The biota present in the activated sludge of a wastewater treatment plant are mainly composed of bacteria, Protozoa and Metazoa. The Protozoa and Metazoa species are important micro-organisms taking part in the ecosystem balance in wastewater treatment plants and are quite sensitive to physical, chemical and operational processes. Several authors have established relationships between the predominance of certai...
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 p...
Automated methods based on the analysis of macro- and meso-scale images has 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 full-scale samples from twelve different wastewater treatment plants in France and Portugal.
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 caracteri...
Suspended and granular sludge from two expanded granular sludge bed (EGSB) reactors fed with oleic acid at organic loads between 2 and 8 kg COD/m³.day was characterised by image analysis. The number, and the average length of free filaments in the dispersed fraction of biomass, and the morphologic changes of granular sludge when exposed to increasing oleic acid concentrations were quantified. Two methods to dis...
Protozoa are important microorganisms for 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 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...
A microfauna presente numa estação de tratamento de efluentes por lamas activadas é composta essencialmente por bactérias, protozoários e metazoários. Os protozoários apresentam uma sensibilidade aos fenómenos físico-químicos e operacionais que os tornam indicadores do estado de funcionamento da estação. A literatura apresenta relações entre a abundância de uma certa espécie ou grupo e parâmetros da estação. Um...
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....
In wastewater treatment plants by activated sludge, a complex ecosystem constituted mainly of bacteria, protozoa and metazoa is degrading the pollution. Bacteria are agglomerated as flocs, exopolymers helping to bind zoogleal bacteria to filamentous bacteria which constitute the backbone of the flocs. When a good equilibrium is not maintained between these two bacterial groups, problems occur such as pin-floc (...
The microfauna present in the activated sludge of a wastewater treatment plant is mainly composed by bacteria, protozoa and metazoa. The protozoan species are quite sensitive to physical, chemical and operational processes making them, thus, precious indicators of the state of the plant. Several authors already established relationships between the predominance of certain species or group and some parameters of...
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