Treatment of methanol in a dry biofilm reactor using tubular carrier

2000 ◽  
Vol 42 (5-6) ◽  
pp. 419-427 ◽  
Author(s):  
F. Thalasso ◽  
F. Omil ◽  
J.O. Otero ◽  
J.M. Lema
Keyword(s):  
Gas Flow ◽  
Degradation Rate ◽  
Biofilm Reactor ◽  
Lag Phase ◽  
Biofilm Growth ◽  
Flow Rates ◽  
Waste Gas ◽  
Loading Rates ◽  
Volumetric Loading ◽  
Specific Degradation

A 13.4 l Dry Tubular Biofilm reactor (DTB), with 19 PVC tubes as carrier, was used to treat polluted air using methanol as a model pollutant. The design of this reactor was based on the creation of a mist by contacting the waste gas and a discontinuous liquid nutrient supply into an atomising nozzle. Air was fed into the reactor at specific gas flow rates from 60 to 230 m3/m3 · h, containing from 0.25 to 2.84×10-3 kg/m3 of methanol (volumetric loading rates from 1.4 to 4.7 kg/m3 · d). Biofilm growth was observed from the very beginning of the experiment although preferentially on the reactor's wall and not on the tubular carrier. Methanol degradation was observed to increase along the experiment and reached 1.24 kg/m3 · d. The efficiency of this system was limited by the clogging of the tubes used as carrier. The biofilm developed directly on the wall of the reactor had a specific methanol degradation rate of 1.08 kg/kgVSS · h, while only 0.6 kg/kgVSS · h of methanol were degraded after a long lag phase by the biomass developed inside the tubular carrier. Another experiment was carried out with the empty reactor without PVC tubing. In that case, a specific degradation rate of 4.15 kg/m3 · d was observed, which confirm that PVC tubular carrier was clearly not favourable to the process.

scholarly journals Influence of Pressure on Gas/Liquid Interfacial Area in a Tray Column

2020 ◽  
Vol 10 (13) ◽  
pp. 4617
Author(s):  
Adel Almoslh ◽  
Falah Alobaid ◽  
Christian Heinze ◽  
Bernd Epple
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Volumetric Flow Rate ◽  
Interfacial Area ◽  
Gas Flow Rate ◽  
Test Rig ◽  
Flow Rates ◽  
Waste Gas ◽  
Simulated Waste ◽  
Series Of Experiments

The influence of pressure on the gas/liquid interfacial area is investigated in the pressure range of 0.2–0.3 MPa by using a tray column test rig. A simulated waste gas, which consisted of 30% CO2 and 70% air, was used in this study. Distilled water was employed as an absorbent. The temperature of the inlet water was 19 °C. The inlet volumetric flow rate of water was 0.17 m3/h. Two series of experiments were performed; the first series was performed at inlet gas flow rate 15 Nm3/h, whereas the second series was at 20 Nm3/h of inlet gas flow rate. The results showed that the gas/liquid interfacial area decreases when the total pressure is increased. The effect of pressure on the gas/liquid interfacial area at high inlet volumetric gas flow rates is more significant than at low inlet volumetric gas flow rates. The authors studied the effect of decreasing the interfacial area on the performance of a tray column for CO2 capture.

Effects of Liquid and Gas Flow Rates on the Performance of a Fluidized Bed Photocatalytic Reactor

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Shuangshi Dong ◽  
Dandan Zhou ◽  
Xiaotao T Bi
Keyword(s):  
Fluidized Bed ◽  
Gas Flow ◽  
Degradation Rate ◽  
Air Flow ◽  
Sol Gel ◽  
Phenol Degradation ◽  
Water Contaminants ◽  
Flow Rates ◽  
Carbon Particles ◽  
Three Phase

Titanium dioxide was immobilized onto spherical activated carbon particles via the sol-gel coating method. The photo-catalyst, annealed at 500 °C, was found to posses the highest activity according to the results of a bench-scale test. The photocatalytic performance of the immobilized photocatalyst was studied in a three-phase fluidized bed photoreactor, with the use of phenol as the model pollutant. Effects of both liquid and air flow rates on the phenol degradation rate were examined. The experimental results showed that the increase of liquid and air flow rates may enhance the phenol degradation rate. However, very high liquid and air flow rates could lead to the decrease in the performance of the three-phase fluidized bed photoreactor. The results on the effect of initial phenol concentration on the degradation rate indicated that the photocatalytic reaction in the three-phase fluidized bed followed the first order kinetics and could be reasonably fitted by the Langmiur-Hinshelwood kinetics model. Compared to the three-phase fluidized bed in which air is introduced into the bed from the distributor, the liquid-solids fluidized bed in which oxygen is provided by injecting air into the freeboard region of the reactor showed a better phenol destruction performance and is thus preferred for photodegradation of water contaminants.

ANNs for Identifying Shock Loads in Continuously Operated Biofilters

2012 ◽  
pp. 72-103 ◽  
Author(s):  
Eldon R. Rene ◽  
M. Estefanía López ◽  
Hung Suck Park ◽  
D. V. S. Murthy ◽  
T. Swaminathan
Keyword(s):  
Gas Flow ◽  
Theoretical Background ◽  
Shock Loads ◽  
Gas Treatment ◽  
Flow Rates ◽  
Waste Gas ◽  
Pollutant Concentrations ◽  
Industrial Complexes ◽  
Waste Gas Treatment ◽  
State Models

Among the different waste gas treatment techniques developed to eliminate odorous and toxic pollutants from air, biological techniques have emerged as an effective, reliable, eco-friendly, simple, and economical option. Biological waste gas treatment systems such as biofilters are commonly used in industrial complexes to handle emissions at high gas flow rates and low pollutant concentrations (<5 g/m3). However, from a practical view-point, variation in concentrations and gas flow rates are common to any industrial emission, and it is a pre-requisite to simulate these conditions (shock loads) at the laboratory scale. This chapter provides sufficient theoretical background information on the different waste gas treatment systems, literature review on shock loads in biofilters, and the different steady and transient state models developed in the field of biofiltration. A fundamental overview of artificial neural networks and the different steps of the modeling process are also presented.

Growth of an aerobic and an anoxic toluene-degrading biofilm - a comparative study

1995 ◽  
Vol 32 (8) ◽  
pp. 125-132 ◽  
Author(s):  
Jean-Pierre Arcangeli ◽  
Erik Arvin
Keyword(s):  
Biomass Concentration ◽  
Growth Dynamics ◽  
Biofilm Reactor ◽  
Exponential Growth Phase ◽  
Simultaneous Increase ◽  
Lag Phase ◽  
Toluene Degradation ◽  
Biofilm Growth ◽  
Anoxic Conditions ◽  
Suspended Biomass

The growth dynamics of a toluene-degrading biofilm was investigated under aerobic and under nitrate-reducing (anoxic) conditions. The study was performed with a continuously fed biofilm reactor (biodrum system). Under denitrifying conditions, the maximum toluene degradation in the reactor was achieved during the exponential growth phase of the biofilm. Under aerobic conditions, however, the maximum toluene degradation was reached during the lag phase of biofilm growth. Meanwhile, a simultaneous increase of the suspended biomass concentration in the bulk occurred concomitant with the toluene removal. The comparison of the structure of the aerobic and anoxic biofilms indicated that the anoxic biofilm was smooth and regular whereas the aerobic biofilm showed a lot of irregularity and a filamentous structure on top of the biofilm. Both the aerobic and the anoxic growth were modelled using the computer programme BIOSIM from EAWAG. The models considered active and inactive biomass. The active biomass was growing on toluene as sole carbon source, whereas the inactive biomass was composed of polymers and dead cells unable to degrade toluene. Model simulations showed that the biofilm activity was mainly concentrated in the top-layer of the biofilm under both aerobic and anoxic conditions.

Toluene removal in a biofilm reactor for waste gas treatment

1997 ◽  
Vol 36 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Anne R. Pedersen ◽  
Erik Arvin
Keyword(s):  
Mass Transfer ◽  
Gas Flow ◽  
Biofilm Reactor ◽  
Biological Degradation ◽  
Gas Treatment ◽  
Waste Gas ◽  
Filter Performance ◽  
Liquid Mass ◽  
Toluene Removal ◽  
Liquid Mass Transfer

A lab-scale trickling filter for treatment of toluene-containing waste gas was investigated. The filter performance was investigated for various loads of toluene. Two levels of the gas flow were examined, 322 m d−1 and 707 m d−1. The gas inlet concentrations were varied in the range from 0.6 to 4.0 g m−3. The toluene elimination increased linearly with increasing load, and at maximum load the elimination was 50 g m−3 h−1 (70% purification efficiency). This was in accordance with reported values for toluene removal in trickling filters. The removal was determined by the gas/liquid mass transfer and the biological degradation as well. An analytical model described the toluene removal as a half-order removal by use of two sets of parameters for the gas/liquid mass transfer and the biological degradation due to the two different gas flows. The mass transfer coefficients and the surface removal rates estimated by parameter fitting corresponded to previously observed values. The effect of the gas flow on the mass transfer coefficient and the biological removal rate may be explained by different flow patterns of the gas and the liquid phases. A characterisation of the biofilm showed an almost even biofilm growth over the filter height, which was in accordance with a constant liquid concentration throughout the column.

Treatment of Chlorobenzene-Contaminated Gas Stream in a Biotrickling Filter Inoculated with Ralstonnia pickettii L2

2014 ◽  
Vol 700 ◽  
pp. 253-256
Author(s):  
Lan Zhou ◽  
Shi Gang Su ◽  
Li Li Zhang
Keyword(s):  
Degradation Rate ◽  
Biotrickling Filter ◽  
Mass Ratio ◽  
Inlet Concentration ◽  
Waste Gas ◽  
Benzene Toluene ◽  
Metabolic Activities ◽  
Specific Degradation ◽  
Menten Kinetic ◽  
Empty Bed Residence Time

Biotrickling filter (BTF) inoculated with Ralstonniapickettii L2 was established to treat waste gas containing chlorobenzene (CB). Results revealed BTF could achieve more than 80% removal efficiency of CB under the conditions of <0.6 g·m-3inlet concentration and >30 s empty bed residence time (EBRT). The mass ratio of carbon dioxide produced to the mixture of benzene, toluene, and oxylene (BTo-X) removed was approximately 2.10, indicating that 89.5% mineralization of the incoming CB vapor. The degradation of CB in the BTF followed Michaelis-Menten kinetic model, and the maximum specific degradation rate (rmax) was 76.3g·m-3·h-1. AWCD values indicated that the microganisms in the BTF showed the high microbial metabolic activities. Real-time PCR indicated that Ralstoniapickettii L2 could still maintain its stability andactivity in the BTF under different conditions.

Anaerobic Thermophilic (55°C) Treatment of TMP Whitewater in Reactors Based on Biomass Attachment and Entrapment

1999 ◽  
Vol 40 (11-12) ◽  
pp. 67-75 ◽  
Author(s):  
Sigrun J. Jahren ◽  
Jukka A. Rintala ◽  
Hallvard Ødegaard
Keyword(s):  
Granular Sludge ◽  
Biofilm Reactor ◽  
Upflow Anaerobic Sludge Blanket ◽  
Hybrid Reactor ◽  
Anaerobic Sludge ◽  
Loading Rates ◽  
Anaerobic Reactors ◽  
Multi Stage ◽  
Degradation Rates ◽  
Thermomechanical Pulping

Thermomechanical pulping (TMP) whitewater was treated in thermophilic (55°C) anaerobic laboratory-scale reactors using three different reactor configurations. In all reactors up to 70% COD removals were achieved. The anaerobic hybrid reactor, composed of an upflow anaerobic sludge blanket (UASB) and a filter, gave degradation rates up to 10 kg COD/m3d at loading rates of 15 kg COD/m3d and hydraulic retention time (HRT) of 3.1 hours. The anaerobic multi-stage reactor, consisting of three compartments, each packed with granular sludge and carrier elements, gave degradation rates up to 9 kg COD/m3d at loading rates of 15-16 kg COD/m3d, and HRT down to 2.6 hours. Clogging and short circuiting eventually became a problem in the multi-stage reactor, probably caused by too high packing of the carriers. The anaerobic moving bed biofilm reactor performed similar to the other reactors at loading rates below 1.4 kg COD/m3d, which was the highest loading rate applied. The use of carriers in the anaerobic reactors allowed short HRT with good treatment efficiencies for TMP whitewater.

Relations between carbon removal rates, biofilm size and density of a novel anaerobic reactor: the inverse turbulent bed

2000 ◽  
Vol 41 (4-5) ◽  
pp. 253-260 ◽  
Author(s):  
P. Buffière ◽  
R. Moletta
Keyword(s):  
Removal Rate ◽  
Removal Rates ◽  
Carbon Removal ◽  
Biofilm Growth ◽  
Loading Rates ◽  
Biomass Activity ◽  
High Turbulence ◽  
The One ◽  
High Level ◽  
Very High

An anaerobic inverse turbulent bed, in which the biogas only ensures fluidisation of floating carrier particles, was investigated for carbon removal kinetics and for biofilm growth and detachment. The range of operation of the reactor was kept within 5 and 30 kgCOD· m−3· d−1, with Hydraulic Retention Times between 0.28 and 1 day. The carbon removal efficiency remained between 70 and 85%. Biofilm size were rather low (between 5 and 30 μm) while biofilm density reached very high values (over 80 kgVS· m−3). The biofilm size and density varied with increasing carbon removal rates with opposite trends; as biofilm size increases, its density decreases. On the one hand, biomass activity within the reactor was kept at a high level, (between 0.23 and 0.75 kgTOC· kgVS· d−1, i.e. between 0.6 and 1.85 kgCOD·kgVS · d−1).This result indicates that high turbulence and shear may favour growth of thin, dense and active biofilms. It is thus an interesting tool for biomass control. On the other hand, volatile solid detachment increases quasi linearly with carbon removal rate and the total amount of solid in the reactor levels off at high OLR. This means that detachment could be a limit of the process at higher organic loading rates.

scholarly journals Evaluation of a Humidified Nasal High-Flow Oxygen System, Using Oxygraphy, Capnography and Measurement of Upper Airway Pressures

2011 ◽  
Vol 39 (6) ◽  
pp. 1103-1110 ◽  
Author(s):  
J. E. Ritchie ◽  
A. B. Williams ◽  
C. Gerard ◽  
H. Hockey
Keyword(s):  
Healthy Volunteers ◽  
Airway Pressure ◽  
Gas Flow ◽  
Air Entrainment ◽  
High Flow ◽  
Positive Pressure ◽  
Mean Airway Pressure ◽  
Flow Rates ◽  
Oxygen Fraction ◽  
Airway Pressures

In this study, we evaluated the performance of a humidified nasal high-flow system (Optiflow™, Fisher and Paykel Healthcare) by measuring delivered FiO2 and airway pressures. Oxygraphy, capnography and measurement of airway pressures were performed through a hypopharyngeal catheter in healthy volunteers receiving Optiflow™ humidified nasal high flow therapy at rest and with exercise. The study was conducted in a non-clinical experimental setting. Ten healthy volunteers completed the study after giving informed written consent. Participants received a delivered oxygen fraction of 0.60 with gas flow rates of 10, 20, 30, 40 and 50 l/minute in random order. FiO2, FEO2, FECO2 and airway pressures were measured. Calculation of FiO2 from FEO2 and FECO2 was later performed. Calculated FiO2 approached 0.60 as gas flow rates increased above 30 l/minute during nose breathing at rest. High peak inspiratory flow rates with exercise were associated with increased air entrainment. Hypopharyngeal pressure increased with increasing delivered gas flow rate. At 50 l/minute the system delivered a mean airway pressure of up to 7.1 cmH2O. We believe that the high gas flow rates delivered by this system enable an accurate inspired oxygen fraction to be delivered. The positive mean airway pressure created by the high flow increases the efficacy of this system and may serve as a bridge to formal positive pressure systems.

scholarly journals Degradation of aggrecan precursors within a specialized subcompartment of the chicken chondrocyte endoplasmic reticulum

1996 ◽  
Vol 316 (2) ◽  
pp. 487-495 ◽  
Author(s):  
Manuel ALONSO ◽  
Josefina HIDALGO ◽  
Linda HENDRICKS ◽  
Angel VELASCO
Keyword(s):  
Endoplasmic Reticulum ◽  
Protease Inhibitors ◽  
Degradation Rate ◽  
Redox State ◽  
Brefeldin A ◽  
Lag Phase ◽  
Cysteine Protease Inhibitors ◽  
Immunofluorescence Analysis ◽  
Smooth Membrane ◽  
Membrane Bound

Chicken chondrocytes in culture synthesize aggrecan proteoglycan as a 370 kDa precursor that is glycosylated and secreted into the medium with a half-life of 30 min. In metabolic studies the 370 kDa precursor was shown to render a degradation intermediate of 190 kDa, which appeared with no measurable lag phase; it was dependent on temperature (> 20 °C) and inhibited by certain serine and serine/cysteine protease inhibitors such as leupeptin and PMSF. By contrast, degradation was unaffected by treatment of the cells with brefeldin A or with lysosomotropic agents. Aggrecan precursors were detected by immunofluorescence analysis within a subcompartment of the endoplasmic reticulum (ER), previously characterized as a smooth-membrane-bound subregion [Vertel, Velasco, LaFrance, Walters and Kaczman-Daniel (1989) J. Cell Biol. 109, 1827–1836]. Analysis of the subcellular fractions derived from chondrocytes indicated that the degradation intermediate was concentrated in the ER subcompartment. Degradation was dependent on the Ca2+ concentration and the redox state in the ER. Treatment of the cells with agents or conditions that alter the degradation rate of aggrecan precursors, such as protease inhibitors, decreased temperature or dithiothreitol, also modified the retention of these molecules in the ER subcompartment, as seen by immunofluorescence. These results indicate that a fraction of the 370 kDa aggrecan precursor is targeted to a smooth ER subcompartment where it undergoes degradation.

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