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Comparative Study of Exhaust Emissions from Diesel and Syngas Powered 3.5 kW Compression Ignition Engine with and without Load

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Journal of Power and Energy Engineering 2024年第8期12卷 30-46页

作者： Benson Kariuki paul njogu Joseph Kamau Robert Kinyua Sameer Bachani Institute of Energy and Environmental Technology Jomo Kenyatta University of Agriculture & Technology Nairobi Kenya Department of Mechanical and Automotive Engineering Technical University of Mombasa Mombasa Kenya

Despite diesel engines being highly efficient, with low fuel consumption and reduced carbon dioxide emissions, they emit relatively high levels of particulate matter and oxides of nitrogen (NOx) due to high exhaust gas temperatures. Engine emissions show the quality and completeness of combustion. This paper aims to present the results of a study comparing exhaust emissions from a diesel and syngas powered engine. Syngas was produced from co-firing coal and biomass in a gasifier then cleaned, cooled and applied as an alternative fuel in an engine operated from 0 - 100% load. Exhaust-emissions were monitored at this load conditions. The exhaust-temperature was measured using thermocouples and the emission gases were analyzed using Testo 350. The emissions were lower and decreased as the engine load increased, except for sulphur dioxide and NOx. The study shows that levels of carbon monoxide, were higher in a range of 46.5 - 80.2%, while carbon dioxide was 3.3 - 18% higher compared to those from diesel. Hydrocarbon emissions were 480 and 1250 ppm for diesel and syngas respectively. The study reveals that the engine operates optimally at higher loads since hydrocarbons and oxides of carbon are low due to complete combustion at higher temperatures. Exhaust gas temperature was higher in the syngas fuel and increased as the engine load increased in the range of 455.83 - 480.03˚C which influenced the formation of NOx. NOx from diesel was found to be higher, ranging from 32.5 - 40.5%, compared to those from syngas with an engine load of 75%. The study observed that relative to diesel, the emissions of sulfur dioxide at 50% engine load were lower in a range of 23.7 - 57.1%. Emissions of hydrocarbons depended on the degree of substitution of diesel and engine load. The study therefore shows that, relative to diesel, emissions decreased when syngas was used with upgraded syngas from Prosporis juliflora presenting as the best alternative followed by Hyphanae compressa, and last

关键词： Emissions Engine Load Temperature Neat-Diesel Syngas

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Development and Application of Integrated Indicators for Assessing Healthcare Waste Management Systems in Kenyan Hospitals

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Open Journal of Applied Sciences 2024年第4期14卷 1080-1120页

作者： Muriithi Jackson Githinji paul Mwangi njogu Zipporah Nganga Mohamed Karama Institute of Tropical Medicine and Infectious Diseases (ITROMID) Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya Institute of Energy and Environmental Technology Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya Academic Research and Student Affairs South Eastern Kenya University Kitui Kenya School of Public Health Amref International University Nairobi Kenya

Healthcare waste management (HCWM) is an important aspect of healthcare delivery globally because of its hazardous and infectious components that have potential for adverse health and environmental impacts. The paper introduces a set of indicators for assessing HCWM systems in hospitals. These indicators are: HCWM policies and standard operating procedures, management and oversight, logistics and budget support, training and occupational health and safety, and treatment, disposal and waste treatment equipment housing. By plotting a mark on a continuum which is defined as good and poor on the extremes and is connected with all other marks in a spoke arrangement, it’s possible to describe a baseline for HCWM in any specific hospital. This baseline can be used to improve awareness of the actors and policy-makers, compare the same hospital at a different point in time, to compare observations by different evaluators and to track improvements. Results suggest that in Kenya, the application of such indicators is useful for evaluating which priorities should be addressed to improve outcomes in HCWM systems. Systematic sampling technique was used to identify and collect data by use of observational checklist, interviews, visual verification and review of documents and a HCWM assessment tool. The objective is to suggest an integrated management tool as a method to identify prevailing problems with a HCWM system. The method can be replicated in other contexts worldwide, with a focus on the developing world. The integrated indicators focus on management of HCW and not its potential impact on human health and environment, an area recognized to be critical for future research.

关键词： Developing Countries HCW Management Indicators Management Tools

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Levels of Polycyclic Aromatic Hydrocarbons (PAHs) in Healthcare Waste Incinerators’ Bottom Ash from Five County Hospitals in Kenya

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Journal of Environmental Protection 2024年第3期15卷 318-337页

作者： Muriithi Jackson Githinji paul Mwangi njogu Zipporah Nganga Mohamed Karama Institute of Tropical Medicine and Infectious Diseases (ITROMID) Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya Institute of Energy and Environmental Technology Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya Academic Research and Student Affairs South Eastern Kenya University Kitui Kenya Public Health and Epidemiology Umma University Kajiado Kenya

Health-care waste contains potentially harmful microorganisms and compounds which can infect and affect hospital patients, healthcare workers, the general public and environment. Therefore, management of health care waste requires safe handling, treatment and disposal procedures. While incineration reduces the volume and quantity of waste for final disposal, it leads to the production of fly and bottom ashes laden with toxic incomplete combustion products such as Polycyclic Aromatic Hydrocarbons (PAHs), dioxins, furans and heavy metals. This exposes workers who handle and dispose the bottom ashes, hospital patients, the general public and environment. The goal of this study was to determine the total and individual levels of 16 most prevalent and toxic PAHs. Bottom ash samples were collected from incinerators in five county hospitals in Kenya, namely;Moi-Voi, Narok, Kitale, Makindu and Isiolo. Bottom ash samples were collected over a period of six months from the five hospitals. The samples were then sieved, homogenised and stored at 4°C in amber coloured glass containers. The PAHs were extracted using 30 ml of a hexane-acetone solvent (1:1) mixture by ultrasonication at room temperature (23°C) for 45 minutes. The PAHs were then analyzed with a GC-MS spectrophotometer model (Shimadzu GCMS-QP2010 SE) connected to a computer work station was used for the PAHs analysis. The GC-MS was equipped with an SGE BPX5 GC capillary column (30 m × 0.25 mm × 0.25 μm) for the separation of compounds. Helium was used as the carrier gas at a flow rate of 15.5 ml/minute and 14.5 psi. 1 μl of the sample was injected at 280°C, split mode (10:1). The oven programming was set for a total runtime of 40 minutes, which included: 100°C (2-minute hold);10°C /min rise to 200°C;7°C /min rise to 249°C;3°C /min rise to 300°C (2-minute hold). The interface temperature was set at 290°C. Analysis was done in Selected Ion Monitoring (SIM) mode and the peak areas of each of the PAHs were collected from

关键词： PAHs GC-MS Healthcare Wastes Disposal Incinerator Bottom Ash

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Concentration of Copper, Zinc, Lead, Cadmium, and Nickel in the Incinerator Bottom Ash in Five County Hospitals in Kenya

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Journal of Geoscience and Environment Protection 2024年第6期12卷 90-114页

作者： Muriithi J. Githinji paul M. njogu Zipporah Nganga Mohamed Karama Institute of Tropical Medicine and Infectious Diseases (ITROMID) Jomo Kenyatta University of Agriculture and Technology (JKUAT) Nairobi Kenya Institute of Energy and Environmental Technology Jomo Kenyatta University of Agriculture and Technology (JKUAT) Nairobi Kenya Academic Research and Student Affairs South Eastern Kenya University Kitui Kenya School of Public Health Amref International University Nairobi Kenya

Healthcare wastes contain potentially harmful microorganisms, inorganic and organic compounds that pose a risk to human health and the environment. Incineration is a common method employed in healthcare waste management to reduce volume, quantity, toxicity as well as elimination of microorganisms. However, some of the substances remain unchanged during incineration and become part of bottom ash, such as heavy metals and persistent organic pollutants. Monitoring of pollution by heavy metals is important since their concentrations in the environment affect public health. The goal of this study was to determine the levels of Copper (Cu), Zinc (Zn) Lead (Pb), Cadmium (Cd) and Nickel (Ni) in the incinerator bottom ash in five selected County hospitals in Kenya. Bottom ash samples were collected over a period of six months. Sample preparation and treatment were done using standard methods. Analysis of the heavy metals were done using atomic absorption spectrophotometer, model AA-6200. One-Way Analysis of Variance (ANOVA) was performed to determine whether there were significant differences on the mean levels of Cu, Zn, Pd, Cd and Ni in incinerator bottom ash from the five sampling locations. A post-hoc Tukey’s Test (HSD) was used to determine if there were significant differences between and within samples. The significant differences were accepted at p ≤ 0.05. To standardize the results, overall mean of each metal from each site was calculated. The metal mean concentration values were compared with existing permissible levels set by the WHO. The concentrations (mg/kg) were in the range of 102.27 - 192.53 for Cu, Zn (131.68 - 2840.85), Pb (41.06 - 303.96), Cd (1.92 - 20.49) whereas Ni was (13.83 - 38.27) with a mean of 150.76 ± 77.88 for Copper, 131.66 ± 1598.95 for Zinc, 234.60 ± 262.76 for Lead, 12.256 ± 10.86 for Cadmium and 29.45 ± 18.24 for Nickel across the five sampling locations. There were significant differences between levels determined by one-way ANOVA of Zn (

关键词： Healthcare Waste Disposal Public Health Environment Incineration Heavy Metals Bottom Ash

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Levels of Polycyclic Aromatic Hydrocarbons (PAHs) in Healthcare Waste Incinerators’ Bottom Ash from Five County Hospitals in Kenya

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Journal of Environmental Protection（环境保护） 2024年第3期 318页

作者： Muriithi Jackson Githinji paul Mwangi njogu Zipporah Nganga Mohamed Karama

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Development and Application of Integrated Indicators for Assessing Healthcare Waste Management Systems in Kenyan Hospitals

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Open Journal of Applied Sciences（应用科学） 2024年第4期 1080页

作者： Muriithi Jackson Githinji paul Mwangi njogu Zipporah Nganga Mohamed Karama

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Kinetics and Process Studies of the Potential for Transformation of Biogas to Biomethane and Liquefaction using Cryogenic Liquid for Domestic Applications

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Energy and Power Engineering 2023年第6期15卷 229-240页

作者： Benard Ogembo paul njogu Francis Ochieng Institute of Energy and Environmental Technology Jomo Kenyatta University of Agriculture and Technology (JKUAT) Nairobi Kenya

The present work dealt with the generation, purifying and liquefaction of biomethane to improve energy density using local materials for domestic applications. Cow dung was sourced at JKUAT dairy farm and experiments were conducted at JKUAT Bioenergy laboratory using biogas generated in laboratory scale 1 m3 bioreactors. Experiments were done in triplicates and repeated under different conditions to get the optimal conditions. The results showed that enhanced cow dung substrate displayed an improved fermentation process with increased biogas yields. Purified biogas optimized methane content from 56% ± 0.18% for raw biogas to 95% ± 0.98% for biomethane which was ideal for liquefaction.

关键词： Biogas Bio-Methane Catalysis Purification Liquefaction Bio-Energy Kinetics

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Elemental Analysis of Fly and Bottom Ash from Burners/Incinerators in Selected Health Care Facilities in Kiambu County, Kenya

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Journal of Environmental Science and Engineering(A) 2014年第5期3卷 243-249页

作者： Raphael Kungu paul njogu Jackson Kiptoo Institute for Energy and Environmental Technology Jomo Kenyatta University of Agriculture and Technology Nairobi P.O. Box62000-00200 Kenya Department of Chemistry Jomo Kenyatta University of Agriculture and Technology Nairobi P. O. Box 62000-00200 Kenya

Medical waste incinerators emit a wide range of pollutants like heavy metals, dioxins and furans. These include Pb （lead）, Hg （mercury）, Cd （cadmium）, fine dust particles and PICs （products of incomplete combustion）. The objective was to determine the elemental composition of medical waste residue after incineration in selected hospitals in Kiambu County, Kenya. Bottom/fly ash samples were collected from the burners/incinerators in the selected health care facilities visited. The concentrations of the metals in the fly ash and bottom ash were determined using an XRF （X-ray fluorescence） spectrometer after acid digestion. The concentrations of heavy metals in the fly and bottom ash were as follows： Ti （titanium） 62-839 mg·kg^-1 and a mean of 202 mg·kg^-1 and 344 mg·kg^-1 in fly ash and bottom ash, respectively. Ca （calcium） was 37,753-204,475 ***1 with means of 27,132 ***-1 in fly ash and 131,185 mgg·kg^-1 in bottom ash. Zn （zinc） was 297-6,605 mg·kg^-1 with means （2,307 mg·kg^-1 in fly ash, 4,359 mg·kg^-1 in bottom ash）, Pb （13-1,819 mg·kg^-1） had means of 280 mg·kg^-1 in fly ash and 291 mg-kg-1 in bottom ash. Cu （copper）（9.5-250 mg·kg^-1） had means of 83.47 mg·kg^-1 in fly ash and 98.8 mg·kg^-1 in bottom ash. The wide variations in results can be attributed to the different burners/incinerators used and different segregation methods of the medical waste. The results show that the reported levels of heavy metals could pose a health risk due to possible leaching after disposal.

关键词： Health care waste fly and bottom ash incinerators metal pollutants.

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An Analysis of Solid Waste Generation and Characterization in Thika Municipality of Kiambu County, Kenya

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Journal of Environmental Science and Engineering(B) 2015年第4期4卷 210-215页

作者： Mugo Ephantus Kinyua Robert njogu paul Institute of Energy and Environmental Technology Jomo Kenyatta University of Agriculture and TechnologyNairobi 62000-00200 Kenya

The rapid increase in population in Thika has led to increase in municipal solid waste generation, which has posed challenges in the waste disposal and management. This study was carried out to quantify and characterize the waste generated within Thika municipality. Six months data （between March 2014 and August 2014） of waste stream at the dumpsite was reviewed and analyzed. The survey indicated that 66.95% ± 0.34% of the total waste dumped originated from the municipal council ofThika （MCT）. It constitutes of domestic, commercial and institutional waste. 33.05% is industrial waste. Sixty eight percent （68%） of the waste consisted primarily of four components： paper, plastic, organics and food. Food accounted for 15.51% ± 0.95%, paper 18.31% ± 1.7%, plastics 17.89% ± 0.81% and organics other than food 16.51% ±1.01%, respectively obtained at 95% confidence level. Each of the components has some level of recovery. Some of the reusable and recyclable materials were being recovered, food waste had the highest recovery rate of 23% ± 1.7% and was used as animal feed, while plastic （soft plastic） 17% ± 0.93% was sold to recyclers. Recovery of materials for recycling and composting was estimated at 10.21 tonnes or 11.35% of daily generation, leaving 76.44 tonnes per day that can be converted into useful energy. The study shows waste in this dumpsite can be exploited to by converting it to energy thus a good solution for waste management.

关键词： Municipal solid waste municipal solid waste management waste to energy Thika municipality.

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Distribution and Concentrations of Heavy Metals in Tropospheric Suspended Particulate Matter (PM10) In Nairobi City, Kenya

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Open Journal of Applied Sciences 2021年第8期11卷 899-907页

作者： Faith Ndunge Mutua paul njogu Christopher Kanali Institute of Energy and Environmental Technology Nairobi Kenya School of Biomechanical and Environmental Engineering JKUAT Nairobi Kenya

Air pollution present the greatest threat to human health and welfare in urban environments. Population growth, industrial activities, expanded transport system, vehicular traffic, poor road planning, poor land use and traffic congestion contribute to the problem. Particulate matter (PM2.5 and PM10) has become the principal pollutants due to increased material use, energy demand and use as a result of global economic growth. This study assessed the levels of PM10 in ambient air and heavy metal composition in Nairobi city. Sampling sites were classified into three categories namely;controlled areas, industrial and residential areas as proscribed in the EMCA Air Quality Regulations, 2014. Portable Mini-Vol ambient air samplers were used for fine particulate monitoring. The concentrations of manganese, lead, and cadmium was determined in PM10 samples from all sampling sites. The lead concentration mean was 0.07 ± 0.06 μg/m3, 0.34 ± 0.35 μg/m3 and 1.10 ± 0.59 μg/m3 for residential, controlled and industrial areas respectively. Generally, all afternoons had high particulate matter while the lowest concentration levels of PM10 were recorded at night.

关键词： Air Pollution Heavy Metals Tropospheric Particulate Matter

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