EPA/625/8-87/014
September 1987
COMPENDIUM OF
TECHNOLOGIES
USED IN THE TREATMENT
OF
HAZARDOUS WASTES
Center for Environmental Research Information
Office of Research and Development
U.S, Environmental Protection Agency
Cincinnati, OH 45268
Printed on Recycled Paper
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DISCLAIMER
This Information has been reviewed in accordance with the U.S. Environmental Protection Agency's
administrative review policies and approved for presentation and publication. Mention of trade names
or commercial products does not constitute endorsement or recommendation for use.
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CONTENTS
Disclaimer , .'... ; jj
Acknowledgement ; '. v
FOREWORD ; vii
PHYSICAL TREATMENT PROCESSES 1
Sedimentation 3
Centrifugation , 4
Flocculation v 5
Oil/Water Separation .'. 5
Dissolved Air Flotation 6
Heavy Media Separation , Q
Evaporation 7
Air'Stripping 8
Steam Stripping : 9
Distillation , 10
Soil Flushing/Soil Washing 11
Chelation ..' n
Liquid/Liquid Extraction 11
Supercritical Extraction........ 12
Filtration............ 13
Carbon Adsorption 14
Reverse Osmosis 15
Ion Exchange 16
Electrodialysis 16
CHEMICAL TREATMENT PROCESSES ...:.. 17
Neutralization ; 18
Chemical Precipitation 19
Chemical Hydrolysis 20
Ultraviolet Photolysis 20
Chemical Oxidation (Chemical Reduction) 21
Oxidation by Hydrogen Peroxide (H2O2) 21
Ozonation 22
Alkaline Chlorination 22
Oxidation by Hypochlorite 22
Electrolytic Oxidation 23
Catalytic Dehydrochlorination 23
Alkali Metal Dechlorination 24
Alkali Metal/Polyethylene Glycol (A/PEG) 24
iii
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CONTENTS (Continued)
BIOLOGICAL PROCESSES - 25
Aerobic Biological Treatment ........ 26
Activated Sludge : .-.......; 27
Rotating Biological Contactors ... 28
Bloreclamation 28
Anaerobic Digestion : 29
White-rot Fungus 30
THERMAL DESTRUCTION PROCESSES 31
Liquid Injection Incineration 32
Rotary Kiln Incineration 33
Fluidized Bed Incineration , 34
Pyrolysis 35
Wet Air Oxidation 36
Industrial Boilers 36
Industrial Kilns (Cement, Lime, Aggregate, Clay) 37
Blast Furnaces (Iron and Steel) :.... 37
Infrared Incineration 38
Circulating Bed Combustor , 39
Supercritical Water Oxidation 40
Advanced Electric Reactor ;...., 40
Molten Salt Destruction 41
Molten Glass 42
Plasma Torch .43
FIXATION/STABILIZATION PROCESSES ,..:...:... 45
Lime-Based Pozzolan Processes 46
Portland Cement Pozzolan Process .-. : 46
Sorption -. 47
Vitrification 47
Asphalt-Based (Thermoplastic) Microencapsulation 48
Polymerization 48
BIBLIOGRAPHY '. 49
IV
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ACKNOWLEDGEMENT
This document was prepared by PEER Consultants, P.C., under EPA Contract No. 68-03-3312. The de-
scriptions of technologies, their status and applicabilities are the result of the efforts of many contrib-
utors, notably the participants of the RCRA/CERCLA Alternative Treatment Technology Seminars, and
the staffs of the Center for Environmental Research Information and of the Hazardous Waste Engi-
neering Research Laboratory.
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FOREWORD
This document is intended to serve as an introduction to available technologies which can be used in
the treatment of hazardous wastes. In the context of this document, hazardous wastes include RCRA-
regulated wastes, such as would come from a generator or storage facility, as well as those wastes
which have contaminated some other medium, such as soil or groundwater, and thus, would be con-
sidered "CERCLA wastes." It should be noted that no one of the waste treatment technologies presented
is a stand-alone process. Any treatment scenario utilized for hazardous waste must include a process
line made up of several of the treatment processes discussed herein.
While the contents of this document are not exhaustive, it is believed that most treatment processes
available now and in the near future are discussed. Each technology discussion includes a description
of the basis of the technology, a brief discussion of the applicability and limitations of that technology,
the status of the technology, a non-exhaustive listing of sources (vendors, suppliers or developers) of
the technology and when appropriate, a process diagram for a typical application of that technology.
Furthermore, for many of the technologies, a tabular listing of specific data needed by an engineer
designing a treatment system is included.
Technologies are categorized on the basis of whether they are considered physical treatment, chemical
treatment, biological treatment, thermal treatment (incineration) or stabilization/fixation. Obviously, there
is overlap in the minds of many regarding the categorization of the different technologies. For example,
some people consider UV photolysis to be a physical process because of the necessity for ultraviolet
irradiation while others merely consider it hydrolysis wherein the activation energy is supplied by the
UV irradiation. In this document the latter view is taken. Similarly, the fixation/stabilization processes
are all either physical or chemical processes. However, the purpose for their use, the design factors for
consideration and the requirements on their end product are so unique that it is felt that these processes
deserved separate treatment.
The source list for each technology is admittedly incomplete/The list is not intended in any way to
endorse the vendors on the list, nor is it a commentary on any capabilities of vendors not listed. The
list is supplied partly as a convenience to the reader, but primarily as an indicator of the overall avail-
ability of that type of technology. In the case where the number of known vendors is exceedingly large
the reader is referred to other sources such as annual buyer's guides published in trade and professional
journals. ,
vii
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PHYSICAL TREATMENT PROCESSES
The processes described herein are those which utilize physical characteristics to effect a separation
or concentration of constituents in a waste stream. The processes are organized into four groupings
according to their physical basis, i.e., separation by gravity, separation by phase change, separation by
dissolution and separation by size, adsorptivity, or ionic characteristics.
Gravity Separation:
Sedimentation
Centrifugation
Flocculation
Oil/Water Separation
Dissolved Air Flotation
Heavy Media Separation
Phase Change:
Evaporation
Air Stripping
Steam Stripping
Distillation
Dissolution:
Soil Washing/Flushing
Chelation
Liquid/Liquid Extraction
Supercritical Solvent Extraction
Size/Adsorptivity/lonic Characteristics:
Filtration
Carbon Adsorption
Reverse Osmosis
Ion Exchange
Electrodialysis
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Data Need
Important Physical Treatment Data Needs
Purpose
Absolute Density
Bulk Density
Size Distribution
Friability
Solubility
(In H2O, organic solvents, oils, etc.)
Specific Gravity
Viscosity
Water Content
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TECHNOLOGY: Sedimentation
DESCRIPTION: Sedimentation is a gravity set-
tling process which allows heavier solids to col-
lect at the bottom of a containment vessel
resulting in its separation from the suspending
fluid. This type of operation can be accom-
plished using a batch process or a continuous
removal process. There exist several physical ar-
rangements in which the sedimentation process
can be applied. These are represented in the dia-
gram shown. The top diagram illustrates a set-
tling pond wherein aqueous waste flows through
while the suspended solids are permitted to
gravitate and settle out. Occasionally the set-
tled particles (sludges) are removed so this sys-
tem would be considered a semi-batch process.
The middle figure shows a circular clarifier
equipped with a solids removal device to facili-
tate clarification on a continuous process basis
resulting in a lower solids content outlet fluid.
The third type is a sedimentation basin, as
shown in the bottom diagram. It uses a belt-type
solids collector mechanism to force the solids
to the bottom of the sloped edge of the basin
where they are removed. The efficiency of sedi-
mentation treatment is dependent upon the
depth and surface area of the basin, settling
time (based on the holding time), solid particle
size and the flow rate of the fluid.
APPLICABILITY/LIMITATION: Sedimentation is
considered to be a separation process only, and
typically, some type of treatment process for the
aqueous liquid and the sludges will follow. Its
use is restricted to solids that are more dense
than water and it is not suitable for wastes con-
sisting of emulsified oils.
STATUS: Conventional
SOURCES: Chemical Waste Management Inc.
Dorr Oliver
Eimco Process Equipment Co.
Wyo Ben Inc.
National Hydro Systems Inc.
Sharpies Stokes Div Pennwalt
Water Tech Inc.
AFL Industries
Important Sedimentation Data Needs
Data Need Purpose
Viscosity of
aqueous waste
Oil and grease
content of
waste stream
Specific gravity of
suspended solids
High viscosity hinders
sedimentation
Not applicable to
wastes containing
emulsified oils
Must by greater than
1 for sedimentation to
occur
REPRESENTATIVE TYPES OF SEDIMENTATION
Setting Pond
Inlet Liquid
Revolving Collection
Mechannm
/ Uqrtl
nrf^l^lx'TTTT
tion^^a
Periodically Removed by Machinical Shovel
Circular Baffle
Annular Overflow Weir
Settling Particles
Settled Particte* 1 Collected and Periodically Removed
I Sludge OrovvoH
Sedimentation Basin
Inlet Zone -,
Settled Particles Collected
and Periodically Removed
or
V Belt-Type Solids Collection Mechanism
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TECHNOLOGY: Centrifugation
DESCRIPTION: Centrifugation is a physical sep-
aration process in which the components of a
fluid mixture are separated, based on their rel-
ative density, by rapidly rotating the fluid mix-
ture within a rigid vessel. Solid particles that are
denser than the fluid medium are deposited far-
thest from the axis of rotation while the liquid
supernatant lies separated near the axis. Cen-
tripetal forces in Centrifugation are similar to
gravitational forces in sedimentation except that
centripetal forces are thousands of times
stronger than gravitational forces, depending
upon diameter and rotational speed of the
centrifuge.
AVAILABILITY/LIMITATION: This treatment is
limited to dewatering sludges (including metal-
bearing sludges), separating oils from water, and
clarification of viscous gums and resins. Cen-
trifuges are generally better suited than vacuum
filters for dewatering sticky or gelatinous
sludges. Disc-type centrifuges can be used to
separate three-component mixtures (e.g., oil,
water, solids). Centrifuges often cannot be used
for clarification since they may fail to remove
less dense solids and those which are small
enough to remain in suspension. Recovery and
removal efficiencies may be improved if paper
or cloth filters are incorporated in the
centrifuges.
STATUS: Commercially available
SOURCES: Clinton Centrifuge Inc.
ALFA Laval Inc.
Tetra Recovery Systems
Dorr-Oliver Inc.
Bird Environmental Systems
Western States Machine
Fletcher
Astro Metallurgical
Barrett Centrifugals
Donaldson Co. Industrial Group
Donaldson Co. Liquid Sys. Div.
GCI Centrifuges
General Productions Svcs Inc.
IT Corp.
Ingersoll Rand Environmental
Master Chemical Corp. Sys. Equip.
Sartorius Bal Div. Brinkmann
Sharpies Stokes Div.
Pen n wait
Tekmar Co.
Thomas Scientific
BASKET CENTRIFUGE
Basket Wall
Filter Paper
(Used With
Perforated Walt)
Revolving
Bukel Frame
Solid bowl centrifuge.
Drive Assembly
Rotor Drive Assembly
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TECHNOLOGY: Flocculation
DESCRIPTION: Flocculation is a treatment
technology which is used to enhance sedimen-
tation or centrifugation. The waste stream is
mixed while a flocculating chemical is added.
Flocculants adhere readily to suspended solids
and with each other (agglomerate) so that the
resultant particles are too large to remain in sus-
pension. Flocculation is primarily used for the
precipitation of inorganics.
AVAILABILITY/LIMITATION: The extent of com-
pletion of flocculation is dependent upon the
flow rate of the waste stream, its composition
and its pH. This process is not recommended
for a waste stream with high viscosity.
STATUS: Conventional, demonstrated
SOURCES: Refer to buyer's guides
Important Flocculation Data Needs
Data Need Purpose
pH of waste
Viscosity of
waste system
Settling rate of
suspended solids
Selection of
flocculating agent
Affects settling of
agglomerated solids;
high viscosity not
suitable
Selection of
flocculating agent
TECHNOLOGY: Oil/Water
Separation
DESCRIPTION: As in sedimentation, the force
of gravity can be used to separate two (or more)
immiscible liquids having sufficiently different
densities, such as oil and water. Liquid/liquid
separation occurs.when the liquid mix is al-
lowed to settle. Thus, flow rates in continuous
processes must be kept low. The waste flows
into a chamber where it is kept quiescent and
permitted to settle. The floating oil is skimmed
off the top through the use of an oil skimmer
while the water or effluent flows out the lower
portion of the chamber. Acids may be used to
break an oil/water emulsion and enhance this
process to allow for greater efficiency in re-
moval of the oil.
AVAILABILITY/LIMITATION: The effectiveness
of the separation process can be influenced by
the waste stream's rate of flow, temperature, and
pH. Separation constitutes a pretreatment proc-
ess if the oil skimmings require further
treatment.
STATUS: Mobile phase separators are commer-
cially available
SOURCES: Refer to buyer's guides
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TECHNOLOGY:
Dissolved Air
Flotation
DESCRIPTION: Dissolved air flotation is a phys-
ical process whereby suspended particles or
mixed liquids can be removed from an aqueous
waste stream. The mixture to be separated is
saturated with air (or some other gas such as
nitrogen) and typically the pressure is reduced
above the treatment tank. As air then comes out
of solution, the microbubbles which form can
readily adsorb onto suspended solids or oils,
enhancing their "flotation" characteristics. In
the flotation chamber, separated oil or other
"floats" are skimmed off the top while the
aqueous liquids flow off the bottom.
AVAILABILITY/LIMITATION: This technology is
only applicable for waste having densities close
to that of water. Air emission controls may be
necessary if hazardous volatile organics are
present in the waste.
STATUS: Conventional
SOURCES: Refer to buyer's guides
AIR/SOLIDS MIX
RECYCLE
^g LIQUID
<- PRESSURIZED .., , .
AIR BUBBLES (SLUDGE)
SOURCE; PEABODY-WELLES,
ROSCOE.IL,
RECYCLE FLOW DISSOLVED AIR FLOTATION
SYSTEM
TECHNOLOGY: Heavy Media
Separation
DESCRIPTION: Heavy media separation is a
process for separating two solid materials which
have significantly different absolute densities.
The mixed solids to be separated are placed into
a fluid whose specific gravity is chosen (or ad-
justed) so that the lighter solid floats while the
heavier sinks. Usually, the separating fluid (the
heavy media) is a suspension of magnetite in
water. Specific gravity of the fluid is thus ad-
justable by varying the amount of magnetite
powder used. Magnetite can be easily recovered
magnetically from rinsewaters and spills and
then reused.
AVAILABILITY/LIMITATION: This type of sepa-
ration is readily used for separating two insolu-
ble solids having different densities. Limitations
include the possibility of dissolving solids and
ruination of the heavy media, the presence of
solids of similar density to those whose sepa-
ration is desired and the inability to cost-
effectively separate magnetic materials (be-
cause of the need to recover magnetite).
STATUS: Commonly used in the mining industry
to separate ores from tailings
SOURCES: Tetra Recovery Systems
Enviro-Chem Waste Management
Service
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TECHNOLOGY: Evaporation
DESCRIPTION: Evaporation is the physical sep-
aration of a liquid from a dissolved or sus-
pended solid by the application of energy to
volatilize the liquid. In hazardous waste treat-
ment, evaporation may be used to isolate the
hazardous material in one of the two phases,
simplifying subsequent treatment. If the hazard-
ous material is in the volatilized phase, the proc-
ess is usually called "stripping." (See Air
Stripping.)
AVAILABILITY/LIMITATION: Evaporation can be
applied to any mixture of liquids and nonvolatile
solids provided the liquid is volatile enough to
evaporate under reasonable heating or vacuum
conditions (both the liquid and the solid should
be stable under those conditions). If the liquid
is water, evaporation can be carried out in a large
pond provided with solar energy. Evaporation of
aqueous wastes can also be done in closed
process vessels with energy provided by steam
and the resulting water vapor can be condensed
for possible reuse. Energy requirements are usu-
ally minimized by such techniques as vapor re-
compression or multiple effect evaporators.
Evaporation is applied to solvent waste contam-
inated with nonvolatile impurities such as oil,
grease, paint solids or polymeric resins. Me-
chanically agitated or wiped thin film evapora-
tors are used. Solvent is evaporated and
recovered for reuse. The residue is the bottom
stream, typically containing 30 to 50% solids.
STATUS: Commercially available
SOURCES: Resources Conservation Company
(mobile brine concentration
systems)
Kipin Industries
APV Equipment Inc.
Ambient Tech. Div. Ameribrom Inc.
Analytical Bio Chem Labs
Aqua Chem Water Technologies
Capital Control Co., Inc.
Dedert Corp.
HPDInc.
Industrial Filter & Pump Mfg.
Kimre Inc.
Kontro Co., Inc.
Lancy International Inc.
Licon Inc.
Rosenmund Inc.
Sasakura Intl American Corp.
Spraying Systems Co.
Votator Anco Votator Div.
Wallace & Tiernan Div. Pennwalt
Wastesaver Corp.
Weathermeasure Weathertronics
Wheaton Instruments
Distilled Vapor
Steam
Steam Condensate
Concentrated Liquid
Typical Single Effect Evaporatorpalling Film Type
Tvpical Multi-effort (Tripla Effect) Evaporator-Falling Film Tvpa
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TECHNOLOGY: Air Stripping
DESCRIPTION: Air stripping is a mass transfer
process in which volatile contaminants, in water
or soils, are evaporated into the air. Factors im-
portant in removal of organics from wastewater
via air stripping are temperature, pressure, air to
water ratio and surface area available for mass
transfer. Air to water volumetric ratios may range
from 10:1 up to 300:1. The resulting residuals are
the contaminated off gas and the stripped ef-
fluent. Volatilized hazardous materials must be
recaptured for subsequent treatment to pre-
clude air pollution concerns.
AVAILABILITY/LIMITATION: This process is
used to treat aqueous organic waste with rela-
tively high volatility, low water solubility (e.g.,
chlorinated hydrocarbons such as tetrachloro-
ethylene) and aromatics (such as toluene). Lim-
itations Include the fact that the process is
temperature dependent so that stripping effi-
ciency can be impacted by changes in ambient
temperature and the presence of suspended sol-
ids may reduce efficiency. If the concentration
of VOCs exceeds approximately 100 ppm, some
other separation process (e.g., steam stripping)
Is usually preferred.
STATUS: Commercially available
SOURCES: OH Materials
Carbon Air Services
Detox Inc.
IT Corporation
Oil Recovery Systems Inc.
Resource Conservation Company
Terra Vac Inc.
Advanced Industrial Technology
Baron Blakeslee Inc.
Beco Engineering Co.
Calgon Carbon Corp.
Chem Pro Corp.
D. R. Technology Inc.
Delta Cooling Towers
Detox Inc.
Hydro Group Inc.
IPC Systems Inc.
IT Corp.
Kim re Inc.
Munters Corp.
NEPCCO
North East Environmental Prods.
Oil Recovery Systems Inc.
Tri-Mer Corp.
Wright R.E. Associates Inc.
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TECHNOLOGY: Steam Stripping
DESCRIPTION: The operation of steam strip-
ping uses steam to evaporate volatile organics
from aqueous wastes. Steam stripping is essen-
tially a continuous fractional distillation process
carried out in a packed or tray tower. Clean
steam, rather than reboiled bottoms, provides
direct heat to the column in which gas flows
from the bottom to the top of the tower. The
resulting residuals are contaminated steam con-
densate, recovered solvent and stripped ef-
fluent. The organic vapors and the raffinate are
sent through a condenser in preparation for fur-
ther purification treatment. The bottoms will re-
quire further consideration as well. Possible
post-treatments may include incineration, car-
bon adsorption and land disposal.
AVAILABILITY/LIMITATION: Steam stripping is
used to treat aqueous wastes contaminated with
chlorinated hydrocarbons, aromatics such as
xylenes, ketones such as acetone or MEK, al-
cohols such as methanol and high boiling point
chlorinated aromatics such as pentachloro-
phenol. Steam stripping will treat less volatile
and more soluble wastes than will air stripping
and can handle a wide concentration range (e.g.,
from less than 100 ppm to about 10 percent or-
ganics). The steam stripping process requires
some type of air pollution control (ARC) mech-
anism to eliminate toxic emissions.
STATUS: Conventional, well demonstrated
SOURCES: Refer to buyer's guides
STEAM STRIPPING COLUMN-
PERFORATED TRAY TYPE
^ Organic
Vapors
Liquid
Feed
Sieve
Tray
Cartridge
Support
Rods
Downcomer
Heat
Flow
Steam
Stripped
Effluent
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TECHNOLOGY: Distillation
DESCRIPTION: Distillation is simply the proc-
ess of evaporation followed by condensation
whereby separation of volatile materials can be
optimized by controlling both the evaporation-
stage temperature (and pressure) and the con-
denser temperature. Distillation separates mis-
cible organic liquids for solvent reclamation and
for waste volume reduction. The resulting resid-
uals are still-bottoms (often containing toxic
metals from ink and paint pigments) and inter-
mediate distillate cuts. Two major types of dis-
tillation processes are batch distillation and
continuous fractional distillation.
AVAILABILITY/LIMITATION: Distillation is used
to separate liquid organic wastes, primarily
spent solvents, for full or partial recovery and
reuse. Both halogenated and nonhalogenated
solvents can be recovered via distillation. Liq-
uids to be separated must have different volatil-
ities. Distillation for recovery can be limited by
the presence of either volatile or thermally re-
active suspended solids. If constituents in the
Input waste streams can form an azeotrope (a
specific mixture of liquids exhibiting a maxi-
mum or minimum boiling point with the individ-
ual constituents) then the energy cost of
breaking the azeotrope can be prohibitive.
Batch distillation in a heated still pot with con-
densation of the overhead vapors is easily con-
trolled and flexible, but cannot achieve the high-
product purity typical of continuous fractional
distillation. Small packaged batch stills treating
Bptch distillation.
Feed-*-
Batch
Suit
Condenser
Partial Recycle
Accumulator
V
1 » Disti
Distillate
Steam
^ Condensate
Bottom
Product
one drum per day or less are becoming popular
for on-site recovery of solvents. Continuous frac-
tional distillation is accomplished in tray col-
umns or packed towers ranging up to 40 feet in
diameter and 200 feet high. Each is equipped
with a reboiler, a condenser and an accumula-
tor. The capacity of a unit is a function of the
waste being processed, purity requirements, re-
flux ratio and heat input. Fractional distillation
is not applicable for liquids with high viscosity
at high temperature, liquids with a high-solids
concentration, polyurethanes and inorganics.
STATUS: Commercially available
SOURCES: Exceltech, Inc.
Kipin Industries
Mobil Solvent Reclaimers, Inc.
APV Equipment Inc.
Ace Glass Inc.
Artisan Industries Inc.
Gilmont Instruments Inc.
Glitsch Inc.
Hoyt Corp.
Licon Inc.
Progressive Recovery Inc.
Rosenmund Inc.
Sutcliffe Croftshaw
Tekmar Co.
Thomas Scientific
Vara International Inc.
Vic Mfg Co. Industrial Div.
Wheaton Instruments
. York Otto H. Co., Inc.
CONTINUOUS FRACTIONAL DISTILLATION
Accumulator
Distillate
Perforated Tray Type
Distillation Plate
10
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TECHNOLOGY: Soil Rushing/
Soil Washing
DESCRIPTION: Soil flushing is an in-situ extrac-
tion of inorganic or organic compounds from
soils and is accomplished by passing extractant
solvents through the soils using an injection/
recirculation process. These solvents may in-
clude: water, water surfactant mixtures, acids or
bases (for inorganics), chelating agents, oxidiz-
ing agents or reducing agents. Soil washing
consists of similar treatments, but the soil is
excavated and treated at the surface in a soil
washer.
AVAILABILITY/LIMITATION: Soil flushing/wash-
ing fluids must have good extraction coeffi-
cients, low volatility and toxicity, be safe and
easy to handle, and (most important), be re-
coverable/ recyclable. This technology is very
promising for extraction of heavy metals from
soils, although problems are likely in dry, or in
organic-rich soils. Surfactants can be used to
extract hydrophobic organisms. Soil character-
istics such as type and uniformity are important.
Certain surfactants, when tested for in-situ ex-
traction, clogged soil pores and precluded fur-
ther flushing.
STATUS: U.S. EPA Edison, New Jersey, has mo-
bile soil washer, other systems are under
development
SOURCES: Critical Fluid Systems
IT Corp.
TECHNOLOGY: Chelation
DESCRIPTION: A chelating molecule contains
atoms which can form ligends with metal ions.
If the number of such atoms in the molecule is
sufficient and if the final molecular shape is
such that the metal atom is essentially sur-
rounded then the metal will not be able to form
ionic salts which can precipitate out. Thus, che-
lation is used to keep metals in solution and to
aid in dissolution for subsequent transport and
removal (e.g., soil washing).
APPLICABILITY/LIMITATION: Chelating chemi-
cals can be chosen for their affinity to particular
metals (e.g., EDTA and calcium). The presence
of fats and oils can interfere with the process.
STATUS: Chelating chemicals are commercially
available
SOURCES: Refer to buyer's guides
TECHNOLOGY: Liquid/Liquid
Extraction
DESCRIPTION: Two liquids which are well mixed
or are mutually soluble may be separated by liq-
uid/liquid extraction. The process requires that
a third liquid be added to the original mix. This
third liquid must be a solvent for one of the orig-
inal components, but must be insoluble in and
immiscible with the other. The final solvent/sol-
ute stream can be subsequently separated by
distillation or by chemical means and the ex-
tracting solvent captured for reuse.
AVAILABILITY/LIMITATION: Complete separa-
tion is rarely achieved, so that some form of post-
treatment is required for each separated stream.
To effectively recover solvent and solute from
the process, other treatments are needed such
as distillation or stripping.
STATUS: Demonstrated
SOURCES: Resources Conservation Co.
11
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TECHNOLOGY: Supercritical
Extraction
DESCRIPTION: At a certain combination of tem-
perature and pressure, fluids reach their critical
point, beyond which their solvent properties are
greatly enhanced. For instance, supercritical
water is an excellent non-polar solvent in which
most organics are readily soluble. These prop-
erties make extraction more rapid and efficient
than processes using distillation or conven-
tional solvent extraction methods. Presently, the
use of supercritical carbon dioxide to extract
hazardous organics from aqueous streams is
being investigated.
AVAILABILITY/LIMITATION: This technology is
potentially useful to extract hazardous waste
from aqueous streams. Specific applicability
and limitations are not yet known.
STATUS: Demonstrated on laboratory scale
SOURCES: N/A
12
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TECHNOLOGY: Filtration
DESCRIPTION: Filtration is a process of sepa-
rating and removing suspended solids from a
liquid by passing the liquid through a porous
medium. The porous medium may be a fibrous
fabric (paper or cloth), a screen, or a bed of gran-
ular material. The filter medium may be pre-
coated with a filtration aid such as ground cel-
lulose or diatomaceous earth. Fluid flow through
the filter medium may be accomplished by grav-
ity, by inducing a partial vacuum on one side of
the medium, or by exerting a mechanical pres-,
sure on a dewaterable sludge enclosed by filter
media.
AVAILABILITY/LIMITATION: Filtration is used for
the dewatering of sludges and slurries as a pre-
treatment for other processes. Granular media
filtration is typically used after gravity separa-
tion processes for additional removal of sus-
pended solids and oils prior to the other
treatment processes. It is also used as a polish-
ing step for treated waste to reduce suspended
solids and associated contaminants to low lev-
els. Pretreatment by filtration is appropriate for
membrane separation processes, ion exchange,
and carbon adsorption in order to prevent plug-
ging or overloading of these processes. Filtra-
tion of settled wastes is often required to remove
undissolved heavy metals which are present as
suspended solids. Filtration does not reduce the
toxicity of the waste although sometimes pow-
dered activated carbon may be used as a com-
bination adsorbent and filter aid. Filtration
should not be used with sticky or gelatinous
sludges, due to the likelihood of filter media
plugging.
STATUS: Commercially available
SOURCES: Calgon Carbon Corp.
Carbon Air Services Inc.
Chemical Waste Management
Industrial Innovations Inc.
Krauss-Maffei
Komline Sanderson
Bird Machine Co.
D.R. Sperry Inc.
Dorr-Oliver
TYPICAL FILTRATION BED
VACUUM FILTRATION CYCLE
Source: Envlrex, Waukesha, Wl,
CROSS SECTION OF A FIXED VOLUME RECESSED PLATE
FILTER PRESS ASSEMBLY
13
-------
TECHNOLOGY: Carbon
Adsorption
DESCRIPTION: The chemistry of carbon is such
that most organic compounds and many inor-
ganics will readily attach themselves to carbon
atoms. The strength of that attachment (and
thus, the energy required for subsequent de-
sorptlon) depends on the bond formed, which in
turn, depends on the specific compound being
adsorbed. Carbon to be used for adsorption is
usually treated to produce a product with large
surface-to-volume ratio, thus, exposing a prac-
tical maximum number of carbon atoms to be
active adsorbers. Carbon so treated is said to
be "activated" for adsorption. Activated carbon
which has adsorbed so much contaminant that
its adsorptlve capacity is severely depleted is
said to be "spent." Spent carbon can be regen-
erated, but for strongly adsorbed contaminants,
the cost of such regeneration can be higher than
simple replacement with new carbon.
AVAILABILITY/LIMITATION: This process is
used to treat single-phase aqueous organic
wastes with high molecular weight and boiling
point and low solubility and polarity, chlorinated
hydrocarbons such as tetrachloroethylene, and
aromatics such as phenol. It is also used to cap-
ture volatile organics in gaseous mixtures. Lim-
itations are usually economic and relate to the
rapidity with which the carbon becomes spent.
Rule of thumb guidelines are that contaminant
concentrations should be less than 10,000 ppm,
suspended solids less than 50 ppm, dissolved
Inorganics and oil and grease less than 10 ppm.
STATUS: Conventional, demonstrated
SOURCES: Calgon Carbon Corp.
Carbon Air Services Inc.
Zimpro Inc.
Chemical Waste Mgt.
Important Carbon Adsorption Process
Data Need Purpose
Chemical
characterization
of waste stream
Molecular weight
Solubility
Polarity of
contaminants
to be removed
pH of waste stream
Suitability for
carbon treatment
Suitability for carbon
treatment
Suitability for carbon
treatment
Suitability for
carbon treatment
Suitability for carbon
treatment
GRANULAR ACTIVATED CARBON ADSORPTION
To Service
Carbon
Adsorption
Column
Carbon
Adsorption
Column ,
K2
Spent Carbon T
(One Unit Changed
Per Time)
-To
Regeneration *
14
-------
TECHNOLOGY: Reverse
Osmosis
DESCRIPTION: In normal osmotic processes,
solvent will flow across a semi-permeable mem-
brane from a dilute concentration to a more con-
centrated solution until equilibrium is reached.
The application of high pressure to the concen-
trated side will cause this process to reverse.
This results in solvent flow away from the con-
centrated solution, leaving an even higher con-
centration of solute. The semi-permeable
membrane can be flat or tubular, but regardless
of its shape it acts like a filter due to the pres-
sure driving force. In application the waste
stream flows past the membrane while the sol-
vent, such as water, is pulled through the mem-
brane's pores and the remaining solutes such
as organic or inorganic components do not pass
through, but become more and more concen-
trated on the influent side of the membrane.
AVAILABILITY/LIMITATION: For an efficient re-
verse osmosis process, the chemical and phys-
ical properties of the semi-permeable membrane
must be compatible with the waste stream's
chemical and physical characteristics. Some
membranes may be dissolved by some wastes.
Suspended solids and some organics will clog
the membrane material. Low-solubility salts may
precipitate onto the membrane surface.
STATUS: Commercial units are available
SOURCES: Osmo Membrane Systems
15
-------
TECHNOLOGY: Ion Exchange
DESCRIPTION: Although there are naturally oc-
curring Ion exchange media, the process is usu-
ally based on the use of specifically formulated
resins having an "exchangeable" ion bound to
the resin with a "weak ionic" bond. Ion ex-
change depends upon the electrochemical po-
tential of the ion to be recovered versus that of
the exchange ion, and also upon the concentra-
tion of the ions in solution. After a critical rela-
tive concentration of "recoverable" ion to
exchanged ion in solution is exceeded, the ex-
change resin is said to be "spent." Spent resin
is usually recharged by exposing it to a very con-
centrated solution of the original exchange ion
so that a "reverse" exchange takes place, re-
sulting in regenerated resin and a concentrated
solution of the removed ion which can then be
further processed for recovery and reuse. The
process is commonly used to remove toxic metal
ions from solution in order to recover concen-
trated metal solutions for recycling. The result-
ing residuals include spent resins and spent
regenerants such as acid, caustic or brine.
AVAILABILITY/LIMITATION: This technology is
used to treat metal wastes including cations
(e.g., Ni2+, Cd2+, Hg2+) and anions (e.g.,
CrOf ~, SeO|~, HAsO| ~). Limitations are selec-
tivity/competition, pH and suspended solids.
Highly concentrated waste streams (greater than
about 25,000 mglt contaminants) can usually be
separated more cost effectively by other means.
High solid concentrations (greater than about
50 mg/f) should be avoided to prevent resin
blinding.
STATUS: Commercially available
SOURCES: Calgon
Dionex
DeVoe-Holbein
Davis Instrument Mfg Co., Inc.
Ecology Protection systems Inc.
Envirex Inc.
Industrial Filter & Pump Mfg.
Lancy International Inc.
McCormack Corp.
Osmo Membrane Sys Div.
Pace International Corp.
Permutit Co., Inc.
Serfilco LTD.
Techni Chem., Inc.
Thomas Scientific
Treatment Technologies
Water Management Inc.
Western Filter Co.
ION EXCHANGE
Acid Caustic
Wi
Comi
Regenerant
Regenerant
raste Containing I
ompound MX .
Regeneration
Cation
Exchanger
Anlon
Exchanger
Removal
X"+R[OH)2RX+20H-
Regeneratlon
HX * 2OHR(OH)2+X "
Delonlzed
- Effluent
-Spent Regenerant
TECHNOLOGY: Electrodialysis
DESCRIPTION: Electrodialysis concentrates or
separates ionic species contained in a water so-
lution. In electrodialysis, a water solution is
passed through alternately placed cation-
permeable and anion-permeable membranes. An
electrical potential is applied across the mem-
brane to provide the motive force for the ion mi-
gration. The ion-selective membranes are thin
sheets of ion exchange resin reinforced by a
synthetic fiber backing.
AVAILABILITY/LIMITATION: The process is well
established for purifying brackish water, and re-
cently has been demonstrated for recovery of
metal salts from plating rinse.
STATUS: Units are being marketed to reclaim
metals of value from rinse streams. Such units
can be skid mounted and require only piping
and electrical connections.
SOURCES: Centec Corp.
16
-------
CHEMICAL TREATMENT PROCESSES
The treatment processes discussed in this section include most of those commonly used for waste
treatment applications. These include
pH Adjustment (for Neutralization or Precipitation)
Hydrolysis and Photolysis
Oxidation and Reduction
Hydrogen Peroxide Oxidation
Ozonation
Alkaline Chlorination ;
Hypochlorite Chlorination
Electrolytic Oxidation ;
Chemical Dechlorination '..-.-- -
Data Need
Important Chemical Treatment Data Needs4
. Purpose
PH
Turbidity/Opacity
Consitituent analysis
Halogen Content
pH Adjustment Needs, Corrosiyity
Photolysis ,
Treatment Need
Dehalogenation
* Generally, the data needs for evaluating and comparing chemical treatment technologies include the
data needs identified for physical treatment technologies
17
-------
TECHNOLOGY: Neutralization
DESCRIPTION: When an ionic salt is dissolved
In water, several of the water molecules break
Into their ionic constituents of H + and OH ~.
Neutralization is the process of changing the
constituents in "an ionic solution until the num-
ber of hydrogen ions (H +) present is balanced
by the number of hydroxyl (OH ) ions. The lack
of balance is measured in terms of the hydrogen
Ion (H +) concentration and is commonly called
the pH of the solution. Neutrality is given on the
pH scale as 7, while an excess of H "^ ions (acid-
ity) is a number between 0 and 7 and an excess
of hydroxide ions (OH ~~) (alkalinity) is indicated
by a number between 7 and 14. Neutralization is
used to treat waste acids and waste alkalies
(bases) in order to eliminate or reduce their reac-
tivity and corrosiveness. Neutralization can be
a very Inexpensive treatment, especially if waste
alkali can be used to treat waste acid and vice/
versa. Residuals include a neutral effluent con-
taining dissolved salts and any precipitated
salts.
APPLICABILITY/LIMITATION: The process
should be performed in a well-mixed system to
ensure completeness. Care should be taken to
ensure compatibility of the waste and treatment
chemicals to prevent the formation of more toxic
or more hazardous compounds than were orig-
inally present.
STATUS: Common industrial process
SOURCES: Refer to buyer's guides for chemi-
cal suppliers
SIMULTANEOUS NEUTRALIZATION
OF ACID AND CAUSTIC WSTE
Waste
Acid
Storage
1 T
! 1
or
1 Waste
Caustic
Storage
I i
i
i
j
r
: 1
1 ^
1 /2>
p. ! >/
L
-------
TECHNOLOGY: Chemical
Precipitation
DESCRIPTION: Like neutralization, chemical
precipitation is a pH adjustment process. To
achieve precipitation, acid or base is added to
a solution to adjust the pH to a point where the
constituents to be. removed have their lowest
solubility. Chemical precipitation facilitates the
removal of dissolved metals from aqueous
wastes. Metals may be precipitated from solu-
tion as hydroxides, sulfides, carbonates, or other
insoluble salts. Hydroxide precipitation with
lime is most common, however, sodium sulfide
is sometimes used to achieve lower effluent
metal concentrations. Solid separation is ef-
fected by standard flocculatipn/coagulation
techniques. The resulting residuals are metal
sludge and the treated effluent which has an
elevated pH and (in the case of suifide precipi-
tation) excess sulfide.
APPLICABILITY/LIMITATION: This technology is
used to treat aqueous wastes containing met-
als. Limitations include the fact that not.all met-
als have a common optimum pH at which they
precipitate. Chelating and compjexing agents
can interfere with the process. Organics are not
removed except through adsorptive carryover.
The resulting sludge may be hazardous by def-
inition, but often may be delisted by specific
petition.
STATUS: Commercially available
SOURCES: Mobile Systems-Rexnord Craig
Ecolochem Inc.
DravoCorp.
Detox Inc.
Envirochem Waste Management
Services
Chemical Waste Management Inc.
Andco Environmental Processes
Inc.
Ensotech Inc.
Tetra Recovery Systems
GENERIC CHEMICAL PRECIPITATION
SOLUBILITIES OF METAL HYDROXIDES
AS A FUNCTION OF pH
100
0.001 -
8 9 10
SOLUTION pH
19
-------
TECHNOLOGY: Chemical
Hydrolysis
DESCRIPTION: Hydrolysis is the process of
breaking a bond in a molecule (which is ordi-
narily not water soluble) so that it will go into
Ionic solution with water. Hydrolysis can be
achieved by the addition of chemicals (e.g., acid
hydrolysis), by irradiation (e.g., photolysis) or bi-
ologically (e.g., enzymatic bond cleavage). The
cloven molecule can then be further treated by
other means to reduce toxicity.
APPLICABILITY/LIMITATION: Chemical hydrol-
ysis is applicable to a wide range of otherwise
refractory organics. Acid hydrolysis as in-situ
treatment must be performed carefully because
of the potential to mobilize any heavy metals
present.
STATUS: Common industrial process
SOURCES: Refer to buyer's guides for chemi-
cal suppliers
TECHNOLOGY: Ultraviolet
Photolysis
DESCRIPTION: Ultraviolet photolysis (UV) is a
process that destroys or detoxifies hazardous
chemicals in aqueous solutions utilizing UV ir-
radation. Adsorption of energy in the UV spec-
trum results in a molecule's elevation to a higher
energy state, thus, increasing the ease of bond
cleavage and subsequent oxidation of the mol-
ecule. For example, ultraviolet light has been
used for degradation of dioxins in waste sludge.
This process requires extraction of the waste to
be destroyed into a clean transparent solvent.
Reaction products are dechlorinated materials
and free chlorine gas. Use of UV photolysis on
nitrated wastes has been successfully demon-
strated on a pilot scale.
APPLICABILITY/LIMITATION: The inability of UV
light to penetrate and destroy pollutants in soil
or in turbid or opaque solutions is a limitation
of this approach. Photolytic treatment can be
enhanced by simultaneous introduction of
ozone or hydrogen peroxide.
STATUS: Laboratory scale
SOURCES: SYNTEX
20
-------
TECHNOLOGY: Chemical
Oxidation
(Chemical
Reduction)
DESCRIPTION: Oxidation and reduction must
both take place in any such reaction. In any ox-
idation reaction the oxidation state of one com-
pound is raised (i.e., oxidized) while the oxidation
state of another compound is lowered (i.e., re-
duced). Oxidation and reduction reactions are
utilized to change the chemical form of a haz-
ardous material in order to render it less toxic
or to change its solubility, stability, separability
or otherwise change it for handling or disposal
purposes. In the reaction, the compound sup-
plying the oxygen,(or chlorine or other negative
ion) is called the oxidizer or oxidizing agent while
the compound accepting the oxygen (i.e., sup-
plying the positive ion) is called the reducing
agent. The reaction can be enhanced by catal-
ysis, electrolysis or irradiation.
The process is called chemical reduction when
its purpose to lower the oxidation state of a
compound. Typical reducing agents include:
iron, aluminum, zinc and sodium compounds.
For the reduction process to occur efficiently,
the pH of the waste should be adjusted to an
appropriate level. After this stage is accom-
plished, the reducing agent is added and the
resulting solution is mixed until the reaction is
completed. This treatment may be applied to
chemicals such as hexavalent chromium, mer-
cury and lead. It is likely that other treatment
processes may be used in conjunction with
chemical reduction.
APPLICABILITY/LIMITATION: The process is
nonspecific. Solids must be in solution. Reac-
tions can be explosive. Waste composition must
be well known to prevent .the inadvertant prp-
duction of a more toxic or more hazardous end
product.
STATUS: Conventional process
SOURCES: Refer to buyer's guides for specific
process application
TECHNOLOGY:
Oxidation by
Hydrogen
Peroxide (H202)
DESCRIPTION: This treatment technology is
based on the addition of hydrogen peroxide to
oxidize organic compounds. Hydrogen peroxide
is not the stable oxide of hydrogen and since it
readily gives up its extra oxygen, it is an excel-
lent oxidizing agent.
APPLICABILITY/LIMITATION: The process is a
nonspecific reaction. It may be exothermic/ex-
plosive or require addition of heat and/or cata-
lysts. Oxidation by hydrogen peroxide is
probably not applicable for in-situ treatment.
However, it may be used for surface treatment
of contaminated groundwaters/sludges;
STATUS: Common industrial process
SOURCES: Refer to buyer's guides
21
-------
TECHNOLOGY: Ozonation
DESCRIPTION: Ozone is an oxygen molecule
containing three oxygen atoms. It is relatively
unstable and thus, is chemically ideal as an ox-
idizing agent. Ozonation is a chemical oxidation
process appropriate for aqueous streams which
contain less than 1 percent oxidizable
compounds.
APPLICABILITY/LIMITATION: Ozone can be
used to pretreat wastes to break down refractory
organics or as a polishing step after biological
or other treatment processes to oxidize un-
treated organics. Ozone is usually produced by
high-voltage ionization of atmospheric oxygen
(O2). Ozone is currently used for treatment of
hazardous wastes to destroy cyanide and phe-
nolic compounds. The rapid oxidation of cya-
nides with ozone offers advantages over the
slower alkaline chlorination method. Limita-
tions include the physical form of the waste (i.e.,
sludges and solids are not readily treated) and
non-selective competition with other species.
STATUS: Commercially available
SOURCES: Refer to buyer's guides
TECHNOLOGY: Alkaline
Chlorination
DESCRIPTION: When chlorine is added to
wastewaters, under alkaline conditions, reac-
tions occur which lead to oxidation (chlorina-
tion) of the contaminant. This oxidation process,
which is widely used in the treatment of cyanide
wastes, is generally referred to as the "alkaline
chlorination" process. Cyanides can be oxidized
with chlorine to the less toxic cyanates. Addi-
tional chlorine will then oxidize the cyanates to
nontoxic nitrogen gas, carbon dioxide, and
bicarbonates.
APPLICABILITY/LIMITATION: Alkaline chlori-
nation is used to treat free cyanides and com-
plex cyanides although combinations with Fe or
Ni will take a longer time. Limitations include
the exothermic heat of the reaction, non-selec-
tive competitions with other species and addi-
tional chlorine demands. Fairly close pH control
(7.5 to 9.0) is required to avoid toxic volatiles
release.
STATUS: Commercially available
SOURCES: Refer to buyer's guides
TECHNOLOGY: Oxidation by
Hypochlorite
DESCRIPTION: This process consists of adding
sodium or calcium hypochlorite (bleaching
agents) to oxidize organic wastes. Such tech-
nology will be recognized as the common
method of disinfecting home swimming pools.
APPLICABILITY/LIMITATION: This method may
produce toxic chlorinated organic by-products
and it must be done under controlled (not in-situ)
conditions, i.e. batch reactors. It is a nonspe-
cific reaction.
STATUS: Commercially available
SOURCES: Refer to buyer's guides
22
-------
TECHNOLOGY: Electrolytic
Oxidation
DESCRIPTION: In this process cathodes and an-
odes are immersed in a tank containing a waste
to be oxidized, and a direct electrical current is
imposed on the system. The process is partic-
ularly applicable to cyanide bearing wastes. Re-
action products are ammonia, urea, and carbon
dioxide. During the decomposition, metals pres-
ent are plated out on the cathodes.
APPLICABILITY/LIMITATION: Electrolytic oxi-
dation is used to treat high concentrations (up
to -10 percent) of cyanide and to separate met-
als to allow their potential recovery. Limitations
include physical form of the feed (solids must
be dissolved), non-selective competition with
other species and long-process times. Electro-
lytic recovery of single metal species can be
high (90 percent and higher).
STATUS: Commercially available
SOURCES: Refer to buyer's guides
TECHNOLOGY: Catalytic
Dehydrochlorination
DESCRIPTION: Catalytic Dehydrochlorination is
based on the reaction of polyehlorinated hydro-
carbons with high pressure hydrogen gas in the
presence of a catalyst. The feed must be in either
a liquid or gaseous form with the inorganic and
inert constituents removed. The operating tem-
peratures are: 350 to 375°C under 30 to 50 atm
pressure. The quantity of catalysts is usually
less than 1 percent of pollutant weight.
APPLICABILITY/LIMITATION: In general, sup-
ported catalysts are quickly deactivated by im-
purities such as tars or sulfur compounds.
These processes are costly and often require the
use of hazardous chemicals as catalysts.
STATUS: Laboratory scale
SOURCES: Not applicable
23
-------
TECHNOLOGY:
Alkali Metal
Dechlorination
DESCRIPTION: The purpose of this process of
chemical dechlorination is to displace chlorine
from chlorinated organic compounds contained
In oils and liquid wastes. Typically the waste is
filtered before it enters the reactor system where
It encounters the dechlorinating reagent. The
great affinity of alkali metals for chlorine (or any
halide) is the chemical basis of the process.
Successive treatment includes additional cen-
trifugation and filtration. By-products include
chloride salts, polymers and sometimes heavy
metals. This process may be carried out in a
reactor system (as mentioned above), in situ or
by excavation techniques. Several chemical de-
chlorination processes are based on a method
developed by the Goodyear Tire and Rubber
Company in 1980. The original method uses so-
dium naphthalene and tetrahydrofuran to strip
chlorine atoms from PCBs, resulting in poly-
merizing the blphenols into an inert condensible
sludge. The reactor is blanketed with nitrogen
because reagents are sensitive to air and to
water and an excess of reagent to chlorine con-
tent is required. The Goodyear Company has not
commercially developed the technology. How-
ever several companies have modified the
method by substituting their own proprietary re-
agent for the naphthalene. The equipment is
mobile and can be transported on semi-trailors.
APPLICABILITY/LIMITATION: Such processes
are used to treat PCBs, other chlorinated hydro-
carbons, acids, thiols, and dioxins. Moisture
content adversely affects rates of reaction and
dewatering should be a pretreatment step. Waste
stream concentrations are also important.
STATUS: Commercially available
SOURCES: American Mobile Purification
SunOhio
PPM Inc.
Ac u rex
Chemical Waste Management Inc.
Exceltech, Inc.
TECHNOLOGY:
Alkali Metal/
Polyethylene
Glycol (A/PEG)
DESCRIPTION: In 1978, the EPA sponsored re-
search which led to the development of the first
of the series of A/PEG reagents, which were
shown to effectively dechlorinate PCBs and oils.
Essentially, these reagents were alkali metal/
polyethylene glycols which react rapidly to de-
halogenate halo-organic compounds of all
types, under both ambient and high temperature
conditions. In the A/PEG reagents, the alkali
metal Ion is held in solution by the large poly-
ethylene glycol anion. PCBs and other halogen-
ated molecules are uniquely soluble in A/PEG
reagents. These qualities combine to get a
single-phase system in which the anions readily
displace the halogen atoms. The reaction of hal-
ogenated aromatics with PEGs result in the sub-
stitution of the PEG for the chlorine atom to form
a PEG ether. The PEG ether, in turn, may then
decompose to a phenol.
APPLICABILITY/LIMITATION: In this treatment,
heat and excess reagent are required for the
process to function effectively in soils contain-
ing more than seven percent moisture.
STATUS: Process has been field tested
SOURCES: Not applicable
24
-------
BIOLOGICAL PROCESSES
Biological degradation of hazardous organic substances is a viable approach to waste management.
The most commonly used processes are those originally utilized in the treatment of municipal waste-
waters, namely, processes based on aerobic bacteria or anaerobic bacteria. In-situ treatment of contam-
inated soils can also be performed biologically. Cultures used in biological degradation processes can
be native (indigenous) microbes, selectively adapted microbes or genetically altered microorganisms.
Some processes based on other biological communities (such as fungi) are under development and
evaluation, but have not been fully demonstrated.
Data Need
Important Biological Treatment Data Needs
* Purpose
Gross Organic Component
(BOD.TOC)
Priority Pollutant Analysis
Dissolved Oxygen
Nutrient Analysis
(NH3> N03, P04, etc.)
PH
ORP
Treatability
Toxicity to Process
Microbes
Aerobic Reaction Rates/
Interference with Anaerobic
System
Nutrient Requirements
pH Adjustment
Chemical Competition-
25
-------
TECHNOLOGY: Aerobic
Biological
Treatment
DESCRIPTION: Hydrocarbons are catabolized -
(broken down, to simpler substances) by micro-
organisms using three general mechanisms.
These are aerobic respiration, anaerobic respi-
ration and fermentation. In general, aerobic deg-
radation processes are more often used for
blodegradation because the degradation proc-
ess is more rapid and more complete, and prob-
lematic end products (methane, hydrogen
sulflde) are not produced. However, anaerobic
degradation is important for dehalogenation.
(See anaerobic process description in this
document).
In aerobic respiration, organic molecules are ox-
idized to carbon dioxide (COg) and water and
other end products using molecular oxygen as
the terminal electron acceptor. Oxygen may also
be incorporated into intermediate products of
microbial catabolism through the action of pxi-
dase enzymes, making them more susceptible
to further biodegradation. Microorganisms me-
tabolize hydrocarbons by anaerobic respiration
In the absence of molecular oxygen using inor-
ganic substrates as terminal electron acceptors.
Naturally occurring aerobic bacteria can decom-
pose organic materials of both natural and syn-
thetic origin to harmless or stable forms or both
by mineralizing them to CO2 and water. Some
anthropogenic compounds can appear rela-
tively refractory to biodegradation by naturally
occurring microbial populations because of the
Interactions of environmental influences, lack of
solubility, absence of required enzymes, nu-
trients, or other factors. However, the use of
properly selected or engineered microbial pop-
ulations, maintained under environmental con-
ditions most conducive to their metabolic
activity can be an important means of biologi-
cally transforming or degrading these otherwise
refractory wastes.
All microorganisms require adequate levels of
Inorganic and organic nutrients, growth factors
(vitamins, magnesium, copper, manganese, sul-
fur, potassium, etc.), water, oxygen, carbon diox-
ide and sufficient biological space for survival
and growth. One or more of these factors are
usually in limited supply. In addition, various mi-
crobial competitors adversely affect each other
through the struggle for these limiting factors.
Other factors which, can influence microbial
biodegradation rates include microbial inhibi-
tion by chemicals in the waste to be treated, the
number and physiological state of the orga-
nisms as a function of available nutrients, the
seasonal state of microbial development, pre-
dators, pH and temperature. Interactions be-
tween these and other potential factors can
cause wide variations in degradation kinetics.
For these and other reasons, aerobic biodegra-
dation is usually carried out in processes in
which all or many of the requisite environmental
conditions can be controlled. Such processes
include conventional activated sludge proc-
esses as well as modifications such as se-
quencing batch reactors, and aerobic-attached
growth biological processes such as rotating bi-
ological contactors and trickling filters. Recent
developments With genetically engineered bac-
teria have been reported to be effective for bio-
logical treatment of specific hazardous wastes
which are relatively uniform in composition.
APPLICABILITY/LIMITATION: Used to treat
aqueous wastes contaminated with low levels
(e.g., BOD less than « 10,000 mgtf) of nonhal-
ogenated organic and/or certain halogenated
organics. The treatment requires consistent,
stable operating conditions.
STATUS: Conventional, broadly used technology
SOURCES: Dependent upon specific engi-
neered approach see following
discussions
26
-------
TECHNOLOGY: Activated Sludge
DESCRIPTION: The function of activated sludge
treatment is to break down organic contami-
nants in aqueous waste streams through the ac-
tivity of aerobic microorganisms. These
microorganisms metabolize biodegradable or-
ganics. This treatment includes conventional
activated sludge processes as well as modifi-
cations, such as sequencing batch reactors. The
aeration process includes pumping the waste to
an aeration tank where the biological treatment
occurs.,Following this the stream is sent to a
clarifier where the liquid effluent (treated
aqueous waste) is separated from the sludge
bipmass. Aerobic processes are capable of sig-
nificantly reducing a wide range of o.rganic, toxic
and hazardous compounds. However, only di-
lute aqueous waste (less than « 1 percent) are
normally treatable.
APPLICABILITY/LIMITATION: The treatment re-
quires consistent stable operating conditions.
Activated sludge processes are not suitable for
removing highly chlorinated organics, aliphat-
ics, amines and aromatic compounds from a
waste stream. Some heavy metals and organic
chemicals are harmful to the organisms. When
utilizing conventional open aeration tanks and
clarifiers, this technology can result in the es-
cape of volatile hazardous materials.
STATUS: Conventional, well developed
SOURCES: Polybac Corp.
Detox Inc.
Ground Decontamination Systems
ACTIVATED SLUDGE PROCESS
Sludgt
Pump
27
-------
TECHNOLOGY: Rotating
Biological
Contactors
DESCRIPTION: Rotating biological contactors
aerobically treat aqueous waste streams, espe-
cially those containing alcohols, phenols,
phthalates, cyanides and ammonia. The proc-
ess consists of primary treatment for solids re-
moval followed by the rotating biological
contactors where the waste stream comes into
contact with the microbial film and the atmos-
phere. The rate of rotation can be varied to op-
timize oxygenation of the bacteria and their
contact time with the wastes to be degraded.
Effluent is then sent to a secondary clarifier.
APPLICABILITY/LIMITATION: Rotating biologi-
cal contactors are not a sufficient method to
remove highly chlorinated organics, aliphatics,
amines and aromatic compounds. Some heavy
metals and organic chemicals are harmful to the
organisms.
STATUS: Conventional
SOURCES: Polybac Corp.
Detox Inc.
Ground Decontamination Systems
Important Data Needs for Screening
RBCs:
Data Need
Purpose
Gross organic
components (BOD,
TOC)
Priority pollutant
analyses (organics,
metals, pesticides,
CN, phenols)
Influent temperature
Waste strength,
treatment duration
Suitability for
treatment, toxic
impact assessment
Feasibility in
climate
TECHNOLOGY: Bioreclamation
DESCRIPTION: Bioreclamation is used to treat
contaminated areas through the use of aerobic
microbial degradation. It may be accomplished
by in-situ treatment using injection/extraction
wells or an excavation process. Extracted
waters, leachates or wastes are oxygenated, nu-
trients and bacteria are added and the liquids
relnjected in the ground. Bacteria then can de-
grade wastes still in the soil. The treatment has
been successfully applied to biodegradable
nonhalogenated organics to reduce the contam-
inated levels in soils and groundwater.
APPLICABILITY/LIMITATION: For in-situ treat-
ment, limitations would include site geology and
hydrogeology which could restrict pumping and
extraction of hazardous wastes, along with rein-
jection and recirculation. Ideal soil conditions
are those with neutral pH, high permeability and
a moisture content of 50 to 75 percent.
STATUS: Demonstrated
SOURCES: FMC
Important Bioreclamation Data Needs
Data Need
Purpose
Gross organic
components (BOD,
TOC)
Priority analysis
Microbiology cell
enumerations
Temperature
Dissolved oxygen
PH
Nutrient analysis
NH3, N03, P04, etc.
Waste strength,
treatment duration
Identify refractory
and biodegradable
compounds, toxic
impact
Determine existence
of dominant bacteria
Feasibility in climate
Rate of reaction
Bacteria preference
Nutrient requirements
28
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TECHNOLOGY: Anaerobic
Digestion
DESCRIPTION: All anaerobic biological treat-
ment processes achieve the reduction of or-
ganic matter, in an oxygen-free environment, to
methane and carbon dioxide. This is accom-
plished by using cultures of bacteria which in-
clude facultative and obligate anaerobes.
Anaerobic bacterial systems include hydrolytic
bacteria (catabolize saccharides, proteins, lip-
ids); hydrogen producing acetogenic bacteria
(catabolize the products of hydrolytic bacteria,
e.g., fatty acids and neutral end products); ho-
molactic bacteria (catabolize multicarbon comT
pounds to acetic acid); and methanogenic
bacteria (metabolize acetic and higher fatty
acids to methane and carbon dioxide). The strict
anaerobes require totally oxygen-free environ-
ments and oxidation reduction potential of less
than -0.2V. Microorganisms in this group are
commonly referred to as methanogenic consor-
tia and are found in anaerobic sediments or sew-
age sludge digesters. These organisms play an
important role in reductive dehalogenation re-
actions, nitrosamine degradation, reduction of
epoxides to olefins, reduction of nitro groups
and ring fission of aromatic structures. Avail-
able anaerobic treatment concepts are based on
such approaches as the classic well-mixed sys-
tem, the two-stage systems and the fixed bed.
In the well-mixed digester system a single ves-
sel is used to contain the wastes being treated
and all bacteria must function in that common
environment. Such systems typically require
long retention times and the balance between
acetogenic and methanogenic populations is
easily upset. In the two stage approach, two ves-
sels are used to maintain separate environ-
ments, one optimized for the acetogenic
bacteria (pH 5.0), and the other optimized for the
methanogenic bacteria (pH 7.0). Retention times
are significantly lower and upsets are uncom-
mon in this approach. The fixed bed approach
(for single or 2-staged systems) utilizes an inert
solid media to which the bacteria attach them-
selves and low solids wastes are pumped
through columns of such bacteria rich media.
Use of such supported cultures allows reduced
retention times since bacterial loss through
washout is minimized. Organic degradation ef-
ficiencies can be quite high. A number of pro-
prietary engineered processes based on these
types of systems are actively being marketed,
each with distinct features but all utilizing the
fundamental anaerobic conversion to methane
and carbon dioxide.
APPLICABILITY/LIMITATION: This process is
used to treat aqueous wastes with low to mod-
erate levels of organics. Anaerobic digestion can
handle certain halogenated organics better then
aerobic treatment. Stable, consistent operating
conditions must be maintained. Anaerobic deg-
radation can take place in native soils but when
used as a controlled treatment process, an air-
tight reactor is required. Since methane and CO2
gases are formed, it is common to vent the gases
or burn them in flare systems. However, volatile
hazardous materials could readily escape via
such gas venting or flare systems. Thus, con-
trolled off-gas burning could be required. Alter-
natively, depending on the nature of the waste
to be treated, the off-gas could be used as a
source of energy.
STATUS: Available and widely used in POTWs
SOURCES: Refer to buyer's guides
29
-------
TECHNOLOGY: White-rot
Fungus
DESCRIPTION: The lignin degrading white-rot
fungus (phanerochaete chrysosporium) has
been found to degrade a broad spectrum of or-
ganopollutants including chlorinated lignin-
derived by-products of the Kraft pulping proc-
ess. White-rot has been shown to degrade ali-
phatic, aromatic and heterocyclic compounds.
Specifically, white-rot fungus has been shown
to degrade lindane, benzo(a)pyrene, DDT, TCDD,
and PCBs to innocuous end products. The stud-
ies performed, to date, suggest that white-rot
fungus may prove to be an extremely useful mi-
croorganism in the biological treatment of haz-
ardous organic waste.
APPLICABILITY/LIMITATION: Demonstrated on
laboratory scale
STATUS: This technology is in the develop-
mental phase and has been applied only in lab-
oratory-type test environs
SOURCES: N/A
30
-------
THERMAL DESTRUCTION PRO<
While limits exist for specific incineration technologies, there are nc
incineration for any wastes, i.e., any waste can be burned at some c<
include several energy recovery processes, traditional incineration
thermal processes.
Data Need
Important Thermal Treatment Data l>
Purpose
Heat Content (HHV and LHV)
Volatile Matter Content
Ash Content
Ash Characteristics
Halogen Content
Moisture Content
Heavy Metal Content
Combustibility
Furnace Design
Furnace Design,
Handling
Furnace Design
Refractory Desij
Flue Gas Ductw
Specification,
ARC Requireme
Auxiliary Fuel
Requirements
Air Pollution Co
Generally, the data needs for evaluating thermal processes incl
treatment for the purpose of feed mechanism design
;hnical limitations on
estruction processes
id several innovative
i needed for physical
31
-------
TECHNOLOGY: Liquid Injection
Incineration
DESCRIPTION: Liquid waste material is intro-
duced to the combustion chamber by means of
specially designed nozzles. Different nozzle de-
signs result in various droplet sizes which mix
with air and fuel as needed. Following combus-
tion, the resulting gases are cooled and treated
to remove particulates and to neutralize acid
gases. Pretreatment such as blending, may be
required for feeding some wastes to specific
nozzles to provide efficient mixing with the ox-
ygen source and to maintain a continuous ho-
mogeneous waste flow. In general, the more
finely atomized liquids will combust more rap-
idly and more completely. Operating tempera-
tures range from 1200 to 1300° F and the gas
residence time ranges from 0.1 to 2 seconds.
Typical heat output ranges from 1 to 100 MMBtu/
hr.
APPLICABILITY/LIMITATION: Liquid injection
Incineration can be applied to all pumpable or-
ganic wastes including wastes with high mois-
ture content. Care must be taken in matching
waste (especially viscosity and solids content)
to specific nozzle design. Particle size is a rel-
evant consideration so the wastes do not clog
the nozzle. Emission control systems will prob-
ably be required for wastes with ash content
above 0.5 percent (particulate control) or for hal-
ogenated wastes (acid gas scrubbers).
STATUS: This process, is conventional and well
demonstrated
SOURCES: Ensco Environmental Services
TRANE Thermal Co.
John Zink Co.
Goen Co. Inc.
Vent-o-Matic Incinerator Corp.
Lotepro Co.
MECHANICAL ATOMIZING NOZZLE
REVERSER AND
FEED PASSAGE
RESONATOR
SONIC NOZZLE
32
-------
TECHNOLOGY: Rotary Kiln
Incineration
DESCRIPTION: A rotary kiln incinerator is es-
sentially a long, inclined tube that is rotated
slowly. Wastes and auxiliary fuels are intro-
duced to the high end of the kiln and the rotation
constantly agitates (tumbles) the solid mate-
rials being burned. This tumbling causes a great
amount of turbulence and allows for improved
combustion. Rotary kilns are intended primarily
for solids combustion, but liquids and gases
may be co-incinerated with solids. Exhaust
gases from the kiln pass to a secondary cham-
ber or afterburner for further oxidation. Ash res-
idue is discharged and collected at the low end
of the kiln. Exhaust gases require acid gas and
particulate removal through the use of a gas
scrubber and the ashes may require solidifica-
tion before landfilling.
APPLICABILITY/LIMITATION: Most types of
solid, liquid, and gaseous organic waste or a
mixture of these wastes can be treated with this
technology. Explosive wastes and wastes with
high inorganic salt content and/or heavy metals
require special evaluation. This operation can
create high particulate emissions which require
post-combustion control.
STATUS: Rotary kiln incinerators are commer-
cially available and are in wide use.
SOURCES: S.D. Myers, Inc.
American Industrial Waste of
ENCSO, Inc., (mobile)
Exceltech, Inc.
Coen Co.
international Waste Energy
Systems
Thermal, Inc.
Lurgi Corp.
Komline Sanderson
International Waste Energy System
Winston Technology, lnc.,(mobile)
Volland, U.S.A.
Von Roll
DETOXCO Inc.
ROTARY KILN INCINERATOR SCHEMATIC
LEGEND.
1 INFLUENT WASTE
2 COMBUSTION AIR
3 FLUE GAS
« RESIDUALS
5 SCRUBBER WATER
6 FUEL
33
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TECHNOLOGY:
Fluidized Bed
Incineration
DESCRIPTION: Fluidized bed incinerators uti-
lize a very turbulent bed of inert granular mate-
rial (usually sand) to improve the transfer of heat
to the waste streams to be incinerated. Air is
blown through the granular bed materials until
they are "suspended" and able to move and mix
In a manner similar to a fluid, i.e., they are "flui-
dlzed." In this manner, the heated bed particles
come In intimate contact with the wastes being
burned. The process requires that the waste be
fed Into multiple injection ports for successful
treatment-Advantages of this technology in-
clude excellent heat transfer to the material
being incinerated and a long residence time. An
off-shoot of this technology is a circulating bed
combustor.
APPLICABILITY/LIMITATION: Fluidized beds re-
quire frequent attention for maintenance and
cleaning purposes. This treatment is ideal for
slurries and sludges but not for bulky or viscous
wastes. The waste particles should be of a cer-
tain size and be homogeneous. Wastes must
have a low sodium content and a low heavy
metal content. Some refractory wastes may not
be fully destroyed since these units operate at
low combustion temperatures (750° to 1000° C).
STATUS: Fluidized bed incineration is presently
available In a demonstration-scale unit for haz-
ardous waste. They have been used to inciner-
ate municipal wastewater treatment plant
sludge, oil refinery waste, some pharmaceutical
wastes, and some chemical wastes including
phenolic waste, and methyl methacrylate. Heat
recovery is possible.
SOURCES: Lurgi Corp.
G.A. Technologies
Waste-Tech Services, Inc.
Dorr-Oliver
Combustion Power
Niro Atomizer
-SIGHT GLASS
THERMOCOUPLE
PRESSURE TAP
FLUIDIZED BED REACTOR
34
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TECHNOLOGY: Pyrolysis
DESCRIPTION: Pyrolysis is the chemical de-
composition of waste brought about by heating
the material in the absence of oxygen. The sys-
tem involves the use of two combustive cham-
bers. In the primary chamber the wastes are
heated, separating .the volatile components
(combustible gases, water vapor, etc.) from the
nonvolatile char and ash (metals and salts). In
the secondary chamber (afterburner or fume in-
cinerator) volatile components are burned under
the proper air, temperature, time and turbulence
to destroy any remaining hazardous compo-
nents. Temperature in the pyrolysis section is
controlled by the addition of auxiliary fuel. There
are two ways to heat the material; tlpe first is by
direct heating where the material comes in con-
tact with hot combustion gases from a burner
or incinerator. The resulting off-gas is a combi-
nation of the combustion gases and the vola-
tiles from the waste. The second method is by
indirect heating by an electric resistance heat-
ing element or an external burner with its ex-
haust gases directly vented to the atmosphere.
This approach allows product recovery, rather
than incineration, from the gaseous stream leav-
ing the primary chamber without contamination
or dilution by the burner flue gases. Indirect
heating is more complex and expensive than di-
rect heating. Pyrolysis can be designed for batch
burning of drummed or containerized material
or continuous processing of f lowable solids and
liquids. The hot combustion gases from the sec-
ondary chamber can be passed through a boiler
to recover energy. Liquid wastes can be injected
simultaneously into the secondary chamber
during the pyrolyzing of waste in the primary
chamber.
APPLICABILITY/LIMITATION: This technology is
used to treat viscous liquids, sludges, solids,
high-ash material, salts and metals or halogen-
ated waste that are not conducive to conven-
tional incineration, wastes that are stored in
containers or which contain volatile metals or
recoverable residues. The limitations are that it
requires auxiliary fuel, currently has small ca-
pacity of waste input and metals and salts in
the residue can be leachable, thus, requiring res-
idue disposal as a hazardous waste.
STATUS: Commercially available, batch and
continuous pyrolysis processes exist.
SOURCES: Midland-Ross Corp.
American Energy Corp.
Econo Therm Energy Systems
Lurgi Corp.
J.M. Huber Corp.
Shirco Infrared Systems, Inc.
Spencer Boiler and Engineering,
Inc.
35
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TECHNOLOGY: Wet Air
Oxidation
DESCRIPTION: Wet air oxidation uses elevated
temperature and pressure to oxidize dissolved
or finely divided organics. The oxidation prod-
ucts usually remain dissolved or suspended in
the liquid. The off-gas is low in nitrogen oxides,
sulfur oxides and particulates. Off-gas treat-
ment may be necessary to control hydrocarbon
emissions. The advantages are, it is thermally
self sustaining, accepts waste with organic con-
centrations ranging between those considered
ideal for either biological treatment or inciner-
ation, detoxifies priority pollutants and the prod-
ucts of oxidation stay in the liquid phase. Wet
air oxidation is particularly well suited for treat-
ing organic compounds in aqueous waste
streams that are too dilute (less than 5 percent
organics) to treat economically by incineration.
Oxidation of the organic compounds occurs
when, the aqueous solution is heated to about
300° C and 137 atm in the presence of com-
pressed air. Typically, 80 percent of the organic
substances will be completely oxidized. The
system can accommodate some partially halo-
genated compounds, but highly-chlorinated
species, such as PCBs, are too stable for conv
plete destruction without the addition of cata-
lysts or the use of very high pressure and
temperature.
APPLICABILITY/LIMITATION: This process is
used to treat aqueous waste streams with less
than 5 percent organics and with some pesti-
cides, phenolics, organic sulfur and cyanide
wastewaters. It is not recommended for aro-
matic halogenated organics, inorganics or for
treating large volumes of waste. This technol-
ogy is not appropriate for solids or viscous
liquids.
STATUS: Available at commercial scale
SOURCES: Zimpro Inc.
Modar Inc.
Vertox Treatment Systems
TECHNOLOGY: Industrial Boilers
DESCRIPTION: Some industrial boilers can use
limited amounts and types of wastes as supple-
mental fuels so that the wastes are destroyed
while recovering the available heat from the
waste. Hazardous waste is used as supplemen-
tary fuel to coal, oil or natural gas in fire-tube
and water-tube industrial boilers. Hazardous
waste fuel (generally limited to liquid waste) can
be fed into a boiler with the primary fuel or it
can be fed separately into the furnace. If a fa-
cility is burning its own wastes as fuel, it can
control "fuel quality" to a great extent. If wastes
are imported for use as fuel, then it is common
to blend incoming wastes to an "optimum" sup-
plemental fuel for that facility's boilers.
APPLICABILITY/LIMITATION: Chlorine and sul-
fur must be limited in Hazardous Waste Fuel
(HWF) to minimize corrosion of boiler materials
of construction and to avoid increases in HCI
and sulfur oxide air emissions. Solid hazardous
wastes such as contaminated soil are not ap-
plicable for use as HWF in boilers. Industrial
boilers are particularly useful for the disposal of
hazardous waste generated on site.
STATUS: Only a small fraction of the nation's
23,000 fossil-fueled boilers are in use burning
hazardous waste as fuel.
SOURCES: Various manufacturers, may be
packaged units or field constructed
36
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TECHNOLOGY: industrial Kilns
(Cement, Lime,
Aggregate, Clay)
DESCRIPTION: Industrial kilns are used to in-
cinerate liquid wastes while recovering heat
value. The system consists of rotary kilns con-
structed of steel casings lined with refractory
brick. These kilns are much longer than rotary
kiln incinerators and have much longer retention
times. Blended feed material (a waste/air mix-
ture) is fed into the hot end of the kiln as a sup-
plement to the primary fuel (coal, gas, or oil).
Kiln temperatures are about 3000° F for cement
and lime kilns and less than 2000° F for aggre-
gate and clay drying kilns. Organics are de-
stroyed while the ash is assimilated into the kiln
product. Waste blending is necessary to obtain
desired fuel characteristics to control product
quality. The kiln should contain a precipitator or
baghouse in order to remove suspended partic-
ulates in the flue gases.
APPLICABILITY/LIMITATION: Kilns have gener-
ally been limited to liquid waste. Heavy metals,
ash, chlorine and sulfur content of waste fuel
must be controlled to prevent kiln operating and
product quality problems. Contaminated soils
are not good candidates for treatment in indus-
trial kilns because of concern for product qual-
ity. The system should be equipped with air
pollution control devices.
STATUS: The use of hazardous waste as a fuel
in kilns is becoming more widespread. At least
15 cement kilns and at least six aggregate kilns
are now burning hazardous waste fuel as sup-
plemental fuels in the U.S. This technology can
be considered conventional 'and well
demonstrated.
SOURCES: SYSTECH Corp.
PATCH EM - Waste Management
McKesson Envirosystems Co.
TECHNOLOGY: Blast Furnaces
(Iron and Steel)
DESCRIPTION: Blast furnace temperatures may
reach up to 3400° F and are generally above
3000° F. High heat content hazardous wastes
can be used to supplement the fuel require-
ments for blast furnaces. A blast furnace pro-
duces molten iron from iron ore and other iron
bearing feed materials. Iron ore, carbon (coke)
and limestone are fed to the top of the furnace,
and iron product and slag are removed in differ-
ent layers from the bottom. Hazardous wastes
used as fuels can be injected above the slag
layer.
APPLICABILITY/LIMITATION: The composition
(trace elements) of the waste must be controlled
to avoid product quality problems. Waste oils
were fired in a blast furnace in HWERL test pro-
grams. Some concerns have been expressed
that the reducing atmosphere in a blast furnace
could result in reduced DREs.
STATUS: .There are less than 80 blast furnaces
currently operating in the U.S. The authors are
aware of none that are currently burning hazard-
ous waste as fuel.
SOURCES: N/A
37
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TECHNOLOGY: Infrared
Incineration
DESCRIPTION: Infrared radiators can be used
as the heat source in the destruction of hazard-
ous waste. This system is made up of a primary
chamber consisting of a rectangular carbon
steel box lined with layers of a light-weight, ce-
ramic fiber blanket. Infrared energy is provided
by silicon carbide resistance heating elements.
The material to be processed is conveyed
through the furnace on a woven wire belt. Solids
are pyrolyzed on the hearth. Sufficient air (or ox-
ygen) is Introduced to fully combust the off-
gases. When the waste reaches the discharge
end of the furnace it drops off the belt into a
hopper. The advantages include a quiescent
combustion zone which results in low particu-
late emission, reduced gaseous pollutant emis-
sions, low fossil fuel usage, and up to 50 percent
operational turndown capacity. This system al-
lows a high degree of control and long-resi-
dence times for solids are achievable.
APPLICABILITY/LIMITATION: This technology is
used primarily to treat solids (not larger than a
specified size) sludges and contaminated soils,
but liquid or gaseous injection systems are
available.
STATUS: Operational units exist at several lo-
cations, mobile units are under construction and
units are presently under evaluation in the SITE
Program.
SOURCES: Shirco Infrared Systems
Haztech
Maecorp Inc.
Reidel Environmental Services
MATERIAL PROCESSING/OS- WATERING
Q
8
AIR POLLUTION CONTROL
EOUIFUEMT
SECONDARY COMBUSTION
CHAMBER
AIR PRE-HEATERfOPT/ONXU
V 1 MATERIAL
HOLDING TANK
FEED METERING
SOURCE: SH/flCO INFRARED S/STEMS INC.
PROCESS FLOW DIAGRAM OF INFRARED INCINERATION SYSTEM
38
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TECHNOLOGY: Circulating Bed
Combustor
DESCRIPTION: The circulating bed combustor
is designed to be an improvement over conven-
tional fluidized beds. The system operates at
higher velocities and finer sorbents than fluid-
ized bed systems. This permits a unit that is
more compact and easier to feed. The unit also
produces lower emissions and uses less sor-
bent materials than the fluidized bed systems.
No off-gas scrubber is necessary in the circu-
lating bed combustor and heat can be recovered
as an added benefit. The key to the high effi-
ciency of the circulating bed combustor is the
high turbulence that is achieved within the com-
bustor. This feature allows efficient destruction
of all types of halogenated hydrocarbons in-
cluding RGBs and other aromatics at tempera-
tures less than 850° C (Freeman, 1985). Acid
gases are captured within the combustion
chamber by limestone in the bed. A baghouse
is needed for particulate control. Compounds
containing high levels of phosphorus, sulfur, cy-
anide, etc. can be processed with low emissions
of NOX, CO and acid gases. In addition to the
turbulence, a large combustion zone with uni-
form and lower temperature throughout also
contributes to high efficiency. The circulating
bed combustor also features longer residence
time of the combustibles and sorbents in the
combustion zone.
APPLICABILITY/LIMITATION: The system is ca-
pable of treating solids, sludges, slurries and
liquids. The high degree of turbulence and mix-
ing ensures treatment of a wide variety of
wastes. The waste however, must be fairly ho-
mogeneous in composition when fed to the
combustor, since it is usually introduced at only
one location. An additional benefit of the cir-
culating bed combustor is the possibility of heat
recovery. The combustion chamber can be of
"waterwall" construction.
STATUS: Ready for full-scale testing. Unit is in
RCRA permit process.
SOURCES: G. A. Technologies
Riley Stoker
Keeler Dorr-Oliver
39
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TECHNOLOGY: Supercritical
Water Oxidation
DESCRIPTION: The supercritical water oxida-
tion process is basically a high temperature,
high pressure wet air oxidation. The unique
properties of water above 500° C (supercritical
region) causes it to act as an excellent nonpolar
solvent for nearly all organic materials. Aqueous
solutions or slurries (organic content greater
than 5 percent) are mixed with high pressure ox-
ygen (3200 to 3600 psi or greater than 218 atm),
to chemically oxidize waste in less than one
minute at greater than 99.99 percent efficiency.
Two processing approaches have been evalu-
ated, an above ground pressure vessel reactor
(Modar) and the use of an 8000 to 10,000 ft deep
well as a reactor vessel (Vertex). The supercrit-
ical water process is best suited for large vol-
ume (200 to 1000 gpm) dilute (in the range of 1
to 10,000 mgl? COD) aqueous wastes that are of
a volatile nature and that have a sufficiently high
heat content to sustain the process. In many
applications, high Btu, nonhazardous waste can
be mixed with low Btu hazardous waste to pro-
vide the heat energy needed to make the proc-
ess self sustaining. Emissions/residues include
gaseous effluent (nitrogen and carbon dioxide),
precipitate of inorganic salts and the liquid con-
taining only soluble inorganic acids and salts.
The advantages are rapid oxidation rates, com-
plete oxidation of organics, efficient removal of
inorganics and no off-gas processing is required.
APPLICABILITY/LIMITATION: Supercritical
water oxidation is used to treat aqueous organic
solutions/slurries and mixed organic/inorganic
waste, which are pumpable. Sophisticated
equipment and operations and long term contin-
uous operations have not been demonstrated,
thereby limiting its use.
STATUS: Demonstration of use with municipal
sewage sludge completed in 1985
SOURCES: Vertex Corporation
Modar Inc.
TECHNOLOGY: Advanced
Electric Reactor
DESCRIPTION: Advanced electric reactors use
electrically heated fluid walls to pyrolyze waste
contaminants. The resulting thermal radiation
causes pyrolysis of the organic constituents in
the waste feed. At these high temperatures in-
organic compounds melt and are fused into vit-
reous solids. Most metal salts are soluble in
these molten glasses and can thus become
bound in a solid matrix (vitrified beads). Follow-
ing pyrolysis in the reactor, granular solids and
gaseous reactor emissions are directed to a post
reactor zone, where radiant cooling occurs. The
advantages are that it is transportable, has a
high treatment efficiency and emissions are low.
APPLICABILITY/LIMITATION: This process is
used to treat organics or inorganics, in solid,
liquid or gaseous form (solid or liquid may re-
quire pretreatment) and for PCB or dioxin con-
taminated soils. It is limited to treating solids
less than 35 US mesh and liquids atomized to
less than 1500 micron droplets. A post treatment
process may be needed in order to remove prod-
ucts of incomplete combustion from the
emissions.
STATUS: Demonstrated on a pilot scale
SOURCES: Thagard Research Corp.
J. M. Huber Construction
40
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TECHNOLOGY: Molten Salt
Destruction
DESCRIPTION: Molten salt combustion is a
method of burning organic material while, at the
same time, sorbing the objectionable by-
products of that combustion from the effluent
gas stream. This process of simultaneous com-
bustion and sorption is accomplished by mixing
the air and waste into a pool of molten sodium
carbonate. The melt is maintained at tempera-
tures between 1500 to 2000° F, causing the hy-
drocarbons of the organic matter to be oxidized
to carbon dioxide and water, while elements
such as phosphorus, sulfur, arsenic and the hal-
ogens react with the sodium carbonate. These
by-products are retained in the melt as inorganic
salts and eventually build up and must be re-
moved in order that the molten bed remain fluid
andjetain its ability to absorb acidic gases. An
aslTconcentration in the melt of up to approxi-
mately 20 percent by weight is acceptable.
APPLICABILITY/LIMITATION: Molten salt can be
used to treat low ash or high chlorine content
wastes. Low water content is required and the
molten salt produced can be corrosive. The neu-
tralization of acid gases results in the formation
of other salts that can change the fluidity of the
bed and hence require frequent replacement of
the material. Used salts must be landfilled.
STATUS: Developmental, pilot-scale unit
available
SOURCES: Rockwell International
41
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TECHNOLOGY: Molten Glass
DESCRIPTION: This technology uses a pool of
molten glass as the heat transfer mechanism to
destroy organics and to capture ash and inor-"
ganics.The emissions include acid gas and any
particulates while all residues are contained in
the glass. The advantages include significant
volume reduction, most wastes are treatable and
the residual is stabilized, nonbreaking glass. The
process is based on existing glass making
technology.
APPLICABILITY/LIMITATION: Molten glass can
be used to treat any solid or liquid such as plas-
tics, asphalts, PCB or pesticides. Sodium sul-
fates greater than 1 percent of the final glass
may pose a problem. It is inappropriate for soils
or high ash waste and it requires additional
treatment for off-gas.
STATUS: The process is commercially available
for uses other than hazardous waste
incineration
SOURCES: Penberthy Electromelt International
Inc.
Battelle-Northwest
Westinghouse Electric Corp.
LIQUID
FEED DIRT
BOXED
WASTE
Ponborthy PYRO-CONVERTER
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TECHNOLOGY: Plasma Torch
DESCRIPTION: The plasma arc process func-
tions by contacting the waste feed with a gas
which has been energized into its plasma state
by an electrical discharge. The plasma torch
acts as one electrode and the hearth at the bot-
tom of the reactor acts as the second electrode.
The discharge of electricity between the two
electrodes causes the centerline temperatures
in the plasma to reach 9000° F. A small amount
of gas is introduced into the centerline region
and is ionized. The ionized gas molecules trans-
fer energy to the waste to cause pyrolysis of the
waste. Since the process is pyrolytic the scale
of the equipment is small considering the high
throughput rates. This characteristic makes it
potentially attractive for use as a mobile unit.
Gaseous emissions (mostly H2, CO), acid gases
in the scrubber and ash components in scrub-
ber water are the residuals. The system's advan-
tages are that it can destroy refractory
compounds and typically the process has a very
short on/off cycle.
APPLICABILITY/LIMITATION: This process is
applicable to liquid (pumpable) organic wastes
and finely divided, fluidizable sludges. It may be
particularly applicable to the processing of liq-
uid wastes with a high chlorine, pesticide, PCB
or dioxin content. Sludges must be capable of
being fluidized by the addition of a liquid. Waste
streams must be free of (or preprocessed to re-
move) solids, which prevent satisfactory
atomization.
STATUS: The application of plasma arc technol-
ogy to hazardous waste treatment is hindered
by a lack of operating experience. At this time,
the only operating plasma arc system that is be-
yond the research and development stage is a
pilot-scale mobile unit capable of 1 gal/min. of
waste. Westinghouse is developing this mobile
unit for the SITE Program.
VENDORS: Westinghouse Electric Corp.
Arc Technologies
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FIXATION/STABILIZATION PROCESSES
The intent of these processes is to immobilize the toxic and hazardous constituents in the waste. This
can be done by changing the constituents into immobile (insoluble) forms, binding them in an immobile,
insoluble matrix and/or binding them in a matrix which minimizes the material surface exposed to
solvent exposure. Each of the processes described herein accomplishes immobilization by one or more
such methods. Often the immobilized product has structural strength sufficient to help protect itself
from future fracturing (and concomitant exposure of additional "leachable" surfaces). Most of these
processes are proprietary.
Data Need
Important Fixation/Stabilization Treatment Data Needs
Purpose
The data needed is generally the same as that for both physical and chemical treatment processes.
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TECHNOLOGY:
Lime-Based
Pozzolan
Processes
DESCRIPTION: This technology treats wastes
and contaminated soils by the addition of large
amounts of siliceous materials combined with
a setting agent such as lime, cement or gypsum.
Such treatment results in a dewatered stabilized
solidified product.
APPLICABILITY/LIMITATION: This stabilization/
solidification process is used for sludges and
contaminated soils. Contaminants can include
metals, waste oils, and solvents. Materials such
as borates, sulfates, and carbohydrates inter-
fere with the process. Long-terrp stability and
resistance to leaching is good for some wastes
but is unknown for others.
STATUS: Commercially available
SOURCES: Different silicate processes
available
TECHNOLOGY:
Portland Cement
Pozzolan
Process
DESCRIPTION: This treatment is a minor variant
of the lime pozzolan process. This stabilization
treatment mixes the waste with portland ce-
ment to incorporate the waste into the cement
matrices.
APPLICABILITY/LIMITATION: This process is
effective for metal cations, latex and solid plas-
tic wastes. Large amounts of dissolved sulfate
salts or metallic anions such as arsenate and
borates will hamper solidification. Organic mat-
ter.'lignite, silt or clay in the wastes will increase
setting time.
STATUS: Commercially available
SOURCES: Aerojet Energy Conversion Co.
ATCOR, Inc.
Chem-Nuclear System, Inc.
Delaware Custom Materials
Energy, Inc.
General Electric Co.
Hittman Nuclear and Development
Co.
Stock Equipment Co.
Todd Research and Technical Div.
United Nuclear Industries
Westinghouse Electric Co.
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TECHNOLOGY: Sorption
DESCRIPTION: Contaminants are bound up in
pozzolan-type matrices by physical sorption or
chemisorptipn yielding a stabilized material
which is easier to handle. Liquid immobilization
depends on added ingredients. This process re-
sults in high concentrations of contaminants at
the surface of the material and contaminants
may leach. The treated material is permeable.
APPLICABILITY/LIMITATION: The process is
suitable for organics and inorganics. Advan-
tages to this technology include the fact that
raw materials are plentiful and inexpensive,
waste handling is improved, minimal pretreat-
ment is required and the product's bearing
strength is adequate for landfill disposal. Dis-
advantages include the fact that large volumes
of additives are required (albeit they are plentiful
and cheap) so that waste volumes to be dis-
posed are greatly increased. Furthermore, leach-
ate control is highly variable, free water may be
released under high pressure and there is tem-
perature sensitivity.
STATUS: In common use for treatment of metal
sludges removed from aqueous waste streams
SOURCES: Chemical Waste Management
TRICIL Environmental,
TECHNOLOGY: Vitrification
DESCRIPTION: Vitrification is a process
whereby hazardous wastes are converted into a
glassy substance utilizing very high tempera-
tures. The process is carried out by inserting
large electrodes into contaminated soils con-
taining significant levels of silicates. Graphite
on the surface connects the electrodes to the
soil. High current of electricity passes through
the electrodes and graphite. The heat causes a
melt that gradually works downward through the
soil. Sortie contaminant organics are volatilized
and escape from the soil surface and must be
collected by a vacuum system. Inorganic and
some organics are trapped in the melt, which,
as it cools, becomes a form of obsidian or very
strong glass. When the melt is cooled, it forms
a stable noncrystalline solid.
APPLICABILITY/LIMITATION: Vitrification was
originally tested as a means of solidification/
immobilization of low level radioactive metals.
It may also be useful for forming barrier walls.
This latter use needs testing and evaluation to
determine how uniform the wall would be and
stability of the material over a period of time.
STATUS: Demonstrated on a field scale
SOURCES: Battelle Northwest
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TECHNOLOGY: Asphalt-Based
(Thermoplastic)
Microencapsulation
DESCRIPTION: This technology involves the
mixing of heated dried waste within either an
asphalt bitumen, paraffin, or polyethylene ma-
trix, resulting in a stable solid waste mass. The
advantages are: waste volume reduction, low
permeability, elimination of free liquids, im-
proved handling and good strength.
APPLICABILITY/LIMITATION: This method is
applicable to hazardous waste that are complex
and difficult to treat. Waste that should not be
treated using this technology are: waste with
high-water content, strongly oxidizing contami-
nants, anhydrous inorganic salts, tetraborates,
iron and aluminum salts, and organics with low
molecular weights and high vapor pressures
(volatile). The disadvantages include the fact
that process equipment and materials can be
expensive and there is some potential for air
pollution.
STATUS: Commercially available
SOURCES: Werner A. Pfleidier
Aerojet Energy Conversion Co.
Newport News Industrial Corp.
TECHNOLOGY: Polymerization
DESCRIPTION: Polymerization uses catalysts to
convert a monomer or a low-order polymer of a
particular compound to a larger chemical mul-
tiple of itself. Often, such large polymers have
greater chemical, physical and biological sta-
bility than the monomers (or dimers or trimers)
of the same chemical.
APPLICABILITY/LIMITATION: This technology
treats organics including aromatics, aliphatics,
and oxygenated monomers such as styrene, vi-
nyl chloride, isoprene, and acrylonitrile. It has
application to spills of these compounds.
STATUS: Has been used on spills
SOURCES: Refer to buyer's guides for sources
of catalysts
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BIBLIOGRAPHY
1. U.S. Environmental Protection Agency, Handbook for Remedial Action at Waste Disposal Sites (Re-
vised), EPA/625/6-85/006, October, 1985.
2. U.S. Environmental Protection Agency, Treatment Technology Briefs: Alternatives to Hazardous Waste
Landfills, EPA/600/8-86/017, July 1986.
3. U.S. Environmental Protection Agency, Technology Briefs: Data Requirements for Selecting Remedial
Action Technology, EPA/600/2-87/001, January 1987.
4. Freeman, Harry M., Innovative Thermal Hazardous Organic Waste Treatment Processes, Noyes Pub-
lication, Park Riley, New Jersey, 1985.
5. U.S. Environmental Protection Agency, Mobile Treatment Technologies for Superfund Wastes, EPA
540/2-86/003(F), September 1986.
6. U.S. Environmental Protection Agency, Superfund Treatment Technologies: A Vendor Inventory, EPA
540/2-86/004(F), September 1986.
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frU.S. GOVERNMENT PRINTING OFFICE: Hf2 - 648-003/40747
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