Biomarkers: a strategic tool in the assessment of environmental quality of coastal waters

Ecosystems are under the pressure of complex mixtures of contaminants whose effects are not always simple to assess. Biomarkers, acting as early warning signals of the presence of potentially toxic xenobiotics, are useful tools for assessing either exposure to, or the effects of these compounds providing information about the toxicant bioavailability. In fact, it has been argued that a full understanding of ecotoxicological processes must consider an integrated multi-level approach, in which molecular impact is related with higher-order biological consequences at the individual, population and community levels. Monitoring programs should make use of this tool to link contaminants and ecological responses fulfilling strategies like those launched by OSPAR (Commissions of Oslo and Paris) Convention on the protection of the marine environment of the North-East Atlantic and the International Council for the Exploration of the Sea (ICES). An overview of the work done in the past few years using biomarkers as in situ tools for pollution assessment in Portuguese coastal waters is presented as a contribution to the set up of a biomonitoring program for the Portuguese coastal zone. Considering the data set available the biomonitoring proposal should include the analysis of biomarkers and effects at individual levels. The aim of the program will include a spatial and temporal characterization of the biomarkers acetyl-cholinesterase, metallothioneins, DNA damage, adenylate energy charge and scope-for-growth levels. The investigation of the spatial variation of biomarkers is crucial to define sites for long term monitoring, which will be integrated with a chemical monitoring program. This framework will be a major contribution to the implementation of a national database for the use of biomarkers along the Portuguese coast.info:eu-repo/semantics/publishedVersio

Predicting effects of toxic events to anaerobic granular sludge with quantitative image analysis and principal component analysis

Detergents and solvents are included in the list of compounds that can be inhibitory or toxic to anaerobic digestion processes. Industrial cleaning stages/processes produce vast amounts of contaminated wastewater. In order to optimize the control of these wastewaters it is important to know and predict the effects on the activity and physical properties of anaerobic aggregates in an early stage. Datasets gathering morphological, physiological and reactor performance information were created from three toxic shock loads (SL1 – 1.6 mgdetergent/L; SL2 – 3.1 mgdetergent/L; SL3 – 40 mgsolvent/L). The use of Principal Component Analysis (PCA) allowed the visualization of the main effects caused by the toxics, by clustering the samples according to its operational phase, exposure or recovery. The morphological parameters showed to be sensitive enough to detect the operational problems even before the COD removal efficiency decreased. Its high loadings in the plane defined by the first and second principal components, which gathers the higher variability in datasets, express the usefulness of monitor the biomass morphology in order to achieve a suitable control of the process. PCA defined a new latent variable t[1], gathering the most relevant variability in dataset, that showed an immediate variation after the toxics were fed to the reactors. t[1] varied 262, 254 and 80%, respectively in SL1, SL2 and SL3. Once more, the high weights of the morphological parameters associated with this new variable express its influence in shock load monitoring and control, and consequently in operational problems recognition

Principal component analysis and quantitative image analysis to predict effects of toxics in anaerobic granular sludge

Principal component analysis (PCA) was applied to datasets gathering morphological, physiological and reactor performance information, from three toxic shock loads (SL1 – 1.6 mgdetergent/L; SL2 – 3.1 mgdetergent/L; SL3 – 40 mgsolvent/L) applied in an expanded granular sludge bed (EGSB) reactor. The PCA allowed the visualization of the main effects caused by the toxics, by clustering the samples according to its operational phase, exposure or recovery. The aim was to investigate the variables or group of variables that mostly contribute for the early detection of operational problems. The morphological parameters showed to be sensitive enough to detect the operational problems even before the COD removal efficiency decreased. As observed by the high loadings in the plane defined by the first and second principal components. PCA defined a new latent variable t[1], gathering the most relevant variability in dataset, that showed an immediate variation after the toxics were fed to the reactors. t[1] varied 262%, 254% and 80%, respectively, in SL1, SL2 and SL3. The high loadings/weights of the morphological parameters associated with this new variable express its influence in shock load monitoring and control, and consequently in operational problems recognition.Fundação para a Ciência e a Tecnologia (FCT) -Bolsa SFRH/BD/13317/2003, projecto POCTI/ AMB/60141/200

Applications of quantitative image analysis in wastewater treatment

Book of abstracts of the Meeting of the Institute for Biotechnology and Bioengineering, 2, Braga, Portugal, 2010Quantitative image analysis (QIA) techniques gained an undeniable role in several fields of research during the last decade. In the field of wastewater treatment (WWT) processes, several computer applications were developed for the monitoring of microbial entities either individual cells, or several types of aggregates. New descriptors were defined that are more reliable, objective, and useful than the subjective and time-consuming parameters used classically to monitor the WWT biological processes. Examples of application include the objective prediction of filamentous bulking, known as one of the most problematical phenomenon occurring in activated sludge technology. It also demonstrated to be useful to classify protozoa and metazoa populations. In high rate anaerobic processes, based on granular sludge, it was possible to detect aggregation time and fragmentation phenomena during critical events, such as toxics and organic overloads. Currently, the major efforts on the development of QIA techniques in WWT technology are focused in its application coupled with coloured samples, obtained after staining and fluorescent techniques. Also, the use of quantitative morphological parameters in process control is being investigated. In fact, employ multivariate statistical analysis to data gathered by QIA during transient states of an anaerobic reactor determined a latent variable that encompasses a weighted sum of performance, physiological and morphological information. This new variable was highly sensitive to reactor efficiency deterioration, enclosing remarkable variation in the first hours of the disturbances. The high loadings raised by morphological parameters revealed that they should be considered to monitor and control load disturbances and toxic events in high rate anaerobic digesters

A chemometric tool to monitor high-rate anaerobic granular sludge reactors during load and toxic disturbances

The wide fluctuations in flow rate and the presence of toxic compounds can damage the high efficiency of high-rate anaerobic granular sludge reactors. As earlier these disturbances are detected, more accurate would be the corrective actions, and less damage will be caused to the microorganisms involved in the process. The use of Principal Component Analysis (PCA) determined a latent variable, combining a weighted sum of operational, physiological, and morphological data, which showed high sensitivity to recognize the operational problems occurred when four organic loading disturbances and three toxic shock loads were applied to Expanded Granular Sludge Bed reactors. The high loadings/weights linked with the morphological parameters, specially the aggregates size distribution (>0.1, >1) and filaments length dynamics (TL/VSS), obtained using quantitative image analysis techniques, illustrate the usefulness of monitor the structural changes of the anaerobic granular sludge. The application of PCA chemometric tool to dataset gathering information from all disturbances allowed the differentiation between organic loading and toxic shock disturbances, as well as the main effects caused by each class of disturbance.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/13317/2003, POCTI/AMB/60141/2001

Integration of morphological and physiological data through Principal Component Analysis to identify the effect of organic overloads on anaerobic granular sludge

Morphological parameters, obtained by quantitative image analysis techniques, together with physiological and reactor performance data were inserted in principal components analysis (PCA) to detect operational problems and control of high rate anaerobic reactors during organic overloads. Four lab-scale Expanded Granular Sludge Blanket reactors were used to performed organic overloads of 18 kg.mˉ³.day ˉ¹(R1 – HRT of 8h; and, R2 – HRT of 2.5h) and 50 kg.mˉ³.dayˉ¹ (R3 - fed for 3 days; and, R4 - fed for 16 days). The application of PCA allowed the visualization of the main effects caused by the organic overloads. The first Principal Component (PC) extracted, in each shock load, retains enough information to group observations in agreement with operational conditions (normal or overload). The variables from quantitative image analysis presented high loadings, suggesting that might play an important role in organic overloads control.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/13317/2003, POCI/AMB/60141/2004

Structural and optical properties of europium doped zirconia single crystals fibers grown by laser floating zone

Yttria stabilized zirconia single crystal fibers doped with europium ions were developed envisaging optical applications. The laser floating zone technique was used in order to grow millimetric high quality single crystal fibers. The as-grown fibers are completely transparent and inclusion free, exhibiting a cubic structure. Under ultraviolet (UV) excitation, a broad emission band appears at 551 nm. The europium doped fibers are translucent with a tetragonal structure and exhibit an intense red emission at room temperature under UV excitation. The fingerprint transition lines between the 5D0 and 7FJ(0–4) multiplets of the Eu3+ ions are observed with the main emission line at ∼ 606 nm due to 5D0→7F2 transition. Photoluminescence excitation and wavelength dependent the photoluminescence spectra confirm the existence of different Eu3+ optical centers. © 2011 American Institute of PhysicsFCT-PTDC/CTM/66195/2006FCT-SFRH/BD/45774/200

Morphology and physiology of anaerobic granular sludge exposed to organic solvents

The use of quantitative image analysis techniques, together with physiological information might be used to monitor and detect operational problems in advance to reactor performance failure. Industrial organic solvents such as white spirit are potentially harmful to granular sludge. In preliminary batch assays, 33 mg.Lˉ¹ of solvent caused 50% relative biomass activity loss. In an Expanded Granular Sludge Blanket reactor fed with 40 mg.Lˉ¹ of solvent, during 222 h, the reactor performance seemed to be unaffected, presenting COD removal efficiency constantly above 95 %. However, in the first hours of exposure the specific acetoclastic and the specific hydrogenotrophic methanogenic activities decreased by 29 and 21 %, respectively. The % of projected aggregates area with equivalent diameter (Deq) higher than 1 mm decreased from 81 to 53 % and consequently the % of projected area of small aggregates increased. The average equivalent diameter of the aggregates larger than 2 mm decreased as well as the settling velocity, showed that the granules experienced fragmentation phenomenon caused by the solvent shock load. The ratio between total filaments length and total aggregates projected area (LfA) increased 2 days before effluent volatile suspended solids, suggesting that LfA could be an early-warning indicator of washout events.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/13317/2003, POCTI/AMB/60141/2001

Effects of detergent shock loads on anaerobic granular sludge morphology and methanogenic activity

Two shock loads of a detergent (shock 1 with 0.15 gCOD/L during 56 h, and shock 2 with 0.30 gCOD/L during 222 h) were applied in a lab-scale EGSB reactor with 1.5 gCOD/L of ethanol. Quantitative image analysis and methanogenic activity measurements were used to characterize the surfactant effects. The COD removal efficiency was unaffected with 0.15 g/L of detergent. However, 88 h after exposure to 0.30 g/L of detergent the COD removal efficiency decreased drastically. In the first 8h of operation of shock 1, the specific methanogenic activity (SMA) was slightly stimulated and decreased afterwards, being recovered 5 days after the end of exposure time. Concerning the shock 2, the SMA was immediately and persistently reduced during the exposure time. Although, the SMA in the presence of H2/CO2 and ethanol were recovered, no improvement was detected in the SMA in the presence of acetate and propionate through the recovery phase. Acetoclastic bacteria are more sensitive to the toxic effects of surfactant, and, the effects are dependent of surfactant concentration and exposure time. The dynamic evolution of filaments length, aggregates area and aggregates density were well defined by the image analysis descriptors. The ratio filament length / total aggregate area proved to be a good washout early warning indicator, once it increased 3 and 5 days before effluent volatile suspended solids, respectively in shock load 1 and 2