x>EPA
United States
Environmental Protection
Agency
Robert S. Kerr Environmental Research
Laboratory
Ada OK 74820
EPA-600 2-79-052
February 1 979
Research and Development
Manual of Practice
The Disposal of
Combined
Municipal/lndustria
Wastewater Residues
(Metals)
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Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further deveJopment and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution-sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-79-052
February 1979
MANUAL OF PRACTICE: THE DISPOSAL OF COMBINED
MUNICIPAL/INDUSTRIAL WASTEWATER RESIDUES (Metals)
by
Hugh M. Jeffus
Source Management Branch
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
Project Officer
Leon H. Myers
Source Management Branch
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ADA, OKLAHOMA 74820
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DISCLAIMER
This report has been reviewed by the Robert S. Kerr Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publication.
Mention of trade names or commercial products does not constitute endorsement
or recommendation for use.
11
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FOREWORD
The Environmental Protection Agency was established to coordinate
administration of major Federal programs designed to protect the quality of
our environment.
An important part of the agency's effort involves the search for infor-
mation about environmental problems, management techniques and new technologies
through which optimum use of the nation's land and water resources can be
assured and the threat pollution poses to the welfare of the American people
can be minimized.
EPA's Office of Research and Development conducts this search through
a nationwide network of research facilities.
As one of these facilities, the Robert S. Kerr Environmental Research
Laboratory is responsible for the management of programs to: (a) investigate
the nature, transport, fate and management of pollutants in groundwater; (b)
develop and demonstrate methods for treating wastewaters with soil and other
natural systems; (c) develop and demonstrate pollution control technologies
for irrigation return flows; (d) develop and demonstrate pollution control
technologies for animal production wastes; (e) develop and demonstrate tech-
nologies to prevent, control or abate pollution from the petroleum refining
and petrochemical industries, and (f) develop and demonstrate technologies
to manage pollution resulting from combinations of industrial wastewaters or
industrial/municipal wastewaters.
This report contributes to the knowledge essential if the EPA is to meet
the requirements of environmental laws that it establish and enforce pollution
control standards which are reasonable, cost effective, and provide adequate
protection for the American public.
W. C. Galegar
Director
Robert S. Kerr Environmental
Research Laboratory
111
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ABSTRACT
The disposal of residues from waste treatment systems treating combined
municipal and industrial wastes, quite often, presents some unique problems.
The uniqueness derives from the nature or the levels of constituents contrib-
uted by industry when combined with municipal wastes. Some of these constit-
uents inhibit treatment processes and/or pose a potential threat to public
health if improperly handled.
On a broad scale, environmentally acceptable methods of disposing of
residues include incineration, landfilling, landspreading, and a combination
of incineration and landfilling. However, no one of these methods is accept-
able in all cases because of the diverse nature of the residues. Additionally,
with some constituents, none of these methods are free of environmental con-
cern.
This effort is concerned specifically with the disposal of residues from
combined treatment systems containing metals and with metal residues in
general.
This manual gives the processes and products where different metals are
used in order that potential sources of metals in combined wastewater resi-
dues may be identified. Potential problems in disposal of these residues are
identified. Most metals are toxic to plants or animals at some concentration
and, therefore, pose potential environmental or health problems.
Disposal practices, incineration, landspreading, landfilling, and encap-
sulation are discussed. Limiting concentrations of potential problem metals
are given for incineration and landspreading.
This report was submitted in fulfillment of IPA contract by
Dr. Hugh M. Jeffus, University of Arkansas, under the partial sponsorship
of the U.S. Environmental Protection Agency. This report covers a period
from August 15, 1977, through August 15, 1978, and work was completed as of
August 15, 1978.
IV
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CONTENTS
Foreword iii
Abstract iv
Tables vi
Acknowledgments vii
1. Introduction 1
2. Conclusions 3
3. Recommendations 4
4. Potential Sources and Problems of Metals in Residues . 5
Aluminum 5
Antimony 5
Arsenic 5
Barium 6
Beryllium 5
Boron 7
Cadmium 7
Chromium 8
Cobalt 9
Copper 9
Lead IQ
Manganese 10
Mercury u
Molybdenum n
Nickel 12
Selenium 12
Silver 15
Sodium 13
Strontium 13
Thallium 14
Tin '.'.'.'.'. 14
Titanium 14
Tungsten 14
Vanadium 15
Zinc 15
Other metals . 15
5. Disposal 19
Incinerators 19
Incineration. 20
Landspreading 22
Landfill. 24
Encapsulation 25
References ?,
Appendices
A. Industrial Waste Survey. 28
B. Metals from Point Source Category 29
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TABLES
Number Page
1 Generalized Metal Toxicity and Solubility Conditions. . 16
2 Melting and Boiling Points of Various Metals (°C) ... 20
3 Metal Concentration Limits in Sludges for Landspreading 23
B-l Metals in Settlement Agreement 29
B-2 Other Metals of Concern 30
VI
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ACKNOWLEDGMENTS
The author wishes to express his sincere appreciation to the following
for their valuable assistance, suggestions, and comments:
Office of Research and Development
Office of Energy, Minerals, and Industry
Mr. Robert Bastian, Municipal Construction Division
Mr. Eugene Grumpier, Hazardous Waste Management Division
Staff, Industrial Sources Section, Robert S. Kerr Environmental Research
Laboratory
VI1
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SECTION 1
INTRODUCTION
The removal of a contaminant from one medium--air, water, land—always
produces a contaminant in another medium, although in a more concentrated
form. This is a result of the principle that matter cannot be created or
destroyed, but can be changed in form and moved to a lower energy level.
The primary problem in wastewater treatment has traditionally been "what
to do with the residue." There is a current trend to dispose of this residue
on the land as a soil amendment. There is also a trend toward placing the
wastewater, either before or after solids separation, on the land. This is
not a new idea. In the "Report from the Poor Law Commissioners on an Inquiry
Into the Sanitary Conditions of the Labouring Population of Great Britain,"
1842, Sir Edwin Chadwick called for "The Rain to the River and the Sewage to
the Soil." Since this concept has been applied in many areas of the world for
centuries, this evidently was not a novel idea when Sir Edwin set it forth.
The municipal sludge of today, particularly from combined systems, is much
more complex than in Sir Edwin's day. In fact, many of the constituents of
modern combined sewage were used but rarely then. Thus, application today
must be made very carefully with consideration given to both short- and long-
term effects of the application.
Several recent publications have addressed the sources and effects of
heavy metals in sludges on crops (1, 2, 3, 4, 5). It is also interesting to
observe how many patents have been issued for recovery of heavy metals from
waste streams in the previous 5 years (6). Recovery and reclamation appear
absolutely necessary not only for environmental considerations, but for re-
source management. The United States consumption of the world production of
certain metals exceeds the following percentages: aluminum 46%, antimony 21%,
cadmium 34%, chromium 16%, cobalt 16%, copper 25%, and zinc 29% (7). There is
an insufficient quantity of several metals to raise world consumption to the
per capita level of consumption in the United States.
Heavy metals from combined industrial and municipal wastewater are con-
centrated in the sludge (8). Therefore, very careful monitoring of all
industrial waste streams and combined wastewater sludges must be followed.
Sludges applied to pasture and cropland probably have more utility as a
soil amendment than as a fertilizer. Currently, less than 0.3 percent of the
Nation's croplands receive sewage sludge, and even if the entire municipal
sludge production were to be applied at crop nitrogen requirement rates, less
than 1 percent of the agricultural land would be involved (3). It has been
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reported that widespread use of sludge as a fertilizer could potentially
satisfy only 2 percent of the current artificial nitrogen and phosphorous
fertilizer market (3).
Boron, copper, iron, manganese, molybdenum, and zinc are essential micro-
nutrients for plants (1). However, in high concentrations most metals in-
cluding boron, copper, manganese, and zinc are toxic to plants.
Copper, chromium, iron, manganese, molybdenum, selenium, and zinc are
essential micronutrients for man and animals (4). However, as with plants,
high concentrations of some of these metals, molybdenum and selenium, are
toxic to man and animals. Cadmium, lead, and mercury are cumulative poisons
in man and animals. Most heavy metals are toxic to some degree to both plants
and animals.
Another factor which complicates land application of sludge from combined
industrial and municipal waste treatment plants is metal mixtures. For example,
proper management of soil organic matter and pH will render some metals rela-
tively unavailable to crops and forage, but will render other metals more
available. Most metals are relatively insoluble under alkaline soil conditions.
Antimony, selenium, and molybdenum are more soluble under alkaline soil con-
ditions.
In the pages that follow, the possible sources of metals which may be
found in a residue are stated. This may be of help to those upon whom the
responsibility falls for monitoring and reducing the discharge of metals to
a waste treatment plant so that the sludge from the wastewater treatment plant
may be environmentally acceptable.
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SECTION 2
CONCLUSIONS
Some metal residues from combined waste treatment systems pose potential
threats to health and the environment. In general, the potential problems
most commonly involve cadmium, copper, lead, mercury, molybdenum, and nickel.
Arsenic, barium, cadmium, selenium, and mercury have low boiling tempera-
tures and, therefore, the potential to cause emission problems from sludge
incinerators.
Antimony, molybdenum, and selenium are most soluble under alkaline condi-
tions and could, therefore, pose a problem when mixed with other metals in an
environment designed to keep other metals immobile, such as a high pH soil
system.
Adverse health effects could occur from landfilling high concentrations
of arsenic, barium, beryllium, cadmium, chromium, cobalt, lead, mercury,
selenium, and vanadium.
Specific information about a landfill site must be obtained before sludge
metals concentration limits can be set for that site.
Analyses of soil metal content and sludge metal content must be made be-
fore landspreading of sludge is started.
Metal analyses of sludges do not normally reveal the form or compound the
metal is in, and almost any metal can exist in some form that is hazardous.
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SECTION 3
RECOMMENDATIONS
The following recommendations are offered:
1. The soil chemistry of cadmium and cobalt should be studied in detail,
2. The antimony content of sludges from combined waste treatment systems
should be monitored.
3. The toxicity of antimony to plants and animals should be investigated
more fully.
4. Stack emission standards for the easily volatilized toxic metals should
be set similar to the standard for mercury.
5. City officials in small municipalities (less than 50,000 population) should
appoint committees to assist city officials in resolving the problem of
residues. The committee might be composed of representatives from in-
dustry, utilities, health services, academia, etc., and might involve the
disciplines of chemistry, geology, engineering, soil science, and plant
science. This committee should contact the appropriate state and federal
agencies for help in order to give city officials some background and
assistance in the use of their manual of practice as follows:
City
Official
Appointed
Committee
Identify^
Sources
Volumes
Concentrations
etc.
Recommend
Pretreatment
Method of disposal
Siting
etc.
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SECTION 4
POTENTIAL SOURCES AND PROBLEMS OF METALS IN RESIDUES
ALUMINUM
Aluminum metal is used in aircraft, utensils, apparatus, electrical con-
ductors, dental alloys, photography, explosives, fireworks, paints, and the
manufacture of steels. Compounds of aluminum are used in medical supplies,
fur processing, baking powder, purifying water, dyeing and printing fabrics,
artificial gems, paper, vegetable glue, marble and porcelain cements, fire-
proofing and waterproofing fabrics, glass manufacture, electrolytic copper-
plating, preserving wood, coating ceramics, organic synthesis, disinfectants,
antiperspirants, detergents and soaps, petroleum cracking, lubricants, and in
the manufacture of lacquers, filaments, semiconductors, resistors, and rubber.
The primary source of aluminum in combined treatment residues is from
water treatment plant discharges where aluminum sulfate is used as a coagu-
lant. The second most prominent use of aluminum sulfate is in the papermaking
industry where the product is used for the sizing of paper.
Very little aluminum is discharged to municipal sewers from the manufac-
ture of aluminum sulfate or aluminum chloride (5).
Aluminum toxicity to plants is common where it exists in soils with pH
values below 5.0. However, in well-aerated soils with pH values above 5.5,
aluminum will not be a major factor in land disposal of aluminum-containing
residues (4).
ANTIMONY
Antimony is used in alloys such as babbitt, hard lead, white metal, auto-
mobile body solders, bullets, fireworks, and metal coatings. Compounds of
antimony are used as catalysts, as pigments, in vulcanizing and coloring rub-
ber, and in the manufacture of matches, fireworks, medical and veterinary
supplies, glass, pottery, and porcelain. It is also used in dyeing and print-
ing fabrics, and in the flameproofing of canvas.
Antimony is not known to be essential to the growth of plants but has
been reported to be moderately toxic (4). Leaves of plants tend to contain
more antimony than do stems (4). Although antimony could be a potential
hazard to plants and animals if applied in large amounts, no evidence of
hazard is currently available (4). Antimony is most soluble under alkaline
soil conditions.
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There is not much information as to the antimony content of sludges from
combined waste treatment. Investigation of the antimony content of suspected
sludges should be made.
ARSENIC
Arsenic originates primarily from the smelting of other nonferrous metals.
Arsenic was used in pesticides before 1967 and is used in wood preservatives,
as pigments in paints, in fireworks, in the textile and tanning industries,
and in making certain bronzes and alloys. Compounds of arsenic are also used
in the manufacture of glass, enamels, ceramics, oil cloth, linoleum, and elec-
trical semiconductors, and photoconductors. However, the primary source may
be from the food processing industry because arsenic tends to accumulate in
the roots and not in the edible portions of most plants (4).
Although arsenic is extremely toxic to man and animals, it is not thought
to pose a serious problem in the disposal of residue by landspreading because
of the low levels commonly found in most sludges (4). Rates of applications
in excess of 90 kilograms (kg) of arsenic per hectare must be applied before
toxicity to plants is observed (4). Arsenic tends to revert to the chemical
form of arsenate, which is strongly held by the clay fraction in most soils (4).
Arsenic in landfills is a different matter. Serious damage has occured
through groundwater contamination from arsenic burial (9).
BARIUM
Barium is used in certain electronic devices and in spark plugs. Com-
pounds of barium are used in printing and dyeing fabrics, tanning and finish-
ing leather, electroplating, synthetic rubber vulcanization, marble substitutes,
lubricants, pesticides, rat poisons, corrosion inhibitors, embalming, and
pigments. Barium compounds are also used in the manufacture of explosives,
paper, glass, paints, enamels, matches, green signal lights, and case hardened
steels (1). Barium is also used in diesel fuels as a smoke suppressant, and
in some veterinary medical supplies.
All water and acid soluble compounds of barium are poisonous.
Barium in high concentrations can cause yield reductions of crops. Barium
concentrations in soils normally range from 200 to 6000 kg per hectare
(1). Barium is found in most surface waters. It appears remote that barium
would impinge significantly upon sludge disposal from combined waste treatment
systems, unless sludge concentrations are in the range of thousands of micro-
grams per gram GI g/g) .
BERYLLIUM
Beryllium is a source of neutrons when bombarded with alpha particles.
It is a neutron reflector and neutron moderator in nuclear reactors. Beryll-
ium oxide is used in rocket propellants. Beryllium has been used in radio
tubes, television tubes, and fluorescent tubes.
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Beryllium production in the United States is less than 500 tons per year
(6). Beryllium is a very expensive metal, and much effort is put forth to
recover this metal from smelting operations. It is usually recovered from
spent pickle acids deriving from the pickling baths for stainless steel and
other alloys in a process for the recovery of copper (6). Beryllium and
beryllium salts are toxic to man in extremely low concentrations but should
present no problems in combined waste residue disposal because there is limited
production and use and efforts are exerted for recovery from waste streams.
BORON
The principal source of boron is from the household use of boron-contain-
ing soaps, detergents, and cleaners. Boron is also used in the manufacture
of glazes, cements, crockery, porcelain, enamels, glasses, alloys, semicon-
ductors, lubricants, and hardened steels (1). Boron compounds are used in
fertilizers, rubber vulcanizers, anesthetics, in fireproofing and weather-
proofing fabrics and wood, in the leather and tanning industry, in printing
and dyeing, paints, photography, and solder (1).
Boron is an essential micronutrient element for plants and is found in
plants and animals. At relatively low levels, boron is toxic to plants and
animals. The toxicity level for plants occur at levels greater than 75 ng/g
in the soil, and the normal concentration of boron in plants is between 30 and
75 vig/g (1). Therefore, it is unlikely that boron content of most sludges
will be a controlling factor in their disposal because of the limited number
of high boron content sludges.
CADMIUM
Cadmium is used in electroplating, pigments and chemicals, and alloys.
Parts of household appliances (refrigerators, washing machines, etc.), auto-
mobiles, airplanes, agricultural implements, and industrial machinery are
commonly cadmium coated (1). Additionally, hand tools (pliers, wrenches,
screw drivers) and fasteners of all kinds are often cadmium coated (1). Com-
pounds of cadmium are used in the plastic industry, in photography, lithog-
raphy, process engraving, rubber curing, medical and dental supplies, and
as fungicides. Alloys of cadmium are used in the production bearings for
internal combustion engines and aircraft, for solder, and bronzing (1).
Cadmium is also used in the production of automobile radiators, batteries, the
manufacture of super-phosphate fertilizers, and luminescent dials. Approxi-
mately 60 percent of the use of cadmium is in the electroplating industry.
Major sources of environmental release of cadmium are metal plating, the
manufacture and use of super-phosphate fertilizers, and the vulcanization of
rubber. Cadmium is taken up by plants through the roots and leaves and may
be quickly translocated to the plant vegetative parts. There is apparently
no general rule that may be applied as to the content that will appear in the
grain of edible plants. The percentage content of grain to foliar parts of
cadmium usually varies from 3 to 15 for corn, but may be from 30 to 100 for
soybeans, wheat, oats, and sorghum (4).
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Cadmium is toxic to plants and is a cumulative poison to man and animals.
Therefore, there is much concern at present about cadmium content of sludges.
Pretreatment ordinances can reduce the cadmium content of sludges as well
as other metals of concern (4). However, studies have shown that cadmium is
concentrated in biological solids (8). The weight ratio of cadmium in the
solids to cadmium in the influent water was 4100 when the influent water con-
centration was 1 milligram per liter (mg/1).
Additional investigation needs to be performed to learn what is not known
about soil chemistry and the interactions of cadmium. The task seems quite
formidable. It appears that cadmium is influenced by soil organic matter,
clay content and type, hydrous oxide content, soil pH, and redox potential (1).
In addition, some metals are antagonistic and some are synergistic to the plant
uptake of cadmium.
In view of these things, it would seem that something else could be sub-
stituted for the primary use of cadmium (electroplating) that would be more
environmentally acceptable. For example, a copper or zinc coated screwdriver
would probably function as well as the cadmium coated product, etc.
CHROMIUM
Chromium is used in chrome steels and alloys to increase the resistance
and durability of metals. The use of chromium in the electroplating industry
is widespread. Chromium is used in making refractory brick to line metallurgi-
cal furnaces (1). Compounds of chromium are used in dyeing and tanning, in
manufacturing inks, varnishes, glazes of porcelain, and as abrasives. Chro-
mates are used as corrosion inhibitors and rust inhibitors in cooling towers,
air conditioners, boilers, and some pipelines. Chromates are also used in
primer paints and dips for metals, in paper matches, dry-cell batteries, and
some fireworks. Chromium compounds are used as topical antiseptics and astrin-
gents, defoliants, and in photographic emulsions (1).
Little soluble chromium is found in soils. Hexavalent chromium applied
to soil is soon converted to trivalent chromium and then to a low solubility
compound. There is some evidence that chromium is required by humans and
animals in minute amounts, and diets are deficient in chromium (4). Excess
chromium, in minute amounts, is eliminated. However, chromium and its com-
pounds are extremely toxic to man, especially from ingestion, and with some
compounds from dermal exposure. Trivalent chromium is the only form available
to plants, and it can be adsorbed through leaves and roots.
Hexavalent chromium can seriously interfere with biological waste treat-
ment at high levels. Trivalent chromium is less inhibitory than hexavalent
chromium.
High concentrations of chromium in soils appear to be slightly toxic to
plants and reduce yields (1). Chromium is not likely to be a limiting factor
in land application of sewage sludge (4). However, care must be taken that
water supplies are not contaminated. The allowable chromium concentration in
drinking water is very low. Pretreatment of chromium-bearing streams at the
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source must be practiced.
COBALT
Cobalt is used in the production of high-grade steels and alloys. Cutting
and wear-resistant materials are commonly produced from steels and alloys
incorporating cobalt (1). Some cobalt compounds are used as a drier in paints,
varnishes, enamels and inks, as a pigment, and as a glass decolorizer (1).
Cobalt compounds are also used in medical and veterinary supplies, and in
radiotherapy.
Cobalt is found in most soils and most sludges. Very little is known
about the chemistry of these elements in natural soils. However, it does not
appear that cobalt will be a major factor in disposal of residues, from most
combined waste treatment systems due to the low concentrations found in most
sludges. Cobalt content of sludges should be monitored if cobalt is used
locally.
COPPER
Copper is used in the production of wire, brass, piping, electrical
apparatus, boilers, cooking utensils, automobile radiators, insecticides,
fungicides, and fertilizers. Copper is alloyed with tin, lead, zinc, aluminum,
nickel, and manganese (1). Compounds of copper are used medical and veteri-
nary supplies, pyrotechnics, paints, pigments, catalyst, manufacturing rayon,
and printing and dyeing fabrics.
Copper is found in most soils at a concentration normally ranging from
10 to 80 parts per million (ppm) (4). Copper is an essential micronutrient
for plants, but copper toxicity can occur at high concentrations. The copper
accumulates in the roots with very little being translocated to the foliage.
Copper appears to be about twice as toxic as zinc to plants.
Copper is toxic to animals in high concentrations, especially if the
molybdenum intake is very low (4). The copper concentrates in animal livers
under this circumstance and can be mitigated by controlling the molybdenum in
the diet, especially for ruminant animals. Sheep are most susceptable to
copper toxicity, followed by cattle, swine, and poultry, in that order (4).
Swine crave copper, and swine and poultry are fed beneficial amounts of cop-
per. The copper seems to be a substitute for antibiotics. The concentrations
fed to swine in their diet have been as high as 250 ppm; however, lower con-
centrations are now fed. The copper accumulates in the swine liver but
causes no apparent harm to the swine if the diet also contains adequate amounts
of zinc and iron (4).
Copper is a problem in waste treatment where concentrations of 100 mg/1
can "poison" anaerobic digesters. This is about 1/5 of the concentration of
chromium or nickel required to cause toxicity in anaerobic digesters.
The concern over copper is that it may build up in the soil over a period
of years and produce toxicity to plants.
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There appears little reason not to control high concentrations at the
source. There are numerous recovery schemes for reclaiming copper (6). There
is little waste from the production of copper sulfate. None of the major United
States producers of copper sulfate discharge to a municipal sewer system (5).
LEAD
The two principal uses of lead are in the production of storage batteries
and gasoline additives (1). Lead is also used in alloys, ammunition, construc-
tion, in pigments, as a caulking compound in plumbing, in solder, in exterior
paints, and in the production of insecticides. Compounds of lead are used in
matches, explosives, printing and dyeing fabrics, organic synthesis, photog-
raphy, and veterinary supplies.
Lead is very toxic to animals. Doses are cumulative. Very small amounts
of lead are adsorbed through plant leaves; the primary entry of lead to plants
is through the roots. If the pH of the soil is above 5.5 and there is adequate
labile phosphorous in the soil, there will be very little translocation by
lead from roots to plant foliage and seeds (4). It appears that the primary
entry of lead into the animal food chain is from animals grazing on forage
that contains residues from exhaust gas sources such as automobile exhausts
and blast furnace emissions.
If lead is adequately controlled at the source, it is unlikely that lead
will control sludge application to land surfaces; however, it must be rigorously
monitored as some sludges have very high lead contents (4). High lead concen-
trations in sludge will inhibit sludge digestion.
MANGANESE
The major use of manganese is in the iron and steel industry. Manganese
is also used in alkaline batteries, glass, paints, and as driers for paints
and varnishes. Other uses of manganese are in fertilizers, disinfectants, as
an antiknock compound for internal combustion engines, as a drier for varnishes
and oils, and in dye manufacturing.
Manganese is an essential micronutrient for plants and animals. It may
enter plants through roots and leaves. High levels of manganese in the soil
may cause toxic conditions in plants under reducing conditions. However, if
the pH of the soil is maintained above 5.5, the manganese exists as the rela-
tively insoluble oxides and hydroxides and plant uptake is restricted.
Manganese content of potable waters is restricted due to the taste im-
parted to certain beverages and the "black water" problems that arise from
the domestic use of manganese-bearing waters.
Manganese should pose relatively little hazard in sludge disposal; how-
ever, care must be exercised to prevent contamination of surface and ground-
water supplies with manganese where it would create the aforementioned
problems.
10
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MERCURY
Mercury is used for many purposes. The largest uses are in the electro-
lytic production of chlorine and caustic soda and in the electrical and elec-
tronics industry. Mercury is also used in paints, industrial and control
instruments, dental preparation, as catalysts, in agriculture and in general
laboratory instruments and experiments. Smaller users of mercury are the
Pharmaceuticals-cosmetics industry, pulp and paper industry, the production
of floor waxes, furniture polishes, fabric softeners, fireworks, and laundry
preparations. Mercury is used in neon, fluorescent, and mercury-arc lights,
in measuring instruments such as thermometers, barometers, manometers, hydro-
meters, etc., and in batteries, rectifiers, switches, and oscillators. It is
also used in the plastics industry, especially in the production of vinyl
chloride and urethane. Low concentrations of mercury may appear in waste-
waters from mercury contamination of commercial bleach.
Mercury is present in most soils as a result of the weathering of cinna-
bar. Mercury is taken up by plants through the roots or leaves and is readily
translocated throughout the plant. A typical soil might have a natural
mercury content of 0.01 to 0.5 ppm (4). Mercury and soil solid surfaces have
affinity for each other, and mercury applied to soil surfaces normally is not
a threat to groundwater. Most natural waters have concentrations of mercury
less than .001 microgram/milliliter (yg/ml) (1).
Mercury ingested in food by animals and man tends to accumulate. It is
excreted at a much slower rate than it is ingested. Mercury is toxic to man
and animals, and has been reported to be toxic to plants. However, most
municipal sludges do not contain sufficient mercury to create a major problem
when sludge is applied to land. In combined systems mercury must be monitored,
and high mercury sources must be pretreated at the source. Many relatively
new recovery processes have been patented for recovery of mercury (6).
Mercury is concentrated many times in the sludge from activated sludge systems
relative to the influent stream (8).
MOLYBDENUM
The largest use of molybdenum is in the production of molybdenum steels
and alloys (1). Other uses are in pigments, lamp filaments, electrical con-
tacts, spark plugs, fertilizers, dyes, and as catalysts. Molybdenum disulfide
is used as a lubricant.
Molybdenum enters plants through roots and leaves. It is an essential
micronutrient for plants. The maximum sorption of molybdenum in soils occurs
at pH 4.2, and the availability of molybdenum to plants increases as the soil
pH increases. This is the reverse behavior to that observed with copper,
nickel, and zinc (4). This will create problems with landspread sludge that
contain mixtures of metals with molybdenum.
Animals are susceptible to a toxicity produced by too much molybdenum
called molybdenosis. The amount of molybdenum necessary to produce the
condition varies with animal species and age (4). Cattle and sheep are more
susceptible than horses and pigs. Forages containing more than 10 to 20 ppm
11
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may produce molybdenosis in ruminants (4). The condition is affected by other
metals intake, such as copper, zinc, and iron,, and by the sulfate intake.
Molybdenum in excessive concentration produces a copper and phosphorous defi-
ciency in the animals.
It is doubtful that molybdenum in sludge would present a serious hazard
to the health of grazing animals except where forages from sites treated with
sludges high in molybdenum form a major part of the animal diet (4). However,
from the foregoing it is apparent that molybdenum could be a problem in com-
bined waste treatment sludge that is to be disposed of on land. Molybdenum
is one of the elements that must be controlled at the source to prevent ex-
cessive concentrations in the sludge from combined municipal and industrial
waste treatment plants.
NICKEL
Nickel is used in the production of stainless steels, in nickel alloys,
in electroplating, in batteries and in magnets, electrodes, electrical con-
tacts, spark plugs, machinery parts, and as a catalyst. Compounds of nickel
are used in paints, lacquers, cellulose compounds, and cosmetics (1).
Nickel is commonly found in soils, plants, and waters. The common con-
centration range in soils is from 10 to 100 ppm, with higher concentrations
found in weathered serpentine soils.
Nickel has been claimed to be an essential micronutrient for some plants,
but generally is regarded as having no essential known function. Nickel
becomes toxic to plants when the nickel concentration reaches 50 ppm (4).
The toxicity has been observed on acid soils. Most nickel is eliminated by
animals and should provide no problems in diets; however, most metals have
some highly toxic compound such as nickel carbonyl.
Nickel is toxic to anaerobic digesters at a concentration of 500 mg/1.
For this reason, and those stated above, nickel must be controlled at the
source.
SELENIUM
Most of the selenium consumed in the United States is used in the glass
and electronics industry (1). Selenium is used in rectifiers and photoelec-
tric cells. The rectifiers are used in electroplating, welding, battery
chargers, magnetic coils, arc lamps, and voltage regulators. Photoelectric
cells are used in light exposure meters, electric eyes, detectors, color-
imeters, and pyrometers. Selenium is used to produce pigments to color
materials such as plastics, paints, enamels, inks, and rubber. It is also
used in stainless steel and photocopiers, and compounds of selenium are used
in Pharmaceuticals, deodorants, pesticides, plastics, inks, oils, fireproofing
agents, glue, insect repellants, lubricants, and paint removers. In addition,
selenium compounds are used in the production of rubber and as catalysts in
the production of soaps, waxes, and edible fats.
Little evidence exists to suggest that selenium is an essential element
12
-------
for plants, but it is definitely required by certain animals (4). It is an
essential element in trace quantities for vitamin E production, and large
quantities can be toxic to animals. Selenium and its compounds can be inhaled,
ingested, and adsorbed through the skin to cause poisoning in man. The symptoms
are much the same as arsenic poisoning. Selenium is taken up by plants, which
serves as a transfer mechanism from soil to animals. At levels of 0.05 ppm in
the diet degeneration of muscle tissue results; when the diet contains more
than 4 ppm, selenium toxicity may occur (4). Selenium, like antimony and
molybdenum, is most soluble under alkaline conditions. This complicates the
management of sludges on land where these metals are mixed with other metals
that are least soluble under alkaline conditons.
There are processes for recovery of selenium (6). Although selenium is
not likely to be a limiting factor in the disposal of most sludges, there
seems little reason for selenium wastes not to be pretreated at the source to
insure that selenium is not a problem.
SILVER
Most silver that enters waste treatment systems probably comes from
source silver used in photographic materials. Silver is also used in elec-
tronics manufacture, jewelry, electroplated ware, storage batteries, the
production of mirrors, dental and medical supplies, gas masks, explosives,
and some bearings and solders. Silver is also used as a catalyst in some
industrial operations. There are no known discharges of silver from the
manufacture of silver nitrate (5).
It is unlikely that silver will be a problem in the disposal of most
residues from combined municipal and industrial wastewater treatment.
SODIUM
Sodium, as salt, is an essential part of the diet of man and animals.
It is found in municipal waste primarily due to the excretions of man and
as waste from food preparation. Sodium compounds have many uses, and the
compounds of sodium are many. It is used in baking powders, medical supplies,
soaps, paper sizing, water softeners, printing fabrics, fire extinguishers,
cleaning compounds, food preservatives, disinfectants, bleaches, and in
manufacturing glazes and enamels. Sodium is also used in sodium arc lamps,
in photography, in fumigants, in oxidants, in organic synthesis, and for
other purposes. It is toxic to plants in high concentrations. However,
the effect of concern where sludge is to be applied to land, is the drastic
effect salt has on the soil. When the sodium concentration is high in ratio
to the calcium and magnesium, the soil becomes plastic and sticky. This
destroys the permeability of the soil and ruins its fertility.
Sodium is not likely to be a major problem in sludge disposal from the
majority of systems. It is toxic to anaerobic digesters at high concentrations.
STRONTIUM
Strontium is used in the production of pyrotechnics to impart a crimson
13
-------
color. Strontium compounds are used in electronics, glass, grease, paints,
plastics, and pharmaceutical supplies. The radioactive isotope, strontium-90,
is often a waste product of fissionable material. Strontium-90 could be a
major problem if it were a constituent of the residue because plant and animal
systems do not discriminate between calcium and strontium. Strontium is not
likely to be a problem in sludge disposal because most sludges have low stron-
tium contents. Some combined sludges do have relatively high strontium levels,
however.
THALLIUM
Thallium is used in electronics, alloys, glass, and agriculture, and as
a rat poison. Thallium compounds are used in the manufacture of artificial
gems, ant bait, and green fire for signaling at sea.
There is only one United States producer of thallium. Therefore, there
is unlikely to be a problem with thallium in combined waste treatment residue
due to the limited production and use of thallium.
TIN
The primary use of tin is in the production of tin cans. Tin is afso
used in the production of many alloys, babbitt, brass, bronze, and galvaniz-
ing materials. It is used in roofing materials, pipe and tubing, solder and
in collapsible tubes, and foil (1). Compounds of tin are used in glass manu-
facture, dyeing and printing fabrics, toothpaste, fingernail polish, and in
decorating porcelain and china. Tin is thought to be quite inert in soils
and is, therefore, unlikely to be a major problem in waste disposal.
TITANIUM
Titanium is used in the production of certain steels, in electrodes,
welding rod coatings, shoe whiteners, paper coating, acetate rayon, water
paints, exterior paints, inks, plastics, and as pigments. Compounds of tita-
nium are used in dyeing, stain removers, reducing agents, and medical supplies.
Titanium is present in any soil that contains layer lattice clay.
Titanium has no recognized essential biological function. It can enter plants
through roots or leaves. Titanium can be toxic to animals if ingested in
large quantities. The toxicity symptoms for humans resemble Parkinson's
Disease. The primary source of titanium in the human diet is black pepper.
Titanium is unlikely to be a major factor in combined waste sludge dis-
posal except from steel mills or where titanium recovery is a segment of the
secondary nonferrous metal industry.
TUNGSTEN
Tungsten is used in the production of steels, cutting tools, and in the
electrical industry as filaments and conductors. Little is known of the
tungsten content of soils and sludges. However, it is unlikely that tungsten
will be a problem in the disposal of combined waste treatment residue because
14
-------
tungsten is not used by many industries.
VANADIUM
The major uses of vanadium are in vanadium steels and nonferrous alloys
(1). Vanadium compounds are used as a catalyst in several processes, as
driers in paints and varnishes, in photography, in drying and printing fabrics,
and in the production of colored glass and glasses (1). The most likely
source of vanadium in waste streams is from crude oil and coal.
Vanadium has no recognized function in biological systems. Plants adsorb
vanadium through roots or leaves. Vanadium is suspected to be toxic to ani-
mals. However, in the absence of steel mills or coal conversion facilities,
vanadium is unlikely to be a limiting factor in combined waste treatment
sludge disposal.
ZINC
Zinc is used extensively as a protective coating of metals to prevent
corrosion and in alloys such as brass and bronze (1). Galvanized pipes are
commonly used in domestic water systems, and zinc solubilized by corrosion
is thought to contribute substantially to the zinc concentrations in waste-
waters (1).
Zinc and its compounds are constituents of many household items including
utensils, cosmetic and pharmaceutical powders and ointments, antiseptics,
astringents, insecticides, fungicides, glues, matches, inks, porcelain, paints,
varnishes, oil colors, linoleum, and rubber. Zinp and zinc compounds are
used in dyes, phosphors for fluorescent lights, and electrical apparatus.
Zinc is also used in the manufacture of glass, castings, printing plates,
building materials, railroad car linings, automobile tires, dry-cell batteries,
television screens, reducing agents, and parchment paper. Zinc compounds are
used in hardeners of cement, weighting textiles, agricultural fertilizers,
wood preservatives, and in paper bleaching.
Zinc is an essential nutritional trace element, and some diets may be
deficient in zinc. It can cause plant toxicity and animal toxicity at high
concentrations. Zinc has been used as a standard for plant toxicity. Zinc
is most soluble in soils under acidic conditions; and, when zinc toxicity does
occur, the plant concentrations will be several hundred ppm (4). Several
hundred ppm of zinc in the diet of animals causes reduced weight gain and
lower feed efficiency.
Zinc is not likely to be a major factor in the disposal of the residue
from combined waste treatment unless the zinc concentration is in the order
of thousands of mg/1.
Table 1 gives toxicity and solubility conditions of some common metals.
OTHER METALS
The following metals are given limited coverage herein because they are
15
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TABLE 1. GENERALIZED METAL TOXICITY AND SOLUBILITY CONDITIONS
Metal
Aluminum (Al)
Antimony (Sb)
Arsenic (As)
Barium (Ba)
Beryllium (Be)
Boron (B)
Cadmium (Cd)
Chromium (Cr)
Cobalt (Co)
Copper (Cu)
Lead (Pb)
Manganese (Mn)
Mercury (Hg)
Molybdenum (Mb)
Toxic to
man or
i'hytotoxin animals
X pH <5.0
X
X X
X X
X
X X
X X
X slight X
X X
X
X pH <5.5
X slight X
X
Highest
solubi.1 i.ty
conditions
Acid
Alkaline
Acid
Acid
Acid
Acid
Acid
Acid
Acid
Alkaline
Toxic conditions
High concentration for plants
Low concentration for animals
High concentration
Low concentration
Medium concentration
Cumulative
Cumulative
Cumulative
Low concentration
(continued)
-------
TABLE 1. (continued)
Metal
Nickel
(Ni)
Selenium (Se)
-------
not produced in large quantities or have very limited usage and, therefore,
will not occur in significant quantities in most sludges.
Bismuth is used in pharmaceuticals, cosmetics, and in the manufacture of
other chemicals as a catalyst.
Cerium is used in manufacturing spark metals for lighters, as a catalyst,
and in the manufacture of glass.
Cesium is used in pharmaceuticals and in electronics manufacture.
Columbium is used to produce high-strength alloys, stainless steel, and
super alloys.
Gadolinium is used in control rods in nuclear reactors.
Gallium is used in the electronics industry primarily in light-emitting
diodes for watches, calculators, and fluorescent light for xerography.
Germanium is used in electronics and dentistry.
Hafnium is used as a neutron absorber.
Indium is used in alloys for bearings, for dentistry, and for the manu-
facture of glass and semiconductors.
Lanthanum is used in glass to improve optical properties.
Lithium is used in chemical manufacture, ceramics, greases, alloys, swim-
ming pool sanitation, and organic synthesis.
Platinum group metals (platinum, palladium, iridium, osmium, rhodium, and
ruthenium) are used as catalysts in the petroleum refining industry and in
automobile exhaust emission control systems.
Radium is used in medical treatment.
Rubidium is used in research.
Scandium is used in high intensity mercury lamps.
Tantalum is used primarily for capacitors in the electronics industry and
as pressure vessels for the manufacture of chlorine.
Tellurium is alloyed with steel and copper and is used in the manufacture
of rubber, electronics, and chemicals.
Yttrium is used as a phosphor in color television receivers and in lasers.
Zirconium is used in flash bulbs, explosives, in vacuum tubes, and in
metallurgy.
18
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SECTION 5
DISPOSAL
The ideal disposal alternative is to have no disposal but to practice
recovery and recycle. Industrial pretreatment must be practiced, and recovery
is only one step removed from pretreatment and, in some cases, may be a part
of pretreatment. Pretreatment complies with the spirit of the Resource Con-
servation and Recovery Act of 1976 (Public Law 94-580) in two ways. First, it
conserves our natural resources. Second, it reduces the amount of pollutants
discharged to the environment. The depletion of our metal resources has
previously been alluded to. However, the most compelling reason to pretreat
industrial wastes is to prevent the dispersal of the pollutants into the en-
vironment. Pretreatment at the source catches the wastes at the most advan-
tageous point insofar as the ability to treat or recover is concerned. At
that point, the waste is in the most concentrated form, has not been diluted
or mixed with other wastes, and is therefore more easily handled.
Disposal alternatives which may be considered are incineration, land-
spreading, landfill, and encapsulation. Incineration for heat recovery and
landspreading for nutrient usage are disposal processes that conform to
resource conservation and recovery. Encapsulation might be used as a method
of storage for some constituents that are not economically recoverable now,
but may be more valuable at some future time. It is difficult to see how
landfilling would be either conservation or recovery. In any situation,
there may be factors that will dominate and override conservation and recovery
considerations. Incineration, landspreading, and landfill are not acceptable
with all materials, but one of these alternatives will usually apply. The
limitations and possible pitfalls of these alternatives are hereinafter dis-
cussed.
INCINERATORS
The two most common types of sewage sludge incinerators are the multiple
hearth and the fluidized bed. The multiple hearth incinerator is used in
more disposal installations than any other type of incinerator. The cyclone
furnace is another type of incinerator that is designed for sludge disposal in
smaller installations.
Other sludge reduction processes are wet air oxidation, pyrolysis, and
sludge drying units.
19
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INCINERATION
Sewage sludge incinerators normally operate at a temperature in the range
of 900 to 1100 C. The melting and boiling temperatures of the metals discussed
in the previous section are given in Table 2. From this table, it is obvious
that many of the metals of concern are likely to be volatilized at incinerator
temperatures.
TABLE 2. MELTING AND BOILING POINTS
OF VARIOUS METALS (°C)
Metal
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Cobalt
Copper
Lead
Manganese
Mercury
Melting
temperature
660
631
*
850
= 1300
2150
321
1900
1493
1083
327.4
1247
-39
Boiling
temperature
1800
1380
*
1440
2970
767
2480
3550
2595
1740
=2032
356.9
Metal
Molybdenum
Nickel
Selenium
Silver
Sodium
Strontium
Thallium
Tin
Titanium
Tungs ten
Vanadium
Zinc
Melting
temperature
2622
1455
+ 144
960.5
97.7
757
303.5
231.9
= 1725
3410
1717
419.4
Boiling
temperature
=4510
3075
+685
=2000
883
1366
1457
2260
5900
3000
907
* Sublimes at 615°C without melting
+ Red form
= Approximately
In addition, the testing procedures for metal content do not determine
the nature or type of compound in which the metal exists. Since different
compounds of a particular metal have different boiling temperatures, some
metals may vent from the incinerator at lower temperatures than those given
for the pure metal in Table 2. The exact nature of the metal could only be
20
-------
determined by going to the source of the metal discharge and ascertaining the
exact compound containing the metal.
Therefore, if significant concentrations of arsenic, barium, cadmium,
lead, mercury, selenium, or thallium exist in the waste treatment residue, it
should not be incinerated. Emission standards have been established for
mercury from sludge incineration at 3200 grams per day (10). This limit is
based upon 1 microgram of mercury per cubic meter of emitted gas. Similar
standards should be promulgated for the other toxic, easily volatized metals.
A recent study has shown that the major portion of the metals in anaerobic
digesters is within the cell mass (11). Thus, the metals will be released in
the incineration process.
The ash remaining after incineration will have a higher concentration of
the more heat-stable metals than the sludge that was incinerated. Assuming
a normal range of 65 to 75 percent volatile solids in the sludge, the ash will
contain three to four times the concentration of these heat-stable metals than
the sludge. Care must be exercised in the disposal of this ash. The ash may
be deposited in a secure landfill; however, if the more toxic metals exist,
the ash should be encapsulated. The metals in the ash will probably be in
the form of oxides and hydroxides. Under the reducing conditions existing in
a landfill, the metals can be solubilized.
The concentration of material allowable in the dry sludge may be computed
as follows:
Assume 23.75 pounds of air per pound of solids is required
for combustion (12) (50% excess air). The volume of required air
is 25.75 = 335 cubic feet per pound.
.0708 335
If the ash remaining is 14% of the dry solids, then —-^- = 390
cubic feet of air per pound of volatile solids. This value is con-
sistent with values from operating incinerators.
390 x .0283 = 11 cubic meters Of air per pound of volatile
solids which is 41 micrograms of combustion products per cubic
meter of air.
Therefore, 41 x 10 x a = gas stream concentrations where
a_ is the allowable concentration of metals in the sludge in
parts per million.
From previous data (13) it appears that it is difficult to predict how much
chromium, copper, cobalt, etc. will appear in the exhaust gas stream. How-
ever, it has been pointed out that some metals will appear in the gas stream
(13). The following limiting concentrations of selected metals in combined
residue from municipal and industrial wastes are based upon a limit of 1.5
21
-------
micrograms per cubic meter of stack gas, except for mercury which is limited
to 1 microgram per cubic meter:
Element p g/g
Arsenic 60
Cadmium 60
Selenium 60
Mercury 40
These concentrations are on a dry weight basis per pound of volatile
solids; therefore, an analysis on a wet basis must be corrected for moisture
content and percent volatile solids.
LANDSPREADING
Landspreading of municipal sludges is becoming more common in the United
States. Before landspreading is begun on a given plot, a complete metal analy-
sis should be made of the soil. Then semiannual analyses should be continued
to prevent excessive buildup of the metals. An analysis of the residue to be
spread should be made periodically. This periodic analysis would alert opera-
tors to any significant changes and would allow computation of theoretical
loading that might be applied without excessive buildup of metals in the soil
Obviously, the soil, the sludge, and the vegetative cover must all be managed!
Edible root crops, for example, should not be grown on soil amended with high
arsenic content sludges. Certain grain crops, rather than edible vegetative
crops, should be grown on land that has been amended by sludges containing
relatively high cadmium or mercury contents, etc.
Landspreading should not be practiced in certain areas such as on thin
soils over carbonate rock or in regions of karstic topography. Such a prac-
tice would contaminate groundwater with heavy metals, nitrates, and organic
material from the sludge.
Assistance in soil analysis, crop recommendations, and other pertinent
local factors may be obtained from the Soil Conservation Service and the County
Extension Service.
Application of residue to soil may be made until the metal content in the
soil approaches the levels given in Column 3 of Table 3. These values were
established for average metal content soils with carbon exchange capacity of
5 to 15 milliequivalents per 100 grams of soil. Local factors may require
reducing the limiting concentrations. In no case should the soil metal con-
tent be allowed to exceed those values given in Column 2 of Table 3. The
following factors may be used to calculate application loadings.
One pg/g in the soil is approximately two pounds per acre. (This assumes
the weight of the soil in the top 15 centimeters is two million pounds per acre)
22
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TABLE 3. METAL CONCENTRATION LIMITS
IN SLUDGES FOR LANDSPREADING
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Cobalt
Copper .
Lead
Lithium
Manganese
Mercury
Molybdenum
Nickel
Selenium
Silver
Sodium
Strontium
Thallium
Tin
Titanium
Tungsten
Vanadium
Zinc
Common
level
-g/g*
Varies
6
500
10
.06
100
8
20
10
850
.03
2
40
0.5
0.1
10
100
50
Maximum
level
ug/g-1-
40
3000
100
7.0
3000
40
100
500
4000
0.6
5
1000
2
5
400
500
300
Limiting
concent rations
per 100 tons
vg/g
20,000
25
25
3000
25
350
457T
1000
100
1000
4400-7T
10
1000
10
25
450
10
40
10% of Calcium
150
5
100
200
100
500
2000
*Most values from (1)
tSome values from (15)
irTaken from (16) with cation exchange capacity of 5-15 (meq/lOOg)
23
-------
One hundred short tons at 100 ug/g equals 10 mg/1 when incorporated in
the top 15 cm of soil.
The limiting concentrations given in Column 3 of Table 3 assumes that
the 100 tons will be applied over an extended period of time that will exceed
a minimum of 10 years. If the concentration of metals is higher, the amount
of sludge that may be applied to the soil is reduced. If more than 100 tons
of sludge is to be applied, the concentration must be reduced. Example calcu-
lations follow.
EXAMPLE 1. Suppose a sludge with the following metal content is to
be spread on pasture land: Boron 300 mg/1, Cadmium 60 mg/1, Chromium
700 mg/1, Copper 600 mg/1, Nickel 300 mg/1. No other metals are
present.
These concentrations are checked against Column 3 of Table 3, and
it is observed that cadmium exceeds the allowable concentration.
Therefore, the cadmium content governs the application, and thus,
45 mg/1 (allowable) ,.,.
60 mg/1 (existing) X 10° tons Per acre = 75 ton-
Thus, only 75 tons of this sludge may be applied per acre.
EXAMPLE 2. If more than 100 tons is to be spread per acre, say 125
tons, the limiting concentrations are computed thusly
100 .. . .
yjjr x limiting concentration = allowable concentration of metal in
the sludge.
This allowable concentration would then be 36 mg/1 for cadmium,
800 mg/1 for chromium, etc.
LANDFILL
The placing of sludges in landfills is practiced in many communities (3)•
however, this practice is not always satisfactory to all parties concerned.
A recent study of industrial waste disposal landfills showed 49 to 50 sites
studied had migration of metals (14). These were old sites, but it would
appear that the difference between old and new sites would be time.
The integrity of a landfill is extremely site specific. The type of soil
annual rainfall and annual runoff, depth to groundwater, depth to bedrock im-'
permeable substrata, etc., all impinge upon the suitability of a site for'a
landfill. Assistance in evaluation of these factors may be obtained from
fJa^rn^rcc*011 C°ntro1 Agencies, the Soil Conservation Service, State Geolog-
ical Commission, County Extension Service, the United States Geological
Survey, and the Environmental Protection Agency.
There have been numerous cases of contamination of groundwater with metals
from the disposal of industrial wastes (9, 17). One notable, recent case in
Minnesota involved contamination of groundwater with arsenic from a grasshopper
poison buried in the mid 1930's. The arsenic appeared almost 40 years later
(.yj. Additionally, there recently have been several fires and explosions with
injury to personnel at landfills where organic matter had been buried. Thus
if an impermeable cap is placed on a landfill to prevent leaching of metals/
24
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another problem is created by allowing methane to accumulate in large, poten-
tially explosive quantities.
Therefore, the conclusion must be that a landfill to dispose of toxic
metal wastes must be sealed at the bottom to prevent excessive leaching of the
potentially toxic metals to groundwater.
Sludges containing the following metals should not be placed in landfills
without encapsulation if the concentrations exceeds the limits set by local
and Federal authorities: Arsenic, Barium, Beryllium, Cadmium, Chromium,
Cobalt, Lead, Mercury, Selenium, and Vanadium. The limiting concentration
will be' site specific due to the variability of the parameters'that affect
leaching, such as annual rainfall, soil type, depth to groundwater, organic
matter, structural integrity of underlying strata, etc.
If local authorities determine that concentrations of metals''exceed safe
concentrations for landfill, the waste may be encapsulated.
ENCAPSULATION
Encapsulation (18) involves the surrbunding o'f the waste with an imper-
meable, durable material that will prevent leaching of the undesirable constit-
uents. Chemical fixation, as commonly practiced, is not encapsulation and
generally has been unsatisfactory (19).
The reason for this unsatisfactory performance appears to be that fixation
involves mixing the residue with a media that holds the residue but does not
prevent water from coming in contact with the residue. The residue and its
metal content is leached when the water does contact it (19).. In'fact,
some fixation processes allow the leaching of a typical metal, copper, from
a fixed sludge at a much faster rate than it is leached from the raw sludge
(19). This, of course, is directly opposite to the desired effect.
Encapsulation provides an impermeable boundary between the residue and
the environment, and therefore the residue is not leached because rainwater
and groundwater never come into contact with the residue (18).
25.
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REFERENCES
1. Page, A. L. Fate and Effects of Trace Elements is Sewage Sludges When
Applied to Agricultural Lands. EPA 670/2-74-005, U.S. Environmental
Protection Agency, Cincinnati, Ohio, Jan. 1974. 98 pp.
2. Carroll, Thomas E. et al. Review of Landspreading of Liquid Municipal
Sewage Sludge. EPA 670/2-75-049, Office of Research and Development,
U.S. Environmental Protection Agency, Cincinnati, Ohio, June 1975. 106 pp.
3. Bastian, Robert K. Municipal Sludge Management: An Overview of the
Sludge Management Situation. EPA 430/9-76-009, EPA Construction Grants
Program, U.S. Environmental Protection Agency, Washington, D.C., April
1976. 64 pp.
4. Council for Agricultural Science and Technology. Application of Sewage
Sludge to Cropland; Appraisal of Potential Hazards of the Heavy Metals
to Plants and Animals. EPA 430/9-76-013, Office of Water Program Oper-
ations, U.S. Environmental Protection Agency, Washington, D.C., NovT 1976
63 pp.
5. Martin, Elwood E. Supplement for Pretreatment to the Development Document
;-?rnS? ^l?™1* chemical Manufacturing Point Source Category. EPA 400/1-
77-087A, Office of Water and Hazardous Materials, U.S. Environmental
Protection Agency, Washington, D.C., July 1977. 282 pp.
6. Sittig, Marshall. Resource Recovery and Recycling Handbook of Industrial
Wastes. Noyes Data Corporation, Park Ridge, New Jersey, 1975. 427 pp.
7. Bureau of Mines. Minerals Yearbook: Volume I, Metals, Minerals, and
Fuels; Volume II: Area Reports-International. U.S. Department of the
Interior, 1972. 1103 pp.
8. Neufeld, Ronald D. Utilization of Biological Sludges for the Removal and
Possible Reclamation of Heavy Metals from Wastewater. In: Proceedings
of the National Conference on Management and Disposal of Residues from
the Treatment of Industrial Wastewaters. Information Transfer, Inc
Washington, D.C., Feb. 1975. pp. 73-77.
9. Office of Solid Waste Management Programs. Hazardous Waste Disposal
Damage Reports. EPA/530/SW-151, U.S. Environmental Protection Agency
Washington, D.C., June 1975. pp. 1-2.
26
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10. Environmental Protection Agency. National Emission Standards for Hazard-
ous Air Pollutants; Subpart E-National Emission Standard for Mercury,
40 CFR 61.52, Federal Register 48302, Oct. 14, 1975.
11. Hayes, Thomas D. and Thomas L. Theis. The Distribution of Heavy Metals
in Anaerobic Digestion. Journal Water and Pollution Control Federation
Jan. 1978. pp. 61-72.
12. Technology Transfer. Process Design Manual for Sludge Treatment and
Disposal. U.S. Environmental Protection Agency, Washington, D.C., Oct
1974. pp. 8-10.
13. Task Force on Sewage Incineration. Sewage Sludge Incineration. EPA/R2-
72-040, Washington, D.C., August 1972. 89 pp.
14. Geraghty and Miller, Inc. The Prevalence of Subsurface Migration of
Hazardous Chemical Substances at Selected Industrial Waste Land Disposal
Sites. EPA 625/77-1-008, U.S. Environmental Protection Agency, Washington,
U • Li • t JLy / / .
15. Technology Transfer. Process Design Manual for the Disposal of Waste-
waters and Sludges on Land. U.S. Environmental Protection Agency
Washington, D.C., 1977. pp. 5-10.
16. The Office of Water Program Operations. Municipal Sludge Management-
Environmental Factors. EPA 430/9-77-004, U.S. Environmental Protection
Agency, Municipal Construction Division, Washington, D.C., Sept 1977
31 pp.
17. Lazar, Emery C. Summary of Damage Incidents from Improper Land Disposal.
In: Proceedings of the National Conference on Management and Disposal
of Residues from the Treatment of Industrial Wastewaters, Washington
D.C., Feb. 1975. pp. 253-257. '
18. Lubowitz, H. R. et al. Development of a Polymeric Cementing and Encap-
sulating Process for Managing Hazardous Wastes. EPA 600/2-77-045, U.S.
Environmental Protection Agency, Cincinnati, Ohio, August 1977. 167*pp.
19. Mahlock, J. L. et al. Pollutant Potential of Raw and Chemically Fixed
Hazardous Industrial Wastes and Flue Gas Desulfruization Sludges.
EPA 600/2-76-182, Interim Report, U.S. Environmental Protection Agency
Cincinnati, Ohio, July 1976. 117 pp.
20. Settlement Agreement. Natural Resources Defense Council, Inc., et al
versus Russell E. Train. United States District Court for the District
of Columbia, Washington, D.C., June 1976.
27
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APPENDIX A
INDUSTRIAL WASTE SURVEY
An industrial waste survey is necessary to determine source, quantity,
etc. of materials discharged to the sewer system. The procedure for the
waste survey is given in "Handbook for Monitoring Industrial Wastewater" and
the analysis of the waste in "Manual of Methods for Chemical Analysis of
Water and Wastes." Both manuals are available form the Office of Technology
Transfer, Cincinnati, Ohio 45268.
The first section of this manual, along with Appendix B, will provide
information on what metals would be expected in the waste streams.
28
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APPENDIX B
METALS FROM POINT SOURCE CATEGORY
TABLE B-l. METALS IN SETTLEMENT AGREEMENT
Point Source. Categories i'2'J) As AR Be Cd Cr Cu Hj? Ni Pb Se Sb Tl Zn
1.
2.
3.
4.
5.
6.
7.
8.
9.
10-
to
11.
12.
13.
14.
Timber Products Processing X XX
Steam Electric Power Plants XX X X
Leather Tanning and Finishing X X
Iron and Steel Manufacturing XX X
Petroleum Refining XX X
Inorganic Chemicals
Manufacturing XXX X X X
Textile Mills X XX XX
Organic Chemicals
Manufacturing X X X X X X X
Nonferrous Metals
Manufacturing XXXXXX XXXX
Paving and Roofing
Materials
Paint and Ink Formulation
and Painting X XXXXXXX
Soap and Detergent
Manufacturing . X
Auto and Other Laundries
Plastic and Synthetic
X
X
X
X
X
X
Materials Manufacturing
15. Pulp and Paper Mills and
Converted Paper Products
16. Rubber Processing
17. Miscellaneous -Chemicals
18. Machinery and Mechanical
Products Manufacturing
19. Electroplating
20. Ore Mining and Dressing
21. Coal Mining
X
X
X
X
X
X X
X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
XX X
XXXX
X X X X X
X
X X X
X X
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TABLE 13-2. OTHER METALS OF CONCERN
Point Source Categories (20)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
Timber Products Processing
Steam Electric Power Plants
Leather Tanning and Finishing
Iron and Steel Manufacturing
Petroleum Refining
Inorganic Chemicals
Manufacturing
Textile Mills
Organic Chemicals
Manufacturing
Nonferrous Metals
Manufacturing
Paving and Roofing
Material
Paint and Ink Formulation
and Painting
Soap and Detergent
Manufacturing
Auto and Other Laundries
Plastic and Synthetic
Materials Manufacturing
Pulp and Paper Mills and
Converted Paper Products
Rubber Processing
Miscellaneous Chemicals
Machinery and Mechanical
Products Manufacturing
Electroplating
Ore Mining and Dressing
Coal Mining
Al
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
B Ba Co Li Mn Mo Na PI Sn Sr Ti V W
X X
X
X X
XXX XX XXXX
XXX X
X X
X XXX
X XX
X X XXXX XXX
XXX XX XX
X X
X
X XX
X X
X X
XXX X XX
X XXX XXXX X
X X
XXX XX XX XXX
X X
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-79-052
3. RECIPIENT'S ACCESSION>NO.
4. TITLE AND SUBTITLE
Manual of Practice: The Disposal of Combined
Municipal/Industrial Wastewater Residues (Metals)
5. REPORT DATE
February 1979 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Hugh M. Jeffus
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Same as below
10. PROGRAM ELEMENT NO.
1BB610
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Robert S. Kerr Environmental Research Laboratory-
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/15
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This manual gives the processes and products where different metals are used
in order that potential sources of metals in combined wastewater residues may
be identified. Potential problems in disposal of these residues are identified.
Most metals are toxic to plants or animals at some concentration and, therefore,
pose potential environmental or health problems.
Disposal practices, incineration, landspreading, landfilling, and encapsulation
are discussed. Limiting concentrations of potential problem metals are given
for incineration and landspreading.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Sludge Disposal
Metals
Residues-Wastes
Incinerators
Encapsulating
Metals - Sources
Landspreading
Landfill
68C
18. DISTRIBUTION STATEMENT
Release unlimited
19. SECURITY CLASS (ThisReport)'
Unclassified
21. NO. OF PAGES
39
2O. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
31
U. S. GOVERNMENT PRINTING OFFICE: 1979-657-060/1620 Region No. 5-11
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