References of "Adam, Gilles"
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See detailComparison of Indicators to Evaluate the Resilience of Lab Scale Continuously Stirred Anaerobic Reactors Submitted to Biological Dysfunctions
Lemaigre, Sébastien; Adam, Gilles ULg; Goux, Xavier et al

Poster (2014, June 02)

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See detailOdour emissions impact of on-farm biogas production with co-digestion : a case study in four European farms of the Great Region
Adam, Gilles ULg; Gennen, Jérome; Ubeda Sanchez, Yolanda et al

Conference (2013, December 06)

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See detailRecursive PCA of e-nose data for anaerobic digestion reactor state monitoring
Adam, Gilles ULg; Lemaigre, Sébastien; Romain, Anne-Claude ULg et al

Poster (2013, July)

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See detailMulti-method monitoring of odor emissions in agricultural biogas facilities.
Nicolas, Jacques ULg; Adam, Gilles ULg; Ubeda, Yolanda et al

in Proceedings of the 5th IWA conference on odours and air emissions, San Francisco, USA, March, 4-7, 2013 (2013, March)

The production of farm-based biogas and electricity is an area of alternative-energy interest to many livestock producers. However, it is still insignificant in comparison to the maximum potential of ... [more ▼]

The production of farm-based biogas and electricity is an area of alternative-energy interest to many livestock producers. However, it is still insignificant in comparison to the maximum potential of farms all over the world. Market penetration should involve better confidence in the technique and better understanding of its possible assets and limits. For instance, is the environmental impact of biomethanation positive or negative? What are the possible ways to avoid or to control process imbalances? In the context of a European project, the research group attempted to tackle those questions under the angle of gas emission and more particularly of odor annoyance. A multi-method approach was applied to monitor biogas and odor emissions, both at the laboratory level on pilot plants and at real scale in 4 agricultural biogas facilities, in Belgium, Luxembourg, France and Germany. Results show that digested material is generally less odorant than crude manure or slurry, while preserving all the amendment and fertilizing qualities of the original material. Possible annoyance of agricultural biogas facilities in the surroundings remains limited and can be solved through simple techniques. [less ▲]

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See detailEvaluation of an electronic nose for the early detection of organic overload of anaerobic digesters
Adam, Gilles ULg; Lemaigre, Sébastien; Romain, Anne-Claude ULg et al

in Bioprocess and Biosystems Engineering (2013), 36(1),

This study aims at the analysis of the utilization of an electronic nose (e-nose) to serve as a specific monitoring tool for anaerobic digestion process, especially for detecting organic overload. An ... [more ▼]

This study aims at the analysis of the utilization of an electronic nose (e-nose) to serve as a specific monitoring tool for anaerobic digestion process, especially for detecting organic overload. An array of non specific metal oxide semiconductor gas sensors were used to detect process faults due to organic overload events in twelve anaerobic semi-continuous reactors of 1.8 L. Three different load strategies were followed (i) a cautious organic load (1.3 gVS•L-1•day-1); (ii), an increasing load strategy (1.3 to 5.3 gVS∙L-1•day-1) and (iii) a cautious organic load with load pulses of up to 12 gVS•L-1•day-1. A first monitoring campaign was conducted with three different substrates : sucrose, maize oil, and a mix of sucrose/oil during 60 days. The second campaign was run with dry sugar beet pulp during 45 days. Hotelling's T²-value and upper control limit to a reference set of digesters fed with a cautious OLR (1.3 gVS•L-1•day-1), was used as indirect state variable of the reactors. Overload situations were identified by the e-nose apparatus with Hotelling’s T²-values at least 4-times higher in magnitude than the upper control limit of 23.7. These results confirmed that the e-nose technology appeared promising for online detection of process imbalances in the domain of anaerobic digestion. [less ▲]

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See detailEvaluation of Electronic Nose Technology for Early-warning of Bio-methanation Process Disturbance
Adam, Gilles ULg

Doctoral thesis (2013)

An electronic nose (e-nose) is an instrument composed of an array of non specific gas sensors inspired by the biological olfactory system for the detection and recognition of odours. In this work, this ... [more ▼]

An electronic nose (e-nose) is an instrument composed of an array of non specific gas sensors inspired by the biological olfactory system for the detection and recognition of odours. In this work, this technology is evaluated to predict process disorders in agricultural anaerobic digestion reactors. Response of the sensor array is used to recognize a gas mixture by the use of multivariate data analysis techniques. In our case, an e-nose developed in our laboratory and composed of metal oxide semi-conductor gas sensors was equipped with a biogas dilution system to realize the measurements. When employed on small-scale digesters fed with simple feeding substrates (sucrose, lipids, mixture lipids and sucrose), the e-nose presented enthusiastic results for the detection of organic overload disorders. Multivariate process control charts were employed with the e-nose data to obtain a simple state indicator represented by the Hotelling's T² statistics. This indicator resumes the general state of the digesters when its value exceeds statistically defined control limit. Instability periods and recovery of the anaerobic digestion process when exposed to organic overfeeding could be thus precisely assessed. In addition, the use of a variety of substrates had no significant effect on the performance of the e-nose monitoring. Variations of methane content in biogas, as a result of use of substrates of different compositions, had neither any influence on the e-nose monitoring quality. Thereafter, an e-nose was placed online on continuously stirred tank reactor of 100 L over a period of 300 days. A multivariate monitoring method using recursive and adaptive principal component analysis (PCA) was applied to the e-nose data. This enabled to very efficiently compensate system drift and notably sensor drift. Moreover, adaptive PCA model could also adapt to environmental variations and to reactor slow shifts. T² statistics and its squared prediction error (SPE) obtained from the PCA model are very competitive state indicators compared to pH, alkalinity, gas production rate and methane and carbon dioxide content. Two electronic noses were also evaluated in real-scale agricultural anaerobic digestion plants. The low process state monitoring in both plants does not enable to conclude to the relevance of disorders observed by the e-nose apparatus and demonstrates the real need for online anaerobic digestion process state monitoring and its subsequent optimization in agricultural biogas plants. Even though, the performance of the recursive PCA monitoring is much superior to that of static PCA. Adaptive PCA proves to be a potential automatic drift and environmental variations correction method for online and real-time e-nose measures, notably for field applications. In conclusion, it was demonstrated in this work that e-nose technology has a real potential as an application of online monitoring of anaerobic digester state. Moreover, this research demonstrated that it was possible to realize a monitoring of the state of anaerobic digesters using only gas phase measurements. Another contribution is the use of multivariate process control techniques on e-nose data to obtain a simple state indicator as well as the use of adaptive PCA to automatically compensate drift and environmental effects on e-nose measurements. [less ▲]

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See detailGas sensor array applied to the monitoring of biogas process
Adam, Gilles ULg; Lemaigre, Sébastien; Romain, Anne-Claude ULg et al

Conference (2011, May)

There is a lack of simple online monitoring system to control the performances of biogas reactors. The electronic nose technology appears to be an adapted device to deliver fast information about process ... [more ▼]

There is a lack of simple online monitoring system to control the performances of biogas reactors. The electronic nose technology appears to be an adapted device to deliver fast information about process disturbances in anaerobic reactors as it is adequate for online monitoring. In this study, twelve anaerobic mini-reactors were supervised with a home-made e-nose to observe process reaction in relation to organic overloads events. Usually, to avoid overload situations, on farms reactors are not fed at maximum load capacity, resulting in non optimized biogas production. The objective of the experiment was to determine if the gas sensors array feature can be related to the process state and if an indirect state variable, giving early warning of process faults, can be derived from the e-nose response. <br />The results demonstrated that focusing on gas phase of anaerobic reactors with a simple device composed of an array of non-specific gas sensors helped in the warning of disorders of the anaerobic digestion process. Mahalanobis distance from a cautious feeding group (group of observations indicating a good process) can be used as an indirect variable to evaluate the intensity of the state disorder. Euclidean distance has been also calculated but it was less informative than the Mahalanobis distance. [less ▲]

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See detailAnaerobic digestion process monitoring: focus on the gas phase using electronic nose technology
Adam, Gilles ULg; Lemaigre, Sébastien; Romain, Anne-Claude ULg et al

in GERBIO (Ed.) Proceedings of the International Congress Progress in Biogas 2011 - part 1 (2011, March 31)

Gas phase of four pilot-scale anaerobic reactors was monitored with a gas sensors array, also called electronic nose (e-nose) over three weeks. CH4, CO2, H2S, H2 concentration in the gas phase and biogas ... [more ▼]

Gas phase of four pilot-scale anaerobic reactors was monitored with a gas sensors array, also called electronic nose (e-nose) over three weeks. CH4, CO2, H2S, H2 concentration in the gas phase and biogas production rate were also measured. Reactors were exposed to process disturbances by doubling the organic loading rate and by decreasing the temperature from 38 to 32°C for 24 hours. During these tests, sludge pH and alkalinity were also measured. When organic loading was doubled, no changes were observed in pH and alkalinity, while hydrogen content in gas phase increased by 20% and took 8 hours to recover stable values of 130 ppm. Hydrogen sulphide also increased proportionally to organic loading of the reactors and took two days to return to stable values. Methane and carbon dioxide ratio changed from 1.2 to 0.95. No changes were observed during the temperature drop of the digesters apart from hydrogen concentration which increased sharply several hours. Electronic nose was able to detect variations in organic loading rates for the four anaerobic reactors, with increased signals for higher organic loadings of the pilots. Sensing of gas phase of anaerobic reactors was able to discriminate disorders of operating conditions of anaerobic reactors, especially organic loading. [less ▲]

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See detailLe biogaz, source d'énergie locale et internationale
Adam, Gilles ULg; Nsavyimana, Gaston ULg

Conference given outside the academic context (2010)

Le biogaz est une énergie renouvelable simple encore trop peu exploitée malgré les innombrables ressources en biomasse valorisables par cette filière. En Belgique, la méthanisation à la ferme utilise les ... [more ▼]

Le biogaz est une énergie renouvelable simple encore trop peu exploitée malgré les innombrables ressources en biomasse valorisables par cette filière. En Belgique, la méthanisation à la ferme utilise les déchets organiques des exploitations (lisier, fumier). Ceux-ci sont méthanisés pour produire du biogaz, valorisé en énergie électrique et chaleur, et du digestat, la fraction liquide, utilisé comme fertilisant. En Afrique, en plus d'être une source d'énergie, la méthanisation est utile dans le traitement des eaux usées. La valorisation des boues de vidange des fosses septiques pour produire du biogaz s'avère une solution pour nombre de villes africaines dont la gestion de ces boues n'est pas contrôlée et présente d'énormes risques sanitaires et environnementaux. Voici comment la méthanisation est une solution aux problèmes environnementaux et énergétiques dans divers pays, développés et en développement. [less ▲]

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See detailPotential of the Electronic Nose as a Tool for the Detection of Disturbances in Anaerobic Digestion Processes
Adam, Gilles ULg; Neyrinck, Roland ULg; Lemaigre, Sébastien et al

in IWWG (Ed.) Venice 2010 Third International Symposium on Energy from Biomass and Waste (2010, November)

Most of agricultural biogas plants do not operate at optimum loading rate to avoid overload and process failure. This study aims at the development of an electronic nose technology to serve as a specific ... [more ▼]

Most of agricultural biogas plants do not operate at optimum loading rate to avoid overload and process failure. This study aims at the development of an electronic nose technology to serve as a specific monitoring tool for anaerobic digestion processes. Twelve semi-continuous anaerobic mini-digesters (1.6 L useful capacity) were fed with three different substrates: sucrose, maize oil and a mix 1:1 of sucrose and maize oil. Two feeding strategies were followed (i) a cautious organic load (1.3 gVS.L-1.day-1) and (ii) an increasing load strategy (1.3 to 5.33 gVS.L-1.day-1). Digesters were monitored during two months by analysing the biogas composition and collecting electronic nose measurements. The electronic nose was able to detect the impact of organic load variations. Overload situations were distinguished by the e-nose apparatus and the different feeding substrates induced distinct responses from the e-nose system. [less ▲]

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See detailPotentiel du nez électronique comme outil de détection d'évènements de suralimentation de digesteurs anaérobies
Adam, Gilles ULg

Speech (2010)

Le succès croissant des énergies renouvelables et locales provient du développement de politiques favorables aux énergies vertes dont le résultat est le développement croissant de la filière de ... [more ▼]

Le succès croissant des énergies renouvelables et locales provient du développement de politiques favorables aux énergies vertes dont le résultat est le développement croissant de la filière de méthanisation agricole en Belgique et au Grand Duché du Luxembourg. La plupart des stations de méthanisation agricole ne peuvent travailler à un rendement optimum afin d'éviter toute suralimentation des réacteurs qui conduit à une perturbation de la digestion. De plus, le monitoring du processus est réalisé par des analyses sur la phase liquide dont les délais ne permettent pas de gérer instantanément le processus de digestion. De cela apparait la nécessité d'un outil simple de suivi servant à prévenir en ligne toute perturbation du processus et de réagir rapidement. Dans cette optique, le nez électronique est un outil potentiel du suivi en ligne des réacteurs anaérobies basé sur l'analyse de la phase gazeuse. Les nez électroniques sont composés d'un réseau de capteurs à gaz non spécifiques qui peuvent répondre à différentes substances dans une matrice complexe, comme le biogaz, et produire des réponses complexes qui sont traitées par analyses multivariées et par des systèmes de reconnaissance. L'objectif de cette étude est de démontrer la capacité d'un système type nez électronique comme un outil robuste, fiable et facile à utiliser pour le suivi du processus des réacteurs anaérobies à la ferme et prévenir des situations de suralimentation des digesteurs. Un nez électronique composé de six capteurs gaz à semi-conducteurs a été testé pendant deux mois sur douze mini-digesteurs semi-continus inoculés avec de la boue anaérobie (1,5 L; 2,2% MS; 54,4% MOS). Les mini-digesteurs ont été nourris avec trois types de substrats: (i) saccharose; (ii) lipides et (iii) un mélange de lipides et saccharose en proportion 1:1. Deux stratégies d'alimentation ont été suivies: un contrôle avec un taux de charge organique de 1,33 g.L-1.jour-1 et une stratégie de suralimentation croissante évoluant de 1,33 à 5,33 g.L-1.jour-1. La concentration en méthane, dioxyde de carbone, sulfure d'hydrogène et monoxyde de carbone et le pH ont été mesurés quotidiennement sur le biogaz issu des mini-digesteurs. Les échantillons de biogaz ont ensuite été dilués 25 fois avec de l'air de référence avant d'être analysés sur le nez électronique. Les résultats de l'analyse en composantes principales des signaux des six capteurs à gaz du nez électronique démontrent que les situations de suralimentation sont détectées par le nez électronique. Les taux de charge organique élevés (> 3 g.L-1.jour-1) sont séparés des contrôles (1,3 g.L-1.jour-1). Les différents types de substrats sont également distingués dans le graphique des composantes principales mais les contrôles de chaque type de substrat sont proches et forment un zone de digestion stable (taux de charge < 3 g.L-1.jour-1) indépendante du substrat. Cela démontre le potentiel du nez électronique à prévenir des phénomènes de suralimentation des digesteurs anaérobies, indépendamment du substrat utilisé. L'intensité de la suralimentation peut-être estimée par la distance euclidienne par rapport au centre de gravité des scores des mini-digesteurs contrôles. Ces résultats devront être validés sur des réacteurs pilotes et finalement sur des installations réelles. [less ▲]

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See detailCan an Electronic Nose Assess the Biomethanation Process?
Adam, Gilles ULg; Nicolas, Jacques ULg

Poster (2010, January 12)

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See detailTetrazolium testing in Allium genus
Rodriguez Quilon, Isabel; Adam, Gilles ULg; Duran, José María

Poster (2009, September 29)

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See detailLa mesure des émissions gazeuses, et plus particulièrement des odeurs, comme outil de caractérisation de matériaux et de processus
Nicolas, Jacques ULg; Romain, Anne-Claude ULg; Degrave, Christophe et al

Conference (2009, September)

La qualité d'un matériau de construction, outre ses caractéristiques physiques, est fonction de son impact sur l'environnement intérieur. Ceci pousse de plus en plus les fabricants à proposer sur le ... [more ▼]

La qualité d'un matériau de construction, outre ses caractéristiques physiques, est fonction de son impact sur l'environnement intérieur. Ceci pousse de plus en plus les fabricants à proposer sur le marché des matériaux (dont les "bio-matériaux") dont les émissions atmosphériques demeurent dans des limites acceptables. Plusieurs initiatives, essentiellement volontaires, existent au niveau européen pour évaluer ces émissions. Un des objectifs de la directive européenne des produits de construction (CPD) est d'harmoniser les méthodes d'évaluation. La comparaison de 4 chambres d'émission, de tailles différentes, l'usage de méthodes d'évaluation physico-chimiques couplées à des méthodes sensitives de mesure des odeurs et l'utilisation de la technique des nez électroniques constituent l'originalité de la démarche du projet mené par l'université de Liège en collaboration avec deux autres institutions belges. Plus généralement, le nez électronique représente un outil particulièrement bien adapté au suivi d'ambiances gazeuses au cours du temps. L'odeur émise peut ainsi servir comme "variable de process" pour suivre en continu, voire contrôler, des processus utilisant la bio dégradation de produits, comme le compostage, la bio méthanisation ou le bio séchage. [less ▲]

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See detailEnsayos de germinacion y analisis de viabilidad y vigor en semillas
Rodriguez, Isabel; Adam, Gilles ULg; Duran, Jose Maria

Article for general public (2008)

La eleccion de la semilla constituye una de las primeras decisiones que ha de adoptar et agricultor cada ano, a la hora de decidir qué variedad debe sembrar y la calidad de semilla a utilizar. En los ... [more ▼]

La eleccion de la semilla constituye una de las primeras decisiones que ha de adoptar et agricultor cada ano, a la hora de decidir qué variedad debe sembrar y la calidad de semilla a utilizar. En los ultimos cincuenta anos se han producido importantes avances en el mundo de las semillas que han contribuido a la evolucion hacia una agricultura cada vez mas tecnificada, con una reduccion sustancial de la mano de obra, unida a un empleo cada vez mas importante de maquinaria, abonos, fitosanitarios y nuevas variedades. [less ▲]

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See detailEnsayos de germinación y análisis de viabilidad y vigor en semillas
Rodriguez Quilón, Isabel; Adam, Gilles ULg; Durán, José María

Article for general public (2008)

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See detailGERMINACIÓN, VIGOR, VIABILIDAD, CALIDAD Y MEJORA DE SEMILLAS DE CEBOLLA (ALLIUM CEPA L.)
Adam, Gilles ULg

Master's dissertation (2007)

In this work, it has been attempted to improve the value of a non-commercial seed lot of an onion (Allium cepa L.) local variety from Galicia, Spain. Different seed conditioning treatments have been done ... [more ▼]

In this work, it has been attempted to improve the value of a non-commercial seed lot of an onion (Allium cepa L.) local variety from Galicia, Spain. Different seed conditioning treatments have been done: prehydration, osmotic and matrix priming, hormonal and disinfection treatments. A densimetric seed separation has been carried out to divide the seed lot in four sublots of different quality and to measure seed answers to hormonal treatments. Moreover, a tetrazolium seed test was carried out to determine the causes of the seed lot low germination rate. In the prehydration essay, seeds were immersed in a circulating water flow from 30 minutes to 24 h. Best results were obtained with the 4 h hydration. Prehydration influences micro-organisms contamination percentage of non-germinated seeds. Furthermore, prehydration was combined to a disinfection using sodium hypochlorite 4 % for 4 minutes. Disinfected seeds lost germination capacity. Hormonal treatment consisted in hydrating seeds on filter paper of different GA3 concentration solutions during germination test. GA3 improved germination uniformity but not germination percentage. Best results have been obtained with the 10 mg•L-1 GA3 concentracion. In seed separation, differences in germination rate and vigour have been observed in function of seeds medium weight. Seeds were separated in a vertical air flow that divided seeds in four fraction of growing density. A linear correlation between seed germination percentage and one hundred seeds medium weight was determined. It’s possible to separate seeds in different seed sublots of different quality. Osmotic conditioning were done with deionized water, KNO3 0,1 and 0,3 M and 150, 250 and 350 g•kg-1 PEG-6000 solutions for periods of 24, 48 and 96 h. In PEG-6000 seed osmoconditioning, a significant loss of germination was observed. Deionized water and KNO3 solutions improved seed quality, improving seed germination velocity and uniformity. It has been detected that seed germination uniformity only depends on the period of treatment but not on the solution concentration. Matrix seed priming gave best results with most deteriorated seeds, improving significantly their germination rate but had a few influence on seeds of better quality. Best treatment resulted the one using the proportion in volume seed: matrix: water of 1:10:2 of Algalita® during 6 days. In the viability test, a incomplete maturation of seeds was observed and 52,5 % of seeds were viable, with germination results of 45 % on date of viability test. Cotyledons of 38,5 % of seeds were inmature and 12,5 % of seeds didn’t have any embryo. Low maturation of seeds must have been the cause of the low lot quality. [less ▲]

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