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Collard F.-X.,International Institute for Water and Environmental Engineering | Mateke J.-A.N.,International Institute for Water and Environmental Engineering | Blin J.,International Institute for Water and Environmental Engineering | Blin J.,CIRAD - Agricultural Research for Development
Fuel | Year: 2012

In previous work, we showed that two-step biomass pyrolysis, consisting of a first low temperature step (T = 360°C, so a low actual heating rate) until the mass loss of the solid reached approximately 50%, followed rapidly by a high temperature step (T > 600°C, so a high actual heating rate) led to optimize charcoal yields with values of up to 40%. In this paper, we describe thermogravimetric analysis studies on eucalyptus wood and its three constituents, i.e. cellulose, xylan and lignin, in order to explain the phenomena behind these results. Two-step pyrolysis experiments were conducted in a TGA oven up to 900°C with a first slow pyrolysis step at a low heating rate of 2°C min -1, followed by a fast pyrolysis step with a heating rate of 100°C min -1. Char yields from eucalyptus wood were increased from 18.8%, for the simple 2°C min -1 pyrolysis, up to 22.8% when the heating rate change was operated at a temperature of 360°C. Char yield from cellulose was also increased, though only very slightly, when the heating rate was changed in the 330-360°C temperature range. Conversely, char yield obtained from xylan and lignin in two-step pyrolysis was always lower than that obtained by simple 2°C min -1 pyrolysis. It appeared from this work that two-step pyrolysis of the eucalyptus sample could not be regarded and described as the result of the sum of the pyrolysis of its constituents. There was a matrix effect with interactions that promoted char formation during two-step pyrolysis. © 2012 Elsevier Ltd. All rights reserved.

Vinai R.,International Institute for Water and Environmental Engineering | Lawane A.,International Institute for Water and Environmental Engineering | Minane J.R.,International Institute for Water and Environmental Engineering | Amadou A.,SONICHAR S.A.
Construction and Building Materials | Year: 2013

This paper presents the results of an experimental investigation on compressive strength of unfired compressed brick obtained with coal combustion residues (CCRs) produced by the Niger Coal Society. Preliminary physical and optical (XRD and SEM) characterisation of coal slag, including lixiviation tests, have been carried out. Cement powder, lateritic clayey soil and sand have been chosen as stabilizing agents for bricks. 12 dosages have been tested and about 300 bricks have been produced with a hand-operated press. Results show uniaxial compressive strengths (UCSs) ranging from 4 MPa to 27 MPa for the highest cement stabilisation ratio. UCS higher than 7.5 MPa have been observed for stabilisation with 20% of laterite +10% cement after 45 days of curing. Obtained bricks showed good mechanical resistance and low weight. No health threat has been detected for the obtained samples. Study developments are oriented towards the analysis of Pozzolanic properties of CCRs, properties of hydrated lime stabilisation, thermal properties and durability assessment.© 2012 Elsevier Ltd. All rights reserved.

Tatsidjodoung P.,International Institute for Water and Environmental Engineering | Dabat M.-H.,Center International de Recherche Agronomique Pour le Developpement | Blin J.,International Institute for Water and Environmental Engineering
Renewable and Sustainable Energy Reviews | Year: 2012

In many African countries, the upswing in oil prices is one factor that favours the adoption and implementation of a national biofuel policy. This trend has a major impact on state budgets and domestic trade balances, while also limiting the access of rural inhabitants to modern energy services. Contribution of biofuels in stabilizing the energy sector, influences ongoing negotiations on the global dynamics of climate change, the reduction in greenhouse gas (GHG) emissions and sustainable development. The question of biofuels as an alternative energy thus depends on international, national and local considerations. Biofuels represent opportunities, e.g., energy independence and security, new national income and employment sources, as well as potential food security problems. African policy makers therefore need to make the right choices to guide the development of biofuel production and use. This article aims to support the development of a biofuel policy by reviewing the latest technical, economic, environmental and social knowledge so as to be able to evaluate the potential and limits of biofuels in Burkina Faso. © 2012 Elsevier Ltd. All rights reserved.

Azoumah Y.,International Institute for Water and Environmental Engineering | Ramde E.W.,Solar Energy Application Laboratory SEAL | Tapsoba G.,International Institute for Water and Environmental Engineering | Thiam S.,International Institute for Water and Environmental Engineering
Solar Energy | Year: 2010

Selecting a site that meets the technical requirements for a concentrating solar power plant (CSP) is a very critical exercise. This paper points out crucial factors and provides guidelines regarding the selection of suitable sites. It especially focuses on Sahelian countries which have their own climatic peculiarities. These countries, characterized by low access to electricity, are well endowed in solar resources. They are potentially good locations for concentrating solar power plants since their mean daily solar radiation exceeds 5.5kWh/m 2. CSP presents therefore, a good opportunity for them to increase in a sustainable manner, their energy supply. The guidelines developed in this paper are applied to Burkina Faso as a case study. © 2010 Elsevier Ltd.

Richardson Y.,CIRAD - Agricultural Research for Development | Richardson Y.,Montpellier University | Motuzas J.,Montpellier University | Julbe A.,Montpellier University | And 3 more authors.
Journal of Physical Chemistry C | Year: 2013

In order to promote process intensification in syngas production from biomass gasification, our research team has already considered the integration of transition metal-based nanocatalysts in the biomass feedstock through its impregnation with metal salt aqueous solutions. The purpose of this work is to provide new insights into the complex physicochemical and catalytic mechanisms involved in this catalytic pathway from nickel salt. Applying a primary vacuum during impregnation allowed the rate of nickel insertion to be optimized and the generation of strong interactions between the metal cations and the lignocellulosic matrix. During biomass pyrolysis, Ni0 nanoparticles (NPs) form in situ below 500 C through carbothermal reduction and provide the active sites for adsorption of aromatic hydrocarbons and subsequent catalytic conversion. In order to test whether it was possible to improve the catalytic efficiency of Ni0 NPs by making them available right from the pyrolysis onset, some preformed Ni0 NPs were inserted into the biomass prior to pyrolysis. The in situ generated Ni0 NPs exhibit higher catalytic efficiency, particularly for aromatic tar conversion, than preformed Ni0 NPs. The high decrease in hard-to-destroy aromatic hydrocarbons formation during pyrolysis is of particular interest in the overall gasification process. The proposed catalytic strategy reveals promising for simplifying the cleaning up of the producer gas. © 2013 American Chemical Society.

Richardson Y.,International Institute for Water and Environmental Engineering | Blin J.,International Institute for Water and Environmental Engineering | Blin J.,CIRAD - Agricultural Research for Development | Julbe A.,Montpellier University
Progress in Energy and Combustion Science | Year: 2012

Application of the process intensification concept to biomass gasification is relatively recent, but is arousing growing interest by providing true opportunities for developing cost-effective high quality syngas, particularly for small to medium-scale installations, adapted to the economic context of most regions in the world. In this highly swarming context towards process intensification, this article provides an overview of the different strategies which are reported in the literature to perform syngas or H 2 purification and conditioning into the gasifier. A promising avenue towards process intensification consists in integrating several functionalities into suitable fluidized bed gasifiers, such as catalytic tar cracking/reforming, CO 2 elimination, H 2 separation and the elimination of particles and other contaminants. The development of new catalytic integrated gasification concepts is also proposed to achieve high conversion performances while pursuing significant process intensification. This strategy is illustrated by relevant examples such as the design of short contact time partial oxidation catalytic reactors, the implementation of specific reaction media such as supercritical water or molten metal, or the realisation of a close contact between solid catalysts and lignocellulosic biomass. Most of these different technologies are not mature yet and research effort has to be performed for optimizing each of these approaches, calling for a multidisciplinary and multi-scale approach integrating catalysis, chemistry, reaction and process engineering. The design of new advanced gasification reactor concept still has to be pursued in order to achieve the challenging one-step production of a high quality syngas from biomass gasification. The implementation of such innovative biomass gasification breakthrough concepts could be one of the most promising ways of process intensification resulting in a significant cut down of the production costs of synthesis gas and H 2 derived from biomass. Graphical abstract: Application of the process intensification concept to biomass gasification is a promising way to cut down the production costs of synthesis gas and H 2 derived from biomass and requires a multidisciplinary and multi-scale approach integrating catalysis, chemistry, reaction and process engineering. © 2012 Elsevier Ltd. All rights reserved.

Hanff E.,International Institute for Water and Environmental Engineering | Hanff E.,CIRAD - Agricultural Research for Development | Dabat M.-H.,CIRAD - Agricultural Research for Development | Blin J.,International Institute for Water and Environmental Engineering | Blin J.,CIRAD - Agricultural Research for Development
Renewable and Sustainable Energy Reviews | Year: 2011

This paper discusses the opportunity for substituting fossil fuels with biofuels in a Sahelian country, Burkina Faso. Bearing in mind the strong link between energy and development, and given the country's heavy reliance on imported fossil fuels, our study showed that the overall economy (private and public companies and basic social services) and the State Budget could be seriously affected if no viable and local alternative is integrated into the national energy strategy. In view of local potential, it is recommended that adequate energy resources be sought in order to ensure sustainable socio-economic development. Biofuel opportunities are discussed taking into account technical, agronomic and land potentials in this country. Diversification of energy resources with biofuels would substantially reduce fuel imports in the short term, improve overall public finances, provide a chance to develop agriculture and provide benefits for the locals. However, if they are to generate development, biofuel projects need to be mindful of food security and economic incentives, and should be part of national agricultural strategies. © 2011 Elsevier Ltd. All rights reserved.

SouDakoure M.Y.,Ecole Polytechnique Federale de Lausanne | SouDakoure M.Y.,International Institute for Water and Environmental Engineering | Mermoud A.,Ecole Polytechnique Federale de Lausanne | Yacouba H.,International Institute for Water and Environmental Engineering | Boivin P.,University of Applied Sciences and Arts Western Switzerland
Geoderma | Year: 2013

Wastewater reuse in agriculture is a widespread practice in developing countries, especially in urban areas where water shortage and poverty encourage people to use that marginal resource. Raw or treated wastewaters are used by farmers, but even treated wastewaters frequently do not meet WHO and FAO standards for irrigation water. Such practices may lead to health hazards, relatively well documented in the literature and to environmental damages. Adverse environmental impacts such as soil degradation and groundwater contamination are frequently associated with the use of wastewater from industrial sources. Previous studies have demonstrated that wastewater irrigation may decrease soil hydraulic conductivity and infiltration rate. Nevertheless, the effects on soil structural and chemical behaviors have been little studied so far and need further investigations.The impacts of irrigation with alkaline and sodic industrial wastewater previously treated in microphyte ponds on soil physical and chemical properties were studied downstream the sewage treatment plant of Kossodo in Ouagadougou, on plots cropped with eggplants. Plots irrigated with fresh water and non cropped, non irrigated plots were used as controls.Different soil properties were characterized: pore volumes determined by using shrinkage analysis, pH and electrical conductivity of water extracts, and major soluble and exchangeable cations (Ca, Mg, K, and Na). Organic matter characterization was performed by means of three dimensional fluorescence spectra analysis to determine its origin and evolution on irrigated soils.Plots irrigated with wastewater showed important structural damages, especially in the subsurface horizon where the soil pore network collapsed dramatically, resulting in a compact impermeable layer. Fluorescence spectra revealed that the organic matter contained in the wastewater was largely dissolved due to a sharp soil pH increase, resulting in black alkali formation at the surface; the soil became sodic, with an exchange complex dominated by sodium, whereas plots irrigated with fresh water kept properties comparable to that of non irrigated plots. Such a rapid soil sodication was seldom reported so far. The study emphasizes the need to carefully examine irrigation water quality and particularly calcite residual alkalinity and suggests that shrinkage analysis could be used to monitor the physical changes of soil properties upon sodication. Inadequate wastewater quality is likely to cause deep and irreversible damages to irrigated soils. © 2013 Elsevier B.V.

Zorom M.,International Institute for Water and Environmental Engineering | Zorom M.,University of Ouagadougou | Barbier B.,International Cooperation Center for Agronomic Research | Mertz O.,Copenhagen University | Servat E.,Montpellier University
Agricultural Systems | Year: 2013

Sahelian farmers tend to diversify their activities to reduce their vulnerability to external shocks. It is important to distinguish between farmers' types response to these shocks as well as to policy incentives. To develop a typology of farmer adaptation strategies, evaluate the level of vulnerability and assess perceptions of policies, two detailed questionnaire surveys were conducted in a community in northern Burkina Faso. Statistical analysis included a cluster analysis to distinguish farmers' types with regard to their assets and strategies. The results show that the main factors of discrimination were family size, access to small irrigation plots and number of animals. The types react differently to climate variability and are likely to follow contrasting pathways of adaptation. Farmers' food vulnerability is still high according to the applied CILSS vulnerability index, and farmers are pessimistic about their capacity to handle future droughts. They see improved credit schemes and further development of irrigation as the most promising adaptation strategies. © 2012 Elsevier Ltd.

Ito R.,International Institute for Water and Environmental Engineering | Takahashi E.,Hokkaido University | Funamizu N.,Hokkaido University
Environmental technology | Year: 2013

Human excreta, especially urine is rich in nitrogen that can be utilized for agricultural purposes, while the slow-release fertilizer allows effective utilization of nutrients in agricultural production. The direct formation of slow-release fertilizer--methylene urea--from urine was being proposed in this study. The experiments were tried to prove formation of methylene urea from human urine, and to investigate the effect of pH and salt concentration on the reaction rate. The synthetic urine and real urine were used for the urea source of the reaction. As a result, the precipitates were prepared from synthetic urine, while the small molecule fractions generated then they grew into precipitate. The nuclear magnetic resonance, infrared spectroscopy, element analyses showed the precipitates in synthetic urine were the same compound found in the urea solution, which was methylene urea. The reaction rate was high at low pH value. The reaction rate in the buffer solution was lower than the synthetic urine at the same pH, because some salts may work as a catalyst. The urea concentration reduction rate in real urine showed the same trend with synthetic urine at the same pH, while the precipitation was quite similar to methylene urea.

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