v>EPA
United States
Environmental Protection
Agency
Technology Transfer
EPA/625/10-85/001
September 1985
Revised
Environmental
Regulations
and Technology
The Electroplating Industry
r -1
1
-------
Cover Photograph: i
Blend tank following the reduction of chrome and cyanide from electroplating wastewater.
-------
Technology Transfer . EPA/625/10-85/001
Environmental
Regulations
and Technology
The Electroplating Industry
September 1985
This report was prepared jointly by
Industrial Technology Division
Office of Water Regulations and Standards
Office of Water
Washington, DC 20460
and
Center for Environmental Research Information
Office of Research Program Management
Office of Research and Development
Cincinnati, OH 45268
-------
Three-stage blending and neutralization system.
This report was prepared by CENTEC Corp., Reston, VA and JACA Corp.,
Fort Washington, PA. Regulatory content was reyiewed by EPA's Office of
General Counsel and the Office of Water Enforcement and Permits. EPA would
like to thank the American Electroplaters' Society, Inc. for technical review.
Photos courtesy of Rainbow Research, Stuart, FL; Hydro-Fax Division of
Amchem Products, Ambler, PA; Baldwin Hardware Inc., Reading, PA;
and SPS Technologies, Jenkintown, PA. ;
This document has been reviewed in accordance wjth U.S. Environmental
Protection Agency policy and approved for publication. Mention of
trade names or commercial products does not constitute endorsement or
recommendation for use. '
-------
Contents
1. Overview 1
2. Water Pollution Control Regulations 2
Legislation 2
Regulations 5
Monitoring Requirements 5
Variances 6
Pollutants in Intake Waters 6
Existing Direct Dischargers 7
Existing Indirect Dischargers 8
Removal Allowances 10
New Sources 11
3. Water Pollution Control Technologies 12
Process Modifications 13
Wastewater Treatment 14
Becoming a Direct Discharger 17
4. Water Pollution Control Case Histories 18
Case History 1. Economic Evaluation of Evaporator Installation . 18
Case History 2. Automated Drag-out Recovery 20
Case History 3. Electrochemical Recovery 22
Case History 4. Stream Segregation 23
Case History 5. Sulfide Precipitation 24
Case History 6. Ion Exchange for Heavy Metal Removal 26
5. Hazardous Waste Regulations and Management 28
Hazardous Waste Regulations 28
Identification of Hazardous Wastes 28
Requirements for Hazardous Waste Generators 29
Special Provisions for Small Quantity Generators 31
Requirements for Storage and Disposal Facilities 31
Hazardous Waste Delisting 32
Hazardous Waste Management 32
Reducing Waste Loads 33
Optimizing Waste Treatment Systems 34
Sludge Dewatering 35
6. Pollution Control Financing Alternatives 38
Income Tax Provisions 33
Small Business Administration 39
The 7(a) Program 39
Pollution Control Financing Guarantees 39
The Section 503 Program 39
Economic Development Administration 40
Farmers' Home Administration 40
Other Sources of Financing 40
7. EPA Sources of Additional Information 41
EPA Headquarters Office 41
EPA Regional Offices 41
References
.43
in
-------
Illustrations
Figures
1. Conventional Wastewater Treatment System for Electroplating 15
2. Annual Sewer Costs as a Function of Flow Rates 17
3. Evaporative Recovery Systems 19
4. Annual Costs and Savings as a Function of Evaporator Systems 19
5. Automated Drag-Out Recovery System 20
6. Drag-Out Recovery as a Function of Recycle Rinse Ratio 21
7. Electrolytic Recovery System 22
8. Wastewater Treatment System with Segregated Treatment of Nickel 23
9. Wastewater Treatment System with Sulfide Precipitation 25
10. Combination Batch and Continuous Treatment System 26
11. Obligations of Hazardous Waste Generators under RCRA 30
12. Annual Cost of Sludge Disposal 33
13. Sludge Generation Rates for Three Wastewater Treatment Systems 34
14. Sludgfe Volume as a Function of Solids Concentration 35
15. Low-Pressure Recessed Plate Filter Press 36
16. Sludge Disposal Costs with and without Filter Press 37
Tables ;
1. Summary of Environmental Legislative Activities
Affectjng the Electroplating Industry 3
2. Applicable Effluent Limitation Guidelines for
Existing Sources and New Sources 6
3. Efflueht Limitations for Existing Direct Dischargers, Existing Indirect
Dischargers with Metal Finishing Facilities, and New Sources 7
4. Applicable Subparts for Existing Indirect Nonintegrated Sources 9
5. Pretre:atment Standards for Existing Dischargers with
Indirect Nonintegrated Facilities • 9
6. Compliance Schedule for All Existing Indirect Sources 11
7. Economic Evaluation of Evaporator Installation 18
8. Effluent Quality After Segregation of Nickel Waste Stream 23
9. Effluent Quality After Sulfide Precipitation 24
10. Effluent Quality After Ion Exchange 27
11. ToxiclWaste Limits Set by EPA's Extraction Procedure Toxicity Test . 29
iv
-------
1. Overview
Under Federal law, the electroplating
industry is bound by a multitude of
pollution control requirements for
wastewater and solid waste
residues. The U.S. Environmental
Protection Agency (EPA) is
responsible for preparing the
detailed regulations and establishing
the administrative procedures for
carrying out these laws. Because the
wastewater and solid waste laws
were passed at different times, EPA's
schedule for implementing pollution
control requirements differs for each
of these areas. Consequently,
electroplaters must keep informed of
new and changing regulations. An
integrated approach to compliance
can reduce compliance costs
considerably.
Electroplating wastewater pollutants
of greatest concern are toxic metals
(cadmium, copper, chromium,
nickel, lead, and zinc); cyanide; toxic
organics (grouped together as total
toxic organics); and conventional
pollutants (total suspended solids
and oil and grease). These and other
constituents degrade water quality
and endanger aquatic life and
human health. They also corrode
equipment, generate hazardous
gases, cause treatment plant
malfunctions, and make the sludge
disposal more difficult.
This publication provides the
electroplating industry with a
summary of the laws, regulatory
activities, and technologies that
affect decisions regarding
wastewater treatment and solid
waste handling and disposal. EPA's
recently promulgated regulations on
water pollution control are presented
in Chapter 2, and wastewater
treatment technologies and case
histories are discussed in Chapters 3
and 4 respectively. Chapter 5
presents information on the current
status of sludge disposal regulations
and technologies, and operating
techniques that can reduce sludge
disposal costs. Various sources of
financial assistance available
through Federal programs are
presented in Chapter 6.
This publication is an update of a
1980 EPA publication of the same
name (EPA publication number
625/10-80-001). It has been revised to
reflect changes in the EPA
regulations as well as the pollution
control technologies that affect the
electroplating industry.
A companion document,
Environmental Pollution Control
Alternatives: Reducing Water
Pollution Control Costs in the
Electroplating Industry (EPA
publication number 625/5-85-016a),
explores the cost tradeoffs of
wastewater reduction and materials
recovery technologies and includes a
brief discussion of sludge handling.
It is intended to assist in the process
of selecting an optimum wastewater
control system.
-------
2. Water Pollution
Control
Regulations
Electroplaters must understand and
comply with several environmental
regulations; particularly the
regulations developed for the metal
finishing ar>d electroplating
categories. This section is intended
to summarize and clarify these
regulations and the laws behind
them. |
Legislation
The environmental legislation
passed by Congress since 1972
which has affected water pollution
control and waste management in
the electroplating industry is
summarize^ in Table 1. Prior to 1972,
water pollution control requirements
were established by the states and
were based primarily on waterbody
uses such as drinking, swimming,
fishing, and navigation. The state
agencies were to identify water uses,
establish the water quality
conditions hecessary to support
these uses, and apply a water quality
standard to each stream or stream
portion. Where a standard was not
being meVattempts were made to
exact compliance through technical
discussions and enforcement action.
This strategy was generally
ineffective (due to political, technical,
and legal weaknesses: some stream
use designations were tailored to
protect or attract industrial
development; adequate information
was not available to link water
quality with wastewater discharges;
the health Of aquatic ecosystems
was not adequately considered; and
implementation of requirements
were not consistent from state to
state. i
Congress addressed these problems
in 1972 with the passage of Public
Law (PL) 92-500, the Federal Water
Pollution Control Act (FWPCA)
Amendments. The goals of the
Amendments were to:
• Achieve "fishable/swimmable"
quality for all waters by 1983
• Eliminate pollutant discharge to all
waterways by 1985
• Eliminate all toxic pollutant
hazards.
Not only did the Amendments
strengthen the current system of
setting water quality standards
based on the waterbody use, but
they also established limitations on
industrial effluents and applied them
uniformly across the nation by:
• Establishing three levels of
effluent limitations for direct
dischargers of a specific industrial
category (that is, plants
discharging directly into public
waterways). These "technology-
based" limitations were to reflect
controls that an entire industry is
capable of based on technology
that is being used or can be used
(as opposed to controls to achieve
specific water quality standards
for a particular waterbody). The
three levels were: best practicable
technology (BPT), to be achieved
by 1977; best available technology
(BAT), to be achieved by 1983
(later changed to 1984); and new
source performance standards
(NSPS), to be achieved when a
new source begins operation. The
Act defines "new source" as any
source whose construction begins
after the publication of applicable
proposed regulations.
• Establishing industry-specific
effluent limitations for indirect
dischargers, that is, plants
discharging into publicly owned
wastewater treatment works, or
POTWs.
• Establishing an expanded Federal
program of financial assistance for
planning and constructing
POTWs.
• Establishing special controls for
toxic pollutants.
• Requiring National Pollutant
Discharge Eliminatipn System
(NPDES) permits for all sources of
pollution; this provided the first
major direct enforcement
mechanism to bring violators into
compliance.
-------
Table 1.
Summary of Environmental Legislative Activities Affecting the Electroplating Industry
Year
Legislation
Requirements
1972
Federal Water Pollution Control Act (FWPCA)
Amendments (Public Law 92-500)
1976
1977
National Resource Defense Council (NRDC)
Consent Decree (NRDC et al. vs. Train)
Resource Conservation and Recovery Act (RCRA)
(Public Law 94-580)
Clean Water Act (Public Law 92-217)
1984
Hazardous and Solid Waste Amendments of 1984
(Public Law 98-616)
Required all industries discharging into waterways to meet technology-based standards
of pollution control:
Best Practicable Technology (BPT) - By July 1, 1977
Best Available Technology (BAT) - By 1983 (later revised to 1984)
New Source Performance Standards (NSPS) - If source begins construction after publica-
tion of the applicable proposed regulations.
Required all industries discharging into municipal systems to attain industry-specific
effluent limitations (pretreatment standards).
Required periodic review and updating of technology-based requirements.
Established National Pollutant Discharge Elimination System (NPDES) permit program.
Required self-monitoring by plants discharging to navigable waters.
Established Federal control over municipal systems.
Committed EPA to a schedule for developing BAT effluent limitations for 21 major
industries covering 65 recognized toxic substance classes (129 specific compounds).
This schedule was later incorporated into the Clean Water Act.
Established controls for disposal of all solid wastes.
Defined hazardous solid wastes. Established tests to determine which wastes are
covered.
Established standards for solid waste generators, storage facilities, and disposal sites.
Established manifest system for transportation of hazardous wastes.
As an amendment to FWPCA, revised FWPCA deadlines.
Defined classes of pollutants as toxic, conventional, and nonconventional with major
emphasis on the toxic compounds associated with the NRDC Consent Decree.
Linked pretreatment standards to BAT guidelines for toxics.
Established BCT (Best Conventional Technology) level of compliance for industrial
discharges of conventional pollutants (e.g., oil and grease, pH, suspended solids,
biochemical oxygen demand) based upon the cost to municipalities to treat conven-
tional pollutants and industries' incremental treatment costs.
Authorized municipal systems to relax pretreatment standards under certain conditions
for individual dischargers.
As an amendment to RCRA, brought small-quantity generators (100 to 1,000 kg/month)
under RCRA requirements. Small-quantity shipments must be accompanied by mani-
fests; small-quantities can be stored on-site for 180 days.
Required certification by generators after 9/1 /85 that the generation of hazardous wastes
have been minimized.
Required new underground storage tanks of petroleum and hazardous wastes to be
constructed to prevent leaks, and existing tanks to be monitored for leaks.
Prohibited landfilling of bulk or noncontainerized liquids after 5/8/85.
Banned certain wastes from land disposal unless they can be demonstrated not harmful
to human health and human environment.
Required certain surface impoundments receiving hazardous wastes to be retrofitted
with double liners, groundwater monitoring capabilities, and leachate collection sys-
tems.
Required EPA to report to Congress on hazardous wastes not addressed by RCRA
because they are sent through municipal sewers.
-------
In 1976 EPA was sued by the
National Resources Defense Council
(NRDC) and others for not
expeditiously issuing regulations
under the 1972 Amendments. Later
that year, EPA agreed to focus its
attention on potentially toxic
substances. This agreement
(referred to as the NRDC Consent
Decree or the Settlement
Agreement) required that toxic
pollutants be controlled to the extent
technologically feasible by including
toxic substances in the standards to
be issued for individual industries.
The agreement committed EPA to a
schedule for developing BAT effluent
limitations for 21 major industries
(including electroplating and metal
finishing) for 65 classes of toxic
pollutants. EPA later refined the 65
classes of pollutants into a list of 126
specific substances.
In 1977 many provisions of the NRDC
Consent Decree and other changes
were incorporated into water
pollution control legislation as the
Clean Watef Act of 1977 (PL 95-217).
The goals of the Clean Water Act of
1977 were identical to those
originally defined in the 1972 FWPCA
amendments, but the language of
the Act placed strong emphasis on
the control iof toxic pollutants and
the control bf industrial wastes
discharged;to POTWs. In addition,
these changes were made:
Three classes of pollutants were
defined: toxic, conventional, and
nonconventional.
A new level of technology which
was to be based on treatment
costs was defined (BCT, or best
conventional technology) for
conventional pollutants.
EPA was required to address the
65 classes of pollutants (126
specific substances) for both direct
and indirect dischargers.
Individual POTWs were authorized
to relax pretreatment standards
for individual dischargers if the
POTW could be shown to remove
certain pollutants of the
discharger.
Barrel electroplating operation
-------
Regulations
In order to provide specific guidance
for carrying out the requirements of
the legislation, EPA has prepared a
number of regulations. These
provide permit writers, whether from
a state, or EPA with a municipal
authority, guidelines for
incorporating discharge or effluent
limitations into a permit. While EPA
retains ultimate authority to enforce
compliance with the conditions of
the permit, most states currently
operate permitting programs under
EPA jurisdiction. The regulations
contain specific performance
standards for processes and
contaminants that sources should be
able to achieve.
Wastewater regulations, including
enforcement mechanisms, have
been divided into several layers of
categories: those for existing and
new sources; and those for direct
and indirect dischargers. Direct
dischargers are regulated by the
NPDES, under which EPA or its state
equivalent issues a separate permit
to each discharger containing
specific discharge limitations,
reporting requirements, and
compliance schedules. NPDES
permits are renewable every five
years. Indirect dischargers must
conform to national pretreatment
standards, both general and specific,
which are enforced by the local
government under EPA oversight
authority. The Federal government
has authority to ensure compliance
with the conditions of the permit. If
violations of state-issued permits are
not followed by appropriate
enforcement action, EPA can initiate
its own action after 30 days notice.
For regulating purposes,
electroplating plants have been
further divided into several
categories. Facilities are first divided
into captive and job shops. A captive
shop owns more than 50 percent of
the area of the materials undergoing
metal finishing in a calendar year. A
job shop owns 50 percent or less.
Captive and job shops are further
divided into integrated plants (those
that combine electroplating waste
streams with other process waste
streams prior to discharge) and
nonintegrated plants (those whose
wastewater discharges come only
from electroplating operations).
Most integrated facilities are captive
operations that perform a wide
range of metal finishing processes.
The electroplating and metal
finishing water pollution control
regulations are contained in the U.S.
Code of Federal Regulations (CFR),
Title 40, Parts 413 and 433,
respectively.* The specific regulation
which applies to a particular facility
is presented in Table 2. It should be
noted that all sectors of the industry
are covered by the metal finishing
regulations except for existing job
shop and independent printed circuit
board manufacturers' (IPCBM)
facilities which are indirect
dischargers. Details of the
regulations are discussed below
following topics of interest to all
plants: monitoring requirements,
variances, and pollutants in intake
waters.
*The Code of Federal Regulations, Title
40, Protection of the Environment, can
be obtained from the Superintendent of
Documents, U.S. Government Printing
Office, Washington, DC 20402.
Monitoring Requirements. To
provide regulatory officials with
information on the amounts of
pollutants being discharged,
monitoring reports must be
submitted to the permitting authority
by both direct and indirect
dischargers. EPA requires, through
the NPDES permit process, that
direct dischargers monitor their own
wastes in a manner specified by EPA
in the industry regulations and by
the permitting authority. The
discharger must keep adequate
records and furnish them to EPA on
request or annually unless other
requirements are imposed by the
NPDES authority. Indirect
dischargers must submit monitoring
reports twice yearly to the permitting
authority.
-------
Monitoring frequency, which is
based primarily on wastewater
variability and flow, is specified in
the permit. Plants with large and/or
highly variable waste streams are
usually required to monitor more
frequently. In most cases, plants are
required to monitor a minimum of
one sample per month for metals
and cyanide. The electroplating
regulations specify that monitoring
for cyanide must be carried out at
one of two locations: either after
cyanide treatment and before
dilution with other streams, or from
the final effluent if the limitations in
the plant's permit are
mathematically adjusted based on
the dilution ratio of the cyanide
waste stream flow to the effluent
flow.
In lieu of requiring monitoring for
total toxic organics (TTO), the
permitting authority may allow
dischargers to certify that con-
centrated toxic organics are not
dumped into wastewaters and that
an approved toxic organic manage-
ment plan is being implemented.
This certification will allow plants to
avoid the high cost of TTO analysis.
If a plant performs TTO monitoring,
the analysis can be limited to those
pollutants that would reasonably be
expected to be present
Variances. Electroplaters who can
substantiate that their processes are
fundamentally different from those
that were used as the basis for the
categorical technology-based
standards can apply for a variance
from the standard. This applies to
both direct and indirect dischargers
and to all types of pollutants.
Variances granted by the permitting
authority can establish equal, more,
or less stringent standards than the
categorical standard.
Normally, indirect dischargers must
apply for variances within 180 days
of the date on which the
requiremerits became effective or
the date on which a source applied
for and was ascertained to be in a
certain source category. For
electroplaters this normal time
period has elapsed. However,
because of a court case, the period
will be reopened by EPA; therefore,
an indirect discharger should contact
the permit ^ssuing authority
regarding eligibility.
Table 2.
Applicable Effluent Limitation Guidelines for Existing Sources and New Sources
| Applicable Guidelines"
For direct dischargers, the initial time
period to apply for variances has
expired. However, any time an
NPDES permit is being renewed, the
discharger may apply for a variance
during the public comment period.
Pollutants in Intake Waters. No
direct or indirect discharger is
required to install treatment
equipment just to treat pollutants
that are in a plant's intake water.
Upon the discharger's, request,
technology-based standards shall
be adjusted to reflect credit for
pollutants in the discharger's intake
water if 1) the effluent limitation
guideline provides for it, or 2) the
discharger demonstrates that its
proposed control system would
meet the limitations in the absence
of pollutants in the intake water.
Direct
Dischargers
Indirect
Dischargers
EXISTING SOURCES
Nonintegrated Plants
Electroplating—Job Shop
Electroplating—Captive
Independent Printed Circuit Board Mfg.
Non-independent Printed Circuit Board Mfg.
Integrated Plants
Electroplating Job Shop
Electroplating Captive
Independent Printed Circuit Board Mfg.
Non-independent Printed Circuit Board Mfg.
NEW SOURCES
MF
MF
MF
MF :
MF
MF
MF
MF
MF
E
E&MF
E
E&MF
E
E&MF
E
E&MF
MF
•E = Electroplating Effluent Limitation Guidelines (40 CFR 413). See also Table 5.
MF = Metal Finishing Effluent Limitation Guidelines (40 CFR 433). See also Table 3.
E & MF = Source first had to meet the electroplating guidelines, then the metal finishing guidelines.
Note: Iron and steel mills that have electroplating operations were exempted from the electroplating
guidelines but must meet the requirements of the metal finishing guidelines.
-------
Existing Direct Dischargers Table 3.
Under the provisions of the Clean
Water Act, every facility discharging
into a waterway must apply for an
NPDES permit which specifies what
pollutants may be discharged and a
schedule for compliance, monitoring
and reporting. The acceptable levels
of pollutants in the effluent are based
on a series of effluent guidelines
published by EPA for specific
industries.
In specific cases, if these regulatory
guidelines do not control a particular
pollutant, the permit issuer may still
limit that pollutant on a case-by-case
basis. The guidelines do not restrict
the power of any permit-issuing
authority from imposing more
comprehensive or more stringent
requirements, as long as they
conform with the purposes of the
Clean Water Act. Indeed, if state
water quality standards or other
provisions of state or Federal law
require more stringent pollutant
limits, the permit-issuing authority
must apply those limitations. The
authority may also insert different
but equivalent units in a permit; for
example, pounds per day instead of
milligrams per liter.
While many industries have
increasing levels of stringency for
the BPT and BAT standards, there is
only one set of limitations in the
metal finishing regulations, i.e., the
level of stringency for BPT and BAT
are the same. The effluent guidelines
for existing direct dischargers are
listed in Table 3. These limitations
had a compliance deadline of June
30,1984.
Effluent Limitations for Existing Direct Dischargers, Existing Indirect Dischargers
with Metal Finishing Facilities, and New Sources
Effluent Limitation (mg/l except for pH)
Direct
Dischargers
Cadmium
Existing Sources
New Sources
Chromium
Copper
Lead
Nickel
Silver
Zinc
Cyanide0
Total
Amenable6
Total toxic
organics
pH
Total suspended
solids
Oil and grease
Maximum
Daily
0.69
0.11
2.77
3.36
0.69
3.98
0.43
2.61
1.20
0.86
2.13
6.0-9.0
60
52
Monthly
Average
0.26
0.07
1.71
2.07
0.43
2.38
0.24
1.48
0.65
0.32
6.0-9.0
31
26
Indirect
Dischargers:
Metal Finishing
Facilities
Maximum
Daily
0.69
0.11
2.77
3.36
0.69
3.98
0.43
2.61
1.20
0.86
2.13
6:0-9.0
60
52
Monthly
Average
. 0.26
0.07
1.71
2.07
0.43
2.38
0.24 '
1.48
0.65
0.32
6.0-9.0
31
26
"Self-monitoring for cyanide must be conducted after cyanide treatment and before dilution with other
streams. Alternatively, samples may be taken of the final effluent if the plant limitations are adjusted
based on the dilution ratio of the cyanide waste stream flow to the effluent flow (40 CFR Part
433.12(c)).
^Cyanide amenable to chlorination may be substituted for total cyanide with agreement of control
authority.
SOURCE: 40 CFR Part 433.
-------
Iron-packed drum (blue) for treating chelated effluent.
EPA and the state have the right to
visit any manufacturing site and
examine permit-related records,
check sampling and monitoring
equipment, and sample wastewater
or treated effluent. This information
becomes a matter of public record
unless trade secrets or proprietary
Information would be revealed in the
process. In these cases, provisions
are made to allow access only by
regulatory officials. (By law,
however, effluent data cannot be
considered proprietary.) The law
further states that any responsible
corporate officer who willfully or
negligently violates any permit
condition can be punished by a fine
up to $25,000, by imprisonment for
not more than six months, or by
both.
Existing Indirect Dischargers
A POTW is essentially designed to
treat domestic sewage. Many
industrial wastes are also compatible
with the treatment system in that the
POTW can treat and discharge these
industrial wastes and still satisfy its
NPDES permit. However, many other
industrial wastes either pass through
the POTW untreated or interfere with
the POTW's normal operation. In
either case,|the POTW may then be
in violation of its permit or be unable
to recycle or dispose of its sludge.
Pretreatment regulations permit
industry continuing access to a
central wastewater treatment system
while at the same time protecting the
quality of the receiving waterbody,
protecting the operations of the
POTW, and preventing POTW sludge
recycle or disposal problems. EPA
has developed these regulations
along two lines:
• General pretreatment regulations,
which delineate responsibilities of
EPA, states, POTWs and industrial
dischargers
• Industry-specific pretreatment
regulations which set limits on the
concentration or loading of the
effluent discharged to the POTW.
The general pretreatment
regulations are found in 40 CFR 403.
Specific pretreatment regulations
affecting electroplaters,are found in
40 CFR 413 for existing job shop and
IPCBM nonintegrated facilities, and
in 40 CFR 433 for all metal finishing
facilities and for electroplating
operations other than job shops and
IPCBMs. [
The effluent limitations for existing
metal finishing facilities are
presented in Table 3; in nearly all
respects, they are identical to those
for direct dischargers.
The effluent limitations for job shop
and IPCBM facilities are more com-
plex. They depend on the types of
operations employed at the facility
and may be either concentration
based or mass-based performance
levels. The operations covered are
listed as subparts of 40 CFR 413 and
are presented in Table 4. The effluent
limitations, or pretreatment stan-
dards, governing these operations
are presented in Table 5.
-------
Table 4.
Applicable Subparts for Existing Indirect IMonintegrated Sources
Code of Federal Regulations, Title 40, Part 413, Subpart:
A—Electroplating of common metals (Al, Cd, Cu, Cr, Fe, Ni, Pb, Sn, Zn, and any combination)
B—Electroplating of precious metals (Ag, Au, In, Pt, and Rh)
C—(Reserved)
D—Anodizing
E—Coating (chromating, phosphating, immersion plating)
F—Chemical etching and milling
G—Electroless plating
H—Printed circuit board manufacturing
Note: Each of the operations listed may also involve stripping, coloring, phosphating, acid cleaning and
alkaline cleaning.
SOURCE: 40 CFR 413.
Table 5.
Pretreatment Standards for Existing Dischargers with Indirect Nonintegrated Facilities
Effluent Limits (mg/l except as noted)
Basic Standard
Concentration-Based
4-day
Daily Average
Alternative 1 Mass-Based
Subparts A-G
Daily
4-day
Average
Subpart Ha
Daily
4-day
Average
Alternative 2b
Concentration-Based
4-day
Daily Average
Plants discharging < 10,000 gal/day
Cadmium 1.2 0.7
Cyanide (amenable) 5.0 2.7
Lead 0.6 0.4
Total toxic organics 4.57 —
Plants discharging a 10,000 gal/day
Cadmium
Chromium
Copper
Lead
Nickel
Silver0
Zinc
Total metals
Cyanide (total)
Total toxic organics
pH
Total suspended solids
1.2
7.0
4.5
0.6
4.1
1.2
4.2
10.5
1.9
2.13
0.7
4.0
2.7
0.4
2.6
0.7
2.6
6.8
1.0
—
—
—
47"
273d
176"
23"
160"
47"
164"
410"
74"
2.13
29"
156"
105"
16"
100"
29"
102"
267"
39"
—
—
—
107"
623d
401d
53"
365"
374"
935"
169"
2.13
65"
357d
241 1
36"
229"
232"
609"
89"
—
—
—
1.2
•
—
0.6
—
—
1.9
2.13
7.5-10.0
20.0
0.7
—
0.4
—
—
1.0
—
7.5-10.0
13.4
'Subpart H, printed circuit board manufacturing.
6Can only be used in the absence of strong chelating agents, after reducing of hexavalent chromium wastes, and after neutralization using calcium oxide (or
hydroxide).
"Applies only to Subpart B, electroplating of precious metals.
^Expressed in units of mg per m2 processed per operation. An operation is any metal finishing step that is followed by a rinsing step.
SOURCE: 40 CFR 413.
-------
As shown in Table 5, facilities
discharging less than 10,000 gal/d
are subject to more lenient standards
than larger facilities. For large
facilities, two alternatives are
available for complying with the
basic standards (subject to approval
by the POTW). The first alternative,
referred to as the mass-based
standard, restricts only the mass of
pollutants discharged without regard
to their actual concentration in the
effluent. The mass of pollutants
allowed in the discharge is a function
of the quantity of work processed (in
terms of m2 of surface area) and the
number of plating operations
performed (a plating operation is
defined as any step in metal finishing
that is followed by a rinse). This
option may appeal to facilities
where, for instance, closed-loop
recovery systems have been
installed and the effluent volume is
quite low but rather concentrated.
The second alternative, referred to as
the concentration-based alternative
standard, restricts the concentration
of a smaller number of pollutants
than is covered in the basic standard.
This standard replaces the limits
on the levels of copper, nickel,
chromium, zinc, and total metals in
the basic standard with limits on
pH and total suspended solids.
This option is only available for
nonchelated effluents which have
been neutralized with Ca(OH)2 and
where all hexavalent chromium has
been reduced.
Table 6 shows the compliance dates
for all existing indirect dischargers.
The dates are differentiated between
metals andfcyanide, and total toxic
organics; they are further
differentiated between captive and
job shops ajnd between integrated
and nonintegrated facilities.
Removal Allowances. Indirect
dischargers may be exempt from
certain pretreatment requirements
through a removal allowance (also
referred to !as a "credit allowance").
The removal allowance program
provides that, under conditions
specified below, a POTW may revise
a plant's discharge limits for a
pollutant if |it can be shown that the
POTW itself is removing the
pollutant in question. The removal
allowance must be applied for by the
plant from the municipality, which in
turn must receive EPA approval for
the allowance.
The application for a removal
allowance requires a demonstration
by the POTW, through actual data,
that the pollutant is being removed
by the POTW. (The municipality may
charge the electroplater for the cost
of the demonstration.) The
concentration limit for the
electroplater would be revised by:
Y =
1-r
where:
Y — revised discharge concentration
x = concentration (or
mg/m2/operation) required by
specific standards for
electroplaters
r = demonstrated fraction removed
by the POTW.
For example, if the data show that
the POTW removes 60 percent of a
specific pollutant (by EPA-specified
sampling methods), a pollutant with
an initial pretreatment concentration
requirement of 2 mg/l would be
revised to:
= 5 mg/1
1 -0.6
10
-------
Table 6.
Compliance Schedule for All Existing Indirect Sources
Compliance Deadline
Captive Operation
Job Shop
Nonintegrated
Facility
Integrated
Facility
Nonintegrated
Facility
Integrated
Facility
Metals and Cyanide:
Electroplating (see Table 5)
Metal Finishing (see Table 3)
Total Toxic Organics:
Interim (4.57 mg/l)a
Final (2.13 mg/l)a
April 27,1984
Feb. 15, 1986
June 30, 1984
Feb. 15,1986
June 30, 1984
Feb. 15, 1986
June 30, 1984
Feb. 15,1986
April 27, 1984
NA
July 15, 1986
July 15,1986"
June 30, 1984
NA
July 15, 1986
July 15, 1986"
NA = not applicable
"Basis for 4.57 mg/l is good housekeeping practices; basis for 2.13 mg/l is good housekeeping practices plus control equipment.
"Job shops discharging < 10,000 gal/d have only to comply with the 4.57 mg/l standard for Total Toxic Organics. Job shops discharging > 10 000 qal/d must
comply with 2.13 mg/I standard for Total Toxic Organics. '
The demonstration of pollutant
removal fractions requires the
municipality's cooperation. For
example, EPA specifies that the
influent and effluent data taken at the
municipal treatment system shall be
derived from a minimum of 12
samples taken at approximately
equal intervals throughout the year.
Average concentrations must be
measured in the influent and the
effluent samples in order to derive
consistent removal capabilities of
the municipal system. When
sampling is for pollutants such as
cyanide that cannot be held for long
periods before analysis, grab
samples can be used.
Certain conditions must be met
before a municipality can provide the
removal allowance to its industrial
users. Of major importance, the
removal allowance must not cause
the municipality to violate its NPDES
limit, and the disposal of the
municipal sludge must not be
impaired.
New Sources
It is important to note that all new
facilities (in both electroplating and
metal finishing) are subject to the
same new source performance
standards (NSPS or PSNS)
regardless of size, type of facility (job
shop or captive, integrated or
nonintegrated), or type of discharger
(direct or indirect). Table 3 presents
the concentration limits which apply
to all new sources in the
electroplating and metal finishing
industries. The only difference
between the standards for new
sources and the standards for the
existing dischargers included in the
table is in the cadmium limitation
(the new source standard is more
stringent). The difference between
the new source standards and those
for existing indirect job shop and
IPCBM sources is that the new
source standards are nearly always
more stringent, as can be seen by
comparing Tables 3 and 5. It should
also be noted that, for new sources,
there is no difference in the
standards between large and small
facilities.
11
-------
3. Water Pollution
Control
Technologies
The costs of complying with
pollution control legislation and the
increasing costs of raw materials,
water and wastewater treatment
have drivenielectroplaters to seek
ways to reduce their costs of
operation. Experience has shown
that the two cost factors most
responsive to improvements are
related to the volume of water used
and discharged and the amount of
plating chemicals which end up in
the waste treatment system. When
plating chemicals are conserved in
the process [stream, for example, less
chemicals must be replaced in the
plating bath, removed from the
wastewater before discharge, and
disposed of1 in residues. Similar
benefits are realized when the
volume of process water is reduced:
less water needs to be replaced or
treated, and, when wastewater is
finally discharged to a public sewer
system, the cost of treatment is
reduced.
i
Today's eleptroplater has a number
of options for cost-effectively
bringing a facility into compliance
with water pollution control
regulations. Within the three general
options — modifying the process,
treating the wastewater, and
becoming a direct discharger —
there is a wide variety of possible
modifications and treatment
technologies to choose from.
The selection and design of a control
system entails the following general
tasks:
• Performing a field investigation to
define current and achievable
waste stream parameters (flow
rate, pollutant types and
concentrations, wastewater
variability)
• Developing conceptual models of
proposed treatment processes
based on data obtained in the field
investigation
• Conducting bench-scale
treatability studies on wastewater
samples to simulate the proposed
treatment processes
• Evaluating the results of these
studies to assess the ability of the
proposed system to meet
discharge requirements
• Using the results of this assess-
ment to develop optimal design
parameters for the full-size system
• Estimating the capital and
operating costs of the proposed
system, based on the operating
parameters needed for adequate
pollutant reduction and on vendor
quotations for the equipment
specified.
Choosing among the different
options also requires a careful cost
and benefit analysis considering:
• The reliability of the systems to
consistently reduce the pollutants
to the levels specified in the
discharge permit or in other
regulations
• The investment cost of the
systems
• The operating costs of the
systems, including labor, utilities,
wastewater treatment chemicals,
and sludge disposal
• The savings in raw materials and
sewer charges as a result of
reduced water flow and the reuse
or recovery of plating chemicals.
12
-------
Process Modifications
Process modifications are designed
either to reduce water use (e.g., by
installing flow restrictors) or to
conserve plating chemicals (e.g., by
recycling or recovering the
chemicals).
There are a number of ways to
reduce water use, including:
• Implementing a rigorous
inspection program to discover
and quickly repair water leaks
• Installing antisiphon devices
equipped with self-closing valves
on water inlet lines
• Using multiple counterflow rinse
tanks to substantially reduce rinse
water volume
• Using spray rinses to reduce rinse
water volume
• Using conductivity cells or flow
restrictors to prevent unnecessary
dilution in the rinse tanks
• Reusing contaminated rinse water
and treated wastewater where
feasible
• Using dry cleanup where possible,
instead of flooding with water.
Modifications to minimize the loss of
plating chemicals, consequently
reducing pollutant loads, include:
• Implementing a rigorous
inspection and housekeeping
program to locate and repair leaks
in process baths and to replace
faulty insulation on plating racks
(thereby reducing drag-out), and
installing drip trays
• Using spray rinses or air knives to
minimize drag-out from plating
baths
• Using air agitation or workpiece
agitation to improve plating
efficiency
• Recycling rinse water to the
plating bath to compensate for
surface evaporation losses
Using spent process solutions as
wastewater treatment reagents
(e.g., using spent acid and alkaline
cleaning baths as reagents in a
neutralization tank)
Using minimum concentrations of
chemicals in plating baths
Using plating bath purification to
control the level of impurities and
prolong the service life of the bath
Installing recovery systems to
reclaim plating chemicals from
rinse waters and recycle them to
the plating bath.
Rear view of lamella plate clarifier.
13
-------
A closed-loop recovery system may
be appropriate for wastes that are
difficult or expensive to treat. In the
case of rinse streams requiring
treatment other than neutralization
and clarification (containing cyanide
or chromium, for example) or rinse
streams containing pollutants that
are not effectively removed by
conventional treatment (such as
certain chelated metal complexes),
installing a closed-loop system to
recycle the rinse may reduce the
water pollution control costs. A
small-volume purge stream from the
closed-loop recovery system will
require treatment, but this should
not be a major expense.
Recovery systems have been
evaluated under EPA research
projects. Reports of this research are
available and are listed in the
reference section. They include the
following topics:
General6"9
Evaporation12*17
Reverse osmosis20-22-25-26-28
Electrodialysis14-19
Electrolytic Recovery15
Ion Exchange.10-11
Conducting a cost analysis of each of
the options is important in selecting
the most appropriate process
modifications for an operation. In
such an analysis the capital and
operating costs of the modifications
are weighed against the total of the
benefits from reductions in raw
material losses, wastewater
treatment capacity and chemicals,
and sludge disposal fees. Case
History 1 (in Chapter 4) highlights the
significance of a thorough analysis. If
the evaporatbr installation were only
justified by the value of the
chromium recovered, the investment
would yield a significant loss.
However whbn reductions in
wastewater treatment costs were
included, a net profit results, yielding
a 22 percent return on investment.
I
Wastewater Treatment
Once the water stream has left the
process, it must be treated before
being discharged. Several treatment
choices are available to the plater,
and proper selection and design of
the system will ensure that current
discharge requirements can be met.
The wastewater treatment system
typically consists of the processes
listed below and illustrated in
Figure 1:
• Wastewater collection: Waste
streams from chrome-plating and
cyanide baths are isolated and
directed to the appropriate waste
treatment 'unit. Effluents from
these units are then combined in
an averaging tank with other
wastewaters such as those from
acid/alkalrbaths and rinses, other
plating baths and rinses, and
chemical dumps. They are then
sent to the neutralization tank.
• Chromium reduction (as needed):
Hexavaleht chromium is
converted (reduced) to the
trivalent state, which is then
precipitated as chromium
hydroxide by alkali neutralization.
A substitute process for chromium
reduction iis electrochemical
reduction.
• Cyanide oxidation (as needed):
Toxic cyanide-bearing waste
streams are oxidized by
chlorination or ozonation, forming
less harmful carbon and nitrogen
compounds.
• Neutralization/precipitation: The
combined waste streams are
treated with acid or alkali to adjust
the pH to acceptable discharge
limits and to precipitate the
dissolved heavy metals as metal
hydroxides.
• Clarification: The neutralized
waste stream is treated with
coagulants and flocculants to
promote the precipitation and
settling of the metal hydroxide
sludge, which is separated from
the clarified liquid.
• Sludge handling: The collected
hydroxide sludge is gravity-
thickened, mechanically
dewatered, and sent to an
approved hazardous waste
disposal site.
While these processes effectively
treat most electroplating waste
streams, they may not be suitable for
all applications. Furthermore, there
is no guarantee that the "normal"
design parameters (such as retention
time and reagent dosage) will
effectively remove the pollutants
from every electroplating
wastewater discharge. Treatability
studies are often needed to verify the
applicability of a treatment process
to a specific wastewater.
14
-------
Cyanide waste
Caustic
CI2 |
1-
V "
A
•£ *
-------
Several alternative treatment
processes have been developed to
overcome the problems encountered
in conventional treatment. Attention
has largely focused on a problem
frequently encountered in the
neutralization/precipitation step in
which the solubility of dissolved
metals cannot be brought to the low
levels required for discharge. The
problem arises when plating
wastewaters contain substances,
known as chelating agents, which
react with dissolved metals and
interfere with their precipitation as
metal hydroxides. Such chelating
agents as ammonia, phosphates,
tartrates, and EDTA*are commonly
used in plating operations and
consequently find their way into the
wastewater. Chelating agents react
with the dissolved metal ion to form
a "chelate complex" that is usually
quite soluble in neutral or slightly
alkaline solutions.
Two methods of overcoming the
solubilizing effects of chelating
agents are:
• Precipitating the metal from
solution by a method that, unlike
hydroxide precipitation, is
relatively immune to chelating
effects
• Pretreating the wastewater to free
the metal ion from the chelating
agents.
*Ethylene diamine tetra-acetic acid
The first category includes such
processes as sulfide precipitation,
ion exchange, and water-insoluble
starch xanthate (ISX) precipitation.
Sulfide precipitation, which
precipitates fnetals as su If ides
instead of hydroxides, has been
found capable of achieving low
levels of metal solubility in highly
chelated waste streams. The process
has been proven as an alternative to
hydroxide precipitation or as a
method for further reducing the
dissolved metal concentration in the
effluent frorr^ a hydroxide
precipitation system (see Case
History 5). :
In ion exchange, a resin which has a
strong affinity for heavy metal ions
(as opposed^o the calcium and
sodium ions normally present in the
wastewater}, is used as a means of
filtering heavy metal ions out of
solution, lori exchange has been
proven to be a cost-effective means
of lowering |the metal concentration
in electroplating discharges (see
Case History 6).
ISX precipitation can remove heavy
metal cations from wastewaters. The
ISX acts as an ion exchange material,
replacing sodium or magnesium
ions on the )SX surface with heavy
metal ions i|i the solution. It is
currently used both as an alternative
to hydroxide precipitation and to
"polish" treated wastewater (i.e., to
lower the residual metal
concentration). Because ISX is
insoluble in:water and its
precipitation reaction rate is rapid, it
is used either as a slurry with the
stream to bfe treated or as a precoat
on a filter through which the waste
stream is passed.
If the problems associated with
chelating agents are not resolved by
precipitation, the waste stream is
usually segregated and pretreated
either by raising the pH to a highly
alkaline level (high pH lime
treatment) or by lowering it to a very
acidic level. At these extreme pH
conditions, the metal complex often
dissociates, freeing the metal ion. A
suitable cation (such as calcium) is
then used to tie up the chelating
agent, preventing it from
recombining with the metal ion
when the solution is neutralized.
While this type of treatment requires
a high dosage of reagents, it has
proved to be an effective means of
treating many wastewaters
containing chelating agents.
Another frequent problem in
wastewater treatment is metals
concentrations in the effluent which
exceed the discharge requirement
even though the total amount of
dissolved metals in the effluent is
quite low. This condition indicates
precipitated (undissolved) metals in
the effluent, a condition which
results from an overloaded clarifier,
ineffective conditioning (coagulation
orflocculation), or poor pH control.
The problem can be resolved by
correcting the process deficiency or
by using a solids removal (polishing)
device, such as a sand or mixed-
media filter, to clean the clarifier
overflow.
16
-------
EPA and the Department of Defense
have funded research to assess the
cost and effectiveness of many
wastewater treatment techniques,
the results of which are reported in
the following publications:
• General6'9'13'15'23'24
• Sulfide precipitation29
• Ion exchange10'11
• Cyanide waste treatment18-27
Becoming a Direct Discharger
Satisfying the pretreatment
requirements for discharging to
a POTW can often produce an
effluent that will also satisfy the
requirements for the direct discharge
to waterways. Where a suitable
receiving waterbody is available,
sewer fees can be completely
avoided by becoming a direct
discharger. Even though the
sampling and reporting require-
ments are more stringent for a
direct discharger, this could be an
important alternative in those
situations where a POTW uses
advanced wastewater treatment
processes, which have significantly
increased sewer charges to
industrial firms using the public
system.
Figure 2 presents the annual sewer
fees levied against a firm as a
function of its discharge rate; it
includes a range of typical rates per
gallon discharged.
20
15
10
Legend:
Sewer Fees
A $2.00/1,000 gal
$1.00/1,000 gal
B
C $0.50/1,000 gal
0 600 1,200 1,800
DISCHARGE RATE (gal/h)
Note:
Based on operating time of 3,000 h/yr.
2,400
3,000
Figure 2. Annual Sewer Costs as a Function of Flow Rates
17
-------
4. Water Pollution
Control Case
Histories
The case histories presented in this
chapter illustrate a few of the
solutions to wastewater and solid
waste management problems faced
by the electroplating industry. They
do not address the gamut of the
industry's problems; rather, these
discussions demonstrate the
analysis and innovation required to
develop optimal solutions to these
problems.
Case History 1.
Evaporator Installation
The Phillips Plating Company,
Phillips, Wisconsin installed a rising
film evaporator to concentrate the
chromium plating bath drag-out in
the rinse stream so that it could be
recycled to the plating bath.
Installation of the 75 gal/h (280 l/h)
closed-loop recovery system
reduced the: need for replacing
anhydrous chromic acid (CrOa) to the
plating solution by approximately 4
lb/h(1.8kg/h).
The total cost to install the recovery
system in 1979 was approximately
$60,000. Table 7 shows the annual
costs and savings realized by
installing and operating the unit. If
the savings in plating chemicals
alone are considered, the investment
would have a net cost of
approximately $9,000/yr. However, if
the analysis also includes savings in
treatment chemicals (Phillips uses a
Sulfex™ insoluble sulfide treatment
system) and in solid waste disposal
charges (based on disposal at 25
percent solids by weight at a cost of
$0.19/gal of sludge), totaling
$28,400/yr, there would be a net
savings before taxes of nearly
$20,000/yr and the system would pay
for itself in just under four years.
Table 7.
Economic Evaluation of Evaporator Installation3
Cost
INSTALLED COST for 75-ga!/h evaporator ($)
60,000
ANNUAL COSTS at 6,000 h/yr ($/yr):
Depreciation (10-yr life)
Taxes and insurance
Maintenance:
Labor (%h/sHift at $6/h)
Utilities: |
Steam (at $3.50/10s Btu)
Electricity [
General plant overhead
Total annual cost
6,000
600
3,600
2,250
16,000
600
2,600
30,650
ANNUAL SAVINGS (S/yr):
Replacement Cr03
Waste treatment reagents
Sludge disposal
Total annual savings
21,600
23,000 :
5,400
50,000
19,350
10,060
Net savings before tax ($/yr)
Net savings after tax, 48% tax rate ($/yr)
Payback after tax (yr) 3-8
Payback if investment tax credit and accelerated depreciation are used (yr) 2.6
i
"These figures reflect 1979 conditions.
18
-------
The payback period can be reduced
even further by taking advantage of
the investment tax credit and
accelerated depreciation allowances.
As shown in Table 7, the investment
payback was reduced to under three
years, a most acceptable investment
rate of return. The Phillips Plating
case highlights the need to consider
all of these factors in evaluating
chemical recovery modifications.
Note that although this case history
is based on 1979 conditions, before
significant changes to tax laws were
made, a present day analysis of a
similar case would yield similar
results for costs and payback period.
In addition to the evaporator
installation, considerable cost
savings were achieved in the Phillips
plant with relatively minor
engineering refinements. Philips
used a closed-loop system of the
kind shown in Figure 3a. In this case,
the rinse rate, which equals the
evaporative loss, is the critical
design parameter. In order to ensure
adequate rinsing in the final rinse
tank, the flow through the closed-
loop system may have to be quite
high. If Phillips were to use a closed-
loop recovery system in the first two
rinse tanks with a running rinse in
the final rinse tank (Figure 3b),
adequate rinsing would be assured
and the plant could still achieve
significant drag-out recovery. This
approach would significantly reduce
the steam costs associated with
evaporation and also would require
a smaller, less expensive evaporator.
Figure 4 illustrates the annual costs
and savings for open-loop
evaporator systems at different
evaporator feed rates.
Workpiece
Concentrate
(a) Closed Lo<
Workpiece
Concentrate
>P
F
1
181
Bating
1
"7 1
jmr
li r
US
|j h
T J
3ath i Rinse tanks
1 Distillate
f
Evaporator
r
1
lit
lating b
(b) Open Loop
1
r
Cooling
towers
i — i r
I _L ,1,
% 1
1 J
ath I Rinse tanks
t
Evaporate
Distilla
*"~ Cooling
_ towers
— i i — *"
Rinse
*~ .r -. . * / water
: '• _• + '/ '
Running
rinse
16 1— ^~~ To waste
treatment
Figure 3. Evaporative Recovery Systems
50
40
8 30
O
o:
o
CD
20
10
Net saving
Legend:
A annual costs (capital plus
operating costs)
B gross annual savings from
resource recovery and reduced
pollution control costs
I
Note:
Costs and savings reflect 1979 prices.
25 50
EVAPORATOR FEED RATES (gal/h)
75
Figure 4. Annual Costs and Savings as a Function of Evaporator Systems
19
-------
Case History 2.
Automated Drag-out
Recovery
The Gillette Company Safety Razor
Division, Boston, installed an
automated drag-out recovery system
that recovered 85 percent of the
nickel drag-out from three plating
tanks. The system (Figure 5) uses
four countercurrent rinse tanks to
provide both rinsing of the
workpiece and a source of solution
makeup for the plating tanks. The
drag-out recovery system allows
closed-loop operation of the nickel
plating bath; all rinse water is
recycled to the plating bath with no
flows to waste treatment. Level
control probes in the three plating
tanks control the addition of rinse
water collected from the most highly
concentrated rinse tank to make up
for surface evaporation losses from
each of the plating tanks. A level
control in the concentrated rinse
sump controls the addition of
makeup water in the final rinse tank.
To minimize the buildup of
impurities in the system, the makeup
water is deionized by a reverse
osmosis water purification unit.
Three factors determine the
percentage o[f drag-out that can be
recovered when this approach is
used:
• The surface evaporation rate from
the plating tank, which determines
the amount of rinse water that can
be recycled
• The ratio of the drag-out volume
to the volume of rinse water
recycled to the plating bath
• The number of countercurrent
rinse tanks used for recovery.
i
Figure 6 shows the percentage of
drag-out that can be reclaimed in
terms of these factors.
The system installed at Gillette
included the reverse osmosis unit,
three chemical transfer pumps, the
concentrated rinse sump (operating
on the U-tube principle), a control
panel, and the necessary control
loops. The total investment cost in
1979 was $8,500.
Makeup water
(deionized) ,
Workpiece
i__il
Li
1 '
1 t '
| 0 1
I 1
1 '
1 61
i i
Plating A tanks
Chemical feed pumps
LC - level control
Concentrated
"ise sump
Rgure 5. Automated Drag-Out Recovery System
20
-------
o
-------
Case History 3.
Electrochemical Recovery
Allied Metal Finishing, Baltimore, is a
job shop involved mostly with zinc,
nickel and cadmium plating. Faced
with effluent discharge standards, a
wastewater reduction program was
initiated to reduce treatment needs
and minimize sludge production.
The first step of the program was a
reduction in water use from 127,000
to 66,000 gal/d. Many of the water
reduction measures were simply
related to operating practices, such
as instructing operators to turn off
the main water valve during breaks
and other line stoppages. Others
involved the use of inexpensive
devices to reduce water flow
automatically. For example, one
effective method was to install timer
devices which turn the rinse water
flow on and off at 15 minute
Intervals; this cutwater usage in half
without diminishing the quality of
the rinse water.
Next, an electrochemical reactor was
installed to recover cadmium. This
unit makes use of a carbon fiber
cathode, whi£h has an enormous
ratio of surface area to volume —
approximately 1,000 times greater
than other types of cathodes. Rinse
water containing cadmium is passed
over the cathode, plating the metal
on the cathode. The metal is
removed from the cathode by
reversing the current or rinsing the
cathode with a stripping solution
which is returned to the plating bath.
The reactor is also capable of
electrolyticatly oxidizing cyanides at
a lower cost than that of the reagents
used in the conventional alkali-
chlorination process. This recovery
system reduces wastewater
treatment requirements and
minimizes sludge generation.
Figure 7 shows the system at Allied.
The solution from the process rinse
is pumped through a filter to remove
particulate matter and then through
the reactor, which houses the carbon
fiber cathode. The treated water is
returned to the rinse tank. The power
for the treatment unit is supplied by
a common rectifier.
Makeup water
Workpiece
To wastewater
treatment
Figure 7. Electrolytic Recovery System
22
-------
Case History 4.
Stream Segregation
In order to enhance its conventional
wastewater treatment system
performance, the Medford Plastics
Company, Medford, Wisconsin
segregated a waste that was
particularly difficult to treat and
demonstrated a cost-effective means
of treating that waste before
discharge. The plant, which plates
copper, nickel, and chromium on
plastic components, installed the
wastewater treatment system shown
in Figure 8.
During the treatability studies
conducted before a system was
selected, it became obvious that the
nickel concentration could not be
reduced in a common treatment
system to the level required by the
discharge permit. It was proposed to
segregate the electroless nickel
plating rinse flow from the rest of the
wastewater. A system was evaluated
in which nickel was precipitated at a
high pH and clarified independently
of the other wastewater flows. The
nickel rinse effluent was then
combined with the balance of the
wastewater before discharge.
Testing indicated that this approach
should provide a total effluent nickel
concentration below the permit
specifications.
Table 8 indicates that the treated
discharge achieves the removal
levels called for in the discharge
permit, levels which are much lower
than national new source
performance standards. When the
system was first installed, however,
the discharge consistently exceeded
the nickel level requirement. To
correct this problem, the plant cut
the flow to the nickel treatment
system in half by further rinse water
recycling. The wastewater flow
reduction created increased
retention time in the treatment
system which, when coupled with
the dilution achieved from adding
the copper-chrome wastewater,
eliminated the problem.
Copper/chrome wastes
(15gal/min)
Nickel waste
(5 gal/min)
Collection Chrome pH adjustment
tank reduction (pH = 8)
Collection pH adjustment
tank (pH = 11)
To wastewater
discharge
Segregated mixer/clarifier
Sludge to
filter press
Figure 8. Wastewater Treatment System with Segregated Treatment of Nickel
Table 8.
Effluent Quality After Segregation of Nickel Waste Stream
Effluent
Characteristic
Permit
Requirements"
Treated
Effluent0
Total suspended solids (Ib/d)
Chromium (Ib/d):
Total
Hexavalent
Nickel (ppm)
Copper (ppm)
pH
8.8
0.22
0.02
1.3
0.17
6.0-9.5
0.13
0.004
0.16
0.06
9.3
"Monthly average of daily values.
23
-------
Case History 5.
Sulfide Precipitation
Holly Carburetor, a Division of Colt
Industries, Paris, Tennessee has
demonstrated the feasibility of
reducing metal concentrations in
wastewaterto low levels using
sulfide precipitation instead of
hydroxide precipitation. Part of the
wastewaterfrom the plant results
from surface treatment of parts used
in the assembly of carburetors. This
waste stream contains varying
concentrations of iron, zinc, and
chromium (hexavalent and trivalent).
The sulfide precipitation system
marketed asSulfex™ was installed
as an EPA demonstration project
funded under a grant to the National
Association of Metal Finishers. The
Sulfex system precipitates metals as
sulfides instead of hydroxides and
because metal sulfides are
considerably less soluble than
hydroxides, lower metal
concentratiohs can be achieved in
the effluent. Table 9 compares the
effluent quality of the system with
the discharg0 limits required by the
local permitting authority. It shows
the system tp be effective in
removing the metals to the levels
required by the permit.
Figure 9 shows the components of a
treatment system using sulfide
precipitation. It should be noted that
most of the equipment components
of the sulfide system are common to
hydroxide systems. Consequently,
this processiOffers a low-cost means
of modifying an existing hydroxide
system to improve metal removal
capability- :
Two distinct sulfide precipitation
processes (insoluble and soluble) are
being used to treat wastewaters
containing heavy metals. The system
at Holly Carburetor is known as
insoluble sulfide precipitation (ISP),
in which ferrous sulfide is the sulfide
source. Ferrous sulfide is relatively
insoluble in water; consequently, the
level of dissolved sulfide in the
wastewater is kept to a minimum.
The main advantage of ISP over the
soluble sulfide approach is that there
is no detectable hydrogen sulfide
odor associated with the process.
Soluble sulfide precipitation (SSP)
uses a water-soluble reagent, such
as sodium hydrosulfide (NaHS) or
sodium sulfide (IMa2S).
Table 9.
Effluent Quality After Sulfide Precipitation
Concentrations (mg/l)
POTW Requirements
Treated Effluent
Zinc
Chromium
Hexavalent
Total
Copper
5.0
0.05
5.0
5.0
0.015
0.02
0.10
"Below detectable limits
24
-------
Legend:
FC = flow counter
pHA = low pH alarm
pHc = pH controller
RC = recycle control
1
- — — 1
\ £
' '
7^ 1
' K • o
=Q=\
Two-stage neutralizer
^—I
•" V.*
#fe
Sand
filter
Wlixer/clarifier
Figure 9. Wastewater Treatment System with Sulfide Precipitation
Chromium wastewater surge tank (left) and cyanide wastewater surge tank
with retaining wall (background).
25
-------
Case History 6.
Ion Exchange for Heavy
Metal Removal
The Hurd Lock and Manufacturing
Company, Greensville, Tennessee
uses an unusual wastewater
treatment system combining batch
and continuous operations. Four
waste streams are collected in four
separate sumps. Each stream is then
processed separately through the
single continuous treatment system
shown in Figure 10. The continuous
treatment for each batch uses the
following steps:
• Chromium reduction (as
appropriate)
« Neutralization (pH is adjusted to
achieve maximum metal removal
for each waste processed)
• Flocculation (with polymer
addition)
• Pressure filtration (with
diatomaceoiis earth precoat)
• Ion exchange polishing.
The ion exchange unit is used to
reduce the concentration of metals in
the effluent to the required level.
Table 10 presents the permit
requirements and a typical set of
concentrations found in the effluent,
indicating that all metal
requirements are met. The plant was
allowed to exceed the chemical
oxygen demand (COD) discharge
level because this pollutant could be
effectively reduced by subsequent
POTW treatment
The resin used in the ion exchange
columns selectively removes heavy
metals from the waste, but allows
alkali and alkaline earth cations to
pass through. A two-stage ion
exchange unit in which the first stage
uses a hydrogen ion resin and the
second stage uses a sodium ion
resin was shown to be the optimal
treatment for this waste. Because the
resin proved more selective for
heavy metals in the presence of
calcium ions, the plant shifted from
caustic soda to lime for
neutralization.
Collection sumps
Chromium reduction Neutralization Flocculation
Precoat return
To wastewater
discharge
Mixing tank
Sludge to
approved disposal
Rgure 10. Combination Batch and Continuous Treatment System
26
-------
Table 10.
Effluent Quality After Ion Exchange
Typical Effluent Concentration
Pollutant (mg/l):
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Zinc
Total suspended solids
COD
pH
Color units
Permit
Requirements
0.01
0.05
0.05
0.50
0.05
0.10
0.10
15
20
6.5-8.5
12
Chrome
Floor
<0.005
<0.02
<0.05
<0.05
<0.05
<0.05
<0.02
<1.0
928
11.0
0
Chrome
Rinses
<0.005
<0.02
<0.05
<0.05
<0.05
<0.05
<0.02
<1.0
210
11.0
0
Nickel
Rinses
<0.005
<0.02
<0.05
<0.05
<0.05
<0.05
<0.02
<1.0
217
6.9
0
Zinc
Pit
<0.005
<0.02
<0.05
<0.05
<0.05
<0.05
<0.02
<1.0
500
11.6
0
Compact 40 gal/h single-stage cyanide oxidation unit (blue) with neutralization/flocculation units (red).
27
-------
5. Hazardous Waste
Regulations and
Management
The treatment of electroplating
wastewater as required by the
national pretreatment standards or
NPDES requirements will result in
two streams:
• An effluenj: that must comply with
regulations for acceptable
pollutant discharge
• A residue (sludge) containing a
high concentration of the
substances which the wastewater
regulations prohibit discharging.
Because electroplating wastewater
treatment systems commonly
remove regulated heavy metals,
most electroplating sludges contain
high concentrations of toxic heavy
metals and are therefore considered
hazardous. Hazardous waste
regulations promulgated in recent
years have drastically altered the
manner in which these materials are
stored, treated, and disposed of. This
chapter outlines these regulations
and discusses the most cost-
effective me&ns by which
electroplaters can bring their
operations ihto compliance with
them. i
Hazardous Waste Regulations
EPA regulates the management and
control of all hazardous wastes from
their point of origin to final disposal.
These regulations are the direct
result of two congressional
mandates on hazardous waste
practices embodied in the 1976
Resource Conservation and -
Recovery Act (RCRA) (PL 94-580) and
the 1984 Hazardous and Solid Waste
Amendments to RCRA (PL 98-616).
Air and water pollution regulations
vary from one industry to the next.
However under RCRA the same rules
apply to all firms that generate,
store, transport, or dispose of
hazardous waste. Most electroplat-
ing facilities will be considered
generators of hazardous waste and
some may be considered storage or
disposal facilities. The procedures to
determine whether certain wastes
are hazardous and the requirements
for those who generate, store, and
dispose of hazardous wastes are
described below.
Identification of Hazardous Wastes.
Solid wastes include all substances
destined for disposal and not already
regulated by the Clean Water Act or
the Atomic Energy Act of 1954.
Under regulations promulgated in
May 1980,2 EPA specified criteria for
four properties, any one of which
characterizes a waste as hazardous:
Ignitability is determined by
measuring the flash point of a
substance. The flash point is the
lowest temperature at which a
substance gives off flammable
vapors which, in contact with a spark
or flame, will ignite. Substances with
a flash point of 60°C (140°F) or lower
are considered ignitable.
28
-------
Corrosivity refers to the capacity of a
waste to extract or solubilize toxic
contaminants from other wastes. A
waste is considered corrosive if it
has a pH below 2 or above 12.5, or if
it corrodes steel (following a test
developed by the National
Association of Corrosion Engineers).
Reactivity refers to the tendency of a
waste to explode, autopolymerize,
create a vigorous reaction with air or
water, or exhibit thermal instability
with regard to shock or to the
generation of toxic gases.
Toxicity refers to the release,
through improper disposal, of toxic
materials in sufficient amounts to
pose a substantial hazard to human
health or to the environment.
Toxicity is perhaps the most
important characteristic to
electroplaters. In EPA's toxicity test
(called the Extraction Procedure [EP]
Toxicity Test), soluble materials are
extracted from the waste at a pH of 5
over a 24-hour period. If the test
extract exceeds established limits for
certain contaminants, the waste is
considered toxic and therefore
hazardous. Among the 14
contaminants currently specified in
the EP Toxicity Test, eight are
metals, several of which are
commonly used in electroplating.
Table 11 lists these metals with the
current limit for each.
In addition, the regulation deems
certain wastes hazardous unless
proved otherwise. These include:
• Wastewater treatment sludges
(toxic)
• Spent plating bath solutions
(reactive and toxic)
• Sludges from the bottom of
plating baths (reactive and toxic)
• Spent stripping and cleaning bath
solutions (reactive and toxic).
Requirements for Hazardous Waste
Generators. Producers of hazardous
waste (called generators) are
ultimately responsible for the
proper identification, storage,
transportation, and disposal of the
waste (see Figure 11). The generator
first determines whether the waste is
hazardous according to the criteria
outlined above though, alternatively,
the generator may simply declare
the waste hazardous and treat it
accordingly. If the waste is known to
be nonhazardous, the generator
need not test it. The responsibility for
the accuracy of the determination of
whether the waste is hazardous or
not lies with the generator.
Generators of hazardous wastes are
also responsible for notifying EPA
and maintaining records of their
activities, using appropriate
containers, labeling the containers,
and ensuring proper disposal. The
law requires most generators of
hazardous waste to use a
manifest system to ensure the
proper transport and disposal of the
wastes. The manifest system records
the movement of hazardous wastes
from the generator's premises to an
authorized off-site treatment,
storage, or disposal facility. The
manifest, signed by the generator,
transporter, and disposer, is an
official record confirming that all
Department of Transportation (DOT)
and EPA requirements have been
met. The generator must maintain
original manifests for three years,
and must report to EPA if the
manifest is not returned to him
within 45 days. An exception report
must be completed for any
unreturned manifests. Annual
reports documenting shipments of
all hazardous wastes originating
during the report year also are
required. All information submitted
by a generator is available to the
public to the extent authorized by the
Freedom of Information Act and EPA
rules related to that Act.
Table 11.
Toxic Waste Limits Set by EPA's
Extraction Procedure Toxicity Test
Extract Level
(mg/l)
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
5.0
100.0
1.0
5.0
5.0
0.2
1.0
5.0
29
-------
YES
Waste is
hazardous
ls<220lb
of waste
produced
peT month?
YES
t
JNO
Record
manifest
reports
t
Will the
waste be
stored for
< 90 days?8
i
YES
I
NO
F
Follow storage
requirements:
Site selection
Security
Inspection
Records
L
Follow disposal
requirements:
Licensing
Security
Inspection
Records
Financing
Monitoring
Closure requirements
Emergency
Process standards
•180 days for small quantity generators (220 to 2,200 Ib/mo).
Figure 11. Obligations of Hazardous Waste Generators Under RCRA
30
-------
Under the 1984 RCRA Amendments,
hazardous waste generators will be
affected by many new requirements.
For instance, the landfilling of bulk or
noncontainerized liquids is
prohibited, and EPA must soon
decide whether land disposal
methods can be used at all for
disposal of certain hazardous
wastes. After September 1,1985,
generators will have to certify that
the amount and toxicity of the
hazardous waste generated has been
reduced to the maximum degree
economically practicable. Many of
these new requirements are
expected to increase the hazardous
waste disposal costs of existing
generators and to bring additional
small-quantity generators and other
sources under RCRA.
Special Provisions for Small
Quantity Generators. A "small
quantity generator" is a business or
organization that produces
hazardous waste in quantities less
than 2,200 Ib (1,000 kg) per month.
Most electroplaters fall into this
category.
Under the May 1980 hazardous
waste regulations, small quantity
generators were required only to
determine whether or not they
produced hazardous waste, and to
see that the waste was sent to
facilities approved by EPA or a
state to manage municipal or
industrial solid waste.
In the 1984 Amendments, however.
Congress directed EPA to publish
regulations covering generators of
more than 220 Ib (100 kg) but less
than 2,200 Ib (1,000 kg) of hazardous
waste per month. These regulations
must be published by March 31,
1986. In these regulations, EPA must,
at a minimum, require these small
quantity generators to see that their
hazardous waste is disposed of at a
hazardous waste facility permitted
under RCRA to manage hazardous
wastes.
The new law also specifies that by
August 1985, generators of 220
to 2,200 Ib (100 to 1,000 kg) of .'
hazardous waste per month are
required at a minimum to complete
certain portions of the manifest to
accompany hazardous waste they
ship off their premises:
• Name, address, and signature of
the generator
• Shipping name and hazard class,
as found in DOT regulations 1
• Number and type of containers
• Quantity of hazardous waste being
transported
• Name and address of facility
designated to receive the
hazardous waste.
Requirements for Storage and
Disposal Facilities. Any generator
who stores hazardous wastes on-site
for 90 days or longer* is subject to
the same regulations that apply to
owners and operators of hazardous
waste storage and disposal facilities.
The storage regulations
promulgated in May 1982, are
intended to prevent the release of
hazardous waste from storage areas
into the environment.
Storage areas must have a
continuous base impervious to the
material being stored and must
provide for spill containment with
either dikes or trenches. Under the
RCRA Amendments, hazardous
waste storage impoundments may
have to be double-lined and a
groundwater monitoring system
may have to be installed depending
upon the hydrogeology of the site
and its proximity to drinking water
sources. Wastes must be stored in
tanks and containers that meet EPA
specifications for the storage of
flammable and combustible liquids.
Containers must be constructed of or
lined with materials which are
compatible with the waste. In
addition, records must be
maintained throughout the storage
period to show the identity and
location of all stored hazardous
wastes.
*180 days for small quantity generators.
31
-------
Hazardous Waste Delisting. RCRA
regulations include a procedure,
called delisting, by which specific
hazardous wastes can be excluded
from RCRA coverage even though
they are listed in the RCRA
regulations. A waste can be delisted
when certain criteria are met,
including conformance with the
standards listed in Table 11. The
advantages of delisting include
lower waste disposal and
recordkeeping costs. EPA requires
that a minimum of four samples of a
waste be analyzed in support of a
delisting petition. The analytical data
and other required information must
be submitted to either an authorized
RCRA state agency or to the Federal
EPA. Specific delisting rules for
states may vary from the Federal
rules.
Many electroplaters and metal
finishers have been successful in
receiving a temporary delisted status
for their wastewater treatment
sludges. These sludges have been
dewatered to the point where the
toxic materials they contain do not
leach out of the sludge cake under
the conditions of the EP toxicity test.
Hazardous Waste
Management
The rapidly escalating cost of solid
and hazardous waste disposal
virtually necessitates an effective
waste management program.
Because the wastewater treatment
system sludge constitutes the most
significant portion of the
electroplater's solid and hazardous
waste, this [discussion will focus on
the management of wastewater
treatment sludges.
The cost of sludge disposal varies.
with three factors: the volume of
sludge to be disposed of, the unit
cost to transport the sludge to a
licensed disposal site, and the unit
fee charged by the disposal site to
accept the sludge. Because the latter
two factors are not likely to be under
the control of the sludge generator,
waste management is concerned
primarily with reducing the volume
of sludge generated. Figure 12
illustrates the relationship between
the annual disposal cost, the amount
of sludge disposed of, and the unit
cost of disposal. The amount of
sludge generated can be reduced in
a number of ways:
Recessed chamber sludge dewatering filter press with sludge cart,
32
-------
500
375
SI
te
O
O
CO
O
Q-
co
Q
D
<
250
125
Legend:
A disposal cost of $1.50/gal
B disposal cost of $0.50/gal
25
50
75
100
SLUDGE VOLUME (gal/h)
Note:
Based on operating time of 3,000 h/yr.
Figure 12. Annual Cost of Sludge Disposal
By reducing the mass of pollutants
entering the waste treatment
system
By reducing the wastewater
volume entering the treatment
system
By using wastewater treatment
techniques that generate minimal
quantities of sludge
By reducing sludge volume by
mechanical dewatering.
To evaluate sludge volume reduction
alternatives, the plant must first
define its present and future disposal
cost factors. Typically, disposal sites
accepting metal hydroxide sludges
base their charges on the volume of
sludge. In some cases, the site will
have one rate structure for fluid
sludges and one for nonflowing
sludges. As a rule, transportation
costs are directly related to the
sludge volume or weight.
Reducing Waste Loads
Reducing the quantity of pollutants
and the volume of wastewater
before it is sent through a
wastewater treatment system has
two advantages: it reduces
wastewater treatment costs and it
reduces the volume of sludge
generated. Although the effect of
reducing wastewater flow is not
usually as great as the effect of
reducing the level of heavy metal
pollutants in the wastewater, the
volume of wastewater processed
does influence sludge generation.
Because of the high pH of most
wastewater discharges, the greater
the water volume treated, the greater
the consumption of the alkali
neutralizing agent (caustic, lime) and
water conditioning agents (ferric
chloride, aluminum chloride). These
chemicals contribute to the quantity
of sludge generated. In the case of
lime, some portion normally remains
undissolved and adds to the sludge
volume. Conditioners such as ferric
and aluminum chloride are
converted to insoluble hydroxides
during treatment, thereby increasing
the volume of the sludge.
The effect of reduced pollutant
loading on sludge volume is easier
to determine. For example, a
discharge of 1 Ib (0.45 kg) of chromic
acid anhydride to the wastewater
will result in the precipitation of
approximately 1 Ib (0.45 kg) of
chromium hydroxide during the
treatment process. This amount of
chromium hydroxide will add
approximately 6 gal (23 I) of volume
to the clarifier underflow, based on
an underflow solids concentration of
2 percent by weight. Similar
relationships exist for other metals
used in plating operations.
33
-------
Optimizing Waste Treatment
Systems
The high cost of sludge disposal
demands that the design of
wastewater treatment systems
consider the relative volumes of
sludge generated by each of the
treatment systems considered. Many
of the newly developed treatment
techniques offer improved pollutant
removal capabilities compared with
the capabilities of conventional
treatment, but at the cost of
significant increases in sludge
generation. For this reason, the
treatability studies conducted during
the evaluation of the different
treatment alternatives should
address sludge generation and the
dewatering properties of the
resultant sludge.
For example, insoluble sulfide
precipitation can reduce the metal
concentration in many waste
streams to lower levels than can
hydroxide precipitation. However,
because this process uses ferrous
sulfide as the source of the sulfide
ion, ferrous ions are liberated in the
reaction and converted to ferrous
hydroxide, which adds to the sludge
volume. Figure 13 compares the
sludge generation rates of an
insoluble sulfide precipitation
system and an insoluble sulfide
polishing system with a
conventional hydroxide system,
using sodium hydroxide as the
neutralizing agent, over a range of
flow rates. Using the sulfide process
as a polishing system to reduce the
concentration of metals in the
effluent after a conventional
hydroxide precipitation/clarification
sequence will achieve the same
degree of metal removal as sulfide
precipitation, but compared with the
hydroxide process, will increase the
volume of sludge generated only
slightly. The trade-off, however, is
that a polishing system will require
additional hardware and have a
higher initial cost. The savings in
sludge disposal fees and reagent
costs must justify the added expense
of the polishing system.
40 r±
30
g
C5
UJ
CD
Q
20
10
Legend:
A insoluble sulfide precipitation
B hydroxide neutralization/
clarification with insoluble
sulfide polishing
C hydroxide neutralization/
clarification
OJ 500 1,000 1,500 2,000
] WASTEWATER FLOW RATE (gal/h)
Notes:
Sludge generation at 3% solids by weight.
VVastewater contains 30 ppm FE+3, 40 ppm Ni+2
Sulfide reagent demand equals 3 times the stoichiometric requirements.
2,500
Figure 13. Sludge Generation Rates for Three Wastewater Treatment
Systems |
i
The choice bf reagents for an
existing treatment process can
drastically affect the quantity of
sludge generated. Lime and caustic
soda are the two alkali neutralizing
agents used most frequently. The
advantages of lime include lower
cost per unit of neutralizing capacity,
sludge that.settles and dewaters
more readily, and the ability to
reduce metals to lower levels in
some applications (primarily
because of the chelate-breaking
capabilities of the calcium ions).
Lime has disadvantages, however, in
that it requires a higher investment
in the reagent feed system, takes
longer to react in the wastewater,
and (according to one study)
produces three to six times the bulk
of sludge produced by caustic soda
neutralization.
A relatively new reagent, sodium
borohydride, may offer technical
advantages over both lime and
caustic. In EPA tests10, sodium
borohydride produced a sludge
mass equal to caustic treatment
while removing metals to levels
lower than lime. Additionally,
sodium borohydride can
simultaneously reduce hexavalent
chromium. A disadvantage is the
relatively high cost of sodium
borohydride.
34
-------
Sludge Dewatering
Since sludge disposal costs depend
primarily on sludge volume,
mechanical dewatering devices have
been shown to produce considerable
cost savings. Figure 14 shows the
volume reduction achieved by
dewatering as a function of solids
concentration. As an example,
consider 1,000 gallons of sludge at
approximately 1 percent solids.
Dewatering to 25 percent solids
would reduce the sludge volume to
about 32 gallons, a volume reduction
of nearly 97 percent. Mechanical
dewatering devices that have been
used successfully to concentrate
metal hydroxide sludge include
pressure, vacuum, and compression
filters, and centrifuges. These are
described briefly below and in
considerable detail in a recent EPA
report16.
Pressure filters dewater sludge by
pressurizing it and forcing the water
out through a membrane. The
simplest pressure filter in its
construction and operation is the
recessed filter plate press (shown in
Figure 15); it is also the most popular
mechanical sludge dewatering
device in the industry today. Such
filters most effectively dewater
sludges that are very dilute or
subject to wide variations in solids
concentration. Low-pressure filters
(80 to 150 psig) can achieve sludges
of 20 to 40 percent solids, while high-
pressure filters (150 to 225 psig) can
attain 30 to 50 percent solids. As with
all sludge filtration devices, the final
solids concentration primarily
depends on the length of time the
sludge remains in contact with the
filter and on the magnitude of the
forces applied to the sludge.
§
HI
ta
Q
1,000
500
400
300
200
100
50
40
30
20
10
10
15
20
25
30
35
SLUDGE SOLIDS CONCENTRATION (% by weight)
Figure 14. Sludge Volume as a Function of Solids Concentration
35
-------
Filtrate to clarifier
Air supply (100 pslg)
V
Clurifier underflow «•»
Rgtire 15. Low-Pressure Recessed Plate Filter Press;
Vacuum filters dewater sludge by
creating a vacuum which draws the
water through a membrane. The
rotary-drum filter is by far the most
popular vacuum filter used in the
industry. These filters perform best
with feed solids concentrations
above 3 percent by weight; sludges
containing lower feed solids
concentrations are usually thickened
before vacuum filtration. Rotary-
drum filters are often precoated with
diatomaceous earth, particularly for
use with dilute or otherwise hard-to-
filter sludges. The precoat material
represents an additional cost and
adds to the quantity of solids to be
disposed of, but in many cases this
method significantly improves the
solids concentration. Vacuum filters
can usually attain 20 to 30 percent
solids concentration, depending on
the depth to which the drum is
submerged and the rotational speed
of the drum.
Compression filters dewater the
sludge by squeezing it between
water-permeable membranes. The
units consist of a series of belts and
rollers thatgradually increase the
compressive force applied to the
sludge. This technique has proved
effective mainly for dewatering
highly compressible sludges
characterized by large, delicate
particle floes typically associated
with polyelectrolyte conditioning.
The compression filter was
developedito overcome the difficulty
of dewatering this type of sludge by
filtration. Compression filters
consume less energy than vacuum
filters or centrifuges, but are more
mechanically sophisticated.
Consequently, the relatively high
capital cosit of smaller units makes
them unattractive for concentrating
the lower sludge volumes typical of
the plating industry.
Centrifuges dewater sludge in a
manner similar to gravity thickeners,
but they create an apparent gravity
thousands of times more powerful
by rapidly rotating the sludge. The
increased gravity greatly accelerates
the settling process and magnifies
the compaction effect. Solids
concentrations of 10 to 20 percent
can be attained, depending on the
nature of the sludge. The use of a
centrifuge usually requires that the
feed stream be conditioned with a
polyelectrolyte to increase settling
ability. Because of the need for
polyelectrolytes and their limited
ability to achieve high solids
concentrations, centrifuges are
losing favor to pressure filters for
electroplating sludge dewatering.
36
-------
The following example examines the
economics of installing a recessed
plate filter press (Figure 15) to
dewater a dilute clarifier underflow
from 3 percent solids (by weight) to
20 percent solids. Figure 16
compares the annual costs of
disposing of the sludge at 3 percent
solids with two higher
concentrations. The figure shows
two curves for sludge disposal at 20
percent solids by weight: one cost
including filter press operation as
well as dewatered sludge disposal
(at $1.00/gal) and the other, the cost
of sludge disposal alone. Even with
its operating costs included, the filter
press reduces annual disposal costs
at underflow rates exceeding 10
gal/h (57 l/h). For a plant disposing of
its sludge at $1.00/gal, the
investment has a reasonable rate of
return at 17 gal/h (95 l/h).
Mechanical dewatering, then, is
usually a cost effective approach to
the problem of solid waste
management.
Plants generating very small sludge
volumes (i.e., less than 17 gal/h) may
find that the investment cost of
sludge dewatering equipment
cannot be justified by the limited
quantities of sludge in need of
disposal. Some hazardous waste
disposal sites have some means
of dewatering sludge. Plants
generating small volumes of sludge
may find it cost-effective to use these
capabilities of the disposal facility
since hazardous waste regulations
promulgated in May 1985 prohibit
the landfilling of sludges unless
they have been dewatered or
containerized.
1,000
o 800
w
8
600
co
Q
LLJ
C5 400
Q
200
Legend:
A disposal of sludge at 3% solids
B disposal of sludge at 20% solids
C disposal of sludge at 20% solids
plus annual cost of filter press
100 200 300 400
CLARIFIER UNDERFLOW (gal/h)
Notes:
Assumes $1.00/gal sludge disposal fee,
Clarifier underflow = 3% solids, and
4,800 h/yr operation.
500
600
Figure 16. Sludge Disposal Costs with and without Filter Press
37
-------
6. Pollution Control
Financing
Alternatives
The Federal government has
established tax incentives and has
made finanping alternatives
available to ease the burden of
complying with environmental
regulations'. The financing
alternatives are available through
several different government
programs. The following provides an
overview of the various programs
and sources of more detailed
information at the Federal level.
Regional, local, and district offices of
all of the Federal agencies listed
below can be found in local
telephone directories.
Income Tax Provisions
There are three categories of Federal
income tax deductions for
investments in pollution control
facilities:
• Interest paid on the loan to finance
the project
• Yearly cost of the pollution control
project as determined by
amortizing or depreciating its cost
• Investment credits.
Questions should be addressed to:
Internal Revenue Service (IRS)
1201 E Street, N.W.
Washington, DC 20224
IRS toll-free telephone assistance:
(800)424-1040
IRS Tel-Tax (Recorded tax
information on 140 topics available
24 hours a day, seven days a week):
Local IRS telephone
IRS Walk-in assistance: Local IRS
office
For detailed instructions on the
deductions mentioned above, the
following publications should be
consulted:
IRS Publication 334, Tax Guide for
Small Business
IRS Publication 534, Depreciation
IRS Publication 572, Investment
Credit
IRS Publication 535, Business
Expense
38
-------
Small Business
Administration
The U.S. Small Business
Administration (SBA) operates three
programs to help small businesses
which are independently owned and
fall within SBA's definition of a small
business finance pollution control
project:
• The 7(a) Program
• Pollution Control Financing
Guarantees
• The Section 503 program.
The 7(a) Program. To be eligible for
funds under the 7(a) Program, the
borrower must have been turned
down by two institutional lenders.
Financing may be used for the
purchase of land, site preparation,
engineering and design costs,
purchase of equipment and
machinery, construction, and
working capital. Both direct loans
and guaranteed loans are available.
Direct loans are for amounts of up to
$150,000. Loans are guaranteed in
amounts of up to 90 percent of the
total loan amount or $500,000,
whichever is less. Details about this
program can be obtained from any
local or district office of the SBA, or
from:
Office of Business Loans
U.S. Small Business Administration
1441 L Street, N.W.
Washington, DC 20416
(202) 653-6696
Pollution Control Financing
Guarantees. Guarantees are
available to small businesses
requiring financing of more than
$250,000. The maximum loan limit in
this program is $5 million. To be
eligible, the business must have a
minimum of five years' operating
history and must show a profit in any
three of the five years in operation.
Funds may be used for the purchase
of real estate, site preparation and
construction, purchase and
installation of equipment, and
financing. Bonds are issued by a
state or local authority, and the SBA
guarantees payment. In the past,
SBA was restricted by law to issuing
guarantees only for taxable
financings. A recent change in the
law (PL 98-473, October 12,1984)
allows SBA to guarantee tax-exempt
financings as well. Further details
about this program can be obtained
from:
Pollution Control Financing Branch
U.S. Small Business Administration
4040 N. Fairfax Drive, Suite 500
Arlington, VA 22203
(703) 235-2902
The Section 503 Program.
Participation in this program is
through a Certified Development
Company; these are corporations
organized through SBA to issue
loans for business and community
development. Financing may be
used to purchase fixed assets with a
useful life of more than 15 years (i.e.,
land, equipment, facilities). These
loans are for up to 40 percent of the
total loan or $500,000, whichever is
less. Details about this program and
application forms can be obtained
from:
Office of Business Loans
U.S. Small Business Administration
1441 L Street, N.W.
Washington, DC 20416
(202) 653-6696
39
-------
Economic Development
Administration
The Economic Development
Administration (EDA) finances the
growth of businesses in
redevelopment areas. Although the
financing of pollution control
equipment is not specifically covered
by the EDA, such items may be
eligible under this program. EDA-
guaranteed loans may be used for
the purchase of land, construction,
equipment, and operating capital.
The EDA will guarantee up to 90
percent of the total loan, but prefers
to guarantee 75 percent or less.
Minimum loan amounts are
$550,000, with a maximum of $10
million. Further information can be
obtained from:
U.S. Department of Commerce
Economic Development
Administration
15th & Constitution Avenues
Room 7844
Washington, DC 20230
(202) 377-5067
Farmers' Home
Administration
Farmers' Home Administration
(FHmA) loans are used to assist
companies located in rural areas of
the country with the purchase of
land, facilities, supplies, and for
working capital. Loans are available
through conventional lenders and
are guaranteed by the FHmA.
Information about the loan
application process and other details
can be obtained from:
Farmers Home Administration
Business and Industry Division
14th and Independence Ave., S.W.,
Room 5420
Washingtok DC 20250
(202)475-4100
Other Sources of Financing
In addition to the programs operated
on the Federal level, financing for the
purchase of pollution control
equipment can be obtained through
private sources as well as through
state and county governments.
Information on these programs at
the state and county levels is
available from local authorities and
EPA's Regional Small Business
Liaison contacts listed in the
following section.
40
-------
7. EPA Sources of
Additional
Information
A number of regional and Federal
EPA representatives can provide
detailed information on
environmental regulations and
financial alternatives.
EPA Headquarters Office
General regulatory information:
U.S. Environmental Protection
Agency
401 M Street, S.W.
Washington, DC 20460
(202) 382-4700
Effluent guidelines and standards:
Jeffrey Denit (WH-552)
U.S. Environmental Protection
Agency
401 M Street, S.W.
Washington, DC 20460
(202)382-7120
Hazardous waste storage and
disposal:
RCRA Hotline: (800) 424-9346.
Financial assistance:
Frances Desselle
Financial Assistance Coordinator
Office of Analysis and Evaluation
Environmental Protection Agency
401 M Street, S.W.
Washington, DC 20460
(202) 382-5373
Small Business Ombudsman
Environmental Protection Agency
(A149C)
401 M Street, S.W.
Washington, DC 20460
(202) 557-7015 or
(800) 368-5888
EPA Regional Offices
Region I (Connecticut, Maine,
Massachusetts, New Hampshire,
Rhode Island, and Vermont)
Room 2203, JFK Federal Building
Boston, MA 02203
David Fierra
Water Division Director
(617) 223-3478
Lester Sutton
Small Business Liaison
(617) 223-5424
Region II (New Jersey, New York,
Puerto Rico, and the Virgin Islands)
Room 900, 26 Federal Plaza
New York, NY 10007
William Muszynski
Water Division Director
(212)264-2573
Kenneth Eng
Small Business Liaison
(212)264-4711
41
-------
Region III (Delaware, Maryland,
Pennsylvania, West Virginia, District
of Columbia, and Virginia)
841 Chestnut Street
Philadelphia, PA 19107
Greene A. Jones
Water Division Director
(215)597-9411
Jim Burke
Small Business Liaison
(215)597-3658
Region IV (Alabama, Florida,
Georgia, Kentucky, Mississippi,
North Carolina, South Carolina,
and Tennessee)
345 Courtland Street, N.E.
Atlanta, GA 30308
Bruce Barrett
Water Division Director
(404)881-4450
H. Mack Rhodes
Small Business Liaison
(404) 881-4727
Region V (Illinois, Indiana,
Wisconsin, Michigan, Minnesota,
and Ohio)
230 Dearborn Street
Chicago, IL 60604
Charles H. Sutfin
Water Division Director
(312) 353-2147
Kathy Brown
Small Business Liaison
(312) 353-3299
Region VI (Arkansas, Louisiana, New
Mexico, Oklahoma, and Texas)
First International Building
1201 Elm Street
Dallas, TX 75270
i
Myron O. Knudson
Water Division Director
(214)729-2^56
Carl Edlund
Small Business Liaison
(214) 767-2605
i
Region VII (Kansas, Missouri,
Nebraska, and Iowa)
324 East 11th Street
Kansas City, MO 64108
t
Paul M. Walker (Acting)
Water Division Director
(816) 758-6^401
Ron Ritter i
Small Business Liaison
(816)374-6,201
Region VIII (Colorado, Wyoming,
Montana, North Dakota, South
Dakota, and Utah)
1860 Lincoln Street
Denver, CO 80203
Max Dodson :
Water Division Director
(303) 327-4871
Charles Stevens
Small Business Liaison
(303)837-3711
Region IX (Arizona, California,
Hawaii, Nevada, American Samoa,
Guam, and the Trust Territories)
215 Fremont Street
San Francisco, CA 94105
Frank M. Covington
Water Division Director
(415)454-8115
James Thompson
Small Business Liaison
(415)974-8015
Region X (Alaska, Idaho, Oregon,
and Washington)
1200 Sixth Avenue
Seattle, WA 98101
Robert Burd
Water Division Director
(206)399-1237
John Ybarra
Small Business Liaison
(206)442-1233
42
-------
References
Regulations
1U.S. Department of Transportation.
"Hazardous Material Table and
Hazardous Materials
Communications Regulations."
Code of Federal Regulations, Title
49, Part 172.
2U.S. Environmental Protection
Agency. "Standards Applicable to
Owners and Operators of
Hazardous Waste Treatment,
Storage, and Disposal Facilities."
Code of Federal Regulations, Title
40, Parts 260-267.
3 "General Pretreatment
Regulations for Existing and New
Sources of Pollution." Code of
Federal Regulations, Title 40, Part
403.
4 "Effluent Guidelines and
Standards; Electroplating Point
Source Category; Pretreatment
Standards for Existing Sources."
Code of Federal Regulations, Title
40, Part 413.
5 "Effluent Guidelines and
Standards: Metal Finishing Point
Source Category; Treatment
Standards for Existing Sources."
Code of Federal Regulations, Title
40, Part 433.
Proceedings
6U.S. Environmental Protection
Agency and American
Electroplaters' Society, Inc. (co-
sponsorsMnnua/ Conference on
Advanced Pollution Control for the
Metal Finishing Industry (1st), held
at Lake Buena Vista, Florida on
January 17-19, 1978. EPA 600/8-78-
010. NTIS No. Pb 282-443. May
1978.
Reports
8U.S. Environmental Protection
Agency. Advanced Treatment
Approaches for Metal Finishing
Wastewaters. Part 1. EPA 600/J-77-
056a. NTIS No. Pb 277-147. Oct.
1977.
. Advanced Treatment
Approaches for Metal Finishing
Wastewaters. Part 2. EPA600/J-77-
056b. NTIS No. Pb 277-148. Nov.
1977.
10
..Assessment of
Emerging Technologies for Metal
Finishing Pollution Control: Three
case studies. Contract No. 68-03-
2907-09. (Prepared by Philip A.
Militello).
11
Control and Treatment
Technology for the Metal
Finishing Industry: Ion Exchange.
EPA 625/8-81-007. (Prepared by
Centec Corporation). June 1981.
— Control Technology for
the Metal Finishing Industry:
Evaporators. EPA 625/8-79-002.
(Prepared by Centec Corporation).
June 1979.
12
13
_. Controlling Pollution
from the Manufacturing and
Coating of Metal Products: Water
Pollution Control. EPA 625/3-73-
009. (Prepared by Centec
Corporation). May 1977.
7 Conference on Advanced
Pollution Control for the Metal
Finishing Industry (2nd), held at
Kissimmee, Florida on February 5-
7, 1979. EPA 600/8-79-014. NTIS
No. Pb 297-453. June 1979.
43
-------
14
.Electrodialysis for Closed
Loop Control of Cyanide Rinse
Waters. EPA 600/277-161. NTIS No.
Pb 272-688. (Prepared by
International Hydronics
Corporation). Aug. 1977.
19
15
_. Electrolytic Treatment of
Job Shop Metal Finishing
Wastewater. EPA 600/2-75-028.
NTIS No. Pb 246-560. (Prepared by
New England Plating Company).
Sept. 1975.
16
-Environmental Pollution
Control Alternatives: Sludge
Handling, Dewatering, and
Disposal Alternatives for the Metal
Finishing Industry. EPA 625/5-82-
018. (Prepared by Centec
Corporation). Oct. 1982.
17
Evaporative Recovery of
Chromium Plating Rinse Waters.
Project No. S803781-1. (Prepared
by Advance Plating Company and
Corning Glass Works). Feb. 1977.
18
..An Investigation of
Techniques for Removal of
Cyanide from Electroplating
Wastes. EPAWOO-12010-EIE-11/71.
NTIS No. Pb 208-210. (Prepared by
Battelle Columbus Laboratories).
Nov. 1971.
_. 'Investigation of Treating
25
Electroplaters' Cyanide Waste by
Electrodialysis. EPA R2/73-287.
NTIS No. Pb 231-263. (Prepared by
RAI Research Corporation). Dec.
1973. i
20
New Membranes for
Treating Metal Finishing Effluents
by Reverse Osmosis. EPA 600/2-76-
197. NTIS No. Pb 265-363.
(Prepared by Midwest Research
Institute).! Oct. 1976.
21
-.{Ozone Treatment of
Cyanide-Bearing Plating Waste.
EPA 600/2-77-104. NTIS No. Pb 271-
015. (Prepared by Sealectro
Corporation).
. FBI Reverse Osmosis
Membrane for Chromium Plating
Rinse Water. EPA 600/2-78-040.
NTIS No.Pb 280-944. (Prepared by
America^ Electroplaters' Society).
Mar. 1978.
23
-.Removal of Chromium
from Plating Rinse Water Using
Activated Carbon. EPA 600/2-75-
055. NTIS No. Pb 243-370.
(Prepared by Battelle Memorial
Laboratories). June 1975.
24 'Removal of Heavy Metals
from Industrial Wastewater Using
Insoluble Starch Xanthate. EPA
600/2-78-J085. NTIS No. Pb 283-792.
(Prepared by U.S. Department of
Agriculture, Agricultural Research
Service). May 1978.
_. Reverse Osmosis Field
Test: Treatment of Copper Cyanide
Rinse Waters. EPA 600/2-77-170.
NTIS No. Pb 272-473. (Prepared by
Abcor, Inc.). Feb. 1977.
26 Reverse Osmosis Field
Test: Treatment of Watts Nickel
Rinse Waters. EPA 600/2-77-039.
NTIS No. Pb 266-919. (Prepared by
Abcor, Inc.). Feb. 1977.
27
_. Treatment of Complex
Cyanide Compounds for Reuse or
Disposal. EPA R2-73-269. NTIS No.
Pb 222-794. (Prepared by Berkey
Film Processing of New England).
June 1973.
28
. Treatment of
Electroplating Wastes by Reverse
Osmosis. EPA 600/2-76-261. NTIS
No. Pb 265-393. (Prepared by
American Electroplaters' Society).
Sept. 1976.
29
_. Treatment of Metal
Finishing Wastes by Sulfide
Precipitation. EPA 600/2-77-049.
NTIS No. Pb 267-284. (Prepared by
Metal Finishers' Foundation). Feb.
1977.
44
-------
-------
&EPA
------- |