Parametric study of single and double stage membrane configuration in methane enrichment process

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

Operational study and simulation of a biogas upgrading plant

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%

Technology selection and siting of a biogas plant for OFMSW via multi-criteria decision analysis

Abstract: Multi-criteria decision analysis (MCDA) techniques were applied to choose a biogas digester technology and a site from a list of potential alternatives for an anaerobic digestion (AD) system utilising the organic fraction of municipal solid waste (OFMSW) based on a case study at the University of Johannesburg’s Doornfontein campus in South Africa. The simple multi-attribute rating technique (SMART) and analytic hierarchy process (AHP) techniques of MCDA were used to select a suitable biodigester model and site respectively. From a list of 14 biodigester technologies to be established at 1 of 3 potential sites in the study area, the most preferred model was the Puxin digester to be sited near the Aurum ladies’ residence within the school campus to supply biogas for heating purposes

Sizing of an anaerobic biodigester for the organic fraction of municipal solid waste

The anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) for biogas production is a potential solution to the growing challenges associated with municipal solid waste (MSW) management while simultaneously providing an alternative clean energy source. Biogas is produced by the anaerobic digestion (AD) of biomass using microorganisms in specifically designed plants called biogas digesters under controlled conditions or naturally in marshes and landfills. It is a rather clean and versatile fuel as opposed to fossil fuels. To design an efficient AD system, a proper understanding of the quality and quantity of available feedstock must be made as well as prevailing operating conditions. This paper represents steps that were taken to come up with an optimal size of biodigester to treat OFMSW produced at the University of Johannesburg’s Doornfontein Campus in downtown Johannesburg. The campus generates 232.2kg of OFMSW per day which required 30m3 of biodigester capacity

Technology selection of biogas digesters for OFMSW via multi-criteria decision analysis

Multi-criteria decision analysis (MCDA) techniques are becoming increasingly popular in decision making for technology selection because of their ability to capture the multi-dimensionality of technologies. Biogas typically refers to an odourless gas produced by anaerobic digestion of biomass using microorganisms. Its production can occur naturally in marshes and landfills or more commonly, in specifically designed plants called biogas digesters under controlled conditions. For techno-economic efficiency of a biodigester, several factors such as cost of plant are taken into consideration. This paper examines various available technologies for biogas digesters using defined selection criteria via MCDA and chooses the best alternatives at various scales of biogas production for a case study in South Africa with municipal biowaste as the target feedstock. 14 biogas plants were analysed in this study and the Puxin and Bio4gas digesters were the best alternatives for small and large scale biogas production respectively

NOVEL AIRFOIL DESIGN FOR SMALL HORIZONTAL AXIS WIND TURBINE: A PRELIMINARY RESULT

Various research efforts have been directed towards the design and re-design of wind turbine systems. This is in order to have more efficient, better performing and cost effective turbine systems. Based on this, efforts have been focused on wind turbine rotor design with emphasis placed on its aerodynamics. This is because the important criterion of a wind turbine rotor is the airfoil. It is the element that produces the forces that makes the turbine rotate. This research builds on existing knowledge and aims to further deepen knowledge in the field of wind turbine rotor design. The study designed and analysed a new airfoil for use in a small horizontal axis wind turbine. It employed the flow stage airfoil behaviour together with analytical software tools that include XFLR5, AirfoilPrep_v2.02.01, WT_Perf, and MATLAB.. Three well known and tested airfoils were employed and the coordinates were interpolated to create a new, more efficient and better performing small wind turbine rotor airfoil. The outcome showed the new airfoil performs better with good glide ratio over longer angle range, chord distribution and blade twist among other things. The parameters of the new airfoil were such that 10.17%, 26.49%, 6.26% and 45.0% of the chord characterised the maximum thickness and its position, and the maximum camber and its position respectivel

Bio-methane potential of the organic fraction of municipal solid waste

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. ..

AN ASSESSMENT OF DISASTER PREPAREDNESS IN THE LIBRARIES OF SOUTH-WESTERN, NIGERIAN UNIVERSITIES

The paper examines the extent of disaster preparedness in libraries of three South-western Nigerian universities. The survey research method was adopted, randomly administering on a ratio of 1:1:2:3, eighty (80) copies of the questionnaire to staff members of four university libraries. A 73% response rate was recorded and simple frequency tables, Likert Scale aided with summative indexing and Chi square test were used for analyzing the collated data. Four research questions were answered with three universities selected for the population study. There were fifty-eight respondents, made up of 30 males (51.7%) and 28 (48.3%) females.Disaster Likelihood Index (DLI) was used to measure propensity to disaster and of the seven indicators, water leakages (3.89) and faulty power supply (3.15) having the highest index scores, are the most probable sources of disaster. In addition, results reveal that the most available disaster management utilities are fire extinguishers, emergency exits and smoke detectors in the libraries with 90%, 75.9% and 72.4% respectively. The availability of smoke detectors however varies significantly across the libraries and is most available in the Kenneth Dike Library. The level of preparedness was also measured with three main indices, namely: maintenance (MI), adequacy (AdI) and awareness (AwI) of disaster management measures, each with its checklist of indicators. With the mean MI, AdW and AwI being 3.17, 3.03 and 2.82 respectively, awareness on disaster management measures is the lowest scoring index of preparedness, and knowledge of emergency numbers has the least AwI (2.31) among its indicators. The study recommends among others, the installation of utilities like smoke detector, emergency exit doors conspicuously indicated,awareness campaign as well as regular staff training on disaster management, to increase the level of preparedness in all the university libraries

Traditional health practitioners' perceptions, herbal treatment and management of HIV and related opportunistic infections

Background: In South Africa, traditional health practitioners? (THPs) explanatory frameworks concerning illness aetiologies are much researched. However there is a gap in the literature on how THPs understand HIV-related opportunistic infections (OIs), i.e. tuberculosis, candidiasis and herpes zoster. This study aimed to comprehend THPs? understandings of the aforementioned; to ascertain and better understand the treatment methods used by THPs for HIV and OIs, while also contributing to the documentation of South African medicinal plants for future conservation. Methods: The study was conducted in two locations: Strand, Western Cape where THPs are trained and Mpoza village, Mount Frere, Eastern Cape from where medicinal plants are ordered or collected. Semi-structured interviews were conducted with 53 THPs of whom 36 were diviners (amagrirha: isangoma) and 17 herbalists (inyanga). THPs were selected through a non-probability ?snowball? method. Data were analysed using a thematic content analysis approach. An ethnobotanical survey was conducted and plants used to manage HIV and OIs were collected. A complete set of voucher specimens was deposited at the University of the Western Cape Herbarium for identification. Plant names were checked and updated with Kew?s online website http://www.theplantlist.org. Results: THPs conceptualise the aetiology of HIV and OIs at two related levels. The first involves the immediate manifestation of the illness/condition because of a viral infection in the blood (HIV), the presence of bacteria in the lungs (tuberculosis), or weakened state of the body making it susceptible to OIs. The presence of OIs is indicative of the probable presence of HIV. The second level of causation affects the first, which includes pollution, changes in cultural sexual norms, witchcraft, environmental factors, and lack of adherence to ancestral rituals. THPs reported using 17 plants belonging to 12 families. Remedies included mixes of up to five plants. Conclusion: This study explored the THPs? perspectives on HIV and commonly associated OIs and their herbal treatment methods. THPs generally rely on biomedical diagnosis before treating a client. They also seek guidance from the ancestors for a particular diagnosis, the plants to use for a specific treatment, when to harvest, and how to administer herbal remedies