An investigation into water and sanitation in the Eastern Cape Province and potential for implementation of biotechnology platforms
- Authors: Gumunyu, Wilbert
- Date: 2022-10-14
- Subjects: Sewage South Africa Eastern Cape , Sanitation South Africa Eastern Cape , Algae Biotechnology , Biotechnology , Sewage Purification Biological treatment , Algal biofuels
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/362830 , vital:65366
- Description: In contemporary South Africa, a country in transition, destruction rather than reconstruction seems commonplace. Electricity supply is at an all-time low and ‘load shedding’ is an almost daily occurrence. Similarly, more fragility of water delivery and sanitation service is being reported with the likelihood of ‘water shedding’ a soon-to-be reality. In view of the ever-increasing reported mismanagement of South Africa’s water and sanitation infrastructure, which is likely nearing the point of collapse if not already collapsed, this thesis set out to interrogate at a provincial and municipal level the status of water and sanitation in Chris Hani District Municipality (CHDM), Eastern Cape Province. One major driver behind this study was to evaluate provincial and municipal water/wastewater infrastructure as a platform to support implementation of locally developed bioprocess technologies. First, publicly available historical data was used to derive a baseline or benchmark from which to determine gains/losses in compliance, water quality and efficiency. The period 2009-2013/4 during which Blue and Green Drop reporting was routine, was used as an appropriate start point. Data thus derived indicated that, at provincial and district municipality (DM) level, potable water supply was by bulk water schemes and, sanitation was typically by waste stabilization pond (WSP) treatment of municipal sewage. The derived benchmark for the period 2009-2013/14 indicated that most plants were not compliant (~75% of the Eastern Cape Province water treatment plants (WTP) operating between average performance to critical state), operated either at- or above design capacity (Eastern Cape Province, 16%; CHDM, 19%). A large number of plants for the province (62.4%) and district (81.25%) had hydraulic design capacity or average daily flows that were unknown (information not provided in available literature or plant reports) and final effluent did not always meet the general standard (70.3% of the CHDM wastewater treatment works (WWTW)). To determine the contemporary state (2020 - 2022) of water and sanitation within CHDM, a scoping exercise of WTP and WWTW in selected local municipalities was carried out. This was done along a west-east transect by appraising WTP and WWTW in the towns of Cradock, Tarkastad, Komani, Tsomo, Cacadu, and Ngcobo. Furthermore, targeted assessment of the Queenstown WTP and the Cradock WWTW was used to derive real-time data on the status of water and sanitation infrastructure. Results showed that water and sanitation services within CHDM had, in the years between 2009-2013/14 to date, deteriorated. Freshwater demand significantly exceeded capability of water supply schemes, where demand was as much as three times greater than reported available supply. For most WWTW, operation was in excess of capacity and between 1.52 and 12 times installed hydraulic loading. The targeted scoping exercise revealed that Queenstown WTP is a moderate risk plant (Cumulative risk rating, CRR = 11 and maximum risk rating, MRR = 47.8%), whereas Cradock WWTW was in working condition but with challenges and some infrastructural dysfunction. Assessment of water/effluent quality revealed that turbidity and TOC were above SANS 241 general limit. Non-compliance in terms of nitrate/nitrite-N, ammonium-N, phosphate-P, TSS, total coliforms, E. Coli, and free chlorine was evident at Cradock WWTW. Unstructured interviews with plant operators corroborated these findings. The overwhelming support for bulk schemes for potable water provision and WSP for sanitation indicated a partially water secure municipal district but derelict in terms of its sanitation services. The later, it was concluded, in particular provides an ideal opportunity for implementation of platform technologies to support bioprocesses for entrepreneurship, employment, economic benefit and to secure a closed circular economy for regional water and sanitation through valorisation of co-product streams. Among the co-product streams considered in this thesis are biomass, biogas, biofertilizers, biofuels and several high value chemical products. , Thesis (MSc) -- Faculty of Science, Institute for Environmental Biotechnology, 2022
- Full Text:
- Date Issued: 2022-10-14
- Authors: Gumunyu, Wilbert
- Date: 2022-10-14
- Subjects: Sewage South Africa Eastern Cape , Sanitation South Africa Eastern Cape , Algae Biotechnology , Biotechnology , Sewage Purification Biological treatment , Algal biofuels
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/362830 , vital:65366
- Description: In contemporary South Africa, a country in transition, destruction rather than reconstruction seems commonplace. Electricity supply is at an all-time low and ‘load shedding’ is an almost daily occurrence. Similarly, more fragility of water delivery and sanitation service is being reported with the likelihood of ‘water shedding’ a soon-to-be reality. In view of the ever-increasing reported mismanagement of South Africa’s water and sanitation infrastructure, which is likely nearing the point of collapse if not already collapsed, this thesis set out to interrogate at a provincial and municipal level the status of water and sanitation in Chris Hani District Municipality (CHDM), Eastern Cape Province. One major driver behind this study was to evaluate provincial and municipal water/wastewater infrastructure as a platform to support implementation of locally developed bioprocess technologies. First, publicly available historical data was used to derive a baseline or benchmark from which to determine gains/losses in compliance, water quality and efficiency. The period 2009-2013/4 during which Blue and Green Drop reporting was routine, was used as an appropriate start point. Data thus derived indicated that, at provincial and district municipality (DM) level, potable water supply was by bulk water schemes and, sanitation was typically by waste stabilization pond (WSP) treatment of municipal sewage. The derived benchmark for the period 2009-2013/14 indicated that most plants were not compliant (~75% of the Eastern Cape Province water treatment plants (WTP) operating between average performance to critical state), operated either at- or above design capacity (Eastern Cape Province, 16%; CHDM, 19%). A large number of plants for the province (62.4%) and district (81.25%) had hydraulic design capacity or average daily flows that were unknown (information not provided in available literature or plant reports) and final effluent did not always meet the general standard (70.3% of the CHDM wastewater treatment works (WWTW)). To determine the contemporary state (2020 - 2022) of water and sanitation within CHDM, a scoping exercise of WTP and WWTW in selected local municipalities was carried out. This was done along a west-east transect by appraising WTP and WWTW in the towns of Cradock, Tarkastad, Komani, Tsomo, Cacadu, and Ngcobo. Furthermore, targeted assessment of the Queenstown WTP and the Cradock WWTW was used to derive real-time data on the status of water and sanitation infrastructure. Results showed that water and sanitation services within CHDM had, in the years between 2009-2013/14 to date, deteriorated. Freshwater demand significantly exceeded capability of water supply schemes, where demand was as much as three times greater than reported available supply. For most WWTW, operation was in excess of capacity and between 1.52 and 12 times installed hydraulic loading. The targeted scoping exercise revealed that Queenstown WTP is a moderate risk plant (Cumulative risk rating, CRR = 11 and maximum risk rating, MRR = 47.8%), whereas Cradock WWTW was in working condition but with challenges and some infrastructural dysfunction. Assessment of water/effluent quality revealed that turbidity and TOC were above SANS 241 general limit. Non-compliance in terms of nitrate/nitrite-N, ammonium-N, phosphate-P, TSS, total coliforms, E. Coli, and free chlorine was evident at Cradock WWTW. Unstructured interviews with plant operators corroborated these findings. The overwhelming support for bulk schemes for potable water provision and WSP for sanitation indicated a partially water secure municipal district but derelict in terms of its sanitation services. The later, it was concluded, in particular provides an ideal opportunity for implementation of platform technologies to support bioprocesses for entrepreneurship, employment, economic benefit and to secure a closed circular economy for regional water and sanitation through valorisation of co-product streams. Among the co-product streams considered in this thesis are biomass, biogas, biofertilizers, biofuels and several high value chemical products. , Thesis (MSc) -- Faculty of Science, Institute for Environmental Biotechnology, 2022
- Full Text:
- Date Issued: 2022-10-14
Bacterial colonisation and degradation of geologically weathered and discard coal
- Authors: Olawale, Jacob Taiwo
- Date: 2018
- Subjects: Coal mine waste , Coal -- Biodegradation , Coal mines and mining -- Environmental aspects , Land degradation , Electron microscopy , Extracellular polymeric substances , Flagella (Microbiology) , Fourier transform infrared spectroscopy , Microbiologically influenced corrosion
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61625 , vital:28043
- Description: Bacterial beneficiation of low-grade coal, coal discard, and waste has the potential to mitigate land degradation, water and soil pollution and, be a strategy for mining companies to responsibly extract and process coal with environmental sustainability. This study investigated the colonisation and biodegradation or depolymerisation of coal discard and geologically weathered coal by selected strains of bacteria, and an attempt has been made to describe the mechanisms associated with colonisation and biodegradation of this carbonaceous material. Ten bacterial strains, Bacillus strain ECCN 18b, Citrobacter strain ECCN 19b, Proteus strain ECCN 20b, Exiguobacterium strain ECCN 21b, Microbacterium strain ECCN 22b, Proteus strain ECCN 23b, Serratia strain ECCN 24b, Escherichia strain ECCN 25b, Bacillus strain ECCN 26b and Bacillus strain ECCN 41b, isolated from diesel-contaminated soil and coal slurry and identified using DNA sequencing, were rescreened and their coal biodegradation potential ranked. The ranking of the bacterial strains was undertaken using several indicators including; formation of brown halos on the plate culture (solid), change in colour intensity of the medium in liquid culture, change in culture media pH, and an increase in absorbance at 280nm and 450nm. Although, all the ten strains showed evidence of biodegradation of coal discard and geologically weathered coal based on the ranking employed, and the three strains considered the best candidates were Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b. The actions of the three bacterial strains were further studied and characterised in relation to coal degradation. Electron microscopy revealed that Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b attached to the surface of coal discard and geologically weathered coal by a process that appeared to involve extracellular polymeric substances (EPS), and flagella. The presence of flagella for Citrobacter strain ECCN 19b and Serratia strain ECCN 24b was confirmed by transmission electron microscopy. Bacterial degradation of coal discard and geologically weathered coal by these selected strains resulted in the release of soluble and insoluble products. Ultraviolet/ visible spectrophotometric (UV/VIS) analysis revealed that the soluble products resembled humic acid-like substances, which was confirmed following Fourier Transform Infrared (FTIR) spectroscopy. Analysis revealed that the coal-derived humic acid-like substances were similar to commercial humic acid extracted from bituminous coal. Elemental analysis of the insoluble product residue after bacterial biodegradation revealed the modification of the chemical compositions of the coal discard and geologically weathered coal substrates. Characterisation of the functional groups of the insoluble product using FTIR spectroscopy indicated changes, with the appearance of new peaks at 1737cm-1, 1366cm-1, 1228cm-1, and 1216cm-1 characteristic of aldehyde, ketones, carboxylic acids, esters, amines, and alkanes. Broad spectra regions of 3500 -3200cm-1, characteristic of alcohol and phenol, were also observed. Together, these results were taken as evidence for increased oxidation of the coal substrates, presumably as a consequence of bacterial catalysed biodegradation of coal discard and geologically weathered coal. During bacterial degradation of coal discard and geologically weathered coal, strains produced extracellular protein, which was detected and further investigated using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS- PAGE). At least three protein bands with molecular mass 53 kDa, 72 kDa, and 82 kDa were common to the three bacterial strains. Following ammonium sulphate precipitation and gel filtration chromatography, additional bands with molecular mass 16 kDa, 33 kDa, 37 kDa, and 43 kDa were detected. An extracellular laccase activity was detected in cultures of Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b. Cytochrome P450 activity was detected in all the bacterial strains in the presence of both coal discard and geologically weathered coal. This is the first time that cytochrome P450 activity has been reported following exposure of these three bacterial strains to a coal substrate. Overall, this research has successfully demonstrated the partial degradation of coal discard and geologically weathered coal by Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b and the release of humic acid-like substances. Thus, the biodegradation process involved adherence to and growth of the bacteria on the surface of coal substrate and appeared to require the formation of alkaline substances and the combined activities of extracellular LAC and cytochrome P450. Since bacterial degradation of low-grade coal and discard appears to be viable, the bacteria isolated in this study can potentially be used either for conversion of discard into valuable chemicals or to mitigate the deleterious effects of stockpiled coal discard on the environment.
- Full Text:
- Date Issued: 2018
- Authors: Olawale, Jacob Taiwo
- Date: 2018
- Subjects: Coal mine waste , Coal -- Biodegradation , Coal mines and mining -- Environmental aspects , Land degradation , Electron microscopy , Extracellular polymeric substances , Flagella (Microbiology) , Fourier transform infrared spectroscopy , Microbiologically influenced corrosion
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61625 , vital:28043
- Description: Bacterial beneficiation of low-grade coal, coal discard, and waste has the potential to mitigate land degradation, water and soil pollution and, be a strategy for mining companies to responsibly extract and process coal with environmental sustainability. This study investigated the colonisation and biodegradation or depolymerisation of coal discard and geologically weathered coal by selected strains of bacteria, and an attempt has been made to describe the mechanisms associated with colonisation and biodegradation of this carbonaceous material. Ten bacterial strains, Bacillus strain ECCN 18b, Citrobacter strain ECCN 19b, Proteus strain ECCN 20b, Exiguobacterium strain ECCN 21b, Microbacterium strain ECCN 22b, Proteus strain ECCN 23b, Serratia strain ECCN 24b, Escherichia strain ECCN 25b, Bacillus strain ECCN 26b and Bacillus strain ECCN 41b, isolated from diesel-contaminated soil and coal slurry and identified using DNA sequencing, were rescreened and their coal biodegradation potential ranked. The ranking of the bacterial strains was undertaken using several indicators including; formation of brown halos on the plate culture (solid), change in colour intensity of the medium in liquid culture, change in culture media pH, and an increase in absorbance at 280nm and 450nm. Although, all the ten strains showed evidence of biodegradation of coal discard and geologically weathered coal based on the ranking employed, and the three strains considered the best candidates were Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b. The actions of the three bacterial strains were further studied and characterised in relation to coal degradation. Electron microscopy revealed that Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b attached to the surface of coal discard and geologically weathered coal by a process that appeared to involve extracellular polymeric substances (EPS), and flagella. The presence of flagella for Citrobacter strain ECCN 19b and Serratia strain ECCN 24b was confirmed by transmission electron microscopy. Bacterial degradation of coal discard and geologically weathered coal by these selected strains resulted in the release of soluble and insoluble products. Ultraviolet/ visible spectrophotometric (UV/VIS) analysis revealed that the soluble products resembled humic acid-like substances, which was confirmed following Fourier Transform Infrared (FTIR) spectroscopy. Analysis revealed that the coal-derived humic acid-like substances were similar to commercial humic acid extracted from bituminous coal. Elemental analysis of the insoluble product residue after bacterial biodegradation revealed the modification of the chemical compositions of the coal discard and geologically weathered coal substrates. Characterisation of the functional groups of the insoluble product using FTIR spectroscopy indicated changes, with the appearance of new peaks at 1737cm-1, 1366cm-1, 1228cm-1, and 1216cm-1 characteristic of aldehyde, ketones, carboxylic acids, esters, amines, and alkanes. Broad spectra regions of 3500 -3200cm-1, characteristic of alcohol and phenol, were also observed. Together, these results were taken as evidence for increased oxidation of the coal substrates, presumably as a consequence of bacterial catalysed biodegradation of coal discard and geologically weathered coal. During bacterial degradation of coal discard and geologically weathered coal, strains produced extracellular protein, which was detected and further investigated using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS- PAGE). At least three protein bands with molecular mass 53 kDa, 72 kDa, and 82 kDa were common to the three bacterial strains. Following ammonium sulphate precipitation and gel filtration chromatography, additional bands with molecular mass 16 kDa, 33 kDa, 37 kDa, and 43 kDa were detected. An extracellular laccase activity was detected in cultures of Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b. Cytochrome P450 activity was detected in all the bacterial strains in the presence of both coal discard and geologically weathered coal. This is the first time that cytochrome P450 activity has been reported following exposure of these three bacterial strains to a coal substrate. Overall, this research has successfully demonstrated the partial degradation of coal discard and geologically weathered coal by Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b and the release of humic acid-like substances. Thus, the biodegradation process involved adherence to and growth of the bacteria on the surface of coal substrate and appeared to require the formation of alkaline substances and the combined activities of extracellular LAC and cytochrome P450. Since bacterial degradation of low-grade coal and discard appears to be viable, the bacteria isolated in this study can potentially be used either for conversion of discard into valuable chemicals or to mitigate the deleterious effects of stockpiled coal discard on the environment.
- Full Text:
- Date Issued: 2018
Performance evaluation and cost analysis of subsurface flow constructed wetlands designed for ammonium-nitrogen removal
- Authors: Tebitendwa, Sylvie Muwanga
- Date: 2018
- Subjects: Sewage Purification Nitrogen removal , Constructed wetlands , Bioremediation , Sewage lagoons , Coal mine waste
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61808 , vital:28062
- Description: Subsurface flow constructed wetlands (SSF CWs) is a low-cost, environmentally friendly sanitation technology for on-site treatment of domestic/municipal sewage. However, these systems are apparently unable to produce treated water of a quality suitable for discharge particularly in terms of nitrogen concentration, which has been attributed to design and operation based on biological oxygen demand as the parameter of choice. The aim of this study was to evaluate the performance, support medium, and techno-economics of a vertical- horizontal (V-H) SSF hybrid CW designed and operated using ammonium-nitrogen (NH4+-N) as the major parameter. Two pilot scale V-H SSF hybrid CWs were designed, constructed, and the performance of each monitored over two seasons and under two phases i.e. an initiation phase, and an optimization phase. Laboratory-scale horizontal SSF CWs were used to evaluate the support medium while the techno-economic study was framed to determine the cost effectiveness of V-H SSF hybrid CWs relative to high rate algal oxidation pond (HRAOP) systems to increase capacity of overloaded and/or under-performing waste stabilization pond (WSP) sewage treatment plants. Results revealed that under optimal operating conditions of hydraulic loading rate, hydraulic retention, and influent NH4+-N loading rate, treated water from the V-H SSF hybrid CWs achieved a quality commensurate with current South African standards for discharge into a surface water resource for all parameters except chemical oxygen demand and faecal coliforms. This suggests that NH4+-N is an important design and operational parameter for SSF CWs treating municipal sewage that is characterised as weak in terms of NH4+-N with a requirement of only simple disinfection such as chlorination to eliminate faecal coliforms. Use of discard coal to replace gravel as support medium in horizontal SSF CWs revealed an overall reduction in elemental composition of the discard coal support medium but without compromising water quality. This result strongly supports use of discard coal as an appropriate substrate for SSF CWs to achieve acceptable water quality. Furthermore, simultaneous degradation of discard coal during wastewater treatment demonstrates the versatility of SSF CWs for use in bio-remediation and pollution control. Finally, a technoeconomic assessment of V-H SSF hybrid CWs and a HRAOP series was carried out to determine the suitability of each process to increase capacity by mitigating dysfunctional and/or overloaded WSP sewage treatment plants. Analysis revealed that the quality of treated water from both systems was within the South African General Authorization standards for discharge to a surface water resource. Even so, each technology system presented its own set of limitations including; the inability to satisfactorily remove NH4+-N and chemical oxygen demand (i.e. for V-H SSF hybrid CWs) and total suspended solids and faecal coliforms (i.e. for HRAOPs), and a requirement for substantial land footprint while, HRAOPs required significantly less capital than V-H SSF hybrid CWs for implementation. The latter suggests that HRAOPs could be preferred over V-H SSF hybrid CWs as a technology of choice to increase the capacity of overloaded WSP sewage treatment plants especially where financial resources are limited. Overall, the results of this thesis indicate the potential to use NH4+-N as a design parameter in constructing SSF CWs treating weak strength municipal sewage (i.e. in terms of NH4+-N concentration) and to supplant gravel as the treatment media with industrial waste material like discard coal to achieve wastewater treatment, bio-remediation, and pollution control. The results of this work are discussed in terms of using SSF CWs as a passive and resilient technology for the treatment of domestic sewage in sub-Saharan Africa.
- Full Text:
- Date Issued: 2018
- Authors: Tebitendwa, Sylvie Muwanga
- Date: 2018
- Subjects: Sewage Purification Nitrogen removal , Constructed wetlands , Bioremediation , Sewage lagoons , Coal mine waste
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61808 , vital:28062
- Description: Subsurface flow constructed wetlands (SSF CWs) is a low-cost, environmentally friendly sanitation technology for on-site treatment of domestic/municipal sewage. However, these systems are apparently unable to produce treated water of a quality suitable for discharge particularly in terms of nitrogen concentration, which has been attributed to design and operation based on biological oxygen demand as the parameter of choice. The aim of this study was to evaluate the performance, support medium, and techno-economics of a vertical- horizontal (V-H) SSF hybrid CW designed and operated using ammonium-nitrogen (NH4+-N) as the major parameter. Two pilot scale V-H SSF hybrid CWs were designed, constructed, and the performance of each monitored over two seasons and under two phases i.e. an initiation phase, and an optimization phase. Laboratory-scale horizontal SSF CWs were used to evaluate the support medium while the techno-economic study was framed to determine the cost effectiveness of V-H SSF hybrid CWs relative to high rate algal oxidation pond (HRAOP) systems to increase capacity of overloaded and/or under-performing waste stabilization pond (WSP) sewage treatment plants. Results revealed that under optimal operating conditions of hydraulic loading rate, hydraulic retention, and influent NH4+-N loading rate, treated water from the V-H SSF hybrid CWs achieved a quality commensurate with current South African standards for discharge into a surface water resource for all parameters except chemical oxygen demand and faecal coliforms. This suggests that NH4+-N is an important design and operational parameter for SSF CWs treating municipal sewage that is characterised as weak in terms of NH4+-N with a requirement of only simple disinfection such as chlorination to eliminate faecal coliforms. Use of discard coal to replace gravel as support medium in horizontal SSF CWs revealed an overall reduction in elemental composition of the discard coal support medium but without compromising water quality. This result strongly supports use of discard coal as an appropriate substrate for SSF CWs to achieve acceptable water quality. Furthermore, simultaneous degradation of discard coal during wastewater treatment demonstrates the versatility of SSF CWs for use in bio-remediation and pollution control. Finally, a technoeconomic assessment of V-H SSF hybrid CWs and a HRAOP series was carried out to determine the suitability of each process to increase capacity by mitigating dysfunctional and/or overloaded WSP sewage treatment plants. Analysis revealed that the quality of treated water from both systems was within the South African General Authorization standards for discharge to a surface water resource. Even so, each technology system presented its own set of limitations including; the inability to satisfactorily remove NH4+-N and chemical oxygen demand (i.e. for V-H SSF hybrid CWs) and total suspended solids and faecal coliforms (i.e. for HRAOPs), and a requirement for substantial land footprint while, HRAOPs required significantly less capital than V-H SSF hybrid CWs for implementation. The latter suggests that HRAOPs could be preferred over V-H SSF hybrid CWs as a technology of choice to increase the capacity of overloaded WSP sewage treatment plants especially where financial resources are limited. Overall, the results of this thesis indicate the potential to use NH4+-N as a design parameter in constructing SSF CWs treating weak strength municipal sewage (i.e. in terms of NH4+-N concentration) and to supplant gravel as the treatment media with industrial waste material like discard coal to achieve wastewater treatment, bio-remediation, and pollution control. The results of this work are discussed in terms of using SSF CWs as a passive and resilient technology for the treatment of domestic sewage in sub-Saharan Africa.
- Full Text:
- Date Issued: 2018
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