ASTM F1522-95

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Designation: F 1522 – 95
Standard Guide for
Use of the Steam Stripping Process in Mitigating Chemical
Spills
This standard is issued under the fixed designation F 1522; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope constant can be estimated from vapor pressure, solubility, and
molecular weight as follows (1) :
1.1 This guide covers the considerations for the use of steam
stripping in the mitigation of spilled chemicals (including V 3 MW 3 16.03
p
HC 5 (1)
sol 3 T
hydrocarbons) dissolved in ground and surface waters. Aes-
thetic and socioeconomic factors are not considered; although,
where:
these and other factors are often important in spill response.
3 3
HC 5 Henry’s law constant (atm m water/m vapor),
1.2 This guide addresses the application of steam stripping
V 5 vapor pressure (mm Hg),
p
alone or in conjunction with other technologies.
MW 5 molecular weight (g/mole),
1.3 In making decisions with regards to discharging treated
sol 5 solubility (mg/L), and
water and operating a boiler, appropriate government authori-
T 5 temperature (K).
ties must be consulted as required by law.
2.1.5 inorganic foulants—compounds, such as those of iron,
1.4 This standard does not purport to address all of the
calcium, and manganese, which precipitate in a treatment unit,
safety concerns, if any, associated with its use. It is the
thereby reducing the throughput and efficiency of the process.
responsibility of the user of this standard to establish appro-
2.1.6 packing—is placed in a stripping column to increase
priate safety and health practices and determine the applica-
the available surface area for mass transfer.
bility of regulatory limitations prior to use. In addition, it is the
2.1.7 pH—a measure of the acidity or alkalinity represent-
responsibility of the user to ensure that such activity takes
ing the logarithm of the reciprocal of the concentration of
place under the control and direction of a qualified person with
hydrogen ions.
full knowledge of any potential or appropriate safety and health
2.1.8 purge and trap technique—uses an inert gas (such as
protocols.
helium or nitrogen) to purge the compounds into a gaseous
state.
2. Terminology
2.1.9 removal effıciency—
2.1 Definitions:
@inlet contaminant# 2 @outlet contaminant#
2.1.1 feed-to-steam ratio—ratio of feed flowrate (by
3 100 % (2)
@inlet contaminant#
weight) to steam flowrate (by weight).
2.1.10 semi-volatile organic compound—a compound that
2.1.2 foulants—substances, such as clay or silt, microbial
is amenable to analysis by extraction of the sample with an
biomass, organic solids or film, inorganics, and naturally
organic solvent. It is used synonymously with Base/Neutral/
occurring compounds, that interfere with the desired process.
Acid (BNA) compounds.
2.1.3 Henry’s law—when a liquid and a gas are in contact,
2.1.11 steam stripping—a separation process that utilizes
the weight of the gas that dissolves in a given quantity of liquid
differences in the thermodynamic properties of liquids. In this
is proportional to the pressure of the gas above the liquid. The
process, steam and organic-contaminated water are fed
law holds true only for equilibrium conditions, that is, when
counter-currently to a packed column, causing the transfer of
enough time has elapsed so that the quantity of gas dissolved
the contaminant(s) from the water phase to the vapor phase.
is no longer changing.
The driving force for the separation is the concentration
2.1.4 Henry’s law constant—a function of the compound’s
differential of the organic component(s) between the liquid and
solubility in the liquid phase and its volatility. A high Henry’s
vapor phases. Two streams are generated in this process,
law constant indicates equilibrium favoring the gas phase, that
namely: bottoms (treated effluent) and tops or overhead (con-
is, the compound is more easily stripped from water than one
centrated contaminant).
with a low Henry’s law constant. Theoretically, Henry’s law
2.1.12 equilibrium vapor pressure—the pressure at which,
at constant temperature, a pure substance’s vaporization, and
This guide is under the jurisdiction of ASTM Committee F-20 on Hazardous
Substances and Oil Spill Responseand is the direct responsibility of Subcommittee
F20.22 on Mitigation Actions.
Current edition approved May 15, 1995. Published July 1995. Originally The boldface numbers in parentheses refer to the list of references at the end of
published as F 1522 – 94. Last previous edition F 1522 – 94. this standard.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
F 1522
condensation rates are at equilibrium. 5. Constraints on Usage
2.1.13 volatile organic compound—a compound amenable
5.1 Literature searches on the predicted removal efficiencies
to analysis by the purge and trap technique. It is used
are essential prior to field scale treatment. Bench scale testing
synonymously with purgeable compounds.
should be done where complex mixtures are present or
2.1.14 volatility—the tendency of a solid or liquid material
behavior cannot be calculated by theory.
to pass into the vapor state at a given temperature.
5.2 The nature and concentration of contaminant will affect
the overall system performance. In general, organic com-
3. Factors
pounds with higher Henry’s constant are more easily stripped.
5.3 Generally, inorganic foulants, such as iron, calcium, and
3.1 Removal efficiency is highly dependent on the proper-
ties of contaminants, such as Henry’s law constant and vapor manganese, in the ppm range, reduce throughput and efficiency
of the process. This phenomenon is common in most organic
pressure, and the system operating parameters, such as tem-
perature and steam-to-water ratio. An increase in any of these treatment units regardless of the mechanism employed. Gen-
erally, pre-treatment systems involving chemical addition (that
parameters or properties produces a corresponding increase in
removal efficiency, assuming all other factors remain constant. is, pH adjustment) or membrane technology, or both, are the
most economical and effective for inorganic removal. Al-
3.2 Other factors that influence removal efficiency include
though, in some cases, the change in pH can affect the removal
the size and type of column packing and the ratio of column
efficiency.
diameter to packing diameter. In addition, the presence of
5.4 Steam stripping must be carried out under the guidance
solids will cause fouling that would reduce the throughput of
of qualified personnel that understand the contaminant, pro-
the unit and could affect organic removal efficiency.
cess, and safety and health aspects of site activities.
3.3 For compounds less volatile than water, the ability to
5.5 Steam stripping cannot remove certain compounds, such
form minimum boiling azeotropes or heteroazeotropes is
as: acetic acid, glycols (ethylene or propylene), glycerine,
considered indicative of good potential for steam stripping. In
sulfonated organics, and inorganics (except in free gaseous
these mixtures, heating a dilute solution will result in a vapor
dissolved form, such as ammonia and carbon dioxide).
phase richer in the contaminant even though the contaminant
5.6 Some phenols can be steam stripped; however, it is
has a lower vapor pressure than water. The azeotrope will
normally not cost effective due to the large amount of steam
prevent production of a pure overhead stream. Since the
required for t
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