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A proposed maintenance strategy for generator sets utilised in biogas applications

- Gerrard, Alastair Douglas

  • Authors: Gerrard, Alastair Douglas
  • Date: 2012-06-04
  • Subjects: Generators , Biogas , Landfill gas
  • Type: Thesis
  • Identifier: uj:2308 , http://hdl.handle.net/10210/4767
  • Description: M. Ing. , The overall purpose of this research project was to develop a proposed maintenance strategy for generator sets utilised in biogas applications. One specific biogas application, involving the use of landfill gas (LFG) to generate electrical energy, was the focal point of the research project. This is due to the fact that the author’s organisation is extensively involved with landfills and power generation through the use of LFG.
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Biogas production using the organic fraction of municipal solid waste as feedstock

- Kigozi, R., Aboyade, A., Muzenda, Edison

  • Authors: Kigozi, R. , Aboyade, A. , Muzenda, Edison
  • Date: 2013
  • Subjects: Anaerobic digestion , Biogas , Organic fraction of municipal solid waste
  • Type: Article
  • Identifier: uj:4900 , ISSN 2349-1442 , http://hdl.handle.net/10210/12995
  • Description: Biogas typically refers to an odourless gas produced by anaerobic digestion (AD) of biomass using microorganisms. It has an approximate composition of 70-50% Methane (a combustible gas), 30-50% Carbon dioxide and other trace gases depending on the nature of the biomass. The idea of using the organic fraction of municipal solid waste (OFMSW) or simply municipal biowaste as feedstock for biogas production represents an environmentally sustainable energy source since it improves solid waste management while simultaneously providing an alternative clean energy source. Among other applications, the gas can be used for heating, cooking and electricity generation. However, notwithstanding, OFMSW as a feedstock for AD comes with its own unique challenges compared to other forms of biomass. This paper therefore reviews the specific opportunities, challenges and techno-economics of using OFMSW as sole feedstock supply for biogas production.
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A review of biogas production optimization from grass silage

- Muzenda, Edison, Sibiya, Noxolo

  • Authors: Muzenda, Edison , Sibiya, Noxolo
  • Date: 2014
  • Subjects: Biogas , Grass - Silage , Anaerobic digestion
  • Type: Article
  • Identifier: uj:5033 , http://hdl.handle.net/10210/13553
  • Description: Anaerobic digestion (AD) of organic materials offers an alternative source of renewable energy, as bio-methane has a potential to replace fossil fuels for energy production for heat and power, vehicular fuel and as well as valuable material recovery. In addition AD can address pollution problems by minimizing and utilizing biodegradable waste. This is a well-researched and technologically advanced technique with various successful small to large scale plants in the developed world. For developing countries, not much success has been reported due to operational and maintenance challenges, low biogas production and public perceptions among other several contributing factors. This paper reviews AD process optimization focusing on parameters such as temperature, pH, loading rate, hydraulic retention time and agitation. Several studies have shown optimum biogas production from grass in mesophilic, alkaline or neutral conditions at retention times of about 30 days. This review is the background and basis of our current work on optimizing biogas production from selected South African grass species.
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Bio-methane generation from organic waste : a review

- Muzenda, Edison

  • Authors: Muzenda, Edison
  • Date: 2014
  • Subjects: Anaerobic digestion , Biodegradable material , Biogas
  • Type: Article
  • Identifier: uj:4987 , ISSN 2078-0966 , http://hdl.handle.net/10210/13119
  • Description: Anaerobic digestion of organic waste can address both energy recovery and pollution control. A variety of agricultural, industrial and domestic wastes can be anaerobically digested as they contain easily biodegradable material. Biogas contains 50 -70% methane and 30-50% carbon dioxide as well as small a amounts of other gases with calorific value of about 21-24 MJ/m3. This paper reviews the history of biogas, biogas production stages and operating parameters. The anaerobic digestion configuration and potential substrates for biogas production are also considered.
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Bio-methane potential of the organic fraction of municipal solid waste

- Mojapelo, N., Muzenda, Edison, Kigozi, R., Aboyade, A. O.

  • Authors: Mojapelo, N. , Muzenda, Edison , Kigozi, R. , Aboyade, A. O.
  • Date: 2014
  • Subjects: Biogas , Bio-methane , Municipal solid waste
  • Type: Article
  • Identifier: uj:5022 , http://hdl.handle.net/10210/13165
  • Description: Biogas is a gas formed from the breakdown of biomass by microorganisms in an anaerobic environment composed of methane (50%–70%) and carbon dioxide (30%–50%). The upgrading of biogas by the removal of carbon dioxide to increase the percentage of methane to over 92% produces bio-methane which is a potent versatile clean fuel. This paper represents a study that was carried out at the University of Johannesburg’s Doornfontein Campus (UJ DFC) to ascertain the potential of bio-methane recovery from the organic fraction of municipal solid waste (OFMSW) collected at the campus’ cafeteria and student residences. ...
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Effect of nutrient addition during anaerobic digestion of potato peels and maize husk

- Ramatsa, Ishmael, Sibiya, Noxolo, Huberts, Roberth

  • Authors: Ramatsa, Ishmael , Sibiya, Noxolo , Huberts, Roberth
  • Date: 2014
  • Subjects: Anaerobic bacteria , Renewable energy sources , Biomass energy , Biogas
  • Type: Article
  • Identifier: uj:5091 , http://hdl.handle.net/10210/13681
  • Description: The composition of the substrate and nutrients addition plays a very significant role during the production of the biogas. For this reason this paper tries to evaluate the effect of nutrients addition during biogas production under anaerobic conditions. Potato peels wastes and maize husk were anaerobically digested in a 5 liter scale reactor at mesophilic conditions (32 o C). The characteristics of the potato peels were and maize husk are presented in Table 1. The results obtained indicated that the addition of the nutrients during anaerobic digestion has an influence on the biogas production, meanwhile methane content in biogas varied from 48 to 64%.
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Effect of temperature and pH on the anaerobic digestion of grass silage

- Sibiya, Noxolo T., Muzenda, Edison, Tesfagiorgis, Habtom B.

  • Authors: Sibiya, Noxolo T. , Muzenda, Edison , Tesfagiorgis, Habtom B.
  • Date: 2014
  • Subjects: Biogas , Anaerobic digestion , Grass - Silage , pH (Chemistry) , Anaerobic digestion - Effect of temperature on
  • Type: Article
  • Identifier: uj:5051 , http://hdl.handle.net/10210/13590
  • Description: The operating temperature and pH level in the digester during anaerobic digestion and the retention period are among the major factors that affect the rate of biogas production. Therefore, this paper evaluates the effects of temperature and pH in anaerobic digestion of grass silage. Grass silage was digested in 1000ml at different temperatures (35 ○C, 40 ○C, 45 ○C and 50 ○C) and pH (6.5, 6.8 &7.2). The digesters were shaken everyday to prevent the formation of surface crust which may prevent contact between microorganisms and the substrate. The characteristics of grass and cow dung and the optimal retention time are also reported. The results show that as the temperature was increased the biogas production and methane was also increased, however the high amount of biogas production rate and methane content was observed in the digester operated at 45 ○C and pH of 6.5. The process was carried out for 11days; however the optimal hydraulic retention time for digester that had high biogas was 8 days.
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Enrichment of biogas for use as vehicular fuel: a review of the upgrading techniques

- Masebinu, S. O., Aboyade, A., Muzenda, Edison

  • Authors: Masebinu, S. O. , Aboyade, A. , Muzenda, Edison
  • Date: 2014
  • Subjects: Biogas , Biogas enrichment
  • Type: Article
  • Identifier: uj:4912 , ISSN 2349-1442 , http://hdl.handle.net/10210/13012
  • Description: Biogas, a renewable energy, can be captured, upgraded and used to fuel a vehicle as an alternative to fossil fuel, thus, reducing greenhouse gas emission. Biogas is environmentally hazardous if emitted directly into the environment. Increasing demand for bio-methane to be used as vehicular fuel has called for efficient use of waste and technology that is optimal yet economical. Biogas in its raw state contains impurities that reduce its heating value to be used directly as fuel, hence, a need to enhance it by upgrading to bio-methane. Several techniques exist for upgrading biogas to bio-methane. This paper present four upgrading techniques; absorption, adsorption, membrane and cryogenic techniques, a brief theoretical background, advantages and operational issues associated with each technique.
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Municipal solid waste utilisation for green energy in Gauteng province - South Africa : a review

- Pilusa, Tsietsi J., Muzenda, Edison

  • Authors: Pilusa, Tsietsi J. , Muzenda, Edison
  • Date: 2014
  • Subjects: Biogas , Solid waste management - South Africa - Johannesburg , Green energy
  • Type: Article
  • Identifier: uj:4958 , http://hdl.handle.net/10210/13059
  • Description: This short paper discusses the potential of utilizing various municipal solids waste streams as feed stock for green energy production. These waste streams includes but not limited to mixed combustible waste, rubber and plastic waste, health care risk waste, organic biodegradable waste, biomass and sewage sludge. Technologies such as anaerobic digestion, gasification and pyrolysis have been reviewed relative to the location and waste stream quantities in the selected sample area. It was discovered that there are environmental, social and economic benefits in waste to energy approach for the waste streams reviewed. The feasibility of implementing such technologies is mainly dependent on the initial capital investment and operational cost of the facility. Other factors include the size of the waste stream, product price and demand.
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Operational study and simulation of a biogas upgrading plant

- Masebinu, S. O., Aboyade, A. O., Muzenda, E.

  • Authors: Masebinu, S. O. , Aboyade, A. O. , Muzenda, E.
  • Date: 2014
  • Subjects: Gas permeation , Biogas , Methane recovery
  • Type: Article
  • Identifier: uj:5020 , http://hdl.handle.net/10210/13163
  • Description: The drive for finding alternative energy to supplement fossil based fuel within the South African energy sector has led to research on waste to energy in particular biomethane as vehicular fuels. Biogas is produced from the anaerobic decomposition of organic matter with 40-70% vol. of methane. Biogas if upgraded, by removing the non-combustible component, can achieve 99% methane concentration which makes it a potent vehicle fuel and a direct substitute to natural gas. In this paper, a biogas upgrading plant operation that uses gas permeation technique for methane enrichment of biogas was studied and simulated. The effect of recycling permeate stream on methane recovery was studied. Recycling of the permeate stream improved the methane recovery of the simulated process by 18%. The overall methane recovery of the simulated process is 81.23%.
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Parametric study of single and double stage membrane configuration in methane enrichment process

- Masebinu, S. O., Aboyade, A. O., Muzenda, E.

  • Authors: Masebinu, S. O. , Aboyade, A. O. , Muzenda, E.
  • Date: 2014
  • Subjects: Biogas , Methane enrichment , Membrane configuration
  • Type: Article
  • Identifier: uj:5003 , http://hdl.handle.net/10210/13143
  • Description: Operational study of a biogas upgrading plant with cleaning and methane (CH4) enrichment has been presented in this study. Parametric study was conducted to investigate the effect of variation of process conditions for single stage without recycle (SSWR) and double stage with permeate recycle (DSPR) on product purity, CH4 recovery and compression power requirement. In the study, achieving high CH4 recovery and product purity simultaneously could not be attained in SSWR configuration. The performance of DSPR yielded a better result but with higher membrane area and compression power. DSPR configuration achieved high CH4 recovery and purity at increasing feed pressure, selectivity and feed flow. The CH4 losses increased in both configurations as %CO2 increased in the feed. DSPR configuration is considered the best configuration due to the end use of the product, as vehicular fuel, which requires high product purity.
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Influence of digestate recirculation and recirculation percentage on biogas production from lawn grass via anaerobic digestion

- Sibiya, Noxolo T., Tesfagiorgis, Habtom B., Muzenda, Edison

  • Authors: Sibiya, Noxolo T. , Tesfagiorgis, Habtom B. , Muzenda, Edison
  • Date: 2015
  • Subjects: Biogas , Digestate , Recirculation
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/72893 , uj:18343 , Citation: Sibiya, N.T., Tesfagiorgis, H.B. & Muzenda, E. 2015. Influence of digestate recirculation and recirculation percentage on biogas production from lawn grass via anaerobic digestion.
  • Description: Abstract: Recirculation of digestate either in the form of liquid or solids has proven to enhance biogas production from energy crops including lawn grass. The explanation to this is that digestate contains suitable bacteria and trace elements (nutrients) needed by methanogens. Influence of digestate recirculation and recirculation percentage in biogas production from lawn grass via anaerobic digestion was studied in laboratory scale digester (1L plastic bottles) at mesophilic condition. Three scenarios were used: digester without recycle digestate (control) (WRD), digesters with recycled liquid digestate (RLD) and digesters with recycled solid digestate (RSD). Liquid recycled digestate was added in percentages variation ranging from 10%-60%, solid recycle digestate was added in percentages variation ranging from 10%-50%. The maximum biogas production with methane content of 55% was obtained in the digester with 60% RLD on the 8th day. During the study of recirculation of solids, highest biogas yield with methane content of 53% was observed in a digester with RSD of 40% on the 5th day. Retention time for both digesters with recycled digestate was reduced and biogas production rate was increased compared to the digester with no recycled digestate.
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Studies on the improvement of biogas production from anaerobic digestion of animal wastes

- Sebola, Mmabyalwa Rebecca

  • Authors: Sebola, Mmabyalwa Rebecca
  • Date: 2015
  • Subjects: Biogas , Sewage - Purification - Anaerobic treatment , Renewable energy sources , Biomass energy
  • Language: English
  • Type: Master’s Thesis
  • Identifier: http://hdl.handle.net/10210/57296 , uj:16377
  • Description: Abstract: The unsustainability of intensive reliance on fossil fuels and none-renewable resources as the main sources of energy, frequent rises in energy prices, the need for climate change mitigation and environmental protection have intensified the need for green energy. In this respect, green energy, in the form of biogas, has gained increased attention as a cost effective and environmentally cautious approach. This dissertation presents various studies aimed at improving the biogas production from anaerobic digestion of animal wastes. The experiments were conducted using the batch scale mesophilic tests. Characterisation studies (ultimate and proximate analysis) were conducted to identify key characteristics of the selected feedstocks. In addition, an economic assessment on the feasibility of anaerobic technology was conducted. The waste had average moisture content (MC) ranging from 7 – 34% and 70 – 81% for the dry and wet samples, respectively. The average volatile matter (VM) varied between 44 – 58% with the C/N for CD, CM, PM and SW being 26.20, 8.13, 17.64 and 8.57, respectively. Decreasing the particle size of the feedstock increased the amount of biogas significantly by increasing the total surface area of the material exposed to the anaerobic microbes. At optimal particle size (25μm), methane production was 3 – 30 % higher as compared to that of 100μm and above. Highest methane yields were achieved from CD to CM, PM and SW at ratio of 1:1:1:1. At optimum temperature (40˚C), the highest methane yield (62% CH4/ d) was obtained on Day 6. Adding 50% VS resulted in more methane yields (64% CH4/d) than 30 and 40%. An introduction of 40% recycled liquid and 60% fresh water to the digester gave the best performance, with 73% CH4/d of biogas produced within 5 days. Soaking the feedstock prior digestion improved both the methane and biogas yields and stability of the process. An economic evaluation over a period of 5 years with 8 hours daily operation and a breakeven of 1.5 years was assessed. The proposed model has debt repayments of R 2,478,551 with the total revenue from years 2 – 5 being R 2,360,800, R 2,930,158, R... , M.Tech. (Chemical Engineering)
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Technology selection and siting of a biogas plant for OFMSW via multi-criteria decision analysis

- Kigozi, R., Aboyade, A. O., Muzenda, E.

Biogas production from anaerobic digestion of fruit and vegetable waste from Johannesburg market

- Maile, Ireen, Muzenda, Edison, Mbohwa, Charles

Biogas purification and upgrading for vehicular fuel application

- Maile, Olivia Ireen

  • Authors: Maile, Olivia Ireen
  • Date: 2016
  • Subjects: Reneable energy sources , Biogas , Biomass energy
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/243015 , uj:25082
  • Description: M.Tech. (Chemical Engineering) , Abstract: Energy is used in the form of electricity, heat, and fuel for lighting, cooking, transportation, and manufacturing of different kind of products. South Africa has faced a long-term struggle on energy shortages which may be related to the 20% growth in the country’s electricity consumption and underinvestment on energy. Thus, the need for producing clean energy from alternative renewable and sustainable energy sources remains an attractive technology. Biogas is energy produced by anaerobic digestion of biodegradable organic waste such as garden waste, food waste, municipal waste, industrial waste and sewage sludge. However, it may not be fully exploited because it contains impurities which limit its application. It can be purified and upgraded using techniques such as high-pressure water scrubbing, pressure swing adsorption, membrane separation, activated carbon sieve, cryogenic separation, chemical absorption. This study focuses on chemical absorption as it can yield biogas with over 95 % CH4 by volume. The substrate used to produce biogas in this study was grass inoculated with cow dung. Sodium hydroxide and acetic acid were used to adjust the pH of the feedstock. The chemicals absorbents of focus are sodium hydroxide, potassium hydroxide, ammonia solution and monoethanolamine. Two kinds of setups were used for this study; biochemical methane potential (BMP) assay tests using the Bioprocess Control AMPTS II and a custom made setup using Buchner flasks. Gas Chromatography was used for biogas analysis. The raw biogas contained on average 52% CH4 by volume which improved to over 80% CH4 after CO2 absorption. The CO2 removal efficiency improved from 22% to 66% for the alkalis and was also quite comparable for MEA and NH3 as it increased from 51% to 67%. The removal efficiency for NH3 and MEA increased from 69% to 79% on average with CH4 concentration reaching over 85% volume at 40 °C. The achievable calorific value for this study ranged from 25 to 33.5 MJ/Nm3.
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Biogas use as fuel in spark ignition engines

- Kukoyi, T.O., Muzenda, E., Akinlabi, Esther Titilayo, Mashamba, A., Mbohwa, Charles, Mahlatsi, T.

Mathematical modelling for biogas production

- Matheri, Anthony Njuguna

  • Authors: Matheri, Anthony Njuguna
  • Date: 2016
  • Subjects: Sewage - Purification - Anaerobic treatment , Sewage - Purification - Mathematical models , Renewable energy sources , Biomass energy , Biogas
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/213006 , uj:21066
  • Description: Abstract: The main focus of this dissertation is the experimental, modelling and simulation of anaerobic digestion processes from pilot bio-digesters. For this purpose, biochemical kinetic models were utilized together with corresponding simulation software; DYNOCHEM. By application of the anaerobic digestion (AD), different parameters have been investigated and simulated including adjustments of the process model and corresponding modifications. To validate the process model, the modelled data was compared with experimental monitored laboratory results. Bio-chemical kinetics modelling was applied as a systematic tool in order to support the process design and optimization of a demonstration of the biogas processes which constitutes the main scientific framework and background of this dissertation. Monitored laboratory-scale biogas production data were used for parameter calibration in order to predict plant performance. The calibration focused on the influent characterization of both substrates and on selection of kinetic of the coefficients in order to generate a uniform set of parameters which are applicable for the simulation of codigestion. In this study, it was observed that the experiment work under laboratory scale using conventional bio-methane potential (BMP) analyzers under mesophilic optimum temperature of 35 oC and 37 oC, and pH of 7 for co-digestion of organic fraction of municipal solid waste (OFMSW) with cow dung and manure with grass clippings. The substrate characterization moisture content ranged from 60-95%, volatile content 55-95%, total solid 10-90% and carbon to nitrogen ratio 16-20 for manure and 5-15 for OFMSW. All trace elements concentration were below the threshold of 32 mg/l that leads to inhibition of micro-organisms activity. The rate of conversion increased with retention time. According to the findings, 54-62% of methane composition was evaluated. The kinetics constant evaluated ranged from 0.009-0.35 d-1 and coefficient of determination (R2) ranged from 0.9989-0.9998. The Michaelis-Menten and Monod models provided goodness of fit of 0.9997 with confidential level of 95%. The simulations confirmed that the rate of conversion increased as temperature increases and conversion of reactants increased with retention time, until an equilibrium state was reached. The AD process modelling using DYNOCHEM was successfully modified and implemented to account for unsteady operation which is generally the case of full-scale reactor by developed methodology. , M.Tech. (Chemical Engineering)
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Municipal solid waste from landfills a solution to energy crisis in South Africa

- Dada, O.R., Mbohwa, Charles

  • Authors: Dada, O.R. , Mbohwa, Charles
  • Date: 2016
  • Subjects: Biogas , Landfill , Sustainable development
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/215015 , uj:21353 , Citation: Dada, O.R & Mbohwa, C. 2016. Municipal solid waste from landfills a solution to energy crisis in South Africa.
  • Description: Abstract: There is a growing interest in the management of municipal solid waste globally, and South Africa is also not relenting in its effort to turning wastes from landfill into resourceful materials or energy because of the environmental issues and job opportunities that arises from the wastes generated from household to industrial by-products. Due to the escalating increase in the cost of dumping wastes into landfills and depletion of land spaces despite the popular global campaign of waste reduction, re-use and recycling there is still a rapid increase in the tonnage of wastes that is being produced on daily basis from all works of life which results in huge quantity of waste that is disposed to landfills. This calls for an urgent need to look into possible ways of managing wastes better in such a manner that it contributes and promotes sustainable socio - economic development of the nation. This research paper focuses on the type of waste generated from the City of Johannesburg, the potential biomethane that could be produced from the organic wastes, waste collection methods around the city before disposal on landfills within the City of Johannesburg and investigation of energy generation from waste as a better waste management technique. Robinson deep landfill which is one of the biggest landfill site within the city in terms of capacity is located in the South of Johannesburg. This landfill is a potential site for the establishment of a biogas plant where landfill wastes is expected to be used as feedstocks for the production of biogas. The biogas produced will be further upgraded to biomethane for powering the City of Johannesburg metro buses.
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Performance and emission evaluation of a bi-fuel car

- Kukoyi, Temitope Oladayo

  • Authors: Kukoyi, Temitope Oladayo
  • Date: 2016
  • Subjects: Alternative fuel vehicles , Spark ignition engines - Alternative fuels , Motor fuels , Biogas , Renewable energy sources
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/242306 , uj:24988
  • Description: M.Ing. (Mechanical Engineering) , Abstract: A fundamental shift towards alternative sources of energy particularly in the transport sector has led to the use of fuels such as liquefied petroleum gas and natural gas in spark ignition (SI) engines. However, these fuels retain the challenges associated with fossil fuels which are primarily their finite reserves and negative effects on the ecosystem. This study assesses the use of biogas, a renewable and environmentally friendly high octane fuel in the more popular spark ignition powered passenger vehicle using the simplest single-point fuel delivery conversion kit available on the market. The vehicle powered by a 1.5 litre 1UF-ZE spark ignition engine was converted to a bi-fuel vehicle. Torque, power, and transient emissions were measured with a single roller chassis dynamometer and a gas analyser while running on vehicle quality biogas also referred to as biomethane. The data collated from the use of biogas was pitched with that of petrol in the same system to compare performance and tailpipe emissions. The biogas was simulated by mixing 95% methane (CH4) with 5% carbon dioxide (CO2). The experiments also afforded the opportunity to validate biogas similarity with natural gas (CNG) when used to power vehicles. The research further looked into enhancing system efficiency by investigating the addition of a measure of 2% hydrogen to create a biomethane-hydrogen mix (HCBG) which is within allowable limits of the mix used in a conventional spark ignition (SI) system to curb the negative impacts associated with hydrogen use as a fuel in internal combustion engines. The HCBG was derived by mixing 93% CH4 with 5% CO2 and 2% H2. Biogas recorded a reduction of 16% in maximum power and torque values when pitched with petrol while similar maximum power and torque values to that of biogas were derived from the experiments using natural gas to power the same vehicle. When the hydrogen-biomethane mix was utilised, a 1% power drop was noticed. However, slight increments in power and torque values at mid-speed ranges showed promise for higher hydrogen concentrations in the HCBG in fine-tuned systems. With respect to the mass emission of pollutants, the Inspection and Maintenance 240 (IM240) Drive Cycle was employed to determine the carbon dioxide (CO2), carbon monoxide(CO), hydrocarbon (HC), nitrous oxide (NOx) values in grammes per kilometer (g/km). Biogas recorded an 18% CO2 emission reduction compared to the data obtained using petrol (152.2 g/km). With reference to biogas, CNG recorded 0.4 g/km more CO2 mass emissions while the enhanced HCBG...
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