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A la dècada dels vuitanta va tenir lloc l'enlairament del sistema de depuració espanyol i amb això la construcció de la majoria de les instal·lacions de sanejament del territori. Actualment, davant d'un canvi d'hàbits de consum de l'usuari que alteren les propietats de l'efluent i unes restriccions més grans d'abocament, Espanya ha de renovar la infraestructura i les tecnologies de depuració. En aquest marc, sorgeix el bioreactor de membranes (MBR), el qual es posiciona com una tecnologia en expansió que substitueix el reactor tradicional amb decantació posterior. Aquest treball descriu la posada en servei del bioreactor de membranes de l’EDARi d’AITASA per al tractament conjunt dels efluents de la industria petroquímica de Tarragona. La maniobra es realitza a l’Estació Depuradora d’Aigües Residuals Industrials (41°05'52"N 1°11'38"E) per l’empresa constructora i explotadora Aqualia. Els reactors tipus MBR permeten treballar amb concentracions de SS superiors, augmentar el rendiment d'eliminació al no requerir-se la decantació del flòcul i accelerar els processos biològics de nitrificació i desnitrificació. Tot aquest seguit de conceptes presentats s'aborden amb profunditat a la primera part del treball, on l'objectiu principal és comprendre el funcionament del reactor d'AITASA i determinar els paràmetres de control i de seguiment del procés que es volen estudiar. Ja amb les bases teòriques establertes, la segona part del treball explica en dues etapes tot el procés d’arrencada del reactor. En la primera fase, se segueix el creixement i l’estabilització de l’inòcul inicial, el qual és de procedència urbana. Progressivament, s’introdueix el cabal industrial al reactor i es monitora la proliferació dels bacteris autòtrofs nitrificants mitjançant el seguiment dels SS i l’eliminació de l’amoni. En una segona fase, el treball es centra en el control dels paràmetres de sortida, per tal de complir durant 14 dies amb l’establert al contracte i a l’Avaluació Ambiental Integrada. En el seu transcurs, sorgeixen dos episodis puntuals que alteren el comportament del reactor. El primer, un canvi en les propietats d’entrada i el segon, l’absència total d’aigua residual a tractar. Principalment, el seguiment de tots dos escenaris s’ha efectuat amb l’observació dels principals índex de contaminació: DQO, SS i NT. Finalment, també es presenta l’estudi del cost econòmic i l’impacte ambiental del projecte. Així mateix, es plantegen unes conclusions per tal de fer un balanç global de tot el treball on es conclou que s’han complert els objectius Objectius de Desenvolupament Sostenible::6 - Aigua Neta i Sanejament::6.3 - Per a 2030, millorar la qualitat de l’aigua mitjançant la reducció de la contaminació, l’eliminació dels abocaments i la reducció al mínim de la descàrrega de materials i productes químics perillosos, la reducció a la meitat del percentatge d’aigües residuals sense tractar, i un augment substancial a escala mundial del reciclat i de la reutilització en condicions de seguretat

[eng] Anaerobic membrane bioreactor (AnMBR), which is a combination of membrane separation and anaerobic digestion, is an emerging biotechnology for municipal sewage treatment. The application of AnMBRs in the mainline of wastewater treatment plants (WWTPs) can provide several advantages compared with conventional activated sludge processes, such as no aeration requirements, biogas production and reduction in the sludge management costs. However, despite these advantages, mainstream AnMBR application still presents challenges, whose resolution requires considering both technical and economic aspects. The goal of this thesis is to evaluate the technical and economic implications of implementing AnMBRs for municipal sewage treatment. Specifically, the thesis covered the techno-economic implications of two main topics: (i) forward osmosis (FO) pre- concentration before AnMBR, and (ii) plant-wide impact of AnMBR implementation in a WWTP. In the first part of this thesis, the techno-economic effects of combining FO and AnMBR technologies have been evaluated. First, a lab-scale mesophilic AnMBR operated at pre- concentration factors of 1, 2, 5 and 10 achieved chemical oxygen demand (COD) removal efficiencies above 90% for all the conditions. The differences between the soluble COD concentration of the permeate and digester suggested that membrane biofilm contributed to COD removal efficiency. Second, the techno-economic analysis of combining FO, reverse osmosis (RO) and AnMBR was conducted. The results showed that the wastewater treatment cost of the FO-RO+AnMBR system ranged between 0.80 and 1.40 € per m3 of wastewater treated. A sensitivity analysis illustrated that FO fluxes above 10 L m-2 h-1 (LMH) would improve the economic competitiveness of the FO-RO+AnMBR system. Finally, the impact of the draw solute and FO membrane material on the economic balance of this system was evaluated. The membrane material had a high impact on the economic balance since thin film composite (TFC) membranes substantially reduced the net cost when compared with cellulose triacetate (CTA) membranes. Conversely, the draw solute featured a moderate impact on the net cost. CH3COONa and CaCl2 were the most economically favourable draw solutes for CTA membrane, whereas MgCl2 was the most economically favourable draw solute for TFC membrane. In the second part of this thesis, the plant-wide impact of implementing AnMBRs in WWTPs has been evaluated. First, the effect of specific gas demand (SGD) and flux on membrane performance and process economics of granular AnMBRs was analysed. SGD and membrane flux impacted membrane fouling, but they did not impact organic matter rejection. The economic evaluation of granular AnMBRs showed that the most competitive strategy for fouling control relied on operating the membrane at normalised fluxes and SGDs of 7.8 LMH and 0.5 m3 m-2 h-1, respectively. Second, the economic feasibility of implementing mainstream AnMBR in a WWTP was evaluated for five different WWTP layouts. The results showed that the net treatment cost ranged between 0.33 and 0.43 € m-3 (100-1200 mg COD L-1) for WWTP layouts combining AnMBR, degassing membrane, primary settler and anaerobic digester. However, when partial nitritation-anammox and chemical phosphorus precipitation were included for nutrients removal, the net treatment cost increased from 0.33-0.43 to 0.51-0.56 € m-3. Finally, the techno-economic implications of co-digesting food waste with sewage sludge in the sidestream anaerobic digester of an AnMBR-WWTP were analysed. Co-digestion reduced the net cost of the sludge line when the nutrients backload was treated in the mainstream. However, when the nutrients backload was treated in the sidestream with partial nitritation-anammox and struvite crystallisation, the electricity revenue did not offset the additional costs of these two processes. The results also indicated that biosolids disposal cost represented the highest cost contributor in the sludge line of an AnMBR- WWTP., [spa] El biorreactor anaeróbico de membranas (AnMBR, por sus siglas en inglés) es una tecnología emergente para el tratamiento de aguas residuales municipales. El AnMBR no requiere de aeración, produce biogás y reduce la producción de fangos en comparación con procesos convencionales de lodos activos. Sin embargo, la aplicación del AnMBR en estaciones depuradoras de aguas residuales (EDAR) es muy limitado, ya que la tecnología debe superar barreras técnicas y económicas antes de una implementación generalizada. El objetivo de esta tesis es evaluar las implicaciones técnicas y económicas de implementar el AnMBR para el tratamiento de aguas residuales municipales. En concreto, la tesis aborda dos temáticas relacionadas con el AnMBR: (i) preconcentración del agua residual municipal mediante osmosis directa (FO, por sus siglas en inglés), e (ii) impacto global de implementar un AnMBR en una EDAR. En la primera parte de esta tesis se ha evaluado la combinación de las tecnologías de FO y AnMBR. El sistema experimental AnMBR alcanzó eliminaciones de demanda química de oxígeno por encima del 90% para el tratamiento de aguas residuales preconcentradas. Un análisis tecno-económico sobre la combinación de la FO, osmosis inversa y AnMBR mostró que el coste de tratamiento osciló entre 0,80 y 1,40 € por m3 de agua residual tratada. Los resultados también mostraron que el material de la membrana de FO tuvo un gran impacto sobre el balance económico del sistema. En la segunda parte de esta tesis se ha evaluado el impacto de implementar un AnMBR en una EDAR. La demanda específica de gas y el flujo de permeado tuvieron un impacto directo sobre el ensuciamiento de la membrana en un sistema AnMBR con fango granular. El análisis tecno-económico de la implementación de un AnMBR en una EDAR mostró que el coste de tratamiento se situaba entre 0,33 y 0,43 € m-3 para configuraciones que combinaron AnMBR, membrana de desgasificación, sedimentador primario y digestor anaeróbico. Finalmente, se determinó que la codigestión de fangos y residuos alimenticios tiene el potencial de reducir el coste de la línea de fangos de una EDAR que utiliza un AnMBR para tratar las aguas residuales.

El planeta Terra està intentant conviure amb les grans quantitats de contaminants atmosfèrics que s’emeten diàriament, degut principalment a l’activitat frenètica dels éssers humans. Per tal de minimitzar al màxim els danys que es poden provocar al medi ambient, i conseqüentment als éssers vius del planeta terra s’estan dedicant grans esforços a dissenyar i investigar mètodes alternatius a les tècniques convencionals amb el principal objectiu de minimitzar els costos d’operació, els residus generats i buscar la màxima optimització dels sistemes. Els bioreactors de membrana són una tècnica utilitzada pel tractament de corrents gasosos i corrents líquids contaminats de manera independent. Arribat aquest punt i veient que en els dos casos els resultats obtinguts són favorables, en aquest projecte es busca l’optimització del sistema per tal de desenvolupar processos biotecnològics per a la eliminació de contaminants gasosos per mitjà de configuracions avançades de bioreactors, acoblats a tècniques d’eliminació biològica de contaminants en aigua (compostos nitrogenats). En aquest treball s’ha utilitzat una membrana microporosa. Durant la realització del treball s’ha dissenyat i caracteritzat la planta per tal de conèixer paràmetres com ara la capacitat d’adsorció de la membrana, el coeficient de transferència d’oxigen i la capacitat de difusió del sistema. Tanmateix, s’ha fet un experiment preliminar per tal de veure el comportament general del sistema, calculant també l’eficiència d’eliminació d’acetat d’etil. Planet Earth is trying to coexist with the large amounts of air pollutants emitted on a daily basis, mainly due to the frantic activity of human beings. In order to minimize the damage that can be caused to the environment, and consequently to living beings on planet earth, great efforts are being made to design and research alternative methods to conventional techniques with the main goal of minimizing the costs of operation and waste generated and seek maximum system optimization. Membrane bioreactors are a technique used for the treatment of independently contaminated gas and liquid streams. At this point and seeing that in both cases favorable results have been obtained, this project seeks to optimize the system in order to develop biotechnological processes for the elimination of gaseous pollutants through advanced configurations of bioreactors, coupled with techniques of biological removal of pollutants in water (nitrogen compounds). A microporous membrane has been used in this project. During the development of the project, the plant has been designed and characterized in order to determine parameters such as the adsorption capacity of the membrane, the oxygen transfer coefficient, and the diffusion capacity of the system. However, a preliminary experiment has been conducted in order to see the overall behavior of the system, also calculating the removal efficiency of ethyl acetate.

Membrane bioreactor (MBR) models are useful tools for both design and management. The system complexity is high due to the involved number of processes which can be clustered in biological and physical ones. Literature studies are present and need to be harmonized in order to gain insights from the different studies and allow system optimization by applying a control. This position paper aims at defining the current state of the art of the main integrated MBR models reported in the literature. On the basis of a modelling review, a standardized terminology is proposed to facilitate the further development and comparison of integrated membrane fouling models for aerobic MBRs. ispartof: WATER SCIENCE AND TECHNOLOGY vol:81 issue:1 pages:1-9 ispartof: location:England status: published

A laboratory scale anaerobic membrane bioreactor was operated for 11 months treating synthetic wastewater that mimicked the concentrate from a forward osmosis process treating municipal wastewater with 80% water recovery. The effect of temperature variation on reactor performance was assessed. The reactor operated during 4 months at 34 °C and then temperature was decreased to 23 °C, 17 °C and 15 °C mimicking the typical temperature seasonal variations of the sewage. Average COD removal efficiencies were 95, 87, 76 and 67% at 34, 23, 17 and 15 °C respectively, obtaining lower biogas production and lower COD removal at lower temperatures. Dissolved methane in the permeate averaged 8.2 mg CH4/L and did not significantly change with temperature. After 2 months operating at 15 °C, temperature was progressively increased, resulting in an immediate increase of methane production and COD removal efficiencies. Microbial analysis showed important changes in the archaeal community when temperature was changed from 34 to 23 °C.

Sewage biogas valorization to different energy applications is hampered by the presence of volatile methyl siloxanes. Despite the high operating costs, adsorption onto activated carbon is the most implemented technology for siloxane removal from biogas. In order to purify biogas sustainably, the current work explores the diffusion of siloxanes (octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane) together with other biogas impurities (limonene, toluene and hexane) through polydimethylsiloxane membranes. Abiotic tests revealed transport efficiencies above 75% towards a clean air stream for most compounds, although the transport of the most hydrophobic pollutants was challenged when water was circulated through the shell side of the membrane. Moreover, the performance of a hollow-fiber membrane bioreactor, inoculated with anerobic active sludge, was evaluated towards biogas purification in anoxic conditions. Toluene and limonene were successfully degraded, hexane's removal efficiency was positively correlated with the residence time, and siloxanes removal was achieved up to 21%. CO2 was detected in the outlet gas as the mineralization product as well as some byproducts from the degradation of limonene and siloxanes. The presence of 1% of O2 in the gas, as a strategy to substitute NO3−, efficiently supported high removal for volatile organic compounds and moderate for siloxanes, which would ultimately reduce the operating costs of the technology This work was funded by the Spanish Ministry of Science, Innovation and Universities (CTQ2014-53718-R) co-funded by FEDER and University of Girona. Eric Santos-Clotas thanks Universitat de Girona for his predoctoral grant (IFUdG-2015/51). Alba Cabrera-Codony acknowledges support from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement Nº 712949 (TECNIOspring PLUS) and from the Agency for Business Competitiveness of the Government of Catalonia (TECSPR16-1-0045). LEQUIA has been recognized as consolidated research groups by the Catalan Government (2017-SGR-1552 and 2017SGR-548, respectively)

Alternative processes need to be designed for the treatment of industrial effluents containing pharmaceutical and personal care products to improve their quality, permit the reuse of water for industrial applications and meet the standards set by environmental regulations prior to discharge. This type of effluent is a major source of water pollution since conventional activated sludge-based treatments are not effective in removing micropollutants. Carbamazepine, caffeine and triclosan are important trace contaminants commonly found in wastewater treatment plants, and were selected as target compounds to be treated in a cyclic anoxic/aerobic membrane bioreactor. This study aims to evaluate the biomass’ characteristics and activity, and its influence over membrane fouling when treating the aforementioned compounds. Caffeine is known to be partially biodegraded whereas triclosan can inhibit microorganism’s activity. In order to evaluate this effect, complimentary batch experiments were set up to determine whether triclosan might inhibit nitrification. Low ammonia removal efficiencies were observed in both experimental systems, therefore suggesting that nitrification was being inhibited probably due to the presence of triclosan. The ultrafiltration membrane bioreactor process demonstrated to be an efficient and appropriate technology for chemical oxygen demand removal, achieving an average of 97%, for caffeine reaching up to 93.7 ± 9.7 removal efficiencies, and 89.7 ± 8.3% for triclosan. For carbamazepine the removal was lower (36.2 ± 6.8%) due to its recalcitrance. Furthermore, biomass filterability indicators displayed high sludge deterioration increasing substantially the fouling Hèctor Monclús acknowledges support from the Spanish Ministry of Economy, Industry and Competitiveness for co-funding the postdoctoral grant (IJCI-2015-23159) and People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement n° 600388 (TECNIOspring program), and the Agency for Business Competitiveness of Government of Catalonia (ACCIÓ) for funding this study (TECSPR 14-2-0021). This study was financed by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project CGL2013-48802-C3-2-R. LEQUIA has been recognized as consolidated research group by the Catalan Government (2017-SGR-1552)

Applying forward osmosis directly on raw municipal wastewater is of high interest for the simultaneous production of a high quality permeate for water reuse and pre-concentrating wastewater for anaerobic digestion. This pilot scale study investigates, for the first time, the feasibility of concentrating real raw municipal wastewater using a submerged plate and frame forward osmosis module (0.34 m2) to reach 70% water recovery. Membrane performance, fouling behavior, and effective concentration of wastewater compounds were examined. Two different draw solutions (NaCl and MgCl2), operating either with constant draw concentration or in batch with draw dilution over time, were evaluated. Impact of gas sparging on fouling and external concentration polarization was also assessed. Water fluxes up to 15 L m-2 h-1 were obtained with clean water and 35 g NaCl/L as feed and draw solution, respectively. When using real wastewater, submerged forward osmosis proved to be resilient to clogging, demonstrating its suitability for application on municipal or other complex wastewater, operating with 11.7 g NaCl/L constant draw solution, water and reverse salt fluxes up to 5.1 &plusmn, 1.0 L m-2 h-1 and 4.8 &plusmn, 2.6 g m-2 h-1 were observed, respectively. Positively, total and soluble chemical oxygen demand concentration factors of 2.47 &plusmn, 0.15 and 1.86 &plusmn, 0.08, respectively, were achieved, making wastewater more suitable for anaerobic treatment.

The presence of sewage-borne Organic Micro-Pollutants (OMP) in Wastewater Treatment Plants (WWTP) effluents represents an increasing concern when water is reclaimed for irrigation or even indirect potable reuse. During eighteen months, an innovative hybrid water reclamation scheme based on a Membrane Biological Reactor (MBR) enhanced with Powder Activated Carbon (PAC) was operated at pilot-scale (70 m3/d) in order to compare it with state-of-the art Wastewater Reclamation System (WWRS) also revamped with a final step of ozonation-UV. Removal of persistent OMP, water quality and treatment costs were evaluated and compared for the different treatment schemes. OMP removal efficiency results for the different schemes concluded that established technologies, such as physico-chemical and filtration systems as well as MBR, do not remove significantly (>15%) the most recalcitrant compounds. The upgrading of these two systems through the addition of ozonation-UV step and PAC dosing allowed improving average recalcitrant OMP removal to 85 ± 2 and 75 ± 5%, respectively. In term of costs, PAC-MBR represents an increase of 37% of costs regarding conventional systems but presents improvements of 50% reduction in space and water quality. On the other hand, ozonation requires up to a 15% increase of foot-print; nevertheless, represents lower costs and lower carbon footprint. Ozonation-UV seems to be the best option for upgrading existing facilities, while PAC-MBR should be considered when space represents a critical limitation and produced water is reused for high water quality purposes.

The removal of N-nitrosodimethylamine (NDMA) formation potential through a membrane bioreactor (MBR) coupled to a nanofiltration (NF) pilot plant that treats urban wastewater is investigated. The results are compared to the fate of the individual NDMA precursors detected: azithromycin, citalopram, erythromycin, clarithromycin, ranitidine, venlafaxine and its metabolite o-desmethylvenlafaxine. Specifically, the effect of dissolved oxygen in the aerobic chamber of the MBR pilot plant on the removal of NDMA formation potential (FP) and individual precursors is studied. During normal aerobic operation, implying a fully nitrifying system, the MBR was able to reduce NDMA precursors above 94%, however this removal percentage was reduced to values as low as 72% when changing the conditions to minimize nitrification. Removal decreased also for azithromycin (68–59%), citalopram (31–17%), venlafaxine (35–15%) and erythromycin (61–16%) on average during nitrifying versus non-nitrifying conditions. The removal of clarithromycin, o-desmethylvenlafaxine and ranitidine could not be correlated with the nitrification inhibition, as it varied greatly during the experiment time. The MBR pilot plant is coupled to a nanofiltration (NF) system and the results on the rejection of both, NDMA FP and individual precursors, through this system was above 90%. Finally, results obtained for the MBR pilot plant are compared to the percentage of removal by a conventional full scale biological wastewater treatment plant (WWTP) fed with the same influent. During aerobic operation, the removal of NDMA FP by the MBR pilot plant was similar to the full scale WWTP This study was funded by the Spanish MINECO funded project WaterFate (CTM2012-38314-C02-01). Dr. Maria Jos e Farr e acknowledges the European Commission for funding project 623711 under the FP7-PEOPLE-2013-IIF - Marie Curie Action: “International Incoming Fellowships”. Mr Julian Mamo acknowledges the funding received from the People Program (Marie Curie Actions) of the European Union’s Seventh Framework Programme FP7/ 2007e2013, under REA agreement 289193 (SANITAS project)

Membrane aeration represents between 35 and 50% of the operational cost of membrane bioreactors (MBR). New automatic control systems and/or module configurations have been developed for aeration optimization. In this paper, we briefly describe an innovative MBR air scour control system based on permeability evolution and present the results of a full-scale validation that lasted over a 1-year period. An average reduction in the air scour flow rate of 13% was achieved, limiting the maximum reduction to 20%. This averaged reduction corresponded to a decrease in energy consumption for membrane aeration of 14% (0.025kWhm-3) with maximum saving rates of 22% (0.04kWhm-3). Permeability and fouling rate evolution were not affected by the air scour control system, as very similar behavior was observed for these variables for both filtration lines throughout the entire experimental evaluation period of 1 year This project was financed by the Spanish Ministry of Economy and Competitiveness (CDTI- IDI20110304, CTM2012-38314-C02-01 and PCIN-2013-074). The work leading to this invention has also received funding from the People Programme (Marie Curie Actions) of the Seventh Framework Programme of the European Union (FP7/2007e2013, under REA agreements 289193 (SANITAS), from ACCI O (REA agreement 600388, TECNIOSPRING) and by the Catalan Agency for the Technical Valorisation (VALOR 2010-00170). The authors would like to thank the staff of La Bisbal d'Empord à WWTP (DAM Aguas), Ivan Brun and Sergi Casas (LEQUIA-UdG) for their support during the project. LEQUIA has been recognized as consolidated research group by the Catalan Government with code 2014-SGR-1168

Membrane bioreactors (MBRs) are a combination of activated sludge bioreactors and membrane filtration, enabling high quality effluent with a small footprint. However, they can be beset by fouling, which causes an increase in transmembrane pressure (TMP). Modelling and simulation of changes in TMP could be useful to describe fouling through the identification of the most relevant operating conditions. Using experimental data from a MBR pilot plant operated for 462days, two different models were developed: a deterministic model using activated sludge model n°2d (ASM2d) for the biological component and a resistance in-series model for the filtration component as well as a data-driven model based on multivariable regressions. Once validated, these models were used to describe membrane fouling (as changes in TMP over time) under different operating conditions. The deterministic model performed better at higher temperatures (>20°C), constant operating conditions (DO set-point, membrane air-flow, pH and ORP), and high mixed liquor suspended solids (>6.9gL-1) and flux changes. At low pH (

Water is a precious and necessary good for humans. We make great use of it be it for industry or urban use. In consequence its quality is altered and generates what we denominate waste waters. This water has to be treated to prevent negative impact on the environment. To avoid this there are waste water treatments. Conventional treatments in waste water treatment plants are composed of physic-chemical and biological treatments. But those water treatment plants present limitations that difficult improvement of the process. This limitations can be balanced out by integrating other advanced technologies of waste water treatment that will improve the treatment and generate better quality water diminishing the impact on the environment. One of those systems is called membrane bioreactor (MBR). This process generates much better water quality but has two big inconvenient: the operational cost and the membrane fouling. The membrane fouling is due to particle accumulation on the surface, negatively affecting water filtration. Fouling is detected by the increase in trans-membrane (TMP) pressure. In consequence there is an increment on the energetic cost and when accumulated it can damage the membrane. There exist different measures to help reduce fouling. Systems like the application of airing to create turbulence and detach fouling. Also periodical back wash process to release obstructed pores or chemical washes to recover filter capacity even though it reduces the membrane useful life. All these measures imply direct actions on the membranes. What we study is the option to apply an external peptic treatment that coats the membrane surface, able to prevent bio-fouling from membranes. With this treatment we could reduce back wash frequency, airing flow or even chemical washes. Therefore we can reduce operational costs from this technology increasing its profitability. Comparison between treated membranes and non-treated ones indicates that we can increase its permeability in low fluxes due to coating

For centuries, mankind has faced water-related issues for it is a limited good of vital importance for human development. Climate change, pollution and world water scarcity now have given more awareness to these problems. However, it is in human societies nature to consume water and return it to the environment in a form that is no longer profitable for human use. Ages of developing techniques and systems for water distribution has led to nowadays being able to obtain water from our own wastewater. Osmotic membrane bioreactor (OMBR) processes are a very important step in water tertiary treatment and furthermore, forward osmosis OMBR (FO-OMBR), which is at the vanguard of research and innovation. FO-OMBR uses the water gradient that the difference of osmotic pressure creates to separate physiochemically water from wastewater. In this project, first steps at laboratory-scale experiments are carried out to characterize osmotic membranes for further use at pilot-scale. Cellulose triacetate (CTA) has been widely used, and new materials such as thin-film composite (TFC) polyamide membranes have been produced. Therefore, new work is needed to compare their behavior at different concentration of the osmotic agent while also comparing performances at water recovery, lifespan of membrane and costs. In this work, sodium chloride is used as the osmotic agent. Also, the system configuration is considered as a limiting variable at operating, so different experiments were carried in both suction and pulsion modes. Impact of the pump is contemplated too so different pump speed experiments were held. In this study, it was also considered challenges such as salt loss from the draw solution (DS), so RSD value is reckoned. However, membrane fouling was not contemplated in this study; further work needs to be done. Once the results were obtained, it was regarded that when operated with TFC membrane better performance of the OMBR is done, as RSD values were lower and permeate volumes higher. Even though no essential differences where seen between suction and pulsion configurations, it was pulsion that showed better performance values

A novel method for catalytic reduction of chromium(VI) to chromium(III) in model and real water is proposed in this work. Hydrogen was used as a reducer. Three different catalytic membrane reactors were prepared and employed in the studied reaction. The catalytic membrane reactors were prepared using commercial corundum hollow fiber membranes. The active phases, palladium, cerium oxide, iron oxide or combinations of them, were incorporated by incipient wetness impregnation of the corresponding water-soluble salts followed by calcination and reduction. The catalytic tests were performed in semi-batch mode at ambient conditions. A mass flow controller was used to supply hydrogen to one end of the membrane whilst the other end was kept closed. The reactors were submerged into a vessel containing the chromate solution. The concentration of the chromate was continuously monitored following a standard analytical method. The initial chromate concentration was varied between 0.5 and 18 mg L-1. In order to completely reduce the Cr(VI) to Cr(III), it was necessary to decrease the pH of the solution to 3. In the end of the tests the final solutions were neutralized to pH 8 and filtered. The content of chromium in the final solutions and in the precipitates was determined by inductively coupled plasma (ICP) technique. It was demonstrated that for the studied reaction the presence of palladium is essential. In all experiments, with synthetic and real water adjusted to pH 3, the catalytic membrane reactors containing palladium (0.3-0.9 w/w%) effectively reduced the chromium to levels below 0.03 mg L-1 without losing activity in repetitive runs. The results from ICP analyses demonstrated that the chromium can be completely eliminated from the water after neutralization and filtration.

Membrane fouling is the most serious problem affecting membrane bioreactors (MBR). It decreases membrane permeability and consequently increases energy consumption. Various methods and techniques to measure fouling rates (FR) can be found in the literature, but few provide online data, and most are expensive or too invasive. The aim of this short communication is to present a new online method for monitoring and estimating the fouling in an MBR, based on the use of the derivative of the transmembrane pressure (TMP) per cycle, for which hourly and daily mean values can be obtained. This online method (FR per cycle) was experimentally evaluated at a lab-scale MBR plant, where fouling conditions were induced by the addition of a protein (albumin) and a polysaccharide (glucose). Finally, we compared the new method to standard methods, such as the flux-step method. Similar results for fouling rates were found, but the new method showed increased sensitivity. At the same time, the method seems to be useful in characterizing the nature of fouling This research was funded by the Spanish Ministry of Education and Science (CTM2009-1-14742-C02-01) and (CONSOLIDER-CSD2007-00055)

The impact of removable and irremovable fouling on the retention of viral and bacterial indicators by the submerged microfiltration membrane in an MBR pilot plant was evaluated. Escherichia coli, sulphite-reducing Clostridium spores, somatic coliphages and F-specific RNA bacteriophages were used as indicators. The membrane demonstrated almost complete removal of E. coli and sulphite-reducing Clostridium spores. However, there was no correlation with membrane fouling. The phage removal varied in accordance with the irremovable fouling, rising from 2.6 to 5.6 log10 units as the irremovable fouling increased (measured by the change in the transmembrane pressure). In contrast, removable fouling did not have any effect on the retention of viruses by the membrane. These results indicate that irremovable membrane fouling may affect the removal efficiency of MBRs and, therefore, their capacity to ensure the required microbiological standards for the permeate achieved This research was partially funded by the Spanish Ministry of Education and Science and Innovation (CTM2009-14742-C02-01) and (CONSOLIDER-CSD2007-00055)

In this paper we report the results obtained for inter-matrix synthesis (IMS) and characterization of monometallic and bimetallic polymer-stabilized metal nanoparticles (PSMNPs). The IMS procedure is based on the use of appropriately functionalized polymeric membranes as nanoreactors, which allows both synthesis and characterization of the composition and morphology of PSMNPs inside the membranes. The membranes were prepared by using noncrosslinked sulfonated poly(etherether ketone) (SPEEK) of desired degree of sulfonation, which provided insolubility of the polymer in water and solubility in some organic solvents (e.g. dimethylformamide). The IMS of PSMNPs involved loading of the membrane with metal ions or complexes followed by metal reduction inside the membrane resulting in the formation of either monometallic (Cu or Pt) or bimetallic (Pt/Cu) PSMNPs with core–shell structure. The electrocatalytic activity of the PSMNPs was estimated by measuring the electrochemical response of amperometric sensors prepared by using SPEEK-Pt-PSMNP and SPEEK-Pt/Cu-PSMNP nanocomposite membranes as sensing elements to detect H2O2. At the same values of Pt loading the response of Pt/Cu-PSMNP-based sensors appeared to be far higher than that of sensors modified with Pt-PSMNP membranes. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Màster d'Enginyeria Ambiental, Facultat de Química, Universitat de Barcelona, Curs: 2014-2015, Tutor: Joan Dosta, The growing concern in the development of new intensive technologies, is due to increasingly stringent regulations regarding waste disposal and to reduce energy needs. During vintage, the high organic load of wastewater from the production of wine, favors the application of mesophilic anaerobic processes to convert organic matter into biogas. However, when loads are low during the winter season, anaerobic digestion has been carried out at room temperature. The main objective of this project is to run an anaerobic membrane bioreactor (AnMBR) fed with synthetic wastewater wine at low temperatures (15ºC and 25ºC) and assess the activity of methanogenic biomass. During the experiment conducted, the AnMBR shows a good performance for the treatment of these waters, getting a good elimination of organic matter with a low requirement of nutrients. COD removal efficiency was not sufficient to meet the current regulations established. The operation at 25ºC had a better removal of COD than at 15 ºC, 80% and 71%, respectively. A higher acid value was detected when operated at 15ºC. It was obtained of the VFA accumulation on average 132±135 mg VFA/L and 183±135 mg VFA/L at 25ºC and 15ºC, respectively. The flux decline was 2.14 and 3.63 LMH d-1 at 25°C and 15°C, respectively, this coincides with the increased removal of organic matter at 25°C. The biogas production at 25ºC was 0.007±0.002 m3 biogas/m3reactord and at 15ºC was not possible to determinate experimentally. At 25ºC were favored the methanosaetas spp and methanosarcinas. Instead, only the methanosarcinas were developed at 15ºC.

The combination of MBR membrane technology with reverse osmosis (RO) for wastewater treatment has been proven to provide a very high quality effluent. The MBR efficiently removes nutrients (C, N & P) from the influent wastewater together with suspended solids and colloids making it suitable to feed it to a RO membrane which removes most of the remainder of the dissolved compounds, to produce very high quality effluent which is of drinking water quality. The main advantages of the wastewater treatment systems based on MBR technology are the quality of output water and the need of little installation space, in comparison with conventional activated sludge (CAS) systems. However, fouling particularly of the RO membrane, remains a problem when using the RO membrane as a final stage in a wastewater reclamation plant. Membranes require frequent chemical cleaning processes to control the build-up of organic, inorganic and biological fouling on the membrane surface. As the membrane gets fouled, increasing amounts of energy are required to produce the same amount of product water. Therefore it is essential to understand what is causing the fouling and what control measures must be applied to achieve long-term sustainable operation. The objective of this project is to understand how the composition of the RO influent water (MBR effluent) in terms of inorganic contaminants, temperature, pH and the system recovery affects membrane fouling. To achieve this objective, the feedwater of an MBR-RO pilot plant located at Quart was studied to obtain a characterisation of RO feedwater quality. The results of a membrane autopsy were used to see what types of membrane fouling are observed during operation. An RO membrane simulation model was then used to understand through multiple simulations how the feed water quality, temperature, pH and system recovery affect membrane fouling, the product water quality and the energy consumption. The results are then used to propose strategies to control membrane fouling and optimize process operation in terms of energy use and permeate quality. The results from the autopsy and those from the modelling studies confirm that the main component of inorganic fouling is Calcium Carbonate (CaCO3) particularly on the concentrate side of the membrane (the end of the membrane). On the feed side of the membrane, organic fouling was predominant. The modelling studies showed that the addition of acid to control the pH could control the CaCO3 precipitation. Furthermore, we have shown that the optimal process recovery to run the RO membrane at the lowest energy consumption for different feedwater temperatures between 24 and 27ºC is 70-75%. The final part of the project utilized online process data to monitor membrane fouling during pilot plant operation and normalize process data in terms of permeate flux and salt rejection

Despite the high number of advantages of membrane bioreactors (MBR), operational costs still remain as one of the main obstacles of this technology. In that sense, a full-scale MBR was studied in order to explore and identify viable optimization strategies for improving effluent quality and reducing operational costs through a model-based approach. Opportunities for optimization strategies, identified through the initial experimental phase, were focused on improving the nitrogen removal efficiencies and reducing the aeration energy costs through the aerobic DO set point and recirculation modifications. A mechanistic model was developed to reproduce the operation of the full-scale MBR and predict the effects of the optimization actions. Moreover, a qualitative risk model was also applied to ensure that the DO set point reduction did not negatively affect the microbiology of the activated sludge. The best viable control scenario was identified and then tested in the full-scale MBR. The results achieved maximum improvements on the nitrogen removal efficiencies of 27% and reduction on the aeration energy (7%) without affecting the sludge properties or the filtration performance. The model approached proved in this study and the optimization strategies identified can be generalized for municipal MBRs This research was funded by the Catalan Water Agency (ACA), the Ministry of Science and Innovation (CTM2012-38314-C02-01 and PCIN-2013-074) and SANITAS Project (289193).

Màster d'Enginyeria Ambiental, Facultat de Química, Universitat de Barcelona, Curs: 2013-2014, Tutors: Núria Basset Olivé i Joan Dosta Parras, The interest in anaerobic membrane bioreactors (An-MBR) has increased in the last years due to the several advantages of combining the anaerobic digestion with filtering membrane systems. Moreover, the necessity to reduce energy consumption and space by means of new technologies development in water treatment is of big concern nowadays. The main aim of the present project is to operate an An-MBR with real winery wastewater, with special emphasis on how its COD fluctuations disturb biogas production. The experimental development of the current study was carried out with real winery wastewater generated during the vintage period, observing COD concentrations between 0.5 and 7.6 g COD L-1, and OLRs from 0.4 up to 3.7 kg COD m-3 d-1. Effluent COD concentrations were detected to be low, achieving an average organic matter removal efficiency of 97 % during the 132 days of study. Biogas production increased progressively according to the organic load applied in each period. Its production varied from 0.04 to 0.3 m3 CH4 m-3digester d-1, for COD concentrations from 1 to 5.2 g L-1, respectively. Energy demands were estimated to be 7.5 kWh m-3, and biogas production was able to cover the energy costs when inlet COD was 3,200 mg L-1. The co-digestion of winery wastewater with reject water from a municipal WWTP was developed, aiming to provide the former with nutrients avoiding external chemicals. An average COD removal of 89 % was achieved treating an OLR of 1.8 kg COD m-3 d-1. However, economic data showed that its viability would be fulfilled at distances shorter than 10 km.

Treballs Finals de Grau d'Enginyeria Química, Facultat de Química, Universitat de Barcelona, Any: 2013, Tutor: Dr. Joan Dosta Parras, Anaerobic membrane bioreactor (AnMBR) technology has arised as an alternative option for wastewater treatment, providing many advantages such as high organic matter removal efficiency (~98%), compact process, energy recovery (biogas) and sludge reduction. It combines the advantages of the use of membranes, already proved in aerobic membrane bioreactors, and the advantages of the anaerobic digestion, widely used since 1900s. The bioreactors can be single or a combination of various reactors, with the membrane either external or immersed. The membrane modules can be multitube (mostly used in external membrane bioreactors), flat sheet or hollow fiber modules (both used mainly in immersed membrane bioreactors). The membrane materials can be polymeric (the mostly used), metallic or ceramic. Also, the biomass can be suspended, granular (widely used in upflow anaerobic sludge blanket reactors) or attached (the most used in anaerobic fluidized-bed reactors). The energy balances confirm that the AnMBR process can be a self-sufficient process, even an energy-producer process, diminishing GHG emissions and reduced carbon footprint. The main limitations of the AnMBRs for urban wastewater treatment are membrane fouling and high quantity of dissolved methane in effluent. Some authors have successfully partially controlled them, but more research is still necessary in this field. In addition, some authors have used AnMBRs for industrial wastewater treatment, with successful results: SRTs up to 230 days with HRTs between 16 h - 5 days, and the COD removal efficiency between 94-99%. However, for urban and high-solid-content wastewaters the applicability is still doubtful: low COD removal efficiency, which does not fulfill with the legislative requirements. The firstly AnMBR commercially used for industrial wastewater treatment in the 1980s were known as Membrane Anaerobic Reactor System (MARS) and Anaerobic Digestion Ultrafiltration (ADUF). In the last decade, Kubota Corporation developed a submerged anaerobic membrane bioreactor process, named KSAMBR process, successfully applied in food and beverages industries, and ADI Systems Inc. developed ADI-AnMBR system, specific for food wastewaters.

L’objectiu d’aquest projecte és seleccionar un sistema de depuració i regeneració de les aigües residuals d’una empresa concreta per poder reutilitzar-les i destinar-les al reg de la seva zona enjardinada, que és de gran extensió, per aconseguir reduir el consum d’aigua potable i obtenir beneficis tant econòmics com medi ambientals. En primer lloc es realitza un estudi del contingut de les aigües residuals, de les seves característiques i del motiu pel qual és important tractar-les. A continuació es fa una revisió dels diferents tractaments i de les normatives vigents. S’escull un tractament terciari, necessari ja que aquestes aigües es destinen a l’ús del reg i és necessari complir la seva normativa. Les aigües residuals que es volen tractar en aquest estudi tenen una gran càrrega de matèria orgànica i nitrogen, fet que complica la seva depuració eliminant la possibilitat de fer-la mitjançant un procés de depuració convencional i obligant a realitzar un procés diferent, més innovador i eficient però més car. Finalment es descriu el tractament escollit, que consisteix en un sistema de depuració amb un reactor biològic per membranes MBR (Membrane BioReactor) que inclou un primer procés de depuració per oxidació biològica seguit d’una filtració per membranes, la qual dóna una qualitat suficient a l’aigua per poder destinar-la a l’ús desitjat. Aquest projecte inclou, també, una avaluació d’impacte ambiental de l’efecte que provoca col·locar aquesta instal·lació sobre el medi, en aquest cas, la parcel·la de l’empresa.

Aquest projecte pretén demostrar la viabilitat i conveniència d‟una estació depuradora de tractament biològic amb membranes per a processar aigües residuals d‟una població d‟aproximadament 9.000 habitants equivalents. Amb aquest objectiu es revisaran, en primer lloc i de forma general, els sistemes emprats tradicionalment per a depurar aquest tipus d‟aigües residuals. Posteriorment es plantejarà la utilització de membranes com a alternativa als sistemes convencionals. Un cop fet això, s‟estudiarà l‟enginyeria de l‟estació depuradora, el seu impacte ambiental, el seu manteniment, el pressupost resultant i la valoració energètica dels residus produïts. Aquesta estudi es farà amb la perspectiva que la planta pugui ser implementada en un futur proper. Una possible localització seria el Port de la Selva o també es podria plantejar l‟ampliació de cabal de qualsevol EDAR convencional de dimensions de reactor similars. Per què l‟estudi sigui vàlid per a diferents ubicacions, la composició de les aigües residuals a tractar s‟obtindrà a partir de bibliografia. Els equips assignats a la planta seran comercials i la planta complirà la normativa vigent.

Zeolite NaA membranes have attracted special attention in the last years in light of their high selectivities (>40000) and fluxes in the dehydration of alcohol/water mixtures. This Ph.D. thesis is aimed at developing new methods for zeolite NaA membrane synthesis together with the characterization of their mass transfer mechanisms for their further application in membrane reactors.The membranes have been prepared onto the outer and inner surface of ceramic tubular supports by in situ and seeded hydrothermal synthesis. To avoid the shortcoming of low accessibility to the lumen of the tubes in inner-side membrane synthesis, a new seeding technique is here presented that relies on a controled filtration of a zeolite particle suspension. The seeding weight gain strongly depends on the retentate flow rate, transmembrane pressure and pH. On the other hand, for the hydrothermal syntheses, four different techniques have been used: (1) synthesis in a batch system, (2) synthesis in a centrifugal force field, (3) semi-continuous synthesis and (4) continuous synthesis. The as-synthesized membranes have been characterized by gas permeance, PV of ethanol/water mixtures, XRD and SEM. The results reveal that techniques (3) and (4) that involve gel renewal improve the PV performance, with selectivities and fluxes up to 16000 and 1.2 kg m-2 h-1, respectively, for ethanol/water mixtures 92:8 wt.% at 323 K. Moreover, despite the presence of a certain amount of intercrystalline defects in the layers, their use is suitable for dehydrating long-chain alcohols and ethers, which opens up the possibility of being used in membrane reactors to carry out etherificarion reactions.The PV process in zeolite NaA membranes has been modeled using the generalized Maxwell-Stefan diffusional theory, including the explicit contribution of intercrystalline porosity and the binary adsorption isotherm of water and ethanol. The surface diffusivities of water obtained from the fittings to PV fluxes are ca. 3-5 orders of magnitud higher than those obtained from adsorption kinetics experiments. This apparent contradiction might be ascribed to the role of grain boundaries between adjacent zeolite grains as fast diffusion paths., Les membranes zeolítiques hidrofíliques, caracteritzades per les seves elevades relacions Al/Si, constitueixen una camp de recerca prometedor per a la deshidratació de mescles orgàniques mitjançant pervaporació (PV). Més específicament, les membranes de zeolita NaA han rebut especial atenció per les seves altes selectivitats (>40000) y fluxos en la deshidratació de mescles alcohol/aigua. En aquest context, l'objectiu principal d'aquesta tesi doctoral ha estat el desenvolupament de nous mètodes de preparació d'aquestes membranes, juntament amb la caracterització dels seus mecanismes de transport per a la seva posterior aplicació en reactors de membrana.En els capítols IV i V de la memòria es descriu la preparació de membranes de zeolita NaA sobre suports tubulars ceràmics, tant a la seva superficie externa com interna, mitjançant síntesi hidrotèrmica in situ y creixement secundari. En aquesta configuració, la sembra del suport és complexa a causa de la poca accessibilitat a la seva superficie interior. Per a paliar aquesta limitació, en esta tesi s'ha desenvolupat un mètode de sembra basat en la filtració controlada d'una suspensió de partícules de zeolita NaA. S'ha observat que el guany de de sembra [mg cm-2] depèn fortament del cabal de retingut, pressió transmembranal y pH. D'altra banda, la síntesi hidrotèrmica de les capes s'ha realizat mitjançant quatre tècniques diferents: (1) síntesi en un sistema batch, (2) síntesi sota l'acció d'un camp centrífug, (3) síntesi en un sistema semi-continu i (4) síntesi en un sistema continu. Les capas sintetizades s'han caracteritzat mitjançant permeació de gasos, PV de mescles etanol/aigua, DRX y SEM. Els resultats obtinguts indiquen que la renovació del gel a l'interior dels tubs millora la qualitat pervaporativa de les membranes, amb selectivitats y fluxos de fins a 16000 y 1.2 kg m-2 h-1, respectivament, per a mescles etanol/aigua 92:8 wt.% a 323 K. Les membranes també mostren bones prestacions en la deshidratació d'alcohols primaris C1-C5 i mescles ternàries 1-pentanol/DNPE/aigua. Els resultats també reflecteixen que, a pesar de la presència de defectes en les capes, el seu ús sembla adequat per a deshidratar alcohols y èters de cadena llarga, la qual cosa en possibilitaria l'ús en reactors de membrana per a dur a terme reaccions d'eterficació. Aquesta possibilitat s'il·lustra a partir de la simulació d'un reactor de membrana de zeolita NaA per a la reacció de l'1-pentanol a di-n-pentil éter (DNPE) en fase líquida catalitzada per resines àcides de bescanvi iònic.En el capítol VI es presenta un model matemàtic per a la predicció de distribucions de tamanys de porus en membranes de MF, UF i NF a partir de la teoria de moments a partir de tres experiments independients: (1) permeació de N2 en règim Knudsen, (2) permeació d'agua pura, i (3) difusió iònica no impedida. Posteriorment, aquest mètode s'ha extès a la caracterització de defectes meso- i macroporosos en capes zeolítiques a partir d'una col·lecció d'experiments de PV. S'observa que les membranes de zeolita NaA perden parcialment la seva capacitat deshidratadora per a porositats intercristal·lines >10-4.Finalment, en els capítols VII y VIII es descriu la modelització del procés de PV en membranes de zeolita NaA mitjançant la teoria generalitzada de Maxwell-Stefan. La modelització inclou explícitament la contribució de la porositat intercristal·lina i la informació de l'adsorció binària d'aigua i etanol. La modelització de l'equilibri d'adsorció binari s'ha realitzat a partir de la teoria IAST i la versió modificada PRAST. Els models resultants representen satisfactòriament les tendències experimentals. Les difusivitats superficials de l'aigua obtingudes a partir dels ajustos a fluxos de PV són 3-5 ordres de magnitud superiors als obtinguts a partir de cinètiques d'adsorció. Aquesta aparent contradicció s'argumenta a partir de la contribució dels límits de gra en les capes, el quals podrien actuar com a camins de difusió ràpida.

Two experimental studies evaluated the effect of aerobic and membrane aeration changes on sludge properties, biological nutrient removal and filtration processes in a pilot plant membrane bioreactor. The optimal operating conditions were found at an aerobic dissolved oxygen set-point (DO) of 0.5mgO2L-1 and a membrane specific aeration demand (SADm) of 1mh-1, where membrane aeration can be used for nitrification. Under these conditions, a total flow reduction of 42% was achieved (75% energy reduction) without compromising nutrient removal efficiencies, maintaining sludge characteristics and controlled filtration. Below these optimal operating conditions, the nutrient removal efficiency was reduced, increasing 20% for soluble microbial products, 14% for capillarity suction time and reducing a 15% for filterability. Below this DO set-point, fouling increased with a transmembrane pressure 75% higher. SADm below 1mh-1 doubled the values of transmembrane pressure, without recovery after achieving the initial conditions The research leading to these results has received funding from the Spanish Ministry of Economy and Competitiveness (CTM2012-38314-C02-01 and PCIN-2013-074) and from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013, under REA agreement 289193 (SANITAS) and under REA agreement 600388 (TECNIOSPRING)). This publication reflects only the authors' views, and the European Union is not liable for any use that may be made of the information contained therein. Montse Dalmau received a grant from the Spanish Ministry of Economy and Competitiveness (BES-2010-033288)

Removal of ammonia from wastewater generated in a waste treatment plant by a membrane contactor was studied at lab scale. The treated wastewater will be applied in the Hydrogen and Oxygen production by electrolysis via renewable energies. The aim of this study relies on fulfill the process requirements in the electrolysis, since the water used in the electrolysis process must be almost pure water due to efficiency process of Hydrogen and Oxygen production decreases with the ions in the dissolution. The residual ammonium concentration of the aqueous stream feeding the membrane distillation step ranging between 1 to 5 ppm is not removed and arrives to the electrolysis step generating an increase in the conductivity. So the use of a liquid-liquid membrane contactor is proposed to reduce ammonium (NH+4) concentration before membranes distillation step. The experimental set-up was performed by a contactor (Liqui-cel X30 HF (Celgard, USA)) which works in close and open loop mode configuration. In close circuit, it was used a tank of 10 liters to storage ammonium solution and in open circuit it was used 25 liters as initial ammonium volume. A pump (Cole Parmer instrument) was used to feed the contactor from the tank. An aqueous ammonium solution with a low concentration is in the inner side of the membrane contactor (Lumen) and sulphuric acid solution goes in the outside of the membrane contactor (Shell). The pH plays a very important role in the chemical equilibrium; for that reason is motorized during the experiments. On the other hand, it has been carried out the simulation of a mathematical model used by various authors to validate the experimental results by COMSOL Multiphysics program

There has been an increasing interest in wastewater treatment in last decades to reduce human footprint. Primarily, anaerobic technology focused on treatment and stabilization of sludge, but now the tendency is to give it a major role in low cost treatment of high/low strength wastewaters, since anaerobic digestion offers energy generation through gas production. Anaerobic membrane bioreactors (AnMBR) combine anaerobic digestion with membrane filtration. They are becoming a feasible option for treating previous unsuitable low-strength wastewaters, decoupling hydraulic and solid retention times, and providing successful treatment with the benefits of biogas production. However, the digestion process is optimal at mesophilic or termophilic (35-37 ºC), requiring heating of reactors. The more inexpensive option to treat the wastewater at its ambient temperature is feasible using AnMBR since this type of reactor can offer long sludge retention times. On the other hand, the digestion equilibrium turns out more sensible and delicate, and performing a proper and robust start-up of AnMBR in ambient temperatures is still challenging. The aim of the thesis was the successful startup and stabilization of AnMBR systems at ambient temperature (25 ºC) and low organic loading rate (OLR). Reactor operation was monitored, and the most relevant process parameters were considered for the aim. Two pilot-scale AnMBR’s (120L) were used with an external membrane configuration. The experiment was carried out in 100 days. Substrate feeding consisted of synthetic dairy wastewater with added nutrients solution. The inoculum was provided from a full-scale anaerobic plant at a digester of BV dairy (UK) treating dairy wastewater at 30ºC. Main operation parameters were monitored every day, along with gas production and methane yield. Laboratory tests were performed twice a week with samples of the reactors and effluent. A number of parameters were analyzed, the most important of which were total solids content (TSS), alkalinity, fatty acids, biogas content and chemical oxygen demand (COD). The startup of the two AnMBR’s differed greatly. In System 1, stable conditions were acquired in one month of operation. System 2 failed after 20 days of function, and did not achieve successful startup. It was not possible to fully recover it during the days of study due to dramatically slow growth of microorganisms and low stability of the process. Thus, satisfactory system performance could be achieved but the ambient anaerobic process was vulnerable to inhibitory conditions. Both systems showed that the delicate process operation required fast corrective measures to prevent digestion failure. Causes of instability and failure were: washout of biomass, high content of VFA, low buffering capacity and poor performance of technical equipment and low pH. However, the digestion could stand a lower pH range than found in literature. In conclusion, the best parameters to control the startup were pH, alkalinity, methane content, biomass content and organic removal. In this sense, low buffering capacity of a reactor makes it vulnerable to inhibition by sudden pH changes, easily solved by systematic addition of a buffering compound. Finally, the use of simple and fast alkalimetric methodologies can give satisfactory process overview compared to complex and more precise techniques for alkalinity measurement. Outgoing

Immobilization of metal nanoparticles in hollow fiber membranes via alternating adsorption of polyelectrolytes and negatively charged Au nanoparticles yields catalytic reactors with high surface areas. SEM images show that this technique deposits a high density of unaggregated metal nanoparticles both on the surfaces and in the pores of the hollow fibers. Catalytic reduction of 4-nitrophenol with NaBH4, which can be easily monitored by UV–vis spectrophotometry, demonstrates that the nanoparticles in the hollow fiber membrane are highly catalytically active. In a single pass through the membrane, >99% of the 4-nitrophenol is reduced to 4-aminophenol, but this conversion decreases over time. The conversion decline may stem from catalyst fouling caused by by-products of 4-aminophenol oxidation.