585 research outputs found

    Anaerobic reactors: specific methanogenic activity and potential for bioregeneration of recalcitrant compounds in powdered activated carbon

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    This work is focused on anaerobic reactors. The process is a complex syntrophic interaction between many different microorganisms to degrade organic compounds and obtain methane as final product; To determine the “health” of the reactor a Specific Methanogenic Activity (SMA) test is performed. Unfortunately, there is no standard for this test. Pharmaceutical Active Compounds have been appearing in effluents of wastewater treatment plants, becoming post-treatment with Activated Carbon a major area of interest, but becomes saturated and needs to be replaced; bioregeneration could be an economically feasible option to solve this issue. The aim of this work was to find the best SMA conditions to evaluate digester health and to study bioregeneration of PAC under anaerobic conditions. When testing SMA this work had better results using glucose as main carbon source rather than acetate, opposite from literature predictions. It also was found that no centrifugation was needed, indicated that possible some important cofactor was excreted by some microorganism. FISH showed a predominance of Methanosaeta in one inoculum. No results on PAC bioregeneration where found, but when less than 50 mgL-1 of diclofenac was used an increase of methane production was detected, since diclofenac was not degraded it could imply that supplies energy to methanogens.Open Acces

    Developing a novel and versatile approach to study populations of microbes on surfaces

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    Spatial structure, for example regarding antibiotic gradients, is an important topic of investigation in microbial ecology and evolution. Experiments investigating pop- ulation dynamics in spatially-structured environments are often performed on agar plates. Whilst inexpensive and straightforward, these provide only rudimentary temporal and spatial control of environmental conditions. In chemostats and microfluidic devices, for well-mixed and micrometre-scale environments, respectively, regulating media inflow and outflow enables environ- mental control. We combine proven use of agar surfaces with such flow-enabled control in a novel, low-cost fluidic device; the device comprises an elastomer supporting base with a thin agar sheet on top on which microbes grow. Indented channels in the base allow flow of media/antibiotics below the agar surface. A Raspberry-Pi-operated camera allows for time-lapse imaging suitable for quantita- tive image analysis. As a proof of principle, we used our device for extended and robust growth of non-motile E. coli and motile P. aeruginosa maintaining the initial speed with which colonies propagate over three days, whilst a continual speed decrease occurred on agar plates. Guided by simulations of flow and diffusion, we then used the device to create stable antibiotic gradients within the agar. Along these gradients, we found P. aeruginosa exhibit unique microbial growth patterns with local adaptations. Because flow below the agar surface can be controlled spatially and temporally, the device promises a range of applications for studying microbial ecology and evolution in spatially continuous environments at a substrate-air interface.Engineering and Physical Sciences Research Council (EPSRC

    Enantioseparations with polysaccharide-based chiral stationary phases in HPLC. Application to the enantioselective evaluation of the biodegradability of chiral drugs in activated sludge from a Valencian waste water treatment plant

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    The chiral nature of living systems has obvious implications for the biologically active compounds that interact with them. At the molecular level, chirality represents an intrinsic property of the essential building blocks of life, such as amino acids and sugars, and therefore, of peptides, proteins, enzymes, carbohydrates, nucleosides and a number of alkaloids and hormones. As a consequence, processes mediated by biological systems are stereochemistry-sensitive, and a pair of enantiomers can have different effects on living organisms. The scientific community has been studying the implications of chirality for life for more than a century. Today, it is still a topic of active research and debate due to the large number of chiral molecules that are part of living organisms and of our everyday life. In this context, analytical methods for the separation of the enantiomers of chiral molecules play a crucial role. Undoubtedly, the use of chiral stationary phases (CSPs) in high performance liquid chromatography (HPLC) is the preferred choice for enantioseparations. This is evidenced by the huge number of CSPs available on the market. This fact, together with the trial-and-error methods commonly used to select the most suitable chromatographic system (CSP/mobile phase combination) for a given enantioseparation, results in enormous cost and experimental effort. This makes it necessary to develop strategies to simplify this important task. This Doctoral Thesis has two clearly differentiated main objectives: (i) To contribute to the knowledge of chiral HPLC with polysaccharide-based CSPs (the most popular commercial ones: three amylose and five cellulose derivatives), and hydro-organic mobile phases (comprising acetonitrile (ACN) and methanol (MeOH) aqueous solutions compatible with aqueous matrices and mass spectrometry (MS) detection). To this end, the following specific objectives were set: (a) to contribute to a rational selection of the chromatographic system to separate the enantiomers of a given compound. To this end, the retention and enantioresolution of a large dataset of structurally unrelated chiral compounds (approximately 60 basic and neutral drugs and pesticides) in the chromatographic systems above-indicated is compared. Moreover, quantitative structure-property relationships (QSPRs) for enantioresolution related data obtained in some of the chromatographic systems studied are developed. (b) To explore the use of deconvolution of overlapping peaks to achieve the mathematical resolution when the baseline resolution cannot be achieved experimentally. To illustrate the potential of this peak model strategy, the enantioseparation of eight chiral drugs in five polysaccharide-based CSPs and ACN or MeOH hydro-organic mobile phases at different separation temperatures is considered. (ii) To contribute to the advancement of knowledge of the risks and hazards of chiral pollutants. To this end, OECD (Organisation for Economic Co-operation and Development) biodegradability tests using activated sludge from a Valencian waste water treatment plant (Quart Benàger) are performed for some common chiral pharmaceutical pollutants: trimeprazine, ibuprofen, ketoprofen, bupivacaine, mepivacaine, prilocaine and propanocaine. Next, the separation and determination of the enantiomers of the intact compound is performed using chiral HPLC methods (with amylose- or cellulose-based CSPs and ACN or MeOH hydro-organic mobile phases compatible with aqueous matrices and MS detection) developed for that purpose

    Modelación matemática del proceso de crecimiento de microalgas en el tratamiento de aguas residuales Aplicación a un fotobiorreactor de membranas (MPBR).

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    Tesis por compendio[ES] En el contexto actual de escasez de recursos que sufre el planeta (biomasa, agua y energía), la tecnología basada en los cultivos de microalgas para el tratamiento de aguas residuales aparece como una tecnología muy interesante que permite no sólo la eliminación de los nutrientes (N y P) presentes en el agua, sino también la recuperación de estos nutrientes en la producción de una biomasa algal de alto valor con diversas aplicaciones: generación de biogás, producción de biocombustibles y biofertilizantes, elaboración de fármacos y cosméticos, etc. Estudios previos han demostrado que el efluente de un reactor anaerobio de membranas (AnMBR) resulta ser un medio de cultivo óptimo para el crecimiento de las microalgas. No obstante, la mayoría de los estudios existentes se han llevado a cabo a escala laboratorio en condiciones controladas de luz, temperatura, pH, carga de nutrientes, etc., y normalmente siempre en experimentos batch. Este trabajo consiste en el estudio y modelación matemática del proceso de cultivo de microalgas en una planta piloto de fotobiorreactores de membrana (MPBR) operando en continuo y en condiciones outdoor para el tratamiento del efluente de un sistema AnMBR que trata agua residual urbana real. Durante la fase de experimentación de los cultivos de microalgas se han llevado a cabo diversos experimentos en la planta MPBR donde se han evaluado diversos factores que afectan al crecimiento de las microalgas: temperatura, luz solar, tiempo de retención celular (TRC), carga de nutrientes o tiempo de retención hidráulico (TRH), sistema de recirculación del cultivo y el volumen en zona oscura. Los resultados obtenidos muestran la enorme importancia de las condiciones ambientales (luz solar y temperatura) en el rendimiento de los cultivos de microalgas. La temperatura óptima del cultivo de microalgas con predominancia del género Scenedesmus sp. resultó estar en torno a los 25ºC, mientras que temperaturas por debajo de 20ºC y por encima de 25ºC afectaron negativamente a la productividad de biomasa. La operación del sistema de fotobiorreactores (FBR) sin membranas para TRH 8 días y en condiciones ambientales favorables consiguió reducir la concentración de nutrientes por debajo de los límites de vertido que marca la Directiva 98/15/CE (10 mg N·L-1 y 1 mg P·L-1) alcanzando valores de eliminación de 75,2% de N y 77,9% de P. La operación del sistema MPBR permitió desacoplar el TRC del TRH en la operación de los FBR, lo que resultó en una mejora general del rendimiento de los cultivos de microalgas y permitió obtener un efluente libre de sólidos con alto potencial de reutilización. Los sistemas de recirculación del cultivo de microalgas comparados en el estudio (bombeo mecánico vs sistema airlift) no afectaron significativamente al rendimiento del cultivo. Por otro lado, reduciendo el volumen en zona oscura de un 27,2% al 13,6% en el sistema MPBR se consiguió un incremento del 40% en la productividad de biomasa. Mediante el uso de los datos obtenidos en planta piloto se ha desarrollado un modelo matemático de crecimiento de microalgas que permite simular de manera muy precisa (R2 = 0,9954) el comportamiento de los cultivos de microalgas en un sistema MPBR. Este modelo utiliza la notación y terminología de los modelos ASM, y consta de un total de 14 componentes (10 solubles y 4 suspendidos), 11 procesos gobernados por la cinética y los equilibrios ácido-base que determinan el pH del medio. Además, el modelo considera los efectos la luz y la temperatura en el crecimiento. Como novedad interesante respecto a otros modelos matemáticos de crecimiento de microalgas ya publicados, este modelo contempla, en condiciones de ausencia de P en el medio de cultivo, el crecimiento de las microalgas a partir del polifosfato almacenado internamente. El modelo desarrollado en este trabajo pretende ser una herramienta para facilitar la implementación futura de la tecnología de cultivos de microalgas en una EDAR a escala industrial.[CAT] En el context actual d'escassetat de recursos que sofreix el planeta (biomassa, agua i energia), la tecnologia basada en els cultius de microalgues per al tractament d'aigües residuals apareix com una tecnologia molt interessant que permet no només l'eliminació dels nutrients (N i P) presents a l'aigua, sinó també la recuperació d'aquests nutrients amb la producció d'una biomassa algal d'alt valor amb diverses aplicacions: generació de biogàs, producció de biocombustibles i biofertilitzants, elaboració de fàrmacs i cosmètics, etc. Estudis previs han demostrat que l'efluent d'un reactor anaerobi de membranes (AnMBR) resulta ser un mitjà de cultiu òptim per al creixement de les microalgues. Tot i això, la majoria dels estudis existents s'han dut a terme a escala laboratori en condicions controlades de llum, temperatura, pH, càrrega de nutrients, etc., i normalment sempre en experiments batch. Aquest treball consisteix en l'estudi i la modelació matemàtica del procés de cultiu de microalgues en una planta pilot de fotobioreactors de membrana (MPBR) operant en continu i en condicions outdoor per al tractament de l'efluent d'un sistema AnMBR que tracta aigua residual urbana real. Durant la fase d'experimentació dels cultius de microalgues s'han dut a terme diversos experiments a la planta MPBR on s'han avaluat diversos factors que afecten al creixement de les microalgues: temperatura, llum solar, temps de retenció cel·lular (TRC), càrrega de nutrients o temps de retenció hidràulic (TRH), sistema de recirculació del cultiu i el volum en zona obscura. Els resultats obtinguts mostren l'enorme importància de les condicions ambientals (llum solar i temperatura) en el rendiment dels cultius de microalgues. La temperatura òptima del cultiu de microalgues amb predominança del gènere Scenedesmus sp. va resultar estar entorn als 25ºC, mentre que temperatures per sota de 20ºC i per sobre de 25ºC van afectar negativament a la productivitat de biomassa. L'operació del sistema de fotobioreactors (FBR) sense membranes per a TRH 8 dies i en condicions ambientals favorables va aconseguir reduir la concentració de nutrients per sota dels límits d'abocament que marca la Directiva 98/15/CE (10 mg N·L-1 i 1 mg (P·L-1) assolint valors d'eliminació de 75,2% de N i 77,9% de P. L'operació del sistema MPBR va permetre desacoblar el TRC del TRH en l'operació dels FBR, la qual cosa va resultar en una millora general del rendiment dels cultius de microalgues i va permetre obtenir un efluent lliure de sòlids amb un alt potencial de reutilització. Els sistemes de recirculació del cultiu de microalgues comparats en aquest estudi (bombeig mecànic vs sistema airlift) no van afectar significativament al rendiment del cultiu. D'altra banda, reduint el volum en zona obscura del 27,2% al 13,6% al sistema MPBR es va aconseguir un increment del 40% en la productivitat de biomassa. Mitjançant l'ús de les dades obtingudes a la planta pilot s'ha desenvolupat un model matemàtic de creixement de microalgues que permet simular de manera molt precisa (R2 = 0,9954) el comportament dels cultius de microalgues en un sistema MPBR. Aquest model utilitza la notació i la terminologia dels models ASM, i consta d'un total de 14 components (10 solubles i 4 suspesos), 11 processos governats per la cinètica i els equilibris àcid-base que determinen el pH del medi. A més, el model considera els efectes de la llum i la temperatura en el creixement. Com a novetat interessant respecte d'altres models matemàtics de creixement de microalgues ja publicats, aquest model contempla, en condicions d'absència de P en el mitjà de cultiu, el creixement de les microalgues a partir del polifosfat emmagatzemat internament. El model desenvolupat en aquest treball pretén ser una eina per facilitar la implementació futura de la tecnologia de cultius de microalgues a una EDAR a escala industrial.[EN] In the actual context of resource scarcity along the world (biomass, water and energy), microalgae-based technology for wastewater treatment appears as a promising technology that allows not only nutrient removal (N and P) from wastewater, but also the recovery of these nutrients for the production of high-value algal biomass which has different applications: biogas generation, biofuel and biofertilizer production, pharmaceuticals and cosmetics manufacturing, etc. Previous studies have proved that the effluent from an anaerobic membrane bioreactor (AnMBR) could be a suitable growth medium for microalgae cultivation. However, most of the existing studies have been carried out at bench scale under controlled conditions of light, temperature, pH, nutrient load, etc., when working in batch mode. The present work consists of the study and mathematical modelling of an outdoor pilot-scale membrane photobioreactor (MPBR) for microalgae cultivation under continuous operation for treating the effluent of an AnMBR system fed with real municipal wastewater. During the experimental phase of microalgae cultivation, different experiments were carried out in the MPBR plant to evaluate the main factors that affect microalgae growth: temperature, solar light irradiance, biomass retention time (BRT), nutrient load or hydraulic retention time (HRT), the algae culture recirculation system and the non-photic volume. The results obtained show the significant effect of the environmental conditions (solar light and temperature) on the microalgae cultivation performance. Optimum temperature for the microalgae cultures with a predominance of the genus Scenedesmus sp. resulted to be around 25ºC, while temperatures below 20ºC and above 25ºC negatively affected biomass productivity. During the operation of the photobioreactors (PBRs) system without membranes at HRT of 8 days and under favourable environmental conditions, it was possible to comply with effluent nutrient discharge limits established by Directive 98/15/CE (10 mg N·L-1 and 1 mg P·L-1) and to achieve nutrient removal efficiencies of 75.2% of N and 77.9% of P. The MPBR plant allowed decoupling BRT and TRH in the PBRs operation, which resulted in a general improvement of the microalgae cultivation performance and allowed to obtain a solid-free effluent with high potential for reuse applications. The microalgae culture recirculation systems compared in the study (mechanical pumping vs airlift system) did not significantly affect the culture performance. Moreover, reducing the non-photic volume fraction in the MPBR system from 27.2% to 13.6% resulted in an increase of 40% in biomass productivity. A mathematical model of microalgal growth was developed by making use of the data obtained in the pilot plant. This model was able to reproduce accurately (R2 = 0.9954) the overall microalgae cultivation performance in an MPBR system. This model uses the notation and terminology of the ASM models, and it considers a total of 14 components (10 soluble and 4 suspended), 11 processes governed by kinetics and acid-base equilibria to calculate the pH of the medium. In addition, the model considers the effects of solar light and temperature on microalgae growth. As an interesting novelty with respect to other published mathematical models of microalgae growth, this model contemplates the possibility of using the stored polyphosphate for growing in the absence of P in the culture medium. The model developed in this work is intended to be a tool to promote the future implementation of microalgae cultivation technology on full-scale WWTP.This research was supported by the Spanish Ministry of Economy and Competitiveness (MINECO, Projects CTM2011-28595-C02-01/02, CTM2014-54980-C2-1-R and CTM2014-54980-C2-2-R) jointly with the European Regional Development Fund (ERDF) and Generalitat Valenciana (GVA-ACOMP2013/203), which are gratefully acknowledged. The authors also like to acknowledge the support received from Generalitat Valenciana via one VALi+d post-doctoral grant (APOSTD/2014/049).Viruela Navarro, A. (2023). Modelación matemática del proceso de crecimiento de microalgas en el tratamiento de aguas residuales Aplicación a un fotobiorreactor de membranas (MPBR) [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/195826Compendi

    Producción de ácido fumárico con Rhizopus arrhizus

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    Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, leída el 20-01-2023La necesidad del desarrollo de procesos industriales sostenibles ha llevado al concepto de biorrefinería, por el cual se usan materias primas renovables (biomasa) como punto de partida de procesos industriales. En el contexto de estos procesos el ácido fumárico está considerado uno de los productos químicos más prometedores para su obtención industrial, ya que tiene una amplia variedad de aplicaciones industriales que permitirían el desarrollo de una nueva industria sostenible en la valorización de biomasa, constituyendo una alternativa a la petroquímica. Por esta razón, en este trabajo se ha abordado el estudio de un proceso fermentativo de producción de ácido fumárico a partir de residuos de fruta, ya que son ricos en azúcares fermentables. Para esta producción se utilizan determinados hongos filamentosos que son conocidos por ser los mejores productores naturales de ácido fumárico. La cepa Rhizopus arrhizus NRRL 1526 ha sido la seleccionada para el desarrollo de este trabajo...The need for the development of sustainable industrial processes has led to the biorefinery concept, whereby renewable raw materials (biomass) are used as astarting point for industrial processes. In the context of these processes, fumaric acidis considered one of the most promising chemical products for industrial production, since it has a wide variety of industrial applications that would allow the development of a new sustainable industry in the revaluation of biomass, constituting an alternative to petrochemicals. For this reason, in this work we have approached the study of a fermentative process for the production of fumaric acid from fruit residues, since they are rich infermentable sugars. For this production, certain filamentous fungi are used, which are known to be the best natural producers of fumaric acid. The strain Rhizopus arrhizus NRRL 1526 has been selected for the development of this work...Fac. de Ciencias QuímicasTRUEunpu

    Rhizosphere processes and associated phosphorus solubilisation during soil drying and rewetting

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    Phosphorus (P) is at the heart of modern agriculture, which helps to sustain crop production. Many of the key processes centered around P solubilisation in the rhizosphere govern both plant uptake or potential leaching. However, the processes of controlling P solubilisation in the rhizosphere are of varying efficiency and now subject to constant changes under the varying soil conditions due to the climate change. In turn it is thought to have a potential onward effect of drying and rewetting (DRW) on the rhizosphere, which is one of the central components of this thesis. Thus, the focus of this PhD is to assess the P solubilisation processes in the rhizosphere with respect to the immediate (i-DRW) and delayed (d-DRW) DRW effect. Alongside this, the thesis is also focussed in assessing the behaviour of different types of phosphate fertiliser and their potential efficiency in the rhizosphere, particularly widely available new low-grade phosphate rock (PR) for potential crop benefit. The low-grade PR material is newly emerging into the market and can be used as a potentially more sustainable type of P fertiliser over time, as a substitute higher-grade PR. The overarching hypothesis tested was “P solubilisation in the rhizosphere can be affected by climate driven changes of soil associated with immediate and delayed effects of DRW events and root-zone acidification, under variable P amendments, with a particular consideration of the effects of low-grade phosphate rock”. To approach this, eight sub-hypotheses were tested, each being part of four different controlled experiments in the greenhouse using soils from four distinct agricultural regions of China. All laboratory experiments of P solubilisation (and potential leaching) in the rhizosphere were undertaken in three steps, which were dealt with chapters 3, 4 and 5. Overall, the key findings indicate that the P solubilisation in the rhizosphere (with corresponding plant productivity) is highly dependent on soil type, in particular the biological and hydrological characteristics. The results show substantially different levels of soil P solubilisation, related to exudative processes of the rhizosphere. Rhizosphere manipulation by inducing soil acidity via chemicals and legumes, had significant effects on soil P solubilsation and plant growth response (chapter 3). The P solubilisation processes also performed better on the soil with recent history of a series of DRW events, than soil with constant moisture treatment (chapter 5). This data supports the practical implications in the crop productivity over arid agricultural regions, especially with soils having low P availability used in these experiments. However, despite the assumptions of an increase in P solubilisation associated with i-DRW, the results of parallel study (chapter 4) did not prove to have a statistically significant difference across all treatments when soils were treated with frequent DRW events immediately. With regards DRW induced P leaching, the concentration of all P forms in leachate water varied in each cycle against soil type and the amount of P leaching following DRW was also proportionate with the rate of new P application. Concentration of P in the leachates of soils receiving different P sources varied from one i-DRW cycle to another, in respect of frequency and rate of DRW. Taken together, the evidence from the thesis led to the acceptance of the overarching hypothesis of this study

    Denitrification of recirculated aquaculture system effluents using fish sludge as primary substrate

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    Recirculating Aquaculture System (RAS) is a technology in which water is reused after different biological and mechanical treatment steps in fish farming. RAS produces a nitrate rich water effluent containing approximately 70-100 mg NO3/l, and a typical plant will have to offload between 50-100 kg NO3-N/d which needs to be denitrified before release to the marine environment to avoid eutrophication. Denitrification is a heterogenic process whereby reduced substrates (primarily organic, but also some reduced inorganic salts, like H2S and Fe2+, may serve as electron donors) are oxidized anoxically by reduction of NO3 and NO2 to N2. Organic substrates may come from external sources (easily biodegradable substrateslike acetate or methanol) or from internal, like the collected fish waste sludge containing feces and feed pellet residuals. Fish waste sludge is mainly particulate slowly biodegradable, and hydrolysis is necessary for use as C-source for denitrification. Fish sludge has been considered waste in the fish farming industries. Therefore, it is free, and applying it to run RAS is a resource recovery process. The kinetics (reaction rate) of denitrification using fish sludge is dependent on the chemical oxygen demand (COD) level; slowly biodegradable CODs (sbCODs) should be converted to readily biodegradable CODs (rbCODs) to provide the nitrate uptake process. Raw fish sludge was step-fed once or twice a day to a batch reactor containing substrate adapted activated sludge loaded with an initial nitrate concentration of 360 mg/l. Fish sludge characterization wet analysis was done on three different sludge batches and were compared. Two fermentation tests at 12 and 20 ℃ were done on fish sludge to investigate the effect of fermentation on biodegradability of fish sludge. Biomass specific nitrate uptake rates (NUR) were measured by an ion selective electrode, and substrate degradability and was estimated. NUR was also estimated using an equivalent initial COD concentration of acetate, and maximum NUR rates using fish sludge and fermented fish sludge were evaluated relative to the acetate driven denitrification rate. Fish sludge COD were split into three biodegradable fractions (easily biodegradable, slowly biodegradable, and slowly biodegradable particulate) based on NUR profiles, and their corresponding COD estimated using typical denitrifying yield factors. The observed acetate specific denitrification rate was 3.64 mg NO3-N/g VSS. h while the fish sludge rates were estimated to 1.2, 0.9 and 0.2 mg NO3-N/g VSS. h for the easily, slowly, and particulate degradable COD fractions respectively. Additionally, the effect of fermentation during anaerobic storages (over seven days) on sludge characteristics and volatile fatty acid production was investigated and the specific denitrification rate of settled and supernatant fermented sludge for easily degradable CODs was 3 and 2.2 mg NO3-N/g VSS. h. We conclude that direct use of fish sludge for denitrification of RAS effluents is possible, but design and operation would have to allow for the relative slow kinetics of the process, hypothetically limited by hydrolysis of slowly biodegradable dissolved and particulate COD fractions, which could be accelerated through fermentation

    The theoretical and experimental exploration of the use of predatory bacteria to control biofilms

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    Membrane based technologies are widely used for treating drinking water in sparsely populated areas, but their effectiveness is significantly diminished by the growth of biofilms and biofouling. Preventing or removing biofilms can increase the life span of membranes and, thus, improve their economic viability. Most cleaning methods involve physical disruption or antimicrobial chemicals and, therefore, require an interruption in the membrane operation. Bdellovibrio, a group of predatory bacteria, are a potential alternative to antimicrobials or physical disruption because of its ability to kill a large range of gram-negative bacterial prey and the inability of their prey to develop genetic resistance. However, the use of Bdellovibrio in industrial application has not been widespread in part due to the lack of understanding of the dynamics between Bdellovibrio and their prey. To compound this, many of the previous investigations into Bdellovibrio and biofilm ecology are limited by inaccurate, uninformative, and labour-intensive methods to quantify the population dynamics, which makes it difficult to build comprehensive models to exploit Bdellovibrio as a control to biofilms in systems like drinking water membranes. This thesis aims to develop a set of novel methods and technologies to accurately investigate Bdellovibrio and the effect they have on dynamics of their prey; Pseudomonas sp, a key gram negative biofilm forming species. This research develops the first protocol to use flow cytometry to accurately and rapidly quantify Bdellovibrio and Pseudomonas sp growth, which makes recording high resolution population dynamics feasible. The protocol was used for the development and experimental validation of mathematical models which aimed to predict Bdellovibrio dynamics in batch and chemostat systems. We show the first experimental observation of Bdellovibrio-prey oscillations, a key component of predation dynamics and a desired phenomenon for the use of Bdellovibrio as a self-sustaining biocontrol. To extend the models for application to systems where biofilms prevail, we demonstrated a new method of deploying flow cytometry and fluorescent assays to quantify and characterise the effect of nutrients on biofilm growth and predation. The findings suggest that extracellular polymeric substances (EPS) play a vital role in the attachment and persistence of biofilm when under Bdellovibrio predation. Thus, in biofilm research, the simple density dependent predator-prey interactions need to be augmented by representing the spatial heterogeneities in biofilm processes and properties such as its detachment, EPS and presence of metabolically damaged cells. For a more nuanced analysis of predator-prey interactions, at the resolution of individual organisms, this research develops a novel microfluidic device to observe Bdellovibrio predation on a 1-D biofilm. This thesis describes both the rationale and novel protocols for combining electron-beam lithography with, the more commonly used, photolithography to create an array of high-resolution channels to constrain biofilms and challenge them with predators. The research demonstrates the opportunities and the technical challenges in using microfluidics. Ultimately, if we are to develop mathematical models that can be parameterised and used effectively in designing strategies for controlling biofilms using predatory bacteria, then observations at the individual scale in microfluidic devices will be invaluable

    Resource Recovery from Water

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    Throughout history, the first and foremost role of urban water management has been the protection of human health and the local aquatic environment. To this end, the practice of (waste-)water treatment has maintained a central focus on the removal of pollutants through dissipative pathways. Approaches like – in the case of wastewater treatment – the activated sludge process, which makes ‘hazardous things’ disappear, have benefitted our society tremendously by safeguarding human and environmental health. While conventional (waste-)water treatment is regarded as one of the greatest engineering achievements of the 20th century, these dissipative approaches will not suffice in the 21st century as we enter the era of the circular economy. A key challenge for the future of urban water management is the need to re-envision the role of water infrastructure, still holding paramount the safeguard of human and environmental health while also becoming a more proactive force for sustainable development through the recovery of resources embedded in urban water. This book aims (i) to explain the basic principles governing resource recovery from water (how much is there, really); (ii) to provide a comprehensive overview and critical assessment of the established and emerging technologies for resource recovery from water; and (iii) to put resource recovery from water in a legal, economic (including the economy of scale of recovered products), social (consumer's point of view), and environmental sustainability framework. This book serves as a powerful teaching tool at the graduate entry master level with an aim to help develop the next generation of engineers and experts and is also highly relevant for seasoned water professionals and practicing engineers

    Biogas conversion into biopolymers: strategies to boost process performance

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    La humanidad se enfrenta en la actualidad a dos grandes desafíos que están estrechamente relacionados y que deben abordarse conjuntamente: la contaminación por plásticos y el cambio climático. Por un lado, reemplazar los plásticos convencionales y recalcitrantes por soluciones alternativas innovadoras y respetuosas con el medio ambiente es de suma importancia para paliar el devastador impacto medioambiental derivado del uso masivo del plástico, así como para mitigar las emisiones de gases de efecto invernadero (GEI) generadas en su producción. Por otro l ado, promover la gestión de residuos a través de biotecnologías consolidadas como la digestión anaerobia puede contribuir a la reducción de las emisiones de GEI al tiempo que se genera biogás como subproducto, una fuente de energía renovable por su alto contenido en metano y que, como otras renovables, contribuye a reducir la fuerte dependencia de la economía del planeta de los combustibles fósiles.Nowadays, mankind faces two major environmental challenges that are closely interconnected and should be tackled simultaneously: plastic pollution and climate change. On the one hand, innovation efforts devoted to the replacement of conventional recalcitrant plastics by environmentally friendly solutions are of utmost importance to mitigate the devastating environmental scenario caused by plastic pollution and to reduce greenhouse gas (GHG) emissions derived from their production. On the other hand, waste management via mature technologies such as anaerobic digestion can contribute to the reduction of GHG emissions while providing a renewable energy source (i.e. biogas) that will partially reduce the world dependence on fossil fuels.Departamento de Ingeniería Química y Tecnología del Medio AmbienteDoctorado en Ingeniería Química y Ambienta
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