Survey of a wastewater treatment plant microfauna by image analysis

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 the plant, such as the biotic indices namely the Sludge Biotic Index. All the above-mentioned procedures demand the identification, classification and quantification of the different species. Normally this is done manually, which implies both time and expertise. In the present work a semi-automatic protozoan recognition procedure by means of image analysis is attempted. The program built for this purpose (ProtoRec v.3) was also used to study the evolution of the microfauna during transient operation times (stoppage and re-run). The results were rather satisfactory in terms of protozoa recognition and the survey of the transient phase allowed verifying the aging and degradation of the microfauna by means of the different predominant species

Estudo por Análise de Imagem do Comportamento de uma Estação de Tratamento de Efluentes sob Condições Transientes

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. Uma outra possibilidade é a qualificação do estado da ETAR através de índices bióticos como o SBI. Todos estes procedimentos exigem uma identificação, classificação e quantificação das espécies presentes. Geralmente isto é feito manualmente, o que implica tempo e muitas vezes a presença de um técnico especializado. 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 facto

Survey of protozoa and metazoa populations in wastewater treatment plants by image analysis and discriminant analysis

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 certain species or groups and some variables of the plant. Such analysis demands the identification and quantification of the different species, which requires skilled workers, specializing in zoology or protozoology, and is time-consuming. To overcome those problems, semi-automatic image analysis and discriminant analysis were carried out for the identification procedures. The overall results were very promising in terms of Protozoa and Metazoa group recognition and of survey of plant conditions. Copyright 2004 John Wiley & Sons, Ltd.Financial support for the co-operation between the Portuguese (Braga) and French (Nancy) teams was provided by the French Embassy in Portugal and ICCTI (Portugal). A. L. Amaral was supported by a PhD grant (PRAXIS XXI/BD/20325/99) of ‘Fundação para a Ciência e Tecnologia’ (Portugal). M. da Motta was supported by a grant of the National Council of Scientific and Technological Development of Brazil (CNPq)

Study on the Performance of Wastewater Treatment Plant by Image Analysis: Validation and Case Study

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

Study of protozoa population in wastewater treatment plants by image analysis

Protozoa are important micro-organisms 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). The identification is performed 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 found commonly in activated sludge

Automated monitoring of activated sludge using image analysis

An automated procedure for the characterisation by image analysis of the morphology of activated sludge has been used to monitor in a systematic manner the biomass in wastewater treatment plants. Over a period of one year, variations in terms mainly of the fractal dimension of flocs and of the amount of filamentous bacteria could be related to rain events affecting the plant influent flow rate and composition.Grand Nancy Council.Météo-France.Brasil. Ministério da Ciência e Tecnologia. Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).Embassy of France in Portugal.Ministério da Ciência e Tecnologia. Instituto de Cooperação Científica e Tecnológica Internacional (ICCTI)

Reconnaissance semi-automatique de la microfaune des boues activées des stations d’epuration des eaux usées : PROTOREC v 2.0

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)

Characterisation by image analysis of anaerobic microbial aggregates under shock conditions

In the present work the characterisation by image analysis of anaerobic biomass under organic and hydraulic shocks was performed. The digester was fed with a synthetic substrate, containing 50% of oleic acid (as COD). Organic and hydraulic shocks were performed by increasing the substrate concentration or by lowering the hydraulic retention time. In both cases the organic loading rate changed from 6 to 30 kgCOD/m³.d. Hydraulic shock induced fast and persistent changes both in the number and length of filaments, but in the organic shock significant changes were detected later and initial values were recovered 840 hours after the shock.Fundação Calouste Gulbenkian (FCG) - post-doctoral research grant.Generalitat de Catalunya. Consell Interdepartamental de Recerca i Innovació Tecnològica (CIRIT) - predoctoral fellowship