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Bioenergy; a substitute and cleaner energy option

  • Authors: Agbenyeku, Emem-Obong Emmanuel , Muzenda, Edison , Msibi, Mandla Innocent
  • Date: 2017
  • Subjects: Anthropogenic , Biomass , Global warming
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/250343 , uj:26085 , Citation: Agbenyeku, E.E., Muzenda, E. & Msibi, M.I. 2017. Bioenergy; a substitute and cleaner energy option. 2nd International Engineering Conference (IEC 2017) Federal University of Technology, Minna, Nigeria.
  • Description: Abstract: The early man used energy in the form of food as power source for himself. Man further used energy from the sun for warmth and drying processes. With the advent of civilization and advancement, even more energy was needed to meet up with everyday industrialization demands. This led to a persistent pursuit and exploitation of the earth’s resources in the likes of coal and petroleum. Fossil fuels were continually burned and used with little or no mind for sustainability and consequential impacts on the future. Estimates reveal that, at this level of exploitation, petroleum may not last another half century. The unfortunate reality however, remains that our planet is now edged with catastrophic events like global warming, ozone layer depletion and acid rain due to mans’ reckless exploitation of nature. The increased level of greenhouse gases (GHGs) in the atmosphere is mostly anthropogenic, born from the combustion of fossil fuels. Acts of man have not only endangered humans and our habitats but also fostered multitude of environmental impacts causing global climate changes. Energy is one of the most significant resource for any country, and the search for fuels and renewable energy the world over is inevitable. The exploration of forms of renewable energy in present day is often directed towards biomass resources. These energy forms are called ‘renewable’ because they are constantly replenished and inexhaustible. Renewable energy technologies utilize these sources and convert them into usable forms of energy like electricity, heat, or mechanical power. These technologies are often described as ‘clean’ or ‘green’ because they produce little or no pollutants. This paper therefore, sheds light on bioenergy as an area commanding global attention as a source for cleaner energy options. Among the biomass conversion processes addressed herein, methane production from organic wastes could be most economically feasible in South Africa within the limitations of scale and location.
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Buffering efficacy and interaction of minerals in clayey soil with contaminants from landfilling and mining activities: a bird-eye view

Buffering efficacy and interaction of minerals in clayey soil with contaminants from landfills and acid mine drainage

  • Authors: Agbenyeku, Emem-Obong Emmanuel
  • Date: 2016
  • Subjects: Acid mine drainage - Environmental aspects , Mines and mineral resources - Environmental aspects , Fills (Earthwork) , Clay soils
  • Language: English
  • Type: Doctoral (Thesis)
  • Identifier: http://hdl.handle.net/10210/225168 , uj:22735
  • Description: Abstract: The extent to which mining and landfilling activities in South Africa impact the environment and invariably have consequential effects on the health of inhabitants has remained insistently dire. Hence, for the study to assess the efficacy and potency of three subtropical clayey soils as buffers of contaminants, their compatibility with acid mine drainage (AMD) and municipal solid waste (MSW) landfill leachate was investigated through geochemical, mechanical and soil hydraulic conductivity testing, batch sorption, column diffusion, chemical and x-ray diffraction studies. The infusion of roughly 18-24 pore volumes of AMD through the soils triggered a dissolution of metals from soil grains. The soils adsorbed more potassium than sodium after 4-10 pore volumes of MSW landfill leachate intrusion. Generally, the effluent breakthrough curves of the respective soils showed early arrival and delayed desorption of magnesium and calcium while iron and nearly all heavy metals in the leachate were buffered. The effective diffusion coefficients for potassium and sodium were found to range between 1.5-1.9 × 10-10 m/s and 7.1-13 × 10-10 m/s respectively. The source solutions used as permeants in the study triggered desorption of chemical species from the exchangeable sites of the clayey soil minerals leading to the alteration, formation and dissolution of other soil minerals. Irrespective of the physicochemical and mineralogical transformations that occurred in the respective soils, the final hydraulic conductivity values satisfied the maximum soil acceptance criterion by roughly two order of magnitude lower than 1 × 10-9 m/s specified for clay liner construction in South Africa. Nonetheless, the three sampled natural subtropical soils were found to be incompatible with AMD and therefore, should not be solely used as naked natural buffers for AMD containment and related acid producing wastes, as they were mostly inadequate in buffering the potentially harmful AMD chemical species. Furthermore, it is not advisable to use the respective naked soils alone as natural buffers in MSW landfills with high concentrations of leachate chemical species as every soil system has a threshold. The soils can however, be used in composite barrier lining systems. This is such that, complex mechanisms provide the natural soils in-situ and ex-situ with their mechanical and physical behaviours including; adsorption, desorption, attenuation, complexation, pressure and transformations which contribute to the development of changes in net repulsion/attraction and natural bonding in the respective soils. , D.Phil. (Civil Engineering Science)
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Chemical alterations in three clayey soils from percolation and interaction with acid mine drainage (AMD)

  • Authors: Agbenyeku, Emem-Obong Emmanuel , Muzenda, Edison , Msibi, Mandla Innocent
  • Date: 2016
  • Subjects: Acid mine drainage , Subtropical clayey soils , Contaminant migration
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/212627 , uj:21000 , Citation: Agbenyeku, E., Muzenda, E & Msibi, M. 2016. Chemical alterations in three clayey soils from percolation and interaction with acid mine drainage (AMD).
  • Description: Abstract: The issues of acid mine drainage (AMD) from mining activities is not a new phenomenon to the present day developing South Africa as well as in most developed countries around the globe. However, the persistent rise in environmental contamination in South Africa is drastically attracting massive concerns. Vital concerns of AMD in South Africa still remain the threat to soil, surface, subsurface and ground water reserves among others, which consequentially impact human and environmental health. This insistent challenge has given rise to the need for investigating the buffering efficacy of clayey mineral soils for use as natural contaminant barriers to contaminant species from AMD. Therefore, the study presented herein, was channeled towards assessing the chemical alterations in three clayey soils from permeation and interaction with AMD via successive protracted percolation up to 18-25 pore volume passage of AMD through the respective soil medium. The final hydraulic conductivity measured, ranged between 1.3 × 10-11 m/s and 1.5 × 10-11 m/s. The obtained pH, electrical conductivity and solute breakthrough curves indicated the soils had low acid-buffering efficacies. Chemical species such as Na, Co and SO42- were highly dissolved due to attack on the soil grains by AMD. Chemical species were also released from the soils including the dissolution of metals and desorption of chemical species from AMD attack. As such, the study revealed that the buffering efficacies of the respective tested clayey soils to AMD chemical contaminants were generally ineffective.
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Energy Efficiency as a drive towards sustainable development

  • Authors: Agbenyeku, Emem-Obong Emmanuel , Muzenda, Edison , Msibi, Mandla Innocent
  • Date: 2017
  • Subjects: Efficiency , Energy , Energy conservation
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/250332 , uj:26083 , Citation: Agbenyeku, E.E., Muzenda, E. & Msibi, M.I. 2017. Energy Efficiency as a drive towards sustainable development. 2nd International Engineering Conference (IEC 2017) Federal University of Technology, Minna, Nigeria.
  • Description: Abstract: It has long been established that the economic development of any nation is deeply associated to its energy consumption levels. Over the years however, the insistent increase in the demand for energy triggered a significant utilization of fossil fuels which adversely impacted the environment. This paper therefore, in line with the numerous efforts made around the world, including in South Africa, offers further insight to the significance of the efficient use of energy and its conservation. Hence, it is pertinent to note that one unit of energy saved at the consumer end evades 2.5-3 times fresh capacity addition. Moreover, such savings via the efficient use of energy can be achieved at less than one-fifth of the cost of new capacity generation. Considering that the per capita consumption in South Africa is likely to grow with growth in economy, thereby increasing the energy demand, the efficient use and conservation of energy has become even more crucial. In simple terms, per capita energy consumption is greatly indicative of the wellbeing of human life. The dismal levels of energy inefficiency the world over, has impacted the atmosphere and caused climate changes. The resultant rise in global temperature affects the complex web of systems that permit life to flourish on earth such as rainfall, wind patterns, ocean currents and distribution of plant and animal species. For these reasons, energy conservation programmes get carbon credit from the United Nations Framework Convention on Climate Change (UNFCCC) which emphasizes how energy efficiency is key to all enterprises, especially for energy intensive industries. As such, any successful energy conservation programme needs the commitment of top management in giving equal importance in their corporate objective as manpower, raw material, production and sales. Furthermore, the paper posits that in actualizing the critical energy saving potential envisaged in South Africa, there should be efforts from entrepreneurs, State Agencies and the Government as “energy conservation is always a win-win situation for all stakeholders”.
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Impact of agricultural waste additive on 1-dimensional clay consolidation behaviour

  • Authors: Agbenyeku, Emem-Obong Emmanuel , Muzenda, Edison , Msibi, Innocent Mandla
  • Date: 2014
  • Subjects: Rice husk ash , Kaolinitic clay , Soil treatment , Soil consolidation , Soil stabilization , Agricultural waste , Landfills , Fills (Earthwork)
  • Type: Article
  • Identifier: http://ujcontent.uj.ac.za8080/10210/386034 , uj:5050 , http://hdl.handle.net/10210/13589
  • Description: Soil treatment is of vital concern in geoenvironmental and construction engineering in present times as suitable naturally occurring materials are rapidly depleted. Efforts are continually invested towards the resourceful utilization of wastes as fillers, cement enhancers, stabilizers and blenders with little or no significant impacts on the environment. This paper explains the use of a locally available and abundant agricultural waste- Rice husk ash (RHA) in West Africa, Nigeria for the treatment and stabilization of kaolinitic clay (KC) sampled from an active landfill site in Johannesburg, South Africa. The impact of incorporating different percentages of RHA on the compressibility characteristics of a parent compressible landfill KC sample was investigated under a One-dimensional consolidation test. Compacted soil specimens were treated at optimum water content (OWC) and maximum dry unit weight (MDUW) by the addition of agricultural waste material to the parent KC. The compacted specimens were subjected incremental vertical loading in a fixed ring consolidometer device. This was done with a view to closely simulate the waste loading effects from a typical landfill on a treated and parent clay/clayey bottom barrier based on one-dimensional consolidation behaviours. The introduction of RHA waste material to the parent KC revealed an outcome with substantial improvements in compaction characteristics. Hence, the results presented herein showed the agricultural waste to positively increase one-dimensional rigidity while settlement was effectively decreased. From results and analysis, the KC stabilized with RHA can withstand loadings from waste heaps under conditions as were applied in this study. With due recommended examination by geoenvironmental specialists, the stabilized material may be considered as an environmental and cost saving beneficiation approach for use in landfill liners.
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Liner-leachate interaction curve models for clayey soils from landfills around the City of Johannesburg

Mechanical properties of green concrete with Palm Nut Shell as low cost aggregate

  • Authors: Agbenyeku, Emem-Obong Emmanuel , Okonta, Felix Ndubisi
  • Date: 2014
  • Subjects: Sustainable construction , Prestressed concrete construction , Concrete - Testing , Building materials , Palm Nut Shell
  • Type: Article
  • Identifier: uj:5077 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13648
  • Description: The cost saving benefits of aggregate replacement in concrete works are well documented. The utilization of Supplementary Aggregate Materials (SAMs) in concrete engineering without compromising standards in concrete works remain very attractive to both infrastructure developers and design engineers. However, there is continual search for low cost beneficial substitute materials. The mechanical properties of green concrete produced from Palm Nut Shell (PNS) as coarse aggregate was investigated. The abundance of PNS (light weight waste product of palm oil production) in West Africa created the impetus for the study. Series of laboratory tests such as; Slump, Compaction factor, Density, Schmidt hammer and Compressive strength tests were conducted on specimens of 10, 20, 30, 40 and 50% replacements of dry weight of PNS as coarse aggregate and specimens of natural aggregate as control sample. The specimens were cured at relative humidity (RH) of 95-100% and temperature (T) of 22-25oC in a chamber for periods of 7, 14, 21 and 28 days. The results showed the PNS samples to have relatively medium to high workability ranging from 24-47 mm for slump height and values of 0.85 to 0.90 for compaction factors. A general strength development was observed across the different samples with the PNS sample reaching strength of 48.7 N/mm2 at 28 days curing. The 50% replacement specimens which mobilized UCS of 28.7 N/mm2 met the requirement for lightweight concrete however, 30% is the optimum for a partial aggregate replacement in green concrete as UCS of 39.2 N/mm2 was mobilized in 28 days. Thus PNS is a suitable concrete constituent and can be a major cost reduction factor especially in low cost rural projects with streamlined loading requirements.
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Palm kernel incinerated ash as low cost concrete component

  • Authors: Agbenyeku, Emem-Obong Emmanuel , Okonta, Felix Ndubisi
  • Date: 2014
  • Subjects: Lightweight concrete , High strength concrete , Incineration
  • Type: Article
  • Identifier: uj:5058 , ISBN 9781614994657 , ISSN 9781614994664 , http://hdl.handle.net/10210/13620
  • Description: The incorporation of commercially available fly ash (FA) as low cost material in concrete has long been established. Large quantities of FA are utilized for research and field applications because of the pozzolanic characteristics. One of many pozzolanic materials is palm kernel incinerated ash (PKIA). The abundance of PKIA as an agricultural waste material in West Africa obtained by the incineration of palm kernel husk and shells in milling boilers paved way for this study. Specimens containing 50%PKIA were cast and cured both in water and air and their compressive strength and shrinkage behaviours were investigated with and without the addition of superplasticizer (hydroxylated carboxylic (HC) acid) in comparison with controlled specimens containing 100%OPC. Results showed that the strength development in PKIA green concrete at all ages of curing; 7,14 and 28 days were lower than OPC concrete. On the addition of superplasticizer, strength of 36.9N/mm2 was observed for specimens with superplasticizer as against 31.7N/mm2 for specimens without superplasticizer on the 28day. The water curing method produced the best results while the predicted shrinkage strain of the green concrete in accordance to ACI 209R-92 standard was higher than the control specimens.
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Susceptibility and defects from the active life of landfill geomembrane liners

  • Authors: Agbenyeku, Emem-Obong Emmanuel , Muzenda, Edison , Msibi, Mandla Innocent
  • Date: 2017
  • Subjects: Active life , Degradation , Defects
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/250653 , uj:26125 , Citation: Agbenyeku, E.E., Muzenda, E. & Msibi, M.I. 2017. Susceptibility and defects from the active life of landfill geomembrane liners. 2nd International Engineering Conference (IEC 2017) Federal University of Technology, Minna, Nigeria.
  • Description: Abstract: The useful/active life of geomembrane (GM) liners are largely reliant on their degradation rate viz-a-viz; the generation of wrinkles, cracks and holes in the liner. This is mostly due to exposure to the elements or by virtue of age as well as the level of leachate or gas leakage specific to a site. The active life of a GM liner in a landfill requires in-depth review of material degradation processes, physical damage and the development of holes by stress cracking. This study highlights the outcomes of a short-term laboratory investigation offering grounds on which projections on medium to long-term landfill liner behaviours can be monitored particularly in Johannesburg, South Africa. Laboratory model of a hole creation born from the active life of a GM liner is pinpointed. It is well known how electrical leak pointer surveys are effective ways of identifying holes caused by physical damage during liner installation and waste disposal, leading to the their repairs. So also is the degradation of the GM liner known as being dependent on the activation energy of the antioxidant depletion process and the oxidative resistance of the material including exposure conditions and limits. In cases where liners are exposed to long-term stresses, stress cracking triggers hole generation. Moreover, the rate of cracking increases once oxidation of the liner begins. As such, approaches to curb the creation of defects are addressed herein.
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