Mass transfer of VOCs in laboratory-scale air sparging tank

Chao, Keh-Ping; Ong, Say Kee; Huang, Mei-Chuan

doi:10.1016/j.jhazmat.2007.07.087

Cited by 36 publications

(14 citation statements)

References 21 publications

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“…Results indicated that air sparging in contaminated water can eliminate BTX compounds from 140 ppm to about 5 ppb in only 1 h of processing with a gassing rate of 0.33 VVM. This result was consistent with bibliographical searches which have clearly indicated that air sparging has become a popular tool for the remediation of contaminated water by volatile organic compounds (VOCs), particularly dissolved petroleum hydrocarbons [16,17]. This approach cannot be considered as a green technology as volatile organic compounds are only transferred from the liquid phase to the gas phase.…”

Section: Resultssupporting

confidence: 85%

BTX Removal from Polluted Water Through Bioleaching Processes

Farhadian

Duchez

Vachelard

et al. 2008

Appl Biochem Biotechnol

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In this study, benzene, toluene, and xylenes (BTX) removal from contaminated water by physical, chemical, and biological processes was studied. Results showed that air sparging in polluted water can reduce monoaromatic compounds from 140,000 to about 5 microg/l in only 1 h process with a gassing rate of 0.33 VVM. This method cannot be considered as a green technology as pollutants are only transferred from the liquid phase to the gas phase The ultimate objective of this research was thus to evaluate the efficiency of a strategy involving BTX adsorption by granular-activated charcoal (GAC) and subsequent regeneration of this support by a bioleaching process. Analysis of such processes requires the building of analytical tools able to accurately determine the contents of the contaminants in samples containing biomass to make possible the calculation of reliable material balances. Current investigation showed that BTX are readily trapped by GAC particles with low further release in the liquid medium whereas they remain at least partially available for in situ biodegradation. BTX adsorption onto the GAC was shown to reach maximum solute retention close to 350, 250, and 150 (as mg/g GAC) for xylenes, toluene, and benzene, respectively. This approach, which could afford efficient biological active carbon regeneration, is very promising for the removal of BTX compounds from water without any further environment damage.

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Section: Resultssupporting

confidence: 85%

BTX Removal from Polluted Water Through Bioleaching Processes

Farhadian

Duchez

Vachelard

et al. 2008

Appl Biochem Biotechnol

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“…According to the increase of the water table, the overall average degree of air saturation of the sand column can be calculated. It is defined as the ratio of the air volume to the total volume of the pore space in sand (Braida and Ong 2000;Chao et al 2008). …”

Section: Specimen Preparation and Test Proceduresmentioning

confidence: 99%

Laboratory Investigation of Air Flow Patterns in Saturated Sands during Air Sparging

Liu

et al. 2014

Geoenvironmental Engineering

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A series of tests were performed to investigate the air flow patterns in saturated sands during air sparging. Test results show that air flow patterns are affected by the particle size of the sand as well as air flow rate. Two types of gasphase flow patterns have been observed, namely, channel flow and bubble flow. Basically, the channel flow pattern develops when the sand particle diameter is less than 1.0 mm; whereas the bubble flow pattern occurs when the sand particle size is larger than 2.0 mm. It has been observed that a transition flow state exists when the sand particle size changes from 1.0 to 2.0 mm. The results indicate that air-phase saturation degree of the sand mass increases with the increased air flow rate. When the air flow rate exceeds a certain threshold value, the air phase saturation tends to reach a steady state. Given the other conditions remain unchanged, the air-phase saturation of the soil mass increases with the decrease of the soil particle size. A pretty good linear relationship was found between air flow rate and air pressure. Based on the extrapolation method, the minimum air injection pressure is derived, which is an important parameter in design practice. Finally, the effect of sand particle size on the estimated capillary pressure is discussed.

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“…Bioremediation technology is being further developed for a wide variety of such purposes. It is used in combination with other purifying technologies to upgrade the remediation efficiency in polluted soils or underground aquifers (Chao et al 2008). Also many petrochemical products are likewise produced to be almost sulfur-free (Javadli and Klerk 2012).…”

Section: Introductionmentioning

confidence: 99%

“…Although AS was introduced in 1985 (Chao et al 2008; Shevah and Waldman 1995), laboratory experiments at the time failed to clearly reveal the relationship between particle size and airflow, as well as the area of influence and the pattern of the saturated air within natural sediments (Peterson et al 2000, 1999). Fully understanding the pervasive airflow, which occurs during groundwater pollution remediation using IAS, is essential (Abdel-Moghny et al 2012; Koretsky et al 2006).…”

Section: Introductionmentioning

confidence: 99%

The radius of influence of a combined method of in situ air sparging and soil vapor extraction in the intertidal sediments of Gomso Bay on the west coast of South Korea

et al. 2016

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BackgroundIn situ air sparging (IAS) was undertaken at sites in the tidal flats of Mandol and Hajeon, on the west coast of South Korea, to estimate variations in the radius of influence (ROI).ResultsThe Mandol core sample consisted of sand and muddy sand 1.6–3.4 (average 2.3 ) and contained water (average 15.10 %). The Hajeon core sample consisted of muddy sand, sandy silt, and muddy sandy gravel 1.31–4.44 (average 3.11 ) and contained water (average 19.77 %). These sites differ in their sedimentary and geochemical characteristics. At the Mandol site, no H2S or combustible gas was detected during a 48-h sampling period, except for some volatile organic compounds (0.1–2.0 ppm) at the monitoring well during the initial 30 min. At the soil vapor extraction wells, CO2 and O2 varied by 850 ppm (690–1540 ppm) and 0.5 % (20.4–20.9 %), respectively. At the Hajeon site, CO2 and O2 varied from 580 to 1250 ppm and 20.6 to 20.9 %, respectively, during the 48-h sampling period.ConclusionsAt the Mandol site, an oxygen concentration of 20.6 % was assumed as the effective concentration, and the ROI was estimated to be 128.0 cm. However, at the Hajeon site the ROI was estimated to be 85.7 cm. The smaller effective ROI at the Hajeon site was likely caused by the thin aquifer and thin screens of the sparing well. This estimated ROI show that the remediation effectiveness varies greatly as a heterogeneities and anisotropies in the porous sediments. Besides, injection pressure, flow rate, pulsing or continuous mode, and the range of intrinsic permeability for most important characteristic of sediment (soil) type impacted the ROI. Therefore, the IAS method is more effective at a pervasive air flow sediments such as Mandol, which consists of sand and muddy sand than at a channelized site such as Hajeon.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-3026-3) contains supplementary material, which is available to authorized users.

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Mass transfer of VOCs in laboratory-scale air sparging tank

Cited by 36 publications

References 21 publications

BTX Removal from Polluted Water Through Bioleaching Processes

BTX Removal from Polluted Water Through Bioleaching Processes

Laboratory Investigation of Air Flow Patterns in Saturated Sands during Air Sparging

The radius of influence of a combined method of in situ air sparging and soil vapor extraction in the intertidal sediments of Gomso Bay on the west coast of South Korea

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