References of "Vasel, Jean-Luc"
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See detailApport du traitement d'images dans le suivi de l'influence des teneurs en nutriments sur la croissance des lentilles d'eau (Lemna minor)
Tangou Tabou, Thierry ULg; Baya, Dehenould Trésor; Liady, Mouhamadou Nourou Dine ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18(1), 37-48

The growth of duckweed (Lemna minor) is an important component in the process in wasterwater floating macrophyte ponds. An excess or shortage of this biomass may be responsible for the dysfunction of such ... [more ▼]

The growth of duckweed (Lemna minor) is an important component in the process in wasterwater floating macrophyte ponds. An excess or shortage of this biomass may be responsible for the dysfunction of such ponds. Modeling these duckweed ponds through mass balances based on Petersen's matrix may be helpful in facilitating the optimal management of such facilities. This study sought at assessing the efficiency of digital image processing in the growth monitoring of Lemna minor under different concentration of nitrogen and phosphorus. The experiments were carried out in a growth chamber (phytotron) using an experimental pilot involving initial fresh Lemna minor biomass (1 g), nitrogen and phosphorus concentration varying between 5 and 64 mg N-NH4+.L-1, and 1 and 24 mg P-PO43-.L-1, respectively. The digital image processing was achieved in addition to gravimetric methods (fresh weight and/or dry weight). Our results showed that image processing method allowed a continuous and non destructive monitoring of duckweeds biomass. The growth of Lemna minor progressively decreases when nitrogen and phosphorus were greater than 16 mg N-NH4+.L-1 and 6 mg P-PO43-.L-1. The maximum growth rate μmax are of the order of 0.07 d-1, the kinetic constants Ks and Ki are respectively 3.83 mg.L-1 and 204 mg L-1 for nitrogen, 1.26 mg.L-1 and 13.3 mg.L-1 for phosphorus. Such results are interesting as they could serve in the optimal management of Lemna minor and the modeling of biological reactors. [less ▲]

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See detailMonitoring the influence of light intensity on the growth and mortality of duckweed (Lemna minor) through digital images processing
Tangou Tabou, Thierry ULg; Baya, Dehenould Trésor; Musibono Eyul'anki, Dieudonné et al

Conference (2013, August)

The growth of duckweed (Lemna minor), depending on biotic and abiotic factors (i.e. temperature, light intensity, photoperiod, pH, nutrients), is an important compartment of the treatment process in ... [more ▼]

The growth of duckweed (Lemna minor), depending on biotic and abiotic factors (i.e. temperature, light intensity, photoperiod, pH, nutrients), is an important compartment of the treatment process in wastewater floating macrophytes ponds. Excess or shortage of this biomass might be responsible of the dysfunction of such ponds. Modeling these duckweed ponds through mass balances based on Petersen’s matrix should help in an optimal management of such facilities. This article focused on (i) the influence of light intensity on the growth, and (ii) the mortality of Lemna minor under a constant temperature. Experiments were carried out in a growth chamber using a pilot consisting of transparent cubic tanks, with an initial fresh Lemna minor biomass. In order to monitor Lemna minor biomass, digital image processing was achieved in addition to fresh weight and dry weight measurements methods. The results showed that Lemna minor reached a maximum growth rate (0.19 d-1) for light intensities ranging between 250 μmol.m-².s-1 and 300 μmol.m-². s-1. Light intensities from 300 μmol.m-².s-1 to 400 μmol.m-².s-1 induced a slight growth inhibition. This inhibition was strongly marked at 450 μmol.m-².s-1. As for mortality, very low levels (< 0.05 d-1) were determined. These results thus provide a contribution in the modeling of duckweed waste stabilization ponds. [less ▲]

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See detailMonitoring and Measuring the biomass of the floating macrophytes by numerical image processing: Case duckweeds (Lemna minor) in Waste Stablisation Ponds
Tangou Tabou, Thierry ULg; Musibono Eyul"Anki, Dieudonné; Vasel, Jean-Luc ULg

Poster (2011, August)

In hot countries temperature conditions allow the use of various WSP technologies, including floating macrophytes. We studied duckweeds and they have been used for industrial or domestic waste water ... [more ▼]

In hot countries temperature conditions allow the use of various WSP technologies, including floating macrophytes. We studied duckweeds and they have been used for industrial or domestic waste water treatment. However, the vegetable carpet formed on the water surface must be managed in order to maintain a good efficiency. The duckweeds must be harvested regularly. Otherwise when the biomass is getting too large there is some overlap, mortality increases, and dead cells sink and degrade at the bottom creating a new pollution. In addition, a hazardous harvest of the lenses can involve the reduction in the capacity of purification and also support the development of algae. We tried to monitor the biomass and the environmental parameters of the system (luminosity, temperature, pH, nitrogen, phosphorus, alkalinity, COD…) as well. Indeed, the duckweed biomass measurements were carried out by many researchers (Köner and Vermaat, 1998; Caicédo et al., 2000; Rhamani and Sternberg, 1999; Edwards et al., 1992;…) according mainly to two methods, : the measurement of fresh or dry weight. It appears that these two methods present disadvantages especially for rather long experiments. If the last one is more reliable but destructive, the first on the other hand is less destructive but less accurate and not very reproducible. In the present work, we considered numerical image processing by adapted soft wares, namely: ACDsee® and Image Pro-Plus®. The purpose of this study is thus to establish the surface-biomass relationship for a possible comparison of the resulting biomasses by image and weighing [less ▲]

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See detailMODELLING OF BACTERIAL SULPHATE REDUCTION IN ANAEROBIC PONDS : KINETIC INVESTIGATIONS
Harerimana, Casimir ULg; Vasel, Jean-Luc ULg; Jupsin, Hugues ULg et al

in Australian Water Association (2011)

The aim of the study was first to develop a simple and practical model of anaerobic digestion including sulphate-reduction in anaerobic ponds. The basic microbiology of our model consists of three steps ... [more ▼]

The aim of the study was first to develop a simple and practical model of anaerobic digestion including sulphate-reduction in anaerobic ponds. The basic microbiology of our model consists of three steps, namely, acidogenesis, methanogenesis, and sulphate reduction. This model includes multiple reaction stoichiometry and substrate utilization kinetics. The second aim was to determine some kinetic parameters associated with this model. The values of these parameters for sulfidogenic bacteria are used in the anaerobic pond model to describe the sulphate reduction processes and to evaluate the risk of odour generation. [less ▲]

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See detailSome influences of sediments in aerated lagoons and waste stabilization ponds
Chabir, D.; El Ouarghi, H.; Brostaux, Yves ULg et al

in Water Science & Technology (2000), 42(10), 237-246

Respirometric tests have been undertaken on sediments in aerated lagoons and waste stabilization ponds to quantify their oxygen demand and to determine the main factors governing the process. Factors such ... [more ▼]

Respirometric tests have been undertaken on sediments in aerated lagoons and waste stabilization ponds to quantify their oxygen demand and to determine the main factors governing the process. Factors such as seasonal variations, temperature, substrate, sediment layer thickness, density of macro-invertebrates and suspended sediments were investigated. The results showed that temperature and substrate concentration are the main factors that influence sediment oxygen demand; followed by spatial heterogeneity and resuspension of sediments, whereas the density of macro-invertebrates could have an effect in summer (hot season). Sediment layer thickness had no effect. A model of sediment oxygen demand is developed for the two main factors (temperature and substrate) with an r2 of 0.98. [less ▲]

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See detailL'environnement
Andre, Philippe ULg; Boreux, Jean-Jacques ULg; Hanson, Alain ULg et al

in Nguyen, Long-Den; Tsalkovitch, Gérard (Eds.) La mesure et l'instrumentation. Etat de l'art et perspectives. (1995)

Il s'agit du chapitre 14 d'un ouvrage collectif consacré à la mesure et à l'instrumentation. Ce chapitre présente plusieurs aspects de la démarche de la mesure dans l'environnement. Il explicite les ... [more ▼]

Il s'agit du chapitre 14 d'un ouvrage collectif consacré à la mesure et à l'instrumentation. Ce chapitre présente plusieurs aspects de la démarche de la mesure dans l'environnement. Il explicite les aspects méthodologiques propres à l'environnement et les méthodes de mesure qui en découlent, notamment les bio-capteurs, les bio-indicateurs, l'utilisation de l'homme comme instrument de mesure, … Il balaye les différents secteurs de l'environnement -air, eau, odeur- et montre comment le modèle et la théorie de l'analyse des systèmes peuvent être considérés comme des outils performants de surveillance d'atmosphères polluées ou de confort thermique dans les bâtiments. [less ▲]

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See detailBase de calcul pour le dimensionnement d'une tour de refroidissement à tirage naturel
Nicolas, Jacques ULg; Vasel, Jean-Luc ULg

in European Journal of Mechanical and Environmental Engineering (1992), 37

Le but de cet article est de fournir de façon exhaustive l'ensemble des relations qui permettent le calcul des transferts thermiques dans une tour de refroidissemenmt à contrecourant et à tirage naturel ... [more ▼]

Le but de cet article est de fournir de façon exhaustive l'ensemble des relations qui permettent le calcul des transferts thermiques dans une tour de refroidissemenmt à contrecourant et à tirage naturel. L'article se base sur les approches classiques décrites dans la littérature (Merkel, Chilton, Braun, ...), mais en uniformisant les symboles et les unités, de façon à fournir en un seul texte tous les éléments qui permettent de modéliser, pour des besoins de contrôle ou de dimensionnement, une tour de refroidissement et d'en estimer les performances.Quelques pratiques d'utilisation de ces relations sont étudiées, ainsi qu'une confrontation de différentes méthodes de résolution sur un même exemple. [less ▲]

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See detailModélisation des échanges thermiques et de la circulation d'air dans un lit bactérien
Nicolas, Jacques ULg; Vasel, Jean-Luc ULg

in Revue des Sciences de l'Eau = Journal of Water Science (1990), 3(3), 303-324

The temperature is one of the main parameters governing the biological reactions in a trickling filter. The present model proposes a set of equations applicable for the determination of a temperature ... [more ▼]

The temperature is one of the main parameters governing the biological reactions in a trickling filter. The present model proposes a set of equations applicable for the determination of a temperature profile, and therefore of an average temperature, inside the trickling filter, when the flowrate and the temperature at entry of the liquid, the ambient air conditions (temperature and humidity) and the thermal exchange coefficients of the tower are known. Moreover, the airflow induced by natural draft is also computed when the head loss coefficients in the media and at entry are known. Beside this formulation, the first results of modal fitting on pilot plants are discussed. With few further developments, the method could be useful for the optimization of the operating temperature in a trickling filter which guarantees a sufficient airflow rate in the tower. [less ▲]

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