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SECTION VI
SELECTION OF POLLUTANT PARAMETERS
Section V presented pollutant parameters to be examined for
possible regulation along with data from plant sampling visits
and subsequent chemical analysis. Priority, non-conventional,
and conventiona] pollutant parameters were selected according to
a specified rationale. Pollutant parameters not detected, or
detected at not quantifiable concentrations were eliminated from
further consideration for regulation. All others which were
detected are discussed in this section. The selected priority
pollutant parameters are discussed in numerical order, followed
by non-conventional pollutants and then conventional pollutant
parameters, each in alphabetical order.
Finally, the pollutant parameters selected for consideration for
specific regulation and those dropped from further consideration
are set forth. The rationale for that selection is also
presented. The occurence and levels of pollutants found are
drawn from Table V-8 (page 50).
POLLUTANT PARAMETERS
Table VI-1 (page 98) lists all the priority pollutant parameters.
For those not followed by an ND or NQ a discussion is presented
in this section. The discussion provides information about:
where the pollutant comes from - whether it is a naturally
occurring element, processed metal, or manufactured compound;
general physical properties and the form of the pollutants; toxic
effects of the pollutant in humans and other animals; and
behavior of the pollutant in POTW at the concentrations that
might be expected from industrial discharges. Specific
literature relied upon-for the following discussion is listed in
Section XV. Particular weight has been given to documents
generated by the EPA Criteria and Standards Division and
Monitoring and Data Support Division.
1,1,1-Trichloroethane(11). 1,1,1-Trichloroethane is one of the
two possible trichloroethanes. It is manufactured by
hydrochlorinating vinyl chloride to 1,1-dichloroethane which is
then chlorinated to the desired product. 1,1,1-Trichloroethane
is a liquid at room temperature with a vapor pressure of 96 mm Hg
at 20°C and a boiling point of 74°C. Its formula is CC13CH3. It
is slightly soluble in water (0.48 g/1) and is very soluble in
organic solvents. U.S. annual production is greater than one-
third of a million tons.
63
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1,1,1-Trichloroethane is used as an industrial solvent and
degreasing agent.
Most human toxicity data for 1,1,1-trichloroethane relates to
inhalation and dermal exposure routes. Limited data are
available for determining toxicity of ingested 1,1,1-
trichloroethane, and those data are all for the compound itself
not solutions in water. No data are available regarding its
toxicity to fish and aquatic organisms. For the protection of
human health from the toxic properties of 1,1,1-trichloroethane
ingested through the consumption of water and fish, the ambient
water criterion is 18.4 mg/1. The criterion is based on bioassay
for possible carcinogenicity.
No detailed study of 1,1,1-trichloroethane behavior in POTW is
available; however, it has been demonstrated that none of the
organic priority pollutants of this type can be broken down by
biological treatment processes as readily as fatty acids,
carbohydrates, or proteins.
Biochemical oxidation of many of the organic priority pollutants
has been investigated in laboratory scale studies at
concentrations higher than commonly expected in municipal
wastewater. General observations relating molecular structure to
ease of degradation have been developed for all of these
pollutants. The conclusion reached by study of the limited data
is that biological treatment produces a moderate degree of
degradation of 1,1,1-trichloroethane. No evidence is available
for drawing conclusions about its possible toxic or inhibitory
effect on POTW operation; however, for degradation to occur, a
fairly constant input of the compound would be necessary.
Its water solubility would allow 1,1,1-trichloroethane, present
in the influent and riot biodegradable, to pass through a POTW
into the effluent. One factor which has received some attention,
but no detailed study, is the volatilization of the lower
molecular weight organics from POTW. If 1,1,1-trichloroethane is
not biodegraded, it will volatilize during aeration processes in
the POTW.
1,1-Dichloroethylene(29). 1,1-Dichloroethylene (1,1-DCE), also
called vinylidene chloride, is a clear colorless liquid
manufactured by dehydrochlorination of 1,1,2-trichloroethane.
1,1-DCE has the formula CC12CH2. It has a boiling paint of 32°C,
and a vapor pressure of 591 mm Hg at 25°C. 1,1-DCE is slightly
soluble in water (2.5 mg/1) and is soluble in many organic
solvents. U.S. production is in the range of hundreds of
thousands of tons annually.
64
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1,1-DCE is used as a chemical intermediate arid for copolymer
coatings or films. It may enter the wastewater of an industrial
facility as the result of decomposition of 1,1,1-
trichloroethylene used in degreasing operations, or by migration
from vinylidene chloride copolymers exposed to the process water.
i -
Human toxicity of 1,1-DCE has not been demonstrated, although it
is a suspected human carcinogen. Mammalian toxicity studies have
focused on the liver and kidney .damage produced by 1,1-DCE.
Various changes occur in those organs in rats and mice ingesting
1,1-DCE. ,
For the maximum protection of human health from the potential
carcinogenic effects of exposure to 1,1-dichloroethylene through
ingestion of water and contaminated aquatic organisms, the
ambient water concentration is zero. The concentration of 1,1-
DCE estimated to result in an additional lifetime cancer risks of
10~4, 10-s, and 10~« are 3.3 x 10~« mg/1, 3.3 x 10-* mg/1, and
3.3 x 10~* mg/1. If contaminated organisms alone are consumed
excluding the consumption of water, the water concentration
should be less than 0.019 mg/1 to keep the lifetime cancer risk
below TO-5.
Under laboratory conditions, dichloroethylenes have been shown to
be toxic to fish. Limited acute and chronic toxicity data for
aquatic life show that adverse effects occur at concentrations
higher than those cited for human;health risks. The primary
effect of acute toxicity of the dichloroethylenes is depression
of the central nervous system. The octanol-water partition
coefficident of 1,1-DCE indicates it should not accumulate
significantly in animals.
The behavior of 1,1-DCE in POTW has not been studied. However,
its very high vapor pressure is expected to result in release of
significant percentages of this material to the atmosphere in any
treatment involving aeration. Degradation of dichloroethylene in
air is reported to occur, with a half-life of 8 weeks.
Biochemical oxidation of many of the organic priority pollutants
has been investigated in laboratory-scale studies at
concentrations higher than would normally be expected in
municipal wastewaters. General observations relating molecular
structure to ease of degradation have been developed for all of
these pollutants. The conclusion reached by study of the limited
data is that biological treatment in POTW produces little or no
biochemical oxidation of 1,1-dichloroethylene. No evidence is
available for drawing conclusions about the possible toxic or
inhibitory effect of 1,1-DCE on POTW operation. Because of water
solubility, 1,1-DCE which is not volatilized or degraded is
65
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is expected
expected to pass through POTW. Very little 1,1-DCE
to be found in sludge from POTW.
Methylene Chloride
ii.il- Methylene chloride, also called
dichlormethane (CH2C12), is a colorless liquid manufactured by
chlorination of methane or methyl chloride followed by separation
from the higher chlorinated methanes formed as coproducts.
Methylene chloride boils at 40°C, and has a vapor pressure of 362
mm Hg at 20°C. It is slightly soluble in water (20 g/1 at 20°C),
and very soluble in organic solvents. U.S. annual production is
about 250,000 tons.
Methylene chloride is a common industrial solvent found in
insecticides, metal cleaners, paint, and paint and varnish
removers.
Methylene chloride is not generally regarded as highly toxic to
humans. Most human toxicity data are for exposure by inhalation.
Inhaled methylene chloride acts as a central nervous system
depressant. There is also evidence that the compound causes
heart failure when large amounts are inhaled.
Methylene chloride does produce mutation in tests for this
effect. In addition, a bioassay recognized for its extremely
high sensitivity to strong and weak carcinogens produced results
which were marginally significant. Thus potential carcinogenic
effects of methylene chloride are not confirmed or denied, but
are under continuous study. Difficulty in conducting and
interpreting the test results from the low boiling point (40°C)
of methylene chloride which increases the difficulty of
maintaining the compound in growth media during incubation at
37°C; and from the difficulty of removing all impuities, some of
which might themselves be carcinogenic.
For the protection of human health from the toxic properties of
methylene chloride ingested through water and contaminated
aquatic organisms, the ambient water criterion is 0.002 mg/1.
The behavior of methylene chloride in a POTW has not been studies
in any detail. However, the biochemical oxidation of this
conpound was studied in one laboratory scale at concentrations
higher than those expected to be contained by most municipal
wastewaters. After five days no degradation of methylene
chloride was observed. The conclusion reached is that biological
treatment produces little or no removal by degradation of
methylene choride in a POTW.
The high vapor pressure of methylene chloride is expected to
result in volatilization of the compound from aerobic treatment
steps in a POTW. It has been reported that methylene chloride
inhibits anerobic processes in a POTW. Methylene chloride that
66
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is not volatillized in the POTW is expected to pass through
the effluent.
into
called isophthalic and
for? all three acids is
Phthalate Esters (66-71). Phthalic acid, or 1/2-
benzenedicarboxylic acid, is one of three isomeric
benzenedicarboxylic acids produced by the chemical industry.
The other two isomeric forms are
terephthalic acids. The formula
C6H4(COOH)2. Some esters of phthalic acid are designated as
priority pollutants. They will be discussed as a group here, and
specific properties of individual phthalate esters will be
discussed afterwards.
Over one billion pounds of phthalic acid esters are manufactured
in the U.S. annually. They are used as plasticizers - primarily
in the production of polyvinyl chloride (PVC) resins. The most
widely used phthalate plasticizer is bis (2-ethylhexyl ) phthalate
(66) which accounts for nearly one 'third of the phthalate esters
produced. This particular ester is commonly referred to as
dioctyl phthalate (DOP) and should not be confused with one of
the less used esters, di-n-bctyl phthalate (69), which is also
used as a plasticizer. In addition to these two isomeric dioctyl
phthalates, four other esters, also used primarily as
plasticizers, are designated as priority pollutants. They are:
butyl benzyl phthalate (67); di-n-butyl phthalate (68); diethyl
phthalate (70); and dimethyl phthalate (71).
Industrially, phthalate esters are prepared from phthalic
anhydride and the specific alcohol to form the ester. Some
evidence is available suggesting that phthalic acid esters also
may be synthesized by certain plant and animal tissues. The
extent to which this occurs in nature is not known.
Phthalate esters used as plasticizers can be present in
concentrations of up to 60 percent of the total weight of the PVC
plastic. The plasticizer is not linked by primary chemical bonds
to the PVC resin. Rather, it is locked into the structure of
intermeshing polymer molecules and held by van der Waals forces.
The result is that the plasticizer is easily extracted.
Plasticizers are responsible for the odor associated with new
plastic toys or flexible sheet that has been contained in a
sealed package.
Although the phthalate esters are not soluble or are only very
slightly soluble in water, they do migrate into aqueous solutions
placed in contact with the plastic. Thus industrial facilities
with tank linings, wire and cable coverings, tubing, and sheet
flooring of PVC are expected to discharge some phthalate esters
in their raw waste. In addition to their use as plasticizers,
phthalate esters are used in lubricating oils and pesticide
67
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carriers. These also can contribute to industrial
phthalate esters.
discharge of
The accumulated data on acute toxicity in animals suggest that
phthalate esters have a rather low order of toxicity. Human
toxicity data are limited. It are thought that the toxic effects
of the esters is most likely due to one of the metabolic
products, in particular the monoester. Oral acute toxicity in
animals is greater for the lower molecular weight esters than for
the higher molecular weight esters.
Orally administered phthalate esters generally produced enlarging
of liver and kidney, and atrophy of testes in laboratory animals.
Specific esters produced enlargement of heart and brain,
spleenitis, and degeneration of central nervous system tissue.
Subacute doses administered orally to laboratory animals produced
some decrease in growth and degeneration of the testes. Chronic
studies in animals showed similar effects to those found in acute
and subacute studies, but to a much lower degree. The same
organs were enlarged, but pathological changes were not usually
detected.
A recent study of several phthalic esters produced suggestive but
not conclusive evidence that dimethyl and diethyl phthalates have
a cancer liability. Only four of the six priority pollutant
esters were included in the study. Phthalate esters do
biconcentrate in fish. The factors, weighted for relative
consumption of various aquatic and marine food groups, are used
to calculate ambient water quality criteria for four phthalate
esters. The values are included in the discussion of the
specific esters.
Studies of toxicity of phthalate esters in freshwater and salt
water organisms are scarce. A chronic toxicity test with bis(2-
ethylhexyl) phthalate showed that significant reproductive
impairment occurred at 0.003 mg/1 in the freshwater crustacean,
Daphnia maqna. In acute toxicity studies, saltwater fish and
organisms showed sensitivity differences of up to eight-fold to
butyl benzyl, diethyl, and dimethyl phthalates. This suggests
that each ester must be evaluated individually for toxic effects.
The behavior of phthalate esters in POTW has not been studied.
However, the biochemical oxidation of many of the organic
priority pollutants has been investigated in laboratory-scale
studies at concentrations higher than would normally be expected
in municipal wastewater. Three of the phthalate esters were
studied. Bis(2-ethylhexyl) phthalate was found to be degraded
slightly or not at all and its removal by biological treatment in
a POTW is expected to be slight or zero. Di-n-butyl phthalate
68
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and diethyl phthalate were degraded to a moderate degree and
their removal by biological treatment in a POTW is expected to
occur to a moderate degree. Using these data and other
observations relating molecular structure to ease of biochemical
degradation of other organic pollutants, the conclusion was
reached that butyl benzyl phthalate and dimethyl phthalate would
be removed in a POTW to a moderate degree by biological
treatment. On the same basis, it was concluded that di-n-octyl
phthalate would be removed to a slight degree or not at all.
No information was found on possible interference with POTW
operation or the possible effects on sludge by the phthalate
esters. The water insoluble phthalate esters - butyl benzyl and
di-n-octyl phthalate - would tend to remain in sludge, whereas
the other four priority pollutant phthalate esters with water
solubilities ranging from 50 mg/1 to 4.5 mg/1 would probably pass
through into the POTW effluent.
Bis (2-ethylhexyl) phthalate(66). Little information is
available about the physical properties of bis(2-ethylhexyl)
phthalate. It is a liquid boiling at 387°C at 5mm Hg and is
insoluble in water. Its formula is C«H4(COOC8H17)2. This
priority pollutant constitutes about one third of the phthalate
ester production in the U.S. It is commonly referred to as
dioctyl phthalate, or DOP, in the plastics industry where it is
the most extensively used compound for the plasticization of
polyvinyl chloride (PVC). Bis(2-ethylhexyl) phthalate has been
approved by the FDA for use in plastics in contact with food.
Therefore, it may be found in wastewaters coming in contact with
discarded plastic food wrappers as well as the PVC films and
shapes normally found in industrial plants. This priority
pollutant is also a commonly used organic diffusion pump oil
where its low vapor pressure is an advantage.
For the protection of human health from the toxic properties of
bis(2-ethylhexyl) phthalate ingested through water and through
contaminated aquatic organisms, the ambient water quality
criterion is determined to be 15 mg/1.
Although the behavior of bis{2-ethylhexyl) phthalate in POTW has
not been studied, biochemical oxidation of this priority
pollutant has been studied on a laboratory scale at
concentrations higher than would normally be expected in
municipal wastewater. In fresh water with a non-acclimated seed
culture, no biochemical oxidation was observed after 5, 10, and
20 days; with an acclimated seed culture, however, biological
oxidation of 13, 0, 6, and 23 percent of theoretical occurred
after 5, 10, 15 and 20 days, respectively. Bis(2-ethylhexyl)
phthalate concentrations were 3 to 10 mg/1. Little or no removal
69
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of bis(2-ethylhexyl) phthalate by biological treatment in POTW is
expected.
Butyl benzyl phthalate(67). No information
physical properties of this compound.
was found on the
Butyl benzyl phthalate is used as a plasticizer for PVC. Two
special applications differentiate it from other phthalate
esters. It is approved by the U.S. FDA for food contact in
wrappers and containers; and it is the industry standard for
plasticization of vinyl flooring because it provides stain
resistance.
No ambient water quality criterion is proposed for
phthalate.
butyl benzyl
Butyl benzyl phthalate removal in POTW by biological treatment in
a POTW is expected to occur to a moderate degree.
Di-n-butyl phthalate (68). Di-n-butyl phthalate (DBP) is a
colorless, oily liquid, boiling at 340°C. Its water solubility
at room temperature is reported to be 0.4 g/1 and 4.5g/l in two
different chemistry handbooks. The formula for
DBP, C6H4.(COOC4H9)2 is the same as for its isomer, di-isobutyl
phthalate. DBP production is one to two percent of total U.S.
phthalate ester production.
DBP is used to a limited extent as a plasticizer for polyvinyl
chloride (PVC). It is not approved for contact with food. It is
used in liquid lipsticks and as a diluent for polysulfide dental
impression materials. DBP is used as a plasticizer for
nitrocellulose in making gun powder, and as a fuel in solid
propellants for rockets. Further uses are insecticides, safety
glass manufacture, textile lubricating agents, printing inks,
adhesives, paper coatings and resin solvents.
For protection of human health from the toxic properties of
dibutyl phthalate ingested through water and through contaminated
aquatic organisms, the ambient water quality criterion is
determined to be 34 mg/1.
Although the behavior of di-n-butyl phthalate in POTW has not
been studied, biochemical oxidation of this priority pollutant
has been studied on a laboratory scale at concentrations higher
than would normally be expected in municipal wastewater.
Biochemical oxidation of 35, 43, and 45 percent of theoretical
oxidation were obtained after 5, 10, and 20 days, respectively,
using sewage microorganisms as an unacclimated seed culture.
70
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Biological treatment in POTW
phthalate to a moderate degree.
is expected to remove di-n-butyl
formula C6H5CH3. It boils at
30 mm Hg at room temperature.
Toluene(86). Toluene is a clear, colorless liquid with a
benzene-like odor. It is a naturally occuring compound derived
primarily from petroleum or petrochemical processes. Some
toluene is obtained from the manufacture of metallurgical coke.
Toluene is also referred to as toluol, methylbenzene, methacide,
and phenylmethane. It is an aromatic hydrocarbon with the
111°C and has a vapor pressure of
The water solubility of toluene is
535 mg/1, and it is miscible with a variety of organic solvents.
Annual production of toluene in the U.S. is greater than 2
million metric tons. Approximately two-thirds of the toluene is
converted to benzene; the remaining 30 percent is divided
approximately equally into chemical manufacture and use as a
paint solvent and aviation gasoline additive. An estimated 5,000
metric tons is discharged to the environment annually as a
constituent in wastewater.
Most data on the effects of toluene in human and other mammals
have been based on inhalation exposure or dermal contact studies.
There appear to be no reports-of oral administration of toluene
to human subjects. A long term toxicity study on female rats
revealed no adverse effects on growth, mortality, appearance and
behavior, organ to body weight ratios, blood-urea nitrogen
levels, bone marrow counts, peripheral blood counts, or
morphology of major organs. The effects of inhaled toluene on
the central nervous system, both at high and low concentrations,
have been studied in humans and animals. However, ingested
toluene is expected to be handled differently by the body because
it is absorbed more slowly and must first pass through the liver
before reaching the nervous system. Toluene is extensively and
rapidly metabolized in the liver. One of the principal metabolic
products of toluene is benzoic acid, which itself seems to have
little potential to produce tissue injury.
Toluene does not appear to be teratogenic in laboratory animals
or man. Nor is there any conclusive evidence that toluene is
mutagenic. Toluene has not been demonstrated to be positive in
any in vitro mutagenicity or carcinogenicity bioassay system, nor
to be carcinogenic in animals or man.
Toluene has been found in fish caught in harbor waters in the
vicinity of petroleum and petrochemical plants. Bioconcentration
studies have not been conducted, but bioconcentration factors
have been calculated on the basis of the octanol-water partition
coefficient.
71
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For the protection of human health from the toxic properties of
toluene ingested through water and through contaminated aquatic
organisms, the ambient water criterion is determined to be 14.3
mg/1. If contaminated aquatic organisms alone are consumed
excluding the consumption of water, the ambient water criterion
is 424 mg/1. Available data show that the adverse effects on
aquatic life occur at concentrations as low as 5 mg/1.
Acute toxicity tests have been conducted with toluene and a
variety of freshwater fish and Daphnia magna. The latter appears
to be significantly more resistant than fish. No test results
have been reported for the chronic effects of toluene on
freshwater fish or invertebrate species.
No detailed study of toluene behavior in POTW is available.
However, the biochemical oxidation of many of the priority
pollutants has been investigated in laboratory scale studies at
concentrations greater than those expected to be contained by
most municipal wastewaters. At toluene concentrations ranging
from 3 to 250 mg/1 biochemical oxidation proceeded to fifty
percent of theoretical oxidation or greater. The time period
varied from a few hours to 20 days, depending on whether or not
the seed culture was acclimated. Phenol adapted acclimated seed
cultures gave the most rapid and extensive biochemical oxidation.
The conclusion reached by study of the limited data is that
biological treatment produces moderate removal of toluene in
POTW. The volatility and relatively low water solubility of
toluene lead to the expectation that aeration processes will
remove significant quantities of toluene from the POTW. The EPA
studied toluene removal in seven POTW facilities. The removals
ranged from 40 to TOO percent. Sludge concentrations of toluene
ranged from 54 x TO-3 to 1.85 mg/1.
Arsenic (115). Arsenic (chemical symbol As), is classified as a
non-metal or metalloid. Elemental arsenic normally exists in the
alpha-crystalline metallic form which is steel gray and brittle,
and in the beta form which is dark gray and amorphous. Arsenic
sublimes at 615°C. Arsenic is widely distributed throughout the
world in a large number of minerals. The most important
commercial source of arsenic is as a by-product from treatment of
copper, lead, cobalt, and gold ores. Arsenic is usually marketed
as the trioxide (As203). Annual U.S. production of the trioxide
approaches 40,000 tons.
The principal use of arsenic is in agricultural chemicals
(herbicides) for controlling weeds in cotton fields. Arsenicals
have varioys applications in medicinal and vetrinary use, as wood
preservatives, and in semicconductors.
72
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The effects of arsenic in humans were known by the ancient Greeks
and Romans. The principal toxic effects are gastrointestinal
disturbances. Breakdown of red blood cells occurs. Symptoms of
acute poisoning include vomiting, diarrhea, abdominal pain,
lassitude, dizziness, and headache. Longer exposure produced
dry, falling hair, brittle, losse nails, eczena, and exfoliation.
Arsenicals also exhibit teratogenic and mutagenic effects in
humans. Oral administration of arsenic compounds has been
associated clinically with skin cancer for nearly one hundred
years. Since 1888 numerous studies have linked occupational
exposure and therapeutic administration of arsenic compounds to
increased incidence of respiratory and skin cancer.
For the maximum protection of human health from the potential
carcinogenic effects of exposure to arsenic through ingestion of
water and contaminated aquatic organisms, the ambient water
concentration is zero. Concentrations of arsenic estimated to
result in additional lifetime cancer risk levels of 10-7, 10-«,
and 10-5 are 2.2 x TO-7 mg/1, 2.2 x 10-6 mg/1, and 2.2 x TO-5
mg/1. respectively. If contaminated aquatic organisms alone are
consumed, excluding the consumption of water, the water
concentration should be less than 1.75 x 10-* to keep the
increased lifetime cancer risk below 10-s. Available data show
that adverse effects on aquatic life occur at concentrations
higher than those cited fro human health risks.
A few studies have been made regarding the behavior of arsenic in
a POTW. One EPA survey of nine POTW facilities reported influent
concentrations ranging from 0.0005 to 0.693 mg/1; effluents from
three a POTW having biological treatment contained 0.0004 to 0.01
mg/1; two POTW facilities showed arsenic removal efficiencies of
50 and 71 percent in biological treatment. Inhibition of
by sodium arsenate is reported to occur at
sludge, and 1.6 mg/1 in in anaerobic
In another study based on data from 60 POTW
in sludge ranged from 1.6 to 65.5 mg/kg and
the median value was 7.8 mg/kg. Arsenic in sludge spread on
cropland may be taken up by plants grown on that land. Edible
plants can take up arsenic, but normally their growth is
inhibited before the plants are ready for harvest.
Cadmium (118). Cadmium is a relatively rare metallic element
that is seldom found in sufficient quantities in a pure state to
warrent mining or extraction from the earth's surface. It is
found in trace amounts of about 1 ppm throughout the earth's
crust. Cadmium is, however, a valuable by-product of zinc
production.
treatment processes
0.1 mg/1 in activated
digestion processes.
facilities, arsenic
73
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Cadmium is used primarily as an electroplated metal, and is found
as an impurity in the secondary refining of zinc, lead, and
copper.
Cadmium is an extremely dangerous cumulative toxicant, causing
progressive chronic poisoning in mammals, fish, and probably
other organisms. The metal is not excreted.
Toxic effects of cadmium on man have been reported from
throughout the world. Cadmium may be a factor in the development
of such human pathological conditions as kidney disease,
testicular tumors, hypertension, arteriosclerosis, growth
inhibition, chronic disease of old age, and cancer. Cadmium is
normally ingested by humans through food and water as well as by
breathing air contaminated by cadmium dust. Cadmium is
cumulative in the liver, kidney, pancreas, and thyroid of humans
and other animals. A severe bone and kidney syndrome known as
itai-itai disease has been documented in Japan as caused by
cadmium ingestion via drinking water and contaminated irrigation
water. Ingestion of as little as 0.6 mg/day has produced the
disease. Cadmium acts synergistically with other metals. Copper
and zinc substantially increase its toxicity.
Cadmium is concentrated by marine organisms, particularly
molluscs, which accumulate cadmium in calcareous tissues and in
the viscera. A concentration factor of 1000 for cadmium in fish
muscle has been reported, as have concentration factors of 3000
in marine plants and up to 29,600 in certain marine animals. The
eggs and larvae of fish are apparently more sensitive than adult
fish to poisoning by cadmium, and crustaceans appear to be more
sensitive than fish eggs and larvae.
For the protection of human health from the toxic properties of
cadmium ingested through water and through contaminated aquatic
organisms, the ambient water criterion is determined to be 0.010
mg/1.
Cadmium is not destroyed when it is introduced into a POTW, and
will either pass through to the POTW effluent or be incorporated
into the POTW sludge. In addition, it can interfere with the
POTW treatment process.
In a study of 189 POTW, 75 percent of the primary plants, 57
percent of the trickling filter plants, 66 percent of the
activated sludge plants and 62 percent of the biological plants
allowed over 90 percent of the influent cadmium to pass through
to the POTW effluent. Only 2 of the 189 POTW allowed less than
20 percent pass-through, and none less than 10 percent pass-
through. POTW effluent concentrations ranged from 0.001 to
1.97 mg/1 (mean 0.028 mg/1, standard deviation 0.167 mg/1).
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Cadmium not passed through the POTW will be retained in the
sludge, where it is likely to build up in concentration. Cadmium
contamination of sewage sludge limits its use on land since it
increases the level of cadmium in the soil. Data show that
cadmium can be incorporated into crops, including vegetables and
grains, from contaminated soils. Since the crops themselves show
no adverse effects from soils with levels up to 100 mg/kg
cadmium, these contaminated crops could have a significant impact
on human health. Two Federal agencies have already recognized
the potential adverse human health effects posed by the use of
sludge on cropland. The FDA recommends that sludge containing
over 30 mg/kg of cadmium should not be used on agricultural land.
Sewage sludge contains 3 to 300 mg/kg (dry basis) of cadmium mean
= 10 mg/kg; median = 16 mg/kg. The USDA also recommends placing
limits on the total cadmium from sludge that may be applied to
land.
Chromium(119). Chromium is an elemental metal usually found as a
chromite (FeO»Crj,03). The metal is normally produced by reducing
the oxide with aluminum. A significant proportion of the
chromium used is in the form of compounds such as sodium
dichromate (Na?Cr04), and chromic acid (Cr03) - both are
hexavalent chromium compounds.
Chromium and its compounds are used extensively in the canmaking
subcategory of the coil coating industry. As the metal, it is
found as an alloying component of many steels.
The two chromium forms most frequently found in industry
wastewaters are hexavalent and trivalent chromium. Hexavalaent
chromium is the form used for metal treatments. Some of it is
reduced to trivalent chromium as part of the process reaction.
The raw wastewater containing both valence states is usually
treated first to reduce remaining hexavalent to trivalent
chromium, and second to precipitate the trivalent form as the
hydroxide. The hexavalent form is not removed by lime treatment.
Chromium, in its various valence states, is hazardous to man. It
can produce lung tumors when inhaled, and induces skin
sensitizations. Large doses of chromates have corrosive effects
on the intestinal tract and can cause inflammation of the
kidneys. Hexavalent chromium is a known human carcinogen.
Levels of chromate ions that show no effect in man appear to be
so low as to prohibit determination, to date.
The toxicity of chromium salts to fish and other aquatic life
varies widely with the species, temperature, pH, valence of the
chromium, and synergistic or antagonistic effects, especially the
effect of water hardness. Studies have shown that trivalent
chromium is more toxic to fish of some types than is hexavalent
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chromium. Hexavalent chromium retards growth of one fish species
at 0.0002 mg/1. Fish food organisms and other lower forms of
aquatic life are extremely sensitive to chromium. Therefore,
both hexavalent and trivalent chromium must be considered harmful
to particular fish or organisms.
For the protection of human health from the toxic properties of
chromium (except hexavalent chromium) ingested through water and
contaminated aquatic organisms, the recommended water qualtiy
criterion is 170 mg/1.
For the protection of human health from the toxic effects of
exposure to hexavalent chromium through ingestion of water and
contaminated aquatic organisms, the ambient water concentration
is zero.
Chromium is not destroyed when treated by POTW (although the
oxidation state may change), and will either pass through to the
POTW effluent or be incorporated into the POTW sludge. Both
oxidation states can inhibit POTW treatment and can also limit
the usefuleness of municipal sludge.
EPA has observed influent concentrations of chromium to POTW
facilities to range from 0.005 to 14.0 mg/1, with a median
concentration of 0.1 mg/1. The efficiencies for removal of
chromium by the activated sludge process can vary greatly,
depending on chromium concentration in the influent, and other
operating conditions at the POTW. Chelation of chromium by
organic matter and dissolution due to the presence of carbonates
can cause deviations from the predicted behavior in treatment
systems.
The systematic presence of chromium compounds will halt
nitrification in a POTW for short periods, and most of the
chromium will be retained in the sludge solids. Hexavalent
chromium has been reported to severely affect the nitrification
process, but trivalent chromium has little or no toxicity to
activated sludge, except at high concentrations. The presence of
iron, copper, and low pH will increase the toxicity of chromium
in a POTW by releasing the chromium into solution to be ingested
by microorganisms in the POTW.
The amount of chromium which passes through to the POTW effluent
depends on the type of treatment processes used by the POTW. In
a study of 240 POTW's, 56 percent of the primary plants allowed
more than 80 percent pass through to POTW effluent. More
advanced treatment results in less pass-through. POTW effluent
concentrations ranged from 0.003 to 3.2 mg/1 total chromium (mean
« 0.197, standard deviation = 0.48), and from 0.002 to 0.1 mg/1
hexavalent chromium (mean = 0.017, standard deviation = 0.020).
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Chromium not passed through the POTW will be retained in the
sludge, where it is likely to build up in concentration. Sludge
concentrations of total chromium of over 20,000 mg/kg (dry basis)
have been observed. Disposal of sludges containing very high
concentrations of trivalent chromium can potentially cause
problems in uncontrollable landfills. Incineration, or similar
destructive oxidation processes can produce hexavalent chromium
from lower valance states. Hexavalent chromium is potentially
more toxic than trivalent chromium. In cases where high rates of
chrome sludge application on land are used, distinct growth
inhibition and plant tissue uptake have been noted.
Pretreatment of discharges substantially reduces the
concentration of chromium in sludge. In Buffalo, New York,
pretreatment of electroplating waste resulted in a decrease in
chromium concentrations in POTW sludge from 2,510 to 1,040 mg/kg.
A similar reduction occurred in a Grand Rapids, Michigan, POTW
where the chromium concentration in sludge decreased from 11,000
to 2,700 mg/kg when pretreatment was required.
Copper(120). Copper is a metallic element that sometimes is
found free, as the native metal, and is also found in minerals
such as cuprite (Cu20), malechite [CuC03»Cu(OH)2], azurite
[2CuC03«Cu(OEJ)?3, chalcopyrite (CuFeS2), and bornite (Cu5FeS4).
Copper is obtained from these ores by smelting, leaching, and
electrolysis. It is used in the plating, electrical, plumbing,
and heating equipment industries, as well as in insecticides and
fungicides. In the canmaking subcategory of the coil coating
industry copper can be attributed to various contaminant sources.
Traces of copper are found in all forms of plant and animal life,
and the metal is an essential trace element for nutrition.
Copper is not considered to be a cumulative systemic poison for
humans because it is readily excreted by the body, but it can
cause symptoms of gastroenteritis, with nausea and intestinal
irritations, at relatively low dosages. The limiting factor in
domestic water supplies is taste. To prevent this adverse
organoleptic effect of copper in water, a criterion of 1 mg/1 has
been established.
The toxicity of copper to aquatic organisms varies significantly,
not only with the species, but also with the physical and
chemical characteristics of the water, including temperature,
hardness, turbidity, and carbon dioxide content. In hard water,
the toxicity of copper salts may be reduced by the precipitation
of copper carbonate or other insoluble compounds. The sulfates
of copper and zinc, and of copper and calcium are synergistic in
their toxic effect on fish.
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Relatively high concentrations of copper may be tolerated by
adult fish for short periods of time; the critical effect of
copper appears to be its higher toxicity to young or juvenile
fish. Concentrations of 0.02 to 0.031 mg/1 have proved fatal to
some common fish species. In general the salmonoids are very
sensitive and the sunfishes are less sensitive to copper.
The recommended criterion to protect saltwater aquatic life is
0.004 mg/1 as a 24-hour average, and 0.023 mg/1 maximum
concentration.
Copper salts cause undesirable color reactions in the food
industry and cause pitting when deposited on some other metals
such as aluminum and galvanized steel.
Irrigation water containing more than minute quantities of copper
can be detrimental to certain crops. Copper appears in all
soils, and its concentration ranges from 10 to 80 ppm. In soils,
copper occurs in association with hydrous oxides of manganese and
iron, and also as soluble and insoluble complexes with organic
matter. Copper is essential to the life of plants, and the
normal range of concentration in plant tissue is from 5 to
20 ppm. Copper concentrations in plants normally do not build up
to high levels when toxicity occurs. For example, the
concentrations of copper in snapbean leaves and pods was less
than 50 and 20 mg/kg, respectively, under conditions of severe
copper toxicity. Even under conditions of copper toxicity, most
of the excess copper accumulates in the roots; very little is
moved to the aerial part of the plant.
Copper is not destroyed when treated by a POTW, and will either
pass through to the POTW effluent or be retained in the POTW
sludge. It can interfere with the POTW treatment processes and
can limit the usefulness of municipal sludge.
The influent concentration of copper to POTW facilities has been
observed by the EPA to range from 0.01 to 1.97 mg/1, with a
median concentration of 0.12 mg/1. The copper that is removed
from the influent stream of a POTW is adsorbed on the sludge or
appears in the sludge as the hydroxide of the metal. Bench scale
pilot studies have shown that from about 25 percent to 75 percent
of the copper passing through the activated sludge process
remains in solution in the final effluent. Four-hour slug
dosages of copper sulfate in concentrations exceeding 50 mg/1
were reported to have severe effects oh the removal efficiency of
an unacclimated system, with the system returning to normal in
about 100 hours. Slug dosages of copper in the form of copper
cyanide were observed to have much more severe effects on the
activated sludge system, but the total system returned to normal
in 24 hours.
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In a recent study of 268 POTW, the median pass-through was over
80 percent for primary plants and 40 to 50 percent for trickling
filter, activated sludge, and biological treatment plants. POTW
effluent concentrations of copper ranged from 0.003 to 1.8 mg/1
(mean 0.126, standard deviation 0.242).
Copper which does not pass through the POTW will be retained in
the sludge where it will build up in concentration. The presence
of excessive levels of copper in sludge may limit its use on
cropland. Sewage sludge contains up to 16,000 mg/kg of copper,
with 730 mg/kg as the mean value. These concentrations are
significantly greater than those normally found in soil, which
usually range from 18 to 80 mg/kg. Experimental data indicate
that when dried sludge is spread over tillable land, the copper
tends to remain in place down to the depth of tillage, except for
copper which is taken up by plants grown in the soil. Recent
investigation has shown that the extractable copper content of
sludge-treated soil decreased with time, which suggests a
reversion of copper to less soluble forms was occurring.
Gyanide(121).
Cyanides are among the most toxic of pollutants commonly observed
in industrial wastewaters. Introduction of cyanide into
industrial processes is usually by dissolution of potassium
cyanide (KCN) or sodium cyanide (NaCN) in process waters;
however, the hydrogen cyanide (HCN) formed when the above salts
are dissolved in water is probably the most acutely lethal
compound.
The relationslhip of pH to hydrogen cyanide formation is very
important. As pH decreases below 7, more than 99 percent of the
cyanide is present as HCN and less than 1 percent as cyanide
ions. Thus, at neutral pH, that of most living organisms, the
more toxic form of cyanide prevails.
Cyanide ions combine with numerous heavy metal ions to form
complexes. The complexes are in equilibrium with HCN. Thus, the
stability of the metal-cyanide complex and the pH determine the
concentration of HCN. Stability of the metal-cyanide anion
complexes is extremely variable. Those formed with zinc, copper,
and cadmium are not stable - they rapidly dissociate, with
production of HCN, in near neutral or acid waters. Some of the
complexes are extremely stable. Cobaltocyanide is very resistant
to acid distillation in the laboratory. Iron cyanide complexes
are also stable, but undergo photodecomposition to give HCN upon
exposure to sunlight. Synergistic effects have been demonstrated
for the metal cyanide complexes making zinc, copper, and cadmium
cyanides more toxic than an equal concentration of sodium
cyanide.
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The toxic mechanism of cyanide is essentially an inhibition of
oxygen metabolism, i.e., rendering the tissues incapable of
exchanging oxygen. The cyanogen compounds are true noncumulative
protoplasmic poisons. They arrest the activity of all forms of
animal life. Cyanide shows a very specific type of toxic action.
It inhibits the cytochrome oxidase system. This system is the
one which facilitates electron transfer from reduced metabolites
to molecular oxygen. The human body can convert cyanide to a
non-toxic thiocyanate and eliminate it. However, if the quantity
of cyanide ingested is too great at one time, the inhibition of
oxygen utilization proves fatal before the detoxifying reaction
reduces the cyanide concentration to a safe level.
Cyanides are more toxic to fish than to lower forms of aquatic
organisms such as midge larvae, crustaceans, and mussels.
Toxicity to fish is a function of chemical form and con-
centration, and is influenced by the rate of metabolism
(temperature), the level of dissolved oxygen, and pH. In
laboratory studies free cyanide concentrations ranging from 0.05
to 0.15 mg/1 have been proven to be fatal to sensitive fish
species including trout, bluegill, and fathead minnows. Levels
above 0.2 mg/1 are rapidly fatal to most fish species. Long term
sublethal concentrations of cyanide as low as 0.01 mg/1 have been
shown to affect the ability of fish to function normally, e.g.,
reproduce, grow, and swim.
For the protection of human health from the toxic properties of
cyanide ingested through water and through contaminated aquatic
organisms, the ambient water quality criterion is determined to
be 0.200 mg/1.
Persistance of cyanide in water is highly variable and depends
upon the chemical form of cyanide in the water, the concentration
of cyanide, and the nature of other constituents. Cyanide may be
destroyed by strong oxidizing agents such as permanganate and
chlorine. Chlorine is commonly used to oxidize strong cyanide
solutions. Carbon dioxide and nitrogen are the products of
complete oxidation. But if the reaction is not complete, the
very toxic compound; cyanogen chloride may remain in the
treatment system and subsequently be released to the environment.
Partial chlorination may occur as part of a POTW treatment, or
during the disinfection treatment of surface water for drinking
water preparation.
Cyanides can interfere with treatment processes in POTW, or pass
through to ambient waters. At low concentrations and with
acclimated microflora, cyanide may be decomposed by
microorganisms in anaerobic and aerobic environments or waste
treatment systems. However, data indicate that much of the
cyanide introduced passes through to the POTW effluent. The mean
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pass-through of 14 biological plants was 71 percent. In a recent
study of 41 POTW, the effluent concentrations ranged from 0.002
to 100 mg/1 (mean. - 2.518, standard deviation = 15.6). Cyanide
also enhances the toxicity of metals commonly found in POTW
effluents, including the priority pollutants cadmium, zinc, and
copper.
Data for Grand Rapids, Michigan, showed a significant decline in
cyanide concentrations downstream from the POTW after pretreat-
ment regulations were put in force. Concentrations fell from
0.66 mg/1 before, to 0.01 mg/1 after pretreatment was required.
Lead (122). Lead is a soft, malleable ductible, bluish-gray,
metallic element, usually obtained from the mineral galena (lead
sulfide, PbS)i, anglesite (lead sulfate, PbS04), or cerussite
(lead carbonate, PbCO3). Because it is usually associated with
the minerals zinc, silver, copper, gold, cadmium, antimony, and
arsenic, special purification methods are frequently used before
and after extraction of the metal from the ore concentrate by
smelting.
Lead is widely used for its corrosion resistance, sound and
vibration absorption, low melting point (solders), and relatively
high imperviousness to various forms of radiation. Small amounts
of copper, antimony and other metals can be alloyed with lead to
achieve greater hardness, stiffness, or corrosion resistance than
is afforded by the pure metal. Lead compounds are used in glazes
and paints. About one third of U.S. lead consumption goes into
storage batteries. About half of U.S. lead consumption is from
secondary lead recovery. U.S. consumption of lead is in the
range of one million tons annually.
Lead ingested by humans produces a variety of toxic effects
including impaired reproductive ability/ disturbances in blood
chemistry, neurological disorders, kidney damage, and adverse
cardiovascular effects. Exposure to lead in the diet results in
permanent increase in lead levels in the body. Most of the lead
entering the body eventually becomes localized in the b.ones where
it accumulates. Lead is a carcinogen or cocarcinogen in some
species of experimental animals. Lead is teratogenic in
experimental animals. Mutangenicity data are not available for
lead.
For the protection of human health from the toxic properties of
lead ingested through water and through contaminated aquatic
organisms, the ambient water criterion is 0.050 mg/1.
Lead is not destroyed in POTW, but is passed through to the
effluent or retained in the POTW sludge; it can interfere with
POTW treatment processes and can limit the usefulness of POTW
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sludge for application to agricultural croplands. Threshold
concentration for inhibition of the activated sludge process is
0.1 mg/1, and for the nitrification process is 0.5 mg/1. In a
study of 214 POTW, median pass through values were over 80
percent for primary plants and over 60 percent for trickling
filter, activated sludge, and biological process plants. Lead
concentration in POTW effluents ranged from 0.003 to 1.8 mg/1
(means = 0.106 mg/1, standard deviation = 0.222).
Application of lead-containing sludge to cropland should not lead
to uptake by crops under most conditions because normally lead is
strongly bound by soil. However, under the unusual conditions of
low pH (less than 5.5) and low concentrations of labile
phosphorus, lead solubility is increased and plants can
accumulate lead.
Mercury (123). Mercury is an elemental metal rarely found in
nature as the free metal. Mercury is unique among metals as it
remains a liquid down to about 39 degrees below zero. It is
relatively inert chemically and is insoluble in water. The
principal ore is cinnabar (HgS).
Mercury is used industrially as the metal and as mercurous and
mercuric salts and compounds. Mercury is used in several types
of batteries. Mercury released to the aqueous environment is
subject to biomethylation - conversion to the extremely toxic
methyl mercury.
Mercury can be introduced into the body through the skin and the
respiratory system as the elemental vapor. Mercuric slats are
highly toxic to humans and can be absorbed through the
gastro-intestinal tract. Fatal does can vary from 1 to 30 grams.
Chronic toxicity of methyl mercury is evidenced primarily by
neurological symptoms. Some mercuric salts cuase death by kidney
failure.
Mercuric salts are extremely toxic to fish and other aquatic
life. Mercuric chloride is more lethal than copper, hexavalent
chromiun, zinc, nickel, and lead towards fish and aquatic life.
In the food cycle, algae containing mercury up to 100 times the
concnetration in the surrouding sea water are eaten by fish which
further concentrate the mercury. Predators that eat the fish in
turn concentrate the mercury even further.
For the protection of human health from the toxic properties of
mercury ingested through water and through contaminated aquatic
organisms the ambient water criterion is determined to be 0.0002
mg/1.
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Mercury is not destroyed when treated by a POTW, and will either
pass through to the POTW effluent or be incorporated into the!
POTW sludge, at low concentrations it may reduce POTW removal
efficiencies, and at high concentrations it may upset the POTW
operation.
The influent concentrations of mercury to a POTW have been
observed by the EPA to range from 0.002 to 0.24 mg/1, with a
median concentration of 0.001 mg/1. Mercury has been reported in
the literature to have inhibiting effects upon an activated
sludge POTW at levels as low as 0.1 mg/1. At 5 mg/1 of mercury,
losses of COD removal efficiency of 14 to 40 percent have been
reported, while at 10 mg/1 loss of removal of 59 percent has been
reported. Upset of an activated sludge POTW is reported in the
literature to occur near 2QO mg/1. The anaerobic digestion
process is much less affected by the presence of mercury, with
inhibitory effects being reported at 1,365 mg/1.
In a study of 22 POTW facilities having secondary treatment, the
range of removal of mercury from the influent to the POTW ranged
from 4 to 99 percent with median removal of 41 percent. THus
significant pass through of mercury may occur.
In sludges, mercury content may be high if industrial sources of
mercury contamination are present. Little is known about the
form in which mercury occurs in sludge. Mercury may undergo
biological methylation in sediments, but no methylation has been
observed in soils, mud, or sewage sludge.
The mercury content of soils not receiving additions of POTW
sewage sludge lie in the range from 0.01 to 0.5 mg/kg. In soils
receiving POTW sludges for protracted periods, the concentration
of mercury has been observed to approach 1.0 mg/kg. In the soil,
mercury enters into reactions with the exchange complex of clay
and organic fractions, forming both ionic and covalent bonds.
CHemical and microbiological degradation of mercurials can take
place side by side in the soil, and the products - ionic or
molecular - are retained by organic matter and clay or may be
volatilized if gaseous. Because of the high affinity between
mercury and the solid soil surfaces, mercury persists in the
upper layer of the soil.
Mercury can enter plants through the roots, it can readily move
to other parts of the plant, and it has been reported to cuase
injury to plants. In many plants mercury concentrations range
from 0.01 to 0.20 mg/kg, but when plants are supplied with high
levels of mercury, these concentrations can exceed 0.5 mg/kg.
Bioconcnetration occurs in animals ingesting mercury in food.
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Nickel(124). Nickel is seldom found in nature as the pure
elemental metal. It is a reltively plentiful element and is
widely distributed throughout the earth's crust. It occurs in
marine organisms and is found in the oceans. The chief
commercial ores for nickel are pentlandite [(Fe,Ni)9SB], and a
lateritic ore consisting of hydrated nickel-iron-magnesium
silicate.
Nickel has many and varied uses. It is used in alloys and as the
pure metal. Nickel salts are used for electroplating baths. The
coil coating industry uses nickel compounds as accelerators in
certain conversion coating solutions. Nickel is also found as a
contaminant in mineral acids.
The toxicity of nickel to man is thought to be very low, and
systemic poisoning of human beings by nickel or nickel salts is
almost unknown. In non-human mammals nickel acts to inhibit
insulin release, depress growth, and reduce cholesterol. A high
incidence of cancer of the lung and nose has been reported in
humans engaged in the refining of nickel.
Nickel salts can kill fish at very low concentrations. However,
nickel has been found to be less toxic to some fish than copper,
zinc, and iron. Nickel is present in coastal and open ocean
water at concentrations in the range of 0.0001 to 0.006 mg/1
although the most common values are 0.002 - 0.003 mg/1. Marine
animals contain up to 0.4 mg/1 and marine plants contain up to
3 mg/1. Higher nickel concentrations have been reported to cause
reduction in photosynthetic activity of the giant kelp. A low
concentration was found to kill oyster eggs.
For the protection of human health based on the toxic properties
of nickel ingested through water and through contaminated aquatic
organisms, the ambient water criterion is determined to be 0.0134
mg/1.
Nickel is not destroyed when treated in a POTW, but will either
pass through to the POTW effluent or be retained in the POTW
sludge. It can interfere with POTW treatment processes and can
also limit the usefulness of municipal sludge.
Nickel salts have caused inhibition of the biochemical oxidation
of sewage in a POTW. In a pilot plant, slug doses of nickel
significantly reduced normal treatment efficiencies for a few
hours, but the plant acclimated itself somewhat to the slug
dosage and appeared to achieve normal treatment efficiencies
within 40 hours. It has been reported that the anaerobic
digestion process is inhibited only by high concentrations of
nickel, while a low concentration of nickel inhibits the
nitrification process.
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EPA has observed influent concentration of nickel to POTW
facilities ranging from 0.01 to 3.19 mg/1, with a median of
0.33 mg/1. In a study of 190 POTW, nickel pass-through was
greater, them 90, percent for 82 percent of the primary plants.
Median pass-through for trickling filter, activated sludge, and
biological process plants was greater than 80 percent. POTW
effuent concentrations ranged from 0.002 to 40 mg/1
{mean = 0.410, standard deviation = 3.279).
Nickel not passed through the POTW will be incorporated into the
sludge. In a recent two-year study of eight cities, four of the
cities had median nickel concentrations of over 350 mg/kg, and
two were over 1,000 mg/kg. The maximum nickel concentration
observed was 4,010 mg/kg.
Nickel is found in nearly all soils,' plants, and waters. Nickel
has no known essential function in plants. In soils, nickel
typically is found in the range from 10 to 100 mg/kg. Various
environmental exposures to nickel appear to correlate with
increased incidence of tumors in man. For example, cancer in the
maxillary antrum of snuff users may result from using plant
material grown on soil high in nickel.
Nickel toxicity may develop in plants from application of sewage
sludge on acid soils. Nickel has reduced yields for a variety of
crops, including oats, mustard, turnips, and cabbage. In one
study, nickel decreased the yields of oats significantly at 100
mg/kg.
Whether nickel exerts a toxic effect on plants depends on several
soil factors, the amount of nickel applied, and the contents of
other metals in the sludge. Unlike copper and zinc, which are
more available from inorganic sources than from sludge, nickel
uptake by plants seems to be promoted by the presence of the
organic matter in sludge. Soil treatments such as liming reduce
the solubility of nickel. Toxicity of nickel to plants is
enhanced in acidic soils.
Zinc(128). Zinc occurs abundantly in the earth's crust,
concentrated in ores. It is readily refined into the pure,
stable, silvery-white metal. In addition to its use in alloys,
zinc is used as a protective coating on steel. It is applied by
hot dipping (i.e. dipping the steel in molten zinc) or by
electroplating.
Zinc can have an adverse effect on man and animals at high con-
centrations. Zinc at concentrations in excess of 5 mg/1 causes
an undesirable taste which persists through conventional
treatment. For the prevention of adverse effects due to these
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organoleptic properties of
ambient water criterion.
zinc, 5 mg/1 was adopted for the
Toxic concentrations of zinc compounds cause adverse changes in
the morphology and physiology of fish. Lethal concentrations in
the range of 0.1 mg/1 have been reported. Acutely toxic
concentrations induce cellular breakdown of the gills, and
possibly the clogging of the gills with mucous. Chronically
toxic concentrations of zinc compounds cause general enfeeblement
and widespread histological changes to many organs, but not to
gills. Abnormal swimming behavior has been reported at
0.04 mg/1. Growth and maturation are retarded by zinc. It has
been observed that the effects of zinc poisoning may not become
apparent immediately, so that fish removed from zinc-contaminated
water may die as long as 48 hours after removal.
In general, salmonoids are most sensitive to elemental zinc in
soft water; the rainbow trout is the most sensitive in hard
waters. A complex relationship exists between zinc
concentration, dissolved zinc concentration, pH, temperature, and
calcium and magnesium concentration. Prediction of harmful
effects has been less than reliable and controlled studies have
not been extensively documented.
The major concern with zinc compounds in marine waters is not
with acute lethal effects, but rather with the long-term
sublethal effects of the metallic compounds and complexers. Zinc
accumulates in some marine species, and marine animals contain
zinc in the range of 6 to 1500 mg/kg. From the point of view of
acute lethal effects, invertebrate marine animals seem to be the
most sensitive organism tested.
Toxicities of zinc in nutrient solutions have been demonstrated
for a number of plants. A variety of fresh water plants tested
manifested harmful symptoms at concentrations of 10 mg/1. Zinc
sulfate has also been found to be lethal to many plants and it
could impair agricultural uses of the water.
Zinc is not destroyed when treated by POTW, but will either pass
through to the POTW effluent or be retained in the POTW sludge.
It can interfere with treatment processes in the POTW and can
also limit the usefuleness of municipal sludge.
In slug doses, and particularly in the presence of copper,
dissolved zinc can interfere with or seriously disrupt the
operation of POTW biological processes by reducing overall
removal efficiencies, largely as a result of the toxicity of the
metal to biological organisms. However, zinc solids in the form
of hydroxides or sulfides do not appear to interfere with
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biological treatment processes, on the basis of available data.
Such solids accumulate in the sludge.
The influent concentrations of zinc to POTW facilities has been
observed by the EPA to range from 0.017 to 3.91 mg/1, with a
median concentration of 0.33 mg/1. Primary treatment is not
efficient in removing zinc; however, the microbial floe of
secondary treatment readily adsorbs zinc.
In a study of 258 POTW, the median pass-through values were 70 to
88 percent for primary plants, 50 to 60 percent for trickling
filter and biological process plants, and 30-40 percent for
activated process plants. POTW effluent concentrations of zinc
ranged from 0.003 to 3.6 mg/1 (mean = 0.330, standard deviation =
0.464).
The zinc which does not pass through the POTW is retained in the
sludge. The presence of zinc in sludge may limit its use on
cropland. Sewage sludge contains from 72 to over 30,000 mg/kg of
zinc, with 3,366 mg/kg as the mean value. These concentrations
are significantly greater than those normally found in soil,
which range from 0 to 195 mg/kg, with 94 mg/kg being a common
level. Therefore, application of sewage sludge to soil will
generally increase the concentration of zinc in the soil. Zinc
can be toxic to plants, depending upon soil pH. Lettuce,
tomatoes, turnips, mustard, kale, and beets are especially
sensitive to zinc contamination.
Aluminum. Aluminum is a non-conventional pollutant. It is a
silvery white metal, very abundant in the earth's crust (8.1%),
but never found free in nature. Its principal ore is bauxite.
Aluminum is produced by electrolysis of this melt. Alumina
(A1203) is extracted from the bauxite and dissolved in molten
cryolite.
Aluminum is light, malleable, ductile, possesses high thermal and
electrical conductivity, and is non-magnetic. It can be formed,
machined or cast. Aluminum is used in the construction,
transportation, and container industries and competes with iron
and steel in these markets.
Aluminum has been found to be toxic to freshwater and marine
aquatic life. In freshwaters acute toxicity and solubility
increases as pH levels increase above pH 7. This relationship
also appears to be true as the pH levels decrease below pH 7.
Chronic effects of aluminum on aquatic life have also been
documented. Aluminum has been found to be toxic to certain
plants. A water quality standard for aluminum was established
(U.S. Federal Water Pollution Control Administration, 1968) for
interstate agricultural and irrigation waters, which set a trace
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element tolerance at 1 mg/1 for continuous use on all soils and
20 mg/1 for short term use on fine-textured soils.
Aluminum and some of its compounds used in food preparation and
as food additives are generally recognized as safe and are
sanctioned by the Food and Drug Administration. No limits on
aluminum content in food and beverage products have been
established.
There are no reported adverse physiological effects on man from
low concentrations of aluminum in drinking water, however, large
concentrations of aluminum in the human body are alleged to cause
changes in behavior. Salts of aluminum are used as coagulants in
water treatment, and in limited quantities do not have any
adverse effects on POTW operations. Some aluminum salts are
soluble, however, mildly alkaline conditions cause precipitation
of aluminum as hydroxide. The precipitation of aluminum
hydroxide can have an adverse effect on rooted aquatics and
invertebrate benthos.
Fluoride. Fluoride is a traditional pollutant. Fluoride is the
anionic form of fluorine a highly reactive gas which exists in
the elemental state only under carefully controlled conditions.
Hydrofluoric acid is commonly used as an etchant to provide
proper surface texture for application of other materials.
Although fluoride is not listed as a priority pollutant, it can
be toxic to livestock and plants, and can cause tooth mottling in
humans. The National Academy of Sciences recommends: (1) two
milligrams per liter as an upper limit for watering livestock
and, (2) one milligram per liter for continuous use as irrigation
water on acid soils to prevent plant toxicity and reduced crop
yield. Although some fluoride in drinking water helps to prevent
tooth decay, EPA's National Interim Primary Drinking Water
Regulations set limitations of 1.4 to 2.4 milligrams per liter in
drinking water to protect against tooth moiling.
Phenols(Total). Total phenols is the result of analysis using
the4-AAP (4-aminoantipyrene) method. This analytical procedure
measures the color development'of reaction products between 4-AAP
and some phenols. The results are reported as phenol. Thus
"total phenol" is not total phenols because many phenols (notably
nitrophenols) do not react. Also, since each reacting phenol
contributes to the color development to a different, degree, and
each phenol has a molecular weight different from others and from
phenol .itself, analyzes of several mixtures containing the same
total concentration in mg/1 of several phenols will give
different numbers depending on the proportions in the particular
mixture.
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Despite these limitations of the analytical method, total phenols
is a 'useful parameter when the mix of phenols is relatively
constant and an inexpensive monitoring method is desired. In any
given plant or even in an industry subcategory, monitoring of
"total phenols" provides an indication of the concentration of
this group of priority pollutants as well as those phenols not
selected as priority pollutants. A further advantage is that the
method is widely used in water quality determinations.
In an EPA survey of 103 POTW the concentration of "total phenols"
ranged from 0.0001 mg/1 to 0.176 mg/1 in the influent, with a
median concentration of 0.016 mg/1. Analysis of effluents from
22 of these same POTW which had biological treatment meeting
secondary treatment performance levels showed "total phenols"
concentrations ranging from 0 mg/1 to 0.203 mg/1 with a median of
0.007. Removals were 64 to 100 percent, with a median of 78
percent.
It must be recognized, however, that six of the eleven priority
pollutant phenols could be present in high concentrations and not
be detected. Conversely, it is possible, but not probable, to
have a high "total phenol" concentration without any phenol
itself or any of the ten other priority pollutant phenols
present. A characterization of the phenol mixture to be
monitored to establish constancy of composition will allow "total
phenols" to be used with confidence.
Phosphorus. Phosphorus, a traditional pollutant, is a general
term used to designate the various anions containing pentavalent
phosphorus and oxygen - orthophosphate [(PO4)~3], metaphosphate
[(P03)~], pyrophosphate [(P207-*], hypophosphate [(PZ0«)~*]. The
element phosphorus exists in several allotropic forms - red,
white or yellow, and black. White phosphorus reacts with oxygen
in air, igniting spontaneously. It is not found free in nature,
but is widely distributed in nature. • The most important
commercial sources of phosphate are the apatites [3Ca3(P04)2«CaFa
and 3Ca3(P04)2«CaCl2]. Phosphates also occur in bone and other
tissue. Phosphates are essential for plant and animal life.
Several millions of tons of phosphates are mined and converted
for use each year in the U.S. The major form produced is
phosphoric acid. The acid is then used to produce other
phosphate chemicals.
The largest use for phosphates is fertilizer. Most of the U.S.
production of phosphoric acid goes into that application.
Phosphates are used in cleaning preparations for household and
industrial applications and as corrosion inhibitors in boiler
feed water and cooling towers.
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Phosphates are not controlled because of toxic effects on man.
Phosphates are controlled because they promote growth of algae
and other plant life in aquatic environments. Such growth first
becomes unsightly; if it flourishes, it eventually dies and adds
to the BOD. The result can be a dead body of water. No
standards or criteria appear to have been established for U.S.
surface waters.
Phosphorus is one of the concerns of any POTW, because phosphates
are introduced into domestic wastewaters from human body wastes
and food wastes as well as household detergents. About ten
percent of the phosphorus entering POTW is insoluble and is
removed by primary settling. Biological treatment removes very
little of the remaining phosphate. Removal is accomplished by
forming an insoluble precipitate which will settle out. Alum,
lime, and ferric chloride or sulfate are commonly used for this
purpose. The point of addition of chemicals for phosphate
removal requires careful evaluation because pH adjustment may be
required, and material and capital costs differ with different
removal schemes. The phosphate content of the effluent also
varies according to the scheme used. There is concern about the
effect of phosphate contained in sludge used for soil amendment.
Phosphate is a principal ingredient of fertilizers.
Oil and Grease. Oil and grease are taken together as one
pollutant parameter. This is a conventional pollutant and some
of its components are:
1. Light Hydrocarbons - These include light fuels such as
gasoline, kerosene, and jet fuel, and miscellaneous solvents
used for industrial processing, degreasing, or cleaning
purposes. The presence of these light hydrocarbons may make
the removal of other heavier oil wastes more difficult.
2.
3.
4.
Heavy Hydrocarbons, Fuels, and Tars - These include the
crude oils, diesel oils, #6 fuel oil, residual oils, slop
oils, and in some cases, asphalt and road tar.
Lubricants and Cutting Fluids - These generally fall into
two classes: non-emulsifiable oils such as lubricating oils
and greases and emulsifiable oils such as water soluble
oils, rolling oils, cutting oils, and drawing compounds.
Emulsifiable oils may contain fat, soap or various other
additives.
Vegetable and Animal Fats and Oils - These originate
primarily from processing of foods and natural products.
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These compounds can settle or float and may exist as solids or
liquids depending upon factors such as method of use, production
process, and temperature of wastewater.
Even small quantities of oils and grease cause troublesome taste
and odor problems. Scum lines from these agents are produced on
water treatment basin walls and other containers. Fish and water
fowl are adversely affected by oils in their habitat. Oil
emulsions may adhere to the gills of fish, causing suffocation,
and the flesh of fish is tainted when microorganisms that were
exposed to waste oil are eaten. Deposition of oil in the bottom
sediments of water can serve to inhibit normal benthic growth.
Oil and grease exhibit an oxygen demand.
Many of the organic priority pollutants will be found distributed
between the oily phase and the aqueous phase in industrial
wastewaters. The presence of phenols, PCBs, PAHs, and almost any
other organic pollutant in the oil and grease make
characterization of this parameter almost impossible. However,
all of these other organics add to the objectionable nature of
the oil and grease.
Levels of oil and grease which are toxic to aquatic organisms
vary greatly, depending on the type and the species
susceptibility. However, it has been reported that crude oil in
concentrations as low as 0.3 mg/1 is extremely toxic to fresh-
water fish. It has been recommended that public water supply
sources be essentially free from oil and grease.
Oil and grease in quantities of 100 1/sq km show up as a sheen on
the surface of a body of water. The presence of oil slicks
decreases the aesthetic value of a waterway.
Oil and grease is compatible with a POTW activated sludge process
in limited quantity. However, slug loadings or high
concentrations of oil and grease interfere with biological
treatment processes. The oils coat surfaces and solid particles,
preventing access of oxygen, and sealing in some microorganisms.
Land spreading of POTW sludge containing oil and grease
uncontaminated by toxic pollutants is not expected to affect
crops grown on the treated land, or animals eating those crops.
pH. Although not a specific pollutant, pH is related to the
acidity or alkalinity of a wastewater stream. It is not,
however, a measure of either. The term pH is used to describe
the hydrogen ion concentration (or activity) present in a given
solution. Values for pH range from 0 to 14, and these numbers
are the negative logarithms of the hydrogen ion concentrations.
A pH of 7 indicates neutrality. Solutions with a pH above 7 are
alkaline, while those solutions with a pH below 7 are acidic.
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The relationship of pH and acidity and alkalinity is not
necessarily linear or direct. Knowledge of the water pH is
useful in determining necessary measures for corrosion control,
sanitation, and disinfection. Its value is also necessary in the
treatment of industrial wastewaters to determine amounts of
chemicals required to remove pollutants and to measure their
effectiveness. Removal of pollutants, especially dissolved
solids, is affected by the pH of the wastewater.
Waters with a pH below 6.0 are corrosive to water works
structures, distribution lines, and household plumbing fixtures
and can thus add constituents to drinking water such as iron,
copper, zinc, cadmium, and lead. The hydrogen ion concentration
can affect the taste of the water and at a low pH, water tastes
sour. The bactericidal effect of chlorine is weakened as the pH
increases, and it is advantageous to keep the pH close to 7.0.
This is significant for providing safe drinking water.
Extremes of pH or rapid pH changes can exert stress conditions or
kill aquatic life outright. Even moderate changes from
acceptable criteria limits of pH are deleterious to some species.
The relative toxicity to aquatic life of many materials is
increased by changes in the water pH. For example,
metallocyanide complexes can increase a thousand-fold in toxicity
with a drop of 1.5 pH units.
Because of the universal nature of pH and its effect on water
quality and treatment, it is selected as a pollutant parameter
for all subcategories in the coil coating industry. A neutral pH
range (approximately 6-9) is generally desired because either
extreme beyond this range has a deleterious effect on receiving
waters or the pollutant nature of other wastewater constituents.
Pretreatment for regulation of pH is covered by the "General
Pretreatment Regulations for Existing and New Sources of
Pollution," 40 CFR 403.5. This section prohibits the discharge
to a POTW of "pollutants which will cause corrosive structural
damage to the POTW but in no case discharges with pH lower than
5.0 unless the works is specially designed to accommodate such
discharges."
Total Suspended Solids(TSS). Suspended solids include both
organic and inorganic materials. The inorganic compounds include
sand, silt, and clay. The organic fraction includes such
materials as grease, oil, tar, and animal and vegetable waste
products. These solids may settle out rapidly, and bottom
deposits are often a mixture of both organic and inorganic
solids. Solids may be suspended in water for a time and then
settle to the bed of the stream or lake. These solids discharged
with man's wastes may be inert, slowly biodegradable materials,
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or rapidly decomposable substances. While in suspension,
suspended solids increase the turbidity of the water, reduce
light penetration, and impair the photosynthetic activity of
aquatic plants.
Supended solids in water interfere with many industrial processes
and cause foaming in boilers and incrustations on equipment
exposed to such water, especially as the temperature rises. They
are undesirable in process water used in the manufacture of
steel, in the textile industry, in laundries, in dyeing, and in
cooling systems.
Solids in suspension are aesthetically displeasing. When they
settle to form sludge deposits on the stream or lake bed, they
are often damaging to the life in the water. Solids, when
transformed to sludge deposit, may do a variety of damaging
things, including blanketing the stream or lake bed and thereby
destroying the living spaces for those benthic organisms that
would otherwise occupy the habitat. Organic solids use a portion
or all of the dissolved oxygen available in the area. Organic
materials also serve as a food source for sludgeworms and
associated organisms.
Disregarding any toxic effect attributable to substances leached
out by water, suspended solids may kill fish and shellfish by
causing abrasive injuries and by clogging the gills and
respiratory passages of various aquatic fauna. Indirectly,
suspended solids are inimical to aquatic life because they screen
out light, and they promote and maintain the development of
noxious conditions through oxygen depletion. This results in the
killing of fish and fish food organisms. Suspended solids also
reduce the recreational value of the water.
Total suspended solids is a traditional pollutant which is
compatible with a well-run POTW. With the exception of those
components which are described elsewhere in this section, e.g.,
toxic metal components, this pollutant does not interfere with
the operation of a POTW; however, since a considerable portion of
the innocuous TSS may be inseparably bound to the constituents
which do interfere with POTW operation, or produce unusable
sludge, or subsequently dissolve to produce unacceptable POTW
effluent, TSS may be considered a toxic waste hazard.
SPECIFIC POLLUTANTS CONSIDERED FOR REGULATION
Discussion of individual pollutant parameters selected or not
selected for consideration for specific regulation is based on
concentrations obtained from sampling and analysis of raw
wastewater streams.
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Canmaking
Pollutant Parameters Considered for Specific Regulation. Based
on sampling results and a careful examination of the canmaking
subcategory manufacturing processes and raw materials, 16
pollutant parameters were selected for consideration for specific
regulation in effluent limitations and standards for this
subcategory. The 16 are: 1,1,1-trichloroethane,
1,1-dichloroethylene, methylene chloride, bis(2-ethylhexy)
phthalate, butyl benzyl phthalate, di-n-butyl phthalate, toluene,
chromium (total), zinc, aluminum, fluoride, phenols (total),
phosphorus, oil and grease, pH, and total suspended solids.
These pollutant parameters were found at treatable levels in raw
wastewater from processes in this subcategory and are amenable to
control by identified wastewater treatment practices.
The seven organic compounds listed above were found at maximum
concentrations ranging from 0.022 mg/1 to 4.10 mg/1. A total of
25 quantifiable concentrations was found out of a total of 63
analyzed samples. Toxic organics are found in some of the oils
used on coil stock supplied to canmakers. The concentrations
reported can be reduced with specific treatment methods.
Therefore, total toxic organics are considered for regulation in
the subcategory.
Chromium was detected in 15 of 15 samples of raw wastewater from
this subcategory. The maximum concentration was 5.41 mg/1.
Chromium compounds are used in surface treatment formulations in
some canwashers. More then one-third of the concentration are
greater than those that can be achieved with specific treatment
methods. Therefore, chromium is considered for specific
regulation in this subcategory.
Zinc was detected in 15 of 15 samples of raw wastewater from this
subcategory. The maximum concentration was 4.647 mg/1. Zinc is
an alloying element in aluminum coil stock used for canmaking.
Some of the zinc concentrations are greater than those that can
be achieved with specific treatment methods. Therefore, zinc is
considered for specific regulation in this subcategory.
Aluminum was detected in all nine of the samples of raw
wastewater analyzed. The maximum concentration was 370 mg/1.
Aluminum is the primary constituent of aluminum can coil stock.
All nine of the concentrations are greater than those that can be
achieved with specific treatment methods. Therefore, aluminum is
considered for specific regulation in this subcategory.
Fluoride was detected in all six samples of raw wastewater
analyzed. The maximum concentration was 18.02 mg/1. Fluoride
ions result from the hydrofluoric acid used in the acid cleaning
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stage of the canwasher and sometimes in surface treating
compositions. The average of all six fluoride concentrations is
greater than the long-term average that can be achieved with
specific treatment methods. In addition, because of the almost
universal use of this material in canmakers and the human health
effects of concentrations well below the treatable levels
fluoride is considered for 'specific regulation in this
subcategory.
Phosphorus was detected in all six samples of raw wastewater
analyzed. The maximum concentration was 12.90 mg/1. Phosphates
are used in some surface treatment compositions. The average of
all six phosphorus concentration is greater than the long-term
average that can be achieved with specific treatment methods. In
addition, because phosphates are used in many canwashers
phosphorus is considered for specific regulation in this
subcategory.
Oil and grease was detected in all 15 of the raw wastewater
samples analyzed. The maximum concentration was 45,094 mg/1.
Oils are used for lubrication and cooling of the can stock in all
seamless canmaking lines. All concentrations are greater than
those that can be achieved with specific treatment methods.
Therefore, oil and grease is considered for specific regulation
in this subcategory.
pH ranged from 1.8 to 6.2 for the six raw wastewater samples
measured. pH can be controlled within the range 7.5 to 10 with
specific treatment methods and is therefore considered for
specific regulation in this subcategory.
Total suspend solids was present in all 15 raw wastewater samples
analyzed. The maximum concentration was 3309 mg/1. Suspended
solids result from various forming and cleaning operations during
canmaking. All the concentrations are greater than those that
can be achieved with specific treatment methods. Therefore,
total suspended solids is considered for specific regulation in
this subcategory.
Pollutant Parameters Not Considered for Specific Regulation. A
total of eight pollutant parameters that were evaluated in
sampling and analysis were dropped from further consideration
from specific regulation in the canmaking subcategory. These
parameters were found to be present in raw wastewater from small,
unique sources or at levels below those usually achieved by
specific treatment methods. The eight are: bis(2-chloroethyl)
ether, arsenic, cadmium, copper, cyanide, lead, mercury, and
nickel.
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Bis(2-chlorethyl) ether was found at a quantifiable level in only
one sample of nine on which analyzes were performed. The
concentration was 0.0103 mg/1 just above the quantification
level.. Therefore,bis(2-chloroethyl) ether is not considered for
specific regulation in this subcategory.
Arsenic was detected in six of the fifteen raw wastewater samples
analyzed. The maximum concentration was 1.402 mg/1. This was
the only concentration above the levels which are considered
treatable by specific methods. Therefore, arsenic is not
considered for specific regulation in this subcategory.
Cadmium was detected in six of the fifteen raw wastewater samples
analyzed. The maximum concentration was 0.010 mg/1 which is
below the level considered treatable. Therefore, cadmium is not
considered for specific regulation in this subcategory.
Copper was detected in all fifteen raw wastewater samples
analyzed. The maximum concentration was 0.09 mg/1 which is below
the level considered treatable. Therefore, copper is not
considered for specific regulation in this subcategory.
Cyanide was detected in eleven of the fifteen raw wastewater
samples analyzed. The maximum concentration was 0.034 mg/1 which
is below the level which is considered treated by specific
methods. Therefore, cyanide is not considered for specific
regulation in this subcategory.
Lead was detected in seven of the fifteen raw wastewater samples
analyzed. The maximum concentration was 0.052 mg/1 which is
below the levels considered treatable by specific methods.
Therefore, lead is not considered for specific regulation in this
subcategory.
Mercury was detected in seven of the fifteen raw wastewater
samples analyzed. The maximum concentration was 0.001 mg/1 which
is below the levels considered treatable by specific methods.
Therefore, mercury is not considered for regulation in this
subcategory.
Nickel was detected in eight of the fifteen raw wastewater
samples analyzed. The maximum concentration was 0.49 mg/1 which
is below the levels considered treatable. Therefore, nickel is
not considered for specific regulation in this subcategory.
Summary
Table VI-1, (page 98) presents the results of selection of
priority pollutant parameters for consideration for specific
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regulation for the canmaking subcategory. The pollutants that
were not detected are indicated by ND; those detected, but not
quantifiable by NQ; those detected at small levels or from a
unique source by SU; those at levels considered not treatable by
NT; and those considered for specific regulation by REG.
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TABLE VI-1
PRIORITY POLLUTANT DISPOSITION
Pollutant
Disposition
1. Acenaphthene ND
2. Acrolein ND
3. Aerylonitrile ND
4. Benzene NQ
5. Benzidene ND
6. Carbon tetrachloride NQ
7. Chlorobenzene NQ
8. 1/2,4-Trichlorobenzene ND
9. Hexachlorobenzene ND
10. 1,2-Dichloroethane ND
11. 1,1,1-Trichloroethane REG
12. Hexachloroethane ND
13. 1,1-Dichloroethane ND
14. 1,7,2-Trichloroethane ND
15. 1,1,2,2-Tetrachloroethane ND
16. Chloroethane ND
17. Bis(chloromethyl)ether ND
18. Bis(2-Chloroethyl)ether SU
19. 2-Chloroethyl vinyl ether ND
20. 2-Chloronaphthalene ND
21. 2,4,6-Trichlorophenol ND
22. Parachlorometa cresol ND
23. Chloroform NQ
24. 2-Chlorophenol ND
25. 1,2-Dichlorobenzene ND
26. 1,3-Dichlorobenzene ND
27. 1,4-Dichlorobenzene ND
28. 3,3-Dichlorobenzidene ND
29. 1,1-Dichloroethylene REG
30. 1/2-Trans-Dichloroethylene ND
ND - NOT DETECTED
NQ - NOT QUANTIFIABLE
SU - SMALL, UNIQUE SOURCE
NT - NOT TREATABLE
REG - REGULATION CONSIDERED
Pollutant
Disposition
31. 2,4-Dichlorophenol ND
32. 1,2-Dichloropropane ND
33. 1,2-Dichloropropylene ND
34. 2,3-Dimethylphenol ND
35. 2,4-Dinitrotoluene ND
36. 2,6-Dinitrotoluene ND
37. 1,2-Diphenylhydrazine NQ
38. Ethylbenzene NQ
39. Fluoranthene ND
40. 4-Chlorophenyl phenyl ether ND
41. 4-Bromophenyl phenyl ether ND
42. Bis(2-Chloroisopropyl)ether ND
43. Bis(2-Chloroethoxy)methane ND
44. Methylene chloride REG
45. Methyl chloride ND
46. Methyl bromide ND
47. Bromoform ND
48. Dichlorobromomethane NQ
49. Trichlorofluoromethane ND
50. Dichlorodifluoromethane ND
51. Chlorodibromomethane NQ
52. Hexachlorobutadiene ND
53. Hexachlorocyclopentadiene ND
54. Isophorone ND
55. Naphthalene NQ
56. Nitrobenzene ND
57. 2-Nitrophenol ND
58. 4-Nitrophenol ND
59. 2,4-Dinitrophenol ND
60. 4,6-Dinitro-o-cresol ND
61. N-Nitrosodimethylamine ND
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TABLE VI-1 (Continued)
PRIORITY POLLUTANT DISPOSITION
Pollutant
Disposition
Pollutant
62. N-Nitrosodiphenylamine NQ
63. N-Nitrosodi-n-propylamine ND
64. Pentachlorophenol ND
65. Phenol NQ
66. Bis(2-ethylhexyl)phthalate REG
67.'Butyl benzyl phthalate REG
68. Di-n-butyl phthalate REG
69. Di-n-octyl phthalate ND
70. Diethyl phthalate NQ
71. Dimethyl phthalate NQ
72. 1,2-Benzathracene NQ
73. Benzo(a)pyrene ND
74. 3,4-Benzofluoranthene ND
75. 11,12-Benzofluoranthene ND
76. Chrysene NQ
77. Acenaphthylene ND
78. Anthracene NQ
79. 1,2-Benzoperylene ND
80. Fluorene NQ
81. Phenanthrene NQ
82. 1,2,5/6-Dibenzanthracene ND
83. Indeno(l,2,3-Cd)pyrene ND
84. Pyrene ND
85. Tetrachloroethylene NQ
86. Toluene REG
87. Trichloroethylene NQ
88. Vinyl chloride ND
89. Aldrin ND
90. Dieldrin ND
91. Chlordane NQ
92. 4,4-DDT NQ
93. 4,4-DDE NQ
94. 4,4-DDD ND
95. Alpha-endosulfan ND
96. Beta-endosulfan ND
97. Endosulfan Sulfate
98. Endrin
99. Endrin aldehyde
100. Heptachlor
101. Heptachlor epoxide
102. Alpha-BHC
103. Beta-BHC
104. Gamma-BBC
105. Delta-BHC
106. PCB-1242
107. PCB-1254
108. PCB-1221
109. PCB-1332
110. PCB-1248
111. PCB-1260
112. PCB-1016
113. Toxaphene
114. Ant imony
115. Arsenic
116. Asbestos
117. Beryllium
118. Cadmium
119. Chromium
120. Copper
121. Cyanide
122. Lead
123. Mercury
124. Nickel
125. Selenium
126. Silver
127. Thallium
128. Zinc
129. 2,3,4,8-tetrachloro-
dibenzo-P-dioxin(TCDD)
Disposition
NQ
NQ
ND
NQ
NQ
NQ
NQ
NQ
ND
ND
NQ
ND
ND
NQ
ND
ND
ND
ND
NT
ND
ND
NT
REG
NT
NT
NT
NT
NT
ND
ND
ND
REG
ND
ND - NOT DETECTED
NQ - NOT QUANTIFIABLE
SU - SMALL, UNIQUE SOURCE
NT - NOT TREATABLE
REG - REGULATION CONSIDERED
99
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SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
•This section describes the treatment techniques currently used or
available to remove or recover wastewater pollutants normally
generated by the canmaking subcategory of the coil coating
industrial point source category. Included are discussions of
individual end-of-pipe treatment technologies and in-plant
technologies. These treatment technologies are widely used in
many industrial categories and data and information to support
their effectiveness have been drawn from a similarly wide range
of sources and data bases.
END-OF^PIPE TREATMENT TECHNOLOGIES
Individual recovery and treatment technologies are described
which are used or are suitable for use in treating wastewater
discharges from canmaking facilities. Each description includes
a functional description and discussions of application and
performance, advantages and limitations, operational factors
(reliability, maintainability, solid waste aspects), and
demonstration status. The treatment processes described include
both technologies presently demonstrated within the canmaking
subcategory and technologies demonstrated in treatment of similar
wastes in other industries.
Canmaking wastewater streams characteristically contain
significant levels of the toxic metals chromium and zinc plus
toxic organic pollutants which are associated with high levels of
oil and grease generated during the drawing and ironing process.
Additionally, the conventional pollutant parameters TSS and pH,
are found as are the nonconventional pollutants aluminum,
fluoride and phosphorus.
In general, these pollutants are removed by chemical
precipitation and sedimentation or filtration. Most of them may
be effectively removed by precipitation of metal hydroxides or
carbonates utilizing the reaction with lime, sodium hydroxide, or
sodium carbonate. For some, improved removals are provided by
the use of sodium sulfide or ferrous sulfide to precipitate the
pollutants as sulfide compounds wi.th very low solubilities.
Preliminary treatment may also be necessary including chromium
reduction, cyanide destruction, emulsion breaking and dissolved
air flotation.
Discussion of end-of-pipe treatment technologies is divided into
three parts: the major technologies; the effectiveness of major
technologies; and minor end-of-pipe technologies.
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MAJOR TECHNOLOGIES
In Sections IX, X, XI and XII, the rationale for selecting
treatment systems is discussed. The individual technologies used
in the system are described here. The major end-of-pipe
technologies are: chemical reduction of hexavalent chromium,
chemical precipitation of dissolved metals, cyanide
precipitation, granular bed filtration, pressure filtration,
settling of suspended solids, chemical emulsion breaking,
dissolved air flotation, and skimming of oil. In practice,
precipitation of metals and settling of the resulting
precipitates is often a unified two-step operation. Suspended
solids originally present in raw wastewaters are not appreciably
affected by the precipitation operation and are removed with the
precipitated metals in the settling operations. Settling
operations can be evaluated independently of hydroxide or other
chemical precipitation operations, but hydroxide and other
chemical precipitation operations can only be evaluated in
combination with a solids removal operation.
1. Chemical Reduction Of_ Chromium
Description of the Process. Reduction is a chemical reaction in
which electrons are transferred to the chemical being reduced
from the chemical initiating the transfer (the reducing agent).
Sulfur dioxide, sodium bisulfite, sodium metabisulfite, and
ferrous sulfate form strong reducing agents, in aqueous solution
and are often used in industrial waste treatment facilities for
the reduction of hexavalent chromium to the trivalent form. The
reduction allows removal of chromium from solution in conjunction
with other metallic salts by alkaline precipitation. Hexavalent
chromium is not precipitated as the hydroxide.
Gaseous sulfur dioxide is a widely used reducing agent and
provides a good example of the chemical reduction process.
Reduction using other reagents is chemically similar. The
reactions involved may be illustrated as follows:
3 SO2 **" 3 H2O————————> 3 H2SO3
3 H2S03 + 2H2Cr04 > Cr2(S04)3 + 5 H20
The above reaction is favored by low pH. A pH of from 2 to 3 is
normal for situations requiring complete reduction. At pH levels
above 5, the reduction rate is slow. Oxidizing agents such as
dissolved oxygen and ferric iron interfere with the reduction
process by consuming the reducing agent.
A typical treatment consists of 45 minutes retention in a
reaction tank. The reaction tank has an electronic recorder-
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controller device
pH and oxidation
dioxide is metered
within the range
added to maintain
tank is equipped
approximately one
shows a continuous
to control process conditions with respect to
reduction potential (ORP). Gaseous sulfur
to the reaction tank to maintain the ORP
of 250 to 300 millivolts. Sulfuric acid is
a pH level of from 1.8 to 2.0. The reaction
with a propeller agitator designed to provide
turnover per minute. Figure VII-13 (page 206)
chromium reduction system.
Application and Performance. It may be necessary in the
canmaking subcategory to treat wastewater from cans which have
been surface treated with a chromium conversion coating. A study
of an operational wastewater treatment facility chemically
reducing hexavalent chromium has shown that a 99.7 percent
reduction efficiency is easily achieved. Final concentrations of
0.05 mg/1 are readily attained, and concentrations of 0.01 mg/1
are considered to be attainable by properly maintained and
operated equipment.
Advantages and Limitations. The major advantage of chemical
reduction to reduce hexavalent chromium is that it is a fully
proven technology based on many years of experience. Operation
at ambient conditions results in low energy consumption, and the
process, especially when using sulfur dioxide, is well suited to
automatic control. Furthermore, the equipment is readily
obtainable from many suppliers, and operation is straightforward.
One limitation of chemical reduction of hexavalent chromium is
that for high concentrations of chromium, the cost of treatment
chemicals may be prohibitive. When this situation occurs, other
treatment techniques are likely to be more economical. Chemical
interference by oxidizing agents is possible in the treatment of
mixed wastes, and the treatment itself may introduce pollutants
if not properly controlled. Storage and handling of sulfur
dioxide is somewhat hazardous.
Operational Factors.
periodic removal of
Reliability:
sludge. The
Maintenance consists of
frequency of removal is a
function of the input concentrations of detrimental constituents.
Solid Waste Aspects; Pretreatment to eliminate substances which
will interfere with the process may often be necessary. The
reduction process produces trivalent chromium which can be
controlled by further treatment. There may, however, be small
amounts of sludge collected due to minor shifts in the solubility
of the contaminants. This sludge can be processed by the main
sludge treatment equipment.
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Demonstration Status. The reduction of chromium waste by sulfur
dioxide or sodium bisulfite is a classic process.and is used by
numerous plants which have hexavalent chromium compounds in
wastewaters from operations such as electroplating, conversion
coating, and noncontact cooling. Seven canmaking plants reported
practicing chromium reduction.
2. Chemical Precipitation
Dissolved toxic metal ions and certain anions may be chemically
precipitated for subsequent removal by physical means such as
sedimentation, filtration, or ceritrifugation. Several reagents
are commonly used to effect this precipitation.
1) Alkaline compounds such as lime or sodium hydroxide may be
used to precipitate many toxic metal ions as metal
hydroxides. Lime also may precipitate phosphates as
insoluble calcium phosphate and fluorides as calcium
fluoride.
2) Both "soluble" sulfides such as hydrogen sulfide or sodium
sulfide and "insoluble" sulfides such as ferrous sulfide may
• be used to precipitate many heavy metal ions as insoluble
metal sulfides.
3) Ferrous sulfate, zinc sulfate or both (as is required) may
be used to precipitate cyanide as a ferro or zinc
ferricyanide complex.
4) Carbonate precipitates may be used to remove metals either
by direct precipitation using a carbonate reagent such as
calcium carbonate or by converting hydroxides into
carbonates using carbon dioxide.
These treatment chemicals may be added to a flash mixer or rapid
mix tank, to a presettling tank, or directly to a clarifier or
other settling device. Because metal hydroxides tend to be col-
loidal in nature, coagulating agents may also be added to faci-
litate settling. After the solids have been removed, final pH
adjustment may be required to reduce the high pH created by the
alkaline treatment chemicals.
Chemical precipitation as a mechanism for removing metals from
wastewater is a complex process of at least two steps - pre-
cipitation of the unwanted metals and removal of the precipitate.
Some small amount of metal will remain dissolved in the
wastewater after precipitation is complete. The amount of
residual dissolved metal depends on the treatment chemicals used
and related factors. The effectiveness of this method of
removing any specific metal depends on the fraction of the
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specific metal in the raw wastewater (and hence in the
precipitate) and the effectiveness of suspended solids removal.
In specific instances, a sacrifical ion such as iron or aluminum
may be added to aid in the precipitation process and reduce the
fraction of a specific metal in the precipitate.
Application and Performance. Chemical precipitation is used in
canmaking for precipitation of dissolved metals. It can be used
to remove metal ions such as aluminum, antimony, arsenic,
beryllium, cadmium, chromium, cobalt, copper, iron, lead,
manganese, mercury, molybdenum, tin and zinc. The process is
also applicable to any substance that can be transformed into an
insoluble form such as fluorides, phosphates, soaps, sulfides and
others. Because it is simple and effective, chemical
precipitation is extensively used for industrial wastewater
treatment.
The performance of chemical precipitation depends on several
variables. The most important factors affecting precipitation
effectiveness are:
1. Maintenance of an alkaline pH throughout the
precipitation reaction and subsequent settling;
2. Addition of a-, sufficient excess of treatment ions to
drive the precipitation reaction to completion;
3. Addition of an adequate supply of sacrifical ions (such
as iron or aluminum) to ensure precipitation and
removal of specific target ions; and
4. Effective removal of precipitated solids (see
appropriate technologies discussed under "Solids
Removal").
Control ojf pjf. Irrespective of the solids removal technology
employed, proper control of pH is absolutely essential for
favorable performance of precipitation-sedimentation
technologies. This is clearly illustrated by solubility curves
for selected metal hydroxides and sulfides shown in Figure VII-1
(page 194), for lead in three alkalies in Figure VII-2 (page
195), and by plotting effluent zinc concentrations against pH as
shown in Figure VII-3 (page 196). Figure VII-3 was obtained from
Development Document for the Proposed Effluent Limitations
Guidelines and New Source Performance Standards for the Zinc
Segment of Nonferrous Metals Manufacturing Point Source Category,
U.S. E.P.A.7 EPA 440/1-74/033, November, 1974. Figure VII-3 was
plotted from the sampling data from several facilities with metal
finishing operations. It is partially illustrated by data
obtained from 3 consecutive days of sampling at one metal
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processing plant as displayed in Table VII-1 (page 174). Flow
through this system is approximately 49,263 1/hr (13,000 gal/hr).
This treatment system uses lime precipitation (pH adjustment)
followed by coagulant addition and sedimentation. Samples were
taken before (in) and after (out) the treatment system. The best
treatment for removal of copper and zinc was achieved on day one,
when the pH was maintained at a satisfactory level. The poorest
treatment was found on the second day, when the pH slipped to an
unacceptably low level, and intermediate values were achieved on
the third day when pH values were less than desirable but in
between those of the first and second days.
Sulfide Precipitation is sometimes used to precipitate metals
resulting in improved metals removals. Most metal sulfides are
less soluble than hydroxides and the precipitates are frequently
more dependably removed from water. Solubilities for selected
metal hydroxide, carbonate and sulfide precipitates are shown in
Table VII-4 (page 175) (Source: Lange's Handbook of Chemistry).
Sulfide precipitation is particularly effective in removing
specific metals such as silver and mercury. Sampling data from
three industrial plants using sulfide precipitation appear in
Table VII-5 (page 176).
In all cases except iron, effluent concentrations are below 0.1
mg/1 and in many cases below 0.01 mg/1 for the three plants
studied.
Sampling data from several chlorine-caustic manufacturing plants
using sulfide precipitation demonstrate effluent mercury
concentrations varying between 0.009 and 0.03 mg/1. As shown in
Figure VII-1, the solubilities of PbS and Ag2S are lower at
alkaline pH levels than either the corresponding hydroxides or
other sulfide compounds. This implies that removal performance
for lead and silver sulfides should be comparable to or better
than that for the heavy metal hydroxides. Bench scale tests on
several types of metal finishing and manufacturing wastewater
indicate that metals removal to levels of less than 0.05 mg/1 and
in some cases less than 0.01 mg/1 are common in systems using
sulfide precipitation followed by clarification. Some of the
bench scale data, particularly in the case of lead, do not
support such low effluent concentrations. However, lead is
consistently removed to very low levels (less than 0.02 mg/1) in
systems using hydroxide and carbonate precipitation and
sedimentation.
Of particular interest is the ability of sulfide to precipitate
hexavalent chromium (Cr+6) without prior reduction to the tri-
valent state as is required in the hydroxide process. When
ferrous sulfide is used as the precipitant, iron and sulfide act
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as reducing agents for the hexavalent chromium according
reaction:
to the
Cr03
FeS
3H20 ----- > Fe(OH)3 + Cr(OH)3
The sludge produced in this reaction consists mainly of ferric
hydroxides, chromic hydroxides and various metallic sulfides.
Some excess hydroxyl ions are generated in this process, possibly
requiring a downward re-adjustment of pH.
Based on the available data, Table VII-6 (page 177) shows the
minimum reliably attainable effluent concentrations for sulfide
precipitation-sedimentation systems. These values are used to
calculate performance predictions of sulfide precipitation-
sedimentation systems. -
Carbonate Precipitation is sometimes used to precipitate metals,
especially where precipitated metals values are to be recovered.
The solubility of most metal carbonates is intermediate between
hydroxide and sulfide solubilities; in addition, carbonates form
easily filtered precipitates.
Carbonate ions appear to be particularly useful in precipitating
lead and antimony. Sodium carbonate has been observed being
added at treatment to improve lead precipitation and removal in
some industrial plants. The lead hydroxide and lead carbonate
solubility curves displayed in Figure VII-2 (page 195) ("Heavy
Metals Removal," by Kenneth Lanovette, Chemical
Enq i neer i nq/Deskbook Issue, Oct. 17, 1977) explain this
phenomenon .
Co-precipitation With Iron- The presence of substantial
quantities of iron in metal bearing wastewaters before treatment
has been shown to improve the removal of toxic metals. In some
cases this iron is an integral part of the industrial wastewater;
in other cases iron is deliberately added as a pre or first step
of treatment. The iron functions to improve toxic metal removal
by three mechanisms: the iron co-precipitates with toxic metals
forming a stable precipitate which desolubilizes the toxic metal;
the iron improves the settleability of the precipitate; and the
large amount of iron reduces the fraction of toxic metal in the
precipitate. Co-precipitation with iron has been practiced for
many years-incidental ly when iron was a substantial consitutent
of raw wastewater and intentionally when iron salts were added as
a coagulant aid. Aluminum or mixed iron-aluminum salt also have
been used.
Co-precipitation using large amounts of ferrous iron salts is
known as ferrite co-precipitation because magnetic iron oxide or
ferrite is formed. The addition of ferrous salts (sulfate) is
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followed by alkali precipitation and air oxidation. The
resultant precipitate is easily removed by filtration and may be
removed magnetically. Data illustrating the performance of
ferrite co-precipitation is shown in Table VII-7 (page 178).
Advantages and Limitations
Chemical precipitation has proven to be an effective technique
for removing many pollutants from industrial wastewater. It
operates at ambient conditions and is well suited to automatic
control. The use of chemical precipitation may be limited
because of interference by chelating agents, because of possible
chemical interference of mixed wastewaters and treatment
chemicals, or because of the potentially hazardous situation
involved with the storage and handling of those chemicals. Lime
is usually added as a slurry when used in hydroxide
precipitation. The slurry must be kept well mixed and the
addition lines periodically checked to prevent blocking of the
lines, which may result from a buildup of solids. Also,
hydroxide precipitation usually makes recovery of the
precipitated metals difficult, because of the heterogeneous
nature of most hydroxide sludges.
The major advantage of the sulfide precipitation process is that
the extremely low solubility of most metal sulfides promotes very
high metal removal efficiencies; the sulfide process also has the
ability to remove chromates and dichromates without preliminary
reduction of the chromium to its trivalent state. In addition,
sulfide can precipitate metals complexed with most complexing
agents. The process demands care, however, in maintaining the pH
of the solution at approximately 10 in order to prevent the gen-
eration of toxic hydrogen sulfide gas. For this reason,
ventilation of the treatment tanks may be a necessary precaution
in most installations. The use of insoluble sulfides reduces the
problem of hydrogen sulfide evolution. As with hydroxide
precipitation, excess sulfide ion must be present to drive the
precipitation reaction to completion. Since the sulfide ion
itself is toxic, sulfide addition must be carefully controlled to
maximize heavy metals precipitation with a minimum of excess
sulfide to avoid the necessity of post treatment. At very high
excess sulfide levels and high pH, soluble mercury-sulfide
compounds may also be formed. Where excess sulfide is present,
aeration of the effluent stream can aid in oxidizing residual
sulfide to the less harmful sodium sulfate (Na2S04). The cost of
sulfide precipitants is high in comparison with hydroxide
precipitants, and disposal of metallic sulfide sludges may pose
problems. An essential element in effective sulfide
precipitation is the removal of precipitated solids from the
wastewater and proper disposal in an appropriate site. Sulfide
precipitation will also generate a higher volume of sludge, than
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hydroxide precipitation, resulting in higher disposal and
dewatering costs. This is especially true when ferrous sulfide
is used as the precipitant.
Sulfide precipitation may be used as a polishing treatment after
hydroxide precipitation-sedimentation. This treatment
configuration may provide the better treatment effectiveness of
sulfide precipitation while minimizing the variability caused by
changes in raw wastewater composition and reducing the amount of
sulfide precipitant required.
Operational
Factors.
Reliability:
Alkaline
.. chemical
precipitation is highly reliable, although proper monitoring and
control are required. Sulfide precipitation systems provide
similar reliability.
Maintainability: The major maintenance needs involve periodic
upkeep of monitoring equipment, automatic feeding equipment,
mixing equipment, and other hardware. Removal of accumulated
sludge is necessary for efficient operation of precipitation-
'sedimentation systems.
Solid Waste Aspects: Solids which precipitate out are removed in
a subsequent treatment step. Ultimately, these solids require
proper disposal.
Demonstration Status. Chemical precipitation of metal hydroxides
is a classic wastewater treatment technology used by most
industrial wastewater treatment systems. Chemical precipitation
of metals in the carbonate form alone has been found to be
feasible and is commercially used to permit metals recovery and
water reuse. Full scale commercial sulfide precipitation units
are in operation at numerous installations. As noted earlier,
sedimentation to remove precipitates is discussed separately.
Use in Canmakinq Plants. Chemical precipitation equipment is in
place at 57 canmaking plants plants, however only a limited
amount of canmaking effluent data were received.
3. Cyanide Precipitation
Cyanide precipitation, although a method for treating cyanide in
wastewaters, does not destroy cyanide. The cyanide is retained
in the sludge that is formed. Reports indicate that during
exposure to sunlight the cyanide complexes can break down and
form free cyanide. For this reason the sludge from this
treatment method must be disposed of carefully.
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Cyanide may be precipitated and settled out of wastewaters by the
addition of zinc sulfate or ferrous sulfate. In the presence of
iron, cyanide will form extremely stable cyanide complexes. The
addition of zinc sulfate or ferrous sulfate forms zinc
ferrocyanide or ferro and ferricyanide complexes.
Adequate removal of the precipitated cyanide requires that the pH
must be kept at 9.0 and an appropriate retention time be
maintained. A study has shown that the formation of the complex
is very dependent on pH. At pH's of 8 and 10 the residual
cyanide concentrations measured are twice those of the same
reaction carried out at a pH of 9. Removal efficiencies also
depend heavily on the retention time allowed. The formation of
the complexes takes place rather slowly. Depending upon the
excess amount of zinc sulfate or ferrous sulfate added, at least
a 30 minute retention time should be allowed for the formation of
the cyanide complex before continuing on to the clarification
stage.
One experiment with an initial concentration of 10 mg/1 of
cyanide showed that 98 percent of the cyanide was complexed ten
minutes after the addition of ferrous sulfate at twice the
theoretical amount necessary. Interference from other • metal
ions, such as cadmium, might result in the need for longer
retention times.
Table VII-8 (page 178) presents cyanide precipitation data
three coil coating plants.
from
Plant 1057 allowed a 27 minute retention time for the formation
of the complex. The retention time for the other plants is not
known. The data suggest that over a wide range of cyanide
concentration in the raw wastewater, the concentration of cyanide
can be reduced in the effluent stream to under 0.15 mg/1.
Application and Performance. Cyanide precipitation can be used
when cyanide destruction is not feasible because of the presence
of cyanide complexes which are difficult to destroy. Effluent
concentrations of cyanide well below 0.15 mg/1 are possible.
Advantages and Limitations. Cyanide precipitation is an
inexpensive method of treating cyanide. Problems may occur when
metal ions interfere with the formation of the complexes.
Demonstration Status; Cyanide precipitation is used in at least
six coil coating plants but is not reported to be used at any
canmaking plants.
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4. Granular Bed Filtration
Filtration occurs in nature as the s.urface ground waters are
cleansed by sand. Silica sand, anthracite coal, and garnet are
common filter media used in water treatment plants. These are
usually supported by gravel. The media may be used singly or in
combination. The multi-media filters may be arranged to maintain
relatively distinct layers by virtue of balancing the forces of
gravity, flow, and buoyancy on the individual particles. This is
accomplished by selecting appropriate filter flow rates (gpm/sq-
ft), media grain size, and density.
Granular bed filters may be classified in terms of filtration
rate, filter media, flow pattern, or method of pressurization.
Traditional rate classifications are slow sand, rapid sand, and
high rate mixed media. In the slow sand filter, flux or
hydraulic loading is relatively low, and removal of collected
solids to clean the filter is therefore relatively infrequent.
The filter is often cleaned by scraping off the inlet face (top)
of the sand bed. In the higher rate filters, cleaning is
frequent and is accomplished by a periodic backwash, opposite to
the direction of normal flow.
A filter may use a single medium such as sand or diatomaceous
earth, but dual and mixed (multiple) media filters allow higher
flow rates and efficiencies. The dual media filter usually
consists of a fine bed of sand under a coarser bed of anthracite
coal. The coarse coal removes most of the influent solids, while
the fine sand'performs a polishing function. At the end of the
backwash, the fine sand settles to the bottom because it is
denser than the coal, and the filter is ready for normal
operation. The mixed media filter operates on the same
principle, with the finer, denser media at the bottom and the
coarser, less dense media at the top. The usual arrangement is
garnet at the bottom (outlet end) of the bed, sand in the middle,
and anthracite coal at the top. Some mixing of these layers
occurs and is, in fact, desirable.
The flow pattern is usually top-to-bottom, but other patterns are
sometimes used. Upflow filters are sometimes used, and in a
horizontal filter the flow is horizontal. In a biflow filter
the influent enters both the top and the bottom and exits
laterally. The advantage of an upflow filter is that with an
upflow backwash the particles of a single filter medium are
distributed and maintained in the desired coarse-to-fine (bottom-
to-top) arrangement. The disadvantage is that the bed tends to
become fluidized, which ruins filtration efficiency. The biflow
design is an attempt to overcome this problem.
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The classic granular bed filter operates by gravity flow;
however, pressure filters are fairly widely used. They permit
higher solids loadings before cleaning and are advantageous when
the filter effluent must be pressurized for further downstream
treatment. In addition, pressure filter systems are often less
costly for low to moderate flow rates.
Figure VII-14 (page 207) depicts a high- rate, dual media, gravity
downflow granular bed filter, with self-stored backwash. Both
filtrate and backwash are piped around the bed in an arrangement
that permits gravity upflow of the backwash, with the stored
filtrate serving as backwash. Addition of the indicated
coagulant and polyelectrolyte usually results in a substantial
improvement in filter performance.
Auxiliary filter cleaning is sometimes employed in the upper few
inches of filter beds. This is conventionally referred to as
surface wash and is accomplished by water jets just below the
surface of the expanded bed during the backwash cycle. These
jets enhance the scouring action in the bed by increasing the
agitation.
An important feature for successful filtration and backwashing is
the underdrain. This is the support structure for the bed. The
underdrain provides an area for collection of the filtered water
without clogging from either the filtered solids or the media
grains. In addition, the underdrain prevents loss of the media
with the water, and during the backwash cycle it provides even
flow distribution over the bed. Failure to dissipate the
velocity head during the filter or backwash cycle will result in
bed upset and the need for major repairs.
Several standard approaches are employed for filter underdrains.
The simplest one consists of a parallel porous pipe imbedded
under a layer of coarse gravel and manifolded to a header pipe
for effluent removal. Other approaches to the underdrain system
are known as the Leopold and Wheeler filter bottoms. Both of
these incorporate false concrete bottoms with specific porosity
configurations to provide drainage and velocity head dissipation.
Filter system operation may be manual or automatic. The filter
backwash cycle may be on a timed basis, a pressure drop basis
with a terminal value which triggers backwash, or a solids carry-
over basis from turbidity monitoring of the outlet stream. All
of these schemes have been used successfully.
Application and Performance. Wastewater treatment plants often
use granular bed filters for polishing after clarification,
sedimentation, or other similar operations. Granular bed
filtration thus has potential application to nearly all
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industrial plants. Chemical additives which enhance the upstream
treatment equipment may or may not be compatible with or enhance
the filtration process. Normal operating flow rates for various
types of filters are as follows:
Slow Sand
Rapid Sand
High Rate Mixed Media
2.04 - 5.30 1/sq m-hr
40.74 - 51.48 1/sq m-hr
81.48 - 122.22 1/sq m-hr
Suspended solids are commonly removed from wastewater streams by
filtering through a deep 0.3-0.9 m (1-3 feet) granular filter
bed. The porous bed formed by the granular media can be designed
to remove practically all suspended particles. Even colloidal
suspensions (roughly 1 to 100 microns) are adsorbed on the
surface of the media grains as they pass in close proximity in
the narrow bed passages.
Properly operated filters following some pretreatment to reduce
suspended solids below 200 mg/1 should produce water with less
than 10 mg/1 TSS. For example, multimedia filters produced the
effluent qualities shown in Table VII-9 (page 179).
The principal advantages of granular bed filtration are its
comparatively (to other filters) low initial and operating costs,
reduced land requirements over other methods to achieve the same
level of solids removal, and elimination of chemical additions to
the discharge stream. However, the filter may require
pretreatment if the solids level is high (over 100 mg/1).
Operator training must be somewhat extensive due to the controls
and periodic backwashing involved, and backwash must be stored
and dewatered for economical disposal.
Operational Factors. Reliability: The recent improvements in
T^eu--, technol°gy have significantly improved filtration
reliability. Control systems, improved designs, and good
operating procedures have made filtration a highly reliable
method of water treatment.
Maintainability: Deep bed filters may be operated with either
manual or automatic backwash. In either case, they must be
periodically inspected for media attrition, partial plugging, and
leakage. Where backwashing is not used, collected solids must be
removed by shoveling, and filter media must be at least partially
replaced. *
Solid Waste Aspects: Filter backwash is generally recycled
within the wastewater treatment system, so that the solids
ultimately appear in the clarifier sludge stream for subsequent
dewatering. Alternatively, the backwash stream may be dewatered
directly or, if there is no backwash, the collected solids may be
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disposed of in a suitable landfill. In either of these
situations there is a solids disposal problem similar to that of
clarifiers.
Demonstration Status. Deep bed filters are in common use in
municipaltreatment plants. Their use in polishing industrial
clarifier effluent is increasing, and the technology is proven
and conventional. Granular bed filtration is used in many
manufacturing plants. As noted previously, however, little data
is available characterizing the effectiveness of filters
presently in use within the industry. However, 10 canmaking
plants have filtration equipment in-place.
5. Pressure Filtration
Pressure filtration works by pumping the liquid through a filter
material which is impenetrable to the solid phase. The positive
pressure exerted by the feed pumps or other mechanical means
provides the pressure differential which is the principal driving
force. Figure VII-15 (page 208) represents the operation of one
type of pressure filter.
A typical pressure filtration unit consists of a number of plates
or trays which are held rigidly in a frame to ensure alignment
and which are pressed together between a fixed end and a
traveling end. On the surface of each plate is mounted a filter
made of cloth or a synthetic fiber. The feed stream is pumped
into the unit and passes through holes in the trays along the
length of the press until the cavities or chambers between the
trays are completely filled. The solids are then entrapped, and
a cake begins to form on the surface of the filter material. The
water passes through the fibers, and the solids are retained.
At the bottom of the trays are drainage ports. The filtrate is
collected and discharged to a common drain. As the filter medium
becomes coated with sludge, the flow of filtrate through the
filter drops sharply, indicating that the capacity of the filter
has been exhausted. The unit must then be cleaned of the sludge.
After the cleaning or replacement of the filter media, the unit
is again ready for operation.
Application and Performance. Pressure filtration is used in coil
coating for sludge dewatering and also for direct removal of
precipitated and other suspended solids from wastewater. Because
dewatering is such a common operation in treatment systems,
pressure filtration is a technique which can be found in many
industries concerned with removing solids from their waste
stream.
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In a typical pressure filter, chemically preconditioned sludge
detained in the unit for one to three hours under pressures
varying from 5 to 13 atmospheres exhibited final solids content
between 25 and 50 percent.
Advantages and Limitations. The pressures which may be applied
to a sludge for removal of water by filter presses that are
currently available range from 5 to 13 atmospheres. As a result,
pressure filtration may reduce the amount of chemical
pretreatment required for sludge dewatering. Sludge retained in
the form of the filter cake has a higher percentage of solids
than that from centrifuge or vacuum filter. Thus, it can be
easily accommodated by materials handling systems.
As a primary solids removal technique, pressure filtration
requires less space than clarification and is well suited to
streams with high solids loadings. The sludge produced may be
disposed without further dewatering, but the amount of sludge is
increased by the use of filter precoat materials (usually
diatomaceous earth). Also, cloth pressure filters often do not
achieve as high a degree of effluent clarification as clarifiers
or granular media filters.
Two disadvantages associated with pressure filtration in the past
have been the short life of the filter cloths and lack of
automation. New synthetic fibers have largely offset the first
of these problems. Also, units with automatic feeding and
pressing cycles are now available.
For larger operations, the relatively high space requirements, as
compared to those of a centrifuge, could be prohibitive in some
situations.
Operational Factors. Reliability: With proper pretreatment,
design, and control, pressure filtration is a highly dependable
system.
Maintainability: Maintenance consists of periodic cleaning or
replacement of the filter media, drainage grids, drainage piping,
filter pans, and other parts of the system. If the removal of
the sludge cake is not automated, additional time is required for
this operation.
Solid Waste Aspects: Because it is generally drier than other
types of sludges, the filter sludge cake can be handled with
relative ease. One of several accepted procedures may be used to
dispose of the accumulated sludge, depending on its chemical
composition. The levels of toxic metals present in sludge from
treating canmaking wastewater necessitate proper disposal.
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Demonstration Status. Pressure filtration is a commonly used
technology in a great many commercial applications.
6. Settling
Settling is a process which removes solid particles from a liquid
matrix by gravitational force. This is done by reducing the
velocity of the feed stream in a large volume tank or lagoon so
that gravitational settling can occur. Figure VII-16 (page 209)
shows two typical settling devices.
Settling is often preceded by chemical precipitation which
converts dissolved pollutants to solid form and by coagulation
which enhances settling by coagulating suspended precipitates
into larger, faster settling particles.
If no chemical pretreatment is used, the wastewater is fed into a
tank or lagoon where it loses velocity and the suspended solids
are allowed to settle out. Long retention times are generally
required. Accumulated sludge can be collected either
periodically or continuously and either manually or mechanically.
Simple settling, however, may require excessively large
catchments, and long retention times (days as compared with
hours) to achieve high removal efficiencies. Because of this,
addition of settling aids such as alum or polymeric flocculants
is often economically attractive.
In practice, chemical precipitation often precedes settling, and
inorganic coagulants or polyelectrolytic flocculants are usually
added as well. Common coagulants include sodium sulfate, sodium
aluminate, ferrous or ferric sulfate, and ferric chloride.
Organic polyelectrolytes vary in structure, but all usually form
larger floe particles than coagulants used alone.
Following this pretreatment, the wastewater can be fed into a
holding tank or lagoon for settling, but is more often piped into
a clarifier for the same purpose. A clarifier reduces space
requirements, reduces retention! time, and increases solids
removal efficiency. Conventional clarifiers generally consist of
a circular or rectangular tank with a mechanical sludge
collecting device or with a sloping funnel-shaped bottom designed
for sludge collection. In advanced settling devices inclined
plates, slanted tubes, or a lamellar network may be included
within the clarifier tank in order to increase the effective
settling area, increasing capacity. A fraction of the sludge
stream is often recirculated to the inlet, promoting formation of
a denser sludge.
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Application and Performance. Settling and clarification are used
in the canmaking industry to remove precipitated metals.
Settling can be used to remove most suspended solids in a
particular waste stream; thus it is used extensively by many
different industrial wastewater treatment facilities. Because
most metal ion pollutants are readily converted to solid metal
hydroxide precipitates, settling is of particular use in those
industries associated with metal production, metal finishing,
metal working, and any other industry with high concentrations of
metal ions in their wastewaters. In addition to toxic metals,
suitably precipitated materials effectively removed by settling
include aluminum, iron, manganese, cobalt, antimony, beryllium,
molybdenum, fluoride, phosphate, and many others.
A properly operating settling system can efficiently remove
suspended solids, precipitated metal hydroxides, and other
impurities from wastewater. The performance of the process
depends on a variety of factors, including the density and
particle size of the solids, the effective charge on the
suspended particles, and the types of chemicals used in
pretreatment. The site of flocculant or coagulant addition also
may significantly influence the effectiveness of clarification.
If the flocculant is subjected to too much mixing before entering
the clarifier, the complexes may be sheared and the settling
effectiveness diminished. At the same time, the flocculant must
have sufficient mixing and reaction time in order for effective
set-up and settling to occur. Plant personnel have observed that
the line or trough leading into the clarifier is often the most
efficient site for flocculant addition. The performance of
simple settling is a function of the retention time, particle
size and density, and the surface area of the basin.
The data displayed in Table VII-10 (page 179) indicate suspended
solids removal efficiencies in settling systems.
The mean effluent TSS concentration obtained by the plants shown
in Table VII-10 is 10.1 mg/1. Influent concentrations averaged
838 mg/1. The maximum effluent TSS value reported is 23 mg/1.
These plants all use alkaline pH adjustment to precipitate metal
hydroxides, and most add a coagulant or flocculant prior to
settling.
Advantages and Limitations. The major advantage of simple
settling is its simplicity as demonstrated by the gravitational
settling of solid particulate waste in a holding tank or lagoon.
The major problem with simple settling is the long retention time
necessary to achieve complete settling, especially if the
specific gravity of the suspended matter is close to that of
water. Some materials cannot be practically removed by simple
settling alone.
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Settling performed in a clarifier is effective in removing slow-
settling suspended matter in a shorter time and in less space
than a simple settling system. Also, effluent quality is often
better from a clarifier. The cost of installing and maintaining
a clarifier, however, is substantially greater than the costs
associated with simple settling.
Inclined plate, slant tube, and lamella settlers have even higher
removal efficiencies than conventional clarifiers, and greater
capacities per unit area are possible. Installed costs for these
advanced clarification systems are claimed to be one half the
cost of conventional systems of similar capacity.
Operational Factors. Reliability: Settling can be a highly
reliable technology for removing suspended solids. Sufficient
retention time and regular sludge removal are important factors
affecting the reliability of all settling systems. Proper
control of pH adjustment, chemical precipitation, and coagulant
or flocculant addition are additional factors affecting settling
efficiencies in systems (frequently clarifiers) where these
methods are used.
Those advanced settlers using slanted tubes, inclined plates, or
a lamellar network may require pre-screening of the waste in
order to eliminate any fibrous materials which could potentially
clog the system. Some installations are especially vulnerable to
shock loadings, as by storm water runoff, but proper system
design will prevent this.
Maintainability: When clarifiers or other advanced settling
devices are used, the associated system utilized for chemical
pretreatment and sludge dragout must be maintained on a regular
basis. Routine maintenance of mechanical parts is also
necessary. Lagoons require little maintenance other than
periodic sludge removal.
Demonstration Status
Settling represents the typical method of solids removal and is
employed extensively in industrial wastewater treatment. The
advanced clarifiers are just beginning to appear in significant
numbers in commercial applications. Sedimentation or
clarification is used in 28 canmaking plants.
7.
Skimming
Pollutants with a specific gravity less than water will often
float unassisted to the surface of the wastewater. Skimming
removes these floating wastes. Skimming normally takes place in
a tank designed to allow the floating debris to rise and remain
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on the surface, while the liquid flows to an outlet located below
the floating layer. Skimming devices are therefore suited to the
removal of non-emulsified oils from raw waste streams. Common
skimming mechanisms include the rotating drum type, which picks
up oil from the surface of the water as it rotates. A doctor
blade scrapes oil from the drum and collects it in a trough for
disposal or reuse. The water portion is allowed to flow under
the rotating drum. Occasionally, an underflow baffle is
installed after the drum; this has the advantage of retaining any
floating oil which escapes the drum skimmer. The belt type
skimmer is pulled vertically through the water, collecting oil
which is scraped off from the surface and collected in a drum.
Gravity separators, such as the API type, utilize overflow and
underflow baffles to skim a floating oil layer from the surface
of the wastewater. An overflow-underflow baffle allows a small
amount of wastewater (the oil portion) to flow over into a trough
for disposition or reuse while the majority of the water flows
underneath the baffle. This is followed by an overflow baffle,
which is set at a height relative to the first baffle such that
only the oil bearing portion will flow over the first baffle
during normal plant operation. A diffusion device, such as a
vertical slot baffle, aids in creating a uniform flow through the
system and increasing oil removal efficiency.
Application and Performance. Lubricants cleaned from most
seamless cans during the canwashing process are the principal
source of oil. Skimming is applicable to any wastewater stream
containing pollutants which float to the surface. It is commonly
used to remove free oil, grease, and soaps. Skimming is often
used in conjunction with air flotation or clarification in order
to increase its effectiveness.
The removal efficiency of a skimmer is partly a function of the
retention time of the water in the tank. Larger, more buoyant
particles require less retention time than smaller particles.
Thus, the efficiency also depends on the composition of the waste
stream. The retention time required to allow phase separation
and subsequent skimming varies from 1 to 15 minutes, depending on
the wastewater characteristics.
API or other gravity-type separators tend to be more suitable for
use where the amount of surface oil flowing through the system is
consistently significant. Drum and belt type skimmers are
applicable to wastewater streams which evidence smaller amounts
of floating oil and where surges of floating oil are not a
problem. Using an API separator system in conjunction with a
drum type skimmer would be a very effective method of removing
floating contaminants from non-emulsified oily waste streams.
Sampling data illustrate the capabilities of the technology with
both extremely high and moderate oil influent levels.
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This data, displayed in Table VII-11 (page 179), is intended to
be illustrative of the very high level of oil and grease removals
attainable in a simple two stage oil removal system. Based on
the performance of installations in a variety of manufacturing
plants and permit requirements that are constantly achieved, it
is determined that effluent oil levels may be reliably reduced
below 10 mg/1 with moderate influent concentrations. Very high
concentrations of oil such as the 22 percent shown above may
require two step treatment to achieve this level.
Skimming which removes oil may also be used to remove base levels
of organics. Plant sampling data show that many organic
compounds tend to be removed in standard wastewater treatment
equipment. Oil separation not only removes oil but also organics
that are more soluble in oil than in water. Clarification
removes organic solids directly and probably removes dissolved
organics by adsorption on inorganic solids.
The source of these organic pollutants is not always known with
certainty, although in metal forming operations they seem to
derive mainly from various process lubricants. They are also
sometimes present in the plant water supply, as additives to
proprietary formulations of cleaners, or due to leaching from
plastic lines .and other materials.
High molecular weight organics in particular are much more
soluble in organic solvents than in water. Thus they are much
more concentrated in the oil phase that is skimmed than in the
wastewater. The ratio of solubilities of a compound in oil and
water phases is called the partition coefficient. The logarithm
of the partition coefficients for fifteen polynuclear aromatic
hydrocarbon (PAH) compounds in octanol and water are listed in
Table VII-12 (page 180).
A study of priority organic compounds commonly found in metal
forming operations wastewater streams indicated that incidental
removal of these compounds often occurs as a result of oil
removal or clarification processes. When all organics analyses
from aluminum forming, copper forming, and coil coating are
considered, removal of organic compounds by other waste treatment
technologies appears to be marginal in many cases. However, when
only raw waste concentrations of 0.05 mg/1 or greater are
considered, incidental organics removal becomes much more
apparent. Lower values, those less than 0.05 mg/1, are much more
subject to analytical variation, while higher values indicate a
significant presence of a given compound. When these factors are
taken into account, analysis data indicate that most
clarification and oil removal treatment systems remove
significant amounts of the organic compounds present in the raw
wastewater. The API oil-water separation system and the thermal
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emulsion breaker (TEB) performed notably in this regard, as shown
in the following tabulation (all values in mg/1).
Data from five plant days demonstrate removal of organics by the
combined oil skimming and settling operations performed on coil
coating wastewaters. Days were chosen where treatment system
influent and effluent analyses provided paired data points for
oil and grease and the organics present. All organics found at
quantifiable levels on those days were included. Further, only
those days were chosen where oil and grease raw wastewater
concentrations exceeded 10 mg/1 and where there was reduction in
oil and grease going through the treatment system. All plant
sampling days which met the above criteria are included below.
The conclusion is that when oil and grease are removed, organics
are removed, also.
Plant-Day
1054-3
13029-2
13029-3
38053-1
38053-2
Mean
Percent Removal
Oil & Grease '
Organics
84.2
For aluminum forming wastewaters, effective oil removal
technology (such as oil skimming or emulsion breaking) is capable
of removing approximately 97 percent of the total toxic organics
(TTO) from the raw waste. As shown in the following tabulation,
the achievable TTO concentration is approximately 0.690 mg/1.
The influent and effluent concentrations presented for each
pollutant were taken from the aluminum forming category for
several plants with effective oil removal technologies in place.
In calculating the concentrations, if only one day's sampling
datum was available, that value was used; if two day's sampling
data were available, the higher of the values was used; and, if
three day's sampling data were available, the mean or the median
value was used, whichever was higher. The Agency confident that
the 0.690 mg/1 value is an appropriate basis for effluent
limitations, since the highest values were used in the
calculation.
Advantages and Limitations. Skimming as a pretreatment is
effective in removing naturally floating waste material. It also
improves the performance of subsequent downstream treatments.
Many pollutants, particularly dispersed or emulsified oil, will
not float "naturally" but require additional treatments. There-
fore, skimming alone may not remove all the pollutants capable of
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being removed by air flotation or other more sophisticated
technologies.
Operational Factors. Reliability: Because of its simplicity,
skimming is a very reliable technique.
Maintainability: The skimming mechanism requires periodic
lubrication, adjustment, and replacement of worn parts.
Solid Waste Aspects: The collected layer of debris must be
disposed of by contractor removal, landfill, or incineration.
Because relatively large quantities of water are present in the
collected wastes, incineration is not always a viable disposal
method.
Demonstration Status. Skimming is a common operation utilized
extensivelyby industrial waste treatment systems. Oil removal
equipment for skimming as a separate process or in conjunction
with chemical emulsion breaking, or dissolved air flotation
(discussed below) is in place at 53 canmaking plants.
8.
Flotation
Flotation is the process of causing particles such as metal
hydroxides or oil to float to the surface of a tank where they
can be concentrated and removed. This is accomplished by
releasing gas bubbles which attach to the solid particles,
increasing their buoyancy and causing them to float. In
principle, this process is the opposite of sedimentation. Figure
VII-23 (page 216) shows one type of flotation system.
Flotation is used primarily in the treatment of wastewater
streams that carry heavy loads of finely divided suspended solids
or oil. Solids having a specific gravity only slightly greater
than l.O/ which- would require abnormally long sedimentation
times/ may be removed in much less time by flotation.
This process may be performed in Several ways: foam, dispersed
air/ dissolved air, gravity, and vacuum flotation are the most
commonly used techniques. Chemical additives are o>ften used to
enhance the performance of the flotation process.
The principal difference among types of flotation is the method
of generating the minute gas bubbles (usually air) in a
suspension of water and small particles. Chemicals may be used
to improve the efficiency with any of the basic methods. The
following paragraphs describe the dissolved air flotation
technique including the method of bubble generation.
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Dissolved Air Flotation - In dissolved air flotation, bubbles are
produced by releasing air from a supersaturated solution under
relatively high pressure. There are two types of contact between
the gas bubbles and particles. The first type is predominant in
the flotation of flocculated materials and involves the
entrapment of rising gas bubbles in the flocculated particles as
they increase in size. The bond between the bubble and particle
is one of physical capture only. The second type of contact is
one of adhesion. Adhesion results from the intermolecular
attraction exerted at the interface between the solid particle
and gaseous bubble.
Application and Performance. The primary variables for flotation
design are pressure, feed solids concentration, and retention
period. The suspended solids in the effluent decrease, and the
concentration of solids in the float increases with increasing
retention period. When the flotation process is used primarily
for clarification, a retention period of 20 to 30 minutes usually
is adequate for separation and concentration.
Advantages and Limitations. Some advantages of the flotation
process are the high levels of solids separation achieved in many
applications, the relatively low energy requirements, and the
adaptability to meet the treatment requirements of different
waste types. Limitations of flotation are that it often requires
addition of chemicals to enhance process performance and that it
generates large quantities of solid waste.
Operational Factors. Reliability: Flotation systems normally
are very reliable with proper maintenance of the sludge collector
mechanism and the motors and pumps used for aeration.
Maintainability: Routine maintenance is required on the pumps
and motors. The sludge collector mechanism is subject to
possible corrosion or breakage and may require periodic
replacement.
Solid Waste Aspects: Chemicals are commonly used to aid . the
flotation process by creating a surface or a structure that can
easily adsorb or entrap air bubbles. Inorganic chemicals, such
as the aluminum and ferric salts, and activated silica, can bind
the particulate matter together and create a structure that can
entrap air bubbles. Various organic chemicals can change the
nature of either the air-liquid interface or the solid-liquid
interface, or both. These compounds usually collect on the
interface to bring about the desired changes. The added
chemicals plus the particles in solution combine to form a large
volume of sludge which must be further treated or properly
disposed.
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Demonstration Status. Flotation is a fully developed process and
is readily available for the treatment of a wide variety of
industrial waste streams. Dissolved air flotation is installed
at 16 canmaking plants.
9. Chemical Emulsion Breaking
Chemical treatment is often used to break stable oil-water (6-W)
emulsions. An 0-W emulsion consists of oil dispersed in water,
stablized by electrical charges and emulsifying agents. A stable
emulsion will not separate or break down without some form of
treatment.
Once an emulsion is broken, the difference in specific gravities
allows the oil to float to the surface of the water. Solids
usually form a layer between the oil and water, since some oil is
retained in the solids. The longer the retention time, the more
complete and distinct the separation between the oil, solids, and
water will be. Often other methods of gravity differential
separation, such as air flotation or rotational separation (e.g.,
centrifugation), are used to enhance and speed separation. A
schematic flow diagram of one type of application is shown in
Figure VII-31 (page 224).
The major equipment required for chemical emulsion breaking
includes: reaction chambers with agitators, chemical storage
tanks, chemical feed systems, pump, and piping.
Emulsifiers may be used in the plant to aid in stabilizing or
forming emulsions. Emulsifiers are surface-active agents which
alter the characteristics of the oil and water interface. These
surfactants have rather long polar molecules. One end of the
molecule is particularly soluble in water (e.g., carboxyl,
sulfate, hydroxyl, or sulfonate groups) and the other end is
readily soluble in oils (am organic group which varies greatly
with the different surfactant type). Thus, the surfactant
emulsifies or suspends the organic material (oil) in water.
Emulsifiers also lower the surface tension of the 0-W emulsion as
a result of solvation and ionic complexing. These emulsions must
be destabilized in the treatment system.
Application and Performance. Emulsion breaking is applicable to
waste streams containing emulsified oils or lubricants such as
rolling and drawing emulsions.
Treatment of spent 0-W emulsions involves the use of chemicals to
break the emulsion followed by gravity differential separation.
Factors to be considered for breaking emulsions are type of
chemicals, dosage and sequence of addition, pH, mechanical shear
and agitation, heat, and retention time.
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Chemicals, e.g., polymers, alum, ferric chloride, and organic
emulsion breakers, break emulsions by neutralizing repulsive
charges between particles, precipitating or salting out
emulsifying agents, or altering the interfacial film between the
oil and water so it is readily broken. Reactive cations, e.g.,
H(+1), Al(+3), Fe(+3), and cationic polymers, are particularly
effective in breaking dilute O-W emulsions. Once the charges
have been neutralized or the interfacial film broken, the small
oil droplets and suspended solids will be adsorbed on the surface
of the floe that is formed, or break out and float to the top.
Various types of emulsion-breaking chemicals are used for the
various types of oils.
If more than one chemical is required, the sequence of addition
can make quite a difference in both breaking efficiency and
chemical dosages.
pH plays an important role in emulsion breaking, especially if
cationic inorganic chemicals, such as alum, are used as
coagulants. A depressed pH in the range of 2 to 4 keeps the
aluminum ion in its most positive state where it can function
most effectively for charge neutralization. After some of the
oil is broken free and skimmed, raising the pH into the 6 to 8
range with lime or caustic will cause the aluminum to hydrolyze
and precipitate as aluminum hydroxide. This floe entraps or
adsorbs destablizied oil droplets which can then be separated
from the waste phase. Cationic polymers can break emulsions over
a wider pH range and thus avoid acid corrosion and the additional
sludge generated from neutralization; however, an inorganic
flocculant is usually required to supplement the polymer emulsion
breaker's adsorptive properties.
Mixing is important in breaking O-W emulsions. Proper chemical
feed and dispersion is required for effective results. Mixing
also causes collisions which help break the emulsion, and
subsequently helps to agglomerate droplets.
In all emulsions, the mix of two immiscible liquids has a
specific gravity very close to that of water. Heating lowers the
viscosity and increases the apparent specific gravity
differential between oil and water. Heating also increases the
frequency of droplet collisons, which helps to rupture the
interfacial film.
Oil and
shown in
obtained
current
reliable
aluminum
grease and toxic organics removal performance data are
Tables VII-11 and VII-13 (pages 180 and 181). Data were
from sampling at operating plants and a review of the
literature. This type of treatment is proven to be
and is considered the current state-of-the-art for
forming emulsified oily wastewaters.
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Advantages and Limitions. Advantages gained from the use of
chemicals for breaking O-W emulsions are the high removal
efficiency potential and the possibility of reclaiming the oily
waste. Disadvantages are corrosion problems associated with
Acid-alum systems, skilled operator requirements for batch
treatment, chemical sludges produced, and poor cost-effectiveness
for low oil concentrations.
Operational Factors. Reliability: Chemical emulsion breaking is
a very reliable process. The main control parameters, pH and
temperature, are fairly easy to control.
Maintainability: Maintenance is required on pumps, motors, and
valves, as well as periodic cleaning of the treatment tank to
remove any accumulated solids. Energy use is limited to mixers
and pumps.
Solid Waste Aspects: The surface oil and oily sludge produced are
usually hauled away by a licensed contractor. If the recovered
oil has a sufficiently low percentage of water, it may be burned
for its fuel value or processed and reused.
Demonstration Status. Chemical emulsion breaking is a fully
developed technology widely used in other industry segments, such
as metal forming, that use oil-water emulsions. At least 17
canmaking plants have installed this technology.
MAJOR TECHNOLOGY EFFECTIVENESS
The performance of individual treatment technologies was
presented above. Performance of operating systems is discussed
here. Two different systems are considered: L&S (hydroxide
precipitation and sedimentation or lime and settle) and LS&F
(hydroxide precipitation, sedimentation and filtration or lime,
settle, and filter). Subsequently, an analysis of effectiveness
of such systems is made to develop one-day maximum, and ten-day
and thirty-day average concentration levels to be used in
regulating pollutants. Evaluation of the L&S and the LS&F
systems is carried out on the assumption that chemical reduction
of chromium, cyanide precipitation, and oil removal are installed
and operating properly where appropriate.
L&S Performance — Combined Metals Data Base
During the development of coil coating and other categorical
effluent limitations and standards, chemical analysis data were
collected of raw wastewater (treatment influent) and treated
wastewater (treatment effluent) from 55 plants (126 data days)
sampled by EPA (or its contractor) using EPA sampling and
chemical analysis protocols. These data are the initial data
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base for determining the effectiveness of L&S technology. Each
of the plants in the initial data; base belongs to at least one of
the following industry categories: aluminum forming, battery
.manufacturing, coil coating, copper forming, electroplating and
porcelain enameling. All of the plants employ pH adjustment and
hydroxide precipitation using lime or caustic, followed by
settling (tank, lagoon or clarifier) for solids removal. Most
also add a coagulant or flocculant prior to solids removal. The
raw (untreated) wastewater data from canmaking facilities sampled
by the Agency were compared to the raw wastewater data from the
combined metals facilities. The analysis is discussed below and
described in detail in the administrative record supporting this
rulemaking.
An analysis of this .data was presented in the development
documents for the proposed regulations for coil coating and
porcelain enameling (January 1981). In response to the proposal,
some commenters claimed that it was inappropriate to use data
from some categories for regulation of other categories. In
response to these comments, the Agency reanalyzed the data. An
analysis of variance was applied to the data for the 126 days of
sampling to test the hypothesis of homogeneous plant mean raw and
treated effluent levels across categories by pollutant. This
analysis is described in the report "A Statistical Analysis of
the Combined Metals Industries Effluent Data" which is in the
administrative record supporting this rulemaking. The main
conclusion drawn from the analysis of variance is that, with the
exception of electroplating, the categories are generally
homogeneous with regard to mean pollutant concentrations in both
raw and treated effluent. That is, when data from electroplating
facilities are included in the analysis, the hypothesis of
homogeneity across categories is rejected. When the
electroplating data are removed from the analysis the conclusion
changes substantially and the hypothesis of homogeneity across
categories is not rejected. On the basis of this analysis, the
electroplating data were removed from the data base used to
determine limitations. Cases that appeared to be marginally
different were not unexpected (such as copper in copper forming
and lead in lead battery manufacturing) were accommodated in
developing limitations by using the larger values obtained from
the marginally different category to characterize the entire data
set.
The statistical analysis provides support for the technical
engineering judgment that electroplating wastewaters are
different from most metal processing wastewaters. These
differences may be further explained by differences in the
constituents and relative amounts of pollutants in the raw
wastewaters,, Therefore, the wastewater data derived from plants
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that only electroplate are not used in developing limitations for
the canmaking subcategory.
After removing the electroplating data, data from 21 plants and
52 days of sampling remained. Eleven of these plants and 25 days
of sampling are from coil coating operations.
Prior to performing the homogeneity analysis, certain data were
deleted from the data base. The following criteria were used in
making these deletions:
Plants where malfunctioning processes or
at time of sampling were identified.
treatment systems
o Data days where pH was less than 7.0 or TSS was greater than
50 mg/1. (This is a prima facie indication of poor
operation).
For the purpose of developing treatment effectiveness, following
homogeneity additional deletions were made. These deletions were
made, almost exclusively, in cases where effluent data points
were associated with raw waste values too low to assure actual
pollutant removal (i.e., less than 0.1 mg/1 of pollutant in raw
waste). A few data points were also eliminated following the
homogeneity analysis where malfunctions not previously identified
were recognized.
Collectively, these selection criteria insure that the data are
from properly operating lime and settle treatment facilities.
The remaining data are displayed graphically in Figures VII-4 to
VH-12 (Pages 197 to 205). This common or combined metals data
base provides a more sound and usable basis for estimating
treatment effectiveness and statistical variability of lime and
settle technology than the available data from any one category.
One-day Effluent Values
The basis assumption underlying the determination of treatment
effectiveness is that the data for a particular pollutant are
lognormally distributed by plant. The lognormal has been found
to provide a satisfactory fit to plant effluent data in a number
of effluent guidelines categories. In the case of the combined
metal categories data base, there are too few data from any one
plant to verify formally the lognormal assumption. Thus, we
assumed measurements of each pollutant from a particular plant,
denoted by X, followed a lognormal distribution with log mean n
and log variance az. The mean, variance and 99th percent!le of X
are then:
mean of X = E(X) = exp (t> + az /2)
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variance of X = V(X) = exp (2 t> •+
-------
and
V(y) » pooled log variance
I ,
Ji - 1) S/
where S,c s log variance at plant i
-1)
y~i = log mean at plant i.
Thus, y and V(y) are the log mean and log variance, respectively,
of the lognormal distribution used to determine the treatment
effectiveness. The estimated mean and 99th percentile of this
distribution form the basis for the long term average and daily
maximum effluent limitations, respectively. The estimates are
A
mean * E(X)
exp(y) v n (0.5 V(y))
99th percent!le - X.gg = expCy +2.33 / V(y) ]
where * (.) is a Bessel function and exp is e, the base of the
natural logarithms (See Aitchison, J. and J.A.C. Brown, The
Loqnormal Distribution, Cambridge University Press, 1963). In
cases where zeros were present in the data, a generalized form of
the lognormal, known as the delta distribution was used (See
Aitchison and Brown, op. cit., Chapter 9).
For certain pollutants, this approach was modified slightly to
accommodate situations in which a category or categories stood
out as being marginally different from the others. For instance,
after excluding the electroplating data and other data that did
not reflect pollutant removal or proper treatment, the effluent
copper data from the copper forming plants were statistically
significantlv greater than the copper data from the other plants.
Thus, copper'effluent values shown in Table VII-14 (page 181) are
based only on the copper effluent data from the copper forming
plants. That is, the log mean for copper is the mean of the logs
of all copper values from the copper forming plants only and the
log variance is the pooled log variance of the copper forming
plant data only. In the case of cadmium, after excluding the
electroplating data and data that did not reflect removal or
proper treatment, there were insufficient data to estimate the
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log variance for cadmium. The variance used to determine the
values shown in Table VII-14 for cadmium was estimated by pooling
the within plant variances for all the other metals. Thus, the
cadmium variability is the average of the plant variability
averaged over all the other metals. The log mean for cadmium is
the mean of the logs of the cadmium observations only. A
complete discussion of the data and calculations for all the
metals is contained in the administrative record for this
rulemaking.
Average Effluent Values
Average effluent values that form the basis for the monthly
limitations were developed in a manner consistent with the method
used to develop one day treatment effectiveness in that the
lognormal distribution used for the one-day effluent values was
also used as the basis for the average values. That is, we
assume a number of consecutive measurements are drawn from the
distribution of daily measurements. The approach used for the 10
measurements values was employed previously for the
electroplating category (see "Development document for Existing
Sources Pretreatment Standards for the Electroplating Point
Source Category" EPA 440/1-79/003, U.S. Environmental Protection
Agency, Washington, D.C., August, 1979). That is, the
distribution of the average of 10 samples from a lognormal was
approximated by another lognormal distribution. Although the
approximation is not precise theoretically, there is empirical
evidence beised on effluent data from a number of categories that
the lognormal is 'an adequate approximation for the distribution
of small samples. In the course of previous work the
approximation was verified in a computer simulation study. We
also note that the average values were developed assuming
independence of the observations although no particular sampling
scheme was Jissumed.
Ten-Sample average:
The formulas for the 10-sample limitations were derived on the
basis of simple relationships between the mean and variance of
the distributions of the daily pollutant measurements and the
average of 10 measurements. We assume the daily concentration
measurements for a particular pollutant, denoted by X, follow a
lognormal distribution with log mean and log variance denoted by
v and a2, respectivey. Let X10 denote the mean of 10 consecutive
measurements. The following relationships then hold assuming the
daily measurements are independent:
mean of Y10 = E(Y10) = E(X)
variance of ~X10 = VU,0) = V(X) + 10.
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Where E(X) and V(X) are the mean and variance of X, respectively
defined above. We then assume that X10 follows a lognormai
distribution with log meanplo and log standard deviation cr,n.
The mean and variance of X10 are then
EQLio) =
V(X,0) = exp (2
0.5 tf2io
>
Now, jr,0 and
[exp( *210)
can be derived in terms of
and
as
= t> +
-------
measurements was, in this case, considered too small a number for
use of the Central Limit Theorem.
30 Sample Average Calculation
The formulas for the 30 sample average were based on an
application of the Central Limit Theorem. According to the
Theorem, the average of 30 observations drawn from the
distribution of . daily measurements, denoted by X30, _^is
approximately normally distributed. The mean and variance of X30
are:
mean of "X30 ^ E(3c30)_= E(X)
variance of X30 = V(X30) = VOO/30.
The 30 sample average value was determined by the estimate of the
approximate 99th percentile of the distribution of the 30 sample
average given by
X3Q(.99) = E(X) + 2.33
where
V(X) T 30
E(X) = exp(y) ij>n(0.5V(y))
and V?X) = exp(2y) [ iJ>n(2V(y)) - ^ ft^^
The formulas for E(X) and V(X) are estimates
respectively given in Aitchison, J. and
Lognormal Distribution, Cambridge University
45.
Application
of E(X) and V(X)
J.A.C. Brown, The
Press, 1963, page
In response to the proposed coil coating and porcelain enameling
regulations, the Agency received comments pointing out that
permits usually required less than 30 samples to be taken during
a month while the monthly average used as the basis for permits
and pretreatment requirements usually is based on the average of
30 samples.
In applying the treatment effectiveness values to regulations we
have considered the comments, examined the sampling frequency
required by many permits and considered the change in values of
averages depending on the number of consecutive sampling days in
the averages. The most common frequency of sampling required in
permits is about ten samples per month or slightly greater than
twice weekly. The 99th percentiles of the distribution of
averages of ten consecutive sampling days are not substantially
different from the 99th percentile of the distribution's 30 day
average. (Compared to the one-day maximum, the ten-day average
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is about 80 percent of the difference between one and 30 day
values). Hence the ten day average provides a reasonable basis
for a monthly average limitation and is typical of the sampling
frequency required by existing permits.
The monthly average limitation is to be achieved in all permits
and pretreatment standards regardless of the number of samples
required to be analyzed and averaged by the permit or the
pretreatment authority.
Additional Pollutants
A number of other pollutant parameters were considered with
regard to the performance of lime and settle treatment systems in
removing them from industrial wastewater. Performance data for
these parameters is not readily available, so data available to
the Agency in other categories has been selectively used to
determine the long term average performance of lime and settle
technology for each pollutant. These data indicate that the
concentrations shown in Table VII-15 (page 182) are reliably
attainable with hydroxide precipitation and settling. The
precipitation of silver appears to be accomplished by alkaline
chloride precipitation and adequate chloride ions must be
available for this reaction to occur.
In establishing which data were suitable for use in Table VI1-14
two factors were heavily weighed; (1) the nature of the
wastewater; (2) and the range of pollutants or pollutant matrix
in the raw wastewater. These data have been selected from
processes that generate dissolved metals in the wastewater and
which are generally free from complexing agents. The pollutant
matrix was evaluated by comparing the concentrations of
pollutants found in the raw wastewaters with the range of
pollutants in the raw wastewaters of the combined metals data
set. These data are displayed in Tables VII-16 (page 182) and
VTI-17 (page 183) and indicate that there is sufficient
similarity in the raw wastes to logically assume transferability
of the treated pollutant concentrations to the combined metals
data base. The available date on these added pollutants do not
allow homogeneity analysis as was performed on the combined
metals data base. The data source for each added pollutant is
discussed separately.
Antimony (Sb) - The achievable performance for antimony is based
on data from a battery and secondary lead plant. Both EPA
sampling data and recent permit data (1978-1982) confirm the
achievability of 0.7 mg/1 in the battery manufacturing wastewater
matrix included in the combined data set.
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Arsenic (As) - The achievable performance of 0.5 mg/1 for arsenic
is based on permit data from two nonferrous metals manufacturing
plants. The untreated wastewater matrix shown in Table VII-17
(page 183) is comparable with the combined data set matrix.
Beryllium (Be) - The treatability of beryllium is transferred
from the nonferrous metals manufacturing industry. The 0.3 mg/1
performance is achieved at a beryllium plant with the comparable
untreated wastewater matrix shown in Table VII-17.
Mercury (Hg) - The 0.06 mg/1 treatability of mercury is based on
data from four battery plants. The untreated wastewater matrix
at these plants was considered in the combined metals data set.
Selenium (Se) - The 0.30 mg/1 treatability of selenium is based
on recent permit data from one of the nonferrous metals
manufacturing plants also used for antimony performance. The
untreated wastewater matrix for this plant is shown in Table
VII-17.
Silver - The treatability of silver is based on a 0.1 mg/1
treatability estimate from the inorganic chemicals industry.
Additional data supporting a treatability as stringent or more
stringent than 0.1 mg/1 is also available from seven nonferrous
metals manufacturing plants. The untreated wastewater matrix for
these plants is comparable and summarized in Table VII-17.
Thallium (Tl) - The 0.50 mg/1 treatability for thallium is
transferred "from the inorganic chemicals industry. Although no
untreated wastewater data are available to verify_ comparability
with the combined metals data set plants, no other sources of
data for thallium treatability could be identified.
Aluminum (Al) - The 1.11 mg/1 treatability of aluminum is based
on the mean performance • of one aluminum forming plant and one
coil coating plant. Both of the plants are from .categories
considered in the combined metals data set, assuring untreated
wastewater matrix comparability.
Cobalt (Co) - The 0.05 mg/1 treatability is based on nearly
complete removal of cobalt at a porcelain enameling plant with a
mean untreated wastewater cobalt concentration of 4.31 mg/1. In
this case, the analytical detection using aspiration techniques
for this pollutant is used as the basis of the treatability.
Porcelain enameling was considered in the combined metals data
base, assuring untreated wastewater matrix comparability.
Fluoride (F) - The 14.5 mg/1 treatability of fluoride is based on
the mean performance of an electronics and electrical component
manufacturing plant. The untreated wastewater matrix for this
135
,\
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plant shown in Table VII-17 is comparable to the combined
data set.
metals
Phosphorus (P) - The 4.08 mg/1 treatability of phosphorus is
based on the mean of 44 samples including 19 samples from the
Combined Metals Data Base and 25 samples from the electroplating
data base. Inclusion of electroplating data with the combined
metals data was considered appropriate, since the removal
mechanism for phosphorus is a precipitation reaction with calcium
rather than hydroxide.
CANMAKING DATA - To determine the applicability of the combined
metals data base to canmaking an analysis was made using the
canmaking data shown in Table V-7 (page 48). Canmaking was
treated as an additional category-in the combined metals data
base and the same statistical procedures used to assess
homogeneity of the combined metals data were performed. The
results indicate substantial homogeneity among untreated
wastewater data from canmaking and the combined metals
categories. In fact, the addition of canmaking as another
category had no effect on the overall tests of homogeneity. That
is, the results of overall homogeneity were the same with and
without the canmaking data. These results support the hypothesis
of similar raw waste characteristics among canmaking and the
combined metals categories and suggest that lime and settle
treatment would reduce concentrations of toxic metal pollutants
in canmaking to levels comparable to those achievable by lime and
settle in the combined metals categories. Additionally, the
concentrations of aluminum, fluoride and phosphorus found in
canmaking raw wastewaters are comparable to or lower than values
for these pollutants found in the combined metals data base
suggesting that L&S technology would remove these pollutants to
the levels shown in Table VII-21. Similarly, the lime, settle,
and filter discussion which follows is applicable to canmaking
wastewater the same as any other wastewater in the common metals
data base. The analysis of the canmaking wastewater data and of
the combined metals data base is detailed in the administrative
record of this rulemaking.
LS&F Performance
Tables VII-18 and VII-19 (pages 184 and 185) show long term data
from two plants which have well operated precipitation-settling
treatment followed by filtration. The wastewaters from both
plants contain pollutants from metals processing and finishing
operations (multi-category). Both plants reduce hexavalent
chromium before neutralizing and precipitating metals with lime.
A clarifier is used to remove much of the solids load and a
filter is used to "polish" or complete removal of suspended
solids. Plant A uses a pressure filter, while Plant B uses a
rapid sand filter.
Raw wastewater data
facility and the
indication of the nature of the wastewater
was collected only occasionally at each
raw wastewater data is presented as an
treated. Data from
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plant A was received as a statistical summary and is presented as
received. Raw laboratory data was collected at plant B and
reviewed for spurious points and discrepancies. The method of
treating the data base is discussed below under lime, settle, and
filter treatment effectiveness.
Table VII-20 (page 186) shows long-term data for zinc and cadmium
removal at Plant C, a primary zinc smelter, which operates a LS&F
system. This data represents about 4 months (103 data days)
taken immediately before the smelter was closed. It has been
arranged similarily to Plants A and B for comparison and use.
These data are presented to demonstrate the performance of
precipitation-settling-filtration (LS&F) technology under actual
operating conditions and over a long period of time.
It should be noted that the iron content of the raw wastewater of
plants A and B is high while that for Plant C is low. This
results, for plants A and B, in coprecipitation of toxic metals
with iron. Precipitation using high-calcium lime for pH control
yields the results shown above. Plant operating personnel
indicate that this chemical treatment combination (sometimes with
polymer assisted coagulation) generally produces better and more
consistant metals removal than other combinations of sacrificial
metal ions and alkalis.
The LS&F performance data presented here are based on systems
that provide polishing filtration after effective L&S treatment.
We have previously shown that L&S treatment is equally applicable
to wastewaters from the five categories because of the
homogeneity of its raw and treated wastewaters, and other
factors. Because of the similarity of the wastewaters after L&S
treatment, the Agency believes these wastewaters are equally
amenable to treatment using polishing filters added to the L&S
treatment system. The Agency concludes that LS&F data based on
porcelain enameling and non-ferrous smelting and refining is
directly applicable to the aluminum forming, copper forming,
battery manufacturing, coil coating, and metal molding and
casting categories, and the canmaking subcategory as well as it
is to porcelain enameling and nonferrous melting and refining.
Analysis of Treatment System Effectiveness
Data are presented in Table VI1-14 showing the mean, one day, 10
day, and 30 day values for nine pollutants examined in the L&S
combined metals data base. The pooled variability factor for
seven metal pollutants (excluding cadmium because of the small
number of data points) was determined and is used to estimate one
day, 10 day and 30 day values. (The variability factor is the
ratio of the value of concern to the mean: the pooled variability
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factors are: one day maximum - 4.100; ten day average - 1.821;
and 30 day average - 1.618.) For values not calculated from the
common data base as previously discussed, the mean value for
pollutants shown in Table VII-15 were multiplied by the
variability factors to derive the value to obtain the one, ten
and 30 day values. These are tabulated in Table VII-21.
LS&F technology data are presented in Tables VII-18 and VII-19.
These data represent two operating plants (A and B) in which the
technology has been installed and operated for some years. Plant
A data was received as a statistical summary and is presented
without change. Plant B data was received as raw laboratory
analysis data. Discussions with plant personnel indicated that
operating experiments and changes in materials and reagents and
occasional operating errors had occured during the data
collection period. No specific information was available on
those variables. To sort out high values probably caused by
methodological factors from random statistical variability, or
data noise, the plant B data were analyzed. For each of four
pollutants (chromium, nickel, zinc, and iron), the mean and
standard deviation (sigma) were calculated for the entire data
set. A data day was removed from the complete data set when any
individual pollutant concentration for that day exceeded the sum
of the mean plus three sigma for that pollutant. Fifty-one data
days (from a total of about 1300) were eliminated by this method.
Another approach was also used as a check on the above method of
eliminating certain high values. The minimum values of raw
wastewater concentrations from Plant B for the same four
pollutants were compared to the total set of values for the
corresponding pollutants. Any day on which the pollutant
concentration exceeded the minimum value selected from raw
wastewater concentrations for that pollutant was discarded.
Forty-five days of data were eliminated by that procedure.
Forty-three days of data in common were eliminated by either
procedures. Since common engineering practice (mean plus 3
sigma) and logic (treated wastewater concentrations should be
less than raw wastewater concentrations) seem to coincide, the
data base with the 51 spurious data days eliminated is the basis
for all further analysis. Range, mean, standard deviation and
mean plus two standard deviations are shown in Tables VII-18 and
VII-19 for Cr, Cu, Ni, Zn and Fe.
The Plant B data was separated into 1979, 1978, and total data
base (six years) segments. With the statistical analysis from
Plant A for 1978 and 1979 this in effect created five data sets
in which there is some overlap between the individual years and
total data sets from Plant B. By comparing these five parts it
is apparent that they are quite similar and all appear to be from
the same family of numbers. The largest mean found among the
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five data sets for each pollutant was selected as the long term
mean for LS&F technology and is used as the LS&F mean in Table
VII-21.
Plant C data was used as a basis for cadmium removal performance
and as a check on the zinc values derived from Plants A and B.
The cadmium data is displayed in Table VI1-20 (page 186) and is
incorporated into Table VII-21 for LS&F. The zinc data was
analyzed for compliance with the 1-day and 30-day values in Table
VI1-20; no zinc value of the 103 data points exceeded the 1-day
zinc value of 1.02 mg/1. The 103 data points were separated into
blocks of 30 points and averaged. Each of the 3 full 30-day
averages was less than the Table VII-21 value of 0.31 mg/1.
Additionally the Plant C raw wastewater pollutant concentrations
(Table VI1-19) are well within the range of raw wastewater
concentrations of the combined metals data base (Table VI1-15),
further supporting the conclusion that Plant C wastewater data is
compatible with similar data from Plants A and B.
Concentration values for regulatory use are displayed in Table
VII-21. Mean one day, ten day and 30 day values for L&S for nine
pollutants were taken from Table VII-13; the remaining L&S values
were developed using the mean values in Table VII-15 and the mean
variability factors discussed above.
LS&F mean values for Cd, Cr, Ni, Zn and Fe are derived from
plants A, B, and C as discussed above. One, ten and thirty day
values are derived by applying the variability factor developed
from the pooled data base for the specific pollutant to the mean
for that pollutant. Other LS&F values are calculated using the
long term average or mean and the appropriate variability
factors. Mean values for LS&F for pollutants not already
discussed are derived by reducing the L&S mean by one-third. The
one-third reduction was established after examining the percent
reduction in concentrations going from L&S to LS&F data for Cd,
Cr, Ni, Zn, and Fe. The average reduction is 0.3338 or one
third.
Copper levels achieved at Plants A and B may be lower than
generally achievable because of the high iron content and low
copper content of the raw wastewaters. Therefore, the mean
concentration value achieved is not used; LS&F mean used is
derived from the L&S technology.
L&S cyanide mean levels shown in Table VI1-8 are ratioed to one
day, ten day and 30 day values using mean variability factors.
LS&F mean cyanide is calculated by applying the ratios of
removals L&S and LS&F as discussed previously for LS&F metals
limitations. The cyanide performance was arrived at by using the
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average metal variability factors. The treatmentmethod used
here is cyanide precipitation. Because cyanide precipitation is
limited by the same physical processes as the metal
precipitation, it is expected that the variabilities will be
similar. Therefore, the average of the metal variability factors
has been used as a basis for calculating the cyanide one day, ten
day and thirty day average treatment effectiveness values.
The filter performance for removing TSS as shown in Table VI1-9
(page 179) yields a mean effluent concentration of 2.61 mg/1 and
calculates to a 10 day average of 4.33, 30 day average of 3.36
mg/1; a one day maximum of 8.88. These calculated values more
than amply support the classic values of 10 and 15, respectively,
which are used for LS&F.
Although iron concentrations were decreased in some LS&F
operations, some facilities using that treatment introduce iron
compounds to aid settling. Therefore, the one day, ten day and
30 day values for iron at LS&F were held at the L&S level so as
to not unduly penalize the operations which use the relatively
less objectionable iron compounds to enhance removals of toxic
metals.
MINOR TECHNOLOGIES
Several other treatment technologies were considered for possible
application in BPT or BAT. These technologies are presented here
with a full discussion for most of them. A few are described
only briefly because of limited technical development.
10. Carbon Adsorption
The use of activated carbon to remove dissolved organics from
water and wastewater is a long demonstrated technology. It is
one of the most efficient organic removal processes available.
This sorption process is reversible, allowing activated carbon to
be regenerated for reuse by the application of heat and steam or
solvent. Activated carbon has also proved to be an effective
adsorbent for many toxic metals, including mercury. Regeneration
of carbon which has adsorbed significant metals, however, may be
difficult.
The term activated carbon applies to any amorphous form of carbon
that has been specially treated to give high adsorption
capacities. Typical raw materials include coal, wood, coconut
shells, petroleum base residues and char from sewage sludge
pyrolysis. A carefully controlled process of dehydration,
carbonization, and oxidation yields a product which is called
activated carbon. This material has a high capacity for
adsorption due primarily to the large surface area available for
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adsorption, 500-1500 m2/g resulting from a large number of
internal pores. Pore sizes generally range from 10-100 angstroms
in radius.
Activated carbon removes contaminants from water by the process
of adsorption, or the attraction and accumulation of one
substance on the surface of another. Activated carbon
preferentially adsorbs organic compounds and, because of this
selectivity, is particularly effective in removing organic
compounds from aqueous solution.
Carbon adsorption requires pretreatment to remove excess
suspended solids, oils, and greases. Suspended solids in the
influent should be less than 50 mg/1 to minimize backwash
requirements; a downflow carbon bed can handle much higher levels
(up to 2000 mg/1), but requires frequent backwashing.
Backwashing more than two or three times a day is not desirable;
at 50 mg/1 suspended solids one backwash will suffice. Oil and
grease should be less than about 10 mg/1. A high level of
dissolved inorganic material in the influent may cause problems
with thermal carbon reactivation (i.e., scaling and loss of
activity) unless appropriate preventive steps are taken. Such
steps might include pH control, softening, or the use of an acid
wash on the carbon prior to reactivation.
Activated carbon is available in both powdered and granular form.
An adsorption column packed with granular activated carbon is
shown in Figure VII-17 (page 210). Powdered carbon is less
expensive per unit weight and may have slightly higher adsorption
capacity, but it is more difficult to handle and to regenerate.
Application and Performance. Carbon adsorption is used to remove
mercury from wastewaters. The removal rate is influenced by the
mercury level in the influent to the adsorption unit. Removal
levels found at three manufacturing facilities are shown in Table
VII-24 (page 190). In the aggregate these data indicate that
very low effluent levels could be attained from any raw waste by
use of multiple adsorption stages. This is characteristic of
adsorption processes.
Isotherm tests have indicated that activated carbon is very
effective in adsorbing 65 percent of the organic priority
pollutants and is reasonably effective for another 22 percent.
Specifically, for the organics of particular interest, activated
carbon was very effective in removing all phthalates. It was
resonably effective on 1,1,1-trichloroethane,
bis(2-chloroethyl)ether, and toluene.
Table VII-22 (page 188) summarizes the treatability effectiveness
for most of the organic priority pollutants by activated carbon
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as compiled by EPA. Table VII-23 (page 189) summarizes classes
of organic compounds together with examples of organics that are
readily adsorbed on carbon. Table VI1-24 lists the effectiveness
of activated carbon.
Advantages and Limitations. The major benefits of carbon
treatment include applicability to a wide variety of organics,
and high removal efficiency. Inorganics such as cyanide,
chromium, and mercury are also removed effectively. Variations
in concentration and flow rate are well tolerated. The system is
compact, and recovery of adsorbed materials is sometimes
practical. However, destruction of adsorbed compounds often
occurs during thermal regeneration. If carbon cannot be
thermally desorbed, it must be disposed of along with any
adsorbed pollutants. The capital and operating costs of thermal
regeneration are relatively high. Cost surveys show that thermal
regeneration is generally economical when carbon usage exceeds
about 1,000 Ib/day. Carbon cannot remove low molecular weight or
highly soluble organics. It also has a low tolerance for
suspended solids, which must be removed to at least 50 mg/1 in
the influent water.
Operational Factors. Reliability: This system should be very
reliable with upstream protection and proper operation and
maintenance procedures.
Maintainability: This system requires periodic regeneration or
replacement of spent carbon and is dependent upon raw waste load
and process efficiency.
Solid Waste Aspects: Solid waste from this process is
contaminated activated carbon that requires disposal. Carbon
undergoes regeneration, reduces the solid waste problem by
reducing the frequency of carbon replacement.
Demonstration Status. Carbon adsorption systems have been
demonstrated to be practical and economical in reducing COD, BOD
and related parameters in secondary municipal and industrial
wastewaters; in removing toxic or refractory organics from
isolated industrial wastewaters; in removing and recovering
certain organics from wastewaters; and in the removing and some
times recovering, of selected inorganic chemicals from aqueous
wastes. Carbon adsorption is a viable and economic process for
organic waste streams containing up to 1 to 5 percent of
refractory or toxic organics. Its applicability for removal of
inorganics such as metals has also been demonstrated.
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11
Centrifugation
Centrifugation is the application of centrifugal force to
separate solids and liquids in a liquid-solid mixture or to
effect concentration of the solids. The application of
centrifugal force is effective because of the density
differential normally found between the insoluble solids and the
liquid in which they are contained. As a waste treatment
procedure, Centrifugation is applied to dewatering of sludges.
One type of centrifuge is shown in Figure VII-18 (page 211).
There are three common types of centrifuges: the disc, basket,
and conveyor type. All three operate by removing solids under
the influence of centrifugal force. The fundamental difference
between the three types is the method by which solids are
collected in and discharged from the bowl.
In the disc centrifuge, the sludge feed is distributed between
narrow channels that are present as spaces between stacked
conical discs. Suspended particles are collected and discharged
continuously through small orifices in the bowl wall. The
clarified effluent is discharged through an overflow weir.
A second type of centrifuge which is useful in dewatering sludges
is the basket centrifuge. In this type of centrifuge, sludge
feed is introduced at the bottom of the basket, and solids
collect at the bowl wall while clarified effluent overflows the
lip ring at the top. Since the basket centrifuge does not have
provision for continuous discharge of collected cake, operation
requires interruption of the feed for cake discharge for a minute
or two in a 10 to 30 minute overall cycle.
The third type of centrifuge commonly used in sludge dewatering
is the conveyor type. Sludge is fed through a stationary feed
pipe into a rotating bowl in which the solids are settled out
against the bowl wall by centrifugal force. From the bowl wall,
they are moved by a screw to the end of the machine, at which
point whey are discharged. The liquid effluent is discharged
through ports after passing the length of the bowl under
centrifugal force.
Application And Performance. Virtually all industrial waste
treatment systems producing sludge can use Centrifugation to
dewater it. Centrifugation is currently being used by a wide
range of industrial concerns.
The performance of sludge dewatering by Centrifugation depends on
the feed rate, the rotational velocity of the drum, and the
sludge composition and concentration. Assuming proper design and
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operation, the
20-35 percent.
solids content of the sludge can be increased to
Advantages And Limitations. Sludge dewatering centrifuges have
minimal space requirements and show a high degree of effluent
clarification. The operation is simple, clean, and relatively
inexpensive. The area required for a centrifuge system
installation is less than that required for a filter system or
sludge drying bed of equal capacity, and the initial cost is
lower.
Centrifuges have a high power cost that partially offsets the low
initial cost. Special consideration must also be given to
providing sturdy foundations and soundproofing because of the
vibration and noise that result from centrifuge operation.
Adequate electrical power must also be provided since large
motors are required. The major difficulty encountered in the
operation of centrifuges has been the disposal of the concentrate
which is relatively high in suspended, non-settling solids.
Operational Factors. Reliability: Centrifugation is highly
reliable with proper control of factors such as sludge feed,
consistency, and temperature. Pretreatment such as grit removal
and coagulant addition may be necessary, depending on the
composition of the sludge and on the type of centrifuge employed.
Maintainability: Maintenance consists of periodic lubrication,
cleaning, and inspection. The frequency and degree of inspection
required varies depending on the type of sludge solids being
dewatered and the maintenance service conditions. If the sludge
is abrasive, it is recommended that the first inspection of the
rotating assembly be made after approximately 1,000 hours of
operation. If the sludge is not abrasive or corrosive, then the
initial inspection might be delayed. Centrifuges not equipped
with a continuous sludge discharge system require periodic
shutdowns for manual sludge cake removal.
Solid Waste Aspects: Sludge dewatered in the centrifugation
process may be disposed of by landfill. The clarified effluent
(centrate), if high in dissolved or suspended solids, may require
further treatment prior to discharge.
Demonstrat ion Status. Centrifugation is currently used in a
great many commercial applications to dewater sludge. Work is
underway to improve the efficiency, increase the capacity, and
lower the costs associated with Centrifugation.
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1 2. Coalescing
The basic principle of coalescence involves the preferential
wetting of a coalescing medium by oil droplets which accumulate
on the medium and then rise to the surface of the solution as
they combine to form larger particles. The most important
requirements for coalescing media are wettability for oil and
large surface area. Monofilament line is sometimes used as a
coalescing medium.
Coalescing stages may be integrated with a wide variety of
gravity oil separation devices, and some systems may incorporate
several coalescing stages. In general a preliminary oil skimming
step is desirable to avoid overloading the coalescer.
One commercially marketed system for oily waste treatment
combines coalescing with inclined plate separation and
filtration. In this system, the oily wastes flow into an
inclined plate settler. This unit consists of a stack of
inclined baffle plates in a cylindrical container with an oil
collection chamber at the top. The oil droplets rise and impinge
upon the undersides of the plates. They then migrate upward to a
guide rib which directs the oil to the oil collection chamber,
from which oil is discharged for reuse or disposal.
The oily water continues on through another cylinder containing
replaceable filter cartridges, which remove suspended particles
from the waste. From there the wastewater enters a final
cylinder in which the coalescing material is housed. As the oily
water passes? through the many small, irregular, continuous
passages in the coalescing material, the oil droplets coalesce
and rise to an oil collection chamber.
Application and Performance. Coalescing is used to treat oily
wastes which do not separate readily in simple gravity systems.
The three stage system described above has achieved effluent
concentrations of 10-15 mg/1 oil and grease from raw waste
concentrations of 1000 mg/1 or more.
Advantages and Limitations. Coalescing allows removal of oil
droplets too finely dispersed for conventional gravity
separation-skimming technology. It also can significantly reduce
the residence times (and therefore separator volumes) required to
achieve separation of oil from some wastes. Because of its
simplicity, coalescing provides generally high reliability and
low capital and operating costs. Coalescing is not generally
effective in removing soluble or chemically stabilized emulsified
oils. To avoid plugging, coalescers must be protected by
pretreatment from very high concentrations of free oil and grease
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and suspended solids. Frequent replacement of prefilters may be
necessary when raw waste oil concentrations are high.
Operational Factors. Reliability: Coalescing is inherently
highly reliable since there are no moving parts, and the
coalescing substrate (monofi lament, etc.) is inert in the
process and therefore not subject to frequent regeneration or
replacement requirements. Large loads or inadequate
pretreatment, however, may result in plugging or bypass of
coalescing stages.
Maintainability: Maintenance requirements are generally limited
to replacement of the coalescing medium on an infrequent basis.
Solid Waste Aspects: No appreciable solid waste is generated by
this process.
Demonstration Status. Coalescing has been fully demonstrated in
industries generating oily wastewater.
13. Cyanide Oxidation By_ Chlorine
Cyanide oxidation using chlorine is widely used in industrial
waste treatment to oxidize cyanide. Chlorine can be utilized in
either the elemental or hypochlorite forms. This classic
procedure can be illustrated by the following two step chemical
reaction:
2.
C12
3C12
NaCN + 2NaOH — > NaCNO + 2NaCl + H,20
6NaOH + 2NaCNO --> 2NaHCO3 + N2 + 6NaCl
2H20
The reaction presented as equation (2) for the oxidation of
cyanate is the final step in the oxidation of cyanide. A
complete system for the alkaline chlorination of cyanide is shown
in Figure VII-19 (page 212).
The alkaline chlorination process oxidizes cyanides to carbon
dioxide and nitrogen. The equipment often consists of an
equalization tank followed by two reaction tanks, although the
reaction can be carried out in a single tank. Each tank has an
electronic recorder-controller to maintain required conditions
with respect to pH and oxidation reduction potential (ORP). In
the first reaction tank, conditions are adjusted to oxidize
cyanides to cyanates. To effect the reaction, chlorine is
metered to the reaction tank as required to maintain the ORP in
the range of 350 to 400 millivolts, and 50 percent aqueous
caustic soda is added to maintain a pH range of 9.5 to 10. In
the second reaction tank, conditions are maintained to oxidize
cyanate to carbon dioxide and nitrogen. The desirable ORP and pH
1.46
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for this reaction are 600 millivolts and a pH of 8.0. Each of
the reaction tanks is equipped with a propeller agitator designed
to provide approximately one turnover per minute. Treatment by
the batch process is accomplished by using two tanks, one for
collection of water over a specified time period, and one tank
for the treatment of an accumulated batch. If dumps of
concentrated wastes are frequent, another tank may be required to
equalize the flow to the treatment tank. When the holding tank
is full, the liquid is transferred to the. reaction tank for
treatment. After treatment, the supernatant is discharged and
the sludges are collected for removal and ultimate disposal.
Application and Performance. The oxidation of cyanide waste by
chlorine is a classic process and is found in most industrial
plants using cyanide. This process is capable of achieving
effluent levels that are nondetectable. The process is
potentially applicable to canmaking facilities where cyanide is a
component in conversion coating formulations.
Advantages and Limitations. Some advantages of chlorine
oxidation for handling process effluents are operation at ambient
temperature, suitability for automatic control, and low cost.
Disadvantages include the need for careful pH control, possible
chemical interference in the treatment of mixed wastes, and the
potential hazard of storing and handling chlorine gas.
Operational Factors. Reliability: Chlorine oxidation is highly
reliable with proper monitoring and control, and proper
pretreatment to control interfering substances.
Maintainability: Maintenance consists of periodic removal of
sludge and recalibration of instruments.
Solid Waste Aspects: There is no solid waste problem associated
with chlorine oxidation.
Demonstrat ion
chlorine is
Status.
a widely
„. „ . The oxidation of cyanide wastes by
chlorine is a widely used process in plants using cyanide in
cleaning and metal processing baths.
14. Cyanide Oxidation By Ozone
Ozone is a highly reactive oxidizing agent which is approximately
ten times more soluble than oxygen on a weight basis in water.
Ozone may be produced by several methods, but the silent
electrical discharge method is predominant in the field. The
silent electrical discharge process produces ozone by passing
oxygen or air between electrodes separated by an insulating
material. A complete ozonation system is represented in Figure
VI1-20 (page 213).
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Application and Performance. Ozonation has been applied
commercially to oxidize cyanides, phenolic chemicals, and organo-
metal complexes. Its applicability to photographic wastewaters
has been studied in the laboratory with good results. Ozone is
used in industrial waste treatment primarily to oxidize cyanide
to cyanate and to oxidize phenols and dyes to a variety of
colorless nontoxic products.
Oxidation of cyanide to cyanate is illustrated below:
CN- + 03 —> CNO- + 02
Continued exposure to ozone will convert the cyanate formed to
carbon dioxide and ammonia; however, this is not economically
practical.
Ozone oxidation of cyanide to cyanate requires 1.8 to 2.0 pounds
ozone per pound of CN-; complete oxidation requires 4.6 to 5.0
pounds ozone per pound of CN-. Zinc, copper, and nickel cyanides
are easily destroyed to a nondetectable level, but cobalt and
iron cyanides are more resistant to ozone treatment.
Advantages and Limitations. Some advantages of ozone oxidation
for handling process effluents are its suitability to automatic
control and on-site generation and the fact that reaction
products are not chlorinated organics and no dissolved solids are
added in the treatment step. Ozone in the presence of activated
carbon, ultraviolet, and other promoters shows promise of
reducing reaction time and improving ozone utilization, but the
process at present is limited by high capital expense, possible
chemical interference in the treatment of mixed wastes, and an
energy requirement of 25 kwh/kg of ozone generated. Cyanide is
not economically oxidized beyond the cyanate form.
Operational Factors. Reliability:- Ozone oxidation is highly
reliable with proper monitoring and control, and proper
pretreatment to control interfering substances.
Maintainability: Maintenance consists of periodic removal of
sludge, and periodic renewal of filters and desiccators required
for the input of clean dry air; filter life is a function of
input concentrations of detrimental constituents.
Solid Waste Aspects: Pretreatment to eliminate substances which
will interfere with the process may be necessary. Dewatering of
sludge generated in the ozone oxidation process or in an "in
line" process may be desirable prior to disposal.
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15. Cyanide Oxidation By_ Ozone With UV Radiation
One of the modifications of the ozonation process is the
simultaneous application of ultraviolet light and ozone for the
treatment of wastewater, including treatment of halogenated
organics. The combined action of these two forms produces
photosens itization, hydroxy1at i on,
The process is unique because several
reactions by photolysis,
oxygenation and oxidation.
reactions and reaction species are active simultaneously.
Ozonation is facilitated by ultraviolet absorption because both
the ozone and the reactant molecules are raised to a higher
energy state so that they react more rapidly. In addition, free
radicals for use in the reaction are readily hydrolyzed by the
water present. The energy and reaction intermediates created by
the introduction of both ultraviolet and ozone greatly reduce the
amount of ozone required compared with a system using ozone
alone. Figure VII-21 (page 214) shows a three-stage UV-ozone
system. A system to treat mixed cyanides requires pretreatment
that involves chemical coagulation, sedimentation, clarification,
equalization, and pH adjustment.
Application and_ Performance. The ozone-UV radiation process was
developed primarily for cyanide treatment in the electroplating
and color photo-processing areas. It has been successfully
applied to mixed cyanides and organics from organic chemicals
manufacturing processes. The process is particularly useful for
treatment of complexed cyanides such as ferricyanide, copper
cyanide and nickel cyanide, which are resistant to ozone alone.
Ozone combined with UV radiation is a relatively new technology.
Four units are currently in operation and all four treat cyanide
bearing waste.
Ozone-UV treatment could be used in canmaking plants to destroy
cyanide present in waste streams from some conversion coating
operations.
16> Cyanide Oxidation By_ Hydrogen Peroxide
Hydrogen peroxide oxidation removes both cyanide and metals in
cyanide containing wastewaters. In this process, cyanide bearing
waters are heated to 49 - 54°C (120 - 130°F) and the pH is
adjusted to 10.5 - 11.8. Formalin (37 percent formaldehyde) is
added while the tank is vigorously agitated. After 2-5 minutes,
a proprietary peroxygen compound (41 percent hydrogen peroxide
with a catalyst and additives) is added. After an hour of
mixing, the reaction is complete. The cyanide is converted to
cyanate and the metals are precipitated as oxides or hydroxides.
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The metals are then removed from solution by either
filtration.
settling or
The main equipment required for this process is two holding tanks
equipped with heaters and air spargers or mechanical stirrers.
These tanks may be used in a batch or continuous fashion, with
one tank being used for treatment while the other is being
filled. A settling tank or a filter is needed to concentrate the
precipitate.
Application and Performance. The hydrogen peroxide oxidation
process is applicable to cyanidebearing wastewaters, especially
those containing metal-cyanide complexes. In terms of waste
reduction performance, this process can reduce total cyanide to
less than 0.1 mg/1 and the zinc or cadmium to less than 1.0 mg/1.
Advantages and Limitations. Chemical costs are similar to those
for alkaline chlorination using chlorine and lower than those for
treatment with hypochlorite. All free cyanide reacts and is
completely oxidized to the less toxic cyanate state. In
addition, the metals precipitate and settle quickly, and they may
be recoverable in many instances. However, the process requires
energy expenditures to heat the wastewater prior to treatment.
Demonstration Status. This treatment process was
1971 and is used in several facilities.
17. Evaporation
introduced in
Evaporation is a concentration process. Water is evaporated from
a solution, increasing the concentration of solute in the
remaining solution. If the resulting water vapor is condensed
back to liquid water, the evaporation-condensation process is
called distillation. However, to be consistent with industry
terminology, evaporation is used in this report to describe both
processes. Both atmospheric and vacuum evaporation are commonly
used in industry today. Specific evaporation techniques are
shown in Figure VII-22 (page 215) and discussed below.
Atmospheric evaporation could be accomplished simply by boiling
the liquid. However, to aid evaporation, heated liquid is
sprayed on an evaporation surface, and air is blown over the
surface and subsequently released to the atmosphere. Thus,
evaporation occurs by humidification of the air stream, similar
to a drying process. Equipment for carrying out atmospheric
evaporation is quite similar for most applications. The major
element is generally a packed column with an accumulator bottom.
Accumulated wastewater is pumped from the base of the column,
through a heat exchanger, and back into the top of the column,
where it is sprayed into the packing. At the same time, air
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drawn upward through the packing by a fan is heated as it
contacts the hot liquid. The liquid partially vaporizes and
humidifies the air stream. The fan then blows the hot, humid air
to the outside atmosphere. A scrubber is often unnecessary
because the packed column itself acts as a scrubber.
Another form of atmospheric evaporator also works on the air
humidification principle, but the evaporated water is recovered
for reuse by condensation. These air humidification techniques
operate well below the boiling point of water and can utilize
waste process heat to supply the energy required.
In vacuum evaporation, the evaporation pressure is lowered to
cause the liquid to boil at reduced temperature. All of the
water vapor is condensed and, to maintain the vacuum condition,
noncondensible gases (air in particular) are removed by a vacuum
pump. Vacuum evaporation may be either single or double effect.
In double effect evaporation, two evaporators are used, and the
water vapor from the first evaporator (which may be heated by
steam) is used to supply heat to the second evaporator. As it
supplies heat, the water vapor from the first evaporator
condenses. Approximately equal quantities of wastewater are
evaporated in each unit; thus, the double effect system
evaporates twice the amount of water that a single effect system
does, at nearly the same cost in energy but with added capital
cost and complexity. The double effect technique is
thermodynamically possible because the second evaporator is
maintained at lower pressure (higher vacuum) and, therefore,
lower evaporation temperature. Another means of increasing
energy efficiency is vapor recompression (thermal or mechanical),
which enables heat to be transferred from the condensing water
vapor to the evaporating wastewater. Vacuum evaporation
equipment may be classified as submerged tube or climbing film
evaporation units.
In the most commonly used submerged tube evaporator, the heating
and condensing coil are contained in a single vessel to reduce
capital cost. The vacuum in the vessel is maintained by an
eductor-type pump, which creates the required vacuum by the flow
of the condenser cooling water through a venturi. Waste water
accumulates in the bottom of the vessel, and it is evaporated by
means of submerged steam coils. The resulting water vapor
condenses as it contacts the condensing coils in the top of the
vessel. The condensate then drips off the condensing coils into
a collection trough that carries it out of the vessel.
Concentrate is removed from the bottom of the vessel.
The major elements of the climbing film evaporator are the
evaporator, separator, condenser, and vacuum pump. Wastewater is
"drawn" into the system by the vacuum so that a constant liquid
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level is maintained in the separator. Liquid enters the steam-
jacketed evaporator tubes, and part of it evaporates so that a
mixture of vapor and liquid enters the separator. The design of
the separator is such that the liquid is continuously circulated
from the separator to the evaporator. The vapor entering the
separator flows out through a mesh entrainment separator to the
condenser, where it is condensed as it flows down through the
condenser tubes. The condensate, along with any entrained air,
is pumped out of the bottom of the condenser by a liquid ring
vacuum pump. The liquid seal provided by the condensate keeps
the vacuum in the system from being broken.
Application and Performance. Both atmospheric and vacuum
evaporation are used in many industrial plants, mainly for the
concentration and recovery of process solutions. Many of these
evaporators also recover water for rinsing. Evaporation has also
been applied to recovery of phosphate metal'cleaning solutions.
In theory, evaporation should yield a concentrate and a deionized
condensate. Actually, carry-over has resulted in condensate
metal concentrations as high as 10 mg/1, although the usual level
is less than 3 mg/1, pure enough for most final rinses. The
condensate may also contain organic brighteners and antifoaming
agents. These can be removed with an activated carbon bed, if
necessary. Samples from one plant showed 1,900 mg/1 zinc in the
feed, 4,570 mg/1 in the concentrate, and 0.4 mg/1 in the
condensate. Another plant had 416 mg/1 copper in the feed and
21,800 mg/1 in the concentrate. Chromium analysis for that plant
indicated 5,060 mg/1 in the feed and 27,500 mg/1 in the
concentrate. Evaporators are available in a range of capacities,
typically from 15 to 75 gph, and may be used in parallel
arrangements for processing of higher flow rates.
Advantages and Limitations. Advantages of the evaporation
process are that it permits recovery of a wide variety of process
chemicals, and it is often applicable to concentration or removal
of compounds which cannot be accomplished by any other means.
The major disadvantage is that the evaporation process consumes
relatively large amounts of energy for the evaporation of water.
However, the recovery of waste heat from many industrial
processes (e.g., diesel generators, incinerators, boilers and
furnaces) should be considered as a source of this heat for a
totally integrated evaporation system. Also/ in some cases solar
heating could be inexpensively and effectively applied to
evaporation units. For some applications, pretreatment may be
required to remove solids or bacteria which tend to cause fouling
in the condenser or evaporator. The buildup of scale on the
evaporator surfaces reduces the heat transfer efficiency and may
present a maintenance problem or increase operating cost.
However, it has been demonstrated that fouling of the heat
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transfer surfaces can be avoided or minimized for certain
dissolved solids by maintaining a seed slurry which provides
preferential sites for precipitate deposition. In addition, low
temperature differences in the evaporator will eliminate nucleate
boiling and supersaturation effects. Steam distiliable
impurities in the process stream are carried over with the
product water and must be handled by pre or post treatment.
Operational Factors. Reliability: Proper maintenance will
ensure a high degree of reliability for the system. Without such
attention, rapid fouling or deterioration of vacuum seals may
occur, especially when handling corrosive liquids.
Maintainability: Operating parameters can be automatically
controlled. Pretreatment may be required, as well as periodic
cleaning of the system. Regular replacement of seals, especially
in a corrosive environment, may be necessary.
Solid Waste Aspects: With only a few exceptions, the process
does not generate appreciable quantities of solid waste.
Demonstration Status.
commercially available
Evaporation is a fully developed,
wastewater treatment system. It is used
extensively to recover plating chemicals in the electroplating
industry and a pilot scale unit has been used in connection with
phosphating of aluminum. Proven performance in silver recovery
indicates that evaporation could be a useful treatment operation
for the photographic industry, as well as for metal finishing.
18. Gravity Sludge Thickening
In the gravity thickening process, dilute sludge is fed from a
primary settling tank or clarifier to a thickening tank where
rakes stir the sludge gently to densify it and to push it to a
central collection well. The supernatant is returned to the
primary settling tank. The thickened sludge that collects on the
bottom of the tank is pumped to dewatering equipment or hauled
away. Figure VII-24 (page 217) shows the construction of a
gravity thickener.
Application and Performance. Thickeners are generally used in
facilities where the sludge is to be further dewatered by a
compact mechanical device such as a vacuum filter or centrifuge
Doubling the solids content in the thickener substantially
reduces capital and operating cost of the subsequent dewatering
device and also reduces cost for hauling. The process is
potentially applicable to almost any industrial plant.
Organic sludges from sedimentation units of one to two percent
solids concentration can usually be gravity thickened to six to
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ten percent; chemical sludges can be thickened to four to six
percent.
Advantages and Limitations. The principal advantage of a gravity
sludge thickening process is that it facilitates further sludge
dewatering. Other advantages are high reliability and minimum
maintenance requirements.
Limitations of the sludge thickening process are its sensitivity
to the flow rate through the thickener and the sludge removal
rate. These rates must be low enough not to disturb the
thickened sludge.
Operational Factors. Reliability: Reliability is high with
proper design and operation. A gravity thickener is designed on
the basis of square feet per pound of solids per day, in which
the required surface area is related to the solids entering and
leaving the unit. Thickener area requirements are also expressed
in terms of mass loading, grams of solids per square meter per
day (Ibs/sq ft/day).
Maintainability: Twice a year, a thickener must be shut down for
lubrication of the drive mechanisms. Occasionally, water must be
pumped back through the system in order to clear sludge pipes.
Solid Waste Aspects: Thickened sludge from a gravity thickening
process will usually require further dewatering prior to
disposal, incineration, or drying. The clear effluent may be
recirculated in part, or it may be subjected to further treatment
prior to discharge.
Demonstration Status. Gravity sludge thickeners are used
throughout industry to reduce water content to a .level where the
sludge may be efficiently handled. Further dewatering is usually
practiced to minimize costs of hauling the sludge to approved
landfill areas. Sludge thickening is used in seven coil coating
plants.
19- Insoluble Starch Xanthate
Insoluble starch xanthate is essentially an ion exchange medium
used to remove dissolved heavy metals from wastewater. The water
may then either be reused (recovery application) or discharged
(end-of-pipe application). In a commercial electroplating oper-
ation, starch xanthate is coated on a filter medium. Rinse water
containing dragged out heavy metals is circulated through the
filters and then reused for rinsing. The starch-heavy metal
complex is disposed of and replaced periodically. Laboratory
tests indicate that recovery of metals from the complex is
feasible, with regeneration of the starch xanthate. Besides
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electroplating, starch xanthate is potentially applicable to coil
coating, porcelain enameling, copper fabrication, and any other
industrial plants where dilute metal wastewater streams are
generated. Its present use is limited to one electroplating
plant.
20. Ion Exchange
Ion exchange is a process in which ions, held by electrostatic
forces to charged functional groups on the surface of the ion
exchange resin, are exchanged for ions of similar charge from the
solution in which the resin is immersed. This is classified as a
sorption process because the exchange occurs on the surface of
the resin, and the exchanging ion must undergo a phase transfer
from solution phase to solid phase. Thus, ionic contaminants in
a waste stream can be exchanged for the harmless ions of the
resin.
Although the precise technique may vary slightly according to the
application involved, a generalized process description follows.
The wastewater stream being treated passes through a filter to
remove any solids, then flows through a cation exchanger which
contains the ion exchange resin. Here, metallic impurities such
as copper, iron, and trivalent chromium are retained. . The stream
then passes through the anion exchanger and its associated resin.
Hexavalent chromium, for example, is retained in this stage. If
one pass does not reduce the contaminant levels sufficiently, the
stream may then enter another series of exchangers. Many ion
exchange systems are equipped with more than one set of
exchangers for this reason.
The other major portion of the ion exchange process concerns the
regeneration of the resin, which now holds those impurities
retained from the waste stream. An ion exchange unit with in-
place regeneration is shown in Figure VII-25 (page 218). Metal
ions such as nickel are removed by an acid, cation exchange
resin, which is regenerated with hydrochloric or sulfuric acid,
replacing the metal ion with one or more hydrogen ions. Anions
such as dichromate are removed by a basic, anion exchange resin,
which is regenerated with sodium hydroxide, replacing the anion
with one or more hydroxyl ions. The three principal methods
employed by industry for regenerating the spent resin are:
A) ^Replacement Service: A regeneration service replaces the
spent resin with regenerated resin, and regenerates the
spent resin at its own facility. The service then has the
problem of treating and disposing of the spent regenerant.
B) In-Place Regeneration: Some establishments may find it less
expensive to do their own regeneration. The spent resin
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column is shut down for perhaps an hour, and the spent resin
is regenerated. This results in one or more waste streams
which must be treated in an appropriate manner.
Regeneration is performed as the resins require it, usually
every few months.
C) Cyclic Regeneration: In this process/ the regeneration of
the spent resins takes place within the ion exchange unit
itself in alternating cycles with the ion removal process.
A regeneration frequency of twice an hour is typical. This
very short cycle time permits operation with a very small
quantity of resin and with fairly concentrated solutions,
resulting in a very compact system. Again, this process
varies according to application, but the regeneration cycle
generally begins with caustic being pumped through the anion
exchanger, carrying out hexavalent chromium, for example, as
sodium dichromate. The sodium dichromate stream then passes
through a cation exchanger, converting the sodium dichromate
to chromic acid. After concentration by evaporation or
other means, the chromic acid can be returned to the process
line. Meanwhile, the cation exchanger is regenerated with
sulfuric acid, resulting in a waste acid stream containing
the metallic impurities removed earlier. Flushing the
exchangers with water completes the cycle. Thus, the
wastewater is purified and, in this example, chromic acid is
recovered. The ion exchangers, with newly regenerated
resin, then enter the ion removal cycle again.
Application and Performance. The list of pollutants for which
the ion exchange system has proven effective includes aluminum,
arsenic, cadmium, chromium (hexavalent and trivalent), copper,
cyanide, gold, iron, lead, manganese, nickel, selenium, silver,
tin, zinc, and more. Thus, it can be applied to a wide variety
of industrial concerns. Because of the heavy concentrations of
metals in their wastewater, the metal finishing industries uti-
lize ion exchange in several ways. As an en.d-of-pipe treatment,
ion exchange is certainly feasible, but its greatest value is in
recovery applications. It is commonly used as an integrated
treatment to recover rinse water and process chemicals. Some
electroplating facilities use ion exchange to concentrate and
purify plating baths. Also, many industrial concerns, including
a number of coil coating plants, use ion exchange to reduce salt
concentrations in incoming water sources.
Ion exchange is highly efficient at recovering metal bearing
solutions. Recovery of chromium, nickel, phosphate solution, and
sulfuric acid from anodizing is commercial. A chromic acid
recovery efficiency of 99.5 percent has been demonstrated.
Typical data for purification of rinse water have been reported
and are displayed in Table VII-25 (page 190).
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Ion exchange is a versatile technology applicable to a great many
situations. This flexibility, along with its compact nature and
performance, makes ion exchange a very effective method of waste
water treatment. However, the resins in these systems can prove
to be a limiting factor. The thermal limits of the anion resins,
generally in the vicinity of 60°C, could prevent its use in
certain situations. Similarly, nitric acid, chromic acid, and
hydrogen peroxide can all damage the resins, as will iron,
manganese, and copper when present with sufficient concentrations
of dissolved oxygen. Removal of a particular trace contaminant
may be uneconomical because of the presence of other ionic
species that are preferentially removed. The regeneration of the
resins presents its own problems. The cost of the regenerative
chemicals can be high. In addition, the waste streams
originating from the regeneration process are extremely high in
pollutant concentrations, although low in volume. These must be
further processed for proper disposal.
Operational Factors. Reliability: With the exception of
occasional clogging or fouling of the resins, ion exchange has
proved to be a highly dependable technology.
Maintainability: Only the normal maintenance of pumps, valves,
piping and other hardware used in the regeneration process is
required.
Solid Waste Aspects: Few, if any, solids accumulate within the
ion exchangers, and those which do appear are removed by the re-
generation process. Proper prior treatment and planning can eli-
minate solid buildup problems altogether. The brine resulting
from regeneration of the ion exchange resin most usually must be
treated to remove metals before discharge. This can generate
solid waste.
Demonstration Status. All of the applications mentioned in this
document ar
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be preceded by those treatment techniques which will properly
prepare the wastewater for solids removal. Typically, a membrane
filtration unit is preceded by pH adjustment or sulfide addition
for precipitation of the metals. These steps are followed by the
addition of a proprietary chemical reagent which causes the
precipitate to be non-gelatinous, easily dewatered, and highly
stable. The resulting mixture of pretreated wastewater and
reagent is continuously recirculated through a filter module and
back into a recirculation tank. The filter module contains
tubular membranes. While the reagent-metal hydroxide precipitate
mixture flows through the inside of the tubes, the water and any
dissolved salts permeate the membrane. When the recirculating
slurry reaches a concentration of 10 to 15 percent solids, it is
pumped out of the system as sludge.
Application and Performance. Membrane filtration appears to be
applicable to any wastewater or process water containing metal
ions which can be precipitated using hydroxide, sulfide or
carbonate precipitation. It could function as the primary
treatment system, but also might find application as a polishing
treatment (after precipitation and settling) to ensure continued
compliance with metals limitations. Membrane filtration systems
are being used in a number of industrial applications,
particularly in the metal finishing area. They have also been
used for heavy metals removal in the metal fabrication industry
and the paper industry.
The permeate is claimed by one manufacturer to contain less than
the effluent concentrations shown in the following table,
regardless of the influent concentrations. These claims have
been largely substantiated by the analysis of water samples at
various plants in various industries.
In the performance predictions for this technology, pollutant
concentrations are reduced to the levels shown in Table VI1-26
(page 191) unless lower levels are present in the influent
stream.
A major advantage of the membrane filtration system is that
installations can use most of the conventional end-of-pipe
systems that may already be in place. Removal efficiencies are
claimed to be excellent, even with sudden variation of pollutant
input rates; however, the effectiveness of the membrane
filtration system can be limited by clogging of the filters.
Because pH changes in the waste stream greatly intensify clogging
problems, the pH must be carefully monitored and controlled.
Clogging can force the shutdown of the system and may interfere
with production. In addition, relatively high capital cost of
this system may limit its use.
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Operational Factors. Reliability: Membrane filtration has been
shown to be a very reliable system, provided that the pH is
strictly controlled. Improper pH can result in the clogging of
the membrane. Also, surges in the flow rate of the waste stream
must be controlled in order to prevent solids from passing
through the filter and into the effluent.
Maintainability: The membrane filters must be regularly
monitored, and cleaned or replaced as necessary. Depending on
the composition of the waste stream and its flow rate, frequent
cleaning of the filters may be required. Flushing with
hydrochloric acid for 6-24 hours will usually suffice. In
addition, the routine maintenance of pumps, valves, and other
plumbing is required.
Solid Waste Aspects: When the recirculating reagent-precipitate
slurry reaches 10 to 15 percent solids, it is pumped out of the
system. It can then be disposed of directly or it can undergo a
dewatering process. Because this sludge contains toxic metals,
it requires proper disposal.
Demonstration Status. There are more than 25 membrane filtration
systems presently in use on metal finishing and similar
wastewaters. Bench scale and pilot studies are being run in an
attempt to expand the list of pollutants for which this system is
known to be effective. A unit has been installed at one coil
coating plant based on these tests.
22. Peat Adsorption
Peat moss is a complex natural organic material containing lignin
and cellulose as major constituents. These constituents,
particularly lignin, bear polar, functional groups, such as
alcohols, aldehydes, ketones, acids, phenolic hydroxides, and
ethers, that can be involved in chemical bonding. Because of the
polar nature of the material, its adsorption of dissolved solids
such as transition metals and polar organic molecules is quite
high. These properties have led to the use of peat as an agent
for the purification of industrial wastewater.
Peat adsorption is a "polishing" process which can achieve very
low effluent concentrations for several pollutants. If the
concentrations of pollutants are above 10 mg/1, then peat
adsorption must be preceded by pH adjustment for metals
precipitation and subsequent clarification. Pretreatment is also
required for chromium wastes using ferric chloride and sodium
sulfide. The wastewater is then pumped into a large metal
chamber called a kier which contains a layer of peat through
which the waste stream passes. The water flows to a second kier
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for further adsorption. The wastewater is then ready for
discharge. This system may be automated or manually operated.
Application and Performance. Peat adsorption can be used for
removal of residual dissolved metals from clarifier effluent.
Peat moss may be used to treat wastewaters containing heavy
metals such as mercury, cadmium, zinc, copper, iron, nickel,
chromium, and lead, as well as organic matter such as oil,
detergents, and dyes. Peat adsorption is currently used
commercially at a textile plant, a newsprint facility, and a
metal reclamation operation.
Table VII-27 (page 191) contains performance figures obtained
from pilot plant studies. Peat-adsorption was preceded by pH
adjustment for precipitation and by clarification.
In addition, pilot plant studies have shown that chelated metal
wastes, as well as the chelating agents themselves, are removed
by contact with peat moss.
Advantages and Limitations. The major advantages of the system
include its ability to yield low pollutant concentrations, its
broad scope in terms of the pollutants eliminated, and its
capacity to accept wide variations of waste water composition.
Limitations include the cost of purchasing, storing, and
disposing of the peat moss; the necessity for regular replacement
of the peat may lead to high operation and maintenance costs.
Also, the pH adjustment must be altered according to the
composition of the waste stream.
Operational Factors. Reliability: The question of long term
reliability is not yet fully answered. Although the manufacturer
reports it to be a highly reliable system, operating experience
is needed to verify the claim.
Maintainability: The peat moss used in this process soon
exhausts its capacity to adsorb pollutants. At that time, the
kiers must be opened, the peat removed, and fresh peat placed
inside. Although this procedure is easily and quickly
accomplished, it must be done at regular intervals, or the
system's efficiency drops drastically.
Solid Waste Aspects: After removal from the kier, the spent peat
must be eliminated. If incineration is used, precautions should
be taken to insure that those pollutants removed from the water
are not released again in the combustion process. Presence of
sulfides in the spent peat, for example, will give rise to sulfur
dioxide in the fumes from burning. The presence of significant
quantities of toxic heavy metals in canmaking wastewater will in
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general preclude incineration of peat used in treating these
wastes.
Demonstration Status. Only three facilities currently use
commercial adsorption systems in the United States - a textile
manufacturer, a newsprint facility, and a metal reclamation firm.
23. Reverse Osmosis
The process of osmosis involves the passage of a liquid through a
semipermeable membrane from a dilute to a more concentrated
solution. Reverse osmosis (RO) is an operation in which pressure
is applied to the more concentrated solution, forcing the per-
meate to diffuse through the membrane and into the more dilute
solution. This filtering action produces a concentrate and a
permeate on opposite sides of the membrane. The concentrate can
then be further treated or returned to the original operation for
continued use, while the permeate water can be recycled for use
as clean water. Figure VI1-26 (page 219) depicts a reverse
osmosis system.
As illustrated in Figure VII-27 (page 220), there are three basic
configurations used in commercially available RO modules:
tubular, spiral-wound, and hollow fiber. All of these operate on
the principle described above, the major difference being their
mechanical and structural design characteristics.
The tubular membrane module uses a porous tube with a cellulose
acetate membrane-lining. A common tubular module consists of a
length of 2.5 cm (1 inch) diameter tube wound on a supporting
spool and encased in a plastic shroud. Feed water is driven into
the tube under pressures varying from 40 - 55 atm (600-800 psi).
The permeate passes through the walls of the tube and is
collected in a manifold while the concentrate is drained off at
the end of the tube. A less widely used tubular RO module uses a
straight tube contained in a housing, under the same operating
conditions.
Spiral-wound membranes consist of a porous backing sandwiched
between two cellulose acetate membrane sheets and bonded along
three edges. The fourth edge of the composite sheet is attached
to a large permeate collector tube. A spacer screen is then
placed on top of the membrane sandwich and the entire stack is
rolled around the centrally located tubular permeate collector.
The rolled up package is inserted into a pipe able to withstand
the high operating pressures employed in this process, up to 55
atm (800 psi) with the spiral-wound module. When the system is
operating, the pressurized product water permeates the membrane
and flows through the backing material to the central collector
tube. The concentrate is drained off at the end of the container
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pipe and can be reprocessed or sent to further treatment facili-
ties.
The hollow fiber membrane configuration is made up of a bundle of
polyamide fibers of approximately 0.0075 cm (0.003 in.) OD and
0.0043 cm (0.0017 in.) ID. A commonly used hollow fiber module
contains several hundred thousand of the fibers placed in a long
tube, wrapped around a flow screen, and rolled into a spiral.
The fibers are bent in a U-shape and their ends are supported by
an epoxy bond. The hollow fiber unit is operated under 27 atm
(400 psi), the feed water being dispersed from the center of the
module through a porous distributor tube. Permeate flows through
the membrane to the hollow interiors of the fibers and is
collected at the ends of the fibers.
The hollow fiber and spiral-wound modules have a distinct advan-
tage over the tubular system in that they are able- to load a very
large membrane surface area into a relatively small volume.
However, these two membrane types are much more susceptible to
fouling than the tubular system, which has a larger flow channel.
This characteristic also makes the tubular membrane much easier
to clean and regenerate than either the spiral-wound or hollow
fiber modules. One manufacturer claims that their helical
tubular module can be physically wiped clean by passing a soft
porous polyurethane plug under pressure through the module.
Application and Performance.
In
a number of metal processing
plants, the overflow from the first rinse in a countercurrent
setup is directed to a reverse osmosis unit, where it is
separated into two streams. The concentrated stream contains
dragged out chemicals and is returned to the bath to replace the
loss of solution due to evaporation and dragout. The dilute
stream (the permeate) is routed to the last rinse tank to provide
water for the rinsing operation. The rinse flows from the last
tank to the first tank and the cycle is complete.
The closed-loop system described above may be supplemented by the
addition of a vacuum evaporator after the RO unit in order to
further reduce the volume of reverse osmosis concentrate. The
evaporated vapor can be condensed and returned to the last rinse
tank or sent on for further treatment.
The largest application has been for the recovery of nickel solu-
tions. It has been shown that RO can generally be applied to
most acid metal baths with a high degree of performance,
providing that the membrane unit is not overtaxed. The
limitations most critical here are the allowable pH range and
maximum operating pressure for each particular configuration.
Adequate prefiltration is also essential. Only three membrane
types are readily available in commercial RO units, and their
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overwhelming use has been for the recovery of various acid metal
baths. For the purpose of calculating performance predictions of
this technology, a rejection ratio of 98 percent is assumed for
dissolved salts, with 95 percent permeate recovery.
Advantages arid Limitations. The major advantage of reverse
osmosis for" handling process effluents is its ability to
concentrate dilute solutions for recovery of salts and chemicals
with low power requirements. No latent heat of vaporization or
fusion is required for effecting separations; the main energy
requirement is for a high pressure pump. It requires relatively
little floor space for compact, high capacity units, and it
exhibits good recovery and rejection rates for a number of
typical process solutions. A limitation of the reverse osmosis
process for treatment of process effluents is its limited
temperature range for satisfactory operation. For cellulose
acetate systems, the preferred limits are 18° to 30°C (65° to
85°F); higher temperatures will increase the rate of membrane
hydrolysis and reduce system life, while lower temperatures will
result in decreased fluxes with no damage to the membrane.
Another limitation is inability to handle certain solutions.
Strong oxidizing agents, strongly acidic or basic solutions,
solvents, and other organic compounds can cause dissolution of
the membrane. Poor rejection of some compounds such as borates
and low molecular weight organics is another problem. Fouling of
membranes by slightly soluble components in solution or colloids
has caused failures, and fouling of membranes by feed waters with
high levels of suspended solids can be a problem. A final limi-
tation is inability to treat or achieve high concentration with
some solutions. Some concentrated solutions may have initial os-
motic pressures which are so high that they either exceed avail-
able operating pressures or are uneconomical to treat.
Operational Factors. Reliability: Very good reliability is
achieved so long as the proper precautions are taken to minimize
the chances of fouling or degrading the membrane. Sufficient
testing of the waste stream prior to application of an RO system
will provide the information needed to insure a successful
application.
Maintainability: Membrane life is estimated to range from six
months to three years, depending on the use of the system. Down
time for flushing or cleaning is on the order of 2 hours as often
as once each week; a substantial portion of maintenance time must
be spent on cleaning any prefliters installed ahead of the re-
verse osmosis unit.
Solid Waste Aspects: In a closed loop system utilizing RO there
is a constant recycle of concentrate and a minimal amount of
solid waste. Prefiltration eliminates many solids before they
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reach the module and helps keep the buildup to a minimum. These
solids require proper disposal.
Demonstration Status. There are presently at least one hundred
reverse osmosis waste water applications in a variety of
industries. In addition to these, there are thirty to forty
units being used to provide pure process water for several
industries. Despite the many types and configurations of
membranes, only the spiral-wound cellulose acetate membrane has
had widespread success in commercial applications. One canmaking
plant has reverse osmosis equipment in-place.
24. Sludge Bed Drying
As a waste treatment procedure, sludge bed drying is employed to
reduce the water content of a variety of sludges to the point
where they are amenable to mechanical collection and removal to
landfill. These beds usually consist of 15 to 45 cm (6 to 18
in.) of sand over a 30 cm (12' in.) deep gravel drain system made
up of 3 to 6 mm (1/8 to 1/4 in.) graded'gravel overlying drain
tiles. Figure VII-28 (page 221) shows the construction of a
drying bed.
Drying beds are usually divided into sectional areas
approximately 7.5 meters (25 ft) wide x 30 to 60 meters (100 to
200 ft) long. The partitions may be earth embankments, but more
often are made of planks and supporting grooved posts.
To apply liquid sludge to the sand bed, a closed conduit or a
pressure pipeline with valved outlets at each sand bed section is
often employed. Another method of application is by means of an
open channel with appropriately placed side openings which are
controlled by slide gates. With either type of delivery system,
a concrete splash slab should be provided to receive the falling
sludge and prevent erosion of the sand surface.
Where it is necessary to dewater sludge continuously throughout
the year regardless of the weather, sludge beds may be covered
with a fiberglass reinforced plastic or other roof. Covered
drying beds permit a greater volume of sludge drying per year in
most climates because of the protection afforded from rain or
snow and because of more efficient control of temperature.
Depending on the climate, a combination of open and enclosed beds
will provide maximum utilization of the sludge bed drying
facilities.
Application and Performance. Sludge drying beds are a means of
dewatering sludge from clarifiers and thickeners. They are
widely used both in municipal and industrial treatment
facilities. •
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Dewatering of sludge on sand beds occurs by two mechanisms:
filtration of water through the bed and evaporation of water as a
result of radiation and convection. Filtration is generally
complete in one to two days and may result in solids
concentrations as high as 15 to 20 percent. The rate of
filtration depends on the drainability of the sludge.
The rate of air drying of sludge is related to temperature,
relative humidity, and air velocity. Evaporation will proceed at
a constant rate to a critical moisture content, then at a falling
rate to an equilibrium moisture content. The average evaporation
rate for a sludge is about 75 percent of that from a free water'
surface.
Advantages and Limitations. The main advantage of sludge drying
beds over other types of sludge dewatering is the relatively low
cost of construction, operation, and maintenance.
Its disadvantages are the large area of land required and long
drying times1 that depend, to a great extent, on climate and
weather.
Operational Factors. Reliability: Reliability is high with
favorable climactic conditions, proper bed design and care to
avoid excessive or unequal sludge application. If climatic
conditions in a given area are not favorable for adequate drying,
a cov,er may be necessary.
Maintainability: Maintenance consists basically of periodic
removal of the dried sludge. Sand removed from the drying bed
with the sludge must be replaced and the sand layer resurfaced.
The resurfacing of sludge beds is the major expense item in
sludge bed maintenance, but there are other areas which may
require attention. Underdrains occasionally become clogged and
have to be cleaned. Valves or sludge gates that control the flow
of sludge to the beds must be kept watertight. Provision for
drainage of lines in winter should be provided to prevent damage
from freezing. The partitions between beds should be tight so
that sludge will not flow from one compartment to another. The
outer walls or banks around the beds should also be watertight.
Solid Waste Aspects: The full sludge drying bed must either be
abandoned or the collected solids must be removed to a landfill.
These solids contain whatever metals or other materials were
settled in the clarifier. Metals will be present as hydroxides,
oxides, sulfides, or other salts. They have the potential for
leaching and contaminating ground water, whatever the location of
the semidried solids. Thus the abandoned bed or landfill should
include provision for runoff control and leachate monitoring.
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Demonstration Status. Sludge beds have been in common use in
both municipal and industrial facilities for many years.
However, protection of ground water from contamination is not
always adequate.
25. Ultrafiltration
Ultrafiltration (UF) is a process which uses semipermeable
polymeric membranes to separate emulsified or colloidal materials
suspended in a liquid phase by pressurizing the liquid so that it
permeates the membrane. The membrane of an ultrafilter forms a
molecular screen which retains molecular particles based on their
differences in size, shape, and chemical structure. The membrane
permits passage of solvents and lower molecular weight molecules.
At present, an ultrafilter is capable of. removing materials with
molecular weights in the range of 1,000'to 100,000 and particles
of comparable or larger sizes.
In an Ultrafiltration process, the feed solution is pumped
through a tubular membrane unit. Water and some low molecular
weight materials pass through the membrane under the applied
pressure of 10 to 100 psig. Emulsified oil droplets and
suspended particles are retained, concentrated, and removed
continuously. In contrast to ordinary filtration, retained
materials are washed off the membrane filter rather than held by
it. Figure VII-29 (page 192) represents the Ultrafiltration
process.
Application
application
Performance.
and
to canmaking
Ultrafiltration has potential
plants for separation of oils and
residual solids from a variety of waste streams. In treating
canmaking wastewater its greatest applicability would be as a
polishing treatment to remove residual precipitated metals after
chemical precipitation and clarification. Successful commercial
use, however, has been primarily for separation of emulsified
oils from wastewater. Over one hundred such units now operate in
the United States/ treating emulsified oils from a variety of
industrial processes. Capacities of currently operating units
range from a few hundred gallons a week to 50,000 gallons per
day. Concentration of oily emulsions to 60 percent oil or more
are possible. Oil concentrates of 40 percent or more are
generally suitable for incineration, and the permeate can be
treated further and in some cases recycled back to the process.
In this way, it is possible to eliminate contractor removal costs
for oil from some oily waste streams.
Table VII-28 (page 191) indicates Ultrafiltration performance
(note that UF is not intended to remove dissolved solids):
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The removal percentages shown are typical, but they can be
influenced by pH and other conditions. The high TSS level is
unusual for this technology and ultrafiltration is assumed to
reduce the TSS level by one-thrid after mixed media filtration.
The permeate or effluent from the ultrafiltration unit is
normally of a quality that can be reused in industrial
applications or discharged directly. The concentrate from the
ultrafiltration unit can be disposed of as any oily or solid
waste.
Advantages and Limitations. Ultrafiltration is sometimes an
attractive alternative to chemical treatment because of lower
capital equipment, installation, and operating costs, very high
oil and suspended solids removal, and little required
pretreatment. It places a positive barrier between pollutants
and effluent which reduces the possibility of extensive pollutant
discharge due to operator error or upset in settling and skimming
systems. Alkaline values in alkaline cleaning solutions can be
recovered and reused in process.
A limitation of ultrafiltration for treatment of process
effluents is its narrow temperature range (18° to 30°C) for
satisfactory operation. Membrane life decreases with higher
temperatures, but flux increases at elevated temperatures.
Therefore, surface area requirements are a function of
temperature and become a tradeoff between initial costs and
replacement costs for the membrane. In addition, ultrafiltration
cannot handle certain solutions. Strong oxidizing agents,
solvents, and other organic compounds can dissolve the membrane.
Fouling is sometimes a problem, although the high velocity of the
wastewater normally creates enough turbulence to keep fouling at
a minimum. Large solids particles can sometimes puncture the
membrane and must be removed by gravity settling or filtration
prior to the ultrafiltration unit.
Operational Factors.
The
the
reliability of an
proper filtration,
Reliability:
ultrafiltration system is dependent on
settling or other treatment of incoming waste streams to prevent
damage to the membrane. Careful pilot studies should be done in
each instance to determine necessary pretreatment steps and the
exact membrane type to be used.
Maintainability: A limited amount of regular maintenance is re-
quired for the pumping system. In addition, membranes must be
periodically changed. Maintenance associated with membrane plug-
ging can be reduced by selection of a membrane with optimum phy-
sical characteristics and sufficient velocity of the waste
stream. It is often necessary to occasionally pass a detergent
solution through the system to remove an oil and grease film
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which accumulates on the membrane. With proper
membrane life can be greater than twelve months.
maintenance
Solid Waste Aspects: Ultrafiltration is used primarily to
recover solids and liquids. It therefore eliminates solid waste
problems when the solids (e.g., paint solids) can be recycled to
the process. Otherwise, the stream containing solids must be
treated by end-of-pipe equipment. In the most probable
applications within the coil coating category, the ultrafilter
would remove hydroxides or sulfides of metals which have recovery
value.
Demonstration Status. The ultrafiltration process is well
developed and commercially available for treatment of wastewater
or recovery of certain high molecular weight liquid and solid
contaminants. One canmaking plant has ultrafiltration equipment
in-place.
26. Vacuum Filtration '
In wastewater treatment plants, sludge dewatering by vacuum
filtration generally uses cylindrical drum filters. These drums
have a filter medium which may be cloth made of natural or
synthetic fibers or a wire-mesh fabric. The drum is suspended
above and dips into a vat of sludge. As the drum rotates slowly,
part of its circumference is subject to an internal vacuum that
draws sludge to the filter medium. Water is drawn through the
porous filter cake to a discharge port, and the dewatered sludge,
loosened by compressed air, is scraped from the filter mesh.
Because the dewatering of sludge on vacuum filters is relativley
expensive per kilogram of water removed, the liquid sludge is
frequently thickened prior to processing. A vacuum filter is
shown in Figure VII-30 (page 223).
Application and Performance. Vacuum filters are frequently used
both in municipal treatment plants and in a wide variety of
industries. They are most commonly used in larger facilities,
which may have a thickener to double the solids content of
clarifier sludge before vacuum filtering.
The function of vacuum filtration is to reduce the water content
of sludge, so that the solids content increases from about 5
percent to about 30 percent.
Advantages and Limitations. Although the initial cost and area
requirement of the vacuum filtration system are higher than those
of a centrifuge, the operating cost is lower, and no special
provisions for sound and vibration protection need be made. The
dewatered sludge from this process is in the form of a moist cake
and can be conveniently handled. :
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Operational Factors. Reliability: Vacuum filter systems have
proven reliable at many industrial and municipal treatment
facilities. At present, the largest municipal installation is at
the West Southwest wastewater treatment plant of Chicago,
Illinois, where 96 large filters were installed in 1925,
functioned approximately 25 years, and then were replaced with
larger units. Original vacuum filters at Minneapolis-St. Paul,
Minnesota now have over 28 years of continuous service, and
Chicago has some units with similar or greater service life.
Maintainability: Maintenance consists of the cleaning or
replacement of the filter media, drainage grids, drainage piping,
filter pans, and other parts of the equipment. Experience in a
number of vacuum filter plants indicates that maintenance
consumes approximately. 5 to 15 percent of the total time. If
carbonate buildup or other problems are unusually severe,
maintenance time may be as high as 20 percent. For this reason,
it is desirable to maintain one or more spare units.
Demonstration Status. Vacuum filtration has been widely used for
many years. It is a fully proven, conventional technology for
sludge dewatering.
IN-PLANT TECHNOLOGY
The intent of in-plant technology for the canmaking subcategory
of the coil coating point source category is to reduce or
eliminate the waste load requiring end-of-pipe treatment and
thereby improve the efficiency of an existing wastewater
treatment system or reduce the requirements of a new treatment
system. In-plant technology involves improved rinsing, water
conservation, process bath conservation, reduction of dragout,
automatic controls, good housekeeping practices, recovery and
reuse of process solutions, process modification and waste
treatment. The in-plant technology has been divided into two
areas:
• In-process treatment and controls
• Process substitutions
In-Process Treatment and Controls
In-process treatment and controls can apply to both existing and
new installations and use technologies and methodologies that
have already been developed. The reduction in chemical and water
usage are desirable because of the attendant reductions in
pollutant discharge which results from treating smaller volumes
of more concentrated waste streams.
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A major portion of the oil, grease, dirt and oxide coating is
removed from the can by cleaning and rinsing. Cleaning of the
can is extremely important because incomplete cleaning adversely
affects subsequent operations. The primary factors that
adversely affect cleaning and rinsing efficiency are:
• Incorrect cleaning compound for basis material.
* Incorrect temperature of cleaning solution and rinse water.
• Insufficient number of spray nozzles or insufficient
pressure for both cleaning and rinsing.
• Absence of bath equilibrium controls that automatically add
make-up water and cleaning solution.
• Undefined soils
• Insufficient time
Cleaning solutions are formulated for specific basis materials.
The most advanced cleaning solutions contain phosphates that form
soluble complexes with the dissolved basis materials rather than
an insoluble sludge. The formation of an insoluble sludge may
necessitate discarding the solution before exhausting all
available alkalinity.
Operating temperature is as important as the proper cleaning
solution and concentration. A solution that is too cold may not
be able to dissolve either enough of the cleaning compound or the
oils from the can.' Excessive temperature may cause excessive
foaming.
Spray nozzles and pressures should be adequate to assure
overlapping coverage of the work area. Experience will dictate
how fast the line can move and be effectively cleaned with a
given set of spray nozzles and pressure.
The use of cleaning rinse water as make-up to the cleaning tank
can conserve water. Another applicable water conservation
mechanism (particularly for new installations) is a
countercurrent rinse. Multi-stage and countercurrent rinses are
employed at many industrial plants. In many ceises, however,
these techniques are not combined with effective flow control,
and the wastewater discharge volumes from the multi-stage or
countercurrent rinses are as large as or larger than
corresponding single stage rinse flows at other plants.
Countercurrent rinsing is more efficient than multiple single
stage rinses from the standpoint of water use. In countercurrent
rinsing one fresh water feed is used for the last tank in the
production sequence. The overflow from each tank in the
production sequence becomes the feed for the tank proceeding it;
the water flow from tank to tank cascades countercurrently to the
products sequence.
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Countercurrent Cascade Rinsing
Rinse water requirements and the
rinsing may be influenced by the
carried into each rinse stage by
the number of rinse stages used, by
impurities being removed, and by the
required (see Figures III-3 and III
factors is expressed in the rinsing
simply as:
benefits of countercurrent
volume of solution dragout
the material being rinsed^, by
the initial concentrations of
final product cleanliness
-4). The influence of these
equation which may be stated
Vr =
Vr is the flow through each rinse stage.
Co is the concentration of the contaminant(s) in the
initial process bath
Cf_ is the concentration of the contaminant (s) in the final
rinse to give acceptable product cleanliness.
n is the number of rinse stages employed
and
Vd is the drag-out carried into each rinse stage, expressed
as a flow.
For convenience we can set r = Co/Cf because for any set of
calculations about flow reduction, the cleanliness ratio Co/Cf is
the same. For a multi-stage rinse, the total volume of rinse
wastewater is equal to n times Vr, while for a countercurrent
rinse the total volume of wastewater discharge equals Vr.
Drag-out is solution which remains on the surface of material
being rinsed when the surface is transferred from process baths
or rinses.
To calculate the cleanliness ratio, r, we start with BPT water
use of 176.7 1/1000 cans and subtract a 10 percent allowance for
wastewater generated from oil sump discharge, ion exchange
regeneration, fume scrubber discharge, and batch dumps of process
tanks (i.e. acid cleaner and conversion coating solution). Thus,
176.7 - 17.7 = 159.0 1/1000 cans represents the rinse water use
for single stage rinses.
Without specific data available to determine drag-out we can
assume a dragout film thickness of 0.075 mm (2.9 mils) which is
equivalent to a poorly drained vertical surface film thickness;
and a surface area of 555 sq. cm for a standard 12 ounce can body
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(can diameter is 6.5 cm and can height is 12.0 cm). The volume
of dragout or carryover is:
Vd - 555 sq cm/can x .0075 cm = 4.16 cu cm/can (ml/can) or 4.16
1/1000 cans
Given the configuration of the inverted seamless can body as it
passes through the washer with a dished impression in the bottom,
4.16 ml per can carryover from one stage to the next by an
inverted can which has little time to drain, seems reasonable
especially when an air knife is used. Substituting in the
rinsing equation for a single stage rinse, Vr = r x Vd, and
solving for r, we get
r . T59 = 38.22.
4.16
If a two stage countercurrent spray rinse is substituted for the
single stage rinse, we get for a rinse water volume:
Vr - (38.22)V2 (4.16)
- 6.18 x 4.16
=25.7 1/1000 cans
If a three stage countercurrent spray rinse is substituted
for the single stage rinse, we get for a rinse water volume:
Vr - (38.22) V3 (4.16)
- 3.368 x 4.16
« 14.01 1/1000 cans i
In-process Control
The conversion coating function is a key step of the canmaking
operation. This is one of the steps in which material is added
to the can. The two types of conversion coating used on cans are
chromating and phosphatirig.
A number of parameters require monitoring and control to maximize
coating formation rate and minimize the amount of material
discarded.
All types of conversion coating operations require careful
monitoring and control of pH. If the pH is not kept at the
optimum level, either the chemical reaction proceeds too slowly
or the surface of the can is excessively etched. The pH of the
system can be sensed electronically and automatic make-up of
specific chemicals performed in accordance with manufacturers'
specifications. Chemical suppliers provide a series of chemicals
for each type of conversion coating. The series includes a new
172
-------
bath formulation and one or two replenishment chemicals depending
upon the constituent that has been depleted. This system
maximizes use of all chemicals and provides for a continued high
quality product.
Temperature must be constantly monitored and kept within an
acceptable range. Low temperatures will slow film formation and
high temperatures will degrade the freshly formed film. For a
given line speed, there should be adequate spray nozzle coverage
and pressure. This assures that all areas of each can have
sufficient reaction time to allow buildup of a specified film
thickness.
The chromating conversion coating chemicals contain significant
quantities of hexavalent and trivalent chromium. The hexavalent
chromium eventually becomes reduced to trivalent chromium,
precluding its use as part of the film. Certain chromating
conversion coating systems are designed to regenerate chromium.
These systems pump chromating conversion coating solution out of
the process tank to another tank where it is electrolytically
regenerated. This application of electrical current to the
solution increases the valence of the trivalent chromium to
hexavalent chromium. The solution is then returned to the
process tank.
In-Process Substitutions
The in-process substitutions for this industry involve only the
conversion coating phases of the total operation. The cleaning,
rinsing, and painting remain virtually unchanged. These in-
process substitutions eliminate the discharge of a significant
pollutant from the conversion coating operation.
Certain chromating solutions contain cyanide ions to promote
faster reaction of the solution. Cyanide is a priority pollutant
which requires separate treatment to remove it once it is in
solution.
There are competing chemical systems that do not contain cyanide
and efforts should be made to eliminate cyanide use where
possible.
173
-------
TABLE VI1-1
pH CONTROL EFFECT ON METALS REMOVAL
In
Day 1
pH Range 2.4-3.4
(mg/1)
TSS*
Copper
Zinc
Out
In
Day 2
Out
In
Day 3
Out
8.5-8.7 1.0-3.0 5.0-6.0 2.0-5.0 6.5-8.1
16 7
107 0.66
43.8 0.66
39
312
250
8
0.22
0.31
16
120
32.5
19
5.12
25.0
TABLE VI1-2
Effectiveness of Sodium Hydroxide for Metals Removal
In
Day 1
Out
In
Day 2
Out
In
Day 3
Out
pH Range 2.1-2.9 9.0-9.3 2.0-2.4 8.7-9.1 2.0-2.4 8.6-9.1
(mg/1)
Cr
Cu
Fe
Pb
Mn
Ni
Zn
TSS
0.097
0.063
9.24
1 .0
0.11
0.077
054
0.0
0.018
0.76
0.11
0.06
0.011
0.0
13
0.057
0.078
15.5
1 .36
0.12
0.036
0.12
0.005
0.014
0.92
0.13
0.044
0.009
0.0
11
0.068 0.005
0.053 0.019
9.41 -0.95
1.45 0.11
0.11 0.044
0.069 0.011
0.19 0.037
11
174
-------
TABLE VII-3
Effectiveness of Lime and Sodium Hydroxide for Metals Removal
Day
In
pH Range 9 . 2-9 . 6
(mg/1)
Al 37.3
Co 3.92
Cu 0.65
Fe 137
Mn 175
Ni 6.86
Se 28.6
Ti 143
Zn 18.5
TSS 4390
1
Out In
8.3-9.8 9.2
0.35 38.1
Day 2
Out In
7.6-8.1 9.6
0.35 29.9
0.0 4.65 0.0 4.37
0.003 0.63
0.49 110
0.12 205
0.0 5.84
0.0 30.2
0.0 125
0.027 16.2
9 3595
0.003 0.72
0.57 208
0.012 245
0.0 5.63
0.0 27.4
0.0 115
0.044 17.0
13 2805
Day 3
Out
7.8-8.2
0.35
0.0
0.003
0.58
0.12
0.0
0.0
0.0
0.01
13
TABLE VI I -4
THEORETICAL
OF
Metal
•••^•IHH^^VW
Cadmium (Cd++)
Chromium
-------
TABLE VI1-5
SAMPLING DATA FROM SULFIDE
PRECIPITATION-SEDIMENTATION SYSTEMS
Treatment
Lime, FeS, Poly-
electrolyte,
Settle, Filter
In
Out
pH
(mg/1)
Cr+6
Cr
Cu
Fe
Ni
Zn
5.0-6.1
25.6
32.3
—
0.52
-
39.5
3 8-9
<0.014
<0.04
—
0.10
—
<0.07
Lime, FeS, Poly-
electrolyte,
Settle, Filter
In
Out
7.7
7.38
0.022 <0.020
2.4 <0.1
108 0.6
0.68 <0.1
33.9 <0.1
NaOH, Ferric
Chloride, Na2S
Clarify (1 stage)
In Out
11.45 <.005
18.35.005
0.029 0.003
0.060 0.009
These data were obtained from three sources:
Summary Report, Control and Treatment Technology for |he
Finishing I ndUstryj Sulfide Precipitation, USEPA, EPA
No. 625/8/80-003, 1979.
Industrial Finishing, Vol. 35, No. 11, November, 1979.
Electroplating sampling data from plant 27045.
176
-------
TABLE VII-6
SULFIDE PRECIPITATION-SEDIMENTATION PERFORMANCE
Parameter
Cd
CrT
Cu
Pb
Hg
Ni
Ag
Zn
Treated Effluent
(mg/1)
0.01
0.05
0.05
0.01
0.03
0.05
0.05
0.01
Table VI1-6 is based on two reports?
Summary Report, Control and Treatment Technology for the
Metal Finishing Industry; Sulfide Precipitation. USEPA, EPA
Addendum to Development Document for Effluent Limitations
Guidelines and New Source Performance Standards?Malor
Inorganic products Segment of InorganicsPoint Source
Category. USEPA., EPA Contract No. EPA-68-01-3281 (Task 7)
June, 1978. '
177
-------
Table VII-7
FERRITE CO-PRECIPITATION PERFORMANCE
Metal
Mercury
Cadmium
Copper
Zinc
Chromium
Manganese
Nickel
Iron
Bismuth
Lead
Influent(mg/1)
7.4
240
10
18
10
12
1,000
600
240
475
Effluent(mg/1)
0.001
.0.008
0.010
0.016
<0.010
0.007
0.200
0.06
0. 100
0.010
NOTE: These data are from:
Sources and Treatment of Wastewater in the Nonferrous
Metals Industry, USEPA, EPA No. 600/2-80-074, 1980.
TABLE VI1-8
CONCENTRATION OF TOTAL CYANIDE
(mg/1)
33056
12052
Mean
Method
FeSO4
FeS04
ZnS04
In
2,
2.
3.
0.
0.
0.
57
42
28
14
16
46
0.12
Out
178
-------
Table VII-9
Plant ID I
06097
13924
18538
30172
36048
mean
Multimedia Filter Performance
TSS Effluent Concentration, mq/1
0.0, 0.0, 0.5
1
3
1
1
8, 2.2, 5.6, 4.0, 4.0, 3.0, 2.2, 2.8
0, " " - ' - - -
0
4, 7,
2.0, 5.6, 3.6, 2.4, 3.4
0,
2.1, 2.6,
2.61
0
5
TABLE VII-10
PERFORMANCE OF SELECTED SETTLING SYSTEMS
PLANT ID
01057
09025
11058
12075
19019
33617
40063
44062
46050
SETTLING
DEVICE
Lagoon
Clarifier
Settling
Ponds
Clarifier
Settling
Pond
Settling
Tank
Clarifier
Lagoon
Clarifier
Clarifier
Settling
Tank
SUSPENDED SOLIDS CONCENTRATION (mg/1)
In
Day 1
451
284
170
4390
182
295
Out In
Day 2
Out In
Day 3
54
1100
6
9
56
1900
6
12
50
1620
5
5
17
6
1
-
9
13
10
242
50
1662
3595
1 18
42
10
1
16
12
14
10
502
- -
1298
2805
174
153
14
13
23
8
179
-------
Plant Skimmer Type
06058 API
06058 Belt
Table VII-11
SKIMMING PERFORMANCE
Oil & Grease
mg/1
In
224,669
19.4
Out
17.9
8.3
TABLE VII-12
SELECTED PARITION COEFFICIENTS
PAH
Priority Pollutant
Log Octanol/Water
Partition Coefficient
1 Acenaphthene 4.33
39 Fluoranthene 5.33
72 Benzo(a)anthracene 5.61
73 Benzo(a)pyrene 6.04
74 3,4-benzof1uoranthene 6.57
75 Benzo(k)fluoranthene 6.84
76 Chrysene 5.61
77 Acenaphthylene 4.07
78 Anthracene 4-45
79 Benzo(ghi)perylene 7.23
80 Fluorene 4.18
81 Phenanthrene 4.46
82 Dibenzo(a,h)anthracene 5.97
83 Indeno(1,2,3,cd)pyrene 7.66
84 Pyrene 5.32
180
-------
TABLE VI1-13
TRACE ORGANIC REMOVAL BY SKIMMING
API PLUS BELT SKIMMERS
(From Plant 06058)
Oil & Grease
Chloroform
Methylene Chloride
Naphthalene
N-nitrosodiphenylamine
Bis-2-ethylhexylphthalate
Diethyl phthalate
Butylbenzylphthalate
Di-n-octyl phthalate
Anthracene - phenanthrene
Toluene
Inf.
225,000
0.023
0.013
2.31
59.0
11 .0
0.005
0.019
16.4
0.02
Eff.
14.6
0.007
0.012
0.004
0.182
0.027
0.002
0.002
0.014
0.012
Table VII-14
COMBINED METALS DATA EFFLUENT VALUES (mg/1)
Cd
Cr
Cu
Pb
Ni
Zn
Fe
Mn
TSS
Mean
0.079
0.08
0.58
0.12
0.57
0.30
0.41
0.21
2.0
One Day
Max.
0.32
0.42
1 .90
0. 15
1 .41
1 .33
1 .23
0.43
41 .0
10 Day Avg
Max.
0.15
0.17
1 .00
0.13
1.00
0.56
0.63
0.34
20.0
30 Day Avg,
Max.
0. 13
0.12
0.73
0.12
0.75
0.41
0.51
0.27
15.5
181
-------
TABLE VII-15
L&S PERFORMANCE
ADDITIONAL POLLUTANTS
Pollutant
Sb
As
Be
Hg
Se
Ag
Th
Al
Co
F
Average Performance (mq/1)
0.7
0.51
0.30
0.06
0.30
0. 10
0.50
1.11
0.05
14.5
TABLE VI1-16
COMBINED METALS DATA SET - UNTREATED WASTEWATER
Pollutant
Cd
Cr
Cu
Pb
Ni
Zn
Fe
Mn
TSS
Min. Cone (mq/1)
4.6
Max. Cone, (mq/1)
3.83
116
108
29.2
27.5
337.
263
5.98
4390
182
-------
TABLE VI1-17
MAXIMUM POLLUTANT LEVEL IN UNTREATED WASTEWATER
ADDITIONAL POLLUTANTS
(mg/1)
Pollutant
As
Be
Cd
Cr
Cu
Pb
Ni
Ag
Zn
F
Fe
O&G
TSS
As & Se
4.2
<0. 1
0.18
33.2
6.5
3.62
16.9
352
Be
10.24
8.60
1 .24
0.35
0.12
646
796
Ag
0.23
110.5
11 .4
100
4.7
1512
16
587.8
22.8
2.2
5.35
0.69
760
2.8
5.6
183
-------
TABLE VII-18
PRECIPITATION-SETTLING-FILTRATION (LS&F) PERFORMANCE
Plant A
Parameters No Pts
For 1 979-Treated
Cr
Cu
Ni
Zn
Fe
For 1978-Treated
Cr
Cu
Ni
Zn
Fe
Raw Waste
Cr
Cu
Ni
Zn
Fe
Range mq/1
Mean +_
std . dev .
Mean + 2
std. dev.
Wastewater
47
12
47
47
o:
0.
0.
0.
015
01
08
08
- 0.
- 0.
- 0.
- 0.
13
03
64
53
0.
0.
0.
0.
045
019
22
17
+0.
+ 0.
+ 0.
+0.
029
006
13
09
0.
0.
0.
0.
10
03
48
35
Wastewater
47
28
47
47
21
5
5
5
5
5
0.
0.
0.
0.
0.
32.
0.
1 .
33.
10.
01
005
10
08
26
0
08
65
2
0
- 0.
- 0.
- 0.
- 2.
*"* .* °*,.
- 72
- 0
- 20
- 32
- 95
07
055
92
35
1
.0
.45
.0
.0
.0
0.
0.
0.
0.
0.
06
016
20
23
49
'
+ 0.
+ 0.
+0.
+0.
+0.
10
010
14
34
18
0.
0.
0.
0.
0.
26
04
48
91
85
184
-------
TABLE -VII-19
PRECIPTTATION-SETTLING-FILTRATION (LS&F) PERFORMANCE
Plant B
Parameters
For 1
For 1
Total
No Pts.
; Range mq/1
Mean +_
std. dev.
Mean + 2
std. dev.
979-Treated Wastewater
Cr
Cu
Ni
Zn
Fe
TSS
,175
176
175
1 75 ' '•
174
2
0.0
' 0.0
0.01
0 . 0 V
0.01
1 .00
- 0.
- 0.
- 1 .
- 0.
- 2.
- 1 .
40
22
49
66
40
00
0
0
0
0
0
.068
.024
.219
.054
.303
+ 0.
+ 0.
+ 0.
+0.
+ 0.
075
021
234
064
398
0.
0.
0.
0.
1 .
22
07
69
18
10
978-Treated Wastewater
Cr
Cu
Ni
Zn
Fe
1974-1
Cr
Cu
Ni
Zn
Fe
144
143
1 43
131
144
979-Treated
1288
1290
1287 '
1273
1287
0 . 0
0.0
o.o:
0.0
0.0
- '0.'
- 0.
- 1 .
- 0.
""" 1 •
70
23
03
24
76
0
0
0
0
0
.059
.017
.147
.037
.200
+ 0.
+ 0.
+ 0.
+0.
+ 0.
088
020
142
034
223
0.
0.
0.
0.
0.
24
06
43
1 1
47
Wastewater
0 ,0
0.0
0.0
0.0
0.0
- 0.
- 0.
- 1 .
- 0.
- 3.
56
23
88
66
15
0
0
0
0
0
.038
.011
.184
.035
.402
+ 0.
+ 0.
+ 0.
+ 0.
+0.
055
016
21 1
045
509
0.
0.
0.
0.
1 .
15
04
60
13
42
Raw Waste
Cr
Cu
Ni
Zn
Fe
TSS
3
3
3
2
3
2 1
2.80
0.09
1 .61
2.35
3.13
77
- 9.
- 0.
- 4.
- 3.
-35.
-466.
15
27
89
39
9
5
0
3
22
.90
.17
.33
.4
185
-------
TABLE VI1-20
PRECIPITATION-SETTLING-FILTRATION (LS&F) PERFORMANCE
Plant C
For Treated Wastewater
Parameters No Pts.
For Treated Wastewater
Cd
Zn
TSS
pH
103
103
103
103
For Untreated Wastewater
Cd
Zn
Fe
TSS
pH
103
103
3
103
103
Range mq/1
Mean +_
std. dev.
0.010 - 0.500 0.049 +.0.049
0.039 - 0.899 0.290 +0.131
0.100-5.00 1.244 +1.043
7.1 - 7.9 9.2*
Mean + 2
std. dev.
0.147
0.552
3.33
0.039 - 2.319
0.949 -29.8
0.107 - 0.46
0.80 -19.6
6.8 - 8.2
0.542 +0.381 1.304
11.009 +6.933 24.956
0.255
5.616 +.2.896 1 1 .408
7.6*
* pH value is median of 103 values.
186
-------
Pollutant
Parameter
TABLE VII-21
Summary of Treatment Effectiveness
(mg/1)
L&S
Technology
System
LS&F
Technology
System
114 Sb
115 As
117 Be
118 Cd
119 Cr
120 Cu
121 CN
122 Pb
123 Hg
124 Ni
125 Se
126 Ag
127 Tl
128 Zn
Al
Co
F
Fe
Mn
P
O&G
TSS
Mean
0.70
0.51
0.30
0.079
0.080
0.58
0.07
0.12
0.06
0.57
0.30
0.10
0.50
0.30
1.11
0.05
14.5
0.41
0.21
4.08
12.0
One
Day
Max.
2.87
2.09
1 .23
0.32
0.42
1 .90
0.29
0.15
0.25
1 .41
1.23
0.41
2.05
1 .33
4.55
0.21
59.5
1 .23
0.43
16.7
20.0
41 .0
Ten
Day
Avq.
1 .28
0.86
0.51
0.15
0.17
1 .00
0. 12
0.13
0.10
1 .00
0.55
0.17
0.84
0.56
1 .86
0.09
26.4
0.63
0.34
6.83
12.0
20.0
Thirty
Day
Avg.
1 .14
0.83
0.49
0.13
0.12
0.73
0.11
0.12
0.10
0.75
0.49
0.16
0.81
0.41
1 .80
0.08
23.5
0.51
0.27
6.60
10.0
15.5
Mean
0.47
0.34
0.20
0.049
0.07
0.39
0.047
0.08
0.036
0.22
0.20
0.07
0.34
0.23
0.74
0.034
9.67
0.28
0. 14
2.72
2.6
One
Day
Max.
1 .93
1 .39
0.82
0.20
0.37
1 .28
0.20
0.10
0. 15
0.55
0.82
0.29
1 .40
1 .02
3.03
0.14
39.7
1 .23
0.30
11 .2
10.0
15.0
Ten
Day
Avq.
0.86
0.57
0.34
0.08
0.15
0.61
0.08
0.09
0.06
0.37
0.37
0.12
0.57
0.42
1 .24
0.07
17.6 •
0.63
0.23
4.6
10.0
12.0
Thirty
Day
Avq.
0.76
0.55
0.32
0.08
0. 10
0.49
0.08
0.08
0.06
0.29
0.33
0.10
0.55
0.31
1 .20
0.06
15.7
0.51
0.19
4.4
10.0
10.0
187
-------
TABLE VI1-22
TREATMILITY RATING OP PRIORITY POLLUTANTS
UTILIZING CARBON ADSORPTION
Priority Pollutant Rati
1. acanaphthena H
2. acrolsin L
3. acrylonitrile L
4. benzene H
5. bonzidine H
6. carbon tetrachlorida H
(totrachloronethane)
7. chlorobenzene H
8. 1,2,3-trichlorobenzene R
9• hexachlorobenzene H
10. 1,2-dichloroethane H
11. 1,1,1-trichloroethane * H
12. haxachloroethana H
13. 1,1-dichloroethane H
14. 1,1,2-trichloroethane H
15. 1,1,2,2-tetrachlorethane R
16. chloroethana L
17. bis(chloromathyl) ether
18. bis(2-chloroethyl) ether H
19. 2-chloroethylvinyl ether L
(mixed)
20. 2-chloronaphthalene _ R
21. 2,4,6-trichlorophenol H
22. parachloromata cresol R
23. chloroform (trichloromethane) L
24. 2-chlorophanol H
25. 1,2-dichlorobenzene H
26. 1,3—dichlorobenzene H
27. 1,4-dichlorobenzene H
28. 3,3'-dichlorobenzidine H
29. 1,1-dichloroethylene L
30. 1,2-trana-dichloroethylena . L
31. 2,4-dichlorophenol H
32. 1,2-dichloropropane ' H
33. 1,2-dichloropropylene H
(1,3-dichloropropane)
34. 2,4-dimathylphenol H
35. 2,4-dinitrotoluene • • H
36. 2,6-dinitrotoluene H
37. 1,2-diphenylhydrazine H
38.. ethylbanzene M
39. fluoranthene H
40. 4-chlorophenyl phenyl other H
41. 4-bromophenyl phenyl ether R
42. bis(2-chloroisopropyl)ether M
43. bis(2-chloroethoxy)methane H
44. methylone chloride L
(dichlororaethane)
45. methyl chloride (chloromethane) L
46. methyl bromide (bromomethane) L
47. brooofoxra (tribromomethane) R
48. dichlorobromomethane H
*Nota Explanation of Removal Ratings
Category H (high removal)
adsorbs at levels S. 100 mg/g carbon at C. » 10 mg/1
adsorbs at levels > 100 mg/g carbon at C < 1.0 mg/1
Category H (moderate removal)
adsorbs at levels Z.100 mg/g carbon at C » 10 mg/1
adsorbs at levels £ 100 mg/g carbon at C.< 1.0 mg/1 . ;
Category L (low removal)
adsorbs at levels < 100 mg/g carbon at C. " 10 mg/1
adsorbs at levels < 10 mg/g carbon at " < 1.0 mg/1
C, " final concentrations of priority pollutant at equilibrium
Priority Pollutant
49. trichlorofluoromathane M
50. dichlorodifluoromethane L
51. chlorodibromomethane M
52. hexachlorobutadiene R
53. hexachlorocyclopentadiene H
54. isophorone R
55. naphthalene H
56. nitrobenzene R
57. 2-nitrophanol H
58. 4-nitrophenol R
59. 2,4-dinitrophenol R
60. 4,6-dinitro—Ch-cresol H
61. N-nitrosodimethylamina H
62. N-nitroaodiphenylamine R
63. N-nitroaodi-n-propyl2,3,6-dibanzanthrac:ene R
(dibenzo(a,h) anthracene)
83. indeno (1,2,3-cd) pyi:ene H
' • .(2/*3-b-phe'hylene pyrene)
84. pyrene
85. tetrachloroethylene M
86. toluene H
87;' trichioroethylene L
88. vinyl chloride.... L
(chloroethylene)
106. PCB-1242 (Aroclor 1242) R
'107. PCB-1254 (Aroclor 12S4) • H
108., PCB-1221 (Aroclor 1221). H
109. PCB-1332 (Aroclor 1232) H
110. PCB-1248 (Aroclor 1248) H
111. PCB-1260 (Aroclor 1260) H
112.;'PCB-1016 (Arpclor 1016) --: H
188
-------
TABLE VII - 23
.CLASSES OF ORGANIC COMPOUNDS ADSORBED ON CARBON
Organic Chemical Class
Aromatic Hydrocarbons
Polynuclear Aronatics
Chlorinated Aromatics
Phenolics
Chorinated Phenolics
*High Molecular Weight Aliphatic and
Branch Chain hydrocarbons
Chlorinated Aliphatic hydrocarbons
*High Molecular Weight Aliphatic
Acids and Aromatic Acids
*High Molecular Weight Aliphatic
Amines and Aromatic Amines
*High Molecular Weight Ketones,
Esters„ Ethers and Alcohols
Surfactants
Soluble Organic Dyes
Examples of Chemical Class
benzene, toluene, xylene
naphthalene, anthracene
biphenyls
chlorobenzene, polychlorinated
biphenyls, aldrin, endrin,
toxaphene, DDT
phenol, cresol, resorcenol
and polyphenyls
trichlorophenol, pentachloro-
phenol
gasoline, kerosine
carbon tetrachloride,
perchloroethylene
tar acids, benzole acid
aniline, toluene diamine
hydroguincne, polyethylene
glycol
alkyl benzene sulfonates
methylene blue, indigo carmine
High Molecular Weight includes ccmpounds in the broad range of from
4 to 20 carbon atoms
189
-------
Table VII-24
ACTIVATED CARBON PERFORMANCE (MERCURY)
Plant
A
B
C
Mercury levels - mq/1
In
28.0
0.36
0.008
Out
0.9
0.015
0.0005
Table VII-25
Ion Exchange Performance
Parameter
All Values mg/1
Al
Cd
Cr+3
Cr+6
Cu
CN
Au
Fe
Pb
Mn
Ni
Ag
SO4
Sn
Zn
Plant
Prior To
Purifi-
cation
5.6
5.7
3.1
7.1
4.5
9.8
-
7.4
-
4.4
6.2
1.5
—
1.7
14.8
A
After
Purifi-
cation
0.20
0.00
0.01
0.01
0.09
0.04
-
0.01
-
0.00
0,00
0.00
-
0.00
0.40
Plant B
Prior To
Purifi-
cation
_
-
-
-
43.0
3.40
2.30
-
] .70
-
1.60
9.10
210.00
1.10
.-
After
Purifi-
cation
_
-
- ;;
-
0.10
0.09
0.10
-
0.01
-
0.01
0.01
2.00
0.10
-
190
-------
Table VI1-26
MEMBRANE FILTRATION SYSTEM EFFLUENT
Specific
Metal
Al
Cr,
Cr
Cu
Fe
Pb
CN
Ni
Zn
TSS
(+6)
(T)
Manufacturers
Guarantee
0
0
0
0
0
0
0
0
0
_.
.5
.02
.03
.1
.1
.05
.02
.1
.1
—
Plant
In
__
0.
4.
18.
288
0.
-------
TABLE VII-29
REMOVAL OF TOXIC ORGANICS BY OIL REMOVAL
Pollutant Parameter
001 acenaphthene
038 ethylbenzene
055 naphthalene
062 N-nitrosodiphenylamine
065 phenol
066 bis(2-ethylhexyl)phthalate
068 di-n-butyl phthalate
078/081 anthracene/phenanthrene
080 fluorene
084 pyrene
085 tetrachloroethylene
086 toluene
087 trichloroethylene
097 endosulfan sulfate
098 endrin
107 PCB-1254 (a)
110 PCB-1248 (b)
(mg/1)
Influent
Concentration
(mq/1)
5.7
0.089
0.75
1 .5
0.18
1 .25
1 .27
2.0
0.76
0.075
4.2
0. 16
4.8
0.012
0.066
1 .1
1 .8
25.7
Effluent
Concentration
(mq/1)
ND
0.01
0.23
0.091
0.04
0.01
0.019
0. 1
0.035
0.01
0.1
0.02
0.01
ND
0.005
0.005
0.005
0.690
a: PCB-1242, PCB-1254, PCB-1221, PCB-1232 reported together.
b: PCB-1248, PCB-1260, PCB-1016 reported together.
192
-------
TABLE VII-30
CHEMICAL EMULSION BREAKING EFFICIENCIES
Parameter
O&G
TSS
O&G
TSS
O&G
TSS
O&G
Concentration (mq/l)
Influent
6,060
2,612
13,000
18,400
21,300
540
680
1,060
2,300
12,500
13,800
1,650
2,200
3,470
7,200
Effluent
98
46
277
—
189
121
59
140
52
27
18
187
153
63
80
Reference
Sampling data*
Sampling data+
Sampling data**
Katnick and Pavilcius, 1978++
*0il and grease and total suspended solids were taken as grab
samples before and after batch emulsion breaking treatment which
used alum and polymer on emulsified rolling oil wastewater.
+0il and grease (grab) and total suspended solids (grab) samples
were taken on three consecutive days from emulsified rolling
oil wastewater. A commercial demulsifier was used in this batch
treatment.
**Oil and grease (grab) and total suspended solids (composite)
samples were taken on three consecutive days from emulsified
rolling oil wastewater. A commercial demulsifier (polymer)
was used in this batch treatment.
++This result is from a full-scale batch chemical treatment system
for emulsified oils from a steel rolling mill.
193
-------
10
JO1 -
10 11 12 13
FIGURE VU-1. COMPARATIVE SOLUBILITIES OF METAL HYDROXIDES
AND SULFIDE AS A FUNCTION OF pH
194
-------
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(9
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0.10
CAUSTIC SODA.
SODA ASH AND
CAUSTIC SODA
8.0
6.5
8.0
9.5
10.0
10.S
PH
FIGURE VII-2. LEAD SOLUBILITY IN THREE ALKALIES
195
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EFFLUENT
INFLUENT
ALUM
WATER
LEVEL
STORED
BACKWASH
WATER
POLYMER
p
^
FILTER
COMPARTMENT
COLLECTION CHAMBER
THREE WAY VALVE
DRAIN
FIGURE VII-14. GRANULAR BED FILTRATION
!07
-------
PERFORATED
BACKING PLATE
\
FABRIC
FILTER MEDIUM
SOLID
RECTANGULAR
END PLATE
INLET
SLUDGE
FABRIC
FILTER MEDIUM
ENTRAPPED SOLIDS
FILTERED LIQUID OUTLET
PLATES AND FRAMES ARE
PRESSED TOGETHER DURING
FILTRATION CYCLE
RECTANGULAR
METAL PLATE
RECTANGULAR FRAME
FIGURE VII-15. PRESSURE FILTRATION
208
-------
SEDIMENTATION BASIN
INLET ZONE
INLET LIQUID
BAFFLES TO MAINTAIN
QUIESCENT CONDITIONS
OUTLET ZONE
i^ * SETTLING PARTI£L5
• *"**«*«.*• TRAJECTORY . •
OUTLET LIQUID
t
BELT-TYPE SOLIDS COLLECTION
MECHANISM
SETTLED PARTICLES COLLECTED
AND PERIODICALLY REMOVED
CIRCULAR CLARIFIER
INLET LIQUID
.CIRCULAR BAFFLE
. ANNULAR OVERFLOW WEIR
SETTLING ZONE.
INLET ZONE -
•*••*. "v^«'.»"
OUTLET LIQUID
•SETTLING PARTICLES
REVOLVING COLLECTION
MECHANISM
SETTLED PARTICLES
COLLECTED AND PERIODICALLY
REMOVED
SLUDGE DRAWOFF
FIGURE VII-16. REPRESENTATIVE TYPES OF SEDIMENTATION
209
-------
FLANOE
WASTE WATER
WASH WATER
BACKWASH
SURFACE WASH
MANIFOLD
INFLUENT
DISTRIBUTOR
BACKWASH
REPLACEMENT CARBON
CARBON REMOVAL PORT
*> TREATED WATER
SUPPORT PLATE
FIGURE VI1-17. ACTIVATED CARBON ADSORPTION COLUMN
210
-------
CONVEYOR DRIVE |_ DRYING
'ZONE
r-BOWL DRIVE
LIQUID
OUTLET
SLUDGE
INLET
CYCLOGEAR
SLUDGE
DISCHARGE
CONVEYOR BOWL
REGULATING
RING
IMPELLER
FIGURE VII-18. CENTR1FUGATION
211
-------
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u
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212
-------
CONTROLS
OZONE
GENERATOR
n
DRY AIR
D
" '
OZONE
REACTION
TANK
iv >i TREATED
-{X}———-
WASTE
RAW WASTE-
FIGURE VI1-20. TYPICAL OZONE PLANT FOR WASTE TREATMENT
213
-------
MIXER
WASTEWATER
FEED TANK
V
FIF
STj
SE
ST
|
T
s-
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C
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1
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TEMPERATURE
CONTROL
PH MONITORING
-- TEMPERATURE
— — CONTROL
PH MONITORING
TEMPERATURE
CONTROL
PH MONITORING
OZONE
OZONE
GENERATOR
FflGURE VII-21. UV/OZONATION
214 '.
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OILY WATER
INFLUENT
WATER
DISCHARGE
OVERFLOW
SHUTOFF
VALVE
MOTOR
DRIVEN
RAKE
EXCESS
AIR OUT
LEVEL
CONTROLLER
TO SLUDGE
TANK "*
FIGURE VII-23. DISSOLVED AIR FLOTATION
216
-------
CONDUIT
TO MOTOR
INFLUENT —-*.
CONDUIT TO
OVERLOAD
ALARM
COUNTERFLOW
INFLUENT WELL
DRIVE UNIT
OVERLOAD ALARM
AFFLUENT WEIR
DIRECTION OF ROTATION
EFFLUENT PIPE
EFFLUENT CHANNEL
PLAN
TURNTABLE
BASE
HANDRAIL
INFLUENT
CENTER COLUMN
CENTER CAGE
WEIR
STILTS
CENTER SCRAPER
SQUEEGEE
SLUDGE PIPE
FIGURE VII-24. 'GRAVITY THICKENING
217
-------
WASTE WATER CONTAINING
DISSOLVED METALS OR
OTHER IONS
_REGENERANT
"SOLUTION
-DIVERTER VALVE
DISTRIBUTOR
SUPPORT
REGENERANT TO REUSE,
TREATMENT. OR DISPOSAL
-DIVERTER VALVE
METAL-FREE WATER
FOR REUSE OR DISCHARGE
FIGURE VII-25. ION EXCHANGE WITH REGENERATION
218
-------
MACROMOLECULES
AND SOLIDS
MEMBRANE
FEED
Ap = 430 PSI
WATER
PERMEATE (WATER)
MEMBRANE CROSS SECTION,
IN TUBULAR, HOLLOW FIBER,
OR SPIRAL-WOUND CONFIGURATION
CONCENTRATE
(SALTS)
O SALTS OR SOLIDS
« WATER MOLECULES
FIGURE VII-26. SIMPLIFIED REVERSE OSMOSIS SCHEMATIC
219
-------
PERMEATE
TUBE
PERMEATE
FLOW
FEED
O-RING—'
ADHESIVE BOUND
SPIRAL MODULE
CONCENTRATE
FLOW
BACKING MATERIAL
MESH SPACER
•MEMBRANE
SPIRAL MEMBRANE MODULE
PRODUCT WATER
POROUS SUPPORT TUBE PERMEATE FLOW
WITH MEMBRANE
• • BRACKISH
WATER
FEED FLOW
PRODUCT WATER
TUBULAR REVERSE OSMOSIS'MO.DULE
BRINE
CONCENTRATE
FLOW
SNAP
RING
SEAL
EPOXY
TUBE SHEET
POROUS
UP DISC
SNAP
RING
END PLATE
PERMEATE
END PLATE
DISTRIBUTOR TUBE
HOLLOW FIBER MODULE
FIGURE VIl-27. REVERSE OSMOSIS MEMBRANE CONFIGURATIONS
220 ;
-------
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D PIPE LAID -S
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PLAN
-6-IN. FINE SANO
•3-IN. COARSE SAND
•3-IN. FINE GRAVEL
•3-IN. MEDIUM GRAVEL
•3 TO 6 IN. COARSE GRAVEL
\—
J
2-IN. PLANK
WALK
PIPE COLUMN FOR
GLASS-OVER
3-IN. MEDIUM GRAVEL
6-IN. UNDERDRAIN LAID-
WITH OPEN JOINTS
SECTION A-A
FIGURE VII-28. SLUDGE DRYING BED
221
-------
ULTRAFILTRATION
MACROMOLECULES
P- 10-50 PSI
1
MEMBRANE
WATER SALTS
-MEMBRANE
PERMEATE
* t. •
FEED
• * • -. O * CONCENTRATE
-•0** *0 * •
T^
O OIL PARTICLES
• DISSOLVED SALTS AND LOW-MOLECULAR-WEIGHT ORGANICS
FIGURE VII-29. SIMPLIFIED ULTRAFILTRATIQN FLOW SCHEMATIC
222
-------
FABRIC OR WIRE
FILTER MEDIA
STRETCHED OVER
REVOLVING DRUM
ROLLER
SOLIDS SCRAPED
OFF FILTER MEDIA
DIRECTION OF ROTATION
STEEL
CYLINDRICAL
FRAME
SOLIDS COLLECTION
HOPPER
INLET LIQUID
TO BE
FILTERED
-TROUGH
FILTERED LIQUID
FIGURE VII-30. VACUUM FILTRATION
223
-------
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w
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224
-------
SECTION VIII
COST, ENERGY, AND NONWATER QUALITY ASPECTS
This section presents estimates of the costs of implementing the
major wastewater treatment and control technologies described in
Section VII. These cost estimates, together with the estimated
pollutant reduction performance for each treatment and control
option presented in Sections IX, X, XI, and XII provide a basis
for evaluating the options presented and identification of the
best practicable control technology currently available (BPT),
best available technology economically achievable (BAT), best
demonstrated technology (BDT), and the appropriate technology for
pretreatment. The cost estimates also provide the basis for the
determination of the probable economic impact on the canmaking
subcategory of regulation at different pollutant discharge
levels. In addition, this section addresses nonwater quality
environmental impacts of wastewater treatment and control alter-
natives, including air pollution, noise pollution, solid wastes,
and energy requirements.
Briefly, the approach taken to develop capital and operating
costs was to identify a normal canmaking line and its water use,
discharge rate and characteristics. These values were used as
input to a computer cost estimation model which is discussed
below. For certain modules, the Agency's exist-ing cost data base
was used to develop costs. The costs for the three-line plant
were extrapolated to different size plants by applying the so-
called "six tenths power rule." This process was employed for
each existing source and new source treatment option.
COST ESTIMATION METHODOLOGY
For the canmaking subcategory, cost estimation is accomplished
for most modules using a computer model which accepts inputs
specifying the treatment system to be estimated, chemical charac-
teristics of the raw waste streams, flow rates and treatment
system entry points of these streams, and operating schedules.
This model utilizes a computer-aided design of a wastewater
treatment system containing modules that are configured to
reflect the appropriate equipment at an individual plant. The
model designs each module and then executes a costing routine
that contains the cost data for each module. The capital and
annual costs from the costing routine are combined with capital
and annual costs for the other modules to yield the total costs
for that regulatory option. The process is then repeated for
each regulatory option.
225
-------
Each module was developed by coupling theoretical.design informa-
tion from the technical literature with actual design data from
operating plants. This permits the most representative design
approach possible to be used, which is a very important element
of accurately estimating costs. The fundamental units for design
and costing are not the modules themselves but the components
within each module, e.g., the lime feed system within the chemi-
cal precipitation module. This is a significant feature of this
model for two reasons. First, it does riot limit the model to
certain fixed relationships between various components of each
module. For instance, cost data for chemical precipitation sys-
tems are typically presented graphically as a family of curves
with lime (or other alkali) dosage as a parametric function. The
model, however, sizes the lime feed system as a function of the
required mass addition rate (Ib/hr) of- lime. The model thus
selects a feed system specifically designed for that plant.
Second, this approach more closely reflects the way a plant would
actually design and purchase its equipment. The resulting costs
are thus more closely tied to the actual costs that would be
incurred by the facility.
Overall Structure
The cost estimation model comprises two main parts: a material
design portion and a costing portion. The material design por-
tion uses input provided by the user to calculate design param-
eters for each module included in the treatment system. The
design parameters are then used as input to the costing routine,
which contains cost equations for each discrete component in the
system. The structure of the program is such that the entire
system is designed before any costs are estimated.
Throughout the
are tracked:
program, the following pollutants or parameters
- Flow,
- Total suspended solids,
- pH,
- Acidity,
- Cadmium,
- Chromium,
- Copper,
- Lead,
226
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- Nickel,
- Zinc,
Iron,
- Aluminum,
Manganese, and
Hexavalent chromium.
The overall logic flow of the computer programs is depicted in
Figure VII1-1 (page 246). First, constants are initialized and
certain variables such as the modules to be included, the system
configuration, and plant and wastewater flows, compositions, and
entry points are specified by the user. Each module is designed
utilizing the appropriate flow and composition data for influent
streams. The design values are transmitted to the cost routine.
The appropriate cost equations are applied, and the module costs
and system costs are computed. Figures VII1-2 and VII1-3 (pages
247 and 248) depict the logic flow diagrams in more detail for
the two major segments of the program.
System Input Data
Several data inputs are required to run the computer model.
First, the treatment modules to be costed and their sequence must
be specified. Next, information on hours of operation per day
and number of days of operation per year is required. The flow
values and characteristics must be specified for each wastewater
stream entering the treatment system. The values will dictate
the size and other parameters of components to be included.
These inputs are derived from actual data if costs are sought for
actual plants. Where costs are developed for representative
plants, flows and concentrations are derived from aggregated
data. For development of costs for the canmaking industry, data
from Section V were used; these data are also summarized later in
this section.
Model Results
For a given plant, the model will generate comprehensive material
balances for each parameter tracked at any point in the system.
It will also summarize design values for key equipment in each
treatment module, and provide a tabulation of costs for each
element in each module, module summaries, total equipment costs,
and system capital and annual costs.
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GENERAL COST FACTORS
Dollar Base - All costs are adjusted to first quarter 1982
dollars.
Cost Update Factors
Investment - Investment costs were updated using the EPA-Sewage
Treatment Plant Construction Cost Index. The value of this index
for the first quarter of 1982 is 414.0.
Operation and Maintenance Labor - The ENR Skilled Labor Wage
Index is used to update the portion of O&M costs attributable to
labor. The March 1982 value is 325.
Maintenance Materials - The producer price index published by the
Department of Labor, Bureau of Statistics is used. The March
1982 value of this index is 276.5.
Chemicals - The Chemical Engineering Producer Price Index for
industrial chemicals is used. This index is published biweekly
in Chemical Engineering magazine. The March 1982 value of this
index is 362.6. : •
i
i , , ,, ,
Energy - Updating power costs is accomplished by using the price
for the desired date for electricity and multiplying it by the
energy requirements for the module in kwhr equivalents.
be
Capital Recovery ;
Capital recovery costs for recovery of committed capital may
calculated by using a capital recovery factor, given by the
following equation:
CRF « i + i ;
where CRF
i
n
(1 + i)n - i
capital recovery factor,
interest rate, and
period of amortization.
For this analysis, an interest rate of 12 percent and a period of
10 years were used. This yields a capital recovery factor of
0.17698. This value is multiplied by the total capital invest-
ment to give the annual amortization charge.
Annual Costs
Labor - A base labor rate for skilled labor of $9.00 per hour was
used. To account for supervisory personnel, 15 percent of the
228
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labor rate was included. Plant overhead at 100 percent of the
combined base and supervisory labor charges is also included.
The resulting composite labor rate used in this study is $21.00
per hour.
Operating Schedule - Two hundred and fifty days per year, 24
hours per day was assumed.
Energy - An electrical cost of 4.83 cents/kwh (March, 1982) was
assumed, based on the industrial cost derived from DOE's Monthly
Energy Review.
System Costs
Engineering - This was assumed to be 15 percent of the total
module cost.
Contractor's Fee - This was assumed to be 10 percent of the
summed module cost.
Contingency - This was assumed at 10 percent of the summed module
cost.
TECHNOLOGY BASIS FOR COST ESTIMATION
Four options for existing sources and two options for new sources
were identified as the treatment alternatives for the canmaking
subcategory. The technologies used, which were described in
detail in Section VII7 include:
Countercurrent rinsing,
Equalization,
- Chemical emulsion breaking,
- Dissolved air flotation,
- Chemical precipitation-sedimentation,
- Vacuum filtration,
- Multimedia filtration, and
- Ultrafiltration.
Where necessary, the following technologies are also available:
- Cyanide precipitation, and
229
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- Chromium reduction. I
The cost elements of each technology are discussed below.
Countercurrent Rinsing
This technology is applied to product rinsing operations. It
involves a number of spray rinse stages, with product and rinse
water moving in opposite directions (more detail may be found in
Section VII). This allows for significantly reduced flow over
single stage rinsing by contacting the most contaminated rinse
water with the incoming product. ;
The countercurrent system for existing plants in this subcategory
was designed assuming that a tank for single stage rinse was
already installed. The tank was converted to a two stage coun-
tercurrent operation by installing a baffle in the tank, recycle
piping, an additional set of stainless steel spray nozzles, and
an additional pump. The baffle was sized based on. a 1.2 x 2.4 x
1.2 meter (4x8x4 foot) tank using rubber-lined carbon steel.
Nine meters (30 feet) of rubber-lined steel pipe, 14 additional
nozzles, and a centrifugal pump rated at 1,814 1pm (480 gpm) were
assumed to be required. Installation of the purchased equipment
cost at 50 percent, and engineering, contractor's fees, and
contingencies at 35 percent of the installed equipment cost were
added, as was a retrofit allowance at 15 percent of the total.
Operation and maintenance costs were calculated assuming 300
hours per year of labor for the tank, and ijtaintenance materials
were estimated at 2 percent of the capital cost.
Equalization
The computer cost estimation model was used for this module. The
equalization tanks are of the vertical steel type with capacities
which vary as a function of flow rate. 'The detention time is
eight hours and the excess capacity is 20 percent. The tanks are
fitted with agitators with a horsepower requirement of 0.006
kw/1,000 liters (.03 hp/1,000 gallons) of capacity to prevent
sedimentation. A control system, valves, a pump, and piping are
also included.
The capital and annual costs are presented in Figure VII1-4 (page
249).
Chemical Emulsion Breaking :
Chemical emulsion breaking involves the separation of relatively
stable oil-water mixtures by addition of certain chemicals, in
this case, alum and polymer. To determine the capital and annual
230
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costs, 400 mg/1 of alum and 10 mg/1 of polymer are assumed to be
added to waste streams containing emulsified oils. The equipment
included in the capital and annual costs are as follows:
Chemical feed system
1. Storage units
2. Dilution tanks
3. Conveyors and chemical feed lines
4. Chemical feed pumps
Rapid mix tank
1. Tank
2. Mixer
3. Motor drive unit
Skimming
1. Gravity separation basin
2. Surface skimmer
3. Bottom sludge scraper
Costs were derived based on a composite of various systems which
included the above equipment. Alum and polymer costs were
obtained from vendors: dry alum at $0.33 per kg ($0.15 per
pound) and polymer at $6.60 per kg ($3.00 per pound). Energy
requirements were also drawn from various literature sources and
are included in the annual costs. The costs were updated to
first quarter, 1982.
The capital and annual costs are presented in Figure VIII-5 (page
250).
Dissolved Air Flotation
Dissolved air flotation (DAF) can be used by itself, in conjunc-
tion with gravity separation for the removal of free oil, or also
in conjunction with coagulant and flocculant addition to increase
oil removal efficiency. The capital and annual costs are based
on the dissolved air flotation unit only; other systems, such as
flocculant addition, may be added in separately.
The equipment used to develop capital and annual
DAF system is as follows:
- Flotation unit
- Surface skimmer
- Bottom sludge scraper
Pressurization unit
costs for the
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- Recycle pump
- Electrical and instrumentation
- Concrete pad, 1 ft. thick
Basic assumptions include a hydraulic loading of 0.70 Ipm/m2 (2
gpm/ft2) and a recycle ratio of 30 percent. All costs and energy
requirements were derived as composites of various systems
presented in the literature. Operational and maintenance labor
are estimated to range from 700 hrs/yr at 113,000 Ipd (30,000
gpd) to 1,800 hrs/yr at 3.78 x 107 Ipd (10 mgd). Energy
requirements are estimated to range from 54,000 Kw-hr/yr at
113,000 Ipd (30,000 gpd) to 3,500,000 kw/hr/yr at 3.78 x 107 Ipd
(10 mgd). Below 113,000 Ipd (30,000 gpd) flow rate, energy
requirements are considered to be constant.
The capital and annual costs for this technology are presented in
Figure VIII-6 (page 251).
Chemical Precipitation
Quicklime (CaO) or hydrated lime [Ca(OH)2] can be used to
precipitate toxic and other metals. Hydrated lime is commonly
used for wastewaters with low lime requirements since the use of
slakers, required for quicklime usage, is practical only for
large-volume application of lime. Due to the low lime dosage
requirements in this industry, hydrated lime is used for costing.
The lime dosage requirements were determined by the model using
specific influent characteristics and flow derived from
wastewater data for representative canmaking operations.
The following equipment were included in the determination
capital and annual costs based on continuous operation:
- Lime feed system
1. Storage units (sized for 30-day storage)
2. Dilution tanks (five minutes average retention)
3. Feed pumps :
- Rapid mix tank (detention time of five minutes; mixer
velocity gradient is 300/sec)
- Clarifier (overflow rate is 7.3 lph/m2 (20.8 gph/ft2);
underflow solids is 3 percent)
1. Sludge rakes
2. Sk immer
3. Weirs '
- Sludge pump
of
232
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The model assumes that a 25 percent excess of lime is used, that
the final pH is 9.0, and the effluent pollutant concentrations
are based on the Agency's combined data base lime precipitation
treatability values.
Batch operation assumes a two fiberglass or steel tank system (if
additional capacity is required, tanks are added in pairs) with
one lime feed system (includes one agitated mixing tank with
hydrated lime added manually in 22.7 kg (50 Ib) bags for every
two tanks), a sludge pump for up to four tanks, and a simple
control system. A lime storage shed is included for lime
addition rates > 90.7 kg/batch (200 Ibs/batch).
O&M costs for the continuous system are for operating and mainte-
nance labor for the clarifier and lime feed system, and the cost
for chemicals, maintenance materials, and energy. For the batch
mode, operational labor is assumed at one half hour per batch for
lime addition up to 90.7 kg/batch (200 Ibs/batch) and one hour
per batch for additional rates above 90.7 kkg/batch (200
Ibs/batch). Maintenance labor is constant for the batch system
at 52 hours per year (one hour/week). Lime is $47.30/kkg
($43/ton) in 22.7 kg (50 Ib) bags and energy requirements and
maintenance materials are negligible.
The operating mode is selected based on an annualized cost com-
parison assuming a 1,200 mg/1 lime dosage. The capital and
annual costs for this technology are presented in Figure VII1-7
(page 252).
Vacuum Filtration
The underflow from the clarifier is routed to a rotary precoat
vacuum filter, which dewaters the mostly hydroxide sludge (it
also includes calcium fluoride precipitate) to a cake of 20 per-
cent dry solids. The filtrate is recycled to the-rapid mix tank
as seed material for sludge formation.
The capital costs for the vacuum filter include the following:
- Vacuum filter with precoat but no sludge conditioning
- Housing
- Pump
The yield from the filter is assumed at 0.126 kg/hr/m2 (3
lb/hr/ft2) with a solids capture of 95 percent. Housing the
filter, which approximately doubles the capital cost of the
module, is required for this technology. The capital and annual
costs for this technology are presented in Figure VIII-8 (page
253). !
233
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Multimedia Filtration
Multimedia filtration is used as a wastewater treatment polishing
device to remove suspended solids not removed in previous treat-
ment processes. The filter beds consist of graded layers of
gravel, coarse anthracite coal, and fine ;sand. The equipment
used to determine capital and annual costs are as follows:
- Influent storage tank sized for one backwash volume
- Gravity flow, vertical steel cylindrical filters
with media (anthracite, sand, and garnet)
- Backwash tank sized for one backwash volume
- Backwash pump to provide necessary flow and head for
backwash operations
- Piping, valves, and a control system
The hydraulic loading rate is 63.2 lph/m2 (180 gph/ft2) and the
backwash loading is 252.8 lph/m2 (720 gph/ft2). The filter is
backwashed once per 24 hours for 10 minutes. The backwash volume
is provided from the stored filtrate. The backwash stream is
recycled to the clarifier. The capital and annual costs for this
technology are presented in Figure VIII-9 (page 254).
Effluent pollutant concentrations are based on the Agency's com-
bined data base for treatability of pollutants by filtration
technology.
Ultrafiltration
The ultrafiltration process employs a semipermeable polymeric
membrane to remove colloidal material from a wastewater. In con-
trast to multimedia filtration, ultrafiltration does not operate
intermittently, i.e., retained materials are continuously rather
than periodically removed.
The equipment costed for this process includes:
- Membrane modules
- Equalization tank
- Process tank
- Feed pump :
- Recirculation pump
- Piping
- Electrical and instrumentation
A flux rate of
tubular module.
0.51 lph/m2 (1.46 gph/ft2) is applied in the
Operation and maintenance labor is assumed to be negligible for
this module. Chemical costs include cleaning solution, caustic,
234
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and acid for pH control. Maintenance materials primarily include
replacement of filter membranes, which are estimated to have a
two year life. The capital and annual costs for this technology
are presented in Figure VIII-10 (page 255).
Cyanide Precipitation
Canmaking facilities that generate wastewaters with significant
concentrations of cyanide can reduce these by application of
cyanide precipitation technology. Cyanide is reacted with fer-
rous sulfate at pH 9.0 to form a ferrous cyanide complex. This
complex is precipitated by additional ferric ions to form
primarily a deep blue precipitate, Fe4 (FeCN6)3.
This continuous system, which closely resembles a conventional
chemical precipitation operation, includes chemical feed equip-
ment for sodium hydroxide and ferrous sulfate addition, a rapid
mix tank, agitator, control system, clarifier and pumps.
The FeS04 7H20 dosage is assumed at 11 times the stoichiometric
requirement. The clarifier overflow rate was assumed to be 7.3
lph/m2 (20.8 gph/ft2), with an underflow solids concentration of
3- percent. A portion of the underflow stream is recycled to the
rapid mix tank to provide seed sludge.
Annual costs for cyanide precipitation include:
(1) Ferrous sulfate feed system
—operating labor at 1.1 hr/1,000 kg per feeder
—maintenance labor at 32 hrs/yr
—maintenance materials at 3 percent of the manufac-
tured equipment cost
—electrical requirements for mixers, feeder operation,
building heating and lighting
(2) NaOH feed system
—operating labor at 190 hrs/yr per feeder
—maintenance labor at 8 hrs/yr
—maintenance materials at 3 percent of the manufac-
tured equipment cost
—electrical requirements for feeder, mixer, and pump
(3) Rapid mix tank
—operation and maintenance labor at 120 hrs/yr
—electrical requirements for agitator
(4) Clarifier
235
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—operation and maintenance labor varies from 150 hrs/
yr at 9.1 m (30 ft) diameter to 310 hrs/yr for 35 m
(115 ft) diameter
—maintenance materials include parts required for
drive mechanism and weirs
—energy requirements for motor size and torque
requirements for hydroxide sludges !
Costs for treatment chemicals are determined from t cyanide con-
centration, pH, metals concentrations, and flow rate of the raw
waste streams.
The capital and annual costs for this technology are displayed in
Figure VIII-11 (page 256).
Chromium Reduction
This technology can be applied to waste streams containing signi-
ficant concentrations of hexavalent chromium. Chromium in this
form will not precipitate until it has been reduced to the tri-
valent form. The waste stream is treated by addition of acid and
gaseous S02 dissolved in water in an agitated reactionvessel.
The S02 is oxidized to sulfate while reducing the chromium. The
equipment required for this continuous stream includes an S02
feed system (sulfonator), an H2S04 feed system, a reactor vessel
and agitator, and a pump. The reaction pH is 2.5 and the S02
dosage is a function of the influent loading of hexavalent
chromium. A conventional sulfonator is used to meter S02 to the
reaction vessel. The mixer velocity gradient is 100/sec.
Annual costs are as follows:
(1) S02 feed system
S02 cost at $0.11/kg ($0.25/lb) ;
—operation and maintenance labor requirements vary
from 437 hrs/yr at 4.5 kg S02/day (10 Ibs S02/day)
to 5,440 hrs/yr at 4,540 kg SO2/day'(10,000 Ibs S02/day)
—energy requirements at 570 kwh/yr at 4.5 kg S02/day
(10 Ibs SO2/day) to 31,000 kwh/yr at 4,540 kg
S02/day (10,000 Ibs SO2/day)
(2) H2S04 feed system
—operating and maintenance labor at 72 hrs/yr at 37.8 Ipd
(10 gpd) of 93 percent H2S04 to 200 hrs/yr at 3,780 Ipd
(1,000 gpd)
236
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—maintenance materials at 3 percent of the equipment
cost
—energy requirements for metering pump and storage
heating and lighting
(3) Reactor vessel and agitator
—operation and maintenance labor at 120 hrs/yr
—electrical requirements for agitator
The capital and annual costs for this technology are displayed in
Figure VIII-12 (page 257).
SYSTEM COST DEVELOPMENT
Existing Sources
To compile capital and annual costs for the canmaking subcate-
gory, the computer cost estimation model was utilized for the
following modules:
- Equalization,
- Chemical precipitation,
- Vacuum filtration, and
- Multimedia filtration.
The design and costing for the remaining modules have not yet
been incorporated into the cost estimation model. Consequently,
the Agency's existing cost data base for industries similar to
the canmaking subcategory was utilized to develop the costs for
these modules.
The cost evaluation was based on the identification of a "normal"
existing plant, which was postulated to operate three normal
processing lines. For currently existing facilities, the water
discharged is equal to 176 liters per thousand cans. The
processing rate for one normal line is 553 cans per minute. For
the BAT options, the water, discharged is 57.4 liters per thousand
cans through water conservation techniques (see Options 1 through
3 below). Further, water conservation technology available to
new sources reduces the water discharged to 14.0 liters per
thousand cans. These values were derived from data collected by
the Agency from can manufacturing plants of several sizes and
locations. The derivation of a "normal" canmaking process line
is discussed in Section IX. Also derived from these data were
representative pollutant concentrations. These values summarized
in Table VIII-1 (page 242).
237
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To calculate costs for lf 2, 4, 5f and 6 processing lines, the
six-tenths power rule was applied. This rule states that the
costs for plants of different sizes can be computed by multiply-
ing the base cost by the ratio raised to the six tenths power of
one plant's capacity over the base plant capacity:
Cost for plant B = cost for plant A x Capacity Plant B 0•6
Capacity Plant A
The slight error associated with this engineering rule does not
preclude its use as a mechanism for establishing costs for this
industry. i
The four options considered for BPT,'BAT and PSES were costed as
follows:
Option O_. This option includes equalization, chemical emulsion
breaking, dissolved air flotation, lime precipitation and
sedimentation, and vacuum filtration at the full BPT flow.
Option !_. This option includes all of Option 0 with flow
reduction in the canwasher discharge achieved through
countercurrent rinsing.
Option 2_. This option includes Option 1 plus multimedia
filtration as a polishing step after lime precipitation and
clarification. '
Option 3_. This option includes Option 2 plus ultrafiltration
after multimedia filtration.
The total costs for each option for each of the six model size
plants are displayed on Table VIII-2 (page 243). These costs
represent the capital investment and operating costs.
New Sources
The new source options include Options 0 through 3 and two
additional options. These are:
Option 4^ This option is Option 1 with a flow reduced to 14
liters per thousand cans based on additional flow reduction
achieved through design of water conservation techniques not
feasible for existing plants (including either an extended stage
canwasher operation or other water reuse technologies that will
achieve this flow reduction).
Option 5. This option is Option 4 with! multimedia polishing
filtration. The same flow as in Option 4 is used.
238
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The counter-current rinsing design basis for new sources differs
from the technology as applied in existing sources. An extended
stage canwasher operation was used as the basis since this
represents for many plants a suitable tradeoff between achievable
water conservation and the cost of additional equipment. Costs
were developed for this technology by adding additional equipment
similar to the two-stage operation costed for existing sources.
Additional piping, tankage, nozzles, and pumps were included to
expand the six-stage operation to a nine-stage operation.
The cost estimation procedure for new sources is otherwise iden-
tical to that used for existing sources. The total costs are
also presented on Table VII1-2. These costs represent the capi-
tal investment and operating costs for new source performance
standards and pretreatment standards for new sources. .
Treatment In Place
The costs listed in Table VIII
account for equipment that
When costs are computed for an
equipment already installed,
tracted from the total module
(costs such as engineering or
level as a percentage of
compliance costs that account
Table X-5 (page 277).
-2 are greenfield costs that do not
plants may already have in place.
actual plant that has some of the
that cost component must be sub-
cost before adding subsidiary costs
contingency added at the system
the installed equipment cost). The
for treatment in place are shown in
ENERGY AND NON-WATER QUALITY ASPECTS
Energy and non-water quality aspects of all of the wastewater
treatment technologies described in Section VII are summarized in
Tables VIII-3 and VIII-4 (pages 244 and 245). These general
energy requirements are listed, the impact on environmental air
and noise pollution is noted, and solid waste generation
characteristics are summarized. The treatment processes are
divided into two groups, wastewater treatment processes on Table
VIII-3, and sludge and solids handling processes on Table VIII-4.
Energy Aspects
Energy aspects of the wastewater treatment processes are
important because of the impact of energy on natural resources
and the economy. Based on dcp information from 5 plants
operating 13 lines, the EPA determined an energy consumption of
17.56 x 10« kwhr per line for canmaking operations, and 0.074 x
10« kwhr per line for treatment system operation. On this basis,
the 224 lines operated by the canmaking industry consumed
approximately 3.9 x 10" kwhr in 1981. Because the energy
239
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requirements for proposed BPT and BAT technology options are
essentially identical, the cost of energy for either of those
proposed technologies on the 20 lines operated by direct
dischargers is approximately 1.5 million 'kwhr/yr. The energy
requirements for proposed PSES technology on the 204 lines
operated by indirect dischargers is estimated to be 15.1 million
kwhr per year.
The energy requirements for the wastewater treatment options for
the subcategory are generally low. When compared to the total
plant energy usage, the wastewater treatment processes contribute
less than 0.5 percent to the overall energy usage. None of the
treatment options considered result in high energy consumption.
Non-Water Quality Aspects ;
It is important to consider the impact of each treatment process
on water scarcity; air, noise, and radiation; and solid waste
pollution of the environment to preclude the development of an
adverse environmental impact.
Consumptive Water Loss
Where evaporative cooling mechanisms are used, water loss may
result and contribute to water scarcity problems, a concern
primarily in arid and seim-arid regions. These treatment options
do not require substantial evaporative: cooling and recycling
which would cause a significant consumptive water loss.
Air Pollution
In general, none of the wastewater handling and treatment
processes considered for this subcategory cause air pollution
problems. For the precipitation of hexavalent chromium using S02
as a-reducing agent, the potential exists for the evolution of
S02 as a gas. However, proper design of the treatment tanks and
proper pH control eliminates this problem, j Incineration of waste
oil lubricants could cause air pollution problems which need to
be controlled by suitable scrubbers or precipitators, as well as
proper incinerator operation and maintenance. The wastewater
treatment sludges are not generally amenable to incineration
because of their high noncombustible solids content.
Noise and Radiation :
None of the wastewater treatment processes cause objectionable
noise levels and none of the treatment processes has any
potential for radioactive radiation hazards.
Solid Waste
240
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Costs for treatment sludge handling were included in the costing
analysis performed for the subcategory. To estimate the amount
of treatment sludge produced as a result of the proposed
treatment technologies, the mass of sludge produced annually per
normal line is used. A computer program is used to estimate
sludge generated by a normal line based on the removals at each
treatment level given in Table X-l. A 20 percent solids content
of the sludge can and a 10 percent excess of lime are the
essential calculation parameters. Total annual sludge generation
for each level is calculated from the number of lines operated by
direct dischargers, and indirect dischargers. For new sources a
plant with six normal lines is used.
The lime precipitation and settling technology produces a sludge
with a high solids content, consisting of calcium salts and a
high pH. When this waste stream is subjected to the RCRA
hazardous waste criteria/ it is judged to be nonhazardous and
therefore no hazardous waste disposal costs are attributed to
disposal of the sludge.
Spent lubricating oil waste is also generated by canmaking plants
and is generally disposed of in a landfill or reclaimed by
contract waste haulers. .Based upon dcp data, the quantity of
this spent lubricant is estimated to be 212.7 kkg/yr/line (12,083
gallons per year) for an average line based on data from 125
canmaking lines. Since the spent lubricant is considered to be
nonhazardous under RCRA criteria, there are no RCRA related costs
attributed to the disposal of this material.
241
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Table VIII-1
WASTEWATER CHARACTERISTICS FROM CAN MAKING
USED FOR COST ESTIMATES
Parameter
Chromium
Zinc i
Aluminum
Fluoride
Iron
Manganese
Phosphorus
Oil and Grease
TSS
pH
iValue
4.99 mg/1
3.7 mg/1
370 mg/1
21.2 mg/1
5.4 mg/1
2.0 mg/1
23.5 mg/1
4,721 mg/1
345 mg/1
6 pH units
242
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Initialize
Conscants
Executive
Routine to Call
Required Modules
Design
Parameters
Call-Cost
Routine
Call-Cost
Equations
For Each Module
Compute
System Costs
Output
Costs
Figure VIII-1
GENERAL LOGIC DIAGRAM OF DESIGN AND COST PROGRAMS
246
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Data from
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Uaatewater
Assume Initial
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Print Material
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Go to Next
Module
Figure VIII-2
LOGIC DIAGRAM OF MODULE DESIGN PROCEDURE
247
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Design Values
and Configuration
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Balance Program
Call Module
Subroutines
Cost Equations
Compute Summed
Module Costs
Compute System
Costs
Output Costs
Figure VIII-3
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LOGIC DIAGRAM OF THE COSTING ROUTINE
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SECTION IX
BEST PRACTICABLE CONTROL TECHNOLOGY
CURRENTLY AVAILABLE
This section defines the effluent characteristics attainable
through the application of best practicable control technology
currently available (BPT). BPT reflects the performance by
plants of various sizes, ages, and manufacturing processes within
the canmaking subcategory.
The factors considered in defining BPT include the total cost of
applying the technology in relation to the effluent reduction
benefits from such application, the age of equipment and
facilities involved, the process employed, non-water quality
environmental impacts (including energy requirements) and other
factors the Administrator considers appropriate. In general, the
BPT level represents the average of the best existing
performances of plants of various ages, sizes, processes or other
common characteristics. Where existing performance is uniformly
inadequate, BPT may be transferred from a different subcategory
or category. Limitations based on transfer technology must be
supported by a conclusion that the technology is, indeed,
transferrable and a reasonable prediction that it will be capable
of achieving the prescribed effluent limits. See Tanners'
Council of America v. Train. BPT focuses on end-of-pipe
treatment rather than process changes or internal controls,
except where such are common industry practice.
TECHNICAL APPROACH TO BPT
EPA first studied canmaking operations to identify the processes
used and the wastewaters generated during the canmaking process.
Information was collected through previous work, dcp forms and
specific plant sampling and analysis. The Agency used these data
to determine what constituted an appropriate BPT.
Canmaking consists of cupping, drawing and ironing, and washing,
where the cans are cleaned and prepared for the decoration
process. These process steps generate different wastewater
streams. In all wastestreams, as discussed in Sections III and
IV, the volume of wastewater is related to the number of cans
processed.
As a mechanism for evaluating costs and environmental benefits
the Agency used the concept of a "normal" canmaking line. A
normal line is defined as a production module having the average
production rate per line of the industry (553 cans/min);
generating wastewater at the mean wastewater level of the
259
-------
category (255 1/1000 cans) or at the regulatory flow used for
specific options; and having raw wastewater characteristics equal
to the average pollutant concentrations of the sampled aluminum
plants (See Table V-8). Data on the number of lines in each
plant and production rates were supplied in the dcp for each
plant.
This document has already discussed some of the factors which
must be considered in establishing effluent limitations based on
BPT. The age of equipment and facilities and the processes
employed were taken into account and are discussed fully in
Section IV. Nonwater quality impacts and energy requirements are
considered in Section VIII.
The general approach to BPT for this subcategory is to treat all
canmaking wastewaters in a single (combined) treatment system.
Normal practice is to combine wastewater for treatment because it
is less expensive. Oil which is used as a!lubricant and coolant
during the formation of the seamless can body, and is removed
during washing, must be remoyed from ;the wastewater. ana
hexavalent chromium, where present, must; be reduced to the
trivalent state so that it can be precipitated and removed along
with other metals. The dissolved metals must be precipitated and
suspended solids, including the metal precipitate, removed.
Therefore, the strategy for BPT is reuse of rinsewaters in the
canwasher; oil removal by dissolved air flotation and emulsion
breaking; chromium reduction and cyanide precipitation when
necessary; and follow or combine with lime and settle technology
to remove metals and solids from the wastewaters. (See Figure
IX-1, page 265). Regulatory flow used as the basis for
calculating BPT is the average of the plants having the best
water use characteristics. ;
SELECTION OF POLLUTANT PARAMETERS FOR REGULATION
The pollutant parameters selected for regulation in the canmaking
subcategory were selected because of their frequent presence at
treatable concentrations in wastewaters from the industry. In
addition to oil and grease, TSS, and pH, the traditional
pollutants chromium, zinc, aluminum, fluoride and phosphorus are
regulated.
DEVELOPMENT OF CANMAKING SUBCATEGORY BPT
The BPT model treatment train for canmaking wastewater consists
of in-process reuse of canwasher water, chromium reduction and
cyanide precipitation when necessary; mixing and pH adjustment of
the combined wastewaters with lime or acid to precipitate metals;
oil skimming, dissolved air flotation, and chemical emulsion
breaking as required to remove oil and grease plus some toxic
260
-------
organics; and settling to remove suspended solids plus
precipitated metals. Forty-eight aluminum canmaking plants
provided sufficient information on their dcps to calculate the
mean production normalized process water use.
The flow basis for BPT is the mean for the 32 plants where water
reuse in the canwasher is practiced. The production normalized
water use for the canmaking subcategory at BPT is 176.7 1/1000
cans as presented in Table V-6.
Cyanide compounds may be used in some conversion coating
formulations applied to aluminum cans and when used is reflected
in the cyanide concentrations found in rinse waters from the
canwasher. Cyanide removal by precipitation is the recommended
cyanide control technology for conversion coating dumps and
rinses.
Plants with production normalized flows significantly above the
mean flow used in calculating the BPT limitations will need to
reduce flows to meet the BPT limitations. Generally this
reduction can be made by incorporating reuse of water within the
canwasher - i.e., the same water is used for more than one
operation within the canwasher before discharging it to
treatment. Other specific water conservation practices
applicable to reducing excess water use are detailed in Section
VII.
Most of the canmaking plants sampled by EPA appear to have
elements of the model BPT treatment system already in place and
12 of those submitting dcps indicate that they have all of the
elements. Of the plants for which usable treatment system
information from dcp was received: 53 have oil removal equipment
including 17 that have emulsion breaking and 16 that have
dissolved air flotation in place; 28 have equipment for chemical
precipitation and clarification; 7 plants have hexavalent
chromium reduction in place and 32 plants practice water reuse in
the canwasher. However, observations by sampling teams and
results of effluent analyses suggest that most treatment systems
are not properly operated, or are not operated at all. The
result is apparent inadequate treatment system effectiveness for
the subcategory. Treatment effectiveness data, therefore was
transferred from other categories. These data provide a sound
statistical basis for predicting the effectiveness of properly
operated lime and settle systems on canmaking wastewaters (see
Section VII). Data in Tables V-9 and V-10 demonstrate the
appropriateness of using the larger treatment effectiveness data
base compiled from a number of categories with similar
wastewater.
261
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A statistical test of homogeneity was applied to raw wastewaters
from the canmaking sampled plants and the combined metals data
base. This test revealed the canmaking raw wastewaters to be
homogeneous with those from the combined metals data base.
Therefore, in the absence of data from properly operating BPT
technology where it is installed at canmaking plants, the EPA
considers transfer of treatment effectiveness from the combined
metals data base to be appropriate. Some plant sampling days for
this subcategory show performance equivalent to that of the
combined metals data base.
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Typical characteristics of total raw wastewjater for the canmaking
subcategory are given in Table V-8. The combination of lime and
settle technology with oil removal and other pretreatment when
necessary will reduce the concentration of regulated pollutants
to the levels described in Table VII-21. When these
concentrations are applied to the dcp mean wastewater flow
described above, the mass of pollutants allowed to be discharged
per 1000 cans is readily calculated. Table IX-1 (page 264) shows
the limitations derived from this calculation.
To determine the reasonableness of these limitations, EPA
reviewed the data for regulated pollutants from the sampled
plants (Table V-12, page 60) to determine how many plants were
meeting this BPT. One plant (ID #565) met the mass based
limitations all three sampling days. A second plant (ID # 557)
met all limitations except for oil and grease on two of the three
sampling days and pH for all three sampling days. The third
plant (ID #488) appears not to have operated its solids removal
and oil removal systems on any of the three sampling days.
Despite the fact that pH was well within limits all three days,
zinc, aluminum, oil and grease, and TSS grossly exceeded the mass
limitations all three days. The fourth plant (ID #515) data were
not used for this comparison (even though it met BPT) because it
has polishing filtration before discharge. All of the sampled
plants had BPT technology installed except that oil removal was
accomplished at three plants using gravity separation only; the
fourth plant had emulsion breaking and dissolved air flotation
equipment installed. Based on these comparisons, the proposed
BPT limitations for the canmaking subcategory are reasonable.
Oil and grease limitations can be met with properly operated oil
removal equipment (see Table VII-11) including skimming, and
chemical emulsion breaking, and dissolved air flotation; and
metals and TSS limitations can be met with pH adjustment and
settling. Close pH control is essential. When pH falls below
the lower limit, metals are not removed. At pH's above the upper
limit, metals that become soluble as oxygenated anions return to
solution. The proposed limitations (Table IX-1) (page 264) for
the canmaking subcategory are reasonable.
262
-------
In the establishment of BPT, the cost of applying a technology
must be considered in relation to the effluent reduction benefits
achieved by such application. The quantity of pollutants removed
by BPT is displayed in Table X-4 (page 276) and the total cost of
application of BPT is shown in Table X-5 (page 277). The capital
cost of BPT as an increment above the cost of in-place treatment
equipment is estimated to be $1,000,000. Annual cost of BPT for
the canmaking subcategory is estimated to be $450,000. The
quantity of pollutants removed above raw wastewater by the BPT
system for the subcategory is estimated to be 7.31 million kg/yr
including 4,415 kg/yr of toxic pollutants. EPA believes that the
effluent reduction benefit outweighs the dollar cost of required
BPT.
263
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TABLE IX-1
BPT Effluent Limitations
Canmaking Subcategory
Pollutant or
Pollutant Property
BPT Effluent Limitations
Maximum for Maximum for
any one day monthly average
q (lbs)/1,000,000 cans manufactured
Cr
Zn
Al
F
P
O&G
TSS
pH
74
235
803
10513
2950
3534
7244
.21
.01
.98
.65
.89
.00
.70
within
(0
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the
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. 130
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.938
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range
30
98
328
4664
1206
2120
3534
of 7.5
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264
-------
Ul
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265
-------
-------
SECTION X
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
The effluent limitations in this section apply to existing direct
dischargers. A direct discharger is a facility which discharges
or may discharge pollutants into waters of the United States.
This section presents information on direct dischargers, and in
addition presents total category data.
The factors considered in assessing best available technology
economically achievable (BAT) include the age of equipment and
facilities involved, the processes employed, process changes,
non-water quality environmental impacts (including energy
requirements) and the costs of application of such technology
(Section 304(b)(2)(B). BAT technology represents the best
existing economically achievable performance of plants of various
ages, sizes, processes or other shared characteristics. As with
BPT, those categories whose existing treatment system performance
is uniformly inadequate may require a transfer of BAT from a
different subcategory or category. BAT may include process
changes or internal controls, even when these are not common
industry practice.
TECHNICAL APPROACH TO BAT
In establishing BAT limitations, the Agency reviewed a wide range
of technology options. These options included the range of
available technologies applicable to the category .
As a general approach for the category, three levels of BAT which
accomplish reduction in the discharge of toxic pollutants greater
than that achieved at BPT were evaluated. Extreme technologies
such as distillation and deep space disposal were rejected a
priori as too costly or not proven.
The Agency proposes BAT based on the following treatment
technologiess
hexavalent chromium reduction, when necessary
cyanide precipitation, when necessary
oil skimming, chemical emulsion breaking, and dissolved
air flotation
hydroxide precipitation and sedimentation of metals
water reuse
two-stage countercurrent cascade spray rinse following
conversion coating in the canwasher
sludge dewatering
267
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The Agency also considered other treatment technologies
including: polishing filtration, and ultrafiltration as outlined
in the following descriptions of the three BAT options
considered.
treatment and adds
Option 1_
Option 1 is based on BPT end-of-pipe
in-process controls. The technologies are:
• chromium reduction, when required
• cyanide removal, when required ;
• chemical emulsion breaking, dissolved air
flotation, and oil skimming
• hydroxide precipitation
• settling
• in process water reduction technology
- countercurrent cascade sprayrinsing in the
rinse stage of the canwasher following con-
version coating
- water reuse
Option 2_
Option 2 builds on option 1 by including all of 1 technology and
adding polishing filtration.
Option 3_
Option 3 builds on option 2 by including all of 2 technology and
adding ultrafiltration. :
i „' ' •',„ „!, ,,.,' ',„";„if M ,' • ' .,„ " I, ' ; ',!'':,' >\ '••
-------
an existing
as effective
cans) is allocated for non-rinse purposes (e.g. oil sump
discharge, ion exchange column regeneration, fume scrubber
discharge, batch dumps of the acid cleaner and conversion coating
spray recycle sumps). The overall water use for the selected BAT
option is (0.10 x 176.7) plus (0.25 x 0.90 x 176.7) which equals
0.325 x 176.7 or 57.43 1/1000 cans. Section VII contains the
details of assumptions and calculations used to establish the
basis of achievable countercurrent rinse turn-down ratio. The
theoretically achievable rinse water reduction is greater than
that used for BAT. The calculations in Section VII show that
2-stage countercurrent rinsing could reduce rinse water
requirements to 25.7 1/1000 cans. However, because the BAT
limitations are for existing sources, and retrofitting of baffles
and additional spray rinse racks is the method of achieving
countercurrent rinsing in the fixed space of
canwasher, the 2-stage rinse is not expected to be
as if the full length were available as in a new installation.
The actual rinse water use of 39.78 1/1000 cans for BAT is
therefore more than 50 percent greater than the theoretically
achievable value. The selected BAT will remove 184 kg/yr of
toxic pollutants over the pollutant removal achieved by BPT. The
economic impact analysis indicates that BAT is economically
achievable.
The incremental pollutant removal benefits of BAT 2 (see Figure
X-2, page 280) above BAT 1 would be the removal annually of 18 kg
of total toxics and 10,000 kg of other pollutants (see Table
X-2). Addition of filtration therefore would result in the
additional removal of only about 0.01 kg per day per direct
discharger. The Agency concluded that filtration for existing
facilities would achieve little additional toxic pollutant
reduction.
BAT option 3 (see Figure X-3, page 281) was not proposed because
of the very substantial costs and extremely low additional
pollutant removals. Removals were less than one kilogram of
additional toxics removal above the selected BAT option, and
capital and annual cost were about five times those of the
selected option.
Industry Cost and Effluent Reduction Benefits of. Treatment
Options
An estimate of capital and annual costs for BPT, BAT 1, BAT 2,
and BAT 3 was prepared. The capital cost of treatment technology
in place according to dcps was also calculated using the
methodology in Section VIII. Results are presented in Table X-5
(page 277).
269
-------
Pollutant reduction benefits were derived by (a) characterizing
raw wastewater and effluent from each proposed treatment system
in terms of concentrations produced and production normalized
discharges (Table X-i, page 273) for each significant pollutant
found; (b) calculating the quantities removed and discharged in
one year by a "normal line" (Table X-2 '. page 274); and (c)
calculating the quantities removed and discharged in one year for
the industry - direct and indirect dischargers (Table X-3, page
275). Table X-4 (page 276) summarizes treatment performances for
BPT and each BAT option by giving the mass :of pollutants removed
and discharged for each option for direct dischargers. Tables
X-l through X-3 present pollutant reduction benefits for all
plants in the category. Table X-4 presents pollutant reduction
benefits for direct dischargers in the category. The pollutant
reduction benefit table for indirect dischargers is presented in
Section XII. Table X-5 (page 277) presents1 costs for plants with
1 through 6 normal lines, total for direct dischargers, and total
for indirect dischargers. All pollutant parameter calculations
were based on mean raw wastewater concentrations for visited
plants (Table V-8, page 50) and mean water use for the treatment
option.
REGULATED POLLUTANT PARAMETERS
The raw wastewater concentrations from individual operations were
examined to select appropriate pollutant parameters for specific
regulation. In Section VI each of the toxic pollutants was
evaluated and .a determination was made as to whether or not to
further consider them for regulation. '. Pollutants were not
considered for regulation if they were not detected, detected at
non-quantifiable levels, unique to a small number of plants, or
not treatable using technologies considered. All toxic
pollutants listed for further consideration are discussed in this
Section. Several toxic or non-conventional metal pollutants are
regulated.
The Agency found small amounts of several toxic organic compounds
(collectively referred to as total toxic organics or TTO) in
canmaking wastewaters. The concentration present is 2.73 mg/1
(see Table V-8, page 50). The percent removal of organics by oil
skimming from coil coating, copper forming and aluminum forming
plants is presented in Section VII. The average removal of
organics in aluminum forming by oil skimming is about 97 percent.
This removal rate is used for projecting the effectiveness of oil
skimming in removing TTO in canmaking because some of the rolling
oils from forming are carried into the canmaking operation and
the raw wastewater levels of oil in canmaking and aluminum
forming are relatively similar. Except for methylene chloride,
all of the toxic organic pollutants found in canmaking are found
in coil coating, aluminum forming, or copper forming and have
270
-------
been shown to be removed by oil removal. TTO is not regulated at
BAT because it is incidentally removed with oil and grease which
is adequately controlled at BCT.
Pollutant parameters selected for regulation in canmaking at BAT
are: chromium, zinc, aluminum, fluoride, and phosphorus. The
toxic metals selected for specific regulation are total chromium
and zinc. The effluent limitations achieved by application of
the selected BAT Option are also presented. Hexavalent chromium
is not regulated specifically because it is included in total
chromium. Only the trivalent form is removed by the lime and
settle technology. Therefore the hexavalent form must be reduced
to meet the limitation on total chromium. Copper, lead and
nickel are not regulated because they are present at low
concentrations and will be adequately removed by the suggested
technology when it is operated to remove the other regulated
pollutants.
Aluminum is regulated at BAT primarily because it is always
present in the wastewaters and it is present in high
concentrations. In these proposed regulations, only two toxic
metals are regulated. If process technology is changed
eliminating the introduction of those two metals, but introducing
other toxic metals, the regulation of aluminum will assure their
control.
Fluoride and phosphorus are regulated at BAT because they are
commonly recognized pollutants found in the wastewaters from most
canwashers and their control will help assure the proper
operation of lime and settle technology.
CANMAKING SUBCATEGORY BAT
BAT Regulatory Flow Calculations
The BAT regulatory flow was developed by assuming that a six
stage canwasher (see Figure III-3) was modified to have a
countercurrent rinse after the conversion coating stage. This
modification of the process is discussed in Section VII. Using
the model BAT system, the flow calculation assumes that
countercurrent cascade rinsing is used in the canwasher. The BAT
wastewater flow was obtained using visited plant data as a model
to determine what portion of total plant flow (all operations) is
attributable to rinsing.
The BAT wastewater allowance for canmaking becomes 57.43 1/1000
cans which is 32.5 percent of the BPT wastewater allowance, as
271
-------
discussed earlier in this section. This water use will be used
to calculate expected performance for BAT.
BAT Effluent Limitations Calculation j
The end-of-pipe treatment applied to the :BAT regulatory flow
detailed above, would produce the Affluent concentrations of
regulated pollutants shown in Section VII, Table VII-21 for
precipitation and sedimentation (lime and settle) technology.
When these concentrations are applied to the plant water use
described above, the mass of pollutant allowed to be discharged
pe? million cans produced can be calculated;. Table X-6 sh°*s the
limitations derived from this calculation The Pollutants listed
as "considered for regulation" in Table VI-1, for which
regulation is not proposed, will be adequately /foyed
coincidentally if the regulated pollutants are removed to the
specified levels.
DEMONSTRATION STATUS j
Each element of the BAT system is demonstrated however, no
sampled canmaking plants use the BAT technology in its entirety.
The BAT model system has the same end-of-pipe treatment as BPT
and twelve plants have the model end-of-pipe treatment equipment
in olace. Data supplied by the canmaking companies in their dcp
responses indicate that six plants achieve the BAT regulatory
flow using countercurrent cascade rinsing in the canwasher. The
in-process water use reduction and end-of-pipe treatment are both
demonstrated.
272
-------
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TABLE X-6
BAT EFFLUENT LIMITATIONS
CANMAKING SUBCATEGORY
Pollutant or
Pollutant Property
BAT Effluent Limitations
Maximum for Maximum for
any one day monthly average
g (lbs)/l,000,000 cans manufactured
Cr
Zn .
Al
F
P
24.10
76.34
261.17
3415.30
958.58
(0.053)
(0.167)
(0.574)
(7.513)
(2.108)
9.75
32.14
106.76
1515.36
392.04
(0.021)
(0.070)
(0.234)
(3.333)
(0.862)
"' , ' • • •
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SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
This section presents effluent characteristics attainable by new
sources through the application of the best available
demonstrated control technology, processes, operating methods, or
other alternatives, including where practicable, a standard
permitting no discharge of pollutants. Five levels of technology
are discussed with respect to costs, performance, and effluent
reduction benefits. The rationale for selecting one of the
technologies is outlined. The selection of pollutant parameters
for specific regulation is discussed, and discharge limitations
for the regulated pollutants are presented.
TECHNICAL APPROACH TO NSPS
As a general approach for the category, five levels of NSPS
options were evaluated. The levels are generally identical to or
build on BAT technology options. The BAT options and the
detailed discussion and evaluation of them carried out in Section
X are incorporated here by specific reference rather than
repeated in this section.
NSPS options 1, 2, and 3 are identical to BAT 1, BAT 2, and BAT
3, respectively which are described in detail in Section X. The
schematic diagrams of those systems are presented in Figures X-l,
X-2, and X-3. In summary form, the two additional NSPS treatment
options are:
At NSPS 4:
- in-process water use reduction
• extended multi-stage canwasher or its equivalent
end-of-pipe (identical to NSPS 1)
chromium reduction, when required
cyanide removal, when required
chemical emulsion breaking, dissolved air flotation,
oil skimming
hydroxide precipitation
sedimentation
At NSPS 5: All of NSPS 4 plus end-of-pipe polishing filtration.
An option requiring no discharge of process wastewater pollutants
was also considered. One plant is achieving this level of
pollutant reduction using water use reduction, ultrafiltration,
reverse osmosis, and water reuse. This system for pollutant
reduction is costly; investment costs greater then $1.7 million
and annual costs greater than $0.97 million are projected for a
283
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six line production plant. This option is'not considered as the
basis for NSPS because of the high costs associated with this
technology. ;
s , , ,, ', ••,.,,•, ,;
NSPS Options 4_ and _5_
The use of an extended multi-stage canwasher, 9-stage or its
equivalent, (See Figure III-4) in water use reduction, reduces
total discharge flow to 14.0 1/1000 cans. The end-of-pipe
technologies for NSPS 4 and NSPS 5 (Figures XI-1 and XI-2, pages
291 and 292) are identical to the end-ofrpipe technologies for
NSPS 1 and NSPS 2. The incorporation of at least 3 additional
stages for countercurrent rinse and reeirculation of rinses
reduces water use to 25 percent of the BAT value and less than 10
percent of the average raw wastewater discharge for aluminum
bodies. Because new plants can be built toiaccommodate the extra
stages without disrupting ongoing production, the use of a 9
stage canwasher as the basis for the NSPS 4 and NSPS 5 does not
introduce a significant investment increase over NSPS 1 pr NSPS 2
costs. In addition, a new plant can be designed to minimize or
eliminate wastewater discharges from other sources (e.g. oil
sumps, ion exchange regeneration, fume scrubber, and batch dumps
of process solutions).
NSPS OPTION SELECTION
EPA is proposing NSPS 4 for new source performance standards.
Options 1, 2 and 3 were not selected because option 4 provides
greater removal of pollutants and is economically achievable.
Option 5 was not selected because the addition of filtration to
the small effluent flow would achieve little additional toxic
pollutant reduction.
EPA selected the final NSPS because it provides a reduced
discharge of all pollutants below the final! BAT (compare Table
XI-1 with Table X-l). The model NSPS technology is less costly
than the BAT technology because the flow .reduction achieved will
allow the use of a smaller treatment system (see Table VIII-2).
Countercurrent Rinses - Countercurrent rinsing is a mechanism
commonly encountered in metal processing operations where
uncontaminated water is used for the finalcleaning of an item,
and water containing progressively more contamination is used to
rinse the more contaminated part. The process achieves
substantial efficiencies of water use and rinsing; for example,
the use of a two stage countercurrent rinse to obtain a rinse
ratio of about 100 can reduce water usage by a factor of
approximately 10 from that needed for a single stage rinse to
achieve the same level of product cleanliness. Similarly, a
284
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three stage countercurrent rinse would reduce water usage by a
factor of approximately 30 for the same rinse ratio. The
theoretical basis for the water use reduction achieved by 3-stage
countercurrent rinsing is presented in Section VII. (Also see
Figure III-4).
Cost and Effluent Reduction Benefits of NSPS
Estimates of capital and annual costs for a new plant with one to
six normal lines for NSPS-4 and NSPS-5 are presented in Table
VIII-2 (page 243).
In calculating NSPS costs, EPA used the "normal line" production
as derived in Section IX and estimated that a new (greenfield)
plant would be a large plant containing six canmaking lines. The
production from this plant was multiplied by the NSPS regulatory
flow, to derive the plant flows for cost estimation. The
extended multistage canwasher was estimated as the added cost for
pipes, pumps and other parts. No plant production or specific
construction cost is included.
The pollutant reduction benefit was derived by (a) characterizing
raw wastewater and effluent from each proposed treatment system
in terms of concentrations produced and production normalized
discharges for each significant pollutant found; and (b)
calculating the quantities removed and discharged in one year by
a "normal line.™ Results of these calculations are presented in
Table XI-2 (page' 289).. All pollutant parameter calculations were
based on mean raw wastewater concentrations for visited plants.
See Table V-8, page 50.
REGULATED POLLUTANT PARAMETERS
The Agency reviewed the wastewater concentrations from individual
operations to select those pollutant parameters found most
frequently and at the highest levels. In Section VI each of the
toxic pollutants was evaluated and a determination was made as to
whether or not to further consider them for regulation.
Pollutants were not considered for regulation if they were not
detected, detected at nonquantifiable levels, unique to a small
number of plants, or not treatable using technologies considered.
All toxic pollutants listed for further consideration are
discussed in this section.
Oil and grease, TSS, and pH were selected for regulation with
several toxic or non-conventional metal pollutants. In the
proposed regulation, the toxic metals selected for control
included all those for which the concentration in the raw
wastewater was above the treatability limit.
285
-------
Chromate conversion coating can be applied to aluminum surfaces
and cyanide compounds are used in some conversion coating
formulations applied to aluminum strip. To insure that there is
no additional discharge of pollutants from conversion coating
waters, chromium is regulated.
In addition to the pollutant parameters listed above, there is
some amount of other toxic pollutants in the canmaking
wastewaters. The Agency is using an oil and grease standard for
new sources in order to control the oil soluble organics found in
these wastewaters. Although a specific numeric standard for
organic priority pollutants is not established, adequate control
is expected to be achieved by controliof the oil and grease
wastes. This is projected to occur because of the slight
solubility of the compounds in water and their relatively high
solubility in oil. This difference in solubility will cause the
organics to accumulate in and be removed with the oil (See Tables
VII-12, VII-13, and VII-29, pages 180, 181, and 192).
The metals selected for specific regulation are discussed and the
performance standards achieved ; by application of NSPS also are
presented. Hexavalent chromium is not regulated specifically
because it is included in total chromium. Only the trivalent
form is removed by the lime and settle technology. Therefore,
the hexavalent form must be reduced to meet the limitation on
total chromium.
CANMAKING SUBCATEGORY NSPS I
The NSPS regulatory wastewater flow for the'canmaking subcategory
is 14.0 1/1000 cans. This level of wastewater discharge is
supported in two ways. Three plants supplied data indicating
their wastewater discharge from canmaking to be equal to or less
than 14.0 1/1000 cans (ID #438-14.0 1/1000 cans; ID #550-13.2
1/1000 cans and ID #557-11.33 1/1000 cans). Additionally, an
examination of countercurrent cascade spray rinsing applied to
canwashing clearly shows this level of wastewater discharge to be
technically achievable. The NSPS; regulatory flowis selected as
the largest of the three exemplary flows and is therefore
supported by both theory and field application.
Pollutant parameters selected for regulation for NSPS are:
chromium, zinc, aluminum, fluoride, phosphorus, oil and grease,
TSS, and pH. The end-of-pipe treatment applied to reduced flow
would produce effluent concentrations of regulated pollutants
equal to those shown in Section VII, Table VII-21 for
precipitation and sedimentation (lime and settle) technology. pH
must be maintained within, the range 7.5 - 10.0 at all times.
286
-------
When these concentrations are applied to the water use described
above, the mass of pollutant allowed to be discharged per
1,000,000 cans produced can be calculated. Table XI-3, shows the
standards derived from this calculation.
DEMONSTRATION STATUS
Each major element of the NSPS technology is demonstrated in one
or more canmaking plants, however no sampled canmaking plant uses
all of the NSPS technology. The NSPS model system has all the
same treatment components of BAT-1 plus the application of
extended multistage canwashing. Early in this study four plants
were identified as having water use equivalent to the NSPS water
use. A recheck of calculations revealed that an error had been
made in calculations for one plant. Therefore, the water use for
NSPS is supported by data from 3 plants.
Countercurrerit cascade spray rinsing can achieve this level. The
end-of-pipe treatment is the same as BAT plus polishing
filtration. Twelve plants have the BAT end-of-pipe treatment in
place and filtration equipment is in place at ten plants. NSPS
technology is demonstrated in the canmaking subcategory.
287
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289
-------
TABLE XI-3
NEW SOURCE PERFORMANCE STANDARDS
CANMAKING SUBCATEGORY
Pollutant or
Pollutant Property
NSPS Effluent Limitations
Maximum for Maximum for
any one day monthly average
g (lbs)/1.000.000 cans manufactured
Cr
Zn
Al
F
P
O&G
TSS
PH
5.88
18.62
63.7
833.0
233.8
280.0
574.0
within
(0.013)
(0.041 )
(0.140)
(1.833)
(0.514)
(0.616)
(1.263)
the ranqe of
2.38
7.84
26.04
369.60
95.62
168.0
280.0
7.5 to
(0.005)
(0.017)
(0.057)
: (0.813)
(0.210)
1 (0.370)
! (0.616)
10 at all times
i
f ' ', , ''• , !
1 , , , , ,
j „ , „ ,
r .• • • :
290
-------
0
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ca
II
291
-------
B
3
C9
292
-------
SECTION XII
PRETREATMENT
The model control technologies for pretreatment of process
wastewaters from existing sources and new sources are described.
An indirect discharger is defined as a facility which introduces
pollutants into a publicly owned treatment works (POTW).
Pretreatment standards for existing sources (PSES) are designed
to prevent the discharge of. pollutants that pass through,
interfere with, or are otherwise incompatible with the operation
of publicly owned treatment works (POTW). They must be achieved
within three years of promulgation. The Clean Water Act of 1977
requires pretreatment for pollutants that pass through the POTW
in amounts that would violate direct discharger effluent
limitations or interfere with the POTW's treatment process or
chosen sludge disposal method.
The legislative history of the 1977 Act indicates that
pretreatment standards are to be technology-based, analogous to
the best available technology for removal of toxic pollutants.
The general pretreatment regulations, which served as the
framework for the pretreatment regulations, are found at 40 CFR
Part 403. See 43 FR 27736 June 26, 1978, 46 FR 9404 January 28,
1981, and 47 FR 4518 February 1, 1982.
PSNS are to be issued at the same time as NSPS. New indirect
dischargers,, like new direct dischargers, have the opportunity to
incorporate the best available demonstrated technologies. The
Agency considers the same factors in promulgating PSNS as it
considers in promulgating PSES.
Most POTW consist of primary or secondary treatment systems which
are designed to treat domestic wastes. Many of the pollutants
contained in canmaking wastes are not biodegradable and are
therefore ineffectively treated by such systems. Furthermore,
these wastes have been known to interfere with the normal
operations of these systems. Problems associated with the
uncontrolled release of pollutant parameters identified in
canmaking process wastewaters to POTW were discussed in Section
VI. The pollutant-by-pollutant discussion covered pass through,
interference, and sludge usability.
EPA has generally determined there is pass through of pollutants
if the percent of pollutants removed by a well operated POTW
achieving secondary treatment is less than the percent removed by
293
-------
the BAT model treatment technology. PpTW removals of the
priority pollutants found in canmaking wastewater are presented
in Table XII-1 (page 297). The average removalof toxic metals
is about 65 percent. The BAT treatment technology removes more
than 99 percent of toxic metals (see Table X-2, page 274). This
difference in removal effectiveness clisarly indicates pass
through of toxic metals will occur unless canmaking wastewaters
are adequately pretreated. Therefore, two toxic metals are
regulated. As at BAT, aluminum is regulated to control toxic
metals which could easily be substituted for the two which are
specifically regulated. However, no removal credit can be
claimed for aluminum because its is regulated to assure
installation and operation of the technology.
Fluoride and phosphorus both pass through POTW. POTW remove no
fluoride. POTW removal of phosphorus is 10 to 20 percent. The
BAT treatment technology removes more than 80 percent of these
pollutants (see Table X-2).
The Agency found small amounts of several toxic organics in
canmaking wastewaters. The Agency considered and analyzed
whether these pollutants should be specifically regulated.
The removal of toxic organics is about 70 percent by a secondary
POTW (Table XII-1, page 297). The treatment technology for
organics removal is oil skimming. The mean raw wastewater level
of TTO (total toxic organics) in canmaking wastewaters is 2.73
mg/1 (Table XII-2, page 298). The wastewaters from aluminum
forming are similar in oil and grease loading to those from
canmaking. The percent removal of organics by oil skimming from
aluminum forming category wastewaters is presented in Section
VII. The average removal of organics by oil skimming in aluminum
forming is about 97 percent. This clearly indicates that pass
through of TTO will occur unless canmaking wastewaters are
adequately pretreated. Clearly there is pass through of total
toxic organics, therefore TTO is regulated.
The model treatment technology system for pretreatment at
existing sources (PSES) is the same as the'.BAT treatment system.
(See Figure X-2). The model treatment system for new sources
(PSNS) is the same as BDT for NSPS. (See Figure XI-1). These
model technologies were selected for the reasons explained in the
BAT and NSPS sections. Oil removal is included in the PSES and
PSNS control technologies, benefits, and costs. The Agency
believes oil and grease removal is needed to meet the total toxic
organics limitations therefore, an oil and grease standard is
established as an alternative monitoring pollutant.
294
-------
For PSES and PSNS, the toxic metals which intefere with, pass
through or prevent sludge utilization for food crops must be
removed before discharge to the POTW. PSES and PSNS includes
hexavalent chromium reduction to render the chromium removable by
precipitation and sedimentation and cyanide removal to prevent
complexing of toxic metals that hinder further treatment. Toxic
metals are removed by pH adjustment and settling for PSES and
PSNS. Flow reduction measures (countercurrent rinses of
different effectiveness) for PSNS and NSPS are retained to
provide minimum mass discharge of toxic pollutants.
Industry Cost and Effluent Reduction of_ Treatment Options
PSES Options 0, 1, 2, amd 3 are parallel to BPT, and BAT Options
1, 2, and 3, respectively. Also, PSNS Options are parallel to
the NSPS Options. Estimates of capital and annual costs for BAT-
PSES option and NSPS-PSNS options were prepared for each
subcategory as an aid to choosing the best options. Results for
BAT-PSES are presented in Table X-5 and results for NSPS-PSNS are
presented in Table VII1-2.
PSES pollutant reduction benfits were derived from the normal
line benefits and the number of normal lines reported by indirect
dischargers. The pollutant reduction benefits for a normal line
were presented in Table X-2. Treatment performance for the
subcategory is presented in Table XII-3 (pages 299). All
pollutant parameter calculations were based on mean raw
wastewater concentrations for visited plants (Table V-8, page
50). The term "toxic organics" refers to toxic organics listed
in Table XII-2 (page 298).
Regulated Pollutant Parameters
The Agency reviewed the canmaking wastewater concentrations, the
BAT model treatment technology removals, and the POTW removals of
major toxic pollutants found in canmaking wastewaters to select
the pollutants for regulation. The pollutants to be regulated
are the same for the subcategory as were selected for BAT except
that TTO or the alternative monitoring pollutant, oil and grease
is added. Toxic metals and toxic organics are regulated to
prevent pass through. Conventionals are not regulated for
themselves because POTW remove these pollutant parameters.
Fluoride and phosphorus are non-conventional pollutant parameters
which pass through POTW.
PRETREATMENT STANDARDS
Mass based limitations are set forth below (Tables XI1-4 and XII-
5 pages 300 and 301). The mass based limitations are the only
method of designating pretreatment standards since the water use
295
-------
reductions at PSES and PSNS are major features of the treatment
and control system. Only mass-based limits will assure the
implementation of flow reduction and the consequent reduction of
the quantity of pollutants discharged. Therefore, to regulate
concentrations is not adequate.
The derivation of standards is explained in Section IX. The mean
water use at PSES is equal to the mean water use at BAT (57.43
1/1000 cans) and its derivation is presented in Section X. For
PSNS, the calculation is the same as NSPS. The mean water use at
PSNS which is equal to the mean water use at NSPS is 14.0
1/1000 cans.
DEMONSTRATION STATUS
Since the model treatment technologies for PSES and PSNS are the
same as BAT and NSPS, respectively, the demonstration status is
presented in Sections X and XI.
296
-------
TABLE XXX-1
POTW REMOVALS OP THE PRIORITY POLLUTANTS
FOUND IN CANM&KING WA8TEWATER
Pollutant
11 1,1,1-Trichloroethane
29 1,1-Dichloroethylene
44 Methylene Chloride
66 Bis (2-ethylhexyl) phthalate
67 Butyl-bensjyl phthalate
68 Di-n-butylphthalate
86 Toluene
119 Chromium
128 Zinc
Percent Removal by Secondary POTW
87
Not Available
58
62
59
48
90
65
65
NOTEs These data compiled from Fate of Priority Pollutants in Publicly Owned
Treatment Works. USEPA, EPA No. 440/1-80-301, October 1980; and
Determine National Removal Credits For Selected Pollutants for Publicly
Owned TreatmentWorks, EPA No. 440/82-008. SgptemhAr
297
-------
VABLE XII-2
TOXIC ORGANICS COMPRISING TTO
Pollutant
11 1,1,1-Trichloroethane
29 1,1-Dichloroethylene
44 Methylene Chloride
66 Bis (2-ethylhexyl) phthalate
67 Butyl-benzyl phthalate
68 Di-n-butylphthalate
86 Toluene
Mean Raw Waste Concentrations (ing/1)
TOTAL
0.093
0.022
l.!>5
0.022
0.464
0.016
2.728
298
-------
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TABLE XII-4
PRETREATMENT STANDARDS FOR EXISTING SOURCES
CANMAKING SUBCATEGORY
Pollutant or
Pollutant Property
PSES Effluent Limitations
Maximum for Maximum for
any one day monthly average
g (lbs)/l,000,000 cans manufactured
Cr
Zn
Al
F
P
TTO
O&G (for
alternate
monitoring)
24.10
76.34
261 .17
3415.30
958.58
18.36
2353.
(0.053)
(0.167)
(0.574)
(7.513)
(2.108)
(0.040)
(5.177)
9.75
32.14
106.76
1515.36
392.04
8.61
1
1148.0
(0.021 )
(0.070)
(0.234)
(3.333)
(0.862)
(0.009)
(2.526!)
300
-------
TABLE XI1-5
PRETREATMENT STANDARDS FOR NEW SOURCES
CANMAKING SUBCATEGORY
Pollutant or
Pollutant Property
PSNS
Maximum for Maximum for
any one day monthly average
q (lbs)/1,000,000 cans manufactured
Cr
Zn
Al
F
P
TTO
O&G (for
alternate
monitoring)
5.88
18.62
63.7
833.0
233.8
4.48
280.0
(0.013)
(0.041 )
(0.140)
(1 .833)
(0.514)
(0.010)
(0.616)
2.38
7.84
26.04
369.60
95.62
2. 10
168.0
(0.005)
(0.017)
(0.057)
(0.813)
(0.210)
(0.005)
(0.370)
301
-------
-------
SECTION XIII
BEST CONVENTIONAL POLLUTANT CONTROL TECHNOLOGY
In 1977, Congress amended the Clean Water Act (the Act) to
include section 304(b). This provision requires EPA to establish
best conventional pollutant control technology (BCT) effluent
limitations to be determined by an analysis of: the
reasonableness of the relationship between the costs of attaining
a reduction in effluents and the effluent reduction benefits
derived; and the comparison of the cost and level of reduction of
such pollutants from the discharge of publicly owned treatment
works to the cost and level of reduction of such pollutants from
a class or category of industrial sources.
BCT is not an additional effluent limitation for industrial
dischargers, but rather replaces "best available technology
economically achievable" (BAT) effluent limitations for the
control of conventional pollutants. Effluent limitations
representing BCT may not be less stringent than limitations
representing "best practicable control technology currently
available" (BPT).
Section 304(a) of the Act specifies that conventional pollutants
include, but are not limtied to, biochemical oxygen demanding
materials (BQD5_), total suspended solids (TSS), fecal coliform,
and pH. The Agency has also designated oil and grease as a
conventional pollutant (44 FR 44501, July 30, 1979).
In developing the methodology for the 1979 regulation, EPA was
guided both by the statutory language of Section 304(b) and by
Congress1 underlying objectives in establishing BCT. Congress
was concerned that requirements for the control of conventional
pollutants beyond BPT were unreasonably expensive in some cases.
Accordingly, Congress required that a special "cost
reasonableness comparison" be applied before establishing BCT
limitations at a level more stringent than BPT. The core of the
Agency's BCT methodology was a comparison of the costs of
removing additional mass of conventional pollutants for industry
with comparable costs of removal for an average-sized publicly
owned treatment works (POTW).
The BCT methodology was challenged in the U.S. Court of Appeals
for the Fourth Circuit. On July 28, 198T, the Court issued its
decision, upholding the methodology EPA had developed for the
POTW cost-comparison test. American Paper Institute v. EPA, 660
F2d 954 (4th Cir., 1981). However, since EPA had recently
informed the court that significant statistical errors had been
303
-------
found in its calculation of the POTW test,
Agency to correct the errors.
held
the Court directed the
that the Act requires EPA to consider two
BCT methodology; an
The Court also
"reasonableness" tests as part of the
industry cost-effectiveness test and a POTW cost comparison test.
Because EPA had only developed the latter test, the Court
remanded the regulations and ordered EPA to develop and implement
an industry cost-effectiveness test that compares the industry's
costs of attaining a reduction in effluents with the effluent
reduction benefits derived.
In response to the court remand, EPA has developed an industry
cost-effectiveness test and corrected the. statistical errors in
its prior calculation of the POTW test.: EPA has generally
reevaluated the BCT methodology in response to a March 15, 1981
directive from the Presidential Task Force on Regulatory Relief
and comments by the Council on Wage and Price Stability. Based
on this review, EPA has determined that with the exception of one
minor change the POTW cost-comparison methodology promulgated in
1979 and upheld by the Court of Appeals |is still the preferred
approach. This new and revised BCT methodology was proposed
October 29, 1982 (49 FR 49176).
The methodology as proposed consists of ;two parts: a POTW test
and an industry cost-effectiveness test. The POTW test is passed
if the incremental cost per pound of conventional pollutant
removed in going from BPT to BCT is less than $.27 per pound in
1976 dollars. This figure is indexed to other years to account
for inflation and is $0.36 in 1981 dollars. The industry test is
passed if this same incremental cost per pound is less than 143
percent of the incremental cost per pound associated with
achieving BPT. Both tests must be passed for a BCT limitation
more stringent than BPT to be established.
The POTW Cost Test :
To make the POTW cost test it is necessary to calculate the
annual incremental cost to remove a mass unit of conventional
pollutants beyond BPT. This incremental cost is calculated as:
[(Candidate BCT annual cost) - (BPT annual costs)] t
[(Candidate BCT conventional pollutants removed) - (BPT
conventional pollutants removed)]
For the canmaking subcategory the incremental cost of removing
conventional pollutants by a BCT equivalent to BAT above BPT is:
420,000 - 451,900
(7,175,056 - 7,164,628) x 2.2
= (-) $1.39/lb
304
-------
The negative cost per pound removed is caused by the lower cost
of end-of-pipe treatment at BCT. The reduced wastewater volume
to be treated at BCT causes this reduced cost. When this cost is
<*viou.ly
The Industry Cost Test
This cost-effectiveness test compares the costs to industry and
S? eTh-«ent reducti?n benefits achieved in going from BPT to
BCT. This comparison is accomplished by relating the ratio of
£™ SS i. P»™ U?ifc m?ss of conventional pollutant removed going
from BPT to BCT to the cost per unit mass of conventional
pollutant removed by BPT to the benchmark ratio of 1.43. This
ratio is calculated as:
Total annual cost/pound removed (BPT to BCT)
Total annual cost/pound removed (pre BPT to BPT)
For the canmaking subcategory the BCT cost ratio is:
$31.900 t (-) 22,900
$420,000 t 7,175,000 x 2.2
• <-> 1-39 = (-) 52.3
0.0266
The negative cost ratio is clearly less than the benchmark ratio
of 1.43 and the BCT passes the industry cost test.
BCT Effluent Limitations
BT? e^ihn^^0n°ent^tions attainafale through the application of
S In 52bl2 SIT ?^ th?hsame as f0^ BJT and *™ shown under L and
s in Table VII-23. The mass discharge limitations for the
conventional pollutants are calculated as the predict of the BAT
flow detailed in Section X and the appropriate concentration
value and are presented in Table XIII-1, page 306 <-«ntration
305
-------
TABLE XIII-1 I
BEST CONVENTIONAL TREATMENT EFFLUENT LIMITATIONS
CANMAKING SUBCATEGORY
Pollutant or
Pollutant Property
Maximum for
any one day
Maximum for
monthly average
g (lbs)/l,000,000 cans manufactured
O&G
TSS
pH
1148.0 (2.526) 668.8 (1.515)
2353.4 (.5.177) 1148.0 (2.526)
Within the range of 7.5 to 10 at all times
306
-------
SECTION XIV
ACKNOWLEDGEMENTS
This document has been prepared
Guidelines Division with assistance
other EPA offices and other persons
is intended to acknowledge the
persons who have contributed to the
by the staff of the Effluent
from technical contractors,
outside of EPA. This Section
contribution of the several
development of this report.
The initial effort on this project was carried out by Sverdrup &
Parcel and Associates under Contract No. 68-01-4408; Hamilton
Standard Division of United Technologies, under Contract No.
68-01-4668, assisted in some sampling and analysis.
The field sampling programs were conducted under the leadership
of Garry Aronberg of Sverdrup & Parcel assisted by Donald
Washington, Project Manager, Claudia O'Leary, Anthony Tawa,
Charles Amelotti, and Jeff Carlton. Hamilton Standard's effort
was managed by Daniel J. Lizdas and Robert Blaser and Richard
Kearns.
In preparation of this proposal document, the Agency has been
assisted by Versar Inc., under contract 68-01-6469. Under
specific direction from Agency personnel, Versar rechecked
calculations and tabulations, made technical and editorial
revisions to specific parts of sections and prepared camera ready
copy of tables and figures. Versar's effort was managed by Lee
McCandless and Pamela Hillis with contributions from Jean Moore,
and others. John Whitescarver, Robert Hardy, and Robert Smith of
Whitescarver Associates (a subcontractor) provided substantial
assistance in preparation of this manuscript.
Ellen Siegler of the Office of General Counsel provided legal
advice to the project. Josette Bailey is the economic project
officer for the project. Henry Kahn provided statistical
analysis and assistance for the project. Alexandra Tarnay
provided environmental evaluations and word processing was
provided by Pearl Smith, Carol Swann, and Glenda Nesby.
Technical direction and supervision of the project have been
provided by Ernst P. Hall. Technical project officer is Mary
Belefski. *
Finally, .appreciation is expressed to the Can Manufacturers
Institute (CMI), and the participating can manufacturing
companies for their assistance and technical advice.
307
-------
-------
SECTION XV
REFERENCES
"The Surface Treatment and Finishing of Aluminum and Its
Alloys" by S. Werrick, PhD, Metal Finishing Abstracts, Third
Edition, Robert Draper Ltd., Teddington, 1964.
Guidebook & Directory, Metal Finishing, 1974, 1975, 1977 and
1978. American Metals and Plastics Publications Inc., One
University Plaza Hackensack, New Jersey 90601.
The Science of Surface Coatings, edited by Dr. H. W.
Chatfield, 1962.
Metals Handbook, Volume 2 8th Edition, American Society for
Metals,"Metals Park, Ohio.
Journal of Metal Finishing; "Pretreatment for Water-Borne
Coatings" - April, 1977
"Guidelines for Wastewater Treatment" - September, 1977
"Guidelines for Wastewater Treatment" - October, 1977
"Technical Developments in 1977 for Organic (Paint)
Coatings, Processes and Equipment" - February, 1978
"Technical Developments in 1977, Inorganic (Metallic)
Finishes, Processes and Equipment" - February, 1978
"The Organic Corner" by Joseph Mazia, - April, 1978
"The Organic Corner" by Joseph Mazia, - May, 1978
"The Economical Use of Pretreatment Solutions" - May, 1978
"The Organic Corner" by Joseph Mazia, - June, 1978
"Selection of a Paint Pretreatment System, Part I" - June,
1978
"The Organic Corner," by Joseph Mazia - September, 1978
How Do Phosphate Coatings Reduce Wear on Movings Parts, W.
R. Cavanagh.
Kirk-Othmer Encyclopedia of_ Chemical Technology, Second
Edition, 1963, Interscience Publishers, New York.
Encyclopedia of Polymer Science and Technology, Second
Edition, 1963, Interscience Publishers, New York.
Conversation and written correspondence with the following
companies and individuals have been used to develop the data
base:
Parker Company:
309
-------
10,
11
Mr. Michael Quinn, Mr. Walter Cavanaugh, Mr. James Maurer,
Mr. John Scalise
Division of Oxy Metals Industries
P. 0. Box 201 '
Detroit, MI 45220
Amchem Corporation:
Lester Steinbrecker
Metals Research Division
Brookside Avenue
Ambler, PA 19002
Diamond Shamrock '
Metal Coatings Division
P. 0. Box 127 ;
Chardon, OH 44024
Wyandotte Chemical: .
Mr. Alexander W. Kennedy |
Mr. Gary Van Ve Streek
Wyandotte, MI
Handbook of Environmental Data on Organic Chemicals,
Verschueren, Karel, Van Nostrand Reinhold Co., New York
1977.
Handbook of Chemistry, Lange, Norbert,iAdolph, McGraw Hill,
New York 1973.
12. Dangerous Properties of Industrial Materials, Sax N. Irving,
Van Nostrand Reinhold Co. New York.
13. Environmental Control in the Organic and Petrochemical
Industries, Jones, H. R, Noyes Data Corp. 1971 .
14. Hazardous Chemicals Handling and Disposal, Howes, Robert and
Kent, Robert, Noyes Data Corp., Park Ridge, New Jersey 1970.
15. Industrial Pollution, Sax, N. Irving, Van Nostrand Reinhold
Co., New York 1974. "
16. "Treatability of 65 Chemicals - Part A - Biochemical
Oxidation of Organic Compounds", June' 24, 1977, Memorandum,
Murray P. Strier to Robert.B. Schaffer.
17. "Treatability of Chemicals - Part B - Adsorption of Organic
Compounds on Activated Carbon," December 8, 1977,
Memorandum, Murray P. Strier to Robert B. Schaffer.
310
-------
18
19
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21 ,
22,
23.
24.
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26.
27.
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29.
30.
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Their Estimated {30 day avg) Treated Effluents Concentration
- A Molecular Engineering Approach", June 1978, Memorandum,
Murray P. Strier to Robert B. Schaffer.
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McKee and Harold W. Wolf, 1963 The Resources Agency of
California, State Water Quality Control Board, Publication
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The Condensed Chemical Dictionary. Ninth Edition, Revised by
Gessner G. Hawley, 1977.
Wastewater Treatment Technology, James W. Patterson.
Unit Operations for Treatment of Hazardous Industrial
Wastes, Edited by D. J. Denyo, 1978.
"Development Document For Proposed Existing Source
Pretreatment Standards For The Electroplating Point Source
Category", February 1978, EPA440/1-78/085.
"Industrial Waste and Pretreatment in the Buffalo Municipal
System", EPA contract #R803005, Oklahoma, 1977.
"Pretreatment of Industrial Wastes", Seminar Handout,
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U.S.
31
"Sources of Metals in Municipal Sludge and Industrial
Pretreatment as a Control Option", ORD Task Force on
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as a Control Option, U.S., EPA 1977.
"Effects of Copper on Aerobic Biological Sewage Treatment",
Water Pollution Control Federation Journal, February 1963 p
227-241. ~~~'
Wastewater Engineering, 2nd edition, Metcalf and Eddy.
Chemical Technology, L.W. Codd, et. al., Barnes and Noble.
New York, 1972
"Factors Influencing the Condensation of 4-aminoantipyrene
with derivatives of Hydroxybenzene - II. Influence of
Hydronium Ion Concentration on Absorbtivity," Samuel D.
Faust and Edward W. Mikulewicz, Water Research, 1967,
Pergannon Press, Great Britain
"Factors Influencing the Condensation of 4-aminoantipyrene
with derivatives of Hydroxylbenzene - I. a Critique," Samuel
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Scott, Murray C., "SulfexT« - A New Process Technology for
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1977 Purdue Industrial Waste Conference, May 10, 11, and 12,
1977.
"SulfexT. Heavy Metals Waste Treatment Process," Technical
Bulletin, Vol. XII, code 4413.2002 (Permutit®) July, 1977.
Scott, Murray C., "Treatment of Plating Effluent by Sulfide
Process," Products Finishing, August, 1978.
Lonouette, Kenneth H., "Heavy MetalsRemoval,"
Engineering, October 17, pp. 73-80. ;
Chemical
Curry, Nolan A., "Philosophy and Methodology of Metallic
Waste Treatment," 27th Industrial Waste Conference.
Patterson, James W., Allen, Herbert E.'and Scala, John J.,
"Carbonate Precipitation for Heavy; Metals Pollutants,"
Journal of Water Pollution Control Federation, December,
1977 pp. 2397-2410.
Bellack, Ervin, "Arsenic Removal from Potable Water,"
Journal American Water Works Association, July, 1971.
Robinson, A. K. "Sulfide -vs- Hydroxide Precipitation of
Heavy Metals from Industrial Wastewater," Presented at
EPA/AES First Annual Conference on Advanced Pollution
Control for the Metal Finishing Industry, January 17-19,
1978. ;
Sorg, Thomas J., "Treatment Technology;to meet the Interim
Primary Drinking Water regulations for Inorganics," Journal
American Water Works Association, February, 1978, pp. 105-
112.
Strier, Murray P., "Suggestions for SettingPretreatment
Limits for Heavy Metals and Further Studies of POTW's
memorandum to Carl J. Schafer, Office of Quality Review,
U.S. E.P.A., April 21, 1977.
Rohrer, Kenneth L., "Chemical Precipitants for Lead Bearing
Wastewaters," Industrial Water Engineering, June/July, 1975.
Jenkins, S. H., Keight, D.G. and Humphreys, R.E., "The
Solubilities of Heavy Metal Hydroxides in Water, Sewage and
Sewage Sludge-I. The Solubilities of Some Metal
312
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50,
51
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53
54
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Pollution, Vol. 8, 1964,pp. 537-556.
Bhattacharyya, 0., Jumawan, Jr., A.B., and Grieves, R.B.,
"Separation of Toxic Heavy Metals by Sulfide Precipitation/1
Separation Science and Technology. 14(5), 1979, pp. 441-452.
Patterson, James W., "Carbonate Precipitation Treatment for
Cadmium and Lead," presented at WWEMA Industrial Pollutant
Conference, April 13, 1978.
"An Investigation of Techniques for Removal of Cyanide from
Electroplating Wastes," Battelle Columbus Laboratories,
Industrial Pollution Control Section, November, 1971.
Patterson, James W. and Minear, Roger A., "Wastewater
Treatment Technology," 2nd edition (State of Illinois,
Institute for*Environmental Quality) January, 1973.
Chamberlin, N.S. and Snyder/ Jr., H.B., "Technology of
Treating Plating Waste," 10th Industrial Waste Conference.
Hayes, Thomas D. and Theis, Thomas L., "The Distribution of
Heavy Metals in Anaerobic Digestion," Journal of Water
Pollution Control Federation. January, 1978. pp. 61-72".
Chen, K.Y., Young, C.S., Jan, T.K. and Rohatgi, N., "Trace
Metals in Wastewater Effluent," Journal of Water Pollution
Control Federation. Vol. 46, No. 12, December, 1974^ppT
2663-2675. vv
Neufeld, Ronald D., Gutierrez, Jorge and Novak, Richard A.,
A Kinetic Model and Equilibrium Relationship for Metal
Accumulation," Journal of Water Pollution Control
Federation. March, 1977, pp. 489-498.
Stover, R.C., Sommers, L.E. and Silviera, D.J., "Evaluation
of Metals in Wastewater Sludge," Journal of Water Pollution
Control Federation. Vol. 48, No. 9, September, 1976"; ppT
2165-2175.
Neufeld, Howard D. and Hermann, Edward R., "Heavy Metal
Removal by Activated Sludge," Journal of Water Pollution
Control Federation. Vol. 47, No. 2, February^ 197I5T ppT
310-329. **
Schroder, Henry A. and Mitchener, Marian, "Toxic Effects of
Trace Elements on the Reproduction of Mice and Rats,"
Archives of Environmental Health, Vol. 23, August, 1971, pp.
102—106.
313
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55,
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57
58
59,
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(Plenum Press, New York, N.Y.), 1978.
Mammals"
Poison, C.J. and Tattergall, R.N.,
(J.B. Lipinocott Cbmpany), 1976.
"Clinical Toxicology,"
Hall, Ernst P. and Barnes, Devereaux, "Treatment of
Electroplating Rinse Waters and ;Effluent Solutions,"
presented to the American Institute of; Chemical Engineers,
Miami Beach, Fl., November 12, 1978. ;
Mytelka, Alan I., Czachor, Joseph S., ;Guggino, William B.
and Golub, Howard, "Heavy Metals in Wastewater and Treatment
Plant Effluents," Journal of Water Pollution control
Federation, Vol. 45, No. 9, September,;1973, pp. 1859-1884.
Davis, III, James A., and Jacknow, Joel, "Heavy Metals in
Wastewater in Three Urban Areas, "Journal of Water Pollution
Control Federation^ September, 1975, 2P_._ 2292-2297.
Klein, Larry A., Lang, Martin, Nash, Norman and Kirschner,
Seymour L., "Sources of Metals in New Vork City Wastewater,"
Journal of Water Pollution Control Federation, Vol. 46, No.
12, December, 1974, pp. 2653-2662. ;
Brown, H.G., Hensley, C.P., McKinney, G.L. and Robinson,
J.L., "Efficiency of Heavy Metals ;Removal in Municipal
Sewage Treatment Plants," Environmental Letters, 5 (2),
1973, pp. 103-114.
Ghosh, Mriganka M. and Zugger, Paul D.L "Toxic Effects of
Mercury on the Activated Sludge Process," Journal of Water
Pollution Control Federation, Vol. 45,:No. 3, March, 1973,
pp. 424-433.
Mowat, Anne, "Measurement of Metal Toxicity by Biochemical
Oxygen Demand," Journal of Water Pollution Control
Federation, Vol. 48, No. 5, May, 1976, pp. 853-866.
Oliver, Barry G. and Cosgrove, Ernest G., "The Efficiency of
Heavy Metal Removal by a Conventional Activated Sludge
Treatment Plant," Water Research, Vo. 8, 1074, pp. 869-874.
"Ambient Water Quality Criteria for Chlorinated Ethanes",
PB81-117400, Criteria and Standards Division, Office of
Water Regulations and Standards, U.S. EPA.
"Ambient Water Quality Criteria for Chloroalkylethers,"
PB81-117418, Criteria and Standards Division, Office of
Water Regulations and Standards, U.S. EPA.
314
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67. "Ambient Water Quality Criteria for Dichloroethylenes,"
PB81-117525, Criteria and Standards Division, Office of
Water Regulations and Standards, U.S. EPA.
68. "Ambient Water Quality Criteria for Halomethanes," PB81-
117624, Criteria and Standards Division, Office of Water
Regulations and Standards, U.S. EPA.
69. "Ambient Water Quality Criteria for Phthalate Esters,"
PB81-117780 Criteria and Standards Division, Office of Water
Regulations and Standards, U.S. EPA.
70. "Ambient Water Quality Criteria for Toluene", PB81-117855,
Criteria and Standards Division, Office of Water Regulations
and Standards, U.S. EPA.
71. "Ambient Water Quality Criteria for Arsenic," PB81-117327,
Criteria and Standards Division, Office of Water Regulations
and Standards, U.S. EPA.
72. "Ambient Water Quality Criteria for Cadmium," PB81-117368,
Criteria and Standards Division, Office of Water Regulations
and Standards, U.S. EPA.
73. "Ambient Water Quality Criteria for Chromium," PB81-117467,
Criteria and Standards Division, Office of Water Regulations
and Standards, U.S. EPA.
74. "Ambient Water Quality Criteria for Copper," PB81-117475,
Criteria and Standards Division, Office of Water Regulations
and Standards, U.S. EPA.
75. "Ambient Water Quality Criteria for Cyanide," PBS 1-117483,
Criteria and Standards Division, Office of Water Regulations
and Standards, U.S. EPA.
76. "Ambient Water Quality Criteria for Lead," PB81-117681,
Criteria and Standards Division, Office of Water Regulations
and Standards, U.S. EPA.
77. "Ambient Water Quality Criteria for Mercury," Criteria and
Standards Division, Office of Water Regulations and
Standards, U.S. EPA
78. "Ambient Water Quality Criteria for Nickel," PB81-117715,
Criteria and Standards Division, Office of Water Regulations
and Standards U.S. EPA.
315
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79. "Ambient Water Quality Criteria for Zinc," PB81-117897,
Criteria and Standards Division, Office of Water Regulations
and Standards, U.S. EPA.
80. Treatability Manual, U.S. Environmental Protection Agency,
Office of Research and Development, Washington, D.C. July
1980, EPA - 600/8-80-042a,b,c,d,e.
81. Electroplating Engineering Handbook, edited by H. Kenneth
Graham, Van Nostrand Reinhold Company, New York, 1971.
82. Can Manufacturers Institute, "Directory - Cans Manufactured
for Sale," 1982. : ~
83
84,
85,
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88
89
90.
91
92,
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Can Manufacturers Institute, "Metal Can Shipments Report,"
1980. ;
Can Manufacturers Institute, "Metal Can Shipments Report,"
1981.
Church, Fred L. "Can Equipment Sales Ride Wave of Plant
Expansions." Modern Metals, April, 1978, pp. 32-40.
"Computer Control Increases Productivity, Cuts Downtime at
Canmaking plant." The BREWERS DIGEST, July, 1975, pp. 36-38.
"Deep-drawn Oval Fish Cans." Iron and Steel Engineer, July,
1974, p. 55. "
"Design Data." Machine Design, February 14, 1974, pp.
150.
"Experts Tell What's New in Forming."
April 1, 1975, pp. 45-46.
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August, 1976, p. 14.
148-
American Machinist,
The BREWERS DIGEST,
Knepp, J. E. and L. B. Sargent, Jr. "Lubricants for Drawing
and Ironing Aluminum Alloy Beverage Cans." Lubrication
Engineering, April, 1978, pp. 196-201.
Kuhner, John G. "Pearl's Total Aluminum Can Program." The
BREWERS DIGEST, January, 1976, pp. 45-50.
"Lone Star Adopts Ultra-Lightweight Seamless SteelCan." The
BREWERS DIGEST, May, 1975, pp. 46-47. ! ~
Lubrication, published by Texaco, Inc. |N.Y., N.Y.. Volume 61,
April-June 1975, pp. 17-18. ;
316
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95. Lund, H., editor, Industrial Pollution Control Handbook,
McGraw-Hill 1971, pp. 612-613.
96. Church, Fred L., "Aluminum's Next Target: Cost-Competative
Food Cans," Modern Metals, Vol. 32, May 1976, pp. 81-87.
97. American Society for Metals, Metals Handbook, 8th Edition,
1969, Vol. 4, "Forming."
98. Maeder, Edward G. "The D&I Can: How & Why it Does More With
Less Metal." Modern Metals, August, 1975, pp. 55-62.
99. Mastrovich, J. D. "Aluminum Can Manufacture." Lubrication.
Vol. 61, April-June, 1975,pp. 17-36.
100. Mathis, Jerry N. "We See . a future For Steel Two-Piece
Cans.." advertisement, The BREWERS DIGEST, January, 1977,
. pp. 13,.
101. Mungovan, James. "New Can Plant on Target: 2 Million
Containers a Day." Modern Metals, Vol. 33, July, 1977, pp.
27-36.
102. "Olympia's Plans for Lone Star." The BREWERS DIGEST, July,
1977, pp. 20-23.
103. "Schmidt's Christens New $7 Million Packaging Facility."
Food Engineering. October, 1977, pp. 47-49.
104. Spruance, Frank Palin, Jr. U.S. Patent 2,438,877, September
6, 1945.
105. Sullivcin, Barry C. "Lone Star Turns It Around With
Returnables, Youth Emphasis." The BREWERS DIGEST, May, 1976,
pp. 28-30.
317
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SECTION XVI
GLOSSARY
Accumulation - In reference to biological systems, is the
concentration which collects in a tissue or organism which-
does not disappear with time.
Acidity - The quantitative capacity of aqueous media to react
with hydroxyl ions.
Acidulated Rinse - See Sealing Rinse
Act - The Federal Water Pollution Control Act (P.L. 92-500)
amended by the Clean Water Act of 1977 (P.L. 95-217).
as
Activator - A material that enhances the chemical or physical
change when treating the metal surface.
Adsorption - The adhesion of an extremely thin layer of molecules
of a gas or liquid to the surface of the solid or liquid
with which they are in contact.
Agency - The U.S. Environmental Protection Agency.
Algicide - Chemical used in the control of phytoplankton (algae)
in water.
Alkalinity - The quantitative capacity of aqueous media to react
with hydrogen ions.
Aluminum Basis Material - Means aluminum and aluminum alloys
which are processed in canmaking.
Anionic Surfactant - An ionic type of surface-active substance
that has been widely used in cleaning products. The hydro-
philic group of these surfactants carries a negative charge
in the washing solution.
Anodizing - An electrochemical process of controlled aluminum
oxidation producing a hard, transparent oxide up to several
mils in thickness.
Area Processed - See Processed Area.
Backwashing - The process of cleaning a filter or ion exchange
column by reversing the flow of water.
319
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Baffles - Deflector vanes, guides, grids, gratings, or similar
devices constructed or placed in flowing water or sewage to
(1) check or effect a more uniform distribution of
velocities; (2) absorb energy; (3) divert, guide, or agitate
the liquids; or (4) check eddy currents.
Basis Material or
Metal - That substance of which the cans are
the
made and that receives the coating
preparation of coating.
and
treatments in
BAT - The best available technology economically achievable under
Section 304(b)(2)(B) of the Act
BCT - The best conventional pollutant control technology, under
Section 304(b)(4) of the Act
BDT - The best available demonstrated control technology
processes, operating methods, or other alternatives,
including where practicable, a standard permitting no
discharge of pollutants under Section 306(a)(l) of the Act.
Biochemical Oxygen Demand (BOD) - (1) The quantity of oxygen
required -for the biological and chemical oxidation of
waterborne substances under conditions of test used in the
biochemical oxidation of organic matter in a specified time,
at a specified temperature, and under specified conditions.
(2) Standard test used in assessing wastewater strength.
Biodegradable - The part of organic matteri which can be oxidized
by bioprocesses, e.g., biodegradable detergents, food
wastes, animal manure, etc. ;
Biological Wastewater Treatment - Forms of wastewater treatment
in which bacteria or biochemical action is intensified to
stabilize, oxidize, and nitrify the unstable organic matter
present.
BMP - Best management practices under Section 304(e) of the Act
Bodymaker - The machine for drawing, or drawing and ironing
two-piece can bodies.
BPT - The best practicable control technology currently available
under Section 304(b)(l) of the Act. ;
Buffer - Any of certain combinations pf chemicals used to
stabilize the pH values or alkalinities of solutions.
Cake - The material resulting from drying or dewatering sludge.
320
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Calibration - The determination, checking, or rectifying of the
graduation of any instrument giving quantitative
measurements.
Canmaking - The manufacturing operations used to produce various
shaped metal containers subsequently used for storing foods,
beverages, and other products.
Captive Operation - A manufacturing operation carried out in a
facility to support other manufacturing, fabrication, or
assembly operations.
Carcinogenic - Referring to the ability of a substance to produce
or incite cancer.
Central Treatment Facility - Treatment plant which co-treats
process wastewaters from more than one manufacturing
operation or cotreats process wastewaters with noncontact
cooling water, or with non-process wastewaters,
miscellaneous runoff, etc.).
Chemical Coagulation
The destabilization and initial
aggregation of colloidal and finely divided suspended matter
by the addition of a floe-forming chemical. The amount of
oxygen expressed in parts per million consumed under
specific conditions in the oxidation of the organic and
oxidizable inorganic matter contained in an industrial
wastewater corrected for the influence of chlorides.
Chemical Oxygen Demand (COD) - (1) A test based on the fact that
all organic compounds, with few exceptions, can be oxidized
to carbon dioxide and water by the action of strong
oxidizing agents under acid conditions. Organic matter is
converted to carbon dioxide and water regardless of the
biological assimilability of the substances. One of the
chief limitations is its ability to differentiate between
biologically oxidizable and biologically inert organic
matter. The major advantage of this test is the short time
required for evaluation (2 hrs). (2) The amount of oxygen
required for the chemical oxidation of organics in a liquid.
Chemical Oxidation - A wastewater treatment in which a pollutant
is oxidized.
Chemical Precipitation - Precipitation induced by addition of
chemicals.
Chlorination - The application of chlorine to water or wastewater
generally for the purpose of disinfection, but frequently
for accomplishing other biological or chemical results.
321
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Chromate Conversion Coating - A process whereby an aqueous
acidified chromate solution consisting mostly of chromic
acid and water soluble salts of chromic acid together with
various catalysts or activators (such as cyanide) is applied
to the coil. |
Chromium Process Controller - A device; used to maintain a
desirable and constant hexavalent chromium concentration.
Clarification - The removal of suspended solids from wastewater.
Cleaning - The process of removing contaminants from the surface
of a coil. '
Clean Water Act - The Federal Water Pollution Control Act
Amendments of 1972 (33 U.S.C. 1251 et seq.), as amended by
the Clean Water Act of 1977 (Public Law 95-217)
Colloids - A finely divided dispersion of one material called the
"dispersed phase" (solid) in another material which is
called the "dispersion medium" :(liquid). Normally
negatively charged. '•
Compatible Pollutant - A specific substance in a waste stream
which alone can create a potential pollution problem, yet is
used to the advantage of a certain treatmentprocess when
combined with other wastes. ;
Composite - A combination of individual samples of water or
wastewater taken at selected intervals and streams and mixed
in proportion to flow or time to minimize the effect of the
variability of an individual sample. i
Concentration Factor - Refers to the biological concentration
factor which is the ratio of the concentration within the
tissue or organism to the concentration outside the tissue
or organism.
Concentration, Hydrogen Ion - The weight of hydrogen ions in
grams per liter of solution. Commonly expressed as the pH
value that represents the logarithm of the reciprocal of the
hydrogen ion concentration.
Contamination - A general term signifying the introduction of
microorganisms, chemicals, wastes or sewage which renders
the material or solution unfit for its,intended use.
Contractor Removal - The disposal of oils, spent
sludge by means of a scavenger service.
solutions, or
322
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Conversion Coating - The process of applying a chromate,
phosphate, complex oxide or other similar protective coating
to a metal surface.
Cooling Tower - A device used to cool water used in the manufac-
turing processes before returning the water for reuse.
Cupping - Process whereby a flat sheet of metal is formed into a
cup by means of a die punch operation (a cupper).
Degreasing - The process of removing grease and oil from the sur-
face of the material.
Deionized Water - Water from which dissolved impurities (in the
form of free ions) have been removed to reduce its
electrical conducting properties and the potential for
contamination of the manufacturing process.
Dewaterinq - A process whereby water is removed from sludge.
Die - Part on a machine that punches shaped holes in, cuts, or
forms sheet metal, cardboard, or other stock.
Direct Discharger - A facility which discharges or may discharge
pollutants into waters of the United States.
Dissolved Solids - Theoretically the anhydrous residues of the
dissolved constituents i^n water. Actually the term is
defined by the method used in determination. In water and
wastewater treatment, the Standard Methods tests are used.
Dragout - The solution that adheres to the can
past the edge of the treatment tank.
and is carried
Drawing - A process where a sheet of metal is pushed into a mold
or die by a solid piece of metal (punch), thus flowing over
the punch to form a cup.
Draw-redraw - Process in which a second drawing step follows an
initial drawing to form a deeper cup.
Drying Beds — Areas for dewatering of sludge by evaporation and
seepage.
Dump - The discharge of process waters not usually discharged for
maintenance, depletion of chemicals, etc.
Effluent - The wastewaters which are discharged to surface
waters, directly or indirectly.
323
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Emergency Procedures - The various special procedures necessary
to protect the environment from wastewater.treatment plant
failures due to power outages, chemical spills, equipment
failures, major storms and floods, etc.
Emulsion Breaking - Decreasing the stability of dispersion of one
liquid in another.
End-of-Pipe Treatment - The reduction and/or removal of
pollutants by chemical treatment just prior to actual
discharge.
Equalization - The process whereby waste streams from different
sources varying in pH, chemical consitMtents, and flow rates
are collected in a common container. The effluent stream
from this equalization tank will have a fairly constant flow
and pH level, and will contain a homogeneous chemical
mixture.
[
Extrusion - Process of shaping by forcing basis material through
a die.
Feeder, Chemical - A mechanical device for applying chemicals to
water and sewage at a rate controlled manually or auto-
matically by the rate of flow. ;
i
Flanging - The forming of a protruding rim or collar on the end
of the can body to allow attachment of; the end.
Float Gauge - A device for measuring the elevation of the surface
of a liquid, the actuating element of which is a buoyant
float that rests on the surface of the liquid and rises or
falls with it. The elevation of the surface is measured by
a chain or tape attached to the float.
Floe - A very fine, fluffy mass formed by the aggregation of fine
suspended particles. ; .
Flocculator - An apparatus designed for the formation of floe in
water or sewage.
Flocculation - In water and wastewater treatment, the agglomera-
tion of colloidal and finely divided suspended matter after
coagulation by gentle stirring by either mechanical or
hydraulic means. In biological wastewater treatment where
coagulation is not used, agglomeration may be accomplished
biologically. : '
324
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Flow-Proportioned
Sample - A sampled stream whose pollutants are
proportion
apportioned to contributing streams in
flow rates of the contributing streams
to the
Grab Sample - A single sample of wastewater taken at neither set
time nor flow.
Grease - In wastewater, a group of substances including fats,
waxes, free fatty acids, calcium and magnesium soaps,
mineral oil, and certain other nonfatty materials. The type
of solvent and method used for extraction should be stated
for quantification.
Hardness - A characteristic of water, imparted by salts of cal-
cium, magnesium, and iron such as bicarbonates, carbonates,
sulfates, chlorides, and nitrates that cause curdling of
soap, deposition of scale in boilers, damage in some
industrial processes, and sometimes objectionable taste. It
may be determined by a standard laboratory procedure or
computed from the amounts of calcium and magnesium as well
as iron, aluminum, manganese, barium, strontium, and zinc,
and is expressed as equivalent calcium carbonate.
Heavy Metals - A general name given to the ions of metallic ele-
ments such as copper, zinc, chromium, and nickel.
Holding Tank - A reservoir to contain preparation materials so as
to be ready for immediate service.
Indirect Discharger - A facility which introduces or may
introduce pollutants into a publicly owned treatment works.
Industrial Wastes - The wastes used directly or indirectly in
industrial processes as distinct from domestic or sanitary
wastes.
In-Process Control Technology - The regulation and conservation
of chemicals and rinse water throughout the operations as
opposed to end-of-pipe treatment.
Ion Exchange - A reversible chemical reaction between a solid
(ion exchanger) and a fluid (usually a water solution) by
means of which ions may be interchanged from one substance
to another. The superficial physical structure of the solid
is not affected.
Ironing - A process where the side walls of a drawn cup are
pressed against the punch, making them thinner and longer,
and creating a deeper can of larger volume.
325
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Lagoon - A man-made pond or lake for holding wastewater for the
removal of suspended solids. Lagoons are also used as
retention ponds. '•
Landfill - An approved site for dumping of waste solids.
Lime - Any of a family of chemicals consisting essentially of
calcium hydroxide made from limestone (calcite).
Limiting Orifice - A device that limits flow by constriction to a
relatively small area. A constant flow can be obtained over
a wide range of upstream pressures. ;
Lubricant - A substance such as oil, grease, etc., used for
lessening friction.
Make-Up Water - Total amount of water used by process.
Mandrel - A shaft or bar the end of which is inserted into a
workpiece to hold it during machining.!
Milligrams Per Liter (mq/1) - This is a weight per volume desig-
nation used in water and wastewater analysis.
Mutaqenic - Referring to the ability of a;substance to increase
the frequency or extent of mutation.
National Pollutant Discharge Elimination System (NPDES) - The
federal mechanism for regulating discharge to surface waters
by means of permits. A National Pollutant Discharge
Elimination System permit issued under Section 402 of the
Act.
Necking - Forming of a narrower portion at the top of a can body.
i
Neutralization - Chemical addition of either acid or base to a
solution such that the pH is adjusted to approximately 7.
Noncontact Cooling Water - Water used for cooling which does not
come into direct contact with any raw material, intermediate
product, waste product or finished product.
Nonionic Surfactant - A general family of surfactants so called
because in solution the entire molecule remains associated.
Nonionic molecules orient themselves at surfaces not by an
electrical charge, but through separate grease-solubilizing
and water-soluble groups within the molecule.
NPDES - National Pollutant Discharge Elimination System.
326
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NSPS - New source performance standards under Section 306 of the
Act.
Orthophosphate - An acid or salt containing phosphorus as P0£.
Outfall - The point or location where sewage or drainage
discharges from a sewer, drain, or conduit.
Paint - A liquid composition of plastic resins, pigments and sol-
vents which is converted to a solid film after application
as a thin layer by a drying or heat curing process step.
Painted Area - (Expressed in terms of square meters). The
dimensional area that receives an enamel, plastic, vinyl, or
laminated coating.
Palletizing - The placing of finished cans into a portable
storage container prior to their being filled.
Parshall Flume - A calibrated device developed by Parshall for
measuring the flow of liquid in an open conduit. It
consists essentially .of a contracting length, a throat, and
an expanding length. At the throat is a sill over which the
flow passes as critical depth. The upper and lower heads
are each measured at a definite distance from the sill. The
lower head cannot be measured unless the sill is submerged
more than about 67 percent.
PJJ - The negative of the logarithm of the hydrogen ion concen-
tration.
pH Adjust - A means of maintaining the optimum pH through the use
of chemical additives.
Phosphate Coating - In canmaking the process of forming a
conversion coat on aluminum by spraying a hot solution of
phosphate, containing titanium or zirconium.
Pollutant - The term "pollutant" means dredged spoil, solid
wastes, incinerator residue, sewage, garbage, sewage sludge,
munitions, chemical wastes, biological materials,
radioactive materials, heat, wrecked or discarded equipment,
rock, sand, cellar dirt and industrial, municipal and
agricultural waste discharged into water.
Pollutant
Parameters - The characteristics or constituents of a
alter the chemical, physical,
waste stream which may alter the chemical,
biological, radiological integrity of water.
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Polyelectrolytes - Used as a coagulant: or a coagulant aid in
water and wastewater treatment. They are synthetic or
natural polymers containing ionic constituents. They may be
cationic, anionic, or nonionic.
POTW - Publicly Owned Treatment Works. j
Prechlorination - (1) Chlorination of water prior to filtration.
(2) Chlorination of sewage prior to treatment.
Precipitate - The solid particles formed from a liquid solution
due to the saturation of the solid in the solution having
been achieved.
Precipitation, Chemical - Precipitation induced by
chemicals. ;
addition of
Pretreatment - Any wastewater treatment Iprocess used to reduce
pollution load partially before the wastewater is introduced
into a main sewer system or delivered j'to a treatment plant
for substantial reduction of the pollutionload.
Printing - The technique of rolling a design on a painted strip.
Priority Pollutant - The 129 specific pollutants established by
the EPA from the 65 pollutants and classes of pollutants as
outlined in the consent decree of June 8, 1976.
Process Water - Any water which during manufacturing or
processing, comes into direct contact:with or results from
the production or use of any raw materials, intermediate
product, finished product, by-product, or waste product.
PSES - Pretreatment standards for existing sources of indirect
discharges under Section 307(b) of the Act.
Publicly Owned Treatment Works (POTW) - A central treatment works
serving a municipality.
Raw Wastewater - Plant water prior to any treatment or use.
RCRA - Resource Conservation and Recovery Act (PL 94-580) of
1976, Amendments to Solid Waste Disposal Act.
Recirculated Water - Process water which is returned as process
water in the same or in a different process step.
Rectangular Weir - A weir having a notch!that is rectangular in
shape. i
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Recycled Water - Process water which
process after treatment.
is returned to the same
Reduction Practices - (1) Wastewater reduction practices can mean
the reduction of water use to lower the volume of wastewater
requiring treatment and (2) the use of chemical reduction to
lower the valance state of a specific wastewater pollutant.
Reduction - The opposite of oxidation treatment wherein a
reductant (chemical) is used to lower the valence state of a
pollutant to a less toxic form e.g., the use of S02_ to
"reduce" hexavalent chromium to trivalent chromium in an
acidic solution.
Retention Time - The retention time is equal to the volume of a
tank divided by the flow rate of liquids into or out of the
tank.
Rinse - Water for removal of dragout by dipping, spraying,
fogging, etc.
Sanitary Sewer - A sewer that carries water or wastewater from
residences, commercial buildings, industrial plants, and
institutions together with minor quantities of ground,
storm, and surface waters that are not admitted
intentionally.
Sealing Rinse - The final rinse in the conversion coating process
which contains a slight concentration of chromic acid.
Seaming - In canmaking the joining of two edges of a rolled metal
blank to form a cylinder and the joining of ends or tops to
can bodies.
Seamless - In canmaking refers to can bodies formed without side
seams. Cans are formed by drawing of flat sheet metal into
a cupped shape.
Secondary Waste Water Treatment - The treatment of wastewater by
biological methods after primary treatment by sedimentation.
Sedimentation - Settling by gravity of matter suspended in water.
Settleable Solids - (1) That matter in wastewater which will not
stay in suspension during a preselected settling period,
such as one hour, but either settles to the bottom or floats
to the top. (2) In the Imhoff cone test, the volume of mat-
ter that settles to the bottom of the cone in one hour.
Skimmer - A device to remove floating matter from wastewaters.
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Sludge - The solids (and accompanying water and organic matter)
which are separated from sewage or industrial wastewater.
\" '"
Sludgje Dewatering - A process used to j increase the solids
concentration of sludge.
I - • .I." •"
Sludge Disposal - The final disposal of solid wastes.
Solvent - A liquid capable of dissolving or dispersing one or
more other substances. i
Spills - A chemical or material spill is an unintentional dis-
charge of more than 10 percent of the daily usage of a
regularly used substance. In the case of a rarely used (one
per year or less) chemical or substance, a spill is that
amount that would result in 10% added loading to the normal
air, water or solids waste loadings measured as the closest
equivalent pollutant. !
Stamping - Forming or cutting of can tops by the application of a
die. I
Suspended Solids - (1) Solids that either float on the surface
of, or are in suspension in water, wastewater, or other
liquids, and which are largely removable by laboratory
filtering. (2) The quantity of material removed from
wastewater in a laboratory test, as prescribed in "Standard
Methods for the Examination of Water and Waste Water" and
referred to as non-filterable residue.;
Teratogenic - Referring to the ability of a substance to form
developmental malformations and monstrosities,,
Three-piece cans - Cans formed by combining a cylindrical portion
and two ends. Usually, the sides are formed by wrapping a
metal around a mandrel and locking the seam.
Total Cyanide - The total content of cyanide including simple
and/or complex ions. In analytical terminology, total
cyanide is the sum of cyanide amenable to chlorination and
that which is not according to standard analytical methods.
Total Solids - The total amount of solids in a wastewater in
solution and suspension. !
Toxicity - Referring to the ability of a substance to cause in-
jury to an organism through chemical Activity.
Treatment Facility Effluent - Treated process
discharge.
wastewater before
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Trimming -
body.
Removal of excess metal from the top of a shaped can
Turbidity - (1) A condition in water or wastewater caused by the
presence of suspended matter, resulting in the scattering
and absorption of light rays. (2) A measure of fine
suspended matter in liquids. (3) An analytical quantity
usually reported in arbitrary turbidity units determined by
measurements of light diffraction.
Two-piece cans - Cans formed by drawing a flat metal plate into a
cup and attaching a top.
Viscosity - That property of a liquid paint or coating material
which describes its ability to resist flow or mixing. Paint
Viscosity is controlled by solvent additions and its control
is essential to effective roller-coater operation and
uniform dry films thickness.
Waste plate - Tin plate with defects too severe to repair. It is
used for making cans for products such as paint which will
not be adversely affected by the defects.
Water Balance - An accounting of all water entering and leaving a
unit process or operation in either a liquid or vapor form
or via raw material, intermediate product, finished product,
by-product, waste product, or via process leaks, so that the
difference in flow between all entering and leaving streams
is zero.
Water Use - The quantity of process water used in processing a
specified number of cans (expressed as 1/1,000 cans)
Weir - (1) A diversion dam. (2) A device that has a crest and
some containment of known geometric shape, such as a V,
trapezoid, or rectangle and is used to measure flow of
liquid. The liquid surface is exposed to the atmosphere.
Flow is related to upstream height of water above the crest,
to position of crest with respect to downstream water
surface, and to geometry of the weir opening. Criteria and
Standards Division, Office of Water Regulations and
Division, Office of Water Regulations and Standards, U.S.
EPA.
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