing with traditional irrigated agriculture. This study aims to estimate the amount of water abstracted for and yield that reflect water values to enhance crop water productivity. The main objective of this study was to assess water use and crop water productivity in farmer managed irrigation schemes across agro-ecological zones of Usa River Catchment. The specific objectives were: (a) to determine crop water productivity, (b) to determine factors causing the variation of crop water productivity, and (c) conveyance efficiencies in the traditional irrigation schemes in the Catchment. The secondary and primary data were collected and analysed using Statistical Package for Social Science (SPSS) and R-program. Consequently, the average productivity obtained were 2.3 kg/ha, 1.9 kg/ha, and 3.4 kg/ha of maize for downstream, midstream, and upstream zones respectively. Similarly, at twenty (20) furrows, the conveyances efficiency of the water channels was 72%, which reflects the water loss in the conveyances of 28% on average. However, the water abstractions were 3500 L/s more than the permitted amount of 2856.2 L/s, which was against the established water abstraction laws and regulations leading to water shortage in downstream of the catchment. Traditional irrigation infrastructure in this study contributed more water losses and low crop water productivity compared to global average water losses in the conveyance and crop water productivity in irrigation schemes. This study recommends weirs with water control structures intakes to be constructed, canal lining and improve irrigation water management.
Evaluation of recharge areas of Arusha aquifer, northern Tanzania: application of water isotope tracers
(NM-AIST, 2022-01) Lugodisha, Innocent
In Arusha urban, northern Tanzania, groundwater contributes about 80% of the water supply. However, elevated fluoride levels and evidence of anthropogenic pollution have been reported in the groundwater around Mount Meru which is a water source for Arusha urban. This study aims at understanding the recharge areas and flow pathways of groundwater in what has been a poorly monitored area. The study uses the isotopic ratio of oxygen and hydrogen to estimate the groundwater recharge area and flow pathway. The results show the recharge elevation of groundwater is between 1800 and 3500 m above mean sea level on the slopes of Mount Meru. Fluoride showed an increasing trend with elevation while NO3 - decreased with sampling altitude. The high content of NO3 - and Cl in water samples from sources in the lower part of the study area is evidence of anthropogenic contamination. The average fluoride contents in the study area are 5.3 ± 0.4 mg/L greater than the limits of 1.5 mg/L and 4 mg/L set by the World Health Organization (WHO) and Tanzania respectively. The nitrate concentration of 83.9 mg/L at the lower elevation areas (<1400 m above mean sea level) exceeds the 50 mg/L WHO limit. The relationship of F- with δ18O and NO3 - suggests the leaching of fluoride in high altitudes and dilution in lower altitudes. Two flow pathways were identified, that start from the recharge area in the south and south-western slopes of Mount Meru towards the southern part of Arusha urban.
Diversity and quantity of macro-and microplastics in irrigation farms sourcing water from an urban river: a case of Arusha Tanzania
(NM-AIST, 2021-10) Kundu, Mercy
Increased concentration of plastics in urban rivers and agricultural farms causes degradation of river system functionality and reduces the productivity of agricultural soils, respectively. This study assessed the quantity and types of macro-and microplastics found in dependent smallholder irrigation farms downstream of Arusha city in Tanzania. The microplastics' concentration from the sites was visualized using dissecting microscope 40X, enumerated and categorized based on the shape, color, and sizes for soil samples. Then the suspected materials’ spectral were determined using the Attenuated Total Reflectance- Fourier Transform Infrared (ATR-FTIR). Afterwards, the confirmations and identifications of the polymers' types from spectral were confirmed using SiMPle Software. The average microplastic from the water column was 0.57 ± 0.27 items L-1 , sediment 0.17± 0.07 items g-1, while in the irrigation farms ranged from 102 to 728 items with a mean of 0.69 ± 0.35 items g-1 . However, no international standards have been developed to ascertain the pollution level, but the reported values are unsafe to the environment. Other studies conducted in similar conditions reported mean values within the range of values found in this study and more. Polyethylene was the dominating type of macroplastics evaluated from riverbanks and irrigation farms with a frequency of occurrence 100 %, while polystyrene was abundant in all microplastics samples. Farms adjacent to the irrigation canal had a greater number of microplastics and macroplastics. Thus this study reveals urban rivers as the primary sources of plastics pollution in the irrigation farms situated in flood-prone zones.
The potential of water resources contamination around a large-scale gold mine
(NM-AIST, 2022-05) Musiba, Musiba
This study used the hydro-chemical properties and isotopic signatures of water to understand the main sources of deterioration of water quality around the North Mara gold mine in Tarime District, Mara Region. The chemical and isotopic signatures of the surface and groundwater were used in understanding the origin, flow pattern, residence times, and vulnerability to pollution. Most samples that were located downstream, western side of the mine tailings dam were slightly acidic with pH as low as 4.6 and enriched with stable isotopes. Most samples with elevated concentrations of Na+ , Cl- , SO4 2- and NO3 - could not be isotopically linked with the local geochemistry, but the observed water chemistry was controlled by evaporation and anthropogenic effects. The Piper trilinear diagram showed Ca and Mg cations dominance, while bicarbonates and sulfates dominated the anions. The heavy metals, Pb and Hg levels (mean 70.29 and 17.95 µg/L, respectively) were all higher than the levels recommended in both the World Health Organization (WHO) and Tanzanian drinking water guidelines. The low pH values and elevated concentrations of cyanides, heavy metals, and metalloids were probably associated with mining activities. The radioactive isotope results indicated the vulnerability of the water to recent contamination that could be attributed to near-surface anthropogenic activities. Moreover, stable isotopic studies indicated the pollutants-carrying water flow pattern was from the eastern to the western side of the study area. Lowland samples had higher tritium activities than the highland ones. Therefore, the present study concludes that groundwater recharge from recent local precipitation may have an impact on the sources studied and the use of shallow dug out wells should be minimized.
Sustainability assessment of existing septic systems in residential buildings: a case study of Mwanza city, Tanzania
(NM-AIST, 2022-07) Salvatory, Siliacus
Septic system (SS) is the oldest anaerobic wastewater treatment system still widely employed today in suburban and urban areas. The sustainability of SS in developing countries, including Tanzania, is restricted by several constraints (e.g., poor installation and hydraulic overloading (technical issues), poor resource recovery practices (economic issue), maintenance and awareness (social issues), etc.). Efforts have been done to improve SSs’ sustainability, but the improvement is hindered by a lack of information on how to guarantee SSs sustainability mainly, at the household level. Therefore, this study was aimed to assess the SSs’ sustainability in residential buildings in Mwanza city, Tanzania emphasizing economic, environmental, technical, and social aspects. The sustainability assessment (SA) was accomplished by study area and sustainability indicators (SIs) selection methods, diverse data collection methods, and the Fuzzy-based Indices Approach (FIA) (data analysis method). The results from SA show that 18 out of 50 indicators were selected as appropriate indicators for SA of 200 households having SSs in the Nyegezi area. Also, the entire systems in the city had an index of 0.42 and fall in a danger state. It was concluded that the SIs assessed were relevant to the studied system. They demonstrate the importance of matching any set of indicators to the characteristics of the specific sanitation system being examined. Indeed, corrective measures must be suggested for immediate livelihood improvement and sustainability considerations. The study provided a tool and framework for assessing the sustainability of SSs in Tanzania using a set of most 18 relevant SIs.
Influence of land use change on nitrate sources and pollutant enrichment in surface and groundwater of a growing urban areas
(NM-AIST, 2022-07) Mallya, Clarah L.
In the present study, three-year (1997, 2008 and 2017) satellite images as well as different hydro chemical parameters, nitrogen and oxygen isotopic composition of nitrate were used to examine the impacts of land use and land cover change on surface and groundwater quality. Through isotopic composition, sources of surface and groundwater nitrate contamination was also elucidated. The results showed significant land use transition whereby land use changed from forest and bare land to agricultural land and built-up areas. A slight reduction in the size of areas covered by water bodies was also observed, from 8 km2 in 1997 to 7.4 km2 in 2017. Results indicate differences in nitrate concentration that mirror land use changes. Samples with elevated levels of nitrate above 10 mg/L were located near agricultural fields and areas with intensive livestock keeping activities. In groundwater, ẟ 15N-nitrate and ẟ 18O-nitrate ranged from 3.2‰ to 20.1‰ with a mean value of 11.7 ± 1.8‰ and from 2.1‰ to 12.0‰ with mean value of 5.4 ± 1.8‰, respectively indicating nitrate was derived from inorganic fertilizer, manure and sewage. In surface water, ẟ 15N-nitrate and ẟ 18O-nitrate ranged from 2.4‰ to 19.3‰ with mean value of 4.9 ± 1.4‰ and from 1.5‰ to 21.9‰ with a mean value of 13.5 ± 2.8‰, respectively indicating nitrate from soil N. Isotopic composition data suggest sources of nitrate in groundwater dominated by synthetic and organic fertilizer application and to a lesser extent a natural soil nitrate source.

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