Towards the bioremediation of the hypertrophic Swartkops Solar Salt-works
- Authors: Difford, Mark
- Date: 2008
- Subjects: Salt industry and trade -- South Africa -- Port Elizabeth , Bioremediation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10606 , http://hdl.handle.net/10948/1506 , Salt industry and trade -- South Africa -- Port Elizabeth , Bioremediation
- Description: This thesis presents the results of three studies aimed at improving brine-quality at the Swartkops solar salt-works (Swartkops Sea Salt [Pty] Ltd) on the outskirts of Port Elizabeth, South Africa. This is a highly eutrophic salt-works, the management of which has become increasingly difficult in recent years. The fundamental problem is how best to operate the system at maximum capacity while limiting nutrient inputs from the nutrient-rich microtidal Swartkops Estuary. In the first study, brine-quality at several sites along the axis of the Swartkops Estuary, and the extent to which it is affected by a variety of factors, is compared. Sites were sampled on micro- and macrotidal time scales, and were selected by the management of the salt-works as possible locations for a new pump-house (for extracting brine from the estuary) for their salt-work operations at Swartkops and Missionvale. The study showed that there are incremental benefits to be had from moving the site of extraction downstream from its present position to a site closer to the mouth of the estuary, where the concentration of nutrients usually is lower and where salinity usually is higher. There is little to be gained from moving the site of extraction laterally, to the mouth of the Inlet from which brine currently is extracted, so that brine is extracted directly from the estuary itself. A set of models relating the concentrations of NH+ 4 , NO{u100000}3 , and PO34{u100000} to salinity is proposed. These take into account the influences of site and season and may be used to estimate the concentration of these nutrients from a measurement of salinity. The model for PO34{u100000} shows that it would be more damaging to the salt-works’ operations to pump “low”-salinity brine during the early months of summer than during autumn. Evidence is also presented to show that Wylde Bridge has no influence on nutrient concentrations in the estuary, with tidal flushing generally passing beyond the Wylde-Bridge break-point. The exceptionally heavy flooding of the estuary that occurred in September 2002 may, however, have biased this conclusion, because of its scouring effect. The second study concentrated on monitoring the effect of (1) decreasing pond depth and (2) increasing pond salinity—two readily available management tools—on brine quality at the salt-works. Pond depth throughout the salt-works was decreased by 40 cm, and the salinity of Pond 5, a pond in the middle of the system, was increased to 175 S. Both measures were kept in place for the duration of the study (Nov. 2002–Aug. 2004). The pond-depth experiment did not have the expected result, there being no evidence of the increase in microalgal growth in the water column that was predicted based on previous research. There was, however, a significant increase in benthic chlorophyll-a, and there was a general improvement in the condition of the sedimentary system of the salt-works. There was also a substantial decrease in particulate organic matter in the water column, with clear evidence that the remaining fraction was closely associated with living forms of particulate matter rather than with detritus. The pond-salinity experiment proves that there is a flourishing, and resilient, population of brine shrimp (Artemia salina L.) at the salt-works. Restocking the salina, or stocking it with a different strain of brine shrimp, is therefore not necessary. The results of this study show that the brine shrimp population at the salt-works needs salinities of greater than about 65–70 S to survive. As a living force they almost certainly need a protective salinity that is greater than about 120–140 S, perhaps even as great as 160 S. Brine shrimp thrived in the high salinity milieu of the experimental pond for the duration of the study, but dwindled from three other ponds of the system once their salinities fell to below 90 S, eventually to disappear from them, apparently completely, once salinity fell to below 65 S. The third and final study concentrated on establishing whether the products released by decomposing barley straw could be used in a solar salt-works to control macroalgal blooms without detrimentally affecting the benthic-mat. Previous research has shown that these products are effective inhibitors of macroalgal growth and that they remain effective under saline conditions. The results presented here show that the same products, or products released under similar conditions of decomposition, adversely effect both the structure and the function of the mat. Consequently, their use in a solar salt-works cannot be recommended.
- Full Text:
- Date Issued: 2008
- Authors: Difford, Mark
- Date: 2008
- Subjects: Salt industry and trade -- South Africa -- Port Elizabeth , Bioremediation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10606 , http://hdl.handle.net/10948/1506 , Salt industry and trade -- South Africa -- Port Elizabeth , Bioremediation
- Description: This thesis presents the results of three studies aimed at improving brine-quality at the Swartkops solar salt-works (Swartkops Sea Salt [Pty] Ltd) on the outskirts of Port Elizabeth, South Africa. This is a highly eutrophic salt-works, the management of which has become increasingly difficult in recent years. The fundamental problem is how best to operate the system at maximum capacity while limiting nutrient inputs from the nutrient-rich microtidal Swartkops Estuary. In the first study, brine-quality at several sites along the axis of the Swartkops Estuary, and the extent to which it is affected by a variety of factors, is compared. Sites were sampled on micro- and macrotidal time scales, and were selected by the management of the salt-works as possible locations for a new pump-house (for extracting brine from the estuary) for their salt-work operations at Swartkops and Missionvale. The study showed that there are incremental benefits to be had from moving the site of extraction downstream from its present position to a site closer to the mouth of the estuary, where the concentration of nutrients usually is lower and where salinity usually is higher. There is little to be gained from moving the site of extraction laterally, to the mouth of the Inlet from which brine currently is extracted, so that brine is extracted directly from the estuary itself. A set of models relating the concentrations of NH+ 4 , NO{u100000}3 , and PO34{u100000} to salinity is proposed. These take into account the influences of site and season and may be used to estimate the concentration of these nutrients from a measurement of salinity. The model for PO34{u100000} shows that it would be more damaging to the salt-works’ operations to pump “low”-salinity brine during the early months of summer than during autumn. Evidence is also presented to show that Wylde Bridge has no influence on nutrient concentrations in the estuary, with tidal flushing generally passing beyond the Wylde-Bridge break-point. The exceptionally heavy flooding of the estuary that occurred in September 2002 may, however, have biased this conclusion, because of its scouring effect. The second study concentrated on monitoring the effect of (1) decreasing pond depth and (2) increasing pond salinity—two readily available management tools—on brine quality at the salt-works. Pond depth throughout the salt-works was decreased by 40 cm, and the salinity of Pond 5, a pond in the middle of the system, was increased to 175 S. Both measures were kept in place for the duration of the study (Nov. 2002–Aug. 2004). The pond-depth experiment did not have the expected result, there being no evidence of the increase in microalgal growth in the water column that was predicted based on previous research. There was, however, a significant increase in benthic chlorophyll-a, and there was a general improvement in the condition of the sedimentary system of the salt-works. There was also a substantial decrease in particulate organic matter in the water column, with clear evidence that the remaining fraction was closely associated with living forms of particulate matter rather than with detritus. The pond-salinity experiment proves that there is a flourishing, and resilient, population of brine shrimp (Artemia salina L.) at the salt-works. Restocking the salina, or stocking it with a different strain of brine shrimp, is therefore not necessary. The results of this study show that the brine shrimp population at the salt-works needs salinities of greater than about 65–70 S to survive. As a living force they almost certainly need a protective salinity that is greater than about 120–140 S, perhaps even as great as 160 S. Brine shrimp thrived in the high salinity milieu of the experimental pond for the duration of the study, but dwindled from three other ponds of the system once their salinities fell to below 90 S, eventually to disappear from them, apparently completely, once salinity fell to below 65 S. The third and final study concentrated on establishing whether the products released by decomposing barley straw could be used in a solar salt-works to control macroalgal blooms without detrimentally affecting the benthic-mat. Previous research has shown that these products are effective inhibitors of macroalgal growth and that they remain effective under saline conditions. The results presented here show that the same products, or products released under similar conditions of decomposition, adversely effect both the structure and the function of the mat. Consequently, their use in a solar salt-works cannot be recommended.
- Full Text:
- Date Issued: 2008
Hydrogenases from sulphate reducing bacteria and their role in the bioremediation of textile effluent
- Mutambanengwe, Cecil Clifford Zvandada
- Authors: Mutambanengwe, Cecil Clifford Zvandada
- Date: 2007
- Subjects: Bioremediation , Dyes and dyeing -- Waste disposal , Sulfur bacteria , Hydragenase , Factory and trade waste -- Purification , Textile waste
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3960 , http://hdl.handle.net/10962/d1004019 , Bioremediation , Dyes and dyeing -- Waste disposal , Sulfur bacteria , Hydragenase , Factory and trade waste -- Purification , Textile waste
- Description: The continuing industrial development has led to a corresponding increase in the amount of waste water generation leading to a consequential decline in levels and quality of the natural water in the ecosystem. Textile industries consume over 7 x 10[superscript 5] tons of dyes annually and use up to 1 litre of water per kg of dye processed and are third largest polluters in the world, the problem being aggravated by the inefficiencies of the dye houses. An abundance of physio-chemical methods are in use world wide, however, there is increasing concern as to their impact in effectively treating textile effluents as they introduce secondary pollutants during the ‘remediation’ process which are quite costly to run, maintain and clean up. Research on biological treatment has offered simple and cost effective ways of bioremediating textile effluents. While aerobic treatment of textile dyes and their effluents has been reported, its major draw back is commercial up-scaling and as such anaerobic systems have been investigated and shown to degrade azo dyes, which form the bulk of the dyes used world wide. However, the mechanisms involved in the bioremediation of these dyes are poorly understood. The aims of this study were to identify and investigate the role of enzymes produced by sulphate reducing bacteria (SRB) in bioremediating textile dye and their effluents. Sulphate reducing bacteria were used in this study because they are tolerant to harsh environmental conditions and inhibit the proliferance of pathogenic micro-organisms. The appearance of clear zones in agar plates containing azo dye concentrations ranging from 10 – 100 mgl[superscript -1] showed the ability of SRB to decolourize dyes under anaerobic conditions. Assays of enzymes previously reported to decolourise azo dyes were not successful, but led to the identification of hydrogenase enzyme being produced by SRB. The enzyme was found to be localised in the membrane and cytoplasm. A surface response method was used to optimize the extraction of the enzyme from the bacterial cells resulting in approximately 3 fold increase in hydrogenase activity. Maximum hydrogenase activity was found to occur after six days in the absence of dyes but was found to occur after one day in the presence of azo dyes. A decline in hydrogenase activity thereafter, suggested inhibition of enzymatic activity by the putative aromatic amines produced after azo cleavage. Purification of the hydrogenase by freeze drying, poly ethylene glycol, and Sephacryl – 200 size exclusion- ion exchange chromatography revealed the enzyme to have a molecular weight of 38.5 kDa when analyzed by a 12 % SDS-PAGE. Characterisation of the enzyme revealed optimal activity at a pH of 7.5 and temperature of 40 °C while it exhibited a poor thermal stability with a half-life of 32 minutes. The kinetic parameters V[subscript max] and K[subscript m] were 21.18 U ml[superscript -1} and 4.57 mM respectively. Application of the cell free extract on commercial dyes was not successful, and only whole SRB cells resulted in decolourisation of the dyes. Consequently trials on the industrial dyes and effluents were carried out with whole cells. Decolourisation rates of up to 96 % were achieved for the commercial dyes and up to 93 % for the industrial dyes over a period of 10 days.
- Full Text:
- Date Issued: 2007
- Authors: Mutambanengwe, Cecil Clifford Zvandada
- Date: 2007
- Subjects: Bioremediation , Dyes and dyeing -- Waste disposal , Sulfur bacteria , Hydragenase , Factory and trade waste -- Purification , Textile waste
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3960 , http://hdl.handle.net/10962/d1004019 , Bioremediation , Dyes and dyeing -- Waste disposal , Sulfur bacteria , Hydragenase , Factory and trade waste -- Purification , Textile waste
- Description: The continuing industrial development has led to a corresponding increase in the amount of waste water generation leading to a consequential decline in levels and quality of the natural water in the ecosystem. Textile industries consume over 7 x 10[superscript 5] tons of dyes annually and use up to 1 litre of water per kg of dye processed and are third largest polluters in the world, the problem being aggravated by the inefficiencies of the dye houses. An abundance of physio-chemical methods are in use world wide, however, there is increasing concern as to their impact in effectively treating textile effluents as they introduce secondary pollutants during the ‘remediation’ process which are quite costly to run, maintain and clean up. Research on biological treatment has offered simple and cost effective ways of bioremediating textile effluents. While aerobic treatment of textile dyes and their effluents has been reported, its major draw back is commercial up-scaling and as such anaerobic systems have been investigated and shown to degrade azo dyes, which form the bulk of the dyes used world wide. However, the mechanisms involved in the bioremediation of these dyes are poorly understood. The aims of this study were to identify and investigate the role of enzymes produced by sulphate reducing bacteria (SRB) in bioremediating textile dye and their effluents. Sulphate reducing bacteria were used in this study because they are tolerant to harsh environmental conditions and inhibit the proliferance of pathogenic micro-organisms. The appearance of clear zones in agar plates containing azo dye concentrations ranging from 10 – 100 mgl[superscript -1] showed the ability of SRB to decolourize dyes under anaerobic conditions. Assays of enzymes previously reported to decolourise azo dyes were not successful, but led to the identification of hydrogenase enzyme being produced by SRB. The enzyme was found to be localised in the membrane and cytoplasm. A surface response method was used to optimize the extraction of the enzyme from the bacterial cells resulting in approximately 3 fold increase in hydrogenase activity. Maximum hydrogenase activity was found to occur after six days in the absence of dyes but was found to occur after one day in the presence of azo dyes. A decline in hydrogenase activity thereafter, suggested inhibition of enzymatic activity by the putative aromatic amines produced after azo cleavage. Purification of the hydrogenase by freeze drying, poly ethylene glycol, and Sephacryl – 200 size exclusion- ion exchange chromatography revealed the enzyme to have a molecular weight of 38.5 kDa when analyzed by a 12 % SDS-PAGE. Characterisation of the enzyme revealed optimal activity at a pH of 7.5 and temperature of 40 °C while it exhibited a poor thermal stability with a half-life of 32 minutes. The kinetic parameters V[subscript max] and K[subscript m] were 21.18 U ml[superscript -1} and 4.57 mM respectively. Application of the cell free extract on commercial dyes was not successful, and only whole SRB cells resulted in decolourisation of the dyes. Consequently trials on the industrial dyes and effluents were carried out with whole cells. Decolourisation rates of up to 96 % were achieved for the commercial dyes and up to 93 % for the industrial dyes over a period of 10 days.
- Full Text:
- Date Issued: 2007
The bioaccumulation of platinum (IV) from aqueous solution using sulphate reducing bacteria: role of a hydrogenase enzyme
- Authors: Rashamuse, Konanani Justice
- Date: 2003
- Subjects: Sulfur bacteria , Bioremediation , Enzymes -- Metabolism , Platinum , Platinum compounds , Reduction (Chemistry) , Hydrogenation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4003 , http://hdl.handle.net/10962/d1004063 , Sulfur bacteria , Bioremediation , Enzymes -- Metabolism , Platinum , Platinum compounds , Reduction (Chemistry) , Hydrogenation
- Description: The enzymatic reduction of a high-valence form of metals to a low-valence reduced form has been proposed as a strategy to treat water contaminated with a range of metals and radionuclides. Metal reduction by sulphate reducing bacteria (SRB) is carried out either chemically (involving reduction by hydrogen sulphide) or enzymatically (involving redox enzymes such as the hydrogenases). While reduction of metal ions by hydrogen sulphide is well known, the enzymatic mechanism for metal reduction is poorly understood. The aims of this study were to investigate the role of SRB in facilitating platinum removal, and to investigate the role of a hydrogenase in platinum reduction in vitro. In order to avoid precipitation of platinum as platinum sulphide, a resting (non-growing) mixed SRB culture was used. The maximum initial concentration of platinum (IV), which SRB can effectively remove from solution was shown to be 50 mg.l⁻¹. Electron donor studies showed high platinum (IV) uptake in the presence of hydrogen, suggesting that platinum (IV) uptake from solution by SRB requires careful optimization with respect to the correct electron donor. Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis indicated that platinum was being precipitated in the periplasm, a major area of hydrogenase activity in SRB. Purification of the hydrogenase by ammonium sulphate precipitation (65%), Toyopearl-Super Q 650S ion exchange and Sephacry 1 S-100 size exclusion chromatography revealed that the hydrogenase was monomeric with a molecular weight of 58 KDa, when analyzed by 12% SDS-PAGE. The purified hydrogenase showed optimal temperature and pH at 35°C and 7.5 respectively, and a poor thermal stability. In vitro investigation of platinum reduction by purified hydrogenase from mixed SRB culture showed that hydrogenase reduces platinum only in the presence of hydrogen. Major platinum (IV) reduction was observed when hydrogenase was incubated with cytochrome C₃ (physiological electron carrier in vivo) under hydrogen. The same observations were also noted with industrial effluent. Collectively these findings suggest that in vitro platinum reduction is mediated by hydrogenase with a concerted action of cytochrome C₃ required to shuttle the electron from hydrogenase.
- Full Text:
- Date Issued: 2003
- Authors: Rashamuse, Konanani Justice
- Date: 2003
- Subjects: Sulfur bacteria , Bioremediation , Enzymes -- Metabolism , Platinum , Platinum compounds , Reduction (Chemistry) , Hydrogenation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4003 , http://hdl.handle.net/10962/d1004063 , Sulfur bacteria , Bioremediation , Enzymes -- Metabolism , Platinum , Platinum compounds , Reduction (Chemistry) , Hydrogenation
- Description: The enzymatic reduction of a high-valence form of metals to a low-valence reduced form has been proposed as a strategy to treat water contaminated with a range of metals and radionuclides. Metal reduction by sulphate reducing bacteria (SRB) is carried out either chemically (involving reduction by hydrogen sulphide) or enzymatically (involving redox enzymes such as the hydrogenases). While reduction of metal ions by hydrogen sulphide is well known, the enzymatic mechanism for metal reduction is poorly understood. The aims of this study were to investigate the role of SRB in facilitating platinum removal, and to investigate the role of a hydrogenase in platinum reduction in vitro. In order to avoid precipitation of platinum as platinum sulphide, a resting (non-growing) mixed SRB culture was used. The maximum initial concentration of platinum (IV), which SRB can effectively remove from solution was shown to be 50 mg.l⁻¹. Electron donor studies showed high platinum (IV) uptake in the presence of hydrogen, suggesting that platinum (IV) uptake from solution by SRB requires careful optimization with respect to the correct electron donor. Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis indicated that platinum was being precipitated in the periplasm, a major area of hydrogenase activity in SRB. Purification of the hydrogenase by ammonium sulphate precipitation (65%), Toyopearl-Super Q 650S ion exchange and Sephacry 1 S-100 size exclusion chromatography revealed that the hydrogenase was monomeric with a molecular weight of 58 KDa, when analyzed by 12% SDS-PAGE. The purified hydrogenase showed optimal temperature and pH at 35°C and 7.5 respectively, and a poor thermal stability. In vitro investigation of platinum reduction by purified hydrogenase from mixed SRB culture showed that hydrogenase reduces platinum only in the presence of hydrogen. Major platinum (IV) reduction was observed when hydrogenase was incubated with cytochrome C₃ (physiological electron carrier in vivo) under hydrogen. The same observations were also noted with industrial effluent. Collectively these findings suggest that in vitro platinum reduction is mediated by hydrogenase with a concerted action of cytochrome C₃ required to shuttle the electron from hydrogenase.
- Full Text:
- Date Issued: 2003
Spirulina as a bioremediation agent : interaction with metals and involvement of carbonic anhydrase
- Authors: Payne, Rosemary Anne
- Date: 2000
- Subjects: Spirulina , Bioremediation , Carbonic anhydrase
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3909 , http://hdl.handle.net/10962/d1003968 , Spirulina , Bioremediation , Carbonic anhydrase
- Description: Heavy metal contamination from mining and other industrial operations is becoming an increasing problem with regards to the depleting water resources in South Africa. This study involved the investigation of the use of an algal biomass as a possible alternative to the traditional chemical means of removing these metals. When the toxic effects of metals were investigated, Spirulina was found to have a threshold level of about 30 μM for copper, zinc and lead. Copper and zinc appeared to have a direct effect on the photosynthetic pathway, thereby causing a rapid decline in cell growth. Lead on the other hand seemed to affect surface properties and hence took longer to cause deterioration in growth. Although relatively low concentrations of metal may have a toxic effect on the cyanobacterium, Spirulina may have potential as a precipitation agent. The role of Spirulina in the precipitation of heavy metals appears to be through its ability to maintain a high pH in the surrounding medium, possibly through the enzyme carbonic anhydrase. Subsequent studies therefore focused on the assay and isolation of this enzyme. Two different radiotracer assays, in which carbonic anhydrase converts radiolabelled bicarbonate to carbon dioxide, were investigated, but were found to have several problems. Results were insensitive and could not be reproduced. The standard Wilbur-Anderson method subsequently investigated also proved to be insensitive with a tremendous degree of variability. Although not quantitative, SDS-PAGE proved to be the most reliable method of detection, and was therefore used in subsequent procedures. Chlamydomonas reinhardtii was the subject of initial enzyme isolation studies as these procedures are well documented. Although the published protocols proved unsuccessful, affinity chromatography of a membrane stock solution from Chlamydomonas reinhardtii yielded two relatively pure protein bands. These bands were presumed to represent two subunits of carbonic anhydrase, although Western blot analysis would be required to confirm their identity. Purification of carbonic anhydrase from Spirulina, however, proved unsuccessful and results obtained were very inconclusive. Hence, further analysis of Spirulina is required. The possibility of cloning CA from a genomic library was also considered, but suitable primers could not be designed from the aligned sequences.
- Full Text:
- Date Issued: 2000
- Authors: Payne, Rosemary Anne
- Date: 2000
- Subjects: Spirulina , Bioremediation , Carbonic anhydrase
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3909 , http://hdl.handle.net/10962/d1003968 , Spirulina , Bioremediation , Carbonic anhydrase
- Description: Heavy metal contamination from mining and other industrial operations is becoming an increasing problem with regards to the depleting water resources in South Africa. This study involved the investigation of the use of an algal biomass as a possible alternative to the traditional chemical means of removing these metals. When the toxic effects of metals were investigated, Spirulina was found to have a threshold level of about 30 μM for copper, zinc and lead. Copper and zinc appeared to have a direct effect on the photosynthetic pathway, thereby causing a rapid decline in cell growth. Lead on the other hand seemed to affect surface properties and hence took longer to cause deterioration in growth. Although relatively low concentrations of metal may have a toxic effect on the cyanobacterium, Spirulina may have potential as a precipitation agent. The role of Spirulina in the precipitation of heavy metals appears to be through its ability to maintain a high pH in the surrounding medium, possibly through the enzyme carbonic anhydrase. Subsequent studies therefore focused on the assay and isolation of this enzyme. Two different radiotracer assays, in which carbonic anhydrase converts radiolabelled bicarbonate to carbon dioxide, were investigated, but were found to have several problems. Results were insensitive and could not be reproduced. The standard Wilbur-Anderson method subsequently investigated also proved to be insensitive with a tremendous degree of variability. Although not quantitative, SDS-PAGE proved to be the most reliable method of detection, and was therefore used in subsequent procedures. Chlamydomonas reinhardtii was the subject of initial enzyme isolation studies as these procedures are well documented. Although the published protocols proved unsuccessful, affinity chromatography of a membrane stock solution from Chlamydomonas reinhardtii yielded two relatively pure protein bands. These bands were presumed to represent two subunits of carbonic anhydrase, although Western blot analysis would be required to confirm their identity. Purification of carbonic anhydrase from Spirulina, however, proved unsuccessful and results obtained were very inconclusive. Hence, further analysis of Spirulina is required. The possibility of cloning CA from a genomic library was also considered, but suitable primers could not be designed from the aligned sequences.
- Full Text:
- Date Issued: 2000
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