Characterization, management and utilization of landfill municipal solid waste : a case study of Soweto
- Authors: Ayeleru, Olusola Olaitan
- Date: 2016
- Subjects: Integrated solid waste management , Sanitary landfills - South Africa - Soweto , Waste disposal in the ground - South Africa - Soweto , Refuse and refuse disposal - South Africa - Soweto
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/233021 , uj:23781
- Description: M.Tech. , Abstract: The management of solid waste (SW) has become a crucial issue confronting low and middle income countries. This problem emanates from the generation of SW which is currently on a large scale as cities expand. The aims of this study were to determine the composition of the various waste components disposed of to the Marie Louise landfill site (LS), evaluates the elemental composition and proximate analysis of the organic fraction of municipal solid waste (OFMSW), conducts an economic analysis of setting up a recycling facility and to finally evaluating the perception of the general public with regards to the current waste management (WM) services in the City of Johannesburg (CoJ). The objectives of this study were to determine the various waste components disposed of to the LS as a baseline to propose complete diversion of wastes from going to the LS; to determine the suitability of food waste (FW) generated as a potential source of compost and biogas generation; to carry out an economic evaluation of setting up a recycling facility as a source of revenue to the municipality and potential source of jobs opportunities for the youths in the municipality and finally to assess the level of awareness of the people towards municipal solid waste management (MSWM). The waste composition studies were conducted during the summer in 2015 and during the winter in 2016 at the LS. The results of the analysis were classified into two groups based on two of the services offered by Pikitup (PU) (the municipality) (Dailies non compacted and Round collected refuse (RCR) compacted wastes collection services). STATA 12 software was used to determine seasonal variation on the main components of the wastes generated between the summer and the winter exercises for both services. The results obtained showed that p-values were too extreme (when the null hypothesis is true, the p-value is the probability of obtaining a result equal to or “more extreme” than what was actually observed. The p-values obtained for both the Dailies and for the RCR were (p-value = 0.9775) and (p-value = 0.9760) respectively. Analysis of variance (ANOVA) was also used to evaluate seasonal variation in both seasons on both services for the sub-division of the waste streams. Results obtained showed (p-value = 0.9999) for Dailies and (p-value = 0.9913) for RCR. These results show that the differences between the winter and summer for both services were not statistically significant. The elemental composition and proximate analysis of the FW was also evaluated. The analysis gave a C/N of 22.66 and an empirical formula of C27H44NO16. An engineering economic evaluation was conducted to determine the financial feasibility of this project. From the analysis, IRR on investment was found to be 41%, IRR on equity was found to be 80%,..
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- Authors: Ayeleru, Olusola Olaitan
- Date: 2016
- Subjects: Integrated solid waste management , Sanitary landfills - South Africa - Soweto , Waste disposal in the ground - South Africa - Soweto , Refuse and refuse disposal - South Africa - Soweto
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/233021 , uj:23781
- Description: M.Tech. , Abstract: The management of solid waste (SW) has become a crucial issue confronting low and middle income countries. This problem emanates from the generation of SW which is currently on a large scale as cities expand. The aims of this study were to determine the composition of the various waste components disposed of to the Marie Louise landfill site (LS), evaluates the elemental composition and proximate analysis of the organic fraction of municipal solid waste (OFMSW), conducts an economic analysis of setting up a recycling facility and to finally evaluating the perception of the general public with regards to the current waste management (WM) services in the City of Johannesburg (CoJ). The objectives of this study were to determine the various waste components disposed of to the LS as a baseline to propose complete diversion of wastes from going to the LS; to determine the suitability of food waste (FW) generated as a potential source of compost and biogas generation; to carry out an economic evaluation of setting up a recycling facility as a source of revenue to the municipality and potential source of jobs opportunities for the youths in the municipality and finally to assess the level of awareness of the people towards municipal solid waste management (MSWM). The waste composition studies were conducted during the summer in 2015 and during the winter in 2016 at the LS. The results of the analysis were classified into two groups based on two of the services offered by Pikitup (PU) (the municipality) (Dailies non compacted and Round collected refuse (RCR) compacted wastes collection services). STATA 12 software was used to determine seasonal variation on the main components of the wastes generated between the summer and the winter exercises for both services. The results obtained showed that p-values were too extreme (when the null hypothesis is true, the p-value is the probability of obtaining a result equal to or “more extreme” than what was actually observed. The p-values obtained for both the Dailies and for the RCR were (p-value = 0.9775) and (p-value = 0.9760) respectively. Analysis of variance (ANOVA) was also used to evaluate seasonal variation in both seasons on both services for the sub-division of the waste streams. Results obtained showed (p-value = 0.9999) for Dailies and (p-value = 0.9913) for RCR. These results show that the differences between the winter and summer for both services were not statistically significant. The elemental composition and proximate analysis of the FW was also evaluated. The analysis gave a C/N of 22.66 and an empirical formula of C27H44NO16. An engineering economic evaluation was conducted to determine the financial feasibility of this project. From the analysis, IRR on investment was found to be 41%, IRR on equity was found to be 80%,..
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Effect of calcium lignosulphonate and ethylene maleic anhydride on the particulate processes during hydrogen reduction of nickel ammine sulphate solutions
- Authors: Iloy, Rama Achtar
- Date: 2015
- Subjects: Reduction (Chemistry) , Maleic anhydride , Polyethylene , Nickel
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/56173 , uj:16339
- Description: Abstract: Since the inception of metal precipitation by hydrogen, it has been recognized that adding some organic compounds to the reduction solution accelerates the reaction, inhibits plating and helps control the resulting powder properties such as morphology, microstructure and particle size distribution, to name but a few. The powder properties are directly linked to the particulate processes taking place during reduction. Controlling these properties is crucial for downstream processes. For instance, in fuel cell technologies, the porosity of materials used to construct the electrodes is a critical parameter amongst others. However, in addition to their relatively high cost, additives’ function and mechanism of action are not well understood. Furthermore most of the additives are used on a trial and error basis. Since additives constitute one of the major operational costs, it becomes evident their use should be optimized. One of the most plausible options to achieve this is to develop an understanding of their mechanism of action. This dissertation assesses the effect of calcium lignosulphonate and ethylene maleic anhydride on the particulate processes taking place during the reduction of nickel ammine sulphate solutions by hydrogen gas. Reactions were carried out in an autoclave operated at 28 bar and 180°C under stirring conditions of 850 rpm. Five densifications were performed for each additive at the dosage of 2, 5, 7 and 10 mg/L. Particulate processes were studied by analysing the particle size distribution and the corresponding normalized moments. These were further validated by scanning electron microscopy and nitrogen physisorption analyses. The powder phase identification and purity were determined by means of X-ray diffraction and X-ray fluorescence respectively. Both calcium lignosulphonate and ethylene maleic anhydride acted as reduction catalysts under experimental conditions. Calcium lignosulphonate promoted growth and by extension agglomeration which was more pronounced at 10 mg/L. At lower concentrations of calcium lignosulphonate, the system was found to be dominated by breakage as validated by scanning electron micrographs. Although there was no significant difference in the nickel content of the powder obtained in the presence and absence of calcium lignosulphonate, the powder obtained at 10 mg/L additive dosage resulted in the highest sulphur content. Ethylene maleic anhydride on the other hand acted as a growth inhibitor and an anti-agglomerating agent, thus... , M.Tech. (Chemical Engineering)
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- Authors: Iloy, Rama Achtar
- Date: 2015
- Subjects: Reduction (Chemistry) , Maleic anhydride , Polyethylene , Nickel
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/56173 , uj:16339
- Description: Abstract: Since the inception of metal precipitation by hydrogen, it has been recognized that adding some organic compounds to the reduction solution accelerates the reaction, inhibits plating and helps control the resulting powder properties such as morphology, microstructure and particle size distribution, to name but a few. The powder properties are directly linked to the particulate processes taking place during reduction. Controlling these properties is crucial for downstream processes. For instance, in fuel cell technologies, the porosity of materials used to construct the electrodes is a critical parameter amongst others. However, in addition to their relatively high cost, additives’ function and mechanism of action are not well understood. Furthermore most of the additives are used on a trial and error basis. Since additives constitute one of the major operational costs, it becomes evident their use should be optimized. One of the most plausible options to achieve this is to develop an understanding of their mechanism of action. This dissertation assesses the effect of calcium lignosulphonate and ethylene maleic anhydride on the particulate processes taking place during the reduction of nickel ammine sulphate solutions by hydrogen gas. Reactions were carried out in an autoclave operated at 28 bar and 180°C under stirring conditions of 850 rpm. Five densifications were performed for each additive at the dosage of 2, 5, 7 and 10 mg/L. Particulate processes were studied by analysing the particle size distribution and the corresponding normalized moments. These were further validated by scanning electron microscopy and nitrogen physisorption analyses. The powder phase identification and purity were determined by means of X-ray diffraction and X-ray fluorescence respectively. Both calcium lignosulphonate and ethylene maleic anhydride acted as reduction catalysts under experimental conditions. Calcium lignosulphonate promoted growth and by extension agglomeration which was more pronounced at 10 mg/L. At lower concentrations of calcium lignosulphonate, the system was found to be dominated by breakage as validated by scanning electron micrographs. Although there was no significant difference in the nickel content of the powder obtained in the presence and absence of calcium lignosulphonate, the powder obtained at 10 mg/L additive dosage resulted in the highest sulphur content. Ethylene maleic anhydride on the other hand acted as a growth inhibitor and an anti-agglomerating agent, thus... , M.Tech. (Chemical Engineering)
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Torrefaction of landfill food waste and characterization of the torrefied biomass
- Authors: Pahla, Godwell
- Date: 2016
- Subjects: Waste products as fuel , Renewable energy sources - Environmental aspects , Biomass energy , Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/243012 , uj:25081
- Description: M.Tech. (Chemical Engineering) , Abstract: Greenhouse gas emissions and municipal solid waste management have presented challenges globally. This study aims to help mitigate these challenges by producing renewable energy from landfill food waste. Food waste is carbon neutral since plants use carbon dioxide for growth, so its application in coal-fired boilers will reduce the amount of carbon dioxide emissions thereby mitigating greenhouse effects. The problem with food waste is that it has high moisture content and it is heterogeneous. This limits its heating value and increases energy requirements for grinding. This study investigated the possibility of upgrading the fuel properties of food waste to produce biochar with similar properties to bituminous coal. The food waste was treated by torrefaction. The main aim was to optimize torrefaction conditions and analyze thermal evolution of the sample during torrefaction. The food waste samples were collected from Marie Louis landfill site in Soweto. The samples were dried and milled for particle size reduction. The samples were further analyzed by proximate and ultimate analyses to determine its fuel properties and elemental composition before torrefaction. A tube furnace was used for the torrefaction process. Temperature was varied from 200 – 300 oC at a constant residence time of 40 min and 10 oC/min heating rate. Calorific value, mass yield, energy yield and energy density were computed and used to determine the appropriate torrefaction temperature. Residence time was then varied from 20 – 60 min at a constant torrefaction temperature of 275 oC and 10 oC/min heating rate. Heating rate was then varied keeping residence time at 20min and torrefaction temperature at 275 oC. Torrefaction temperature had a more pronounced effect than residence time and heating rate. The calorific value was upgraded from 19.76 MJ/kg for dried raw food waste to 26.15 MJ/kg for torrefied food waste at the optimum conditions which were 275 oC, 20 min and 10 oC/min. The higher heating value was comparable to that of bituminous coal currently being used for power generation in South Africa. Elemental analysis of biochar showed an increase in carbon content with temperature due to loss of oxygen containing volatiles. It was also observed that biochar obtained at the optimum conditions could easily be pelletized since it assumed the shape of the crucible...
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- Authors: Pahla, Godwell
- Date: 2016
- Subjects: Waste products as fuel , Renewable energy sources - Environmental aspects , Biomass energy , Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/243012 , uj:25081
- Description: M.Tech. (Chemical Engineering) , Abstract: Greenhouse gas emissions and municipal solid waste management have presented challenges globally. This study aims to help mitigate these challenges by producing renewable energy from landfill food waste. Food waste is carbon neutral since plants use carbon dioxide for growth, so its application in coal-fired boilers will reduce the amount of carbon dioxide emissions thereby mitigating greenhouse effects. The problem with food waste is that it has high moisture content and it is heterogeneous. This limits its heating value and increases energy requirements for grinding. This study investigated the possibility of upgrading the fuel properties of food waste to produce biochar with similar properties to bituminous coal. The food waste was treated by torrefaction. The main aim was to optimize torrefaction conditions and analyze thermal evolution of the sample during torrefaction. The food waste samples were collected from Marie Louis landfill site in Soweto. The samples were dried and milled for particle size reduction. The samples were further analyzed by proximate and ultimate analyses to determine its fuel properties and elemental composition before torrefaction. A tube furnace was used for the torrefaction process. Temperature was varied from 200 – 300 oC at a constant residence time of 40 min and 10 oC/min heating rate. Calorific value, mass yield, energy yield and energy density were computed and used to determine the appropriate torrefaction temperature. Residence time was then varied from 20 – 60 min at a constant torrefaction temperature of 275 oC and 10 oC/min heating rate. Heating rate was then varied keeping residence time at 20min and torrefaction temperature at 275 oC. Torrefaction temperature had a more pronounced effect than residence time and heating rate. The calorific value was upgraded from 19.76 MJ/kg for dried raw food waste to 26.15 MJ/kg for torrefied food waste at the optimum conditions which were 275 oC, 20 min and 10 oC/min. The higher heating value was comparable to that of bituminous coal currently being used for power generation in South Africa. Elemental analysis of biochar showed an increase in carbon content with temperature due to loss of oxygen containing volatiles. It was also observed that biochar obtained at the optimum conditions could easily be pelletized since it assumed the shape of the crucible...
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Removal of heavy metals from aqueous acidic mineral effluents by reductive precipitation
- Authors: Sithole, Nastassia Thandiwe
- Date: 2015
- Subjects: Sewage - Purification - Heavy metals removal , Heavy metals - Absorption and adsorption , Hydrazine
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/56204 , uj:16342
- Description: Abstract: The removal of heavy metals from acidic mineral effluents (pH<3) is among the most important issues for many industrialized countries. Removal of Fe3+, Al3+ and Mn2+ from acidic mineral effluents was studied using reductive precipitation as an alternative method. A comparative study of using different reducing agents (hydrazine, dimethylamine borane (DMAB) and glyoxylic acid) and different seeding materials (Nickel powder, Fe powder, Granulated Blast Furnace Slag (GBFS) and Basic Oxygen Furnace Slag (BOFS) respectively) was done. Reductive precipitation batch experiments were conducted where metal ions solution, seeding material and a reducing agent were added to a batch reactor. The volume of acidic mineral effluents was 500 ml and 30g of the seeding materials and stoichiometric amounts of the different reducing agents. The obtained BOFS before and after reductive precipitation was characterized for particle size distribution using MPAM, surface morphology and surface functional groups were done using SEM and FTIR respectively. Identification of phases was done using XRD while elemental composition was performed using XRF. using SEM and surface functional groups using FTIR, identification of phases using XRD, elemental composition using XRF. BOFS was the only seeding material characterized since it was found to be more effective and efficient than other seeding materials... , M.Tech. (Chemical Engineering)
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- Authors: Sithole, Nastassia Thandiwe
- Date: 2015
- Subjects: Sewage - Purification - Heavy metals removal , Heavy metals - Absorption and adsorption , Hydrazine
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/56204 , uj:16342
- Description: Abstract: The removal of heavy metals from acidic mineral effluents (pH<3) is among the most important issues for many industrialized countries. Removal of Fe3+, Al3+ and Mn2+ from acidic mineral effluents was studied using reductive precipitation as an alternative method. A comparative study of using different reducing agents (hydrazine, dimethylamine borane (DMAB) and glyoxylic acid) and different seeding materials (Nickel powder, Fe powder, Granulated Blast Furnace Slag (GBFS) and Basic Oxygen Furnace Slag (BOFS) respectively) was done. Reductive precipitation batch experiments were conducted where metal ions solution, seeding material and a reducing agent were added to a batch reactor. The volume of acidic mineral effluents was 500 ml and 30g of the seeding materials and stoichiometric amounts of the different reducing agents. The obtained BOFS before and after reductive precipitation was characterized for particle size distribution using MPAM, surface morphology and surface functional groups were done using SEM and FTIR respectively. Identification of phases was done using XRD while elemental composition was performed using XRF. using SEM and surface functional groups using FTIR, identification of phases using XRD, elemental composition using XRF. BOFS was the only seeding material characterized since it was found to be more effective and efficient than other seeding materials... , M.Tech. (Chemical Engineering)
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Desilication of fly ash and geotechnical applications of the desilicated fly ash
- Authors: Falayi, Thabo
- Date: 2016
- Subjects: Geotechnical engineering , Engineering geology , Soil stabilization , Fly ash
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/233013 , uj:23780
- Description: D.Phil. (Civil Engineering Science) , Abstract: Silica was leached from fly ash (FA) produced by Camden power station (South Africa). The residue, desilicated fly ash (DFA) was then stabilised using lime and alkaline activation. The stabilised residue was then used as a soil stabiliser. Camden FA was found to have a basic pH (10.7) whilst DFA was more basic (12.3) due to a higher K2O content.The major difference between DFA and FA was the presence of a zeolite (Phillipsite K) in DFA. Radiological analysis showed that the activity concentrations of 226Ra, 232Th and 40K for both DFA and FA were below the limits of the South African Government Gazette of 2006. Silica was leached from FA using KOH. The leaching parameters investigated were leaching time, KOH concentration, agitation speed, FA particle size, leaching temperature and liquid solid ratio (L/S). It was found that the optimum leaching conditions were leaching time of 6 h, 3 M KOH, 500 rpm agitation speed, 25 L/S ratio, leaching temperature of 100˚C. The yield was found to be 283.7 g of silica per kg of FA. Silica leaching followed a modified Jander equation kinetics with an N value of 1.48 and an activation energy of 5.9 kJ/mol. DFA was stabilised using lime at elevated temperatures. DFA and lime were mixed in different ratios at optimum moisture content and maximum dry density and then cured at 40ºC, 80ºC and 100ºC for 4 days. 80ºC was found to be the optimum curing temperature. The DFA: lime ratio of 70:30 was found to have an average UCS of 8.8 MPa. Lime consumption was found to follow modified Jander kinetics with activation energy of 16 kJ/mol. Toxicity leaching tests showed a 79% reduction in the leachability of trace and heavy metals. The composite met the minimum requirement of ASTM C34-13 and South African burnt clay standard (SANS227:2007). The influence of open porosity, sum of hydration products and extent of DFA hydration on the strength of DFA lime composites was also studied. For both FA and DFA it was observed that the three parameters combined (open porosity, extent of fly ash/desilicated fly ash hydration and sum of hydration products) had the greatest influence on the UCS than individually with correlation coefficients above 0.98. The use of DFA-lime composite as a stabiliser for expansive soil was also studied. A 70:30 DFA: lime composite was used as the stabiliser. The 30% stabilised soil was found to have a UCS of 4.1 MPa. The stabilised soil met the minimum requirements for the American Concrete Institute’s requirements for backfill material. A 40% addition of FA: lime composite was the optimum for the stabilisation of the same expansive soil. DFA composite stabilisation was better than the FA composite stabilisation due to a superior UCS (4.1 vs 2.62 MPa), better 24 h soak UCS (3.62 vs 0.98 MPa) and a better saturation coefficient 0.35 vs 0.68...
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- Authors: Falayi, Thabo
- Date: 2016
- Subjects: Geotechnical engineering , Engineering geology , Soil stabilization , Fly ash
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/233013 , uj:23780
- Description: D.Phil. (Civil Engineering Science) , Abstract: Silica was leached from fly ash (FA) produced by Camden power station (South Africa). The residue, desilicated fly ash (DFA) was then stabilised using lime and alkaline activation. The stabilised residue was then used as a soil stabiliser. Camden FA was found to have a basic pH (10.7) whilst DFA was more basic (12.3) due to a higher K2O content.The major difference between DFA and FA was the presence of a zeolite (Phillipsite K) in DFA. Radiological analysis showed that the activity concentrations of 226Ra, 232Th and 40K for both DFA and FA were below the limits of the South African Government Gazette of 2006. Silica was leached from FA using KOH. The leaching parameters investigated were leaching time, KOH concentration, agitation speed, FA particle size, leaching temperature and liquid solid ratio (L/S). It was found that the optimum leaching conditions were leaching time of 6 h, 3 M KOH, 500 rpm agitation speed, 25 L/S ratio, leaching temperature of 100˚C. The yield was found to be 283.7 g of silica per kg of FA. Silica leaching followed a modified Jander equation kinetics with an N value of 1.48 and an activation energy of 5.9 kJ/mol. DFA was stabilised using lime at elevated temperatures. DFA and lime were mixed in different ratios at optimum moisture content and maximum dry density and then cured at 40ºC, 80ºC and 100ºC for 4 days. 80ºC was found to be the optimum curing temperature. The DFA: lime ratio of 70:30 was found to have an average UCS of 8.8 MPa. Lime consumption was found to follow modified Jander kinetics with activation energy of 16 kJ/mol. Toxicity leaching tests showed a 79% reduction in the leachability of trace and heavy metals. The composite met the minimum requirement of ASTM C34-13 and South African burnt clay standard (SANS227:2007). The influence of open porosity, sum of hydration products and extent of DFA hydration on the strength of DFA lime composites was also studied. For both FA and DFA it was observed that the three parameters combined (open porosity, extent of fly ash/desilicated fly ash hydration and sum of hydration products) had the greatest influence on the UCS than individually with correlation coefficients above 0.98. The use of DFA-lime composite as a stabiliser for expansive soil was also studied. A 70:30 DFA: lime composite was used as the stabiliser. The 30% stabilised soil was found to have a UCS of 4.1 MPa. The stabilised soil met the minimum requirements for the American Concrete Institute’s requirements for backfill material. A 40% addition of FA: lime composite was the optimum for the stabilisation of the same expansive soil. DFA composite stabilisation was better than the FA composite stabilisation due to a superior UCS (4.1 vs 2.62 MPa), better 24 h soak UCS (3.62 vs 0.98 MPa) and a better saturation coefficient 0.35 vs 0.68...
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Use of Moringa Oleifera seed as a flocculant, anti-microbial agent and metal bio-sorbent in water and wastewater treatment
- Authors: Ncube, Pauline
- Date: 2016
- Subjects: Sewage - Purification , Water - Purification - Adsorption , Flocculation , Coagulation
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/233212 , uj:23806
- Description: M.Tech. (Chemical Engineering) , Abstract: Milled Moringa Oleifera (M.O) seeds were characterised and used as a bio-sorbent in the removal of metals from acidic mineral effluents, coagulant/flocculent and antimicrobial agent in water and wastewater treatment. Biosorption experiments were conducted by means of agitation in a thermostatic shaker using synthetic acidic mineral wastewater consisting of 20 ppm Ni, 20 ppm Cu, 100 ppm Mn and 500 ppm Fe. The effects of solid loading, pH, contact time and temperature were investigated. Adsorption isotherms, kinetics and thermodynamics parameters were calculated from the experimental data obtained. The ability of milled spent Moringa seeds to be re-used (without recycling) and to be recycled was also investigated. Jar test experiments were conducted in order to evaluate the coagulation/flocculation process using synthetic turbid water. Optimum M.O dosage and TSS removal efficiency were determined from the experimental data obtained. The antimicrobial activity of M.O seeds was determined through experiments investigating the effect of raw seed extract and aqueous seed extract on coliforms and Heterotrophic Plate Count (HPC) bacteria. Metal removal followed the order: Ni > Cu > Fe > Mn. Metal removal efficiency increased with pH, time, % solid loading and temperature until sorption equilibrium was achieved. Optimum operating conditions achieved were pH = 3, Temperature = 308K, % solid loading = 10% and residence time of 60, 90, 90 and 120 minutes for Ni, Cu, Fe and Mn respectively. The bio-sorption process was feasible and spontaneous for Cu and Ni only as shown by the negative ΔG◦ values. These values increased on the negative scale with temperature (-80.3 to -2926.9 J/mol for Cu and -782.9 to -2647.3 J/mol for Ni) implying increased probability of the sorption process at higher temperatures. For all metals, ΔH◦ and ΔS◦ values were positive signifying the endothermic nature of the adsorption process and the increase in the degrees of freedom on the surface of the sorbent and disorderness of the system. For the adsorption reaction to proceed spontaneously, ΔG◦< 0, ΔS◦ > 0 and ΔH◦ > 0. The Langmuir model and second order kinetics best described the adsorption process for Ni, Cu and Fe. Ion exchange or chemisorption was the possible mechanism of adsorption as suggested by the Temkin model. FTIR spectrum suggested -C=O- to be the predominant functional group that binds and reacts with Me2+ ions. The spent milled seeds could be effectively re-used for metal removal for two cycles without desorption and could possibly be recycled for further use as bio sorbents for metal removal from AMD...
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- Authors: Ncube, Pauline
- Date: 2016
- Subjects: Sewage - Purification , Water - Purification - Adsorption , Flocculation , Coagulation
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/233212 , uj:23806
- Description: M.Tech. (Chemical Engineering) , Abstract: Milled Moringa Oleifera (M.O) seeds were characterised and used as a bio-sorbent in the removal of metals from acidic mineral effluents, coagulant/flocculent and antimicrobial agent in water and wastewater treatment. Biosorption experiments were conducted by means of agitation in a thermostatic shaker using synthetic acidic mineral wastewater consisting of 20 ppm Ni, 20 ppm Cu, 100 ppm Mn and 500 ppm Fe. The effects of solid loading, pH, contact time and temperature were investigated. Adsorption isotherms, kinetics and thermodynamics parameters were calculated from the experimental data obtained. The ability of milled spent Moringa seeds to be re-used (without recycling) and to be recycled was also investigated. Jar test experiments were conducted in order to evaluate the coagulation/flocculation process using synthetic turbid water. Optimum M.O dosage and TSS removal efficiency were determined from the experimental data obtained. The antimicrobial activity of M.O seeds was determined through experiments investigating the effect of raw seed extract and aqueous seed extract on coliforms and Heterotrophic Plate Count (HPC) bacteria. Metal removal followed the order: Ni > Cu > Fe > Mn. Metal removal efficiency increased with pH, time, % solid loading and temperature until sorption equilibrium was achieved. Optimum operating conditions achieved were pH = 3, Temperature = 308K, % solid loading = 10% and residence time of 60, 90, 90 and 120 minutes for Ni, Cu, Fe and Mn respectively. The bio-sorption process was feasible and spontaneous for Cu and Ni only as shown by the negative ΔG◦ values. These values increased on the negative scale with temperature (-80.3 to -2926.9 J/mol for Cu and -782.9 to -2647.3 J/mol for Ni) implying increased probability of the sorption process at higher temperatures. For all metals, ΔH◦ and ΔS◦ values were positive signifying the endothermic nature of the adsorption process and the increase in the degrees of freedom on the surface of the sorbent and disorderness of the system. For the adsorption reaction to proceed spontaneously, ΔG◦< 0, ΔS◦ > 0 and ΔH◦ > 0. The Langmuir model and second order kinetics best described the adsorption process for Ni, Cu and Fe. Ion exchange or chemisorption was the possible mechanism of adsorption as suggested by the Temkin model. FTIR spectrum suggested -C=O- to be the predominant functional group that binds and reacts with Me2+ ions. The spent milled seeds could be effectively re-used for metal removal for two cycles without desorption and could possibly be recycled for further use as bio sorbents for metal removal from AMD...
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Extraction and precipitation of phosphorus from sewage sludge
- Authors: Shiba, Nothando
- Date: 2016
- Subjects: Sewage - Purification - Phosphate removal , Sewage - Purification - Nutrient removal , Sewage - Purification - Precipitation , Sewage - Purification - Activated sludge process
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/212973 , uj:21062
- Description: Abstract: Raw sewage sludge from East Rand Water Care Association (ERWAT) had high phosphorus (P) content, approximately 15.2 % (w/w) P2O5. This indicates a potential resource of the limiting nutrient P. The effect of the acid type, acid concentration, time and solid/liquid ratio on extraction was investigated. Methods of solution purification were also explored namely adsorption and ion exchange. Magnesium oxide and ammonium hydroxide were used as sources of magnesium and nitrogen, respectively, as well as pH regulators to precipitate P as struvite. XRF results showed that 82 % P was recovered from raw sewage sludge after 2 hours leaching using 1 M sulphuric acid and purification using ion exchange. Kinetic studies showed that the leaching of phosphorus follows the Dickinson model. Most graphs show a linear fit up to 100 mins, thereafter the slope changes suggesting a two-step process with different rate parameters. Thus a trend line fitting all the points may not be ideal. A rate of reaction of about 2 × 10-5 s-1 was obtained for the first 100 mins. The rate limiting step is controlled by diffusion. Adsorption of phosphorus using ion exchange provided a better solution for the recovery of this natural resource, which eventually could meet the ever-increasing requirement for phosphorus. The overall results indicated that the raw sewage sludge can be treated with acid to efficiently recover phosphorus and thus can be considered a potentially renewable source of phosphorus. Phosphorus solubility in 2 % critic acid was almost 96 %. Environmental, gram-positive bacillus subtilis were found in the precipitate, which are harmless to the plants since they already exist in the soil conditions where the precipitate would be applied. The precipitate can therefore be used as a fertiliser. , M.Tech. (Chemical Engineering)
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- Authors: Shiba, Nothando
- Date: 2016
- Subjects: Sewage - Purification - Phosphate removal , Sewage - Purification - Nutrient removal , Sewage - Purification - Precipitation , Sewage - Purification - Activated sludge process
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/212973 , uj:21062
- Description: Abstract: Raw sewage sludge from East Rand Water Care Association (ERWAT) had high phosphorus (P) content, approximately 15.2 % (w/w) P2O5. This indicates a potential resource of the limiting nutrient P. The effect of the acid type, acid concentration, time and solid/liquid ratio on extraction was investigated. Methods of solution purification were also explored namely adsorption and ion exchange. Magnesium oxide and ammonium hydroxide were used as sources of magnesium and nitrogen, respectively, as well as pH regulators to precipitate P as struvite. XRF results showed that 82 % P was recovered from raw sewage sludge after 2 hours leaching using 1 M sulphuric acid and purification using ion exchange. Kinetic studies showed that the leaching of phosphorus follows the Dickinson model. Most graphs show a linear fit up to 100 mins, thereafter the slope changes suggesting a two-step process with different rate parameters. Thus a trend line fitting all the points may not be ideal. A rate of reaction of about 2 × 10-5 s-1 was obtained for the first 100 mins. The rate limiting step is controlled by diffusion. Adsorption of phosphorus using ion exchange provided a better solution for the recovery of this natural resource, which eventually could meet the ever-increasing requirement for phosphorus. The overall results indicated that the raw sewage sludge can be treated with acid to efficiently recover phosphorus and thus can be considered a potentially renewable source of phosphorus. Phosphorus solubility in 2 % critic acid was almost 96 %. Environmental, gram-positive bacillus subtilis were found in the precipitate, which are harmless to the plants since they already exist in the soil conditions where the precipitate would be applied. The precipitate can therefore be used as a fertiliser. , M.Tech. (Chemical Engineering)
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Removal of sulphates from acid mine drainage using barium and organically modified clay
- Authors: Moreroa, Mabatho
- Date: 2015
- Subjects: Acid mine drainage , Acid mine drainage - Purification , Sulfates - Absorption and adsorption , Water - Purification - Organic compounds removal
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/212962 , uj:21060
- Description: Abstract: Attapulgite and Mozambican bentonite (MB) were modified by using barium chloride and ammonium cations such as hexadecyltrimethylammonium bromide (HDTMA) and trimethyldecylammonium bromide (TDTMA) to enhance the removal capacity of sulphates from acid mine drainage (AMD). Through the modification process the surface properties of the clays was rendered organophilic. Batch adsorption experiments of the modified clays were done in a thermostatic shaker at different temperatures, mass loading of adsorbent, and cation exchange capacity (CEC) percentages to investigate the sorption behaviour of sulphates from AMD. Characterization of the modified clay that gave the highest removal of sulphates was done using XRF, XRD, FTIR and SEM to investigate the chemical composition of the clay, removal mechanism and structural change of the clay as a result of sorption of sulphates. Attapulgite showed higher removal of sulphates (70.8%) when modified with BaCl2 than the other two surfactants. This maximum removal was achieved at 25oC and 10% w/v clay to AMD. The reaction fitted the Temkin adsorption isotherm and the second order kinetic model. Adsorption of sulphates on attapulgite was not dependent on temperature as the difference in recovery was not statistically significant when temperature was varied. The value of activation energy (23.7kJ/mol) showed that chemisorption was the dominant mechanism of sulphate removal. MB showed higher removal of sulphates (74.0%) when modified with TDTMA. The reaction was endothermic and fitted the Temkin isotherm model and the second order kinetic model. More sulphates were adsorbed at higher temperatures, suggesting that this was an endothermic reaction, which was supported by the positive value of enthalpy. The activation energy for this reaction (-124.8 kJ/mol) showed that physisorption was the dominant mechanism of sulphate removal. Characterization of both clays showed that the sulphates were removed by adsorption and that the modifiers were only adsorbed on the surface of the clay during the cation exchange process without destroying the crystalline structure of the clay. At high solid loading, more sulphates were adsorbed from the AMD sample by both clays. This implied that at higher solid loadings, there are more sites of adsorption and thus, the higher sulphate removal... , M.Tech. (Chemical Engineering)
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- Authors: Moreroa, Mabatho
- Date: 2015
- Subjects: Acid mine drainage , Acid mine drainage - Purification , Sulfates - Absorption and adsorption , Water - Purification - Organic compounds removal
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/212962 , uj:21060
- Description: Abstract: Attapulgite and Mozambican bentonite (MB) were modified by using barium chloride and ammonium cations such as hexadecyltrimethylammonium bromide (HDTMA) and trimethyldecylammonium bromide (TDTMA) to enhance the removal capacity of sulphates from acid mine drainage (AMD). Through the modification process the surface properties of the clays was rendered organophilic. Batch adsorption experiments of the modified clays were done in a thermostatic shaker at different temperatures, mass loading of adsorbent, and cation exchange capacity (CEC) percentages to investigate the sorption behaviour of sulphates from AMD. Characterization of the modified clay that gave the highest removal of sulphates was done using XRF, XRD, FTIR and SEM to investigate the chemical composition of the clay, removal mechanism and structural change of the clay as a result of sorption of sulphates. Attapulgite showed higher removal of sulphates (70.8%) when modified with BaCl2 than the other two surfactants. This maximum removal was achieved at 25oC and 10% w/v clay to AMD. The reaction fitted the Temkin adsorption isotherm and the second order kinetic model. Adsorption of sulphates on attapulgite was not dependent on temperature as the difference in recovery was not statistically significant when temperature was varied. The value of activation energy (23.7kJ/mol) showed that chemisorption was the dominant mechanism of sulphate removal. MB showed higher removal of sulphates (74.0%) when modified with TDTMA. The reaction was endothermic and fitted the Temkin isotherm model and the second order kinetic model. More sulphates were adsorbed at higher temperatures, suggesting that this was an endothermic reaction, which was supported by the positive value of enthalpy. The activation energy for this reaction (-124.8 kJ/mol) showed that physisorption was the dominant mechanism of sulphate removal. Characterization of both clays showed that the sulphates were removed by adsorption and that the modifiers were only adsorbed on the surface of the clay during the cation exchange process without destroying the crystalline structure of the clay. At high solid loading, more sulphates were adsorbed from the AMD sample by both clays. This implied that at higher solid loadings, there are more sites of adsorption and thus, the higher sulphate removal... , M.Tech. (Chemical Engineering)
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Absorption of heavy metals and neutralisation of acid mine drainage using clay minerals
- Authors: Falayi, Thabo
- Date: 2014-06-04
- Subjects: Acid main drainage - Purification , Water - Purification - Adsorption , Clay
- Type: Thesis
- Identifier: uj:11389 , http://hdl.handle.net/10210/11027
- Description: M.Tech. (Chemical Engineering) , Please refer to full text to view abstract
- Full Text:
- Authors: Falayi, Thabo
- Date: 2014-06-04
- Subjects: Acid main drainage - Purification , Water - Purification - Adsorption , Clay
- Type: Thesis
- Identifier: uj:11389 , http://hdl.handle.net/10210/11027
- Description: M.Tech. (Chemical Engineering) , Please refer to full text to view abstract
- Full Text:
Geotechnical properties of marginal highway backfill stabilized with activated fly ash
- Authors: Aneke, Ikechukwu Frank
- Date: 2015
- Subjects: Engineering geology , Geotechnical engineering , Reliability , Soil stabilization , Fly ash
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/82735 , uj:18995
- Description: Abstract: Soil stabilized with fly ash is the most frequently used method in improvement of the geotechnical properties of soil in South Africa and it is increasingly gaining interest internationally. However, South Africa has several standards and regulations for the use of fly ash and other by products in the soil stabilization process as well as in concrete production. Activated fly ash has not been explored for stabilization of soils in South Africa. Therefore, the present study is an attempt to empirically evaluate the use of chemically activated class „F‟ fly ash obtained from Lethabo power plant in South Africa. The use of the activated fly ash could improve the geotechnical properties [including consistency limits, compaction properties, unconfined compressive strength (UCS), elasticity modulus, durability, california bearing ratio (CBR) and hydraulic conductivity]of the two different fine-grained soils tested in this study. A Red soil sample collected from Parktown, Johannesburg, South Africa was studied in two combinations; a proportion of 50% Kaolinite + 50% Red soil = Kaolinite soil and 30% Bentonite + 20% Kaolinite + 50% Red soil = Bentonite soil. Soils used in the study were built up from the red soil with different proportions to Bentonite and Kaolinite clays. One of the significant objectives of this study was to use mechanically and chemically activated class „F‟ fly ash to improve the geotechnical properties of the heavy clay content soils and to compare these properties with those of the same soils when untreated... , M.Ing. (Civil Engineering)
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- Authors: Aneke, Ikechukwu Frank
- Date: 2015
- Subjects: Engineering geology , Geotechnical engineering , Reliability , Soil stabilization , Fly ash
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/82735 , uj:18995
- Description: Abstract: Soil stabilized with fly ash is the most frequently used method in improvement of the geotechnical properties of soil in South Africa and it is increasingly gaining interest internationally. However, South Africa has several standards and regulations for the use of fly ash and other by products in the soil stabilization process as well as in concrete production. Activated fly ash has not been explored for stabilization of soils in South Africa. Therefore, the present study is an attempt to empirically evaluate the use of chemically activated class „F‟ fly ash obtained from Lethabo power plant in South Africa. The use of the activated fly ash could improve the geotechnical properties [including consistency limits, compaction properties, unconfined compressive strength (UCS), elasticity modulus, durability, california bearing ratio (CBR) and hydraulic conductivity]of the two different fine-grained soils tested in this study. A Red soil sample collected from Parktown, Johannesburg, South Africa was studied in two combinations; a proportion of 50% Kaolinite + 50% Red soil = Kaolinite soil and 30% Bentonite + 20% Kaolinite + 50% Red soil = Bentonite soil. Soils used in the study were built up from the red soil with different proportions to Bentonite and Kaolinite clays. One of the significant objectives of this study was to use mechanically and chemically activated class „F‟ fly ash to improve the geotechnical properties of the heavy clay content soils and to compare these properties with those of the same soils when untreated... , M.Ing. (Civil Engineering)
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Recovery of hematite from fluorspar tailings using reverse cationic flotation
- Authors: Lubisi, Thembelihle Portia
- Date: 2017
- Subjects: Fluorspar - Analysis , Fluorspar - South Africa , Ore deposits - South Africa , Cations
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/263032 , uj:27799
- Description: M.Tech. (Chemical Engineering) , Abstract: The exploration of fluorspar ore in mining results in large amount of unrecovered valuable products found associated with fluorspar in the ore, representing 60% of the run of mine. Several million tons of valuable minerals are discarded every year into tailings ponds, incurring disposal costs, loss of potential company revenue and environmental pollution. This study was undertaken to identify the valuable mineral in the fluorspar tails with an aim of recovering such minerals, thus contributing to an ongoing treatment of waste minerals. A representative sample was received from Vergenoeg Mine, South Africa, in 2014. Characterisation of the sample was conducted to determine physical, chemical and mineralogical properties. Particle size distribution analysis using Micratrac Particle Size Analyser showed that the sample was of fine texture, with 80% passing 120μm. Chemical analysis using X-ray fluorescent spectrometer (XRF) showed that the major element was Fe assaying 48.9þ. Major gangue minerals were SiO2 (16.8%) and minor presence of CaO (3.8%) and F (2.25%) while all other components were reported at <1%. The metal distribution showed that iron was concentrating in the finer size range with 33.59þ reported in the +150μm and 52.09þ in the <38μm size fraction. The mineral phase test using X-ray powder diffraction (XRD) showed that iron was abundantly (>50%) found in the form of hematite while minor presence (3-10%) of iron in a form of goethite and magnetite was observed. The Quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) results showed that the largest portion of iron oxides (12.04wt%) occurred between the 40-50μm particle size range and the majority of Fe-oxide in the sample occurred between 10-70μm size range. Mineral liberation analysis showed that 81% of the iron oxide is liberated, while 16% and 3% were middling and locked Fe-oxide respectively. The locked particles were found to be in the <20μm size range. From the characterization results the sample was classed as low grade iron oxide and reverse cationic flotation was selected as the best concentration method. This study used reverse cationic flotation to concentrate the iron, whereby two types of depressants and amine collectors were studied. The objective was to concentrate the low grade iron into quality standards required for blast furnace feed; ≥63þ, alumina to silica ratio of ≤1% with alumina <2%. The collectors investigated were the primary mono-amine (Dodecylamine) and tertiary amine (Betacol 373). The investigated depressants were soluble starch and a dextrin (Betachem 30D). The flotation parameters investigated were collector dosage, depressant dosage, pH, solids content, conditioning time, agitation speed, air rate and...
- Full Text:
- Authors: Lubisi, Thembelihle Portia
- Date: 2017
- Subjects: Fluorspar - Analysis , Fluorspar - South Africa , Ore deposits - South Africa , Cations
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/263032 , uj:27799
- Description: M.Tech. (Chemical Engineering) , Abstract: The exploration of fluorspar ore in mining results in large amount of unrecovered valuable products found associated with fluorspar in the ore, representing 60% of the run of mine. Several million tons of valuable minerals are discarded every year into tailings ponds, incurring disposal costs, loss of potential company revenue and environmental pollution. This study was undertaken to identify the valuable mineral in the fluorspar tails with an aim of recovering such minerals, thus contributing to an ongoing treatment of waste minerals. A representative sample was received from Vergenoeg Mine, South Africa, in 2014. Characterisation of the sample was conducted to determine physical, chemical and mineralogical properties. Particle size distribution analysis using Micratrac Particle Size Analyser showed that the sample was of fine texture, with 80% passing 120μm. Chemical analysis using X-ray fluorescent spectrometer (XRF) showed that the major element was Fe assaying 48.9þ. Major gangue minerals were SiO2 (16.8%) and minor presence of CaO (3.8%) and F (2.25%) while all other components were reported at <1%. The metal distribution showed that iron was concentrating in the finer size range with 33.59þ reported in the +150μm and 52.09þ in the <38μm size fraction. The mineral phase test using X-ray powder diffraction (XRD) showed that iron was abundantly (>50%) found in the form of hematite while minor presence (3-10%) of iron in a form of goethite and magnetite was observed. The Quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) results showed that the largest portion of iron oxides (12.04wt%) occurred between the 40-50μm particle size range and the majority of Fe-oxide in the sample occurred between 10-70μm size range. Mineral liberation analysis showed that 81% of the iron oxide is liberated, while 16% and 3% were middling and locked Fe-oxide respectively. The locked particles were found to be in the <20μm size range. From the characterization results the sample was classed as low grade iron oxide and reverse cationic flotation was selected as the best concentration method. This study used reverse cationic flotation to concentrate the iron, whereby two types of depressants and amine collectors were studied. The objective was to concentrate the low grade iron into quality standards required for blast furnace feed; ≥63þ, alumina to silica ratio of ≤1% with alumina <2%. The collectors investigated were the primary mono-amine (Dodecylamine) and tertiary amine (Betacol 373). The investigated depressants were soluble starch and a dextrin (Betachem 30D). The flotation parameters investigated were collector dosage, depressant dosage, pH, solids content, conditioning time, agitation speed, air rate and...
- Full Text:
Attainable regions for optimal reaction networks: application of ΔH-ΔG plot to direct synthesis of dimethyl ether from syngas
- Authors: Paepae, Thulane
- Date: 2015
- Subjects: Heat balance (Engineering) , Chemical processes , Thermodynamics , Thermodynamics - Industrial applications
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/213511 , uj:21162
- Description: Abstract: Industrial processes pose a serious threat to the world’s natural resources for they consume them in high proportions as sources of energy for driving chemical processes that provide raw materials for many industrial chemicals. The chemical and petrochemical industries consume about 61% of global industrial energy and emit about 36% of carbon dioxide to the environment. A significant portion of the energy demand is entirely for feedstock, which cannot be reduced through energy efficiency measures. The responsibility therefore for cutting back on the amount of energy needed for chemical processes rests on improving the efficiency of the processes used. The purpose of this research is to demonstrate the use of a novel method of synthesizing process flowsheets, using a graphical tool called the GH-space and in particular to look at how it can be used to compare the reactions of a combined simultaneous process with regard to their thermodynamics. This allows us to synthesize flow-sheets that are reversible and which meet the process targets by implementing mass and energy integration. It also provides guidance on what design decisions would be best suited to developing new processes that are more effective and make lower demands on raw material and energy usage. The approach also provides useful information for evaluating processes through likely limiting extents with respect to the reaction pathways, and comparison between the research findings and their theoretical targets in order to identify any possible energy savings that can be made. The GH-space technique uses fundamental thermodynamic principles to allow the mass, energy and work balances locate the attainable region for chemical processes in a reactor. Furthermore, processes and unit operations can be defined as vectors in the GH-space. Using the targets, one can combine the vector processes in such a way as to approach the target. These vector processes, and the way they are combined, can then be interpreted in terms of flowsheets. This is opposite to what is normally done and allows the process balances to determine what the best flowsheet might look like, allowing for great innovation from the very start of a design. In addition to this, probably the greatest advantage of the GH-space technique is that processes of great complexity can all be analysed on a set of two-dimensional axes. After finding the attainable region, its boundaries can be interpreted in... , M.Tech. (Chemical Engineering)
- Full Text:
- Authors: Paepae, Thulane
- Date: 2015
- Subjects: Heat balance (Engineering) , Chemical processes , Thermodynamics , Thermodynamics - Industrial applications
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/213511 , uj:21162
- Description: Abstract: Industrial processes pose a serious threat to the world’s natural resources for they consume them in high proportions as sources of energy for driving chemical processes that provide raw materials for many industrial chemicals. The chemical and petrochemical industries consume about 61% of global industrial energy and emit about 36% of carbon dioxide to the environment. A significant portion of the energy demand is entirely for feedstock, which cannot be reduced through energy efficiency measures. The responsibility therefore for cutting back on the amount of energy needed for chemical processes rests on improving the efficiency of the processes used. The purpose of this research is to demonstrate the use of a novel method of synthesizing process flowsheets, using a graphical tool called the GH-space and in particular to look at how it can be used to compare the reactions of a combined simultaneous process with regard to their thermodynamics. This allows us to synthesize flow-sheets that are reversible and which meet the process targets by implementing mass and energy integration. It also provides guidance on what design decisions would be best suited to developing new processes that are more effective and make lower demands on raw material and energy usage. The approach also provides useful information for evaluating processes through likely limiting extents with respect to the reaction pathways, and comparison between the research findings and their theoretical targets in order to identify any possible energy savings that can be made. The GH-space technique uses fundamental thermodynamic principles to allow the mass, energy and work balances locate the attainable region for chemical processes in a reactor. Furthermore, processes and unit operations can be defined as vectors in the GH-space. Using the targets, one can combine the vector processes in such a way as to approach the target. These vector processes, and the way they are combined, can then be interpreted in terms of flowsheets. This is opposite to what is normally done and allows the process balances to determine what the best flowsheet might look like, allowing for great innovation from the very start of a design. In addition to this, probably the greatest advantage of the GH-space technique is that processes of great complexity can all be analysed on a set of two-dimensional axes. After finding the attainable region, its boundaries can be interpreted in... , M.Tech. (Chemical Engineering)
- Full Text:
Development of value-added materials from municipal plastic solid waste
- Authors: Ayeleru, Olusola Olaitan
- Date: 2020
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/443771 , uj:38760
- Description: Abstract: Continuous consumption of plastic materials that brings about rapid and more plastic wastes (PWs) generation has become an issue of concern globally, specifically in low-income countries (LCs) where waste management services are still at an infant stage and are inadequate and unstainable. The explosion and acute generation of PWs are dependent on many factors including, incessant migration of citizens in search of greener pastures from rural areas to cities and continuous influx of economic migrants from surrounding African nations and other nations of the world to sub Sahara Africa (SSA) region, changes in consumption pattern, rapid economic and industrial growth etc. The most startling thing about the severe plastic waste (PW) generation is that many citizens are not even aware of the negative/damaging impact of their activities on public health and the natural environment. Besides, the management of PW is now a challenge owing to factors like; insufficient budget for waste management (WM), unavailability of land spaces in cities for the construction of new disposal facilities, bad legislation and policies; and poor education and awareness campaigns. Hence, this study aims to enlighten the populace on the need for a change of attitude and behaviour towards municipal plastic solid waste management and to support recycling for greener cities and a sustainable future. To achieve this, a cross section of the students of the University of Johannesburg, South Africa were interviewed via a structured questionnaire survey and a logistic prediction model was developed to evaluate the attitudes and behaviours of the students towards recycling. Moreover, polystyrene plastic wastes (PSPWs) were recycled via solvothermal technique (chemical recycling) where a hybrid organic-inorganic nanocomposite (a value-added material) was developed. The synthesised nanocomposites (NCs) were characterized by XPS and EDX; XRD, FTIR, SEM, TEM and DLS; TGA, DSC and BET. Moreover, the neat (control) and unprocessed recycled polystyrene (rPS) were also characterized by NMR and GPC. , Ph.D. (Chemical Engineering)
- Full Text:
- Authors: Ayeleru, Olusola Olaitan
- Date: 2020
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/443771 , uj:38760
- Description: Abstract: Continuous consumption of plastic materials that brings about rapid and more plastic wastes (PWs) generation has become an issue of concern globally, specifically in low-income countries (LCs) where waste management services are still at an infant stage and are inadequate and unstainable. The explosion and acute generation of PWs are dependent on many factors including, incessant migration of citizens in search of greener pastures from rural areas to cities and continuous influx of economic migrants from surrounding African nations and other nations of the world to sub Sahara Africa (SSA) region, changes in consumption pattern, rapid economic and industrial growth etc. The most startling thing about the severe plastic waste (PW) generation is that many citizens are not even aware of the negative/damaging impact of their activities on public health and the natural environment. Besides, the management of PW is now a challenge owing to factors like; insufficient budget for waste management (WM), unavailability of land spaces in cities for the construction of new disposal facilities, bad legislation and policies; and poor education and awareness campaigns. Hence, this study aims to enlighten the populace on the need for a change of attitude and behaviour towards municipal plastic solid waste management and to support recycling for greener cities and a sustainable future. To achieve this, a cross section of the students of the University of Johannesburg, South Africa were interviewed via a structured questionnaire survey and a logistic prediction model was developed to evaluate the attitudes and behaviours of the students towards recycling. Moreover, polystyrene plastic wastes (PSPWs) were recycled via solvothermal technique (chemical recycling) where a hybrid organic-inorganic nanocomposite (a value-added material) was developed. The synthesised nanocomposites (NCs) were characterized by XPS and EDX; XRD, FTIR, SEM, TEM and DLS; TGA, DSC and BET. Moreover, the neat (control) and unprocessed recycled polystyrene (rPS) were also characterized by NMR and GPC. , Ph.D. (Chemical Engineering)
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