Activated sludge monitoring of a wastewater treatment plant using image analysis and partial least squares

The wastewater treatment plant activated sludge is a complex ecosystem mainly of bacteria and protozoa. Bacteria agglomerate as settleable robust aggregates leading to low organic matter and turbidity final effluents. However, when the operating conditions are not perfect some malfunctions may occur leading to bulking problems. Classical methods to survey the bacteria aggregation and contents resided on manual counting which are, rather tiring, imprecise and time-consuming urging the development of faster automated image analysis methods. Therefore, the prime objective of this work resided on surveying the activated sludge filamentous bacteria and aggregates contents and morphology, and establish relationships between the biomass and some operating parameters by multivariable statistical techniques. One of the main conclusions of this work resided on the determination of a filamentous, rather than a zoogleal, bulking problem in the course of this survey. This conclusion could be withdrawn by the strong resemblance between the sludge volume index and the filaments/aggregates contents ratio behaviour throughout the experiment time and by the high filamentous bacteria/suspended solids ratio (above 10000 mm/mg) which clearly indicates the existence of a filamentous bulking problem. Furthermore, an in-depth statistical analysis revealed that the filamentous bacteria/suspended solids ratio parameter may be used, at some extent, to monitor the SVI behaviour in a wastewater treatment plant aeration tank, whereas the suspended solids could be satisfactory monitored by the total aggregates area parameter. However, these results refer only to a wastewater treatment plant experiencing a bulking phenomenon and further studies should be developed in normal plants

Activated sludge monitoring of a wastewater treatment plant using image analysis and partial least squares regression

The biomass present in awastewater treatment plantwas surveyed and their morphological properties related with operating parameters such as the total suspended solids (TSS) and sludge volume index (SVI). For that purpose image analysis was used to provide the morphological data subsequently treated by partial least squares regression (PLS) multivariable statistical technique. The results denoted the existence of a severe bulking problem of non-zoogleal nature and the PLS analysis revealed a strong relationship between the TSS and the total aggregates area as well as a close correlation between the filamentous bacteria per suspended solids ratio and the SVI.Fundação para a Ciência e a Tecnologia (FCT) – PRAXIS XXI/BD/20325/99

Environmental Variables And Intertidal Beach Annelids Of São Sebastião Channel (state Of São Paulo, Brazil).

Benthic annelid communities were studied during a one-year period (August/95 to July/96) in two sectors of the beaches Engenho d'Agua and São Francisco, São Sebastião Channel (São Paulo, Brazil), where the substrate is composed by a mixture of sand and rock fragments. Abiotic parameters such as salinity of interstitial water and sediment properties were used to characterize the environment. The polychaetes were well represented in the two sectors and their distribution was related with sediment type. The density of individuals and the number of taxa was higher at São Francisco, while the diversity and the evenness were higher at Engenho d'Agua. This difference can be a consequence of organic enrichment caused by domestic input, and of the lower and more variable salinity at São Francisco. Due to these factors, the high density of opportunistic species, like Capitella capitata ssp., Scolelepis squamata, Laeonereis acuta and several oligochaetes, represented 75.5% of total abundance at this sector.49849-5

Aplicações de técnicas de análise de imagem em microbiologia ambiental

São evidenciadas algumas aplicações da análise de imagem em microbiologia ambiental, nomeadamente: o reconhecimento e identificação automática de algumas espécies de protozoários presentes em estações de tratamento de águas residuais; o estudo da influência de três tóxicos na mobilidade do protozoário ciliado Tetrahymena pyriformis em meio líquido; a correlação entre actividade metanogénica, velocidade de sedimentação e parâmetros morfológicos de agregados microbianos em digestores anaeróbios; e finalmente o estudo da correlação entre as actividades metanogénicas acetoclástica e hidrogenofílica e a fluorescência de um consórcio de microrganismos de um digestor anaeróbio. Procura-se assim demonstrar a utilidade das técnicas de análise de imagem na monitorização quer de processos de tratamento de águas resíduais quer da própria qualidade ambiental.Ministério da Ciência e Tecnologia. Instituto de Cooperação Científica e Tecnológica Internacional (ICCTI).Embaixada de França em Portugal

Hilbert Space of Isomorphic Representations of Bosonized Chiral QCD2QCD_2

We analyse the Hilbert space structure of the isomorphic gauge non-invariant and gauge invariant bosonized formulations of chiral $QCD_2$ for the particular case of the Jackiw-Rajaraman parameter $a = 2$. The BRST subsidiary conditions are found not to provide a sufficient criterium for defining physical states in the Hilbert space and additional superselection rules must to be taken into account. We examine the effect of the use of a redundant field algebra in deriving basic properties of the model. We also discuss the constraint structure of the gauge invariant formulation and show that the only primary constraints are of first class.Comment: LaTeX, 19 page

Characterization of bamboo species and other biomasses with potential for thermal energy generation.

Made available in DSpace on 2019-05-17T00:36:28Z (GMT). No. of bitstreams: 1 Characterizationofbamboospeciesandotherbiomasses2019.pdf: 228850 bytes, checksum: 8c177d72338020e0e4e5795a8e37bd1a (MD5) Previous issue date: 2019bitstream/item/197403/1/Characterization-of-bamboo-species-and-other-biomasses-2019.pd

Characterisation of activated sludge abnormalities by image analysis and multivariate statistics

The ability to distinguish between different types of abnormalities affecting wastewater activated sludge systems, by means of image analysis and chemometrics methodologies, was studied in the current work. Three experiments were performed in a pilot plant activated sludge system, during periods ranging from 47 to 85 days each, in a total of 108 samples, reflecting filamentous bulking, zoogleal bulking and pin point flocs conditions. These samples were further analyzed for the determination of image analysis parameters and of the most commonly surveyed operating parameters. Regarding the image analysis methodology three aliquots of each sample were visualized by bright field and fluorescence microscopy, and a total of 150 images per sample were acquired. These images were then treated by image processing software allowing the study of the contents and morphology of aggregated and filamentous bacteria, resulting in the determination of parameters reflecting the aggregates size distribution, filamentous to aggregated biomass ratio, and biomass viability. A Principal Components Analysis was then carried out on the obtained data to identify each studied conditions, with cross-validation (CV) as the criterion to determine the optimal number of significant components. Although the optimal number of principal components, obtained by the CV method, was found to be 7, explaining 91.9 % of the data variability, it was found that the use of the 2 first principal components (explaining 61.2 % of the data variability) allowed to clearly identify all three conditions (pin point flocs, filamentous and zoogleal bulking). In fact, the samples score plot in these two principal components presented three distinct and non-overlapping zones, reflecting the three different studied conditions. Furthermore, it allowed for the identification and exclusion of 5 outliers within the dataset. Analysing the loading contribution for these 2 first principal components, it was evident the preponderance of the aggregates size distribution and of the filamentous to aggregated biomass ratio, reflecting the importance of these two groups of parameters in the identification and enlightenment of activated sludge abnormalities

Improved image analysis procedures for monitoring activated sludge systems with filamentous bulking

Activated sludge systems are frequently used in wastewater treatment plant. This process is the most suitable and studied system. However, several problems are being always detected, such as filamentous bulking. Filamentous bulking is typically caused by an overabundance of filamentous organisms that interfere with the settling and compaction process. This phenomenon can be studied and related with settling parameters by automated image analysis using different microscopy acquisitions. However, by using these standard image analysis procedures some relevant information about the state of the sludge is enclosed. Conventional routines, using monochrome images are not suitable to detect the filamentous bacteria which are gram-positive or gram-negative. Moreover, the traditional image acquisition methodologies are not capable to detect both viable and damaged bacteria present within the sludge. Presently, the gram-stain evaluation is performed by visual inspection and manual counting using a microscope which is a tedious procedure. Also, to overcome the lack of viability information, an epifluorescence staining method composed with two nucleic acid-binding stains can be used. For this study, a lab-scale activated sludge reactor was monitored during 100 days through image analysis information and the operational parameters were modified inducing filamentous bulking. Morphological changes were investigated by using new acquisition methods such as epifluorescence staining LIVE/DEAD® BacLight™ Bacterial Viability Kit, the LIVE BacLight™ Bacterial Gram Stain Kit and the traditional bright field. The overall results revealed an improvement of the sludge morphological characterisation, combining these new image analysis procedures with the conventional routines

Monitoring filamentous bulking and pin-point flocs in a lab-scale activated sludge system using image analysis

Activated sludge processes are the most frequently used techniques regarding biological wastewater treatment. However, depending on the process operation conditions, several malfunctions could take place, in which filamentous bulking and deflocculation processes, such as pin-point flocs, are the most common problems, causing the sludge settling ability decrease and effluent quality deterioration. Bright field Image analysis is nowadays considered a powerful tool to quantitatively characterize aggregated and filamentous bacteria. Furthermore, the use of epifluorescent staining techniques, coupled to image analysis, presents a promising method to determine bacteria gram nature and viability. Encouraged by the success of image analysis procedures over the last years, the present work studied a lab-scale activated sludge system, under operation conditions causing filamentous bulking and pin-point flocs phenomena. Sludge settling ability and turbidity values were measured verifying the nature of the settling problem. COD contents, as well as nitrogen contents, in terms of N-NH4+, N-NO3- and N-NO2-, were surveyed in the feeding effluent, reactor bulk and settler. Regarding the biomass characterization, four major morphological descriptors groups were studied, covering free filamentous bacteria contents, aggregates contents, aggregates size and aggregates morphology. With respect to the aggregates characterization, these were divided in 3 classes (large, intermediate and small aggregates) according to their size. Percentages of gram-positive bacteria, gram-negative bacteria, viable and damaged bacteria were also evaluated based on fluorescent image analysis. Finally, the raw resulting data was fed into a multivariate statistical analysis, in order to enlighten the relationships between the obtained image analysis information and operational parameters. An improvement of the sludge morphological characterisation was found by combining fluorescent and bright field image analysis procedures. Furthermore, the results obtained during the monitoring period indicate that automated image analysis can help clarifying the nature of the events within the aeration tank, when the system is submitted to disturbances

Automatic identification of activated sludge disturbances and assessment of operational parameters

Activated sludge systems are prone to be affected by changes in operating conditions leading to problems such as pinpoint flocs formation, filamentous bulking, dispersed growth, and viscous bulking. These problems are often related with the floc structure and filamentous bacteria contents. In this work, a lab-scale activated sludge system was operated sequentially obtaining filamentous bulking, pinpoint floc formation, viscous bulking and normal conditions. Image processing and analysis techniques were used to characterize the contents and structure of aggregated biomass and the contents of filamentous bacteria. Further principal component and decision trees analyses permitted the identification of different conditions from the collected morphological data. Furthermore, a partial least squares analysis allowed to estimate the sludge volume index and suspended solids key parameters. The obtained results show the potential of image analysis procedures, associated with chemometric techniques, in activated sludge systems monitoring.The authors acknowledge the financial support to D.P.M. through the post-doctoral grant SFRH/BPD/82558/2011 and to the Project PTDC/EBB-EBI/103147/2008 both funded by Fundacao para a Ciencia e a Tecnologia (Portugal) and Fundo Social Europeu (FSE)