Masters Theses and Dissertations [MEWES]
https://dspace.nm-aist.ac.tz/handle/20.500.12479/61
2024-03-29T15:49:09ZThe hydrochemical evolution and water balance of the emakat lake in the northern crater highland of Tanzania
https://dspace.nm-aist.ac.tz/handle/20.500.12479/2186
The hydrochemical evolution and water balance of the emakat lake in the northern crater highland of Tanzania
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.
A Dissertation Submitted in Partial Fulfilment of the Requirements for the Degree of
Master’s in Hydrology and Water Resources Engineering of the Nelson Mandela
African Institution of Science and Technology
2023-07-01T00:00:00ZInvestigating the potential of producing eco-friendly liquid biofertilizer from domestic wastewater
https://dspace.nm-aist.ac.tz/handle/20.500.12479/2185
Investigating the potential of producing eco-friendly liquid biofertilizer from domestic wastewater
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.
A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of
Master’s in Hydrology and Water Resources Engineering of the Nelson Mandela
African Institution of Science and Technology
2023-08-01T00:00:00ZInfluence of duct configurations on the performance of solar-assisted heat pump dryer for drying tobacco leaves
https://dspace.nm-aist.ac.tz/handle/20.500.12479/2145
Influence of duct configurations on the performance of solar-assisted heat pump dryer for drying tobacco leaves
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 Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Master’s in Sustainable Energy Science and Engineering of the Nelson Mandela African Institution of Science and Technology
2023-08-01T00:00:00ZA quantity-quality tradeoff: Water quality and poverty assessment of drinking water sources in Southern Tanzania
https://dspace.nm-aist.ac.tz/handle/20.500.12479/2143
A quantity-quality tradeoff: Water quality and poverty assessment of drinking water sources in Southern Tanzania
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.
A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree Masters in Environmental Science and Engineering of the Nelson Mandela African Institution of Science and Technology
2023-06-01T00:00:00Z