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Colloque avec actes et comité de lecture. Internationale.; International audience

Colloque avec actes et comité de lecture. Internationale.; International audience

In this work, several models have been coupled in order to represent the whole forest-to-energy production chain: the growth phase, the primary transformation, and the ultimate conversion to heat and/or electricity. Combined with literature data for wood transportation, they gave a complete balance of emissions to compare with fossil-based alternatives. An economic analysis completes the work. The results show that wood-based scenarios do perform better than their fossil counterparts, but also that the primary transformation and transportation items can greatly diminish this advantage. Further work will focus on determining the best metric to assess the climate change impact of forestry scenarios based on the timing of carbo dioxide emissions as well as geophysical effects such as albedo and evapotranspiration., Proceedings of the 24th European Biomass Conference and Exhibition, 6-9 June 2016, Amsterdam, The Netherlands, pp. 1402-1404

Many processes in the chemical and pharmaceutical industries generate wastewater containing organic toxic compounds and other kinds of xenobiotics. Usually, biological treatments are used to degrade a great quantity of these substances. However, most of the time, the microorganisms are not adapted and the treatment can be blocked. Therefore, the first step to make a continuous reactor operative is the acclimation, i.e., the adaptation of the microorganisms to a specific substrate. During this particular step of the process there is a selection and a multiplication of specialized microorganisms and physiological transformations can occur in their metabolic system. Furthermore, combining image processing techniques have already been successfully used to elucidate the activated sludge morphological changes for both aggregated and filamentous bacteria contents, during such processes. The experimental set-up is composed of an aerated reactor and a clarifier. The sludge is recycled from the clarifier by a peristaltic pump. The complete mixing inside the reactor is guaranteed by the diffusion of air from its bottom. The reactor was inoculated with biomass collected from a wastewater treatment plant and fed with an artificial wastewater based on meat extract. During acclimation, chemical parameters were measured in the influent, reactor and effluent, in order to verify the stability of the process. To complete the evaluation of the process, microscopy acquisition and image processing and analysis techniques were performed for aggregates and filamentous bacteria characterization for bright field, Gram and poly-β-hydroxybutyrate (PHB) staining images. The information extracted from those images allowed for aggregates and filamentous bacteria contents inspection, identification of PHB storing microorganisms and, gram-positive and gram-negative filamentous bacteria recognition. Figure 1 presents activated sludge samples at the beginning and at the end of the acclimation phase. It was found in this study that biomass changes during the acclimation phase could be effectively monitored, combining image analysis information and chemical parameters.

International audience; Two excess sludge reduction processes (ultrasounds and thermal) were studied with specific attention to some physico-chemical characteristics of treated sludge. Several parameters were monitored and discussed in respect to process efficiency and implications to dewaterability of excess sludge generated. Release of biopolymers, floc size reduction, transfer of ionizable functional groups in the liquid fraction and decrease of relative hydrophobicity were observed. According to the applied treatment, these modifications may improve or worsen the sludge dewaterability properties.

International audience

Comunicação apresentada no "7th World Congress of Chemical Engineering" em Glasgow, Escócia, em Julho de 2005., The effect of the solids on the mass transfer characteristics in a bubble column was studied experimentally for the system air/water/beads of calcium alginate. Volumetric liquid side mass transfer coefficient, kLα, specific interfacial area, α, and liquid side mass transfer coefficient, kL, were determined under different solid concentrations, gas flow rates and solid sizes. Bubble characteristics were obtained using an image analysis technique. The presence of solids affect negatively kLα, decreasing both α and kL and the effect is more pronounced for the smaller particles. For these particles the variation of kLα is due to the variation of its two components, while for larger particles kLα variation is due, essentially, to changes in kL as no significant differences in α were observed. An optical probe technique was also used to obtain gas holdup radial profiles for higher solids loadings and gas flow rates. It was observed that increasing the solids loading, the gas holdup decreases and the shape of the gas holdup profiles is also influenced by the solids concentration., Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/3427/2000, POCTI/EQU/45194/2002.

Neste trabalho é proposto um procedimento para reconhecimento semi-automático das espécies de protozoários por análise de imagem. Este programa (ProtoRec v.2) foi em seguida utilizado para estudar a evolução da microfauna durante períodos de transição (paragem e arranque da estação). Os resultados obtidos foram satisfatórios em relação ao reconhecimento das espécies pelo programa e o acompanhamento da estação permitiu-nos verificar a degradação e envelhecimento da lama e o aparecimento de protozoários que evidenciam tal fato.

International audience; A survey of wastewater characteristics in Europe has been conducted to evaluate the range of pollution ratios (BOD5/COD, SS/COD, N/COD and P/COD) that can be used to assess the robustness of wastewater management systems in terms of sustainability. Data were collected from questionnaires sent to wastewater treatment plants managers (Austria, France), from national data bases (Denmark, Flanders, The Netherlands), from national contacts and from literature. Average values are proposed for N/COD (about 0.1 mg/mg), P/COD (about 0.016 mg/mg), SS/COD (about 0.5 mg/mg) and BOD5/COD (about 0.4 mg/mg). But these values are subject to time-variations (short and long-term range) which merit further investigations.; Une enquête sur les caractéristiques des eaux usées en Europe a été réalisée dans l`objectif d`évaluer les ratios représentatifs de la pollution (DBO5/DCO, MES/DCO, N/DCO, P/DCO). Les données ont été collectées à l`aide de questionnaires envoyés aux exploitants de stations d`épuration (Autriche, France), de base de données nationales (Danemark, Flandres, Pays-Bas), de contacts nationaux et de données bibliographiques. Les valeurs moyennes obtenues sont les suivantes : N/DCO (environ 0.1 mg/mg), P/DCO (environ 0.016 mg/mg), MES/DCO (environ 0.5 mg/mg) et DBO5/DCO (environ 0.4 mg/mg). Ces valeurs sont sujettes à des variations temporelles (à court et long terme) qui mériteraient de plus amples investigations.

Um método baseado na análise de imagens foi desenvolvido para caracterizar os flocos de lodo ativado em termos do seu tamanho e forma (dimensão fractal) e da abundância de bactérias filamentosas. Após ter sido testado em experimentos em escala piloto, o método foi validado para estações de tratamento reais. Foram analisadas doze estações de tratamento de esgotos situadas na França e em Portugal, de tamanhos e processos diferentes. Em seguida realizou-se um acompanhamento sobre a estação de Braga (Portugal) que estava com problemas de intumescimento do lodos (“bulking” filamentoso)., Automated methods based on image analysis have been developed to characterise activated sludge in terms of size and shape (fractal dimension) of flocs and abundance of filamentous bacteria. After tests on pilot-scale reactors, the method has been validated on samples from twelve different full-scale wastewater treatment plants of different sizes and processes in France and Portugal. Finally sludge morphology changes have been monitored during a bulking event on a full-scale plant in Portugal.

Morphological changes in anaerobic granular sludge fed with increasing loads of oleic acid were quantified by image analysis. The combination of this technique with data on the accumulation of adsorbed long chain fatty acid give insight into the mechanisms of sludge disintegration, flotation and washout The molecular characterization of microbial community indicated that the bacterial domain was affected during sludge disintegration, flotation and washout. The archaeal domain was less affected although no acetoclastic and only a residual hydrogenotrophic activity were detected at the end of the operation., Instituto Gulbenkian de Ciência., Fundação para a Ciência e Tecnologia (FCT).

An automated procedure for the characterisation by image analysis of the morphology of activated sludge has been used to monitor the biomass in a pilot wastewater treatment plant during two runs inoculated with a different sludge and operated at two different temperatures. The bulking events were easily detected by image analysis. Correlations were found between settleability properties (Sludge Volume Index and settling velocity) and the morphological parameters (filament total length, filament number and floc size).

O estudo da biomassa de sistemas de tratamento de efluentes por análise de imagem permite avaliar o seu estado de agregação assim como acompanhar as modificações por ela sofrida quando submetida a choques orgânicos ou hidráulicos. Certos processos de tratamento trabalham com uma forte concentração em biomassa, o que obriga a uma diluição prévia. O presente estudo avalia o efeito desta diluição sobre a caracterização da biomassa aeróbia e anaeróbia (agregada sob a forma de flocos ou grânulos ou isolada). Os resultados obtidos indicam que este efeito varia segundo a origem e tipo da biomassa e o tipo de água utilizada na diluição. Foi observado que a diluição provoca inicialmente um aumento do tamanho dos flocos para em seguida provocar a sua ruptura. Devido a fortes variações sofridas sobretudo em relação à quantificação das bactérias filamentosas, recomenda-se a opção por uma diluição e sua manutenção até o fim do experimento., The study by image analysis of biomass in wastewater treatment systems allow us to evaluate its aggregation state and to relate its changes to changes in the process operation conditions. In some processes, a high biomass concentration is used and dilution is necessary for visualisation by optical microscopy. The effect of the dilution factor on the measured characteristics of aerobic and anaerobic bacteria (aggregated as flocs or granules, or isolated) has been investigated. The results indicate that the effect depends on the origin and type of biomass and on the kind of water used for dilution. Dilution induces initially an increase of the floc size. The flocs are disrupted when the dilution factor is high. Due to the observed variations on the quantification of filamentous bacteria, it is recommended to select initially an appropriate dilution factor and to maintain it for the whole experiment., Brasil. Ministério da Ciência e Tecnologia. Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)., Fundação para a Ciência e a Tecnologia (FCT)., Embaixada de França em Portugal., Ministério da Ciência e Tecnologia. Instituto de Cooperação Científica e Tecnológica Internacional (ICCTI).

Protozoa are important microorganisms taking part to the ecosystem balance in wastewater treatment plants. A procedure for their semi-automated identification and counting based on image analysis is proposed. The main difficulty is the segmentation of the protozoa as most of them are in contact with the sludge. The protozoa are characterized by the size of their silhouette (area and length) and three shape factors (elongation, circularity and eccentricity). They are identified after projecting the resulting 5D space into a 3D space of principal components. The rate of automated identification is actually higher than 50% for some of the species commonly found in activated sludge., National Council of Scientific and Technological Development of Brazil (CNPq). Embassy of France in Portugal. Instituto de Cooperação Científica e Tecnológica Internacional (ICCTI).

The applications of visualisation and image analysis to bioreactors can be found in two main areas: the characterisation of biomass (fungi, bacteria, yeasts, animal and plant cells, etc), in terms of size, morphology and physiology, that is the far most developed, and the characterisation of the multiphase behaviour of the reactors (flow patterns, velocity fields, bubble size and shape distribution, foaming), that may require sophisticated visualisation techniques.

Une procédure a été développée pour la reconnaissance semi-automatique de protozoaires présents dans les boues activées. Après sélection sur l’image de la zone d’intérêt où se trouve l’individu, la taille et la forme de la silhouette de ce dernier sont caractérisées par onze paramètres. La classification selon l’espèce se fait par étape, chacune faisant appel à une procédure d’analyse factorielle discriminante. Durant la phase de validation un taux de reconnaissance supérieur à 70% a été obtenu pour la plus grande partie des espèces prises en compte., Brasil. Ministério da Ciência e Tecnologia. Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)., Ambassade de France au Portugal., Ministério da Ciência e Tecnologia. Instituto de Cooperação Científica e Tecnológica Internacional (ICCTI).