Network models and community phylogenetic analyses are applied to assess the composition, structu... more Network models and community phylogenetic analyses are applied to assess the composition, structure, and ecological assembly mechanisms of microbial communities. Here we combine both approaches to investigate the temporal dynamics of network properties in individual samples of two activated sludge systems at different adaptation stages. At initial assembly stages, we observed microbial communities adapting to activated sludge, with an increase in network modularity and co-exclusion proportion, and a decrease in network clustering, here interpreted as a consequence of niche specialization. The selective pressure of deterministic factors at wastewater treatment plants produces this trend and maintains the structure of highly functional and specialized communities responding to seasonal environmental changes.
Wastewater treatment plants (WWTPs) are necessary to protect ecosystems quality and human health.... more Wastewater treatment plants (WWTPs) are necessary to protect ecosystems quality and human health. Their function relies on the degradation of organic matter and nutrients from a water influent, prior to the effluent release into the environment. In this work we studied the bacterial community dynamics of a municipal WWTP with a membrane bioreactor through 16S rRNA gene sequencing. The main phyla identified in the wastewater were Proteobacteria, Bacteroidetes, Chloroflexi, Planctomycetes and Actinobacteria. The WWTP is located in Spain and, like other studied WWTP in temperate climate zones, the temperature played a major role in community assembly. Seasonal community succession is observed along the two years sampling period, in addition to a continual annual drift in the microbial populations. The core community of the WWTP bioreactor was also studied, where a small fraction of sequence variants constituted a large fraction of the total abundance. This core microbiome stability alo...
A cell-to-cell communication system called quorum sensing (QS) promotes the transcription of cert... more A cell-to-cell communication system called quorum sensing (QS) promotes the transcription of certain target genes in bacterial cells leading to the activation of different cellular processes, some of them related to bacterial biofilm formation. The formation of bacterial biofilms favours antibiotic resistance, which is nowadays a significant public-health problem. In this study, the effect of selenium (SeNPs) and tellurium (TeNPs) nanoparticles was examined in two bacterial processes mediated by QS: violacein production by Chromobacterium violaceum and biofilm formation by Pseudomonas aeruginosa. For this purpose, quantification of the pigment production in the presence of these nanoparticles was monitored using the C. violaceum strain. Additionally, a combination of different microscopical imaging techniques was applied to examine the changes in the 3D biofilm structure of P. aeruginosa, which were quantified through performing architectural metric calculations (substratum area, ce...
Kaolin waste dumps contain a huge volume of material that cannot be commercialized due to the pre... more Kaolin waste dumps contain a huge volume of material that cannot be commercialized due to the presence of variable amounts of iron minerals, which impart a yellowish color to the kaolin. Elimination of iron from kaolin using either a chemical or a biological method was the aim of this study. The chemical leaching of iron from kaolin was carried out using response surface methodology to optimize the reaction conditions. Time was found to be the most influential variable, although oxalic acid must be present to leach 32% of the iron. Biological leaching was also assayed for 14 days using a Bacillus strain. The results of bacterial leaching of iron from kaolin showed <1% iron elimination.
Backgrounds: Nowadays, the main challenges in the wastewater treatment sector entail the need to ... more Backgrounds: Nowadays, the main challenges in the wastewater treatment sector entail the need to advance in the control and optimization of the processes. In adittion, the restrictions imposed in the discharge of certain pollutants, such as nitrogen and phosphorus, force modifications in the configuration of the treatment plants. Therefore, it is increasingly necessary to deepen knowledge of the dynamic of the microbial populations of the biological community in activated sludge, mainly protists and metazoans. Many studies have attempted to relate protists and metazoans to physicochemical and operational variables of WWTPs in order to reveal their possible value as bioindicators. However, these studies have been mainly descriptive and/or exploratory, and moreover they have not focused on the environmental interpretation. Objetives: Proposal new bioindicators of the biological nitrogen removal process. Methods: Samples from activated sludge, influent and treated effluent were collected every fifteen days during a year from six bioreactors belonging to four different WWTPs located in Spain. The estimation of the absolute density of protists and metazoans was carried out by direct counting under phase contrast microscopy. A dual approach was applied to investigate models of environmental interpretation of biological variables, using distance-based linear models (DISTLM), as well as the canonical correspondence analysis (CCA). Conclusions: The multivariate models constructed with DISTLM and CCA have provided relevant information about the relationships between protists and metazoans and some plant nitrogen compounds, allowing their ecological interpretation and obtaining new bioindicators for monitoring the biological nitrogen removal process in active sludge.
International journal of environmental research and public health, May 18, 2018
Quorum sensing (QS) is a mechanism dependent on bacterial density. This coordinated process is me... more Quorum sensing (QS) is a mechanism dependent on bacterial density. This coordinated process is mediated by the synthesis and the secretion of signal molecules, called autoinducers (AIs). -acyl-homoserine lactones (AHLs) are the most common AIs that are used by Gram-negative bacteria and are involved in biofilm formation. Quorum Quenching (QQ) is the interference of QS by producing hydrolyzing enzymes, among other strategies. The main objective of the present study was to identify QS and QQ strains from MBR wastewater treatment plants. A total of 99 strains were isolated from two Spanish plants that were intended to treat leachate from municipal solid waste. Five AHL producers were detected using AHL biosensor strains ( CV026 and NT1). Fifteen strains of seventy-one Gram-positive were capable of eliminating or reducing at least one AHL activity. The analysis of 16S rRNA gene sequence showed the importance of the genus in the production of biofilms and the relevance of the genus in th...
En este trabajo se exponen los resultados del estudio de las comunidades biológicas en tratamient... more En este trabajo se exponen los resultados del estudio de las comunidades biológicas en tratamientos avanzados para la eliminación de compuestos nitrogenados en tres plantas de fangos activos, con diferentes diseños, mediante una colaboración Universidad–Empresa. Los resultados se han analizado buscando posibles correlaciones o asociaciones entre las distintas variables (biológicas, biológicas/físico-químicas), con el fin de encontrar posibles bioindicadores en estos sistemas biológicos.
Los protistas son una de las principales comunidades de microorganismos implicadas en la eliminac... more Los protistas son una de las principales comunidades de microorganismos implicadas en la eliminación de contaminantes en los reactores biológicos de lodos activos, contribuyendo a la formación del flóculo (Arregui et al., 2007, 2008) y a la depredación de las poblaciones de bacterias (Pérez-Uz et al., 2005). En las depuradoras convencionales los ciliados representan la comunidad más abundante dentro de los componentes estables del sistema, siendo especialmente importantes los ciliados peritricos sésiles y los esticotricos (ambos asociados al flóculo); los flagelados y las amebas están asociados, salvo excepciones, a procesos de colonización y puesta en marcha de la depuradora o a problemas relacionados con la entrada de productos tóxicos a la planta, que producen una alteración en la estructura de la comunidad (Al-Shawani, 1991; Curds &amp;amp; Cockburn, 1970; Madoni, 1991, 1994, Madoni et al., 1993; Martín-Cereceda et al., 1996, 2002; Poole, 1984; Serrano et al., 2008). Los datos acerca de las comunidades de protistas en EDAR de alto rendimiento son muy escasas; el grupo de investigación compuesto por los autores de esta comunicación ha realizado, durante los años 2007 y 2008, un estudio en diversas plantas sobre la estructura de las comunidades asociadas a la eliminación de nitrógeno cuyos resultados se exponen en el presente artículo. Referencia Serrano, S., Arregui, L., Calvo, P., Salvadó, H., Zornoza, A., Fernández, N., Rodríguez, E., Pérez-Uz, B. (2008) Comunidades de protistas asociados a plantas con eliminación de nitrógeno. V Jornadas de Transferencia de Tecnología sobre Microbiología del Fango Activo. Sevilla, Spain.
ABSTRACT Occurrence and density of microbial populations, and particularly of the protists commun... more ABSTRACT Occurrence and density of microbial populations, and particularly of the protists community, are directly related to the operational parameters performance of wastewater treatment plants (WWTP) such as sludge retention time or effluent quality. Microscopic monitoring of floc structure and other biological factors as filamentous bacteria and protist populations, have become a frequent practice to evaluate the state of the purification processes; however, the application of biotic indexes is not as accurate as it would be expected. The microorganism species cited in different WWTP studies are very restrained if these communities are compared to those described in natural waters. &quot;In vivo&quot; observations using conventional or phase contrast optical microscopy are the most frequent method employed to identify protist species although precise identification is difficult to achieve in this way. The inaccurate assignment of species to other similar morphotypes following previous observations or reports in depuration processes is unfortunately too frequent in the plant laboratories. Besides, many specimens go undetected due difficulties such as small size, colorless cytoplasm, the presence of an agglutinate test or a lorica included within the flocs, etc. Therefore it would be feasible an increase on protists diversity if an accurate identification was performed. The use of general silver staining techniques or, more recently, of the fluorescent taxoid FLUTAX has facilitated solving some of the problems listed. In addition, most studies in the literature dealing with protist communities have been carried out on conventional activated sludge systems although more efficient activated sludge plants new designs are continuously developing in response to the legislation requirements concerning the removal of carbonaceous, nitrogen and phosphate compounds. These advanced nutrient removal systems combine aerobic, anoxic and anaerobic phases with distinct strategies of sludge recirculation. As it will be discussed, these treatments restraints are responsible to shape singular protist communities present in the biological reactors, becoming flagellates and amoebae usual components of the floc populations sharing this niche with typical crawling ciliate species.
Resumen: La observacion de bacterias con microscopia optica, en un laboratorio de Microbiologia, ... more Resumen: La observacion de bacterias con microscopia optica, en un laboratorio de Microbiologia, puede realizarse por diferentes procedimientos como son la observacion directa de microorganismos “in vivo” o el tratamiento con colorantes mediante tincion positiva y negativa, procesos dirigidos a incrementar el contraste y por consiguiente a optimizar el resultado. Se describen aqui los metodos y las tecnicas mas habituales para la observacion de muestras con microscopia optica, asi como procedimientos de observacion con microscopia de fluorescencia y confocal con diferentes tipos de fluorocromos y sondas moleculares. Palabras clave: Microscopia de campo claro y fluorescencia. Microscopia confocal. Tinciones. Frotis. Fijacion. Colorantes. Fluorocromos. Sondas moleculares.
El conocimiento integrado de las variables fisicoquimica , biologicas y operacionales permite apo... more El conocimiento integrado de las variables fisicoquimica , biologicas y operacionales permite aportar nuevos dalo para optimizar la nilrificacion en las e. taciones depuradoras de aguas residuales (EDAR) con sistema anoxicooxico, ambito con pocas experiencias a e cala real. Este trabajo establece la relacion entre las distinta · variable' y el rendimiento del proceso de bionitrificacion, utilizando para ello un analisi de correlacion bivariante. Los datos obtenidos han definido los parametros operacionales y fi icoquimico de may r relevancia para el control del proceso. como la carga masica.la DQO o el tiempo de retencion hidraulico. La lemperatura y el oxigeno no parecen ser parametros limitante para el proceo de nitrilicacion.
Microorganisms colonize surfaces and develop biofilms through interactions not yet thoroughly und... more Microorganisms colonize surfaces and develop biofilms through interactions not yet thoroughly understood, with important implications in water and wastewater systems. This study has investigated the interactions between N-acyl homoserine lactone (AHL)-producing bacteria, yeasts and protists, and their contribution to biofilm development. Sixty-one bacterial strains were isolated from activated sludge and screened for AHL production, with Aeromonas sp. found to be the dominant AHL-producer. Shewanella xiamenensis, Aeromonas allosaccharophila, Acinetobacter junii and Pseudomonas aeruginosa recorded the highest adherence capabilities, with S. xiamenensis being the most effective in surface colonization. Additionally, highly significant interactions (i.e., synergic or antagonistic) were described for dual and multistrain mixtures of bacterial strains (P. aeruginosa, S. xiamenensis, A. junii and P. stutzeri), as well as for strongly adherent bacteria co-cultured with yeasts. In this last...
ABSTRACT Gypsum board containing a shape-stabilized PCM either as a sheet or as pellets is thermo... more ABSTRACT Gypsum board containing a shape-stabilized PCM either as a sheet or as pellets is thermo-physically characterized. The main objective is to elucidate which is the most efficient way to introduce the PCM into gypsum boards by measuring the thermal transmittance, effective thermal conductivity, total heat accumulated, and the average heat capacity. At their light it can be concluded that a gypsum board containing 25% PCM is more thermally insulating than the gypsum without PCM, and the average heat capacity of the samples containing sheet-PCM and pellets-PCM are higher than the gypsum by itself due to the latent heat effect, being 41% and 33% respectively.
ABSTRACT According to the International Energy Agency (IEA) the primary energy production was inc... more ABSTRACT According to the International Energy Agency (IEA) the primary energy production was increased by 49% and CO2 emissions by 43% over the past 20 years. Furthermore, 30 - 40% of total energy consumption in developed countries comes from the private sector (housing and offices). Thermal energy storage (TES) is proposed as one way to improve the gap between energy consumption and energy supply. TES systems can store energy as sensible heat, latent heat or chemical reaction. Phase change materials (PCM) are extensively studied materials for thermal energy storage as latent heat because these materials have high phase change enthalpy in a wide variety of phase change temperature. Nowadays it is quite difficult to have all the reported information about PCM properties, not only the thermophysical ones but other relevant properties, even though there are different compilations. CES Selector is software used in material selection, besides being a materials database it permits to include new materials introducing their properties, as well as to classify them in several groups, to plot the data and combine graphs production with the material selection under the desired criteria. More than 300 substances used as PCM and reported in the literature were introduced in a new database created using CES Selector. Thermophysical properties as melting temperature (°C) and melting enthalpy (kJ·kg-1) have been plotted and PCM selections under different criteria were carried out. This database can be completed in the future with other relevant properties either than thermal such as chemical properties (durability in different media etc), reported density or viscosity at a given temperature or even cost of each material. Analyzing these plots it is observed that some PCM are represented occupying a wide range of a given thermophysical property. This is the case of CaCl2·6H2O: data came from 7 sources and the occupied area in the plot is the highest one from all the PCM reported. On the other hand, some other PCM are represented with smaller dots associated with a lower dispersion in the property values and this size may possibly be attributed to different reasons: scarce sources for experimental data or low dispersion among several experimental reported values. These results emphasize that there is a lack of standardization for the measurement of the PCM thermophysical properties.
Network models and community phylogenetic analyses are applied to assess the composition, structu... more Network models and community phylogenetic analyses are applied to assess the composition, structure, and ecological assembly mechanisms of microbial communities. Here we combine both approaches to investigate the temporal dynamics of network properties in individual samples of two activated sludge systems at different adaptation stages. At initial assembly stages, we observed microbial communities adapting to activated sludge, with an increase in network modularity and co-exclusion proportion, and a decrease in network clustering, here interpreted as a consequence of niche specialization. The selective pressure of deterministic factors at wastewater treatment plants produces this trend and maintains the structure of highly functional and specialized communities responding to seasonal environmental changes.
Wastewater treatment plants (WWTPs) are necessary to protect ecosystems quality and human health.... more Wastewater treatment plants (WWTPs) are necessary to protect ecosystems quality and human health. Their function relies on the degradation of organic matter and nutrients from a water influent, prior to the effluent release into the environment. In this work we studied the bacterial community dynamics of a municipal WWTP with a membrane bioreactor through 16S rRNA gene sequencing. The main phyla identified in the wastewater were Proteobacteria, Bacteroidetes, Chloroflexi, Planctomycetes and Actinobacteria. The WWTP is located in Spain and, like other studied WWTP in temperate climate zones, the temperature played a major role in community assembly. Seasonal community succession is observed along the two years sampling period, in addition to a continual annual drift in the microbial populations. The core community of the WWTP bioreactor was also studied, where a small fraction of sequence variants constituted a large fraction of the total abundance. This core microbiome stability alo...
A cell-to-cell communication system called quorum sensing (QS) promotes the transcription of cert... more A cell-to-cell communication system called quorum sensing (QS) promotes the transcription of certain target genes in bacterial cells leading to the activation of different cellular processes, some of them related to bacterial biofilm formation. The formation of bacterial biofilms favours antibiotic resistance, which is nowadays a significant public-health problem. In this study, the effect of selenium (SeNPs) and tellurium (TeNPs) nanoparticles was examined in two bacterial processes mediated by QS: violacein production by Chromobacterium violaceum and biofilm formation by Pseudomonas aeruginosa. For this purpose, quantification of the pigment production in the presence of these nanoparticles was monitored using the C. violaceum strain. Additionally, a combination of different microscopical imaging techniques was applied to examine the changes in the 3D biofilm structure of P. aeruginosa, which were quantified through performing architectural metric calculations (substratum area, ce...
Kaolin waste dumps contain a huge volume of material that cannot be commercialized due to the pre... more Kaolin waste dumps contain a huge volume of material that cannot be commercialized due to the presence of variable amounts of iron minerals, which impart a yellowish color to the kaolin. Elimination of iron from kaolin using either a chemical or a biological method was the aim of this study. The chemical leaching of iron from kaolin was carried out using response surface methodology to optimize the reaction conditions. Time was found to be the most influential variable, although oxalic acid must be present to leach 32% of the iron. Biological leaching was also assayed for 14 days using a Bacillus strain. The results of bacterial leaching of iron from kaolin showed <1% iron elimination.
Backgrounds: Nowadays, the main challenges in the wastewater treatment sector entail the need to ... more Backgrounds: Nowadays, the main challenges in the wastewater treatment sector entail the need to advance in the control and optimization of the processes. In adittion, the restrictions imposed in the discharge of certain pollutants, such as nitrogen and phosphorus, force modifications in the configuration of the treatment plants. Therefore, it is increasingly necessary to deepen knowledge of the dynamic of the microbial populations of the biological community in activated sludge, mainly protists and metazoans. Many studies have attempted to relate protists and metazoans to physicochemical and operational variables of WWTPs in order to reveal their possible value as bioindicators. However, these studies have been mainly descriptive and/or exploratory, and moreover they have not focused on the environmental interpretation. Objetives: Proposal new bioindicators of the biological nitrogen removal process. Methods: Samples from activated sludge, influent and treated effluent were collected every fifteen days during a year from six bioreactors belonging to four different WWTPs located in Spain. The estimation of the absolute density of protists and metazoans was carried out by direct counting under phase contrast microscopy. A dual approach was applied to investigate models of environmental interpretation of biological variables, using distance-based linear models (DISTLM), as well as the canonical correspondence analysis (CCA). Conclusions: The multivariate models constructed with DISTLM and CCA have provided relevant information about the relationships between protists and metazoans and some plant nitrogen compounds, allowing their ecological interpretation and obtaining new bioindicators for monitoring the biological nitrogen removal process in active sludge.
International journal of environmental research and public health, May 18, 2018
Quorum sensing (QS) is a mechanism dependent on bacterial density. This coordinated process is me... more Quorum sensing (QS) is a mechanism dependent on bacterial density. This coordinated process is mediated by the synthesis and the secretion of signal molecules, called autoinducers (AIs). -acyl-homoserine lactones (AHLs) are the most common AIs that are used by Gram-negative bacteria and are involved in biofilm formation. Quorum Quenching (QQ) is the interference of QS by producing hydrolyzing enzymes, among other strategies. The main objective of the present study was to identify QS and QQ strains from MBR wastewater treatment plants. A total of 99 strains were isolated from two Spanish plants that were intended to treat leachate from municipal solid waste. Five AHL producers were detected using AHL biosensor strains ( CV026 and NT1). Fifteen strains of seventy-one Gram-positive were capable of eliminating or reducing at least one AHL activity. The analysis of 16S rRNA gene sequence showed the importance of the genus in the production of biofilms and the relevance of the genus in th...
En este trabajo se exponen los resultados del estudio de las comunidades biológicas en tratamient... more En este trabajo se exponen los resultados del estudio de las comunidades biológicas en tratamientos avanzados para la eliminación de compuestos nitrogenados en tres plantas de fangos activos, con diferentes diseños, mediante una colaboración Universidad–Empresa. Los resultados se han analizado buscando posibles correlaciones o asociaciones entre las distintas variables (biológicas, biológicas/físico-químicas), con el fin de encontrar posibles bioindicadores en estos sistemas biológicos.
Los protistas son una de las principales comunidades de microorganismos implicadas en la eliminac... more Los protistas son una de las principales comunidades de microorganismos implicadas en la eliminación de contaminantes en los reactores biológicos de lodos activos, contribuyendo a la formación del flóculo (Arregui et al., 2007, 2008) y a la depredación de las poblaciones de bacterias (Pérez-Uz et al., 2005). En las depuradoras convencionales los ciliados representan la comunidad más abundante dentro de los componentes estables del sistema, siendo especialmente importantes los ciliados peritricos sésiles y los esticotricos (ambos asociados al flóculo); los flagelados y las amebas están asociados, salvo excepciones, a procesos de colonización y puesta en marcha de la depuradora o a problemas relacionados con la entrada de productos tóxicos a la planta, que producen una alteración en la estructura de la comunidad (Al-Shawani, 1991; Curds &amp;amp; Cockburn, 1970; Madoni, 1991, 1994, Madoni et al., 1993; Martín-Cereceda et al., 1996, 2002; Poole, 1984; Serrano et al., 2008). Los datos acerca de las comunidades de protistas en EDAR de alto rendimiento son muy escasas; el grupo de investigación compuesto por los autores de esta comunicación ha realizado, durante los años 2007 y 2008, un estudio en diversas plantas sobre la estructura de las comunidades asociadas a la eliminación de nitrógeno cuyos resultados se exponen en el presente artículo. Referencia Serrano, S., Arregui, L., Calvo, P., Salvadó, H., Zornoza, A., Fernández, N., Rodríguez, E., Pérez-Uz, B. (2008) Comunidades de protistas asociados a plantas con eliminación de nitrógeno. V Jornadas de Transferencia de Tecnología sobre Microbiología del Fango Activo. Sevilla, Spain.
ABSTRACT Occurrence and density of microbial populations, and particularly of the protists commun... more ABSTRACT Occurrence and density of microbial populations, and particularly of the protists community, are directly related to the operational parameters performance of wastewater treatment plants (WWTP) such as sludge retention time or effluent quality. Microscopic monitoring of floc structure and other biological factors as filamentous bacteria and protist populations, have become a frequent practice to evaluate the state of the purification processes; however, the application of biotic indexes is not as accurate as it would be expected. The microorganism species cited in different WWTP studies are very restrained if these communities are compared to those described in natural waters. &quot;In vivo&quot; observations using conventional or phase contrast optical microscopy are the most frequent method employed to identify protist species although precise identification is difficult to achieve in this way. The inaccurate assignment of species to other similar morphotypes following previous observations or reports in depuration processes is unfortunately too frequent in the plant laboratories. Besides, many specimens go undetected due difficulties such as small size, colorless cytoplasm, the presence of an agglutinate test or a lorica included within the flocs, etc. Therefore it would be feasible an increase on protists diversity if an accurate identification was performed. The use of general silver staining techniques or, more recently, of the fluorescent taxoid FLUTAX has facilitated solving some of the problems listed. In addition, most studies in the literature dealing with protist communities have been carried out on conventional activated sludge systems although more efficient activated sludge plants new designs are continuously developing in response to the legislation requirements concerning the removal of carbonaceous, nitrogen and phosphate compounds. These advanced nutrient removal systems combine aerobic, anoxic and anaerobic phases with distinct strategies of sludge recirculation. As it will be discussed, these treatments restraints are responsible to shape singular protist communities present in the biological reactors, becoming flagellates and amoebae usual components of the floc populations sharing this niche with typical crawling ciliate species.
Resumen: La observacion de bacterias con microscopia optica, en un laboratorio de Microbiologia, ... more Resumen: La observacion de bacterias con microscopia optica, en un laboratorio de Microbiologia, puede realizarse por diferentes procedimientos como son la observacion directa de microorganismos “in vivo” o el tratamiento con colorantes mediante tincion positiva y negativa, procesos dirigidos a incrementar el contraste y por consiguiente a optimizar el resultado. Se describen aqui los metodos y las tecnicas mas habituales para la observacion de muestras con microscopia optica, asi como procedimientos de observacion con microscopia de fluorescencia y confocal con diferentes tipos de fluorocromos y sondas moleculares. Palabras clave: Microscopia de campo claro y fluorescencia. Microscopia confocal. Tinciones. Frotis. Fijacion. Colorantes. Fluorocromos. Sondas moleculares.
El conocimiento integrado de las variables fisicoquimica , biologicas y operacionales permite apo... more El conocimiento integrado de las variables fisicoquimica , biologicas y operacionales permite aportar nuevos dalo para optimizar la nilrificacion en las e. taciones depuradoras de aguas residuales (EDAR) con sistema anoxicooxico, ambito con pocas experiencias a e cala real. Este trabajo establece la relacion entre las distinta · variable' y el rendimiento del proceso de bionitrificacion, utilizando para ello un analisi de correlacion bivariante. Los datos obtenidos han definido los parametros operacionales y fi icoquimico de may r relevancia para el control del proceso. como la carga masica.la DQO o el tiempo de retencion hidraulico. La lemperatura y el oxigeno no parecen ser parametros limitante para el proceo de nitrilicacion.
Microorganisms colonize surfaces and develop biofilms through interactions not yet thoroughly und... more Microorganisms colonize surfaces and develop biofilms through interactions not yet thoroughly understood, with important implications in water and wastewater systems. This study has investigated the interactions between N-acyl homoserine lactone (AHL)-producing bacteria, yeasts and protists, and their contribution to biofilm development. Sixty-one bacterial strains were isolated from activated sludge and screened for AHL production, with Aeromonas sp. found to be the dominant AHL-producer. Shewanella xiamenensis, Aeromonas allosaccharophila, Acinetobacter junii and Pseudomonas aeruginosa recorded the highest adherence capabilities, with S. xiamenensis being the most effective in surface colonization. Additionally, highly significant interactions (i.e., synergic or antagonistic) were described for dual and multistrain mixtures of bacterial strains (P. aeruginosa, S. xiamenensis, A. junii and P. stutzeri), as well as for strongly adherent bacteria co-cultured with yeasts. In this last...
ABSTRACT Gypsum board containing a shape-stabilized PCM either as a sheet or as pellets is thermo... more ABSTRACT Gypsum board containing a shape-stabilized PCM either as a sheet or as pellets is thermo-physically characterized. The main objective is to elucidate which is the most efficient way to introduce the PCM into gypsum boards by measuring the thermal transmittance, effective thermal conductivity, total heat accumulated, and the average heat capacity. At their light it can be concluded that a gypsum board containing 25% PCM is more thermally insulating than the gypsum without PCM, and the average heat capacity of the samples containing sheet-PCM and pellets-PCM are higher than the gypsum by itself due to the latent heat effect, being 41% and 33% respectively.
ABSTRACT According to the International Energy Agency (IEA) the primary energy production was inc... more ABSTRACT According to the International Energy Agency (IEA) the primary energy production was increased by 49% and CO2 emissions by 43% over the past 20 years. Furthermore, 30 - 40% of total energy consumption in developed countries comes from the private sector (housing and offices). Thermal energy storage (TES) is proposed as one way to improve the gap between energy consumption and energy supply. TES systems can store energy as sensible heat, latent heat or chemical reaction. Phase change materials (PCM) are extensively studied materials for thermal energy storage as latent heat because these materials have high phase change enthalpy in a wide variety of phase change temperature. Nowadays it is quite difficult to have all the reported information about PCM properties, not only the thermophysical ones but other relevant properties, even though there are different compilations. CES Selector is software used in material selection, besides being a materials database it permits to include new materials introducing their properties, as well as to classify them in several groups, to plot the data and combine graphs production with the material selection under the desired criteria. More than 300 substances used as PCM and reported in the literature were introduced in a new database created using CES Selector. Thermophysical properties as melting temperature (°C) and melting enthalpy (kJ·kg-1) have been plotted and PCM selections under different criteria were carried out. This database can be completed in the future with other relevant properties either than thermal such as chemical properties (durability in different media etc), reported density or viscosity at a given temperature or even cost of each material. Analyzing these plots it is observed that some PCM are represented occupying a wide range of a given thermophysical property. This is the case of CaCl2·6H2O: data came from 7 sources and the occupied area in the plot is the highest one from all the PCM reported. On the other hand, some other PCM are represented with smaller dots associated with a lower dispersion in the property values and this size may possibly be attributed to different reasons: scarce sources for experimental data or low dispersion among several experimental reported values. These results emphasize that there is a lack of standardization for the measurement of the PCM thermophysical properties.
Backgrounds: Nowadays, the main challenges in the wastewater treatment sector entail the need to ... more Backgrounds: Nowadays, the main challenges in the wastewater treatment sector entail the need to advance in the control and optimization of the processes. In adittion, the restrictions imposed in the discharge of certain pollutants, such as nitrogen and phosphorus, force modifications in the configuration of the treatment plants. Therefore, it is increasingly necessary to deepen knowledge of the dynamic of the microbial populations of the biological community in activated sludge, mainly protists and metazoans. Many studies have attempted to relate protists and metazoans to physicochemical and operational variables of WWTPs in order to reveal their possible value as bioindicators. However, these studies have been mainly descriptive and/or exploratory, and moreover they have not focused on the environmental interpretation. Objetives: Proposal new bioindicators of the biological nitrogen removal process.
Methods: Samples from activated sludge, influent and treated effluent were collected every fifteen days during a year from six bioreactors belonging to four different WWTPs located in Spain. The estimation of the absolute density of protists and metazoans was carried out by direct counting under phase contrast microscopy. A dual approach was applied to investigate models of environmental interpretation of biological variables, using distance-based linear models (DISTLM), as well as the canonical correspondence analysis (CCA).
Conclusions: The multivariate models constructed with DISTLM and CCA have provided relevant information about the relationships between protists and metazoans and some plant nitrogen compounds, allowing their ecological interpretation and obtaining new bioindicators for monitoring the biological nitrogen removal process in active sludge.
En este trabajo se exponen los resultados del estudio de las comunidades biológicas en tratamient... more En este trabajo se exponen los resultados del estudio de las comunidades biológicas en tratamientos avanzados para la eliminación de compuestos nitrogenados en tres plantas de fangos activos, con diferentes diseños, mediante una colaboración Universidad–Empresa. Los resultados se han analizado buscando posibles correlaciones o asociaciones entre las distintas variables (biológicas, biológicas/físico-químicas), con el fin de encontrar posibles bioindicadores en estos sistemas biológicos.
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Methods: Samples from activated sludge, influent and treated effluent were collected every fifteen days during a year from six bioreactors belonging to four different WWTPs located in Spain. The estimation of the absolute density of protists and metazoans was carried out by direct counting under phase contrast microscopy. A dual approach was applied to investigate models of environmental interpretation of biological variables, using distance-based linear models (DISTLM), as well as the canonical correspondence analysis (CCA).
Conclusions: The multivariate models constructed with DISTLM and CCA have provided relevant information about the relationships between protists and metazoans and some plant nitrogen compounds, allowing their ecological interpretation and obtaining new bioindicators for monitoring the biological nitrogen removal process in active sludge.