Table of Contents
Electrocoating: Regulatory Requirements
The Clean Air Act regulates the emission of
compounds (VOCs) (40 CFR Part 60) and hazardous
air pollutants (HAPs) (40 CFR Part 61 and
40 CFR Part 63), and provides specific standards
of performance to control emissions from various types of coating operations
(40 CFR Part 60). Depending on the solvent content
of the coating material used with electrocoating methods, solvents can
evaporate and produce sufficient VOC and HAP emissions to subject an operator
to major source requirements and
Title V permitting requirements.
Controlling VOC emissions from electrocoating areas can be accomplished
in several ways. First, a coating material with a lower VOC content
can be used. Second, air
pollution control equipment can be attached to the ventilation system
to capture VOCs prior to their release into the atmosphere.
As part of the Clean Water Act, Effluent
Guidelines and Standards for Metal Finishing (40 CFR Part 433) have
been established that limit concentrations of toxic
organics in wastewater streams. The organic solvents often contained
in liquid coatings used with electrocoating application methods may be
classified as toxic organics. These materials can enter the wastewater
through the use of rinse water tanks or when cleaning coatings from containers
or equipment. However, the use of recycling systems to filter and
reuse coatings and rinse waters greatly reduces the possibility of contamination. Actual limits for effluent constituents depend on the size of the operation
and the amount of wastewater generated from the facility. If the facility
discharges directly to receiving
waters, these limits will be established through the facility's National
Pollutant Discharge Elimination System (NPDES) permit (40
CFR Part 122). Facilities which are indirect dischargers releasing
to a POTW must meet limits in the POTW's discharge agreement. Wastewater
streams with concentrations exceeding permit limits will require pretreatment
prior to discharge to receiving waters
or to a publicly
owned treatment works. Pretreatment may include separation of
liquid wastes to remove solvents, and settling or precipitation of solid
materials. Indirect discharges who release to POTW's must meet limits
in the POTW discharge agreement.
Solid and Hazardous Waste
Under the Resource Conservation and Recovery
Act (RCRA), organic finishing facilities are required to manage listed
and characteristic hazardous wastes (40 CFR Part
261). Liquid coatings used with electrocoating application methods
may contain constituents listed or characterized as hazardous wastes. Materials contaminated with the coatings, such as air filters, masking
materials for floors, conveyor system components, and rags or other materials
used for cleaning, may require treatment as hazardous waste depending on
their formulation. Hazardous waste management (40
CFR Part 262) includes obtaining permits for the facility in order
to generate wastes, meeting accumulation limits for waste storage areas,
and manifesting waste containers for off-site disposal.
The Emergency Planning and Community Right-to-Know
Act (EPCRA) requires facilities to notify employees, customers and
the surrounding community of certain hazardous chemicals and materials
(40 CFR Parts 355
and 370) that are present on-site. Electrocoating
operations may use hazardous materials in sufficient quantities to subject
a facility to several EPCRA requirements. Facilities may be required
to inform the local
emergency planning committee (LEPC) and the state
emergency response commission (SERC) of the materials stored and used
on-site, devise emergency
response plans for reacting to spills, and notify authorities of accidental
spills and releases (40 CFR Parts 302 and 355). The materials used in electrocoating solutions may also require facilities
to submit Material
Safety Data Sheets (MSDS) for these materials to state, regional, and
local organizations, while disposed volumes of the material may have to
be documented on annual Toxic
Release Inventory reports (40 CFR Part 372).
Health and Safety
While not directly regulated by EPA, several conditions exist that
should be considered when using electrocoating application methods. Workers should be aware of their responsibilities when handling coating
materials during equipment preparation and cleaning activities. Workers
should also know the risks associated with inhaling the VOC
emissions from the coating materials. Finally, workers should be
trained properly to avoid accidents and injuries when working with spray
equipment, including the probability of electric shock.
Do exhaust air streams have air pollution control equipment attached? Is that air pollution control equipment working properly? Does final
exhaust air have concentrations of pollutants below required levels?
Does the electrocoating system produce a liquid waste stream? Do concentrations of pollutants in the waste stream exceed limits established
by the facility NPDES permit or POTW discharge agreement?
Are solid wastes handled to separate hazardous and non-hazardous wastes? Are wastes labeled and packaged in accordance with 40
CFR Part 262, Subpart C? Are manifest forms completed for hazardous
wastes to be shipped for disposal?
Electrocoating: Common Causes of Violations
Electrocoating systems apply coating materials which may include solvents
classified as volatile organic compounds and/or hazardous air pollutants. The solvents evaporate and may accumulate above limits allowed by Clean
Air Act Title V permits. Ventilation and exhaust systems must operate properly to ensure the vapors
are removed from the electrocoating area. Air pollution control equipment
should be attached to exhaust systems to recover or destroy volatile organic
compounds and hazardous air pollutants instead of releasing them to the
Electrocoating systems utilize liquid coating materials as well as solvent
and water rinses which can contaminate water streams. Contamination
may occur when replacing used rinse solutions or from accidental spills
or leaks from equipment. Contaminated water streams may contain pollutants
or heavy metals in concentrations that exceed the limits established by
permits or POTW
discharge agreements. As a result, effluent, may not be directly
released to water systems or to publicly owned treatment works without
Electrocoating systems utilize liquid coating materials and rinses with
organic solvents which must be stored, manifested and disposed of according
to 40 CFR Part 262 if classified as hazardous
waste under 40 CFR Part 261.
Electrocoating: Sources of Pollution
Electrocoating systems apply liquid coating materials that contain components
classified as volatile organic compounds, hazardous air pollutants, and/or
ozone depleting substances. In addition, the large surface area of
electrocoating tanks exposes much of the coating to the air which promotes
evaporation of the solvents.
Electrocoating systems can generate large volumes of coating material waste. Coating materials may be contaminated by dirt, dust, or other debris that
falls into the tank. Coating materials may not maintain uniform consistency
of pigments and additives if not properly mixed. Excess coating material
is necessary to meet tank depth requirements. These coating materials
Electrocoating rinse tanks produce waste solvents, water, and coating solids
if not filtered and reused.
Electrocoating: Pollution Prevention Alternatives
Use liquid coating materials with low organic solvent content to minimize
the amount of volatile organic compounds that will be volatized and to
reduce the volume of solid and liquid hazardous waste created.
Electrocoating provides pollution prevention over traditional spray application
systems due to the higher transfer efficiency (above 90%), and lower volatilization
of organic solvents.
Recycle permeate and water rinse solutions, a typical operation of electrocoating
lines. Solutions are filtered to separate coating solids and return
them to the coating dip tank. â€œCleanâ€� permeate and water is returned
to the rinse tanks.
Reduce or eliminate contamination of coatings by enclosing and covering
tanks. Surround system with a semi-open structure which allows operation
of the process but does not fully expose the tanks to the air and contaminants
from the rest of the facility. Securely cover coating tank when not
in use to maintain coating purity and prevent solvent evaporation.
Orient parts to minimize areas that would hold excess coating material
and rinse solutions when removed from tanks.
Increase the time a part is suspended over each tank so that excess material
runs into the same tank, not subsequent ones.
Schedule paint jobs to minimize changing colors in electrocoating equipment. Paint with light colors first, then darker ones; lighter coating does not
need to be completely removed from the equipment, but can blend into the
darker coating. Since most electrocoating lines apply only one color,
this is typically not an issue.
Clean electrocoating equipment regularly to prevent coating materials from
drying inside tanks and fluid lines. Use water in cleaning steps
to reduce the amount of organic solvents used and amount of hazardous waste
generated. Perform initial cleaning with used solvent, saving fresh
solvents for final cleaning stages.
Segregate non-hazardous coating solids and water from hazardous solvents
and thinners, and label containers to prevent mixing. Separation
of the materials reduces the amount of hazardous waste that is produced. Coating material solids can be dried and treated as a solid waste, thus
allowing for disposal in a landfill.
Maintain equipment to sustain proper operation. Keep air lines free
of water, dirt, and oils. Make sure valves, gauges, pumps, and filters
are in proper working order.
Keep electrocoating areas clean so that leaks in equipment can be found
and fixed quickly, and accidents can be prevented.
Train employees on safe handling of materials and wastes and encourage
continuous improvement. Training familiarizes workers with their
responsibilities, which reduces spills and accidents.