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

[Abstract] 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.Ministerio de Educación y Ciencia; CTQ2006 – 14997-C02-0

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

CFD modeling of a fixed-bed biofilm reactor coupling hydrodynamics and biokinetics

Peer ReviewedPostprint (author's final draft

High H2S concentrations abatement in a biotrickling filter: start-up at controlled pH and effect of the EBRT and O2H2S supply ratio

[Abstract] In this study, a biotrickling filter reactor was set up and used to treat high concentrations of gaseous H2S. Inoculation was carried out at an inlet H2S concentration of 1,000 ppmv (27.8 g H2S m-3 h-1) and sludge from a municipal wastewater treatment plant (MWWTP) was used as inoculum. After 3 days, removal efficiency (RE) above 98 % was achieved even after the loading rate (LR) was increased up to 55.6 g H2S m-3 h-1 (2,000 ppmv). Operation at such LR, with an empty bed residence time (EBRT) of 180 s and controlled pH of 6.5-7 was carried out during 3 months. The start-up phase, the effect of decreasing EBRTs at constant inlet concentration and the composition of the process end-products in relation to the supplied O2/H2S ratio were studied. Also, a carbon mass balance under steady state conditions was calculate

Study of NH3 removal by gas-phase biofiltration: effects of shock loads and watering rate on biofilter performance

[Abstract] Ammonia biofiltration performance under shock loads episodes was studied in a reactor packed with coconut fiber as carrier material. Periodical gas and leachate samplings were analyzed and used to characterize the biofilter performance in terms of removal efficiency (RE) and elimination capacity (EC). Nitrogen fractions in the leachate were quantified to identify the experimental rates of nitritation and nitratation.. In a primary experiment a sudden increment of ammonia load was applied for 1 day by changing the ammonia inlet load from 5.2 to 29.1 g N.m-3.h-1. Even though stable operation was obtained (RE of 99.9%), a notable accumulation of nitrite was verified in the leachate. Experimental rates showed that nitritation increased at the same the same ratio that ammonia load was varied. However the nitratation seemed to be largely affected by high ammonia and nitrite concentration. In a subsequent experiment varying the inlet ammonia load, the system was rapidly recovered by increasing the watering rate. Since ammonia was partially removed by physicochemical process as observed in previous experiments, a final experimental was conducted to improve the nitritation capacity. The addition of inorganic carbon source demonstrated to enhance the capacity of the biofilter to degrade a higher amount of ammonia

Optimization of SO2 and NOx sequential wet absorption in a two-stage bioscrubber for elemental sulphur valorisation

Flue gases contain SO2 and NOx that can be treated together for elemental sulphur recovery in bioscrubbers, a technology that couples physical-chemical and biological processes for gaseous emissions treatment in a more economic manner than classical absorption. Sequential wet absorption of SO2 and NOx from flue gas is thoroughly studied in this work in a two-stage bioscrubber towards elemental sulphur valorisation pursuing reuse of biological process effluents as absorbents. The optimal operating conditions required for SO2 and NOx absorption in two consecutive spray absorbers were defined using NaOH-based absorbents. Overall, removal efficiencies of 98.9% and 55.9% for SO2 and NOx abatement were obtained in two in-series scrubbers operated under a gas contact time of 1 and 100 s, and a liquid-to-gas ratio of 7.5 and 15 L m−3, respectively. Higher NOx removal efficiency to clean gas emission was obtained by oxidants dosing in the absorber for NOx absorption. High NaHCO3 concentration in a two-stage bioscrubber effluent was exploited as alkaline absorbent for flue gas treatment. The performance of scrubbers using an absorbent mimicking a reused effluent exhibited the same removal efficiencies than those observed using NaOH solutions. In addition, the reuse of bioprocess effluent reduced reagents' consumption by a 63.7%. Thus, the two-stage bioscrubber proposed herein offers an environmentally friendly and economic alternative for flue gas treatment

PRESAS DE AYAGAURES Y GAMBUESA [Material gráfico]

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

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

Mechanistic modeling of glycerol fermenting and sulfate-reducing processes by granular sludge under sulfidogenic conditions

Acord transformatiu CRUE-CSICGlycerol can be converted to ethanol, 1,3-propanediol, formate, acetate, propionate, and inorganic carbon under anaerobic conditions through oxidative and reductive pathways in the absence and presence of sulfate. A structured mathematical model considering multiple pathways of glycerol fermentation combined with sulfate reduction was set up in this work, where three mechanisms were proposed and verified by modeling. Finally a mechanism properly predicting both glycerol fermenting and sulfate-reducing processes was chosen. Concentrations of multiple intermediates measured in batch activity tests were satisfactorily described by the model. The intermediate products of glycerol fermentation included formate, propionate, ethanol, 1,3-propanediol, and 3-hydroxypropionate (3HP). The main pathways of glycerol fermentation were the oxidative pathway to produce ethanol and the reductive pathway to produce 1,3-propanediol. The former accounted for 40.6% of the total glycerol converted whereas the latter accounted for 42.6%. 1,3-propanediol was converted to 3HP coupled to sulfate reduction. 3HP was mainly further oxidized to acetate. The kinetic parameters of maximum specific uptake rates of substrate were calibrated and then, the sulfate reduction process was validated. The confidence intervals of estimated parameters were assessed according to the Fisher information matrix (FIM) method. The low confidence intervals obtained indicated that the experimental behavior was satisfactorily described with the proposed kinetic model