Page 286 - Materials Chemistry, Second Edition

7

VOC-Laden Air Treatment

7.1 Introduction
Remediation of impacted soil/groundwater often results in transfer of
organic compounds of concern (COCs) from soil/groundwater into air. The
air stream, containing organic COCs, usually needs to be treated before
being released to the atmosphere. Development and implementation of an
air emission control strategy should be an integral part of the overall reme-
diation program. Air emission control can be expensive, and it may affect the
cost-effectiveness of a specific remedial alternative.
Common sources of volatile organic compounds (VOC)-laden off-gas from
soil/groundwater remediation activities include soil vapor extraction (SVE),
low-temperature thermal desorption, soil washing, solidification/stabiliza-
tion, air sparging, biosparging, air stripping, and bioremediation. This chap-
ter covers some design calculations for commonly used off-gas treatment
technologies, including activated-carbon adsorption, direct incineration,
catalytic incineration, internal combustion (IC) engines, and biofiltration.
Much background information in this chapter is taken from three techni-
cal articles published by the US Environmental Protection Agency (USEPA)
[1–3].

7.2 Activated-Carbon Adsorption

7.2.1 Description of the Activated-Carbon Adsorption Process
Activated-carbon adsorption is one of the most commonly used air pollution
control processes for VOC emissions. The process is very effective in remov-
ing a wide range of VOCs. The most common form of vapor-phase activated
carbon is granular activated carbon (GAC).
Activated carbon has a fixed capacity or a limited number of active adsorp-
tion sites. Once the adsorbed COCs occupy most of the available sites, the
removal efficiency will drop significantly. If the operation is continued

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