Simultaneous application of vacuum and sweep gas in a polypropylene membrane contactor for the recovery of dissolved methane from water

Abstract Vacuum and nitrogen as sweep gas were used simultaneously (combination mode) to generate the driving force in a microporous polypropylene membrane contactor for the recovery of dissolved methane from water. Experiments were carried out under different liquid flow-rates (5.0–28.0 L h−1), N2 flow-rates (0.5–1.5 L h−1) and vacuum pressures (0–480 mbar). The maximum removal efficiency of methane was >90% at moderate values of gas-to-liquid ratios (G/L) and vacuum of 0.2 and ≤ 200 mbar, respectively. Removal efficiencies obtained in combination mode were usually higher than when using vacuum or sweep gas, separately. To achieve a methane content >35% in the recovered gas, G/L values low…

Removal of acetone from air emissions by biotrickling filters: providing solutions from laboratory to full-scale

A full-scale biotrickling filter (BTF) treating acetone air emissions of wood-coating activities showed difficulties to achieve outlet concentrations lower than 125 mg C m-3, especially for high inlet concentrations and oscillating emissions. To solve this problem, a laboratory investigation on acetone removal was carried out simulating typical industrial conditions: discontinuous and variable inlet concentrations and intermittent spraying. The results were evaluated in terms of removal efficiency and outlet gas emission pattern. Industrial emissions and operational protocols were simulated: inlet load up to 70 g C m-3 h-1 during 2 cycles of 4 h per day and intermittent trickling of 15 min …

Effect of substrate composition on the stability and microbial community of an anaerobic expanded granular sludge bed reactor treating printing solvent mixtures of ethanol and glycol ethers

Abstract The performance and microbial community analysis of an expanded granular sludge bed reactor (EGSB) treating wastewater polluted with mixtures of ethanol and glycol ethers –such as 1-ethoxy-2-propanol (E2P) and 1-methoxy-2-propanol (M2P)– were evaluated. The results showed good EGSB performance during start-up (100% of ethanol) in terms of global removal efficiency (RE > 95%). When glycol ethers were added, an initial adaptation period was observed of ~20 days. While the RE of M2P became complete, the RE of E2P reached only 65%. The proportion of glycol ethers was gradually increased and at the end of this study only a binary mixture of E2P and M2P was fed. In the last stage, the gl…

Performance evaluation of a biotrickling filter treating a mixture of oxygenated VOCs during intermittent loading

Laboratory scale-studies on the biodegradation of a 1:1:1 weight mixture of three oxygenated volatile organic compounds (VOCs), ethanol, ethyl acetate, and methyl-ethyl ketone (MEK) in a biotrickling filter (BTF) were carried out using two identically sized columns, filled with different polypropylene rings. The performance of the BTFs was examined for a period of 10 months applying several operational strategies. Similar performance was obtained for both supports. Intermittent flow rate of trickling liquid was shown beneficial to improve the removal efficiency (RE). Continuous feeding of VOC resulted in an excessive accumulation of biomass so high pressure drop was developed in less than 2…

Alkylation of Benzene with Short-Chain Olefins over MCM-22 Zeolite: Catalytic Behaviour and Kinetic Mechanism

Abstract Benzene alkylation with ethene and propene has been carried out under liquid-phase reaction conditions over zeolites MCM-22, Beta, and ZSM-5. MCM-22 seems to be a good catalyst for benzene alkylation especially with propene, showing high activity and stability and good selectivity. Kinetic experiments show that alkylation with propene follows an Eley–Rideal type mechanism.

Influence of activated carbon on performance and microbial communities in the treatment of solvent pollutant mixtures in a continuous stirred tank reactor

The influence of the addition of granular activated carbon (GAC) on the anaerobic treatment of wastewater with a mixture of ethanol and 1-ethoxy-2-propanol (E2P), which are typical pollutants from the flexographic/printing industry, was evaluated. For this purpose, the reactor performance and microbial community in two continuous stirred tank reactors (CSTRs), i.e. control and GAC supplemented, were assessed. Both reactors, seeded with anaerobic granular biomass, showed similar global performance (RE > 93%), except after organic load shocks and after E2P addition. GAC supplementation substantially enhanced the response of the biological system to organic load shocks and reduced the acclimat…

Coupling Adsorption and Biological Technologies for Multicomponent and Fluctuating Volatile Organic Compounds Emissions Abatement: Laboratory-Scale Evaluation and Full-Scale Implementation

The capacity of activated carbon as a buffer pretreatment combined with biotrickling filtration for volatile organic compound (VOC) removal has been studied. The adsorption capacity of commercial activated carbons for m-xylene, acetone and n-butyl acetate (typical paint solvents) was evaluated, including the response to the interchanging of adsorbed compounds and to mixtures over fluctuating inlet conditions. The adsorption of m-xylene and n-butyl acetate was mainly irreversible and more than three times higher than for acetone. The prior use of activated carbon influenced adsorption and buffer capacities in consecutive adsorption/desorption cycles. The Dubinin–Radushkevich equation was use…

Biofiltration of ethyl acetate under continuous and intermittent loading

A laboratory-scale peat biofilter was used for ethyl acetate removal from an air stream over a period lasting 1 yr. In a first stage, the biofilter was operated under continuous mode: a maximum elimination capacity of 400 g m−3 h−1 was obtained, and ethyl acetate was efficiently degraded with empty bed residence time (EBRT) as short as 22 s. The estimated yield coefficient, determined from the carbon dioxide production, resulted in 0.42 g dry biomass produced per gram of ethyl acetate consumed. The living and the dead cell concentrations were also monitored. The dead cell percentages varied between 18 and 85%, progressive increases in the dead cell percentages were achieved as EBRT decrease…

Isobaric Vapor−Liquid Equilibria for the Binary System 3-Methylpentane + Ethanol and for the Ternary System 2-Methyl-2-propanol + Ethanol + 3-Methylpentane at 101.3 kPa

Isobaric vapor-liquid equilibria data were measured for the 3-methylpentane + ethanol binary system and 2-methyl-2-propanol + ethanol + 3-methylpentane ternary system at 101.3 kPa in a temperature range from 329 to 356 K. The data were found to be thermodynamically consistent according to the Van Ness-Byer-Gibbs method for the binary system and according to the McDermott-Ellis method for the ternary one. The binary system shows a minimum boiling azeotrope that boils at 327.9 K and contains 71.4 mol % 3-methylpentane. The binary interaction parameters obtained from this work and literature data are used to predict the vapor-liquid equilibrium for the ternary system using the UNIQUAC, NRTL, a…

Evolution of Bacterial Community in a Full-scale Biotrickling Filter by Fluorescence in Situ Hybridization (FISH)

The performance of a full-scale biotrickling system for the treatment of exhaust gases from two different paint sources at a furniture facility, was investigated applying Fluorescense in situ hybridization (FISH). This technique allowed the detection of major bacteria groups and, therefore, helped in understanding complex microbial communities. The results indicated that Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria were more predominant than Firmicutes and Actiniobacterias. In addition, a variation in the composition of the bacterial community throughout the time of operation and with the paint source was observed. Betaproteobacteria showed similar r…

Isobaric Vapor−Liquid Equilibria for the Binary Mixtures of Styrene with Ethylbenzene, o-Xylene, m-Xylene, and p-Xylene

Consistent vapor−liquid equilibria (VLE) data have been determined at (5 and 15) kPa for the binary systems styrene + ethylbenzene, + o-xylene, + m-xylene, and + p-xylene in the temperature range (324 to 359) K. The binary systems exhibit very slight deviations from ideal behavior, and no azeotrope is present. The VLE data were well-correlated by the Wilson, NRTL, and UNIQUAC equations.

Densities, Refractive Indices, and Derived Excess Properties of the Binary Systems Toluene + Isooctane and Methylcyclohexane + Isooctane and the Ternary Systems tert-Butyl Alcohol + Toluene + Isooctane and tert-Butyl Alcohol + Methylcyclohexane + Isooctane at 298.15 K

This paper reports mesurements of the densities and refractive indices of the binary systems toluene + isooctane and methylcyclohexane + isooctane and the ternary systems tert-butyl alcohol (TBA) + toluene + isooctane and tert-butyl alcohol (TBA) + methylcyclohexane + isooctane over the entire range of composition at 298.15 K. Excess molar volumes and changes of refractive indices were evaluated from the experimental data obtained. These derived properties were fitted to variable-degree polynomials. The experimental values of physical properties were compared with the values estimated by different methods.

Densities, refractive indices, and derived excess properties of the binary systems tert-butyl alcohol+toluene, +methylcyclohexane, and +isooctane and toluene+methylcyclohexane, and the ternary system tert-butyl alcohol+toluene+methylcyclohexane at 298.15 K

Abstract This paper reports experimental densities and refractive indices of the binary systems tert -butyl alcohol (TBA)+toluene, +isooctane, and +methylcyclohexane, and toluene+methylcyclohexane, and the ternary system TBA+toluene+methylcyclohexane, over the entire range of composition at 298.15 K. Excess molar volumes and changes of refractive indices were evaluated from the experimental data obtained. These derived properties were fitted to variable-degree polynomials. The experimental values of physical properties were compared with the values estimated by different methods of prediction.

Photodegradation of Toluene, m-Xylene, and n-Butyl Acetate and Their Mixtures over TiO2 Catalyst on Glass Fibers

The abatement of typical paint solvent compounds as individuals and in mixtures was carried out in an annular TiO2 supported reactor, for concentrations up to 900 mg C m–3. Two different fiberglass supports were compared, and the catalyst supported over a fiber mat showed better performance, with a lower pressure drop (>35% of reduction) and a slightly higher removal efficiency (about 2%) than that supported over glass wool. For every target compound in the whole range of relative humidity studied (4–75%), the photocatalytic activity increased with the air water content. The removal of the compounds in the binary and ternary mixtures was depressed, even >90% for toluene, compared with indiv…

Performance and feasibility of biotrickling filtration in the control of styrene industrial air emissions

Abstract The performance and feasibility of a pilot unit of biotrickling filter (BTF) for the treatment of industrial emissions polluted by styrene was investigated for one year at a fiber reinforced plastic industrial site. The pilot unit was packed with a structured material with a volume of 0.6 m3. Monitoring results have shown successful treatment of the industrial styrene emissions working at empty bed residence times (EBRT) between 31 and 66 s. The best performance was obtained after 300 days when a more stable biofilm had been developed, obtaining the highest elimination capacity of 18.8 g m−3 h−1 (removal efficiency of 75.6%) working at 31 s of EBRT. In addition, a photocatalytic re…

Mathematical modeling of the biofiltration of ethyl acetate and toluene and their mixture

Abstract A dynamic model for ethyl acetate and toluene removal by biofiltration is presented. Haldane-type kinetic expressions that include the oxygen limitation, the inhibition effect due to high concentration of substrate, and the cross-inhibition between substrates have been considered. A decrease in the biomass density with the bed height was proposed to represent the performance of peat biofilters over a broad range of operating conditions. Experimental yield coefficients have been derived from the experimental CO 2 production data. The unknown kinetic parameters of the model along with the coefficient for axial biomass density distribution were calibrated using experimental data from …

Performance of a polypropylene membrane contactor for the recovery of dissolved methane from anaerobic effluents: Mass transfer evaluation, long-term operation and cleaning strategies

Abstract A polypropylene membrane contactor was used for the recovery of dissolved methane from an anaerobic reactor effluent. Effect of operational parameters, operation mode and fouling on long-term operation was studied using vacuum pressure or N 2 as sweep gas. Results were analyzed based on the mass transfer estimations. Lower performance was observed in the shell-side mode due to the lower liquid velocity and the probable channeling. Membrane pore wetting was observed with the increase in Q L in the vacuum-pressure mode. This was confirmed with mass transfer resistance analysis, resulting in an estimated wetted pore fraction of between 0.25 and 0.53. The highest removal efficiencies w…

Removal of TEX vapours from air in a peat biofilter: influence of inlet concentration and inlet load

This paper presents the results of the study of the removal of toluene, ethylbenzene, and o-xylene (TEX) by biofiltration using a commercial peat as filter-bed material. Runs with a single organic compound in air, and with the mixture of TEX in air, were carried out for at least 55 days in laboratory-scale reactors inoculated with a conditioned culture. The influence of organic compound inlet load and of gas flow rate on the biofilter's performance was studied, including relatively high values of pollutant inlet concentration (up to 4.3 gC m−3 for ethylbenzene, 3.2 gC m−3 for toluene, and 2.7 gC m−3 for o-xylene). Results obtained show maximum elimination capacities of 65 gC m−3 h−1 for o-x…

Long-term performance of peat biofilters treating ethyl acetate, toluene, and its mixture in air.

Three laboratory-scale peat biofilters were operated at 90 s empty bed residence time (EBRT) for over a year. Biodegradation of ethyl acetate, toluene, or a 1:1 mixture were investigated. In first stage, inlet concentration was progressively increased from 0.4 to 4.5 g/m3. The maximum elimination capacity (EC) found for ethyl acetate was 190 gC/m3·h, and it was not affected by toluene. The maximum EC found for toluene as a sole contaminant was 150 gC/m3·h, but the presence of ethyl acetate decreased the toluene maximum EC to 80 gC/m3·h. From respirometry monitoring, values of 3.19 g CO2/gC and 3.06 g CO2/gC for pure ethyl acetate and pure toluene, respectively, were found, with overall yiel…

Densities, refractive indices, and derived excess properties of tert-butyl alcohol, methyl tert-butyl ether and 2-methylpentane binary and ternary systems at 303.15 K

Abstract This paper reports experimental densities and refractive indices of the binary systems tert-butyl alcohol (TBA)+methyl tert-butyl ether (MTBE), TBA+2-methylpentane, and MTBE+2-methylpentane, and the ternary system TBA+MTBE+2-methylpentane, over the entire range of composition at 303.15 K. Excess molar volumes and changes of refractive indices were evaluated from the experimental data obtained. These derived properties were fitted to variable-degree polynomials. The experimental values of physical properties were compared with the values estimated by different methods of prediction.

UV photocatalytic oxidation of paint solvent compounds in air using an annular TiO2-supported reactor

BACKGROUND: One of the most important industrial sources of volatile organic compounds (VOCs) is related to coating and painting applications. In this sense, photocatalytic oxidation can become an innovative and promising alternative for the remediation of air polluted by VOCs. In this study the UV photodegradation of m-xylene, toluene and n-butyl acetate, as representative compounds of paint solvents, was carried out in an annular reactor using a TiO2–glass wool supported catalyst. RESULTS The removal of each component and their mixture, simulating an industrial emission, was evaluated under different operational conditions. A maximum elimination capacity of 12, 18 and 80 mg C m−3 s−1 was …

Evaluation of a combined activated carbon prefilter and biotrickling filter system treating variable ethanol and ethyl acetate gaseous emissions

The removal of a 1:1 by weight mixture of ethanol and ethyl acetate was studied in a gas phase biotrickling filter running under conditions that simulated industrial emissions from the flexographic sector, i.e. discontinuous loading (twelve hours per day and five days per week) and oscillating concentration of the inlet stream. Three sets of experimental conditions were tested in which empty-bed residence time varied from 60 to 25s (inlet loads from 50 to 90g Cm -3 h -1 ). The biotrickling filter reached a maximum elimination capacity of 48.5g Cm -3 h -1 (removal efficiency = 68.9%) for an empty-bed residence time of 40 s. A decrease in the residence time from 40 to 25 s adversely affected …

Comparative study of degassing membrane modules for the removal of methane from Expanded Granular Sludge Bed anaerobic reactor effluent

Abstract The feasibility of an emergent technology for in situ removal/recovery of methane from the effluent of an Expanded Granular Sludge Bed (EGSB) anaerobic reactor has been studied. For this purpose, the performances of two commercial hollow fibre degassing contactors with different membrane materials – microporous (polypropylene, PP) and non-porous (polydimethylsiloxane, PDMS) – were compared. The influence of water fluxes (Q L /A membrane ranging from 22.6 to 377.4 L h −1  m −2 ), vacuum pressure (140–800 mbar), sweep gas fluxes (Q N2 /A membrane ranging from 0.14 × 10 3 to 4.44 × 10 3  L h −1  m −2 ), and mode of operation (liquid flowing in the lumen side or the shell side) was stu…

Vapor−Liquid Equilibria for the Binary Systems tert-Butyl Alcohol + Toluene, + Isooctane, and + Methylcyclohexane at 101.3 kPa

Vapor-liquid equilibria were measured for binary systems of tert-butyl alcohol with toluene, isooctane, and methylcyclohexane at 101.3 kPa using a recirculating still. Experimental values of the vapor pressure of non-oxygenated pure components have been obtained. The accuracy of experimental measurements was ±0.01 K in temperature, ±0.01 kPa in pressure, and ±0.001 in mole fractions. The results are thermodynamically consistent according to the point-to-point consistency test. The data were correlated with five liquid-phase activity coefficients models (Margules, Van Laar, Wilson, NRTL, UNIQUAC).

Biofiltration of ethylbenzene vapours: influence of the packing material.

In order to investigate suitable packing materials, a soil amendment composed of granular high mineralized peat (35% organic content) locally available has been evaluated as carrier material for biofiltration of volatile organic compounds in air by comparison with a fibrous peat (95% organic content). Both supports were tested to eliminate ethylbenzene from air streams in laboratory-scale reactors inoculated with a two-month conditioned culture. In pseudo-steady state operation, experiments at various ethylbenzene inlet loads (ILs) were carried out. Maximum elimination capacity of about 120 g m(-3) h(-1) for an IL of 135 g m(-3) h(-1) was obtained for the fibrous peat. The soil amendment re…

Biological nitrate removal from wastewater of a metal-finishing industry

An upflow packed bed reactor at laboratory scale has been operated for a continuous period of 5 months to investigate the technical feasibility of biological nitrate removal applied to the effluent of the coagulation-sedimentation wastewater of a metal-finishing industry. The reactor was fed with industrial wastewater in a five-fold dilution to reproduce the global spill in the factory (20/80, industrial wastewater/domestic wastewater) with a concentration of nitrate between 141 and 210 gNO(3)-N/m(3). Methanol was added as a carbon source for denitrification. Inlet flow rate was progressively increased from 9 to 40 L/day (nitrogen input load from 45 to 250 gNO(3)-N/(m(3)h)). The highest obs…

Evaluation of a pilot-scale biotrickling filter as a VOC control technology for the plastic coating sector

Abstract The performance and feasibility of a biotrickling filter (BTF) pilot unit for the treatment of exhaust gases from two robotic spray paint booths at a plastic coating facility were investigated. The volatile organic compound (VOC) concentrations in the emissions of the exhaust gases from the paint booths were relatively stable, although the VOC composition depended on the applied solvent-paint formulation in the booths. The pilot plant was operated for one year at empty bed residence times (EBRTs) ranging from 30 to 93 s. The performance of the system was affected by the solvent-paint formulations. An EBRT between 30 and 40 s was enough to meet legal requirements for products contai…

Mild Hydrocracking of Vacuum Gasoil over NiMo-Beta Zeolite Catalysts: The Role of the Location of the NiMo Phases and the Crystallite Size of the Zeolite

Abstract Mild hydrocracking composite catalysts based on NiMo/γ-Al2O3-Beta zeolite have been prepared and the influence of the location of the NiMo phases has been studied. A good hydrocracking activity and the highest HDS conversion was found during the hydrocracking of a vacuum gasoil with the composite catalyst where the NiMo is located on the alumina component and then mixed with the zeolite in a proportion of 1 : 1 by weight. The crystal size of the beta zeolite had a significative influence on the catalytic behaviour, being better the smaller the crystallite size is. The small crystallite beta-based catalyst displayed a higher hydrocracking activity than conventional USY and silica-al…

Influence of ground tire rubber on the transient loading response of a peat biofilter

Abstract The effect of using ground tire rubber (GTR) as an adsorptive material in the removal of a 2:1:1 weight mixture of n-butyl acetate, toluene and m-xylene by using a peat biofilter under different intermittent conditions was investigated. The performance of two identical size biofilters, one packed with fibrous peat alone and the other with a 3:1 (vol) fibrous peat and GTR mixture, was examined for a period of four months. Partition coefficients of both materials were measured. Values of 53, 118 and 402 L kg −1 were determined for n-butyl acetate, toluene and m-xylene in peat, respectively; and values of 40, 609 and 3035 L kg −1 were measured for the same compounds in GTR. Intermitte…

Anaerobic degradation of glycol ether-ethanol mixtures using EGSB and hybrid reactors: Performance comparison and ether cleavage pathway.

Abstract The anaerobic biodegradation of ethanol-glycol ether mixtures as 1-ethoxy-2-propanol (E2P) and 1-methoxy-2-propanol (M2P), widely used in printing facilities, was investigated by means of two laboratory-scale anaerobic bioreactors at 25oC: an expanded granular sludge bed (EGSB) reactor and an anaerobic hybrid reactor (AHR), which incorporated a packed bed to improve biomass retention. Despite AHR showed almost half of solid leakages compared to EGSB, both reactors obtained practically the same performance for the operating conditions studied with global removal efficiencies (REs) higher than 92% for organic loading rates (OLRs) as high as 54 kg of chemical oxygen demand (COD) m−3 d…

Recovery of dissolved methane through a flat sheet module with PDMS, PP, and PVDF membranes

Abstract A degassing contactor using a flat sheet membrane module (FM) was operated in sweep gas mode to study the performance of several commercial polymer membranes, both dense (polydimethylsiloxane, PDMS) and microporous (polypropylene, PP, and polyvinylidenefluoride, PVDF), for the recovery of dissolved methane from water. Non-steady state experiments were conducted at different liquid (QL, 3.5–40.5 L h-1) and gas flow rates (QN2, 0.05–15.00 L h-1). In the case of PDMS, PP, and when PVDF was operated at moderate high QL (≥ 21 L h-1), similar methane removal efficiencies (RE) were obtained. In the case of PVDF operated at relatively low QL (3.5 L h-1), a lower RE was observed. A model fo…

Comparison between laboratory and pilot biotrickling filtration of air emissions from painting and wood finishing

BACKGROUND: Painting and wood finishing is one industrial sector affected by the European Union environmental regulations on volatile organic compound (VOC) air emissions. The painting process typically results in high flow rates with low VOC concentrations, so biotrickling filtration could be an economical alternative for controlling air emissions. This study analyses the operation of a pilot unit installed in a furniture facility, and compares its performance with the removal efficiency obtained in the laboratory using a synthetic feed composed of n-butyl acetate, toluene and m-xylene to simulate industrial air emissions. RESULTS: Laboratory studies showed that fluctuating and oscillating…

Catalytic Performance of the New Delaminated ITQ-2 Zeolite for Mild Hydrocracking and Aromatic Hydrogenation Processes

Abstract Catalysts based on NiMo and Pt supported on the new delaminated ITQ-2 zeolite have been prepared and their catalytic properties evaluated for the mild hydrocracking (MHC) of vacuum gasoil and aromatic hydrogenation. The results were compared with those obtained using other conventional supports, e.g., silica, γ-alumina, amorphous silica–alumina (25 wt% Al 2 O 3 ), and USY zeolite, all of which contain the same metal loading as the ITQ-2 material. In the case of MHC of vacuum gasoil, NiMo/ITQ-2 displayed a higher hydrocracking activity than NiMo/SiO 2 –Al 2 O 3 and NiMoγ-Al 2 O 3 , and even higher activity than NiMo/USY in the range 375–425°C. Moreover, NiMo/ITQ-2 had a selectivity …

Control of VOC emissions from a flexographic printing facility using an industrial biotrickling filter.

The study of an industrial unit of biotrickling filter for the treatment of the exhaust gases of a flexographic facility was investigated over a 2-year period with the objective to meet the volatile organic compound (VOC) regulatory emission limits. Increasing the water flow rate from 2 to 40 m3 h−1 improved the performance of the process, meeting the VOC regulation when 40 m3 h−1 were used. An empty bed residence time (EBRT) of 36 s was used when the inlet air temperature was 18.7 °C, and an EBRT as low as 26 s was set when the inlet temperature was 26.8 °C. During this long-term operation, the pressure drop over the column of the bioreactor was completely controlled avoiding clogging prob…

Biofiltration of toluene in the absence and the presence of ethyl acetate under continuous and intermittent loading

BACKGROUND: Two peat biofilters were used for the removal of toluene from air for one year. One biofilter was fed with pure toluene and the other received 1:1 (by weight) ethyl acetate:toluene mixture. RESULTS: The biofilters were operated under continuous loading: the toluene inlet load (IL) at which 80% removal occurred was 116 g m−3 h−1 at 57 s gas residence time. Maximum elimination capacity of 360 g m−3 h−1 was obtained at an IL of 745 g m−3 h−1. The elimination of toluene was inhibited by the presence of ethyl acetate. Intermittent loading, with pollutants supplied for 16 h/day, 5 days/week, did not significantly affect the removal efficiency (RE). Biomass was fully activated in 2 h a…

Effect of pre-treatments based on UV photocatalysis and photo-oxidation on toluene biofiltration performance

BACKGROUND: The integration of UV photocatalysis and biofiltration seems to be a promising combination of technologies for the removal of hydrophobic and poorly biodegradable air pollutants. The influence of pre-treatments based on UV254 nm photocatalysis and photo-oxidation on the biofiltration of toluene as a target compound was evaluated in a controlled long-term experimental study using different system configurations: a standalone biofilter, a combined UV photocatalytic reactor-biofilter, and a combined UV photo-oxidation reactor (without catalyst)-biofilter. RESULTS: Under the operational conditions used (residence time of 2.7 s and toluene concentrations 600–1200 mg C m−3), relativel…

Biotrickling Filters for Removal of Volatile Organic Compounds from Air in the Coating Sector

Full-scale biotrickling filtration of volatile organic compounds from air emission in wood-coating activities

BACKGROUND: Biotrickling filtration could be considered as a suitable and viable technology for controlling the industrial emissions of volatile organic compounds (VOCs) in waste gases. In this study, the performance of a full-scale biotrickling system, including a passively activated carbon-smoothing prefilter was investigated for the treatment of exhaust gases from two different paint spray sources at a furniture facility. RESULTS: The VOC profiles were uneven for both sources, but the second source was more irregular, with highly variable VOC loads. The plant was operated at empty bed residence times (EBRTs) between 20 and 100 s. The system was able to control the VOC emissions, so air t…

Performance of a pilot-scale biotrickling filter in controlling the volatile organic compound emissions in a furniture manufacturing facility.

A 0.75-m3 pilot-scale biotrickling filter was run for over 1 yr in a Spanish furniture company to evaluate its performance in the removal of volatile organic compounds (VOCs) contained in the emission of two different paint spray booths. The first one was an open front booth used to manually paint furniture, and the second focus was an automatically operated closed booth operated to paint pieces of furniture. In both cases, the VOC emissions were very irregular, with rapid and extreme fluctuations. The pilot plant was operated at an empty bed residence time (EBRT) ranging from 10 to 40 sec, and good removal efficiencies of VOCs were usually obtained. When a buffering activated carbon prefil…

Biotrickling filter modeling for styrene abatement. Part 1: Model development, calibration and validation on an industrial scale

Abstract A three-phase dynamic mathematical model based on mass balances describing the main processes in biotrickling filtration: convection, mass transfer, diffusion, and biodegradation was calibrated and validated for the simulation of an industrial styrene-degrading biotrickling filter. The model considered the key features of the industrial operation of biotrickling filters: variable conditions of loading and intermittent irrigation. These features were included in the model switching from the mathematical description of periods with and without irrigation. Model equations were based on the mass balances describing the main processes in biotrickling filtration: convection, mass transfe…

Isovaleraldehyde degradation using UV photocatalytic and dielectric barrier discharge reactors, and their combinations

International audience; The abatement of isovaleraldehyde present in air was carried out in UV photocatalytic and dielectric barrier discharge reactors (and their combinations) for concentrations up to 150 mg C m−3 and air flow rates ranging from 4 to 10 m3 h−1. A kinetic study was performed following a Langmuir–Hinshelwood model. Photocatalytic treatment of an isovaleraldehyde and isovaleric acid mixture showed a clear inhibition of isovaleric acid abatement in presence of isovaleraldehyde. Dielectric barrier discharge treatment of isovaleraldehyde showed an increase of removal efficiency with applied voltage and a decrease with air flow rate and inlet concentration. Moreover, introduction…

Hydrogenation of Aromatics in Diesel Fuels on Pt/MCM-41 Catalysts

Abstract The hydrogenation activity of Pt supported on two mesoporous MCM-41 samples differing in their chemical composition has been studied by following the kinetics of the hydrogenation of naphthalene at 225–275°C reaction temperature and 5.0 MPa total pressure and by comparing the kinetic parameters obtained with Pt supported on a mesoporous amorphous silica-alumina (MSA) and other conventional supports, such as commercial amorphous silica-alumina (ASA), zeolite USY, γ-alumina, and silica. The two mesoporous MCM-41 and MSA materials having very high surface areas allowed for a better dispersion of the Pt particles, and they showed a superior overall hydrogenation activity as compared to…

Demethanization of aqueous anaerobic effluents using a polydimethylsiloxane membrane module: Mass transfer, fouling and feasibility

Abstract The performance, fouling and feasibility of a polydimethylsiloxane hollow fibre membrane module for in situ methane degasification from the effluent of an Expanded Granular Sludge Bed anaerobic reactor has been investigated. Experiments at different operational conditions were carried out (liquid flow, sweep gas flow and vacuum pressure) with maximum removal efficiency (77%) at lowest flow-rate (0.4 L h−1), highest vacuum gauge pressure (−800 mbar) and liquid flowing in lumen side. Mass transport analysis denoted a considerably higher methane transfer than that predicted (attributed to liquid oversaturation). An enhancement factor for liquid phase has been proposed to correlate the…