Civil & Environmental Engineering

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    A review of the "tea cup effect" and removal of suspended solids from water.
    (NUST, 2011) Mashauri, Damas A.
    Suspended solids problem in water is an issue as old as water treatment itself. Suspended solids can be causative to eroding through abrasion of impellers, pump casings, pipes and other water works related appurtenances. It is therefore appropriate that suspended solids must be removed as early as possible in the water works treatment facilities. It is usually done at the river/lake intakes to reduce the coarse particulate matter that would otherwise adversely affect the water works thereafter. The fine particles that will escape the entrapment at the intake works would therefore require further and more effective system that would remove this fraction. By and large this removal process is achieved by chemically aided process such as coagulation/flocculation unit operation. This process is expensive and demands high level trained personnel to man them. In the same vein then a simple and effective system is proposed. This is a swirl or grit removal system that does not need any chemicals, moving parts or even highly trained personnel to operate them. This paper is looking at the theory of the “Tea Cup Effect” and how it has been used in practice to remove or reduce suspended solids from water. The paper gives some examples where such devices have been used and how effective they have been.
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    Namibia's performance in mathematics and physical science: Implications for technical skills.
    (NUST, 2013) Kgabi, Nnenesi A.; Tyobeka, Errol M.
    In recent years skill shortages in the labour force have become a key challenge in the SADC region, suggesting that policies for continuous upgrading of skills of the workforce are becoming increasingly important [1]. While Namibia is no exception to the skills shortage dilemma, over the past decade the situation has been worsened by the increased unemployment rates in the country’s urban areas, particularly in Windhoek. Obtaining a junior/senior certificate alone does not guarantee any return to the youth of our country unless accompanied by some technical skills. The curriculum for Namibian Basic Education as set out in “Toward Education for All” [2] includes the following: Aesthetic, social and economic, linguistic and literacy, mathematical, spiritual, moral and ethical, physical, natural scientific and technological learning areas. These, if developed further and applied appropriately to the country’s economic situation, should be sufficient to combat the existing skills deficit.
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    Engineering Research for Economic Advancement in Namibia
    (Scientific Research Publishing Inc., 2014) Kgabi, Nnenesi
    The aim of this special issue of the Open Journal of Applied Sciences on Engineering Research for Economic Advancement is to articulate the relevance of applied engineering research in driving the economic development and sustainability, and addressing national and regional needs of the “small economies”. The research focus areas covered in this issue include renewable energy, water resources management, manufacturing systems, and sustainable mining practices. The focus areas are also relevant in addressing the global change challenges relating to sustainable production and consumption of natural resources for provision of basic services at national and local level.
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    Evaluation of co-axial diagram for Namibia flood determination methods
    (2019) Neliwa, Gabriel; Burger, G.J.; Sinombe, S
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    Designing of an Equalization Process for Improving the Performance of the Gammams Water Care Works, Windhoek, Namibia
    (2020-09) Shino, Silo T.
    This thesis examines and presents a first stage assessment of the potential improvement of waste-water treatment plant performance by including an equalization process as part of the treatment train of the Gammams Water Care works in Windhoek, Namibia. The treatment plant’s operational objective of achieving compliant final effluent quality on a consistent basis is hampered by influent hydraulic and pollutant load daily diurnal pattern variations oppose to a near uniform condition experienced. These non-uniform hydraulic and pollutant loading conditions impose a negative impact on achieving overall optimal treatment plant performance. During the study, daily variations in hydraulic and pollutant loading at the Gammams Water Care Works were established and a representative day of a typical week identified for the equalization process attenuation capacity design in order to minimize both flow and pollutant load diurnal pattern variations. Furthermore, a comparative analysis of equalised and unequalised treatment scenarios on overall plant performance was done by applying both numerical and graphical analysis methodologies aided by the STOAT computer software simulation model. This study uniquely made a comparative analysis of the current Gammams Water Care Works treatment train (which currently operates without an equalization step) using the STOAT model, considering both unequalised and equalised process equalization scenarios. The graphical or Ripple method and a numerical time-step method were employed for equalization process attenuation capacity determination. The numerical time-step method together with STOAT modelling steady state simulations were employed for this 1st approximation step analyses, for initial comparison and impact assessment as well as for identifying the road map for further future detailed extended-time simulation purposes. The study found that the plant typically experiences diurnal daily influent hydraulic and pollutant load variations similar to other plants receiving mainly domestic wastewater in the early morning hours and between midday and early evenings. For STOAT modelling purposes, current plant influent and subsequent unit process outflows along the treatment train were sampled and selected pollutant concentrations were determined over 4-hour intervals for the representative dry weather weekday mentioned before. The STOAT model calibration was limited to the actual Gammams plant treatment train, unit process sizes and operational criteria employed. Bio-chemical process kinetic algorithms inherent to the STOAT model was not changed due to the software limitations of use and not being allowed. The analysis done of unequalised and equalised scenarios was thereof of a comparative nature.
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    ASSESSING THE IMPACT OF OMARURU MUNICIPAL DUMPSITE ON GROUNDWATER WITHIN OMARURU RIVER BASIN.
    (2020-10) Andreas, Jesaya N.
    River basins are vulnerable to pollution from anthropogenic activities such as the disposal of waste from domestic, commercial, industrial, and agricultural activities. The anthropogenic activities can be a source of contamination, consequently affecting the quality and quantity of groundwater. The study aimed at assessing the impact of the Omaruru municipal dumpsite on groundwater quality. Ideal individual sampling sites were selected based on their positions relative to the municipal dumpsite. Water and soil samples were analysed onsite for physical and chemical parameters including Total Dissolved Solids (3036 mg/L), Turbidity (1.69 NTU) and Electrical Conductivity (20 mS/cm) by using HANNA, H19811-5 multi-meter instrument. Heavy metals (lead, manganese, iron, copper, cadmium) that can impact groundwater quality were analysed in the laboratory using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and geochemical analysis of soil samples were was conducted in a laboratory using X-ray Fluorescence (XRF). High concentrations of heavy metals were measured in water from boreholes located downgradient of the river sub-catchment. A strong correlation relationship was found between the concentration of chemical parameters found in the soil from the municipal dumpsite and groundwater from nearby water boreholes. Chemical parameters that exceeded the Namibian water quality standards were Calcium (Ca) 100-300 mg/l > (90 mg/l), Chloride (Cl) 250> (64 mg/l), Iron (Fe) 0.3 mg/l > (0.1mg/l) and Copper (Cu) 1.3mg/l > (0.5mg/l). Chemical parameters that were found within Namibian water quality standards and Environmental Protection Agency (EPA) standards were Potassium (K) 0.2 mg/l < (1 mg/l), Magnesium (Mg) 0.07 mg/l < (25 mg/l), Barium (Ba) 0.03 mg/l < (0.5 mg/l), Lead (Pb) 0.015mg/l < (0.05) mg/l, Cadmium (Cd) 0.03 mg/l < 0.01 mg/l) and Nickel(Ni) 0.07mg/l< (0.25 mg/l). Contamination Factor (CF) of the study area ranged between 0.8–2.7 indicating the degree of overall groundwater contamination of the sampled sites. The Geo-accumulation Index (Igeo) values from the study were measured between 0.003-0.7, while the value of Pollution Load Index (PLI) of the study area was at 2. The PLI value of >1 is polluted whereas a value of <1 indicates no pollution. A strong positive correlation existed between heavy metals found in water and soil from the municipal dumpsite. Concentrations of physical and chemical parameters were benchmarked with Environmental Protection Agency (EPA) and Namibian water standards for drinking water quality.
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    COMPREHENSIVE STUDY ON THE IMPACT OF USING AGRICULTURAL RESIDUES FOR ENHANCING BUILDING ENERGY PERFORMANCE IN NAMIBIA
    (2020-11) Agbo, Onjefu L.
    This research work aimed at an understanding of the impact of using local agricultural residues to enhance building performance in Namibia. As human lifestyles improved with the emergence of high economic growth and technologies, the increasing demand for energy in Namibia as a developing country is posing a serious challenge to government and lawmakers in the allocation of funds for appropriate researches and technologies. One such appropriate kinds of research involve developing appropriate material technologies that will improve energy efficiency in the form of using agricultural residues/wastes readily available in Namibia. Like other developing countries, the building sector accounts for approximately 40% of total energy usage in Namibia. For that purpose, the efficient use of energy within buildings is a needed requisite to alienate against rising energy costs and contribute towards decreasing global greenhouse gas emissions. Namibia´s energy usage of buildings closely reflects these global trends and this research therefore aimed at validating its results through the construction of rigs following the design concept of the prototype of the EEBN (Energy Efficient Building in Namibia) research project at the Namibia University of Science and Technology campus that was designed, constructed and equipped through funding from EEP (Energy Efficiency Programme), in partnership between NUST and Carinthia University of Applied Sciences Austria. Through appropriate mixed designs of well-selected locally available agricultural residues, insulating boards and bricks of standard sizes were developed, and results validated through the construction of rigs. Thermal conductivities and transmissibility of the insulating boards together with compressive strength, water absorption were also measured for bricks to measure the degree of thermal effectiveness/efficiency of a standard residential building. This is to establish how the use of affordable and readily available local materials can be used to develop high-quality and energy- efficient building materials which when used in building construction will improve the comfort level of occupants without the use of conventional heating and cooling devices. Vary mixed percentages of residues of maize, millet, rice, and cow dung were designed to develop eleven 220cm by 110 cm by 40 cm board samples (labelled AK) from residues of maize, millet, rice, and cow dung. The samples were compacted, sun-dried for 7 days, and tested for thermal conductivity and thermal resistivity using a thermal conductivity test machine EP500e. Results from the eleven samples tested revealed that sample C (composed of 10% maize, 10% millet, 30% rice, and 40% cow dung) gives the lowest thermal conductivity (i.e. of 54.65 mW/(m*K)) and the highest thermal resistivity (i.e. 0.6935 m2K/W), hence a very good thermal efficiency as compared with sample A (composed of 40% maize, 30% millet, 10% rice and 20% cow dung) that gave the highest thermal conductivity and lowest thermal resistivity, hence considered poor thermal efficiency. Regression analyses conducted between the best (i.e. sample C) and the worst (i.e. sample A) revealed an R2 value of 95% and 91% respectively Test rigs were constructed and equipped with appropriate devices both inside and outside. Wide- ranging measurements were conducted, and results related to thermal behaviour of the interior at fluctuating changes in temperature at the exterior especially at extreme summer and winter periods were obtained. The three prototype Rigs, with varying compositions, were designed and built using standard building procedures. Rig A (TAR 1) with 150 mm thick internal and external walls; made of standard bricks of 7 MPa, insulated with a compacted mixture containing 20% (wt.) Maize, 10 % (wt.) Millet, 30% (wt.) Rice and 40% (wt.), 30% (wt.) Cow dung; Rig B (Tamb2) 40% (wt.) with Maize, 30% (wt.), Millet, 10% (wt.), 20% (wt.), 20%wt. Marble dust and C (TNo3) that serve as control rig. Outside and inside temperatures of the Rigs were monitored during the warm (September 2017 - March 2018) and cold (April to August – 2018) seasons. Temperature and humidity sensors installed at critical positions in the interior of the building were connected to the symmetron data logger. Results of the three design concepts revealed that TAR 1 (Rig A) attained maximum and minimum temperatures of 24.40C and 14.80C, and humidity of 26.4% during winter and 29.60C and 19.30C during summer with an average humidity of 21.1%. Tamb2 (Rig B) recorded a maximum and minimum temperature of 31.220C and 18.70C during summer with a relative humidity of 20.3%. During winter Rig B attained an average temperature of 22.600C. Furthermore, Rig C (TN03) recorded 32.220C and 21.700C in summer and winter respectively. From the results, it can be deduced that Rig A (TAR 1) with compositions of 20% (wt.) Maize, 10 % (wt.) Millet, 30% (wt.) Rice and 40% (wt.), 30% (wt.) Cow dung; had the best performance. Simulation on results obtained from the rigs was also done using Ansys software. This research showed that results from both software and measured are approximately the same.