Biofiltration de l'air pollué par le xylène : observations expérimentales

2002 ◽  
Vol 29 (4) ◽  
pp. 543-553 ◽  
Author(s):  
Hasnaa Jorio ◽  
Guy Viel ◽  
Michèle Heitz
Keyword(s):  
Carbon Dioxide ◽  
Pressure Drop ◽  
Key Words ◽  
Removal Efficiency ◽  
Residence Time ◽  
Elimination Capacity ◽  
Nutritive Solution ◽  
Filter Bed ◽  
Empty Bed Residence Time

A new filtering material has been tested for its biofiltration performance for the treatment of air contaminated with the three isomers of xylene. The biofilter, operated at an empty bed residence time of 68 s and for xylene concentrations up to 6.7 g·m–3, allowed a xylene load and reduction of more than 92% for concentrations up to 2 g·m–3, and more than 65% for concentrations less than 6.7 g·m–3. The maximum xylene elimination capacity is of 236 g·m–3·h–1. In general, the removal efficiency of meta-xylene is the highest whereas the removal efficiency of ortho-xylene is the lowest. At high xylene concentration, the increase of biodegradation intensity leads to the accumulation of a voluminous biofilm around the filtering particles, causing the clogging of the filter bed, the progressive retention of the nutritive solution in the superior parts of the bed, and the drying of the inferior parts of the bed. These observations have showed that a biofilter operating at high elimination capacities requires a meticulous control of the humidity of the filtering bed and a regular draining of the biomass excess. Key words: biofiltration, xylene, ortho, meta, and para isomers, carbon dioxide, biofilm, pressure drop, biomass excess.[Journal translation]

Treatment of air polluted with methanol vapours in biofilters with and without percolationThis article is one of a selection of papers published in this Special Issue on Biological Air Treatment.

2009 ◽  
Vol 36 (12) ◽  
pp. 1911-1918 ◽  
Author(s):  
Antonio Avalos Ramirez ◽  
Sandrine Bénard ◽  
Anne Giroir-Fendler ◽  
J. Peter Jones ◽  
Michèle Heitz
Keyword(s):  
Carbon Dioxide ◽  
Production Rate ◽  
Removal Efficiency ◽  
Nitrogen Concentration ◽  
Carbon Dioxide Production ◽  
Elimination Capacity ◽  
Biotrickling Filter ◽  
Filter Performance ◽  
Carbon Dioxide Production Rate ◽  
Maximum Elimination Capacity

Air polluted with methanol vapours was treated in a biofilter and a biotrickling filter, both packed with inert materials. The effects of the nitrogen concentration present in the nutrient solution, the empty bed residence time, and the methanol inlet load, on the biofilter and biotrickling filter performance were all examined and compared. The elimination capacity, the biomass and the carbon dioxide production rates all increased with the increase of the parameters tested. The maximum elimination capacity for the biotrickling filter was 240 g·m–3·h–1 with corresponding removal efficiency of 75% and carbon dioxide production rate of 10 g·m–3·h–1, whereas the maximum elimination capacity for the biofilter was 80 g·m–3·h–1 with corresponding removal efficiency of 35% and carbon dioxide production rate of 70 g·m–3·h–1. The biomass production rate was similar for both the biofilter and the biotrickling filter. The carbon dioxide production rate was higher by a factor of 2 to 9 for the biofilter compared to the biotrickling filter.

Biofiltration of volatile organic compounds – application to air treatment

2000 ◽  
Vol 41 (12) ◽  
pp. 183-190 ◽  
Author(s):  
E. M. Ramirez-Lopez ◽  
A. Montillet ◽  
J. Comiti ◽  
P. Le Cloirec
Keyword(s):  
Pressure Drop ◽  
Residence Time ◽  
Structural Parameters ◽  
Packing Material ◽  
Aerobic Biodegradation ◽  
Operational Conditions ◽  
Hydrodynamic Study ◽  
Wood Bark ◽  
Qualitative Measure ◽  
Empty Bed Residence Time

A hydrodynamic study and an ethanol biodegradation were carried out in an experimental biofilter using wood bark as packing material. The Comiti and Renaud model was used in order to determine, from pressure drop measurements, the tortuosity and the dynamic specific surface area of the packing material, and its structural parameters, considering the wall effect corrections. The pressure drop was used as a qualitative measure of the growth of native wood bark microorganisms. The aerobic biodegradation with a concentration of 1 g of ethanol m–3 was studied. An air superficial velocity of 100 m h–1, an air flow rate of 20 m3 h–1 and an empty bed residence time of 37 seconds with a true residence time of 19.5 s were the operational conditions in the biofilter. The ethanol concentration, pH, temperature and the pressure drop at different heights of the biofilter were measured. Performances of this process were presented.

Study on phosphorus removal using a new coagulation system

1994 ◽  
Vol 30 (6) ◽  
pp. 257-262 ◽  
Author(s):  
Weimin Xie ◽  
Masao Kondo ◽  
Yuzuru Naito
Keyword(s):  
Pressure Drop ◽  
Removal Efficiency ◽  
Phosphorus Removal ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Coagulation System ◽  
Soluble Phosphorus ◽  
Filter Bed ◽  
Coagulation And Filtration ◽  
Removal System

In this study, the conditions for coagulation and filtration to gain high phosphorus removal efficiency were investigated with a coagulation-filtration phosphorus removal system and its practicability was confirmed. Sand of 0.6 mm in diameter, anthracite of 1.2 mm in diameter and a mixture of both were examined as a filter media, and the dual filter bed proved to be superior in the aspects of pressure drop and breakthrough. This system can be operated continuously for over 20 hours. A blocked filter bed can be recovered by backwashing. Over 80% phosphorus removal efficiency is achieved at an LV of under 5.0 m·hr−1. when the PAC dose is controlled so that the A1/P mole ratio would be 3.0 for the first period, and then subsequently around 2.0. Flocs caught in the filter further adsorb the soluble phosphorus in the wastewater, thus the chemical requirement can be reduced compared to the chemical precipitation method.

Research on CBR+PFB to Treat Domestic Wastewater

2011 ◽  
Vol 183-185 ◽  
pp. 611-615
Author(s):  
Li Sun ◽  
Jing Ping Zhu
Keyword(s):  
Removal Efficiency ◽  
Residence Time ◽  
Domestic Wastewater ◽  
Anaerobic Sludge ◽  
Hydraulic Residence Time ◽  
Combined Process ◽  
Start Up ◽  
Filter Bed

The combined process which consisted of a four-stage contact baffled reactor followed by a five-stage plant filter bed was used to treat domestic wastewater. The start-up of the four-stage contact baffled reactor was investigated, and the efficiency of the combined technology treating domestic wastewater was studied. The results indicated that the four-stage contact baffled reactor which inoculated with anaerobic sludge could be started up in 52 d, and the proper hydraulic residence time was 24 h; when the four-stage contact baffled reactor was running stably, its average CODCr removal efficiency was 57.0%, and in the four-stage contact baffled reactor, the average CODCr removal efficiency of each stage was decreased gradually, which were 45.8%, 11.1%, 6.8% and 3.3%, respectively; when the influent CODCr was 276-370 mg/L, the effluent CODCr of the combined technology was 73.0-90.7 mg/L and the average CODCr removal efficiency of the combined technology was 75.0%.

Removal of trichloroethylene and trichloroethane using a novel hollow-fibre gas-permeable membrane

2003 ◽  
Vol 3 (5-6) ◽  
pp. 67-72
Author(s):  
S. Takizawa ◽  
T. Win
Keyword(s):  
Boundary Layer ◽  
Flow Regime ◽  
Removal Efficiency ◽  
Residence Time ◽  
Flow Rate ◽  
Air Flow ◽  
Hollow Fibre ◽  
Permeation Rate ◽  
Permeable Membrane ◽  
Diffusional Boundary Layer

In order to evaluate effects of operational parameters on the removal efficiency of trichloroethylene and 1,1,1-trichloroethene from water, lab-scale experiments were conducted using a novel hollow-fibre gaspermeable membrane system, which has a very thin gas-permeable membrane held between microporous support membranes. The permeation rate of chlorinated hydrocarbons increased at higher temperature and water flow rate. On the other hand, the effects of the operational conditions in the permeate side were complex. When the permeate side was kept at low pressure without sweeping air (pervaporation), the removal efficiency of chlorinated hydrocarbon, as well as water permeation rate, was low probably due to lower level of membrane swelling on the permeate side. But when a very small amount of air was swept on the membrane (air perstripping) under a low pressure, it showed a higher efficiency than in any other conditions. Three factors affecting the permeation rate are: 1) reduction of diffusional boundary layer within the microporous support membrane, 2) air/vapour flow regime and short cutting, and 3) the extent of membrane swelling on the permeate side. A higher air flow, in general, reduces the diffusional boundary layer, but at the same time disrupts the flow regime, causes short cutting, and makes the membrane dryer. Due to these multiple effects on gas permeation, there is an optimum operational condition concerning the vacuum pressure and the air flow rate. Under the optimum operational condition, the residence time within the hollow-fibre membrane to achieve 99% removal of TCE was 5.25 minutes. The log (removal rate) was linearly correlated with the average hydraulic residence time within the membrane, and 1 mg/L of TCE can be reduced to 1 μg/L (99.9% removal).

Understanding Carbon Dioxide Transfer in Direct Methanol Fuel Cells Using a Pore-Scale Model

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Nathaniel Metzger ◽  
Archana Sekar ◽  
Jun Li ◽  
Xianglin Li
Keyword(s):  
Carbon Dioxide ◽  
Pressure Drop ◽  
Gas Flow ◽  
Direct Methanol Fuel Cells ◽  
Gas Pressure ◽  
Mass Transfer Resistance ◽  
Transfer Resistance ◽  
Cell Components ◽  
Direct Methanol ◽  
Methanol Fuel Cells

Abstract The gas flow of carbon dioxide from the catalyst layer (CL) through the microporous layer (MPL) and gas diffusion layer (GDL) has great impacts on the water and fuel management in direct methanol fuel cells (DMFCs). This work has developed a liquid–vapor two-phase model considering the counter flow of carbon dioxide gas, methanol, and water liquid solution in porous electrodes of DMFC. The model simulation includes the capillary pressure as well as the pressure drop due to flow resistance through the fuel cell components. The pressure drop of carbon dioxide flow is found to be about two to three orders of magnitude higher than the pressure drop of the liquid flow. The big difference between liquid and gas pressure drops can be explained by two reasons: volume flowrate of gas is three orders of magnitude higher than that of liquid; only a small fraction of pores (<5%) in hydrophilic fuel cell components are available for gas flow. Model results indicate that the gas pressure and the mass transfer resistance of liquid and gas are more sensitive to the pore size distribution than the thickness of porous components. To buildup high gas pressure and high mass transfer resistance of liquid, the MPL and CL should avoid micro-cracks during manufacture. Distributions of pore size and wettability of the GDL and MPL have been designed to reduce the methanol crossover and improve fuel efficiency. The model results provide design guidance to obtain superior DMFC performance using highly concentrated methanol solutions or even pure methanol.

Study of carbon dioxide condensation in chevron plate exchangers; pressure drop analysis

2012 ◽  
Vol 55 (11-12) ◽  
pp. 2916-2925 ◽  
Author(s):  
Niel Hayes ◽  
Amir Jokar ◽  
Zahid H. Ayub
Keyword(s):  
Carbon Dioxide ◽  
Pressure Drop

scholarly journals SIMULATION OF GAS DYNAMICS IN PLASMA REACTOR FOR CARBON DIOXIDE CONVERSION

2021 ◽  
pp. 131-135
Author(s):  
P.P. Platonov ◽  
S.V. Dudin ◽  
V.A. Lisovskiy
Keyword(s):  
Carbon Dioxide ◽  
Energy Efficiency ◽  
Residence Time ◽  
Plasma Reactor ◽  
Gas Injection ◽  
Navier Stokes ◽  
Carbon Dioxide Conversion ◽  
Navier Stokes Equation ◽  
Hydrodynamic Approximation ◽  
Gas Conversion

Numerical simulation of a bulk-type plasma reactor for carbon dioxide conversion with distributed gas injection and pumping has been performed in hydrodynamic approximation by solution of Navier-Stokes equation using the mathematical package COMSOL. It is shown that the geometry of gas injection and pumping, which determines the trajectories of the particles and their residence time in reactor, can significantly affect the energy efficiency of the conversion. Different particles on their way from inlet to pumping hole move along different trajectories and spend different times inside the reactor. If the residence time of the gas in the reactor is less than optimal, the gas conversion will be incomplete. If this time is more than optimal, then an excessive amount of energy will be applied to the already converted gas. It is shown that the reactor height affects significantly the energy efficiency of plasma conversion of carbon dioxide.

scholarly journals Honeycomb wet scrubber for acidic gas control: modeling and long-term test results

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Thi-Cuc Le ◽  
Gung-Hwa Hong ◽  
Guan-Yu Lin ◽  
Ziyi Li ◽  
David Y. H. Pui ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Removal Efficiency ◽  
Treatment Method ◽  
Acidic Gases ◽  
Potential Applications ◽  
Wet Scrubber ◽  
Predicted Height ◽  
Long Term Performance ◽  
Term Performance

AbstractA laboratory scale, 1.0 CMM (m3 min− 1) wet scrubber packed with water-absorbing honeycomb material (HWS) with a very large geometric surface area of 480 m2 m− 3 and a low pressure drop developed in our previous study was shown to achieve a very high removal efficiency for acidic gases but there were no long-term test data. In this study, the HWS scaled up to operate at a 100 CMM flow rate was tested for removing mixed acidic gases at a semiconductor fab for a very long period of 3.5 yr. Results showed that the removal efficiency for the mixed gases emitted from the fab always maintained as high as > 95% for HF, CH3COOH, HCl, HNO3, HNO2, and H2SO4 with the inlet concentrations ranging from supper-ppmv to sub-ppmv, during a 3.5-yr period. With water jet cleaning of the honeycomb modules once per year, the pressure drop of the HWS remained to be low at 0.5–0.8 cm H2O, indicating minimal scaling in the HWS. Additionally, the predicted height and removal efficiencies of the HWS were very close to the experimental data. The excellent long-term performance of the HWS warrants its potential applications in many areas in which liquid absorption is the preferred treatment method and the theoretical equations can facilitate the design of the HWS.

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