Remediation Technologies - Environmental Investigation and Remediation - page 324

7 Remediation Technologies
William H. DiGuiseppi
As discussed in Chapter 3, 1,4-dioxane has a low K oc (soil adsorption coefi cient for soil organic
matter) and a high solubility and is therefore not highly sorbed to soils. Because of these character-
istics, 1,4-dioxane is dominantly found in groundwater. Therefore, the following discussion of reme-
dial technologies is focused solely on groundwater remediation methods, both ex situ and in situ ,
and does not address soil remediation methods. In this chapter, we i rst describe each technology,
and then we present literature studies to demonstrate the effectiveness of the technology at
1,4-dioxane removal or destruction. The literature studies include laboratory bench-scale studies
and i eld-scale tests, documenting the removal of 1,4-dioxane from groundwater or efl uent. Finally,
we assess the technology's likelihood of success in the remediation of actual sites contaminated
with 1,4-dioxane.
Remediation technologies presented are
a. Vapor-phase transfer (e.g., air stripping)
b. Sorption
c. Natural attenuation
d. Ultraviolet photolysis
e. Phytoremediation
f. Bioremediation
g. Chemical oxidation
The assessment of treatment technologies for 1,4-dioxane presented here is comprehensive;
however, it is not intended to capture each and every study of 1,4-dioxane treatment. The selected
citations provide an assessment of the viability of a given technology to remediate groundwater
contaminated with 1,4-dioxane. Preference is given to citations that provide insight into the fate of
1,4-dioxane or the treatment mechanism.
7.1 VAPOR-PHASE TRANSFER
7.1.1 A IR S TRIPPING
Air stripping is a common method of removing volatile organic compounds (VOCs) from ground-
water because the relationship between solubility and volatility is optimal in this group of contami-
nants. This method is typically conducted in a packed tower or a low-proi le aeration system. Water
is introduced to the top of the stripper and l ows down through the system under gravity. Air is
pumped into the bottom of the stripper under pressure and exits the top. This arrangement, called
countercurrent l ow, optimizes the exchange of contaminants from water to air. Air stripping is a
nondestructive transfer of contaminants from the liquid phase to the vapor phase. The resulting
gaseous phase contaminants often require treatment. Granular activated carbon (GAC) adsorption
and thermal destruction are commonly used to treat contaminated air before it is discharged to the
atmosphere. Although 1,4-dioxane is highly volatile when in pure form, its ini nite solubility in
water is generally considered to prevent efi cient air-stripping removal from groundwater to concen-
trations suitable for discharge. Nevertheless, several studies have been performed to assess the
ability of air stripping to remove 1,4-dioxane from groundwater.
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