Angélique Leonard
Université de Liège, Department of Chemical Engineering, Faculty Member
This paper focuses on the dewatering efficiency of activated sludge from waste water treatment plant using biobased coagulants in addition with classical flocculant and compares the results with those obtained with a sole classical... more
This paper focuses on the dewatering efficiency of activated sludge from waste water treatment plant using biobased coagulants in addition with classical flocculant and compares the results with those obtained with a sole classical coagulant. For this work, a standard compression-expression cell is used and an experimental design is develop to highlight the effect of the biobased coagulants
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ABSTRACT Drying appears as a major step prior to valorization of sludge from wastewater treatment plant. This study uses an experimental design on different sludges to highlight the drying behavior according to drying conditions, storage... more
ABSTRACT Drying appears as a major step prior to valorization of sludge from wastewater treatment plant. This study uses an experimental design on different sludges to highlight the drying behavior according to drying conditions, storage and extrusion. This research is performed with industrial view, but on a single cylinder sample, and focuses on five responds: maximum drying flux, time to reach 95% of dry matter, final volume, critical moisture and slowing-down coefficient.
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Drying appears as a major step prior to valorization of sludge from wastewater treatment plant. This study uses an experimental design on different sludges to highlight the drying behavior according to drying conditions, storage and... more
Drying appears as a major step prior to valorization of sludge from wastewater treatment plant. This study uses an experimental design on different sludges to highlight the drying behavior according to drying conditions, storage and extrusion. This research is performed with industrial view, but on a single cylinder sample, and focuses on five responds: maximum drying flux, time to reach 95% of dry matter, final volume, critical moisture and slowing-down coefficient.Peer reviewe
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The aim of this study is to have a good understanding of the environmental impact of glucose production. Glucose is generally produced from corn or wheat. Since agricultural processes are known to be difficult to evaluate by LCA, the... more
The aim of this study is to have a good understanding of the environmental impact of glucose production. Glucose is generally produced from corn or wheat. Since agricultural processes are known to be difficult to evaluate by LCA, the results obtained with two different LCA databases, Gabi and Ecoinvent, are compared in this work. The production of glucose from raw materials can be divided in two steps: the agricultural steps allowing the plant production, and the conversion step including the extraction of the starch from the plant and its hydrolysis into glucose. Preliminary results underline the high impact of the agricultural step, so a special attention has been paid to these data. Specific Belgian data collected by the Walloon Agricultural Research Centre (CRA-W) (2014) [1] have been used as primary data (yield, amount of fertilizers, etc.), either using Ecoinvent or GaBi datasets background data to model fertilizers, diesel consumption, etc. A third model was built using only data available in Ecoinvent for corn and wheat cultures. For the conversion steps, literature data have been used along with some industrial data. As few studies are available in the literature concerning starch hydrolysis, the focus has been placed on data validation (mass balance checks, cross-reference information, etc.). Based on these multiple sources, it is possible to compare the LCA results for the production of 1 kg of glucose for three different cases, summarized in the following table. The results obtained using these three models will be presented, at both the inventory and the impact assessment steps. They show significant differences and highlight the need to understand in depth the involved assumptions when developing the datasets, in addition to the ones adopted for the inventory.Peer reviewe
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status: publishe
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Conclusions and perspectives 2. Inclusion of others components • High contribution of carbohydrate (agricultural practice) • Comparison with other binders: results depend on the environmental impacts categories. ECOSE better if related to... more
Conclusions and perspectives 2. Inclusion of others components • High contribution of carbohydrate (agricultural practice) • Comparison with other binders: results depend on the environmental impacts categories. ECOSE better if related to resources depletion, GWP (1) Department of Chemical Engineering – PEPs (Products, Environment and Processes) University of Liège, Building B6 – Sart-Tilman, 4000 Liège, Belgium. Saicha.Gerbinet@ulg.ac.be (2) Knauf Insulation Sprl, Head of Sustainability, Products and Buildings, Axis Parc, Rue E. Francqui, 1435 Mont-St-Guibert, Belgium (3) Knauf insulation Sprl., ECOSE development manager, St-Helens, United Kingdom
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This work reports the results of an experimental study concerning on one hand the influence of water-to cement ratios (W/C), and the role of aggregates on the other hand on the drying kinetics of cement pastes during thermal drying. Three... more
This work reports the results of an experimental study concerning on one hand the influence of water-to cement ratios (W/C), and the role of aggregates on the other hand on the drying kinetics of cement pastes during thermal drying. Three types of cement pastes were realized and studied; cement pastes with ratios W/C 0.4, W/C 0.5 and mortar with ratio W/C 0.5. These tries present the advantage to reproduce the natural conditions met in the problems of interaction atmosphere and material. Cylindrical samples of cement of size (17 X 13) mm are dried in a convective dryer. The sample is continuously weighed during the drying test and its mass is recorded every 60 s, in the purpose to obtain the drying curves. The results show that the increase of the W/C ratio leads to an increase of the drying rate due to the increase of the initial porosity. The effect of the introduction of aggregates is observable by the comparison of the drying curve obtained for the mortar and the cement pastes. The results show a decrease of the drying kinetics with mortars. The results also show that the air drying temperature has a large impact on the drying process, increasing the temperature leading to significant drying time reduction. The Effective diffusion coefficient is calculated by comparison between the experimental results and the analytical solution of Fick’s equation written for a finite medium.Peer reviewe
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In this paper, a new unpublished study on the watermelon fruit is presented. It concerns the experimental determination of the water desorption isotherms at three different temperatures, using the dynamic method requiring the Dynamic... more
In this paper, a new unpublished study on the watermelon fruit is presented. It concerns the experimental determination of the water desorption isotherms at three different temperatures, using the dynamic method requiring the Dynamic Vapor System device (DVS). In order to select the appropriate desorption curve equation, 11 different models available in the literature were applied to the experimental data. The models were compared using the correlation coefficient, the standard error, the reduced chi-squared, the mean bias error and the root mean square error; they were predicted by a non-linear regression analysis using the Curve Expert software. The effect of the temperature on the constants of the found equation is also examined. Finally, the desorption isosteric heat of watermelon is determined using the Clausius-Clapeyron relation. Contrary to long times taken in the static method, the results show that 4.5 days are widely sufficient to reach the equilibrium via the DVS device. In addition, the obtained curves are of the type III and the Henderson model is the most appropriate model representing them. In the interval 0.05 - 0.45 kg of water/kg d.m of equilibrium moisture, the values of the isosteric heat vary from 65.02 to 113.25 kJ/mol. Finally, the equation giving the isosteric heat of desorption v.s. the equilibrium moisture content is obtained
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This paper investigated the influence of dual conditioning of waste water treatment sludge on the evolution of sludge internal structure during convective drying. Results showed clearly an impact of chemical conditioners on the evolution... more
This paper investigated the influence of dual conditioning of waste water treatment sludge on the evolution of sludge internal structure during convective drying. Results showed clearly an impact of chemical conditioners on the evolution of the created porosity. For sludge flocculated by single conditioning, a centered porosity delimiting by external crust was shown, while for dual conditioning, a porosity structured in lamellae, was identified
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This paper focuses on potential errors when assessing the human toxicity of corn farming in Wallonia, Belgium. The USEtox method is applied to the farming of 1 hectare of corn. Local data are used for farming data and GaBi datasets for... more
This paper focuses on potential errors when assessing the human toxicity of corn farming in Wallonia, Belgium. The USEtox method is applied to the farming of 1 hectare of corn. Local data are used for farming data and GaBi datasets for background data. Field emissions due to farming are calculated by the most prevailing models. The results in human toxicity, cancer effect, underline the large contribution of chromium (Cr) emissions. But when characterizing fertilizer composition, only the total chromium is measured and therefore unspecified chromium is used as emissions. However, it is known that chromium in the natural environment is mostly the non-toxic form Cr (III), which would greatly decrease the impact as the characterization factor for unspecified chromium is, in USEtox, the average of Cr (III) and the toxic form Cr (VI). The impact for human toxicity, non-cancer effect is mostly related to zinc emissions even if zinc is relatively harmless. The impact of pesticides is negli...
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This presentation will give the last figures about sludge valorisation within EU and will summarize the emerging management routes. The critical role of sludge dewatering and drying will developed in view of the optimization of the whole... more
This presentation will give the last figures about sludge valorisation within EU and will summarize the emerging management routes. The critical role of sludge dewatering and drying will developed in view of the optimization of the whole sludge treatment chain
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Despite its generalized use, the concept of capillary law applied to water movement through the soil is far from representing the real occurring processes. Beside individual pores volume (or size), should the connectivity and tortuosity... more
Despite its generalized use, the concept of capillary law applied to water movement through the soil is far from representing the real occurring processes. Beside individual pores volume (or size), should the connectivity and tortuosity of the complete pore network be part of any calculation regarding soil-water fluxes. We aimed at demonstrating that statement through the visualization of 20 agricultural soil samples (3 x 5 cm) at various water matric potentials. The samples were firstly saturated with water and then a specified negative pressure was applied to the bottom of the samples through the use of pressure plates in order to reach an internal water matric potential. At equilibrium, the samples were scanned with an X-ray microtomograph (micro-CT system Skyscan-1172) which produces 3D images where the air phase is distinguishable from the water phase and soil matrix. That procedure was applied after reaching water matric potential of -4 kPa, -7 kPa, -10 kPa, and -30 kPa. For e...
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In this study, we aim to improve knowledge about the soil water evaporation process. First, evaporation tests were carried out to characterise the drying kinetics, soil temperature evolution and soil shrinkage. Second, numerical... more
In this study, we aim to improve knowledge about the soil water evaporation process. First, evaporation tests were carried out to characterise the drying kinetics, soil temperature evolution and soil shrinkage. Second, numerical simulations of the test were performed using the finite element code LAGAMINE developed at the University of Liège. The aim is to reproduce numerically the drying behaviour of the soil and to emphasise the water transport mechanisms between the soil and the atmosphere.
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Drying is known as a high energy consuming unit operation, representing between 12 to 25% of the global industrial energy consumption in developed countries. Consequently, drying contributes to several environmental impacts mainly... more
Drying is known as a high energy consuming unit operation, representing between 12 to 25% of the global industrial energy consumption in developed countries. Consequently, drying contributes to several environmental impacts mainly associated to its heat or electricity requirements. One can cite global warming, emission of particles, acidification, photochemical ozone formation, … Based on a literature review and some dedicated case studies, this work will illustrate how Life Cycle Assessment (LCA) can be used to evaluate the environmental impacts associated to a drying operation. The results will be presended in a way to indicate some eco-design strategies for dryers. Keywords: drying; eco-design; Life cycle assessment; environmental impact.
Research Interests: Environmental Science, Energy, Process Control, Life Cycle Assessment, Environmental Impact Assessment, and 15 moreEnergy Consumption, Evaporation, Emerging Technologies, Electricity, Global Warming, Diffusion, Global warming potential, Drying, Intensification, Eco Design, Environmental Impact, Dehydration, Dewatering, Environmental, and Products Quality
The present paper presents the interactions between water retention/evaporation and cracking during the desiccation of intact and disturbed Belgian Luvisol. The disturbed (DS) and undisturbed (NDS) samples (reduced-tillage-residue-in... more
The present paper presents the interactions between water retention/evaporation and cracking during the desiccation of intact and disturbed Belgian Luvisol. The disturbed (DS) and undisturbed (NDS) samples (reduced-tillage-residue-in (RTRI) and conventional-tillage-residue-out (CTRO)) were collected from an agricultural field in Gembloux, Wallonia, Belgium. The drying experiment took place in controlled laboratory conditions at 25 °C. Moisture content, soil suction and surface cracks were monitored with a precision balance, a tensiometer and a digital camera, respectively. The image processing and analysis were performed using PCAS® and ImageJ® software. The results showed that crack formation was initiated at a stronger negative suction and a lower water content (Wc) in DS > CTRO > RTRI. The suction and the crack propagation were positively correlated until 300 kPa for the DS and far beyond the wilting point for the NDS. For the NDS, the cracking accelerated after reaching th...
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Multiple myeloma osteolytic disease is caused by an uncoupled bone-remodelling process with an increased osteoclast activity. Disease development relies on interactions between myeloma cells and bone marrow stromal cells. Recent findings... more
Multiple myeloma osteolytic disease is caused by an uncoupled bone-remodelling process with an increased osteoclast activity. Disease development relies on interactions between myeloma cells and bone marrow stromal cells. Recent findings suggest a role for glycan-binding proteins in myeloma microenvironment. Here, we investigated lectins involved in osteoclastogenesis and their role in myeloma bone disease. Microarray data analysis showed a lower expression of galectin-1 (gal-1) in mature osteoclasts compared to monocytic progenitor cells, confirmed at the RNA and protein levels in osteoclast cultures. Confocal microscopy showed that gal-1 localised predominantly in the sealing zone of mature osteoclasts. Although equal differentiated-osteoclast numbers, gal-1−/− osteoclasts showed a higher resorption activity compared to wild-type controls. Micro-computed tomography showed an aberrant bone phenotype with decreased bone densities in gal-1−/− mice. In vivo, tumour progression was fas...
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The obtained drying curves were fitted with the nine most commonly models used for food drying. The two models giving the best fitting results for the whole studied temperatures were selected, i.e. the Page model and the 4 th polynomial... more
The obtained drying curves were fitted with the nine most commonly models used for food drying. The two models giving the best fitting results for the whole studied temperatures were selected, i.e. the Page model and the 4 th polynomial degree model. The fitting parameters are presented in the following table. They can be expressed as functions of the drying air temperature of the heated air, making the model useful for multiple temperatures or changes of the operating temperature during the drying process. Comparison between experimental and predicted values are illustrated in Fig. 3.
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Drying behavior of baker's yeast depends on the internal structure of the grain. In this paper, investigation of the porous structure of a dry grain using X-ray microtomography is presented. The resulting data are treated to deduce pore... more
Drying behavior of baker's yeast depends on the internal structure of the grain. In this paper, investigation of the porous structure of a dry grain using X-ray microtomography is presented. The resulting data are treated to deduce pore network characteristics for drying modeling. The treatment algorithm is based on segmentation kriging and medial axis calculation by thinning. Complementary informations are also calculated using auto-correlation function. The complete procedure is first tested on a virtual solid and then applied to yeast. The results present a large pore size distribution and a high connectivity between the pores. Both those effects can partially be attributed to the choice of the algorithms to deduce the pore network.