Modelling of the performance of a batch biogas digester fed with selected types of substrates
- Authors: Mukumba, Patrick
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc (Physics)
- Identifier: vital:11596 , http://hdl.handle.net/10353/d1016197
- Description: The increasing population and the rapid economic growth in South Africa have led to higher consumption of food resulting in the generation of large amounts of waste. In addition, South Africa has plenty of biomass from cattle, donkeys, horses, goats, pigs, chicken and sheep. However, anaerobic digestion could be an alternative solution for the utilization of these kinds of waste due to its environmental and economic benefits. Therefore, the main focus of the research was design, construct a field batch biogas digester, monitor its performance when fed with co-substrates and model the methane yield for an optimized mixing ratio.
- Full Text:
- Date Issued: 2013
- Authors: Mukumba, Patrick
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc (Physics)
- Identifier: vital:11596 , http://hdl.handle.net/10353/d1016197
- Description: The increasing population and the rapid economic growth in South Africa have led to higher consumption of food resulting in the generation of large amounts of waste. In addition, South Africa has plenty of biomass from cattle, donkeys, horses, goats, pigs, chicken and sheep. However, anaerobic digestion could be an alternative solution for the utilization of these kinds of waste due to its environmental and economic benefits. Therefore, the main focus of the research was design, construct a field batch biogas digester, monitor its performance when fed with co-substrates and model the methane yield for an optimized mixing ratio.
- Full Text:
- Date Issued: 2013
Anaerobic digestion of fungally pre-treated wine distillery wastewater
- Melamane, Xolisa L, Tandlich, Roman, Burgess, Jo E
- Authors: Melamane, Xolisa L , Tandlich, Roman , Burgess, Jo E
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71740 , vital:29932 , https://doi.org/10.5897/AJB2007.000-2305
- Description: The combination of fungal pre-treatment with Trametes pubescens and anaerobic digestion were tested for the removal of chemical oxygen demand (COD) and phenolic compounds from wine distillery wastewater. The COD removal efficiency after fungal pre-treatment reached 53.3%. During digestion, pH buffering was achieved using CaCO3 and K2HPO4. This provided a stable environment inside digester for efficient and time-independent COD removal. The total COD removal efficiency reached 99.5%, and the system proved able to eliminate shock COD loads, as indicated by the concentrations of sludge and volatile fatty acids. Complex changes of phenolic compounds are suspected in anaerobic digestion system, and are investigated further.
- Full Text:
- Date Issued: 2007
- Authors: Melamane, Xolisa L , Tandlich, Roman , Burgess, Jo E
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71740 , vital:29932 , https://doi.org/10.5897/AJB2007.000-2305
- Description: The combination of fungal pre-treatment with Trametes pubescens and anaerobic digestion were tested for the removal of chemical oxygen demand (COD) and phenolic compounds from wine distillery wastewater. The COD removal efficiency after fungal pre-treatment reached 53.3%. During digestion, pH buffering was achieved using CaCO3 and K2HPO4. This provided a stable environment inside digester for efficient and time-independent COD removal. The total COD removal efficiency reached 99.5%, and the system proved able to eliminate shock COD loads, as indicated by the concentrations of sludge and volatile fatty acids. Complex changes of phenolic compounds are suspected in anaerobic digestion system, and are investigated further.
- Full Text:
- Date Issued: 2007
Physiology of Digestion and Ruminology and Energy and Protein Metabolism: AGA 605
- Muchenje, V, Nkukwana, T T, Chimonyo, M, van de Vyver, F
- Authors: Muchenje, V , Nkukwana, T T , Chimonyo, M , van de Vyver, F
- Date: 2011-02
- Subjects: Ruminants -- Digestive organs
- Language: English
- Type: Examination paper
- Identifier: vital:17526 , http://hdl.handle.net/10353/d1009808
- Description: Physiology of Digestion and Ruminology and Energy and Protein Metabolism: AGA 605, supplementary examination February 2011.
- Full Text: false
- Date Issued: 2011-02
- Authors: Muchenje, V , Nkukwana, T T , Chimonyo, M , van de Vyver, F
- Date: 2011-02
- Subjects: Ruminants -- Digestive organs
- Language: English
- Type: Examination paper
- Identifier: vital:17526 , http://hdl.handle.net/10353/d1009808
- Description: Physiology of Digestion and Ruminology and Energy and Protein Metabolism: AGA 605, supplementary examination February 2011.
- Full Text: false
- Date Issued: 2011-02
Physiology of Digestion and Ruminology and Energy and Protein Metabolism: AGA 605
- Muchenje, V, Nkukwana, T T, Chimonyo, Van de Vyver, F
- Authors: Muchenje, V , Nkukwana, T T , Chimonyo , Van de Vyver, F
- Date: 2011-02
- Subjects: Ruminants -- Metabolism
- Language: English
- Type: Examination paper
- Identifier: vital:17525 , http://hdl.handle.net/10353/d1009807
- Description: Physiology of Digestion and Ruminology and Energy and Protein Metabolism: AGA 605, supplementary examination February 2010.
- Full Text: false
- Date Issued: 2011-02
- Authors: Muchenje, V , Nkukwana, T T , Chimonyo , Van de Vyver, F
- Date: 2011-02
- Subjects: Ruminants -- Metabolism
- Language: English
- Type: Examination paper
- Identifier: vital:17525 , http://hdl.handle.net/10353/d1009807
- Description: Physiology of Digestion and Ruminology and Energy and Protein Metabolism: AGA 605, supplementary examination February 2010.
- Full Text: false
- Date Issued: 2011-02
Physiology of Digestion and Ruminology and Energy and Protein Metabolism: AGA 605
- Chimonyo, M, Van de Vyver, F
- Authors: Chimonyo, M , Van de Vyver, F
- Date: 2010-01
- Subjects: Ruminants -- Metabolism
- Language: English
- Type: Examination paper
- Identifier: vital:17529 , http://hdl.handle.net/10353/d1009819
- Description: Physiology of Digestion and Ruminology and Energy and Protein Metabolism: AGA 605, supplementary examination January 2010.
- Full Text: false
- Date Issued: 2010-01
- Authors: Chimonyo, M , Van de Vyver, F
- Date: 2010-01
- Subjects: Ruminants -- Metabolism
- Language: English
- Type: Examination paper
- Identifier: vital:17529 , http://hdl.handle.net/10353/d1009819
- Description: Physiology of Digestion and Ruminology and Energy and Protein Metabolism: AGA 605, supplementary examination January 2010.
- Full Text: false
- Date Issued: 2010-01
Investigation and laboratory tests of sub-economic aluminium resources in China
- Authors: Hu, Sichun
- Date: 2011
- Subjects: Aluminum -- China , Bauxite -- China , Iron -- China , Sulfur -- China , Fertilizers -- China
- Language: English
- Type: Thesis , Doctoral , PhD (Geology)
- Identifier: vital:11520 , http://hdl.handle.net/10353/436 , Aluminum -- China , Bauxite -- China , Iron -- China , Sulfur -- China , Fertilizers -- China
- Description: China, the largest aluminium producer, is seriously lacking of reserves at the present and in the future. However, there are a huge amount of sub-economic aluminium resources (high iron diasporic, low A/S and high iron gibbsite and high sulfur diasporic bauxite), and potassic sandy shale suitable for the extraction of aluminium and the production of potassium and silicon fertilizers if proper metallurgical processes are developed. This study aims to investigate the sub-economic aluminium resources through investigation and identify the right technologies through laboratory tests for metal extraction and utilization of the by-products of K-feldspar sandy shale. The investigation of the sub-economic aluminium resources includes field and site visits and data collection and collation. A series of laboratory scale tests were carried out for different types of bauxite and potassic sandy shale, which includes initial try tests and formal laboratory experiments for optimization of the processes and procedures, and crop planting tests for use of potassium and silicon fertilizers. The successful laboratory tests (technologies) in this study were optimized and proved to be effective. The results showed: 1) Medium temperature metallization roasting and then magnetic separation, and gas reduction metallization roasting and then magnetic separation are effective for processing of the high iron diasporic bauxite; 2) Dry magnetic separation, wet magnetic separation and medium temperature magnetization roasting and then magnetic separation are not effective for processing of the high iron diasporic bauxite; 3) Digestion at atmospheric conditions and high caustic alkali concentration is effective for processing of low A/S and high iron gibbsite bauxite; 4) Desulfurization flotation and desulfurization with barium aluminate are both effective for processing of the high sulfur bauxite. However, each of these methods have their own advantages and disadvantages and must be evaluated; and 5) The soda-lime sintering process is suitable for processing of the Linzhou potassic sandy shale. The aluminium and potassium are extracted and the silicon residues can be used for silicon fertilizer. The results of this study help solve the problem of aluminium reserve shortage. They also open a new way for integrated utilization of other aluminium resources including potassic sandy shale.
- Full Text:
- Date Issued: 2011
- Authors: Hu, Sichun
- Date: 2011
- Subjects: Aluminum -- China , Bauxite -- China , Iron -- China , Sulfur -- China , Fertilizers -- China
- Language: English
- Type: Thesis , Doctoral , PhD (Geology)
- Identifier: vital:11520 , http://hdl.handle.net/10353/436 , Aluminum -- China , Bauxite -- China , Iron -- China , Sulfur -- China , Fertilizers -- China
- Description: China, the largest aluminium producer, is seriously lacking of reserves at the present and in the future. However, there are a huge amount of sub-economic aluminium resources (high iron diasporic, low A/S and high iron gibbsite and high sulfur diasporic bauxite), and potassic sandy shale suitable for the extraction of aluminium and the production of potassium and silicon fertilizers if proper metallurgical processes are developed. This study aims to investigate the sub-economic aluminium resources through investigation and identify the right technologies through laboratory tests for metal extraction and utilization of the by-products of K-feldspar sandy shale. The investigation of the sub-economic aluminium resources includes field and site visits and data collection and collation. A series of laboratory scale tests were carried out for different types of bauxite and potassic sandy shale, which includes initial try tests and formal laboratory experiments for optimization of the processes and procedures, and crop planting tests for use of potassium and silicon fertilizers. The successful laboratory tests (technologies) in this study were optimized and proved to be effective. The results showed: 1) Medium temperature metallization roasting and then magnetic separation, and gas reduction metallization roasting and then magnetic separation are effective for processing of the high iron diasporic bauxite; 2) Dry magnetic separation, wet magnetic separation and medium temperature magnetization roasting and then magnetic separation are not effective for processing of the high iron diasporic bauxite; 3) Digestion at atmospheric conditions and high caustic alkali concentration is effective for processing of low A/S and high iron gibbsite bauxite; 4) Desulfurization flotation and desulfurization with barium aluminate are both effective for processing of the high sulfur bauxite. However, each of these methods have their own advantages and disadvantages and must be evaluated; and 5) The soda-lime sintering process is suitable for processing of the Linzhou potassic sandy shale. The aluminium and potassium are extracted and the silicon residues can be used for silicon fertilizer. The results of this study help solve the problem of aluminium reserve shortage. They also open a new way for integrated utilization of other aluminium resources including potassic sandy shale.
- Full Text:
- Date Issued: 2011
Interpretation of regional geochemical data as an aid to exploration target generation in the North West Province South Africa
- Authors: Mapukule, Livhuwani Ernest
- Date: 2009
- Subjects: Ore deposits -- South Africa , Prospecting -- South Africa , Mines and mineral resources -- South Africa
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: vital:11519 , http://hdl.handle.net/10353/268 , Ore deposits -- South Africa , Prospecting -- South Africa , Mines and mineral resources -- South Africa
- Description: This study involves the application, interpretation and utilization of regional geochemical data for target generation in the North West Province, South Africa. A regional soil geochemical survey programme has been carried out by the Council of Geoscience South Africa since 1973. A number of 1:250 000 sheet areas have been completed, but there are no interpretative maps which could aid in mineral exploration and other purposes. In order to utilize the valuable and expensive data, the project was motivated through data acquisition and interpretation to generate exploration targets. The study area is confined to Mafikeng, Vryburg, Kuruman and Christiana in the Northwest Province, where potential exploration and mining opportunities exist in areas of great geological interest. These include geological events such as the Bushveld Complex, the Kalahari manganese field and the Kraaipan greenstone belts. The aim of this project was to utilize geochemical data together with geophysical and geological information to verify and identification of possible obscured ore bodies or zones of mineralization, and to generate targets. Another objective was the author to be trained in the techniques of geochemical data processing, interpretation and integration of techniques such as geophysics, in the understanding of the geology and economic geology of the areas. Approximately 5 kg of surface soil was collected per 1 km2 by CGS from foot traversing. Pellets of the samples were prepared and analyzed for TiO2, MnO and Fe2O3, Sc, V, Cr, Ni, Co, Cu, Zn, As, Y, Ba, Nb, Rb, Th, W, Zr, Pb, Sr and U using the simultaneous wavelengthdispersive X-ray fluorescence spectrometer technique at the Council for Geoscience, South Africa. For each element the mean +2 standard deviations were used as a threshold value to separate the negative from the positive anomalies. The integration of geological, geophysical and geochemical information was used to analyze and understand the areas of interest. A number of computer programmes were extensively used for data processing, manipulation, and presentation. These include Golden Software Surfer 8®, Arc-View 3.2a®, TNT-Mips®, JMP 8 ®, and Microsoft Excel®. Through geochemical data processing and interpretation, together with the low resolution aeromagnetic data, gravity data and geological data, seven (7) exploration target areas have been generated: These have been numbered A to G. It is concluded that there is good potential for Cr, PGMs, vanadium, nickel, iron, copper, manganese, uranium and niobium in the targets generated. The results provide some indication and guide for exploration in the target areas. In Target A, Cu, Cr, Fe, Ni and V anomalies from the lower chromitite zone of far western zone of the Bushveld Complex, which has be overlain buy the thick surface sand of the Gordonia Formation. Target B occurs over the diabase, norite, andesitic lava and andalusite muscovite hornfels of the Magaliesberg Formation. This target has the potential for Cu, Fe and Ni mineralization. The felsic rocks of the Kanye Formation and the Gaborone Granite in target C have shown some positive anomalies of niobium, uranium, yttrium and rubidium which give the area potential for Nb, REE and U exploration. Target D is located on the Allanridge Formation, and has significant potential for Ni-Cu mineralization, and is associated with the komatiitic lava at the base of the Allanridge Formation in the Christiana Area. The light green tholeiitic, calc-alkali basalt and andesitic rocks of the Rietgat Formation are characterized by a north-south trending yttrium anomaly with supporting Ba and Y anomalies (Target E). This makes the area a potential target for rare earth elements. Calcrete on the west of the Kuruman has a low b potential target for vanadium. It is believed that the area might be potential for potassium-uranium vanadate minerals, carnotite which is mostly found in calcrete deposits. This study has proved to be a useful and approach in utilizing the valuable geochemical data for exploration and future mining, generated by Council for Geoscience Science. It is recommended that further detailed soil, rock and geochemical surveys and ultimately diamond drilling be carried out in the exploration target areas generated by this study.
- Full Text:
- Date Issued: 2009
- Authors: Mapukule, Livhuwani Ernest
- Date: 2009
- Subjects: Ore deposits -- South Africa , Prospecting -- South Africa , Mines and mineral resources -- South Africa
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: vital:11519 , http://hdl.handle.net/10353/268 , Ore deposits -- South Africa , Prospecting -- South Africa , Mines and mineral resources -- South Africa
- Description: This study involves the application, interpretation and utilization of regional geochemical data for target generation in the North West Province, South Africa. A regional soil geochemical survey programme has been carried out by the Council of Geoscience South Africa since 1973. A number of 1:250 000 sheet areas have been completed, but there are no interpretative maps which could aid in mineral exploration and other purposes. In order to utilize the valuable and expensive data, the project was motivated through data acquisition and interpretation to generate exploration targets. The study area is confined to Mafikeng, Vryburg, Kuruman and Christiana in the Northwest Province, where potential exploration and mining opportunities exist in areas of great geological interest. These include geological events such as the Bushveld Complex, the Kalahari manganese field and the Kraaipan greenstone belts. The aim of this project was to utilize geochemical data together with geophysical and geological information to verify and identification of possible obscured ore bodies or zones of mineralization, and to generate targets. Another objective was the author to be trained in the techniques of geochemical data processing, interpretation and integration of techniques such as geophysics, in the understanding of the geology and economic geology of the areas. Approximately 5 kg of surface soil was collected per 1 km2 by CGS from foot traversing. Pellets of the samples were prepared and analyzed for TiO2, MnO and Fe2O3, Sc, V, Cr, Ni, Co, Cu, Zn, As, Y, Ba, Nb, Rb, Th, W, Zr, Pb, Sr and U using the simultaneous wavelengthdispersive X-ray fluorescence spectrometer technique at the Council for Geoscience, South Africa. For each element the mean +2 standard deviations were used as a threshold value to separate the negative from the positive anomalies. The integration of geological, geophysical and geochemical information was used to analyze and understand the areas of interest. A number of computer programmes were extensively used for data processing, manipulation, and presentation. These include Golden Software Surfer 8®, Arc-View 3.2a®, TNT-Mips®, JMP 8 ®, and Microsoft Excel®. Through geochemical data processing and interpretation, together with the low resolution aeromagnetic data, gravity data and geological data, seven (7) exploration target areas have been generated: These have been numbered A to G. It is concluded that there is good potential for Cr, PGMs, vanadium, nickel, iron, copper, manganese, uranium and niobium in the targets generated. The results provide some indication and guide for exploration in the target areas. In Target A, Cu, Cr, Fe, Ni and V anomalies from the lower chromitite zone of far western zone of the Bushveld Complex, which has be overlain buy the thick surface sand of the Gordonia Formation. Target B occurs over the diabase, norite, andesitic lava and andalusite muscovite hornfels of the Magaliesberg Formation. This target has the potential for Cu, Fe and Ni mineralization. The felsic rocks of the Kanye Formation and the Gaborone Granite in target C have shown some positive anomalies of niobium, uranium, yttrium and rubidium which give the area potential for Nb, REE and U exploration. Target D is located on the Allanridge Formation, and has significant potential for Ni-Cu mineralization, and is associated with the komatiitic lava at the base of the Allanridge Formation in the Christiana Area. The light green tholeiitic, calc-alkali basalt and andesitic rocks of the Rietgat Formation are characterized by a north-south trending yttrium anomaly with supporting Ba and Y anomalies (Target E). This makes the area a potential target for rare earth elements. Calcrete on the west of the Kuruman has a low b potential target for vanadium. It is believed that the area might be potential for potassium-uranium vanadate minerals, carnotite which is mostly found in calcrete deposits. This study has proved to be a useful and approach in utilizing the valuable geochemical data for exploration and future mining, generated by Council for Geoscience Science. It is recommended that further detailed soil, rock and geochemical surveys and ultimately diamond drilling be carried out in the exploration target areas generated by this study.
- Full Text:
- Date Issued: 2009
Extracellular digestion in two intertidal mussels and the role played by their gut bacteria
- Authors: Simon, Carol Anne
- Date: 1997
- Subjects: Perna -- Digestive organs , Mussels -- Digestive organs , Spirochaeta
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5692 , http://hdl.handle.net/10962/d1005378 , Perna -- Digestive organs , Mussels -- Digestive organs , Spirochaeta
- Description: The intertidal mussels. Perna perna and Choromytilus meridionalis co-occur on the southern coast of South Africa. Mussels ingest mixtures of bacteria. phytoplankton. zooplankton and detritus. with proportions varying according to availability. These bivalves filter similar-sized particles. which might result in interspecific competition. Carbohydrate-digesting enzymes of the mussels and their enteric bacteria. and bacteriolytic enzymes of the mussels were therefore examined to elucidate feeding ecology in these animals at an enzymatic level. Style enzymes of both species digested the storage carbohydrates amylose glycogen and laminarin, and the structural carbohydrate carboxymethyl cellulose (CMC). Differential rates of digestion of these carbohydrates suggests that Perna perna relies more on plankton (and possibly bacteria) than on detritus for food while Choromytilus meridionalis relies equally on all components of the seston. There may therefore be some degree of resource partitioning of the seston. The styles of P.perna had a lower specific enzyme activity. but higher protein content than those of C.meridionalis. P.perna could therefore release more glucose from a given concentration of substrate than C.meridionalis. The gut contents and tissue were examined microscopically to determine where the bacterial colonisation sites were. Bacteria were associated primarily with the gut contents but not the gut walls. of both species. The styles housed spirochaete bacteria (Crislispira sp), Perna perna housed large numbers of one species. while Choromytilus meridionalis had lower numbers of two species. Levels of infection differed between species and localities. Enteric (but not style) bacteria of Perna perna and Choromytilus meridionalis always digested the same carbohydrates as the mussels as well as the structural carbohydrates mannan and fucoidan. Activity was erratic on the structural compounds, carageenin and xylan, and absent on alginic acid or inulin. Activity on the storage carbohydrates by enteric bacteria from C.meridionalis was higher than by those from P.perna. This is probably related to the larger bacterial populations housed by C.meridionalis than by P.perna. Bacteriolytic activity by the digestive enzymes of Pema perna was higher than for Choromytilus. In P.perna it was due to a combination of different enzymes one of which is a true lysozyme. C.meridionalis did not produce a true lysozyme. Enzymes produced by the mussels and their enteric bacteria allow the mussels to utilise all components of the seston. Low endogenous enzyme activity by Choromytilus meridionalis, coupled with the high activity by its enteric bacteria, suggests that they rely more on bacterial activity to meet their dietary requirements than does Perna perna. The ability of enteric bacteria to digest carbohydrates which the mussels cannot indicates that the bacteria are endosymbiotic, although the sporadic nature of activity of some of the enzymes, and the fact that bacteria are associated with the gut contents, indicates that the relationship is only incidental.
- Full Text:
- Date Issued: 1997
- Authors: Simon, Carol Anne
- Date: 1997
- Subjects: Perna -- Digestive organs , Mussels -- Digestive organs , Spirochaeta
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5692 , http://hdl.handle.net/10962/d1005378 , Perna -- Digestive organs , Mussels -- Digestive organs , Spirochaeta
- Description: The intertidal mussels. Perna perna and Choromytilus meridionalis co-occur on the southern coast of South Africa. Mussels ingest mixtures of bacteria. phytoplankton. zooplankton and detritus. with proportions varying according to availability. These bivalves filter similar-sized particles. which might result in interspecific competition. Carbohydrate-digesting enzymes of the mussels and their enteric bacteria. and bacteriolytic enzymes of the mussels were therefore examined to elucidate feeding ecology in these animals at an enzymatic level. Style enzymes of both species digested the storage carbohydrates amylose glycogen and laminarin, and the structural carbohydrate carboxymethyl cellulose (CMC). Differential rates of digestion of these carbohydrates suggests that Perna perna relies more on plankton (and possibly bacteria) than on detritus for food while Choromytilus meridionalis relies equally on all components of the seston. There may therefore be some degree of resource partitioning of the seston. The styles of P.perna had a lower specific enzyme activity. but higher protein content than those of C.meridionalis. P.perna could therefore release more glucose from a given concentration of substrate than C.meridionalis. The gut contents and tissue were examined microscopically to determine where the bacterial colonisation sites were. Bacteria were associated primarily with the gut contents but not the gut walls. of both species. The styles housed spirochaete bacteria (Crislispira sp), Perna perna housed large numbers of one species. while Choromytilus meridionalis had lower numbers of two species. Levels of infection differed between species and localities. Enteric (but not style) bacteria of Perna perna and Choromytilus meridionalis always digested the same carbohydrates as the mussels as well as the structural carbohydrates mannan and fucoidan. Activity was erratic on the structural compounds, carageenin and xylan, and absent on alginic acid or inulin. Activity on the storage carbohydrates by enteric bacteria from C.meridionalis was higher than by those from P.perna. This is probably related to the larger bacterial populations housed by C.meridionalis than by P.perna. Bacteriolytic activity by the digestive enzymes of Pema perna was higher than for Choromytilus. In P.perna it was due to a combination of different enzymes one of which is a true lysozyme. C.meridionalis did not produce a true lysozyme. Enzymes produced by the mussels and their enteric bacteria allow the mussels to utilise all components of the seston. Low endogenous enzyme activity by Choromytilus meridionalis, coupled with the high activity by its enteric bacteria, suggests that they rely more on bacterial activity to meet their dietary requirements than does Perna perna. The ability of enteric bacteria to digest carbohydrates which the mussels cannot indicates that the bacteria are endosymbiotic, although the sporadic nature of activity of some of the enzymes, and the fact that bacteria are associated with the gut contents, indicates that the relationship is only incidental.
- Full Text:
- Date Issued: 1997
Towards the development of a larval feeding strategy for the white-margined sole (Dagetichthys marginatus)
- Authors: Thompson, Ernst Frederick
- Date: 2014
- Subjects: Flatfishes -- South Africa , Soleidae -- South Africa , Soleidae -- Larvae , Soleidae -- Larvae -- Feeding and feeds , Soleidae -- Larvae -- Physiology , Artemia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5364 , http://hdl.handle.net/10962/d1012982
- Description: The major bottleneck during the domestication of the white-margined sole Dagetichthys marginatus in South Africa has been low larval survival. The cause of this is not clear but considering current literature on flatfish culture and more specifically soleid culture, nutritional deficiencies are hypothesized to be the main possible cause. Following the importance of nutrition, the first aim of the research was to use an ontogenetic developmental approach to develop a species specific larval feeding strategy. Ontogenetic development of D. marginatus showed that weaning will take place at much later ages than other soleids currently being farmed. This makes the partial replacement of Artemia with a suitable inert diet in co-feeding strategies very important to cut the cost associated of live food production. This leads on to the second aim, in which an 'in vitro' approach was used to model the digestibility of Artemia, which could ultimately contribute towards designing inert feeds with similar digestibility characteristics to Artemia in the future. Obtaining nutrients from food is closely linked to the functional status of the digestive tract, the support organs and the external morphological characteristics required for the ingestion of live or inert feeds. Considering both morphological and physiological ontogenetic development, it is clear that D. marginatus follow a similar pattern to other soleids. Larvae can successfully feed on Artemia as early as 3 days after hatching but exhibit a slow metamorphosis into the juvenile stage when compared to other soleids. The absence of any detectable acidic protease activity during the first 45 days of development and the importance of exogenous enzymes from Artemia all points to limited capacity to digest artificial diets. Prior to modelling the 'in vitro' digestion of Artemia, digestive enzyme activity at different pH's were modelled using functional forms from the normal distributive category of functions. , As there is no substantiated information for the general effects of pH on enzyme activity in the literature for finfish larvae, three species occurring in the same bio-geographical region of Dagetichthys marginatus, namely Sarpa salpa, Diplodus sargus capensis and Argyrosomus japonicus were used to investigate this effect. The fitted parameters, namely the optimal pH and sigma (the slope around the optimal pH) showed two interesting results. When using a negative log likelihood ratio test to test for differences between species for a particular enzyme, the optimal pH for alkaline proteases (7.67), lipase (8.03), amylase (7.69) and phosphatase (9.84) activity was the same for all three species. Furthermore, the study illustrated the potential to detect dietary shifts during ontogenetic development based on changes in enzyme activity around the optimal pH using the sigma parameter. Sarpa salpa showed increased amylase activity and a decrease in protease activity around the optimal pH with increased size, corresponding to a change in diet from zooplankton to algae. The 'in vitro' modelling approach taken in this study was based on known enzyme interactions and dynamics which makes the results very interpretable. from Artemia is achieved based on gut evacuation time and enzyme levels. This 'in vitro' study furthermore clearly indicates the importance of exogenous enzymes from Artemia, contributing as much as 54 percent to protein digestion and 64 – 72 percent to carbohydrate digestion. This was however, only an initial investigation, and further expansion of the model is required to achieve a complete understanding of Artemia digestion and ultimately partial replacement with artificial diets. A feeding strategy for D. marginatus should therefore follow those of other farmed soleids, although there will be a general delay in implementation due to slower development. Problems can thus be solved and improvements made by transferring technology from other soleids to D. marginatus.
- Full Text:
- Date Issued: 2014
- Authors: Thompson, Ernst Frederick
- Date: 2014
- Subjects: Flatfishes -- South Africa , Soleidae -- South Africa , Soleidae -- Larvae , Soleidae -- Larvae -- Feeding and feeds , Soleidae -- Larvae -- Physiology , Artemia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5364 , http://hdl.handle.net/10962/d1012982
- Description: The major bottleneck during the domestication of the white-margined sole Dagetichthys marginatus in South Africa has been low larval survival. The cause of this is not clear but considering current literature on flatfish culture and more specifically soleid culture, nutritional deficiencies are hypothesized to be the main possible cause. Following the importance of nutrition, the first aim of the research was to use an ontogenetic developmental approach to develop a species specific larval feeding strategy. Ontogenetic development of D. marginatus showed that weaning will take place at much later ages than other soleids currently being farmed. This makes the partial replacement of Artemia with a suitable inert diet in co-feeding strategies very important to cut the cost associated of live food production. This leads on to the second aim, in which an 'in vitro' approach was used to model the digestibility of Artemia, which could ultimately contribute towards designing inert feeds with similar digestibility characteristics to Artemia in the future. Obtaining nutrients from food is closely linked to the functional status of the digestive tract, the support organs and the external morphological characteristics required for the ingestion of live or inert feeds. Considering both morphological and physiological ontogenetic development, it is clear that D. marginatus follow a similar pattern to other soleids. Larvae can successfully feed on Artemia as early as 3 days after hatching but exhibit a slow metamorphosis into the juvenile stage when compared to other soleids. The absence of any detectable acidic protease activity during the first 45 days of development and the importance of exogenous enzymes from Artemia all points to limited capacity to digest artificial diets. Prior to modelling the 'in vitro' digestion of Artemia, digestive enzyme activity at different pH's were modelled using functional forms from the normal distributive category of functions. , As there is no substantiated information for the general effects of pH on enzyme activity in the literature for finfish larvae, three species occurring in the same bio-geographical region of Dagetichthys marginatus, namely Sarpa salpa, Diplodus sargus capensis and Argyrosomus japonicus were used to investigate this effect. The fitted parameters, namely the optimal pH and sigma (the slope around the optimal pH) showed two interesting results. When using a negative log likelihood ratio test to test for differences between species for a particular enzyme, the optimal pH for alkaline proteases (7.67), lipase (8.03), amylase (7.69) and phosphatase (9.84) activity was the same for all three species. Furthermore, the study illustrated the potential to detect dietary shifts during ontogenetic development based on changes in enzyme activity around the optimal pH using the sigma parameter. Sarpa salpa showed increased amylase activity and a decrease in protease activity around the optimal pH with increased size, corresponding to a change in diet from zooplankton to algae. The 'in vitro' modelling approach taken in this study was based on known enzyme interactions and dynamics which makes the results very interpretable. from Artemia is achieved based on gut evacuation time and enzyme levels. This 'in vitro' study furthermore clearly indicates the importance of exogenous enzymes from Artemia, contributing as much as 54 percent to protein digestion and 64 – 72 percent to carbohydrate digestion. This was however, only an initial investigation, and further expansion of the model is required to achieve a complete understanding of Artemia digestion and ultimately partial replacement with artificial diets. A feeding strategy for D. marginatus should therefore follow those of other farmed soleids, although there will be a general delay in implementation due to slower development. Problems can thus be solved and improvements made by transferring technology from other soleids to D. marginatus.
- Full Text:
- Date Issued: 2014
Pre-concentration of toxic metals using electrospun amino-functionalized nylon-6 nanofibre sorbent
- Darko, G, Sobola, A, Adewuyi, Sheriff, Okonkwo, J O, Torto, N
- Authors: Darko, G , Sobola, A , Adewuyi, Sheriff , Okonkwo, J O , Torto, N
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6571 , http://hdl.handle.net/10962/d1004134
- Description: This paper presents a new approach for pre-concentrating toxic metals (As, Cd, Ni and Pb) in aqueous environments using an amino-functionalized electrospun nanofibre sorbent. The sorbent, composed of nanofibres of average diameter 80 ± 10 nm and specific surface area of 58m2 g–1, exhibited fast adsorption kinetics (<20 min) for As, Cd, Ni and Pb. The optimalpHfor the uptake of As, Cd, Ni and Pb were 5.5, 6.0, 6.5 and 11, respectively. The adsorption process best fitted the Freundlich isothermand followed the first-order kinetics. The highest pre-concentration achieved using the sorbent was 41.99 (Ni in treated wastewater). The capacity of the sorbent to pre-concentrate the toxic metals was compared with those of aqua regia and HNO3+H2O2 digestions. The pre-concentration factors achieved for Cd in river water samples can be ranked as aqua regia digestion (0.73) > adsorption (0.34)>HNO3+H2O2 (0.23) digestion.Asimilar trend was observed for Ni in river water as well as Ni andCdin tap water samples. Pb ions in the river water samples were pre-concentrated slightly better using the two digestion methods pre-concentration factors ~22) compared to adsorption method (pre-concentration factor ~21). The use of the electrospun amino-functionalized nanofibre sorbent presentsanefficientand cost-effective alternative for pre-concentration of toxic metals inaqueousenvironments.
- Full Text:
- Date Issued: 2012
- Authors: Darko, G , Sobola, A , Adewuyi, Sheriff , Okonkwo, J O , Torto, N
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6571 , http://hdl.handle.net/10962/d1004134
- Description: This paper presents a new approach for pre-concentrating toxic metals (As, Cd, Ni and Pb) in aqueous environments using an amino-functionalized electrospun nanofibre sorbent. The sorbent, composed of nanofibres of average diameter 80 ± 10 nm and specific surface area of 58m2 g–1, exhibited fast adsorption kinetics (<20 min) for As, Cd, Ni and Pb. The optimalpHfor the uptake of As, Cd, Ni and Pb were 5.5, 6.0, 6.5 and 11, respectively. The adsorption process best fitted the Freundlich isothermand followed the first-order kinetics. The highest pre-concentration achieved using the sorbent was 41.99 (Ni in treated wastewater). The capacity of the sorbent to pre-concentrate the toxic metals was compared with those of aqua regia and HNO3+H2O2 digestions. The pre-concentration factors achieved for Cd in river water samples can be ranked as aqua regia digestion (0.73) > adsorption (0.34)>HNO3+H2O2 (0.23) digestion.Asimilar trend was observed for Ni in river water as well as Ni andCdin tap water samples. Pb ions in the river water samples were pre-concentrated slightly better using the two digestion methods pre-concentration factors ~22) compared to adsorption method (pre-concentration factor ~21). The use of the electrospun amino-functionalized nanofibre sorbent presentsanefficientand cost-effective alternative for pre-concentration of toxic metals inaqueousenvironments.
- Full Text:
- Date Issued: 2012
An investigation into the use of anaerobic digestion for the treatment of tannery wastewaters
- Authors: Jackson-Moss, Clive Alan
- Date: 1991
- Subjects: Tanneries -- Waste disposal , Sewage sludge -- South Africa -- Management , Sewage -- Purification -- Biological treatment -- South Africa , Water quality management -- South Africa , Water -- Purification -- Biological treatment -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4059 , http://hdl.handle.net/10962/d1004120 , Tanneries -- Waste disposal , Sewage sludge -- South Africa -- Management , Sewage -- Purification -- Biological treatment -- South Africa , Water quality management -- South Africa , Water -- Purification -- Biological treatment -- South Africa
- Description: The anaerobic digestion of tannery wastewaters was investigated with a view to using this form of treatment in the tanning industry. As these wastewaters are extremely complex and contain high concentrations of both inorganic and organic compounds, the effect of these individual compounds on the anaerobic digestion process was investigated in detail, in order to ascertain the fate of these compounds during the digestion process. The experiments comprising the initial toxicity study were carried out as adaptation experiments using a synthetic wastewater. It was found that the heavy metals such as chrome, aluminium and iron precipitated and accumulated in the sludge bed of the digesters . The soluble ions such as sodium and chloride were not retained and passed through the digesters. Approximately 20 % of the calcium ions were removed through precipitation, with the remainder being present in the digester effluent . Under the anaerobic conditions, ammonification of the organic nitrogen occurred, and influent sulphates were reduced to sulphides . These sulphides were present as either H2S, HS or insoluble sulphides. As these compounds under investigation on caused no inhibition of the anaerobic digestion process at the concentrations found in tannery wastewaters, the anaerobic treatment of these wastewaters appeared to be possible, provided the bacteria were given sufficient time to adapt to the potentially toxic compounds. However, despite the findings of the synthetic study, the successful anaerobic digestion of the tannery effluents could not be achieved. Although the use of acid was found to be essential in order to control the digester pH in the optimum range, the metabolism of the methanogenic bacteria was inhibited by the presence or absence of unknown compounds. Neither the addition of essential trace nutrients, nor the prevention of the competition between the methanogens and the sulphate-reducing bacteria were able to reverse this inhibition. As tannery effluents contain very low concentrations of phosphorous, it is possible that the methanogens were inhibited by a lack of phosphorous, which is essential during methanogenesis. In contrast to the results obtained from the effluent experiments, the anaerobic digestion of tannery sludge was found to be possible. Of the organic solids present in the sludge, 60 % were degraded and converted into biogas, which had a methane content greater than 70 %. The degradation of the organic solids ensured that COD and PV reductions of greater than 90 % were achieved, and the fate of the compounds in the digesters were in agreement with the findings of the v synthetic study. Efforts to improve the efficiency of the digestion process through the addition of trace nutrients and the use of a two-stage process were only successful in bringing about a minor improvement in digester performance. The overall results of this investigation show, therefore, that although the anaerobic treatment of the tannery effluent was not achieved, the successful anaerobic digestion of tannery sludge is possible at low loading rates. As many difficulties still need to be solved, a great deal of further research is necessary if anaerobic digestion is to be used on an industrial scale for the treatment and disposal of tannery wastewaters.
- Full Text:
- Date Issued: 1991
- Authors: Jackson-Moss, Clive Alan
- Date: 1991
- Subjects: Tanneries -- Waste disposal , Sewage sludge -- South Africa -- Management , Sewage -- Purification -- Biological treatment -- South Africa , Water quality management -- South Africa , Water -- Purification -- Biological treatment -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4059 , http://hdl.handle.net/10962/d1004120 , Tanneries -- Waste disposal , Sewage sludge -- South Africa -- Management , Sewage -- Purification -- Biological treatment -- South Africa , Water quality management -- South Africa , Water -- Purification -- Biological treatment -- South Africa
- Description: The anaerobic digestion of tannery wastewaters was investigated with a view to using this form of treatment in the tanning industry. As these wastewaters are extremely complex and contain high concentrations of both inorganic and organic compounds, the effect of these individual compounds on the anaerobic digestion process was investigated in detail, in order to ascertain the fate of these compounds during the digestion process. The experiments comprising the initial toxicity study were carried out as adaptation experiments using a synthetic wastewater. It was found that the heavy metals such as chrome, aluminium and iron precipitated and accumulated in the sludge bed of the digesters . The soluble ions such as sodium and chloride were not retained and passed through the digesters. Approximately 20 % of the calcium ions were removed through precipitation, with the remainder being present in the digester effluent . Under the anaerobic conditions, ammonification of the organic nitrogen occurred, and influent sulphates were reduced to sulphides . These sulphides were present as either H2S, HS or insoluble sulphides. As these compounds under investigation on caused no inhibition of the anaerobic digestion process at the concentrations found in tannery wastewaters, the anaerobic treatment of these wastewaters appeared to be possible, provided the bacteria were given sufficient time to adapt to the potentially toxic compounds. However, despite the findings of the synthetic study, the successful anaerobic digestion of the tannery effluents could not be achieved. Although the use of acid was found to be essential in order to control the digester pH in the optimum range, the metabolism of the methanogenic bacteria was inhibited by the presence or absence of unknown compounds. Neither the addition of essential trace nutrients, nor the prevention of the competition between the methanogens and the sulphate-reducing bacteria were able to reverse this inhibition. As tannery effluents contain very low concentrations of phosphorous, it is possible that the methanogens were inhibited by a lack of phosphorous, which is essential during methanogenesis. In contrast to the results obtained from the effluent experiments, the anaerobic digestion of tannery sludge was found to be possible. Of the organic solids present in the sludge, 60 % were degraded and converted into biogas, which had a methane content greater than 70 %. The degradation of the organic solids ensured that COD and PV reductions of greater than 90 % were achieved, and the fate of the compounds in the digesters were in agreement with the findings of the v synthetic study. Efforts to improve the efficiency of the digestion process through the addition of trace nutrients and the use of a two-stage process were only successful in bringing about a minor improvement in digester performance. The overall results of this investigation show, therefore, that although the anaerobic treatment of the tannery effluent was not achieved, the successful anaerobic digestion of tannery sludge is possible at low loading rates. As many difficulties still need to be solved, a great deal of further research is necessary if anaerobic digestion is to be used on an industrial scale for the treatment and disposal of tannery wastewaters.
- Full Text:
- Date Issued: 1991
Design, construction and performance evaluation of an agitated portable biogas digester under greenhouse-regulated temperature
- Authors: Mutungwazi Asheal
- Date: 2017
- Subjects: Sewage -- Purification -- Anaerobic treatment Green technology Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9055 , vital:34222
- Description: Biogas yield in anaerobic digesters is negatively affected by low temperatures during cold seasons and nights, temperature fluctuations and inefficient agitation. Electrical heating and underground digester installations have been used to help minimise these effects but the high cost of electrical heating, infeasibility of underground installations in some terrains, inefficient agitation and difficult maintenance continue to be major set-backs to high biogas yields. In this study a 100 ℓ, agitated, portable carbon steel digester housed within a greenhouse, whose operation temperature is automatically maintained at an optimum of 35 ± 1 oC by means of an ON/OFF electronic circuit for ventilation control through a suitably sized window and insulation offered by an air film trapped in-between a double layer of polyethylene plastic covering of the greenhouse, was designed. Cow dung from a dairy farm at the University of Fort Hare with total solids (TS), volatile solids (VS), chemical oxygen demand (COD) and ammonia nitrogen content of 162348.67 mg/ℓ, 116543.98 mg/ℓ, 37 879 mg/ℓ and 128 - 235 mg/ℓ respectively was used for the performance evaluation of the digester. Analysis of the biogas produced starting from day 6 of the 31-day retention period showed a specific biogas yield of 0.036 m3/kgVSadded and a methane yield of 55percent. The optimum pH maintained was 7.2 and the COD reduction achieved during the digestion period was 61percent. This simple, easy to construct, inexpensive yet efficient design will lead to improved biogas yields and quality and faster dissemination of the biogas technology.
- Full Text:
- Date Issued: 2017
- Authors: Mutungwazi Asheal
- Date: 2017
- Subjects: Sewage -- Purification -- Anaerobic treatment Green technology Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9055 , vital:34222
- Description: Biogas yield in anaerobic digesters is negatively affected by low temperatures during cold seasons and nights, temperature fluctuations and inefficient agitation. Electrical heating and underground digester installations have been used to help minimise these effects but the high cost of electrical heating, infeasibility of underground installations in some terrains, inefficient agitation and difficult maintenance continue to be major set-backs to high biogas yields. In this study a 100 ℓ, agitated, portable carbon steel digester housed within a greenhouse, whose operation temperature is automatically maintained at an optimum of 35 ± 1 oC by means of an ON/OFF electronic circuit for ventilation control through a suitably sized window and insulation offered by an air film trapped in-between a double layer of polyethylene plastic covering of the greenhouse, was designed. Cow dung from a dairy farm at the University of Fort Hare with total solids (TS), volatile solids (VS), chemical oxygen demand (COD) and ammonia nitrogen content of 162348.67 mg/ℓ, 116543.98 mg/ℓ, 37 879 mg/ℓ and 128 - 235 mg/ℓ respectively was used for the performance evaluation of the digester. Analysis of the biogas produced starting from day 6 of the 31-day retention period showed a specific biogas yield of 0.036 m3/kgVSadded and a methane yield of 55percent. The optimum pH maintained was 7.2 and the COD reduction achieved during the digestion period was 61percent. This simple, easy to construct, inexpensive yet efficient design will lead to improved biogas yields and quality and faster dissemination of the biogas technology.
- Full Text:
- Date Issued: 2017
Microalgae biomass as fermentation feedstock
- Authors: Tijjani-Oshungboye, Kubura
- Date: 2012
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5956 , http://hdl.handle.net/10962/d1006168
- Description: The search for alternative energy is as a result of pollution generated by the utilization of fossil fuel. Bearing in mind the increase in demand which exceeds supply, alternative energy must reduce the carbon foot print in order to relieve use of fossil fuels. Biogas generation from wastes is an old technology that has been in existence for decades. This same concept was behind the development of the integrated algae ponding system (IAPS), where the use of microalgae biomass is adopted for waste water treatment and, anaerobic digestion which is a component of the IAPS, simultaneously generates biogas. The biogas from the IAPS was quantified in order to evaluate efficiency of the system and the anaerobic fermentation pit was also simulated in the laboratory to optimize biogas production using microalgae as co-fermentation feedstock. Microalgae biomass was evaluated as potential feedstock for ethanol fermentation and the use of biogas was investigated as an alternative transportation fuel. In an IAPS substantial biomass is produced on an annual basis. For effective treatment of waste water and efficient nutrient removal continuous harvest of the biomass is required. In the present study, water treatment efficiency of the EBRU IAPS was determined by carrying out a series of tests to investigate the decline in nutrient content from port of influent entry to effluent discharge. There was more than a 60% reduction in nutrient content with a concomitant increase in biomass and growth rate of 0.25 g/L . Biogas generated from the IAPS was quantified using a flow meter and the composition determined by gas chromatography. Methane which is the principal constituent of biogas was 75% (±SD, n=IO) and 2.34 m³.d⁻¹ was measured as biogas yield from the EBRU IAPS. The study also investigated the use of the excess microalgae biomass as a fermentation feedstock for ethanol production and as a co-substrate in order to increase biogas yield from the system. Positive results were achieved for ethanol production from microalgae although yield was generally low. About 385 mg.⁻¹ of ethanol was recovered when glucose was used as substrate, where as only 115 mg.⁻¹ of ethanol was recovered with microalgae as substrate. Suitability of microalgae as feedstock for ethanol generation and biogas generation was determined by characterisation which involved estimation of the carbohydrate, protein and lipid content, and analysis of the C, H, 0, Nand S content. Laboratory fed batch reactors simulated the anaerobic digestion process in order to study the effect of microalgae biomass as co-substrate for biogas generation. The fermenters were inoculated with an active consortium obtained from the Makana municipal waste water works and microbial studies were carried to confirm the presence of the anaerobic consortium. Different pre-treatments (concentrated, rupturing and freeze-drying) were used to disrupt the microalgae prior to introduction into fermenters in a ratio of 3: I. COD, TC, TOC, SO₄⁻² and TN analyses were carried out to monitor nutrient depletion in the system, and biogas generated by the system was quantified by volumetric analysis and the gas composition determined. Statistical analysis (ANOVA) was used to test for significant difference pre and post addition of microalgae. In the most effective fermenter, biogas production was at an average of 394 ml.d·' and CH₄ ratio in the biogas increased by over a 100%. Theoretical methane potential of the IAPS and the Makana municipal waste water works treating 5 ML.d⁻¹ of domestic waste was determined using the empirical formula of waste water and shown to yield 1,037,342.40 m³/yr. The projected biogas yield from this system was used to evaluate its potential use as transportation fuel. In total, 198,673 .55 m³ of biogas was estimated to be required to fuel the Rhodes University's fleet of vehicles, with a residual biogas stream of 838,668.85 m³. It was also demonstrated in the present study that renewable energy sourced from biomass has the potential of supplanting the use of fossil fuel resulting in less pollution leading to a cleaner and healthier environment.
- Full Text:
- Date Issued: 2012
- Authors: Tijjani-Oshungboye, Kubura
- Date: 2012
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5956 , http://hdl.handle.net/10962/d1006168
- Description: The search for alternative energy is as a result of pollution generated by the utilization of fossil fuel. Bearing in mind the increase in demand which exceeds supply, alternative energy must reduce the carbon foot print in order to relieve use of fossil fuels. Biogas generation from wastes is an old technology that has been in existence for decades. This same concept was behind the development of the integrated algae ponding system (IAPS), where the use of microalgae biomass is adopted for waste water treatment and, anaerobic digestion which is a component of the IAPS, simultaneously generates biogas. The biogas from the IAPS was quantified in order to evaluate efficiency of the system and the anaerobic fermentation pit was also simulated in the laboratory to optimize biogas production using microalgae as co-fermentation feedstock. Microalgae biomass was evaluated as potential feedstock for ethanol fermentation and the use of biogas was investigated as an alternative transportation fuel. In an IAPS substantial biomass is produced on an annual basis. For effective treatment of waste water and efficient nutrient removal continuous harvest of the biomass is required. In the present study, water treatment efficiency of the EBRU IAPS was determined by carrying out a series of tests to investigate the decline in nutrient content from port of influent entry to effluent discharge. There was more than a 60% reduction in nutrient content with a concomitant increase in biomass and growth rate of 0.25 g/L . Biogas generated from the IAPS was quantified using a flow meter and the composition determined by gas chromatography. Methane which is the principal constituent of biogas was 75% (±SD, n=IO) and 2.34 m³.d⁻¹ was measured as biogas yield from the EBRU IAPS. The study also investigated the use of the excess microalgae biomass as a fermentation feedstock for ethanol production and as a co-substrate in order to increase biogas yield from the system. Positive results were achieved for ethanol production from microalgae although yield was generally low. About 385 mg.⁻¹ of ethanol was recovered when glucose was used as substrate, where as only 115 mg.⁻¹ of ethanol was recovered with microalgae as substrate. Suitability of microalgae as feedstock for ethanol generation and biogas generation was determined by characterisation which involved estimation of the carbohydrate, protein and lipid content, and analysis of the C, H, 0, Nand S content. Laboratory fed batch reactors simulated the anaerobic digestion process in order to study the effect of microalgae biomass as co-substrate for biogas generation. The fermenters were inoculated with an active consortium obtained from the Makana municipal waste water works and microbial studies were carried to confirm the presence of the anaerobic consortium. Different pre-treatments (concentrated, rupturing and freeze-drying) were used to disrupt the microalgae prior to introduction into fermenters in a ratio of 3: I. COD, TC, TOC, SO₄⁻² and TN analyses were carried out to monitor nutrient depletion in the system, and biogas generated by the system was quantified by volumetric analysis and the gas composition determined. Statistical analysis (ANOVA) was used to test for significant difference pre and post addition of microalgae. In the most effective fermenter, biogas production was at an average of 394 ml.d·' and CH₄ ratio in the biogas increased by over a 100%. Theoretical methane potential of the IAPS and the Makana municipal waste water works treating 5 ML.d⁻¹ of domestic waste was determined using the empirical formula of waste water and shown to yield 1,037,342.40 m³/yr. The projected biogas yield from this system was used to evaluate its potential use as transportation fuel. In total, 198,673 .55 m³ of biogas was estimated to be required to fuel the Rhodes University's fleet of vehicles, with a residual biogas stream of 838,668.85 m³. It was also demonstrated in the present study that renewable energy sourced from biomass has the potential of supplanting the use of fossil fuel resulting in less pollution leading to a cleaner and healthier environment.
- Full Text:
- Date Issued: 2012
Isolation of a Clostridium Beijerinckii sLM01 cellulosome and the effect of sulphide on anaerobic digestion
- Authors: Mayende, Lungisa
- Date: 2007
- Subjects: Cellulose , Clostridium , Cellulase , Sulfides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3973 , http://hdl.handle.net/10962/d1004032 , Cellulose , Clostridium , Cellulase , Sulfides
- Description: Cellulose is the most abundant and the most resistant and stable natural organic compound on earth. Enzyme hydrolysis is difficult because of its insolubility and heterogeneity. Some (anaerobic) microorganisms have overcome this by having a multienzyme system called the cellulosome. The aims of the study were to isolate a mesophilic Clostridium sp. from a biosulphidogenic bioreactor, to purify the cellulosome from this culture, to determine the cellulase and endoglucanase activities using Avicel and carboxymethylcellulose (CMC) as substrates and the dinitrosalicyclic (DNS) method. The organism was identified using 16S rDNA sequence analysis. The sequence obtained indicated that a strain of Clostridium beijerinckii was isolated. The cellulosome was purified from the putative C. beijerinckii sLM01 host culture using affinity chromatography purification and affinity digestion purification procedures. The cellulosomal and non-cellulosomal fractions of C. beijerinckii sLM01 were separated successfully, but the majority of the endoglucanase activity was lost during the Sepharose 4B chromatography step. These cellulosomal and non-cellulosomal fractions were characterised with regards to their pH and temperature optima and effector sensitivity. Increased additions of sulphide activated the cellulase activity of the cellulosomal and non-cellulosomal fractions up to 700 %, while increased additions of sulphate either increased the activity slightly or inhibited it dramatically, depending on the cellulosomal and non-cellulosomal fractions. Increased additions of cellobiose, glucose and acetate inhibited the cellulase and endoglucanase activities. pH optima of 5.0 and 7.5 were observed for cellulases and 5.0 for endoglucanases of the cellulosomal fraction. The noncellulosomal fraction exhibited a pH optimum of 7.5 for both cellulase and endoglucanase activities. Both fractions and enzymes exhibited a temperature optimum of 30 °C. The fundamental knowledge gained from the characterisation was applied to anaerobic digestion, where the effect of sulphide on the rate-limiting step was determined. Sulphide activated cellulase and endoglucanase activities and increased the % chemical oxygen demand (COD) removal rate. Levels of volatile fatty acids (VFAs) were higher in the bioreactor containing sulphide, substrate and C. beijerinckii. Sulphide therefore accelerated the rate-limiting step of anaerobic digestion.
- Full Text:
- Date Issued: 2007
- Authors: Mayende, Lungisa
- Date: 2007
- Subjects: Cellulose , Clostridium , Cellulase , Sulfides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3973 , http://hdl.handle.net/10962/d1004032 , Cellulose , Clostridium , Cellulase , Sulfides
- Description: Cellulose is the most abundant and the most resistant and stable natural organic compound on earth. Enzyme hydrolysis is difficult because of its insolubility and heterogeneity. Some (anaerobic) microorganisms have overcome this by having a multienzyme system called the cellulosome. The aims of the study were to isolate a mesophilic Clostridium sp. from a biosulphidogenic bioreactor, to purify the cellulosome from this culture, to determine the cellulase and endoglucanase activities using Avicel and carboxymethylcellulose (CMC) as substrates and the dinitrosalicyclic (DNS) method. The organism was identified using 16S rDNA sequence analysis. The sequence obtained indicated that a strain of Clostridium beijerinckii was isolated. The cellulosome was purified from the putative C. beijerinckii sLM01 host culture using affinity chromatography purification and affinity digestion purification procedures. The cellulosomal and non-cellulosomal fractions of C. beijerinckii sLM01 were separated successfully, but the majority of the endoglucanase activity was lost during the Sepharose 4B chromatography step. These cellulosomal and non-cellulosomal fractions were characterised with regards to their pH and temperature optima and effector sensitivity. Increased additions of sulphide activated the cellulase activity of the cellulosomal and non-cellulosomal fractions up to 700 %, while increased additions of sulphate either increased the activity slightly or inhibited it dramatically, depending on the cellulosomal and non-cellulosomal fractions. Increased additions of cellobiose, glucose and acetate inhibited the cellulase and endoglucanase activities. pH optima of 5.0 and 7.5 were observed for cellulases and 5.0 for endoglucanases of the cellulosomal fraction. The noncellulosomal fraction exhibited a pH optimum of 7.5 for both cellulase and endoglucanase activities. Both fractions and enzymes exhibited a temperature optimum of 30 °C. The fundamental knowledge gained from the characterisation was applied to anaerobic digestion, where the effect of sulphide on the rate-limiting step was determined. Sulphide activated cellulase and endoglucanase activities and increased the % chemical oxygen demand (COD) removal rate. Levels of volatile fatty acids (VFAs) were higher in the bioreactor containing sulphide, substrate and C. beijerinckii. Sulphide therefore accelerated the rate-limiting step of anaerobic digestion.
- Full Text:
- Date Issued: 2007
Treatment of wine distillery wastewaters by high rate anaerobic digestion and submerged membrane systems
- Authors: Melamane, Xolisa Lorraine
- Date: 2007
- Subjects: Wine and wine making -- Waste disposal Sewage -- Purification -- Anaerobic treatment Membrane reactors Bioreactors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3963 , http://hdl.handle.net/10962/d1004022
- Description: Experiences in treating wine distillery wastewaters (WDWs) contribute to the field of oenology as many oenologists are concerned with the selection, efficiency and economy of their wastewaters. Wine distillery wastewaters are strongly acidic, have high chemical oxygen demand (COD), high polyphenol content and are highly variable. Primary attention was focussed on sustainable biological treatment of raw wine distillery wastewater (RWDW) and fungally pre-treated wine distillery wastewater (FTWDW) by energy-efficient high rate anaerobic digestion (AD). This study also explored the development of a novel dual-stage anaerobic digestion ultrafiltration (ADUF) process, using a ceramic submerged membrane bioreactor (SMBR) in the treatment of both RWDW and FTWDW. The first stage was for the selection of microorganisms that were able to treat the toxic pollutants from WDWs. It was operated at a high feed-to-microorganism ratio. The second stage, a secondary digester, was operated like a typical membrane bioreactor at a low feed-to-microorganism ratio to sustain a stable efficient population for a long period. The characteristics of RWDW were as follows: pH 3.83, 15 000 mg/l soluble COD (CODs) and 5229 mg/l of phenols. After pre-treatment of RWDW with Trametes pubescens, starting parameters for FTWDW were as follows: pH 6.7, 7000 mg/l soluble COD (CODS) and 1440 mg/l of phenols. During operation of a high rate anaerobic digester for RWDW treatment, K2HPO4 was required for buffering the digester. Volatile fatty acid concentrations were <300 mg/l throughout the study, indicating degradation of organic acids present. Mean CODS removal efficiency for the 130 day study was 87 %, while the mean polyphenol removal efficiency was 85 %. Addition of 50 mg/l Fe3+ increased the removal efficiencies of CODS to 97 % and of polyphenols to 99 %. High removal efficiencies of CODS and polyphenols were attributed to the addition of macronutrients and micronutrients that caused pH stability and stimulated microbial activity. The CODS removal efficiency of high rate anaerobic digestion of FTWDW reached 99.5%. During FTWDW digestion, pH buffering was achieved using K2HPO4. A combination of a SMBR and a secondary digester was tested for the treatment of RWDW and FTWDW during a 30 day study. Results for RWDW showed that pH buffering was achieved by dosing the feed stream with CaCO3 and K2HPO4. Buffering proved to be significant for optimum performance of the system in removal of soluble CODS, and volatile fatty acids (VFAs). Different batches of RWDW used for feeding the reactor had variable compositions with respect to concentrations of nitrates, ammonium and total phenolic compounds. Ammonium accumulated in the secondary digester after 14 days of system operation, indicated the time required for the establishment of anaerobic conditions in the system. Dosing of the SMBR treating FTWDW with CaCO3 and K2HPO4 buffered the pH; iii this proved significant for optimum performance of the system in removal of CODS. The system eliminated an average of 86 (± 4) % of CODS present in the FTWDW. The residual CODS levels in the effluent were approximately 400 mg/l, significantly lower than the concentrations observed when treating RWDW, indicating that fungal pre-treatment might have provided additional nutrients for removal of recalcitrant components of the wastewater. The resulting effluent was rich in nitrates and phosphates and might be used as a fertiliser. Alternatively, a membrane process, such as reverse osmosis (RO) or nanofiltration (NF) could be applied to raise the water quality to meet the levels required for reuse. Biomass samples were obtained from the four treatment systems and population shifts characterization using phospholipids fatty acids (PLFA) and 16S rRNA analysis to provide an indication of limitations within the microbial population. The values of the concentrations of the individual PLFAs detected in the samples indicated that ten bacterial species were present, with the GC content of the 16S rRNA increasing from 1 to 10. Analysis of denaturing gradient gel electrophoresis DGGE data indicated that the composition of the archeal community changed the consortia used for both RWDW and FTWDW treatment. Changes in band intensities indicated the presence of different components of the archeal communities. The results were not conclusive in terms of species identity as cloning, sequencing and phylogenetic analyses were not performed, but they did indicate microbial population shifts and species diversity for high rate anaerobic digestion. The results also confirmed prevalence of relatively few species during operation of SMBRs for treatment of RWDW and FTWDW, which suggested that the microorganisms that survived were either tolerant of toxic components of RWDW and FTWDW or they were able to remove polyphenols.
- Full Text:
- Date Issued: 2007
- Authors: Melamane, Xolisa Lorraine
- Date: 2007
- Subjects: Wine and wine making -- Waste disposal Sewage -- Purification -- Anaerobic treatment Membrane reactors Bioreactors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3963 , http://hdl.handle.net/10962/d1004022
- Description: Experiences in treating wine distillery wastewaters (WDWs) contribute to the field of oenology as many oenologists are concerned with the selection, efficiency and economy of their wastewaters. Wine distillery wastewaters are strongly acidic, have high chemical oxygen demand (COD), high polyphenol content and are highly variable. Primary attention was focussed on sustainable biological treatment of raw wine distillery wastewater (RWDW) and fungally pre-treated wine distillery wastewater (FTWDW) by energy-efficient high rate anaerobic digestion (AD). This study also explored the development of a novel dual-stage anaerobic digestion ultrafiltration (ADUF) process, using a ceramic submerged membrane bioreactor (SMBR) in the treatment of both RWDW and FTWDW. The first stage was for the selection of microorganisms that were able to treat the toxic pollutants from WDWs. It was operated at a high feed-to-microorganism ratio. The second stage, a secondary digester, was operated like a typical membrane bioreactor at a low feed-to-microorganism ratio to sustain a stable efficient population for a long period. The characteristics of RWDW were as follows: pH 3.83, 15 000 mg/l soluble COD (CODs) and 5229 mg/l of phenols. After pre-treatment of RWDW with Trametes pubescens, starting parameters for FTWDW were as follows: pH 6.7, 7000 mg/l soluble COD (CODS) and 1440 mg/l of phenols. During operation of a high rate anaerobic digester for RWDW treatment, K2HPO4 was required for buffering the digester. Volatile fatty acid concentrations were <300 mg/l throughout the study, indicating degradation of organic acids present. Mean CODS removal efficiency for the 130 day study was 87 %, while the mean polyphenol removal efficiency was 85 %. Addition of 50 mg/l Fe3+ increased the removal efficiencies of CODS to 97 % and of polyphenols to 99 %. High removal efficiencies of CODS and polyphenols were attributed to the addition of macronutrients and micronutrients that caused pH stability and stimulated microbial activity. The CODS removal efficiency of high rate anaerobic digestion of FTWDW reached 99.5%. During FTWDW digestion, pH buffering was achieved using K2HPO4. A combination of a SMBR and a secondary digester was tested for the treatment of RWDW and FTWDW during a 30 day study. Results for RWDW showed that pH buffering was achieved by dosing the feed stream with CaCO3 and K2HPO4. Buffering proved to be significant for optimum performance of the system in removal of soluble CODS, and volatile fatty acids (VFAs). Different batches of RWDW used for feeding the reactor had variable compositions with respect to concentrations of nitrates, ammonium and total phenolic compounds. Ammonium accumulated in the secondary digester after 14 days of system operation, indicated the time required for the establishment of anaerobic conditions in the system. Dosing of the SMBR treating FTWDW with CaCO3 and K2HPO4 buffered the pH; iii this proved significant for optimum performance of the system in removal of CODS. The system eliminated an average of 86 (± 4) % of CODS present in the FTWDW. The residual CODS levels in the effluent were approximately 400 mg/l, significantly lower than the concentrations observed when treating RWDW, indicating that fungal pre-treatment might have provided additional nutrients for removal of recalcitrant components of the wastewater. The resulting effluent was rich in nitrates and phosphates and might be used as a fertiliser. Alternatively, a membrane process, such as reverse osmosis (RO) or nanofiltration (NF) could be applied to raise the water quality to meet the levels required for reuse. Biomass samples were obtained from the four treatment systems and population shifts characterization using phospholipids fatty acids (PLFA) and 16S rRNA analysis to provide an indication of limitations within the microbial population. The values of the concentrations of the individual PLFAs detected in the samples indicated that ten bacterial species were present, with the GC content of the 16S rRNA increasing from 1 to 10. Analysis of denaturing gradient gel electrophoresis DGGE data indicated that the composition of the archeal community changed the consortia used for both RWDW and FTWDW treatment. Changes in band intensities indicated the presence of different components of the archeal communities. The results were not conclusive in terms of species identity as cloning, sequencing and phylogenetic analyses were not performed, but they did indicate microbial population shifts and species diversity for high rate anaerobic digestion. The results also confirmed prevalence of relatively few species during operation of SMBRs for treatment of RWDW and FTWDW, which suggested that the microorganisms that survived were either tolerant of toxic components of RWDW and FTWDW or they were able to remove polyphenols.
- Full Text:
- Date Issued: 2007
Biodiversity of Salmonella strains isolated from selected water sources and wastewater discharge points in the Easern Cape Province of South Africa
- Authors: Mafu, Nwabisa Charity
- Date: 2008
- Subjects: Biodiversity conservation -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Salmonella typhimurium
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11248 , http://hdl.handle.net/10353/74 , Biodiversity conservation -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Salmonella typhimurium
- Description: In this study, the diversity of forty Salmonella isolates from selected drinking water and wastewater sources in the Eastern Cape Province of South Africa was assessed using parameters such as protein and lipopolysaccharide profile analysis, DNA fingerprinting and antibiotic susceptibility profile as test indices. Wastewater samples from Amalinda, Shornville and Fort Hare wastewater plants, and water samples from Gogogo and Tyume rivers were collected on ice and transported to the laboratory of the department of Microbiology and Biochemistry, University of Fort Hare for processing. The DNA dendograms of Salmonella and the applied UPGMA revealed 4 similarity groups of the strains. Most of the strains recovered from Amalinda, Shornville, Fort Hare wastewater plants, Gogogo and Tyume rivers show a high percentage of genetic similarity. On the other hand, protein dendograms of Salmonella isolates revealed 2 similarity groups which varied widely. Also, the lipopolysaccharide dendograms revealed three similarity groups with the first similarity groups showing a very high relatedness between strains from different water sources. The second similarity group included 16 strains which formed a rather homogenous group, and the third similarity group formed a distinct group. Of the seven antibiotics and sulfonamides tested against the Salmonella species, five namely, neomycin, chloramphenicol, kanamycin, streptomycin and cotrimoxazole were significantly inhibitory, while the bacteria showed considerable resistance to doxycycline and sulphamethoxazole. Our results based on restriction digestion, SDS/PAGE and dendogram construction show that there is a high similarity between the forty Salmonella strains studied, and that these methods are valuable tools for evaluating the relatedness ofSalmonella species. Our observations have proffered a veritable reference point on the diversity of Salmonella strains in the studied area.
- Full Text:
- Date Issued: 2008
- Authors: Mafu, Nwabisa Charity
- Date: 2008
- Subjects: Biodiversity conservation -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Salmonella typhimurium
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11248 , http://hdl.handle.net/10353/74 , Biodiversity conservation -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Salmonella typhimurium
- Description: In this study, the diversity of forty Salmonella isolates from selected drinking water and wastewater sources in the Eastern Cape Province of South Africa was assessed using parameters such as protein and lipopolysaccharide profile analysis, DNA fingerprinting and antibiotic susceptibility profile as test indices. Wastewater samples from Amalinda, Shornville and Fort Hare wastewater plants, and water samples from Gogogo and Tyume rivers were collected on ice and transported to the laboratory of the department of Microbiology and Biochemistry, University of Fort Hare for processing. The DNA dendograms of Salmonella and the applied UPGMA revealed 4 similarity groups of the strains. Most of the strains recovered from Amalinda, Shornville, Fort Hare wastewater plants, Gogogo and Tyume rivers show a high percentage of genetic similarity. On the other hand, protein dendograms of Salmonella isolates revealed 2 similarity groups which varied widely. Also, the lipopolysaccharide dendograms revealed three similarity groups with the first similarity groups showing a very high relatedness between strains from different water sources. The second similarity group included 16 strains which formed a rather homogenous group, and the third similarity group formed a distinct group. Of the seven antibiotics and sulfonamides tested against the Salmonella species, five namely, neomycin, chloramphenicol, kanamycin, streptomycin and cotrimoxazole were significantly inhibitory, while the bacteria showed considerable resistance to doxycycline and sulphamethoxazole. Our results based on restriction digestion, SDS/PAGE and dendogram construction show that there is a high similarity between the forty Salmonella strains studied, and that these methods are valuable tools for evaluating the relatedness ofSalmonella species. Our observations have proffered a veritable reference point on the diversity of Salmonella strains in the studied area.
- Full Text:
- Date Issued: 2008
Enzymology of activated sewage sludge during anaerobic treatment of wastewaters : identification, characterisation, isolation and partial purification of proteases
- Tshivhunge, Azwiedziswi Sylvia
- Authors: Tshivhunge, Azwiedziswi Sylvia
- Date: 2001
- Subjects: Sewage sludge , Sewage sludge -- Environmental aspects , Sewage sludge digestion , Anaerobic bacteria
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4012 , http://hdl.handle.net/10962/d1004072 , Sewage sludge , Sewage sludge -- Environmental aspects , Sewage sludge digestion , Anaerobic bacteria
- Description: During anaerobic digestion bacteria inside the digester require a carbon source for their growth and metabolism, sewage sludge was used as a carbon source in this study. The COD content was used to measure the disappearance of the substrate. COD content was reduced by 48.3% and 49% in the methanogenic and sulphidogenic bioreactors, respectively, while sulphate concentration was reduced by 40%, producing 70mg/L of hydrogen sulphide as the end product over the first 5-7 days. Sulphate (which is used as a terminal electron acceptor of sulphur reducing bacteria) has little or no effect on the sulphidogenic and methanogenic proteases. Sulphite and sulphide (the intermediate and end product of sulphate reduction) increased protease activity by 20% and 40%-80%, respectively. Maximum protease activity occurred on day 21 in the methanogenic reactor and on day 9 in the sulphidogenic reactor. The absorbance, which indicates the level of amino acid increased to 2 and 9 for methanogenic and sulphidogenic bioreactors, respectively. Proteases that were active during anaerobic digestion were associated with the pellet (organic particulate matter) of the sewage. These enzymes have an optimum activity at pH 10 and at temperature of 50°C. The proteases that were active at pH 5 and 7, had optimum temperatures at 30°C and 60°C, respectively. Due to their association with organic particulate matter, these enzymes were stable at their optimum temperatures for at least five hours at their respective pH. Inhibition by PMSF, TPCK and 1.10-phenanthroline suggested that proteases inside the anaerobic digester are a mixture of cysteine, serine and metalloproteases. At pH 5, however, EDTA appeared to enhance protease activity by 368% (three-fold). Acetic acid decreased protease activity by 21%, while both propionic and butyric acid at 200 mg/L cause total inhibition of protease activity while these acids at higher pH (where they exist as their corresponding salts) exerted little effect. Copper, iron and zinc inhibited protease activity by 85% at pH 5 with concentrations ranging between 200 and 600 mg/L. On the other hand, nickel, showed an increase in protease activity of nearly 250%. At pH 7 and 10, copper had no effect on protease activity while iron, nickel and zinc inhibited these enzymes by 20-40%. Proteases at pH 7 were extracted from the pellet by sonication, releasing 50% of the total enzymes into the solution. The enzymes were precipitated by ammonium sulphate precipitation, and further purified by ion exchange chromatography and gel filtration. Ion exchange chromatography revealed that most of the enzymes that hydrolyse proteins are negatively charged while gel filtration showed that their molecular weight is approximately 500 kDa.
- Full Text:
- Date Issued: 2001
- Authors: Tshivhunge, Azwiedziswi Sylvia
- Date: 2001
- Subjects: Sewage sludge , Sewage sludge -- Environmental aspects , Sewage sludge digestion , Anaerobic bacteria
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4012 , http://hdl.handle.net/10962/d1004072 , Sewage sludge , Sewage sludge -- Environmental aspects , Sewage sludge digestion , Anaerobic bacteria
- Description: During anaerobic digestion bacteria inside the digester require a carbon source for their growth and metabolism, sewage sludge was used as a carbon source in this study. The COD content was used to measure the disappearance of the substrate. COD content was reduced by 48.3% and 49% in the methanogenic and sulphidogenic bioreactors, respectively, while sulphate concentration was reduced by 40%, producing 70mg/L of hydrogen sulphide as the end product over the first 5-7 days. Sulphate (which is used as a terminal electron acceptor of sulphur reducing bacteria) has little or no effect on the sulphidogenic and methanogenic proteases. Sulphite and sulphide (the intermediate and end product of sulphate reduction) increased protease activity by 20% and 40%-80%, respectively. Maximum protease activity occurred on day 21 in the methanogenic reactor and on day 9 in the sulphidogenic reactor. The absorbance, which indicates the level of amino acid increased to 2 and 9 for methanogenic and sulphidogenic bioreactors, respectively. Proteases that were active during anaerobic digestion were associated with the pellet (organic particulate matter) of the sewage. These enzymes have an optimum activity at pH 10 and at temperature of 50°C. The proteases that were active at pH 5 and 7, had optimum temperatures at 30°C and 60°C, respectively. Due to their association with organic particulate matter, these enzymes were stable at their optimum temperatures for at least five hours at their respective pH. Inhibition by PMSF, TPCK and 1.10-phenanthroline suggested that proteases inside the anaerobic digester are a mixture of cysteine, serine and metalloproteases. At pH 5, however, EDTA appeared to enhance protease activity by 368% (three-fold). Acetic acid decreased protease activity by 21%, while both propionic and butyric acid at 200 mg/L cause total inhibition of protease activity while these acids at higher pH (where they exist as their corresponding salts) exerted little effect. Copper, iron and zinc inhibited protease activity by 85% at pH 5 with concentrations ranging between 200 and 600 mg/L. On the other hand, nickel, showed an increase in protease activity of nearly 250%. At pH 7 and 10, copper had no effect on protease activity while iron, nickel and zinc inhibited these enzymes by 20-40%. Proteases at pH 7 were extracted from the pellet by sonication, releasing 50% of the total enzymes into the solution. The enzymes were precipitated by ammonium sulphate precipitation, and further purified by ion exchange chromatography and gel filtration. Ion exchange chromatography revealed that most of the enzymes that hydrolyse proteins are negatively charged while gel filtration showed that their molecular weight is approximately 500 kDa.
- Full Text:
- Date Issued: 2001
Morphology and histochemistry of the digestive tract in the Banded Tilapia (Tilapia Sparrmanii, Smith 1840)
- Authors: Bongile, Bhomela
- Date: 2014
- Subjects: Tilapia sparrmanii, fish; Tilapia; teleost; stomach; digestive system; light microscopy; light microscopy; histology; morphology Teleostei, digestive tube, histology
- Language: English
- Type: Masters, Msc Zoology
- Identifier: http://hdl.handle.net/11260/2401 , vital:41456
- Description: The digestive system of Tilapia sparrmanii, Smith 1894, a small sized cichlid fish widely distributed in Southern Africa and of little economic importance was studied by light microscopy as part of establishing base-line data for future references. The gut in T. sparrmanii was a simple long coiled tube. With greater fish length, the gut progressed into a complexly-coiled definitive form. Strong linear correlations were observed between fish size and gut length. The esophagus was relatively very short and the stomach sac-like and small. Histologically, T. sparrmanii displayed a stratified esophagus epithelium with goblet cells which displayed both neutral and acid mucus at the anterior region. The stomach of T. sparrmanii was divided into three distinct segments the cardiac, fundic, and pyloric portions. The study revealed that the gastric wall is composed of several tunicae: mucosa, submucosa, muscularis and serosa. The tunica mucosa was thrown up into a number of high longitudinal folds projecting into a lumen. The mucosal surface had surface epithelial cells. The epithelium in this region was simple columnar devoid of goblet cells, with glandular regions in the lamina propria. The mucosa of the fundic region had gastric pits lined by columnar epithelium, and simple tubular glands filled most of the lamina propria. The pyloric part of the stomach was very short and its mucosa was slightly folded and devoid of both gastric pits and mucous glandular cells. The lining epithelium of this portion of the stomach was simple columnar and a few goblet cells were seen at its junction with the first part of the intestine. The tunica muscularis of the stomach contained skeletal muscle in the initial and terminal regions, usually intermingled with smooth muscle fibres. Skeletal muscle fibres were also observed in the first portion of the proximal intestine, iii near the junction with the stomach. Gastric pits were present as invaginations of the mucosal surface. Their epithelium secreted both neutral and acid mucins. Simple, straight, tubular unbranched gastric glands occupied most of the surface of the mucosa, and were lined with cells that had eosinophilic granules. The tunica muscularis of the stomach consisted of skeletal muscles usually mixed with smooth muscle fibres. Also, the stomach was separated from the proximal intestine by a pyloric sphincter. Results demonstrate that the intestine was a relatively undifferentiated muscular tube lined with a simple columnar epithelium interspersed with goblet cells. The proximal region had a greater surface area, as revealed by the presence of elongated mucosal ridges. The enterocytes were covered apically with uniform microvilli. The number of goblet cells were moderate in the proximal intestine and fewer in the medial intestine. All segments of the intestine contained neutral and acidic mucins. The distal intestine mucosa was thinner and less elaborately folded and consisted of columnar cells with shorter and sparser microvilli. After the intestinerectal valve, the rectum displayed lower mucosal folds, numerous goblet cells and a thicker muscularis. An ileorectal valve was observed. This confirms that separate intestine and rectum does exist in T. sparrmanii.
- Full Text:
- Authors: Bongile, Bhomela
- Date: 2014
- Subjects: Tilapia sparrmanii, fish; Tilapia; teleost; stomach; digestive system; light microscopy; light microscopy; histology; morphology Teleostei, digestive tube, histology
- Language: English
- Type: Masters, Msc Zoology
- Identifier: http://hdl.handle.net/11260/2401 , vital:41456
- Description: The digestive system of Tilapia sparrmanii, Smith 1894, a small sized cichlid fish widely distributed in Southern Africa and of little economic importance was studied by light microscopy as part of establishing base-line data for future references. The gut in T. sparrmanii was a simple long coiled tube. With greater fish length, the gut progressed into a complexly-coiled definitive form. Strong linear correlations were observed between fish size and gut length. The esophagus was relatively very short and the stomach sac-like and small. Histologically, T. sparrmanii displayed a stratified esophagus epithelium with goblet cells which displayed both neutral and acid mucus at the anterior region. The stomach of T. sparrmanii was divided into three distinct segments the cardiac, fundic, and pyloric portions. The study revealed that the gastric wall is composed of several tunicae: mucosa, submucosa, muscularis and serosa. The tunica mucosa was thrown up into a number of high longitudinal folds projecting into a lumen. The mucosal surface had surface epithelial cells. The epithelium in this region was simple columnar devoid of goblet cells, with glandular regions in the lamina propria. The mucosa of the fundic region had gastric pits lined by columnar epithelium, and simple tubular glands filled most of the lamina propria. The pyloric part of the stomach was very short and its mucosa was slightly folded and devoid of both gastric pits and mucous glandular cells. The lining epithelium of this portion of the stomach was simple columnar and a few goblet cells were seen at its junction with the first part of the intestine. The tunica muscularis of the stomach contained skeletal muscle in the initial and terminal regions, usually intermingled with smooth muscle fibres. Skeletal muscle fibres were also observed in the first portion of the proximal intestine, iii near the junction with the stomach. Gastric pits were present as invaginations of the mucosal surface. Their epithelium secreted both neutral and acid mucins. Simple, straight, tubular unbranched gastric glands occupied most of the surface of the mucosa, and were lined with cells that had eosinophilic granules. The tunica muscularis of the stomach consisted of skeletal muscles usually mixed with smooth muscle fibres. Also, the stomach was separated from the proximal intestine by a pyloric sphincter. Results demonstrate that the intestine was a relatively undifferentiated muscular tube lined with a simple columnar epithelium interspersed with goblet cells. The proximal region had a greater surface area, as revealed by the presence of elongated mucosal ridges. The enterocytes were covered apically with uniform microvilli. The number of goblet cells were moderate in the proximal intestine and fewer in the medial intestine. All segments of the intestine contained neutral and acidic mucins. The distal intestine mucosa was thinner and less elaborately folded and consisted of columnar cells with shorter and sparser microvilli. After the intestinerectal valve, the rectum displayed lower mucosal folds, numerous goblet cells and a thicker muscularis. An ileorectal valve was observed. This confirms that separate intestine and rectum does exist in T. sparrmanii.
- Full Text:
The effect of in vitro digestion on selected biological activities of Hypoxis sobolifera corms
- Authors: Van Rooyen, Anzel
- Date: 2013
- Subjects: Potatoes -- Therapeutic use , Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10344 , http://hdl.handle.net/10948/d1020058
- Description: In South Africa part of the cultural and religious beliefs of the African people is the use of traditional remedies to treat diseases. These remedies are obtained from medicinal plants (Steenkamp, 2003). One of the most frequently traded plants in the Eastern Cape is Hypoxis, commonly known as Afrika patat, or African potato. South African traditional healers instruct patients to brew the fresh Hypoxis corm as a tea and then ingest it (Steenkamp, 2006a). This prompted an investigation into the digestive stability of a traditionally prepared Hypoxis extract. The H. sobolifera extracts were digested using a simulated gastric/small intestinal digestion and their biological activity determined. The hot water H. sobolifera extract before digestion only showed cytotoxic activity against cancer cell lines at very high concentrations which are not likely to be achieved under normal ingestion circumstances. In Chang liver cells on the other hand, chronic exposure to the hot water H. sobolifera extract increased glucose uptake in amounts similar to that of metformin. On the negative side, the glucose utilization stimulation was lost due to the simulated digestion process. The significant inhibition of AGEs by hot water H. sobolifera extract (IC50 of 6.3 Ig/ml) is a very encouraging result as treatment in the management of diabetes. This activity was only slightly reduced by the in vitro digestion process. Also observed was enzyme inhibition activity by traditionally prepared H. sobolifera, with ∝-amylase being inhibited (IC50 of approximately 250 Ig/ml) and therefore preventing or limiting starch breakdown. From the DPPH results it was clear that H. sobolifera, even when digested, is a potent anti-oxidant (IC50 of 134.4 Ig/ml when undigested compared to 162.9 when digested with β-glucosidase added to stomach digestive step). HPLC and TLC experiments revealed that rooperol which has previously been thought to be the compound responsible for the anti-oxidant activity in Hypoxis extracts, was absent from the traditional extract of H. sobolifera and therefore cannot be the sole compound exhibiting anti-oxidant activity; other compounds such as phenolics may be contributing. The phenolic and flavonoid content results revealed very highconcentrations of these compounds in the traditionally prepared H. sobolifera extract. These compounds may therefore play major roles in all of the biological activities observed from treatment with Hypoxis spp. The ROS results yielded interesting and promising results. Using standard or traditionally prepared H. sobolifera extracts, activation of differentiated U937 cells with PMA was greatly enhanced by cotreatment with the extracts, while extracts on their own did not cause significant activation. Future studies should investigate this property of the extracts as a promising immune boosterThe HPLC results showed that hypoxoside was undetectable in the hot water traditional extract and the TLC anti-oxidant experiment proved that rooperol is not present in the hot water traditional extract after treatment with β-glucosidase. This indicates that neither one of the Hypoxis compounds previously believed to be responsible for the biological activities observed are present in the extract when prepared the traditional way. Therefore, the biological activities observed in this study can be attributed to other phytochemical compounds.
- Full Text:
- Date Issued: 2013
- Authors: Van Rooyen, Anzel
- Date: 2013
- Subjects: Potatoes -- Therapeutic use , Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10344 , http://hdl.handle.net/10948/d1020058
- Description: In South Africa part of the cultural and religious beliefs of the African people is the use of traditional remedies to treat diseases. These remedies are obtained from medicinal plants (Steenkamp, 2003). One of the most frequently traded plants in the Eastern Cape is Hypoxis, commonly known as Afrika patat, or African potato. South African traditional healers instruct patients to brew the fresh Hypoxis corm as a tea and then ingest it (Steenkamp, 2006a). This prompted an investigation into the digestive stability of a traditionally prepared Hypoxis extract. The H. sobolifera extracts were digested using a simulated gastric/small intestinal digestion and their biological activity determined. The hot water H. sobolifera extract before digestion only showed cytotoxic activity against cancer cell lines at very high concentrations which are not likely to be achieved under normal ingestion circumstances. In Chang liver cells on the other hand, chronic exposure to the hot water H. sobolifera extract increased glucose uptake in amounts similar to that of metformin. On the negative side, the glucose utilization stimulation was lost due to the simulated digestion process. The significant inhibition of AGEs by hot water H. sobolifera extract (IC50 of 6.3 Ig/ml) is a very encouraging result as treatment in the management of diabetes. This activity was only slightly reduced by the in vitro digestion process. Also observed was enzyme inhibition activity by traditionally prepared H. sobolifera, with ∝-amylase being inhibited (IC50 of approximately 250 Ig/ml) and therefore preventing or limiting starch breakdown. From the DPPH results it was clear that H. sobolifera, even when digested, is a potent anti-oxidant (IC50 of 134.4 Ig/ml when undigested compared to 162.9 when digested with β-glucosidase added to stomach digestive step). HPLC and TLC experiments revealed that rooperol which has previously been thought to be the compound responsible for the anti-oxidant activity in Hypoxis extracts, was absent from the traditional extract of H. sobolifera and therefore cannot be the sole compound exhibiting anti-oxidant activity; other compounds such as phenolics may be contributing. The phenolic and flavonoid content results revealed very highconcentrations of these compounds in the traditionally prepared H. sobolifera extract. These compounds may therefore play major roles in all of the biological activities observed from treatment with Hypoxis spp. The ROS results yielded interesting and promising results. Using standard or traditionally prepared H. sobolifera extracts, activation of differentiated U937 cells with PMA was greatly enhanced by cotreatment with the extracts, while extracts on their own did not cause significant activation. Future studies should investigate this property of the extracts as a promising immune boosterThe HPLC results showed that hypoxoside was undetectable in the hot water traditional extract and the TLC anti-oxidant experiment proved that rooperol is not present in the hot water traditional extract after treatment with β-glucosidase. This indicates that neither one of the Hypoxis compounds previously believed to be responsible for the biological activities observed are present in the extract when prepared the traditional way. Therefore, the biological activities observed in this study can be attributed to other phytochemical compounds.
- Full Text:
- Date Issued: 2013
The effect of diet and age-at-weaning on growth and survival of clownfish Amphiprion percula (Pisces : Pomacentridae)
- Authors: Gordon, A. K. (Andrew K.)
- Date: 1999
- Subjects: Anemonefishes , Pomacentridae , Fishes -- Growth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5270 , http://hdl.handle.net/10962/d1005114 , Anemonefishes , Pomacentridae , Fishes -- Growth
- Description: The aim of this study was to improve the rearing of common clownfish Amphiprion percula, by weaning juveniles from a live feed to a formulated feed as early as possible, while still maintaining good growth and survival. The growth response of A. percula to a formulated dry feed was initially investigated. There was no difference in growth rate of juveniles fed a formulated feed, and the formulated feed supplemented with either Artemia or a Donax serra / Penaeus indicus combination. Amphiprion percula readily consumed the formulated feed, and the fishmeal/casein combination appeared an acceptable protein source. As the amount of protein included in a diet can have a profound effect on growth, the optimal dietary protein level for juvenile A. percula was investigated by feeding semipurified diets containing graded levels of protein, ranging from 40-65%. There was no difference in the growth rates of juveniles fed the various diets, however all diets promoted good growth with an average weight gain of 419%, and thus for the purposes of this study the diet formulation was deemed adequate. The histological study of the digestive system of larval A. percula revealed that the alimentary canal was advanced at hatching and that larvae start exogenous feeding immediately. Three days after hatch (DAH) the yolk sac is completely absorbed. In the hind-gut epithelium of 5-day-old larvae small supranuclear inclusion vacuoles appear, suggesting pinocytotic digestion, and by 7 DAH gastric glands are established in the epithelium of the stomach. Nine DAH supranuclear inclusion vacuoles appear in the epithelium of the mid-gut, indicating extracellular digestion and absorption across the lumen. As pinocytotic digestion of protein is less efficient than extracellular digestion, especially in the case of formulated feeds, it was hypothesised that the digestive system of A. percula could only effectively digest formulated feeds 9 DAH onwards. The two weaning experiments designed to test this hypothesis revealed that A. percula was able to utilise the formulated feed, without reduction in survival, from 7 DAH onwards. However, in terms of growth, the optimal time to wean juveniles from the live feed to the formulated dry feed was between 15 to 20 DAH. As A. percula accept a formulated feed and can benefit nutritionally from it, the dependence of larvae and juveniles on live feed can be reduced. This study has shown that the rearing of A. percula can been simplified and improved by weaning from 7 DAH with no reduction in survival, and from 15 to 20 DAH with no reduction in growth.
- Full Text:
- Date Issued: 1999
- Authors: Gordon, A. K. (Andrew K.)
- Date: 1999
- Subjects: Anemonefishes , Pomacentridae , Fishes -- Growth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5270 , http://hdl.handle.net/10962/d1005114 , Anemonefishes , Pomacentridae , Fishes -- Growth
- Description: The aim of this study was to improve the rearing of common clownfish Amphiprion percula, by weaning juveniles from a live feed to a formulated feed as early as possible, while still maintaining good growth and survival. The growth response of A. percula to a formulated dry feed was initially investigated. There was no difference in growth rate of juveniles fed a formulated feed, and the formulated feed supplemented with either Artemia or a Donax serra / Penaeus indicus combination. Amphiprion percula readily consumed the formulated feed, and the fishmeal/casein combination appeared an acceptable protein source. As the amount of protein included in a diet can have a profound effect on growth, the optimal dietary protein level for juvenile A. percula was investigated by feeding semipurified diets containing graded levels of protein, ranging from 40-65%. There was no difference in the growth rates of juveniles fed the various diets, however all diets promoted good growth with an average weight gain of 419%, and thus for the purposes of this study the diet formulation was deemed adequate. The histological study of the digestive system of larval A. percula revealed that the alimentary canal was advanced at hatching and that larvae start exogenous feeding immediately. Three days after hatch (DAH) the yolk sac is completely absorbed. In the hind-gut epithelium of 5-day-old larvae small supranuclear inclusion vacuoles appear, suggesting pinocytotic digestion, and by 7 DAH gastric glands are established in the epithelium of the stomach. Nine DAH supranuclear inclusion vacuoles appear in the epithelium of the mid-gut, indicating extracellular digestion and absorption across the lumen. As pinocytotic digestion of protein is less efficient than extracellular digestion, especially in the case of formulated feeds, it was hypothesised that the digestive system of A. percula could only effectively digest formulated feeds 9 DAH onwards. The two weaning experiments designed to test this hypothesis revealed that A. percula was able to utilise the formulated feed, without reduction in survival, from 7 DAH onwards. However, in terms of growth, the optimal time to wean juveniles from the live feed to the formulated dry feed was between 15 to 20 DAH. As A. percula accept a formulated feed and can benefit nutritionally from it, the dependence of larvae and juveniles on live feed can be reduced. This study has shown that the rearing of A. percula can been simplified and improved by weaning from 7 DAH with no reduction in survival, and from 15 to 20 DAH with no reduction in growth.
- Full Text:
- Date Issued: 1999