Energy generating performance of domestic wastewater fed sandwich dual-chamber microbial fuel cells
- Authors: Adeniran, Joshua Adeniyi
- Date: 2015-06-26
- Subjects: Waste products as fuel , Water - Purification - Membrane filtration , Water - Purification - Biological treatment , Sewage - Purification - Anaerobic treatment , Microbial fuel cells , Waste heat , Bioreactors
- Type: Thesis
- Identifier: uj:13627 , http://hdl.handle.net/10210/13808
- Description: M.Tech. (Civil Engineering) , This study presents work on the design and construction of three dual-chamber microbial fuel cells (MFCs) using a sandwich separator electrode assembly (SSEA) and membrane cathode assembly (MCA) for the dual purposes of energy generation from domestic wastewater and wastewater treatment. MFC1 was designed using an improvised SSEA technique (i.e. a separator electrode membrane electrode configuration, SEMEC) by gluing a sandwich of anode, membrane and a mesh current collector cathode to an anode chamber made from a polyethylene wide-mouth bottle. The reactor was filled with 1500 mL of domestic wastewater and operated on a long fed-batch mode with a residence time of 3 weeks. The reactor was inoculated with a mixed culture of bacteria present in the wastewater stream. The aim was to study the impact of wastewater COD concentration on power generation and wastewater treatment efficiency. For MFC2 and MFC 3, cathodes were constructed using the MCA technique consisting of a membrane and a mesh current collector cathode, with the anode electrode at the opposite side of stacked Perspex sections used for the anode chamber. The impact of electrode material on current production was examined in this study. For MFC2 a mesh current collector treated with polytetrafluoroethylene (PTFE) and activated carbon (AC) functioned as the cathode, while the MFC3 cathode was an uncatalyzed mesh current collector. The two reactors were both filled with 350 mL of domestic wastewater...
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- Authors: Adeniran, Joshua Adeniyi
- Date: 2015-06-26
- Subjects: Waste products as fuel , Water - Purification - Membrane filtration , Water - Purification - Biological treatment , Sewage - Purification - Anaerobic treatment , Microbial fuel cells , Waste heat , Bioreactors
- Type: Thesis
- Identifier: uj:13627 , http://hdl.handle.net/10210/13808
- Description: M.Tech. (Civil Engineering) , This study presents work on the design and construction of three dual-chamber microbial fuel cells (MFCs) using a sandwich separator electrode assembly (SSEA) and membrane cathode assembly (MCA) for the dual purposes of energy generation from domestic wastewater and wastewater treatment. MFC1 was designed using an improvised SSEA technique (i.e. a separator electrode membrane electrode configuration, SEMEC) by gluing a sandwich of anode, membrane and a mesh current collector cathode to an anode chamber made from a polyethylene wide-mouth bottle. The reactor was filled with 1500 mL of domestic wastewater and operated on a long fed-batch mode with a residence time of 3 weeks. The reactor was inoculated with a mixed culture of bacteria present in the wastewater stream. The aim was to study the impact of wastewater COD concentration on power generation and wastewater treatment efficiency. For MFC2 and MFC 3, cathodes were constructed using the MCA technique consisting of a membrane and a mesh current collector cathode, with the anode electrode at the opposite side of stacked Perspex sections used for the anode chamber. The impact of electrode material on current production was examined in this study. For MFC2 a mesh current collector treated with polytetrafluoroethylene (PTFE) and activated carbon (AC) functioned as the cathode, while the MFC3 cathode was an uncatalyzed mesh current collector. The two reactors were both filled with 350 mL of domestic wastewater...
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Process parameters and conditions for batch production of eco-fuel briquettes
- Authors: Pilusa, Tsietsi Jefrey
- Date: 2012-09-04
- Subjects: Fuel - Combustion , Fuel , Waste products as fuel
- Type: Thesis
- Identifier: uj:3505 , http://hdl.handle.net/10210/6894
- Description: M.Tech. , In this work, eco-fuel briquettes made from a mixture of 32% spent coffee grounds, 23% coal fines, 11% saw dust, 18% mielie husks, 10% waste paper and 6% paper pulp contaminated water, respectively were investigated. Various processing stages such as briquetting, drying, combustion and flue gas emissions were investigated in order to evaluate the socio-economic viability of the batch production of eco-fuel briquettes from biomass waste material. Each stage was studied independently in order to develop basic models that contained material and energy balances. A screw press briquetting machine was designed and fabricated as part of this work to be tested against the legacy foundation Porta press, and the Bikernmayer hand brick press. The compaction of the biomass waste material into briquettes follows the principle of physical interlocking of the fine particles within the plant fibres, natural material binding due to released cellulose content, as well as reduction in porosity, due to a simultaneous dewatering and compaction action. The processing variables such as cycle times and pressure were studied. The Bikernmayer press is preferred as it produced briquettes of higher bulk densities and lower moisture content as compared to the other presses. The drying was investigated in a laboratory scale convective dryer to establish typical convection parameters. A drying system that utilizes produced briquettes as a heating medium is proposed, and here drying will be effected over a refractory brick fireplace by means of convection and radiation. A basic model was set up to include radiation with the convection to predict a drying time of 4.8 hours. The combustion of briquettes was investigated using a POCA ceramic stove linked to the testo Portable Emission Analyzer System. This enabled an air-to-fuel ratio of 1.44 and a burning rate of 2g per minute to be established. The energy transfer efficiency for boiling a pot of water was found to be 85%. The gas emissions were found to be within the acceptable limits, as set out by OSHA. A standard initial economic evaluation was performed based on a briquette selling price of R2.26 per kilogram for the ease of accommodating the local market. The financial model for both Porta press and screw press were not economically viable, as their running costs were greater than the gross project revenues. For the Bikernmayer conceptual model, with a total capital investment of R669, 981+ VAT (this includes one year operating cost) and a project life of five years, the gross Process parameters and conditions batch production of eco-fuel briquettes profit margin is 44%, the profitability index is 5.33 and the internal Rate of return 31.44%. The net present value and return period are R676, 896 and 0.408 years respectively. The customer profile as currently at hand is 17% of the selected area within 80 m radius from production site. The remaining 83% will be in need of energy as they become aware of the new product offering. The selling of the briquettes should be accompanied by an education process, to avoid the dangers of heating indoors. The principal driver for this project is socio economic development and it is being strengthened by Eskom’s inability to provide sufficient energy. A secondary driver is the global drive to reduce emissions and fossil fuel usage; this technology does exactly this whilst diverting waste from landfill. In the Polokwane declaration (2008), it is stated that South Africa will have no calorific waste to landfill by 2014. Hence legislation will also provide a major part of the drive.
- Full Text:
- Authors: Pilusa, Tsietsi Jefrey
- Date: 2012-09-04
- Subjects: Fuel - Combustion , Fuel , Waste products as fuel
- Type: Thesis
- Identifier: uj:3505 , http://hdl.handle.net/10210/6894
- Description: M.Tech. , In this work, eco-fuel briquettes made from a mixture of 32% spent coffee grounds, 23% coal fines, 11% saw dust, 18% mielie husks, 10% waste paper and 6% paper pulp contaminated water, respectively were investigated. Various processing stages such as briquetting, drying, combustion and flue gas emissions were investigated in order to evaluate the socio-economic viability of the batch production of eco-fuel briquettes from biomass waste material. Each stage was studied independently in order to develop basic models that contained material and energy balances. A screw press briquetting machine was designed and fabricated as part of this work to be tested against the legacy foundation Porta press, and the Bikernmayer hand brick press. The compaction of the biomass waste material into briquettes follows the principle of physical interlocking of the fine particles within the plant fibres, natural material binding due to released cellulose content, as well as reduction in porosity, due to a simultaneous dewatering and compaction action. The processing variables such as cycle times and pressure were studied. The Bikernmayer press is preferred as it produced briquettes of higher bulk densities and lower moisture content as compared to the other presses. The drying was investigated in a laboratory scale convective dryer to establish typical convection parameters. A drying system that utilizes produced briquettes as a heating medium is proposed, and here drying will be effected over a refractory brick fireplace by means of convection and radiation. A basic model was set up to include radiation with the convection to predict a drying time of 4.8 hours. The combustion of briquettes was investigated using a POCA ceramic stove linked to the testo Portable Emission Analyzer System. This enabled an air-to-fuel ratio of 1.44 and a burning rate of 2g per minute to be established. The energy transfer efficiency for boiling a pot of water was found to be 85%. The gas emissions were found to be within the acceptable limits, as set out by OSHA. A standard initial economic evaluation was performed based on a briquette selling price of R2.26 per kilogram for the ease of accommodating the local market. The financial model for both Porta press and screw press were not economically viable, as their running costs were greater than the gross project revenues. For the Bikernmayer conceptual model, with a total capital investment of R669, 981+ VAT (this includes one year operating cost) and a project life of five years, the gross Process parameters and conditions batch production of eco-fuel briquettes profit margin is 44%, the profitability index is 5.33 and the internal Rate of return 31.44%. The net present value and return period are R676, 896 and 0.408 years respectively. The customer profile as currently at hand is 17% of the selected area within 80 m radius from production site. The remaining 83% will be in need of energy as they become aware of the new product offering. The selling of the briquettes should be accompanied by an education process, to avoid the dangers of heating indoors. The principal driver for this project is socio economic development and it is being strengthened by Eskom’s inability to provide sufficient energy. A secondary driver is the global drive to reduce emissions and fossil fuel usage; this technology does exactly this whilst diverting waste from landfill. In the Polokwane declaration (2008), it is stated that South Africa will have no calorific waste to landfill by 2014. Hence legislation will also provide a major part of the drive.
- Full Text:
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