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Chemical Pretreatment Methods for the Production of Cellulosic Ethanol: Technologies and Innovations
Edem Cudjoe Bensah,Moses Mensah
International Journal of Chemical Engineering , 2013, DOI: 10.1155/2013/719607
Abstract: Pretreatment of lignocellulose has received considerable research globally due to its influence on the technical, economic and environmental sustainability of cellulosic ethanol production. Some of the most promising pretreatment methods require the application of chemicals such as acids, alkali, salts, oxidants, and solvents. Thus, advances in research have enabled the development and integration of chemical-based pretreatment into proprietary ethanol production technologies in several pilot and demonstration plants globally, with potential to scale-up to commercial levels. This paper reviews known and emerging chemical pretreatment methods, highlighting recent findings and process innovations developed to offset inherent challenges via a range of interventions, notably, the combination of chemical pretreatment with other methods to improve carbohydrate preservation, reduce formation of degradation products, achieve high sugar yields at mild reaction conditions, reduce solvent loads and enzyme dose, reduce waste generation, and improve recovery of biomass components in pure forms. The use of chemicals such as ionic liquids, NMMO, and sulphite are promising once challenges in solvent recovery are overcome. For developing countries, alkali-based methods are relatively easy to deploy in decentralized, low-tech systems owing to advantages such as the requirement of simple reactors and the ease of operation. 1. Introduction Cellulosic or second generation (2G) bioethanol is produced from lignocellulosic biomass (LB) in three main steps: pretreatment, hydrolysis, and fermentation. Pretreatment involves the use of physical processes (e.g., size reduction, steaming/boiling, ultrasonication, and popping), chemical methods (e.g., acids, bases, salts, and solvents), physicochemical processes (e.g., liquid hot water and ammonium fibre explosion or AFEX), biological methods (e.g., white-rot/brown-rot fungi and bacteria), and several combinations thereof to fractionate the lignocellulose into its components. It results in the disruption of the lignin seal to increase enzyme access to holocellulose [1, 2], reduction of cellulose crystallinity [3, 4], and increase in the surface area [5, 6] and porosity [7, 8] of pretreated substrates, resulting in increased hydrolysis rate. In hydrolysis, cellulose and hemicelluloses are broken down into monomeric sugars via addition of acids or enzymes such as cellulase. Enzymatic hydrolysis offers advantages over acids such as low energy consumption due to the mild process requirements, high sugar yields, and no unwanted wastes.
Status and prospects for household biogas plants in Ghana – lessons, barriers, potential, and way forward
Edem Cudjoe Bensah, Moses Mensah, Edward Antwi
International Journal of Energy and Environment , 2011,
Abstract: Ghana is a country faced with pressing developmental challenges on energy, sanitation, environment and agriculture. The development of a large scale, enterprise-based biogas programme in Ghana will improve sanitation, produce clean energy, reduce greenhouse gas emissions, promote nutrient recovery, and create jobs. While aforementioned benefits of biogas are known, the biogas industry is still not growing at rates that would enable its impact on sanitation, agriculture and energy usage to be felt, owing to challenges such as low awareness creation and poor biogas supply chain, lack of well-trained personnel, poor follow-up services, and high cost of biogas digesters – USD 235- 446 per cubic meter. This paper looks at the chronology of biogas developmental in Ghana, technical and market potential of household biogas plants, strengths and weaknesses of main biogas service providers, human resource development, quality issues, and risks involved in developing a large scale household biogas programme. From the paper, the technical and market potential of dung-based, household biogas digesters in Ghana are estimated at 162,066 and 16,207 units respectively. In order to take full advantage of biogas technology, the paper recommends the development of standardized digesters, increase in awareness programmes on the life-long benefits of biogas systems, introduction of flexible payment schemes, and stepping-up of follow-up services. Finally, there is an urgent need for a "promoter" who will engage all stakeholders to ensure that a national action plan on biogas technology is initiated and implemented.
Biogas technology dissemination in Ghana: history, current status, future prospects, and policy significance
Edem Cudjoe Bensah, Abeeku Brew-Hammond
International Journal of Energy and Environment , 2010,
Abstract: Despite numerous benefits derived from biogas technology, Ghana is yet to develop a major programme that will promote the dissemination of biogas plants on a larger scale. This paper reviews biogas installations in Ghana and investigates challenges facing the design, construction, and operation of biogas plants. It further captures the current status and functions of biogas plants as well as the impact of these plants on the people who use them. The study was done by surveying fifty (50) biogas installations, and conducting interviews with both plant users and service providers. From the survey, twenty-nine (58 %) installations were institutional, fourteen (28 %) were household units, and the remaining seven (14 %) were community plants. Fixed-dome and water-jacket floating-drum digesters represented 82 % and 8 % of installations surveyed, respectively. It was revealed that sanitation was the main motivational reason for people using biogas plants. Of the 50 plants, 22 (44 %) were functioning satisfactorily, 10 (20 %) were functioning partially, 14 (28 %) were not functioning, 2 (4 %) were abandoned, and the remaining 2 (4 %) were under construction. Reasons for non-functioning include non-availability of dung, breakdown of balloon gasholders, absence of maintenance services, lack of operational knowledge, and gas leakages and bad odour in toilet chambers of biolatrines. This paper recommends the development of a national biogas programme focussing on three major areas – sanitation, energy, and agricultural fertilizer production; it further supports the development of standardized digester models. The founding of a national body or the establishment of a dedicated unit within an existing organization with the sole aim of coordinating and managing biogas dissemination in Ghana is proposed.
Improving Sanitation in Ghana-Role of Sanitary Biogas Plants
Edem Cudjoe Bensah,Edward Antwi,Julius Cudjoe Ahiekpor
Journal of Engineering and Applied Sciences , 2012, DOI: 10.3923/jeasci.2010.125.133
Abstract: This study assesses the state of sanitation in Ghana from a global perspective and discusses policies and strategies for improving sanitation in Ghana. It outlines milestones of biosanitation programmes in Ghana, highlighting socio-cultural, technical and environmental challenges facing dissemination of sanitary biodigesters. The state of twenty sanitary biogas plants at various locations in Ghana is captured and problems and complaints from users are discussed. This study recommends the linking up of public toilets with biogas (anaerobic treatment) digesters as a way of improving communal hygiene and combating hygiene-related communicable diseases including cholera and dysentery. This study, however, cautions that such a project should come into gear only after solution to technical challenges such as inappropriate designs of latrines, inlet channels of biodigesters and effluent disposal systems are found. Social-cultural challenges such as the use of digested slurry in agriculture and irrigation and the use of gas for cooking must also be addressed. This study advocates for the development of a national biosanitation programme aimed at disseminating standardized sanitary biogas plants in Ghana with active involvement of the Community Water and Sanitation Agency and Metropolitan, Municipal and District Assemblies.
Ghana's biofuels policy: challenges and the way forward
Edward Antwi, Edem Cudjoe Bensah, David Ato Quansah, Richard Arthur, Julius Ahiekpor
International Journal of Energy and Environment , 2010,
Abstract: Liquid biofuels have come up strongly as possible substitute to conventional fossils fuels and woodfuels apparently because of its perceived environmental benefit, sustainability and recent hikes in petroleum fuel prices. These have led most countries to include biofuels in their energy mix to mitigate climate change effect caused by petroleum fuels and also to ensure energy security. Ghana as a developing country has also identified the potential of biofuels in her energy mix by setting some targets in its Strategic National Energy Policy (SNEP). This paper analyses the implications of the policy as presented in SNEP. It also looks at programmes put in place to achieve the set objectives and the possible challenges that are likely to be faced in their implementation. The paper concludes by calling for strong governmental involvement in achieving the set objectives.
The nature and effect of sulphur compounds on Co2 and air reactivity of petrol coke
Yaw Delali Bensah,Trygve Foosnaes
Journal of Engineering and Applied Sciences , 2010,
Abstract: Three different single-source coke types (SSA, SSB and SSC) were studied for their air and CO2 reactivities using the Hydro method and the observed correlation with reactivity determinant parameter such as elemental composition was noted. The reaction temperatures were 525 oC and 960 oC for air and CO2 reactivities, respectively. Coke sample SSA recorded the highest CO2 reactivity value of 166 mg/g h while coke sample SSB recorded the lowest value of 25 mg/g h. The coke CO2 reactivity showed a moderately strong correlation with the combined effect of Na, Fe and Ca concentrations. The inhibitory effect of sulphur as a catalytic poison on Na was observed with significant downward trend in CO2 reactivity of the investigated cokes. Coke air reactivities showed the expected strong correlation with V. Air reactivity was highest in sample SSC (262 mg/g h) at V concentration of 378 ppm and lowest in sample SSB (39.6 mg/g h) at V concentration of 68 ppm. Sample SSA recorded reactivity value of 129.6 mg/g h at V concentration of 147 ppm. The compound 1-butanethiol was identified by 1-D 1H NMR and 13C NMR, and by 2-D COSY, HSQC and HMBC NMR spectroscopic techniques. It is proposed that 1-butanethiol is one of the possible organosulphur compounds responsible for the reaction with Na forming a stable non-mobile complex partially inhibiting the catalytic effect of Na.
Analysis of the Implementation of Child Rights Law in Nigeria
AO Udoh, E Edem
African Research Review , 2011,
Abstract: The aim of the study was to analyse the implementation of Child Rights Law in Nigeria so far. To accomplish this: three research questions and three hypotheses were formulated to guide the investigation. Descriptive survey research was employed carrying out the study. Stratified random sampling technique was used to select 1811 respondents comprising 546 Civil Servants, 291 Industrialists and 344 Traders. Data analysed using descriptive statistics and analysis of variance were collected through a questionnaire entitled-implementation of Child Rights Law questionnaire (ICRLQ). The findings indicated that 68.75% of Child Rights Law had been implemented. The implications of these findings were discussed.
Vitamin A: A Review
D.O. Edem
Asian Journal of Clinical Nutrition , 2009,
Abstract: This study provides a comprehensive review on the fat-soluble micronutrient vitamin A, changes in its status among vulnerable groups of different populations and the results of experience with different strategies/interventions designed to improve its status. Vitamin A can be derived from animal sources (preformed in liver, milk, eggs, fatty fish) or plant sources (in fruits and vegetables as provitamin A). The vitamin is required for normal growth and development, playing a part in reproduction, differentiation of cellular epithelium, regulation of cell division, genetic regulation and enhancement of immune responses. Retinol (its basic molecule) is metabolised into a number of biologically active retinoid compounds, such as retinal (active element of visual pigment) and retinoic acid, an intracellular messenger that modulates cell differentiation. Uneven distribution of natural sources of vitamin A, low dietary intake of animal products, the traditional technological transformation/processing of foods, low absorption and limited bioconversion of carotenoids may impact negatively on vitamin A activity. Vitamin A deficiency (VAD), a major public health nutritional problem in many developing countries, results in a range of developmental and pathological states with consequences ranging from potentially blinding xerophthalmia to increased risks of infection and mortality. All alternatives employed towards eradicating VAD (nutrition education, dietary diversification, dietary supplementation and food fortification) have provided a high return on investment in terms of disability-adjusted-life years gained. Key options for action, as well as important areas of research are being discussed. Control of VAD will lead to a substantial improvement in childhood survival and prevent the scandal of irreversible blindness. It is suggested that early introduction of children to abundant natural sources of vitamin A (like red palm oil-prepared meals) be encouraged.
Information Needs and Information Seeking Behavior Patterns of Journalists in Selected Nigerian Town
  U. Selong Edem
Journal of Library and Information Science , 1993,
Abstract: 頁次:1-14
Effects of agricultural credit facility on the agricultural production and rural development
GE Ekwere,ID Edem
International Journal of Environment , 2014, DOI: 10.3126/ije.v3i2.10529
Abstract: Lack of capital has been identified as one of the constraints that faced by small scale farmers. The aim of this research was to examine the effect of agricultural credit on the agriculture production, and calculate the inputs and outputs among small scale farmers. Structured questionnaires were distributed to 136 farmers, who had been selected using the stratified random sampling technique, and the data obtained were summarized into percentages. Regression analysis was adopted to assess the impacts of socio-economic factors on loan size among farmers, while Cobb-Douglas Production Function Analysis (CDPFA) was used to test the relationship between key independent variables such as loan amount, farm size, inputs and farm output as dependent variable. The analysis revealed a significantly high value of coefficient of determination (R2= 0.922) that reflected a high relationship between the dependent variable and the independent variables; gender, age, education, family size, farm size, farming experience. The Adjusted (R2) coefficient (R2 = 0.918) revealed that 91.8 % of variation in loam size explained by the changes in variables. The results showed a significance in F-test in size of loan. The hypothesis two, exhibited that the independent variables; loan size, farm size, and inputs explained the variation in the total value of farmers output. The study therefore showed that to achieve the positive agricultural credit impacts on agricultural production, The Government and the private sector should regularly and timely facilitate the credit to the small scale farmers. DOI: http://dx.doi.org/10.3126/ije.v3i2.10529 International Journal of the Environment Vol.3(2) 2014: 192-204
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