A comparative study of the characteristics and physical behaviour of different packing materials commonly used in biofiltration

In this study, the characteristics and physical behaviour of 8 different packing materials were compared. The materials were selected according to previous works in the field of biofiltration including organic and inorganic or synthetic materials. Results pre-selected those more acceptable support materials for the main function they have to perform in the biological system: high surface contact, rugosity to immobilize the biomass, low pressure drop, nutrients supply, water retentivity or a commitment among them. Otherwise, pressure drop have been described by means of the respective mathematic expressions in order to include phenomena in the classical biofiltration models.Peer ReviewedPostprint (author's final draft

Comparison of organic packing materials for toluene biofiltration

he paper focuses on the operation of a pilot plant with four biofilters operated in parallel for determining the suitability of coconut fiber, peat, compost from the digested sludge of a wastewater treatment plant and pine leaves as packing materials for biofiltration of toluene. Physical characteristics of packing materials such as specific surface area, density, pore size and elemental composition were determined for each packing material. Biological activity and packing capabilities related to toluene removal were determined during the startup and operation of the four biofilters under different conditions of nutrients, watering and inlet air relative humidity supply. Nutrient addition was key in improving removal efficiency (RE) and elimination capacity (EC) of biofilters. Feeding of medium with nutrients increased the RE and the EC by a factor of 2 to 4 than these found when supplying only tap water. Additionally, when extra nitrogen was supplied in the medium, RE and EC increased by a factor of 2. Nutrient addition also lead to a microbial population change from bacterial to fungal biofilters. It was denoted that watering control is necessary to improve fungal biofilters performance in terms of ensuring a proper washout of acidic by-products to avoid fungi inhibition and consequent lowered removal capacities.Peer ReviewedPostprint (published version

PRESAS DE AYAGAURES Y GAMBUESA [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201

Dynamic modelling of ammonia biofiltration from waste gases

A dynamic model to describe ammonia removal in a gas-phase biofilter was developed. The math-ematical model is based on discretized mass balances and detailed nitrification kinetics that includeinhibitory effects caused by free ammonia (FA) and free nitrous acid (FNA). The model was able to pre-dict experimental results operation under different loading rates (from 3.2 to 13.2 g NH3h-1m-3). In par-ticular the model was capable of reproducing inhibition caused by high inlet ammonia concentrations. Alsoelimination capacity was accurately predicted. Experimental data was also used to optimize certain modelparameters such as the concentration of ammonia- and nitrite-oxidizing biomass.Peer ReviewedPostprint (published version

Biofiltration of WWTP sludge composting emission at contact times of 2 to 8 seconds

The performance of a biotrickling filter for the abatement of composting emissions was evaluated at short contact times of 2 to 8 seconds. The effect of EBRT, pH control and water renovation rate were evaluated. The average elimination capacity was 13 and 3.3 g N/C m-3 h -1 for ammonia and VOCs, respectively, and the maximum EC obtained during a doping process were 40 and 20 g N/C m -3 h -1 . Biotrickling filters appear as a better alternative than biofilters due to their controllability. However, water renovation becomes a critical parameter to avoid substrate inhibition by nitrite and ammonia accumulation. Not only ammonia absorption is negatively affected at low renovation rate but it is also affected the biological process. A decrease of 40 % was detected in the nitrification step when the hydraulic residence time increased from 2 to 5 hours. Results presented herein demonstrate that high removal efficiencies can be achieved for composting emissions in a biotrickling filter operated at short contact times which entails a substantial reduction of operational and investment costs in comparison to traditional techniques.Peer ReviewedPostprint (author’s final draft

Performance characterization of a full-scale biofilter at an organic waste treatment plant

Data from the regular monitoring of a full-scale biofilter at a municipal solid waste treatment facility for the integral treatment of domestic residues was analyzed in order to assess potential operational problems and to evaluate reactor’s performance in terms of ammonia removal, the target odorous compound at the facility. Performance was assessed based on ammonia removal efficiency and elimination capacity. Average elimination capacities up to 1,6 g NH3 m-3 h-1 at average inlet loads of 2,1 g NH3 m-3 h-1 were found, which correspond to a low-loaded biofilter type. Year-round data collected and packing material analysis revealed a marked effect of water content in the packed bed of the biofilter which lead to reduced removal efficiencies.Peer ReviewedPostprint (published version

Conversion of chemical scrubbers to biotrickling filters for VOCs and H2S treatment at low contact times

The purpose of this work was to evaluate the technical and economical feasibility of converting three chemical scrubbers in series to biotrickling filters (BTFs) for the simultaneous removal of H2S and volatile organic compounds (VOCs). The conversion of the full-scale scrubbers was based on previous conversion protocols. Conversion mainly required replacing the original carrier material and recycle pumps as well as modifying the controls and operation of the reactors. Complete removal of H2S and VOCs on a routine basis was reached at neutral pH in a longer period of time compared to previous conversions reported. Biotrickling filters operated at a gas contact time of about 1.4 s per reactor and at pH controlled between 6.5 and 6.8. Inlet average concentrations below 10 ppmv of H2S and below 5 ppmv for VOCs were often completely removed. The first and second bioreactors played a primary role in H2S removal. Year-round operation of the biotrickling filters proved the ability of the system to handle progressive load increases of H2S and VOCs. However, fast, sudden load changes often lead to reduced removal efficiencies. Odor analyses showed average removal efficiencies above 80 %. Gas chromatography-mass spectrometry of selected samples showed that outlet odor concentration was due to limited removal of VOCs. The conversion showed was economically viable taking into account the theoretical consumption of chemicals needed for the absorption and oxidation of both H2S and VOCs.Peer ReviewedPostprint (published version

Computational and experimental investigation of biofilm disruption dynamics induced by high-velocity gas jet impingement

Peer ReviewedPostprint (published version

The role of water in the performance of biofilters: parameterization of pressure drop and sorption capacities for common packing materials

The presence of water in a biofilter is critical in keeping microorganisms active and abating pollutants. In addition, the amount of water retained in a biofilter may drastically affect the physical properties of packing materials and packed beds. In this study, the influence of water on the pressure drop and sorption capacities of 10 different packing materials were experimentally studied and compared. Pressure drop was characterized as a function of dynamic hold-up, porosity and gas flow rate. Experimental data were fitted to a mathematical expression based on a modified Ergun correlation. Sorption capacities for toluene were determined for both wet and dry materials to obtain information about the nature of interactions between the contaminant, the packing materials and the aqueous phase. The experimental sorption capacities of materials were fitted to different isotherm models for gas adsorption in porous materials. The corresponding confidence interval was determined by the Fisher information matrix. The results quantified the dynamic hold-up effect resulting from the significant increase in the pressure drop throughout the bed, i.e. the financial cost of driving air, and the negative effect of this air on the total amount of hydrophobic pollutant that can be adsorbed by the supports. Furthermore, the results provided equations for ascertaining water presence and sorption capacities that could be widely used in the mathematical modeling of biofilters.Peer ReviewedPostprint (author's final draft

Estratègies i recursos per a no nadius per a la impartició d'assignatures en anglès de química en els graus d'enginyeria

Una eina per aconseguir el domini d’una llengua estrangera, és l’aprenentatge integrat de continguts i llengües estrangeres. Aquesta comunicació es focalitza en l’experiència acadèmica adquirida a partir de la impartició del Grau d’Enginyeria Química a l’Escola Politècnica Superior d’Enginyeria de Manresa (UPC). L’estratègia seguida s’ha basat en la disponibilitat del professorat per impartir assignatures en anglès. Inicialment s’imparteix en anglès l’assignatura de Química ubicada en el primer quadrimestre. Això permet que a l’inici de la carrera, professorat i estudiantat comparteixin un glossari bàsic. Més endavant es familiaritzen amb el llenguatge de laboratori a l’assignatura d’Anàlisi Química Instrumental. El fet que les classes siguin en anglès aconsegueix, en la majoria d’hores de classe, que el nivell d’atenció sigui més alt i això s’ha reflectit en uns millors resultats acadèmics dels estudiants. Com a recursos han estat claus, en primer lloc, el curs “Intensive Interactive Teacher Speaking Skills & Strategies” (ICE, UPC) per estimular la impartició de classes en anglès. Segonament, s’ha disposat d’un recurs molt útil per donar classes de qualsevol assignatura en anglès, el “Class Talk” http://www.upc.edu/slt/classtalk/, elaborat per professors de l’EPSEM i el SLT de la UPC. També cal destacar el recurs anomenat “Multilingual Formulae” (http://mformulae.epsem.upc.edu), que defineix en anglès conceptes químics, fórmules, equacions i altres expressions simbòliques. Finalment s’han elaborat material de les assignatures en anglès (presentacions, apunts, llistat de problemes i guions de pràctiques) com a material suplementari per ajudar a la comprensió de las classes.Peer Reviewe