BACKGROUND DOCUMENT FOR SOLVENTS
TO SUPPORT .4 0 CFR PART 26 8
LAND DISPOSAL RESTRICTIONS
VOLUME II
ANALYSIS OF TREATMENT AND RECYCLING TECHNOLOGIES FOR
SOLVENTS AND DETERMINATION OF BEST AVAILABLE
DEMONSTRATED TECHNOLOGIES (BDAT)
J. Winston Porter
Assistant Administrator For Solid Waste
and Emergency Response
Marcia Williams, Director
Office of Solid Waste
John P. Lehman, Director
Waste Management and Economics Division
James R. Berlow, P.E., Acting Chief
Waste Treatment Branch
Linda D. Galer
Technical Project Officer
January 1986
-------
EXECUTIVE SUMMARY
There are numerous treatment and recycling technologies that
are capable of replacing land disposal management techniques for
waste solvents. This volume of the background document identifies
those technologies and documents their demonstration status and
effectiveness. From this information, the best demonstrated
achievable technology (or technologies) for hazardous waste
solvents are determined.
The Agency has evaluated many treatment and recycling
technologies for their ability to remove, destroy, or immobilize
solvent constituents present in hazardous wastes. Recycling
methods (e.g. , reclamation and reuse) are included in this
analysis because these technologies also remove or destroy
hazardous constituents present in hazardous wastes. It has
been determined that separation and removal, destruction, and
immobilization techniques are potentially applicable to solvent
wastes. In all, the following 14 treatment and recycling
technologies are studied for their applicability to solvents:
° Separation and removal technologies
- air stripping
- stream stripping
- distillation
- carbon adsorption
- resin adsorption
- evaporation
1
-------
0 Destruction technologies
- biological degradation
- chemical oxidation
- chemical reduction
- fuel substitution
- incineration
- wet air oxidation
° Immobilization techniques
- chemical fixation/solidification
- encapsulation
Each of these technologies is discussed briefly in this
volume with an emphasis on their solvent treatment and recycling
applicability. Data demonstrating the past use of these technologies
and the performance achieved are also presented. More detailed
information regarding process design and operation is generally
available in standard engineering texts. (For instance, see
Reference 1.)
2
-------
PART A
SEPARATION AND REMOVAL TECHNOLOGIES
Many hazardous waste solvents can be removed from waste
streams by taking advantage of their volatile nature. Most
solvents have relatively low boiling points (as compared to
water); therefore, heat can be applied to a water stream, result-
ing in the volatilization of these low boiling organics.
Other separation technologies rely on sorption phenomena to
remove solvents from a waste. As a waste stream is contacted
with an adsorbent, the solvent constituents are removed by
physical and or chemical attraction at macro- and micro-pores on
the surface of the adsorbents. Each of these separation technol-
ogies is discussed below.
1. AIR STRIPPING
a. General Description
Air stripping is a unit process in which water and air are
brought into contact with each other for the purpose of transfer-
ring volatile substances from the water. In general, this treat-
ment method uses forced air to remove low concentration of
volatile organic compounds, such as solvents, from wastewater.
Air stripping also commonly used to release or strip soluble
gases (e.g., hydrogen sulfide, carbon dioxide, and ammonia) from
water. It also has been used to reduce the concentration of
taste- and odor-causing compounds. In the last several years
air stripping has been studied as a means to remove organics
from drinking water, particularly ground water.
3
-------
Air stripping is used to transfer a substance from a solution
in a liquid to solution in a gas. Transfer is caused by a
concentration gradient of the substance, which tends to move the
substance in a direction that will equalize the concentration and
destroy the gradient. The rate of mass transfer depends on
several factors defined by the following equation:
M = KLaP
where M = mass of substance transferred per unit time and volume
Kl = coefficient of mass transfer
a = effective area of transfer
P = concentration difference or driving force.
To optimize air stripping unit processes, KL and effective area
must be maximized.
The effectiveness of removing organic compounds from water
by air stripping is influenced by both operating parameters (e.g.,
contact time, ratio of air to water, and temperature) and the
physical properties of the contaminant (i.e., vapor pressure and
solubility). Although contactor design is critical to unit
process efficiency and cost, operating parameters and physical
properties can be useful for estimating the feasibility and
performance of air stripping.
Only volatile organic compounds, which have low solubility
in water and high vapor pressure, can be removed from water by
this process. The Henry's Law Constant (HLC) for a compound
gives the relative tendency for a compound to separate, or parti-
tion, between the gas and the liquid at equilibrium. Table A-l
4
-------
ranks the ease of stripping of the solvents addressed here by
their HLCs. The high HLC value indicates that a compound is
susceptable to stripping; compounds with constants above
approximately 10"^ atm-m^/mol are considered highly volatile.
Moderately volatile, slightly volatile, and nonvolatile compounds
are also indicated in the table. A thorough discussion of the
property of volatility can be found in Physical-Chemical ,Properties
and Categorization or RCRA Wastes According to Volatility (2).
Although relative removal of contaminants is related to
Henry's Law Constants, data clearly show that actual removal
efficiences are influenced by other factors. When experimental
results for contaminant removal are compared to optimum removal
curves based solely on HLCs, deviations between theoretical
and actual air-to-water ratios necessary to achieve any given
percentage of contaminant removal are several orders of magnitude
(3). These deviations are the result of operating factors listed
previously that effect the rate of transfer of the gas between
the liquid and gas phases. The operating parameters used to
maximize this transfer rate are discussed below.
The factors influencing the rate of mass transfer have a
great effect on removal by air stripping. Once the organics for
which air stripping is feasible have been determined, the rate
of mass transfer from the liquid phase to the gas phase must be
optimized in order to efficiently remove the contaminant from
solution. The rate of transfer depends on the magnitude of the
driving force: when conditions are not near equilibrium, the
5
-------
TABLE A-1
HENRY'S LAW CONSTANTS FOR SOLVENTS OF CONCERN
Henry's Law Constant (HLC)
Highly Volatile (HLOIO"^ ) at 25°C ( atn-m3/mol) 1/
1,1,2-Trichloro-l,2,2-
trifluoroethane
Trichlorofluoromethane
Te trachlor.oet hy lene
Carbon tetrachloride
Carbon disulfide
Trichloroethylene
Ethyl benzene
Toluene
o-Xylene
1,1,1-Trichloroethane
Chlorobenzene
Methylene chloride
m-Xylene
p-Xylene
1,2-Dichlorobenzene
Moderately Volatile (10~3>HLC>10~5)
8.69x10-4
1. 2 x 10 ~ 4
2.56xl0"5
2.4xl0~5
2. 4xl0~5
1.32xl0~4
1.03xl0"5
Slightly Volatile (10"5>HLC>10~7)
7.0x10"®
6. 8x10"6
2.0x10"®
l.lxlO"6
l.OxlO"6
9.5xl0-7
Nonvolatile (HLC<10~7)
Pyridine 7.0x10"^
4 . 82x10"1 y
5.83x10"2
2.87xl0"2
2.13xl0"2
1.2xl0"2
8.92xl0"3
8.7xl0"3 at 20°C V
6.64xl0-3
5.27xl0"3
4.92xl0~3
3.93xl0"3
3.19xl0"3
2.55xl0"3
2.51x10"3
1.94xl0~3
Ethyl ether
Ethyl acetate
Cyclohexanone
Methyl ethyl ketone
Nitrobenzene
Methyl isobutyl ketone
Isobutanol
n-Butyl alcohol
Acetone
o-Cresol
Methanol
m-Cresol
p-Cresol
1/ USEPA. Physical-Chemical Prope
Wastes According to Volatility.
2/ Lyman, W.J. et al^. Handbook of
Methods: Environmental Behavior
1982.
ties and Categorization of RCRA
EPA-450/3-85-007, February 1985.
Chemical Property Estimation
of Organic Compounds. McGraw-Hill,
6
-------
driving force is greater than when equilibrium is approached.
Many factors in the design of air stripping systems influence
mass transfer rate: liquid and gas flow rate, selection of packings
to optimize surface area, and transfer unit height (contact time).
Temperature also influences mass transfer rates. Lastly, the
concentration of contaminant effects transfer rates: in general,
the higher the concentration, the further the system is from equili-
brium, and the stronger the driving force. The ratio of air-to-water
is particularly important to the rate of transfer. This factor
also determines to a large degree the cost of an air stripping
sys tem.
The relationship of air-to-water ratio to removal efficiency
has been investigated. . EPA compiled experimental data on the
ratios required to remove seven volatile organic constituents
present at various influent concentrations and extrapolated from
these data to estimate air-to-water ratios required to achieve
hypothetical effluent values (Table A-2). The range of estimated
aeration requirements varies widely. The estimates illustrate,
however, that harder to remove compounds (as indicated by HLCs)
require higher air-to-water ratios than more volatile organics
to obtain the same effluent concentration. For a given contaminant
and concentration, the ratio also must be increased to achieve
a lower effluent concentration. Removal of higher influent
contaminant concentrations also requires higher ratios. Table A-3
gives experimental data from a pilot-scale facility utilizing
packed-tower aeration. The data illustrate the difference in
performance achieved as air-to-water ratio varies.
7
-------
TABLE A-2
ESTIMATED AIR-TO-WATER RATIOS NECESSARY TO ACHIEVE DESIRED TREATMENT
Effluent concentration, i.q/L
Inf. conc., 0.1 1 7 lo"
ug/l a b c a b ~_c a "b c a
Trfchldroethylene
1000
2:1
40-136:1
76:1
2:1
25-100:1
54:1
2:1
10-66:1
32:1
2:1
4-44:1
17:1
2:1
3-34:1
II
100
2:1
25-100:1
54:1
2:1
10-66:1
32:1
2:1
3-34:1
11:1
<1:1
1-10:1
1 : 1
1:)
10
2:1
10-66:1
32:1
2:1
3-34:1
11:1
.
-
.
.
.
_
.
.
1
2:1
3-34:1
11:1
-
-
-
-
-
-
-
-
-
-
-
Tetrach1oroe thy1ene
1000
1:1
25-320:1
96:1
1:1
17-150:1
72.1
<1:1
11-65:1
45.1
<1:1
8-36:1
26:1
<1:1
6-30:1
10
100
1:1
17-150:1
72:1
1:1
11-65:1
45:1
<1:1
6-30:1
18:1
<1:1
2-7:1
1:1
.
_
10
1:1
11-65:1
45:1
1:1
6-30:1
18:1
-
.
.
.
.
.
.
.
1
1:1
6-30:1
18:1
-
-
-
-
-
-
-
-
-
-
-
1, t ,1-Trichloroethane
1000
6:1
60-600 1
198:1
6:1
21-260:1
90:1
6:1
11-120:1
35:)
6:1
5-65:1
14:1
6:1
4-52:1
8
100
6:1
21-260:1
90:1
6:1
10-120:1
35:1
6:1
4-52:1
8:1
4:1
1-15:1
1:1
.
.
10
6:1
10-120:1
35:1
6:1
4-52:1
8:1
-
-
-
-
-
-
.
.
1
6:1
4-52:1
8:1
-
-
-
-
-
-
-
-
-
-
-
Carbon tetrachloride
1000
1:1
19:1
1:1
_
15:1
1:1
.
10:1
1:1
_
6:1
<1:1
.
4:
100
1:1
-
15:1
1:1
.
10:1
1:1
-
6:1
<1:1
.
1:1
_
10
1:1
-
10:1
1:1
-
6:1
-
.
-
-
-
-
.
.
1
1:1
-
6:1
-
-
-
-
-
-
-
-
-
-
Cis-l,2-0tchloroethylene
1000
4:1
14-152:1
104:1
9:1
10-115:)
77:1
4:1
8-76:1
52:1
4:1
5-50:1
34:1
4:1
438:1
26
100
4:1
10-115:1
77:1
4:1
8-76:1
52:1
4:1
4-3B:1
26:1
2:1
2-10:1
4:1
-
10
4:1
8-76:1
52:1
3:1
4-38:1
26:1
-
-
-
-
-
-
-
-
1
3:1
4-38:1
26:1
-
-
-
-
-
-
-
-
-
-
-
1,2-Dichloroethane
1000
20:1
_
56:1
20:1
.
42:1
20:1
.
28:1
20:1
_
18:1
_
14:
100
20:1
-
42:1
20:1
-
28:1
18:1
-
14:1
10:1
-
-
-
10
20:1
-
28:1
10:1
-
14:1
-
-
-
-
-
-
-
-
1
18:1
-
14:1
-
-
-
-
-
-
-
-
-
-
-
1,1-Dichloroethylene
1000
0.1:1
.
10:1
0.1:1
0:1
0.1:1
_
5:1
0.1 :
1
3:1
<0.1:1
1
3:
100
0.1.1
-
8:1
0.1:1
-
5:1
<0.1:1
-
-
-
-
-
-
-
10
0.1:1
-
5:1
*0.1:1
-
3:1
-
-
-
-
-
-
-
-
1
'0.1:1
-
3:1
-
-
-
-
-
-
-
-
-
-
-
a = Theoretical optimum air-to-water ratio based on the reciprocal of Henry's Law Constants,
b = Range of air-to-water ratios extrapolated from actual experimentation,
c = Average air-to-water ratio calculated fran "b."
Source: USEPA. Treatment of Volatile Organic Compounds in Drinking Water. EPA-600/8-83-019, May 1983.
-------
TABLE A-3
REMOVALS OF VOLATILE ORGANICS IN GROUND WATER BY
USING PILOT-SCALE PACKED. COLUMN AERATOR
Influent Concentration^/ Effluent Concentration^/
(mq/1) (mg/1)
Air-to-W&ter Ratio 8.8 52.8
Tetrahydrof uran 22.0 ND ND
1,1,1-Trichloroethane 150. 66.3 7.60
Benzene 68.8 68.8 36.0
Trichloroethylene 338. 307. 189.
Methyl isobutyl ketone 76.4 60.2 18.5
Toluene 92.0 44.8 6.60
Ethylbenzene 23.5 1.04 0.053
1/ Rounded off to three significant figures.
ND = Not Detected
Source: Stover, E.L. and D.F. Kincannon. Contaminated Groundwater Treatability
- a Case Study. Journal of the American Water Works Association,
June 1983.
9
-------
Three types of aeration devices are also used to strip volatiles
from water: mechanical surface aerators; diffused aerators;
and waterfall aerators, such as cascades, multiple trays, spray
nozzles, and packed columns. These devices are discussed below.
(1) Mechanical Surface Aerators. These types of aerators are
the simplest. Aeration is accomplished by submerged or partially
submerged impellers that agitate the water vigorously. The
turbulence entrains air in the wastewater and rapidly changes
the air-water interface to facilitate solution of the air. Air
stripping of volatiles within the water is also achieved by
the agitation and increased air-water contact. The volatiles are
usually released directly to the atmosphere.
(2) Diffused Aerators. Air stripping is accomplished in
diffused aeration by injecting air bubbles into water through
submerged diffusers or porous plates. Ideally, the process is
conducted counterflow, with the untreated water entering the
top and the treated water exiting the bottom. Exhausted air
leaves the top. Gas transfer can be improved by increasing the
basin depth, improving contact basin geometry, and using a turbine
to reduce the bubble size and increase bubble retention time.
Diffused aeration is commonly used to strip volatiles prior to
or during biological treatment processes.
(3) Waterfall Aerators. Waterfall-type equipment provides
air stripping by causing water to fall through the air and break
into small drops or thin films. Cascade, multiple tray, and
spray nozzle aerators have been used for water treatment to
remove carbon dioxide. However, packed towers are the most
10
-------
compact and achieve the greatest separation of volatile material
from the water. Packed towers (or stripping towers) provide
high void volumes and high surface areas. Water flows downward
by gravity and fans draw air up through the tower countercurrent
to the water. Sprays or distribution trays distribute the untreated
water over the packing, which consists of inert, irregular shaped
pieces that are randomly placed in the column. This design
maximizes contact of the liquid with the gas and minimizes the.
thickness of the layer of water in the packing, which promotes
mass transfer.
Typically packed towers are operated at ambient temperature.
The exhaust gas containing the organic constituents is often
vented to the atmosphere. It may also be vented to a carbon
adsorption column for removal of organics, or to an incinerator
for destruction. In other separation technologies where heat is
applied, the exhaust gas can be condensed, allowing for the
recovery and reuse of the solvent.
Waste streams containing suspended solids may interfere
with packed tower operation. As the suspended solids content
exceeds about two percent by weight, the suspended matter will
quickly accumulate in the tower and begin to plug or foul the
packing. As the pressure drop increases through the column, the
effeetivenesss at which the volatile constituents are removed is
decreased. Also, dissolved metals that will be oxidized to an
insoluble form must be removed to prevent fouling of the packed
tower.
11
-------
Each type of aerator or air stripper has advantages and
disadvantages to mass transfer. Diffused aeration provides much
less interfacial area for mass transfer but much greater liquid
contact with air, which optimized the transfer of gases into
water. Packed towers provide greater effective area but must
lower liquid volume compared with the volume of liquid film, an
optimum condition of removal of gases from water. The packed
column can more practically achieve greater air-to-water ratios
because of lower air pressure drops. Packed column aeration,
therefore, provide the optimum system for removing volatile
contaminants from water (4). In an evaluation of air stripping
data for chloroform removal by experimental systems, EPA (5)
concluded that countercurrent towers achieved best removal of
chloroform (greater than 90 percent) compared to batch diffused
air (about 5 0 percent removal).
b. Demonstration of Use to Treat Solvent Wastewaters
Air stripping is a well-understood and frequently used method
to remove volatiles from wastewaters. It is often used as a
pretreatment to biological treatment to reduce levels of toxic
volatile organics, typically solvents. The methods most often
used for this purpose are mechanical surface aeration, diffused
aeration, and spray aeration. These methods are applied to
aerated lagoons, in which both biological degradation and air
stripping is promoted through aeration over extended periods of
time. It should be noted that such treatment takes place in
basins or tanks as well as surface impoundments. Air strippinq
also occurs to some extent in activated sludge biological treatment,
12
-------
in which detention times are shorter. Because there are approxi-
mately 15,000 publicly-owned treatment works (POTWs) that operate
biological treatment facilities in the United States, and thousands
of private, industrial facilities utilize biological treatment,
it is clear that the use of air stripping as a part of these
facilities is demonstrated.
The total concentration of solvents addressed in this rulemaking
that enter surface impoundments is estimated to average approxi-
mately 3,000 mg/1, ranging from 0.00016 mg/1 to 40,000 mg/1.
Most wastewaters placed in surface impoundments are below 5,500
mg/1 (6). Based on the information gathered in the development of
effluent guidelines, it is estimated that many treatment surface
impoundments used to treat solvent-contaminated wastewaters are
aerated, and that the concentrations of solvents given here
represent the levels currently being treated at least partially
by air stripping in surface impoundments. Biological treatment
is discussed in detail later in this volume.
The use of air stripping columns, either diffused air or
packed tower, have been used principally to remove solvent
contaminants from drinking water, particularly ground water.
USEPA (7) conducted several pilot-scale diffused-air studies
on the removal of dilute solvents from ground water and spiked
tap water. McCarty (8) reported on a full-scale packed tower
air stripping unit treating several solvents present in very low
concentrations (micrograms per liter). The constituents treated
in these studies included tetrachloroethylene, trichloroethylene,
1, 2-dichloroethane, chlorobenzene, 1,1,1-trichloroeth-ane, methyl
13
-------
isobutyl ketone, toluene, and ethylbenzene. Influent concentra-
tions of individual constituents ranged from 0.0001 mg/1 to 338
mg/1. Total solvent concentrations varied from a few milligrams
per liter to approximately 800 mg/1. Air stripping has been
used recently to treat contaminated ground water at three hazardous
sites undergoing cleanup under the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) (8).
In conclusion, it appears that the use of packed tower air
stripping is demonstrated to treat a maximum of 800 mg/1 total
solvents. Simpler aeration methods, such as diffused and
mechanical surface aeration are demonstrated principally as part
of biological treatment. Aerated lagoons frequently treat much
higher concentrations of solvents,
c. Assessment of Performance
As explained above, the use of air stripping to remove
volatile solvent constituents is widely demonstrated, either
alone or in conjunction with other methods such as biological
treatment.
Data from only one full-scale packed tower facility was
available (9). This facility operates a 0.66 m^/s (15 mgd) treat-
ment plant. There are two stripping towers, each 63 m long by
19 m wide, designed to treat 0.66 raVs of flow. Each tower is
also equipped with six fans which provide 990 m-Vs of air. Data
from this facility is summarized in Table A-4. It can be seen
that even at concentrations averaging as low as 0.0001 mg/1,
removal efficiencies ranged from 60 to 94 percent. Table A-3
14
-------
TABLE A-4
REMOVALS OF VOLATILE ORGANICS IN GROUND WATER USING
A , FULL-SCALE PACKED TOWER AERATOR
Average Influent Average Effluent
Compound Concentrations Concentration Average Percent
(micrograms/1iter) (microqrams/1iter) Removal (Range)
Chlorobenzene
3.0
0.120
96(89-99)
1,2-dichlorobenzene
0.6
0.072
88(61-96)
1,3-dichlorobnezene
0.1
0.083
83(60-93)
1,4-dichlorobenzene
1.0
0.030
97(88-99)
1.3
0.100
92(89-94)
Tetrachloroethylene
2.5
0.125
95(88-98)
1,1,1-Trichloroethane
4.7
0.423
91(76-96)
Source: McCarty, P.L. Organics in Water - an Engineering Challenge. Journal
of the Environmental Engineering Division. Proceedings of the
American Society of Civil Engineering. 106, #EE1, February 1980.
15
-------
discussed earlier gives data from a pilot-scale study using
a 7.9 x 122 cm glass stripping column. Even using an air-to-water
ratio of 53:1, effluent values for individual constituents
ranged from 7.60 to 189 mg/1.
Data from two other pilot-scale facilities are given in
Table A-5. This facility achieved nondetectable levels in the
effluent for several solvents using an air-to-water ratio of 8:1
or better; influent values were only 0.003 to 1 mg/1. A diffused
aerator was used consisting of a 4-cm (1.5 in) diameter glass
column, 1.2 m (4 ft) long.
These results indicate that even at high air-to-water ratios,
air stripping may not achieve very low concentrations of volatile
solvent present above 5 mg/1. However, air stripping may be useful
in treating volatiles present at low concentrations, or in
treating higher concentrations of volatiles prior to further
treatment, such as biological treatment.
2. STEAM STRIPPING
a. General Description
As in air stripping, steam stripping makes use of the higher
volatility of solvents compared to water and other waste constit-
uents. Volatility or vapor pressure of organics increases with
increasing temperature; thus, the application of heat in the form
of steam increases the rate and effectiveness of organics removal
as compared to air stripping. Solvents of relatively lower
volatility may also be removed when steam is used as the stripping
agent.
16
-------
TABI" * -5
REMOVAL OF VOLATILE ORGANIC COMPOUNDS FROM DRINKING WATER BY DIFFUSED-AIR AERATION1/
Location of Study
Compound
Average
Influent
Concentration
(microqrams/1i ter)
Average Effluent Concentration
at Various Air-to-Water Ratios2/
(mi croqrams/1 i ter)
Remarks
1:1
2:1
3:1
4:1
8:1
16:1
20:1
The tap waiter was
Site 1
Tetrachloro-
1025
698
416
304
156
16
spiked with these
ethylene
636
161
177
46
34
8
<1
<1
solvents.
338
139
103
47
34
4
1
2
114
32
17
7
4
<1
<1
<1
107
32
17
7
4
<1
<1
<1
17
3
2
1
1
<1
<1
<1
Trichloro-
1064
796
614
508
319
53
ethylene
397
223
273
102
82
22
<1
<1
241
136
110
61
53
8
2
3
110
40
28
18
9
3
<1
<1
73
22
14
8
6
1
<1
<1
Site 2
Tetrachloro-
94
9
The ground water
ethylene
was contaminated
by industrial
discharge.
Trichloro-
3
0.4
The pilot-scale
ethylene
column was run
continuously for
1,1,1-Trichloro-
237
23
over one year.
ethane
cis-1,2-Dichloro-
0.5
<0.1
ethylene
1,2-Dichloro-
1.4
ethane
0.8
1/ All studies used a 4-cm (1.5-in.) diameter glass column, a 10-min contact time, and a water depth of 0.8 m.
2/ Blank spaces indicate no tests were conducted.
Source: Love, O.T. and R.G. Eilers. Treatment of Drinking Water Containing Trichloroethylene and Related Industrial
-------
The principal index used to establish steam stripping
feasibility for a specific compound is boiling point, which is a
function of vapor pressure. Organic compounds with boiling points
less than 150°C have good steam stripping potential. As discussed
earlier, Henry's Law Constants are also good indicators of
volatility. Compounds with the ability to form azeotropes with
water at a weight fraction of greater than or equal to 0.8 also
are good candidates. (Azeotropes are mixtures that distill
without a change in composition, i.e., the liquid and vapor
phases of the compound have the same relative weights of the mixed
compounds.) The degree of ionic dissociation of the contaminents
also affects the ease with which they can be stripped, although
this is generally not a factor in stripping organic compounds.
The same operating and design factors that affect air
stripping performance also influence the performance of steam
stripping. Steam-to-water ratio, surface area, contact time, and
solute concentration all affect the ease with which a compound
can be stripped.
Steam stripping is normally performed in a cylindrical shell
(stripping tower) containing packing or a series of perforated
plates to allow efficient contact between the steam and the
aqueous liquid containing volatile solutes. Steam is injected
into the bottom of the stripping tower, and preheated liquid
waste enters near the top. As the steam vapor passes up through
the tower, it provides heat, increasing the vapor pressure of the
solute and driving the solute out of solution. The volatile
components from the liquid are carried out of the top- of the
tower along with the steam.
18
-------
This overhead stream, containing the steam and volatile
organics, is condensed to a liquid form. The treated aqueous
liquid is removed from the bottom of the stripping tower. The
treated aqueous liquid and the condensed overhead stream
constitute two separate residuals from steam stripping.
Wastes containing high concentrations of suspended solids
(two percent or greater by weight) or of materials that tend to
polymerize, such as cresols and pyridines, may interfere with the
operation of a packed tower. Such materials cause fouling of the
packing material and eventual plugging of equipment,
b• Demonstration of Use to Treat Solvents
The use of steam stripping to remove solvents is a widely
recognized manufacturing process and waste treatment technology
for the separation of solvents from water. Recent data indicate
that there are currently approximately 27 industrial- steam stripping
wastewater treatment units, both commercial and private. Four
full-scale facilities were sampled recently during the development
of the reproposal of effluent limitations for the organic chemical,
plastics, and synthetic fibers (OCPSF) industries (10). Several
additional full-scale facilities were tested previously as part of
this program. EPA also has identified one facility in the pharma-
ceutical industry that operates eight full-scale packed tower
steam strippers (11). At least 11 full-scale strippers were
documented in use by pesticides manufacturers (12). Pilot-scale
facilities have been used to remove solvents from contaminated
ground water.
19
-------
Steam stripping has been used to treat carbon tetrachloride,
methylene chloride, nitrobenzene, toluene, and trichloroethylene (10);
chlorobenzene, 1,2-dichlorobenzene, tetrachloroethylene, and
1,1,1-trichloroethane (9); isobutyl alcohol, methanol, and xylene (12);
o-cresol, m-cresol, ethylbenzene, and methyl isobutyl ketone (7);
and acetone (13).
c. Assessment of Performance
Table A-6 summarizes the data available for the solvents being
addressed here. These data were screened to exclude influent values
below the screening levels proposed in this rulemaking. As this
table illustrates, data show that very low levels can be achieved
for six solvents of concern: ethylbenzene, methyl isobutyl
ketone, methylene chloride, toluene, 1,1,1-trichloroethane, and
trichloroethylene. The performance data considered includes only
data for the treatment of wastewaters containing these solvents
in concentrations that exceed the proposed screening levels.
In order to evaluate the reasonableness of the performance
indicated in Table A-6, data for additional volatile organic
compounds was evaluated. Table A-7, gives performance data for
these additional compounds. For the analysis of OCPSF data, all
influent values were included. Samples for which the constituent
was not detected were assumed to contain the compound at the nominal
detection limit. In addition, not all influent values for these
additional solvents had corresponding effluent values taken. The
Henry's Law Constants of these constituents and of the five
solvents also were used to provide a basis for comparing the
20
-------
TABLE A-6
STEAM STRIPPING SUMMARY OF DATA FOR SOLVENTS OF CONCERN
(mg/1)
Average Influent Average Effluent
Concentration Concentration
Compound (Range) (Range)
Ethylbenzene
Methylene chloride
Methyl isobutyl ketone
Toluene
1,1,1-Trichloroethane
23. 5
<159.
5.13 (1.76-12.1)
1.97 (1.29-5.10)
Mean
76.4
92.0
150.
0.200(<0.010-0.992)V
<0.010 (NA)^/
0.010 (0.010-<0.010)3/
0.308 (0.010-1.12)3/-
0.109
<0.010 (<0.010-<0.010)
0.036 (<0.010-1.26)V
0.457 (<0.010-2.14)!/
Trichloroethylene 3.05 (0.210-10.3) 0.019 ( <0. 010-0.085)3/
1/ Pilot-scale continuous flow packed column. Countercurrent
steam/air flow. 7.9x122 cm (3 1/8 x 48 in.) glass stripping
tower packed with 66-cm (26 in) of 7-mm glass Raschig rings.
(Stover, E.L. and D.F. Kincannon. Contaminated Groundwater.
Treatability-a Case Study. Journal American Waterworks
Association, June, 1983.
2/ Full-scale packed tower. 0.0165 MGD; 15 feet of packing; 8,000
lb/hr wastewater; 1,860 lb/hr steam. USEPA. Development
Document for Expanded Best Practicable Control Technology, Best
Conventional Pollutant Control Technology, Best Available
Technology, New Source Performance Technology, and Pretreatment
Technology in the Pesticides Chemical Industry. PB83-153171.
Office of Water Regulations and Standards, November 1982.
2/ Office of Solid Waste. Analysis of Organic Chemicals, Plastics,
and Synthetic Fibers (OCPSF) Industries Database.
21
-------
TABLE A-7
STEAM STRIPPING PERFORMANCE FOR ADDITIONAL SOLVENTS
Henry's Law Constant Average Influent Average Effluent
at 25°C Concentration (mg/1) Concentration (mg/1)
Compound (atm-m3/mole) (Range) (Range)
1.1-Dichloroethylene 1.5 x 1(T2 4.36 (0.200-10.8) <0.010 (<0.010- 0.013)V
Chloroethane 1.5 x 10-2 at 20°c£/ 20.4 (0.690-42.0) <0.010 (<0.010- 0.010)V
Benzene 5.5 x 10"3 820. (0.239-2,010) 0.045 (<0.010- 0.171)V
92.2 (34.7-147) <0.010 (<0.010 -0.010)V
Mean 0.027
1.2-trans-Dichloro- 5.32xlO"3 13.7 (4.86-43.0) <0.014 (<0.010- 0.057)2/
ethylene
Chloroform 3.39xl0-3 399. (7.33 - 1,090) <0.010 (<0.010- 0.016)£/
1,1,2-Trichloroethane 1.18xl0-3 6.81 (0.220-14.5) <0.010 (<0.010- 0.010)V
1,2-trans-Dichloro- l.lOxlO-3 9,610. (2,340-2,350) 0.056 (<0.010- 0.374)V
ethane
Tetrahydrofuran 1.08x10"^ 22.0 <0.010 (<0.010- 0.010)4/
1/ USEPA. Physical-Chemical Properties and Categorization of RCRA Wastes
According to Volatility. EPA-450/3-85-007, February 1985.
2/ McCarty, P.L. Organics in Water-an Engineering Challenge. Journal of
Engineering Division, 106, EEl, February 1980.
V Office of Solid Waste Analysis of Organic Chemicals, Plastics, and Synthetic
Fibers (OCPSF) Industries database.
4/ Pilot-scale continuous flow packed column. Countercurrent steam/air flow.
7.9x122 cm (3 1/8 x 48 in.) glass stripping tower packed with 66-cm (26 in.)
of 7-rrcn glass Rasching rings. (Stover, E.L. and D.F. Kincannon. Contaminated
Groundwater Treatability - a Case Study. Journal American Water Wbrks Association,
June 1983.)
NA = Not Available
22
-------
TABLE A-8
STEAM STRIPPING PERFORMANCE AND THEORETICAL EASE OF STRIPPING
Constituent
Henry's Law Constant
at 25°C (atm-m^/mole)
Average Level
Achieved(mg/1)
1,1,2-trichloro-l,2,2-
4.82xl0_1
trifluoroethane*
Trichlorofluoromethane*
5.8xl0-2
Tetrachloroethylene*
2.87xl0-2
Carbon tetrachloride*
2.13x10-2
1,1-Dichloroethylene
1.5xl0-2
<0.010
Chloroethane
1.5x10-2 at 20°C
<0.010
Carbon disulfide*
1.2x10-2
Tr ichlo roe thy lene*
8.92xl0-3
0.019
Ethylbenzene*
8.7xl0-3 at 20°C
0. 200
1,1, 2-Trichloroethane*
7.8xl0"3
<0.010
Toluene*
6.64x10-3
0.036
Be nze ne
5.5x10-3
0.027
1,2-trans-Dichloro-
5.3x10-3
<0.010
ethylene
o-Xylene*
5.27xl0-3
1,1,1-Trichloroethane*
4.92x10-3
0. 457
Chlorobenzene*
3.93x10-3
<0.010
Chloroform
3.39x10-3
<0.010
Methylene chloride*
3.19x10-3
<0.010
m-Xylene*
2.55x10-3
p-Xylene*
2.51x10-3
1,2-Dichlorobenzene*
1.94x10-3
1,1, 2-Trichloroethane
1.18x10-3
<0.010
1,2-Dichloroethane
l.lOxlO"3
0. 051
Tetrahydrofuran
1.08xl0"4
<0.010
Methyl isobutyl ketone*
5.41xl0-5
<0.010
* Appendix VII solvents listed under F001 through F005.
23
-------
data. Table A-8 presents the available data from Tables A-6 and
A-7, and the HLC's for all of the solvents of concern. It is
clear from Table A-8 that the performance indicated for the five
solvents of concern is consistant with additional data for solvents
of lower or similar HCLs.
Table A-8 also illustrates that many other solvents addressed
in this rule should be amenable to steam stripping. These solvents
are: carbon disulfide, carbon tetrachloride, chlorobenzene,
1,2-dichlorobenzene, tetrachloroethylene, 1,1,2-trichloro-
1,2,2-trifluoroethane, trichlorofluoromethane, and xylene. In
particular, 1,1,2-trichloro-1,2,2-trifluoroethane and trichloro-
fluoromethane are highly volatile, and should be easily steam
stripped if present in concentrations amenable to steam stripping.
The lack of data pertaining to these solvents is due in part to
the fact that several of them are not priority pollutants under
the Clean Water Act, and usually were not analyzed during the
development of effluent limitations.
Steam stripping has also been applied to some solvents that
are rated as moderately volatile and slightly volatile (see Table
A-l). Data in Table A-6 from a pilot-scale facility shows removal
to nondetectable levels of methyl isobutyl ketone (MEK) present
at 76.4 mg/1 in ground, water containing over 770 mg/1 of total
organic constituents. Steam stripping data also are available
for acetone, isobutyl alcohol, methanol, methyl ethyl ketone, and
nitrobenzene. In many cases, significant amounts of these
substances, particularly nitrobenzene, have been recovered and
reused. However, with the exception of MEK, no data demonstrate
24
-------
that wastewaters containing moderately or slightly volatile
solvents can be treated to levels as low as those achieved for
volatile compounds. Conceivably, given high temperatures and
long retention times, the moderately and slightly volatile
constituents can be steam stripped to lower levels than are
documented. Furthermore, steam stripping is frequently used as a
pretreatment for such compounds in order to reduce their
concentrations sufficiently to treat by carbon adsorption and/or
biological degradation.
3. DISTILLATION
a. General Description
Distillation is a method used to separate components of a liquid
mixture by partially vaporizing the mixture and separately
recovering the vapor and the remaining liquid. This method is
normally used to reclaim solvents from wastes containing high
concentrations of solvents and low levels of solids, often leaving
behind a sludge (still bottoms).
The process takes advantage of the fact that the vapor above
a liquid mixture has a different composition from the mixture
itself. The composition of the vapor depends on the vapor
pressures of the mixture components. In general, the vapor will
contain greater concentrations of the components with higher
vapor pressures than does the liquid. As a result, the vapor can
be removed from the system and condensed to produce a mixture
with higher concentrations of the more volatile components than
were present in the original mixture.
25
-------
The most common types of distillation processes are batch
distillation and fractional distillation. Batch distillation
consists of a single vapor-liquid equilibrium stage. The liquid
to be distilled is charged into a closed vessel (still) equipped
with a steam jacket or a heating coil. The liquid is boiled and
the vapor (or overhead) is driven off, condensed, and collected
until the desired compositions are.reached in the overhead and in
the remaining liquid or sludge (bottoms).
Fractional distillation is carried out in a column containing
perforated trays or packing so as to provide more than one vapor-
liquid equilibrium stage. Numerous equilibrium stages provide
additional vapor-liquid contact. A steady feed stream enters the
column, and overhead vapors and bottoms are continuously withdrawn.
When aqueous wastes containing volatile solvents are distilled,
a disproportional amount of solvent is vaporized and thus the
overhead vapors contain a much higher concentration of the solvent
than was present in the original mixture. These overhead vapors
are condensed to yield a liquid mixture with relatively high
solvent content. This "reclaimed solvent" can often be reused
with little or no further treatment. In such cases, the still
bottoms typically contain low concentrations of solvent (at least
one percent and more typically 10 percent). Still bottoms also
contain the less volatile organics, as well as oil and grease,
that were present in the original mixture.
When the solvent of concern is one of the less volatile
components of a mixture, some or all of the solvent will remain
in the liquid phase and thus be concentrated in the still bottoms.
26
-------
In such cases, the still bottoms may contain a greater concentration
of solvent than the original mixture did. More detailed information
on the characteristics of still bottoms is given later in the
discussion of distillation performance.
In both cases two residuals are generated by distillation:
an overhead stream and still bottoms. The solvent of concern has
been concentrated in one of these residuals, while its concentration
has been proportionally lowered in the other. Thus distillation
is actually a waste minimization or concentration step. Further
treatment or reuse of the resulting residuals is required.
Although wastes containing any amount of solvent can
theoretically be distilled, currently it is economically attractive
as a method of solvent recovery when the waste contains greater
than 50 percent solvent (13).
In order for distillation to be practical, the boiling points
of the mixture components must be separated by 20°C to 30°C,
depending on the size of the column and on the packing material
(14). Substances with low boiling points are more economical to
distill because less heat is required. The volatility of each
component to be separated must be different, as distillation
separates components based on the differences in their volatility.
Wastes containing concentrations of suspended solids greater
than ten percent by weight (14), or significant amounts of materials
that tend to polymerize, such as cresols and pyridines, may
interfere with the operation of a packed distillation tower.
Such materials cause fouling of the packing material and eventual
plugging of equipment.
27
-------
Such waste streams can be pretreated to remove the suspended
solids so that they do not interfere with the distillation unit.
Simple settling and skimming may be applied to those waste streams
containing greater than 10 percent solids. Additional treatment
through filtration may be applied to further reduce the solids
loading when the solids content, is less than 10 percent (14).
A scraped-surface separator may also be used to remove low
levels of solids (less than 10 percent) from a solvent waste
stream. The scraped-surface separator consists of a heated,
agitated vessel. The agitation is sufficient to promote heat
transfer while still permitting the solids to settle. Solvent
vapor is drawn from the top of the vessel, and sludge is removed
frcm the bottom. The overhead stream from the separator may then
go on to further purification using conventional distillation
techniques.
b. Demonstration of Use to Treat Solvents
Distillation for solvent reclamation is a widely demonstrated
technology throughout the United States. In 1978, it was reported
that over 4,000 facilities were involved in some sort of solvent
recycling activities (14). Additional data gathered for the
Agency indicate that 43 commercial facilities belong to the
National Association of Solvent Recyclers, or NASR (14). The
NASR claims to represent 70 percent of the nationwide off-site
recycling capacity for solvents.
A telephone survey of the NASR members was performed to
identify, among other things, the volumes and types of solvents
processed by "F" hazardous waste code. A summary of -this infor-
28
-------
TABLE A-9
VOLUME OF SOLVENTS COMMERCIALLY RECYCLED
(THOUSAND GALLONS PER YEAR)
Facility
Number
Solvent Input
F001
F002
F004
F005
Other
0101
71
29
0201
3, 145
1 ,275
-
-
2,560
0202
122
795
795
795
0203
—
106
25
-
4,000
0204
200
—
-
-
-
0301
187
79
-
67
112
0302
127
1,138
-
539
1 ,805
0303
12
12
-
220
306
0304
38
38
-
276
276
0401
360
360
—
841
841
0402
84
12
—
72
72
0403
-
-
-
-
4,000
0404
661
661
-
1,223
1 ,223
0501
—
-
-
42
295
0502
1 12
112
-
1,011
1,011
0503
37
37
—
1,441
480
0504
229
25
0
587
840
0505
337
-
—
1,997
331
0506
68
23
—
68
68
0507
46
4
-
2,251
2,251
0508
79
79
—
603
3,774
0509
79
—
—
314
393
0510
166
166
166
166
166
0511
106
25
—
4,000
0601
—
—
12
16
0602
96
96
—
96
191
0603
—
—
—
-
4,000
0901
399
250
25
25
300
0902
106
25
-
4,000
1001
544
60
—
379
528
1002
27
27
-
154
154
Source: Engineering-Science. Supplemental Report on the Tech-
nological Assessment of Treatment Alternatives for
Waste Solvents. Prepared for the U.S. EPA, Office of
Solid Waste, 1985.
29
-------
mation is presented in Table A-9. In the NASR survey, 31 members
provided data indicating that these 31 facilities had a combined
production input of 65 million gallons. When these data are
extrapolated to a nationwide total, an estimated 149 million
gallons of solvent wastes are recycled domestically each year.
Additional data gathered during a survey of small quantity
generators indicate that they recycled 18 million gallons of
solvent wastes annually, primarily by distillation (15).
As can be seen in Table A-9, solvent recycling is routinely
demonstrated for wastes codes F001, F002, F004, F005, and other
mixed wastes. It follows that off-specification solvent products
i.e., those with individual U and P constituent codes, which are
generally more concentrated in solvents, can also be recovered
through distillation.
The telephone survey did not inquire about hazardous waste
code F003, which includes many ignitable solvents. Nevertheless,
the Agency has further information that F003 constituents are
recoverable through distillation. For example, one commercial
facility reports the processing of waste streams to recover the
following F003 constituents: xylene, acetone, ethyl acetate,
methyl isobutyl ketone (MIBK), n-butyl alcohol, eyelohexanone
and methanol (16). Table A-10 lists 19 solvent consituents
addressed in this rulemaking that are present in waste solvents
that were generated by the chemical manufacturing industry and
that underwent distillation. The mean concentration of solvent
constituents present in the waste are also presented. At the
30
-------
TABLE A-10
MEAN SOLVENT CONCENTRATIONS
OF DISTILLATION RESIDUES
(Percent)
Heavy Ends
Number of Mean
Constituent Reported Values Concentration
carbon disulfide
4
53
methyl isobutyl ketone
2
30
toluene
32
27
acetone
9
25
n-butyl alcohol
12
23
isobutanol
5
22
ethyl acetate
4
18
xylene
7
13
ethylbenzene(s)
14
11
chlorobenzene
17
11
methanol
14
11
tetrachloroethylene
26
8
methylene chloride
14
6
carbon tetrachloride
19
6
trichloroethylene
22
4
1,2-dichlorobenzene
8
2
cyclohexanone
6
1
1,1,1-trichloroethane
12
0.3
trichlorofluoromethane
2
_
Distillation Residues
Number of Mean
Reported Values Concentration
1
30
23
30
6
23
8
22
4
20
3
22
5
10
6
15
14
10
8
3
12
4
9
0.2
8
5
14
4
6
3
4
3
2
Source: Science Applications International Corporation. Industry Studies Data Base.
Prepared for the U.S. EPA, Office of Solid Waste. 1985.
-------
lower concentrations, it is likely that the waste stream is being
reclaimed for other: constituents that are present at much higher
concentrat ions.
c. Assessment of Performance
As stated previously, distillation for solvent recovery and
reuse is actually a waste concentration step. It produces a
product and a residual, which still can contain high concentra-
tions of solvents. Data received by the Agency demonstrate, as
expected, that the solvent concentration in the recovered solvent
is increased through the use of distillation. A summary of these
data is presented in Table A-ll for the solvents methylene chloride,
trichloroethylene, and 1,1,1-trichloroethane. Also presented in
the table are similar data for paint thinner and an ink wash
sample. The data demonstrate that distillation increases the
solvent concentration in the spent solvent stream to 90 percent
or greater, thus allowing its reuse. The residual stream from
distillation is routed to other treatment or disposal methods,
such as incineration, or i t may be used as a fuel substitute in a
high-energy industrial application.
Quite frequently, residuals from distillation are the bottoms
stream (or nonvolatile material) removed from the distillation
unit. Table A-10 presents data demonstrating that still bottoms
may contain significant quantities of solvents. Depending on the
constituent, the mean solvent concentration in still bottoms is
reported to be above one percent. For many constituents, the
mean concentration is above 10 percent and ranges up to 50 percent.
Reportedly the solvent concentration in the still bottoms is
32
-------
TABLE A-11
EXAMPLES OF SOLVENT CONCENTRATIONS BEFORE AND AFTER DISTILLATION
Percent in Percent in
Original Recovered
Sample/Constituent Waste Stream Solvent
Spent methylene chloride
Methylene chloride 70.1 98.7
Isopropanol 0.3 0.4
Methyl ethyl ketone 0.3 0.4
Toluene 0.1 0.2
Other trace organics 0.2 0.3
Non-distillable constituents 29.0
TOTAL 100.0 100.0
Spent trichloroethylene
Trichloroethylene 58.3 97.1
Toluene 0.2 0.4
Perchloroethylene 0.2 0.4
Ethanol 0,2 0.3
Ethyl acetate 0.2 0.3
Other trace organics 0.9 1.5
Non-distillable constituents 40.0
TOTAL 100.0 100.0
Spent 1,1,1-trichloroethane
1,1,1-Trichloroethane 66.0 91.7
Trichloroethylene 5.3 7.3
2-Butanol 0.2 0.3
Xylene 0.1 0.2
Other trace organics 0.4 0.5
Non-distillable constituents 28.0
TOTAL 100.0 100.0
continued
33
-------
TABLE A-11 (Continued)
EXAMPLES OF SOLVENT CONCENTRATIONS BEFORE AND AFTER DISTILLATION
Percent in Percent in
Original Recovered
Sample/Constituent Waste Stream Solvent
Spent paint thinner
Toluene 9.4 15.4
Isopropyl acetate 9.1 14.9
Ethanol 6.9 11.4
Methyl ethyl ketone . 6.8 11.1
Acetone 3.8 6.3
Isopropanol 3.1 5.2
Butyl acetate 2.4 4.0
Methanol 3.0 4.9
Ethyl acetate 3.0 4.9
Xylene 1 2.8 4.6
Cellosolve acetate 1.6 2.6
1-Propanol 1.2 1.9
Ethylbenzene 1.2 1.9
Methyl isobutyl ketone 0.7 1.2
Other trace organics 2.9 9.7
Non-distillable constituents 42.1
TOTAL 100.0 00.0
Ink wash
Ethyl acetate 30.0 44.8
Ethanol 21.5 31.6
Propyl acetate 8.1 11.9
Methanol 2.1 3.1
Isopropyl acetate 1.7 2.5
Isopropanol 1.4 2.1
Other trace organics 3.2 4.0
Non-distillable constituents 32.0 _==
TOTAL 100.0 100.0.
1
Ethylene glycol monoethyl ether acetate.
Source: Chemical Waste Management. Hazardous Waste Treatment
Workshop #3: Treatment and Recovery of Iqnitables.
Solvents, and Solvent-Bearing Wastes. April 9, 1984.
34
-------
often intentionally maintained at a high level to prevent fouling
of heat exchange equipment. Impurities that tend to foul the
equipment are soluble in the solvent. By maintaining a high
level of solvent in the bottoms stream, these impurities are kept
in solution and equipment fouling is avoided (14).
In summary, distillation is a recycling method that is well-
demonstrated on most of the solvents addressed, in this rulemaking.
The residuals (i.e. still bottoms and reclaimed solvent) generated
by distillation still contain high concentrations of solvents. The
still bottoms, require further treatment or reuse, most likely by
incineration or fuel substitution. Based on available data
distillation alone does not appear to achieve low levels
solvents in the waste residual. Therefore, distillation
is not considered BDAT for any solvent waste.
4. CARBON ADSORPTION
a. General Description
Carbon adsorption uses any amorphous form of carbon
been specially treated (activated) to increase the ratio
surface area to volume of carbon. The separation process relj.es
on the physical or chemical attraction between the solute molecules
and the surface of the carbon.
Aqueous liquids are treated by contacting them with the
activated carbon in a tank or column and allowing sufficient time
for the solute molecules to be adsorbed onto the carbon surface.
In powdered activated carbon (PAC) treatment, loose granules of
carbon are mixed with the waste as a slurry and removed by gravity
settling. In flow-through columns, the stream flows continuously
of
alone
that has
of
35
-------
through a granular activated carbon (GAC) column in either an
upward or downward direction.
When effluent quality approaches a predetermined level, the
carbon can be regenerated to remove the solute, which may be
reused or destroyed in an incinerator. The most common form of
regeneration is thermal regeneration carried out in a multiple
hearth furnace or a rotary kiln at temperatures approaching
1,000°C. With proper control, the carbon can be returned to its
original activity with losses of less than 10 percent. Fresh
carbon is added to replace that which is lost. Chemicals (such
as alkali and acids), hot water, or steam can be used for
nondestructive carbon regeneration. If nondestructive methods
are used, the solute may be recovered for reuse. The residues
from carbon adsorption include spent carbon and treated aqueous
liquid. the exhausted carbon may also be directly destroyed by
incinerat ion.
Carbon adsorption is applicable to single-phase fluid streams,
including aqueous liquid solutions, containing low concentrations
of organic contaminant (up to 5 weight percent) and inorganic
contaminants (up to 0.1 weight percent) (17). It is also applicable
to organic liquid solutions, although it is less likely that the
desired constituent will be removed from an organic solvent to
the carbon surface.
Many waste contaminants can interfere with carbon adsorption.
If calcium or magnesium are present in concentrations greater
than 500 mg/1, these constituents may precipitate out and plug or
foul the column (18). Oil and grease in excess of 200 mg/1, and
36
-------
suspended solids present at levels greater than 100 mg/1, also
interfere with column operation (18). Lead and mercury are of
concern because they may compete for adsorption sites, and they
are difficult to remove from the carbon during the regeneration
cycle (19). The presence of chlorine has also been found to
influence adsorption of organic compounds (20).
Both GAC columns and PAC are often used in conjunction with
other treatment processes. Carbon adsorption may be used as a
pretreatment to conventional biological treatment. Although
this may lead to higher loadings on the carbon in a column, its
use prior to combining wastewaters may result in fewer competing
constituents in the feed to the adsorption column. Less competi-
tion for adsorption sites on the carbon may facilitate solute
removal. More frequently GAC columns are used as a polishing
step for effluent from biological treatment for removal of compounds
that are resistant to biodegradation. In this capacity, it is
generally used for high volume wastewaters which contain dilute
organic constituents. PAC is also used concurrently with biological
treatment to enhance organic removal in the biological treatment
process.
The adsorbability of specific compounds from pure-solute
solution by activated carbon can be classified to a limited
extent. In general, two properties of organics that influence
adsorption by activated carbon are solubility and carbon affinity.
Generally, less soluble organic materials are better adsorbed, as
well as those that have a greater molecular attraction to the
carbon surface. Several factors decrease the solubility of
-------
organics and, as a result# increase adsorption: high molecular
weight, low polarity, low ionic character, low pH for organic
acids or high pH for organic bases, and aromatic structure. In
general, molecules of higher molecular weights are attracted more
strongly to carbon than are molecules of lower molecular weights.
Pesticides and polychlorinated biphenyls (PCBs), for instance, are
particularly high molecular weight compounds that are well-adsorbed
onto carbon. However, there is an upper limit of molecular size
above which adsorption is adversely affected (21). Strongly
ionized or highly polar compounds are also more soluble and thus
usually poorly adsorbed. Compounds with solubilities of less
than 0.1 g/ml in water and molecular weights between 100 to 1000
are considered moderately to highly adsorbable (18).
Several other aspects of molecular structure also affect
adsorbability. In general, branched-chain compounds are more
adsorbable than straight-chain compounds. Increasing hydrocarbon
unsaturation also tends to decrease solubility and increase carbon
adsorption. Thus unsaturated organics such as ethylenes tend to
more readily adsorb on carbon than saturated compounds, such as
ethanes. Reference 21 discusses the influence of substituent
groups on adsorbability in more detail.
Adsorption isotherms are equilibrium batch tests that measure
the relationship, at a given temperature, between the amount of
substance adsorbed and its concentration in the surrounding
solution at equilibrium. Isotherms provide information on the
relative affinity of an organic compound for carbon and the amount
of adsorbate absorbed per weight of adsorbent or the -adsorption
38
-------
capacity. Thus isotherm tests, can be useful in making qualitative
evaluations of different carbons for adsorption of specific
components from a given waste stream. Perrotti (19) conducted
isotherm tests with 12 different carbons to determine the capacity
of each for the adsorption of phenol. These tests showed that
adsorptive capacities of different carbons vary widely.
Isotherms are frequently calculated using the Freudlich
Equation, which describes the adsorbability characteristics of a
constituent for a given carbon. This equation can be written as
follows: x/m=KC0 */n. The K-intercept is an indicator of adsorp-
tion capacity: the higher K, the higher the compound's adsorba-
bility. 1/n is an indicator of adsorption intensity. A high
value of 1/n indicates a stonger propensity for high concentrations
of a compound to adsorb at a greater rate than at low concentrations.
Data are available on the adsorption isotherms for many
organic compounds (e.g., Reference 22). Table A-12 gives the
results of several isotherm tests for many of the solvents addressed
in this rulemaking. Because adsorption isotherms vary widely for
different carbons, the solvent constituents listed in Table A-9
are ranked by the results of isotherm tests using one type of
carbon, Filtrasorb 300. Table A-12 demonstrates that a wide
spectrum of efficiency exists for the solvents addressed in this
rulemaking. The variation of adsorbability with carbon used is
also illustrated.
Inherent adsorbability of a compound as measured by an
isotherm test does not necessarily predict its degree of removal
from a dynamic, continuous-flow system. Adsorptive capacities
39
-------
TABLE A-12
COMPARISON OF ISOTHERM ADSORPTION CAPACITIES ON ACTIVATED CARBON
Molecular
Aqueous
Solubility
Freunlich Parameters
Weiqht
at 25°C (mq/1)
K
1/n
1,2-Dichlorobenzene
147
1.45xl02
129.0
0.41
Chlorobenzene
113
5.OxlO2
91.0
1.01
p-Xylene
106
1.75xl02
85.0
0.21
Nitrobenzene
123
1.19xl04
68.0
0.41
Ethylbenzene
106
l.OxlO4
53.0
0.81
Te tr ac hlor oe t hy le ne
166
50.8
0.6^"
84.1
0.47
273.0
0.64
Trichloroethylene
131
l.lxlO3
28.0
0.61
26.2
0.52
28.2
0.47
Toluene
92
5.15xl02
26.1
0.41
Methyl ethyl ketone
72
3.53xl05
23.0
0.28
24.0
0.25
5.OxlO2
36.0
0.211
Carbon tetrachloride
154
11.1
0.81
14.2
0.76
14.8
0.47
25.8
0.710
28.5
0.89
23xl04
38.1
0.73
Cyclohexanone
98
6.2
0.81
Trichlorofluoromethane
137
l.lxlO3
5.6
0.21
n-Butyl alcohol
5.5(7.
0) 0.5(0,
0.6(0,
9.5xl02
0.5(0,
1,1,1-Trichloroethane
133
2.5
°-3;
7.9xl04
9.4
0.57
Ethyl acetate
88
2.4
0.7®
1.67xl04
0.8^
0.811
Methylene chloride
85
1.3
121 A
0.74
I5 pH=2(11)
1. Fitrasorb 300(40)
2. Filtrasorb 300
3. Fitrasorb 400 (62)
4. Fitrasorb 400 (47)
5. Fitrasorb 400 (40)
6.- Hydrodarco 1030 (62)
7. Witcarb 950
8. Witco Grade 517(30)
9. Norit(62)
10. Nuchar WV-G (62)
11. Nuchar WV-G(40)
40
-------
TABLE A-12 (Continued)
Sources: USEPA. Treatment of Volatile Organic Compounds in Drinking Water.
EPA-600/8-83-019. May 1983.
Dobbs, R.A. and J.M. Cohen. Carbon Adsorption Isotherms for
Toxic Organics. EPA-600/8-80-023, April 1980.
Giusti, D. M, R.A. Conway, and C.T. Lawson. Activated Carbon
Adsorption of Petrochemicals. Journal of the Water Pollution
Control Federation, £6, No. 5, May 1974.
41
-------
calculated from isotherm studies may be significantly higher than
capacities achieved in columns evaded to exhaustion (21). Nonideal
flow conditions and limited contact times often employed in the
operation of full-scale carbon columns may play an important role
in reducing column loadings to values less than those predicted
from isotherm testing. However, the relative treatability of a
particular wastewater by activated carbon can be estimated by
isotherm data.
Bench-scale tests performed using PAC also provide information
on the amenability of solvents to carbon adsorption. Table A-13
gives the results of one bench-scale study for several solvents
addressed here. The solvents are ranked according to their
adsorbability. An analysis of molecular weights and solubilities
of these compounds shows no correlation between these properties
and adsorbability. It is clear that other factors, such as
molecular structure and ionic characteristics, also affect adsorba-
bility of the compounds.
b. Demonstration Status of Use to Treat Solvents
One EPA study performed in 1982 found that there are over
100 granular activated carbon systems used nationally to treat
industrial wastewaters (21). Activated carbon has also been used
to treat contaminated ground water (3,7,8). Another report docu-
ments the use of PAC at seven facilities in the United States and
four in Japan (23). An additional two facilities were in the
design stage when the report was published.
Theoretically, most of the solvent constituents can be
treated to some extent using carbon adsorption. Data- are avail-
42
-------
TABLE A-13
AMENABILITY OF SOLVENTS TO ACTIVATED CARBON ADSORPTION
Aqueous Concentration (mg/1) Adsorbability^/
Molecular Solubility^/ mg compound/ Percent
Compound Weight at 25°C (roq/1) Initial (C0) Final (Cf) g carbon Reduction
Nitrobenzene
123
1.9xl03
1,023
44
196
95.6
Methyl isobutyl
ketone
100
1.9xl04
1,000
152
169
84.8
Cyclohexanone
98
2.3xl04
1,000
332
134
66.8
N-Butyl alcohol
74
9.lxlO4
1,000
466
107
53.4
Ethyl acetate
88
7.9xl04
1,000
495
100
50.5
Pyridine
79
3.0xl0-8
1,000
527
95
47.3
Methyl ettyl
ketone
72
3.5xl05
1,000
532
94
46.8
obutanol
74
9.5xl04
1,000
581
84
41.9
Toluene
92
l.OxlO2
317
66
50
79.2
Acetone
58
2.3xl06
1,000
782
43
21.8
Ethyl benzene
106
1.5xl023/
at 20°C
115
18
19
84.3
Methanol
32
4.4xl06
1,000
964
7
3.6
1/ USEPA. Physical-Chemical Properties and Categorization of RCRA Wastes According to
Volatility. EPA 450/3-85-007, February 1985.
2/ Dosage: 5g carbon per liter solution; using Westvaco Nuchar WV-G(40) carbon.
3/ Verschuesen, K. Handbook of Environmental Data on Organic Chemicals. Van Nostrand
Press, New York, 1977.
Source: Giusti, D.M., R.A. Conway, and C.T. Lawson. Activated Carbon Adsorption of
Petrochemicals. Journal of the Water Pollution Control Federation, 46, No. 5,
May 1974.
43
-------
able that show the use of carbon adsorption to treat industrial
wastewaters or contaminated ground water containing acetone,
n-butyl alcohol, carbon tetrachloride, cresols, 1,2-dichlorobenzene,
methylene chloride, toluene, trichloroethylene, and xylene (21);
1,1,1-trichloroethane (24), pyridine and eyelohexanone (25); and
nitrobenzene (see Administrative Record to this rulemaking).
Isotherm and other adsorbability studies have been performed on
these and additional solvents (see Tables A-12 and A-13). Clearly,
carbon adsorption has been studied extensively, and the design of
carbon adsorption columns and use of powdered activated carbon is
wel1-documented.
c. Assessment of Performance
Data on the performance of carbon adsorption in treating
individual constituents present in wastewaters is limited for
several reasons. Because industrial wastewaters contain multiple
compounds and vary with time, data are often reported in terms of
gross parameters, such as biochemical oxygen demand (BOD), chemical
oxygen demand (COD), and total organic carbon (TOC). Removal
efficiencies as measured by these parameters can be poor indicators
of wastewater treatment performance, especially when the system
was designed for removal of color or specific components (21).
Only data available for removal of individual constituents are
reported here.
Furthermore, as discussed earlier, effluent concentrations
attained are generally dictated by the operation of the carbon
adsorption system. In some cases, concentration achieved was set
as an effluent concentration which was not to be exceeded.
44
-------
Contact time often limited to attain the desired performance.
The EPA study (21). found that 50 percent of the full-scale facili
ties reporting contact times used values of less-than 100 minutes
The study attributed contact times of greater than 230 minutes
to applications which required high degree of pollutant removal
or to the use of standardized adsorbers, where contact time is
set automatically based on flow and the number of columns in
operation.. This study also found that the degree of organic
removal varies widely from plant-to-plant and changes with time
at a given plant. These differences in performance may be caused
by variation in influent characteristics and changes in activated
carbon characteristics following repeated regeneration cycles.
Waste-specific pilot studies and full-scale testing can be used,
however, to determine contact times, hydraulic loading rate (and
other operating parameters that influence activated carbon
performance) that are necessary to achieve a performance goal.
Given these constraints, only data that in EPA's judgement,
resulted from optimally operated and designed carbon asborption
systems is presented here.
(1) Powdered Activated Carbon. PAC is a good adsorbent
with a high surface area per gram of material, but as it is
usually added to the water to be treated in a single dose, an
equilibrium is established between the organic compounds and the
absorbent, which limits the extent of removal possible. Results
of studies to date indicate that PAC is effective in removing
certain higher molecular weight compounds; however the lower
molecular weight compounds are not satisfactorily removed except
-------
when a very high dosage of PAC is used. In one study (7) to
remove organics from ground water, a PAC dosage of 50,000 mg/1
removed most extractable organics and slightly better removal was
achieved when lime was added (Table A-14). The concentration of
total organic carbon, however, remained 2500 to 3000 mg/1. At a
full-scale study at a water treatment plant in Florida, a PAC
dosage of 7 mg/1 and a 2-hour contact time removed at best 15 to
20 percent of an 18 ug/1 concentration of 1,1,1-trichloroethane
in ground water (26).
When added to activated sludge processes, however, PAC has
proven useful in increasing removals of volatile organics present
in higher concentrations. At a PAC dosage of 134 mg/1, 11 out of
13 volatile organic pollutants.showed greater than 90 percent
removal and acid extractable organics were readily removed at a
50 mgd plant (27). These results are shown in Table A-15. In
another full-scale activated sludge process, an undesignated
amount of PAC reduced effluent concentrations of chlorinated
pesticides by 95 percent, PCBs by 99 percent, organosulfur pesti-
cides by 100 percent, organophosphate pestides by 59 percent, and
phenol by 58 percent over the activated sludge process alone
(23).
(2) Granular Activated Carbon (GAC). Many pilot column
studies have been performed to evaluate the effectiveness of GAC
for removing organic compounds. A large number of recent studies
focus on the removal of volatile organic compounds found in water
supplies from ground water sources. Pilot-scale data are also
available for the treatment of industrial wastewaters; Table A-16
46
-------
TABLE A-14
EFFECTIVENESS OF POWDERED ACTIVATED CARBON (PAC)
TREATMENT FOR VARIOUS EXTRACTABLE ORGANICS
Concentration in Water-uq/1
Compound
Raw Water
PAC-Treated
Water
Lime-and PAC-
Treated Water
Solvents of Concern:
o-Cresol
80
<1
ND
m-Cresol
2 20
<1
ND
1, 2-Dichlo robe nze ne
5
ND
2
Other Orqanics:
Benzoic acid
1230
<1
ND
2-Chlorophenol
540
8
6
1, 4-Dichlorobenzene
35
ND
<1
2, 4-Dimethylphenol
20
2
<1
2-Ni trophe nol
15
<1
8
Pentachlorophenol
40
<1
ND
Phenol
370
<1
ND
1/ Water samples adjusted to pH 10.0, then supernatant was adjusted
to pH 6.5 with sulfuric acid before PAC treatment.
ND - None Detected
Source: Stover, E.L. and.D.F. Kincannon. Contaminated
Groundwater Treatability - a Case Study. Journal
American Water Works Association, June 1983.
-------
TABLE A-15
PERFORMANCE OF POWDERED ACTIVATED CARBON V
ADDED TO AN ACTIVATED SLUDGE SYSTEM
Concentration, ug/1
Percent
Compound
Influent
Effluent
Removal
Solvents of Concern:
Carbon tetrachloride
95
5. 5
94
Chlorobe nzene
1900
12
99
Ethylbenzene
29
6.5
78
Tetrachloroethylene
62
7.3
88
Toluene
680
4.1
99
1,1,1-Trichloroethane
18
ND
99
Trichlorofluoromethane
920
13
99
Other Organics:
Chlorodibromomethane
81
ND
>99
Chloroform
950
51
95
Benzene
160
ND
>99
Bromoform
910
100
89
Dichlorobromomethane
54
ND
>99
1/ Patented DuPont PACT process.
ND = None Detected
Source: Hutton, D.G. Removal of Priority Pollutants by
the DuPont PACT Process. Proceedings of the 7th
Annual Industrial Pollution Conference, Philadelphia,
PA, June 5-7, 1979.
48
-------
gives data for two such pilot-scale studies. These data illustrate
that consistently low effluent concentrations and high removal
efficiencies can be achieved for low concentrations (less than
250 ug/1) of individual constituents. It should be noted that
total organic concentrations were higher for the waste streams
treated.
Table A-17 summarizes available data (principally from pilot-
scale studies) for adsorption capacities for several volatile
organic compounds, including some of the solvents addressed in
this rulemaking. For all of the organic constituents listed, treat-
ment to less than 0.1 ug/1 was obtained.. Also using data from
several pilot column studies and from adsorption isotherms values
(22), carbon usage rates for six volatile organic were calculated
for various influent concentrations and desired effluent levels
(Table A-18). It is clear from both Table A-17 and A-18 that
both influent concentrations and effluent goals influence GAC
capacities. In particular, a wide range of GAC usage rates is
estimated for the removal of poorly adsorbed contaminants
(e.g., 1,1,1-trichloroethane) because a large amount of activated
carbon is required to achieve high removal rates. In application,
GAC usage rates must be estimated from exhaustion capacities and
other performance data obtained in pilot column studies of the
wastewater under consideration.
Table A-19 lists data from two full-scale GAC units. Plant.A
is a 1.64 MGD treatment facility in which three activated carbon
towers are operated as a polishing step to an activated sludge
49
-------
TABLE A-16
PERFORMANCE OF PILOT-SCALE GRANULAR ACTIVATED
CARBON COLUMNS FOR SOLVENTS OF CONCERN
Influent Effluent Percent
Compound Concentration (uq/1) Concentration (ug/1) Removal
Carbon tetrachloride
1.1
O.lV
91
Cresol
230
8.1V
97
Methylene chloride
190
51. oy
73
Te t rachlor et hy le ne
49.0
o.i4y
>99
Toluene
120
0.3y
>99
1,1,1-Trichloroethane
12.0
3.7
0.31/
0.775£/
>99
79
Trichlorethylene
21.0
170.8
0.31/
0.5902/
99
>99
1/ Becker, D.L., and S.C. Wilson. The Use of Activated Carbon for the Treatment
of Pesticides and Pesticidal Wastes. Carbon Adsorption Handbook.
P.N. Cheremisinoff and F. Ellerbusch, eds. . Ann Arbon Science, Ann Arbor,
Michigan, 1978.
2/ Ruggiero, D.C., and Ausubel, R. Removal of Organic Contaminants from Drinking
W&ter Supply at Glen Cover, New York. USEPA, Office of Research and
Development. Nebolsine Kohlman Ruggiero Engineers, P.C. NTIS PB 82-258963,
1982.
50
-------
TABLE A-17
ADSORPTION OF VOLATILE ORGANIC COMPOUNDS
BY GRANULAR ACTIVATED CARBON, SUMMARY
Exhaustion
loading, mVm'(a) capacity.
Avg.
8ed
depth.
EBCT,
Breakthrough
Exhaustion
cone.,
m
(U)
min
0.1 ug/L
(inf • eff)
(b)
uQ/L
(except as noted)
Trichloroethylene
177
0.8
(2.5)
9
>20.160
>20,160
21,500
4
0.8
(2.5)
8.5
>60,900 but '123.340
>123.340
99,900
3«
0.8
(2.5)
18
>32.500
>32,500
106,560
0.4"
0.8
(2.5)
18
>32.500
>32,500
199,800
Tetrachloroethylene
1400
0.8
(2.5)
9
12.300
33,100
17.500
94* ¦
0.8
(2.5)
18
>32,500
>32,500
57,400
9**
0.8
(2.5)
18
>32,500
>32.500
162,800
4
0.8
(2.5)
8.5
>60,900 but <123.340
>123,3-10
237,600
1
0.8
(2.5)
9
>20,160
>20,160
475,200
1,1, 1-Trichloroetnane
100
0.6
(2)
7.5
1,300t
not reported
3.800
1.2
(4)
15
2,700t
not reported
3,800
1.8
(6)
22.5
3.900t
not reported
3.800
237*
0.8
(2.5)
18
15,700
30,800
2,600
23**
0.8
(2.5)
18
>32.500
>32,500
12.000
38
0.8
(25)
8.5
11.800
26,000
9,400
1
0.6
(2.5)
9
16.400
22,500
94,400
Carbon Tetracnloride
12
0.8
(2.5)
10
14.000
25.000
9,400
0.8
(2.5)
5
6.050
not reported
9,400
Cis -1,2-Oichloroethylenet
18
0.8
(2.5)
6
4.100
15.800
9,400
1.5
(5)
12
7.100
14,300
9,400
2.3
(7.5)
18
8.100
13,700
9,400
6
0.8
(2.5)
9
14.200
19,000
15.300
2
0.8
(2.5)
8.5
29,600
48,600
26,000
Vinyl Chloride
7
0.8
(2.5)
S
810
2.400
Isotherm
1.5
(5)
12
1,250
¦
not repor
2.3
(7.5)
18
2.800
-
3.1-
CO)
25
2,050
5,011
1,2-0ichloroethane
8
0.8
(2.5)
20
1.700
8.640
3,500
1.4*
0.8
(2.5)
18
17,400
45.900
5,700
0.8—
0.8
(2.5)
18
>32,500
>32.500
5,000
2
0.9
(3)
11
3,300
9.160
4.000
1.8
(6)
22
3.400
7,850
4.000
2.7
(9)
33
4,150
>7,000
4.000
3.6
(12)
44
>7,000
>7,000
4,000
0.8
(2.5)
17.5
2.S00
7,450
4,000
0.7
(2.4)
17
2,500
7,450
4,000
1,1-Oichloroethylene
122*
0.8
(2.5)
18
22.400
>33,600
5.600
4"
0.8
(2.5)
18
*33,600
>33,600
31,100
Benzene
sooo
2.9
(9.4)
54
3.030H
>3,030
4,100
Methylene Chloride
20,000
2.7
(8.8)
262
860
860
600
(a) m3 water/in^ carbon
(b) Predicted by Freundlich isotherms.
* Adsorption of unaerated water; ** Adsorption after
10-minute aeration @ 4:1 (volume) air-to-water
t 5 ug/L in effluent? ttlO ug/L in effluent
Source: Dyksen, J.E. and A.F. Hess. Alternatives for
Controlling Organics in Groundwater Supplies.
Journal American Water Works Association,
August 1982.
51
-------
TABLE A-18
ESTIMATED CARBON USAGE NECESSARY
TO ACHIEVE DESIRED TREATMENT, SUMMARY
Desired effluent concentration. uq/L
Inf. COOC.. 0.1 1 10 50 loo
ufl/t a b ab a b a b a b
Trichloro-
1000
5.7-10.5
6.9 (0.50)
7.8-11.3
8.7 (0.4)
9.8-12.2
10.4 (0.32)
11.2-12.7
11.6 (0.29)
11.8-13.0
12.1 (0.28)
ethylene
100
13.8-25.3
16.7
(0.20)
20.2-27.9
22.1 (0.15)
26.7-30.5
27.7 (0.12)
31.2-32.3
31.5 (0.11)
10
33.1-64.6
41.0
(0.08)
56.3-72.1
60.3 (0.06)
-
.
-
_
_
1
79.4-146
96.1
(0.03)
-
-
-
-
-
-
-
-
1,1,1-Trichloro-
1000
0.17-6.1
1.7
(20)
0.19-7.5
2.6 (1.3)
0.2-8.9
3.3 (1.0)
0.21-9.9
3.9 (0.86)
0.22-10.3
4.2 (0.80)
e thane
100
0.79-28.0 8 1
(0.41)
0.88-36.0
13.0 (0.26)
0.98-45.0
18.0 (0.19)
1.1-51.0
21.0 (0.16)
-
_
10
3.6-127
37.0 (0.09)
4.3-186
70.0 (0.05)
-
..
-
_
_
_
1
16.0-580
169 (0.02)
-
-
-
-
-
-
-
-
Tetrachloro-
1000
10.6-16.2
14.7
(0.23)
17.7-21.8
20.7 (0.16)
24.7-27.5
26.7 (0.13)
29.5-31.4
30.9 (0.11)
31.7-33.2
32.7 (0.10)
ethylene
100
29.2-44.4
40.1
(0.08)
55.0-66.7
' 59.6 (0.06)
80.6-83.8
81.2 (0.41)
99.0-101
100 (0.03)
-
10
80.4-122
111 (0.03)
186-208
200 (0.02)
-
-
-
-
_
1
221-337
306 (0.01)
-
-
-
-
-
-
-
-
Carbon tetra-
1000
2.9-6.6
4.8
(0.7)
5.0-7.9
6.5 (0.51)
7.2-9.2
8.2 (0.41)
8.8-10.1
9.5 (0.35)
9.3-10.5
9.9 (0.34)
chloride
100
4.3-9.8
7.0
(0.48)
8.8-12.3
10.6 (0.32)
13.2-14.8
14.0 (0.24)
16.1-16.6
16.3 (0.21)
-
.
10
6.4-14.4
10.4
(0.32)
16-20.1
18.0 (0.19)
-
-
-
-
-
.
1
9.5-21.4
15.5
(0.22)
-
-
-
-
-
-
-
-
Cis-1.2-0lchloro-
1000
0.6-1.4
1.1
(30)
1.0-1.6
1.3 (2.6)
1.4-1.9
1.5 (2.2)
1.4-2.0
1.7 (2.0)
1.5-2.1
1.8 (1.9}
ethylene
100
1.8-4.4
3.3
(JO)
3.5-5.3
4.2 (0.8)
4.4-6.2
5.2 (0.65)
4.7-6.9
5.9 (0.55)
-
-
10
5.5-13.5
10.1
(0.3)
13.0-17.8
14.6 (0.2)
.
.
-
-
-
-
1
17.0-41.6
31.1
(0.1)
-
-
-
-
-
-
-
1,2-Dlchloro-
inoo
0.8-5.2
2.0
(1.7)
1.3-7.0
3.1 (1.1)
1.7-9.0
4.1 (0.82)
2.0-11.1
4.9 (0.6B)
2.2-12.0
5.2 (0.65)
ethane
100
1.1-8.4
3.5
(1.0)
2.2-13.0
5.4 (0.62)
3.0-17.6
7.3 (0.46)
3.6-20.8
8.6 (0.39)
-
-
10
1.6-12.5
5.2
(0.65)
3.8-22.6
9.3 (0.36)
-
-
-
-
-
-
1
2.4-18.4
7:6
(0.45)
-
-
-
-
-
-
-
-
1,l-0fchloro-
1000
2.5-8.5
5.5
(0.61)
3.3-11.5
7.4 (0.45)
4.8-14.5
9.6 (0.36)
4.8-16.6
11.0 (0.31)
5.1-17.5
11.3 (0.29)
ethylene
100
7.1-24.6
15.9
(0.21)
10.4-36.4
23.0 (0.14)
13.8-47.7
30.8 (0.11)
16.1-55.7
35.9 (0.09)
-
-
10
20-4-71
45 (0.07)
34.8-120
77.4 (0.04)
-
-
-
-
-
-
I 59.0-205 132 (0.03)
a - Granular activated carbon loadino range, 10 m water/in carbon; estimated from
isotherms and empirical data
b * Mean loading, lo' m' water/ro^ carbon (GAC usage, lb carbon/10^ gal Hater)
Source: Love, O.T. et cQ. Treatment of Volatile Organic Compounds in Drinking Water.
EPA-600/8-83-019, May 1983.
-------
system (10). The carbon is continually regenerated on-site. The
total of the average concentrations of the sampled organic com-
pounds for the influent to Plant A is 4.50 mg/1. Plant B operates
two GAC beds, 27 ft high by 8ft in diameter (inside diameter of 4
ft) at a flow of 60-80 gpm, or 1.3-1.6 gpm/ft 2 (10).. The
corresponding concentration of sampled constituents in the influent
to Plant B is 69.2 mg/1. This facility achieved very low effluent
values (below detection) for three phenolic compounds and excep-
tionally low values for a fourth, 2,4-dinitrophenol, present at
an average concentration of 35.5 mg/1. Effluent values for
phenol are also low if an outlier is excluded. Substantial
removal of nitrobenzene (94%) is also demonstrated. Although the
effluent values achieved for nitrobenzene are not below the
screening levels proposed in this rulemaking, modifications to
the operation and/or design of the GAC column may improve perfor-
mance for this constituent.
Table A-20 summarizes the full-scale data available for sol-
vents addressed in this rulemaking. Paired data are not available
for the carbon adsorption unit treating 3,500-6,500 mg/1 p-cresols.
The two carbon columns measured 4 ft in diameter by 30 ft high,
and contained 6,000 lb of Westvaco Nuchar WV-L activated carbon,
the system operated at superficial feed velocities of 2.2 to 3.6
gpm/ft^, averaging 3.2 gpm/ft^ (28). The units were designed
to achieve an effluent value of 3 mg/1 of cresols. Based on this
design information, and on the range of effluent values achieved,
it appears that the system is capable of reducing 3,500 mg/1 of
effluent to below detectable values in the effluent.
53
-------
TABLE A-19
Performance Data For Full Scale
Granular Activated Carbon Treatment Systems11/
Plant A
Compound
Benzene
Chlorobenzene
1,2-Dichlorobenzene
1,4-Dichlorobenzene
2,4-Dini trotoluene
2,6-Dini trotoluene
Methylene Chloride
Nitrobenzene
2-Ni trophenol
4-Nitrophenol
2,4-Dini trophenol
Phenol
Toluene
Average Influent
Concentration
(mq/1) (range)
0.138(0.
0.109(0.
0.597(0.
0.018(0.
0.947(0.
0.347(0.
0.026(0.
0.936(0.
0.062(0.
0.115(0.
0.102(0.
0.087(0.
1.02 (0.
033-0.526)
014-0.298)
394-1.15)
011-0.023)
516-1.91)
214-0.740)
026-0.026)
011-4.17)
033-0.098)
087-0.143)
063-0.155)
013-0.258)
094-2.14)
Average Effluent
Concentration
(mg/1) (range)
0.023(
0.020(
0.203(
<0.010(
0.312(
0.179(
<0.010(
0.422(
0.023(
0.055(
<0.050(
0.030(
0.114(
0.010- 0.087)
<0.010- 0.056)
0.126- 0.481)
<0.010-<0.010)
0.119-0.536)
0.104- 0.338)
<0.010-<0.010)
<0.010- 1.90)
<0.020- 0.035)
<0.050- 0.059)
<0.050-<0.050)
<0.010- 0.184)
0.021- 0.330)
Plant B
Canpound
Average Influent
Concentration
(mg/1) (range)
Average Effluent
Concentration
(mg/1) (range)
Ni trobenzene
2-Nitrophenol
4-Ni trophenol
2,4-Dintrophenol
2-Methyl-4,6-Dini trophenol
Phenol
11.8 (4.60-22.0)
2.46(1.40- 3.72)
4.18(1.79- 6.60)
35.5(20.0 -58.4)
9.86(7.62-11.4)
5.39(2.18- 9.80)
0.713(0.135- 4.90)
<0.020(<0.020-<0.020)
<0.050(<0.050-<0.050)
0.372(<0.050-<0.020)
<0.020( 0.023- 0.472)
0.260( 0.023- 0.472)
11/ Office of Solid Waste Analysis of Organic Chemicals, Plastics, and Synthetic
Fibers Industries database.
54
-------
TABLE A-20
SUMMARY OF PERFORMANCE OF FULL-SCALE GRANULAR ACTIVATED
CARBON ADSORPTION FOR SOLVENTS OF CONCERN
Average Influent Average Effluent
Concentration Concentration
Compound (Range) (mq/1) (Range) (mq/1)
Chlorobenzene 0.101 (0.010-0.298) 0.023 (0.010-0.068)
Cresols 16.5 0.62^/
3,500-6,500 0-700V
1,2-Dichlorobenzene 0.596 ( 0. 394-1. 153) 0.201 ( 0 .1 26-0 . 481)_}/
Nitrobenzene 0.344 ( 0. 169-0.664) 0.027 (<0. 010-0.079 )£/
11.8 (4.60-2.20) 0.713. (0.135-4.90)£/
Toluene 2.14 0.0214/
1/ Office of Solid Waste analysis of Organic Chemicals, Plastics,
and Synthetic Fibers Industries Database; average of influent
values above screening levels; unpaired influent values excluded.
2/ USEPA. Survey of Industrial Applications of Aqueous-Phase
Activated Carbon Adsorption for Control of Pollutant Compounds
from Manufacture of Organic Compounds. PB-83-200-188, 1982.
3/ Baker, C.D. et: al^. Recovery of p-cresol from Process Effluent.
In AIChE Symposium Series, ed. G.F. Bennett, Water, 70(136), 1973.
£/ Office of Solid Waste analysis of Organic Chemicals, Plastics,
and Synthetic Fibers Industries Database; average of all influent
values is given, including unpaired values.
55
-------
Although performance data for. individual constituents is
lacking, available data clearly demonstrate that for some
wastewaters, even those containing relatively high concentrations
of organic constituents, low effluent values can be achieved.
Available data demonstrate that the use of GAC columns achieve
levels below the proposed screening levels for cresols,
nitrobenzene, and toluene.
5. RESIN ADSORPTION
a. General Description
A synthetic resin (sometimes referred to macroreticular
carbonaceous adsorbents) is a man-made, high molecular weight
polymer. Special types of synthetic resins have been found to be
useful as adsorption media by virtue of their high ratio of
surface area to volume. Some of the more common commerically
available resin adsorbents are s.tyrene-di vinyl benzene, acrylic
esters, and phenol-formaldehyde resins.
The liquid waste is forced through a bed of resin, where
organic molecules are preferentially adsorbed. Usually, two beds
are used, with one being regenerated while the other is in operation.
The waste is passed through the bed. Removal efficiency and life
of the resin are dependent on the type of waste and resin used.
Regeneration can be performed in situ with aqueous solutions of
various pH, salt solutions, or nonaqueous solvents. Unless the
solute contaminated solvent can be used in an industrial process,
some sort of refining process such as distillation will be
necessary to recover the solvent.
56
-------
Synthetic resins have been developed to adsorb low molecular
weight organics but will pass the higher molecular weight organics.
Synthetic resins remove organic compounds by the same mechanism
as activated carbon. However/ through proper choice of porosity
and hydrophobic surface characteristics, synthetic adsorbents can
be manufactured to adsorb specific compounds. For instance,
Ambersorb XE-340, manufactured in the past by the Rohm and Haas
Company, is designed to remove low molecular weight, nonpolar
organics (e.g., most volatile organic compounds), and it has
little affinity for high molecular weight polar organics (i.e.,
molecular weight greater than approximately 200 g/mole).
b. Demonstration of Use to Treat Solvents
Because of their expense, resins are not commonly used full-
scale to remove organics from wastewaters. Data documenting the
experimental use of resin is discussed in the next section. Most
of the studies were performed to compare the performance of resins
to activated carbon adsorption. There is experimental evidence
that resins can be used to remove a variety of organic constituents.
These organics include the following solvents addressed in this
rulemaking: trichloroethylene, tetrachloroethylene, 1,1,ltrichloro-
ethane, and carbon tetrachloride (3); n-butyl alcohol and
1,2-dichlorobenzene (29); and toluene and xylene (30).
c. Assessment of Performance
In various tests of Ambersorb XE-340 on ground water
contaminated with volatile organics, the capacity for adsorbance
per gram of the resin has been shown to be typically two to three
times that of GAC'(on a weight basis) for control to break through
57
-------
TABLE A-21
ADSORPTION OF TRICHLOROETHYLENE AND RELATED
SOLVENTS BY AMBERSORB XE-340, SUMMARY
Empty bed
Loading to 0.1 jg/L
Avg. cone.
Bed depth,
contact time
, breakthrough,
uq/L
m (ft)
minutes
m3/m3*
Trichloroethyl ene
215
0.3
1)
2
83,700**
210
0.6
2)
4
78,600**
210
1.2
4)
7.5
>53,300**
177
0.8
2.5)
9
>20,160
4
0.8
2.5)
8.5
>123,340
3 .
0.2
0.8)
5
>117,000
Tetrachloroethylene
41
0.3
1)
2
>99,900**
51
0.6
2)
4
78,600**
65
1.2
4)
7.5
>53,300**
70
0.3
1)
2
106,000**
94
0.8
2.5)
5
112,900
1400
0.8
2.5)
9
17,920
3
0.8
2.5)
8.5
>123,340
2
0.8
2-5)
9
>20,160
1,1,1-Trichloroethane
5
1.2
4}
7.5
39,300**
33
0.8
2.5)
9
56,000
237
0.2
0.8)
5
82,600
23
0.2
0.8)
5
>100,800
1
0.8
2.5)
9
>20,160
Carbon Tetrachloride
19
0.8
2.5)
5
7560
19
0.3
2.5)
10
15,120
Cis-1,2-0ichloroethylene
40
0.3
1)
2
37,200**
38
0.6
2)
4
39,500**
40
l.Z
4)
7.5
19,700**
40
0.3
1)
2
36,400**
25
0.8
2.5)
6
14,400
22
0.8
2.5)
6
7200
16
0.8
2.5)
6
11,500
6
0.8
2.5)
9
>20,160
2
0.8
2.5)
8.5
>59,000 but<123,340
1,2-0ichloroe thane
1
0.2
9.8)
5
108,860
1,1-Dichloroethylere
122
0.2
0.8)
5
80,600
4
0.2
0.8)
5
110,800
•ot-* wattr/mJ carbon ¦ : ' ~
"Breakthrough defined by shape of wavefront curve; generally 20 to 25 ug/L of contaminant in
adsorbent effluent
Source: USEPA. Treatment of Volatile Organic Compounds in
Drinking Water, EPA-600/8-83-019, May 1983.
58
-------
(32). Table A-21 gives a summary of resin adsorption data. These
data can be compared to GAC data given in Table A-17. Note that
resin loadings will appear disproportionally higher than GAC
loadings when resin breakthrough is defined as 20-25 ug/1 of
contaminant in the effluent.
Adsorption behavior, as well as capacity, is different for
resins. Symons (5) reported that Ambersorb XE-340 removed carbon
tetrachloride from Cincinnati, Ohio drinking water for about the
same length of time as GAC did. However, the resin showed much
less desorption than GAC when influent concentration of carbon
tetrachloride declined. Similarly, the breakthrough curve was
gradual for the resin when 1,1,1-trichloroethane was adsorbed,
compared to a steep slope for GAC. Ambersorb XE-340 appears to
be more susceptable to competitive adsorption. In one study, an
increase in chlorine concentration decreased resin capacity for
PAHs, whereas GAC performance did not suffer (32). Time in
service for this resin when treating chlorinated hydrocarbons
also decreased significantly as TOC in the water increased from
less than 1 mg/1 to greater than 1 mg/1.
6. EVAPORATION
a. General Description
Quite simply, evaporation is the vaporization of a liquid
from a solution or a slurry to separate the liquid from a dissolved
or suspended solid or liquid. Evaporation differs from distillation
because one or more components in the waste are not appreciably
volatile. Types of evaporators include kettle, tubular, scraped
surface and thin^-film. The simplest evaporation device is an
59
-------
open pan or kettle which receives heat from a coil or jacket or
by direct firing underneath the pan. Tube evaporation contain
liquid in tubes contained within a closed vessel. Steam or hot
gases pass over the bundle of tubes located in the lower part of
the vessel.
A scraped-surface evaporator is designed to facilitate
density separation of spent solvent components. A power-driven
shaft with attached paddles revolves inside a vertical vessel.
The entire vessel is encased in a heating jacket surrounded by an
exterior insulation jacket. Heat is usually provided by steam,
but other heating methods are also used. Heavy sludges and solid
materials fall to the bottom of the vessel, while the lighter
components are vaporized and drawn out of the top of the vessel.
The scraped-surface evaporator is well suited to solvent streams
with a high concentration of suspended solids and sludges and can
be effective in separating spent solvent fractions by density.
However, wastes containing resinous solids are not amenable to
this technology.
Thin-film evaporation operates on the same principle as
scraped-surface evaporation? that is, density separation of spent
solvent components facilitated by added heat. However, the vessel
is modified so that a thin film of liquid material is spread
against the heated walls of the vessel. The lighter fraction in
the solvent material vaporizes when heated and rises out of the
vessel, where it is condensed and routed to further distillation,
recycle, or reuse. The heavier solids and sludge materials remain
in the vessel and*are periodically withdrawn from tha vessel
60
-------
bottom for disposal. Thin-film evaporation is best suited to
reclaiming lighter solvents (i.e., those with boiling points
between 150°C and 200°C). As in the case of other evaporative
methods, thin-film evaporation is not applicable to spent solvent
streams containing resinous materials.
In general, evaporation is useful for the separation of
volatile constituents from liquid waste. Evaporation processes
can be particularly useful for the treatment of spent solvents,
because volatile materials existing the evaporator may be condensed
and recycled or reused.
Operational problems may arise when processing spent solvent
streams that contain high concentrations of dissolved or suspended
solids. Dissolved solids can interfere with heat transfer, if
they are allowed to crystallize and deposit on the walls of the
evaporation vessel forming an insulating layer. Suspended solids
are of concern because they can erode the tubes. If high
concentrations of dissolved or suspended solids are present, then
a scraped-surface evaporator may be suitable,
b. Demonstration of Use of Treat Solvents
Very limited data are available concerning the extent to
which evaporation is currently used as a spent solvent treatment
or recovery technique. It has been reported that the scraped-
surface evaporator is used in the chemical industry both as an
independent separator and as a pretreatment step prior to fractional
distillation in a spent solvent recycling process. Information
regarding current use of evaporation was obtained from a study,
the effeetiveness of thin film evaporation in the removal of
61
-------
volat ile organics was evaluated. The report asserts that thin-
film evaporators are used in many solvent recovery operations.
In the EPA study, three thin-film evaporation processes
currently operating in the chemical industry were investigated by
field sampling and analysis. The wastes treated in the three
processes were: (1) a mixture of high-boiling hydrocarbons with
less than 2 percent each of methylene chloride, chloroform, 1,1,1-
trichloroethane/ and toluene? (2) mixed xylenes and isopropyl
alcohol, with about 10 percent ethylbenzene; (3) waste acetone
containing xylene, low levels of chlorinated solvents, and
dissolved polymeric resins. These data demonstrate that thin-
film evaporation is useful for waste volume reduction and volatile
organic compound (VOC) removal in systems with high boiling point
organics.
c. Assessment of Performance
Performance data for three thin-film evaporators were obtained
in a study performed for EPA (13). This study, described briefly
above, provided data from analysis of the feed, the bottoms, and
the product streams from three thin-film evaporators. The
available information and data are summarized in Table A-22. The
first evaporator treated a streamed consisting mostly of mixed
chlorinated xylenes containing low concentrations of methylene
chloride, chloroform, 1,1,1-trichloroethane, toluene, and
trichlorofluoromethane (Freon TF). Removal effectiveness levels
for the following solvent compounds were estimated using a material
balance from the information presented in Table A-22. These data
62
-------
Table A-22
PERFORMANCE DATA FOR THREE THIN-FILM EVAPORATORS
PLANT A
Feed
Product
Bottoms
Constituent
Concentration
Concentration
Concentration*
Methylene chloride
2.0$
0.9*
Chloroform
1.5*
ND
1,1,1-Trichloroethane
0.7*
ND
Toluene
1.3*
1.6*
Xylenes
94.4*
93.9*
Freon TF
1.8*
•Bottoms were solid upon cooling.
ND - Indicates compound was not detected.
PLANT
B
Feed
Produot
Bottoms
Constituent
Concentration
Concentration
Concentration*
Isopropyl alcohol
38.2*
53.8*
Freon TF
0.6*
0.7*
Toluene
0.4*
0.4*
Ethylbenzene
11.4*
8.4*
Xylenes
49.2*
34.0*
•Bottoms were solid upon cooling.
PLANT
C
Feed
Distillate
Bottoms
toattntrattQD
ftnsttntrattoB
S
-------
are based upon the headspace analysis and 95 percent product
recovery:
Chloroform <99.99
Methylene chloride 99.1
Toluene <85.0
1,1,1-Trichloroethane <99.5
Concentrations of the more volatile components are reduced in the
bottoms stream. Vapor pressure of these compounds are reduced
more than 90 percent during treatment by thin-film evaporation.
The second evaporator that was evaluated processed a volatile
organic liquid composed of alcohol and aromatics (xylene and
ethylbenzene as shown in Table A-22). Although the data do not
appear to demonstrate high removal rates in terms of percentages,
it should be noted that hte volume of waste was reduced by about
50 percent. In general, the more volatile components were
concentrated in the overhead or product stream, while the.less
volatile components were concentrated in the bottoms stream as
expected.
The third thin-film evaporator processed a waste consisting
primarily of acetone low levels of xylene, chlorinated solvents,
and dissolved polymeric resins (see Table A-22). The performance
data obtained from this evaporator demonstrate that the acetone
was somewhat concentrated in the distillate, and xylene was
enriched in the bottoms stream. In this case, the volume of
waste was reduced by 10 percent.
64
-------
In conclusion, the use of evaporation is not well-demonstrated
for solvent-containing wastes. Furthermore, from the evaluation
of three evaporators thin-film evaporation appears to be useful
for reducing the volume of waste that must be treated further,
and for separating volatile components from systems with high
boiling point organic substances.
65
-------
PART B
DESTRUCTION TECHNOLOGIES
There are several treatment technologies that can be used to
"destroy" waste solvents using biological, chemical, or thermal
means. These include biological degradation, chemical oxidation
and reduction, and the thermal decomposition techniques of fuel
substitution and incineration. All of these processes involve
oxidation and reduction reactions, which break the chemical bonds
within the solvent molecule, producing smaller and less hazardous
molecules. During biological degradation, the oxidation and
reduction reactions take place within the cell walls of various
biota such as bacteria, viruses, fungi, and other, microbes.
Chemical and thermal decomposition require the addition of
chemical agents or heat and oxygen to induce the oxidation-
reduction reactions. The products of oxidation/reduction are
typically carbon dioxide, carbon monoxide, water, and, if the
waste is chlorinated, hydrogen chloride.
1. BIOLOGICAL TREATMENT
a. General Description
There are several biological treatment processes that have
been successfully used to remove organic constituents from waste
streams. The biological treatment systems most commonly used on
waste solvents are those employing aerobic digestion, such as
activated sludge, aerated lagoons, and trickling filters. Other
biological treatment technologies such as composting and
66
-------
anaerobic digestion are applicable to such wastes but currently
are used to a lesser extent.
Five biological treatment technologies are discussed here.
Three of these are applicable to wastewaters contaminated with
organic solvents: activated sludge, aerated lagoons, and trick-
ling filters. Rotating biological contactors are less frequently
used, and are discussed only briefly here. The last two, anaero-
bic digestion and composting, are applicable to solids and
sludges containing greater than one percent solids, and also are
discussed only briefly.
(1) Activated Sludge. The activated sludge process con-
sists of aeration in a basin or tank, followed by clarification
to separate the biomass sludge from the effluent. The aeration
basin contains the microorganisms (activated sludge) that aero-
bically biodegrade the organic waste stream constituents. The
basin provides 2 to 24 hours of retention, depending on the
organic decomposition. Nutrient (e.g., phosphorus and nitrogen)
levels must be maintained in the aeration basin. A mixture of
organisms and effluent is discharged from the basin into a
clarifier, where the sludge is removed through sedimentation.
Clarified effluent is discharged from the clarifier and a portion
of the sludge is recycled to the aeration basin. This recycling
allows the maintenance of high concentrations of aerobic bacte-
ria. These acclimated bacteria hydrolyze and oxidize polysaccha-
rides, fats and proteins, and simple and complex organics. In
67
-------
addition, trace levels of soluble metals are adsorbed on the
sludge contents.
Removal of organics during activated sludge treatment is
normally complete enough so that the effluent may be discharged
without further treatment. However, the resulting sludge may
require additional biological treatment to reduce organics
concentrations prior to disposal. The sludge may also require
further treatment or special disposal because of its tendency to
adsorb metals.
Activated sludge treatment is capable of handling waste
streams containing less than one percent suspended solids and
trace levels (less than one milligram per liter) of inorganics.
The process is unsuitable for treating viscous liquids, slurries,
sludges, tars, solids, and wastes containing the following types
of compounds: nitrogen compounds, insoluble metals and cyanides,
halogenated organics, compounds with slow biodegradation rates,
cellulose, lignin, and oils and grease (33). The activated
sludge process is sensitive to sudden changes in organic or
hydraulic loading or the sudden appearance of toxic substances.
(2) Aerated Lagoons. Aerated lagoons are the simplest means
of biological treatment. Biological degradation is often accom-
plished by natural processes involving the use of both algae and
bacteria (1). This method of biological treatment incorporates
mechanical aeration in a surface impoundment or large shallow
tank. Biological degradation occurs much more slowly than in
68
-------
activated sludge or trickling filter systems, and partial
removal, particularly of solvents, may result from air stripping.
Shallow lagoons (i.e., depth of about 6 to 8 inches) maximize
the production of algae. The oxygen released by the algae
through the process of photosynthesis is used by the bacteria in
the aerobic degradation of organic matter. To maximize the
amount of oxygen produced by the algae, pond depths of up to 5
feet are used. In both cases, best results are achieved when the
contents of the lagoon are mixed periodically using pumps or
surface aerators. Up to 95 percent removal of BOD^ is achieved
in aerobic ponds (1), and removal in aerated lagoons is probably
higher.
(3) Trickling Filter. The trickling filter process is a
proven technology used to decompose organics in aqueous waste
streams with less than one percent suspended solids. The process
can partially treat wastes similar to those handled by the
activated sludge process over a retention time of less than an
hour. Trickling filters consist of a basin, usually 3 to 15 feet
deep, filled with rocks or synthetic media over which wastewater
is distributed. The. rocks or media support bacterial growth.
Liquid waste is sprayed through the air over the trickling filter
assembly to absorb oxygen and is allowed to trickle through the
bed of rock or synthetic media coated with a slime of microbial
growth. The microbial slime of aerobic bacteria is able to
decompose organics in the waste stream. Wastewater is
69
-------
distributed evenly over the filter media by either rotary distri-
bution arms, or fixed spray nozzles. An underdrain is used to
convey effluent, and to provide a conduit through which upflowing
air can pass to maintain aerobic conditions. Simple and complex
organics are either oxidized or hydrolyzed to produce methane and
carbon dioxide.
Because of the relatively short residence time of wastewater
in contact with microorganisms, the removal of organics is not
complete, and thus trickled effluent must be further treated
biologically. It . is suggested that short residence time allows
greater variations in influent waste composition, allowing
resistance to shock loadings without inhibiting microbial activ-
ity. Trickling filters maintain a slow sludge buildup which
allows low production of waste sludge. The trickled effluent
must be clarified so that microbial slime which has sloughed off
the support is removed. Extreme hydraulic loadings should be
avoided so that the biomass does not slough off the filter.
The process is often used as a primary treatment step to
level hydraulic and organic loads or to reduce concentration
levels of biodegradable organics. The process is not sufficient
as the sole means of biodegradation because of the inefficient
and incomplete decomposition of organics (33, 34).
(4) Rotating Biological Contactor. The rotating biological
contactor (RBC) consists of a series of closely spaced, parallel
disks which are rotated while partially immersed in a trough of
70
-------
wastewater. Here, wastewater is held for four hours only. The
disks are constructed of. polystyrene, polyvinyl chloride, or
similar materials. Each disk is covered with a biological slime
which absorbs colloidal and dissolved organic matter present in
the wastewater. As the disk is rotated out of the tank, it
carries a film of the wastewater into the air where oxygen is
available for aerobic biological decomposition. As excess
biomass is produced, it sloughs off from the disk and must be
collected from the process effluent in a final clarifier.
RBCs can be used to treat and dilute aqueous wastes contain-
ing biodegradable organics, including solvents. The larger
amount of biological cell mass permits the system to withstand
organic and hydraulic surges effectively. High concentrations of
heavy metals, refractory organics, and other toxic substances and
conditions are unsuitable for the RBC treatment. Sludge is a
by-product and accumulation of heavy metals and certain refrac-
tory organics may require disposal of the sludge as hazardous
waste. The continuous agitation can cause release of certain
volatile organic compounds (34).
(5) Anaerobic Digestion. Anaerobic digestion is a process
for decomposing organic matter in closed vessels in the absence
of air. The anaerobic condition is maintained in a closed-tank
digester with no agitation mechanism, at temperatures between 31°
and 40° C. The process allows hydrolysis and fermentation to
occur in the oxygen-free environment and supports symbiotic
71
-------
habitation of acid-forming and methane-producing bacteria. Over
a two week period, anaerobic bacteria digest simple organic and
nitrogen-containing compounds to produce methane and carbon
dioxide, and to reduce carbon substrate. The process is not
suitable for treating acidic wastes; hydrocarbons, especially the
chlorinated type; or high organic loadings.
Anaerobic digestion has traditionally been used to reduce
waste volume and to improve the stability of organic semisolids
and biomass sludges. The process typically treats sludges
containing 5 to 7 percent solids content. The sludge is reduced
in volume by 40 to 60 percent.
Because the process can be modified for the recovery of
usable energy, namely methane gas, it can be cost-competitive. A
growing number of full-scale, industrial wastewater anaerobic
treatment installations are using new reactor configurations and
process modifications. Current research and development efforts
in hazardous waste treatment include the degradation of wastes
containing polyaromatic hydrocarbons and halogenated aromatics
(33).
(6) Composting. Composting involves leaving high-strength
organic sludges and solids in piles or pits for decomposition,
and aerating by periodic turning. Adequate aerating, optimum
temperature, moisture and nutrient contents, and presence of the
mixed microbial population are necessary to accelerate decomposi-
tion of all organics, phosphorus- and nitrogen-containing
72
-------
compounds, and oil by hydrolysis or oxidation reactions. Com-
posting is enhanced by size uniformity of the substrate.
This is the only biological treatment process relatively
insensitive to toxicants, and it encourages adsorption of metals.
The mesophilic and thermophilic bacteria used in composting are
active when the ambient temperature is between 10°C and 45°C and
50°C and 70°C, respectively. Aeration is accomplished by peri-
odic turning. Alkaline aerobic conditions are maintained to
minimize metal toxicity to microorganisms. Metals are removed by
either adsorption or precipitation. The process is unsuitable
for halogenated aromatic hydrocarbons and refractory organics.
The process, with a waste retention time of 3 to 6 months,
can be made environmentally safe by providing means to collect
leachate and runoff water from the composting beds. The process
is not presently used because insufficient market exists for the
resulting end product, humus (33, 35, 36).
b. Demonstration of Use to TrMt Snlventa
Biological treatment, principally activated sludge and
aerobic lagoons, is commonly applied to the treatment of indus-
trial wastes. EPA estimates that over 2,000 direct industrial
dischargers use biological treatment. In addition, hundreds of
indirect dischargers pretreat their wastes prior to discharging.
As discussed in the next section, biological treatment data
are available for the following solvents addressed in this
rulemaking: carbon tetrachloride, chlorobenzene,
73
-------
1,2-dichlorobenzene, ethylbenzene, methylene chloride, nitroben-
zene, tetrachloroethylene, toluene, and trichloroethylene.
Although data are not readily available, the following solvents
are amenable to biological treatment based on their high solubil-
ity and/or low inhibitory "effects: acetone, n-butyl alcohol,
cresols, cyclohexanone, ethyl acetate, ethyl ether, isobutanol,
methanol, methyl ethyl ketone, methyl isobutyl ketone, and
pyridine.
c. Assessment of Pprformance
Treatment performance data for nine solvent constituents in
biological treatment systems were obtained from data collected
during development of effluent guidelines for the Organic Chemi-
cals, Plastics, and Synthetic Fibers Point Source Category. A
summary of this data is presented in Table B-1. The data reflect
the performance of activated sludge, aerated lagoons, and trick-
ling filter treatment systems. As indicated on the table,
significant removals are achieved for all constituents listed.
Additional treatment performance data for solvent wastes are also
available in the open literature. Research articles demonstrat-
ing the biodegradability of acetone, n-butyl alcohol, cresols,
ethyl acetate, pyridine, and 1,1,1-trichloroethane are contained
in the Administrative Record supporting this rulemaking (63* 64,
65, 66, 67, 68, and 69). Data presented in those articles
indicate that activated sludge treatment generally removes 60 to
.99+ percent of these solvent waste constituents.
74
-------
Table B-1
AVERAGE PERFORMANCE OF FULL-SCALE BIOLOGICAL TREATMENT
FACILITIES FOR SOLVENTS OF CONCERN1
(mg/1)
Compound
Carbon tetra-
chloride
Chlorobenzene
1,2-Dlchloroben-
zene
Ethylbenzene
Methylene chlo-
ride
Nitrobenzene
Tetraohloro-
ethylene
Toluene
Triohloroethyl-
ene
Type of
Treatments
AS
AS, AL
AS, AL
AS, AL
AS
AS
AS, AL
Average Influent
Concentration (Range)
6.00 (0.192-44.0)
9.88 (3.04-49.8)
5.70 (2.08-23.3)
8.45 (2.21-80.0)
2.30 (1.64-3.91)
0.765 (0.140-2.32)
0.435 (0.036-2.25)
AS, AL, TF 20.9 (2.08-160)
AS 0.231 (0.134-0.484)
Average Effluent
Concentration (Range)
<0.010 (NA)
0.292 (0.017-1.33)
0.302 (<0.010-1.15)
<0.010 (NA)
0.011 (<0.010-0.026)
<0.010 (NA)
0.010 (<0.010-0.019)
0.066 (<0.010-1.45)
0.011 (<0.010-0.016)
^Office of Solid Waste Analysis of Organic Chemicals, Plastics, and Synthetic
Fibers Industries Data Base.
AS s Activated Sludge
AL a Aerated Lagoon
TF s Trickling Filter
NA s Not Applicable
75
-------
Many of the solvents addressed in this rulemaking are not
priority pollutants regulated under the Clean Water Act. As
such, little or no treatment performance data have been developed
and published for these pollutants. Treatment performance data
for biological treatment are currently unavailable for: carbon
disulfide, cyclohexanone, ethyl ether, isobutanol, methanol,
methyl ethyl ketone, methyl isobutyl ketone, 1,1,2-trichloro-
1,2,2-trifluoroethane, trichlorofluoromethane, and xylene.
Although performance data for these compounds are not available,
the effectiveness of biological treatment in treating these
solvents at noninhibitory concentrations is expected to be
similar to the performance demonstrated for other solvent con-
stituents.
2. CHEMICAL QXIDATIOM
a. General Description
Chemical oxidation technology makes use of strong oxidizing
agents to oxidize substances in aqueous solution. Chemical
oxidation differs from thermal oxidation in that the strong
oxidizing potential of the oxidizing agent is the driving force
of the chemical oxidation reaction. Thermal oxidation utilizes
high temperatures to derive the reaction. Organic solvents are
among those compounds that are potentially oxidized by chemical
means. Commonly used chemical oxidants for organic constituents
include potassium permanganate, ozone, and hydrogen peroxide.
Other oxidizing agents that are available include chlorine,
76
-------
chlorine dioxide, perclorate ion, persulfate ion, percloric acid,
and nitric acid.
Chemical oxidations are generally performed in well-mixed
continuous or batch reactors. The speed at which the oxidation
reaction takes place is often dependent on several variables,
such as solution pH, presence of inorganic catalysts, concentra-
tion of reactants, and completeness of mixing. Practical reac-
tion times for oxidation reactions are generally considered to be
a few minutes to about one hour. At the end of this time the
constituents to be oxidized are either completely oxidized to
carbon dioxide and water or have been partially broken down into
components which can be further treated by other means, such as
biological oxidation. Once reacted, the final oxidized solution
is generally subjected to some form of treatment to settle or
precipitate any insoluble oxidized material, metals, and other
residues.
Chemical oxidation is best suited for aqueous liquids contain-
ing less than one percent of the oxidizable compound. Violent
reactions may occur when oxidizing agents are added to signifi-
cantly higher concentrations of easily oxidizable organics.
Strong oxidants are relatively non-selective; therefore, any
easily oxidizable material will be treated. Certain organic
species are more easily oxidized than others. In a very qualita-
tive way, the reactivity of selected organic compounds with
respect to oxidation is as follows (37):
77
-------
1. High reactivity - phenols, aldehydes, aromatic amines,
certain organic sulfur compounds, e.g., thioalcohols, thioethers;
2. Medium reactivity - alcohols, alkyl-substituted aromat-
ics, nitro-substituted aromatics, unsaturated alkyl groups,
carbohydrates, aliphatic ketones, acids, esters, and amines; and
3. Low reactivity - halogenated hydrocarbons, saturated
aliphatic compounds, benzene.
Chemical oxidation is not suitable for wastes containing
significant amounts of compounds or properties that represent an
excessive demand for oxidant, such as BOC, COD, nitrogen, or
phosphorus. If the waste matrix to be oxidized contains a
significant amount of material that is more easily oxidized than
the toxic constituents of concern, then oxidant demand exhibited
by the easily oxidized species must be met before oxidation of
the constituents of concern will take place. For this reason,
oxidation often has limited application to sludges containing
solvents. If present, more easily oxidized components of the
sludge will be oxidized preferentially rather than the constitu-
ents of concern.
b. Demonstration of Use to Treat Solvents
Technology for large-scale application of chemical oxidation
is well-developed (38). The primary use of chemical oxidation
technology has been in municipal water treatment for the
oxidation of phenols, amines, humic acids, other taste, odor, or
color-producing or toxic compounds, bacteria, and algae (37)•
78
-------
Chemical oxidation has been used to oxidize, organics in
industrial wastewaters. Among the organics for which oxidative
treatment has been reported are aldehydes, mercaptans, phenols,
benzidine, and unsaturated acids (38).
c. Analysis of Performance
The use of chemical oxidation in the specific treatment of
solvent bearing wastes is not documented. However, chemical
oxidation with hydrogen peroxide is used by a manufacturer of
chemical intermediates to pretreat a waste stream for removal of
a toxic proprietary compound, and in the course of that treatment
concentrations of toluene, ethylbenzene, chlorobenzene, and
1,2-dichlorobenzene in the waste are reduced by 70 to 95 percent.
However, it should be noted that the removal ..of the above sol-
vents is a secondary benefit of the oxidation process, which is
not implemented for their removal.
3. CHEMICAL REDUCTION
a. General Description
Chemical reduction processes are based on oxidation-reduction
reactions between waste components in aqueous solution and added
reducing agents. Chemical reduction is used to reduce the
hazardous components of a waste stream to less hazardous forms.
Reduction processes are used most extensively on aqueous waste
79
-------
streams that contain toxic metals, to reduce those metals to safer
elemental forms, which are then amenable to recycle or removal.
Chemical reduction technology has also been used on the
treatment of halogenated organics, and in this capacity could be
used to treat solvent wastes. However, the Agency is unaware of
this technology being used for the specific treatment of solvent
wastes. Nonetheless, sodium or potassium metal are used as
strong reducing agents to strip halogens from the halogenated
organics. This reduction is also referred to as dechlorination.
The majority of dechlorination research has been aimed at the
detoxification of highly chlorinated materials, such as polychlo-
rinated biphenyls (PCBs) and dioxins. However, strong reducing
agents such as sodium and potassium might be used to treat
halogenated solvents in the same manner. Reduction in this
manner is designed for non-aqueous wastes because of the reactive
nature sodium and potassium metal exhibit when mixed with water.
These reagents are dangerously reactive and have limited applica-
tion.
4. FUEL SUBSTITUTION
a. General Deaertntlon
There are numerous high temperature industrial processes that
are capable of destroying solvent wastes. In most cases, the
organic waste is used to supplement primary fuels such as natural
gas, fuel oil, or coal, thus lowering the total fuel cost
required for the process, and providing an inexpensive, efficient
80
-------
means of destroying wastes. The more predominant industrial
applications for this technology are discussed below.
(1) Industrial Boilers. A boiler is a closed vessel in which
water under pressure is transformed into steam by the application
of heat. Typically, heat is supplied by the combustion of
pulverized coal, fuel oil, or gas. These fuels are fired into a
combustion chamber with nozzles and burners that provide mixing
with air. Liquid wastes, and granulated solid wastes in the case
of grate-fired boilers, can be burned as fuels in a boiler by
using these wastes as auxiliary fuels. However, it has been
reported that few grate-fired boilers burn hazardous wastes,
because grate-fired boilers are not prevalent in the types of
industries that produce combustible wastes (39).
There are numerous designs and modes of operation for indus-
trial boilers. In fire tube boilers, the products of combustion
pass through tubes or flues that are surrounded by water.
Conversely, a water tube boiler allows the products of combustion
to pass over tubes that contain the water.
Some boilers, primarily small boilers, may not be equipped
with combustion controls sophisticated enough to maintain peak
combustion conditions when burning fuels the device was not
designed to burn. Finally, however, emissions testing demon-
strates that boilers can readily achieve good destruction of
toxic organics (i.e., 99.99 percent DRE).
81
-------
. In general, burning of solvent-containing wastes in indus-
trial boilers is economically attractive when the waste possesses
a heat content greater than or equal to 8,000 to.10,000 Btus per
pound (40). Viscosity is also an important physical parameter
for waste liquid injection systems, as discussed later in this
section under liquid injection incinerators. The waste must be
capable of being pumped and also of being atomized. Liquids with
dynamic viscosities of 10,000 SSU (23,000 centistokes) or less
are considered pumpable. The optimum viscosity for atomization
is considered to be 7,500 SSU (16,000 centistokes) (41, 42).
Deposition of fly ash and slag on heating surfaces in a
boiler can lead to serious fouling. Therefore, the boiler needs
to be capable of handling ash. Oil-fired boilers are designed to
be fired with oils containing less than 0.2 percent ash. Boilers
fired with coal are reportedly designed to handle fuels contain-
ing roughly 8 to 20 percent ash (43).
Another important waste characteristic that should be taken
into consideration is the chlorine content of the waste. Excess
quantities of chlorine may lead to unacceptable corrosion of the
unprotected metal surfaces within the boiler. Co-firing indus-
trial boilers with organic wastes is considered to be applicable
when the fuel mixture contains three percent or less chlorine
(44).
(2) Industrial Kilns. Combustible waste liquids may be used
to reduce fuel requirements in industrial kilns. Three types of
82
-------
kilns are particularly applicable: (1) cement kilns, (2) light-
weight aggregate kilns, and (3) lime kilns. There are other
types of high-temperature industrial processes, such as blast
furnaces and sulfur recovery furnaces that may also be used.
Light-weight aggregate kilns heat clay to produce an expanded
lightweight inorganic material, that is used in Portland Cement
formulations and other applications. The kiln has a temperature
range of 1,100°C to 1,150°C (2,000°F to 2,100°F) with a residence
time of 1.5 seconds. Combustible waste liquids are often used to
co-fire the kiln.
Clinker, a primary additive of cement, is manufactured in a
cement kiln, which is an application of rotary kiln technology.
The cement kiln is a refractory-lined steel shell used to calcine
a mixture of calcium, silicon, aluminum, iron, and magnesium.
These raw materials are crushed, blended, and fed to the kiln as
either a slurry or a dry mixture, thus the terms wet and dry
kilns. In the wet process, water is added to the raw materials
before they are ground. Over 50 percent of the cement kilns in
the United States use the wet technology. The kiln is usually
fired by coal or oil; liquid and solid combustible wastes then
serve as auxiliary fuel. Temperatures within the kiln are
typically between 1,380°C and 1,540°C (2,500°F and 2,800°F).
Lime (CaO) is manufactured in a calcination process using
limestone (CaCO^) or dolomite (CaCO^'MgCO^). These raw materials
are also heated in a refractory-lined rotary kiln to temperatures
83
-------
of 982°c to 1,260°C (1,800°F to 2,300°F). In general, rotary
kilns with residence times in excess of 1.5 seconds are used.
As with industrial boilers, industrial kilns will generally
accept wastes with sufficient heat content to promote combustion.
Literature values for acceptable heat content of wastes range
from 9,600 to 18,000 Btus per pound (45, 46). A limit is gener-
ally placed on the halogen (most specifically chlorine) content
of wastes used to fire aggregate kilns in order to minimize
scrubber liquor neutralization costs and corrosion of the scrub-
ber and its peripherals. For cement and lime kilns, product
quality degradation becomes a problem as the chlorine content of
the fuel increases. For cement kilns, this level is about 0.7
percent of the total fuel feed (47); for lime kilns, about 0.5
percent (48). Fuels with higher chlorine content may be blended
with fuels of lower chlorine content to obtain a fuel that will
not affect product quality.
b. Demonstration of Use fco Treat Solvents
Various industrial surveys and numerous field tests have
shown that solvent wastes are widely and successfully used to
co-fire industrial boilers and kilns. A summary of this data and
information is presented below.
According to an EPA survey of facilities that burned waste-
derived fuel material in 1983, 4,934 industrial boilers, and 868
industrial furnaces and kilns burned waste-derived fuel (49). A
large volume of the hazardous wastes burned in these devices
84
-------
contained chlorinated and nonchlorinated solvent constituents.
Data indicate that all of the solvent constituents listed in F001
and F005 wastes have been present in hazardous wastes burned as
fuel substitutes. However, because of their high chlorine
content, and resulting corrosivity, most F001 and F002 waste must
be blended with other organic wastes or fuel prior to burning,
c. Assessment-, nf Performance
The Agency conducted field tests at 11 full-scale industrial
boilers. As shown in Table B-2f the test facilities represented
a wide variety of boiler sizes, burning a variety of solvent
constituents (50). Further test burn data are available for
small commercial boilers (51). In these test burns, fuel oil was
spiked with selected organic compounds, including the volatiles
chloroform, 1,1,1-trichloroethane, trichloroethylene, and tetra-
chloroethylene, in addition to the semivolatiles trichloroben-
zene, dichloronaphthalene, and 2,4,5-trichlorophenol. A summary
of the solvent feed concentrations and boiler types is presented
in Table B-3.
Test burn data are also available from field tests conducted
at nine Industrial kilns. These facilities were utilizing
solvent wastes to co-fire kilns producing cement (both wet and
dry processes), lightweight aggregate, and lime. A summary of
the pertinent data for these kilns is presented in Table B-4.
The solvent constituents contained in the waste feed for the
test burns ranged from methanol and toluene wastes with a heating
85
-------
Table B-2
SOLVENT COMPOSITION OF WASTES INCINERATED IN
11 INDUSTRIAL BOILERS
(grams/liter)
Facility:
Boiler Type:
Design Fuel(a)
Site A
Hater Tube
Hood
Site B
Fire Tube
Gas
Site C
Water Tube
Oil and Gas
Site.D
Water Tube
Oil and Gas
Site E
Hater Tube
Oil and Gas
Avg. total heat Input at
test conditions (Billion
Btu's/hr):
_2J_
Ji.
Constituents:
acetone
n-butyl alcohol
carbon disulfide
carbon t^trachlwl^ ; Q.Q9 to 27
chlorobenzene
creaola
cyclohexanone
1.2-dlohlorobenzene
ND to 19
ethyl acetate
ethyl benzene
ethyl ether
lsobutanol
ae thanol
methylene chloride
methyl ethyl ketone
methyl lsobutvl ketone
700
nitrobenzene
pyridine
tetrachloroethylene
toluene
0.3 to 550
70 to 300
900
1.1.1-trlchloroethane
1.1.2-trlohloro-1,2,2-
trlfluoroethane
trlchloroethvlene
0.09 to SI
trlohlorofluorcsethane
xylene
Avg. higher heating value
(Btu/lb)
8.500
268 to 2,760
3.600
16.600
150
11.100
11.800
Haste Description
Creosote sludge
froo wood
preserving
Alkyd resin waste
from paint
manufacturing
-methyl styrene
diners and
phenolic and
benezene residues
Haste solvents
Third stage
bottoms from the
distillation of
crude methyl
methacrylate
Source: U.S. EPA. Engineering Assessment Renort: Hazardous Haste Coflrlng In Industrial Boilers. 198H.
-------
Table B-2 (Continued)
SOLVENT COMPOSITION OF WASTES INCINERATED IN
11 INDUSTRIAL BOILERS
(grams/liter)
Facility:
Boiler Type:
Design Fuel(s)
Site F
Water Tube
Coal, Oil, Gas
Site G
Fire Tube
Oil and Gas
Site H
Water Tube
Coal
Site I
Hater Tube
Oil and Gas
Site J
Fire Tube
Oil and Gas
Site K
Water Tube
Oil
Avg. total heat Input at
test conditions (nillion
Ptu'arttrh
-1L
^20
JLL
JjJL
-53_
Constituents:
acetone
n-butyl alcohol
oarbon disulfide
0 to 10
chlorobenzene
oresol s
cyclohexanone
1.2-dl chlorobenzene
1 to 6
26 to 49
0.01
1 to 5
0 to 9
ethyl acetate
ethylbenzene
ethyl ether
lsobutanol
methanol
methylene chloride
methyl ethyl ketone
methvl laobutvl ketone
nitrobenzene
pyridine
tetrachloroethylene
toluene
5 to 1Z
1
0.01
860
0.5 to 28
1.1.1-trichloroethane
1.1.2-trlchloro-l,2,2-
trifluoroethane
trichloroethvlene
8 to 61
20 to 40
0.02
9 to 18
0 to 8
t r1chlorof1uorone thane
xylene
Avg. higher heating value
(Btu/lb)
lit .000
9.000
6.800
10.600
17.900
0.2 to 16
18.000
Waste Description
Waste paint
thinner spiked
with solvents
(Not available)
Crude methyl
acetate spiked
lalvents
Waste stream
from the
production
of aniline
and aplked
Synthetic
mixture of
solvents
Off-spec
uaste fuel 3
ar.d llo. 6
fuel oil
spiked with
w/gol vents
sol vents
'specific gravity of fuel mixture Ik assumed to be equivalent to water
-------
Table B-3
SOLVENT CONCENTRATIONS IN WASTE OIL INCINERATED IN
SIX SMALL COMMERCIAL BOILERS
(grams/liter)
00
oo
Facility: Site k Boiler Site C Boiler Site D Boiler Site £ Boiler Site F Boiler Site G Boiler
Boiler Type: Caat Iron Horizontal Return Tube Fire Tube Fire Tube Fire Tube Fire Tube
Rated Capacity: 0.5 2.1 2.7 3.1 1.2 12.5
(million Btu/hr)
Solvent
Constituents:
Trlchloroethane 1 to 1.6 3 to 3.1 2.6 to 3.0 2.9 to 12.5 2.3 to 6.3 2.5 to 5.7
Trlohloroethylene 0.8 to 1.2 2.2 to 2.7 1.9 to 2.3 2-3 to 3-5 2.8 to 3.9 1.8 to 3.7
Tetractiloroethy 1 ene 1.5 to 6.3 1.0 to 1.2 2.2 to 8.5 2.8 to 9.1 0.71 to 7.7 2.6 to 7.6
Average Heat Content: The waste burned at eaoh site consisted of a basestock oil with a heating value of 16,180 BlU/lb, spiked with organlcs.
Waste Description: Used automotive oil spiked with organic compounds.
Note: Site B boiler was not available Tor testing In this program because of problems with burner assembly and fuel feed system.
Source: U.S. EPI. Environmental Characterization of Disposal of Haste Oils In Small Coabustera. 1981.
-------
Table B-4
SOLVENT COMPOSITION OF WASTES INCINERATED
IN SEVEN INDUSTRIAL KILNS
(grams/liter)
Facility: Site A1 Site B Site C Site D
Kiln Type: Pry Process Cement Net Process Cement Lightweight Aggregate Lime
Production (lb/hr) 150,000 60,000 20,000 17,000
Constituents:
acetone
n-butyl alcohol
carbon disulfide
carbon tetrachloride
13
7 to 18
2
3 to.4
chlorobenzene
creoaola
oyclohexanone
1.2-dlohl orobenzene
ethyl acetate
ethyl benzene
ethyl ether
iaobutanol
10
1 to 15
6 to 7
12 to 24
methanol
methylene chloride
methyl etbyl ketone
nethvl lsobutvl ketone
150
3 to 2t>
2 to 3
1 to 2
3
11
nltrobenzenz ene
pyridine
tetrach1oroethy1ene
toluene
WO
2.0 to 32
6 to 36
0.07 to 0.2
8
1,1,1-trichloroethane
1,1,2-triohloro-1,2,2-
trlfluoroethane
trichloroethvlene
to
0.6 to 12
0.7 to 5
2 to 3
2
trlchorof1uoroaethane
xylene
82
13 to 20
1 to 8
Heat Content (BTU/lb)
13,800
10,700 to 13,700
9,530 to 12,670
12,084 to 14 ,06'l
Waste Description
Mixed solvents
Mixed solvents
Solvents, alcohols,
Solvents, lacquer,
(85$ aromatic; IS ethers, still bottoms thinners, still
ohlorlnated) bottoms, alcohol,
paint waste
'specific gravity of fuel mixture la asstmed to be
Source: Engineering Science. Background Dooiment
equivalent to water
for Kiln Regulatory Iapact Analvala.
Prepared for U.S. EPA, Office of Solid Maste. 19BM.
-------
Table B-4 (Continued)
SOLVENT COMPOSITION OF WASTES INCINERATED
IN SEVEN INDUSTRIAL KILNS
(grams/liter)
Facility:
Klin Type:
Production (lb/hr)
Site E1
Dry Process Cedent
120,000
Site F
Dry Process Ceoent
120,000
Site G
Wet Process Cesent
120,000
Constituents:
aoetone
n-butyl alcohol
carbon disulfide
carbon tetrachloride
(2)
17 to 112
0.2 to 160
chlorobenzene
creoaols
cyclohexanone
1.2-dlohlorobenzene
ethyl acetate
ethyl benzene
ethyl ether
lsobutanol
(2)
7 to 15
31 to 203
¦ethanol
¦ethylene ohlorlde
aethyl ethyl ketone
oetlwl laobutvl ketone
(2)
27 to 63
75 to 89
(2)
4
49 to 110
19 to 330
0.7 to 9
nltrobenzenzene
pyridine
tet raohloroe thy1e ne
toluene
85 to 120
10 to 14
22 to ill
0.2 to 4
1.1.1-trlchloroethane
1.1.2-trlohloro-l,2,2-
trlfluoroethane
trlchloroe thvlene
160 to 2C0
10 to 11
16 to 23
trlchorofluorooethane
xylene
(2)
9 to 21
21
Heat Content (BTU/lb)
11,823 to 13,012
12,170 to 12,470
4,546 to 13,098
Waste Description
Solvent reclamation
still bottcas (2-5*
Hydrocarbon solvents
(2* Cl)
Degreasers and
pharmaceutical wastes
Cl)
'specific gravity of fuel mixture is assumed to be equivalent to uater
^Present but unquantlfied
-------
value similar to No. 6 fuel oil (and which was spiked with
chlorinated organics for test purposes) to methyl acetate waste
with a heating value of less than half that of No. 6 fuel oil
(and which was also spiked with chlorinated organics for test
purposes). The results of the tests showed that commercial and
industrial boilers along with industrial kilns can achieve
destruction and removal efficiencies of at least 99.99 percent.
This includes those organic compounds considered difficult to
burn, such as 1,1,1-trichloroethane, carbon tetrachloride,
chlorobenzene, trichloroethylene, and tetrachloroethylene. Also
destroyed were organic compounds that burn more easily such as
benzene, toluene, xylene, and nitrobenzene.
5. INCINERATION
a. General Doanrlptlon
There are many forms of incineration or thermal treatment,
but they all involve the nearly complete destruction of organic
waste materials by combustion at temperatures of approximately
600°C to 1,500°C. The two incineration methods most widely used
on a commercial basis are liquid injection and rotary kiln
incinerators. These two methods'are discussed in detail below.
There are other thermal destruction technologies that are not
widely demonstrated but that may also be applicable to wastes
containing hazardous organic solvents. These technologies
include fixed hearth, multiple hearth, and fluidized bed
91
-------
furnaces. Further discussion regarding these incineration
technologies can be found in the open literature.
(1) Liquid Injection. As the name suggests, liquid injection
incinerators are used to destroy pumpable wastes (<10,000 SSU or
23,000 centistokes) (52). Operating temperatures within the
incinerator are typically 650°C to 1,650°C (1,200°F to 3,000°F)
with residence times ranging from 0.5 to 2.0 seconds. Liquid
waste is injected into the incinerator through an orifice
designed to increase- the surface area of the liquid through
atomization. Atomization is generally accomplished using rotary
cup or pressure atomization nozzles. Design of the nozzles tends
to be waste-specific to ensure minimum droplet diameter. The
atomized liquid, in droplet form, is first vaporized in a primary
refractory-lined chamber. The waste is then combusted in a
secondary chamber, which is unfired.
Orientation of liquid injection incinerators may be either
vertical or horizontal. Wastes containing high concentrations of
inorganic salts and ash content are more appropriately inciner-
ated in vertically aligned units to allow for easier ash clean-
out. Furthermore, the vertical orientation has an advantage over
the horizontal type in that the incinerator may also function as
the emissions stack; however, the stack height then becomes
limited.
The turbulence of the liquid injection incinerator can be
increased by injecting the waste tangentially into the system.
92
-------
Often referred to as a cyclone furnace, this mode of operation
results in lower combustion temperatures, requiring smaller
auxiliary fuel requirements.
Liquid injection incinerators are applicable only to pumpable
liquids. Destruction efficiency depends on proper atomization of
the liquid, which is a function of liquid viscosity. For proper
atomization, the waste ideally should have a viscosity no greater
than 7»500 SSU (16,000 centistokes) (41, 42). If the waste is
too viscous, proper viscosities can usually be achieved through
heating, production of one- or two-phase emulsions, or solubiliz-
ing the waste in a lower viscosity liquid.
In addition, liquid injection may not be applicable to highly
corrosive or abrasive materials, or those containing high concen-
trations of suspended solids. Such wastes can interfere with the
proper operation of the atomization nozzle or orifice, greatly
reducing nozzle life and interfering with proper destruction.
Suspended solids content is a concern due to the potential of
plugging in the injection nozzle.
Although these waste characteristics are concerns, they are
not necessarily restrictive. By choosing and using the proper
injection system, these potential problems are minimized or
eliminated. In fact, the design and selection of injection
systems tends to be waste-specific. A typical commercial liquid
injection incinerator may be equipped with several injection
systems so that a variety of wastes can be introduced into the
93
-------
system. Utilizing several injection systems not only provides
flexibility, but it also allows noncompatible fluids to be
destroyed in the same system. If the incinerator is not equipped
with multiple ports, the injection system can be removed and
replaced with a system that is compatible with the particular
waste liquid to be incinerated.
(2) Rotary Ki1n. The rotary kiln is a versatile incineration
technology that is used to incinerate both solid and liquid
combustible wastes. A primary advantage of this technology is
that it accepts wastes that, because of their physical form,
cannot be treated with other incineration technologies. Contain-
erized wastes are routinely incinerated in rotary kilns.
The kiln is a refractory-lined, cylindrical shell, oriented
slightly off center from horizontal. Solid wastes, fuel, and air
are fed into the raised end so that the waste will move along the
length of the cylinder. Liquid wastes are fired horizontally
into the kiln. High combustion efficiency is maintained in the
kiln because of the continuous mixing of the unburned waste and
oxygen as the kiln rotates. The specific waste dictates combus-
tion temperature; however, the temperature range within the kiln
is typically 650°C to 870°C (1,200°F to 1,600°F). Residence
times range from seconds to hours depending on waste viscosity.
Entrainment of small particles from the tumbling action almost
always requires an afterburner or secondary combustion chamber to
ensure acceptable destruction and removal efficiencies.
94
-------
Temperatures within this afterburner normally range from 1,090°C
to 1f320°C (2,000°F to 2,400°F).
Rotary- kiln incineration is commonly applied to liquid, solid
and containerized wastes; however, wastes containing fusible ash
or inorganic salts may present a problem. At operating tempera-
tures of 870°C to 1,600°C (1,600°F to 2,900°), ash fusion and
slagging may occur if the waste contains inorganic salts.
Inorganic salts in this temperature range begin to soften and
melt, which allows them to agglomerate. This can interfere with
proper operation if the fused material attaches itself to the
kiln wall forming what is known as a ring. In addition, this
tacky material is carried over to the secondary combustion
chamber where it may settle out and begin to collect other
particulate matter.
Rotary kilns can be designed to operate below the ash fusion
temperature, where solids agglomeration is not a problem, or well
above the ash fusion temperature, so that the ash is discharged
from the system in a molten state. However, both of these
designs present certain technical problems that must be overcome
to ensure thorough destruction of the waste. Thus the optimum
waste for rotary kiln incineration would have an ash fusion
temperature higher than the operating temperature of the kiln,
b. Demonstration of Use to Troat Solvents
Incineration as a method of destroying organic wastes is
widely demonstrated. There are over 300 private and commercial
?5
-------
incineration units operating in the United States (53). Depend-
ing on the incineration technology, these units are capable of
destroying both halogenated and nonhalogenated organic constitu-
ents present in liquids, sludges, or solid waste streams.
Further, incineration technology is capable of treating wastes
with low solvent concentrations. For example, soils contaminated
with solvents can be treated through incineration by utilizing
auxiliary fuels to provide sufficient heat input yielding operat-
ing temperatures that promote thermal destruction. As the
organic content.of the waste increases, a general decrease in the
auxiliary fuel requirements is observed. Consequently, any waste
stream in theory containing organic solvents is applicable to
incineration technology.
The available data and information demonstrate that all of
the solvent constituents of concern have been or are currently
destroyed through incineration technology (54). These data and
information were obtained from the following sources:
1. SRI Directory of Chemical Producers (1982),
2. A telephone survey to verify Part A permit application
information,
3- Site visit reports for 15 hazardous waste incineration
facilities,
4. Regulatory Impact Analysis site visit reports for nine
hazardous waste incineration facilities,
96
-------
5. Responses to the EPA Office of Solid Waste Hazardous
Waste Incineration Questionnaire, and
6. A study performed for the Agency on the composition of
104 selected hazardous waste streams.
From these various information sources, detailed data on the
composition of 413 waste streams incinerated at 204 individual
facilities were obtained. The relevant information regarding the
solvent constituents of concern is summarized and presented in
Table B-5. As can be seen, incineration is demonstrated for each
of the constituents listed under hazardous waste codes F001
through F005. These data also show that 199 million gallons of
solvent waste were incinerated on a yearly basis at these 204
facilities.
C. Assessment of Performance
The current regulatory requirements for incinerators
requires, among other things, that a 99.99 percent destruction
and removal efficiency (DRE) be obtained for the principle
organic hazardous waste constituents (POHCs) contained in the
waste stream. Data obtained through trial burns for permit
applications and EPA research efforts have documented that
organic solvents can be destroyed to at least this level (53).
The determination of DRE requires the monitoring of organic
constituents in the waste feed stream and in the emissions
exiting the system. Evaluation of the other two residuals, ash
and wet air pollution control scrubber liquor, demonstrate they
97
-------
Table B-5
SOLVENT CONSTITUENTS PRESENT IN INCINERATED WASTE STREAMS
Amount
of Constituent
Number of Waste Streams Incinerated
Containing Constituent (milieu ftaHgng)
Constituents:
acetone
n-butyl alcohol
carbon disulfide
carbon tetrachloride
chlorobenzene
cresols
cydohexanone
1,2-dichlorobenzene
ethyl acetate
ethylbenzene
ethyl ether
isobutanol
methanol
methylene chloride
methyl ethyl ketone
methyl isobutyl ketone
nitrobenzene
pyridine
tetraohloroethylene
toluene
1.1.1-trichloroethane
1.1.2-tr^ohloro-1,2,2-trifluoro-
ethane
trichloroethylene
trichlorofluoromethane
xylene
TOTAL
80 17.2
9 32.3
3 0.128
9 0.547
21 6.18
8 5.92
4 0.344
2 0.240
24 9.62
6 0.264
2 0.248
9 4.50
95 44.4
26 5.84
54 14.0
10 4.68
3 0.0057
9 4.38
19 6.74
103 17.3
23 5.05
2 0.0008
15 3.69
2 0.401
78 15.2
199
1Data are reported for chlorinated fluorocarbons, not otherwise specified.
Source: Mitre Corporation. Composition of Hazardous Waste Streams Currently
Incinerated. Prepared for U.S. EPA, Office of Solid Waste. 1983«
98
-------
contain negligible quantities of the POHC present in the waste
feed stream. Solvent concentrations for the residuals from the
four full-scale incinerators are presented in Table B-6. The
analytical data shown for the ash samples are presented as the
maximum concentration of constituent that would be expected in
leachate from these residual samples. To calculate these concen-
trations, the total analysis data were used, and it was assumed
that a 100 gram ash sample was extracted by two liters of solu-
tion as is currently proposed by the EPA Extraction Procedure
(TCLP). Such a calculation allows for the direct comparison with
the screening levels proposed, which are to be evaluated against
data obtained from the leaching procedure. Such a comparison
indicates that ash and the scrubber liquor contain solvents below
the screening levels proposed.
Thus it can be seen that incineration technology can achieve
the near complete destruction of organic solvents. Furthermore,
the residuals produced from incineration meet the screening
levels proposed.
6. WET AIR OXIDATION
Wet air oxidation utilizes elevated temperature and pressure
to oxidize dissolved or suspended organic substances in aqueous
solution. The waste solution to be treated is fed to the treat-
ment system by a high-pressure pump. The waste is mixed with
compressed air, and passed through the cold, heat-up side of a
heat exchanger. The heated, incoming waste-air mixture exits
99
-------
Table B-6
RESIDUALS ANALYSIS AT FOUR FULL-SCALE INCINERATORS (mg/1)
SU* 0
o
o
Ash
Scrubber
Liquor
Site P
Site C
Ash
Scrubber
Liquor
Ash
1
Scrubber
Liquor
Constituent Concentration Concentration Concentration Concentration Concentration
carbon tetra-
chloride
chlorobenzene
cresols
methylene chlo-
ride
methyl ethyl
ketone
letrachloro-
ethylene
tol uene
1,1,1-trichloro-
ethane
<0.05
<0.010
<0.001
<0.010
<0.010
<0.010
<0.010
<0.010
<0.05-0.05
<0.05-0.1
0.2-0.7
<0.001
<0.001
<0.001-0.0026
<0.05
<0.05
<0.05-0.08
<0.05
0.211-1.8
<0.05
<0.001
<0.001
(2)
<0.001
(2)
<0.001
Site D
Scrubber
Ash 1 Liquor
Concentration
<0.002
0.001
<0.001
<0.001-0.013
<0.001
tilchloroethylene
<0.010
<0.05-0.1
<0.001
<0.05
<0.001
<0.001
Notes: ^Theoretical concentration if all of the constituents present in 100 grams of dry ash were completely extracted Into 2 liters or solution.
Concentration of compound in scrubber makeup water higher than concentrations in scrubber effluent.
Source: HHJ. Performance Evaluation of Full-Scale Hazardous Waste Incinerators. Volume IV. Prepared for U.S. EPA, Office of Solid Wasto. 1991.
-------
from the heat exchanger and enters a reactor where the oxygen in
the compressed air reacts with the organic matter in the waste.
The oxidation reaction is thermally self-sustaining with as low.
as 15 g/1 COD organic feed concentrations (56). After reaction,
the vapor and liquid phases are separated, and the liquid is used
as the heating fluid in the waste-feed heat exchanger.
The vapor product from the reactor consists of C02, N2, water
vapor, and volatile organics. Water is condensed and returned to
the reactor, along with condensible organics. Noncondensible
gases may be treated by conventional techniques, such as absorp-
tion, adsorption, or scrubbing.
Wet air oxidation differs from dry, thermal oxidation in that
water serves to modify the oxidation reactions so that they
proceed at relatively low temperatures, 175° to 325°C, and at the
same time serves to moderate the oxidation rates by removing
excess heat through evaporation. The rate of water evaporation
is controlled by maintaining the reactor system at high pressure.
Wet air oxidations are generally conducted at pressures between
300 and 3»000 psi (57). The oxidation reaction is exothermic and
energy recovery from exit streams may be practical, depending
upon the COD concentration in the waste-feed.
Higher temperatures tend to enhance the wet air oxidation
reaction. However, higher temperatures necessitate higher
process pressure to control the vaporization of water. Increased
temperatures and pressures increase corrosion, which is a
101
-------
fundamental problem in the reactor and associated heat exchang-
ers. Corrosion is controlled by the use of corrosion resistant,
materials such as titanium.
Catalysts are used in some wet oxidation reactions to lower
the temperature required for oxidation of a given fraction of
organic substances in any waste. Catalysts can also function to
increase conversions at a set temperature. One patented
co-catalyst system consists of bromide and nitrate anions in an
acidic, aqueous solution (58). Copper has also been used suc-
cessfully to catalyze wet air oxidations (57).
Wet air oxidation is most applicable to nonhalogenated
aqueous wastes containing less than two percent organics. By
using a catalyst this range can be extended another five percent
(59). It has been demonstrated that conventional wet air oxida-
tion is not effective in destroying all halogenated hydrocarbons
(60, 59, and 57). Empirical observations of particular compounds
susceptibility to conventional Wet air oxidation based on molecu-
lar structure indicate that (57):
a. Aliphatic compounds, even with multiple halogen atoms,
can be destroyed within conventional wet oxidation
conditions. Formulation of oxygenated compounds, such as
low molecular weight alcohols, aldehydes, ketones, and
carboxylic acids result, but these are readily biotreat-
able.
102
-------
b. Aromatic hydrocarbons, such as toluene, acenaphthene, or
pyrene, are easily oxidized.
c. Halogenated aromatic compounds can be oxidized, provided
there is at least one nonhalogen functional group present
on the ring, i.e., pentachlorophenol (-0H) or 2,4,6-tri-
chloraniline (-NH2).
d. Halogenated aromatic compounds, such as 1,2-dichloro-
benzene or PCB Aroclor 1254, are resistant under conven-
tional conditions.
Another researcher has reported that wet air oxidation can be
used for destroying PCBs and TCDD, two compounds that are normal-
ly resistant to this technology, if extreme conditions of time,
temperature, and catalyst concentrations are present (59).
b. Demonstration Status
Full-scale use of wet air oxidation technology is well-
demonstrated in the treatment of municipal sludge. One commer-
cial vendor reports that the majority of the 140-150 of their wet
air oxidation units in service are used for this purpose. By
oxidizing 5-10 percent of the COD present in the sludge, dewater-
ing characteristics of the sludge are greatly enhanced (61).
Full-scale treatment of solvent wastes using wet air oxida-
tion technology is not demonstrated. A 10 gpm pilot unit has
been used to oxidize various hazardous organic wastes at a
commercial waste treatment facility in California. Among the
103
-------
wastes treated with this pilot unit were an alkaline solvent
waste and a solvent still bottoms.
Bench-scale testing of wet air oxidation of hazardous, organ-
ics has been conducted and is reported in the literature.
Specific data are available on the wet air oxidation of carbon
tetrachloride, 1,2-dichlorobenzene, nitrobenzene, toluene, and
o-xylene.
C. Performance naha
Pilot-scale wet oxidation tests on solvent still bottoms at
a commercial waste treatment facility in California were just
recently completed at an average temperature of 268°C, 1,550 psig
pressure, and 118 minute residence time. COD, BOD, and DOC
reductions were 72.3, 73.6, and 47.4 percent, respectively (62).
In related bench-scale tests conducted on wastes at the same
facility, wet air oxidation was used to treat alkaline solvent
waste and solvent still bottoms. The results of those tests are
reported in Table B-6.
Bench-scale studies have also been conducted to evaluate the
performance of wet air oxidation in treating a number of specific
hazardous solvents. Those results are presented in Table B-7.
104
-------
Table B-6
BENCH-SCALE WET AIR OXIDATION PERFORMANCE DATA
TEST CONDITIONS: 280°
ONE HOUR RESIDENCE TIME
Waste
Alkaline Solvent
Solvent Still Bottcos
Parameter Ififid
COD, g/1 39.8
Total phenols, mg/1 840
COD, g/1 43.9
BOD, g/1 21.3
Effluent j Removal
7.5
20
8.6
6.3
81.2
97.6
80.4
70.4
Source: 63
105
-------
Table B-7
RESULTS OF BENCH-SCALE TESTS OF WET AIR OXIDATION
% Destroyed
99.99
99.99
2.98
32.2
69.1 1
18-31
46
99.73
<99.96
54.3
Sources:
1. 57
2. 58
TREATMENT OF SPECIFIC SOLVENTS
Carbon tetrachloride1
1,2-Dichlorobenzene
Nitrobenzene
1
Toluene
1
275 °C
275 C
275°C
27-5 ®C
320 C
200°C
250 C
275°C
275 C
Catalyst
Copper
Copper
Copper
Br-NO^-Mn
Copper
o-Xylene
165°C
106
-------
PART C
IMMOBILIZATION TECHNIQUES
Theoretically, any organic molecule (and, therefore, any
solvent) can be entrapped in an inorganic or organic matrix and
immobilized. The immobilization mechanism can be either chemical
fixation,, which is a chemical phenomenon, or encapsulation, which
is a physical phenomenon. These two immobilization techniques
are discussed, below.
1. CHFMTCAL FIXATION/SOLIDIFICATION
Fixation is a hazardous waste treatment system designed to
achieve one or more of the following goals: (1) improve waste
handling; (2) decrease surface area, thereby reducing potential
for breach of containment; and (3) limit solubility or toxicity
of hazardous waste constituents. Literally, chemical fixation
refers to the chemical interaction of waste constituents with a
binder. The result is a stable matrix in which the constituents
of concern are chemically bound and thus their mobility is
decreased.
Fixation systems can be broadly classified by the fixative
(binder material) used to incorporate the hazardous waste within
a stable matrix. These fixatives include power boiler fly ash,
cement kiln dust, cements, lime, and organic polymers.
To date, both organic and inorganic hazardous wastes have
been treated by fixation treatment systems in both field and
laboratory conditions. Generally, the success of the fixation
107
-------
system depends upon the compatibility of the waste with the
fixative material and the ability of the fixative to incorporate
the waste in a stable, secure matrix, thus preventing contaminant
loss. Fixation systems have been developed commercially, employ-
ing inorganic, organic, and mixed organic and inorganic fixa-
tives. They are not suitable for all types of wastes, however,
and organic wastes require particular care with regard to waste
composition and waste-to-fixative ratios. An EPA report ( )
concerning this treatment method states that organic wastes are
less amenable to currently available chemical fixation/solidifi-
cation methods than are organic wastes, and tha.t-wastes contain-
ing greater than 10 to 20 percent of organic constituents are not
generally recommended for treatment. Overall, fixation systems
have been used to treat mixed wastes from a variety of industrial
sources containing heavy metals and radioactive waste constitu-
ents, and a large body of literature exists discussing their
effectiveness.
The most important waste characteristics to determine treat-
ment applicability for chemical fixation are interfering inor-
ganics, organic content, and physical/chemical form. Very dilute
water-based waste streams are not applicable to fixation technol-
ogies. Generally, the higher the percent solids, the more
effective the fixation process.
Very high concentrations of some inorganics (i.e., copper,
sodium, sulfide, and zinc) can interfere with the fixation
108
-------
process and reduce the physical strength. It is possible to
pretreat to eliminate the interfering ions or to modify the
binder formulation to handle the interfering inorganics.
Data are not available that document the individual solvent
constituents present in wastes that have been treated by chemical
fixation or the ability of chemical fixation to fix organic
constituents in the matrix. More research is necessary in this
area to determine the extent to which this technique is applica-
ble to wastes containing organic constituents. Data for inor-
ganic constituents (e.g., metals) are usually cited.
2. ENCAPSULATION
Encapsulation of waste in a jacket of thermoplastics, glass,
cement, ceramic, polybutadiene, polyethylene, or other resins
offers promise as a waste treatment technology. As the name
suggests, this technology encases or surrounds the solidified
waste's surface by binding it in a rigid material such as those
listed above. In the strict sense, encapsulation provides a
physical surrounding to reduce the mobility of the waste constit-
uents. Quite often the term encapsulation is mistakenly used
interchangeably with fixation or solidification.
Encapsulation might be applied to most wastes that have been
sufficiently dewatered, such as dewatered sludge from physical-
chemical wastewater treatment processes. The technology involves
several steps, including additional dewatering, as needed,
coating of the waste particulates with resin, compaction and
109
-------
thermosetting of the wastes, and encapsulating the waste in a
binder block.
There are no data available to document the use of this
technology to treat solvent wastes. Conceivably, encapsulation
could be used to treat solids, such as soils, containing low
levels of solvents addressed in this rulemaking. However, more
work must be done in this area to determine the applicability of
encapsulation to these wastes.
110
-------
PART D
COMBINATIONS OF TREATMENT TECHNOLOGIES
As has been noted throughout this background document,
treatment technologies are commonly used together to treat
hazardous wastes. Table D-1 gives available data for various
treatment combinations for some of the solvents addressed in this
rulemaking.
ill
-------
Table D-1
AVERAGE PERFORMANCE OF FULL-SCALE TREATMENT FACILITIES
OPERATING MULTIPLE TREATMENT TECHNOLOGIES
FOR SOLVENTS OF CONCERN
(mg/1)
Compound
Chlorobenzene
1,2-Dlchl oro ben-
zene
Methylene chlo-
ride
Type of
Treatments
AS & AC
AS & AC
AS & AC
Average Influent
Concentration (Range)
6.59 (6.08-7.20)
2.82 (2.19-3.28)
3.85 (2.98-5.55)
Average Effluent
Concentration (Range)
Nitrobenzene
AS
&
AC
46.1 (1.21-90.5)
Toluene
AS
&
AC
9.34 (5.40-12.9)
SS
&
AS
8.92
SS
&
AS
5.45
AC
&
SS
6.13
Xylene
AC
&
SS
101
1
1
0.062 (0.035-0.080)
0.053 (0.035-0.072)
<0.010 (NA)1
0.026 (<0.010-0.038)
0.230-(<0.010-0.437)
0.040*
0.073,
<0.007
<0.005
1
1
10ffice of Solid Waste Analysis of Organic Chemicals, Plastics, and Synthetic
Fibers Industry Data Base.
2
USEPA. Development Document for Effluent Limitations Guidelines and Stan-
dards for the Iron and Steel Manufacturing Point Source Category. Volume
II. Office of Water Regulations and Standards, Effluent Guidelines Division.
EPA 440/1-80-024b. December 1980.
AS = Activated Sludge
AC s Granular Aotlvated Carbon Column
SS s Steam Stripping
NA s Not Applicable
112
-------
PART E
BIBLIOGRAPHY
1. MeteaIf and Eddy, Inc. 19 79. Wastewater Engineering: Treat-
ment, Disposal, Reuse. McGraw-Hill Book Company: New York.
2. U.S. Environmental Protection Agency. February 1985.
Physical-Chemical Properties and Categorization of RCRA
Wastes According to Volatility. Office of Air Quality
Planning and Standards. EPA-450/3-85-007.
3. Love, O.T. and R.G. Eilers. August 1982. "Treatment of
Drinking Water Containing Trichloroethylene and Related
Industrial Solvents." Journal American Water Works
Association.
4. Dyksen, J.E. and A.F. Hess. August 1982. "Alternatives for
Controlling Organics in Groundwater Supplies." Journal
American Water Works Association.
5. Symons, J.M. et:. al_. September 1981. Treatment Technigues
for Controlling Trihalomethanes in Drinking Water. EPA-600/
2-81-156.
6. Science Applications International Corporation. 1985.
Industry Studies Data Base. Prepared for U.S. E.P.A.,
Office of Solid Waste, Waste Identification Branch.
7. Stover, E.L. and D.F. Kincannon. June 1983. "Contaminated
Groundwater Treatability - Case Study." Journal American
Water Works Association.
8. U.S. Environmental Protection Agency. July 31, 1985. SUPERFUND
Records of Decision update. Office of Emergency and Remedial
Response, Hazardous Site Control Division.
9. McCarty, P.L. February 1980. "Organics in Water - An
Engineering Challenge. Journal of the Environmental
Engineering Division, 106, EE 1.
10. Administrative Record.. Notice of Availability of New
Information for Establishment of Effluent Guidelines for the
Organic Chemicals, Plastics, and Synthetic Fibers Industrial
Point Source Category.October 9, 1985.
U.,3 PA > t
11. U.S. Environmental Protection Agency. September 1983.
Development Document for Final Effluent Limitations Guide-
lines, New Source Performance Standards, and Pretreatment
Standards for The Pharmaceuticals Manufacturing Point Source
Category. , Effluent Guidelines Division.
Uv.S. £ PA J O-f^
113
-------
itm 14,
US'15-
*\3i5[ 16'
17.
18-
19.
20.
21.
22.
23.
U.S. Environmental Protection Aqency. November 1982.
Development Document for Expanded Best Practicable Control
Technology, Best Conventional Pollutant Control Technology,
Best Available Technology, New Source Performance Technology,
and Pretreatment Technology in the Pesticides Chemical
Industry. PB83-153171. Office of Water Regulations amd
Standards, Effluent Guidelines Division.
Allen, C.C. and B.L. Blaney. September 1985. "Case Studies
of Waste Treatment at Hazardous Waste Facilities." Incineration
and Treatment of Hazardous Waste; Proceedings of the 11th
Annual Research Symposium. EPA-600/9-85-028.
Engineering-Science. July 1985. Supplemental Report on
the Technical Assessment of Treatment Alternatives for
Waste Solvents. U.S. Environmental Protection Agency:
Washington, D.C.
ABT Associates. February 1985. National Small Quantity
Generator Survey. U.S. Environmental Protection Agency:
Washington, D.C.
Chemical Waste Management. April 1984. Hazardous Waste
Treatment Work Shop #3: Treatment and Recovery of Ignitables,
Solvents and Solvent-Bearing Wastes, EPA communication.
Berkowitz, J.B. £t al^. 1978. Physical, Chemical, and
Biological Treatment Technigues for Industrial Wastes.
Noyes Data Corporation: Park Ridge, New Jersey.
Roe, A. 1985. Calgon. Personal communication.
Perrich, J.R., ed. 1981. Activated Carbon Adsorption for
Wastewater Treatment. CRC Press, Inc: Boca Raton, Florida.
Yohe, T.L. et al_. August 1981.
Granular Activated Carbon Pilot
Water Works Association.
"Specific Organic Removals by
Contactors." Journal American
IT Enviroscience, Incorporated. April 1983. Survey of
Industrial Applications of Aqueous-Phase Activated-Carbon
Adsorption for Control of Pollutant Compounds from Manufacture
of Organic Compounds^ Prepared for USEPA, Industrial
Environmental Research Laboratory.
Dobbs, R.A. and J.M. Cohen. April 1980. Carbon Adsorption
Isotherms for Toxic Organics. USEPA, Municipal Environmental
Research Laboratory, EPA-600/8-80-023.
Meidl, J.A. June 1982. "PAC Process." Water Engineering and
Management.
114
-------
24. Browning, J.E. 1972. "New Water - Cleanup Roles for Powdered
Activated Carbon." Chemical Engineering, 79(4).
25. Torpy, M.F. et^ al_. 1982. "Activated Sludge Treatment and
Organic Characterization of Oil Shale Retort Water." Oil
Shale Symposium Proceedings, 15.
26. Argo, D.G. 1978. "Control of Organic Chemical Contaminants in
Drinking Water." Proceedings, Control of Organic Chemical
Contaminants in Drinking Water, Public Technology Incorporated/
EPA Seminar.
27. Hutton, D.G. 1979. "Removal of Priority Pollutants by the
DuPont PACT Process." Proceedings of the 7th Annual Industrial
Pollution Conference, Philadelphia, PA, June 5-7.
28. Baker, C.D. et al. 1973. "Recovery of p-cresol from Process
Effluent." AICE Symposium Series, ed. G.F. Bennett, Water,
70 (136).
29. Chriswell, C.D. e_t al_. 1979. "Comparison of Macroreticular
Resin and Activated Carbon as Sorbents." Journal American
Water Works Association, 69(12).
30. Fox, C.R. "Toxic Organic Removal from Waste Waters with
Polymeric Adsorbent Resins." 1979. Paper read at 86th National
American Institute of Chemical Engineer Meeting, Houston, Texas.
31. U.S. Environmental Protection Agency. May 1983 Treatment of
Volatile Organic Compounds in Drinking Water. Municipal
Environmental Research Laboratory, EPA-600/8-83-019.
32. Neely, J.W. and E.G. Isacoff. 1982. Carbonaceous Adsorbants
for the Treatment of Ground and Surface Waters. Marcel Dekker,
Incorporated. New York, NY.
33. Kiang, Y.S., and Metry A.A. 1982. Biological Treatment in:
Hazardous Waste Processing Technology. Ann Arbor Science
Publishers, Inc.: Ann Arbor.
34. Metcalf & Eddy, Inc. 1985. Technologies Applicable to Hazardous
Waste* Briefing presented for the U.S. Environmental Protection
Agency, Office of Research and Development, Hazardous Waste
Engineering Research Laboratory, Cincinnati, Ohio.
35. Pavoni, J.L., Heer, J.E., Jr., and Hagerty, D.L. 1975. Handbook
of Solid Waste Disposal Materials and Energy Recovery.
Von Nostrand Reinhold Environmental Engineering Series: New York
36. Dinges, R. 1982. Natural Systems for Water Pollution Control.
Von Nostrand Reinhold Environmental Engineering Series: New York,
115
-------
37
38
39
40
4 1
42
43
44
45
4 6
47
48,
49,
Webe r, W.J. , Jr.
Qaulity Control.
1972 .
Wiley
Physicochemical Processes for Water
- Interscienee: New York.
EPA-6 00/8-80-4 2c, 1980. ??
Olexsey, Robert A. 1984. Incineration of Hazardous Waste in
Power Boilers: Emissions Performance Study Rationale and Test
Site Matrix. Incineration and Treatment of Hazardous Waste,
Proceedings of the Tenth Annual Research Symposium, U.S.
Environmental Protection Agency.
McCormick, R., and Weitzman, L. 1984. Preliminary Assessement
of Costs and Credits for Hazardous Waste Cofiring in Industrial
Boilers * Incineration and Treatment of Hazardous Waste,
Proceedings of the Tenth Annual Research Symposium. U.S.
Environmental Protection Agency.
Hitchcock, D.A. 1979. Solid-Waste Disposal: Incineration.
Solid Waste Disposal Methods. Originally published in Chemical
Eng ineering.
Hooper, G.V. , ed. 1981. Offshore Ship and Platform- Incineration
of Hazardous Wastes, Pollution Technology Revision No. 79.
Noyes Data Corporation: Park Ridge, New Jersey.
Babcock and Wilcox. 1975. Steam, it's Generation and Use. 38th
ed.
Fred C. Hart Associates, Inc. August 1982. Impact of Burning
or Hazardous Waste in Boilers. Prepared for SCA Chemical Services
Inc., Boston, Massachusetts.
Frazier, J. July 1985. Norlite, Richmond, Virginia. Personal
Communication.
L-4v^S
-------
50. U.S. Environmental Protection Agency. 1984. Engineering
Assessment Report: Hazardous Waste Cofiring in Industrial
Boilers. EPA-600/2-84-177a arri b.
51. U.S. Environmental Protection Agency. 1984. Environmental
Characterization of the Combustion of Waste Oil in Small
Combustors. EPA 600/52-84-150, PQ/85-105-880.
52. Manson, L., and Unger S. 1979. Hazardous Material Incinerator
Design Criteria. U.S. Environmental Protection Agency - IERL. .
EPA-6 00/2-79-198.
53. U.S. Environmental Protection Agency. 1984. Supporting
Documentation for the RCRA Incineration Regulations. PB-86-
11-293.
54. Mitre Corporation. 1983. Composition of Hazardous Waste
Streams Currently Incinerated. Prepared for U.S. EPA,
Office of Solid Waste.
55. (no reference #55 in text)
56. Coda, W. et^ al. 19 84. Full Scale Demonstration of Wet Air
Oxidation as a Hazardous Waste Treatment Technology, Incineration
and Treatment of Hazardous Waste, Proceeding of the Ninth Annual
Research Symposium, EPA-600/9-84-015.
57. Randall, T.R., 1981. Wet Oxidation of Toxic and Hazardous
Compounds, Zimpro Inc. Technical Bulletin 1-610, Zimpro Inc.,
Rothschild, Wisconsin.
58. Miller, R.A., 1982. The Destruction of Various Organic
Substances By a Catalyzed Wet Oxidation Process. Incineration
and Treatment of Hazardous Waste, Proceeding of the Eighth
Annual Research Symposium, EPA-600/9-83-003.
59. Freeman, H. 1985. Innovative Thermal Hazardous Waste Treatment
Processes (Draft Document). Cincinnati, Ohio: U.S. Environ-
mental Protection Agency, Hazardous Waste Engineering Research
Laboratory, Office of Research and Development.
60. Mantell, C.L. 1975. Solid Wastes-Origin, Collection, Processing
and Disposal. New York. John Wiley and Sons.
61. Wilhelmi, A., Zimpro Inc., Personal Communication with Ron Dickson,
Radian Corporation, June 10, 19 85.
62. Canney, P.J. 1984, Commercial Demonstration of Wet Air Oxidation
of Hazardous Wastes Solvent Still Bottoms Waste Class, Casmalia
Resources/ Casmalia, CA. Report of Zimpro, Inc., Rothschild
Wisconsin. June 15, 1984.
117
-------
63a. Coda W. 1985, Demonstration of Wet Air Oxidation of Hazardous
Waste, Incineration and Treatment of Hazardous Waste, Proceedings
of the Tenth Annual Research Symposium.
63. Marston, K.R., and F.E. Woodard , 1985, Treatment of High
Strength Wastewater Containing Organic Solvents, Purdue
Industrial Wastewater Conference, Vol 39.
64. Kincannon, D.F., e_t al. , 1982, Compatability of Semiconductor
Industry Wastewater with Municipal' Activated Sludge Systems,
Purdue Industrial Wastewater Conference, Vol 39.
6 5. Kinca nnon, D. F. ,. e_t al_. , 19 83, Removal Mechanisms for Toxic
Priority Pollutants, Journal WPCF, Feb. 1983, Vol. 55, p. 157
66. Torpy, M.F., L.A. Raphaelian, and R.G. Luthy, 1981, Wastewater
and Sludge Control-Technology Options for Synfuels Industries,
Vol. 2: Tar-Sand-Combustion Process Water - Removal of
Organic Constituents by Activated - Sludge Treatment, Argonne
National Laboratory ANL/ES-115, Vol. 2.
68. U.S. EPA, 1979, Selected Biodegradation Technigues for Treatment
and/or Ultimate Disposal of Organic Materials. EPA-600/2-79-006.
69. Tabak, H.H., et al., 1981, Biod egrad ability Studies with Organic
Priority Pollutant Compounds, Journal WPCF, October 1981, Volume
53, p. 1503.
118
------- |