-------
Summary
Table VI-1 (page 175) summarizes the selection of non-
conventional and conventional pollutant parameters for
consideration for specific regulation by subcategory. Table VI-
2/ (page 176) presents the results of selection of priority
pollutant parameters for consideration for specific regulation
for the steel, galvanized, and aluminum subcategories,
respectively. The pollutants that were not detected (included by
ND) include some pollutants which were detected in screening
analysis of total raw wastewater, but which were not detected
during verification analysis of raw wastewater from process steps
within subcategories. "Environmentally Insignificant" includes
parameters found in only one plant, present only below an
environmentally significant level, or those that cannot be
attributed to the point source category because they are
generally found in plant equipment. "Not Treatable" means that
concentrations were lower than the level achievable with the
specific treatment methods considered in Section VII.
174
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TABLE VI-1
NONCONVENTIONAL AND CONVENTIONAL POLLUTANT
PARAMETERS SELECTED FOR CONSIDERATION FOR
SPECIFIC REGULATION IN THE COIL COATING CATEGORY
Pollutant
TSS
Subcategory
Parameter Steel Galvanized Aluminum
x x
X X
Aluminum x
Iron x
Manganese x x x
Phenols, Total x x x
Phosphorus x x x
Oil & Grease x x x
PL
x X x
175
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TABLE VI—2
PRIORITY POLLUTANT DISPOSITION
Pollutant
001 Acenaphthene
002 Acrolein
003 Acrylonitrile
004 Benzene
005 Benzidine
006 Carbon tetrachloride
(tetrachloromethane)
007 Chlorobenzene
008 1,2,4-trichloro-
benzene
009 Hexachlorobenzene
010 1,2-dichloroethane
011 1,1,1-trichloroethane
012 Hexachloroethane
013 1,1-dichloroethane
014 1,1, 2-trichloroethane
015 1,1,2,2-tetra-
chloroethane
016 Chloroethane
017 Bi$ (chloromethyl)
ether
018 Bis (2-chloroethyl)
ether
019 2-chloroethyl vinyl
ether (mixed)
020 2-chloronaphthalene
021 2,4,6-trichlorophenol
022 Parachlorometa cresol
023 Chloroform (trichloro-
methane)
024 2-chlorophenol
025 1,2-dichlorobenzene
026 1,3-dichlorobenzene
027 1,4-dichlorobenzene
028 3,3-dichlorobenzidine
029 1,1-dichloroethylene
030 1,2-trans-dichloro-
ethylene
031 2,4-dichlorophenol
032 1,2-dichloropropane
033 1,2-dichloropropylene
{1,3-dichloropropene)
176
Subcategory
Steel Galvanized Aluminum
ND ND ND
ND ND ND
ND ND ND
NQ NQ NQ
ND ND ND
ND ND ND
ND ND ND
ND ND ND
ND ND ND
ND ND ND
NT NT NT
ND ND ND
SU NQ ND
ND ND ND
ND ND ND
ND ND ND
ND ND ND
ND ND ND
ND ND ND
ND ND ND
ND ND ND
ND ND ND
ND ND ND
ND NQ ND
ND ND ND
ND ND ND
ND ND ND
ND ND ND
ND ND ND
ND NT ND
ND NT ND
ND ND ND
ND ND ND
ND ND ND
ND ND ND
-------
034
2,4-dimethylphenol
ND
ND
ND
035
2,4-dinitrotoluene
ND
ND
ND
036
2,6-dinitrotoluene
ND
ND
ND
037
1,2-diphenylhydrazine
ND
ND
ND
038
Ethylbenzene
NQ
NQ
NQ
039
Fluoranthene
RG
RG
NQ
040
4-chlorophenyl phenyl
ND
ND
ND
ether
041
4-bromophenyl phenyl
ND
ND
ND
ether
042
Bis(2-chloroisopropyl)
ND
ND
ND
ether
043
Bis(2-chloroethoxyl)
ND
ND
ND
methane
044
Methylene chloride
•ND
ND
ND
(di chloromethane)
045
Methyl chloride
ND
ND
ND
(dichloromethane)
046
Methyl bromide
ND
ND
ND
(bromomethane)
047
Bromoform (tribromo-
ND
ND
ND
methane)
048
Di ch1orobromomethane
ND
ND
ND
049
Trichlorofluoromethane
ND
ND
ND
050
Dichlorodifluoromethane
ND
ND
ND
051
Ch1orod i bromomethane
ND
NQ
ND
052
Hexachlorobutadiene
ND
ND
ND
053
Hexachloromyclopenta-
ND
ND
ND
diene
054
Isophorone
SU
SU
ND
055
Naphthalene
NT
NT
NQ
056
Nitrobenzene
ND
ND
ND
057
2-nitrophenol
ND
ND
ND
058
4-nitrophenol
ND
ND
ND
059
2,4-dinitrophenol
ND
ND
ND
060
4,6-dinitro-o-cresol
ND
ND
ND
061
N-nitrosodimethyl-
ND
ND
ND
amine
062
N-nitrosodiphey1-
ND
ND
ND
amine
063
N-nitrosodi-n-propyl
ND
ND
ND
amine
064
Pentachlorophenol
ND
ND
ND
065
Phenol
ND
ND
ND
066
Bis(2-ethylhexyl
RG
RG
RG
phthalate)
067
Butyl benzyl-
RG
RG
RG
phthalate
068
Di-N-Butyl Phthalate
RG
RG
RG
177
-------
069 Di-n-octyl phthalate SU RG RG
070 Diethyl, phthalate SU RG RG
071 Dimethyl phthalate NQ RG RG
072 1,2-benzanthracene RG RG NQ
(benzo(a)anthracene)
073 Benzo(a)pyrene (3,4- RG RG RG
benzopyrene)
074 3,4-Benzofluoranthene RG RG NQ
(benzo(b)fluoranthene)
075 11,12-benzofluoranthene RG RG NQ
(benzo(b)f1uoranthene)
076 Chrysene RG RG NQ
077 Acenaphthylene RG RG NQ
078 Anthracene RG RG NQ
079 1,12-benzoperylene RG RG NQ
(benzo(ghi)perylene)
080 Fluorene RG RG NQ
081 Phenanthrene RG RG NQ
082 1,2,5,6-dibenzanthracene RG RG NQ
dibenzo(h)anthracene
083 Indeno(1,2,3-cd) pyren RG RG NQ
(2,3-o-pheynylene
pyrene)
084 Pyrene RQ RQ NQ
085 Tetrachloroethylene NQ NQ NQ
086 Toluene ND ND ND
087 Trichloroethylene RG RG RG
088 Vinyl chloride ND ND ND
(chloroethylene)
089 Aldrin ND ND ND
090 Dieldrin ND ND ND
091 Chlordane (technical ND ND ND
mixture and
metabolites)
092 4,4-DDT ND ND ND
093 4,4-DDE (p,p-DDX) ND ND ND
094 4,4-DDD (p,p-TDE) ND ND ND
095 Alpha-endosulfan ND ND ND
096 Beta-endosulfan ND ND ND
097 Endosulfan sulfate ND ND ND
098 Endrin ND ND ND
099 Endrin aldehyde ND ND ND
100 Heptachlor ND ND ND
101 Heptachlor epoxide ND ND ND
(BHC hexachloro-
lioxctno)
102 Alpha-BHC ND ND ND
103 Beta-BHC ND ND ND
104 Gamma-BHC (lindane) ND ND ND
178
-------
105 Delta-BHG (PCB-poly- ND ND ND
chlorinated bi-
phenyls)
106 PCB-1232(Arochlor 1242), ND ND ND
107 PCB-1254(Arochlor 1254 ND ND ND
108 PCB-1221(Arochlor 1221) ND ND ND
109 PCB-1232(Arochlor 1232) ND ND ND
110 PCB-1248(Arochlor 1248) ND ND ND
111 PCB-1260(Arochlor 1260) ND ND ND
112 PCB-1016(Arochlor 1016) ND ND ND
113 Toxaphene ND ND ND
114 Antimony RG ND ND
115 Arsenic ND ND ND
116 Asbestos ND ND ND
117 Beryllium ND ND ND
118 Cadmium R'G RG RG
119 Chromium RG RG RG
120 Copper NT RG RG
121 Cyanide RG RG RG
122 Lead RG RG RG
123 Mercury ND ND ND
124 Nickel RG RG RG
125 Selenium ND ND ND
126 Silver SU ND ND
127 Thallium ND ND ND
128 Zinc RG RG RG
129 2,3,7,8-tetrachlorodihenzo-
p-dioxin (TCDD) ND ND ND
LEGEND:
ND = NOT DETECTED
NQ « NOT QUANTIFIABLE
SU, = SHALL, UNIQUE SOURCES
NT = NOT TREATABLE
RG = REGULATION CONSIDERED
179
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Intentionally Blank Page
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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 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 has 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 coil coating 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 coil coating
category, and technologies demonstrated in treatment of similar
wastes in other industries.
Coil coating wastewater streams characteristically contain
significant levels of toxic inorganics. Chromium, cyanide, lead,
nickel, and zinc are found in coil coating wastewater streams at
substantial concentrations. These toxic inorganic pollutants
constitute the most significant wastewater pollutants in this
category.
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 with very low solubilities.
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.
181
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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, 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 S02 + 3 H20 > 3 H2S03
3 H2S03 + 2H2Cr04 > Cr2(S04)3 + 5 Hz0
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-
182
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controller device to control process conditions with respect to
pH and oxidation reduction potential (ORP). Gaseous sulfur
dioxide is metered to the reaction tank to maintain the ORP
within the range of 250^ to>300 millivolts. Sulfuric acid is
added to maintain a pH level of from 1.8 to 2.0. The reaction
tank is equipped with a propeller agitator designed to provide
approximately one turnover per minute. Figure VII-13 (page 288)
shows a continuous chromium reduction system.
Application and Performance. Chromium reduction is used in coil
coating for treating chromating rinses for high-magnesium
aluminum basis materials. Electroplating rinse waters and
cooling tower blowdown are two major sources of chromium in waste
streams. A study of an operational waste 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. Reliability; Maintenance consists of
periodic removal of slodge, the frequency of which 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. This
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.
183
-------
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 and noncontact
cooling.
2. Chemical Precipitation
Dissolved toxic metal ions and certain anions may be chemically
precipitated for removal by physical means such as sedimentation,
filtration, or centrifugation. 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 complete precipitation. 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 specific metal
184
-------
in the raw waste (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
coil coating 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 waste 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 sacrificial 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 of pH. 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 metals hydroxides and sulfides shown in Figure VII-1
(page 276), and by plotting effluent zinc concentrations against
pH as shown in Figure VII-3 (page 262). 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., 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
processing plant (47432) as displayed in Table VII-1 (page 257).
185
-------
Flow through this system is approximately 49,263 1/h (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 ©n the second day, when the pH slipped to an
unacceptably low level and intermediate values were were achieved
on the third day when pH values were less than desirable but in
between the first and second days.
Sodium hydroxide is used by one facility (plant 439) for pH
adjustment and chemical precipitation, followed by settling
(sedimentation and a polishing lagoon) of precipitated solids.
Samples were taken prior to caustic addition and following the
polishing lagoon. Flow through the system is approximately
22/700 1/hr (6,000 gal/hr).
These data for this plant indicate that the system was operated
efficiently. Effluent pH was controlled within the range of 8.6-
9.3, and, while raw waste loadings were not unusually high, most
toxic metals were removed to very low concentrations.
Lime and sodium hydroxide are sometimes used to precipitate
metals. Data developed from plant 40063, a facility with a metal
bearing wastewater, exemplify efficient operation of a chemical
precipitation and settling system. Table VII-3 (page 258) shows
sampling data from this system, which uses lime and sodium
hydroxide for pH adjustment, chemical precipitation,
polyelectrolyte flocculant addition, and sedimentation. Samples
were taken of the raw waste influent to the system and of the
clarifier effluent. Flow through the system is approximately
5,000 gal/hr.
At this plant, effluent TSS levels were below 15 mg/1 on each
day) despite average raw waste TSS concentrations of over 3500
mg/1. Effluent pH was maintained at approximately 8, lime
addition was sufficient to precipitate the dissolved metal ions,
and the flocculant addition and clarifier retention served to
remove effectively the precipitated solids.
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
186
-------
Table VII-4 (page 259) (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 VI1-5 (page 260).
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-2, (page 277) solubilities of PbS and AgzS 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 hydroxide^. 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
as reducing agents for the hexavalent chromium according to the
reaction:
Cr03 + FeS + 3H20 —->Fe(0H)3 + Cr(0H)3 + S
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 VI1-6 (page 261 ) 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
187
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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-4 (page 279) ("Heavy
Metals Removal," by Kenneth Lanovette, Chemical Engineering
Deskbook Issue, Oct. 17, 1977) explain this phenomenon.
Coprecipitation With Iron- The presence of substantial quantites
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 incidentally 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
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 262).
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
188
-------
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 (Na2S0*). 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
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 waste 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.
189
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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 waste treatment technology used by most industrial
waste 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 Coil Coating Plants. Chemical precipitation is used at 37
coil coating plants. The quality of treatment provided, however,
is variable. A review of collected data and on-site observations
reveals that control of system parameters is often poor. Where
precipitates are removed by clarification, retention times are
likely to be short and cleaning and maintenance questionable.
Similarly, pH control is frequently inadequate. As a result of
these factors, effluent performance at coil coating plants
nominally practicing the same wastewater treatment is observed to
vary widely.
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.
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
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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 262) presents data from three coil coating
plants. A fourth plant was visited for the purpose of observing
plant testing of the cyanide precipitation system. Specific data
from this facility are not included because: (1) the pH was
usually well below the optimum level of 9.0; (2) the historical
treatment data were not obtained using the standard cyanide
analysis procedure; and (3) matched input-output data were not
made available by the plant. Scanning, the available data
indicates that the raw waste CN level was in the range of 25.0;
the pH 7.5; and treated CN level was from 0.1 to 0.2.
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 waste, the concentration of cyanide can
be reduced in the effluent stream to under 0.07 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.
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4. Granular Bed Filtration
Filtration occurs in nature as the surface 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 bapkwash 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 289) 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 polyelectroiyte usually results in a substantial
improvement in filter performance.
Auxilliary 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.
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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
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 2.04 - 5.30 1/sq m-hr
Rapid Sand 40.74 - 51.48 1/sq m-hr
High Rate Mixed Media 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 263).
Advantages and Limitations. 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
filter technology 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.
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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
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
municipal treatment 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.
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 290) 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.
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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.
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.
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.Solid Waste Aspects: Because it is generally drier than other
types of sludges, the filter sludge cake can be handled with
relative ease. The accumulated sludge may be disposed by any of
the accepted procedures depending on its chemical composition.
The levels of toxic metals present in sludge from treating coil
coating wastewater necessitate proper disposal.
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-7 (page 266)
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
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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.
Application and Performance. Settling and clarification are used
in the coil coating category 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 waste 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 263) 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.
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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.
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 waste treatment. The advanced
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clarifiers are just beginning to appear in significant numbers in
commercial applications. Sedimentation or clarification is used
in many coil coating plants as shown below.
Settling is used both as part of end-of-pipe treatment and within
the plant to allow recovery of process solutions and raw
materials.
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
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. Oil cleaned from the strip is a
principal source of oil. Skimming is applicable to any waste
stream containing pollutants which float to the surface. It is
commonly used to remove free oil, grease, and soaps. Skimming is
Settling Device
No. Plants
Settling Tanks
Clarifier
Tube or Plate Settler
Lagoon
21
24
4
6
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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 waste 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 shown below illustrate the capabilities of the technology
with both extremely high and moderate oil influent levels.
This data, displayed in Table VII-11 (page 264); 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
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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 84).
A study of priority organic compounds commonly found in metal
forming operations waste streams indicated that incidental
removal of these compounds often occurs as a result of oil
removal or clarification processes. When all organics analyses
from visited plants 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 waste. The API oil-water separation system
and the thermal emulsion breaker (TEB) performed notably in this
regard, as shown in the following table (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.
Percent Removal
Plant-Day
Oil & Grease
Organics
1054-3
13029-2
13029-3
38053-1
38053-2
Mean
95.9
98. 3
95. 1
96.8
98.5
96.9
98.2
78.0
77.0
81 .3
86.3
84.2
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The unit operation most applicable to removal of trace priority
organics is adsorption, and chemical oxidation is another
possibility. Biological degradation is not generally applicable
because the organics are not present in sufficient concentration
to sustain a biomass and because most of the organics are
resistant to biodegradation.
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
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
extensively by industrial waste treatment systems. Oil skimming
is used in seven coil coating plants.
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 skimming are
installed and operating properly where appropriate.
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L&S PERFORMANCE ~ COMBINED METALS DATA BASE
Before proposal, chemical analysis data were collected of raw
waste (treatment influent) and treated waste (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 data base for determining the effectiveness of L&S
technology. Each of these plants 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.
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
relative amounts of pollutants in the raw wastewaters.
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Therefore, the wastewater data derived from plants that only
electroplate are not used in developing limitations for the coil
coating category.
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.
For the purpose of developing treatment effectiveness, certain
data were deleted from the data base. Before examination for
homogeneity the first two data items below were removal; the
third data item was removed after the homogeneity examination.
These deletions were made to ensure that the data reflect
properly operated treatment systems and actual pollutant removal.
The following criteria were used in making these deletions;
o Plants where malfunctioning processes or treatment systems
at time of sampling were identified.
o Data days where pH was less than 7.0 or TSS was greater than
50 mg/1. (This is a prima facia indication of poor
operation).
o Data points where the raw waste value was too low to assure
actual pollutant removal occurred (i.e., less than 0.1 mg/1
of pollutant in raw waste).
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-8 to
VII-16 (Pages 283-291). 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 »
and log variance
-------
mean of X = E(X) = exp (v + a2 /2)
variance of X = V(X) = exp (2 n + «2) [exp( az )-1]
99th percentile = X.9, •- exp ( 11 + 2.33 c)
where exp is e, the base of the natural logarithm. The term
lognormal is used because the logarithm of X has a normal
distribution with mean v and variance
-------
where n = total number of observations
I
i=l
V(y) = pooled log variance
-E(Ji - D Si2
i=l
"E(Ji -1)
1=1
S-j^ = log variance at plant 1
=J^(yTj ~ ?l)2/(Jj - 1)
yi = 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
mean = E(X) = exp(y) ij> n (0*5 V(y))
99th percentile = X.gg = exp[y + 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
Lognormal 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
significantly greater than the copper data from the other plants.
Thus, copper effluent values shown in Table VI1-14 (page 265) 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
and
where
207
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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
log variance for cadmium. The variance used to determine the
values shown in Table VII-13 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 based 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 assumed.
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
u and
-------
measurements. The following relationships then hold assuming the
daily measurements are independent:
mean of X10 = E(Xt0) = E(X)
variance of X~10 = V(X~10) = V(X) * 10.
Where E(X) and V(X) are the mean and variance of X, respectively,
defined above. We then assume that Xl0 follows a lognormal
distribution with log mean U10 and log standard deviation oJ0.
The mean and variance of X10 are then
E(X10) = exp (* 10 + 0.5 tf2l0)
V(X10) = exp (2 „ 10 + a210) [exp( *210)-1]
Now, » 10 and tf2,0 can be derived in terms of v and as
„ 10 = v + x0 and ei0f respectively.
30 Sample Averages
The average values based on 30 measurements are determined on the
basis of a statistical result known as the Central Limit Theorem.
This Theorem states that, under general and nonrestrictive
assumptions, the distribution of a sum of a number of random
variables, say n, is approximated by the normal distribution.
The approximation improves as the number of variables, n,
increases. The Theorem is quite general in that no particular
distributional form is assumed for the distribution of the
individual variables. In most applications (as in approximating
the distribution of 30-day averages) the Theorem is used to
approximate the distribution of the average of n observations of
a random variable. The result makes it possible to compute
approximate probability statements about the average in a wide
range of cases. For instance, it is possible to compute a value
below which a specified percentage (e.g., 99 percent) of the
averages of n observations are likely to fall. Most textbooks
state that 25 or 30 observations are sufficient for the
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approximation to be valid. In applying the Theorem to the
distribution of the 30 day average effluent values, we
approximate the distribution of the average of 30 observations
drawn from the distribution of daily measurements and use the
estimated 99th percentile of this distribution. The monthly
limitations based on 10 consecutive measurements were determined
using the lognormal approximation described above because 10
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 x"30 _!l E(X30 )_= E(X)
variance of X30 = V(X30) = V(X)/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
X30 (*99,) = EU) s 2.33 /"vfxT~T30
where a _
E(X) = exp(y) w n (0.5V(y)) , \
and VOO = exp(2y) t * „(2V(y)) - *
The formulas for E(X) and V(X) are estimates of E(X) and V(X)
respectively given in Aitchison, J. and J.A.C. Brown, The
Lognormal Distribution, Cambridge University Press, 1963, page
45.
Application
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
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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
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 266) 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 VII-15
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 266) and
VII-17 (page 267) 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
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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.
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 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
performance is achieved at a beryllium plant with the comparable
untreated wastewater matrix shown in Table VII 17.
Mercury (Hq) - 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-1& (page
267).
Thallium (T1) - 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 (A1) - 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.
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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
plant shown in Table VI1-17 is comparable to the combined metals
data set.
L,S&F PERFORMANCE
Tables VI1-18 and VI1-19 (pages 268-269) 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 waste data was collected only occasionally at each facility
and the raw waste data is presented as an indication of the
nature of the wastewater treated. Data from 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 VI1-20 (Page 270) 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 waste 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
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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, as well as to the porcelain enameling and
nonferrous melting and refining.
ANALYSIS OF TREATMENT SYSTEM EFFECTIVENESS
Data are presented in Table VI1-14 (page 265) showing the mean,
one day, 10 day, and 30 day values for nine pollutants examined
in the L&S metals data base. The mean variability factor for
eight 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 average variability
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 VI1-15 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 (page
271 •).
LS&F technology data are presented in Tables VII-18 and VI1-19
(pages 268-269). 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
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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 waste should be less than raw waste)
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
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 VII-20 (page 270) 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
VII-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 VI1-20) are well within the range of raw wastewater
concentrations of the combined metals data base (Table VII-15),
21 5
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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 VI1-15 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
average metal variability factors. The treatment method 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
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.
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Although iron was reduced 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.
8. 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
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
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(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 292). 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. 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 2,4-dimethylphenol,
fluoranthene, isophorone, naphthalene, all phthalates, and
phenanthrene. It was reasonably effective on 1,1,1-
trichloroethane, 1,1-dichloroethane, phenol, and toluene. Table
VII-22 (page 272) summarizes the treatability rating for most of
the organic priority pollutants by activated carbon as compiled
by EPA. Table VII-23 (page 273) summarizes classes of organic
compounds together with examples of organics that are readily
adsorbed on 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
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regeneration are relatively high. Cost surveys show that thermal
regeneration is generally economical when carbon usage exceeds
about 1,000 lb/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.
9. Centrifuqation
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 293).
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.
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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
operation, the solids content of the sludge can be increased to
20-35 percent.
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
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operation of centrifuges hassbeen 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.
Demonstration 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.
10. 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
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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 arid 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
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 (monofilament, 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.
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Demonstration Status¦ Coalescing has been fully demonstrated in
industries generating oily., wastewater, although none are
currently not in use at any coil coating facility.
11. 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:
1. Cl2 + NaCN + 2-NaOH —> NaCNO + 2NaCl + H20
2. 3C12 + 6NaOH + 2NaCN0 —> 2NaHC03 + 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 294).
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
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
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effluent levels that are nondetectable. The process is
potentially applicable to coil coating 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.
Demonstration Status. The oxidation of cyanide wastes by
chlorine is a widely used process in plants using cyanide in
cleaning and metal processing baths.
12. 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
VII-20 (page 295).
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
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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.
13. Cyanide Oxidation By Ozone With UV Radiation
. ¦ *
One of the modifications of the ozonation process is the
simultaneous application of ultraviolet light arid ozone for the
treatment of wastewater, including treatment of halogenated
organics. The combined action of these two forms produces
reactions by photolysis, photosensitization, hydroxylation,
oxygenation and oxidation. The process is unique because several
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
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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 296) 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 coil coating plants to
destroy cyanide present in waste streams from some conversion
coating operations.
14. 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 hy.droxides.
The metals are then removed from solution by either settling • or
filtration.
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.
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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 introduced in
1971 and is used in several facilities. No coil coating plants
use oxidation by hydrogen peroxide.
15. Evaporation
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 297) 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 generially 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
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
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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. Waste water
is "drawn" into the system by the vacuum so that a constant
liquid 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
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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
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 supersaturat ion effects. Steam distiliable
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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. Evaporation is a fully developed,
commercially available 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.
No data have been reported showing the use of evaporation in coil
coating plants.
16. 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 298) 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 1.0, 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 often 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
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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 different flotation techniques
and the method of bubble generation for each process.
Froth Flotation - Froth flotation is based on differences in the
physiochemical properties in various particles. Wettability and
surface properties affect the particles' ability to attach
themselves to gas bubbles in an aqueous medium. In froth
flotation, air is blown through the solution containing flotation
reagents. The particles with water repellant surfaces stick to
air bubbles as they rise and are brought to the surface. A
mineralized froth layer, with mineral particles attached to air
bubbles, is formed. Particles of other minerals which are
readily wetted by water do not stick to air bubbles and remain in
suspension.
Dispersed Air Flotation - In dispersed air flotation, gas bubbles
are generated by introducing the air by means of mechanical
agitation with impellers or by forcing air through porous media.
Dispersed air flotation is used mainly in the metallurgical
industry.
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.
Vacuum Flotation - This process consists of saturating the waste
water with air either directly in an aeration tank, or by
permitting air to enter on the suction of a wastewater pump. A
partial vacuum is applied, which causes the dissolved air to come
out of solution as minute bubbles. The bubbles attach to solid
particles and rise to the surface to form a scum blanket, which
is normally removed by a skimming mechanism. Grit and other
heavy solids that settle to the bottom are generally raked to a
central sludge pump for removal. A typical vacuum flotation unit
consists of a covered cylindrical tank in which a partial vacuum
is maintained. The tank is equipped with scum and sludge removal
mechanisms. The floating material is continuously swept to the
tank periphery, automatically discharged into a scum trough, and
removed from the unit by a pump also under partial vacuum.
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Auxilliary equipment includes an aeration tank for saturating the
wastewater with air, a tank with a short retention time for
removal of large bubbles, vacuum pumps, and sludge pumps.
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 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.
Demonstrat ion Status. Flotation is a fully developed process and
is readily available for the treatment of a wide variety of
industrial waste streams.
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17. 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 299) shows the construction of a
gravity thickener.
Application and Performance. Thickeners are generally used in
facilities- where the sludge is tb 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
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 (lbs/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
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recirculated in part, or it may be subjected to further treatment
prior to discharge.
Demonstrat ion 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.
18. 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
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.
19. 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
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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 300). 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
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
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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 end-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-24 (page 274).
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.
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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 are available for commercial use, and industry sources
estimate the number of units currently in the field at well over
120. The research and development in ion exchange is focusing on
improving the quality and efficiency of the resins, rather than
new applications. Work is also being done on a continuous
regeneration process whereby the resins are contained on a fluid-
transfusible belt. The belt passes through a compartmented tank
with ion exchange, washing, and regeneration sections. The
resins are therefore continually used and regenerated. No such
system, however, has been reported beyond the pilot stage.
20. Membrane Filtration
Membrane filtration is a treatment system for removing
precipitated metals from a wastewater stream. It must therefore
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.
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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 VI1-25
(page 274) 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.
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.
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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. Although there are no data on the use of
membrane filtration in coil coating plants, the concept has been
successfully demonstrated using coil coating plant wastewater. A
unit has been installed at one coil coating plant based on these
tests.
21. 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
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 in coil
coating 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.
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Table VI1-27 (page 275) 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 '•¦f toxic heavy metals in coil coating manufacturing
wastewater '.-,1 in ger^ral 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.
No data have been reported showing the use of peat adsorption in
coil coating plants.
22. Reverse Osmosis
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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 VII-26 (page 301) depicts a reverse
osmosis system.
As illustrated in Figure VII-27 (page 302), 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 arid 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
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.
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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
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.
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Advantages and 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 prefilters 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
reach the module and helps keep the buildup to a minimum. These
solids require proper disposal.
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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.
23. 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 303) 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.
Dewatering of sludge on sand beds occurs by two mechanisms:
filtration of water through the bed and evaporation of water as a
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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 times 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 cover 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.
24. 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 304) represents the ultrafiltration
process.
Application and Performance. Ultrafiltration has potential
application to coil coating plants for separation of oils and
residual solids from a variety of waste streams. In treating
coil coating 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.
The following test data indicate 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-thfid 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 Limitat ions. 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. Reliability: The reliability of an
ultrafiltration system is dependent on the proper filtration,
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
247
-------
solution through the system to remove an oil and grease film
which accumulates on the membrane. With proper maintenance
membrane life can be greater than twelve months.
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.
25. 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 305).
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
248
-------
dewatered sludge from this process is in the form of a moist cake
and can be conveniently handled.
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 waste water 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.
If intermittent operation is used, the filter equipment should be
drained and washed each time it is taken out of service. An
allowance for this wash time must be made in filtering schedules.
Solid Waste Aspects: Vacuum filters generate a solid cake which
is usually trucked directly to landfill. All of the metals
extracted from the plant wastewater are concentrated in the
filter cake as hydroxides, oxides, sulfides, or other salts.
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 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
249
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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. Coil coating operations consist of
three main functional groups; cleaning, conversion coating and
painting. Each of these operations is amenable to reduction of
both chemical and water usage. These reductions 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.
A major portion of the oil, grease, dirt and oxide coating is
removed from the coil by alkaline cleaning and rinsing. Cleaning
of the coil is extremely important because incomplete cleaning
adversely affects subsequent operations. The primary factors
that adversely affect cleaning and rinsing efficiency are:
Incorrect alkaline cleaning compound for basis material.
Incorrect temperature' of alkaline cleaning solution and
rinse water.
Insufficient number of spray nozzles or insufficient
pressure for both alkaline cleaning and rinsing.
Insufficient squeegee action to prevent excessive dragout of
alkaline cleaning solution.
Absence of bath equilibrium controls that automatically add
make-up water and cleaning solution.
Undefined soils
Insufficient time
Alkaline cleaning solutions are formulated for specific basis
materials. For example, the cleaning compound for steel is more
alkaline than for galvanized or aluminum. The most advanced
alkaline 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 alkaline
cleaning solution and concentration. A solution that is too cold
may not be able to dissolve either enough of the dry alkaline
cleaning compound or the dirt, oil, grease and oxides from the
coil. A solution that is too warm may set certain types of soil
onto the coil itself, in the spray nozzles, or onto the tank. In
addition, excessive temperature may cause excessive foaming.
250
-------
Spray nozzles and pressures should be adequate to assure
overlapping coverage of the work area. Experience will dictate
how fast the coil can move and be effectively cleaned with a
given set of spray nozzles and pressure.
Following the alkaline cleaning, squeegees are important to
reduce dragout of the alkaline cleaning compounds. Excessive
dragout reduces the rinsing rate and wastes cleaning materials.
Of the thirteen visited plants, ten have dragout control in the
form of squeegees or air knives somewhere in the line. Automatic
alkalinity sensors can reduce the consumption of alkaline
cleaning compounds; six of the visited plants used automatic
controls to maintain bath equilibrium.
The use of alkaline cleaning rinse -water as make-up to the
alkaline 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 cases, 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 overfrom flow flow each tank in the
production sequence becomes the feed for the tank preceeding it;
the water flow from tank to tank cascades countercurrently to the
products sequence.
Countercurrent Cascade Rinsing
Rinse water requirements and the benefits of countercurrent
rinsing may be influenced by the volume of solution dragout
carried into each rinse stage by the material being rinsed, by
the number of rinse stages used, by the initial concentrations of
impurities being removed, and by the final product cleanliness
required. The influence of these factors is expressed in the
rinsing equation which may be stated simply as:
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
251
-------
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 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 it is removed from process baths or rinses.
Without specific plant data available to determine drag-out, we
can make an estimate of rinse water reduction to be achieved with
three-stage countercurrent rinsing by assuming a thickness of any
process solution film as it is introduced into the rinse tank.
If the film is 0.6 mil thick, (equivalent to the film on a
well-drained vertical surface) then the volume of process
solution, VD, carried into the rinse tank on one square meter of
metal will be:
VD = 0.0006 in X 2.54 cm x 144 sq in x (2.54)2 sq cm X
in sq ft sq in
1 liter x 1 sq ft = 0.015 1/m2 of metal
1000 cu cm 0.0929 sq m
To calculate the benefits of countercurrent rinsing for coil
coating we assume a 3 stage countercurrent spray rinse is
installed after alkaline cleaning and conversion coating
operations. Using the mean subcategory cleaning rinse and
conversion coating rinse water use from Table V-12 as Vr we have:
Vr
Conversion
Subcategory Cleaning Coating
Steel 2.274 0.421
Galvanized 1.368 0.528
Aluminum 0.964 0.546
Let r = Co then rVn = Vr
Cf VD
For single stage rinsing n = 1
252
-------
therefore r = Vr
VD
and: = .,r
Conversion
Subcategory Cleaning Coating
Steel 151.6 28.1
Galvanized 91.2 35.2
Aluminum 64.3 36.4
And these are assumed to be the rinse ratios achieved for these
operations at visited plants.
For a 3-stage countercurrent rinse to obtain the same r,
Vr = r1/3 and: VR
VD VD
Conversion
Subcategory Cleaning Coating
Steel 5.33 3.04
Galvanized 4.50 3.28
Aluminum 4.01 3.31
But VD « 0.015
therefore for 3-stage countercurrent rinsing Vr is
Vr /sq m
Conversion
Subcategory Cleaning Coating
Steel 0.080 0.046
Galvanized 0.068 0.049
Aluminum 0.060 0.050
Adding the water use for the cleaning rinse and conversion
coating rinse gives the water use which can be achieved by
substituting 3-stage countercurrent spray rinsing for each single
stage spray rinse:
Subcategory Combined Water Use 1/sq m
Steel 0.126
Galvanized 0.117
Aluminum 0.110
These numbers may vary depending on efficacy of squeegees or air
knives, and the rinse ratio desired.
253
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In Section XI of this document, water use allowances are based on
practical considerations, assuming that 3-stage countercurrent
spray rinsing is substituted for single stage spray rinsing. The
overall water allowances are from 2.5 to 4.3 times the above
water use which are derived from strictly theoretical
considerations and limited to rinse water use, excluding batch
dumps.
In-process Control
The conversion coating function is the heart of the coil coating
operation. This is one of the steps in which material is added
to the coil. The three types of conversion coating operations
used are chromating, phosphating (either zinc or iron) and
complex oxides.
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 coil 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. This control was used at six of the visited
plants. Chemical suppliers provide a series of chemicals for
each type of conversion coating. The series includes a bath
make-up 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 coil speed, there should be adequate spray nozzle coverage
and'pressure. This assures that all areas of the coil have
sufficient reaction time to allow buildup of a specified film
thickness. After film formation, a set of squeegees is required
to reduce dragout which wastes unreacted conversion coating
chemicals and contaminates the subsequent sealing rinse.
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 able 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 valance of the trivalent chromium to
hexavalent chromium. The solution is . then returned to the
process tank. This chromium regeneration process was employed at
two plants.
A sealing rinse is used for both phosphate and chromate
conversion coatings. The sealing rinses are basically dilute
solutions of chromic acid, phosphoric acid and sometimes certain
metal ions such as zinc. Depending upon the type of conversion
coating and basis material, various proportions of these
constituents are used. This sealing rinse removes unreacted
conversion coating chemicals from the film surface, thereby
stopping the reactions and sealing the effective pore area of the
film with a layer of chromium complexes. Similar to conversion
coating operations, the solution must be maintained at proper
temperatures and spray nozzle area and pressure must be adequate
for the desired coil speed. The rinse can be recirculated and
reused until dragged in conversion coating chemicals contaminate
the bath, rinsing action is affected, or the chemicals themselves
are depleted. Following the sealing rinse, good practice,
provides a squeegee roll and an air knife to prevent dragout and
to prevent wet strip from entering the painting operation. The
benefits of countercurrent rinsing for this step were discussed
previously.
The subsequent painting and baking operations are followed by a
water spray quench. This quench cools the basis material and
films for either subsequent coats of paint or final rewinding.
The freshly painted and cured surfaces are clean and stable and
very little contamination of the quench water occurs. To
conserve water and prevent dilution of other plant wastes
discharging to treatment, quench water can either be recycled
through a cooling tower, with make-up water added as needed, or
reused as the cleaning or conversion coating rinse. Fifteen
plants in the data base had the necessary equipment for partial
or full quench water recycle. Five plants reused a portion of
their quench water as the cleaning rinse.
In-Process Substitutions
The in-process substitutions for this industry involve only the
conversion coating phases of the total operation. The alkaline
cleaning, rinsing, painting, baking, and quenching operations
remain virtually unchanged. These inprocess substitutions either
eliminate the discharge of a significant pollutant or entirely
eliminate discharge from the conversion coating operation.
255
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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 in solution.
There are competing chemical systems that do not contain cyanide
and efforts should be made to eliminate cyanide use where
possible.
Certain sealing rinses contain zinc which, is also a priority
pollutant and requires treatment before being discharged.
Efforts should be made to incorporate and use sealing rinses that
do not contain zinc. Several of the visited plants used non-zinc
sealing rinses.
No-rinse conversion coating is a possible substitute for chromate
conversion coating which can be applied to steel, galvanized and
aluminum basis materials. The operation eliminates chromate
conversion coating bath dumps and sealing rinse discharges by
applying the coating with a roll coater. Existing lines require
extensive modification to effectively use this technology. Three
plants in the data base indicated that they currently use no-
rinse conversion coating. The high line speeds and nature of no-
rinse conversion coating require more precise control of
cleaning, rinsing, and drying than a typical conversion coating
line with rinsing. No-rinse conversion coating requires only
liquid level monitoring as bath constituents are all depleted at
the same rate. The benefits of countercurrent rinsing for this
step were discussed previously.
256
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TABLE VI'I-1
pH CONTROL EFFECT ON METALS REMOVAL
Day 1 Day 2 Day 3
In Out In Out In Out
pH Range 2.4-3.4 8.5-8.7 1.0-3.0 5.0-6.0 2.0-5.0 6.5-8.1
(mg/I)
TSS 39 8 16
Copper 312 0.22 120
Zinc 250 0.31 32.5
TABLE VI1-2
Effectiveness of Sodium Hydroxide for Metals Removal
Day 1 Day 2 Day 3
In Out In Out. In 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
0.097
0.0
0.057
0.005
0.068
0.005
Cu
0.063
0.018
0. 078
0.014
0. 053
0.019
Fe
9.24
0. 76
15.5
0. 92
9.41
0.95
Pb
1 .0
0.1 1
1 .36
0.13
1 .45
0.11
Mn
0.11
0.06
0.1 2
0.044
0. n
0.044
Ni
0.077
0.011
0.036
0.009
0. 069
0.01 1
Zn
.054
0.0
0.12
0.0
0.19
0.037
TSS
13
1 1
1 1
1 9
5.12
25. 0
16
1 07
43,8
7
0. 66
0.66
257
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Effectiveness of
Lime and
TABLE VI1-3
Sodium Hydroxide for
Metals
Removal
Day
In
1
Out
Day
In
2
Out
In
Day 3
Out
pH Range
(mg/1)
9.2-9.6
8.3-9.8
9.2
7.6-8.1
9.6
7.8-8
A1
37.3
0.35
38. 1
0.35
29.9
0.35
Co
3.92
0.0
4.65
0.0
4.37
0.0
Cu
0.65
0. 003
0. 63
0. 003
0.72
0.003
Fe
137
0.49
110
0,57
208
0.58
Mn
175
0.12
205
0.01 2
245
0.1 2
Ni
6.86
0.0
5. 84
0.0
5. 63
0.0
Se
28.6
0.0
' 30.2
0.0
27.4
0.0
Ti
143
0.0
125
0.0
115
0.0
Zn
18.5
0. 027
16.2
0.044
17.0
0.01
TSS
4390
9
3595
13
2805
13
258
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TABLE VI1-4
THEORETICAL SOLUBILITIES OF HYDROXIDES AND SULFIDES
OF SELECTED METALS IN PURE WATER
Metal
Cadmium (Cd++)
Chromium (Cr+++)
Cobalt (Co++)
Copper (Cu++)
Iron (Fe++)
Lead (Pb++)
Manganese (Mn++)
Mercury (Hg++)
Nickel (Ni++)
Silver (Ag+)
Tin (Sn++)
Zinc (Zn++)
As Hydroxide
Solubility of metal ion, mq/1
2.3
8.4
2.2
2.2
8.9
2. 1
1 .2
3,
6,
13,
1 ,
1 ,
10-®
10-«
10-1
10-2
10-1
io-*
10-'
x 1 0-*
As Carbonate
1.0 x 10-4
7.0 x 10-3
3.9 x 10-2
1.9 x 10-i
2.1 x 10-i
7.0 x 10-4
As Sulfide
6.7 x 10->
No precipita
1.0 x 10-"
5.8 x 10-i
3.4 x 10-s
3.8 *10"'
2.1 x 10-'
9.0 x 10-2
6.9 x 10-«
7.4 x 10-i
3.8 x 10-e
2.3 x 10-»
259
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TABLE VI1-5
SAMPLING DATA FROM SULFIDE
PRECIPITATION-SEDIMENTATION SYSTEMS
Treatment
PH
(mg/1)
Cr+6
Cr
Cu
Fe
Ni
Zn
Lime, FeS, Poly-
electrolyte,
Settle, Filter
In
Out
5.0-6.8
25.6
32.3
0.52
39.5
8-9
<0.014
<0.04
0.10
<0.07
Lime, FeS, Poly-
electrolyte,
Settle, Filter
In
7.7
0.022
2.4
Out
7.38
<0.020
<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 the
Metal Finishing Industry: Sulfide Precipitation. USEPA. EPA
No. 625/8/80-003, 1979.
Industrial Finishing, Vol. 35, No. 11, November, 1979.
Electroplating sampling data from plant 27045.
260
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TABLE VI1-6
SULFIDE PRECIPITATION-SEDIMENTATION PERFORMANCE
Parameter
Treated Effluent
(mg/I)
Cd
CrT
Cu
Pb
Hg
Ni
Ag
Zn
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
No. 62578/80-003, 1979.
Addendum to Development Document for Effluent Limitations
Guidelines and New Source Performance Standards. Major
Inorganic products Segment' of Inorganics Point Source
Category? USEPA., EPA Contract No. EPA=68-01-3281 (Task 7),
June, 1978.
261
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Table VII-7
FERRITE CO-PRECIPITATION
PERFORMANCE
Metal
Influent(mg/1)
Effluent(mg/1)
Mercury
7.4
0.001
Cadmium
240
0.008
Copper
10
0.010
Zinc
18
0.016
Chromium
10
<0.010
Manganese
1 2
0.007
Nickel
1 ,000
0.200
Iron
600
0.06
Bismuth
240
0.100
Lead
475
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)
Plant
Method In
Out
1057
FeS04 2.57
0. 024
2.42
0.015
3.28
0.032
33056
FeS04 0.14
0.09
0.16
0.09
12052
ZnSO* 0.46
0.14
0.12
0.06
Mean
0.07
262
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Plant ID #
Table VII-9
Multimedia Filter Performance
TSS Effluent Concentration, mq/1
06097
0.0,
0.0,
0.5
1 3924
1 .8,
2.2,
5.6,
4.0,
4.0, 3.0,
3.0,
2.0,
5.6,
3.6,
2.4, 3.4
18538
1 .0
30172
1.4,
7.0,
1 .0
36048
2.1,
2.6,
1 .5
mean
2.61
TABLE VII-10
PERFORMANCE OF SELECTED SETTLING SYSTEMS
PLANT ID SETTLING SUSPENDED SOLIDS CONCENTRATION (mg/1)
DEVICE Day 1 Day 2 Day 3
In Out In Out In Out
01057
Lagoon
54
6
"56
6
50
5
09025
Clarifier
Settling
Ponds
1100
9
1900
12
1620
5
11058
Clarifier
451
17
-¦
-
-
-
12075
Settling
Pond
284
6
242
10
502
14
19019
Settling
Tank
170
1
50
1
—
33617
Clarifier &
Lagoon
—
1662
16
1298
4
40063
Clarifier
4390
9
3595
12
2805
13
44062
Clarifier
182
13
118
14
174
23
46050
Settling
Tank
295
10
42
10
153
8
263
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Table VII-11
SKIMMING PERFORMANCE
Oil & Grease
mg/1
Plant Skimmer Type In Qui
06058 API 224,669 17.9
06058 Belt 19.4 8.3
TABLE VII-12
SELECTED PARITION COEFFICIENTS
PAH Log Octanol/Water
Priority Pollutant 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-benzofluoranthene
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
264
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TABLE VII-13
TRACE ORGANIC REMOVAL BY SKIMMING
API PLUS BELT SKIMMERS
(From Plant 06058)
Oil & Grease
Chloroform
Methylene Chloride
Naphthalene
N-nitrosodiphenylamine
Bis-2-ethylhexylphthaiate
Diethyl phthalate
Butylbenzylphthaiate
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.
0.
0,
0,
0,
0,
6
007
01 2
004
1 82
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,
0,
0.
0,
0.
12
57
30
41
21
One Day
Max.
0.32
0.42
1 .90
12.0
0.
1 ,
1 .
1 ,
0,
41 ,
15
41
33
23
43
0
10 Day Avg.
Max.
0.15
0.17
1 .00
0,
1 ,
13
00
0.56
0.63
0.34
20.0
30 Day Avg.
Max.
0,
0,
0,
1 3
12
73
0.12
0.75
0.41
0.51
0.27
15.5
265
-------
TABLE VII-15
L&S PERFORMANCE
ADDITIONAL POLLUTANTS
Pollutant Average Performance (mq/1)
Sb 0.7
As 0.51
Be 0.30
Hg 0.06
Se 0.30
Ag 0.10
Th 0.50
ai i. n
Co 0.05
F 14.5
TABLE VII-16
COMBINED METALS DATA SET - UNTREATED WASTEWATER
Pollutant Min. Cone (mq/1) Max. Cone, (mq/1)
Cd <0.1 3.83
Cr <0.1 116
Cu <0.1 108
Pb <0.1 29.2
Ni <0.1 27.5
Zn <0.1 337.
Fe <0.1 263
Mn. <0.1 5.98
TSS 4.6 4390
266
-------
TABLE VI1-17
MAXIMUM POLLUTANT LEVEL IN UNTREATED WASTEWATER
ADDITIONAL POLLUTANTS
(mg/1)
Pollutant As & Se Be Aq F
As 4.2 -
Be - 10.24
Cd <0.1 - <0.1 <0.1
Cr 0.18 8.60 ' 0.23 22.8
Cu 33.2 1.24 ' 110.5 2.2
Pb 6.5 0.35 11.4 5.35
Ni - 100 0.69
Ag - - 4.7 -
Zn 3.62 0.12 1512 <0.1
F - - - 760
Fe - 646 -
O&G 16.9 - 16 2.8
TSS 352 796 587.8 5.6
267
-------
TABLE VII-18
PRECIPITATION-SETTLING-FILTRATION (LS&F) PERFORMANCE
Plant A
Mean + Mean + 2
Parameters No Pts. Range mq/1 std. dev. std. dev.
For 1979-Treated Wastewater
Cr 47 0.015 - 0.13 0.045 +0.029 0.10
Cu 12 0.01 - 0.03 0.019 +0.006 0.03
Ni 47 0.08 - 0.64 0.22 +0.13 0.48
Zn 47 0.08 - 0.53 0.17 +0.09 0.35
Fe
For 1978-Treated Wastewater
Cr 47 0.01-0.07 0.06+0.10 0.26
Cu 28 0.005 - 0.055 0.016 +0.010 0.04
Ni 47 0.10 - 0.92 0.20 £0.14 0.48
Zn 47 . 0.08 - 2.35 0.23 +0.34 0.91
Fe 21 0.26 - 1.1 0.49 +0.18 0.85
Raw Waste
Cr 5 32.0 - 72.0
Cu 5 0.08 - 0.45
Ni 5 1 .65 - 20.0
Zn 5 33.2 - 32.0
Fe 5 10.0 - 95.0
268
-------
TABLE VI1-19
PRECIPITATION-SETTLING-FILTRATION (LS&F) PERFORMANCE
Plant B
Parameters
No Pts. Range mq/1
For 1979-Treated Wastewater
Mean +
std. dev.
Mean + 2
std. dev.
Cr
175
0.0
-
0.40
0. 068
+0.075
0. 22
Cu
176
0.0
-
0. 22
0,024
+0.021
0.07
Ni
175
0.01
-
1 .49
0.219
+0.234
0.69
Zn
175
0.01
-
0.66
0.054
+0.064
0.18
Fe
174
0.01
-
2.40
0.303
+0.398
1.10
TSS
2
1 .00
-
1 .00
For
1978-Treated Wastewater
Cr
144
0.0
—
0.70
0. 059
+0.088
0.24
Cu
143
0.0
-
0.23
0.017
+0.020
0.06
Ni
143
0.0
-
1 .03
0. 147
+0.142
0.43
Zn
131
0.0
-
0.24
0. 037
+0.034
0.11
Fe
144
0.0
—
1 .76
0 . 200
+0.223
0.47
Total 1974-
1979-Treated
Wastewater
Cr
1288
0.0
.
0.56
0.038
+0.055
0.15
Cu
1290
0.0
-
0.23
0.01 1
+0.016
0.04
Ni
1287
0.0 ,
-
1 .88
0. 184
+0.211
0.60
Zn
1 273
0.0
—
0. 66
0. 035
+0.045
0.13
Fe
1287
0.0
—
3.15
0.402
+0.509
1 .42
Raw
Waste
Cr
3
2. 80
9.15
5.90
Cu
3
0.09
-
0.27
0.17
Ni
3
1 .61
-
4.89
3.33
Zn
2
2.35
-
3.39
Fe
3
3.13
35.9
22.4
TSS
2
177
-466.
269
-------
TABLE VI1-20
PRECIPITATION-SETTLING-FILTRATION (LS&F) PERFORMANCE
Plant C
For Treated Wastewater Mean + Mean + 2
Parameters No Pts. Range mq/1 std. dev. std. dev.
For Treated Wastewater
Cd 103 0.010 - 0.500 0.049 +0.049 0.147
Zn 103 0.039 - 0.899 0.290 +0.131 0.552
TSS 103 0.100-5.00 1.244 +1.043 3.33
pH 103 7.1 -7.9 9.2*
For Untreated Wastewater
Cd 103 0.039 - 2.319 0.542 +0.381 1.304
Zn 103 0.949 -29.8 11.009 +6.933 24.956
Fe 3 0.107 - 0.46 0.255
TSS 103 0.80 -19.6 5.616+2.896 11.408
pH 103 6.8 - 8.2 7.6*
* pH value is median of 103 values.
270
-------
TABLE VI1-21
Summary of Treatment Effectiveness
(mg/1)
Pollutant
Parameter
L&S
Technology
System
LS&F
Technology
System
Mean
One
Day
Max.
Ten
Day
Avq.
Thirty
Day
Avq.
Mean
One
Day
Max.
Ten
Day
Avq.
Thirty
Day
Avq.
114 Sb
115 As
117 Be
0.70
0.51
0.30
2.87
2.09
1 .23
1 . 28
0. 86
0.51
1.14
0.83
0.49
0.47
0.34
0.20
1 . 93
1 .39
0.82
0.86
0. 57
0.34
0.76
0.55
0.32
118 Cd
119 Cr
120 Cu
0.079
0.080
0.58
0.32
0.42
1 . 90
0.15
0.17
1 . 00
0.13
0.12
0.73
0.049
0.07
0.39
0.20
0.37
1 . 28
0.08
0.15
0.61
0. 08
0.10
0.49
121 CN
122 Pb
123 Hg
0.07
0.12
0.06
0.29
0.15
0.25
0.12
0.13
0.10
0.1 1
0.12
0.1 0
0.047
0.08
0.036
0.20
0.10
0.15
0.08
0.09
0.06
0.08
0.08
0.06
124 Ni
125 Se
126 Ag
0.57
0.30
0.10
1 .41
1 .23
0.41
1 . 00
0.55
0.17
0.75
0.49
0.16
0.22
0.20
0.07
0.55
0.82
0.29
0.37
0.37
0.12
0.29
0.33
0.10
127 T1
128 Zn
A1
0.50
0.30
1.11
2.05
1 .33
4.55
0.84
0.56
1 .86
0.81
0.41
1 . 80
0. 34
0.23
0.74
1 .40
1 .02
3. 03
0.57
0.42
1 .24
0. 55
0.31
1 .20
Co
F
Fe
0.05
14.5
0.41
0.21
59. 5
1 .23
0.09
26.4
0.63
0.08
23. 5
0.51
0.034
9.67
0.28
0.14
39.7
1 .23
0.07
17.6
0.63
0.06
15.7
0.51
Mn
P
0.21
4.08
0 .43
16.7
0.34
6.83
0.27
6.60
0.14
2.72
0.30
11.2
0.23
4.6
0.19
4.4
O&G
TSS
12.0
20.0
41 .0
12.0
20.0
10.0
15.5
2.6
10.0
15.0
10.0
12.0
10.0
10.0
271
-------
TABLE V1X-22
TREATABILITY HATING OF PRIORITY POLLUTANTS
UTILIZING CARBON ADSORPTION
Priority Pollutant
•Removal
Rating
Priority Pollutant
~Removal
Rating
1.
acenaphthene
H
49.
trichlorofluoromethane
M
2.
acrolein
L
50.
dichlorodifluoromethane
L
3.
acrylonitrile
L
51.
chlorodibromomethane
H
4.
benzene
M
52.
hexachlorobutadiene
H
5.
benzidine
B
53.
hexachlorocyclopentadiene
H
6.
carbon tetrachloride
M
54.
isophorone
a
(tetrachloroaethane)
55.
naphthalene
a
7.
chlorobenzene
H
56.
nitrobenzene
a
8.
1,2,3-trichlorobenzene
H
57.
2-nitrophenol
a
9.
hexachlorobenzene
H
58.
4-nitrophenol
a
10.
1,2-dichloroethane
M
59.
2,4-dinitrophenol
a
11.
1,1,1-trichloroethane
H
60.
4,6-dinitro-o-cresol
a
12.
hexachloroethane
H
61.
N-nitrosodimethylamine
H
13.
1,1-dichloroethane
H
62.
N-nitrosodiphenylamine
a
14.
1,1,2-trichloroethane
M
63.
N-nitrosodi-n-propylamine
M
15.
1,1,2,2-totrachlorethane
H
64.
pentachlorophenol
a
16.
chloroethane
L
65.
phenol
M
17.
bis(chloromethy1) ether
-
66.
bis(2-ethylhexy1)phthalate
a
IS.
bis(2-chloroefchyl) ether
M
67.
butyl benzyl phthalate
a
19.
2-chloroethylvinyl ether
L
68.
di-n-butyl phthalate
a
( mixed)
69.
di-n-octyl phthalate
H
20.
2-chloronaphthalene
H
70.
diethyl phthalate
a
21.
2,4,6-trichlorophenol
H
71.
dimethyl phthalate
a
22.
parachloroaeta cresol
a
72.
1,2-benzanthracene
a
23.
chloroform (trichlorome-thane)
L
(benzo(a)anthracene)
24.
2-chlorophenol
H
73.
benzo(a)pyrene (3,4-benzo-
a
25.
1,2-dichlorobenzene
a
pyrene)
26.
1,3-dichlorobenzene
a
74.
3,4-benzofluoranthene
a
27.
1,4-dichlorobenzene
a
(benzo(b)fluoranthene)
2B.
3,3*-dichlorobenzidine
a
75.
11,12-benzofluoranthene
a
29.
1, l-di chloroethylens
L
(benzo (1c) f luoranthene)
30.
1,2-trans-di chloroe thyl<»ne
L
76.
chrysene
a
31.
2,4-dichlorophenol
a
77.
acenaphthylene
a
32.
1,2-dichloropropane
H
78.
anthracene
a
33.
1,2-dichloropropylene
M
79.
l,12~benzoperylene (benzo
a
(1,3-dichloropropene)
(ghi)-perylene)
34.
2,4-dimethylphenol
H
80.
fluorene
a
35.
2,4-dinitrotoluone
a
81.
phenanthrene
a
36.
2,6-dinitrotoluene
a
82.
1,2,3,6-dibenzanthracene
a
37.
1,2-diphenylhydrazine
a
(dibenzo(a,h) anthracene)
38-
ethylbenzene
M
83.
indeno (1,2,3-cd) pyrene
a
39.
flooranthene
H
(2,3~o-phenylene pyrene)
40.
4-chlorophenyl phenyl ether
a
84.
pyrene
-
41.
4-bronophenyl phenyl ether
a
85.
tetrachloroethylene
M
42.
bis(2-chloroisopropyl)ether
M
86.
toluene
H
43.
bis(2-chlorcethoxy)methane
K
87.
trichloroethylene
L
44.
methylene chloride
L
88.
vinyl chloride
L
(dichloromethane)
{chloroethylene)
45.
methyl chloride (chlororaethane)
L
106.
PCB-1242 (Aroclor 1242)
a
46.
methyl bromide (bromometehane)
L
107.
PCB-1254 (Aroclor 1254)
a
47.
broooform (tribromomethnne)
a
108.
PCB-1221 (Aroclor 1221)
a
48.
dichlorobromnmethane
M
109.
PCB-1332 (Aroclor 1232)
a
110.
PCS—1248 (Aroclor 1248)
a
111.
PCB-1260 (Aroclor 1260)
H
112.
PCB-1016 (Aroclor 1016)
a
•Tlote Explanation of Removal Ratings
Category H (high removal)
adsorbs at levels > 100 mg/g carbon at Cr » 10 mg/1
adsorbs at levels >100 mg/g carbon at Cf < 1.0 mg/1
Category M (moderate removal)
adsorbs at levels i100 mg/g carbon at C
10 mg/1
1.0 mg/1
adsorbs at levels S 100 mg/g carbon at C
Category L (low removal)
adsorbs at levels < 100 mg/g carbon at Cc " 10 mg/1
adsorbs at levels < 10 mg/g carbon at Ct <1.0 mg/1
Cj " final concentrations of priority pollutant at equilibrium
272
-------
TABLE VII - 23
CLASSES OF ORGANIC COMPOUNDS ADSORBED (XT CARBON
Organic Chemical Class
Arcraatic Hydrocarbons
Polynuclear Arcmatics
Chlorinated Arcnatics
Fhenolics
Chorinated Phenolics
*High MolecuLar Weight Aliphatic and
Bramdi Chain hydrocarbons
Golorinated 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 polyphenols
trichloropfaanol, pentachloro-
gasoline, kerosine
carbon tetrachloride,
perchloroethylene
tar acids, benzoic acid
aniline, toluene diamine
hydroquinone, polyethylene
glycol
alkyl benzene sulfonates
methylene blue, indigo carmine
* High Molecular Weight includes compounds in the broad range of from
4 to 20 carbon atoms
273
-------
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
Parameter
Table VI1-25
Ion Exchange Performance
Plant A
Plant B
All Values mg/1
Prior To
Purifi-
cation
After
Purifi-
cation
Prior To
Purifi-
cation
After
Purifi-
cation
A1
5.6
0. 20
-
-
Cd
5.7
0. 00
-
-
Cr+3
3.1
0. 01
-
-
Cr+6
7.1
0.01
-
-
Cu
4.5
0. 09
43. 0
0.10
CN
9.8
0. 04
3.40
0.09
Au
-
-
2.30
0.10
Fe
7.4
•—i
o
o
-
-
Pb
—
-
1 .70
0.01
Mn
4.4
0. 00
-
-
Ni
6.2
0. 00
1.60
0.01
Ag
1.5
0.00
9.10
0.01
S04
—
-
210.00
2.00
Sn
1.7
0.00
1.10
0.10
Zn *
14.8
0. 40
-
-
274
-------
Table VI1-26
MEMBRANE FILTRATION SYSTEM EFFLUENT
Specific
Metal
A1
Cr, (+6)
Cr (T)
Cu
Fe
Pb
CN .
Ni
Zn
TSS
Advantages and Limitations.
Manufacturers
Plant
1 9066
Plant
31022
Guarantee
In
Out
In
Out
0.5
_ —_
___
0. 02
0.46
0.01
5.25
<0.005
0. 03
4.13
0.018
98.4
0. 057
0.1
18.8
0.043
8.00
0. 222
0.1
288
0.3
21.1
0. 263
0.05
0.652
0.01
0.288
0.01
0.02
<0.005
<0.005
<0.005
<0.005
0.1
9. 56
0.017
1 94
0. 352
0.1
2, 09
0. 04.6
5.00
0. 051
632
0.1
13.0
8.0
Pollutant
(mg/1)
Cr+6
Cu
CN
Pb
Hg
Ni
Ag
Sb
Zn
Table VII-27
PEAT ADSORPTION PERFORMANCE
In
35,000
250
36.0
20.0
1.0
...... .. 2 . 5
1.0
2.5
1.5
Table VII-28
ULTRAFILTRATION PERFORMANCE
Out
0.04
0.24
0.7
0.025
0.02
0. 07
0.05
0.9
0.25
Predicted
Performance
0.05
0.20
0. 30
0.05
0.02
0.40
0. 1 0
1 .0
Parameter
Oil (freon extractable)
COD
TSS
Total Solids
Feed (mq/1)
1230
8920
1380
2900
Permeate (mq/1)
4
148
13
296
275
-------
10
10
10
10
Cd (OH)
10'
10'
cu (oh)2
to-
cos
ZnS
CdS
10'
PfaS
10'
10'
10
'82
3
4
2
5
7
8
9
10
11
12
13
pH
FIGURE VII-1. COMPARATIVE SOLUBILITIES OF METAL HYDROXIDES
AND SULFIPE AS A FUNCTION OF pH
276
-------
0.40
0.30
CAUSTIC SODA
Q 0.20
SOOA ASH AND
CAUSTIC SODA
0.10
LIME
8.0
8.5
9.0
9.5
10.0
10.5
PH
FIGURE VI1-2. LEAD SOLUBILITY IN THREE ALKALIES
277
-------
to
-J
CO
0
2
Z
0
H
<
a
H
Z
U
O
z
0
u
o
z
N
h
z
u
3
-I
lL
1L
111
•
O
-
o
-
O
<
u
>
¦
O
O
o o
O
oo
° (
I n o
' o °
8°
—2o—o—(
o
» 0-
o
MINIMUM EFFLUENT pH
FIGURE VI1-3. EFFLUENT ZINC CONCENTRATION VS. MINIMUM EFFLUENT pH
-------
1.0
en
E
5 0.1
E
to
Tl
0.01
Data points with a raw waste concentration
less than 0.1 mg/l were not included in
treatment effectiveness calculations.
0.1 1.0
Cadmium Raw Waste Concentration (mg/l)
10
100
(Number of observations = 2)
FIGURE VII — 4
HYDROXIDE PRECIPITATION SEDIMENTATION EFFECTIVENESS
CADMIUM
-------
10
to
CO
o
cn
j:
e
o
c
03
U
e
0
u
-M
e
01
3
E
LLI
¦a
ai
+-»
S3
<0
E
3
u
1.0
0.1
0.01
•
(
/7)
>
(
)
a
%
A
•)
©
(
)
t
i
D
b
(
)
l!
t
©
©
A
a
_,../a, rt
*
•>
0.1
1.0 10
Chromium Raw Waste Concentration (mg/l)
100 1000
(Number of observations = 26)
FIGURE VII-5
HYDROXIDE PRECIPITATION SEDIMENTATION EFFECTIVENESS
CHROMIUM
-------
1.0 10 100 1000
Copper Raw Waste Concentration (mg/l)
(Number of observations = 19)
FIGURE VII — 6
HYDROXIDE PRECIPITATION SEDIMENTATION EFFECTIVENESS
COPPER
-------
to
CO
to
cn
.E
e
o
a
o
c
u
0)
E
H-
¦S3
s
0.1
8.01
0.001
(
®
> ®
<:
I
>
©
Euaa
iixi.
J
i
0.01
0.1
1.0
Lead Raw Waste Concentration (mg/l)
10 100
(Number of observations = 23)
FIGURE VII-7
HYDROXIDE PRECIPITATION SEDIMENTATION EFFECTIVENESS
LEAD
-------
10
o>
J. =¦
s Oi
2 S
£
*-»
es
ou
u
c
o
(U M
W C
0 e
O 0>
u
4- C
s o
as o
St; e
to uj §
CO T3 C
(jj a> H-
ts
3 -s
f— s
E £
=3 |_
C _
1 J
3 U
< s
x ©
.01
X
X
<•
(
)
S
©
X
e
'
12*
£
©
at
a
0.1
1.0 10
© Nickel Raw Waste Concentration (mg/l)
x Aluminum Raw Waste Concentration (mg/l)
100
(Number of observations = 13)
(Number of observations = 5)
1000
FIGURE VII- 8
HYDROXIDE PRECIPITATION SEDIMENTATION EFFECTIVENESS
NICKEL AND ALUMINUM
-------
10
to
CO
O)
E
3 1.0
b
o
•J3
E
¦W
E
O)
U
B
O
u
€
a
s
£
LU
U
e
M
0.1
n\
<3
*©
9
14
3
>
©
©
<•>
I
{
P
©
(i
/r\
»
|f
h
©
9
©
©
©
9
©
©
0.1
1.0
10
Zinc Raw Waste Concentration (rng/l)
100
1000
(Number of observations = 29)
FIGURE VII-9
HYDROXIDE PRECIPITATION SEDIMENTATION EFFECTIVENESS
ZINC
-------
10
to
ca
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1.0
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+3
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0.1
1.0
10
Iron Raw Waste Concentration (mg/l)
100 1000
(Number of observations = 29)
FIGURE VII-10
HYDROXIDE PRECIPITATION SEDIMENTATION EFFECTIVENESS
IRON
-------
1.0
to
CO
-------
1000
N)
oo
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100
o
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1.0
10
100
TSS Raw Waste Concentration (mg/1)
1000 10,000
(Number of observations = 46)
FIGURE VII-12
HYDROXIDE PRECIPITATION SEDIMENTATION EFFECTIVENESS
TSS
-------
SULFURIC SULFUR
ACID DIOXIDE
LIME OR CAUSTIC
pH CONTROLLER
"O
ORP CONTROLLER
RAW WASTE
(HEXAVALENT CHROMIUM)
(TRIVALENT CHROMIUM)
pH CONTROLLER
REACTION TANK
PRECIPITATION TANK
TO CLARIFIER
(CHROMIUM
HYDROXIDE)
FIGURE V1I-13. HEXAVALENT CHROMIUM REDUCTION WITH SULFUR DIOXIDE
-------
INFLUENT
ALUM
EFFLUENT
WATEJ?
LEVEL
POLYMER
STORED
BACKWASH
WATER
PH
§33
THREE WAY VALVE
FILTER
BACKWASH-
FILTER
COMPARTMENT
FILTER
MEDIA
-> U
E <
COAL
SAND'
COLLECTION CHAMBER
SUMP
DRAIN
FIGURE VH-14. GRANULAR BED FILTRATION
289
-------
PERFORATED
BACKING PLATE
FABRIC
FILTER MEDIUM
SOLID
RECTANGULAR
END PLATE
r
1AI
INLET
SLUDGE
FABRIC
FILTER MEDIUM
ENTRAPPED SOLIDS
PLATES AND FRAMES ARE
PRESSED TOGETHER DURING
FILTRATION CYCLE
RECTANGULAR
METAL PLATE
FILTERED LIQUID OUTLET
RECTANGULAR FRAME
FIGURE VII-15. PRESSURE FILTRATION
290
-------
SEDIMENTATION BASIN
INLET ZONE
INLET LIQUID
BAFFLES TO MAINTAIN
QUIESCENT CONDITIONS
OUTLET ZONE
' * SETTLING PARTICLE
« • ' . '— . TRAJECTORY y °U
• • • •*"-«**. • . i . • • A
•••« • • • •" —^ .» •. • ••
. • • •• • - y i* y. V*' > , r ¦" i
rn • • •> y 1 f i/*i ' » ¦ I • •! a •
1 t i y,"n f * * •,* fV*
IT )* *' .* ?' : i'iI *-Hzrr?r\ . >< '
OUTLET LIQUID
BELT-TYPE SOLIDS COLLECTION
MECHANISM
SETTLED PARTICLES COLLECTED
AND PERIODICALLY REMOVED
CIRCULAR CLARIFIER
SETTLING ZONE.
INLET LIQUID
CIRCULAR BAFFLE
• • •
INLET ZONE
i v*** • * '/ •.*.
VkIV.''•••.TV ¦.Vv
-------
BACKWASH
WASTE WATER'
INFLUENT —
DISTRIBUTOR
.CEMENT CARBON
WASH WATER
SURFACE WASH
MANIFOLD
CARBON BED
CARBON REMOVAL FORT
TREATED WATER
BACKWASH
SUI
FIGURE VI1-17. ACTIVATED CARBON ADSORPTION COLUMN
292
-------
LIQUID
OUTLET
CONVEYOR DRIVE
DRYING
ZONE
LIQUID ZONE
BOWL DRIVE
SLUDGE
INLET
SLUDGE
DISCHARGE
CYCLOGEAR
CONVEYOR
BOWL
REGULATING
RING
IMPELLER
FIGURE VII-18. CENTRIFUGATION
293
-------
RAW WASTE
CAUSTIC
SODA
PH
CONTROLLER
ORP CONTROLLERS
CAUSTIC
SODA
pH
CONTROLLER
WATER
CONTAINING
CYANATE
TREATED
WASTE
do
CIRCULATING
PUMP ~~7
CHLORINE
REACTION TANK
REACTION TANK
CHLORINATOR
FIGURE VII-19. TREATMENT OF CYANIDE WASTE BY ALKALINE CHLORINATION
-------
TREATED
WASTE
OZONE
REACTION
TANK
CONTROLS
J OZONE
GENERATOR
CD
DRY AIR
PH
RAW WASTE
FIGURE VI1-20. TYPICAL OZONE PLANT FOR WASTE TREATMENT
295
-------
I
MIXER
EXHAUST
GAS
TEMPERATURE
CONTROL
PH MONITORING
TEMPERATURE
CONTROL
WASTEWATER
FEED TANK
3
THIRD
STAGE
PUMP
PH MONITORING
TEMPERATURE
CONTROL
PH MONITORING
OZONE
GENERATOR
TREATED WATER
FIGURE Vll-21. UV/OZONATION
296
-------
EXHAUST
WATER VAPOR
PACKED TOWER.
EVAPORATOR
WASTEWATER
Ill
EVAPORATOR
STEAM
VAPOR-LIQUID
~~~\ MIXTURE /
/
SEPARATOR
CONDENSER
1
HEAT
EXCHANGER
STEAM
STEAM
CONDENSATE
CONCENTRATE
ATMOSPHERIC EVAPORATOR
.STEAM
CONDENSATE
WASTEWATER
RETURN
WATER VAPOR
T
COOLING
WATER
1
~a
.CONDENSATE
VACUUM PUMP
-CONCENTRATE
ro
CLIMBING FILM EVAPORATOR
VAPOR
VACUUM LINE
HOT VAPOR
WATER
WATER
CONDEN-
SATE
:««««««<
WATER
STEAM
Z2227
CONDENSATE
WASTEWATER
CONDENSATE
VACUUM PUMP
EXHAUST
ACCUMULATOR
CONDENSATE
FOR REUSE
CONCENTRATE
SUBMERGED TUBE EVAPORATOR
STEAM
CONDENSATE
CONCENTRATE FOR REUSE
DOUBLE-EFFECT EVAPORATOR
FIGURE Vll-22. TYPES OF EVAPORATION EQUIPMENT
-------
OILY WATER
INFLUENT
WATER
DISCHARGE
OVERFLOW
SHUTOFF
VALVE
DRIVEN
AIR IN
BACK PRESS
VALVE
f,
FINES & OIL
OUT
HOLDING
TANK
WATER I
EXCESS
AIR OUT
LEVEL
CONTROLLER
TO SLUDGE
TANK*
FIGURE VIl-23. DISSOLVED AIR FLOTATION
298
-------
RAKE ARM
BLADE
•COUNTERFLOW
INFLUENT WELL
CONDUIT
TO MOTOR
DRIVE UNIT
INFLUENT — fc. I
WALKWAY
CONDUIT TO
OVERLOAD
ALARM
OVERLOAD ALARM
EFFLUENT WEIR
DIRECTION OF ROTATION
EFFLUENT PIPE
EFFLUENT CHANNEL
PLAN
TURNTABLE
BASE
HANDRAIL
DRIVE
WEIR
WATER LEVEL
CENTER COLUMN
— CENTER CAGE
INFLUENT
FEED WELL
SQUEEGEE
STILTS
SLUDGE PIPE
CENTER SCRAPER
FIGURE Vll-24. GRAVITY THICKENING
299
-------
WASTE WATER CONTAINING
DISSOLVED METALS OR
OTHER IONS
REGENERANT
SOLUTION
DIVERTER VALVE
DISTRIBUTOR
EXCHANGE,
RESIN 1
•SUPPORT
DIVERTER VALVE
METAL-FREE WATER
FOR REUSE OR DISCHARGE
REGENERANT TO REUSE,
TREATMENT. OR DISPOSAL
FIGURE VII-25. ION EXCHANGE WITH REGENERATION
300
-------
® MACROMOLECULES
AND SOLIDS
MEMBRANE
Ap» 450 PSlI
WATER
MEMBRANE CROSS SECTION,
IN TUBULAR, HOLLOW FIBER,
OR SPIRAL-WOUND CONFIGURATION
PERMEATE (WATER)
O «
CONCENTRATE
(SALTS)
FEED
O SALTS OR SOLIDS
• WATER MOLECULES
FIGURE Vll-26. SIMPLIFIED REVERSE OSMOSIS SCHEMATIC
301
-------
PERMEATE
TUBE
PER
meate
feed flow
O-RING —>
ADHESIVE BOUND
SPIRAL. MODULE
feed
FUOW
CONCENTRATE
FLOW
BACKING MATERIAL.
¦MESH SPACER
•MEMBRANE
SPIRAL MEMBRANE MODULE
POROUS SUPPORT TUBE
WITH MEMBRANE
%*.¦*
.* I**BRACKISH
WATER
FEED FLOW
PRODUCT WATER
PERMEATE FLOW
'GOT
O 9 • ;
qoA 0 ©0 0 0 oq
^ On o dVoeo D ° a o t
BRINE
CONCENTRATE
FLOW
PRODUCT WATER
TUBULAR REVERSE OSMOSIS MODULE
SNAP
RING
"O" RING
SEAL
OPEN ENDS
OF FIBERS
f— EPOXY
I TUBE SHEET
POROUS
BACK-UP DISC
FIBER
FLOW SCREEN
L
SNAP
RING
O" RING
SEAL
1BER
END PLATE
POROUS FEED
DISTRIBUTOR TUBE —1
PERMEATE
END PLATE
HOLLOW FIBER MODULE
FIGURE VU-27. REVERSE OSMOSIS MEMBRANE CONFIGURATIONS
302
-------
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PLAN
S-IN. FINE SAND
3-IN. COARSE SAND
3-IN. FINE GRAVEL
3-IN. MEDIUM GRAVEL
3 TO 6 IN. COARSE GRAVEL
6-IN. CI PIPE
PLANK
WALK
PIPE COLUMN FOR
GLASS-OVER
3-IN. MEDIUM GRAVEL
6-IN. UNDERDRAIN LAID-
WITH OPEN JOINTS
§g§T!PN A-A
FIGURE VU-2§, SLUDGE DRYING BED
-------
Ul.TR A FILTRATION
MACROMOLECULES JS
• •
• m
P « 10-50 PSI
MEMBRANE
PERMEATE
• i
-MEMBRANE
• •
• • •
• •
• •
O* • • *o • o • • .*o
• °. • . o • . .
F"° O . °»
3 • r> • o _
© • ~
> O ' CONCENTRATE
• • " • O • ^ • Q • • *o * •
• I-
° .o
O OIL PARTICLES
• DISSOLVED SALTS AND LOW-MOLECULAR-WEIGHT ORGANICS
FIGURE VI1-29. SIMPLIFIED ULTRAFILTRATION FLOW SCHEMATIC
304
-------
FABRIC OF? WIRE
FILTER MEDIA
STRETCHED OVER
REVOLVING DRUM
STEEL
CYLINDRICAL
FRAME
TRUNNION
VACUUM
SOURCE
LIQUID FORCE
THROUGH
MEDIA BY ^
MEANS OF
VACUUM \y
INLET LIQUID
TO BE
FILTERED
FIGURE VI1-30. VACUUM FILTRATION
305
-------
Intentionally Blank Page
-------
SECTION VIII
COST OF WASTE WATER CONTROL AND TREATMENT
This section presents estimates of the costs of implementing the
major wastewater treatment and control technologies descrived 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
determining the probable economic impact on the coil coating
category of regulation at different pollutant discharge levels.
In addition, this section addresses non-water quality
environmental impacts of wastewater treatment and control
alternatives, including air pollution, noise pollution, solid
wastes, and energy requirements.
In developing the cost estimates presented in this section, EPA
selected specific wastewater treatment technologies and in-
process control techniques from among those discussed in Section
VII and combined them in wastewater treatment and control systems
appropriate for each subcategory. Investment and annual costs
for each system were estimated based on wastewater flow rates and
raw waste characteristics for each subcategory as presented in
Section V.
COST ESTIMATION METHODOLOGY
Cost estimation is accomplished using a computer program which
accepts inputs specifying the treatment system to be estimated,
chemical characteristics of the raw waste streams treated, flow
rates and operating schedules. The program accesses models for
specific treatment components which relate component investment
and operating costs, materials and energy requirements, and
effluent stream characteristics to influent flow rates and stream
characteristics. Component models are exercised sequentially as
the components are encountered in the system to determine
chemical characteristics and flow rates at each point. Component
investment and annual costs are also determined and used in the
computation of total system costs. Mass balance calculations are
used to determine the characteristics of combined streams
resulting from mixing two or more streams and to determine the
volume of sludges or liquid wastes resulting from treatment
307
-------
operations such as sedimentation,, filtration, flotation, and oil
separation.
Cost estimates are broken down into several distinct elements:
total investment and annual costs, operation and maintenance
costs, energy costs, depreciation, and annual costs of capital.
The cost estimation program incorporates provisions for
adjustment of all costs to a common dollar base on the basis of
economic indices appropriate to capital equipment and operating
supplies. January 1978 dollar base has been used throughout this
document as the basing point requiring least adjustment of the
data supplied. Labor and ¦ electric power costs are input
variables appropriate to the dollar base year for cost estimates.
Cost Estimation Input Data
The waste treatment system descriptions input to the computer
cost estimation program include both a specification of the waste
treatment components included and a definition of their
interconnections. For some components, retention times or other
operating parameters are specified in the input, while for
others, such as reagent mix tanks and clarifiers, these
parameters are specified within the program based on prevailing
design practice in industrial waste treatment. The waste
treatment system descriptions may include multiple raw waste
stream inputs and multiple treatment trains. For example,
cyanide bearing waste streams are segregated and treated by
cyanide precipitation after chromium reduction and then given
chemical precipitation treatment with the remaining process
wastewater.
The specific treatment systems selected for cost estimation for
each subcategory were based on an examination of raw waste
characteristics, consideration of manufacturing processes, and an
evaluation of available treatment technologies discussed in
Section VII. The rationale for selection of these systems is
presented in Sections IX through XII which also discusses their
pollution removal effectiveness.
The input data set also includes chemical characteristics for
each raw waste stream (specified as input to the treatment
systems for which costs are to be estimated). These
characteristics are derived from the raw waste sampling data
presented in Section V. The pollutant parameters which are
presently accepted as input by the cost estimation program appear
in Table VIII-1 (page 340). The values of these parameters are
used in determining materials consumption, sludge volumes,
treatment component sizes and effluent characteristics. The list
of input parameters is expanded periodically as additional
308
-------
pollutants are found to be significant in waste streams from
industries under study and as additional treatment technology
cost and performance data become available. For the coil coating
category, individual subcategories commonly encompass a number of
different waste streams which are present to varying degrees at
different facilities. The raw waste characteristics shown as
input to waste treatment represent a mix of these streams
including all significant pollutants generated in the subcategory
and do not correspond precisely to process wastewater at any
existing facility. The process by which these raw wastes were
defined is explained in Section V.
The final input data set comprises raw waste flow rates for each
input stream for a "normal" plant in each subcategory. The
"normal" plant is defined as a plant having the mean prediction
level for the subcategory and equivalent flow and wastewater
characteristics. The normal plant is used to indicate the
encountered at existing facilities for each coil coating
subcategory and to indicate the treatment costs which would be
incurred in the implementation of each control and treatment
option considered. In addition, data corresponding to the flow
rates and equipment in place reported by each plant in the
category were used to provide cost estimates for use in economic
impact analysis.
System Cost Computation
Figure VIII-1 (page 359) presents a simplified flow chart of the
computer cost estimation system. This is useful in
conceptualization of the estimation of wastewater treatment and
control costs from the input data described above. In the
computation, raw waste characteristics and flow rates for the
first case are used as input to the model for the first treatment
technology specified in the system definition. This model is
used to determine the sige and cost of the component, materials
and energy consumed in its operation, and the volume and
characteristics of the stream(s) discharged from it. These
stream characteristics are then used as input to the next
component(s) encountered in the system definition. This
procedure is continued until the complete system costs and the
volume and characteristics of the final effluent stream(s) and
sludge or concentrated oil wastes have been determined. In
addition to treatment components, the system may include mixers
in which two streams are combined, and splitters in which part of
a • stream is directed to another destination. These elements are
handled by mass balance calculations and allow cost estimation
for specific treatment of segregated process wastes such as
oxidation of cyanide bearing wastes prior to combination with
309
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other process wastes for further treatment, and representation of
partial recycle of wastewater.
As an example of this computation process, the sequence of
calculations involved in the development of cost estimates for a
simple treatment system including chemical precipitation,
sedimentation, and sludge dewatering are described. Initially,
input specifications for the treatment system are read to set up
the sequence of computations. The subroutine addressing chemical
precipitation and clarification is then accessed. The sizes of
the mixing tank and clarification are calculated based on the raw
waste flow rate to provide 45 minute retention in the mix tank
and 4 hour retention with 15.0 gph/ft2 surface loading in the
clarifier. Based on these sizes, investment and annual costs for
labor, supplies for the mixing tank and clarifier including
mixers, clarifier rakes and other directly related equipment are
determined. Fixed investment costs are then added to account for
sludge pumps, controls and reagent feed systems.
Based on the input raw waste concentrations and flow rates, the
reagent additions (lime, alum, and polyelectrolyte) are
calculated to provide fixed concentrations of alum and poly-
electrolyte and 10 percent excess lime over that required for
stoichiometric reaction with the acidity and metals present in
the waste stream. Costs are calculated for these materials, and
the suspended solids and flow leaving the mixing tank and
entering the clarifier are increased to reflect the lime solids
added and precipitates formed. These modified stream character-
istics are then used with performance algorithms for the
clarifier (as discussed in Section VII) to determine
concentrations of each pollutant in the clarifier effluent
stream. By mass balance, the amount of each pollutant in the
clarifier sludge may be determined. The volume of the sludge
stream is determined by the concentration of TSS, which is fixed
at 4 to 5 percent based on general operating experience;
concentrations of other pollutants in the sludge stream are
determined from their masses and the volume of the stream.
The subroutine describing vacuum filtration is then called, and
the mass of suspended solids in the clarifier sludge stream is
used to determine the size and investment cost of the vacuum
filtration unit. Operating hours for the filter are calculated
from the flow rate and TSS concentration and are used to
determine manhours required for operation. Maintenance labor
requirements are added as a fixed additional cost.
The sludge flow rate and TSS content are then used to determine
costs of materials and supplies for vacuum filter operation
including iron and alum added as filter aids, and the electrical
31 0
-------
power costs for operation. Finally, the vacuum filter
performance algorithms are used to determine the volume and
characteristics of the vacuum filter sludge and filtrate, and the
costs of contract disposal of the sludge are calculated. The
recycle of vacuum filter filtrate to the chemical precipitation-
clarification system is not reflected in the calculations due to
the difficulty of iterative solution of such loops and the
general observation that the contributions of such streams to the
total flow and pollutant levels are in practice, negligibly
small. Such minor contributions are accounted for in the 20
percent excess capacity provided in most components.
The costs determined for all components of the system are summed
and subsidiary costs are added to provide output specifying total
investment and annual costs for the system and annual costs for
capital, depreciation, operation and maintenance, and energy.
Costs for specific system components and the characteristics of
all streams in the system may also be specified as output from
the program.
After proposal numerous public comments were received about the
Agency's porcelain enameling costs and costing factors. Because
the same methodology and costing factors were proposed for both
coil coating and porcelain enameling, the Agency considered
comments about porcelain enameling costs to be equally valid for
coil coating. Review of data and consideration of information
provided in the comments resulted in a number of changes that
increased substantially the Agency's cost estimates. These
changes are summarized here.
1. The hydraulic surface loading of clarifier was reduced from
33.3 to 15.0 gal/hr/ft2.
2.. The TSS concentration in clarifier sludge stream was
corrected to read 4.5 percent.
3. The excess capacity factor for flocculator, settling tanks,
and sludge pumps of clarifier was increased from 1.2 to 1.4.
4. Intercomponent piping, instrumentation, and contingency
costs were added to list of subsidiary costs.
5. The wastewater sampling frequency chart was corrected to
show weekly rather than monthly sampling at the third size
level (189, 251-378, 500 lb/day).
6. Instrumentation costs are now assigned a fixed value of
$25,000 for continuous treatment, zero cost for batch
treatment.
311
-------
7. Engineering costs were increased and now range from 10.6
percent of total investment for a $650,000 plant to 22
percent for a $55,000 plant.
8. Legal, fiscal, and administrative costs were increased and
now range from 1.6 percent of total plant investment costs
for a $650,000 plant, to 3.7 percent for a $55,000 plant.
9. Interest for construction costs was increased from 10
percent to 16 percent.
Treatment Component Models
The cost estimation program presently incorporates subroutines
providing cost and performance calculations for the treatment
technologies identified in Section VII. These subroutines have
been developed over a period of years from the best available
information, including on-site observations of treatment system
performance, costs and construction practices at a large number
of industrial facilities, published data, and information
obtained from suppliers of wastewater treatment equipment. The
subroutines are modified and new subroutines added as
improvements in treatment technologies become available, and as
additional treatment technologies are required for the industrial
wastewater streams under study. Specific discussion of each of
the treatment component models used in costing wastewater
treatment and control systems for the coil coating category is
presented later in this section where cost estimation is
addressed, and in Section VII where performance aspects were
developed.
In general terms, cost estimation is provided by mathematical
relationships in each subroutine approximating observed
correlations between component costs and the most significant
operational parameters such as water flow rate, retention times,
and pollutant concentrations. In general, flow rate is the
primary determinant of investment costs and of most annual costs
with the exception of materials costs. In some cases, however,
as discussed for the vacuum filter, pollutant concentrations may
also significantly influence costs.
Cost Factors and Adjustments
As previously indicated, costs are adjusted to a common dollar
base and are generally influenced by a number of factors
including: Cost of Labor, Cost of Energy, Capital Recovery Costs
and Debt-Equity Ratio. These cost adjustments and factors are
discussed below.
312
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Dollar Base - A dollar base of January 1978 was used for all
costs.
Investment Cost Adjustment - Investment costs were adjusted to
the aforementioned dollar base by use of the Sewage Treatment
Plant Construction Cost Index. This cost is published monthly by
the EPA Division of Facilities Construction and Operation. The
national average of the Construction Cost Index for January 1978
was 288.0.
Supply Cost Adjustment - Supply costs such as chemicals were
related to the dollar base by the Wholesale Price Index. This
figure was obtained from the U.S. Department of Labor, Bureau of
Labor Statistics, "Monthly Labor Review". For January 1978 the
"Industrial Commodities" Wholesale Price Index was 201.6.
Process supply and replacement costs were included in the
estimate of the total process operating and maintenance cost.
Cost of Labor - To relate the operating and maintenance labor
costs, the hourly wage rate for non-supervisory workers in water,
stream, and sanitary systems was used from the U.S. Department of
Labor, Bureau of Labor Statistics Monthly publication,
"Employment and Earnings". For January 1978, this wage rate was
$6.00 per hour. This wage rate was then applied to estimates of
operation and maintenance man-hours within each process to obtain
direct labor charges. To account for indirect labor charges, 15
percent of the direct labor costs was added to the direct labor
charge to yield estimated total labor costs. Such items as
Social Security, employer contributions to pension or retirement
funds, and employer-paid premiums to various forms of insurance
programs were considered indirect labor costs.
Cost of Energy - Energy requirements were calculated directly
within each process. Estimated costs were then determined by
applying an electrical rate of 3.3 cents per kilowatt hour.
The electrical charge for January 1978 was corroborated through
consultation with the Energy Consulting Services Department of
the Connecticut Light and Power Company. This electrical charge
was determined by assuming that any electrical needs of a waste
treatment facility or in-process technology would be satisfied by
an existing electrical distribution system; i.e., no new meter
would be required. This eliminated the formation of any new
demand load base for the electrical charge.
Capital Recovery Costs - Capital recovery costs were divided into
straight line ten-year depreciation and cost of capital at a ten
percent annual interest rate for a period of ten years. The ten
year depreciation period was consistent with the faster write-off
313
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(financial life) allowed for these facilities, even though the
equipment life is in the range of 20 to 25 years. The annual
cost of capital was calculated by using the capital recovery
factor approach.
The capital recovery factor is normally used in industry to help
allocate the initial investment and the interest to the total
operating cost of the facility. It is equal to:
CRF = i + i
(1+i)N-1
where i is the annual interest rate and N is the number of years
over which the capital is to be recovered. The annual capital
recovery was obtained by multiplying the initial investment by
the capital recovery factor. The annual depreciation of the
capital investment was calculated by dividing the initial
investment by the depreciation period N, which was assumed to be
ten years. The annual cost of capital was then equal to the
annual capital recovery minus the depreciation.
Debt-Equity Ratio - Limitations on new borrowings assume that
debt may not exceed a set percentage of the shareholders equity.
This defines the breakdown of the capital investment between debt
and equity charges. However, due to the lack of information
about the financial status of various plants, it was not feasible
to estimate typical shareholders equity to obtain debt financing
limitations. For these reasons, no attempt was made to break
down the capital cost into debt and equity charges. Rather, the
annual cost of capital was calculated via the procedure outlined
in the Capital Recovery Costs section above.
Subsidiary Costs
The waste treatment and control system costs for end-of-pipe and
in-process waste water control and treatment systems include
subsidiary costs associated with system construction and
operation. These subsidiary costs include:
administration and laboratory facilities
garage and shop facilities
line segregation
yardwork
land
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engineering
legal, fiscal, and administrative
interest during construction
contingency
intercomponent piping instrumentation
Administrative and laboratory facility treatment investment is
the cost of constructing space for administration, laboratory,
and service functions for the waste water treatment system. For
these cost computations, it was assumed that there was already an
existing building and space for administration, laboratory, and
service functions. Therefore, there was no investment cost for
this item.
For laboratory operations, an analytical fee of $90 (January 1978
dollars) was allowed for each wastewater sample, regardless of
whether the laboratory work was done on or off. site. This
analytical fee is typical of the charges experienced during the
past several years of sampling programs. The frequency of
wastewater sampling is a function of wastewater discharge flow
and is presented in Table VIII-2 (page 341). This frequency was
suggested by the Water Compliance Division of the USEPA.
Industrial waste treatment facilities were assumed to need no
garage and shop investment because this cost item was assumed to
be part of the normal plant costs.
Line segregation investment costs account for plant modifications
to segregate wastes. The investment costs for line segregation
included placing a trench in the existing plant floor and
installing the lines in this trench. The same trench was used
for all pipes and a gravity feed to the treatment system was
assumed. The pipe was assumed to run from the center of the
floor to a corner. A rate of 2.04 liters per hour of waste water
discharge per square meter of area (0.05 gallons per hour per
square foot) was used to estimate floor and trench dimensions
from waste water flow rates for use in this cost estimation
process.
The yardwork investment cost item includes the cost of general
site clearing, intercomponent piping, valves, overhead and
underground electrical wiring, cable, lighting, control
structures, manholes, tunnels, conduits, and general site items
outside the structural confines of particular individual plant
components. This cost is typically 9 to 18 percent of the
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installed components investment costs. These cost estimates,
were based on an average of 14 percent: Annual yardwork
operation and maintenance costs are considered a part of normal
plant maintenance and were not included in these cost estimates.
No new land purchases were required. It was assumed that the
land required for the end-of-pipe treatment system was already
available at the plant.
Engineering costs include both basic and special services. Basic
services include preliminary design reports, detailed design, and
certain office and field engineering services during construction
of projects. Special services include improvement studies,
resident engineering, soils investigations, land surveys,
operation and maintenance manuals, and other miscellaneous
services. Engineering cost is a function of process installed
and yardwork investment costs and ranges between 5.7 and 14
percent depending on the total of these costs.
Legal, fiscal and administrative costs relate to the planning and
construction of waste water treatment facilities and include such
items as preparation of legal documents, preparation of
construction contracts, acquisition to land, etc. These costs
are a function of process installed, yardwork, engineering, and
land investment costs ranging between 1 and 3 percent of the
total of these costs.
Interest cost during construction is the interest cost accrued on
funds from the time payment is made to the contractor to the end
of the construction period. The total of all other project
investment costs (process installed; yardwork; land; engineering;
and legal, fiscal, and administrative) and the applied interest
affect this cost. An interest rate of 10 percent was used to
determine the interest cost for these estimates. In general,
interest cost during construction varies between 3 and 10 percent
of total system costs.
Contingency allowance has been included at 10 percent and
intercomponent piping at 20 percent of installed component cost;
instrumentation is included as a lump sum of $25,000 for
continuous processes only.
COST ESTIMATES FOR INDIVIDUAL TREATMENT TECHNOLOGIES
Introduction
Treatment technologies have been selected from among the larger
set of available alternatives discussed in Section VII on the
basis of an evaluation of raw waste characteristics, typical
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plant characteristics (e.g. location, production schedules,
product mix, and land availability), and present treatment
practices within the subcategories .addressed. Specific rationale
for selection is addressed in Sections IX, X, XI and XII. Cost
estimates for each technology addressed in this section include
investment costs and annual costs for depreciation, capital,
operation and maintenance, and energy.
Investment - Investment is the capital expenditure required to
bring the technology into operation. If the installation is a
package contract, the investment is the purchase price of the
installed equipment. Otherwise, it includes the equipment cost,
cost of freight, insurance and taxes, and installation costs.
Total Annual Cost - Total annual cost is the sum of annual costs
for depreciation, capital, operation and maintenance (less
energy), and energy (as a separate function).
Depreciation - Depreciation is an allowance, based on tax
regulations, for the recovery of fixed capital from an investment
to be considered as a non-cash annual expense. It may be
regarded as the decline in value of a capital asset due to
wearout and obsolescence.
Capital - The annual cost of capital is the cost, to the plant,
of obtaining capital expressed as an interest rate. It is equal
to the capital recovery cost (as previously discussed on cost
factors) less depreciation.
Operation and Maintenance - Operation and maintenance cost is the
annual cost of running the waste water treatment equipment. It
includes labor and materials such as waste treatment chemicals.
As presented on the tables, operation and maintenance cost does
not include energy (power or fuel) costs because these costs are
shown separately.
Energy - The annual cost of energy is shown separately, although
it is commonly included as part of operation and maintenance
cost. Energy cost has been shown separately because of its
importance to the nation's economy and natural resources.
Cyanide Oxidation
In this technology, cyanide is destroyed by reaction with sodium
hypochlorite under alkaline conditions. A complete system for
this operation includes reactors, sensors, controls, mixers, and
chemical feed equipment. Control of both pH and chlorine
concentration! (through oxidation-reduction potential) is
important for effective treatment.
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Capital Costs. Capital costs for cyanide oxidation shown in
Figure VIII-2 (page 360) include reaction tanks, reagent storage,
mixers, sensors and controls necessary for operation. Costs are
estimated for both batch and continuous systems with the
operating mode selected on a least cost basis. Specific costing
assumptions are as follows:
For both continuous and batch treatment, the cyanide oxidation
tank is sized as ^an above ground cylindrical tank with a
retention time of 4 Hours based on the process flow. Cyanide
oxidation is normally done on a batch basis; therefore, two
identical tanks are employed. Cyanide is removed by the addition
of sodium hypochlorite with sodium hydroxide added to maintain
the proper pH level. A 60-day supply of sodium hypochlorite is
stored in an in-ground covered concrete tank, 0.3 m (1 ft) thick.
A 90-day supply of sodium hydroxide also is stored in an in-
ground covered concrete tank, 0.3 m (1 ft) thick.
I
Mixer power requirements for both continuous and batch treatment
are based on 2 horsepower for every 11,355 liters (3,000 gal) of
tank volume. The mixer is assumed to be operational 25 percent
of the time that the treatment system is operating.
A continuous control system is costed for the continuous
treatment alternative. This system includes:
2 immersion pH probes and transmitters
2 immersion ORP probes and transmitters
2 pH and ORP monitors
2 2-pen recorders
2 slow process controller
2 proportional sodium hypochlorite pumps
2 proportional sodium hydroxide pumps
2 mixers
3 transfer pumps
1 maintenance kit
2 liquid level controllers and alarms, and miscellaneous
electrical equipment and piping
A complete manual control system is costed for the batch
treatment alternative. This system includes:
2
pH probes and monitors
1
mixer
1
liquid level controller and horn
1
proportional sodium hypochlorite
pump
1
on-off sodium hydroxide pump and
PVC piping from the
chemical storage tanks
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Operation and Maintenance Cost. Operation and maintenance costs
for cyanide oxidation include labor requirements to operate and
maintain the system; electric power for. mixers, pumps and
controls, and treatment chemicals. Labor requirements for
operation and maintenance are shown in Figure VIII-3 (page xxx).
As can be seen operating labor is substantially higher for batch
treatment than for continuous operation. Maintenance labor
requirements for continuous treatment are fixed at 150 manhours
per year for flow rates below 23,000 gph and thereafter increase
according to:
Labor - .00273 x (Flow-23000) + 150
Maintenance labor requirements for batch treatment are assumed to
be negligible.
Annual costs for treatment chemicals and electrical power are
presented in Figure VII1-4 (page 362). Chemical additions are
determined from cyanide, acidity, and flow rates of the raw waste
stream according to:
lbs sodium hypochlorite = 62.96 x lbs CN-
lbs sodium hydroxide = 0.8 x lbs acidity
Cyanide Precipitation
This technology reacts zinc sulfate or ferrous sulfate with the
cyanide to form complex cyanide precipitates such as Fe4 (FeCN6)3
(Prussian Blue). This system, which closely follows a
conventional chemical precipitation system, includes chemical
feed equipment for sodium hydroxide or lime, zinc sulfate or
ferrous sulfate addition, a reaction tank, agitator, control
system, clarifier and pump.
Capital Costs.
The computer calculated capital costs for cyanide precipitation
include costs for each of the five subsystems; 1) alkali feed
system, 2) reactant feed system, 3) reaction tank with agitator;
4) clarifier, and 5) recirculation pumps and control
instrumentation costs are estimated for both batch and continuous
systems with the operating mode selected on a least cost basis.
Specific costing assumptions are set forth below.
For both continuous and batch treatment systems, the alkali feed
system is a FRP tank signed for 15 days supply with dual head
metering pumps including standby. The reactant feed system
includes a steel storage with dust collectors sized for 15 days
supply with volumetric feeders, dual head metering pumps. The
reaction tank is a lined steel tank with agitator sized for one
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hour retention. The clarifier, sized at 10 gal/hr sq ft.
includes the support structive, sludge scraper assembly and drive
unit. A continuous pump and control system is costed for the
continuous alternative. This system includes:
2 immersion pH probes and transmitters
2 immersion ORP probes and transmitters
2 pH and ORP monitors
2 2-pen recorders
2 slow process- controller
2 proportional sodium hypochlorite pumps
2 proportional sodium hydroxide pumps
2 mixers
3 transfer pumps
1 maintenance kit
2 liquid level controllers and alarms, and miscellaneous
electrical equipment and piping
2 immersion pH probes and transmitters
2 immersion ORP probes and transmitters
2 pH and ORP monitors
2 2-pen recorders
2 slow process controller
2 proportional reactant pumps
2 proportional sodium hydroxide pumps
2 mixers
3 transfer pumps
1 maintenance kit
2 liquid level controllers and alarms, and miscellaneous
electrical equipment and piping
2 recycle pumps
1 sludge pump
A manual batch system is costed for the batch treatment
alternative. This system includes:
2 pH probes and monitors
1 mixer
1 liquid level controller and horn
2 pH probes and monitors
1 mixer
1 liquid level controller and horn
1 proportional reactant pump
1 on-off sodium hydroxide pump and PVC piping from the
chemical storage tanks
Mixer power requirements for both continuous and batch treatment
are based on 2 horsepower for every 11,400 1 (3,000 gal) of tank
volume. The mixer is assumed to be operational 25 percent of the
time that the treatment system is operating.
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Operation and Maintenance Cost. Operation .and maintenance costs
for cyanide precipitation include labor requirements to operate
and maintain the system, electric power for mixers, pumps,
clarifier and controls, and treatment chemicals. Electrical
requirements are also included for the chemical storage
enclosures for lighting and ventilation and in the case of
caustic storage, heating. The following criteria are used in
establishing O&M costs:
(1) Reactant feed system
- maintenance materials - 3 percent of manufactured
equipment cost
labor for chemical unloading
5 hrs/50,000 lb for bulk handling
8 hrs/16,000 lb for bag feeding to the hopper
routine inspection and adjustment of feeders is 10
min/feeder/shift
maintenance labor
8 hrs/yr for liquid metering pumps
24 hrs/yr for solid feeders and solution tank
power [function of instrumentation and control,
metering pump HP and volumetric feeder (bag feeding)]
(2) Caustic feed system
maintenance materials - 3 percent of manufactured
equipment cost (excluding storage tank cost)
labor/unloading
dry NaOH - 8 hrs/16,000 lb
liquid 50 percent NaOH - 5 hrs/50,000 lb
labor operation (dry NaOH only) - 10 min/day/feeder
- labor operation for metering pump - 15 min/day
annual maintenance - 8 hrs
power [includes metering pump HP, instrumentation and
control, volumetric feeder (dry NaOH)]
(3) Clarifier
maintenance materials range from 0.8 percent to 2
percent as a function of increasing size
- labor - 150 to 500 hrs/yr (depending on size)
power - based on horsepower requirements for sludge
pumping and sludge scraper drive unit
(4) Reaction vessel with agitator
maintenance materials 6 2 percent of equipment cost
labor
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— 15 min/mixer/day routine O&M
— 4 hrs/mixer/6 mos - oil changes
— 8 hrs/yr - draining, inspection, cleaning
- power - based on horsepower requirements for agitator
(5) Recycle pump
maintenance materials - percent of manufactured
equipment cost variable with flowrate
50 ft TDH; motor efficiency of 90 percent and pump
efficiency of 85 percent
Annual costs for treatment chemicals are determined from cyanide
concentration, pH, metals concentrations, and flowrate of the raw
waste stream. Cost curves are not presented for this technology
because the cyanide oxidation curves are judged to be close
enough for graphic estimates. Computer calculated costs are
precise calculations.
Chromium Reduction
This technology chemically reduces hexavalent chromium under acid
conditions to allow subsequent removal of the trivalent form by
precipitation as the hydroxide. Treatment may be provided in
either continuous or batch mode, and cost estimates are developed
for both. Operating mode for system cost estimates is selected
on a least cost basis.
Capital cost. Cost estimates include all required equipment for
performing this treatment technology, including reagent dosage,
reaction tanks, mixers and controls. Different reagents are
provided for batch and continuous treatment resulting in dif-
ferent system design considerations as discussed below.
For both continuous and batch treatment, sulfuric acid is added
for pH control. A 90 day supply is stored in the 25 percent
aqueous form in an above-ground, covered concrete tank, 0.305 m 1
ft) thick.
For continuous chromium reduction, the single chromium reduction
tank is sized in an above-ground cylindrical concrete tank with a
0.305 m (1 ft) wall thickness, a 45 minute retention time, and an
excess capacity factor of 1.2. Sulfur dioxide is added to con-
vert the influent hexavalent chromium to the trivalent form.
i
The control system for continuous chromium reduction consists of:
1 immersion pH probe and transmitter
1 immersion ORP probe and transmitter
1 pH and ORP monitor
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2 slow process controllers
1 sulfonator and associated pressure regulator
1 sulfuric acid pump
1 transfer pump for sulfur dioxide ejector
2 maintenance kits for electrodes, .and miscellaneous
electrical equipment and piping
For batch chromium reduction, the dual chromium reduction tanks
are sized as above-ground cylindrical steel steel tanks with a 4
hour retention time, and an excess capacity factor of 1.2.
Sodium bisulfite is added to reduce the hexavalent chromium.
A completely manual system is provided for batch operation. Sub-
sidiary equipment includes:
1 sodium bisufite mixing and feed tank
1 metal stand and agitator collector
1 sodium bisulfite mixer with disconnects
1 sulfuric acid pump
1 sulfuric acid mixer with disconnects
2 immersion pH probes
1 pH monitor, and miscellaneous piping
Capital costs for batch and continuous treatment systems are pre-
sented in Figure VIII-5 (page 363).
Operation and Maintenance. Costs for operating and maintaining
chromium reduction systems include labor, chemical addition, and
energy requirements. These factors are determined as follows:
LABOR
The labor requirements are plotted in Figure VIII-6 (page 364).
Maintenance of the batch system is assumed to be negligible and
so it is not shown.
CHEMICAL ADDITION
For the continuous system, sulfur dioxide is added according to
the following:
(lbs S02/day) = (15.43) (flow to unit-MGD) (Cr+6 mg/1)
In the. batch mode, sodium bisulfite is added in place of sulfur
dioxide according to the following:
(lbs NaBS03/day) = (20.06) (flow±o unit-MGD) (Cr+6 mg/1)
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ENERGY
Two horsepower is required for chemical mixing. The mixers are
assumed to operate continuously over the operation time of the
treatment system.
Given the above requirements, operation and maintenance costs are
calculated based on the following:
$6.00 per man + 10% indirect labor charge
$380/ton of sulfur dioxide
$20/ton of sodium bisulfite
$0.032/kilowatt hour of required electricity
Oil Skimming
This technology removes oils from process wastewater by gravity
separation and subsequent removal of the surface layer of oil. A
baffled tank provides quiescent conditions conducive to
separation of oil droplets and retention of floating oil behind
an underflow baffle.
Capital Cost. The costing analyses for the API Oil Skimming pro-
cess were based upon an optimization of the one channel oil se-
parator design by expanding the API design standards. The fol-
lowing assumptions were used for costing purposes:
1. The unit was assumed to be an in-the-ground rectangular
cross-section concrete tank with a maximum horizontal stream
velocity set to the smaller of 3 fpm or 4.72 times the oil
rise rate.
2. The depth-to-width ratio was maintained between 0.3-0.5 to
minimize tank size.
3. The depth was maintained between 3 ft. minimum and 8 ft.
maximum, and the width between 6 ft. minimum and 20 ft.
maximum to provide minimum tank size.
4. The costs were based on a 0.3 m (1 ft) concrete thickness
and include the excavation required.
Figure VIII-7 (page 365) presents estimated oil separator capital
costs. Flows up to 0.25 MGD are costed for a single unit; flows
greater than 0.25 MGD, require more than one unit.
Operation and Maintenance Cost. Only labor is included in the
o'peration and maintenance costs of the skimmer since other costs
were considered negligible in comparison. Figure VIII-8 (page
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366) illustrates the correlation used to calculate the required
man-hours for operation and maintenance. The total man-hours are
then multiplied by the $6.00 per hour labor rate plus 10 percent
indirect labor charge.
Chemical Precipitation and Clarification
This technology removes dissolved pollutants by first reacting
added lime and sodium sulfide to form precipitates and then
removing the precipitated solids by gravity settling in a
clarifier. Several distinct operating modes and construction
techniques are costed to provide least cost treatment over a
broad range of flow rates. Because of their interrelationships
and integration' in common equipment in some installations,'both
the chemical addition and solids removal equipment are addressed
in a single subroutine.
Investment Cost. Investment costs are determined for this tech-
nology for continuous treatment and for batch treatment systems
using steel tank construction. The least cost system is selected
for each application. Continuous treatment systems include a mix
tank for reagent feed addition and a clarification basin with
associated sludge rakes and pumps. Batch treatment includes only
reaction-settling tanks and sludge pumps.
For the continuous treatment systems, construction is different
for flows above and below 10,000 1/hr (2700 gph). For flow rates
greater than or equal to 10,000 1/hr, the continuous treatment
system costs include a flocculator, settling tank, and associated
equipment. For flow rates less than 10,000 1/hr, the continuous
clarifier costs include two above-ground tanks instead of the
flocculator-settling tank combination.
The in-ground flocculator is a conrete unit. The size is based
on a 45 minute retention time, a length to width ratio of 5, a
depth of 8 feet, and a 40 percent excess capacity. Capital costs
include excavation and a mixer. The estimated flocculator cost
for batch operation is shown in Figure VIII-9 (page 367).
The settling tank is a steel unit sized for a hydraulic loading
of 15.0 gph/sq ft, a 4 hour retention time, and an excess
capacity of 40 percent. The two conical unlined carbon steel
tanks are sized for four hour retention in each tank. Capital
costs include excavation and a skimmer. Figure VIII-10 (page
368) shows the combined flocculator - settling tank cost for
batch operation.
cost for these tanks for flows less than 1000 1/hr (2604 gph).
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A cost of $3202 is included in capital cost estimates for sludge
pumps regardless of whether the dual tanks or the flocculator-
settling tank combination is used. This cost covers the expense
for two centrifugal sludge pumps.
For batch treatment, dual cylindrical carbon steel tanks sized
for 8 hour retention and 40 percent excess capacity are used. If
the required tank volume exceeds 50,000 gallons, then costs for
field fabrication are'included. The capital cost for the batch
system (not including the sludge pump costs) is shown in Figure
VIII-11 (page 369). The capital cost estimate for batch
treatment also includes a fixed $3,202 cost for sludge pumps as
discussed above.
Figure VIII-12 (page 370) shows a comparison of the capital cost
curves for the modes discussed above. These curves include
sludge pump costs.
All costs include motors, starters, alternators, and necessary
piping.
Operation and Maintenance Cost
The operation and maintenance costs for the chemical
precipitation and clarification routine include:
1) Cost of chemicals added (lime, alum)
2) Labor (operation and maintenance)
3) Energy
Each of these contributing factors are discussed below.
CHEMICAL COST
Lime and sodium sulfide are added for metals and solids
removal. The amount of chemical required is based on
equivalent amounts of various pollutant parameters present
in the stream entering the unit. The methods used in
determining the lime requirements are shown in Table VII1-3
(page 336).
LABOR
Figure VIII-13 (page 371) presents the man-hour requirements
for the continuous clarifier system. For the batch system,
maintenance labor is assumed to be negligible and operation
labor is calculated from:
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(man-hours for operation) = 390 •+ (0.975) (lbs. lime added
per day)
ENERGY
The energy costs are calculated from the treatment and
sludge pump horsepower requirements.
Continuous Mode
The treatment horsepower requirement is assumed to be
constant over the hours of operation of the treatment system
at a level of 0.0000265 horsepower per 1 gph of flow
influent to the clarifier. The sludge pumps are assumed to
be operational for 5 minutes of each operational hour at a
level of 0.00212 horsepower per 1 gph of sludge stream flow.
Batch Mode
The treatment horsepower requirement is assumed to occur for
7.5 minutes per operational hour at the following level:
inf1uent flow 1 042 gph; 0.0048 hp/gph
influent flow 1042 gph; 0.0096 hp/gph
The power required for the sludge pumps in the batch mode is
the same as that required for the sludge pumps in the con-
tinuous mode.
Given the above requirements, operation and maintenance
costs are calculated based on the following:
$6.00 per man-hour + 15% indirect labor charge
$41.26/ton of lime
$0.284/pound of sodium sulfide
$0.032/kilowatt-hour of required electricity
Sulfide Precipitation - Clarification
This technology removes dissolved pollutants by the formation of
precipitates by reaction with sodium sulfide, sodium bisulfide,
or ferrous sulfide and lime, and subsequent removal of the pre-
cipitate by settling. As discussed for chemical precipitation
and clarification, the addition of chemicals, formation of pre-
cipitates, and removal of the precipitated solids from the waste-
water stream are addressed together in cost estimation because of
their interrelationships and common equipment under some
circumstanced.
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Vjr
Investment Cost. Capital cost estimation procedures for sulfide
precipitation and clarification are identical to those for che-
mical precipitation and clarification. Continuous treatment sys-
tems using steel construction and batch treatment systems are
costed to provide a least cost system for each flow range and set
of raw waste characteristics. Cost factors1 are also the same as
for chemical precipitation and clarification.
Operation and Maintenance Costs. Costs estimated for the
operation and maintenance of a sulfide precipitation and
clarification system are also identical to those for chemical
precipitation and clarification except for the cost of treatment
chemicals. Lime is added prior to sulfide precipitation to
achieve an alkaline pH of approximately 8.5-9 and this
precipitates some pollutants as hydroxides or calcium salts.
Lime consumption based on both neutralization and formation of
precipitates is calculated to provide a 10 percent excess over
stochiometric requirements. Sulfide costs are based on the
addition of ferrous sulfate and sodium bisulfide (NaHS) to form a
10 percent excess of ferrous sulfide over stoichiometric
requirements for precipitation. Reagent additions are calculated
as shown in Table VII1-4 (page 343) . Labor and energy rates are
identical to those shown for chemical precipitation and clari-
fication.
Multi-Media Filtration
This technology removes suspended solids by filtering them
through a bed of particles of several distinct size ranges. As a
polishing treatment after chemical precipitation and
clarification multi-media filtration improves the removal of
precipitates and thereby improving removal of the original
dissolved pollutants.
Capital Cost. The size of the multi-media filtration unit is
based on 20 percent excess flow capacity and a hydraulic loading
of 0.5 ft2/gpm. The capital cost, presented in Figure VIII-14
(page 372) as a function of flow rate, includes a backwash
mechanism, pumps, controls, media and installation. Minimum
costs are obtained using a minimum filter surface area of 60 ft2.
Operation and Maintenance. The costs shown in Figure VIII-14 for
operation and maintenance includes contributions of materials,
electricity and labor. These curves result from correlations
made with data obtained by a major manufacturer. Energy costs
are estimated to be 3 percent of total O&M. '
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Membrane Filtration
Membrane filtration includes addition of sodium hydroxide to form
metal precipitates and removal of the precipitated solids on a
membrane filter. As a polishing treatment, it minimizes metal
solubility and very, effectively removes precipitated hydroxides
and sulfides.
Capital Cost. Based on manufacturer's data, a factor of
$52.60/gph flow to the membrane filter is used to estimate
capital cost. Capital cost includes installation.
Operation and Maintenance Cost. The operation and maintenance
costs for membrane filtration include:
1) Labor
2) Sodium Hydroxide Added
3) Energy
Each of these contributing factors are discussed below.
2 man-hours per day of operation are included.
SODIUM HYDROXIDE ADDITION
Sodium hydroxide (or lime) is added to precipitate metals as
hydroxides or to insure a pH favorable to sulfide precipitation.
The amount of sodium hydroxide required is based on equivalent
amounts of various pollutant parameters present in the stream
entering the membrane filter. The method used to determine the
sodium hydroxide demand is shown below:
(Sodium Hydroxide Per Pollutant, lb/day) = ANaOH x Flow Rate
(GPH) x Pollutant Concentration (mg/1)
LABOR
POLLUTANT
ANaOH
Chromium, Total
Copper
Acidity
Iron, DIS
Zinc
Cadmium
Cobalt
Manganese
Aluminum
0.000508
0.000279
0.000175
0.000474
0.000268
0.000158
0.000301
0.000322
0.000076
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ENERGY
The horsepower required is as follows:
2 1/2-horsepower mixers operating 34 minutes per operational
hour
2 1-horsepower pumps operating 37 minutes per operational
hour
1 20-horsepower pump operating 45 minutes per operational
hour
Given the above requirements, operation and maintenance costs are
calculated based on the following:
$6.00 per man-hour + 15% indirect labor charge
$0.11 per pound of sodium hydroxide required
$0,032 per kilowatt-hour of energy required
Ultrafiltration
Capital Cost. The capital cost for ultrafiltration is calculated
using a correlation developed from data supplied by a major manu-
facturer. Figure VIII-15 (page 373) illustrates the results for
this-correlation.
Operation and Maintenance Cost
The unit is sized on the basis of a hydraulic loading of 1,430
1/day/ m2 of surface area and an excess capacity factor of 1.2.
The operation and maintenance costs are made up of contributions
from:
1) Labor
2) Membrane Replacement
3) Energy
Each of these factors are discussed below.
LABOR
Figure VII1-16 (page 374) shows curves of the man-hour
requirements for both maintenance and operation.
MEMBRANE REPLACEMENT
One filter module is required per year for each 500 gallons
per day of treated flow.
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ENERGY
The power requirements based on 30.48 m of pumphead yield a
constant horsepower value of 0.006 horsepower/flow to the
ultrafiltration unit.
Given the above requirements, opeation and maintenance costs
are calculated based on the following:
$(5.00 per man-hour + 15 percent indirect labor charge
$218/ultrafiltration module
$0.032/kilowatt-hour of required energy
Vacuum Filtration
Vacuum filtration is widely used to reduce the water content of
high solids streams. In the coil coating industry, this tech-
nology is used to dewatering sludge from clarifiers, membrane
filters and other waste treatment units.
Capital Cost. The vacuum filter is sized based on a typical
loading of 14.6 kg of influent solids per hour per square meter
of filter area (3 lbs/ft2-hr). The curves of cost versus flow at
TSS concentrations of, 3 percent and 5 percent are shown in Figure
VIII-17 (page 375). The capital cost obtained from this Curve
includes installation costs.
Operation and Maintenance Cost.
. . LABOR, '
The vacuum filtration subroutine may be run for off-site
sludge, disposal or for on-site sludge incineration. On-site
sludge incineration assumes a conveyor transport and reduced
operating man-hours from!those for off-site disposal. The
required operating hours per year varies with both flow rate and
the total suspended solids concentration in the influent stream.
Figure VII1-18 (page 376) shows the variance of operating hours
with flow and TSS concentration. Maintenance labor for either
sludge disposal mode is fixed at 24 manhours per year.
MATERIALS
The cost of materials and supplies needed for operation and
maintenance includes belts, oil, grease, seals, and chemicals
required to raise the total suspended solids to the vacuum
filter. The amount of chemicals required (iron and alum) is
based on raising the TSS concentration to the filter by 1 mg/1.
331
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Costs of materials required as a function of flow and unaltered
TSS concentrations is presented in Figure VIII-19 (page 377).
ENERGY
Electrical costs needed to supply power for pumps and
controls are presented in Figure VIII-20 (page 378). Because the
required pump horsepower depends on the influent TSS level, the
costs are presented as. a function of flow rate and TSS level.
Contract Removal
Sludge, waste oils, and in some cases concentrated waste
solutions frequently result from wastewater treatment processes.
Although these may be disposed of on-site by incineration,
landfill or reclamation, they are most often removed on a
contract basis for off-site disposal. System cost estimates are
based on contract removal of sludges and waste oils. Where only
small volumes of concentrated wastewater are produced, contract-
removal for off-site treatment may represent the most cost-
effective approach to water pollution abatement. Estimates of
solution contract-haul costs are also provided by this subroutine
and may be selected in place of on-site treatment on a least-cost
basis.
Capital Costs. Capital investment for contract removal is zero.
Operating Costs. Annual costs are estimated for contract removal
of total waste streams or sludge and oil streams as specified in
input data. Sludge and oil removal costs are further divided
into wet and dry haulage depending upon whether or not upstream
sludge dewatering is provided. The use of wet haulage or of
sludge dewatering and dry haulage is based on least cost as
determined by annualized system costs over a ten year period.
Wet haulage costs are always used in batch treatment systems^ahd
when the volume of the sludge stream is less than 100 galIons per
day. j
Both wet sludge haulage and total waste haulage differ in cost
depending on the chemical composition of the waste removed.
Wastes are classified as cyanide bearing, hexavalent chromium
bearing, or oily and assigned different haulage costs as shown
below.
332
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Waste Composition Haulage Cost
-0.05 mg/1 CN- $0.45/gallon
-0.1 mg/1 Cr+6 $'0 .'20/gallon
Oil & grease-TSS $0.12/gallon
All others $0.16/gallon
Dry (40 percent dry solids in the sludge) sludge haul costs are
estimated at $0.12 gallon.
In-process Treatment and Control Components
Three major in-process control techniques have been identified
for use in reducing wastewater pollutant discharges from coil
coating facilities. Since product quench water constitutes a
substantial fraction of the total process wastewater discharge,
use of a cooling tower to recirculate this stream significantly
reduces elf fluent flow rates and pollutant loads. Also the reuse
of quench blowdown for three stage countercurrent cascade rinsing
for cleaning and conversion coating reduces flow rates and
pollutant loads. Cyanides may be eliminated from process
wastewater effluents by substitution of non-cyanide chromating
solutions. Cost estimates are presented for cooling towers;
however, EPA did not develop specific cost estimates for
substitution of non-cyanide chromating solutions because these
costs are highly site specific and are not amenable to estimation
on a general basis.
Quench water recirculation Requires installation of a cooling
tower for the quench stream.
Capital Costs. The cooling towers were sized to provide a
temperature reduction through the tower of approximately 5.6°C
with an effluent temperature 3.9°C above the ambient wet bulb
temperature. Capital costs presented in Figure VIII-21 (page
379) are based on data supplied by a major manufacturer. The
smallest unit available is for 10 gpm flow. For flow rates less
than 10 gpm, capital (as well as operating and maintenance) costs
are set to zero, and a warning is printed * The three distinct
curve segments correspond to three different cooling units which
are required to produce the necessary range of flow capacity.
Operation and Maintenance Costs. Operation and maintenance
expenses include labor and electrical power. Labor is estimated
at 252 hours per year.
Figure VI11-22 (page 380) shows the electrical energy costs for
operation of the pumps and fans for the cooling tower.
333
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Countercurrent rinsing is included in the model technology form
to reduce the volume of the cleaning and conversion coating waste
streams to levels necessary to allow LS&F end-of-pipe technology
to be applied. Countercurrent rinsing requires additional rinse
tanks or spray equipment and plumbing as compared to single-stage
rinses, and extension of materials handling equipment or
provision of additional manpower for finse operation.
Capital Cost. Cost estimates for countercurrent rinsing are
based upon installation,of a three stage system on each of the
individual waste streams. The installation cost is small for a
new source. Cost estimates included such variables as tank
costs, recycle pump and motor costs, piping, valving, and control
instrumentation costs. The investment cost curve used is the
equalization tank curve (Figure VII1-23, page 381). These costs
include mixers, pumps and installation. The motor costs needed
for countercurrent rinse are estimated equal to the mixer costs.
Operation and Maintenance Cost. The operation and maintenance
costs associated with countercurrent rinsing include labor,
materials and energy. Each of these costs is discussed below.
LABOR
Labor requirements for operation and maintenance of the pump
station are based upon one hour of maintenance per week of
operation for each process line associated with surface
preparation. A rate of $6.00 per hour plus a 15 percent indirect
labor charge (to cover the cost of employee fringe benefits) is
used in determining labor costs.
MATERIALS Annual material costs for operation and
maintenance of each countercurrent rinsing system are assumed to
be 3 percent of the initial system capital cost.
ENERGY
Electrical energy requirements for each countercurrent rinsing
system are based upon recirculation pump motor horsepower
requirements. Electrical cost is calculated based upon a charge
of $0.33 per kilowatt-hour and is shown in Figure VIII-24 (page
382).
Non-cyanide chromating solutions are available which serve the
same function as the cyanide bearing solutions at an
approximately equal cost; however, reports indicate that use of
the non-cyanide solutions requires closer process control and
longer residence time in the chromating bath. The costs of
reagent substitution, therefore, are not directly calculable as
334
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reagent or fixed equipment costs, but are highly dependent on
process conditions at individual plants. Facilities with well-
controlled processes may be able to use non-cyanide solutions
with little or. no cost impact,, while poorly controlled facilities
or facilities with marginally sized equipment could incur very
high costs for major process revisions. As a result of these
considerations, no general cost estimates for this technology are
presented, and none are included in system cost estimates.
Summary of Treatment and Control Component Costs. Example costs
for each of the treatment and control components discussed" above
as supplied to process wastewater streams within the coil coating
category are presented in Tables VII1-4 through VII1-15 (pages
343-354). Each technology is provided with three cost levels
representative of typical, low and high raw waste flow rates
encountered within the category.
TREATMENT SYSTEM COST ESTIMATES
This section presents estimates-of the total cost of wastewater
treatment and control systems which incorporate the treatment and
control components discussed above. Median (typical), low and
high flow rates in the subcategory addressed are presented for
each system in order to provide an indication of the range of
costs to be incurred in implementing each level of treatment.
All available flow data from industry data collection portfolios
were used in defining median, maximum and minimum raw waste
flows, and flow breakdowns where streams are segregated for
treatment. Raw waste characteristics were based on sampling data
as discussed in Section V.
The system costs include component costs and subsidiary costs,
including engineering, line segregation, admininstration, and
interest expenses during construction. The cost estimates for
BPT systems assume that none of the specified treatment and
control measures are in place, so that the presented costs
represent total costs for the systems. Costs are presented for
BAT systems both as total system costs and as incremental costs
required to modify an existing BPT system to achieve BAT.
System Cost Estimates (BPT)
This section presents the system cost estimates for the BPT end-
of-pipe treatment sytems. Several flow rates are presented for
each case to effectively model a wide spectrum of plant sizes.
Figure IX-1 (page 400) shows the model end-of-pipe treatment for
all three basis material subcategories. The chemical oxidation
of cyanide and the chemical reduction of chromium are shown as
335
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optional treatment processes. The use of either of these
treatment components depends on the production processes employed
at the plant. For the purpose of the BPT system cost estimates,
cyanide precipitation was assumed to be a required treatment
process only for the aluminum subcategory, because of the
presence of cyanide in the chromating baths applied to aluminum.
Chromium reduction was included in the system costs for all
subcategories to treat hexavalent chromium wastes from the
chromic acid sealer and conversion coating rinses, where
appropriate.
The costing assumptions for each component of the BPT system were
discussed above under Technology Costs and Assumptions. In addi-
tion to these components, contractor oil and sludge removal was
included in all cost estimates.
Table VIII-16 (page 355) present costs for normal plant BPT
treatment system influent flow rates. The basic cost elements
used in preparing these tables are the same as those presented
for the individual technologies: investment, annual capital
cost, annual depreciation, annual operation and maintenance cost
(less energy cost), energy cost, and total annual cost. These
elements were discussed in detail earlier in this section.
Cost computations were based on selection of a least cost
treatment system. This procedure calculated the costs for a
batch treatment system, a continuous treatment system, and haul-
age of the complete waste water flow over a 10 year comparison
period; the least expensive system was then selected for presen-
tation in the system cost tables.
The various investment costs assume that the treatment system
must be specially constructed and include all subsidiary costs
discussed previously. Operation and maintenance costs assume
continuous operation, 24 hours a day, 5 days per week, for 52
weeks per year.
System Cost Estimates (BAT Level I)
The BAT Level 1 alternative calls for reduction of the plant
discharge flow by using in-plant technology - recirculation and
reuse of quench waters.
Recirculation and,reuse of quench water significantly reduces the
volume of waste water discharged by a typical coil coating plant.
Costs of installing and operating a cooling tower were calculated
based on total quench water recirculation. . Design and cost
assumptions for the cooling tower were discussed previously.
336
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Table VIII-17 (page 356) presents example cost data for
construction and operation of BAT Level I treatment facilities
for normal plants with no existing wastewater treatment. Figure
X-l (page 429) depicts the components of the end-of-pipe system.
Quench water recirculation is integrated within the process line.
System Cost Estimates (BAT Level II)
System cost estimates for adding a multimedia filter to the BAT
Level 1 end-of-pipe system were developed to provide BAT Level 2
treatment cost estimates A schematic of this end-of-pipe system
which is similar to the proposed BAT is shown in Figure X-2 (page
430). The costing assumptions for the multimedia filter were
discussed earlier.
Table VIII-18 (page 357) present example BAT Level II treatment
costs for construction of the entire end-of-pipe system. These
costs represent anticipated expenditures to attain BAT Level II
for a plant with no treatment in place.
System Cost Estimates - (New Sources)
The suggested treatment system for NSPS is displayed in Figure
XI-3 (page 445), and costs are presented in Table VIII-19 (page
358). Thesystem costs include quench water recirculation costs
as discussed previously for BAT Level 1.
System Cost Estimates - (Pretreatment)
The model treatment technology for pretreatment at existing
sources (PSES) is the same as the BAT 1 treatment system and the
model treatment system for new sources (PSNS) is the same as the
NSPS treatment system. Estimates of construction and operation
of PSES and PSNS treatment facilities for normal plants with no
existing wastewater treatment are the same as BAT 1 and NSPS,
respectifely (See Tables VIII-17 and VIII-19).
Use of Cost Estimation Results
Cost estimates presented in the tables in this section are for
treatment and control equivalent to the specified level. They
will not, in general, correspond precisely to cost experience at
any individual plant. Specific plant conditions such as age,
location, plant layout, or present production and treatment
practices may yield costs which are either higher or lower than
the presented costs. Because the costs shown are total system
costs and do not assume any treatment in place, it is probable
that most plants will require smaller expenditures to reach the
specified levels of control from their present status.
337
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The actual costs of installing and operating a BPT system at a
particular plant may be substantially lower than the tabulated
values. Reductions in investment and operating costs are
possible in several areas. Design and installation costs may be
reduced by using plant workers. Equipment costs may be reduced
by using or modifying existing equipment instead of purchasing
all new equipment. Application of an excess capacity factor,
which increases the size of most equipment foundation costs could
be reduced if an existing concrete pad or floor can be utilized.
Equipment size requirements may be reduced by the ease of treat-
ment (for example, shorter retention time) of particular waste
streams. Substantial reduction in both investment and operating
cost may be achieved if a plant reduces its water use rate below
that assumed in costing.
ENERGY AND NON-WATER QUALITY ASPECTS
Energy Aspects
Energy aspects of the wastewater treatment processes are impor-
tant because of the impact of energy use on' our natural resources
and on the economy. Electrical power and fuel requirements
(coal, oil, or gas) are listed in units of kilowatt hours per ton
of dry solids for sludge and solids handling. Specific energy
uses are noted in the "Remarks" column.
Energy requirements are generally low, although evaporation can
be an exception if no waste heat is available at the plant. If
evaporation is used to avoid discharge of pollutants, the in-
fluent water rate should be minimized. For example, an upstream
reverse osmosis or ultrafiltration unit can drastically reduce
the flow of wastewater to an evaporation device.
i
Non-Water Quality Aspects
It is important to consider the impact of each treatment process
on air, noise, and radiation pollution of the environment to pre-
clude the development of a more adverse environmental impact.
In general, none of the liquid handling processes causes air pol-
lution. With sulfide precipitation, however, the potential
exists for evolution of hydrogen sulfide, a toxic gas. Proper
control of pH in treatment eliminates this problem. Alkaline
chlorination for cyanide destruction and chromium reduction using
sulfur dioxide also have potential atmospheric emissions. With
proper design and operation, however, air pollution impacts are
eliminated. Incineration of sludges or solids can cause
significant air pollution which must be controlled by suitable
bag houses, scrubbers or stack gas precipitators as well as
338
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proper incinerator operation and maintenance. None of the
wastewater treatment processes causes objectionable noise and
none of the treatment processes has any potential for radioactive
radiation hazards.
The processes for treating the wastewaters from this category
produce considerable volumes of sludges. In order to ensure
long-term protection of the environment from harmful sludge
constituents, special consideration of disposal sites should be
made by RCRA and municipal authorities where applicable.
339
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TABLE VIII-l
COST PROGRAM POLLUTANT PARAMETERS
Parameter, Units
Flow, MGD
pH, pH units
Turbidity, Jackson Units
Temperature, degree C
Dissolved Oxygen, mg/1
Residual Chlorine, mg/1
Acidity, mg/1 CaC03
Alkalinity, mg/1 CaC03
Ammonia, mg/1
Biochemical Oxygen Demand, mg/1
Color, Chloroplatinate units
Sulfide, mg/1
Cyanides, mg/1
Kjeldahl Nitrogen, mg/1
Phenols, mg/1
Conductance, micromhos/cm
Total Solids, mg/1
Total Suspended Solids, mg/1
Setteable Solids, mg/1
Aluminum, mg/1
Barium, mg/1
Cadmium, mg/1
Calcium, mg/1
Chromium, Total, mg/1
Copper, mg/1
Fluoride, mg/1
Iron, Total, mg/1
Lead, mg/1
Magnesium, mg/1
Molybdenum, mg/1
Total Volatile Solids, mg/1
Parameter, Units
Oil, Grease, mg/1
Hardness, mg/1 CaC03
Chemical Oxygen Demand, mg/1
Algicides, mg/1
Total Phosphates, mg/1
Polychlorobiphenyls, mg/1
Potassium, mg/1
Silica, mg/1
Sodium, mg/1
Sulfate, mg/1
Sulfite, mg/1
Titanium, mg/1
Zinc, mg/1
Arsenic, mg/1
Boron, mg/1
Iron, Dissolved, mg/1
Mercury, mg/1
Nickel, mg/1
Nitrate, mg/1
Selenium, mg/1
Silver, mg/1
Strontium, mg/1
Surfactants, mg/1
Beryllium, mg/1
Plasticizers, mg/1
Antimony, mg/1
Bromide, mg/1
Cobalt, mg/1
Thallium, mg/1
Tin, mg/1
Chromium, Hexavalent, mg/1
340
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TABLE VIII—2
WASTEWATER SAMPLING FREQUENCY
Wastewater Discharge
(liters per day) Sampling Frequency
0 ~ 37/850 once per month
37,850 - 189,250 twice per month
189,250 - 378,500 once per week
378,500 - 946,250 twice per week
946,250+ thrice per week
341
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TABLE VIII-3
CLARIFIER CHEMICAL REQUIREMENTS
LIME REQUIREMENT*
POLLUTANT
Chromium, Total
Copper
Acidity-
Iron, Dissolved
Zinc
Cadmium
Cobalt
Manganese
Aluminum
aLIME ,
0.000470
0.000256
0.000162
0.000438
0.000250
0.000146
0.000276
0.000296
0.000907
* (Lime Demand Per Pollutant, lbs/day) = ALime x Plow Rate (GPH) x Pollutant
Concentration (mg/1)
342
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TABLE VIII-4
CONTINUOUS CYANIDE OXIDATION
TREATMENT COSTS
System Plow Rate - liters/hr
(gals/day)
Investment
Annual Costs
Capital Costs
Deprec iation
Operating and Maintenance Costs
(Excluding Energy and Power Costs)
Energy and Power Costs
3154. 1577. 252.
(20000.) (10000.) (1600.)
55436.246 49425.184 41934.156
3478.402 3101.223 2631.195
5543.621 4942.516 4193.414
1586.535 1383.234 1125.162
179.391 89.696 14.351
TOTAL ANNUAL COSTS
10787.945 9516.664 7964.117
343
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TABLE VIII-5
BATCH CYANIDE OXIDATION
TREATMENT COSTS
System Flow Rate - liters/hr
(gals/day)
Investment
Annual Costs
Capital Costs
Depreciation
Operating and Maintenance Costs
(Excluding Energy and Power Costs)
Energy and Power Costs
3154. 1577. 252.
(20000.) (10000.) (1600.)
26350.004 20338.941 12847.922
1653.351 1276.186 806.154
2635.000 2033.990 1284.792
7879.973 3939.990 630.398
179.391 89.696 14.351
TOTAL ANNUAL COSTS
12347.715 7339.762 2735.694
344
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TABLE VIII-6
CONTINUOUS CHROMIUM REDUCTION
TREATMENT COSTS
System Flow Rate - liters/hr
(gals/day)
Investment
Annual Costs
Capital Costs
Depreciation
Operating and Maintenance Costs
(Excluding Energy and Power Costs)
Energy and Power Costs
3154. 1577. 252.
(20000.) (10000.) (1600.)
22651.824 21899.258 20875.820
1421.310 1374.090 1309.871
2265.182 2189.926 2087.582
2239.690 1513.156 844.668
322.905 322.905 322.905
TOTAL ANNUAL COSTS
6249.082 5400.070 4565.023
345
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TABLE VIII-7
BATCH CHROMIUM REDUCTION
TREATMENT COSTS
System Plow Rate - liters/hr
(gals/day)
Investment
Annual Costs
Capital Costs
Depreciation
Operating and Maintenance Costs
(Excluding Energy and Power Costs)
Energy and Power Costs
3154. 1577. 252.
(20000.) (10000.) (1600.)
19382.414 15243.586 9959.789
1216.167 956.473 624.936
1938.241 1524.358 995.979
2654.711 1327.357 995.979
322.905 322.905 322.905
TOTAL ANNUAL COSTS
6132.020 4131.090 2156.197
346
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TABLE VIII-8
OIL SKIMMING
TREATMENT COSTS
System Flow Rate - liters/hr 15771. 4416. 473.
(gals/day) (100000.) (28000.) (3000.)
Investment 6311.102 4265.543 3604.671
Annual Costs
Capital Costs
Depreciation
Operating and Maintenance Costs
(Excluding Energy and Power Costs)
Energy and Power Costs
395.996 267.646 226.178
631.110 426.554 360.467
785.906 439.380 179.619
0.0 0.0 0.0
TOTAL ANNUAL COSTS
1813.012 1133.580
766.264
347
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TABLE VIII-9
CONTINUOUS CHEMICAL PRECIPITATION
TREATMENT COSTS
System Flow Rate - liters/hr
(gals/day)
Investment
Annual Costs
Capital Costs
Depreciation
Operating and Maintenance Costs
(Excluding Energy and Power Costs)
Energy and Power Costs
29176. 11670. 3154.
(185000.) (74000.) (20000.)
74613.500 65033.004 41844.191
4681.680 4080.555 2625.551
7461.348 6503.297 4184.418
5400.215 3783.685 2997.265
34.966 13.986 3.780
TOTAL ANNUAL COSTS
17578.207 14381.520 9811.008
348
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table VIII-10
BATCH CHEMICAL PRECIPITATION
TREATMENT COSTS
System Flow Rate - liters/hr
(gals/day)
Investment
Annual Costs
Capital Costs
Depreciation
Operating and Maintenance Costs
(Excluding Energy and Power Costs)
Energy and Power Costs
29176. 11670. 3154.
(185000.) (74000.) (20000.)
64009.352 38949.047 31069.320
4016.320 2443.892 1949.470
6400.934 3894.905 3106.932
7973.828 4733.922 3157.762
1495.387 598.155 80.937
TOTAL ANNUAL COSTS
19886.469 11670.871 8295.098
349
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TABLE VIII-11
MULTIMEDIA FILTRATION
TREATMENT COSTS
System Plow Rate - liters/hr
(gals/day)
Investment
Annual Costs
Capital Costs
Depreciation
Operating and Maintenance Costs
(Excluding Energy and Power Costs)
Energy and Power Costs
29176. 11670. 3154.
(185000.) (74000.) (20000.)
46439.742 40997.281 40997.281
2913.906 2572.414 2572.414
4643.973 4099.727 4099.727
7093.230 6064.945 6064.949
332.302 284.130 284.130
TOTAL ANNUAL COSTS
14983.410 13021.215 13021.219
350
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TABLE VIII-12
MEMBRANE FILTRATION
TREATMENT COSTS
System Flow Rate - liters/hr
(gals/day)
Investment.
Annual Costs
Capital Costs
Depreciation
Operating and Maintenance Costs
(Excluding Energy and Power Costs)
Energy and Power Costs
29176. 11670. 3154.
(185000.) (74000.) (20000.)
404894.000 161957.500 43772.336
25405.414 10162.184 2746.539
40489.398 16195.750 4377.230
4111.840 3703,931 3505.489
2714.417 2714.417 2714.417
TOTAL ANNUAL COSTS
72721.000 32776.277 13343.672
351
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TABLE VIII-13
ULTRAFILTRATION
TREATMENT COSTS
System Flow Rate - liters/hr
(gals/day)
Investment
Annual Costs
Capital Costs
Depreciation
Operating and Maintenance Costs
(Excluding Energy and Power Costs)
Energy and Power Costs
29176. 11670. 3154.
(185000.) (74000.) (20000.)
554999.000 221999.562 82285.500
34823.914 13929.590 5163.074
55499.898 22199.953 8228.547
114374.562 57493.914 25418.340
7542.590 3017.035 815.415
TOTAL ANNUAL COSTS
212240.937 96640.437 39625.375
352
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TABLE VIII-14
VACUUM FILTRATION
TREATMENT COSTS
System Flow Rate - liters/hr
(gals/day) ,
Investment
Annual Costs
Capital Costs
Depreciation
Operating and Maintenance Costs
(Excluding Energy and Power Costs)
Energy and Power Costs
252.
(1600.)
104.
(660.)
28.
(177.)
25218.168 25218.168 25218.168
1582.332 1582.336 1582.328
. 2521.817 2521.817 2521.817
7067.633 5677.867 4391.320
1242.477 1242.477 1242.477
TOTAL ANNUAL COSTS
12414.258 11024.496 9737.941
353
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TABLE VIII-15 1
COOLING TOWER COSTS
System Plow Rate - liters/hr
(gals/day)
Investment
Annual Costs
Capital Costs
Depreciation
Operating and Maintenance Costs
(Excluding Energy and Power Costs)
Energy and Power Costs
TOTAL ANNUAL COSTS
3154
(20000)
3116
196
312
1663
268
2439
9463
(60000)
4484
281
448
1663
493
2886
19871
(129000)
6114
383
611
1663
869
3528
354
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TABLE VIII-16
BPT COSTS
NORMAL PLANT
System Flow Rate -
liters/hr
Least Cost Operation Mode
Investment
Annual Costs
Capital Costs
Depreciation
Steel
5377
Batch
372887
23397
37289
Galvanized Aluminum
Operation and Maintenance Costs
(Excluding Energy
and Power Costs) 35623
Energy and Power Costs
TOTAL ANNUAL COSTS
1960
98269
4811
Batch
369384
23177
36938
32876
1924
94916
15670
Continuous
500723
31418
50072
73962
2667
158121
355
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TABLE VIII—17
BAT 1 COSTS
(PROMULGATED OPTION)
NORMAL PLANT
System Flow Rate -
liters/hr
Least Cost Operation Mode
Investment
Annual Costs
Capital Costs
Depreciation
Operation and Maintenance Costs
(Excluding Energy
and Power Costs)
Energy and Power Costs
TOTAL ANNUAL COSTS
Steel
2292
Batch
305033!
19139
30503
26043
1663
77350
Galvanized Aluminum
1651
Batch
288061
18075
28806
23776
1636
72292
4599
Batch
355703
22319
35570
43506
1761
103157
356
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TABLE VIII-18
BAT 2 COSTS
NORMAL PLANT
System Flow Rate -
liters/hr
Least Cost Operation Mode
Investment
Annual Costs
Capital Costs
Depreciation
Steel
2292
Batch
311017
20017
31101
Operation and Maintenance Costs
(Excluding Energy
and Power Costs) 26043
Energy and Power Costs
TOTAL ANNUAL COSTS
1663
78824
Galvanized
1651
Batch
293034
18805
29303
23776
1636
73520
Aluminum
4599
Continuous
364941
23627
36461
43506
J.761
105355
357
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TABLE VIII-19
NSPS COSTS
NORMAL PLANT
System Flow Rate -
Liters/hr
Least Cost Operation Mode
Investment
Annual Costs
Capital Costs
Depreciation
Steel
6i7
Batch
171516
11672
17152
Galvanized Aluminum
Operation and Maintenance Costs
(Excluding Energy
and Power Costs) 22416
Energy and Power Costs
TOTAL ANNUAL COSTS
47
51287
632
Batch
172525
11738
17253
22726
48
51765
2213
Batch
316802
20507
31680
35764
1660
89611
358
-------
SIMPLIFIED LOGIC DIAGRAM
SYSTEM COST ESTIMATION PROGRAM
(NOT WITHIN
TOLERANCE LIMITS)
(RECYCLE SYSTEMS)
NON-RECYCLE
SYSTEMS
(WITHIN TOLERANCE LIMITS)
OUTPUT
STREAM DESCRIPTIONS -
COMPLETE SYSTEM
INDIVIDUAL PROCESS SIZE AND
COSTS
OVERALL SYSTEM INVESTMENT
AND ANNUAL COSTS
CONVERGENCE
A) POLLUTANT PARAMETER
TOLERANCE CHECK
COST CALCULATIONS
A) SUM INDIVIDUAL PROCESS
COSTS
B) ADD SUBSIDIARY COSTS
C) ADJUST TO DESIRED DOLLAR BASE
INPUT
RAW WASTE DESCRIPTION
SYSTEM DESCRIPTION
"DECISION" PARAMETERS
COST FACTORS
PROCESS CALCULATIONS
A) PERFORMANCE - POLLUTANT
PARAMETER EFFECTS.
B) EQUIPMENT SIZE
C) PROCESS COST
FIGURE VIII-1. COST ESTIMATION PROGRAM
359
-------
4.0 MG/L CYANIDE
0.1 MG/L CYANIDE
CONTINUOUS
4.0 MG/L CYANIDE""
0.1 MG/L CYANIDE
BATCH
100,000
too
10,000
1,000
10
I
FLOW RATE TO CYANIDE OXIDATION (GPH)
FIGURE VIII-2. CHEMICAL OXIDATION OF CYANIDE CAPITAL COST
-------
3.785 37.85 378.5 3785 37850
FLOW RATE TO CYANIDE OXIDATION (1/HR)
FIGURE VIH-3. CHEMICAL OXIDATION OF CYANIDE ANNUAL LABOR REQUIREMENTS
-------
10,000
00
CTl
ro
co
fN
Z
<
-i
l
K
w
I"
UJ
O
U
J
<
3
Z
Z
<
1,000
4.0 MG/L CYANIDE)
CHEMICALS
CHEMICALS
[O.t MG/L CYANIDE
100
100 1,000
FLOW RATE TO CYANIDE OXIDATION (GPH)
10,000
100,000
FIGURE Vlll-4. CHEMICAL OXIDATION OF CYANIDE CHEMICAL AND ENERGY COST
-------
I
1
CONTINUOUS
BATCH
1
1
100,000
10,000
100
1,000
I
10
FLOW RATE TO CHROMIUM REDUCTION (GPH)
FIGURE VIII-5. CHEMICAL REDUCTION OF CHROMIUM CAPITAL COST
-------
—A
/
/
/
/
r
1
3A
T
C
4
OPERA"
rioM
)-
j
1
~
/
/
—J
/
i
y
F
/
/
/
•
<
:ontini
IOUS
(O
PE
Ri
*i
o
.
/
/
Ml
4IMI
IM
:o
N'
ri
N
U
DUS PRC
CES
i M
Al
"E
N
A
NCE
/
/
/
1
H
s
—y~
/
/
(MAINTENANCE)
y
s
A
4
f
/
r
E
A'
r<
*
i f
riAINTEr
JANC
:e
0
H
R
;
/
/
1 10 too 1,000 10,000 100,000
FLOW RATE - GPH
FIGURE VI11-6. CHEMICAL REDUCTION OF CHROMIUM ANNUAL LABOR REQUIREMENTS
-------
0«
100,000
10,000
100 1,000
FLOW RATE TO OIL SKIMMER (GPH)
FIGURE VIII-7. OIL SKIMMER CAPITAL COST
-------
10"
CO
CTl
«
c
3
0
z
1
K
0
CD
«
J
<
3
Z
Z
<
10J
10'
10'
-
-
4
4
~
A
\
rs
1"
'ENANC
E\
(
»
E
F
i
lTION «
10
100 1,000
FLOW RATE — GPH
10,000
100,000
FIGURE VIII-8. OIL SKIMMER ANNUAL LABOR REQUIREMENTS
-------
100,000*
CO
oi
z
<
7 io.ooo
H
n
O
U
J
<
u
K
0
t-
<
J
3
U
u
o
J
k.
1,000
too
—
I
i
i !
¦X
i
—
-
i
t
1
10
too 1,000
FLOW RATE TO CLARIFIER - GPH
10,000
FIGURE VIII- 9. FLOCCULATOR CAPITAL COST
-------
r
|
o
1 T
K
gill
ED
All
r
r>
MATIC
CUT-OFF
aC
51
IV
1
>1 1
1
1
1
i
1
I
|
,
1
1
I
i
1
1
¦
1
¦
1
-
- ----
--
1
I
1
I
i
1
1
1
1
1 10 100 1,000 10,000 100,000
FLOW RATE TO CLARIFIER (GPH)
FIGURE VIII-10. CLARIFICATION CAPITAL COST FOR CONTINUOUS OPERATION
-------
10'
CO
CTl
<£>
m 105
z
<.
¦n
I
s.
I- -
«
O
u
J
<
H
& -
<
W I04
10-
10
100 1,000
FLOW RATE TO CLARIPIER (GPH)
JD<
;e
PI
Jl
11
>
s
OST EX
:lu
)Et
- SLI
- FIELD
¦ N
4STALL
EQUIRE
LUATIO
rir
ATION :
R
D
10,000
100,000
FIGURE VIII-11. CLARIFICATION CAPITAL COST FOR BATCH OPERATION
-------
SL
JC
G
E
P
J
P COST
INC
.Ul
3E
3
f
*
(
:<
H
Z
c
0
US 1
RE
M
M
E
f
r
£
~
»
*
*
iA
rc
H
1
F
::
iATMEf
E
1
1-
lll~
I 10 100 1,000 10,000 100,
FLOW RATE TO CLARIFIER (GPH)
FIGURE VII1-12. CLARIFICATION COST SUMMARY
-------
£
<
LI
>•¦
0).
St
3
0
1
Z
<
2
800
700
600
500
400
300
200
too
•
MAI!
4TENAN
CE
0 10 20 30 40 50 60 70 80 90 100
FLOW RATE TO CLARIFIER
(THOUSAND GALLONS/HOUR)
FIGURE VIII-13. CLARIFICATION MAN HOUR REQUIREMENTS FOR CONTINUOUS
OPERATION
371
-------
C
A
PITAL COST (5)
TOT
AL
Ef
N AND
M AIT
"ITE
.Ni
\ IS
tt
(
/YR)
1 to 100 1,000 10,000 100,000
FLOW RATE TO FILTER (GPH)
FIGURE VIII-14. MULTIMEDIA FILTER COSTS
-------
} loo kooo
I
FLOW RATE TO ULTRAFILTRATION(GPH)
FIGURE VI11-15. ULTRAFILTRATION CAPITAL COST
-------
10,000
1,000
CO
"VI
-fc>
a
<
ui
*
to"
K
3
O
X
z
<
s
100
10
I
>F
E
IV
T
ION
S.
MA
\
NT
Ef
A
N
s
-
-
—
—
-
- - —
-
-
-
10
100 1,000
(GPH)
10,000
100,000
FIGURE VIII-16. ULTRAFILTRATION LABOR REQUIREMENTS
-------
10i
CO
en
00
5.0«
I
w
E
<
J
J
0
O
I-
(0
o
u
J
<
SI
<
u
£ 10"
10*
It
>0
0
,6»-(
gIu
_
-*®i
3o.°
c
SC
>*-
t
£
1
c
i*1-
•
10
100
10J
1 0
1 0 =
1 0*
FLOW RATE (GPH)
FIGURE VIII-17. VACUUM FILTRATION CAPITAL COST
-------
10s
w
-~j
G\
ct
<
Id
>-
t?T
K
3
0
c
0
0)
<
J
Q
Id
tt
5
a
u
tt
to*
10-
too
¦r
¦
•oi
'A!
^ j
11
£
P
S
NDED S
OLII
IS !
0,
)0
)
M
G
IU \
» TOT A
L SU
SPI
:n
31
E
!
SO
LIDS 30
,000
MG
/L
. .
to
too
1 0J
10"
10=
FLOW RATE (GPH)
FIGURE VIII-18. VACUUM FILTRATION LABOR REQUIREMENTS
-------
-
.....
X
1
¦OT
Al
. S
LI
SP
;nded s
3L.lt
S !
0,1
>0
) h
1G/
'U\
/
k TO
rAi
.s
us
iPE
:n
~ ED SOL
IDS
30, i
)0(
i K
1G
/L-
I 10 100 !03 to4 <0
FLOW RATE (GPH)
FIGURE VIII-19. VACUUM FILTRATION MATERIAL AND SUPPLY COST
-------
TOTAL SUSPENDED SOLIDS = 50,000 MG/L
TOTAL SUSPENDED SOLIDS = 30,000 MG/L
I0S
1
100
10
FLOW RATE (GPH)
FIGURE VI11-20. VACUUM FILTRATION ELECTRICAL COST
-------
I0«
1,000
100,000
I
10
too
10,000
FLOW RATE TO COOLING TOWERS (GPH)
FIGURE VIII-21. COOLING TOWER CAPITAL COST
-------
PUMP
FAN
100 1,000
FLOW RATE TO COOLING TOWER (GPH)
FIGURE VIII-22. COOLING TOWER ANNUAL ELECTRICAL COST
-------
equ;
T
XLIZ
ASiK
AT
l:
or
NE
n
R
rA
Af
N
K
it
INCLUDES
MIXER
F
ET
IN
n
)i
r
i
ME: 0.33 1
JAYS
103 104 105 106 to7
FLOW RATE TO EQUALIZATION TANK - (LPH)
FIGURE VIII—23. EQUALIZATION TANK INVESTMENT COSTS
-------
EQUALIZATION TANK INCLUDES
TANK LINER AND MIXER
RETENTION TIME: 0.33 DAYS
100
10J
10H
10°
10°
10'
FLOW RATE TO EQUALIZATION TANK - (LPH)
OPERATION: 24 HOURS/DAY
260 DAYS/YEAR
FIGURE VIII—24. EQUALIZATION TANK ENERGY COSTS
-------
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 three basis material subcategories.
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,
transferable 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 the coil coating operations to identify the
processes used and the wastewaters generated during coil coating.
Information was collected through previous work, dcp forms and
specific plant sampling and analysis. The Agency used this data
to subcategorize the operations and to determine what constituted
an appropriate BPT. Some of the salient considerations are:
The cleaning step of coil coating removes oil, dirt and
oxide coating, and generates alkaline or acid wastewaters
containing oils, dissolved metals and suspended solids.
The conversion coating and sealing wastewater generally is
acid in nature and contains dissolved metals, and suspended
solids.
383
-------
Quench wastewater which derives from cooling the paint
surface after drying typically is slightly alkaline and
contains small amounts of organics and suspended solids.
Of the 69 plants for which data was received: 49 have
hexavalent chromium reduction, 6 have cyanide treatment, 20
have oil skimming, 37 use chemical precipitation, 42 have
sedimentation by tank, lagoon, clarifier or tube or plate
settlers and 32 have sludge dewatering to assist in sludge
disposal.
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 in subcategorization and are
discussed fully in Section IV. Nonwater quality impacts and
energy requirements are considered in Section VIII.
Coil coating consists of three different sets of processes -
metal preparation, conversion coating, and painting. These
generate different wastewater streams. As Table IX-1 (page 393)
shows, the chemical makeup of these wastewaters is distinctly
different. In all three wastewater streams, as discussed in
Sections III and IV, the volume of wastewater is related to area
of material processed.
Cyanide compounds are used in some conversion coating
formulations applied to aluminum strip. This fact is reflected
in the high cyanide concentrations in rinse waters from aluminum
conversion coating. Although cyanides are not commonly used in
conversion coating formulations applied to steel and galvanized
strip, appreciable concentrations of cyanide appeared in the
conversion coating rinse streams from plants in the galvanized
subcategory which also coated steel and aluminum strip.
Apparently, cyanide from aluminum conversion coating operations
is not readily eliminated from the rinse system when the
production line is changed over to other metals. Therefore,
cyanide removal by precipitation is selected for conversion
coating dumps and rinses from all three subcategories.
The general approach to BPT for this category is to treat all
wastewaters in a single (combined) treatment system. Normal
practice is to combine wastewater for treatment because it is
less expensive. Oil which is removed from the strip during
alkaline cleaning must be removed from the wastewater, cyanide
from conversion coating operations • must be treated, and
hexavalent chromium 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,
384
-------
including the metal precipitate, removed. Segregation and
separate treatment of conversion coating wastewaters is necessary
to provide effective removal of cyanide and reduction of
hexavalent chromium. Therefore, the strategy for BPT is to treat
cyanide and reduce hexavalent chromium in conversion coating
wastewaters; combine all wastewater streams and apply oil
skimming to remove oil and grease and some organics; and follow
or combine with lime and settle technology to remove metals and
solids from the combined wastewaters. (See Figure IX-1, page
400). Some slight modification may be necessary in specific
subcategories but the overall treatment strategy is applicable
throughout this category. Although flows of wastewater differ
from subcategory to subcategory and result in different mass
limitations for each subcategory, the same treatment is
applicable and equally effective on all subcategory wastewater
streams.
Most of the coil coating plants sampled by EPA appear to have
elements of the proposed BPT system already in place; however,
observations by sampling teams and results of effluent analyses
(presented in each subcategory) suggest that most treatment
systems are not properly operated. Hardware systems are
in-place, but operating instructions are not consistently or
adequately followed. The result is universally inadequate
treatment system effectiveness for the category. Treatment
effectiveness data must therefore be transferred. Some plant
sampling days for this category show performance equivalent to
that of the combined metals data base as shown in Tables V-33, 35
and 3 7 which demonstrates the appropriateness of using the larger
treatment effectiveness data base compiled from a number of
categories with similar wastewater. Data from 11 coil coating
plants are included in the combined metals data base.
SELECTION OF POLLUTANT PARAMETERS FOR REGULATION
The pollutant parameters selected for regulation in the coil
coating category were selected because of their frequent presence
at treatable concentrations in wastewaters from the three
subcategories. In addition to oil and grease, TSS, and pH,
metals are regulated in each subcategory. Also cyanide is
regulated in each subcategory with an exemption procedure
provided. If a plant demonstrates and certifies that it neither
has nor uses cyanide in its processes and will not initiate such
use, it may be exempt from the requirement of monitoring cyanide.
This procedure is a change from the proposal. Table VII-21 (page
271) summarizes the BPT treatment system effectiveness for all
pollutant parameters regulated in the coil coating category.
385
-------
The importance of pH control is stressed in Section VII and its
importance for metals removal cannot be overemphasized. Even
small excursions away from the optimum level can result in less
than optimum functioning of the system. Study of plant effluent
data presented for each subcategory shows the importance of pH.
The pH level may shift slightly from the optimum range (8.7
9.2) if wastewater composition differs appreciably from that of
wastewaters studied. Therefore, the regulated pH is specified to
be within a range of 7.5 - 10.0 (instead of 6.0 - 9.0) to
accommodate the optimum level without the necessity for a final
pH adjustment.
STEEL SUBCATEGORY
The BPT treatment train for steel subcategory wastewater consists
of chromium reduction and cyanide removal for the segregated
wastewaters from the conversion coating operation; mixing and pH
adjustment, with lime or acid, of the combined wastewaters to
precipitate metals; oil skimming to remove oil and grease and
organics; and settling to remove suspended solids and
precipitated metals.
Wastewater generated in the steel subcategory was calculated from
all dcp data because dcp responses provide a more extensive data
base than visited plants. Production normalized mean water use
for the steel subcategory is 2.752 1/sq m processed area as set
forth in Table V-12 (page 84) which is 93 percent of the proposed
wastewater allowance.
Plants with production normalized flows significantly above the
mean flow used in calculating the BPT limitations will need to
reduce these flows to meet the BPT limitations. This reduction
can usually be made at no significant cost by correcting obvious
excessive water use practices (such as leaking rinse tanks) or by
shutting off flows to rinses when they are not in use and
installing flow control valves on rinse tanks. Specific water
conservation practices applicable to reducing excess water are
detailed in Section VII.
The typical characteristics of wastewaters from the cleaning and
conversion coating operations in the steel subcategory, and for
quench operations for the coil coating category are given in
Tables V-28, V-29, and V-30 (pages TOO, 101, and 102). Typical
characteristics of total raw wastewater for the steel subcategory
are given in Table V-31 (page 103). Table VI-1 (page 174) lists
the non-conventional pollutants that were considered in setting
effluent limitations for this subcategory. Regulated pollutants
at BPT include chromium, cyanide, zinc, iron, oil and grease,
TSS, and pH, cadmium, copper, lead and nickel, proposed for
386
-------
regulation/ are not included at promulgation. Other pollutants
listed, in Table VI-1 are not specifically regulated at BPT.
However, if the regulated pollutants are removed to the
appropriate levels, the other pollutants will be adequately
removed coincidentally. Lime and settle technology combined with
oil skimming should 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 pollutant allowed to be
discharged per unit area prepared and coated can be calculated.
Table IX-2 (page 394) shows the limitations derived from this
calculation. Total wastewater values are based on a typical coil
coating operation where the strip is cleaned, conversion coated,
and painted once.
The derivation of one limitation is presented below in reverse
order so that the individual numerical steps in arriving at the
limitations can be seen. The steel subcategory BPT maximum for
any one day for chromium is 1.156 mg/m2. This number is the
product of the one day maximum chromium concentration for lime
and settle treatment which is 0.42 mg/1, (Table VII-21) and the
mean dcp steel subcategory water use which is 2.752 1/m2 (Table
V-12). The one day maximum chromium value was developed in
Section VII. The mean water use is the mean of the steel
subcategory water uses (presented in Table V-6). Each of these
individual water uses was calculated by dividing the yearly water
used in a plant by the total production (two sides of coil) for
that year (dcp's and Section V). At proposal, the median
production normalized flow was used as the regulatory flow. the
Agency is using the mean rather than the median for the
production normalized flow because the mean more accurately
characterizes water use practices in the category.
To determine the reasonableness of these limitations, EPA
examined data for the regulated pollutant parameters from the
sampled plants (Table IX-3, page 395) to determine how many
plants were meeting this BPT. These data indicate that, no
plants were meeting all the BPT mass limitations; however, values
for one plant sampling day (11058-1) met all the limitations and
more than half of the values from all sampling days are within
the limitations for each pollutant parameter except pH and oil
and grease. On four additional sampling days (11055-1, 36056-1,
36056-2 and 36056-3), all but one of the values were within the
proposed limitation on each day. Viewed as a group, the 34
effluent values for the five sampling days with best performance
(including three plants) included only 4 values outside the
limitations 2 for- oil and grease and 2 for pH. Of particular
387
-------
note is the fact that all 15 metals values were within the
limitations and that all pH values were 8.0 or greater.
EPA also examined the effect of pH on the sampled plants' data.
On one plant sampling day (46050-1) where TSS limitations were
met, but where the pH was below 7.5, all 3 of the regulated
metals values exceeded the limitations. On two other plant
sampling days (11058-2 and 12052-2) where TSS values were at
least double the limitation and where the pH was below 7.5 all 5
of the reported values for regulated metals exceeded the
limitations. Correction of the pH to a more normal level in the
range of 7.8 to 8.3 would be expected to bring the plant
performances into conformance with the BPT Limitations.
Proposed oil and grease limitations can be met with properly
operated oil skimmers, and proposed metals and TSS limitations
can be met with pH adjustment and settling. Table VII-11
demonstrates that oil skimming can remove oil and grease to the
regulated levels. The need for close pH control is illustrated
by the effluent data. When pH falls below the lower limit,
metals are not removed. At pH's above the upper limit,metals
that became soluble as oxygenated anions return to solution.
Therefore, the promulgated limitations (Table IX-2) for the steel
subcategory are reasonable.
In the establishment of BPT, the cost of application of
technology must be considered in relation to the effluent
reduction benefits from such application. The quantity of
pollutants removed by BPT is displayed in Table X-17 (page 425)
and the total cost of application of BPT is shown in Table X-18
(page 426). The capital cost of BPT as an increment above the
cost of in-place treatment equipment is estimated to be
$2,321/000 for the steel subcategory. Annual cost of BPT for the
steel subcategory is estimated to be $858,000. The quantity of
pollutants removed by the BPT system for this subcategory is
estimated to be 233,889 kg/yr, including 6,690 kg/yr of toxic
pollutants. The effluent reduction benefit is worth the dollar
cost of required BPT.
GALVANIZED SUBCATEGORY
The BPT treatment train for galvanized subcategory wastewater
consists of chromium reduction and cyanide removal for the
segregated wastewaters from the conversion coating operation;
mixing and pH adjustment of the combined wastewaters with lime or
acid to precipitate metals; oil skimming to remove oil and grease
and some organics; and settling to remove suspended solids and
precipitated metals.
388
-------
Wastewater generated in the galvanized subcategory was calculated
from all dcp data because dcp responses provide a more extensive
data base than visited plants. Production normalized mean water
use for the galvanized subcategory is 2.610 1/sq m processed area
as set forth in Table V-12 (page 84) which is 78 percent of the
proposed wastewater allowance.
Plants with production normalized flows significantly above the
mean flow used in calculating the BPT limitations will need to
reduce these flows to meet the BPT limitations. This reduction
can usually be made at no significant cost by correcting obvious
excessive water use practices (such as leaking rinse tanks) or by
shutting off flows to rinses when they are not in use and
installing flow control values on rinse tanks. Specific water
conservation practices applicable to reducing excess water are
detailed in Section VII.
The typical characteristics of wastewaters from the cleaning and
conversion coating operations in the galvanized subcategory, and
for quench operations for the total coil coating category are
shown in Tables V-28, V-29, V-30. Typical characteristics of
total raw wastewater for the galvanized subcategory are in Table
V-31. Tables VI-2 and VI-4 list the pollutants that were
considered in setting effluent limitations for this subcategory.
Regulated pollutants at BPT include chromium, copper, cyanide,
zinc, iron, oil and grease, TSS, and pH, cadmium, lead, and
nickel, proposed for regulation, are not included at
promulgation. Other pollutants listed in Table VI-2 and VI-4 are
not specifically regulated at BPT. However, if the regulated
pollutants are removed to the appropriate levels, the other
pollutants will be adequately removed coincidentally. The
combination of lime and settle technology with oil skimming
should 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 pollutant allowed to be
discharged per unit area prepared and coated can be calculated.
Table IX-4 shows the limitations derived from this calculation.
Total wastewater values are based on a typical coil coating
operation where the strip is cleaned, conversion coated, and
painted once.
To determine the reasonableness of these limitations, EPA
examined data for regulated pollutant parameters from the sampled
plants (Table IX-5, page 397) to determine how many plants were
meeting this BPT. Values for three sampling day (11058-1,
389
-------
33056-1 and 33056-2) met all limitations; values for one
additional sampling day (38053-1) met all limitations except pH;
a third sampling days {38053-3 and 4-6050-3) had pH and one metal
value outside of the limitation. Thus for six sampling days with
48 reported values for regulated pollutant parameters, only 4 of
the values, including 2 pH values, exceeded the limitations. TSS
was 31.72 mg/sq m or less, showing effective solids removal. The
remaining eight sampling days with 64 reported values for
regulated metals can be examined in two groups of four and one
group (36058-2, 38053-2, 46050-2, and 46050-3) with 12 metals
values had low pH for each sampling day and 7 metal values
exceeded the limitation. The second group (11058-2, 12052-1,
12052-2, and 12052-3) had TSS values from 2 times the limitations
and all 11 reported values for regulated metals exceed the
limitations. Correction of the pH to a more normal level in the
range of 7.8-8.3 would be expected to bring plant performances
into conformance with the BPT limitations.
Oil and grease limitations can be met with properly operated oil
skimmers (see Table VII-11) and metals and TSS limitations can be
met with pH adjustment and settling. The need for close pH
control is illustrated by the effluent data. 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. Therefore, the promulgated limitations (Table IX-4)
for the galvanized subcategory are reasonable.
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-17 and the total cost (1978
dollars) of application of BPT is shown in Table X-18. The
capital cost of BPT as an increment above the cost of in-place
treatment equipment is estimated to be $231,000 for the
galvanized subcategory. Annual cost of BPT for the galvanized
subcategory is estimated to be $86,000. The quantity of
pollutants removed above raw waste by the BPT system for this
subcategory is estimated to be 121,720 kg/yr, including 7,484
kg/yr of toxic pollutants. EPA believes that the effluent
reduction benefit outweighs the dollar cost of required BPT.
ALUMINUM SUBCATEGORY
The BPT treatment train for aluminum subcategory wastewater
consists of chromium reduction and cyanide precipitation for the
segregated wastewaters from the conversion coating operation;
mixing and pH adjustment of the combined wastewaters with lime or
acid to precipitate metals; oil skimming to remove oil and grease
390
-------
plus some organics; and settling to remove suspended solids plus
precipitated metals.
Wastewater generated in -the aluminum subcategory was calculated
from all dcp data because dcp responses provide a more extensive
data- base than visited plants. Production normalized mean water
use for the aluminum subcategory is 3.363 1/sq m processed area
as set forth in Table V-12 (page 84) which is 117 percent of the
proposed wastewater allowance.
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. This reduction can
usually be made at no significant cost by correcting obvious
excessive water use practices (such as leaking rinse tanks) or by
shutting off flows to rinses when they are not in use and
installing flow control valves on rinse tanks. Specific water
conservation practices applicable to reducing excess water are
detailed in Section VII.
The typical characteristics of wastewaters from the cleaning and
conversion coating operations in the aluminum subcategory, and
from quench operations for the total coil coating category are
shown in Tables V-28, V-29, and V-30. Typical characteristics of
total raw wastewater for the aluminum subcategory are in Table V-
31. Tables VI-3 and VI-4 list the pollutants that should be
considered in setting effluent limitations for this subcategory.
The regulated pollutants at BPT include chromium, cyanide, zinc,
aluminum, oil and grease, TSS and pH, lead, cadmium, copper,
nickel and iron, proposed for regulation, are not included at
promulgation. Other pollutants listed in Table VI-3 and VI-4 are
not specifically regulated at BPT. However, if the regulated
pollutants are removed to the appropriate levels, the other
pollutants will be adequately removed coincidentally. The
combination of lime and settle technology with oil skimming
should reduce the concentration of regulated pollutants to the
levels described in Table VI1—21. The pH must be maintained
within the range 7.5 - 10.0 at all times.
When these concentrations are applied to the dcp mean wastewater
flow described above, the mass of pollutants allowed to be
discharged per unit area prepared and coated can be calculated.
Table IX-6 shows the limitations derived from this calculation.
Total wastewater values are based on a typical coil coating
operation where the strip is cleaned, conversion coated, and
painted once.
To determine the reasonableness of these limitations, EPA
reviewed the data for regulated pollutant from the sampled plants
-------
Table IX-7, page 379} to determine how many plants were meeting
this BPT. The effluent values for all pollutant parameters with
within the limitations for one sampling day (01054-3) and all
parameters except pH were within the limitations on two sampling
days (01054-1 and 01054-2) An additional 12 sampling days
(including four plants) had 53 of 84 effluent values within the
limitations. One plant (40064) had no solids removal facilities
in the wastewater treatment system.
Oil and grease limitations can be met with properly operated oil
skimmers (see Table VII-11) and metals and TSS Limitations can be
met with pH adjustment and settling. The need for close pH
control is illustrated by the effluent data. 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. Therefore, the promulgated limitations (Table IX-6)
for the aluminum subcategory are reasonable.
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-17 and the total cost of
application of BPT is shown in Table X-18. The capital cost of
BPT as an increment above the cost of in-place treatment
equipment is estimated to be $4,429,000 for the aluminum
subcategory. Annual cost of BPT for the aluminum subcategory is
estimated to be $1,722,000. The quantity of pollutants removed
above raw waste by the BPT system for this subcategory is
estimated to be 633,138 kg/yr including 98,916 kg/yr of toxic
pollutants. EPA believes that the effluent reduction benefit
outweighs the dollar cost of required BPT.
392
-------
tobte IX-1
SMOT TABLE
WBSTBPKfflER OmmCIERISHCS FOR COIL CQKHNS CKEB30K3f
(Median Value)
Process Operation Cleaning
Subcategory
Flew 1/a?
Conversion
Coating
Quenching
Ccrttoined
Wastewater
Steal Galvanized Abminum Steel Galvanized Mtsnimm Steel Galvanized Muminum Steel Galvanized Aluninum
.2.274
1.368 0.964
0.421
0.528 0.546
3.632
3.632 3.632
6.33
5.53
5.14
Parameter (mg/1)
118 Cacknim 0.004 0.040 0.003 0.006 0.010 0.008 0.014 0.014 0.014 0.001 0.045 0.004
119 Chromium 0.182 0.270 0.180 71.081 0.200 117.500 0.013 0.013 0.013 6.865 57.5% 43.500
120 Ct^per 0.059 0.020 0.075 0.032 0.018 0.052 0.006 0.006 0.006 0.015 0.009 0.430
121 Cyanide
122 Lead
124 Nickel
0.024
0.457
0.039
0.017
1.950
0.150
0.010
0.170
0.000
0.092
0.480
6.762
0.200
0.500
4.430
2.570
0.285
0.108
0.021
0.048
0.190
0.021
0.048
0.190
0.021
0.048
0.190
0.012
0.142
0.392
0.082
0.422
0.395
0.568
0.118
0.028
128
Zinc
TcsdLc Grganics
3.200
0.579
85.300
0.516
0.210
0.145
51.264
1.035
73.350
0.183
0.540
0.213
0.150
0.480
0.150
0.480
0.150
0.480
7.588
1.344
25.489
0.201
0.200
0.140
Aluminum 0.340 1.300 251.500 1.190 2.310 107.500 1.025 1.025 1.025 0.607 1.741 112.212
Iron 5.200 1.025 0.275 9.234 5.050 7.815 0.136 0.136 0.136 10.145 2.829 3.448
Phosftarous 42.300 32.600 90.400 43.400 25.100 14.500 0.780 0.780 0.780 42.974 14.758 7.000
Oil & Grease 261.00 107.500 75.000 6.600 10.500 2.000 5.000 5.000
TSS 256.00 162.000 49.000 133.500 190.000 55.000 5.000 5.000
5.000 341.650
5.000 152.791
52.965
114.053
57.561
84.884
-------
TABLE IX-2
BPT EFFLUENT LIMITATIONS
STEEL SUBCATEGORY
POLLUTANT OR
POLLUTANT MAXIMUM FOR MAXIMUM FOR
PROPERTY ANY ONE DAY MONTHLY AVERAGE
mg/m^
(lb/1,000,000
ft^) mg/m^
(lb/1,000,0
CADMIUM
0.881
(0.180)
0.413
(0.085)
*CHROMIUM
1.156
(0.237)
0.468
(0.096)
COPPER
5.229
(1.071)
2.752
(0.564)
~CYANIDE
0.798
(0.163)
0.330
(0.068)
LEAD
0.413
(0.085)
0.358
(0.073)
NICKEL
3.880
(0.795)
2.752
(0.564)
~ZINC
3.660
(0.750)
1.541
(0.316)
~IRON
3.385
(0.693)
1.734
(0.355)
~OIL & GREASE
55.040
. (11.273)
33.024
(6.764)
~TSS .
112.832
(23.110)
55.040
(11.273)
~pH
WITHIN
THE RANGE OF
7.5 TO 10.0 AT
ALL TIMES
* THIS POLLUTANT IS REGULATED AT PROMULGATION
394
-------
TBBIE IX-3
PRODXTCION NOBMMIZED EFETUENT MASS
9IEEL SJBCKMXm (mg/m2)
Pollutant Plant ID - Sanpling Day
Parameter 11055-1 11058-1 11058-2 12052-2 12052-3 36056-1 36056-2 36056-3 36058-1 36058-3 36058-4 46050-1 46050-2
Cadmium
0.011
0.00
0.00
*
.*
0.00
0.00
—
0.296
—
0.00
0.00
0.00
Chromium
0.273
0.659
1.833
14.25
0.703
1.020
1.068
0.492
0.065
0.324
0.615
1.284
0.692
Cyanide
0.00
0.00
0.00
0.693
0.190
0.00
0.001
0.00
0.00
0.00
0.351
0.089
Lead
0.164
0.00
0.00
2.215
0.626
0.008
0.006
0.005
0.00
—
0.00
0.314
0.207
Nickel
0.176
0.00
0.00
0.385
*
0.016
*
0.00
0.00
0.00
0.00
3.622
5.30
Zinc
0.757
0.528
3.856
120.4
37.52
0.144
0.167
0.127
3.874
4.050
9.82
27.09
32.25
Iron
0.00
1.243
—-
77.7
37.90
0.346
0.370
0.366
13.02
16.07
26.18
3.615
3.369
Oil & Grease
9.69
11.30
59.2
220.7
79.1
24.40
75.6
122.0
0.00
772.
115.2
150.2
107.5
TSS
46.93
32.03
225.3
376.2
305.5
46.25
107.4
68.4
667. '
—
—-
49.91
68.0
EH
8.0-11.1
8.3-9.5
6.9-8.6
7.4-10.8
7.1-10.0
8.5-10.8
8 0-9.0
8.0-8.9
2.0-9.1
2.7-10.7
2.7-10.7
6.7-7.3
6.7-7.3
*Possibly detected but below the detection limit.
-------
TABLE IX-4
BPT EFFLUENT LIMITATIONS
GALVANIZED SUBCATEGORY
POLLUTANT OR
POLLUTANT
PROPERTY
MAXIMUM FOR
ANY ONE DAY
MAXIMUM FOR
MONTHLY AVERAGE
mg/m2
(lb/1,000,000
ft2)
mg/m2
(lb/1,000,0
CADMIUM
0.835
(0.171)
0.392
(0.080)
~CHROMIUM
1.096
(0.224)
0.444
(0.091)
~COPPER
4.959
(1.016)
2.610
(0.535)
~CYANIDE
0.757
(0.155)
0.313
(0.064)
LEAD
0.392
(0.080)
0.339
(0.069)
NICKEL
3.680
(0.754)
2.610
(0.535)
~55 INC
3.471
(0.711)
1.462
(0.299)
~IRON
3.210
(0.657)
1.644
(0.337)
~OIL & GREASE
52.200
• (10.691)
31.320
(6.415)
~TSS
107.010
(21.917)
52.200
(10.691)
~pH
WITHIN
THE RANGE OF
7.5 TO
10.0 AT
ALL TIMES
* THIS POLLUTANT IS REGULATED AT PROMULGATION
396
-------
TftBLE IX-5
PHUUCriCN NCBMRUZED EBTLUENT fftSS
GMJffiNIZED SUBCMEGORY (mg/m2)
Pollutant Plant ID - Sairpling lay
Parameter
11058-1
11058-2
12052-1
12052-2
12052-3
33056-1
33056-2
36058-2
38053-1
38053-2
38053-3
46050-3
Cadmium
0.00
0.00
1.389
*
*
0.00
0.044
0.00
0.00
0.00
0.00
0.00
Chromium
0.653
1.956
119.1
9.03
1.151
0.589
0.106
0.372
0.177
2.978
0.435
0.128
Copper
0.013
0.022
0.075
0.049
0.059
0.00
0.00
0.079
0.003
0.00
0.00
0.012
Cyanide
0.00
0.00
0.622
0.439
0.311
0.106
0.095
0.00
0.00
0.00
0.00
0.478
Lead
0.00
0.00
3.454
1.421
1.025
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Nickel
0.00
0.00
5.212
0.244
0.025
0.082
0.00
0.00
0.00
0.007
0.035
5.53
Zinc
0.522
4.117
432.7
76.25
61.4
0.353
0.096
5.93
0.361
3.805
3.757
5.13
Iron
1.232
-
52.2
49.23
62.1
1.178
1.852
15.82
0.200
0.142
0.284
1.981
Oil & Grease
11.20
63.2
192.2
139.8
129.5
21.20
22.22
69.6
8.00
11.56
5.48
43.45
TSS
31.72
240.5
3014.
238.3
500.
7.07
'21.16
—
19.35
24.00
23.47
70.02
EH
8.3-9.5
6.9-8.6
7.0-10.7
7.4-11.6
6.8-11.5 7.5-7.5
7.5-7.5
3.9-9.2
7.1-11.5
6.5-9.1
4.3-9.4
6.7-7.3
*Possihly detected but below the detection limit.
-------
TABLE IX-6
BPT EFFLUENT LIMITATIONS
ALUMINUM SUBCATEGORY
POLLUTANT OR
POLLUTANT MAXIMUM FOR MAXIMUM FOR
PROPERTY ANY ONE DAY MONTHLY AVERAGE
mg/m^ (lb/1/000/000 ft2) mg/m^ (lb/1/000/000 ft^)
CADMIUM
1.076
(0.220)
0.504
(0.103)
~CHROMIUM
1.412
(0.289)
0.572
(0.117)
COPPER
6.390
(1.309)
3.363
(0.689)
~CYANIDE
0.975
(0.200)
0.404
(0.083)
LEAD
0.504
(0.103)
0.437
(0.090)
NICKEL
4.742
(0.971)
3.363
(0.689)
~ZINC
4.473
(0.916)
1.883
(0.386)
~ALUMINUM
15.302
' (3.134)
6.255
(1.281)
IRON
4.136
(0.847)
2.119
(0.434)
~OIL & GREASE
67.260
(13.776)
40.356
(8.266)
~TSS
137.883
(28.241)
67.260
(13.776)
~pH
WITHIN
THE RANGE OF 7.5
TO 10.0 AT
ALL TIMES
* THIS POLLUTANT IS REGULATED AT PROMULGATION
398
-------
TABLE Ei-7
PRXUCTICK NSMMJZED EETOUENT I©SS
AUUMTNtM SUBCMSOCKT (mg/m2)
Pollutant
Parameter
01054-1
01054-2
Plant ID - Sampling Day
01054-3
01057-1
01057-2
01057-3
13029-1
13029-2
Cadmium
Chromium
Cyanide
0.Q0
0.257
0.018
0.00
0.113
0.012
0.00
0.030
0.002
0.00
*
0.093
0,025
4c
0.100
0.045
0.00
0.056
0.00
8.23
0.00
0.00
3.043
0.00
Lead
Nickel
Zinc
0.01?
0.00
0.135
0.022
0.00
0.648
0.020
0.00
0.966
0.00
0.00
1.275
0.00
0.00
1.365
0.00
0.00
4.068
0.00
0.00
0.819
0.00
0.00
0.201
Aluminum
Iron
Oil & Grease
0.893
0.262
0.902
0.612
0.009
2.184
0.504
0.008
0.900
17.89
0.703
35.77
45.27
0.970
26.88
40.85
0.511
55.6
11.21
0.645
26.78
5.98
0.145
29.78
TSS
pH
46.45
6.9-7.9
35.31
7.0-8.1
3.900
7.8-8.2
14.45
6.4-8.4
87.60
6.5-8.4
51.7
6.3-8.5
127.5
7.7-8.6
45.36
7.7-8.7
Pollutant
Parameter
13029-3
15436-1
Plant ID - Sanpling Day
15436-2
15436-3
40064-1
40064-2
40064-3
Cadmiun
Chromium
Cyanide
0.00
11.19
0.00
0.00
1.760
0.00
3.419
0.00
0.00
2.898
0.00
283.7
3.124
0.013
519.
3.066
*
251.6
2.327
Lead
Nickel
Zinc
0.00
0.00
0.307
0.00
0.00
0.048
0.00
0.254
0.00
0.00
0.061
0.593
0.083
0.714
1.298
0.171
1.942
0.580
0.00
0.693
Aluminum
Iron
Oil & Grease
14.13
0.259
16.05
0.00
0.00
4.224
12.80
1.087
2.416
11.03
0.849
1.749
176.1
87.0
4.212
138.1
181.3
1.118
157.8
88.4
9.80
TSS
117.7
7.7-8.5
139.0
7.2-9.0
62.8
7.2-7.5
64.9
7.7-7.7
2256.
6.3-11.2
6717.
4.9-11.3
1931.
3.4-11.9
*Possibly detected but below the detection limit.
-------
CHEMICAL
CHEMICAL ADDITION
CONVERSION
COATSnG
WASTEWATER
CYANIDE {
TREATMENT I
(OPTIONAL) (
CHROMIUM
REDUCTION
CHEMICAL
ApDITION
l\.), , Ol
OIL
SKIMMING
CLEANING
WASTEWATER
DISCHARGE
CHEMICAL
PRECIPITATION
SEDIMINTATION
OTHER
(QUENCH WASTES)
SLUDGE
REMOVAL OF
OIL AND GREASE
SLUDGE TO
DISPOSAL
RECYCLE
SLUOGE
DEWATERING
FIGURE IX-1. BPT WASTEWATER TREATMENT SYSTEM
-------
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 dischargers
or may discharge pollutants into waters of the United States.
This section presents information on direct dischargers only as
well as total category and each subcategory data.
The factors considered in assessing best available technology
economically achievable (BAT) include the age of equipment and
facilities involved, the process 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 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 and its
subcategories, and suggested three technology trains which
accomplish reduction in the discharge of toxic pollutants above
that achieved at BPT.
As a general approach for the category, three levels of BAT were
evaluated. The technologies in general are equally applicable to
all the subcategories and each level produces similar
concentrations of pollutants in the effluent from all
subcategories. Mass limitations derived from these options,
however, vary because of the impact of varying water use and
wastewater generation rates. Extreme technologies such as
distillation and deep space disposal were rejected a priori as
too costly or not proven.
The Agency proposed BAT based on the following treatment
technologies:
quench water recycle through cooling tower
401
-------
quench water reuse as cleaning rinse
rinse sensors to shut off unused flow
hexavalent chromium reduction
cyanide oxidation or precipitation
oil skimming
hydroxide precipitation and sedimentation of metals
filtration after sedimentation
sludge dewatering
Before proposal the Agency also considered treatment technologies
which included: countercurrent rinsing, non-cyanide conversion
coating, no-rinse conversion coating, and ultrafiltration rather
than conventional filtration.
The Agency received comments criticizing the requirement of
filters at BAT. Industry believed the difference in removal
efficiency due to filtration was too small to economically
justify the addition of filtration. In response to this comment,
the Agency reevaluated filtration for final rule. BAT Option 1
(page 429) for the final rule included all the proposed treatment
technologies except filtration after sedimentation; BAT Option 2
(page 430) included all the proposed treatment technologies.
BAT OPTION SELECTION
The selected Option is BAT 1 which consists of: recycle of quench
water using cooling towers; use of blowdown from cooling towers
to provide rinse water; reduction of hexavalent chromium and
removal of cyanide from conversion coating rinses; combination of
rinse water and treatment with lime; settling of suspended
solids; skimming of oil from settling unit; and dewatering of
sludge. The selected BAT will remove 700 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 above BAT 1
would be the removal annually of 152 kg of total toxics and 9794
kg of other pollutants (see Table X-16, page 424). Filtration
therefore would result in the removal of only about 0.02 kg per
day per direct discharger.
Industry Cost and Effluent Reduction Benefits of Treatment
Options
An estimate of capital and annual costs for BPT, BAT 1 and BAT 2
were prepared for each subcategory as an aid to choosing the best
BAT option. The capital cost of treatment technology described
in place was also calculated for each subcategory using the
402
-------
methodology in Section VIII. Results are presented in Table X-18
(page 426). All costs are based on January 1978 dollars.
EPA used the following method to obtain cost figures. The total
cost of in-place treatment equipment for each subcategory was
estimated using information provided on dcps. An average cost
for a "normal plant" was determined by dividing each total
subcategory cost by the number of plants having operations in
that subcategory. Some plants carry out operations in more than
one subcategory leading to double or triple counting of the
plant. Thus the sum of "normal plants" will not equal the actual
number of physical plants in the category. For "Capital In
Place", this procedure defines the "Normal Plant."
In developing BPT, BAT 1 and BAT 2 costs, each known coil plant
was costed for the needed equipment at the appropriate flows.
Multisubcategory plants were apportioned to the appropriate
subcategories by production. For each subcategory, the
individual plant costs were summed to obtain costs incurred by
direct dischargers, indirect dischargers and total subcategory.
A "normal plant" cost was calculated by dividing the total
subcategory costs by the number of plants in the subcategory.
The subcategory costs were summed to arrive at category costs.
Results are presented in Table X-18. The capital costs are
incremental costs above equipment in place. . The annual costs
include the operation of the equipment in place.
Pollutant reduction benefits for each subcategory were derived by
(a) characterizing raw wastewater and effluent from each proposed
treatment system in terms of concentrations produced and
production normalized discharges (Tables X-l through X-3, pages
409-411) for each significant pollutant found; (b) calculating
the quantities removed and discharged in one year by a "normal
plant" (Tables X-5 through X-7, pages 413-415); and (c)
calculating the quantities removed and discharged in one year by
subcategory and for the category (Tables X-8 through X—11, pages
416-419). Table X-l2 (page 420) summarizes treatment
performances by subcategory and by category for BPT and each BAT
option showing the mass of pollutants removed and discharged by
each option. Tables X-l through X-3 and X-5 through X-12 present
pollutant reduction benefits for all plants in the subcategories
and the category. Tables X-13 through X-17 present pollutant
reduction benefits for direct dischargers in the subcategories
and the category. The pollutant reduction benefit tables for
indirect dischargers are presented in Section XII. Table X-18
presents costs for normal plants, direct dischargers, indirect
dischargers, subcategory totals, and category totals. All
pollutant parameter calculations were based on median raw
wastewater concentrations for visited plants (Table V-31, page
403
-------
103). The term "toxic organics" refers to toxic organics listed
in Table X-4 (page 412).
REGULATED POLLUTANT PARAMETERS
The raw wastewater concentrations from individual operations and
from the subcategory total 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 handled in this Section. Several toxic or non-
conventional metal pollutants are regulated in each subcategory.
The Agency found a small amount of several toxic organic
compounds (collectively referred to as total toxic organics) in
coil coating wastewaters. The concentration present is 1.47 mg/1
(see Table X-4, page 412). The percent removal of organics by
oil skimming from five coil coating plants is presented in
Section VII. The average removal of organics by oil skimming in
the category is about 84 percent. This would lower
concentrations of all but 4 of the toxic organics in Table X-4 to
below the quantification level.
In the proposed regulation, the toxic metals selected for control
included all priority pollutants and non-conventionals for which
the concentration in the raw wastewater was above the
treatability limit of technologies considered. Also, if one
metal was below the treatability limit in one subcategory, but
not in another, it was still regulated in both. This was because
most coil coating plants run more than one basis material and
wastewater pollutants generated in one subcategory may
contaminate wastewaters from other subcategories. Industry
recommended that only pH and TSS are necessary to control the
effluent toxic metals and,was confused that metals in the raw
wastewater in some subcategories below the treatable
concentration were being controlled. Based on these comments
and further evaluation, EPA decided to regulate fewer toxic
metals; three metals are regulated in the steel and aluminum
subcategories and four in the galvanized subcategory. This
decision is because at moderate alkaline pH levels (usually 8.7
to 9.2) toxic metals form very slightly soluble hydroxides. The
lime and settle technology on which the coil coating limitations
are based is limited by the level of residual dissolved metals
and the effectiveness of solids removal. General experience and
theoretical chemistry both indicate that control of a small
404
-------
number of key metals will result in near optimum removal of most
toxic and other pollutant metals. This would also reduce the
number and cost of chemical analysis required for compliance.
Some industry sources stated that cyanide is not used in cleaning
formulations and is a conversion coating process chemical only in
the aluminum subcategory and that a severe product quality
penalty could result from total application of non-cyanide
processing; therefore, a discharge of cyanide is allowed. The
Agency stated at proposal that the preferred mechanism for
control of cyanide is the use of non-cyanide conversion coating.
A plant may be exempt from the requirement of monitoring for
cyanide regularly if it demonstrates and certifies that it
neither has nor uses cyanide in its processes and it will not
initiate such use.
Also, for the aluminum subcategory, the pollutants regulated are
the same as those expected to be regulated in aluminum forming.
This is because aluminum coil coating and aluminum forming
operations are often performed at the same site and this will
allow co-treatment of the wastewaters. Aluminum forming effluent
limitations and standards were proposed by the Agency November
22,1982, (47 FR 52626).
The metals selected for specific regulation are discussed by
subcategory. The effluent limitations achieved by application of
the selected BAT Option also are presented by subcategory.
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 in each
subcategory.
STEEL SUBCATEGORY
Using the model BAT system, the flow calculation assumes that
quench water would be recycled and reused so that there would be
no discharge directly identifiable with quench operation. The
BAT wastewater flow for the steel subcategory was obtained using
visited plant data as a model to determine what portion of total
plant flow (all operations) is attributable to cleaning and
conversion coating operations. A ratio was calcualted using the
model (visited plant data) by dividing the mean flow for all
operations minus the mean flow for quench by the mean flow for
all operations. This ratio was then applied to mean flow for all
operations as calcualted from the dcp responses to determine BAT.
The dcp responses were used because they provide an extensive
data base.
405
-------
The visited plant mean water use for all operations in the steel
subcategory as set forth in Section V is 6.33 1/sq m processed
area. This flow is the sum of 3.632 1/sq m in the quench
operation, 2.274 1/sq m in cleaning, and 0.421 1/sq m in the
conversion coating operation as set forth in Section V. The dcp
mean water use for all operations in the subcategory as set forth
in Section V is 2.752 1/sq m. The wastewater allowance for the
subcategory would then become 1.173 1/sq m which is 97 percent of
the proposed wastewater allowance. This flow will be used to
calculate expected performance for BAT in the steel subcategory.
Pollutant parameters selected for regulation at BAT are:
chromium, cyanide, zinc, and iron. The end-of-pipe treatment
applied to the reduced flow would produce the effluent
concentrations of regulated pollutants shown in Section VII,
Table VII-21 the tabulation for precipitation and sedimentation
(lime and settle) technology.
When these concentrations are applied to the plant flows
described above, the mass of pollutant allowed to be discharged
per unit area of steel coil cleaned and conversion coated can be
calculated. Table X-19 shows the limitations derived from this
calculation. The non-regulated pollutants listed in Table X-19
which were proposed for regulation will be adequately removed
coincidentally if the regulated pollutants are removed to the
apporpriate levels. The derivation of limitations is explained
in Section IX (page 383). The BAT mean production normalized
flows are derived for each subcategory in this section.
GALVANIZED SUBCATEGORY
Using the model BAT system, the flow calculation assumes that
quench water would be recycled and reused so that there would be
no discharge directly identifiable with quench operation. The
BAT wastewater flow for the galvanized subcategory was obtained
using visited plant data as a model to determine what portion of
total plant flow (all operations) is attributable to cleaning and
conversing coating operations. A ratio was calcualted using the
model (visited plant data) by dividing the mean flow for all
operations minus the mean flow for quench by the mean flow for
all operations. This ratio was then from the dcp responses to
determine BAT. The dcp responses were used because they provide
a more extensive base.
The visited plant mean water use for all operations in the
galvanized subcategory as set forth in Section V is 5.53 1/sq m
processed area. This flow is the sum of 3.632 1/sq m in the
quench operation, 1.368 1/sq m in cleaning, and 0.528 1/sq m in
the conversion coating operation as set forth in Section V. The
406
-------
dcp mean water use for all operations in the subcategory as set
forth in Section V is 2.610 1/sq m. The wastewater allowance for
the subcategory would then become 0.896 1/sq m which is 74
percent of the proposed wastewater allowance. This flow will be
used to calculate expected performance for BAT in the galvanized
subcategory.
Pollutant parameters selected for regulation in the galvanized
subcategory at BAT are: chromium, copper, cyanide, and iron. The
end-of-pipe treatment applied to the reduced flow would produce
the effluent 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 flows
described above, the mass of pollutant allowed to be discharged
per unit area of galvanized coil cleaned and conversion coated
can be calculated. Table X-20 shows the limitations derived from
this calculation. The non-regulated pollutants listed in Table
X-20 which were proposed for regulation will be adequately
removed coincidentally if the regulated pollutants are removed to
the appropriate levels.
ALUMINUM SUBCATEGORY
Using the model BAT system, the flow calculation assumes that
quench water would be recycled and reused so that there would be
no discharge directly identifiable with quench operation. The
BAT wastewater flow for the aluminum subcategory was obtained
using visited plant data as a model to determine what portion of
total plant flow (all operations) is attributable to cleaning and
conversion coating operations. A ratio was calculated using the
model (visited plant data) by dividing the mean flow for all
operations minus the mean flow for quench by the mean flow for
all operations. This ratio was then applied to mean flow for all
operations as calculated from the dcp responses to determine BAT.
The dcp responses were used because they provide a more extensive
base.
The visited plant mean water use. for all operations in the
aluminum subcategory as set forth in Section V is 5.14 1/sq m
processed area. This flow is the sum of 3.632 1/sq n in the
quench operaion, 0.964 1/sq m in cleaning, and 0.546 1/sq m in
the conversion coating operatio as set forth in Section V. The
dcp mean water use for all operations in the subcategory as set
forth in Section V is 3.363 1/sq m. The wastewater allowance for
the subcategory would then become 0.987 1/sq m which is 101
percent of the proposed wastewater allowance. This flow will be
407
-------
used to calculate expected performance for BAT in the aluminum
subcategory.
Pollutant parameters selected for regulation in the aluminum
subcategory at BAT ares chromium, cyanide, zinc, and aluminum.
The end-of-pipe treatment applied to the reduced flow would
produce the effluent concentrations of regulated pollutant shown
in Section VII, Table VII-21 for precipitation and sedimentation
(lime and settle) technology.
When these concentrations are applied to the plant flows
described above, the mass of pollutant allowed to be discharged
per unit area of aluminum coil cleaned and conversion coated can
be calculated. Table X-21 shows the limitations derived from
this calculation. The non-regulated pollutants listed in Table
X-21 which were proposed for regulation will be adequately
removed coincidentally if the regulated pollutants are removed to
the specified levels.
DEMONSTRATION STATUS
No sampled coil coating plants in any subcategory use the BAT
technology in its entirety. However, each element of the system
is demonstrated in the category. The BAT model system has the
same end-ofrpipe treatment as BPT. In addition, BAT includes
quench water recycle through a cooling tower and reuse as
cleaning rinse. Of the 69 plants for which data was received: 15
have cooling towers, 19 recycle quench water, and 5 reuse quench
water. The dissolved solids concentration of quench water does
not increase significantly over influent concentrations;
therefore, there should be no problem in using quench recycle and
reuse at all coil coating facilities.
408
-------
TABLE X-l
SUMMARY OF TREATMENT EFFECTIVENESS
STEEL SUBCATEGORY
PARAMETER
FLOW 1/m2
RAW WASTE
mg/1
mg/nr
2.752
BPT•(PSES 0)
mg/1
mg/nr
2.752
BAT 1 (PSES 1)
mg/1
mg/nr
1.173
BAT 2 (PSES 2)
mg/1
mg/m2
1.173
118 CADMIUM
119 CHROMIUM
120 COPPER
0.001
6.865
0.051
0.003
18.892
0.140
0.001
0.080
0.051
0.003
0.220
0.140
0.002
0.080
0.119
0.002
0.094
0.140
0.002
0.070
0.119
0.002
0.082
0.140
121 CYANIDE
122 LEAD
124 NICKEL
0.012
0.142
0.392
0.033
0.391
1.079
0.012
0.120
0.392
0.033
0.330
1.079
0.028
0.120
0.570
0.033
0.141
0.669
0.028
0.080
0.220
0.033
0.094
0.258
4*
O
128 ZINC 7.588 20.882 0.300 0.826 0.300 0.352 0.230 0.270
TOXIC ORG. 1.282 3.528 0.038 0.105 0.038 0.045 0.038 0.045
IRON 10.145 27.919 0.410 1.128 0.410 0.481 0.280 0.328
PHOSPHORUS
OIL & GREASE
TSS
42.874
341.650
152.790
117.989
940.221
420.478
4.080
10.000
12.000
11.228
27.520
33.024
4.080
10.000
12.000
4.786
11.730
14.076
2.720
10.000
2.600
3.191
11.730
3.050
-------
TABLE X-2
SUMMARY OF TREATMENT EFFECTIVENESS
GALVANIZED SUBCATEGORY
PARAMETER
FLOW 1/m2
RAW WASTE
mg/1
mg/nr
2.610
BPT (PSES 0)
mg/1
mg/m2
2.610
BAT 1 (PSES 1)
mg/1
mg/m2
0.896
BAT 2 (PSES 2)
mg/1
mg/m2
0.896
118 CADMIUM
119 CHROMIUM
120 COPPER
0.045
57.600
0.009
0.117
150.336
0.023
0.045
0.080
0.009
0.117
0.209
0.023
0.079
0.080
0.026
0.071
0.072
0.023
0.049
0.070
0.026
0.044
0.063
0.023
121 CYANIDE
122 LEAD
124 NICKEL
0.082
0.422
0.395
0.214
1.101
1.031
0.070
0.120
0.395
0.183
0.313
1.031
0.070
0.120
0.570
0.063
0.108
0.511
0.047
0.080
0.220
0.042
0.072
0.197
-p»
i—•
o
128 ZINC
TOXIC ORG.
IRON
25.489
0.118
2.829
66.526
0.308
7.384
0.300
0.022
0.410
0.783
0.057
1.070
0.300
0.022
0.410
0,269
0.020
0.367
0.230
0.022
0.280
0.206
0.020
0.251
PHOSPHORUS
OIL & GREASE
TSS
14.758
52.965
114.050
38.518
138.239
297.671
4.080
10.000
12.000
10.649
26.100
31.320
4.080
10.000
12.000
3.656
8.960
10.752
2.720
10.000
2.600
2.437
8.960
2.330
-------
TABLE X-3
SUMMARY OF TREATMENT EFFECTIVENESS
ALUMINUM SUBCATEGORY
PARAMETER
FLOW 1/m2
RAW WASTE
mg/x
mg/m2
3.363
BPT (PSES 0)
mg/1
mg/m2
3.363
BAT 1 (PSES 1)
mg/1
mg/m'5
0.987
BAT 2 (PSES 2)
mg/1
mg/m^
0.987
118 CADMIUM
119 CHROMIUM
120 COPPER
0.005
43.500
0.043
0.017
146.291
0.145
0.005
0.080
0.043
0.017
0.269
0.145
0.017
0.080
0.147
0.017
0.079
0.145
0.017
0.070
0.147
0.017
0.069
0.145
121 CYANIDE
122 LEAD
124 NICKEL
0.568
0.118
0.003
1.910
0i397
0.010
0.070
0.118
0.003
0.235
0.397
0.010
0.070
0.120
0.010
0.069
0.118
0.010
0.047
0.080
0.010
0.046
0.079
0.010
128 ZINC
TOXIC ORG.
ALUMINUM
0.028
0.070
112.212
0.094
0.235
377.369
0.028
0.012
1.110
0.094
0.040
3.733
0.095
0.012
1.110
0.094
0.012
1.096
0.095
0.012
0.740
0.094
0.012
0.730
IRON
PHOSPHORUS
OIL & GREASE
3.448
7.000
57.561
11.596
23.541
193.578
0.410
4.080
10.000
1.379
13.721
33.630
0.410
4.080
10.000
0.405
4.027
9.870
0.280
2.720
10.000
0.276
2.685
9.870
TSS
84.884
285.465
12.000
40<356
12.000
11.844
2.600
2.566
-------
TABLE X-4
SUMMARY OF RAW WASTEWATER ORGANIGS
STEEL GALVANIZED ALUMINUM
mg/1 mg/m^ mq/l mg/m^ mg/l mq/m^
11
1,1,1-Trichloroethane
*
*
0.011
0.064
-
-
13
1,1-Di chloroethane
0.018
0.034
-
-
-
-
29
1,1-Dichloroethylene
-
-
0.015
0.016
-
-
30
1,2-Trans-Dichloroethylene
-
-
*
0.019
-
-
34
2,4-Dimethylphenol
0.021
0.032
-
-
-
-
39
Fluoranthene
0.040
0.036
*
*
*
*
54
Isqphorone
0.600
0.909
*
*
-
-
55
Naphthalene
*
*
*
*
*
*
65
Phenol
0.016
0.024
0.00
0.00
0.00
0.00
66
Bis (2-ethylhexyl) phthalate 0.035
0.050
0.030
0.177
0.014
0.047
67
Butyl-benzyl phthalate
0.152
0.300
*
*
*
*
68
Di-n-butylphthalate
*
*
*
*
*
*
69
Di-n-octyl phthalate
0.027 '
0.031
*
*
*
*
70
Diethyl phthalate
0.056
0.158
0.048
0.174
0.056
0.188
71
Dimethyl phthalate
0.00
0.00
*
*
*
*
72
1,2-Benzanthracene
0.056
0.044
*
*
0.00
0.00
73
Benzo (a) pyrene
*
*
*
*
*
*
74
3,4-Benzofluoranthene
0.035
0.023
*
*
*
*
75
11,12-Benzofluoranthene
0.035
0.023
*
*
*
*
76
Chrysene
0.023
0.040
*
*
0.00
0.00
77
Acenaphthalene
*
*
*
*
0.00
0.00
78
Anthracene
0.064
0.097
*
*
*
*
79
1,12-Benzqperylene
0.00
0.00
0.00
0.00
*
*
80
Fluorene
0.028
0.100
0.005
0.016
*
*
81
Phenathrene
0.064
0.097
*
*
*
*
82
1,2,5,6-Dibenzanthracene
0.00
0.00
0.00
0.00
0.00
0.00
83
Indeno (l,2,3-cd)pyrene
0.00
0.00
0.00
0.00
0.00
0.00
84
Pyrene
0.012
0.024
*
*
0.00
0.00
86
Toluene
*
*
0.00
0.00
*
*
87
Trichloroethylene
*
*
*
*
—
—
TOTAL
1.282
2.022
0.118
0.466
0.070
0.235
Blank indicates analysis not performed
- indicates not a verification parameter in respective category
* indicates parameter was detected but concentration was below a quantifiable level
0.0 indicates the parameter was not detected in all samples for which it was analyzed
412
-------
TABLE X-5
POLLUTANT REDUCTION BENEFITS OF CONTROL SYSTEMS
STEEL SUBCATEGORY - NORMAL PLANT
PARAMETER
FLOW 1/yr (106)
118 CADMIUM
119 CHROMIUM
120 COPPER
RAW WASTE
kg/yr
33.55
0.03
230.32
1.71
BPT (PSES 0)
Removed
kg/yr
0.00
227.64
0.00
Discharged
kg/yr
33.55
0.03
2.68
1.71
BAT 1 (PSES 1)
Removed
kg/yr
0.00
229.18
0.00
Discharged
kg/yr
14.30
0.03
1.14
1.71
BAT 2 (PSES 2)
Removed
kg/yr
0.00
229.32
0.00
Discharged
kg/yr
14.30
0.03
1.00
1.71
t-*
oo
121 CYANIDE
122 LEAD
124 NICKEL
128 ZINC
TOXIC ORG.
IRON
0.40
4.76
13.15
254.58
43.01
340.36
0.00
0.73
0.00
244.51
41.74
326.60
0.40
4.03
13.15
10.07
1.27
13.76
0.00
3.04
5.00
250.29
42.47
334.50
0.40
1.72
8.15
4.29
0.54
5.86
0.00
3.62
10.00
251.29
42.47
336.36
0.40
1.14
3.15
3.29
0.54
4.00
PHOSPHORUS
OIL & GREASE
TSS
1438.42
11462.36
5126.10
1301.54
11126.86
4723.50
136.88
335.50
402.60
1380.08
11319.36
4954.50
58.34
143.00
171.60
1399.52
11319.36
5088.92
38.90
143.00
37.18
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
504.55
16588.46
547.96
18915.20
472.88
15850.36
514.62
17993.12
31.67
738.10
33.34
922.08
487.51
16273.86
529.98
18518.42
17.04
314.60
17.98
396.78
494.23
16408.28
536.70
18680.86
10.32
180.18
11.26
234.34
SLUDGE GEN
120232.79
124692.12
126072.93
-------
TABLE X-6
POLLUTANT REDUCTION BENEFITS OF CONTROL SYSTEMS
GALVANIZED SUBCATEGORY - NORMAL PLANT
PARAMETER RAW WASTE BPT (PSES 0) BAT 1 (PSES 1) BAT 2 (PSES 2)
Removed Discharged Removed Discharged Removed Discharged
kg/yr kg/yr kg/yr kg/yr kg/yr kg/yr kg/yr
FLOW 1/yr (106)
30.02
30.02
10.30
10.30
J—»
4*
118 CADMIUM 1.35 0.00 1.35 0.54 0.81 0.85
119 CHROMIUM 1729,15 1726.75 2.40 1728.33 0.82 1728.43
120 COPPER 0.27 0.00 0.27 0.00 0.27 0.00
121 CYANIDE 2.46 0.36 2.10 1.74 0.72 1.98
122 LEAD 12.67 9.07 3.60 11.43 1.24 11.85
124 NICKEL 11.86 0.00 11.86 5.99 5.87 9.59-
128 ZINC 765.18 756.17 9.01 762.09 3.09 762.81
TOXIC ORG. 3.54 2.88 0*66 3.31 0.23 3.31
IRON 84.93 72.62 12.31 80.71 4.22 82.05
PHOSPHORUS 443.04 320.56 122.48 401.02 42.02 415.02
OIL & GREASE 1590.01 1289.81 300.20 1487.01 103.00 1487.01
TSS 3423.78 3063.54 360.24 3300.18 123.60 3397.00
TOXIC METALS 2520.48 2491.99 28.49 2508.38 12.10 2513.53
CONVENTIONALS 5013.79 4353.35 660.44 4787.19 226.60 4884.01
TOTAL TOXICS 2526.48 2495.23 31.25 2513.43 13.05 2518.82
TOTAL POLLU. 8068.24 7241.76 826.48 7782.35 285.89 7899.90
0.50
0.72
0.27
0.48
0.82
2.27
2.37
0.23
2.88
28.02
103.00
26.78
6.95
129.78
7.66
168.34
SLUDGE GEN
55892.55
60546.82
61552.60
-------
TABLE X-7
POLLUTANT REDUCTION BENEFITS OF CONTROL SYSTEMS
ALUMINUM SUBCATEGORY - NORMAL PLANT
PARAMETER
FLOW 1/yr (106)
118 CADMIUM
119 CHROMIUM
120 COPPER
121 CYANIDE
122 LEAD
124 NICKEL
RAW WASTE
kg/yr
97.80
0.49
4254.30
4.21
55.55
11.54
0.29
BPT (PSES 0)
BAT 1 (PSES 1)
BAT 2 (PSES 2)
Removed
kg/yr
0.00
4246.48
0.00
48.70
0.00
0.00
Discharged
kg/yr
97.80
0.49
7.82
4.21
6.85
11.54
0.29
Removed
kg/yr
0.00
4252.00
0.00
53.54
8.10
0.00
Discharged
kg/yr
28.70
0.49
2.30
4.21
2.01
3.44
0.29
Removed
kg/yr
Discharged
kg/yr
0.00
4252.29
0.00
54.20
9.24
0.00
28.70
0.49
2.01
4.21
1.35
2.30
0.29
-P»
i—*
128 ZINC
TOXIC ORG.
ALUMINUM
2.74
6.85
10974.33
0.00
5.68
10865.77
2.74
1.17
108.56
0.00
6.51
10942.47
2.74
0.34
31.86
0.00
6.51
10953.09
2.74
0.34
21.24
IRON
PHOSPHORUS
OIL & GREASE
337.21
684.60
5629.47
297.11
285.58
4651.47
40.10
399.02
978.00
325.44
567.50
5342.47
11.77
117.10
287.00
329.17
606.54
5342.47
8.04
78.06
287.00
TSS
8301.66
7128.06
1173.60
7957.26
344.40
8227.04
74.62
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
4273.57
13931.13
4335.97
30263.24
4246.48
11779.53
4300.86
27528.85
27.09
2151.60
35.11
2734.39
4260.10
13299.73
4320.15
29455.29
13.47
631.40
15.82
807.95
4261.53
13569.51
4322.24
29780.55
. 12.04
361.62
13.73
482.69
SLUDGE GEN
423142.18
440651.42
443364.43
-------
TABLE X-8
TOTAL TREATMENT PERFORMANCE
STEEL SUBCATEGORY
PARAMETER
118 CADMIUM
119 CHROMIUM
120 COPPER
RAW WASTE
kg/yr
FLOW 1/yr (106) 1341.88
1.34
9212.01
68.44
BPT & PSES 0
Removed
kg/yr
0.00
9104.66
0.00
1341.88
1.34
107.35
68.44
BAT 1 & PSES 1
Discharged
kg/yr
Removed
kg/yr
0.00
9166.25
0.00
Discharged
kg/yr
571.95
1.34
45.76
68.44
BAT 2 S PSES 2
Removed
kg/yr
0.00
9171.97
0.00
Discharged
kg/yr
571.95
1.34
40.04
68.44
h-1
Ol
121 CYANIDE
122 LEAD
124 NICKEL
128 ZINC
TOXIC ORG.
IRON
16.10
190.55
526.02
10182.19
1720.29
13613.37
0.00
29.52
0.00
9779.63
1669.30
13063.20
16.10
161.03
526.02
402.56
50.99
550.17
• 0.00
121.92
200.01
10010.60
1698.56
13378.87
16.10
68.63
326.01
171.59
21.73
234.50
0.00
144.79
400.19
10050.64
1698.56
13453.22
16.10
45.76
125.83
131.55
21.73
160.15
PHOSPHORUS
OIL & GREASE
TSS
57531.76 52056.89 5474i87 55198.20
458453.30 445034.50 13418.80 452733.80
205025.85 188923.29 16102.56 198162.45
2333.56 55976.06 1555.70
5719.50 452733.80 5719.50
6863.40 203538.78 1487.07
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
20180.55 18913.81 1266.74 19498.78 681.77 19767.59 412.96
663479.15 633957.79 29521.36 650896.25 12582.90 656272.58 7206.57
21916.94 20583.11 1333.83 21197.34 719.60 21466.15 450.79
756541.22 719660.99 36880.23 740670.66 15870.56 747168.01 9373.21
SLUDGE GEN
4808887.06
4987240.57
5042480.83
-------
TABLE X-9
TOTAL TREATMENT PERFORMANCE
GALVANIZED SUBCATEGORY
PARAMETER
RAW WASTE
kg/yr
FLOW 1/yr (106) 600.30
BPT & PSES 0
Kemovea
kg/yr
600.30
BAT 1 & PSES 1
Discharged
kg/yr
Removed
kg/yr
206.08
BAT 2 & PSES 2
Discharged
kg/yr
Removed
kg/yr
Discharged
kg/yr
206.08
118 CADMIUM
119 CHROMIUM
120 COPPER
27.01
34577.28
5.40
0.00
34529.26
0.00
27.01
48.02
5.40
10.73
34560.79
0.00
16.28
16.49
5.40
16.91
34562.85
0.00
10.10
14.43
5.40
i-»
121 CYANIDE
122 LEAD
124 NICKEL
128 ZINC
TOXIC ORG.
IRON
49.22
253.33
237.12
15301.05
70.84
1698.25
7.20
181.29
0.00
15120.96
57.63
1452.13
42.02
72.04
237.12
180.09
13.21
246.12
34.79
228.60
119.65
15239.23
66.31
1613.76
14.43
24.73
117.47
61.82
4.53
84.49
39.53
236.84
191.78
15253.65
66.31
1640.55
9.69
16.49
45.34
47.40
4.53
57.70
PHOSPHORUS
OIL & GREASE
TSS
8859.23
31794.89
68464.21
6410.01
25791.89
61260.61
2449.22
6003.00
7203.60
8018.42
29734.09
65991.25
840.81
2060.80
2472.96
8298.69
29734.09
67928.40
560.54
2060.80
535.81
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
50401.19
100259.10
50521.25
161337.83
49831.51
87052.50
49896.34
144810.98
569.68
13206.60
624.91
16526.85
50159.00
95725.34
50260.10
155617.62
242.19
4533.76
261.15
5720.21
50262.03
97662.49
50367.87
157969.60
139.16
2596.61
153.38
3368.23
SLUDGE GEN
1117661.56
1210699.01
1230826.21
-------
TABLE X-10
TOTAL TREATMENT PERFORMANCE
ALUMINUM SUBCATEGORY
PARAMETER
RAW WASTE
kg/yr
FLOW 1/yr (106) 4694.21
BPT & PSES 0
BAT 1 & PSES 1
Removed Discharged Removed Discharged
kg/yr kg/yr kg/yr kg/yr
4694.21
1377.69
BAT 2 S PSES 2
Removed Discharged
kg/yr kg/yr
1377.69
118 CADMIUM
119 CHROMIUM
120 COPPER
23.47
204198.13
201.85
0.00
203822.59
0.00
23.47 0.00
375.54 204087.91
201.85 0.00
23.47 0.00 23.47
110.22 204101.69 96.44
201.85 0.00 201.85
45>
H->
CO
121 CYANIDE
122 LEAD
124 NICKEL
128 ZINC
TOXIC ORG.
ALUMINUM
2666.31 2337.72
553.92 0.00
14.08 0.00
131.44 0.00
328.59 272.26
526746.69 521536.12
328.59 2569.87
553.92 388.60
14.08 0.00
131.44 0.00
56.33 312.06
5210.57 525217.45
96.44 2601.56 64.75
165.32 443.70 110.22
14.08 0.00 14.08
131.44 0.00 131.44
16.53 312.06 16.53
1529.24 525727.20 1019.49
IRON
PHOSPHORUS
OIL & GREASE
16185.64 14261.01
32859.47 13707.09
270203.42 223261.32
1924.63 15620.79
19152.38 27238.49
46942.10 256426.52
564.85 15799.89 385.75
5620.98 29112.15 3747.32
13776.90 256426.52 13776.90
TSS
398463.32 342132.80 56330.52 381931.04 16532.28 394881.33
3581.99
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
205122.89 203822.59
668666.74 565394.12
208117.79 206432.57
1452576.33 1321330.91
1300.30
103272.62
1685.22
204476.51
638357.56
207358.44
131245.42 1413792.73
646.38 204545.39 577.50
30309.18 651307.85 17358.89
759.35 207459.01 658.78
38783.60 1429406.10 23170.23
SLUDGE GEN
20310010.20
21150390.73
21280616.61
-------
TABLE X-ll
TREATMENT PERFORMANCE
TOTAL CATEGORY
PARAMETER
RAW WASTE
kg/yr
BPT & PSES 0
BAT 1 & PSES 1
BAT 2 & PSES 2
Remov g d
kg/yr
Discharged
kg/yr
Removed
kg/yr
FLOW 1/yr (106) 6636.39
6636.39
118 CADMIUM
119 CHROMIUM
120 COPPER
121 CYANIDE
122 LEAD
124 NICKEL
51.82 0.00 51.82 10.73
247987.42 247456.51 530.91 247814.95
275.69 0.00 275.69 0.00
2731.63
997.80
777.22
2344.92
210.81
0.00
386.71
786.99
777.22
2604.66
739.12
319.66
Discharged
kg/yr
126.97
258.68
457.56
Removed
kg/yr
Discharged
kg/yr
2155.72
2641.09
825.33
591.97
2155.72
41.09 16.91 34.91
172.47 247836.51 150.91
275.69 0.00 275.69
90.54
172.47
185.25
128 ZINC
TOXIC ORG.
ALUMINUM
25614.68 24900.59 714.09 25249.83
2119.72 1999.19 120.53 2076.93
526746.69 521536.12 5210.57 525217.45
364.85 25304.29 310.39
42.79 2076.93 42.79
1529.24 525727.20 1019.49
IRON
PHOSPHORUS
OIL & GREASE
31497.26 28776.34 2720.92 30613.42 883.84 30893.66 603.60
99250.46 72173.99 27076.47 90455.11 8795.35 93386.90 5863.56
760451.61 694087.71 66363.90 738894.41 21557.20 738894.41 21557.20
TSS
671953.38 592316.70 79636.68 646084.74 25868.64 666348.51
5604.87
TOXIC METALS 275704.63 272567.91
CONVENTIONALS 1432404.99 1286404.41
TOTAL TOXICS 280555.98 276912.02
TOTAL POLLU. 2370455.38 2185802.88
3136.72 274134.29
146000.58 1384979.15
3643.96 278815.88
184652.50 2310081.01
1570.34 274575.01 1129.62
47425.84 1405242.92 27162.07
1740.10 279293.03 1262.95
60374.37 2334543.71 35911.67
SLUDGE GEN
26236558.82
27348330.31
27553923.65
-------
TABLE X-12
SUMMARY TABLE
POLLUTANT REDUCTION BENEFITS
TOTAL CATEGORY
RAW WASTE
kg/yr
BPT
BAT 1
BAT 2
Removed Discharged Removed Discharged Removed Discharged
kg/yr kg/yr kg/yr kg/yr kg/yr kg/yr
Steel Subcategory
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
20180.55
86347S.15
21916.94
756541.22
18913.81
633957.79
20583.11
719660.99
1266.74
29521.36
1333.83
36880.23
19498.78
650896.25
21197.34
740670.66
681.77
12582.90
719.60
15870.56
19767.59
656272.58
21466.15
747168.01
412.96
7206.57
450.79
9373.21
•p*
ro
o
Galvanized Subcategory
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
50401.19
100259.10
50521.25
161337.83
49831.51
87052.50
49896.34
144810.98
569.68
13206.60
624.91
16526.85
50159.00
95725.34
50260.10
155617.62
242.19
4533.76
261.15
5720.21
50262.03
97662.49
50367.87
157969.60
139.16
2596.61
153.38
3368.23
-Aluminum Subcategory
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
205122.89
668666.74
208117.79
203822.59
565394.12
206432.57
1300.30
103272.62
1685.22
204476.51
638357.56
207358.44
646.38
30309.18
759.35
204545.39
651307.85
207459.01
1452576.33 1321330.91 131245.42 1413792.73 38783.60 1429406.10
577.50
17358.89
658.78
23170.23
Total Subcategory
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
275704.63 272567.91
1432404.99 1286404.41
280555.98 276912.02
2370455.38 2185802.88
3136.72 274134.29
146000.58 1384979.15
3643.96 278815.88
184652.50 2310081.01
1570.34 274575.01 1129.62
47425.84 1405242.92 27162.07
1740.10 279293.03 1262.95
60374.37 2334543.71 35911.67
-------
TABLE X-13
TREATMENT PERFORMANCE - DIRECT DISCHARGERS
STEEL SUBCATEGORY
PARAMETER
RAW WASTE
kg/yr
FLOW 1/yr (106) 436.11
BPT
BAT 1
Removed Discharged Removed Discharged
kg/yr kg/yr kg/yr kg/yr
436.11
185.88
BAT 2
Removed Discharged
kg/yr kg/yr
185.88
118 CADMIUM
119 CHROMIUM
120 COPPER
0.43
2993.90
22.25
0.00
2959.01
0.00
0.43
34.89
22.25
0.00
2979.03
0.00
0.43
14.87
22.25
0.00
2980.88
0.00
0.43
13.02
22.25
-p=>
no
121 CYANIDE
122 LEAD
124 NICKEL
128 ZINC
TOXIC ORG.
IRON
5.23
61.93
170.96
3309.21
559.09
4424.33
0.00
9.59
0.00
3178.38
542.52
4245.53
5.23
52.34
170.96
130.83
16.57
178.80
0.00
39.63
65.01
3253.44
552.03
4348.12
5.23
22.30
105.95
55.77
7.06
•76.21
0.00
47.06
130.07
3266.46
552.03
4372.28
5.23
14.87
40.89
42.75
7.06
52.05
PHOSPHORUS
OIL & GREASE
TSS
18697.78
148996.98
66633.25
16918.45
144635.88
61399.93
1779.33 17939.39
4361.10 147138.18
5233.32* 64402.69
758.39 18192.19 505.59
1858.80 147138.18 1858.80
2230.56 66149.96 483.29
TOXIC METALS
CONVENTIONALE
TOTAL TOXICS
TOTAL POLLU.
6558.68 6146.98 411.70 6337.11
215630.23 206035.81 9594.42 211540.87
7123.00 6689.50 433.50 6889.14
245875.34 233889.29 11986.05 240717.52
221.57 6424.47 134.21
4089.36 213288.14 2342.09
233.86 6976.50 146.50
5157.82 242829.11 3046.23
SLUDGE GEN
1562884.74
1620850.62
1638803.35
-------
TABLE X-14
TREATMENT PERFORMANCE - DIRECT DISCHARGERS
GALVANIZED SUBCATEGORY
PARAMETER
PLOW 1/yr (106)
RAW WASTE
kg/yr
90.04
BPT
Removed Discharged
kg/yr kg/yr
90.04
BAT 1
Removed Discharged
kg/yr kg/yr
30.91
BAT 2
Removed Discharged
kg/yr kg/yr
30.91
118 CADMIUM
119 CHROMIUM
120 COPPER
4.05
5186.30
0.81
0.00
5179.10
0.00
4.05
7.20
0.S1
1.61
5183.82
2.44
2.48
0.81
2.53
5184.13
0.00
1.52
2.17
0.81
121 CYANIDE
122 LEAD
124 NICKEL
7.38
38.00
35.57
1.08
27.19
0.00
6.30
10.81
35.57
• 5.21
34.29
17.95
2.17
3.71
17.62
5.92
35.52
28.77
1.46
2.48
6.80
128 ZINC
TOXIC ORG.
IRON
2295.03
10.63
254.72
2268.02
8.65
217.81
27.01
1.98
36.91
2285.76
9.95
242.05
9.27
0.68
12.67
2287.92
9.95
246.07
7.11
0.68
8.65
PHOSPHORUS
OIL & GREASE
TSS
1328.81
. 4768.97
10269.06
961.45
3868.57
9188.58
367.36
900.40
1080.48
1202.69
4459.87
9898.14
126.12
309.10
370.92
1244.73
- 4459.87
10188.69
84.08
309.10
80.37
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
7559.76
15038.03
7577.77
24199.33
7474.31
13057.15
7484.04
21720.45
85.45
1980.88
93.73
2478.88
7523.43
14358.01
7538.59
23341.34
36.33
680.02
39.18
857.99
7538.87
14648.56
7554.74
23694.10
20.89
389.47
23.03
505.23
SLUDGE GEN
167640.01
181594.40
184613.22
-------
TABLE X-15
TREATMENT PERFORMANCE - DIRECT DISCHARGERS
ALUMINUM SUBCATEGORY
PARAMETER
118 CADMIUM
119 CHROMIUM
120 COPPER
121 CYANIDE
122 LEAD
124 NICKEL
RAW WASTE
kg/yr
BPT
BAT 1
FLOW 1/yr (106) 2249.31
11.25
97844.98
96.72
1277.61
265.42
6.75
Removed Discharged
kg/yr kg/yr
2249.31
11.25
179.95
96.72
157.45
265.42
6.75
BAT 2
0.00
97665.03
0.00
1120.16
0.00
0.00
RsiuOV 0 u
kg/yr
0.00
97792.16
0.00
1231.40
186.21
0.00
discharged
kg/yr
660.14
11.25
52.82
96.72
46.21
79.21
6.75
Removed Discharged
kg/yr kg/yr
660.14
11.25
46.21
96.72
31.03
52.82
6.75
0.00
97798.77
0.00
1246.58
212.60
0.00
128 ZINC
TOXIC ORG.
ALUMINUM
IRON
PHOSPHORUS
OIL & GREASE
TSS
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
62.98 0.00 62.98 0.00 62.98 0.00 62.98
157.45 130.46 26.99 149.53 7.92 149.53 7.92
252399.57 249902.84 2496.73 251666.81 732.76 251911.07 488.50
7755.62 6833.40 922.22 7484.97 ' 270.65 7570.78 184.84
15745.17 6567.98 9177.19 13051.79 2693.38 13949.59 1795.58
129472.53 106979.43 22493.10 122871.13 6601.40 122871.13 6601.40
190930.43 163938.71 26991.72 183008.75 7921.68 189214.07 1716.36
98288.10
320402.96
99723.16
97665.03
270918.14
: 98915.65
TOTAL POLLU. 696026.48 633138.01
623.07 97978.37 309.73 98011.37 276.73
49484.82 305879.88 14523.08 312085.20 8317.76
807.51 99359.30 363.86 99407.48 315.68
62888.47 677442.75 18583.73 684924.12 11102.36
SLUDGE GEN
9731884.28
10134567.60
10196967.27
-------
TABLE X-16
TREATMENT PERFORMANCE
TOTAL CATEGORY - DIRECT DISCHARGERS
PARAMETER
RAW WASTE
kg/yr
FLOW 1/yr (106) 2775.46
BPT
Removed
kg/yr
Discharged
kg/yr
2775.46
BAT 1
Removed
kg/yr
Discharged
kg/yr
876.93
BAT 2
Removed
kg/yr
Discharged
kg/yr
876.93
118 CADMIUM
119 CHROMIUM
120 COPPER
15.73
106025.18
119.78
0.00
105803.14
15.73
222.04
119.78
1.61
105955.01
0.00
14.12
70.17
119.78
2.53
105963.78
0.00
13.20
61.40
119.78
-P»
ro
-p»
121 CYANIDE
122 LEAD
124 NICKEL
128 ZINC
TOXIC ORG.
ALUMINUM
1290.22
365.35
213.28
5667.22
727.17"
252399.57
1121.24
36.78
0.00
5446.40
681.63
249902.84
168.98
328.57
213.28
220.82
45.54
2496.73
1236.61
260.13
82.96
5539.20
711.51
251666.81
53.61
105.22
130.32
128.02
15.66
732.76
1252.50
295.18
158.84
5554.38
711.51
251911.07
37.72
70.17
54.44
112.84
15.66
488.50
IRON
PHOSPHORUS
OIL S GREASE
12434.67
35771.76
283238.48
11296.74
24447.88
255483.88
1137.93
11323.88
27754.60
12075.14
32193.87
274469.18
359.53
3577.89
8769.30
12189.13
33386.51
274469.18
245.54
2385.25
8769.30
TSS
267832.74 234527.22 33305.52 257309.58 10523.16 265552.72
2280.02
TOXIC METALS
CONVENTIONALE
TOTAL TOXICS
TOTAL POLLU.
112406.54
551071.22
114423.93
966101.15
111286.32
490011.10
113089.19
888747.75
1120.22
61060.12
1334.74
77353.40
111838.91
531778.76
113787.03
941501.61
567.63
19292.46
636.90
24599.54
111974.71
540021.90
113938.72
951447.33
431.83
11049.32
485.21
14653.82
SLUDGE GEN
11462409.03
11937012.62
12020383.84
-------
TABLE X-17
SUMMARY TABLE
POLLUTANT REDUCTION BENEFITS
DIRECT DISCHARGERS
RAW WASTE
kg/yr
BPT
BAT 1
BAT 2
ttemovea
kg/yr
Steel Subcategory
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
6558.68
215630.23
7123.00
6146.98
206035.81
6689.50
245875.34 233889.29
Galvanized Subcategory
uiscnargea
kg/yr
Kemoved
kg/yr
411.70 6337.11
9594.42 211540.87
433.50 6889.14
11986.05 240717.52
Discharged
kg/yr
Removed
kg/yr
Discharged
kg/yr
221.57 6424.47 134.21
4089.36 213288.14 2342.09
233.86 6976.50 146.50
5157.82 242829.11 3046.23
-P*
ro
ui
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
7559.76
15038.03
7577.77
24199.33
7474.31
13057.15
7484.04
21720.45
85.45
1980.88
93.73
2478.88
7523.43
14358.01
7538.59
23341.34
36.33
680.02
39.18
857.99
7538.87
14648.56
7554.74
23694.10
20.89
389.47
23.03
505.23
Aluminum Subcategory
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
98288.10
320402.96
99723.16
97665.03
270918.14
98915.65
696026.48 633138.01
623.07 97978.37
49484.82 305879.88
807.51 99359.30
62888.47 677442.75
309.73 98011.37 276.73
14523.08 312085.20 8317.76
363.86 99407.48 315.68
18583.73 684924.12 11102.36
Total Subcategory
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
112406.54 111286.32 1120.22 111838.91
551071.22 490011.10 61060.12 531778.76
114423.93 113089.19 1334.74 113787.03
966101.15 888747.75 77353.40 941501.61
567.63 111974.71 431.83
19292.46 540021.90 11049.32
636.90 113938.72 485.21
24599.54 951447.33 14653.82
-------
0KBEEX-2B
TSEfflJEOT COSTS
BPT (PSES O)
Capital Capital Annual
In Plaos Costs $ Costs $
BAT 1 (PSES 1)
Capital Annual
Costs $ Costs $
BAT 2 (PSES 2)
Capital Annual
Costs $ Costs $
Steel Subcategory
Normal Plant
Direct Dischargers
Indirect Dischargers
Subcategory Total
39000
504000
1047000
1551000
157000
2321000
3946000
6267000
55000
858000
1329000
2187000
154000
2267000
3875000
6142000
54000
854000
1318000
2172000
182000
2800000
4493000
7293000
84000
1287000
2062000
3349000
Galvanized Subcategory
Normal Plant
Direct Dischargers
Indirect Dischargers
Subcategory Total
145000
436000
2470000
2906000
102000
231000
1811000
2042000
34000
86000
593000
673000
92000
208000
1624000
1832000
33000
82000
584000
666000
111000
273000
1941000
2214000
51000
125000
892000
1017000
Aluminum Subcategory
Normal Plant
Direct Dischargers
Indirect Dischargers
Subcategory Ibtal
83000
1911000
2078000
3989000
194000
4429000
4878000
9307000
67000
1722000
1499000
3221000
192000
4436000
4787000
9223000
66000
1707000
1482000
3189000
233000
5314000
5857000
11171000
104000
2484000
2509000
4993000
Category
Direct Dischargers
Indirect Dischargers
Category "total
2851000
5595000
8446000
6981000
10635000
17616000
2721000
3421000
6087000
6911000
10286000
17197000
2643000
3384000
6027000
8387000
12291000
20678000
3896000
5463000
9359000
NOTE): Capital costs are presented as incremental costs above "Capital In Place."
Annual costs include continuing operation of "Capital In Place."
-------
TABLE X—19
BAT EFFLUENT LIMITATIONS
STEEL SUBCATEGORY
POLLUTANT OR
POLLUTANT MAXIMUM FOR MAXIMUM FOR
PROPERTY ANY ONE DAY MONTHLY AVERAGE
mg/m2
(lb/1,000,000 ft2)
mg/m2
(lb/1,000,000 ft2)
CADMIUM
0.375
(0.077)
0.176
(0.036)
*CHROMIUM
0.493
(0.101)
0.199
(0.041)
COPPER
2.229
(0.457) '
1.173
(0.240)
~CYANIDE
0.340
(0.070)
0.141
(0.029)
LEAD
0.176
(0.036)
0.152
(0.031)
NICKEL
1.654
(0.339)
1.173
(0.240)
~ZINC
1.560
(0.320)
0.657
(0.135)
~IRON
1.443
(0.296)
0.739
(0.151)
TABLE X-20
BAT EFFLUENT LIMITATIONS
GALVANIZED SUBCATEGORY
POLLUTANT OR
POLLUTANT MAXIMUM FOR MAXIMUM FOR
PROPERTY ANY ONE DAY MONTHLY AVERAGE
mg/m2
(lb/1,000,000 ft2)
mg/m2
(lb/1,000,000
CADMIUM
0.287
(0.059)
0.134
(0.027)
~CHROMIUM
0.376
(0.077)
0.152
(0.031)
~COPPER
1.702
(0.349)
0.896
(0.184)
~CYANIDE
, 0.260 ,
(0.053)
0.108
(0.022)
LEAD
0.134
(0.027)
0.116
(0.024)
NICKEL
1.263
(0.259)
0.896
(0.184)
~ZINC
1.192
(0.244)
0.502
(0.103)
~IRON
1.102
(0.226)
0.564
(0.116)
* THIS POLLUTANT IS REGULATED AT PROMULGATION
427
-------
TABLE X-21
BAT EFFLUENT LIMITATIONS
ALUMINUM SUBCATEGORY
POLLUTANT OR
POLLUTANT MAXIMUM FOR MAXIMUM FOR
PROPERTY ANY ONE DAY MONTHLY AVERAGE
mg/m2
(lb/1,000,000 ft2)
mg/m2
(lb/1,000,0
CADMIUM
0.316
(0.065)
0.148
(0.030)
~CHROMIUM
0.415
(0.085)
0.168
(0.034)
COPPER
1.875
(0.384)
0.987
(0.202)
~CYANIDE
0.286
(0.059)
0.118
(0.024)
LEAD
0.148
(0.030)
0.128
(0.026)
NICKEL
1.392
(0.285)
0.987
(0.202)
~ZINC
1.313
(0.269)
0.553
(0.113)
~ALUMINUM
4.491
(0.920)
1.836
(0.376)
IRON
1.214
(0.249)
0.622
(0.127)
*.THIS POLLUTANT IS REGULATED AT PROMULGATION
428
-------
CHEMICAL
CHEMICAL ADDITION
ADDITION
DISCHARGE
CHEMICAL
PRECIPITATION
SEDIMENTATION
OIL
SKIMMING
SLUDGE
OTHER
(QUENCH WASTES)
SlIIOGE TO
DISPOSAL
RECYCLE
COOLING
TOWER
SLUDGE
DEWATERING
RECYCLE TO OUENCH
REUSE TO PROCESS
FIGURE X-1. BAT LEVEL 1 WASTEWATER TREATMENT SYSTEM
-------
CHEMICAL
ADDITION
CHEMICAL
ADDITION
CONVERSION
COATING
WASTEWATER
CHROMIUM
REDUCTION
C'
J CYANIDE f
J TREATMENT I
| (OPTIONAL)
!% !
CLEANING
WASTEWATER
»fa>
OJ
O
OTHER
{QUENCH WASTES)
COOLING
TOWER
RECYCLE TO QUENCH
REUSE TO PROCESS
REMOVAL OF
OIL AND GREASE
CHEMICAL
ADDITION
CHEMICAL
PRECIPITATION
SKIMMING
RECYCLE
SEDIMENTATION
.
IF? POLISHING
SHLTRATIONi
discharge
SLUDGE
si unnETo
DISPOSAL
SLUOGE OEWATERING
FIGURE X-2. BAT LEVEL Z WASTEWATER TREATMENT SYSTEM
-------
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 (BDT), processes, operating
methods, or other alternatives, including where practicable, a
standard permitting no discharge of pollutants. Possible model
NSPS technologies 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
for each subcategory.
TECHNICAL APPROACH TO NSPS
As a general approach for the category, three levels of NSPS were
evaluated. The technologies are equally applicable to all
subcategories and each level can produce similar concentrations
of pollutants in the effluent from all three subcategories. Mass
limitations will vary among subcategories because of differences
in water use.
The Agency proposed NSPS based on:
in-process wastewater reduction
• countercurrent cascade rinses (cleaning)
• quench water recycle through cooling tower
• quench water reuse as cleaning rinse
• rinse sensors to shut off unused flow
in-process pollutant reduction
• non-cyanide conversion coating
• no-rinse conversion coating
oil skimming
hydroxide precipitation of metals, sedimentation and
filtration
431
-------
sludge dewatering
Additionally, treatment options considered before proposal
included the application of ultrafiltration in place of
conventional filtration and the application of membrane
filtration in place of sedimentation.
Industry commented that the use of no rinse conversion coating
was not generally applicable because there are no Food and Drug
Administration approved no rinse conversion coatings. In light
of these comments, the Agency reexamined the requirement that no
wastewater be discharged from conversion coating processes as
described at proposal.
The final NSPS allows 20 percent blowdown from quenching
operations to be used after conversion coating as well as after
cleaning. This is adequate flow allowance to permit conventional
conversion coating if three stage countercurrent cascade rinsing
is employed for cleaning and conversion coating rinse water.
Hexavalent chromium reduction has been included in the NSPS model
technology since no rinse conversion coating, which would
eliminate the discharge of chromium, has been deleted.
Some industry sources stated that cyanide is not used in cleaner
formulations and is a conversion coating process chemical only in
the aluminum subcategory and that a severe product quality
penalty could result from total application of non-cyanide
processing. The final regulation allows some discharge of
cyanide. The Agency stated at proposal that the preferred
mechanism for control of cyanide is the use of non-cyanide
conversion coating. To encourage this change, a plant may be
exempted from the requirement of monitoring cyanide if it
demonstrates and certifies that it neither has nor uses cyanide
in its processes and it will not initiate such use.
The model technology basis for NSPS iss recycle of quench water,
reuse of quench water blowdown as cleaning and conversion coating
rinse water, three stage countercurrent cascade rinsing for both
cleaning and conversion coating, removal of cyanide and reduction
of hexavalent chromium from conversion coating rinses, oil
skimming, precipitation of metals, sedimentation, polishing
filtration, and dewatering of sludge.
The methods for water use reduction included in the NSPS model
technology are described belows
432
-------
Countercurrent Rinses - Countercurrent rinsing is a mechanism
commonly encountered in electroplating, and other metal processing
operations where uncontaminated water is used for the final
cleaning 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 three stage countercurrent rinse would reduce water
usage approximately 30 times for the same rinse ratio.
Countercurrent rinsing is presently used in one coil coating
plant.
Quench Water Recycle - The cooling and recycle of quench water is
commonly practiced throughout the industry and 20 plants are
believed to use cooling towers and recycle some substantial
fraction of their cooling or quench water. Because the principle
function of. quench water is to remove heat quickly from the
painted coil, the principle requirements of the water are that it
be cool and that it not contain dissolved solids at such level
that it leaves water marks or other discolorations on the painted
surface. There is sufficient industry experience to assure the
success of this technology; six plants already do not discharge
any quench water by reason of continued recycle.
Quench Water Reuse - Water that has been used one or two cycles
as quench, water appears to be satisfactory for further use as
rinse water in the coil coating operation. The amount of water
used for quench purposes is about 1.5 times the once through
amount of rinse water used in a coil coating plant, so that some
level of recirculation would be required to completely use the
quench water. This does not appear to be unreasonable; three
plants are presentlyusing part or all of their quench water
blowdown for other coil coating purposes.
Rinse Sensors - Sensing devices that shut off rinse water when
the coil coating line is not running eliminate unnecessary water
flow. These devices have been observed installed and operating
at six of the coil coating plants visited.
For the final NSPS, EPA considered making NSPS equivalent to the
final BAT which consists of recycle of quench water using cooling
towers, use of blowdown from cooling towers to provide rinse
water, removal of cyanide and reduction of hexavalent chromium
from conversion coating rinses, combination of rinse waters and
treatment with lime, settling of suspended solids, skimming of
433
-------
oil from settling unit, and dewatering of sludge (Figure X-l,
page 429).
EPA selected the final NSPS because it provides a reduced
discharge of all, pollutants below the final BAT (see Tables XI-2,
3 and 4). 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 XI-1).
Cost and Effluent Reduction Benefits of NSPS
Estimates of capital and annual costs for NSPS for each
subcategory are presented in Table XI-1 (page 439) which is based
on January 1978 dollars.
In calculating NSPS costs, EPA Used the "normal Plant" production
as derived in Section X. The average production for the steel,
galvanized and aluminum subcategories are 12.19, 11.50 and 29.08
sq meters [million] per year, respectively. An average plant
production was multiplied by a production normalized flow for
each subcategory. Control technology was sized for the normal
plant.
The pollutant reduction benefit for each subcategory 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 in each subcategory; and (b) calculating the quantities
removed and discharged in one year by a "normal plant." Results
of these calculations were presented in Tables X-5, X-6, and X-7.
Comparison of Table XI-1 with Tables X-5, X-6, and X-7 shows that
BDT-1 costs less and produces greater incremental benefits than
the other BDT options. All pollutant parameter calculations were
based on median total raw wastewater concentrations for visited
plants. See Table V-31 (Page 103).
REGULATED POLLUTANT PARAMETERS
The Agency reviewed the wastewater concentrations from individual
operations and from the subcategory total 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.
434
-------
In each subcategory oil and grease, TSS, and pH were selected for
regulation with several toxic or non-conventional metal
pollutants plus cyanide. In the propsoed regulation, the toxic
metals selected for control included all those for which the
concentration in the raw wastewater was above the treatability
limit. EPA decided to regulate three or four metals in each
subcategory and to use the parameter pH as an indicator to ensure
control of the unregulated toxic metals. Maintaining effluent pH
within optimum pH levels assures removal of those toxic metals
not selected for specific regulation.
Chromate conversion coating" can be applied to aluminum and
galvanized 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 the aluminum
and galvanized subcategories for the steel subcategory, chromium
is also regulated because of discharges from cleaning operations.
Cyanide is regulated in all subcategories, but if a plant
demonstrates and certifies that it neither has nor uses cyanide,
it may be exempt from the requirement of monitoring cyanide.
In addition to the pollutant parameters listed above, there is a
amount of other toxic pollutants in the coil coating wastewaters.
The Agency is using an oil and grease standard for new sources in
order to control the polynuclear aromatic hydrocarbons and 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
control of 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 Table VII-11, page 264).
The metals selected for specific regulation are discussed by
subcategory. The performance standards achieved by application
of BDT also are presented by subcategory. Hexavalent chromium is
not regulated specifically because it is included in total
chromium. Only the trivalent form is removed by the lime-settle-
filter technology. Therefore, the hexavalent form must be
reduced to meet the limitation on total chromium in each
subcategory.
STEEL SUBCATEGORY
Applying the NSPS technology, the quench water would be recycled
and the blowdown of 20 percent of quench flow would be used for
countercurrent cascade rinsing. The NSPS wastewater flow for the
435
-------
steel subcategory was obtained using visited plant data model to
determine what portion of total plant flow (all operations) is
attributable to 20 percent of quench. A ratio was calculated
using the model (visited plant data) by dividing 20 percent of
the mean flow for all operations. This ratio was then applied to
mean flow for all operations as calculated from the dcp responses
to determine the NSPS. The dcp responses provide an extensive
data base.
The visited plant mean water use for quench operations in the
category as set forth in Section V is 3.632 1/sq m processed
area. The visited- plant mean water use for all operations in the
steel subcategory 1/sq m and the dcp responses mean water use for
all operations is 2.752 1/sq m. The wastewater allowance for the
subcategory would then become 0.316 1/sq m which is 91 percent of
the proposed wastewater allowance. This flow will be used to
calculate expected performance for new direct dischargers in the
steel subcategory.
Pollutant parameters selected for regulation in the steel
subcategory for NSPS are:• chromium, cyanide, zinc, iron, oil and
grease, TSS, and pH. The end-of-pipe treatment applied to the
reduced flow would produce effluent concentrations of regulated
pollutants equal to those shown in Section VII, Table VII-19 ,
for precipitation, sedimentation, and filtration (lime, settle,
and filter) technology., pH must be maintained within the range
of 7.5 - 10.0 at all times.
When these concentrations are applied to the water flows
described above, the mass of pollutant allowed to be discharged
per unit area of steel coii cleaned and conversion coated can be
calculated. Table XI--5 shows the performance standards derived
from this calculation.
GALVANIZED SUBCATEGORY
Applying the NSPS model technology, the quench water would be
recycled and the blowdown of 20 percent of quench flow would be
used for countercurrent cascade rinsing. The NSPS wastewater
flow for the galvanized subcategory was obtained using visited
plant data as a model to determine what portion of total plant
flow (all operations) is attributable to 20 percent of quench. A
ratio was calculated using the model (visited plant data) by
dividing 20 percent of the mean flow for quench by the mean flow
for all operations. This ratio was then applied to mean flow for
all operations as calculated from the dcp responses to determine
the NSPS flow. The dcp responses provide a more extensive data
436
-------
base. The visited plant mean water use for quench oeprations in
the category as set forth in Section V is 3.632 1/sq m processed
area. The visited plant mean water use for all operations in the
galvanized subcategory is 5.53 1/sq m and the dcp response mean
water use for all operations is 2.610 1/sq m. The wastewater
allowance for the subcategory would then become 0.343 1/sq m
which is 80 percent of the proposed wastewater allowance. This
flow will be used to calculate expected performance for new
direct dischargers in the galvanized subcategory.
Pollutant parameters selected for regulation in the galvanized
subcategory for BDT ares chromium, copper, cyanide, zinc, iron,
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 VI1-19
precipitation, sedimentation, and filtration (lime-settle-filter)
technology. pH must be maintained within the range 7.5 - 10-0 at
all times.
When these concentrations are applied to the water flows
described above, the mass of pollutant allowed to be discharged
per unit area galvanized coil cleaned and conversion coated can
be calculated. Table XI-6 shows the standards derived from this
calculation.
ALUMINUM SUBCATEGORY
Applying the NSPS technology, the quench water would be recycled
and the blowdown of 20 percent of quench flow would be used for
countercurrent cascade rinsing. The NSPS qastewater flow for the
aluminum subcategory was obtained using visited plant data as a
model to determine what portion of total plant flow (all
operations) is attributable to 20 percent of quench. A ratio was
calculated using the model (visited plant data) by dividing 20
percent of the mean flow for quench by the mean flow for all
operations. This ratio was then applied to mean flow for all
operations as calculated from the dcp responses to determine the
NSPS flow. The dcp responses provide a more extensive data base.
The visited plant mean water use for quench operations in the
category as set forth in Section V is 3.632 1/sq m processed
area. The visited plant mean water use for all operations is
5.14 1/sq m and the dcp response mean water use for all
operations is 3.363 1/sq m. the wastewater allowance for the
subcategory would then become 0.475 1/sq m which is 126 percent
of the proposed wastewater allowance. This flow will be used to
437
-------
calculate expected performance for new direct dischargers in the
aluminum subcategory.
Pollutant parameters selected for regulation in the aluminum
subcategory for NSPS are: chromium, cyanide, zinc, aluminum, 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 VI1-19 for
precipitation, sedimentation, and filtration (lime-settle-filter)
technology. pH must be maintained within the range 7.5 - 10.0 at
all times.
When these concentrations are applied to the water flows
described above, the mass of pollutant allowed to be discharged
per unit area of aluminum coil cleaned and conversion coated can
be calculated. Table XI-7 shows the standards derived from this
calculation.
DEMONSTRATION STATUS
No sampled coil The NSPS model system has all the same treatment
components as BAT plus countercurrent rinse and polishing
filters, coating plant in any subcategory uses all of the NSPS
technology. However, each major element of the NSPS technology
is demonstrated in one or more coil coating plants except for
polishing filters. Countercurrent rinse is demonstrated at 2
coil coating plants. Polishing filters, while not in use at coil
coating plants, are widely known to be effective in reducing TSS
and precipitated metals (See Section VII) in categories whose
wastewaters are similar to coil coating wastewater.
438
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TABLE XI-1
COSTS OF BDT FOR COIL COATING NSPS
NOBMftL PLANT
Final NSPS (PSNS)
Capital Annual
Costs $ Costs $
Final BAT (PSES)
Capital Annual
Costs 1$ Costs $
Steel Subcategory
Normal Plant
Flow, liters/year
Production, sq m/year
171,500
3.9xl06
12.19x10s
51,300
305,000
14.3x10s
12.19xl06
77,400
Galvanized Subcategory
Normal Plant
Flow, liters/year
Production, sq m/year
172,500
3.9xl06
11.50x10s
51,800
288,100
10.3x10s
11.50x10s
72,300
Aluminum Subcategory
Normal Plant
Flow, liters/year
Production, sq m/year
316,800 89,600
13.8x10s
29.08x10s
355,700 103,200
28.7x10s
29.08x10s
-------
TABLE XI-2
POIZOTANT REDUCTION BENEFITS OF CONTROL SYSTEMS
STEEL SUBCATEGORY - NORMAL PLANT
PARAMETER
RAW WASTE Final NSPS (PSNS)
Final BAT (PSES)
kg/yr
Removed
kg/yr
Discharged
kg/yr
Removed
kg/yr
Discharged
kg/yr
FLOW 1/yr (106)
33.55
3.85
14.30
118 CADMIUM
0.03
0.00
0.03
0.00
0.03
119 CHROMIUM
230.32
230.05
0.27
229.18 .
1.14
120 COPPER
1.71
0.21
1.50
0.00
1.71
121 CTANIDE
0.40
0.22
0.18
0.00
0.40
122 LEAD
4.76
4.45
0.31
3.04
1.72
124 NICKEL
13.15
12.30
0.85
5.00
8.15
128 ZINC
254.58
253.69
0.89
250.29
4.29
TOXIC ORG.
43.01
42.86
0.15
42.47
0.54
IRON
340.36
339.28
1.08
334.50
5.86
PHOSPHORUS
1438.42
1427.95
10.47
1380.08
58.34
OIL & GREASE
11462.36
11423.86
38.50
11319.36
143.00
TSS
5126.10
5116.09
10.01
4954.50
171.60
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
504.55 500.70
16588.46 16539.95
547.96 543.78
18915.20 18850.96
3.85 487.51 17.04
48.51 16273.86 314.60
4.18 529.98 17.98
64.24 18518.42 396.78
SLUDGE GEN
127612.57
124692.12
440
-------
TABLE XI-3
POLLUTANT REDUCTION BENEFITS OF CONTROL SYSTEMS
GALVANIZED SUBCATEGORY - NORMAL PLANT
PARAMETER RAW WASTE Final NSPS (PSNS) Final BAT (PRF.R)
Removed Discharged Removed Discharged
kg/yr kg/yr kg/yr kg/yr kg/yr
FLOW 1/yr (106)
30.02
3.94
10.30
118 CADMIUM
119 CHROMIUM
120 COPPER
1.35
1729.15
0.27
1.16
1728.87
0.00
0.19
0.28
0.27
0.54
1728.33
0.00
0.81
0.82
0.27
121 CYANIDE
122 LEAD
124 NICKEL
2.46
12.67
11.86
2.27
12.35
10.99
0.19
0.32
0.87
1.74
11.43
5.99
0.72
1.24
5.87
128 ZINC
TOXIC ORG.
IRON
765.18
3.54
84.93
764.27
3.45
83.83.
0.91
0.09
1.10
762.09
3.31
80.71
3.09
0.23
4.22
PHOSPHORUS
OIL & GREASE
TSS
443.04
1590.01
3423.78
432.32
1550.61
3413.54
10.72
39.40
10.24
- 401.02
1487.01
3300.18
42.02
103.00
123.60
TCKIC METALS
OONVENITQNALS
TOTAL TCKICS
TOTAL POLLU.
2520.48
5013.79
2526.48
8068.24
2517.64
4964.15
2523.36
8003.66
2.84
49.64
3.12
64.58
2508.38
4787.19
2513.43
7782.35
12.10
226.60
13.05
285.89
SLUDGE GEN
62496.07
60546.82
441
-------
TABLE XI-4
POLLUTANT REDUCTION BENEFITS OF CONTROL SYSTEMS
ALUMINUM SUBCATEGORY - NORMAL PLANT
PARAMETER
RAW WASTE Final NSPS (PSNS) Final BAT (PSES)
kg/yr
Removed
kg/yr
Discharged
kg/yr
Removed
kg/yr
Discharged
kg/yr
FLOW 1/yr (106)
97.80
13.81
28.70
118 CADMIUM
119 CHROMIUM
120 COPPER
0.49
4254.30
4.21
0.00
4253.33
0.00
0.49
0.97
4.21
0.00
4252.00
0.00
0.49
2.30
4.21
121 CYANIDE
122 LEAD
124 NICKEL
55.55
11.54
0.29
54.90
10.44
0.00
0i65
1.10
0.29
53.54
8.10
0.00
2.01
3.44
0.29
128 ZINC
TOXIC ORG.
AU3MINUM
2..74
6,85
10974 ,.33
0.00
6.68
10964.11
2.74
0.17
10.22
0.00
6.51
10942.47
2.74
0.34
31.86
IRON
PHOSPHORUS
OIL & GREASE
337.21
684.60
5629.47
333.34
647.04
5491.37
3.87
37.56
138«10
325.44
567.50
5342.47
11.77
117.10
287.00
TSS
8301.66
8265.75
35.91
1
7957.26
344.40
TCKCC METALS
CONVEOTICSSALS
TOTAL TOXICS
TOTAL POLLU.
4273.57
13931.13
4335.97
30263.24
4263.77
13757.12
4325.35
30026.96
9.8
174.01
10.62
236.28
4260.10
13299.73
4320.15
29455.29
13.47
631.40
15.82
807.95
SLUDGE GEN
445730.54
440651.42
442
-------
TABLE XI-5
NEW SOURCE,PERFORMANCE STANDARDS
STEEL SUBCATEGORY
POLLUTANT OR
POLLUTANT
PROPERTY
MAXIMUM FOR
ANY ONE DAY
MAXIMUM FOR
MONTHLY AVERAGE
mg/m2
(lb/1,000,000
ft2)
mg/m2
(lb/1,000,000
CADMIUM •
0.063
(0.013)
0.025
(0.005)
~CHROMIUM
0.117
(0.024)
0.047
(0.010)
COPPER
0.404
(0.083)
0.193
(0.040)
~CYANIDE
0.063
(0.013) •
0.025
(0.005)
LEAD
0.032
(0.007)
0.028
(0.006)
NICKEL
0.174
(0.036)
0.117
(0.024)
~ZINC
0.322
(0.066)
0.133
(0.027)
~IRON
0.389
(0.080)
0.199
(0.041)
~OIL & GREASE
3.160
(0i647)
3.160
(0.647)
~TSS
4.740
(0.971)
3.476
(0.712)
~pH
WITHIN
THE RANGE OF
7.5 TO
10.0 AT
ALL TIMES
TABLE XI-S
NEW SOURCE PERFORMANCE STANDARDS
GALVANIZED SUBCATEGORY
POLLUTANT OR
POLLUTANT MAXIMUM FOR MAXIMUM FOR
PROPERTY ANY ONE DAY MONTHLY AVERAGE
mg/m2 (lb/1,000/000 ft2) mg/m2 (lb/1,000,000 ft2)
CADMIUM
0.069
(0.014)
0.027
(0.006)
~CHROMIUM
0.127
(0.026)
0.051
(0.010)
~COPPER
0.439
(0.090)
0.209
(0.043)
~CYANIDE
0.069
(0.014)
0.027
(0.006)
LEAD
0.034
(0.007)
0.031
(0.006)
NICKEL
0.189
(0.039)
0.127
(0.026)
~ZINC
0.350
(0.072)
0.144
(0.029)
~IRON
0.422
(0.086)
0.216
(0.044)
~OIL & GREASE
3.430
(0.703)
3.430
(0.703)
~TSS
5.145
(1.054)
3.773
(0.773)
~pH
WITHIN
THE RANGE OF
7.5 TO 10.0 AT
ALL TIMES
*
THIS POLLUTANT
IS REGULATED AT
PROMULGATION
443
-------
TABLE XI-7
NEW SOURCE PERFORMANCE STANDARDS
ALUMINUM SUBCATEGORY
POLLUTANT OR
POLLUTANT MAXIMUM FOR MAXIMUM FOR
PROPERTY ANY ONE DAY MONTHLY AVERAGE
mg/m2 (lb/1,000,000 ft2) mg/m2 (lb/1,000,000 ft2)
CADMIUM
0.095
(0.019)
0.038
(0.008)
~CHROMIUM
0.176
(0.036)
0.071
(0.015)
COPPER
0.608
(0.125)
0.290
(0.059)
~CYANIDE
0.095
(0.019)
0.038
(0.008)
LEAD
0.048
(0.010)
0.043
(0.009)
NICKEL
0.261
• (0.053)
0.176
(0.036)
~ZINC
0.485
(0.099)
0.200
(0.041)
~ALUMINUM
1.439
(0.295)
0.589
(0.121)
IRON
0.584
(0.120)
0.299
(0.061)
~OIL & GREASE
4.750
(0.973)
4.750
(0.973)
~TSS
7.125 _
(1.459)
5.225
(1.070)
*PH
WITHIN
THE RANGE OF
7.5 TO 10.0 AT
ALL TIMES
* THIS POLLUTANT IS REGULATED AT PROMULGATION
444
-------
CHEMICAL
CHEMICAL ADDITION
ADDITION
CHEMICAL
ADDITION
CLEANING
WASTEWATER
CHEMICAL
PRECIPITATION
OIL
SKIMMING
SEDIMENTATION
SLDDGE
REMOVAL OF
OIL AND GREASE
OTHER
(ODENCH WASTES)
RECYCLE
COOLING
TOWER
SLDDGE DEWATERING
RECYCLE TO QUENCH
20% REUSE TO COUNTERCURRENT RINSE
FIGURE XI I. BDT LEVEL 1 WASTEWATER TREATMENT SYSTEM
-------
Intentionally Blank Page
-------
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).
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 regulation, which served as ;the framework for this
pretreatment regulation is found at 40 CFR Part 403.
Like PSES, PSNS are to prevent the discharge of pollutants which
pass through, interfere with, or are otherwise incompatible with
the operation of the POTW. 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 coil coating 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 coil
coating processwastewaters,to POTW were discussed in Section VI.
The pollutcint-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 the BAT model treatment
technology. POTW removals of the major toxic pollutants found in
447
-------
coil coating wastewater are presented in Table XII-1. The
average removal of toxic metals is about 31 percent. The BAT
treatment technology removes more than 99 percent of toxic metals
(see Table X-16, page 424). This difference in removal
effectiveness clearly indicates pass through of toxic metals will
occur unless coil coating wastewaters are adequately pretreated.
The Agency found small amounts of several toxic organics in coil
coating wastewaters. The Agency considered and analyzed whether
these pollutants should be specifically regulated.
The average removal of toxic organics is about 70 percent by a
secondary POTW (Table XII-1, page 451). The treatment technology
for organics removal is oil skimming. The percent removal of
organics by oil skimming from five coil coating plant sampling
days is presented in Section VII. The average removal of
organics by oil skimming in this category is about 84 percent.
Clearly there is pass through of about 0.2 mg/1 of total toxic
organics (TTO). On the other hand, the raw waste level of TTO in
the coil category is only about 1.47 mg/1 (See Table X-4, page
412). The Agency's concludes that the treatment effected by POTW
reduces the small amount arid the toxicity of organics below the
level that would require national regulation.
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. The modifications made to the proposed
PSES and PSNS are the same as the modifications made to the
proposed BAT and NSPS, respectively. Oil skimming is included in
the PSES and PSNS control technologies, benefits, and costs. The
Agency believes oil and grease removal may be needed to meet the
toxic metals limitations since oil and grease can interfere with
the removal of precipitated metals. 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 by pH adjustment,
settling, and filtration for PSNS. Flow reduction measures
(~quench recycle and reuse for both and countercurrent rinse for
PSNS) are retained to provide minimum mass discharge of toxic
pollutants. If conventional conversion coating is used for PSNS,
there is no allowance for additional discharge from coating
operations.
448
-------
Industry Cost and Effluent Reduction of Treatment Options
PSES Options 1 and 2 are parallel to BAT Options 1 and 2. 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-18 and results for NSPS-PSNS are presented in Table XI-1. All
costs are based on January 1978 dollars.
PSES pollutant reduction benfits for each subcategory were
derived by applying the percentage of production attributable to
indirect dischargers. The pollutant reduction benefits for the
subcategories and the category are presented in Table XII-1
through XII-4 (pages 451-454). Table XII-5 summarizes treatment
performances by subcategory and by category for each PSES option.
All pollutant parameters calculations were based on median raw
wastewater concentrations for visited plants (Table V-31, page
103). The term "toxic organics" refers to toxic organics listed
in Table X-4 (page 412).
PSNS pollutant reduction benefits for each subcategory were based
on a normal plant production. The normal plant production for
the steel, galvanized and aluminum subcategories are 12.19, 11.50
and 29.08 million sq meters per year, respectively. The
pollutant reduction benefits for each subcategory are presented
in Tables XI-2 through XI-4. All pollutant parameter
calculations were based on median raw wastewater concentrations
for visited plants (Table V-31, page 103). The term "toxic
organics" refers to toxic organics listed in Table X-4 (page
412).
Regulated Pollutant Parameters
The Agency reviewed the coil coating wastewater concentrations,
the BAT model treatment technology removals, and the POTW
removals of major toxic pollutants found in coil coating
wastewaters to select the pollutants for regulation. The
pollutants to be regulated are the same for each subcategory as
were selected for BAT except that the nonconventional pollutants
(aluminum and iron) are not regulated because POTW remove these
pollutant parameters. Aluminum and iron compounds are frequently
used as flocculation aids in POTW. Toxic metals are regulated to
prevent pass through. Toxic organics are not regulated because
POTW reduce the small amount and toxicity below the level
requiring national regulation.
449
-------
PRETREATMENT STANDARDS
Mass based limitations are set forth below (Tables XI1-7 through
XII-12, pages 457-459). The mass based limitations are the only
method of designating pretreatment standards since the water flow
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 if
the quantity of pollutants discharged. Therefore, to regulate
concentrations is not adequate. Standards for existing sources
are presented first, by subcategory; then standards for new
sources are presented by subcategory.
The derivation of standards is explained in Section IX (page
483). The mean water use for each subcategory at PSES is equal
to the mean water use for each subcategory at BAT and their
derivation is presented in Section X (pages 405, 406 and 407).
For PSNS, the calculation is the same, except the lime, settle
andfilter treatment effectivenesses and the PSNS Mean water uses
are used. The lime, settle and filter treatment effectiveness
are developed in Section VII. The mean water use for each
subcategory at PSNS is equal to the mean water use for each
subcategory at NSPS.
DEMONSTRATION STATUS
Since the model treatment technologies for PSES and PNSN are the
same as BAT and NSPS, respectively, the demonstration status is
the same as for BAT and NSPS (See Sections X and XI).
450
-------
TABLE XII-1
POTW REMOVALS OF THE MAJOR TOXIC POLLUTANTS
FOUND IN COIL COATING WASTEWATER
Pollutant Percent Removal By
Secondary POTW
11 1,1,1-Trichloroethane 87
13 1,1-Dichloroethane 76
29 1,1-Dichloroethylene 80
30 1,2-Trans-Dichloroethylene 72
34 2,4-Dimethylphenol: 59
39 Fluoranthene NA
54 Isophorone NA
55 Naphthalene 61
65 Phenol 96
66 Bis (2-ethylhexyl) phthalate 62
67 Butyl-benzyl phthalate 59
68 Di-n-butylfhthalate 48
69 Di-n-octyl phthalate 81
70 Diethyl phthalate 74
71 Dimethyl phthalate 50
72 1,2-Benzanthracene - NA
73 Benzo (a) pyrene NA
74 3,4-Benzofluoranthene NA
75 11,12-Benzofluoranthene NA
76 Chrysene NA
77' Acenaphthalene NA
78 Anthracene 65
79 1,12-Benzoperylene 83
80 Fluorene NA
81 Phenathrene 65
82 1,2,5,6-Dibenzanthr acene NA
83 Indeno (1,2,3-cd )pyrene NA
84 Pyrene 40
86 Toluene 90
87 Trichloroethylene 85
118 Cadmium 38
119 Chromium, hexavalent 18
Chromium, trivalent NA
120 Copper 58
121 Cyanide 52
122 Lead 48
124 Nickel 19
128 Zinc 65
NA Not Available
NOTE: This data compiled from Fate Of Priority Pollutants In
Publicly Ctoned Treatment Works, USEPA, EPA No. 440/1-80-301,
October 1980.
451
-------
TABLE XII—2
TREATMENT PERFORMANCE - INDIRECT DISCHARGERS
STEEL SUBCATEGORY
PARAMETER
RAW WASTE
kg/yr
PLOW 1/yr (106) 905.77
PSES 0
Removed
kg/yr
905.77
PSES 1
Discharged
kg/yr
Removed
kg/yr
386.07
PSES 2
Discharged
kg/yr
Removed
kg/yr
Discharged
kg/yr
386.07
118 CADMIUM
119 CHROMIUM
120 COPPER
0.91
6218.11
46.19
0.00
6145.65
0.00
0.91
72.46
46.19
0.00
6187.22
0.00
0.91
30.89
46.19
0.00
6191.09
0.00
0.91
27.02
46.19
121 CYANIDE
122 LEAD
124 NICKEL
10.87
128.62
355.06
0.00
19.93
0.00
10.87
108.69
355.06
0.00
82.29
135.00
10.87
46.33
220.06
0.00
97.73
270.12
10.87
30.89
84.94
128 ZINC
TOXIC ORG.
IRON
6872.98
1161.20
9189.04
6601.25
1126.78
8817.67
271.73
34.42
371.37
6757,16
1146.53
9030.75
115.82
14.67
158.29
6784.18
1146.53
9080.94
88.80
14.67
108.10
PHOSPHORUS
OIL & GREASE
TSS
38833.98 35138.44 3695.54 37258.81
309456.32 300398.62 9057.70 305595.62
138392.60 127523.36 10869.24 133759.76
1575.17 37783.87 1050.11
3860.70 305595.62 3860.70
4632.84 137388.82 1003.78
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
13621.87 12766.83 855.04 13161.67 460.20 13343.12 278.75
447848.92 427921.98 19926.94 439355.38 8493.54 442984.44 4864.48
14793.94 13893.61 900.33 14308.20 485.74 14489.65 304.29
510665.88 485771.70 24894.18 499953.14 10712.74 504338.90 6326.98
SLUDGE GEN
3246002.32
3366389.95
3403677.48
-------
TABLE XII-3
TREATMENT PERFORMANCE - INDIRECT DISCHARGERS
GALVANIZED SUBCATEGORY
PARAMETER
118 CADMIUM
119 CHROMIUM
120 COPPER
121 CYANIDE
122 LEAD
124 NICKEL
128 ZINC
TOXIC ORG.
IRON
PHOSPHORUS
OIL & GREASE
TSS
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
RAW WASTE
kg/yr
PSES 0
PSES 1
PSES 2
FLOW 1/yr (106) 510.26
22.96
29390.98
4.59
41.84
215.33
201.55
13006.02
60.21
1443.53
7530.42
27025.92
58195.15
42841.43
85221.07
42943.48
137138.50
Removed
kg/yr
0.00
29350.16
0.00
6.12
" 154.10
0.00
12852.94
48.98
1234.32
5448.56
21923.32
52072.03
42357.20
73995.35
42412.30
123090.53
Discharged
kg/yr
Removed
kg/yr
510.26
22.96
40.82
4.59
35.72
61.23
201.55
153.08
11.23
209.21
2081.86
5102.60
6123.12
484.23
11225.72
531.18
14047.97
9.12
29376.97
0.00
29.58
194.31
101.70
12953.47
56.36
1371.71
6815.73
25274.22
56093.11
42635.57
81367.33
42721.51
132276.28
Discharged
kg/yr
175.17
13.84
14.01
4.59
12.26
21.02
99.85
52.55
3.85
71.82
714.69
1751.70
2102.04
205.86
3853.74
221.97
4862.22
Removed
kg/yr
Discharged
kg/yr
14.38
29378.72
0.00
33.61
201.32
163.01
12965.73
56.36
1394.48
7053.96
25274.22
57739.71
42723.16
83013.93
42813.13
134275.50
175.17
8.58
12.26
4.59
8.23
14.01
38.54
40«29
3.85
49.05
476.46
1751.70
455.44
118.27
2207.14
130.35
2863.00
SLUDGE GEN
950021.55
1029104.61
1046212.99
-------
TABLE XII-4
TREATMENT PERFORMANCE - INDIRECT DISCHARGERS
ALUMINUM SUBCATEGORY
PARAMETER
RAW WASTE
kg/yr
PLOW 1/yr (106) 2444.90
PSES 0
POTS 1
PSES 2
Removed Discharged Removed Discharged Removed Discharged
kg/yr kg/yr kg/yr kg/yr kg/yr kg/yr
2444.90
717.55
717.55
118 CADMIUM
119 CHROMIUM
120 COPPER
12.22 0.00
106353.15 106157.56
105.13 0.00
12.22 0.00
195.59 106295.75
105.13 0.00
12.22 0.00 12.22
57.40 106302.92 50.23
105.13 0.00 105.13
-P»
Ol
-£>
121 CYANIDE
122 LEAD
124 NICKEL
128 ZINC
TOXIC ORG.
ALUMINUM
1388.70 1217.56
288.50 0.00
7.33 0.00
68.46 0.00
171.14 141.80
274347.12 271633.28
171.14 . 1338.47
288.50 202.39
7.33 0.00
68.46 0.00
29.34 162.53
2713.84 273550.64
50.23 1354.98 33.72
86.11 231.10 57.40
7.33 0.00 7.33
68.46 0.00 68.46
8.61 162.53 8.61
796.48 273816.13 530.99
IRON
PHOSPHORUS
OIL & GREASE
8430.02
17114.30
140730.89
7427.61
7139.11
116281.89
1002.41 8135.82
9975.19 14186.70
24449.00 133555.39
294.20 8229.11 200.91
2927.60 15162.56 1951.74
7175.50 133555.39 7175.50
TSS
207532.89 178194.09 29338.80 198922.29
8610.60 205667.26
1865.63
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
106834.79
348263.78
108394.63
756549.85
106157.56
294475.98
107516.92
688192.90
677.23 106498.14
53787.80
877.71
68356.95
332477.68
107999.14
736349.98
336.65 106534.02
15786.10
395.49
20199.87
339222.65
108051.53
744481.98
300.77
9041.13
343.10
12067.87
SLUDGE GEN
10578125.92
11015823.13
11083649.34
-------
TABLE XII-5
TREATMENT PERFORMANCE - INDIRECT DISCHARGERS
TOTAL CATEGORY
PARAMETER
RAW WASTE
kg/yr
PSES 0
PSES 1
FLOW 1/yr (106) 3860.93
Removed
kg/yr
Discharged
kg/yr
3860,93
Removed
kg/yr
1278.79
PSES 2
Discharged
kg/yr
Removed
kg/yr
Discharged
kg/yr
1278.79
118 CADMIUM
119 CHROMIUM
120 COPPER
121 CYANIDE
122 LEAD
124 NICKEL
36.09 O.OO
141962.24 141653.37
155.91 0.00
1441.41
632.45
563.94
1223.68
174.03
0.00
36.09 9.12
308.87 141859.94
155.91 0.00
217.73
•458.42
563.94
1368.05
478.99
236.70
26.97 14.38
102.30 141872.73
155.91 0.00
73.36
153.46
327.24
1388.59
530.15
433.13
21.71
89.51
155.91
52.82
102.30
130.81"
128 ZINC
TOXIC ORG.
ALUMINUM
19947.46 19454.19
1392.55 1317.56
274347.12 271633.28
493.27 19710.63
74.99 1365.42
2713.84 273550.64
236.83. 19749.91 197.55
27.13 1365.42 27.13
796.48 273816.13 530.99
IRON
PHOSPHORUS
OIL Si GREASE
19062.59 17479.60 1582.99 18538.28
63478.70 47726.11 15752.59 58261.24
477213.13 438603.83 38609.30 464425.23
524.31 18704.53 358.06
5217.46 60000.39 3478.31
12787.90 464425.23 12787.90
TSS
404120.64 357789.48 46331.16 388775.16 15345.48 400795.79
3324.85
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
163298.09 161281.59
881333.77 796393.31
166132.05 163822.83
1404354.23 1297055.13
2016.50 162295.38
84940.46 853200.39
2309.22 165028.85
107299.10 1368579.40
1002.71 162600.30 697.79
28133.38 865221.02 16112.75
1103.20 165354.31 777.74
35774.83 1383096.38 21257.85
SLUDGE GEN
14774149.79
15411317.69
15533539.81
-------
TABLE XII-6
SUMMARY TABLE
POLLUTANT REDUCTION BENEFITS
INDIRECT DISCHARGERS
RAW WASTE
kg/yr
PSES 0
PSES 1
Removed
kg/yr
Discharged
kg/yr
Removed
kg/yr
Discharged
kg/yr
PSES 2
Removed
kg/yr
Discharged
kg/yr
Steel Subcategory
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
13621.87
447848o92
14793.94
510665.88
12766.83
427921.98
13893.61
485771.70
855.04
19926.94
900.33
24894.18
13161.67
439355.38
14308.20
499953.14
460.20
8493.54
485.74
10712.74
13343.12
442984.44
14489.65
504338.90
278.75
4864.48
304.29
6326.98
U!
Galvanized Subcategory
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
42841.43
85221.07
42943.48
42357.20
73995.35
42412.30
137138.50 123090.53
484.23
11225.72
531.18
14047.97
42635.57
81367.33
42721.51
132276.28
205.86
3853.74
221.97
4862.22
42723.16
83013.93
42813.13
134275.50
118.27
2207.14
130.35
2863.00
Aluminum Subcategory
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
106834.79
348263.78
108394.63
106157.56
294475.98
107516.92
756549.85 688192.90
677.23
53787.80
877.71
68356.95
106498.14
332477.68
107999.14
736349.98
336.65
15786.10
395.49
20199.87
106534.02
339222.65
108051.53
744481.98
300.77
9041.13
343.10
12067.87
Total Subcategory
TOXIC METALS
CONVENTIONALS
TOTAL TOXICS
TOTAL POLLU.
163298.09
881333.77
166132.05
161281.59
796393.31
163822.83
2016.50
84940.46
2309.22
162295.38
853200.39
165028.85
1002.71
28133.38
1103.20
162600.30
865221.02
165354.31
1404354.23 1297055.13 107299.10 1368579.40 35774.83 1383096.38
697.79
16112.75
777.74
21257.85
-------
TABLE XII-7
PRETREATMENT STANDARDS FOR EXISTING SOURCES
STEEL SUBCATEGORY
POLLUTANT OR
POLLUTANT
PROPERTY
MAXIMUM FOR
ANY ONE DAY
MAXIMUM FOR
MONTHLY AVERAGE
mg/m'
(lb/1,000,000 ft2)
mg/m2
(lb/1,000,000
CADMIUM
0.375
(0.077)
0.176
(0.036)
~CHROMIUM
0.493
(0.101)
0.199
(0.041)
COPPER
2.229
(0.457)
1.173
(0.240)
*CYANIDE
0.340
(0.070)
0.141
(0.029)
LEAD
0.176
(0.036)
0.152
(0.031)
NICKEL
1.654
(0.339)
1.173
(0.240)
*ZINC
1.560
(0.32Q)
0.657
(0.135)
TABLE XII-8
PRETREATMENT STANDARDS FOR EXISTING SOURCES
GALVANIZED SUBCATEGORY
POLLUTANT OR
POLLUTANT MAXIMUM FOR MAXIMUM FOR
PROPERTY ANY ONE DAY MONTHLY AVERAGE
mg/m^ (lb/1,000,000 f) mg/m^ (lb/1/000,000 f)
CADMIUM
0.287
(0.059)
0.134
(0.027)
~CHROMIUM
0.376
(0.077)
0.152
(0.031)
~COPPER
1.702
(0.349)
0.896
(0.184)
~CYANIDE
0.260
(0.053)
0.108
(0.022)
LEAD
0.134
(0.027)
0.116
(0.024)
NICKEL
1.263
(0.259)
0.896
(0.184)
~ZINC
1.192
(0.244)
0.502
(0.103)
* THIS POLLUTANT IS REGULATED AT PROMULGATION
457
-------
TABLE XII-9
PRETREATMENT STANDARDS FOR EXISTING SOURCES
ALUMINUM SUBCATEGORY
POLLUTANT OR
POLLUTANT MAXIMUM FOR MAXIMUM FOR
PROPERTY ANY ONE DAY MONTHLY AVERAGE
mg/m2 (lb/1,000,000 ft2) mg/m2 (lb/1,000,000 ft2)
CADMIUM
0.316
(0.065)
0.148
(0.030)
~CHROMIUM
0.415
(0.085)
0.168
(0.034)
COPPER
1.875
(0.384)
0.987
(0.202)
~CYANIDE
0.286
(0.059)
0.118
(0.024)
LEAD
0.148
(0.030)
0.128
(0.026)
NICKEL
1.392
(0.285)
0.987
(0.202)
~ZINC
1.313
. (0.269)
0.553
(0.113)
TABLE XII-10
PRETREATMENT STANDARDS FOR NEW SOURCES
STEEL SUBCATEGORY
POLLUTANT OR
POLLUTANT MAXIMUM FOR MAXIMUM FOR
PROPERTY ANY ONE DAY MONTHLY AVERAGE
mg/m2 (lb/1,000,000 ft2) • mg/m2 (lb/1,000,000 ft2)
CADMIUM
0.063
(0.013)
0,025
(0.005)
~CHROMIUM
0.117
(0.024)
0.047
(0.010)
COPPER
0.404
(0.083)
0.193
(0.040)
~CYANIDE
0.063
(0.013)
0.025
(0.005)
LEAD
0.032
(0.007)
0.028
(0.006)
NICKEL
0.174
(0.036)
0.117
(0.024)
~ZINC
0.322
(0.066)
0.133
(0.027)
* THIS POLLUTANT IS REGULATED AT PROMULGATION
458
-------
TABLE XII-11
PRETREATMENT STANDARDS FOR NEW SOURCES
GALVANIZED SUBCATEGORY
POLLUTANT OR
POLLUTANT MAXIMUM FOR MAXIMUM FOR
PROPERTY ANY; ONE DAY MONTHLY AVERAGE
mg/m2
(lb/1,000,000 ft2)
mg/m2
(lb/1,000,000 ft2)
CADMIUM
0.069
(0.014)
0.027
(0.006)
~CHROMIUM
0.127
(0.026)
0.051
(0.010)
*COPPER
0.439
(0.090)
0.209
(0.043)
~CYANIDE
0.069
(0.014)
0.027
(0.006)
LEAD
0.034
(0.007)
0.031
(0.006)
NICKEL
0.189
(0.039)
0.127
(0.026)
*ZINC
0.350
(0.072)
0.144
(0.029)
TABLE XII—12
PRETREATMENT STANDARDS FOR NEW SOURCES
ALUMINUM SUBCATEGORY
POLLUTANT OR
POLLUTANT MAXIMUM FOR MAXIMUM FOR
PROPERTY ANY ONE DAY MONTHLY AVERAGE
mg/m2
(lb/1,000,000 ft2)
mg/m2
(lb/1,000,000 ft2)
CADMIUM
0.095
(0.019)
0.038
(0.008)
~CHROMIUM
0.176
(0.036)
0.071
(0.015)
COPPER
0.608
(0.125)
0.290
(0.059)
~CYANIDE
0.095
(0.019)
0.038
(0.008)
LEAD
0.048
(0.010)
0.043
(0.009)
NICKEL
0.261
(0.053)
0.176
(0.036) .
~ZINC
0.485
(0.099)
0.200
(0.041)
* THIS POLLUTANT IS REGULATED AT PROMULGATION
459
-------
Intentionally Blank Page
-------
SECTION XIII
BEST CONVENTIONAL POLLUTANT CONTROL TECHNOLOGY
INTRODUCTION
The 1977 Amendments added Section 301(b)(2)(E) to the Act
establishing "best conventional pollutant control technology"
[BCT] for discharges of conventional pollutants from existing
industrial point sources. Conventional pollutants are those
defined in Section 304(a)(4) [biological oxygen demanding
pollutants (BOD%), total suspended solifs (TSS), fecal coliform,
and pH], and any addittional pollutants defined by the
Administrator as "conventional" [oil and grease, 44 FR 44501,
July 30, 1979].
BCT is not an additional limitation but replaces BAT for the
control of conventional pollutants. In addition to other factors
specified in section 304(b)(4)(B), the Act requies that BCT
limitations be assessed in light of a two part
"cost-reasonableness" test. American Paper Institute v. EPA, 660
F.2d 954 (4th Cir. 1981)J The first test compares the cost for,
private industry.to reduce its conventional pollutants with the
costs to publicly owned , treatment works for similar levels of
reduction in their discharge of these pollutants. The second
test examines the cost-effectiveness of additional industrial
treatment beyond BPT. EPA must find that limitations are
"reasonable" under both tests before establishing them as BCT.
In no case may BCT be less stringent than BPT.
EPA first published its methodology for carrying out the BCT
analysis on August 29, 1979 (44 FR 50732). In the case mentioned
above, the Court of Appeals ordered EPA to correct data errors
underlying EPA's claculation of the first test, and to apply the
second cost test. (EPA had argued that a second cost test was
not required.)
EPA has determined that the BAT technology is capable of removing
significant amounts of conventional pollutants. However, EPA has
not yet promulgated a revised BCT methodology in response to the
American Paper Institute v. EPA decision mentioned earlier. EPA
is deferring a decision on the appropriate BCT limitations.
461
-------
Intentionally Blank Page
462
-------
SECTION XIV
ACKNOWLEDGEMENTS
This document has been prepared by the staff of the Effluent
Guidelines Division with assistance from technical contractors/
other EPA offices and other persons outside of EPA. This Section
is intended to acknowledge the contribution of the several
persons who have contributed,to the development of this report.
The collection and organization of information for use in this
report were performed by Hamilton Standard, Division of United
Technologies Corporation under Contract No. 68-01-4668. Some
sections of this report are edited versions of the proposed
development document and supplemental information prepared by
Hamilton Standard. Hamilton Standard's effort was managed by
Daniel J. Lizdas and Robert Blaser and included significant
contributions by Messrs. Clark Anderson, James Brown, Walter
Drake, Peter Formica, Remy Helm, Richard Kearns, Lawrence
McNamara, Lawrence Morris, Jack Nash, Greg Wannenwetsch, Jeffrey
Wehner, Peter Wilk and Peter Williamsj Lori Kucharzyk, and Pat
Bonzek of Hamilton Standard who worked to prepare the manuscript.
Ellen Siegler and Michael Dworkin of the Office of General
Counsel have provided legal advice to the project. Josette
Bailey and Debra Maness have been economic project officers for
the project. Henry Kahn and Richard Kotz provided statistical
analysis and assistance for the project. Alexandra Tarnay
provided environmental evaluations and word processing was
provided by Pearl Smith, Carol Swann, Glenda Nesby, Kaye Storey
and Nancy Zrubek.
Technical direction and supervision of the project have been
provided by Ernst Hall. Technical project officers are Mary
Belefski, Catherine Campbell, Rex Regis and Lee Fletcher; John
von- Hemert and Robert Hardy performed specific technical
assignments. (Where more than one EPA employee in listed for a
specific function the most recent is listed first).
In preparation of this final 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 Jerome
Strauss, Jean Moore, Gayle Riley and John Whitescarver, Robert
Hardy and Robert Smith of Whitescarver Associates (a
463
-------
subcontractor on this contract). Manuscript preparation was
performed by Nan Dewey, Lucy Gentry and Sally Gravely of Versar
Inc.
Appreciation is expressed to Dean Costen, John Geyer, Frank
Graziano, Norman Roller, and other industry personnel who
provided technical guidance during the program.
Finally, appreciation is also expressed to the National Coil
Coating Association and its member plants that participated in
and contributed data for the formulation of this document.
464
-------
SECTION XV
REFERENCES
1. "The Surface Treatment and Finishing of Aluminum and Its
Alloys" by S. Werrick, PhD, Metal Finishing Abstracts, Third
Edition, Robert Draper Ltd., Teddington, 1964.
2. Guidebook & Directory, Metal Finishing, 1974, 1975, 1977 and
1978. American Metals and Plastics Publications Inc., One
University Plaza Hackensack, New Jersey 90601.
3. The Science of Surface Coatings, edited by Dr. H. W.
Chatfield, 1962.
4. Metals Handbook, Volume 2 8th Edition, American Society for
Metals, Metals Park, Ohio.
5. 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
6. "Zincrometal: Coil Coatings Answer to Corrosion" by
Alexander W. Kennedy, Modern Paint and Coatings, September,
1976.
7. How Do Phosphate Coatings Reduce Wear on Movings Parts, W.
R. Cavanagh.
8. Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, 1963, Interscience Publishers, New York.
9. Encyclopedia of Polymer Science and Technology, Second
Edition, 1963, Interscience Publishers, New York.
465
-------
10. Conversation and written correspondence with the following
companies and individuals have been used to develop the data
base:
Parker Company:
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
11. Handbook of Environmental Data on Organic Chemicals,
Verschueren, Karel, Van Nostrand Reinhold Co., New York
1 977.
12. Handbook of Chemistry, Lange, Norbert, Adolph, McGraw Hill,
New York 1973.
13. Dangerous Properties of Industrial Materials. Sax N. Irving,
Van Nostrand Reinhold Co. New York.
14. Environmental Control in the Organic and Petrochemical
Industries, Jones, H. R, Noyes Data Corp. 1971 .
15. Hazardous Chemicals Handling and Disposal, Howes, Robert and
Kent, Robert, Noyes Data Corp., Park Ridge, New Jersey 1970.
16. Industrial Pollution, Sax, N. Irving, Van Nostrand Reinhold
Co., New York 1974. "
17. "Treatability of 65 Chemicals - Part A - Biochemical
Oxidation of Organic Compounds", June 24, 1977, Memorandum,
Murray P. Strier to Robert B. Schaffer.
466
-------
18. "Treatability of Chemicals - Part B - Adsorption of Organic
Compounds on Activated Carbon," December 8, 1977,
Memorandum, Murray P. Strier to Robert B. Schaffer.
19. "Treatability of the Organic Priority Pollutants - Part C -
Their Estimated (30 day avg) Treated Effluents Concentration
A Molecular Engineering Approach", June 1978, Memorandum,
Murray P. Strier to Robert B. Schaffer.
20. Water Quality Criteria Second Edition, edited by Jack Edward
McKee and Harold W. Wolf, 1963 The Resources Agency of
California, State Water Quality Control Board, Publication
No. 3-A.
21. The Condensed Chemical Dictionary, Ninth Edition, Revised by
Gessher G. Hawley, 1977.
22. Wastewater Treatment Technology, James W. Patterson.
23. Unit Operations for Treatment of Hazardous Industrial
Wastes, Edited by D. J. Denyo, 1978.
24. "Development Document For Proposed Existing Source
Pretreatment Standards For The Electroplating Point Source
Category", February 1978, EPA440/1-78/085.
25. Hittman Associates, Inc., "Development Document for Effluent
Limitations Guidelines and Standards of Performance, The
Coil. Coating Industry", EPA Contract No. 68-01-3501,
Washington, August 1976.
26. "Industrial Waste and Pretreatment in the Buffalo Municipal
System", EPA contract #R803005, Oklahoma, 1977.
27. "Pretreatment of Industrial Wastes", Seminar Handout, U.S.
EPA, 1978 o
28. "Sources of Metals in Municipal Sludge and Industrial
Pretreatment as a Control Option", ORD Task Force on
Assessment of Sources of Metals in Sludges and Pretreatment
as a Control Option, U.S., EPA 1977.
29. "Effects of Copper on Aerobic Biological Sewage Treatment",
Water Pollution Control Federation Journal, February 1963 p
227-241.
30. Wastewater Engineering, 2nd edition, Metcalf and Eddy.
467
-------
31. Chemical Technology, L.W. Codd, et. al., Barnes and Noble,
New York, 1972
32. "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
33. "Factors Influencing the Condensation of 4-aminoantipyrene
with derivatives of Hydroxylbenzene - I. a Critique," Samuel
D. Faust and Edward W. Mikulewicz, Water Research, 1967,
Pergannon Press, Great Britain
30. Scott, Murray C., "SulfexTi - A New Process Technology for
Removal of Heavy Metals from Waste Streams, " presented at
1977 Purdue Industrial Waste Conference, May 10, 11, and 12,
1977.
31. "SulfexTt Heavy Metals Waste Treatment Process," Technical
Bulletin, Vol. XII, code 4413.2002 (Permutit®) July, 1977.
32. Scott, Murray C., "Treatment of Plating Effluent by Sulfide
Process," Products Finishing, August, 1978.
33. Lonouette, Kenneth H., "Heavy Metals Removal," Chemical
Engineering, October 17, pp. 73-80.
34. Curry, Nolan A., "Philogophy and Methodology of Metallic
Waste Treatment," 27th Industrial Waste Conference.
35. 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.
36. Bellack, Ervin, "Arsenic Removal from Potable Water,"
Journal American Water Works Association, July, 1971.
37. 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.
38. 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.
468
-------
39. Strier, Murray P., "Suggestions for Setting Pretreatment
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.
40. Rohrer, Kenneth L., "Chemical Precipitants for Lead Bearing
Wastewaters," Industrial Water Engineering, June/July, 1975.
41. 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
Hydroxides," International Journal of Air and Water
Pollution, Vol. 8, 1964,pp. 537-556.
42. Bhattacharyya, 0., Jumawan, Jr., A.B., and Grieves, R.B.,
"Separation of Toxic Heavy Metals'by Sulfide Precipitation,"
Separation Science and Technology, 14(5), 1979, pp. 441-452.
43. Patterson, James W., "Carbonate Precipitation Treatment for
Cadmium and Lead," presented at WWEMA Industrial Pollutant
Conference, April 13, 1978.
44. "Coil Coating, The Better Way," National Coil Coaters
Association, December, 1978.
45. "An Investigation of Techniques for Removal of Cyanide from
Electroplating Wastes," Battelle Columbus Laboratories,
Industrial Pollution Control Section, November, 1971.
46. Patterson, James W. and Minear, Roger A., "Wastewater
Treatment Technology," 2nd edition (State of Illinois,
Institute for Environmental Quality) January, 1973.
47. Chamberlin, N.S. and Snyder, Jr., H.B., "Technology of
Treating Plating Waste," 10th Industrial Waste Conference.
48. 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.
49. 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, pp.
2663-2675.
50. 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.
469
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51. Stover, F 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, pp.
2165-2175.
52. Neufeld, Howard D. and Hermann, Edward R., "Heavy Metal
Removal by Activated Sludge," Journal of Water Pollution
Control Federation, Vol. 47, No. 2, February, 1975, pp.
310-329.
53. Schroder, Henry A. and Mitchener, Marian, "Toxic Effects of
Trace Elements on ' the Reproduction of Mice and Rats,"
Archieves of Environmental Health, Vol. 23, August, 1971,
pp. 102-106.
54. Venugopal, B. and Luckey, T.D., "Metal Toxicity in Mannals"
(Plenum Press, New York, N.Y.), 1978.
55. Poison, C.J. and Tattergall, R.N., "Clinical Toxicology,"
(J.B. Lipinocott Company), 1976.
56. Hall, Ernst P. and .Barnes, Deveraeaux, "Treatment of
Electroplating Rinse Waters and Effluent Solutions,"
presented to the American Institute of Chemical Engineers,
Miami Beach, F1., November 12, 1978.
57. 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.
58. Davis, III, James A., and Jacknow, Joel, "Heavy Metals in
Wastewater in Three Urban Areas, "Journal of Water Pollution
Control Federation^ September, 1975, pp. 2292-2297.
59. Klein, Larry A., Lang, Martin, Nash, Norman and Kirschner,
Seymour L., "Sources of Metals in New York City Wastewater,"
Journal of Water Pollution Control Federation, Vol. 46, No.
12, December, 1974, pp. 2653-2662.
60. 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.
61. Ghosh, Mriganka M. and Zugger, Paul D., "Toxic Effects of
Mercury on the Activated Sludge Process," Journal of Water
Pollution Control Federation, Vol. 45, No. 3, March, 1973,
pp. 424—433.
470
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62. 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.
63. Oliver, Barry G. and Cqsgrove, Ernest G., "The Efficiency of
Heavy Metal Removal by a Conventional Activated Sludge
Treatment Plant," Water Re-soarch, Vol. 8, 1074, pp. 869-
874.
64. Ambient Water Quality Criteria for Acenapthane, PB117269
Criterion Standards Division, Office of Water Regulations
and Standards (45 FR 79318-79379, November 28, 1980).
65. Ambient Water Quality Criteria for Chlorinated Ethanes,
PB117400 Criterion Standards Division, Office of Water
Regulations and Standards (45 FR 79318-79379, November 28,
1980).
66. Ambient Water Quality Criteria for Dichloroethylenes,
PB117525 Criterion Standards Division, Office of Water
Regulations and Standards (45 FR 79318-79379, November 28,
1980).
67. Ambient Water Quality Criteria, for Dimethylphenol PB117558
Criterion Standards Division, Office of Water Regulations
and Standards (45 FR 79318-79379, November 28, 1980).
68. Ambient Water Quality Criteria for Fluoranthene, PB117608,
Criterion Standards Division, Office of Water Regulations
and Standards (45 FR 79318-79379, November 28, 1980.
69. Ambient Water Quality Criteria" for Isophorone, PB117673,
Criterion Standards Division, Office of Water Regulations
and Standards (45 FR 79318-79319, November 28, 1980).
70. Ambient Water Quality Criteria for Napthalene, PB296786,
Criterion Standards Division, Office of Water Regulations
and Standards (45 FR 79318-79379, November 28, 1980).
71. Ambient Water Quality; Criteria for Phenol, PB117772,
Criterion Standards Division, Office of Water Regulations
and Standards (45 Fr 79318-79379, November 28, 1982).
72. Ambient Water Quality Criteria for Phthalate Esters,
PB117780, Criterion Standards Division, Office of Water
Regulations and Standards (45 FR 79318-79379, November 28,
1980).
471
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73. Ambient Water Quality Criteria for Polynuclear Aromatic
Hydrocarbons, PB117806, Criterion Standards Division, Office
of Water Regulations and Standards (45 FR 79318-79379,
November 28, 1980).
74. Ambient Water Quality Criteria for Toluene, PB117855,
Criterion Standards Division, Office of Water Regulations
and Standards (45 FR 79318-79379, November 28, 1980).
75. Ambient Water Quality Criteria for Trichloroethylene,
PB117871, Criterion Standards Division, Office of Water
Regulations and Standards (45 FR 79318-79379, November
1980).
76. Ambient Water Quality Criteria for Cadmium, PB117368,
Criterion Standards Division, Office of Water Regulations
and Standards (45 FR 79318-79379, November 28, 1980
77. Ambient Water Quality Criteria for Chromium, PB117467,
Criterion Standards Division, Office of Water Regulations
and Standards (45 FR 79318-79379, November 28, 1980).
78. Ambient Water Quality, Criteria for Copper PB1 1 7475 Criterion
Standards Division, Office of Water Regulations and
Standards (45 FR 79318-79379 November 28, 1980).
79. Ambient Water Quality Criteria for Cyanide, PB117483,
Criterion Standards Division, Office of Water Regulations
and Standards (45 Fr 79318-79379, November 26, 1980).
80. Ambient Water Quality Criteria for Lead, PB117681, Criterion
Standards Division, Office of Water regulations and
Standards (45 FR 79318-79379 November 28, 1980).
81. Ambient Water Quality Criteria for Nickel, PB117715,
Criterion Standards Division, Office of Water Regulations
and Standards (45 FR 79318-79319 November 28, 1980).
82. Ambient Water Quality Criteria for Zinc, PB117897 Division,
Office of Water Regulations and Standards (45 FR 79318-
79379). July 25, 1979).
83. 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.
84. Electroplating Engineering Handbook, edited by H. Kenneth
Graham, Van Nostrand Reinhold Company, New York, 1971.
472
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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.
Accumulator or Looper - A series of fixed and movable rolls which
serves as a reservoir of basis material in a continuous
coating line. Their purpose is to provide enough basis
material to avoid shutting down the line when attaching a
new roll or removing a completed one.
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) as
amended by the Clean Water Act of 1977 (P.L. 95-217).
Activator - A material that enhances the chemical or physical
change on the coated coil 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.
Air Drying - A process whereby the coil is dried by air before
proceeding to the next process step.
Air Knife - A device with air jets to permit the use of hot or
ambient air to control dragout and temperature
Alqicide - Chemical used in the control of phytoplankton (algae)
in water.
Alkaline Cleaning - A process where mineral deposits, animal fats
and oils are removed from the bare metal surface of a coil.
Solutions containing caustic soda, soda ash, alkaline
silicates, alkaline phosphates and ionic and nonionic
detergents are commonly used.
Alkalinity - The quantitative capacity of aqueous media to react
with hydrogen ions.
473
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Aluminum Basis Material - Means aluminum, aluminum alloys and
aluminum coated steels which are processed in coil coating.
Anionic Surfactant - An ionic type of surface-active substance
that has been widely used in cleaning products. The hydro-
philic group of these surfactants carri
in the washing solution.
es a negative charge
Anodizing - An electrochemical process of controlled aluminum
oxidation producing a hard, transparent oxide up to several
mils in thickness.
Applicator Roll - The roll in a roll coater which applies the
paint, conversion coat, or other liquid to a moving strip of
metal.
Area Processed - See Processed Area.
Backwashinq - The process of cleaning a filter or ion exchange
column by reversing the flow of water.
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.
Baking - A drying or curing process carried out in an enclosure
where the temperature is maintained in excess of 150°C.
Basis Material or Metal - That substance of which the workpieces
are made and that receives the coating and the treatments in
preparation of coating.
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)(1) 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 matter 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
BPT - The best practicable control technology currently available
under Section 304(b)(1) of the Act.
Buffer - Any of certain combinations of chemicals used to
stabilize the pH values or alkalinities of solutions.
Cake - The material resulting from drying or dewatering sludge.
Calibration - The determination, checking, or rectifying of the
graduation of any instrument giving quantitative
measurements.
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. laneous
runoff, etc.).
Chemical Coagulation - The destabilization and initial
aggregation of colloidal and finely divided suspended matter
by the addition of a floc-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.
475
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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.
Chemcial 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.
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)
Coil - Means a strip of basis material rolled into a roll for
handling.
Coil Coating A process of applying a protective coating to a
coil which involves at least two of the following
operations: cleaning, conversion coating, and painting.
476
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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 treatment process 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.
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 solutions, or
sludge by means of a scavenger service.
Conversion Coating - The process of applying a chromate,
phosphate, complex oxide or other similar protective coating
to a coil.
Cooling Tower - A device used to cool water used in the manufac-
turing processes before returning the water for reuse.
Curing - A process which follows coating and uses heat to
evaporate solvents and prepare the coil for further
processing or recoiling.
Degreasing - The process of removing grease and oil from the sur-
face of the coil.
Dewatering - A process whereby water is removed from sludge.
477
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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 in water. Actually the term is
defined by the method used in determination. In water and
wastewater treatment, the Standard Methods tests are used.
Draqout - The solution that adheres to the coil and is carried
past the edge of the treatment tank.
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.
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 consitutents, 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.
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.
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.
478
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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.
Flow-Proportioned Sample - A sampled stream whose pollutants are
apportioned to contributing streams in proportion to the
flow rates of the contributing streams.
Galvanized Basis Material - Means zinc coated steel, galvanized,
brass and other copper base strip which is processed in coil
coating.
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 bil, 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.
479
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Industrial Wastes - The liquid 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.
Lagoon - A man-made pond or lake for holding wastewater for the
removal of suspended solids. Lagoons are also used as
retentioft ponds.
Laminator - A _uri.it which may be included in a coil line to permit
the fastening of a film by an adhesive process or a
thermoplastic process.with or without heat.
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.
Make-Up Water - Total amount of water used by process.
Milligrams Per Liter (mg/1) - This is a weight per volume desig-
nation used in water and wastewater analysis.
Mutagenic - Referring to the ability of a substance to increase
the frequency or extent of mutation. j
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.
Neutralization - Chemical addition of either acid or base to a
solution such that the pH is adjusted to approximately 7.
480
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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.
NSPS - New source performance standards under Section 306 of the
Act.
Orthophosphate - An acid or salt containing phosphours as P04.
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.
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.
pH - 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 - The process of forming a conversion coat
usually on steel by immersing or spraying a hot solution of
iron or zinc phosphate.
481
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Pick Up Roll - A roll which revolves within a pan and is
partially submerged in the liquid being applied and
transfers it to the transfer or applicary roll.
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
waste stream which may alter the chemical, physical,
biological, radiological integrity of water.
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.
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 addition of
chemicals.
Pretreatment - Any wastewater treatment process used to reduce
pollution load partially before the wastewater is introduced
into a main sewer system or delivered to a treatment plant
for substantial reduction of the pollution load.
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.
Processed Area - (Expressed in terms of square meters). The area
of the coil actually processed. Both sides of the coil are
included.
Process Water - Any water which during manufacturing or
processing, comes into direct contact with or results from
482
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the production or use of any raw materials, intermediate
product, finished product, by-product, or waste product.
Production Area - The area of one side of the coil.
PSES - Pretreatment standards for existing sources of indirect
discharges under Section 307(b) of the Act.
Publicly Owned Treatment Works - 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.
Recoiler - Apparatus to recoil the strip after it is processed.
Rectangular Weir - A weir having a notch that is rectangular in
shape.
Recycled Water - Process water which is returned to the same
process after treatment.
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.
Reverse Roll Coating - Coating with the coating roll revolving in
a direction opposite to that of the strip.
Rinse - Water for removal of dragout by dipping, spraying,
fogging, etc.
Roll Coating A coat to a coil using rollers.
483
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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.
!
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.
Sludge - The solids (and accompanying water and organic matter)
which are separated from sewage or industrial wastewater.
Sludge Dewaterinq - A process used to increase the solids
concentration of sludge.
Sludge Disposal - The final disposal of solid wastes.
Solvent - A liquid capable of dissolving or dispersing one or
more other substances.
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.
Squeegee - Device used between stages to wipe off excess material
applied to the coil to reduce dragout from one process tank
to following process tanks.
Steel feasis Material - Means cold rolled steel, hot rolled steel,
and chrome, nickel and tin coated steel which are processed.
484
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Stitcher - A machine used to join rolls together to form a
continuous strip for coating.
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.
Top Coat - The final applied coating,- usually a clear organic
film applied over a two coat, two color- printed pattern sys-
tem, such as wood graining.
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.
Transfer Roll - The roll between the pick-up and applicator roll
which transfers the liquid to the applicator roll.
Treatment Facility Effluent - Treated process wastewater before
discharge.
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.
Uncoiler - An apparatus at the beginning of the line to pay off
the strip and control tension.
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
485
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is essential to effective roller-coater operation and
uniform dry films thickness.
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 area of coil (expressed as 1/sq m of processed
area).
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.
486
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METRIC UNITS
MULTIPLY (ENGLISH UNITS)
ENGLISH UNIT
acre
acre - feet
British Thermal
Unit
British Thermal
Unit/pound
cubic feet/minute
cubic feet/second
cubic feet
cubic feet
cubic inches
degree Fahrenheit
feet
gal Ion
gallon/minute
horsepower
i nches
i nches of mercury
pounds
million gallons/day
mile
pound/square
inch (gauge)
square feet
square inches
ton (short)
yard
CONVERSION TABLE
by
TO OBTAIN (METRIC UNITS)
ABBREVIATION CONVERSION
ABBREVIATION
METRIC UNIT
ac
0.405
ha
hectares
ac ft
1233.5
cu m
cubic meters
BTU
0.252
kg cal
kilogram - calories
BTU/lb
0.555
kg cal/kg
kilogram calories/kilogra
cfm
0.028
cu m/min
cubic meters/minute
cfs
1.7
cu m/min
cubic meters/minute
cu ft
0.028
" cu m
cubic meters
cu ft
28.32
1
1 iters
cu in
16.39
cu cm
cubic centimeters
[F
0.555([F-32)*
[C
degree Centigrade
ft
0.3048
m
meters
gal
3.785
1
liters
gpm
0.0631
1/sec
liters/second
hp
0.7457
kw
killowatts
in
2.54
cm
centimeters
in Hg
0.03342
atm
atmospheres
lb
0.454
kg
kilograms
mgd
3,785
cu m/day
cubic meters/day
mi
1.609
km
kilometer
psig
(0.06805 psig +1)*
atm
atmospheres (absolute)
sq ft
0.0929
sq m
square meters
sq in
6.452
sq cm
square centimeters
ton
0.907
kkg
metric ton (1000 kilograrr.
yd
0.9144
m
meter
* Actual conversion, not a multiplier
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