COETEC Students Publications
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Publications by Staff and students of COETEC2024-03-28T13:38:00ZCommon occupational machinery hazards in mechanical engineering workshops in TVET institutions in Nairobi metropolitan, Kenya
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Common occupational machinery hazards in mechanical engineering workshops in TVET institutions in Nairobi metropolitan, Kenya
Ronoh, Patrick Kipkurui
The metal fabrication sector involves a variety of processes, activities, products, and by-products.
This involves various interventions such as milling, turning, welding, drilling, and grinding. Firms in
this sector use one or a combination of these interventions where machinery is used, which can
expose workers to machinery hazards if proper safety procedures are not observed. Occupational
Safety and Health (OSH) is vital in Technical Vocational Education and Training (TVET) institutions,
especially in mechanical engineering programmes where metal fabrication is practised. The
objective of this study was to assess the awareness of occupational machinery hazards in
mechanical engineering workshops in TVET Institutions. The study adopted a descriptive research
design and employed a structured questionnaire for data collection. Purposive sampling was used
to identify institutions participating in the study. SPSS version 25 was used to analyse the data and
present it in tables and graphs. Noise (90.4%) and vibration (71.9%) were reported as the most
common occupational hazards, respectively, in mechanical engineering workshops. Regarding
workstations, the grinding section (39.4%) and milling section (15.8%) were reported as
experiencing high levels of noise. The study recommends that adequate control measures be put
in place to mitigate against these hazards.
2023-07-31T00:00:00ZEvaluation of crushed slates as a suitable capping material for rapid gravity sand filters
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Evaluation of crushed slates as a suitable capping material for rapid gravity sand filters
Kakoi, Beatrice Katheu
In the potable water treatment process, Rapid Gravity Sand Filters (RGSF) are commonly
adopted as the last solid-liquid separation stage. Cleaning of the RGSF is done through
backwashing. RGSF is widely adopted all over the World due to its ease of operation and high
filtration rates. However, these filters suffer from stratification of the sand media, which causes
floc removal to occur only at the topmost layer of the filter bed, leaving the remaining depth
unutilized. Capping is a technique whereby a thin layer of sand filter media is replaced with a
suitable coarse material to overcome the problem of stratification and transform a single media RGSF into a dual-media filter. The objective of this study is to determine the suitability
of crushed slates as a capping material. The study evaluated the performance of a crushed
expanded slate-capped filter against a conventional single-media RGSF, the effects of its
physical and chemical characteristics, and varying the depth of the capping material.
Laboratory tests were conducted to assess the physical and chemical characteristics of slates
from Maji ya Chumvi (Coast, Kenya). This included specific gravity, acid solubility, water
extractable substances, silica content, and friability. A performance comparison was carried
out by means of a fabricated model filtration unit set up within an existing community water
treatment plant. The model filtration unit was fed with pretreated raw water of varying influent
turbidities. Crushed expanded slates met the minimum physical and chemical requirements
for use as a capping material for RGSF. The crushed expanded slate-capped RGSF model
demonstrated high robustness under high shock turbidity loads (above 150 NTU), which is
illustrated by an increased length of filter run of 27% (50–150 NTU) and 45% (150–300 NTU).
Increasing the depth of capping material from 25mm to 50mm did not yield any significant
improvement or deterioration in the filter run length. At influent turbidities below 150 NTU,
the effluent water quality for all three scenarios (uncapped, 25 mm, and 50mm crushed
expanded slates capped) is below 5 NTU and therefore meets the Kenyan drinking water
standards. Above 150 NTU influent turbidity, the effluent water quality for the uncapped RGSF
deteriorates, whereas for the 25mm and 50mm capped RGSF, it remains consistently below 5
NTU. This demonstrates the usefulness of the crushed expanded slates in improving the
turbidity removal of RGSF for high (above 150 NTU) turbidity loads. This study recommends a
full-scale trial of crushed expanded slates to facilitate a more precise estimation of the overall
benefit of full-scale community water filtration systems.
2023-07-31T00:00:00ZEffects of Urban Wetland Patch Pattern on the Biodiversity of Aquatic Birds in Nairobi, Keny
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Effects of Urban Wetland Patch Pattern on the Biodiversity of Aquatic Birds in Nairobi, Keny
1Caleb Toroitich, 2Mugwima Njugunaand1Dennis Karanja
Urban wetlands are ubiquitous landscape elements that affect the spatial pattern and functions of cities. Despite beingrich and important habitats for a variety of birds, they are continually being isolated or lost. Isolation and loss negatively impact on the integrity of the urban landscape pattern and compromises on biophilic planning and development. Since urbanization is a continuous cultural process, it is important to investigate how its impacts, which are invariably in conflict with nature,would portend for aquatic bird communities inurbanareas. This study sought to determine the variability and relationship betweenthe structural patch pattern of palustrine wetlands in Nairobiandthe species richness and abundance of aquatic birds in these wetlands. From a population of 300 wetlands, this study used heterogeneous sampling to identify and investigate 31 palustrine wetlands spread across the city of Nairobi. For each of these wetlands, a variety of landscape metrics were calculated and the species diversity ofaquatic birds was quantified. Multiple regression analysis was performed in IBM SPSS Statistics 21 to determine the relationships between wetland patch pattern and wetland biodiversity. The study found that patch pattern significantly affects aquatic bird biodiversity, R² = .516, F (7, 23) = 3.498, p < .05. It was also found that the characteristics of the wetland neighbourhood significantly affected aquatic bird biodiversity, R² = .301, F (3, 27) = 3.867, p < .05. This study highlights the need to mainstream, plan, and design for the conservation and monitoring of spatial patterns and biodiversity of palustrine wetlands in urban landscapes. In doing so, biophilic cities are created, bio-systemic urban infrastructure is generated, human wellbeing is enhanced, and urban wetland ecosystem services are valued
2022-04-05T00:00:00ZOVERVIEW: THE 15THJKUAT SCIENTIFIC, TECHNOLOGICAL AND INDUSTRIALIZATION CONFERENCE
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OVERVIEW: THE 15THJKUAT SCIENTIFIC, TECHNOLOGICAL AND INDUSTRIALIZATION CONFERENCE
J. Kinyuru, P. Home, W. Owino, P. Oyier, P. Kahenya, S. Kimani, M. Njire, M. Kaibui, G. Njiri, R. Ndeda, V. Ngugi, M. Kimwele, O. Oluoch, P. Mbindyo, R. Mangira, J. Nyori, V. Opondo, S. Wakhu, R. Maina, J. Obel, C. Oywer, E. Olweny, W. Kahangi, D. Ngosi, C. Mugodo, S. Muya and M. Abukutsa-Onyango.
2022-04-04T00:00:00Z