Risk-based assessment of environmental asbestos contamination in the Northern Cape and North West provinces of South Africa
- Authors: Jones, Robert Ryan
- Date: 2011
- Subjects: Asbestos industry -- Health aspects -- South Africa -- Northern Cape Asbestos industry -- Health aspects -- South Africa -- North West Environmental risk assessment -- South Africa-- Northern Cape Environmental risk assessment -- North West Asbestos -- Toxicology -- South Africa -- Northern Cape Asbestos -- Toxicology -- South Africa -- North West Tailings (Metallurgy) -- Waste disposal -- South Africa -- Northern Cape Tailings (Metallurgy) -- Waste disposal -- South Africa -- North West
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4780 , http://hdl.handle.net/10962/d1012612
- Description: The commercial mining of asbestos occurred in four Provinces of South Africa (Northern Cape, North West, Limpopo and Mpumalanga). It was initiated in the late 1800's and lasted for over a hundred years into the beginning of this century. As a producer of amphibole asbestos, South Africa far outpaced every other country being responsible for 97% of global production. The last crocidolite mine closed in 1996 and chrysotile in 2002. Anecdotal information concerning environmental contamination as a result of the former mining activities and the improper disposal of mine waste tailings has been reported by a variety of authors. Few comprehensive or systematic surveys have been conducted to date to document this issue and very little quantifiable research has been completed on the communities located in close proximity to the former mine sites to determine the extent of contamination. In 2004-2006 communities were surveyed within the Northern Cape and North West Provinces to determine the extent and severity of environmental contamination. This research developed and applied a methodology to select those communities suspected of environmental contamination, a targeted survey methodology, and a protocol for rapid sample laboratory analysis. A total of 41 communities were initially predicted by the model to be suspected for environmental asbestos contamination. Based on the inclusion of local knowledge, a final 36 communities were selected for a screening-level field assessment, 34 of which were found to contain environmental asbestos contamination at rates ranging from 20 to 100% of the surveyed locations. A total of 1 843 samples of soil and building material were collected in the screening level assessment. One community (Ga-Mopedi) was selected as being representative of the total cohort and a more detailed house to house survey was completed. A total of 1 486 samples were collected during the detailed survey. Results of the detailed survey revealed 26.2% of the homes were contaminated with asbestos containing soil and/or building material. A theoretical quantitative cumulative exposure assessment was developed to estimate the disease burden within the study area population of 126,130 individuals within the surveyed communities resulting in a predicted range of 25-52.4 excess deaths per year from lung cancer and mesothelioma due solely to environmental exposures to asbestos pollution.
- Full Text:
- Date Issued: 2011
- Authors: Jones, Robert Ryan
- Date: 2011
- Subjects: Asbestos industry -- Health aspects -- South Africa -- Northern Cape Asbestos industry -- Health aspects -- South Africa -- North West Environmental risk assessment -- South Africa-- Northern Cape Environmental risk assessment -- North West Asbestos -- Toxicology -- South Africa -- Northern Cape Asbestos -- Toxicology -- South Africa -- North West Tailings (Metallurgy) -- Waste disposal -- South Africa -- Northern Cape Tailings (Metallurgy) -- Waste disposal -- South Africa -- North West
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4780 , http://hdl.handle.net/10962/d1012612
- Description: The commercial mining of asbestos occurred in four Provinces of South Africa (Northern Cape, North West, Limpopo and Mpumalanga). It was initiated in the late 1800's and lasted for over a hundred years into the beginning of this century. As a producer of amphibole asbestos, South Africa far outpaced every other country being responsible for 97% of global production. The last crocidolite mine closed in 1996 and chrysotile in 2002. Anecdotal information concerning environmental contamination as a result of the former mining activities and the improper disposal of mine waste tailings has been reported by a variety of authors. Few comprehensive or systematic surveys have been conducted to date to document this issue and very little quantifiable research has been completed on the communities located in close proximity to the former mine sites to determine the extent of contamination. In 2004-2006 communities were surveyed within the Northern Cape and North West Provinces to determine the extent and severity of environmental contamination. This research developed and applied a methodology to select those communities suspected of environmental contamination, a targeted survey methodology, and a protocol for rapid sample laboratory analysis. A total of 41 communities were initially predicted by the model to be suspected for environmental asbestos contamination. Based on the inclusion of local knowledge, a final 36 communities were selected for a screening-level field assessment, 34 of which were found to contain environmental asbestos contamination at rates ranging from 20 to 100% of the surveyed locations. A total of 1 843 samples of soil and building material were collected in the screening level assessment. One community (Ga-Mopedi) was selected as being representative of the total cohort and a more detailed house to house survey was completed. A total of 1 486 samples were collected during the detailed survey. Results of the detailed survey revealed 26.2% of the homes were contaminated with asbestos containing soil and/or building material. A theoretical quantitative cumulative exposure assessment was developed to estimate the disease burden within the study area population of 126,130 individuals within the surveyed communities resulting in a predicted range of 25-52.4 excess deaths per year from lung cancer and mesothelioma due solely to environmental exposures to asbestos pollution.
- Full Text:
- Date Issued: 2011
The identification and evaluation of key sustainable development indicators and the development of a conceptual decision-making model for capital investment within Gold Fields Limited (GFL)
- Authors: Jacobs, Phillip A H
- Date: 2010
- Subjects: Industrial management -- Environmental aspects -- South Africa -- Case studies Social responsibility of business -- South Africa -- Case studies Environmental protection -- South Africa -- Case studies Sustainable development -- South Africa -- Case studies Business ethics -- South Africa -- Case studies Industries -- Social aspects -- South Africa -- Case studies Industries -- Moral and ethical aspects -- South Africa -- Case studies Gold Fields Ltd -- Case studies
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:820 , http://hdl.handle.net/10962/d1008304
- Description: The current trends in sustainable development (SO) were examined in this study, which brought about the realisation that SO has become a business imperative. Mining, which is a highly impacting industry, is faced with the dilemma of implementing the principles of SO despite the realisation that its activities are severely limited by· the finite nature of the resource it is capitalising on. This reality, however, does not detract from the non-negotiable requirement for the industry to meet the increasing pressures to act responsibly towards the environment and the community in which it operates. Gold Fields has stepped up to the plate and has already taken several steps to achieve this end. These include the adoption of SO in its Vision, Values and strategies and the development and implementation of a SO framework to ensure the integration of the principles of SO into the business. Furthermore, Gold Fields has also entered into voluntary activities that further cement the commitment the company has towards so. These other initiatives include, inter alia, its International Council on Mining and Metals membership, UN Global Compact participation, becoming a signatory to the cyanide code, IS014001, and so on. This study focussed on several indicator categories and the identification of a set of supporting sustainable development indicators (SOls) for each, which included environmental, social, economic, technological, and ethics, legal and corporate governance (not in order of priority). These indicators were assessed by a carefully selected group of respondents whose collective wisdom and expertise were used to identify and weight supporting SOls for each of the indicator categories. These supporting SOls were in turn used to develop a model that is able to assist in the business's decision making processes when capital investment is being considered . A water treatment project that is currently being considered by Gold Fields was utilised to demonstrate how the decision making model can be applied to two different scenarios. The result clearly and successfully demonstrated that by proactively taking environmental, economic, social, technological, and ethics, legal and corporate governance considerations into account, a gold mining company is able to increase the level of SO of a capital investment project.
- Full Text:
- Date Issued: 2010
- Authors: Jacobs, Phillip A H
- Date: 2010
- Subjects: Industrial management -- Environmental aspects -- South Africa -- Case studies Social responsibility of business -- South Africa -- Case studies Environmental protection -- South Africa -- Case studies Sustainable development -- South Africa -- Case studies Business ethics -- South Africa -- Case studies Industries -- Social aspects -- South Africa -- Case studies Industries -- Moral and ethical aspects -- South Africa -- Case studies Gold Fields Ltd -- Case studies
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:820 , http://hdl.handle.net/10962/d1008304
- Description: The current trends in sustainable development (SO) were examined in this study, which brought about the realisation that SO has become a business imperative. Mining, which is a highly impacting industry, is faced with the dilemma of implementing the principles of SO despite the realisation that its activities are severely limited by· the finite nature of the resource it is capitalising on. This reality, however, does not detract from the non-negotiable requirement for the industry to meet the increasing pressures to act responsibly towards the environment and the community in which it operates. Gold Fields has stepped up to the plate and has already taken several steps to achieve this end. These include the adoption of SO in its Vision, Values and strategies and the development and implementation of a SO framework to ensure the integration of the principles of SO into the business. Furthermore, Gold Fields has also entered into voluntary activities that further cement the commitment the company has towards so. These other initiatives include, inter alia, its International Council on Mining and Metals membership, UN Global Compact participation, becoming a signatory to the cyanide code, IS014001, and so on. This study focussed on several indicator categories and the identification of a set of supporting sustainable development indicators (SOls) for each, which included environmental, social, economic, technological, and ethics, legal and corporate governance (not in order of priority). These indicators were assessed by a carefully selected group of respondents whose collective wisdom and expertise were used to identify and weight supporting SOls for each of the indicator categories. These supporting SOls were in turn used to develop a model that is able to assist in the business's decision making processes when capital investment is being considered . A water treatment project that is currently being considered by Gold Fields was utilised to demonstrate how the decision making model can be applied to two different scenarios. The result clearly and successfully demonstrated that by proactively taking environmental, economic, social, technological, and ethics, legal and corporate governance considerations into account, a gold mining company is able to increase the level of SO of a capital investment project.
- Full Text:
- Date Issued: 2010
An evaluation of building sustainability considerations in South Africa : a case of the SAIAB building
- Authors: Ngwadla, Xolisa
- Date: 2007
- Subjects: South African Institute for Aquatic Biodiversity Construction industry -- Environmental aspects -- South Africa Sustainable buildings -- Environmental aspects -- South Africa Sustainable buildings -- Design and construction -- South Africa Leadership in Energy and Environmental Design Green Building Rating System
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:821 , http://hdl.handle.net/10962/d1008375
- Description: The theory of sustainable development has received worldwide acceptance, and is characterised by the protection of environmental quality, social justice and economic development to ensure a quality of life for future generations. The concepts of sustainable development have transcended to all aspects of society, including the built environment through the Habitat Agenda and building sustainability rating tools. The thesis investigates the implications of sustainable development on how it relates to the building construction industry in South Africa. The study sought to evaluate the extent of consideration and motivation for the incorporation of sustainability criteria in building design, using the case of the South African Institute for Aquatic Biodiversity wet collection facility in Grahamstown. The goal of the thesis was achieved by evaluating sustainability considerations and barriers to adoption of sustainability criteria in the design of the SAlAB building, the rating of the building against the LEED ™ criteria, and evaluation of the applicability of the LEED ™ in the South African context. The importance of the research emanates from the fact that, despite the proliferation of sustainable development and sustainability rating tools in the world, there is no widely used building sustainability rating tool in South Africa, even though the country is industrialising with a very active built environment. The study therefore contributes to the body of knowledge necessary for the implementation of a building rating tool in the country, through an understanding of barriers to implementation. The research method used in the study was a case study with the intention of obtaining the design professional's considerations and challenges in the context of designing the SAIAB building. The case study used multiple data collection methods, with primary information obtained from interviews of professionals involved in the design of the building, whilst additional information was from analysis of technical drawings and review of literature on the subject. The findings of the research showed that there is an understanding of sustainability and consideration in the building industry even though there is no targeted intent to meet sustainability goals. The barriers to building sustainability were identified as lack of regulation, incentives, access to land, awareness, availability of professional codes and standards, economic costs and capacity. These barriers translated into a relatively low score, a silver rating for the SAlAB building when using the LEEDTM rating system. The implications of the findings suggests a need for the development of a comprehensive building sustainability rating tool suited for the South African context, with performance standards and a technical manual to support it. This should however be done in an environment where sustainability goals are supported by regulation and incentives have been developed.
- Full Text:
- Date Issued: 2007
- Authors: Ngwadla, Xolisa
- Date: 2007
- Subjects: South African Institute for Aquatic Biodiversity Construction industry -- Environmental aspects -- South Africa Sustainable buildings -- Environmental aspects -- South Africa Sustainable buildings -- Design and construction -- South Africa Leadership in Energy and Environmental Design Green Building Rating System
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:821 , http://hdl.handle.net/10962/d1008375
- Description: The theory of sustainable development has received worldwide acceptance, and is characterised by the protection of environmental quality, social justice and economic development to ensure a quality of life for future generations. The concepts of sustainable development have transcended to all aspects of society, including the built environment through the Habitat Agenda and building sustainability rating tools. The thesis investigates the implications of sustainable development on how it relates to the building construction industry in South Africa. The study sought to evaluate the extent of consideration and motivation for the incorporation of sustainability criteria in building design, using the case of the South African Institute for Aquatic Biodiversity wet collection facility in Grahamstown. The goal of the thesis was achieved by evaluating sustainability considerations and barriers to adoption of sustainability criteria in the design of the SAlAB building, the rating of the building against the LEED ™ criteria, and evaluation of the applicability of the LEED ™ in the South African context. The importance of the research emanates from the fact that, despite the proliferation of sustainable development and sustainability rating tools in the world, there is no widely used building sustainability rating tool in South Africa, even though the country is industrialising with a very active built environment. The study therefore contributes to the body of knowledge necessary for the implementation of a building rating tool in the country, through an understanding of barriers to implementation. The research method used in the study was a case study with the intention of obtaining the design professional's considerations and challenges in the context of designing the SAIAB building. The case study used multiple data collection methods, with primary information obtained from interviews of professionals involved in the design of the building, whilst additional information was from analysis of technical drawings and review of literature on the subject. The findings of the research showed that there is an understanding of sustainability and consideration in the building industry even though there is no targeted intent to meet sustainability goals. The barriers to building sustainability were identified as lack of regulation, incentives, access to land, awareness, availability of professional codes and standards, economic costs and capacity. These barriers translated into a relatively low score, a silver rating for the SAlAB building when using the LEEDTM rating system. The implications of the findings suggests a need for the development of a comprehensive building sustainability rating tool suited for the South African context, with performance standards and a technical manual to support it. This should however be done in an environment where sustainability goals are supported by regulation and incentives have been developed.
- Full Text:
- Date Issued: 2007
The relevance of sustainable development principles and goals through a case study of Gold Fields and Living Gold
- Authors: Ferreira, Adrian
- Date: 2007
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192977 , vital:45286
- Description: The conventional definition of sustainable development as proposed by the Brundtland Report (United Nations, 1987), involving the integration of economic, social and environmental components, is widely accepted. Presumed benefits of these current framework applications tend to perpetuate a business as usual status, with no real sustainable development occurring. The growing debate surrounding this topic makes the case for relevant and contextual inputs to be included into sustainable development objectives. A case study, of Gold Fields and Living Gold, attempts to create a deeper understanding of the components of this debate, and begins to contextualise sustainable development principles, goals and their outcomes. This is carried out though an enquiry of the use of cultural development as a fourth sustainable development category. The case study includes the opinions of a directly affected local community entity (Living Gold) in order to observe the difference between the two organisations (Gold Fields and Living Gold). During the study, the focus began to move away from purely unabated growth impacts and looked to the creation and fostering of resilience and flexibility by the use of adaptive management. In breeding states of resilience, it was recognised that cultural impacts played an important role in ensuring long term systemic resilience. The case study involved assessing the feedback and responses of strategically selected individuals at both organisations, with Gold Fields representing a more western centric entity and Living Gold a formal representation of a traditional/ indigenous community. Similarities and differences were assessed in order to understand how current sustainable development criteria might differ between organisations that have different end objectives in mind, yet are dependent on each other. The findings resulted in a perspective of how culture could be used to describe the qualities of a local community, and how to begin aligning development goals with affected communities. The result was the development of the Integrated Resilience Sustainability Method and the consequent development of the Balanced Bottom Line Framework, which seeks to promote sustainable development along the lines of economic, social, environmental and cultural development. , Thesis (MBA) -- Faculty of Commerce, Rhodes Investec Business School, 2007
- Full Text:
- Date Issued: 2007
- Authors: Ferreira, Adrian
- Date: 2007
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192977 , vital:45286
- Description: The conventional definition of sustainable development as proposed by the Brundtland Report (United Nations, 1987), involving the integration of economic, social and environmental components, is widely accepted. Presumed benefits of these current framework applications tend to perpetuate a business as usual status, with no real sustainable development occurring. The growing debate surrounding this topic makes the case for relevant and contextual inputs to be included into sustainable development objectives. A case study, of Gold Fields and Living Gold, attempts to create a deeper understanding of the components of this debate, and begins to contextualise sustainable development principles, goals and their outcomes. This is carried out though an enquiry of the use of cultural development as a fourth sustainable development category. The case study includes the opinions of a directly affected local community entity (Living Gold) in order to observe the difference between the two organisations (Gold Fields and Living Gold). During the study, the focus began to move away from purely unabated growth impacts and looked to the creation and fostering of resilience and flexibility by the use of adaptive management. In breeding states of resilience, it was recognised that cultural impacts played an important role in ensuring long term systemic resilience. The case study involved assessing the feedback and responses of strategically selected individuals at both organisations, with Gold Fields representing a more western centric entity and Living Gold a formal representation of a traditional/ indigenous community. Similarities and differences were assessed in order to understand how current sustainable development criteria might differ between organisations that have different end objectives in mind, yet are dependent on each other. The findings resulted in a perspective of how culture could be used to describe the qualities of a local community, and how to begin aligning development goals with affected communities. The result was the development of the Integrated Resilience Sustainability Method and the consequent development of the Balanced Bottom Line Framework, which seeks to promote sustainable development along the lines of economic, social, environmental and cultural development. , Thesis (MBA) -- Faculty of Commerce, Rhodes Investec Business School, 2007
- Full Text:
- Date Issued: 2007
The application of integrated environmental management to improve storm water quality and reduce marine pollution at Jeffreys Bay (South Africa)
- Authors: Seebach, Rudi Dieter
- Date: 2006
- Subjects: Marine pollution -- South Africa -- Jeffreys Bay , Storm sewers -- South Africa -- Jeffreys Bay , Marine ecology -- South Africa -- Jeffreys Bay , Environmental management -- South Africa -- Jeffreys Bay , Environmental risk assessment -- South Africa -- Jeffreys Bay , Community development -- South Africa -- Jeffreys Bay , Sustainable development -- South Africa -- Jeffreys Bay , Sewage disposal -- South Africa -- Jeffreys Bay
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4738 , http://hdl.handle.net/10962/d1005287 , Marine pollution -- South Africa -- Jeffreys Bay , Storm sewers -- South Africa -- Jeffreys Bay , Marine ecology -- South Africa -- Jeffreys Bay , Environmental management -- South Africa -- Jeffreys Bay , Environmental risk assessment -- South Africa -- Jeffreys Bay , Community development -- South Africa -- Jeffreys Bay , Sustainable development -- South Africa -- Jeffreys Bay , Sewage disposal -- South Africa -- Jeffreys Bay
- Description: It is projected that by 2025 three-quarters of the world’s population will live in the coastal zone. This is an alarming statistic, with a consequently significant impact on small coastal towns and the adjacent marine environments. Developing communities within the coastal zone of South Africa have proved to be a significant pollution source of storm water. Studies have shown that storm water that is deposited in the ocean will be trapped in the near shore marine environment causing poor seawater quality over a large distance. Furthermore, this can pose a significant threat to the health of recreational users and important marine ecosystems. In Jeffreys Bay storm water quality is thought to pose a threat to the maintenance of the international Blue Flag status for its beach. The aim of the current project was to investigate the main sources of storm water and subsequent marine pollution at Jeffreys Bay and to develop an appropriate management strategy using the integrated environmental management framework. In order to achieve this objective, it was also necessary to determine the current quality of water at various points within the catchment and near shore marine environment. Even though the storm water was found to be severely contaminated no evidence existed for a negative impact on the marine environment. None the less, a precautionary approach was adopted and a risk assessment employed in order to consider potential impacts on the marine and aquatic environment, human health and socio-economic welfare within the town. Significant sources of storm water contamination included grey water, domestic solid waste disposal and informal ablution. These significant aspects were investigated further and it was found that solid waste management in the catchment was poor with significant quantities of waste, primarily (76%) from domestic sources, being disposed of illegally. A study of sanitation management showed inadequacies where up to 58% of the residents from the informal settlements disposed of their grey water into open spaces. The ratio of residents to toilets in these areas was 28:1, therefore supporting the outcome of the risk assessment. Due to the fact that all the significant aspects were related to anthropogenic waste, an integrated waste management plan (IWMP) was developed that would not only facilitate the reduction of pollution of storm water, but would also allow for sustainable community-based development.
- Full Text:
- Date Issued: 2006
- Authors: Seebach, Rudi Dieter
- Date: 2006
- Subjects: Marine pollution -- South Africa -- Jeffreys Bay , Storm sewers -- South Africa -- Jeffreys Bay , Marine ecology -- South Africa -- Jeffreys Bay , Environmental management -- South Africa -- Jeffreys Bay , Environmental risk assessment -- South Africa -- Jeffreys Bay , Community development -- South Africa -- Jeffreys Bay , Sustainable development -- South Africa -- Jeffreys Bay , Sewage disposal -- South Africa -- Jeffreys Bay
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4738 , http://hdl.handle.net/10962/d1005287 , Marine pollution -- South Africa -- Jeffreys Bay , Storm sewers -- South Africa -- Jeffreys Bay , Marine ecology -- South Africa -- Jeffreys Bay , Environmental management -- South Africa -- Jeffreys Bay , Environmental risk assessment -- South Africa -- Jeffreys Bay , Community development -- South Africa -- Jeffreys Bay , Sustainable development -- South Africa -- Jeffreys Bay , Sewage disposal -- South Africa -- Jeffreys Bay
- Description: It is projected that by 2025 three-quarters of the world’s population will live in the coastal zone. This is an alarming statistic, with a consequently significant impact on small coastal towns and the adjacent marine environments. Developing communities within the coastal zone of South Africa have proved to be a significant pollution source of storm water. Studies have shown that storm water that is deposited in the ocean will be trapped in the near shore marine environment causing poor seawater quality over a large distance. Furthermore, this can pose a significant threat to the health of recreational users and important marine ecosystems. In Jeffreys Bay storm water quality is thought to pose a threat to the maintenance of the international Blue Flag status for its beach. The aim of the current project was to investigate the main sources of storm water and subsequent marine pollution at Jeffreys Bay and to develop an appropriate management strategy using the integrated environmental management framework. In order to achieve this objective, it was also necessary to determine the current quality of water at various points within the catchment and near shore marine environment. Even though the storm water was found to be severely contaminated no evidence existed for a negative impact on the marine environment. None the less, a precautionary approach was adopted and a risk assessment employed in order to consider potential impacts on the marine and aquatic environment, human health and socio-economic welfare within the town. Significant sources of storm water contamination included grey water, domestic solid waste disposal and informal ablution. These significant aspects were investigated further and it was found that solid waste management in the catchment was poor with significant quantities of waste, primarily (76%) from domestic sources, being disposed of illegally. A study of sanitation management showed inadequacies where up to 58% of the residents from the informal settlements disposed of their grey water into open spaces. The ratio of residents to toilets in these areas was 28:1, therefore supporting the outcome of the risk assessment. Due to the fact that all the significant aspects were related to anthropogenic waste, an integrated waste management plan (IWMP) was developed that would not only facilitate the reduction of pollution of storm water, but would also allow for sustainable community-based development.
- Full Text:
- Date Issued: 2006
The enzymology of enhanced hydrolysis within the biosulphidogenic recycling sludge bed reactor (RSBR)
- Authors: Enongene, Godlove Nkwelle
- Date: 2004
- Subjects: Hydrolysis , Sewage sludge , Sewage -- Purification -- Anaerobic treatment , Water -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4132 , http://hdl.handle.net/10962/d1015744
- Description: The hydrolysis of complex organic heteropolymers contained in municipal wastewater to simpler monomers by extracellular hydrolytic enzymes is generally considered the rate-limiting step of the biodegradation process. Previous studies of the Recycling Sludge Bed Reactor (RSBR) revealed that the hydrolysis of complex particulate organics, such as those contained in primary sludge (PS), was enhanced under anaerobic biosulphidogenic conditions. Although the mechanism was not fully understood, it appeared to involve the interaction of sulfide and sludge flocs. The current study was conducted using a 3500 ml laboratory-scale RSBR fed sieved PS at a loading rate of 0.5 kg COD/m³.day and an initial chemical oxygen demand (COD) to sulfate ratio (COD:SO₄) of 1:1. There was no significant accumulation of undigested sludge in the reactor over the 60-day experimental period and the quantity of SO₄ reduced indicated that the yield of soluble products from PS was at least as high as those reported previously for this system (> 50%). In the current study, the specific activities of a range of extracellular hydrolytic enzymes (L-alanine aminopeptidase, L-leucine aminopeptidase, arylsulphatase, α-glucosidase, β- glucosidase, protease and lipase) were monitored in a sulfide gradient within a biosulphidogenic RSBR. Data obtained indicated that the specific enzymatic activities increased with the depth of the RSBR and also correlated with a number of the physicochemical parameters including sulfide, alkalinity and sulfate. The activities of α- glucosidase and β-glucosidase were higher than that of the other enzymes studied. Lipase activity was relatively low and studies conducted on the enzyme-enzyme interaction using specific enzyme inhibitors indicated that lipases were probably being digested by the proteases. Further studies to determine the impact of sulfide on the enzymes, showed an increase in the enzyme activity with increasing sulfide concentration. Possible direct affects were investigated by looking for changes in the Michaelis constant (Km) and the maximal velocity (Vmax) of the crude enzymes with varying sulfide concentrations (250, 400 and 500 mg/l) using natural and synthetic substrates. The results showed no significant difference in both the Km and the Vmax for any of the hydrolytic enzymes except for the protease. The latter showed a statistically significant increase in the Km with increasing sulfide concentration. Although this indicated a direct interaction, this difference was not large enough to be of biochemical significance and was consequently not solely responsible for the enhanced hydrolysis observed in the RSBR. Investigation into the floc characteristics indicated that the biosulphidogenic RSBR flocs were generally small in size and became more dendritic with the depth of the RSBR. Based on the above data, the previously proposed descriptive models of enhanced hydrolysis of particulate organic matter in a biosulphidogenic RSBR has been revised. It is thought that the effect of sulfide on the hydrolysis step is primarily indirect and that the reduction in floc size and alteration of the floc shape to a more dendritic form is central to the success of the process.
- Full Text:
- Date Issued: 2004
- Authors: Enongene, Godlove Nkwelle
- Date: 2004
- Subjects: Hydrolysis , Sewage sludge , Sewage -- Purification -- Anaerobic treatment , Water -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4132 , http://hdl.handle.net/10962/d1015744
- Description: The hydrolysis of complex organic heteropolymers contained in municipal wastewater to simpler monomers by extracellular hydrolytic enzymes is generally considered the rate-limiting step of the biodegradation process. Previous studies of the Recycling Sludge Bed Reactor (RSBR) revealed that the hydrolysis of complex particulate organics, such as those contained in primary sludge (PS), was enhanced under anaerobic biosulphidogenic conditions. Although the mechanism was not fully understood, it appeared to involve the interaction of sulfide and sludge flocs. The current study was conducted using a 3500 ml laboratory-scale RSBR fed sieved PS at a loading rate of 0.5 kg COD/m³.day and an initial chemical oxygen demand (COD) to sulfate ratio (COD:SO₄) of 1:1. There was no significant accumulation of undigested sludge in the reactor over the 60-day experimental period and the quantity of SO₄ reduced indicated that the yield of soluble products from PS was at least as high as those reported previously for this system (> 50%). In the current study, the specific activities of a range of extracellular hydrolytic enzymes (L-alanine aminopeptidase, L-leucine aminopeptidase, arylsulphatase, α-glucosidase, β- glucosidase, protease and lipase) were monitored in a sulfide gradient within a biosulphidogenic RSBR. Data obtained indicated that the specific enzymatic activities increased with the depth of the RSBR and also correlated with a number of the physicochemical parameters including sulfide, alkalinity and sulfate. The activities of α- glucosidase and β-glucosidase were higher than that of the other enzymes studied. Lipase activity was relatively low and studies conducted on the enzyme-enzyme interaction using specific enzyme inhibitors indicated that lipases were probably being digested by the proteases. Further studies to determine the impact of sulfide on the enzymes, showed an increase in the enzyme activity with increasing sulfide concentration. Possible direct affects were investigated by looking for changes in the Michaelis constant (Km) and the maximal velocity (Vmax) of the crude enzymes with varying sulfide concentrations (250, 400 and 500 mg/l) using natural and synthetic substrates. The results showed no significant difference in both the Km and the Vmax for any of the hydrolytic enzymes except for the protease. The latter showed a statistically significant increase in the Km with increasing sulfide concentration. Although this indicated a direct interaction, this difference was not large enough to be of biochemical significance and was consequently not solely responsible for the enhanced hydrolysis observed in the RSBR. Investigation into the floc characteristics indicated that the biosulphidogenic RSBR flocs were generally small in size and became more dendritic with the depth of the RSBR. Based on the above data, the previously proposed descriptive models of enhanced hydrolysis of particulate organic matter in a biosulphidogenic RSBR has been revised. It is thought that the effect of sulfide on the hydrolysis step is primarily indirect and that the reduction in floc size and alteration of the floc shape to a more dendritic form is central to the success of the process.
- Full Text:
- Date Issued: 2004
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