EPA-670/2-74-088
November 1974
PROMISING TECHNOLOGIES
FOR
TREATMENT OF HAZARDOUS WASTES
By
Robert E. Landreth
Charles J. Rogers
Solid and Hazardous Waste Research Laboratory
Program Element 1DB311
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
-------
REVIEW NOTICE
The National Environmental Research Center—Cincinnati
has reviewed this report and approved its publication.,
Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
n
-------
FOREWORD
Man and his environment must be protected from the
adverse effects of pesticides, radiation, noise and other
forms of pollution, and the unwise management of solid
waste. Efforts to protect the environment require a
focus that recognizes the interplay between the com-
ponents of our physical environment—air, water, and
land. The National Environmental Research Centers
provide this multidisciplinary focus through programs
engaged in
• studies on the effects of environmental
contaminants on man and the biosphere, and
• a search for ways to prevent contamin-
ation and to recycle valuable resources.
Current research efforts directed at detoxifying
or recycling hazardous wastes are being studied; this report
presents the first year's progress of the study. Promising
methods are identified, reviewed, and suggested for further
development.
A. W. Breidenbach, Ph.D.
Director
National Environmental
Research Center, Cincinnati
-------
ABSTRACT
Numerous toxic and hazardous wastes are being generated
and improperly treated or disposed of by industrial sources.
The wastes produced have varied toxicities and possess
characteristics that make them unique. This study was
undertaken to identify and recommend promising waste treatment
technologies, the use of which would minimize the growing
threat to public health and environmental quality. Literature
searches, site visits, and personal communications with
experts in the field provided the basis for identifying needed
treatment technologies.
The rationale used in the selection of promising techniques
recommended for development were inadequacy of present technology,
and the economics, resource recovery, and volume reduction of the
new technology. Treatment processes that appear applicable for
processing both homogeneous and hetergeneous hazardous waste streams
include chemical, biological, and physical treatments.
This report is designed to fulfill the Office of Solid Waste
Management Programs request of May 16, 1973 that the Solid and
Hazardous Waste Research Laboratory identify and recommend for
future development promising treatment technologies for hazardous
wastes.
-------
CONTENTS
Page
Abstract iv
List of Figures V
Notes vi
Background and Introduction 1
Recommended Promising Treatment Techniques 3
A. Chlorinolysis 4
B. Wet Air Oxidation 7
C. Decomposition by Acids and Bases 11
D. Chemical Oxidation 12
E. Other Chemical Treatments 14
F. Biological Degradation 15
enzymes 15
trickling filters 17
activated sludge 19
G. Catalysis 20
H. Batch and Continuous Ion Exchange 20
I. Photochemical Processing 23
J. Low-Temperature Microwave Discharge 26
K. Osmosis/Ultrafiltration 27
L. Activated Carbon Adsorption 30
Promising Techniques Summary 30
References 34
FIGURES
No. Page
1. Typical Chlorinolysis Reactions 5
2. Basic Wet Air Oxidation System 8
3. Anaerobic Degradation of Lindane in Sludge 16
4. Countercurrent Continuous Ion-Exchange System 25
5. Nature of Microwave Discharge 27
6. Osmosis Theory 28
-------
NOTES
1. The mention of company names or products is not to be considered
as endorsement or recommendation for use by the U.S. EPA.
2. EPA policy is to express all measurements in Agency documents
in metric units. Implementing this practice results in difficulty
in clarity therefore conversion factors for non-metric units
used in this document are as follows:
British Metric
1 ft2 0.0929 meters2
1 ft3 0.0283 meters3
1 ft3/min 28.316 1/min
1 gpm 3.785 1/min
1 Ib. 0.454 kg.
1 ton (short) 0.9072 metric tons
-------
BACKGROUND AND INTRODUCTION
In a report to Congress on hazardous waste disposal June 30, 1973,
it was estimated that the total quantities of nonradioactive hazardous
waste streams generated by industrial sources amounted to 10 million
tons, or approximately 9% of the 110 million tons of all wastes
generated by industry. Geographically, approximately 70% of industrial
hazardous wastes are generated in the mid-Atlantic, Great Lake, and
Gulf Coast areas. Physically, about 90% of the hazardous wastes by
weight are found in the liquid waste stream. Approximately 40% of
these wastes are inorganic, and 60% are organic. In retrospect, it
was only in the last few years that an increasing number of questions
have been raised regarding the disposal of hazardous wastes and, if
in fact, the inadequacy of treatment/disposal technology did not
represent a substantial and growing threat to public health and
environmental quality.
Under Section 212 of Public Law 91-512, the Resource Recovery
Act of 1970, the U.S. Environmental Protection Agency was charged with
preparing a comprehensive report and plan for the creation of a system
of national disposal sites for the storage and disposal of hazardous
wastes. Section 212 mandated, in part, that recommended methods of
reduction, neutralization, recovery, or disposal of the materials be
-------
determined. Work called for by this mandate has been completed and
reports presenting information on treatment/disposal techniques are
now available.1'3 Needless to say, only the technical issues involving
definitions, nature, and magnitude of the problem to be solved and
the approaches to be used are provided in the reports. Technology
for disposing of hazardous wastes recommended in the reports generally
was based on the best available information. Where information was
limited, some estimates were made presumably with the expectation
that treatment/disposal data would result from future developing
processes. It is important to be aware that methodology recommended
for control of hazardous wastes1'3 may not have been employed in the
treatment of hazardous constituents in waste streams.
Recognizing the present inadequacy of treatment/disposal
technology, the Office of Water and Hazardous Materials, Office of
Solid Waste Management Programs (OSWMP) requested that the Solid
and Hazardous Waste Research Laboratory (SHWRL) of the National
Environmental Research Center-Cincinnati conduct a control technology
assessment. In OSWMP's assessment of control technology, it considered
the two basic options available for preventing damage that may arise
from land disposal: treatment or isolation of hazardous materials
that are disposed of into the environment. The OSWMP then specifically
requested that SHWRL complete reports on new treatment technologies
by June 30, 1974. This report therefore is prepared in fulfillment
-------
of the OSWMP request that several new promising treatment
technologies for hazardous wastes be identified.
The rationale used in the selection of techniques that appear
promising for development are:
1. Existing technology for hazardous waste is not
adequate.
2. Atlhough existing treatment is adequate, new
processes would neutralize or reduce the volume of
waste, require less energy to operate, and, thus,
be more economical.
3. Existing treatment is adequate, but new processes
could lead to maximum recovery of safe reusable products.
4. New treatments would eliminate the synthesis of
compounds equally or more toxic during processing, and
the processed materials having been rendered nonhazardous
would be safe for disposal.
It is assumed that future support for development by SHWRL of any of
the selected techniques to be described for detoxification of hazardous
wastes will be through mutual agreement between OSWMP and SHWRL.
RECOMMENDED PROMISING TREATMENT TECHNIQUES
By far, the majority of waste streams are mixtures, and those of
hazardous wastes are no exception. Most hazardous waste streams are
mixtures of pesticides, heavy metals, organic solvents, acids, or
bases, and have a high solids concentration. Promising methods
-------
for treating such complex streams — methods that need further
development and implementation -- are:
A. Chlorinolysis
B. Wet air oxidation
C. Decomposition by acids and bases
D. Chemical oxidation
E. Other chemical treatments
F. Biological degradation
-enzymes
-trickling filters
-activated sludge
G. Catalysis
H. Batch and continuous ion exchange
I. Photochemical processing
J. Low-temperature microwave discharge
K. Osjwosis/ultrafiltration
L. Activated carbon adsorption
A. CHLORINOLYSIS
4
Chlorinolysis appears to be a very desirable process for
eliminating some very toxic and hard to dispose of products. For
example, herbicide orange, still bottoms from organic manufacturing
operations, and pesticides can be converted by chlerinolysis to the
principal product, carbon tetrachleride. Chlerinolysis invelves
-------
chlorine to the waste material in special nickle—stainless steel
reactor under one of two sets of conditions: high pressure and
low temperature or low pressure and high temperature. No catalyst
is required for the vapor phase reaction. The mole ratio of chlorine
to carbon is between 4 to 1 and 8 to 1. Carbon atoms end up as
carbon tetrachloride. In addition, depending upon the starting
molecule, other byproducts may be formed. Possible byproducts formed
in the chlorinolysis of three typical pesticides are indicated by
the reactions shown in Figure 1.
HCB + CI2 - " CCI4
DDT + CI2 - » CCI4 + HCI
2,4,5 -T + CI2 - »CCI4 + HCI + COCI2
TYPICAL CHLORINOLYSIS REACTIONS
Figure 1
-------
The byproducts can be undesirable and require clean-up before
release to the environment. Although phosgene is a toxic byproduct
of chlorinolysis when carbonyl groups are present, it does have
commercial value and is used in the synthesis of plastics. Another
byproduct hydrochloric acid has limited commercial application and must
be neutralized before discharging into the environment. Limitations
on ocean and deep-well disposal make these types of disposal unacceptable.
Electrolysis technology can and is being used to convert waste
hydrochloric acid into chlorine and hydrogen for commercial use.
Electrolysis is competitive with the traditional caustic chlorine
process and is recommended as a method for cleaning up hydrochloric
acid in chlorinolysis. A possible deterent to the commercial
development of the chlorinolysis process is the poisoning effect
of sulfur. As little as 20 ppm will poison the system and render
the oxidation process ineffective. Research^ currently is under way
to investigate this and other related problems. An interim report
on chlorinolysis is expected by June 1975.
Dioxin-impurity, introduced by way of incompleteness of the
chlorinolysis reaction, has been investigated. Gas chromatograph
and mass spectrometer analysis, with an analytical limit of detection
of 10 parts per trillion, did not inducate any dioxin contamination
in the carbon tetrachloride formed in the reaction. lexicological
evaluation has not as yet been completed, but no evidence of dioxin
has been found thus far.
-------
B. WET AIR OXIDATION
The wet air oxidation process^ is another potential solution to
the problem of disposing of toxic and hazardous wastes. Although it
developed some 20 years ago and is a relatively expensive operation,
recent legislative prohibitions concerning deep well, lagoon, and
ocean disposal of processing wastes, coupled with the need to conserve
natural resources and recover energy, have resulted in wet air oxidation
becoming increasingly competitive with other types of treatment
processes.
The wet air oxidation process is diagrammed schematically in
Figure 2. Waste is pumped into the system by a high-pressure pump
and mixed with air from an air compressor. The waste is passed through
a heat exchanger and then into a reactor where atmospheric oxygen
reacts with the organic matter in the waste. The oxidation is
accompanied by a rise in temperature. The gas and liquid phases are
separated. The liquid is circulated through the heat exchanger before
being discharged. The gas and liquid are both exhausted through
control valves. System pressure is controlled to maintain the
reaction temperature as changes occur in the feed characteristics
(i.e., organic content, heat value, temperature). The mass of water
in the system serves as a heat sink to prevent a runaway reaction
that might be caused by a high influx of concentrated organics.
-------
oc
Q
111
H
(0
>-
CO
z
O
X
O
H
UJ
£
O
(/>
to
CVJ
CD
3
cn
-------
The degree of oxidation can be varied from 0% to 100% to meet
treatment requirements for a given waste stream. Holding the
temperature to about 150°C allows only 5% to 10% oxidation, whereas
nearly complete oxidation, depending on the type of waste being
oxidized occurs at 320 °C. The basis flow sheet shown in Figure 2
can be varied to meet the requirement of the individual plant or
waste stream. Systems have been designed to recover energy and
for generating saturated or slightly superheated steam. In addition,
because of the flexibility of the system, it appears that reusable
byproducts, such as alochols, organic acids, etc., can be produced.
Wet air oxidation and thermal conditioning are competitive
processes that eliminate the need for costly chemicals used in
other treatment processes. The economics of wet air oxidation is
dictated by three principal factors: (1) volumetric throughput,
(2) COD of the wastewater, and (3) oxidation characteristics of the
waste. Operating costs are affected by the amount of air to be
compressed. Plants requiring more than 2500 compressor horsepower
generally show a negative operating cost; that is; the value of
power or steam generated exceeds the value of utility and labor
required to operate the plant. Wet air oxidation becomes economically
feasible when the organic content of a hazardous waste stream is
extremely high (> 10,000 mg/£ BOD), the waste stream is toxic or
marginally biodegradable, and land disposal is prohibited or expensive.
-------
This process also is applicable to low pressure oxidation of
sludges whereby the required vaccum filter area can be reduced by
80% to 90% of that required for chemically conditioned sludges.
By increasing the temperature and the amount of air, COD reductions
of 80% to 90% and sludge volume reductions of 95% to 99% can be
accomplished. The complex and expensive air pollution controls
required in incineration make wet air oxidation competitive with it,
since emissions from wet air oxidation can be controlled. In the wet
air oxidation process, the usual interfering agents such as sulfur,
phosphorus, and chlorinated hydrocarbons, are oxidized to their
respective acids, carbon dioxide, and water. Thus, proper operation
and control of the discharges from the system eliminates toxic and
hazardous emissions.
Wet air oxidation has been used in reclaiming sodium hydroxide
from spent caustic pulping liquor. Concentrations of acrylonitrile
in waste streams have been reduced from 2000 mg/£ to 6 mg/£, in
addition to completely oxidating total solids and sulfur. Effluents
containing cyanide from coke production may also be treated by way
of wet air oxidation. A bonus is the concomitant production of a
usable steam or power recovery. Explosives can be safely disposed
of by wet air oxidation since in the process they are handled as a wet
slurry, which is a safe form. Thus, dangerous conditions as well as
air pollution are eliminated. Yet another application of wet air
oxidation is in the recovery of chromium and silver from waste streams
containing these two metals. Previously, incineration of such metal
10
-------
waste streams left the inorganic chemicals in an undesirable form
or resulted in the loss of the metals by way of the flue gas discharge.
Wet air oxidation may be used in the smelting of ores, e.g., sulfides
are converted to sulfates. This approach to smelting eliminates
the air pollution created in the conventional smelting of sulfide ores.
Except in the recovery (and hence removal) of metals, wet air
oxidation is not directly applicable to most metallic waste streams
because of the oxidation of the metal to a higher valence state and,
hence, more toxic waste. Nevertheless, wet air oxidation systems
can be economically designed to treat several types of hazardous
waste streams. Wet air oxidation even has a use in industry disposing
of radioactive waste. With its use, a 1000-fold decrease in the volume
of some radioactive byproducts can be expected.**
C. DECOMPOSITION BY ACIDS AND BASES
Within practical capabilities, chemical treatment may provide
Q
limited success. Kennedy et al. reported that the addition to or
reaction of eight selected commercial pesticide formulations with
strong acid or strong alkali compounds resulted in partial decomposition
of the pesticides. Sodium hydroxide caused only slight changes in the
structure of dieldrin. Malathion was decomposed sufficiently to produce
inorganic phosphate, and 2,4-D was hydrolyzed to a sodium salt.
Picloram was decarboxylated, with the chlorine being replaced by an
11
-------
hydroxyl group. The toxicities of the end-products were not determined.
They also used a sodium biphenyl compound to decompose five other
pesticidal compounds, and obtained very desirable results. However,
the usefulness of sodium biphenyl compound is limited from a practical
standpoint in that it is not stable for extended periods of time when
stored at temperatures above 0°C. When a sodium-liquid ammonia
treatment was applied, 16 to 19 pesticide compounds were completely
degraded. Only eight were completely decomposed with the use of a
lithium-liquid ammonia treatment. In the degradation process, several
toxic gases were produced that, in a practical operation, would have
to be scrubbed from the gas stream before release to the atmosphere.
These gases included chlorine, hydrogen chloride, hydrogen sulfide,
and certain nitrogen gases.
Price'' reported that carbaryl, DDT, and toxaphene were decomposed
when exposed to alkaline conditions. Decomposition did not necessarily
constitute a solution to the problem since it only served to alter the
compounds, and disposal was still a problem. Price also suggested a
method to remove chlorine from organochlorine pesticides that was
expensive and hazardous, due to the chemicals involved. Moreover,
disposal of its byproducts or end-products would be a problem.
D. CHEMICAL OXIDATION
In reports by several research teams^2~^ to the pesticide industry's
waste management program, several oxidants and pesticides were discussed.
12
-------
Among the oxidants were chlorine, chlorine dioxide, potassium
permaganate, ozone, and peroxide. Pesticides used with the above
oxidants included DDT, Lindane, Parathion, Dieldrin, 2,4,5-T Ester,
Endrin, Aldrin, Toxaphene, Sulfoxide, 2,4-DCP, and 2,4-D compounds.
Potassium permanganate readily oxidized 2,4-DCP and attacked Aldrin
and Lindane when in an aqueous solution. Unsaturated organic
compounds were found to be more susceptible to ozone oxidation that were
saturated compounds. Parathion was oxidized by both chlorine and
ozone, but the more toxic compound paraoxon was produced. Ozonation
removed 90% of the Dieldrin and aeration, 80%. This removal rate
was produced starting with an initial concentration of Dieldrin of
about 0.2 mg/^'in distilled water, an ozone concentration of 3.9% by
weight in air injected at 0.3 £/m through a 2.5-£ reactor.
16
Goma and Faust used potassium permanganate, chlorine, and
chlorine dioxide to remove residual diquat and paraquat from water.
Thier results showed the reaction rates to be very fast, and the
rate of reaction with potassium permanganate to vary greatly with pH.
This oxidant appeared to have more effect in an alkaline solution than
in an acid medium. Chlorine had no effect on diquat or paraquat under
acidic conditions. On the other hand, an increase in pH increased
the rate of the oxidation.
Treating electroplating rinse streams with a proprietary peroxygen
compound effectively destroys free cyanide and precipitates zinc and
cadmium. The reaction is fast and simple to control. In less than
13
-------
an hour, the treated rinse can be released to the sewer after having
collected the precipitates on a filter. Research under way indicates
that other cyanide-containing wastes may be treated this way.
Generally speaking, any type of organic waste can be totally oxidized
to carbon dioxide and water. However, the process economics dictate
that oxidation be terminated when the toxicological properties of
the waste have been destroyed.
E. OTHER CHEMICAL TREATMENTS
Heavy metals in plating wastes have always presented a disposal
problem. Usually it was uneconomical to install treatment facilities
for the low-flow rates characteristic of plating. However, in a 1973
18
report, it was pointed out recent inovations allow the flexible
plater to meet current discharge requirements at negligible capital
and low chemical costs. Hexavalent chromium can be reduced to the
trivalent state by the addition of ferrous sulfate, which can be
obtained free of charge from steel picklers. Five pounds of pickle
liquor are required for every pound of chromic acid to be destroyed.
The same report also states that cyanide can be destroyed by trickling
sodium hypochloride into the copper bath rinse stream water. Five
gallons of 16.5% solution of sodium hypochloride is required per
pound of cyanide to precipitate the copper. Nickel is precipitated
out of the rinse water by combining the electrocleaner rinse water
with the rinse stream from the nickel tanks. The alkalinity of the
former raises the pH of the latter above 8 and causes the nickel to be
14
-------
preciptated as a hydroxide. The preciptated metal can then be removed
by settling and filtration.
F. BIOLOGICAL DEGRADATION
Biological treatments have been used extensively in treating
hazardous and nonhazardous manufacturing wastes. Among the several
types of biological systems that have been used are trickling filters,
activated sludge systems, aerated lagoons, and stabilization ponds.
Numerous studies have been made of the biological degradation of several
pesticidal formulations. These studies involved microbial degradation
under aerobic and anaerobic conditions. Pesticides used in the studies
were Parathion, Methyl Parathion, DDT, Dieldrin, 2,4-D, 2-CPA, MCPA,
Sienex, Fexoc, Delapon, CDAA, CIPC, 2,4,5-T Hydrochlor Expoxide, Lindane,
Heptachlor, Endrin, ODD, and Aldrin. An example of biological reaction
is the anaerobic degradation of Lindane. The extent of the breakdown
of Lindane in a sludge containing 1.5% dry solids (56% volatile) is
19
indicated by the graph in Figure 3.
Enzymes
The use of immobilized enzymes may prove to be very effective
on
in the control on hazardous or toxic wastes. According to one report ,
immobilized enzymes can be regarded as ones with a handle, which thereby
allows them to be used repeatedly in unit processing operations.
Enzyme technology is being investigated with the objective of developing
a treatment for concentrated phenolic waste that could be used as a
polishing treatment step to remove phenols from waste water. Although
15
-------
1 ppm LINDANE ADDED
10 ppm LINDANE ADDED
2 4 6 8 10
DAYS AFTER PESTICIDE INJECTION
ANAEROBIC DEGRADATION OF LINDANE IN SLUDGE
Figure 3
16
-------
the enzymes presently being used have a useful life-time of only 1 week,
longer lasting, more stable enzymes are being investigated. Since many
hazardous compounds are phenolic derivatives, immobilized enzymes
may be useful as a polishing step to a number of final detoxification
processes. Enzymes are used in hydrolytic processes for the synthesis
of materials and in processes that involve either oxidation or reduction.
20
Enzyme inhibition is being used at Louisiana State University in the
design of sensors for the detection of pesticides, cyanides, and other
hazardous materials.
21
The field of enzymes technology is not without problems. The
promised advantage of enzymes being able to carry out useful tasks
with a high degree of specificity at ambient temperatures and with
few side reactions is offset by the high cost of the enzymes. The
high cost necessarily dictates conservation and reuse. The use of
immobilized enzyme technology appears to be a promising course of
action, and it could become competitive with other hazardous waste
treatment processes. Several industries utilize enzyme systems.
Because of the highly competitive nature of the field of developing
enzyme technology, they are reluctant to discuss any information
regarding their respective systems.
Trickling Filters
Trickling filter units are used primarily as load leveling tanks,
although some BOD reduction is achieved. As a roughing filter, up to
85% BOD reduction can be accomplished on a single pass; and more
17
-------
importantly, the system is able to withstand fluctuating waste!oads
and toxic slugs.
The organisms that accomplish waste treatment in a biological
filter are found in the biological slimes attached to the filter
medium. The microorganisms making up the slime assimilate and oxidize
soluble nutirents contained in the waste waters passed through the
filter. The oxygen needed to oxidize the wastes comes by way of forced
or natural air movement through the filter. Rocks or synthetics may
be used as a filter medium. The use of synthetic media has greatly
increased the efficiency of filters because of a lessened tendency
to plug and the provision of effective ventilation. With the use of
a synthetic medium, filters as deep as 20 feet can be used without
trouble with some wastes.
Normally, a hydraulic loading rate of less than 0.5 gallon of
waste per minute per square foot of filter surface is applied to a
trickling filter.^ For "roughing filters," the organic loading is
relatively unimportant, but it should be sufficient to utilize the
organisms for waste removal. An idea of the effect of organic and
hydraulic loading rates on extent of waste treatment is given by the
information in the following table, in which are listed data obtained
23
from two plants that manufacture herbicides:
Plant
A
B
Organic
loading
#71000 ft3/day
25
45
Hydraulic
loading
gpm/ft^
0.11
0.24
BOD
reduction
%
80
72
Phenol
reduction
%
70
54
18
-------
Note that high rate filters should be used only in special
circumstances. In most cases, some dilution is needed to reduce
toxicity and the concentration of dissolved salts before biological
treatment can become effective.
Activated Sludge
In an activated sludge system, most organics, including pesticides,
pesticide isomers, solvents, and organic byproducts, can be utilized
1? 1 "3 19 24-27
and hence decomposed by the bacteria that make up activated sludge. '''
In essence, this biological oxidation system is a fluidized reactor
consisting of a concentrated biomass supplied with organic waste and
forced oxygen. Part of the biomass is recirculated while the remainder
is allowed to coagulate and settle. The settled mass is disposed of
into the environment after an appropriate treatment. Oxygen supply is
an important operational factor because the microbial mass can function
effectively only in the presence of an adequate supply of the element.
In one plant, from 95% to 99% reduction of pesticidal compounds
is achieved by holding the waste in an aeration basin for 6 days. BOD
removal is on the order of 99%. Operating parameters necessary for the
plant's operation are a COD loading of 12,000 pounds per day and an
air flow up to 24,000 cfm. Clarified effluent and excess biological
solids are sent from the plant to a municipal treatment plant (activated
sludge) for final treatment.
Areas in need of further research and development are those concerned
with the design of trickling filters, activated sludge system, and
19
-------
stabilization ponds, as well as the adaptation of microbial populations,
suited to the destruction of specific hazardous wastes.
G. CATALYSIS
Catalytic conversion techniques are currently being investigated.28
The utility of the technique is illustrated by the removal of the poison
thiophene from benzene by a single-pass catalytic process. With the use
of chromia alumia as the catalyst, thiophene was reduced from a concentration
of 1CT ppm in benzene to one of 10~ ppm. It has been suggested that
dichloro-dibenzo-p-dioxins can be dechlorinated by palladium on charcoal.^9
Nickel boride also may be useful in the dechlorination of hazardous
materials. Although nickel boride has not been used in dechlorination,
it has been applied to the hydrogenation of olefins and the desulfurization
of thoils. Total dechlorination of isodrin has been accomplished by
exposure to lithium metal in tetrahyrofuran and t-butyl alcohol. These and
other applications provide evidence that catalysts may be discovered
that will remove the group or element conferring toxicity to an original
chemical structure, and thereby leave a building block available for
po
the synthesis of a useful chemical. An interim report^ on catalysis of
pesticides is being prepared and will provide information on the
effectiveness of this technique.
H. BATCH AND CONTINUOUS ION EXCHANGE
Ion exchange media have been and are being developed to concentrate
and remove the hazardous components from a variety of waste streams.30,31
Originally developed to soften or demineralize water, ion exchange
20
-------
methods can be adapted to batch, to continuous flow, and to counter-
current continuous-flow operations. Advantages include high throughput
rates per unit size, efficient chemical utilization, small dilution
process streams, lessened water requirements, and a uniform product
quality over the entire cycle. Two major disadvantages are that it is
a relatively complex mechanical operation and that it greatly depends
on instrumentation.
Kennedy32 has described a new synthetic polymeric adsorbent
(Amberlite XAD4) for treatment of effluents from the manufacture of
pesticides. Amberlite XAD4 is a resin characterized by a chemically
inert surface that allows very efficient regeneration. In addition,
it is hard and resilient and is highly resistant to attrition. The
adsorbent's high degree of porosity, extensive surface area, and uniform
pore distribution favor rapid adsorption kinetics, high operation
efficiency and low leakage. A substantial amount of laboratory data
indicates that isopropanol is more effective than methanol in regeneration
and the adsorbent is superior to activated carbon in regeneration
efficiency and adsorption kinetics. Experiments suggest that leakage
of chlorinated pesticides from the adsorbent was not noticeable until
more than 39 bed volumes had been treated. A distinct advantage in the
use of this adsorbent is that the regenerant can be recovered by heating
to leave a residue of the pesticide that can be recovered or easily
disposed of because of the significant volume reduction*
21
-------
33
Ion exchange resins made of peanut skin or walnut expeller meal
have been tried. The two resins were used in adsorption tests with
heavy metals. Known concentrations of heavy metals were passed through
packed columns and eluted with alkaline or acidic solutions. The
fractions and adsorbents were then analyzed by standard atomic adsorption
methods. Results indicated that the adsorbents removed 10 percent of
their weight of mercuric at a flow rate of 2500 t/m. An advantage in
the use of peanut waste was that mercury was effectively adsorbed over
a wide pH range, and at low concentrations, i.e., parts per billion.
Soil also has very excellent ion exchange capacity^ and is the
subject of current research.3^ However, insufficient data are available
at the present time to permit a meaningful evaluation.
A compact, chromic acid waste reclamation system based on ion
34
exchange principles is currently being used in Canada. With the use
of the system, more than 99.5% of the chromic acid is recovered from
the plating rinse waters. The acid can be returned to the process.
The unit also removes undesirable metallic impurities and, thus, allows
the electrolyte to work more efficiencly than in the original bath.
The unit combines three, short ion exchange beds, one containing anion
resins and the other two containing cation resins in a reciprocating
flow system to reclaim the chromic acid. Since the operation takes
place in a closed-loop, countercurrent, ion exchange mode, the chromic
acid is more concentrated and high recovery efficiency is achieved
than with conventional ion'exchange system.
22
-------
A typical continuous countercurrent ion exchange system is
illustrated in Figure 4. The system is divided into three sections
(pulse, regenerating, and contacting) and operates in a run and pulse
mode. During the rum mode, the raw waste is fed in at the top of
the contact section. Treated product water is delivered at the bottom
of the bed. Simultaneously, regenerant is fed through the loaded resin
in the regenerating section at the bottom of the loop and exists as
waste after stripping the resin free of unwanted ions. If needed, makeup
resin is supplied during this time period. Rinse water is passed
through to wash any traces of regenerant from the stripped resin. In
the pulse mode, valves separating the three sections are opened and feed
and waste valves are closed. This allows the resin bed to be "pulsed"
around a certain distance to provide fresh resin for the contacting
section to enable new resin to be generated, and to add some resin in
the storage area.
I. PHOTOCHEMICAL PROCESSING
The influence of light and, in particular, sunlight on chemical
reactions is a part of everyday life (e.g., plant photosynthesis, fabric
fading, smog, skin reactions, etc.). Only recently has it been
recognized that sunlight can influence environmental chemical reactions.
Water and air deserve particular attention with regard to photodegradation
processes, because of the transparency to ultraviolet light, pervasive
significance to life, and their own reactivity.
Water properties serve both as a medium for and reactant in ionic
processes. Besides the usual hydrolytic reactions, water provides
23
-------
photonucleophilic displacements such as replacement of chlorines by
hydroxyl groups in aromatic compounds. The photodegradation of such
diverse compounds of nitrogen, dexon, and PCP can also be shown to be
a result of photonucleophilic reactions. Photooxidation and photo-
reduction play an important role in the degradation of xenobiotics
by light.
Herbicides react favorably with the ultraviolet region of the
spectrum. Laboratory studies by Plimmer^ indicate that with halogenated
herbicides, the loss of halogen was the dominant process and was affected
by the orientation and electronic effect of a substituent. A free
phenyl radical, generated by the photoreaction, would react by
hydroxylation or by replacement of chlorine by hydrogen in an aqueous
solution; although, under certain environmental conditions, it could
react differently.
A field assessment of the effect of photodecomposition processes on
herbicides is very difficult because of competing modes of loss such as
volatilization, microbial reactions, and leaching. Results in one case
do suggest that products isolated from plants after field application
were identical to products produced by photochemical decomposition.36
Several studies have been completed on photochemical methods for
treating pesticides3?-^ and waters containing hazardous waste^^,43
such as phenols and other organic compounds that absorb light in the
ultraviolet region. Generally, artifical light from fluorescent
ultraviolet lamps having a spectrum comparable to that of sunlight was
24
-------
OVERFLOW
TO RESIN &
RECYCLE TANK
RAW WATER
BACKWASH
rcfb &
PULSE
POSITIVE
PULSE _
CONTROL
REGENERATING
SECTION
CONDUCTIVITY
CONTROLLER
REGENERANT
COUNTERCURRENT CONTINUOUS
ION EXCHANGE SYSTEM
Figure 4
25
-------
used. In all cases, results were comparable in terms of decomposition.
The photolysis rates for pesticides were strongly dependent on the
amount of chlorination. The experiments conducted under idealized
conditions indicated that organic hydrogen donors are needed to energize
the rapid destruction of certain pesticides. These donors may be present
in the environment as waxy cuticles of green leaves, surface films
on water, or the spray oils or aromatic solvent incorporated into the
pesticide/herbicide formulation. Bare surfaces of soil and water offer
little opportunity for the photodecomposition process.
J. LOW-TEMPERATURE MICROWAVE DISCHARGE
Investigations have been conducted with the objective of treating
the organic pollutant in the presence of interferring agents. Results
indicate that the rate of organic oxidation by microwave discharge within
a given irradiation time is increased radiation intensity and is independent
of interferring agents. For a specified amount of absorbed radiant energy,
lower intensities produce more overall organic oxidation than do higher
intensities.
According to one study,45 microwave discharge may be used to
detoxify toxic or hazardous wastes. Preliminary results indicate that
phosphonates, acetate can be efficiently decomposed by this process.
The process variables include, but are not limited to, the nature
of the carrier gas, flow rate, concentration, power input, residence
time, and total pressure. Decomposition products can be controlled to
26
-------
yield gases, liquids, or solids. The mechanism involved in low-temperature
microwave discharge is shown in Figure 5.
1. Microwave energy + electron energy » electrons* + hr
transfer
via elastic
collisions
2. e* + He inelastic > He* + 2e
collisions
3. e* + He »Hed9eV) + e
4. He* + 2He >Het> + He
... ., low molecular wt
5. e*+ Haz.mat. >[Haz.mat*] »• products + e
6.He*+ Haz.mat. -»[Haz.mat*] •> CO2 + H2O + He
* indicates an electromagnetically excited, or energized atom
or molecule.
NATURE OF MICROWAVE DISCHARGE
Figure 5
K. OSMOSIS/ULTRAFILTRATION
The imposition of increasingly stricter effluent standards has
brought an increase in the utilization of another type of treatment
process, namely, reverse osmosis. Reverse osmosis, although primarily
thought of as a water or waste water treatment process, can be used in
hazardous waste application. ^ Osmosis is the spontaneous flow of
a solvent form a dilute to a concentrated solution across an ideal
semi-permeable membrane, which impedes passage of solute but allows
27
-------
solvent flow. At a certain valve of pressure (the osmotic pressure)
equilibrium is reached and the amount of solvent that passes in each
direction is equal. If the pressure is increased above the osmotic
pressure on the solution side of the membrane, the flow reverses.
Ideally, pure solvent will then pass from the solution into the solvent.
These basis processes are shown in Figure 6.
Osmosis
Fresh
Water
Saline
Water
Osmotic
Equilibrium-i
Reverse
Osmosis
Pressure
Semipermeable
Membrane
OSMOSIS THEORY
Figure 6
28
-------
In the electroplating industry, proper operation demands that the
paint bath should be kept at a constant concentration. In flux of rinse
water and paint, usage brings about a lowering of the concentration.
The result is that water must be continuously removed. Contaminants
such as chromates, phsophates, chlorates, and sulfates also find their
way into the tank and must be removed. By means of an ultrafiltration/
reverse osmosis process, unwanted contaminants can be removed and the
paint solids returned to the dip tank. Acceptance by the industry of
the ultrafiltration/reverse osmosis process has resulted in substantial
savings.
The plating industry also loses or discharges a majority of its
metal inventory to the environment. This practice could be changed
bu using reverse osmosis to purfiy low-level plating rinse waters;
plating ions could be concentrated to levels where it would become
economically attractive to recycle the wastes to the plating bath.
Reverse osmosis coupled with appropriate chemical pretreatment
and post-treatment oxidation can supplant the sometimes unreliable
physiochemical-biological step in the removal of organics from
pesticide and petroleum refinery operations. Trace quantities of
heavy metals and organics usually are picked up during the metal-
finishing operations. Through reverse osmosis and electrodialysis, a
water can be produced that is suitable for reuse, and thus water
consumption can be decreased.
29
-------
The pulp and paper industry is making progress in removing
hazardous materials from its wastes. For it, reverse osmosis
provides an attractive alternative as a first concentration step for
bleach plant effluents because of the biological oxidation resistant
dissolved organics and salts. Research in this area has been hampered
by problems such as high back pressures, fouling, and tubular development.
L. ACTIVATED CARBON ADSORPTION
Pesticide industry research on activated carbon adsorption indicates
this method to be successful in reducing pesticide concentrations in the
waste stream.48'51 In some studies, 2,4-D, Aldrin, Dieldrin, and DDT
were completely removed at all concentrations with the use of activated
carbon. Removal was not as complete in other studies, although it
generally was higher than 90%. Contract time played an important
part in the removal efficiency in the process. To remove greater than
80% of DDT, Aldrin, and Dieldrin, at least 1 hour contact time and
carbon dosages of 100 mg/£ were required when wood or coconut charcoal
was used.
PROMISING TECHNIQUES SUMMARY
A review of current research activities indicates that a substantial
effort is being directed toward the development of processes or treatments
for the control of toxic and hazardous wastes. It should be recognized
that some of the techniques proposed for development may have been
investigated under ideal conditions, and their success may in part be
due to the presence of only a single hazardous or toxic component in
30
-------
the waste stream. It should be further realized that a practical
technology for the control of all types of hazardous and toxic waste
streams has not as yet been fully developed. Consequently, a continuous
effort will be required to develop and maintain acceptable treatment
operations. A suggested course of action would be to further research
the techniques described herein so as to develop practical and effective
treatment processes for mixed hazardous waste streams. The following
summary of promising techniques is based on the rationale that treatment
technology is inadequate, energy could be used more efficiently, and
there exists a potential for the recovery of safe reusable products.
In some cases the recommendations are made knowing that incomplete
processing data are available to make sound scientific judgements.
However, the preliminary data indicated that with sufficient refinements
viable processes could be developed. Since products from the petroleum
industry have added a new dimension to the economic picture of process
operations and product recovery, the economic issues over and above
those specifically mentioned with each process cannot be determined at
this time.
Recommendations and potentials for specific areas requiring
additional research are:
1. Chemical treatment methods, including oxidation with
chlorine dioxide, potassium permanganate, ozone, and
peroxide, have been shown to be capable of removing in
excess of 95% of certain hazardous materials from hazardous
31
-------
waste streams. Further research is needed to identify
efficient oxidants and to optimize treatment processes for
a variety of hazardous wastes.
2. Wet air oxidation could potentially solve many treatment
problems if its economics were improved. Research on the use
of oxidants such as ozone and pure oxygen, instead of compressed
air, may provide the needed economic improvement.
3. Biological degradation has proven to be an effective
method for the detoxification of certain hazardous wastes.
Condition requirements for maximization of treatment are
still ill-defined. Further, research is needed to fully
quantify the parameters. Since biological degradation
treatment systems are inexpensive, they should be thoroughly
researched and developed for single and complex hazardous
waste streams.
4. Ion exchange technology could be developed for
concentrating toxic metal ores. Environmental
pollution from heavy metal streams, which frequently
occurs, could be abated by the use of ion exchange
technology. In addition, dilute streams of organic
and organometallic materials could be isolated for
treatment/disposal, if ion exchange technology were
fully research and developed.
32
-------
5. Photochemical treatment has been in limited use for
the detoxification of several hazardous components in
processing waste streams. Preliminary data suggest
that detoxification of hazardous wastes by this process
appears to be rapid and effective and the formation
of toxic byproducts is prevented. Research and
development should be directed toward overcoming existing
equipment constraints.
6. Results with low-temperature microwave discharge
methods for destroying hazardous toxic compounds are
very encouraging. A number of hazardous materials
have been destroyed with the use of microwave discharge
without an accompanying formation of toxic byproducts.
In addition, the problem arising from the formation of
such compounds as the teratogenic agent dioxin resulting
from the imporper incineration of certain pesticides
could potentially be eliminated through the development
of this process. Additional research is needed to verify
conclusions obtained to date, improve and optimize the
hardware, investigate radio-frequency and corona discharge
effects, and expand the technique to other unrelated
classes of toxic compounds.
33
-------
REFERENCES
1. Ottinger, R. S., J. L. Blumenthal, D. F. Dal Porto, G. I. Gruber,
M. J. Santy, and C. C. Shih. Recommended Methods of Reduction,
Neutralization, Recovery or Disposal of Hazardous Waste. NTIS
Publication No. PB224579 set/AS. August 1973.
2. A Study of Hazardous Waste Materials, Hazardous Effects and Disposal
Methods. Booz Allen Applied Research Inc. BARRINC Report No.
9705-003-001. June 30, 1972.
3. Program for the Management of Hazardous Wastes. Battelle Memorial
Institute, Pacific Northwest Laboratories, EPA Contract No.
68-01-0762. July 1973.
4. Emerging Technology of Chlorinolysis. Environmental Sciences and
Technology. 8:18-19. January 1974.
5. Private telephone communication with Mr. Paul DesRosiers,
Industrial Pollution Control Division, Office of Research and
Development, EPA, Washington, D.C.
6. Pradt, L. A. Developments in Wet Air Oxidation. Chem. Eng.
Progr. 68:72-77. December 1972.
7. Ely, R. B. Wet Air Oxidation. Pollution Engineering. 5:37-38.
May 1973.
8. Private telephone communication with Mr. Ely, Industrial Engineer
with Zimpro, Rothschild, Wisconsin.
9. Kennedy, M. V., B. J. Stojanovic, and F. L. Shuman, Jr. Chemical
and Thermal Methods for Disposal of Pesticides. Residue Rev.
29:89-104. 1969.
10. Kennedy, M. V., B. J. Stojanovic, and F. L. Shuman, Jr. Chemical
and Thermal Aspects of Pesticide Disposal. J. Environ. Quality.
1:63-65. January 1972.
11. Price, J. D. Disposal-Pesticide and Pesticide Containers. Fact
Sheet L-1008 Co-op Exten Work in Agriculture and Home Economics,
Texas A&M University.
12. Robeck, G. G., K. A. Dostal, J. M. Cohen, and J. F. Kreissel.
Effectiveness of Water Treatment Processes in Pesticide Removal.
J. AWMA. 57:181-199. February 1965.
34
-------
13. Aly, 0. M., and S. D. Faust. Removal of 2,4-Dichlorophenoxyacetic
Acid Derivatives from Natural Waters. JAWWA. 57:221-230.
February 1965.
14. Buescher, C. A., J. H. Dougherty, and R. T. Skrinde. Chemical
Oxidation of Selected Organic Pesticides. JWPCF. 36:1005-1014.
August 1964.
15. Cohen, J. M., L. J. Kumphake, A. E. Lemke, C. Henderson, and
R. L. Woodward. Effects of Fish Poisons on Water Supplies.
JAWWA. 52:1551-1565. December 1960.
16. Goma, M. Hassan, and S. D. Faust. Kinetics of Chemical Oxidation
of Dipyridylium Quaternary Salts. Agricultural and Food Chemistry.
19(2):302. Mar/April 1971.
17. Sandoski,Dorothy A. (ed.) Industrial Pollution Control Technology
Bulletin No. 119, 1(5). November 1973. The Franklin Institute
Research Laboratories, Philadelphia, Pa. 19103.
18. Sandoski, Dorothy A. (ed.) Industrial Pollution Control Technology
Bulletin No. 136, 1(6). December 1973. The Franklin Institute
Research Laboratories, Philadelphia, Pa. 19103.
19. Hill, D. W., and P. L. McCarty. Anaerobic Degradation of Selected
Chlorinated Hydrocarbon Pesticides. JWPCF. 39:1259-1277.
20. Enzyme Utilization - A Sleeping Giant. Environmental Science
and Technology. 7:106-107. February 1973.
21. Is the Bloom Off Enzyme Engineering. Chem. and Eng. News.
52(5):14-15. February 1974.
22. Fair, G. M., and J. C. Geyer. Water Supply and Waste-Water Disposal.
New York, John Wiley & Sons, Inc. p. 703-754. 1967.
23. Atkins, P. R. The Pesticide Manufacturing Industry-Current Waste
Treatment and Disposal Practices. Environmental Protection
Agency, Washington, D.C. Publication No. 12020 FYE, January
1972. p. 44-52.
24. Ultimate Disposal of Advanced Treatment Waste. AWTR-3, U.S. Dept.
of HEW. 1963.
25. Chucku, C. I., J. L. Lockwood, and M. Zabik. Chlorinated Hydrocarbon
Pesticides: Degradation by Microbes. Science. 154:3751. 1961,
35
-------
26. Loos, et_._ al_^ Phenoxyacetate Herbicide Detoxification by
Bacterial Enzymes. Journal of Agricultural and Food Chemistry.
15:858. 1967.
27. Randall, C. W. Biodegradation of Palathion in an Aerobic
Biological System. M.S. Thesis. The University of Kentucky,
Lexington, Kentucky. 1963.
28. Kranich, Wilber L. Worcester Polytechnic Institute. EPA
Grant 802857, awarded 7/1/73. Unpublished.
29. Dennis, W. H., Jr. Methods of Chemical Degradation of Pesticides
and Herbicides. A Review. U.S. Army Medical Research and
Development Command Publication No. AD 752123. October 1972. 31 p.
30. Miller, John R. Fundamentals of Ion Exchange. Chem. and In.
No. 9. 9:401-413. May 5, 1973.
31. Roulier, M. H., SHWRL, NERC, EPA, Cincinnati, Ohio. Research
being conducted at Dugway Proving Ground, Utah, under
Interagency Agreement No. EPA-IAG-D4-0043.
32. Kennedy, David C. Treatment of Effluent from Manufacture of
Chlorinated Pesticides with a Synthetic, Polymeric Adsorbent,
Amber!ite XAD-4. Environmental Science and Technology.
7:138-141. February 1963.
33. Sandoski, Dorothy (ed.) Industrial Pollution Control Technology
Bulletin No. 087, 1(4). October 1973.
34. Modern Power and Eng. 67:46-47. June 1973.
35. Plimmer, J. R. The Photochemistry of Halogenated Herbicides.
Residue Rec. 33:47-74. 1971.
36. Slade, P. Photochemical Degradation of Paraquat. Nature 207:515,
1965.
37. Plimmer, J. R., U. L. Klingebiel, and B. E. Hummer. Photo-oxidation
of DDT and DDE. Science. 167:67-69. 1970.
38. Crosby, D. G., A. S. Wong, J. R. Plimmer, and E. A. Woodson.
Photodecomposition of Chlorinated Dibenzo-p-dioxins. Science.
173:748-749. 1971.
36
-------
39. DDT: An Unrecognized Source of Polychlorinated Biphenyls.
Science. 180:578-579. 1973.
40. Sweeney, K. H., A. F. Graefe, R. L. Schendel, and R. D. Cardwell.
Development of Treatment Process for Chlorinated and Hydrocarbon
Pesticide Manufacturing and Processing Wastes. Unpublished
report Environmental Protection Agency, Athens, Georgia, Contract
No. 68-01-0083. July 1973.
41. Plimmer, S. R. Principles of Photodecomposition of Pesticides.
]_n_ Degradation of Synthetic Organic Molecules in the Biosphere.
National Academy of Sciences. Washington, D.C.
42. Cha, C. Y., and J. M. Smith. Photochemical Methods for Purifying
Water. Environmental Protection Agency, Cincinnati, Ohio.
Publication No. EPA-R2-72-104. November 1972.
43. Meiners, Alfred F. Light-Catalyzed Chlorine Oxidation for Treatment
of Wastewater. Environmental Protection Agency, Water Resources
Scientific Information Center, Washington, D.C. Publication
No. 17020. September 1970.
44. Sibert, M. E. Vapor Decomposition by Microwave Discharge.
Defensive Research Department Research Laboratories, Edgewood
Arsenal, Maryland. Publication No. AD IMSC/D243400. September
1971.
45. Witner, Fred E. Revising Waste Water by Desalination. Environ-
mental Science and Technology. 7:314-318. April 1973,
46. Hamoda, M. F., K. T. Brodersen, and S. Sourirajan. Organics
Removal by Low Pressure Reverse Osmosis. Journal Water Pollution
Control Federation. 45:2146-2154. October 1973.
47. Cruver, James E. Reverse Osmosis-Where It Stands Today. Water
and Sewage Works 120:74-78. October 1973.
37
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-670/2-74-088
3. RECIPIENT'S ACCESSION>NO.
4. TITLE AND SUBTITLE
PROMISING TECHNOLOGIES FOR TREATMENT OF
HAZARDOUS WASTES
5. REPORT DATE
November 1974; Issuing Date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Robert E. Landreth
Char!es J. Rogers
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORG \NIZATION NAME AND ADDRESS
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
10. PROGRAM ELEMENT NO.
1DB311; ROAP 07ADZ, Task 02
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Same as above
13. TYPE OF REPORT AND PERIOD COVERED
Final 7/1/73-7/1/74
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Numerous toxic and hazardous wastes are being generated and improperly treated/
disposed of by industrial sources. The wastes produced have varied toxicities
and possess characteristics which make them unique. This study was undertaken
to identify and recommend promising waste treatment technologies the use of which
would minimize the growing threat to public health and environmental quality
Literature searches, site visits, and personal communications with experts in the
field provided the basis for identifying needed treatment technologies.
The criteria used in the selection of promising techniques for development were
inadequacy of present technology and the economics, resource recovery, and
volume reduction of the new technology. Treatment processes that appear applicable
for processing both homogeneous and heterogeneous hazardous waste streams
include chemical, biological, and physical treatments.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
*Hazardous materials
*Waste treatment
*Waste disposal
*Sludge disposal
Toxicity
Pesticides
*Hazardous waste
Solid waste control
hazardous waste control
Physical treatment
Biological treatment
Chemical treatment
Heavy metals
13B
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
44
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
38
U.S. GOVERNMENT PRINTING OFFICE: 197A-657-587/5317 Region No. 5-II
------- |