Enhanced styrene removal in a two-phase partitioning bioreactor operated as a biotrickling filter: Towards full-scale applications

Styrene vapor abatement was investigated in a two-phase partitioning bioreactor operated as a biotrickling filter (TPPB-BTF). The removal performance of the TPPB-BTF was simultaneously compared with a conventional BTF, which served as a control. Industrial-grade silicone oil was used as the non-aqueous phase in the TPPB-BTF due to its high affinity for styrene. Both bioreactors were operated at styrene inlet concentrations ranging from 55 to 323 mg C m−3 and empty bed residence times (EBRT) of 15-30 s, corresponding to pollutant loading rates of 13-77 g C m−3 h−1. Both bioreactors exhibited styrene removal efficiencies (REs) higher than 90% at an EBRT of 30 s. Nevertheless, the TPPB-BTF showed a superior removal performance than that recorded in the control BTF at EBRTs shorter than 30 s. REs of 89%, 84% and 57% were recorded in the TPPB-BTF at EBRT of 15 s and loading rates of 13, 22 and 77 g C m−3 h−1, respectively, while the control BTF supported removal efficiencies of 64%, 42% and 18-42% under the same experimental conditions. The resilience and robustness of the TPPB-BTF over styrene shock loadings and transient inlet concentration was also confirmed, the TPPB-BTF being able to recover a stable RE of 89% one day after such operation disturbances. The potential of the TPPB-BTF towards full scale applications was also critically discussed based on the experimental determination of silicone oil loses through aqueous phase renewal, which accounted for 0.4% of the initial volume of oil added to the TPPB-BTF after 87 days of operation

Knowledge extraction from raw data in water networks: application to the Barcelona supramunicipal water transport network

Critical Infrastructure Systems (CIS) such as the case of potable water transport network are complex large-scale systems, geographically distributed and decentralized with a hierarchical structure, requiring highly sophisticated supervisory and real-time control (RTC) schemes to ensure high performance achievement and maintenance when conditions are non-favorable due to e.g. sensor malfunctions (drifts, offsets, problems of batteries, communications problems,...). Once the data are reliable, a process to transform these validated data into useful information and knowledge is key for the operating plan in real time (RTC). And moreover, but no less important, it allows extracting useful knowledge about the assets and instrumentation (sectors of pipes and reservoirs, flowmeters, level sensors, ...) of the network for short, medium and large term management plans. In this work, an overall analysis of the results of the application of a methodology for sensor data validation/reconstruction to the ATLL water network in the city of Barcelona and the surrounding metropolitan area since 2008 until 2013 is described. This methodology is very important for assessing the economic and hydraulic efficiency of the network.Peer ReviewedPostprint (published version

Modelling mass transfer properties in a biotrickling filter for the removal of isopropanol

A study was carried out to model mass transfer properties in biotrickling filters, treating isopropanol as the target pollutant. This study was extended to the mass transfer of oxygen related to the fact that the treatment of hydrophilic compounds by biotrickling filtration is often limited by oxygen. A simple method for each compound was developed based on their physical properties. The influence of temperature on the Henry"s law constant of isopropanol was determined. An increase of 1.8 per 10ºC for the dimensionless Henry"s law constant was obtained. The determination of the overall mass transfer coefficients of isopropanol (KGa) was carried out, obtaining values between 500 and 1800 h-1 for gas velocities of 100 and 300 m h-1. No significant influences were observed for either the liquid velocity or packing material. Also, the determination of overall mass transfer coefficients of oxygen (KLa) were carried out, obtaining values between 20 and 200 h-1 depending on the packing material for liquid velocities between 2 and 33 m h-1. Structured packing materials exhibited greater mass transfer coefficients, while for random packing materials, the mass transfer coefficients clearly benefited from the high specific surface area. Mathematical correlations found in the literature were compared with the empirical data, showing that neither was capable of reproducing the mass transfer coefficients obtained empirically. Thus, empirical relationships between the mass transfer coefficients and the gas and liquid velocities are proposed to characterise the syste

Study of Mass Oxygen Transfer in a Biotrickling Filter for Air Pollution Control

Biotrickling filtration is a potential and cost effective alternative for the treatment of volatile organic compound (VOC) emissions in air, so it is necessary to deepen into the key aspects of design and operation for the optimization of this technology. One of these factors is the oxygen mass transfer of the process. This study would facilitate the selection of the packing material and the mathematical modelling and simulation of bioreactors. Four plastic packing materials with a different specific surface area have been evaluated in terms of oxygen mass transfer. For the tested range of superficial liquid velocities, data show a relationship between the kLa and the superficial liquid velocity in all packing materials used, except for the biggest plastic rings. No significant differences in mass transfer coefficients at low liquid velocities were observed, however dependency between oxygen transfer and specific surface area increased considerably for high liquid velocities. No significant influences of the superficial air velocity were observed

Aspen Plus process-simulation model: Producing biogas from VOC emissions in an anaerobic bioscrubber

A process-simulation model for a novel process consisted of an anaerobic bioscrubber was developed in Aspen Plus®. A novel approach was performed to implement the anaerobic reactor in the simulation, enabling it to be connected to the scrubber. The model was calibrated and validated using data from an industrial prototype that converted air emissions polluted with volatile organic compounds with an average daily concentration of 1129 mgC Nm−3 into bioenergy for more than one year. The scrubber, which showed a removal efficiency within 83-93%, was successfully predicted with an average absolute relative error of 5.2 ± 0.08% using an average height-to-theoretical-plate value of 1.05 ± 0.08 m and 1.37 ± 0.11 m for each of the two commercial packing materials used, respectively. The anaerobic reactor, which treated up to 24 kg of chemical oxygen demand m−3 d−1 with efficiencies of about 93%, was accurately simulated, both in effluent-stream characteristics and in the biogas stream. For example, the average absolute error between the experimental biogas production and the model values was 19.6 ± 18.9%. The model proved its capability as a predictive tool and an aid in design, resulting in savings of time and money for practitioners. In addition, the approach proposed can be expanded to other bioprocesses that include unit operations

Optimization of instruction fetch for decision support workloads

Instruction fetch bandwidth is feared to be a major limiting factor to the performance of future wide-issue aggressive superscalars. In this paper, we focus on database applications running decision support workloads. We characterize the locality patterns of ia database kernel and find frequently executed paths. Using this information, we propose an algorithm to lay out the basic blocks for improved I-fetch. Our results show a miss reduction of 60-98% for realistic I-cache sizes and a doubling of the number of instructions executed between taken branches. As a consequence, we increase the fetch bandwith provided by an aggressive sequential fetch unit from 5.8 for the original code to 10.6 using our proposed layout. Our software scheme combines well with hardware schemes like a trace cache providing up to 12.1 instruction per cycle, suggesting that commercial workloads may be amenable to the aggressive I-fetch of future superscalars.Peer ReviewedPostprint (published version

A comparison of medically serious suicide attempters admitted to intensive care units versus other medically serious suicide attempters

Medically serious suicide attempts (MSSA) represent a subgroup of clinically heterogeneous suicidal behaviours very close to deaths by suicide. A simple definition of an MSSA is a suicide attempt with life-threatening consequences, regardless of the severity of the attempter's mental disorder. Few studies have specifically analysed the heterogeneity of MSSA. Therefore, the aim of this study is to describe the profile of individuals who made a highly severe MSSA and to compare those admitted to Intensive Care Units (ICU) - including Burn Units- with other MSSA admitted to other medical and surgical units. The study sample consisted of 168 patients consecutively admitted to non-psychiatric wards from two public hospitals in Barcelona after an MSSA during a 3-year period. In order to select more severe MSSA, the minimum hospital stay was expanded from Beautrais' definition of ≥ 24 h to ≥ 48 h. Mean hospital stay was 23.68 (SD = 41.14) days. Patients needing ICU treatment (n = 99) were compared to other MSSArs (n = 69) that were admitted to other medical and surgical units, not requiring intensive care treatment, with an initial bivariant analysis followed by a logistic regression analysis using conditional entrance. Medically serious suicide attempters (MSSArs) spent more time hospitalized, more frequently reported recent stressful life events, were more likely to have at least one prior suicide attempt (SA) and their current attempt was more frequently non-planned, compared to the profile of MSSArs reported in previous studies. The most frequent method was medication overdose (67.3%) and jumping from heights (23.2%). Among those who chose more than one method (37.6%), the most frequent combination was medication overdose and drug use. Affective disorders and personality disorders were the most frequent diagnoses. Higher educational level, history of previous mental disorders and prior lifetime suicide attempts were significantly more frequent among those admitted to ICU compared to other MSSArs. Patients needing admission to ICU less frequently used self-poisoning and cuts. MSSA needing ICU admission can be regarded clinically as similar to attempts resulting in suicide. More research on this type of highly severe suicide behaviour is needed due to its serious implications both from a clinical and public health perspective

Cerramientos multicapas ligeros en el concurso solar Decathlon 2007

El constante crecimiento de consumo energético en todos los sectores, siendo el caso particular el de las edificaciones que consumen una tercera parte del consumo total. Todo ello surge como consecuencia del crecimiento económico y del aumento de las exigencias de las condiciones de confort, además de utilizar energías fósiles. Si se estudia el consumo energético en las edificaciones, se puede ver que el mayor consumo se genera en climatización con un 46%, luego el agua caliente con 21%, electrodomésticos 16%, cocina 10% e iluminación 7%. Desde la década de los setenta, ha surgido una creciente demanda social por un crecimiento sostenible, originado por una parte por la crisis energética iniciada con el conflicto de Medio Oriente y por otra parte por un cada vez mayor y mejor análisis de la repercusión en el ambiente de nuestras actividades. Esto ha llevado a actuaciones de ámbito mundial como son: El Protocolo de Montreal, AGENDA 21, propone el desarrollo de las energías renovables, disminuir los impactos sobre la salud y el medio ambiente de la producción y consumo de energía y el fomento de una educación hacia el desarrollo sostenible. El Programa 21 de la ONU, plantea el control de aquellas substancias que producen el agotamiento de la capa de ozono. El Protocolo de Kyoto, cuyo objetivo es la disminución de las emisiones de Gases de Efecto Invernadero, en especial del CO2. Dando respuesta a estas actuaciones mundiales la Unión Europea ha desarrollado normativas, tendentes a la mejora de la eficiencia energética y a la seguridad y diversificación de los suministros. Así ha desarrollado: La Directiva 93/76 de 13.09.93 (SAVE), El Libro Verde, La Directiva 2002/91. En España las actuaciones se han presentado con: Código Técnico de la Edificación, Documento Básico “Ahorro de Energía” y Real Decreto 47/2007, por el que se aprueba el procedimiento básico para la certificación de eficiencia energética de edificios. Este certificado deberá incluir información objetiva sobre las características energéticas de los edificios de forma que se pueda valorar y comparar su eficiencia energética, con el fin de favorecer la promoción de edificios de alta eficiencia energética y las inversiones en ahorro de energía. Como respuesta a toda esta serie de normativas para la mejora del consumo energético se tiene, por un lado es el empleo de las energías renovables, como la solar fotovoltaica, solar térmica, eólica, hidráulica, biomasa, geotérmica,… y por otro mejorar el diseño y construcción de los edificios usando cerramientos eficientes, como los multicapa y aún mejor los multicapa ligeros, ya que generan mejores prestaciones en término de confort y ahorro energético