Buffering efficacy and interaction of minerals in clayey soil with contaminants from landfills and acid mine drainage
- Agbenyeku, Emem-Obong Emmanuel
- 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)
- Full Text:
- 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)
- Full Text:
Buffering efficacy and interaction of minerals in clayey soil with contaminants from landfilling and mining activities: a bird-eye view
- Agbenyeku, Emem-Obong Emmanuel, Muzenda, Edison, Msibi, Mandla Innocent
- Authors: Agbenyeku, Emem-Obong Emmanuel , Muzenda, Edison , Msibi, Mandla Innocent
- Date: 2016
- Subjects: Mines and mineral resources - Environmental aspects , Clay soils , Fills (Earthwork) , Acid mine drainage - Environmental aspects
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/188255 , uj:20992 , Citation: Agbenyeku, E., Muzenda, E. & Msibi, M. 2016. Buffering efficacy and interaction of minerals in clayey soil with contaminants from landfilling and mining activities : a bird-eye view.
- Description: Abstract: The drastic growth in global population, energy resource use, industrial and infrastructure development have led to enormous problems in global conditions and contending environmental challenges. In recent years, South Africa has intensified research on industrialisation and associated environmental problems regarding waste generation, ecosystem matters, human and environmental health risk assessment, and waste management systems. The study has made it clear that geo-environments in and around landfills, and mines are severely contaminated by toxic substances not limited to heavy metals and organic compounds. The allencompassing introductory presentation in this paper based on a bird-eye view- review approach, pinpoints the present state from site reconnaissance, and impact of landfilling and mining operations in areas with such activities. This study however, has paved way for subsequent technically intense investigations on assessing the buffering efficacy of natural soils from affected sites. This include examining the interaction of pollutants with the soil minerals in succeeding papers towards curtailing soil, surface, subsurface and ground water contamination which invariably affect human and environmental health.
- Full Text:
- Authors: Agbenyeku, Emem-Obong Emmanuel , Muzenda, Edison , Msibi, Mandla Innocent
- Date: 2016
- Subjects: Mines and mineral resources - Environmental aspects , Clay soils , Fills (Earthwork) , Acid mine drainage - Environmental aspects
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/188255 , uj:20992 , Citation: Agbenyeku, E., Muzenda, E. & Msibi, M. 2016. Buffering efficacy and interaction of minerals in clayey soil with contaminants from landfilling and mining activities : a bird-eye view.
- Description: Abstract: The drastic growth in global population, energy resource use, industrial and infrastructure development have led to enormous problems in global conditions and contending environmental challenges. In recent years, South Africa has intensified research on industrialisation and associated environmental problems regarding waste generation, ecosystem matters, human and environmental health risk assessment, and waste management systems. The study has made it clear that geo-environments in and around landfills, and mines are severely contaminated by toxic substances not limited to heavy metals and organic compounds. The allencompassing introductory presentation in this paper based on a bird-eye view- review approach, pinpoints the present state from site reconnaissance, and impact of landfilling and mining operations in areas with such activities. This study however, has paved way for subsequent technically intense investigations on assessing the buffering efficacy of natural soils from affected sites. This include examining the interaction of pollutants with the soil minerals in succeeding papers towards curtailing soil, surface, subsurface and ground water contamination which invariably affect human and environmental health.
- Full Text:
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