Evaluation of flocculating potentials and charecterization of bioflocculants produced by three bacterial isolates from Algoa Bay, South Africa
- Authors: Okaiyeto, Kunle
- Date: 2016
- Subjects: Flocculation Water -- Purification -- Flocculation Water quality management
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2633 , vital:27947
- Description: Flocculation has been widely adopted as one of the most effective methods to remove colloidal particles in water or wastewater treatment. Synthetic flocculants are conventionally used because of their high flocculating efficiency and cost-effectiveness. However, they have been reported to have hazardous properties and implicated in some serious health problems including senile dementia and neuro-toxicity, as well as being recalcitrant in the environment. Consequently, efforts are being geared away from the use of synthetic flocculants in water and wastewater treatment. Hence, the need for safe and eco-friendly flocculants has become imperative. Compared with synthetic flocculants, bioflocculants have special advantages such as safety, biodegradability and harmlessness to the environment and humans; attributes which make them potential alternatives in water treatment, downstream as well as fermentation processes. In the current study, the potentials of bacterial isolates recovered from Algoa Bay in the Eastern Cape Province of South Africa for bioflocculant production were investigated. The bacterial isolates were identified by polymerase chain reaction (PCR) as belonging to the Bacillus genus. The analysis of 16S ribosomal deoxyribonucleic acid (rDNA) nucleotide sequence of isolate M72 showed 99 percent similarity to Bacillus toyonensis strain BCT-7112 and was deposited in the GenBank as Bacillus toyonensis strain AEMREG6 with accession number KP406731. Likewise, the 16S rDNA nucleotide sequences of isolates M69 and M67 showed 98 percent sequence similarity to Bacillus licheniformis strain W7 and Bacillus algicola strain QD43 respectively; and M67 isolate was subsequently deposited in the GenBank as Bacillus sp. AEMREG7 with accession number KF933697.1. The results of the nutritional requirements and fermentation conditions revealed that optimum inoculum size for REG-6 production was 4 percent (v/v), while 5 percent (v/v) and 3 percent (v/v) were most favourable for MBF-W7 and MBF-UFH production respectively. Glucose was the best carbon source for the production of bioflocculants (REG-6 and MBF-UFH) by Bacillus toyonensis AEMREG6 and Bacillus sp. AEMREG7 respectively, while maltose supported optimum bioflocculant (MBF-W7) production by Bacillus specie. Inorganic nitrogen (NH4NO3) was the favoured nitrogen source for both REG-6 and MBF-W7 production, while mixed nitrogen sources [yeast extract + urea + (NH4)2SO4] supported the maximum production of MBF-UFH. The initial medium pH for REG-6 was 5, while MBF-W7 and MBF-UFH were both maximally produced at the initial pH of 6. After a 96 h cultivation period under optimal culture conditions, 3.2 g of purified REG-6 with a maximum flocculating activity of 77 percent was recovered from 1 L fermented broth of Bacillus toyonensis AEMREG6. Yields of 3.8 g and 1.6 g pure bioflocculants with the respective highest flocculating activities of 94.9 percent and 83.2 percent were also obtained from 1 L, 72 h-fermented broths of Bacillus licheniformis and Bacillus sp. AEMREG7 respectively. Furthermore, all the three bioflocculants (REG-6, MBF-W7 and MBF-UFH), displayed thermal stability within the temperature range of 50 to 100 oC, with strong flocculating activities of over 80 percent against kaolin suspension over a wide range of pH range (3–11) and relatively low dosage requirements of 0.1-03 mg/ml in the presence of divalent cations in the treatment of kaolin clay suspension and Thyme River waters. Chemical composition analyses of the bioflocculants showed them to be glycoproteins with a predominantly polysaccharide backbones as shown by the following carbohydrate/protein (w/w) ratios: 77.8 percent:11.5 percent (REG-6); 73.7 percent:6.2 percent (MBF-W7) and 76 percent:14 percent (MBF-UFH).
- Full Text:
- Date Issued: 2016
- Authors: Okaiyeto, Kunle
- Date: 2016
- Subjects: Flocculation Water -- Purification -- Flocculation Water quality management
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2633 , vital:27947
- Description: Flocculation has been widely adopted as one of the most effective methods to remove colloidal particles in water or wastewater treatment. Synthetic flocculants are conventionally used because of their high flocculating efficiency and cost-effectiveness. However, they have been reported to have hazardous properties and implicated in some serious health problems including senile dementia and neuro-toxicity, as well as being recalcitrant in the environment. Consequently, efforts are being geared away from the use of synthetic flocculants in water and wastewater treatment. Hence, the need for safe and eco-friendly flocculants has become imperative. Compared with synthetic flocculants, bioflocculants have special advantages such as safety, biodegradability and harmlessness to the environment and humans; attributes which make them potential alternatives in water treatment, downstream as well as fermentation processes. In the current study, the potentials of bacterial isolates recovered from Algoa Bay in the Eastern Cape Province of South Africa for bioflocculant production were investigated. The bacterial isolates were identified by polymerase chain reaction (PCR) as belonging to the Bacillus genus. The analysis of 16S ribosomal deoxyribonucleic acid (rDNA) nucleotide sequence of isolate M72 showed 99 percent similarity to Bacillus toyonensis strain BCT-7112 and was deposited in the GenBank as Bacillus toyonensis strain AEMREG6 with accession number KP406731. Likewise, the 16S rDNA nucleotide sequences of isolates M69 and M67 showed 98 percent sequence similarity to Bacillus licheniformis strain W7 and Bacillus algicola strain QD43 respectively; and M67 isolate was subsequently deposited in the GenBank as Bacillus sp. AEMREG7 with accession number KF933697.1. The results of the nutritional requirements and fermentation conditions revealed that optimum inoculum size for REG-6 production was 4 percent (v/v), while 5 percent (v/v) and 3 percent (v/v) were most favourable for MBF-W7 and MBF-UFH production respectively. Glucose was the best carbon source for the production of bioflocculants (REG-6 and MBF-UFH) by Bacillus toyonensis AEMREG6 and Bacillus sp. AEMREG7 respectively, while maltose supported optimum bioflocculant (MBF-W7) production by Bacillus specie. Inorganic nitrogen (NH4NO3) was the favoured nitrogen source for both REG-6 and MBF-W7 production, while mixed nitrogen sources [yeast extract + urea + (NH4)2SO4] supported the maximum production of MBF-UFH. The initial medium pH for REG-6 was 5, while MBF-W7 and MBF-UFH were both maximally produced at the initial pH of 6. After a 96 h cultivation period under optimal culture conditions, 3.2 g of purified REG-6 with a maximum flocculating activity of 77 percent was recovered from 1 L fermented broth of Bacillus toyonensis AEMREG6. Yields of 3.8 g and 1.6 g pure bioflocculants with the respective highest flocculating activities of 94.9 percent and 83.2 percent were also obtained from 1 L, 72 h-fermented broths of Bacillus licheniformis and Bacillus sp. AEMREG7 respectively. Furthermore, all the three bioflocculants (REG-6, MBF-W7 and MBF-UFH), displayed thermal stability within the temperature range of 50 to 100 oC, with strong flocculating activities of over 80 percent against kaolin suspension over a wide range of pH range (3–11) and relatively low dosage requirements of 0.1-03 mg/ml in the presence of divalent cations in the treatment of kaolin clay suspension and Thyme River waters. Chemical composition analyses of the bioflocculants showed them to be glycoproteins with a predominantly polysaccharide backbones as shown by the following carbohydrate/protein (w/w) ratios: 77.8 percent:11.5 percent (REG-6); 73.7 percent:6.2 percent (MBF-W7) and 76 percent:14 percent (MBF-UFH).
- Full Text:
- Date Issued: 2016
Exploration of Nahoon beach milieu for lignocellulose degrading bacteria and optimizing fermentation conditions for holocellulase production by selected strains
- Authors: Fatokun, Evelyn
- Date: 2016
- Subjects: Lignocellulose Lignocellulose -- Biodegradation Water -- Purification -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/1529 , vital:27413
- Description: A significant trend in the modern day industrial biotechnology is the utilization and application of renewable resources, and ecofriendly approach to industrial processes and waste management. As a consequence thereof, the biotechnology of holocellulases: cellulase and xylanase and, enzymatic hydrolysis of renewable and abundant lignocellulosic biomass to energy and value added products are rapidly increasing; hence, cost effective enzyme system is imperative. In that context, exploration of microbiota for strains and enzymes with novel industrial properties is vital for efficient and commercially viable enzyme biotechnology. Consequent on the complex characteristics of high salinity, variable pressure, temperature and nutritional conditions, bacterial strains from the marine environment are equipped with enzyme machinery of industrial importance for adaptation and survival. In this study, bacterial strains were isolated form Nahoon beach and optimized for holocellulase production. Three isolates selected for lignocellulolytic potential were identified by 16S ribosomal deoxyribonucleic acid (rDNA) sequence analysis. Isolate FS1k had 98 percent similarity with Streptomyces albidoflavus strain AIH12, was designated as Streptomyces albidoflavus strain SAMRC-UFH5 and deposited in the GenBank with accession number KU171373. Similarly, isolates CS14b and CS22d with respective percentage similarity of 98 and 99 (percent) with Bacillus cereus strains and Streptomyces sp. strain WMMB251 were named Bacillus cereus strain SAMRC-UFH9 and Streptomyces sp. strain SAMRC-UFH6; and were deposited in the GenBank with accession number KX524510 and KU171374 respectively. Optimal pH, temperature and agitation speed for cellulase production by S. albidoflavus strain SAMRC-UFH5, and B. cereus strain SAMRC-UFH9 were 6 and 7; 40 and 30 (°C); and 100 and 150 (rpm) respectively; while xylanase production was optimal at pH, temperature and agitation speed of 8 and 7; 40 and 30 (°C); and 150 and 50 (rpm) respectively. Maximum cellulase activity of 0.26 and 0.061(U/mL) by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 were attained at 60 h respectively, while maximal xylanase activity of 18.54 and 16.6 (U/mL) was produced by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 at 48 h and 60 h respectively. Furthermore, xylanase production by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 was maximally induced by wheat straw and xylan respectively, while cellulase production was best induced by mannose and carboxymethyl cellulose respectively. On the other hand, cellulase and xylanase production by Streptomyces sp. strain SAMRC-UFH6 was optimal at pH, temperature and agitation speed of 7 and 8, 40 °C and 100 rpm, respectively. Highest production of cellulase and xylanase was attained at 84 and 60 h with respective activity of 0.065 and 6.34 (U/mL). In addition, cellulase and xylanase production by the strain was best induced by beechwood xylan. Moreover, xylanase produced by Streptomyces sp. strain SAMRC-UFH6 at optimal conditions was characterized by optimal pH and temperature of 8 and 80-90 °C respectively; retaining over 70 percent activity at pH 5-10 after 1 h and 60 percent of initial activity at 90 °C after 90 min of incubation. In all, optimization improved cellulase and xylanase production yields, being 40 and 95.5, 10.89 and 72.17, and 10 and 115- fold increase by S. albidoflavus strain SAMRC-UFH5, B. cereus strain SAMRC-UFH9 and Streptomyces sp. SAMRC-UFH6 respectively. The results of this study suggest that the marine bacterial strains are resource for holocellulase with industrial applications.
- Full Text:
- Date Issued: 2016
- Authors: Fatokun, Evelyn
- Date: 2016
- Subjects: Lignocellulose Lignocellulose -- Biodegradation Water -- Purification -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/1529 , vital:27413
- Description: A significant trend in the modern day industrial biotechnology is the utilization and application of renewable resources, and ecofriendly approach to industrial processes and waste management. As a consequence thereof, the biotechnology of holocellulases: cellulase and xylanase and, enzymatic hydrolysis of renewable and abundant lignocellulosic biomass to energy and value added products are rapidly increasing; hence, cost effective enzyme system is imperative. In that context, exploration of microbiota for strains and enzymes with novel industrial properties is vital for efficient and commercially viable enzyme biotechnology. Consequent on the complex characteristics of high salinity, variable pressure, temperature and nutritional conditions, bacterial strains from the marine environment are equipped with enzyme machinery of industrial importance for adaptation and survival. In this study, bacterial strains were isolated form Nahoon beach and optimized for holocellulase production. Three isolates selected for lignocellulolytic potential were identified by 16S ribosomal deoxyribonucleic acid (rDNA) sequence analysis. Isolate FS1k had 98 percent similarity with Streptomyces albidoflavus strain AIH12, was designated as Streptomyces albidoflavus strain SAMRC-UFH5 and deposited in the GenBank with accession number KU171373. Similarly, isolates CS14b and CS22d with respective percentage similarity of 98 and 99 (percent) with Bacillus cereus strains and Streptomyces sp. strain WMMB251 were named Bacillus cereus strain SAMRC-UFH9 and Streptomyces sp. strain SAMRC-UFH6; and were deposited in the GenBank with accession number KX524510 and KU171374 respectively. Optimal pH, temperature and agitation speed for cellulase production by S. albidoflavus strain SAMRC-UFH5, and B. cereus strain SAMRC-UFH9 were 6 and 7; 40 and 30 (°C); and 100 and 150 (rpm) respectively; while xylanase production was optimal at pH, temperature and agitation speed of 8 and 7; 40 and 30 (°C); and 150 and 50 (rpm) respectively. Maximum cellulase activity of 0.26 and 0.061(U/mL) by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 were attained at 60 h respectively, while maximal xylanase activity of 18.54 and 16.6 (U/mL) was produced by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 at 48 h and 60 h respectively. Furthermore, xylanase production by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 was maximally induced by wheat straw and xylan respectively, while cellulase production was best induced by mannose and carboxymethyl cellulose respectively. On the other hand, cellulase and xylanase production by Streptomyces sp. strain SAMRC-UFH6 was optimal at pH, temperature and agitation speed of 7 and 8, 40 °C and 100 rpm, respectively. Highest production of cellulase and xylanase was attained at 84 and 60 h with respective activity of 0.065 and 6.34 (U/mL). In addition, cellulase and xylanase production by the strain was best induced by beechwood xylan. Moreover, xylanase produced by Streptomyces sp. strain SAMRC-UFH6 at optimal conditions was characterized by optimal pH and temperature of 8 and 80-90 °C respectively; retaining over 70 percent activity at pH 5-10 after 1 h and 60 percent of initial activity at 90 °C after 90 min of incubation. In all, optimization improved cellulase and xylanase production yields, being 40 and 95.5, 10.89 and 72.17, and 10 and 115- fold increase by S. albidoflavus strain SAMRC-UFH5, B. cereus strain SAMRC-UFH9 and Streptomyces sp. SAMRC-UFH6 respectively. The results of this study suggest that the marine bacterial strains are resource for holocellulase with industrial applications.
- Full Text:
- Date Issued: 2016
Evaluation of the incidence of enteric viruses, Vibrio species and Escherichia coli pathotypes in effluents of two wastewater treatment plants located in Keiskammahoek and Stutterheim in the Eastern Cape Province of South Africa
- Authors: Adefisoye, Martins Ajibade
- Date: 2016
- Subjects: Escherichia coli -- South Africa -- Eastern Cape Water -- Purification -- South Africa -- Eastern Cape Effluent quality -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/3165 , vital:28328
- Description: South Africa is currently experiencing water shortage crisis, a challenge that has been attributed not only to the scarcity of freshwater, but also to fast degrading water quality. Factors such as rapid urbanisation, population and economic growth, climate change as well as poor operational and maintenance of many of the exisiting water/wastewater treatment facilities have been acknowledged as important contributors to degrading water quality in the country. Untreated or inadequately treated discharged wastewater effluents constitute point source pollution to many freshwater environments in South Africa. Hence, it becomes imperative to evaluate wastewater discharges in other to protect the scarce freshwater resource, the environment and public health. Over a twelve-month sampling period (September 2012 to August 2013), we assessed the bacteriological, virological and physicochemical qualities of the discharged final effluents of two wastewater treatment facilities in the Eastern Cape Province of South Africa. For the physicochemical assessment, a total of 144 final effluent samples were collected from both the final effluent tanks (FE) and the discharge points (DP) of the treatment facilities. Physicochemical parameters including pH, temperature, turbidity, total dissolved solids (TDS), dissolved oxygen (DO), electrical conductivity (EC) and free chlorine concentration were determined on site while biological oxygen demand (BOD), nitrate (NO3-), nitrite (NO2-), phosphate (PO4-) and chemical oxygen demand (COD) were determined in the laboratory. The bacteriological analysis of the samples was done using standard membrane filtration (MF) technique. Bacterial group assessed included: faecal indicator bacteria (faecal coliforms and E. coli) and Vibrio species, while the antibiotic susceptibility profiles of selected E. coli and Vibrio species isolates against some selected antibiotics commonly used in human therapy and veterinary medicine were determind using the standard agar-disc diffusion method. The occurrence and concentrations of human enteric viruses including: human adenovirus (HAdV), hepatitis A virus (HAV) and rotavirus (RoV) in the samples were determined by TaqMan-based real-time polymerase chain reaction (qPCR) following concentration by adsorption-elution method. The physicochemical characteristics of the samples ranged as follows: pH (6.5 – 7.6), TDS (95 – 171 mg/L), EC (134 – 267 μS/cm), temperature (12 – 27 °C), turbidity (1.5 – 65.7 mg/L), free chlorine (0.08 – 0.72 mg/L), DO (2.06 – 9.81 mg/L), BOD (0.13 – 9.81 mg/L), NO3- (0 – 21.5 mg/L), NO2- (0 – 0.72 mg/L), PO4- (0 – 18.3 mg/L) and COD (27 – 680 mg/L). Some of the characteristic such as pH, TDS, EC, temperature, nitrite and DO (on most instances) complied with recommended guidelines. Other characteristics, however, including turbidity, BOD, nitrate, phosphate and COD fell short of the recommended guidelines. All the 48 samples analysed for bacteriological qualities tested positive for the presence of the bacterial groups with significant (P≤0.05) seasonal variation in their densities. Faecal coliforms were detected in counts ranging from 1 CFU/100ml to 2.7 × 104 CFU/100ml. Presumptive E. coli counts ranged generally between 1 CFU/100ml – 1.4 × 105 CFU/100ml while counts of presumptive Vibrio species ranged between 4 CFU/100ml – 1.4 × 104 CFU/100ml. Molecular identification of the presumptive isolates by polymerase chain reactions PCR gave positive reaction rates of 76.2 percent (381/500) and 69.8 percent (279/400) for E.coli and Vibrio species respectively. The antibiotic susceptibility profiling of 205 PCR-confirmed Vibiro isolates against 18 commomly used antibiotics showed resistance frequencies ranging from 0.5 percent (imipenem) to 96.1 percent (penicillin G) at recommended breakpoint concentrations. Eighty-one percent (166/205) of the Vibrio isolates showed multidrug resistance (resistance to 3 or more antibiotics) with the most common multiple antibiotic resistance phenotype (MARP) being AP-T-TM-SMX-PG-NI-PB, occurring in 8 isolates.
- Full Text:
- Date Issued: 2016
- Authors: Adefisoye, Martins Ajibade
- Date: 2016
- Subjects: Escherichia coli -- South Africa -- Eastern Cape Water -- Purification -- South Africa -- Eastern Cape Effluent quality -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/3165 , vital:28328
- Description: South Africa is currently experiencing water shortage crisis, a challenge that has been attributed not only to the scarcity of freshwater, but also to fast degrading water quality. Factors such as rapid urbanisation, population and economic growth, climate change as well as poor operational and maintenance of many of the exisiting water/wastewater treatment facilities have been acknowledged as important contributors to degrading water quality in the country. Untreated or inadequately treated discharged wastewater effluents constitute point source pollution to many freshwater environments in South Africa. Hence, it becomes imperative to evaluate wastewater discharges in other to protect the scarce freshwater resource, the environment and public health. Over a twelve-month sampling period (September 2012 to August 2013), we assessed the bacteriological, virological and physicochemical qualities of the discharged final effluents of two wastewater treatment facilities in the Eastern Cape Province of South Africa. For the physicochemical assessment, a total of 144 final effluent samples were collected from both the final effluent tanks (FE) and the discharge points (DP) of the treatment facilities. Physicochemical parameters including pH, temperature, turbidity, total dissolved solids (TDS), dissolved oxygen (DO), electrical conductivity (EC) and free chlorine concentration were determined on site while biological oxygen demand (BOD), nitrate (NO3-), nitrite (NO2-), phosphate (PO4-) and chemical oxygen demand (COD) were determined in the laboratory. The bacteriological analysis of the samples was done using standard membrane filtration (MF) technique. Bacterial group assessed included: faecal indicator bacteria (faecal coliforms and E. coli) and Vibrio species, while the antibiotic susceptibility profiles of selected E. coli and Vibrio species isolates against some selected antibiotics commonly used in human therapy and veterinary medicine were determind using the standard agar-disc diffusion method. The occurrence and concentrations of human enteric viruses including: human adenovirus (HAdV), hepatitis A virus (HAV) and rotavirus (RoV) in the samples were determined by TaqMan-based real-time polymerase chain reaction (qPCR) following concentration by adsorption-elution method. The physicochemical characteristics of the samples ranged as follows: pH (6.5 – 7.6), TDS (95 – 171 mg/L), EC (134 – 267 μS/cm), temperature (12 – 27 °C), turbidity (1.5 – 65.7 mg/L), free chlorine (0.08 – 0.72 mg/L), DO (2.06 – 9.81 mg/L), BOD (0.13 – 9.81 mg/L), NO3- (0 – 21.5 mg/L), NO2- (0 – 0.72 mg/L), PO4- (0 – 18.3 mg/L) and COD (27 – 680 mg/L). Some of the characteristic such as pH, TDS, EC, temperature, nitrite and DO (on most instances) complied with recommended guidelines. Other characteristics, however, including turbidity, BOD, nitrate, phosphate and COD fell short of the recommended guidelines. All the 48 samples analysed for bacteriological qualities tested positive for the presence of the bacterial groups with significant (P≤0.05) seasonal variation in their densities. Faecal coliforms were detected in counts ranging from 1 CFU/100ml to 2.7 × 104 CFU/100ml. Presumptive E. coli counts ranged generally between 1 CFU/100ml – 1.4 × 105 CFU/100ml while counts of presumptive Vibrio species ranged between 4 CFU/100ml – 1.4 × 104 CFU/100ml. Molecular identification of the presumptive isolates by polymerase chain reactions PCR gave positive reaction rates of 76.2 percent (381/500) and 69.8 percent (279/400) for E.coli and Vibrio species respectively. The antibiotic susceptibility profiling of 205 PCR-confirmed Vibiro isolates against 18 commomly used antibiotics showed resistance frequencies ranging from 0.5 percent (imipenem) to 96.1 percent (penicillin G) at recommended breakpoint concentrations. Eighty-one percent (166/205) of the Vibrio isolates showed multidrug resistance (resistance to 3 or more antibiotics) with the most common multiple antibiotic resistance phenotype (MARP) being AP-T-TM-SMX-PG-NI-PB, occurring in 8 isolates.
- Full Text:
- Date Issued: 2016
Indigenous forests level of deforestation, forest dependency and factors determining willingness to participate in indigenous forest conservation: evidence from resettled farmers of Shamva, Zimbabwe
- Authors: Chivheya, Renias V
- Date: 2016
- Subjects: Forest conservation -- Zimbabwe Forests and forestry -- Economic aspects -- Zimbabwe Deforestation -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2370 , vital:27786
- Description: This study first explored the rate of forest deforestation in Shamva resettlement areas. It then identified and estimated the extent to which these resettled farmers depend on forest for their livelihoods. Evaluation of farmer perceptions on management issues and willingness to participate in indigenous forest conservation and the socio-economic and institutional factors which affect their willingness to participate were also done. Finally the study sought to identify incentives for forests conservation. The study was conducted in Shamva district in Mashonaland Central province. And the respondents were stratified into three groups: A1, A2 and Old resettlement models. The three models differ on how they were implemented and supported which might render them to have different deforestation rates, livelihood strategies and forest dependency. A total of 247 respondents were surveyed, consisting of 98 A1 farmers, 50 A2 farmers and 99 Old resettled farmers. The data was collected using GIS and remote sensing, structured questionnaire interviews and direct observation. The data was analysed using descriptive analysis, KAP analytic framework and binary logistic regression analysis. The land cover/changes results revealed that both deforestation and afforestation are taking place in Shamva resettlement. Woodland and bushland were decreasing, croplands were also decreasing. However woodland dense and grasslands were increasing. Deforestation was found to be as a result of the resettled farmers’ livelihood strategies which were found to be diverse and agriculture being dominant in all models. All the farmers depended on the forest but at varying levels of 19 percent for Old and 14 percent forA1 and 0.02 percent for A2 resettle farmers. 84 percent of the interviewed farmers however, indicated that they are willing to conserve forest with A1 farmers being the highest followed by A2 86 percent and lastly Old resettled farmers at 76.8 percent. Results of the binary regression model revealed that the significant factors which explain willingness to participate in indigenous forest conservation are age, marital status, education, gender, institution, culture and belief, employment and household size. The highest preferred incentive was the provision of free seedlings and the lowest was out grower scheme. The study recommends that GIS and remote sensing should be used to monitor deforestation, off farm projects be encouraged, exotic and indigenous trees be promoted and forest conservation education be promoted in resettlement areas.
- Full Text:
- Date Issued: 2016
- Authors: Chivheya, Renias V
- Date: 2016
- Subjects: Forest conservation -- Zimbabwe Forests and forestry -- Economic aspects -- Zimbabwe Deforestation -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2370 , vital:27786
- Description: This study first explored the rate of forest deforestation in Shamva resettlement areas. It then identified and estimated the extent to which these resettled farmers depend on forest for their livelihoods. Evaluation of farmer perceptions on management issues and willingness to participate in indigenous forest conservation and the socio-economic and institutional factors which affect their willingness to participate were also done. Finally the study sought to identify incentives for forests conservation. The study was conducted in Shamva district in Mashonaland Central province. And the respondents were stratified into three groups: A1, A2 and Old resettlement models. The three models differ on how they were implemented and supported which might render them to have different deforestation rates, livelihood strategies and forest dependency. A total of 247 respondents were surveyed, consisting of 98 A1 farmers, 50 A2 farmers and 99 Old resettled farmers. The data was collected using GIS and remote sensing, structured questionnaire interviews and direct observation. The data was analysed using descriptive analysis, KAP analytic framework and binary logistic regression analysis. The land cover/changes results revealed that both deforestation and afforestation are taking place in Shamva resettlement. Woodland and bushland were decreasing, croplands were also decreasing. However woodland dense and grasslands were increasing. Deforestation was found to be as a result of the resettled farmers’ livelihood strategies which were found to be diverse and agriculture being dominant in all models. All the farmers depended on the forest but at varying levels of 19 percent for Old and 14 percent forA1 and 0.02 percent for A2 resettle farmers. 84 percent of the interviewed farmers however, indicated that they are willing to conserve forest with A1 farmers being the highest followed by A2 86 percent and lastly Old resettled farmers at 76.8 percent. Results of the binary regression model revealed that the significant factors which explain willingness to participate in indigenous forest conservation are age, marital status, education, gender, institution, culture and belief, employment and household size. The highest preferred incentive was the provision of free seedlings and the lowest was out grower scheme. The study recommends that GIS and remote sensing should be used to monitor deforestation, off farm projects be encouraged, exotic and indigenous trees be promoted and forest conservation education be promoted in resettlement areas.
- Full Text:
- Date Issued: 2016
Appraisal of experimental performance and modelling of an on-farm dairy milk bulk cooler: Fort Hare Dairy Trust, South Africa
- Authors: Mhundwa, Russel
- Date: 2017
- Subjects: Milk -- Cooling Milk -- Cooling -- Equipment and supplies Milk tanks -- Specifications
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/4671 , vital:28487
- Description: South Africa contributes approximately 0.5 percent to the total world milk demand and is the third largest producer of fresh cow milk in Africa after Sudan and Kenya. In comparison to any other enterprise, the cost of milk production is influenced by numerous factors, that in turn affect the profitability of the farm enterprise; however one of such factors is high electricity cost. In this regard, there is need for efficient operation of the milk processing plant at all stages and at the same time maximising on product quality and minimising on the cost of production including energy. At the dairy farm, milk handling mainly commences as the milk leaves the cow udder at 35°C–37°C and must be cooled rapidly to a storage temperature of 4°C in a bid to stop microbial activity. The cooling of the milk can be done directly by the bulk milk cooler (BMC) from 37°C to the required storage temperature of 4°C or it can be done successively through pre-cooling. The process of pre-cooling involves the use of a heat exchanger where in most instances the plate heat exchanger (PHE) is used as the pre-cooler (PC) thereby leading to energy savings in a dairy facility. Cooling of milk involves significant amount of energy and it could account for about 20 percent of the total energy consumed on a farm. The aim of the research was to develop mathematical models that could be used to predict the electrical energy performance and capture the cooling saving of an on-farm direct expansion bulk milk cooler (DXBMC) during the milk cooling process. Accordingly, data acquisition system (DAS) was designed and built to accurately measure the power consumption of the BMC, temperature of raw milk, room temperature, temperature of cold water, relative humidity and ambient temperature. The volume of milk produced per day was extracted from the daily records on the farm. In addition, the temperature sensors were connected to a four channel HOBO data loggers which were configured to log at every five-minutes interval. The results were analysed and the mathematical models were developed using MATLAB. The statistical Toolbox in MATLAB was used to rank the predictors according to their weight of importance using the ReliefF Algorithm test. The results showed that on average, the daily electrical energy consumed by the BMC at the two milking times was higher during the peak period (127.82 kWh and 93.86 kWh) than the off-peak period (48.31 kWh and 43.23 kWh). On average, the electricity used for cooling of milk on the dairy farm was 17.06 kWh/m3 of milk. The average monthly electricity used per cow on the farm was 8.03 kWh/cow which translated to an average of 0.26 kWh/cow/day The average specific energy consumption of the cooling system per litre of milk cooled was 0.02 kWh/L and was almost constant throughout the whole period of monitoring. Furthermore, the BMC was able to cool 57.33 L/kWh during the off-peak period which increased by 7.7 percent to 62.13 L/kWh during the peak period. Furthermore, mathematical models represented as multiple linear regression (MLR) models were built and developed using the experimental data. The developed mathematical models had good agreement with the experimental data as evidenced by the correlation coefficients of 0.922 and 0.8995 along with 0.935 and 0.930. The ReliefF Algorithm test revealed that the volume of milk was the principal contributor to the energy consumption of the BMC for both the morning (AM) and afternoon (PM) milking period. The Relative Prediction Error (RPE) was used to evaluate the suitability of the developed models. In this light, the AM off-peak model had RPE of 18.54 percent while the PM off-peak model had 14.42 percent. In addition, the AM peak and PM peak models had RPE of 19.23 percent and 18.95 percent respectively. This suggested that the MLR models for the off-peak and peak milking periods (both AM and PM) had acceptable prediction accuracy since the RPE values were between 10 percent and 20 percent. The findings from the experimental study showed that the coefficient of performance (COP) of the AM milking period was higher (2.20) than that of the PM milking period of the BMC (1.93). Increase in the milk volume led to an increase in the COP such that the peak period with higher milk volumes recorded a high COP increase of 12.61 percent and 19.81 percent for the AM and PM milking periods respectively.
- Full Text:
- Date Issued: 2017
- Authors: Mhundwa, Russel
- Date: 2017
- Subjects: Milk -- Cooling Milk -- Cooling -- Equipment and supplies Milk tanks -- Specifications
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/4671 , vital:28487
- Description: South Africa contributes approximately 0.5 percent to the total world milk demand and is the third largest producer of fresh cow milk in Africa after Sudan and Kenya. In comparison to any other enterprise, the cost of milk production is influenced by numerous factors, that in turn affect the profitability of the farm enterprise; however one of such factors is high electricity cost. In this regard, there is need for efficient operation of the milk processing plant at all stages and at the same time maximising on product quality and minimising on the cost of production including energy. At the dairy farm, milk handling mainly commences as the milk leaves the cow udder at 35°C–37°C and must be cooled rapidly to a storage temperature of 4°C in a bid to stop microbial activity. The cooling of the milk can be done directly by the bulk milk cooler (BMC) from 37°C to the required storage temperature of 4°C or it can be done successively through pre-cooling. The process of pre-cooling involves the use of a heat exchanger where in most instances the plate heat exchanger (PHE) is used as the pre-cooler (PC) thereby leading to energy savings in a dairy facility. Cooling of milk involves significant amount of energy and it could account for about 20 percent of the total energy consumed on a farm. The aim of the research was to develop mathematical models that could be used to predict the electrical energy performance and capture the cooling saving of an on-farm direct expansion bulk milk cooler (DXBMC) during the milk cooling process. Accordingly, data acquisition system (DAS) was designed and built to accurately measure the power consumption of the BMC, temperature of raw milk, room temperature, temperature of cold water, relative humidity and ambient temperature. The volume of milk produced per day was extracted from the daily records on the farm. In addition, the temperature sensors were connected to a four channel HOBO data loggers which were configured to log at every five-minutes interval. The results were analysed and the mathematical models were developed using MATLAB. The statistical Toolbox in MATLAB was used to rank the predictors according to their weight of importance using the ReliefF Algorithm test. The results showed that on average, the daily electrical energy consumed by the BMC at the two milking times was higher during the peak period (127.82 kWh and 93.86 kWh) than the off-peak period (48.31 kWh and 43.23 kWh). On average, the electricity used for cooling of milk on the dairy farm was 17.06 kWh/m3 of milk. The average monthly electricity used per cow on the farm was 8.03 kWh/cow which translated to an average of 0.26 kWh/cow/day The average specific energy consumption of the cooling system per litre of milk cooled was 0.02 kWh/L and was almost constant throughout the whole period of monitoring. Furthermore, the BMC was able to cool 57.33 L/kWh during the off-peak period which increased by 7.7 percent to 62.13 L/kWh during the peak period. Furthermore, mathematical models represented as multiple linear regression (MLR) models were built and developed using the experimental data. The developed mathematical models had good agreement with the experimental data as evidenced by the correlation coefficients of 0.922 and 0.8995 along with 0.935 and 0.930. The ReliefF Algorithm test revealed that the volume of milk was the principal contributor to the energy consumption of the BMC for both the morning (AM) and afternoon (PM) milking period. The Relative Prediction Error (RPE) was used to evaluate the suitability of the developed models. In this light, the AM off-peak model had RPE of 18.54 percent while the PM off-peak model had 14.42 percent. In addition, the AM peak and PM peak models had RPE of 19.23 percent and 18.95 percent respectively. This suggested that the MLR models for the off-peak and peak milking periods (both AM and PM) had acceptable prediction accuracy since the RPE values were between 10 percent and 20 percent. The findings from the experimental study showed that the coefficient of performance (COP) of the AM milking period was higher (2.20) than that of the PM milking period of the BMC (1.93). Increase in the milk volume led to an increase in the COP such that the peak period with higher milk volumes recorded a high COP increase of 12.61 percent and 19.81 percent for the AM and PM milking periods respectively.
- Full Text:
- Date Issued: 2017
Effects of grazing and housing management systems on greenhouse gas emissions, blood profiles and meat quality of Nguni goats
- Authors: Tapiwa, Chikwanda Allen
- Date: 2016
- Subjects: Goats Goats -- Feeding and feeds Greenhouse gas mitigation , Grazing -- Environmental aspects
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2314 , vital:27752
- Description: The broad objective of this study was to evaluate the effects of grazing and housing management systems on greenhouse gas emissions, blood profiles and meat quality of Nguni goats. A total of 64 castrated Nguni goats were used and a housing structure was designed to accommodate the goats as well as evaluate effects of type of floor on greenhouse gases, meat quality, blood metabolites and fatty acid profiles. In the first experiment: Forty-eight castrated Nguni goats, at 6-7 months old were used for herding (H) or tethering (T) management systems and randomly allocated to pens with earth (E) or slatted (S) floors. Gas sampling was done using static chambers and analysed using a SRI 8610C gas chromatography machine. The highest CH4 fluxes were from the manure of herded goats on earth floors (HE). The highest CO2 fluxes were from manure of herded goats that were housed on slatted floors (HS): The highest N2O fluxes were from the manure of tethered goats that were sheltered on slatted floors (TS). It was concluded from the first experiment that goat manure is an important source of GHG that is influenced by grazing and floor type management systems. The second experiment was done to evaluate greenhouse gas (GHG) emission from disused (DP) vs occupied goat pens (OP) with earth (EF) or slatted (SF) floors. Eight previously occupied pens were used in this study. Sixteen goats were randomly put in the pens labelled occupied pens with earth floors (OPEF) and occupied pens with slatted floors (OPSF) resulting in four goats per OP. There were month by pen use; month by floor type; and use by floor type interaction effects (P < 0.05) on CH4 production. Floor type, use (DP vs OP) and month affected (P < 0.05) CH4 production. Manure on earth floors of occupied pens (OPEF) emitted the highest (P < 0.05) methane followed by earth floors of disused pens (DPEF). The least CH4 was emitted from DPSF. There was pen use (DP vs OP) by floor type interaction effect (P < 0.05) on CO2 emission. Floor type and pen use affected (P < 0.05) CO2 production. Manure in occupied pens with slatted floors (OPSF) produced the highest CO2 and the least CO2 was from disused pens with slatted floors (DPSF). Floor type and month influenced (P < 0.05) N2O production. It was concluded that continued use of goat pens increased GHG emissions. However, disused goat pens with manure remain an important source of GHG as they continued to emit quantifiable levels of CH4, CO2 and N2O. The third experiment was done to determine the effects of grazing and housing management systems on the concentrations of blood metabolites, activity of creatine kinase, body weight (BW), body condition score (BCS) and carcass characteristics using 48 castrated Nguni goats. Tethered goats had higher (P<0.05): urea, creatinine, total protein, globulin concentrations and more activity of CK than herded goats. On the other hand, herded goats had higher (P<0.05) plasma glucose (H: 3.39±0.020 vs T: 3.23±0.020 mmol/L), serum albumin (H: 15.30±0.147 vs T: 14.82±0.144 g/L) concentration. It was concluded that serum concentrations of all the metabolites and the activity of CK were sensitive to grazing system. Herding of goats promoted more glucose concentration and preservation of muscle protein and hence superior body weights and BCS than tethered goats. The fourth experiment was done to determine the effects of grazing and housing management systems on the activity of creatine kinase (CK) and cortisol concentration, and chevon quality. Further, the effect of muscle type [Muscularis longissimus thoracis et. Lumborum (LTL) and triceps brachii (TB)] on chevon quality was also investigated. Forty eight castrated Nguni goats aged 6- 7 months were randomly allocated to tethering (n=24) and herding (n=24) treatments. Floor type affected meat (P<0.05) pH24. Tethered goats had higher (P < 0.05) L* and CL percent than herded goats. Muscle type had a significant influence (P < 0.05) on a*, WBSF and pH. It was observed and concluded that T resulted in higher L* and more CL percent whilst SF lowered the pH24 of chevon; at the same time meat from the TB muscle was more tender, despite having a higher pH24 and more CL percent relative to LTH cuts. The fifth experiment was done to determine the effect of grazing and floor type on fatty acid composition of chevon from tethered and herded Nguni goats. Floor type had no effect on fatty acid composition. Oleic, stearic, palmitic and linoleic were the major fatty acids. Chevon from tethered goats had higher (P < 0.05) proportions of long chain polyunsaturated fatty acids (PUFAs): eicosapentaenoic, docosapentaenoic, docosahexaenoic, conjugated linoleic acid (CLA) and more total SFA, total PUFA, total Omega- 6 and total omega 3 fatty acids than herded goats. On the other hand, chevon from herded goats had more (P < 0.05) C18:1c9, C18:2t9, 12 (n-6), C20:3c11, 14, 17 (n-3) and total MUFA than tethered goats. However, there was no difference (P > 0.05) in the PUFA: SFA and n-6/n-3 fatty acid ratios between the herded and tethered goats. It was concluded that tethering promoted higher proportions of beneficial PUFAs which were more in TB than LTH muscle. The overall conclusions from the whole study were that goat manure is an important source of GHG with high CH4 being emitted from earth floors of herded goats. High CO2 and N2O are emitted from SF of herded and tethered goats, respectively. There were no major differences in meat quality between herded and tethered goats. However, herding promoted more live weight gain than tethering. On the other hand, tethering promoted more beneficial fatty acids. Therefore depending on the objective of the enterprise, smallholder farmers can safely tether or herd their goats. Further, there is need to develop technologies to harness CH4 from goat manure.
- Full Text:
- Date Issued: 2016
- Authors: Tapiwa, Chikwanda Allen
- Date: 2016
- Subjects: Goats Goats -- Feeding and feeds Greenhouse gas mitigation , Grazing -- Environmental aspects
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2314 , vital:27752
- Description: The broad objective of this study was to evaluate the effects of grazing and housing management systems on greenhouse gas emissions, blood profiles and meat quality of Nguni goats. A total of 64 castrated Nguni goats were used and a housing structure was designed to accommodate the goats as well as evaluate effects of type of floor on greenhouse gases, meat quality, blood metabolites and fatty acid profiles. In the first experiment: Forty-eight castrated Nguni goats, at 6-7 months old were used for herding (H) or tethering (T) management systems and randomly allocated to pens with earth (E) or slatted (S) floors. Gas sampling was done using static chambers and analysed using a SRI 8610C gas chromatography machine. The highest CH4 fluxes were from the manure of herded goats on earth floors (HE). The highest CO2 fluxes were from manure of herded goats that were housed on slatted floors (HS): The highest N2O fluxes were from the manure of tethered goats that were sheltered on slatted floors (TS). It was concluded from the first experiment that goat manure is an important source of GHG that is influenced by grazing and floor type management systems. The second experiment was done to evaluate greenhouse gas (GHG) emission from disused (DP) vs occupied goat pens (OP) with earth (EF) or slatted (SF) floors. Eight previously occupied pens were used in this study. Sixteen goats were randomly put in the pens labelled occupied pens with earth floors (OPEF) and occupied pens with slatted floors (OPSF) resulting in four goats per OP. There were month by pen use; month by floor type; and use by floor type interaction effects (P < 0.05) on CH4 production. Floor type, use (DP vs OP) and month affected (P < 0.05) CH4 production. Manure on earth floors of occupied pens (OPEF) emitted the highest (P < 0.05) methane followed by earth floors of disused pens (DPEF). The least CH4 was emitted from DPSF. There was pen use (DP vs OP) by floor type interaction effect (P < 0.05) on CO2 emission. Floor type and pen use affected (P < 0.05) CO2 production. Manure in occupied pens with slatted floors (OPSF) produced the highest CO2 and the least CO2 was from disused pens with slatted floors (DPSF). Floor type and month influenced (P < 0.05) N2O production. It was concluded that continued use of goat pens increased GHG emissions. However, disused goat pens with manure remain an important source of GHG as they continued to emit quantifiable levels of CH4, CO2 and N2O. The third experiment was done to determine the effects of grazing and housing management systems on the concentrations of blood metabolites, activity of creatine kinase, body weight (BW), body condition score (BCS) and carcass characteristics using 48 castrated Nguni goats. Tethered goats had higher (P<0.05): urea, creatinine, total protein, globulin concentrations and more activity of CK than herded goats. On the other hand, herded goats had higher (P<0.05) plasma glucose (H: 3.39±0.020 vs T: 3.23±0.020 mmol/L), serum albumin (H: 15.30±0.147 vs T: 14.82±0.144 g/L) concentration. It was concluded that serum concentrations of all the metabolites and the activity of CK were sensitive to grazing system. Herding of goats promoted more glucose concentration and preservation of muscle protein and hence superior body weights and BCS than tethered goats. The fourth experiment was done to determine the effects of grazing and housing management systems on the activity of creatine kinase (CK) and cortisol concentration, and chevon quality. Further, the effect of muscle type [Muscularis longissimus thoracis et. Lumborum (LTL) and triceps brachii (TB)] on chevon quality was also investigated. Forty eight castrated Nguni goats aged 6- 7 months were randomly allocated to tethering (n=24) and herding (n=24) treatments. Floor type affected meat (P<0.05) pH24. Tethered goats had higher (P < 0.05) L* and CL percent than herded goats. Muscle type had a significant influence (P < 0.05) on a*, WBSF and pH. It was observed and concluded that T resulted in higher L* and more CL percent whilst SF lowered the pH24 of chevon; at the same time meat from the TB muscle was more tender, despite having a higher pH24 and more CL percent relative to LTH cuts. The fifth experiment was done to determine the effect of grazing and floor type on fatty acid composition of chevon from tethered and herded Nguni goats. Floor type had no effect on fatty acid composition. Oleic, stearic, palmitic and linoleic were the major fatty acids. Chevon from tethered goats had higher (P < 0.05) proportions of long chain polyunsaturated fatty acids (PUFAs): eicosapentaenoic, docosapentaenoic, docosahexaenoic, conjugated linoleic acid (CLA) and more total SFA, total PUFA, total Omega- 6 and total omega 3 fatty acids than herded goats. On the other hand, chevon from herded goats had more (P < 0.05) C18:1c9, C18:2t9, 12 (n-6), C20:3c11, 14, 17 (n-3) and total MUFA than tethered goats. However, there was no difference (P > 0.05) in the PUFA: SFA and n-6/n-3 fatty acid ratios between the herded and tethered goats. It was concluded that tethering promoted higher proportions of beneficial PUFAs which were more in TB than LTH muscle. The overall conclusions from the whole study were that goat manure is an important source of GHG with high CH4 being emitted from earth floors of herded goats. High CO2 and N2O are emitted from SF of herded and tethered goats, respectively. There were no major differences in meat quality between herded and tethered goats. However, herding promoted more live weight gain than tethering. On the other hand, tethering promoted more beneficial fatty acids. Therefore depending on the objective of the enterprise, smallholder farmers can safely tether or herd their goats. Further, there is need to develop technologies to harness CH4 from goat manure.
- Full Text:
- Date Issued: 2016
Electrical power output estimation model for a conical diffuser augmented wind turbine
- Authors: Masukume, Peace-Maker
- Date: 2016
- Subjects: Wind power , Wind turbines , Renewable energy sources
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/1517 , vital:27404
- Description: Energy is integral to the quality of life of any society. However, meeting the demand for energy sustainably is the main challenge facing humanity. In general, non-renewable energy resources are used to supply the ever increasing energy demand. However, the extraction and processing of these resources is accompanied by the production of wastes which are a health hazard and impact negatively on climate change. Considering the finite nature of non-renewable sources, the environmental concerns which are associated with their usage and ensuring energy security, renewable energy sources have been brought in the energy supply chain. Wind energy is one of the renewable energy sources which has been supplying electrical energy to the ever increasing energy demand of humanity. Wind energy technology is a mature technology which over and above the bare (conventional) wind turbine technology has seen the development of duct augmented wind turbines. Ducts are used to encase wind turbine rotors to augment the power output of wind turbines especially in low wind speed areas. Though the technology has been under study for decades now, research indicates that there is no known model to estimate the power output of a diffuser augmented wind turbine. This thesis presents the development of the conical Diffuser Augmented Wind Turbine (DAWT) power output estimation model and its validation.
- Full Text:
- Date Issued: 2016
- Authors: Masukume, Peace-Maker
- Date: 2016
- Subjects: Wind power , Wind turbines , Renewable energy sources
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/1517 , vital:27404
- Description: Energy is integral to the quality of life of any society. However, meeting the demand for energy sustainably is the main challenge facing humanity. In general, non-renewable energy resources are used to supply the ever increasing energy demand. However, the extraction and processing of these resources is accompanied by the production of wastes which are a health hazard and impact negatively on climate change. Considering the finite nature of non-renewable sources, the environmental concerns which are associated with their usage and ensuring energy security, renewable energy sources have been brought in the energy supply chain. Wind energy is one of the renewable energy sources which has been supplying electrical energy to the ever increasing energy demand of humanity. Wind energy technology is a mature technology which over and above the bare (conventional) wind turbine technology has seen the development of duct augmented wind turbines. Ducts are used to encase wind turbine rotors to augment the power output of wind turbines especially in low wind speed areas. Though the technology has been under study for decades now, research indicates that there is no known model to estimate the power output of a diffuser augmented wind turbine. This thesis presents the development of the conical Diffuser Augmented Wind Turbine (DAWT) power output estimation model and its validation.
- Full Text:
- Date Issued: 2016
Nutritional value and cultivation requirements of Cleome Gynandra: a wild vegetable growing in the Eastern Cape Province, South Africa
- Sowunmi, Linda Ifeanyichukwu
- Authors: Sowunmi, Linda Ifeanyichukwu
- Date: 2015
- Subjects: Ethnobotany -- South Africa -- Eastern Cape Vegetables -- South Africa -- Eastern Cape Nutrition -- South Africa -- Evaluation
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2600 , vital:27907
- Description: South Africa has wide ranges of plants among which are leafy vegetables growing in the wild. These wild vegetables have been reported to have high nutritive and medicinal potentials. Yet, there is still high prevalence of malnutrition and micronutrients deficiencies among the low income bracket of the population. Effective utilization of wild vegetables has been proposed as part of the solutions to address the problem of dietary deficiencies among the populace. Their importance is mainly as relish to accompany and complement starch based diets. They are also known to serve as supplements for food which have the potential to improve the health status of its consumers in many rural communities. Cleome gynandra L. (Capparaceae) is one of the underutilized species mentioned during asurvey conducted in Nkonkobe municipality of the Eastern Cape Province, South Africa. The plant is an erect annual herb with alternate, palmately compound leaves and its petals are white, pink or lilac. It grows as a weed in this part of the Province and is usually gathered from the wild for food and medicine. It is commonly found on wastes land, road sides and on grass lands. Therefore, this research work was designed to contribute to the possible domestication of this wild vegetable in order to explore the nutritive and therapeutic potentials which would broaden the food base in the Eastern Cape Province. The ultra-micromorphological features of plants have become an essential tool in proper identification and authentication of several plant species. In the light of this, the micromorphology of Cleome gynandra was examined to reveal the micro-morphological characters of the plantand to determine if micro and macro mineral elements are present using energy dispersive x-rays. The present study revealed the epidermal cells of the leaves to be asymmetric in shape with undulating cell walls having four subsidiary cells around the stomata. The leaves have anomocyctic stomata which are more distributed in the abaxial surface than the adaxial surface. The mean length and width of the guard cells in the abaxial surface are 0.09 ± 0.01 mm and 0.08 ± 0.01 mm respectively while that of adaxial surface are 0.1± 0.01 mm and 0.07 ± 0.01 mm respectively. The energy dispersive x-rays (EDXS) micro-analysis of the leaf revealed the presence of phosphorus, manganese, iron, calcium, sodium, magnesium, potassium and zinc as the major constituents of the crystal deposits present in the stomata pores and the mesophyll. C. gynandra was collected from the wild and analysed for its mineral and proximatecomposition using standard analytical methods. The plant showed high levels of sodium, iron, zinc, calcium and potassium while many other macro and micro minerals were moderately present. Amongst the proximate factors investigated, moisture content was found to be 82.1% while crude fibre and protein contents were 39.9 percent and 31.03 percent respectively. Vitamin C was also high (345.3 mg/100g). The anti-nutrients compositions revealed low concentrations of oxalate (7.4 ± 0.4) and phytate (0.6 ± 0.0) mg/100g. The study revealed high nutritive value of the species growing naturally from the wild. Interest in the phenolic compounds has greatly increased recently because these compounds have been implicated in suppressing the risk of degenerative diseases in humans. The pharmacological properties of plants may be related to their antioxidant capacities and hence there was need to investigate the antioxidant potential using aqueous, ethanolic and acetone extracts of different parts of C. gynandra. The quantities of phenols, flavonoids and flavonols were significantly higher (p < 0.05) in both aqueous and ethanol extracts of the leaf while the concentration of proanthocyanidins was higher in the aqueous stem extract compared to other plant parts. The aqueous extract of the different parts exhibited better ABTS, reducing power and NO radical scavenging abilities than ethanol extract.
- Full Text:
- Date Issued: 2015
- Authors: Sowunmi, Linda Ifeanyichukwu
- Date: 2015
- Subjects: Ethnobotany -- South Africa -- Eastern Cape Vegetables -- South Africa -- Eastern Cape Nutrition -- South Africa -- Evaluation
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2600 , vital:27907
- Description: South Africa has wide ranges of plants among which are leafy vegetables growing in the wild. These wild vegetables have been reported to have high nutritive and medicinal potentials. Yet, there is still high prevalence of malnutrition and micronutrients deficiencies among the low income bracket of the population. Effective utilization of wild vegetables has been proposed as part of the solutions to address the problem of dietary deficiencies among the populace. Their importance is mainly as relish to accompany and complement starch based diets. They are also known to serve as supplements for food which have the potential to improve the health status of its consumers in many rural communities. Cleome gynandra L. (Capparaceae) is one of the underutilized species mentioned during asurvey conducted in Nkonkobe municipality of the Eastern Cape Province, South Africa. The plant is an erect annual herb with alternate, palmately compound leaves and its petals are white, pink or lilac. It grows as a weed in this part of the Province and is usually gathered from the wild for food and medicine. It is commonly found on wastes land, road sides and on grass lands. Therefore, this research work was designed to contribute to the possible domestication of this wild vegetable in order to explore the nutritive and therapeutic potentials which would broaden the food base in the Eastern Cape Province. The ultra-micromorphological features of plants have become an essential tool in proper identification and authentication of several plant species. In the light of this, the micromorphology of Cleome gynandra was examined to reveal the micro-morphological characters of the plantand to determine if micro and macro mineral elements are present using energy dispersive x-rays. The present study revealed the epidermal cells of the leaves to be asymmetric in shape with undulating cell walls having four subsidiary cells around the stomata. The leaves have anomocyctic stomata which are more distributed in the abaxial surface than the adaxial surface. The mean length and width of the guard cells in the abaxial surface are 0.09 ± 0.01 mm and 0.08 ± 0.01 mm respectively while that of adaxial surface are 0.1± 0.01 mm and 0.07 ± 0.01 mm respectively. The energy dispersive x-rays (EDXS) micro-analysis of the leaf revealed the presence of phosphorus, manganese, iron, calcium, sodium, magnesium, potassium and zinc as the major constituents of the crystal deposits present in the stomata pores and the mesophyll. C. gynandra was collected from the wild and analysed for its mineral and proximatecomposition using standard analytical methods. The plant showed high levels of sodium, iron, zinc, calcium and potassium while many other macro and micro minerals were moderately present. Amongst the proximate factors investigated, moisture content was found to be 82.1% while crude fibre and protein contents were 39.9 percent and 31.03 percent respectively. Vitamin C was also high (345.3 mg/100g). The anti-nutrients compositions revealed low concentrations of oxalate (7.4 ± 0.4) and phytate (0.6 ± 0.0) mg/100g. The study revealed high nutritive value of the species growing naturally from the wild. Interest in the phenolic compounds has greatly increased recently because these compounds have been implicated in suppressing the risk of degenerative diseases in humans. The pharmacological properties of plants may be related to their antioxidant capacities and hence there was need to investigate the antioxidant potential using aqueous, ethanolic and acetone extracts of different parts of C. gynandra. The quantities of phenols, flavonoids and flavonols were significantly higher (p < 0.05) in both aqueous and ethanol extracts of the leaf while the concentration of proanthocyanidins was higher in the aqueous stem extract compared to other plant parts. The aqueous extract of the different parts exhibited better ABTS, reducing power and NO radical scavenging abilities than ethanol extract.
- Full Text:
- Date Issued: 2015
Effect of post-slaughter handling on physico-chemical and microbiological quality of red meat along the distribution chain in the Eastern Cape Province, South Africa
- Authors: Rani, Zikhona Theodora
- Date: 2015
- Subjects: Meat -- Microbiology Meat -- Transportation -- South Africa -- Eastern Cape Meat -- Quality -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2490 , vital:27875
- Description: The broad objective of the study was to investigate the effect of post-slaughter handling in the distribution chain on red meat quality and safety. A survey was conducted among 300 consumers and 100 meat handlers in five different municipalities (Buffalo City, Nkonkobe, Ngqushwa, Lukhanje and Amahlathi) in the Eastern Cape Province of South Africa to investigate their perceptions on meat quality and safety, together with challenges faced by meat handlers during the distribution of meat from the abattoir to retailers. The microbiological profile and physico-chemical quality of red meat at different stages of the abattoir to retail outlets in the distribution chain were also determined. Swabs (n=216) and meat samples (n=450) were collected from beef, pork and mutton carcasses during the loading process of carcasses into trucks at the abattoir, when offloading carcasses at the supply points and during marketing. Physico-chemical qualities such as colour (L* - lightness, b* - redness and a* - yellowness) and meat pH measurements were taken at each point. To determine the microbiological profiles of the carcasses, four microbiological parameters were considered: Total bacteria count (general bacteria), coliform count (related to hygiene and indicator for pathogens), Escherichia coli (Gram-negative pathogen) and Staphylococcus aureus (Gram-positive pathogen). Two types of packaging (vacuum and overwrapping) were used to determine their effect on shelf-life and microbiological quality of red meat under the normal marketing conditions over a storage duration of 15 days. The results from the study showed low awareness of consumers about the pathogenic diseases which arise from meat. A strong significant association (p ˂ 0.05) between educational status and awareness on meat safety was observed. Most of the consumers perceived that quality goes beyond safety such that 35.6 percent of the respondents indicated that they did not have a problem with consuming spoiled meat, whilst the remaining 64.4 percent indicated that they would r eject spoiled meat. Although retailers indicated that they take meat safety into consideration in their shops, 92 percent of the retailers revealed that they do not perform microbial assessment of meat in their shops. A series of loading and off-loading, temperature fluctuations, environmental temperatures and ques during offloading were reported as the major challenges during transportation of carcasses from the abattoir to the supply points. The microbial counts were significantly (p<0.05) higher in samples from the commercial abattoir than in those from the communal abattoir. Escherichia coli was the predominant microbial contaminant in the samples from both abattoirs. When following the chain, total bacterial count (TBC), coliform count (CC) and the levels of E. coli contamination increased progressively between the loading and the off-loading points (5.1 to 7.9 log10 CFU/cm2; 5.0 to 5.6 log10 CFU/cm2 and 2.7 to 3.7 log10 CFU/cm2, respectively). The storage period, meat type, distance during transportation and temperature were found to have a significant impact on the microbial levels during the distribution of carcasses. Distribution stage had a significant effect (p<0.05) on some of the physico- chemical meat quality attributes and differences in the lightness (L*) and redness (a*) values between the loading, off-loading and display points were observed. Consumers perceived retailer class as one of the factors influencing meat quality, but according to the instrumental measurements retailer class did not have a significant effect on physico-chemical meat quality. However, distance and storage duration significantly (p<0.05) affected (L*) and (a*) values in the meat during distribution chain. Vacuum and overwrapping packaging significantly affected (p<0.05) the shelf life of meat. Therefore, it was concluded that post-slaughter handling during the distribution chain affects the physico- chemical, microbiological and shelf-life of meat.
- Full Text:
- Date Issued: 2015
- Authors: Rani, Zikhona Theodora
- Date: 2015
- Subjects: Meat -- Microbiology Meat -- Transportation -- South Africa -- Eastern Cape Meat -- Quality -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2490 , vital:27875
- Description: The broad objective of the study was to investigate the effect of post-slaughter handling in the distribution chain on red meat quality and safety. A survey was conducted among 300 consumers and 100 meat handlers in five different municipalities (Buffalo City, Nkonkobe, Ngqushwa, Lukhanje and Amahlathi) in the Eastern Cape Province of South Africa to investigate their perceptions on meat quality and safety, together with challenges faced by meat handlers during the distribution of meat from the abattoir to retailers. The microbiological profile and physico-chemical quality of red meat at different stages of the abattoir to retail outlets in the distribution chain were also determined. Swabs (n=216) and meat samples (n=450) were collected from beef, pork and mutton carcasses during the loading process of carcasses into trucks at the abattoir, when offloading carcasses at the supply points and during marketing. Physico-chemical qualities such as colour (L* - lightness, b* - redness and a* - yellowness) and meat pH measurements were taken at each point. To determine the microbiological profiles of the carcasses, four microbiological parameters were considered: Total bacteria count (general bacteria), coliform count (related to hygiene and indicator for pathogens), Escherichia coli (Gram-negative pathogen) and Staphylococcus aureus (Gram-positive pathogen). Two types of packaging (vacuum and overwrapping) were used to determine their effect on shelf-life and microbiological quality of red meat under the normal marketing conditions over a storage duration of 15 days. The results from the study showed low awareness of consumers about the pathogenic diseases which arise from meat. A strong significant association (p ˂ 0.05) between educational status and awareness on meat safety was observed. Most of the consumers perceived that quality goes beyond safety such that 35.6 percent of the respondents indicated that they did not have a problem with consuming spoiled meat, whilst the remaining 64.4 percent indicated that they would r eject spoiled meat. Although retailers indicated that they take meat safety into consideration in their shops, 92 percent of the retailers revealed that they do not perform microbial assessment of meat in their shops. A series of loading and off-loading, temperature fluctuations, environmental temperatures and ques during offloading were reported as the major challenges during transportation of carcasses from the abattoir to the supply points. The microbial counts were significantly (p<0.05) higher in samples from the commercial abattoir than in those from the communal abattoir. Escherichia coli was the predominant microbial contaminant in the samples from both abattoirs. When following the chain, total bacterial count (TBC), coliform count (CC) and the levels of E. coli contamination increased progressively between the loading and the off-loading points (5.1 to 7.9 log10 CFU/cm2; 5.0 to 5.6 log10 CFU/cm2 and 2.7 to 3.7 log10 CFU/cm2, respectively). The storage period, meat type, distance during transportation and temperature were found to have a significant impact on the microbial levels during the distribution of carcasses. Distribution stage had a significant effect (p<0.05) on some of the physico- chemical meat quality attributes and differences in the lightness (L*) and redness (a*) values between the loading, off-loading and display points were observed. Consumers perceived retailer class as one of the factors influencing meat quality, but according to the instrumental measurements retailer class did not have a significant effect on physico-chemical meat quality. However, distance and storage duration significantly (p<0.05) affected (L*) and (a*) values in the meat during distribution chain. Vacuum and overwrapping packaging significantly affected (p<0.05) the shelf life of meat. Therefore, it was concluded that post-slaughter handling during the distribution chain affects the physico- chemical, microbiological and shelf-life of meat.
- Full Text:
- Date Issued: 2015
Effects of natural antioxidants and thermal treatment on quality of meat from Bonsmara and non-descripts cattle
- Authors: Falowo, Andrew Bamidele
- Date: 2015
- Subjects: Meat -- Preservation Antioxidants Meat -- Microbiology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2589 , vital:27906
- Description: The broad objective of this study was to determine the effects of natural antioxidants and thermal treatment on quality of meat from Bonsmara and non-descript cattle. A survey was conducted among 222 consumers in Alice (Fort Hare University community), Eastern Cape Province to determine the level of their awareness on application of antioxidants as preservatives in meat and meat products during storage. Representative samples of Muscularis longissimuss thoracis et lumborum and liver were collected from each carcass of Bonsmara (n=40) and non-descript (n=40) cattle reared on natural pasture to determine the effect of natural antioxidants and thermal treatment on their quality. The results from the survey revealed that 51.35 percent of the respondents had not heard about the use of antioxidant as preservatives in meat products. However, among the remaining respondents (48.65 percent) that were aware of antioxidant and its use as preservative, about 19 percent knew of natural antioxidants, 35 percent synthetic antioxidants while 46 percent had knowledge of both. The results further revealed that the majority of the respondents (82 percent) that had knowledge of natural antioxidants were concerned about the use of synthetic antioxidants in meat and meat products due to their health consequences. The in vitro antioxidant and antibacterial analyses of Bidens pilosa and Moringa oleifera leaf extracts revealed that they contain rich bioactive compounds. Furthermore, the addition of leaf extracts from Moringa oleifera (ML, 0.05 and 0.1 percent w/w) and Biden pilosa (BP, 0.05 and 0.1 percent w/w) to ground raw beef as a natural antioxidant were found to improve the physicochemical, oxidative stability and microbiological qualities of meat compared to the control (meat without extract) and BHT treatment (0.02 percent w/w) during 6 days storage at 40 C. Cattle breed did not have much effect on colour parameters. However, the overall pH of ground beef treated with extracts showed lower values than control and BHT treated beef. Also, ground beef samples containing extracts exhibited (P < 0.05) better colour stability, especially higher redness (a* values), than the control. The formation of TBARS in beef samples treated with extracts was significantly (P < 0.05) lower than the control and BHT treatment. The antibacterial assay of the extracts revealed an appreciable broad spectrum activity against the tested bacteria and microbial counts in ground beef samples compared to control and BHT group. Ground beef treated with plant extracts exhibited lower microbial and lactic acid bacterial counts (P < 0.05) at day 0 and 3 than control samples. Moreover, it was observed that application of sous vides thermal method did not significantly affect the fatty acids and mineral loss in beef and liver across the treatments. However, the total concentration of MUFA was lower in raw liver (20.11±2.38 - 21.08±1.23 percent) than in beef (40.22±1.90 - 42.53±1.29 percent), while total PUFA content were higher in liver (30.73±2.60 - 31.11±1.19 percent) than in beef samples (10.13±3.36 - 11.02±2.74 percent) (p < 0.05). The results also revealed that liver samples from Bonsmara and non-descript cattle had a higher percentage of intramuscular fat content of 4.67 ± 0.53 percent and 4.44 ± 0.53 percent respectively, and fat free dry matter of 27.51 ± 1.05 percent and 25.73 ± 1.05 percent, respectively, than the beef samples (p < 0.05). The concentrations of Mg (52.80±0.22 - 53.70±0.02mg/100g) and Zn (8.90±0.15 - 19.60±0.15mg/100g) were higher in beef than liver samples. The level of Ca (17.00±0.17 - 17.50 ± 0.17mg/100g) in liver was higher than that of beef samples. It was concluded that most consumers preferred the use of natural antioxidants in meat products than synthetic antioxidants due to their health risk. The effectiveness of M. oleifera and B. pilosa leaf extracts on meat quality also revealed that these plants are promising candidates as natural preservatives and their application should be considered in the meat industry. Lastly, findings from this study showed that application of the sous vide technique could protect meat products from nutritional loss during thermal treatment.
- Full Text:
- Date Issued: 2015
- Authors: Falowo, Andrew Bamidele
- Date: 2015
- Subjects: Meat -- Preservation Antioxidants Meat -- Microbiology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2589 , vital:27906
- Description: The broad objective of this study was to determine the effects of natural antioxidants and thermal treatment on quality of meat from Bonsmara and non-descript cattle. A survey was conducted among 222 consumers in Alice (Fort Hare University community), Eastern Cape Province to determine the level of their awareness on application of antioxidants as preservatives in meat and meat products during storage. Representative samples of Muscularis longissimuss thoracis et lumborum and liver were collected from each carcass of Bonsmara (n=40) and non-descript (n=40) cattle reared on natural pasture to determine the effect of natural antioxidants and thermal treatment on their quality. The results from the survey revealed that 51.35 percent of the respondents had not heard about the use of antioxidant as preservatives in meat products. However, among the remaining respondents (48.65 percent) that were aware of antioxidant and its use as preservative, about 19 percent knew of natural antioxidants, 35 percent synthetic antioxidants while 46 percent had knowledge of both. The results further revealed that the majority of the respondents (82 percent) that had knowledge of natural antioxidants were concerned about the use of synthetic antioxidants in meat and meat products due to their health consequences. The in vitro antioxidant and antibacterial analyses of Bidens pilosa and Moringa oleifera leaf extracts revealed that they contain rich bioactive compounds. Furthermore, the addition of leaf extracts from Moringa oleifera (ML, 0.05 and 0.1 percent w/w) and Biden pilosa (BP, 0.05 and 0.1 percent w/w) to ground raw beef as a natural antioxidant were found to improve the physicochemical, oxidative stability and microbiological qualities of meat compared to the control (meat without extract) and BHT treatment (0.02 percent w/w) during 6 days storage at 40 C. Cattle breed did not have much effect on colour parameters. However, the overall pH of ground beef treated with extracts showed lower values than control and BHT treated beef. Also, ground beef samples containing extracts exhibited (P < 0.05) better colour stability, especially higher redness (a* values), than the control. The formation of TBARS in beef samples treated with extracts was significantly (P < 0.05) lower than the control and BHT treatment. The antibacterial assay of the extracts revealed an appreciable broad spectrum activity against the tested bacteria and microbial counts in ground beef samples compared to control and BHT group. Ground beef treated with plant extracts exhibited lower microbial and lactic acid bacterial counts (P < 0.05) at day 0 and 3 than control samples. Moreover, it was observed that application of sous vides thermal method did not significantly affect the fatty acids and mineral loss in beef and liver across the treatments. However, the total concentration of MUFA was lower in raw liver (20.11±2.38 - 21.08±1.23 percent) than in beef (40.22±1.90 - 42.53±1.29 percent), while total PUFA content were higher in liver (30.73±2.60 - 31.11±1.19 percent) than in beef samples (10.13±3.36 - 11.02±2.74 percent) (p < 0.05). The results also revealed that liver samples from Bonsmara and non-descript cattle had a higher percentage of intramuscular fat content of 4.67 ± 0.53 percent and 4.44 ± 0.53 percent respectively, and fat free dry matter of 27.51 ± 1.05 percent and 25.73 ± 1.05 percent, respectively, than the beef samples (p < 0.05). The concentrations of Mg (52.80±0.22 - 53.70±0.02mg/100g) and Zn (8.90±0.15 - 19.60±0.15mg/100g) were higher in beef than liver samples. The level of Ca (17.00±0.17 - 17.50 ± 0.17mg/100g) in liver was higher than that of beef samples. It was concluded that most consumers preferred the use of natural antioxidants in meat products than synthetic antioxidants due to their health risk. The effectiveness of M. oleifera and B. pilosa leaf extracts on meat quality also revealed that these plants are promising candidates as natural preservatives and their application should be considered in the meat industry. Lastly, findings from this study showed that application of the sous vide technique could protect meat products from nutritional loss during thermal treatment.
- Full Text:
- Date Issued: 2015
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