United States
Environmental Protection
Agency
Water Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-85/072 Aug. 1985
f/EPA Project Summary
Evaluation of New and
Emerging Technologies in the
Metal Finishing Industry
John D. Dietz and Christopher M. Cherniak
A research program was completed
to identify new and emerging waste
management technologies in the metal
finishing industry. A limited field sam-
pling and analytical program was pur-
sued to define performance at full scale
operating facilities for the following
technologies:
1. Buoyant media filtration - 3M*
2. Zerpol® zero liquid discharge
3. Zerpa distillation solvent recovery
Information was developed regarding
cost, performance, safety, and applica-
bility of these technologies. A prelimi-
nary evaluation of the processes based
on the limited testing indicated poten-
tial applications for all three processes
in segments of the metal finishing in-
dustry.
This Project Summary was devel-
oped by EPA's Water Engineering Re-
search Laboratory, Cincinnati, OH, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
Enactment of federal legislation over
the preceding decade has resulted in
the implementation of extensive pollu-
tion management programs in the elec-
troplating and metal finishing industry.
Effluent limitations and pretreatment
standards have been established for a
number of toxic metals (Cd, Cr, Cu, Pb,
Ni, Ag, Zn), cyanide, total toxic organics
•Mention of trade names or commercial products
does not constitute endorsement or recommenda-
tion for use
(TTO), oil and grease, total suspended
solids (TSS), and pH.
Although the effluent standards are
based on application of a specific tech-
nology, the individual discharger has
the option to select an alternative
method of treatment. New processes
for treatment of metal finishing wastes
and/or recovery of valuable wastewater
components have been developed in re-
sponse to the environmental legislation
and regulations of the preceding
decade. The U.S. Environmental Protec-
tion Agency (EPA) and The American
Electroplaters' Society, Inc., (AES) have
been involved in many studies to define
the performance of promising tech-
niques and to distribute the information
to the affected segments of the metal
finishing industry. These technologies
offer great environmental benefits by
improving existing processes and by
enhancing industry's ability to meet ap-
plicable standards while minimizing ad-
verse economics impacts. This project
represents a continuation of this coop-
erative effort between EPA and AES.
The principal objectives of the re-
search program were to identify and
evaluate in a preliminary manner new
technologies which could be consid-
ered as alternatives to existing waste
management practices in the metal fin-
ishing industry. Attention was directed
toward methodologies with the poten-
tial for treating industrial liquid effluent
and residual solvent and solids streams.
The objective was to evaluate the effec-
tiveness and potential of these emerg-
ing technologies for applicability on an
industry-wide scale. In some cases, the-
technologies incorporated a novel mod-
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ification to a component of a conven-
tional precipitation process; thus it was
not mandatory that the candidate tech-
nologies be entirely free of the chemical
precipitation treatment method.
Procedure
The research program was initiated in
May 1983 with an aggressive effort to
solicit the metal finishing industry for
information regarding new technolo-
gies. A limited number of the latter were
selected to be characterized by means
of field sampling and analysis. The can-
didate technologies were evaluated on
the basis of the following criteria:
1. Technical merit
Energy requirements
Cost of technology
Degree of applicability
Anticipated performance
Safety considerations
2. Technical probability of success
Current level of demonstration
Technical barriers
Legal constraints
3. Cost of sampling and analysis pro-
gram
Determination of eligibility for partici-
pation in the field characterization
phase of the research centered on the
criteria used to define "new" and
"emerging" technologies. Well-
established technologies were, there-
fore, precluded from this analysis. The
requirement for completion of field
sampling and analysis at an operating
metal finishing facility eliminated addi-
tional technologies that were not suffi-
ciently developed to locate full- or pilot-
scale treatment systems. The decision
to restrict consideration to new and
emerging technologies at a specific
stage of development was consistent
with the objectives and requirements of
this research program. Elimination of a
technology from consideration did not
reflect or imply any adverse judgment
regarding the merit of the technology.
Three technologies were evaluated in
the field by means of a limited sampling
and analysis program:
1. Buoyant media filtration - 3M
2. Zero liquid discharge - Zerpol®
3. Distillation solvent recovery -
Zerpa
Results and Discussion
Buoyant Media Filtration
Buoyant media filtration refers to a
granular bed filtration process in which
liquid passes in an upflow mode
through a media which has a density
less than the density of the filtrate. The
media is held in place below the liquid
surface by a retaining screen. Backwash
of the media is achieved by reversal of
the flow and subsequent fluidization of
the media. This flow reversal is accom-
plished by gravity withdrawal of fluid
from the bottom of the filter unit.
The particular media examined in this
study was manufactured by the 3M
Company. The media, known as macro-
spheres, is available in diameters rang-
ing from 0.3 mm to 6 mm. Potential ap-
plications of the technology include:
1. Effluent polishing following con-
ventional clarification.
2. Replacement of conventional clari-
fication.
3. Modification of conventional clari-
fication to include a buoyant
media filter at the surface of an ex-
isting clarifier.
A production facility was surveyed
which included parallel installation of a
buoyant media filter and a conventional
slant-tube clarifier. Comparative evalua-
tion of the conventional and emerging
technology was pursued on the basis of
this side-by-side experimentation. Al-
though both units achieved compliance
with applicable effluent standards, it
was determined that the buoyant media
filter achieved lower effluent concentra-
tions and reduced variation in effluent
concentration in comparison to the clar-
ifier. A summary of the data is provided
in Table 1.
Zerpol®-Zero Liquid Discharge
The Zerpol" process achieves zero
discharge of liquid effluent by recycle
and reuse of treated effluents as rinse-
water. Chemical treatment of the rinse-
waters is conducted in a batch mode,
with sequential treatment in a single re-
actor for cyanide oxidation, chromium
reduction, metal hydroxide precipita-
tion, and gravity sedimentation. A high
purity rinsewater is produced by con-
densation of steam generated by a
boiler receiving a portion of these
treated rinsewaters as feed. The con-
densate is used for critical rinsing oper-
ations, and the remaining treated efflu-
ent is used for other rinsing operations.
Residual salts and solids are removed
from the system as boiler blowdown
and metal hydroxide sludge, respec-
tively.
Three installations were surveyed
which have successfully operated in a
zero liquid discharge mode for more
than 3 years. Data are reported in
Table 1.
Buoyant Media
ance
Parameter
Filter Perform -
Clarifier Filter
Zn
mean, mg
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Table 2. Zerpol" -Zero Liquid Discharge
Condensate
Parameter
Treated
Effluent
Plant A
Ca, mg/L
Mg, mg/L
Cu, mg/L
Ni, mg/L
Cr, mg/L
CN, mg/L
TDS, mg/L
TSS, mg/L
pH
Plant B
Ca, mg/L
Mg, mg/L
Cd, mg/L
Cr, mg/L
Cu, mg/L
Zn, mg/L
CN, mg/L
TDS, mg/L
TSS, mg/L
pH
Plant C
Ca, mg/L
Mg, mg/L
Cd, mg/L
Cr, mg/L
Zn, mg/L
CN, mg/L
TDS, mg/L
TSS, mg/L
pH
2.39
1.11
702*
79
0.83
216*
9553
737
9.72
8.1
5.4
12.9
1.2
18.3
13.4
3.2
16200
21
8.21
9.09
3.16
17.3
73.2
15.0
11
9833
315
6.85
0.16
0.02
47*
1.3
0.01
20*
703
3
9.46
3.29
1.34
2.74
1.71
2.79
3.25
0.5
11800
14
9.14
0.13
0.07
0.16
0.34
0.17
0.3
85
3
9.17
^Unrepresentative conditions resulting from
heating coil leak.
toluol, butanol, ethylene glycol mono
ethyl ether acetate (cellosolve acetate),
and VM&P naphtha. The solvent con-
sumption did not exceed 100 gal per
month. The recovered solvent was sat-
isfactory for reuse in this application.
Comparative data for virgin and recov-
ered solvent are provided in Table 3.
Table 3. Zerpa Solvent Recovery Charac-
terization of Recovered Solvent
As % of Total
Solvent
Compound
Toluol, %
Butanol, %
Cellosolve
Acetate, %
Naphtha, %
Virgin
Solvent
20.2
17.6
18.1
44.0
Recovered
Solvent
25.9
13.3
21.6
38.3
Conclusions and Recommenda-
tions
Three new technologies for manage-
ment of wastes in the metal finishing
industry were characterized through a
limited field sampling and analysis pro-
gram. The study objectives were con-
fined to a preliminary evaluation of the
technologies because of the constraints
on field sampling activities. Evaluation
of the processes in the specific applica-
tions selected for study may not provide
sufficient information to assess applica-
bility in all segments of the industry, but
the information developed through this
type of program provides a starting
point for general evaluation of any new
or emerging technology.
A buoyant media filtration system de-
veloped by 3M was demonstrated to
achieve compliance with federal efflu-
ent guidelines when applied instead of a
clarifier. The test system was subjected
to significant hydraulic and solids load-
ing fluctuations, and the buoyant media
filter evidenced improved stability of
operation when compared to a slant-
tube clarifier. Alteration of conventional
clarification systems to provide a buoy-
ant media filter appears to be generally
feasible, in which case the applicability
of the process would be very significant.
Three facilities surveyed have suc-
cessfully achieved zero liquid discharge
for a period in excess of 3 years using
the Zerpol" process. Reuse of treated
effluent and condensate as rinsewater
make-up did not produce problems with
product quality for the chemical condi-
tions and plating operations identified
in this report. Prior operational difficul-
ties with the boiler were reported if cer-
tain cleaners were used. Consequently,
adoption of the Zerpol*' process may
limit flexibility in selection of chemicals
in various plating and cleaning solu-
tions. The rinsewater quality was char-
acterized for the three facilities sur-
veyed. The suitability of these streams
for rinsewater make-up must be evalu-
ated on a case-by-case basis for each
rinsing operation.
Successful operation of a solvent re-
covery system for a blend containing
toluol, butanol, cellosolve acetate, and
VM&P naphtha was documented using
a Zerpa batch distillation unit. The re-
claimed solvent was acceptable as a
substitute for the virgin solvent blend.
The criteria for selecting technologies
restricted consideration to those pro-
cesses that were recently developed.
This time factor precluded examination
of long-term operating data for evalua-
tion of life cycle costs and specific long-
term operating problems. This general
limitation applies to all three of the tech-
nologies reported here.
With respect to the buoyant media fil-
tration system, extended studies to
evaluate media durability, alternative
media, particle size distribution, and al-
ternative backwash operation practices
(frequency, duration, and hydraulic
loading) would enhance system devel-
opment.
Development of a complete material
and energy balance for the Zerpol® pro-
cess would require an extended pres-
ence. A detailed examination would be
beneficial to identify energy require-
ments for boiler operation throughout
summer and winter periods. Full char-
acterization of boiler function and asso-
ciated condensate water quality cannot
be established on the basis of the lim-
ited sampling effort involved in this
study. Completion of a material balance
would also require data on sludge and
salt production over a compositing pe-
riod that corresponds with the duration
of characterization of the influent and
reuse stream.
Long-term operating data would be
required to assess maintenance and re-
pair costs for the Zerpa distillation unit.
Such data were not readily available be-
cause of the short history of operation.
The full report was submitted in fulfill-
ment of Cooperative Agreement No.
CR-810787-01-0 by the University of
Central Florida under the sponsorship
of the U.S. Environmental Protection
Agency and the American Electro-
platers' Society, Inc.
-------
John D. Dietz and Christopher M. Cherniak are with the University of Central
Florida, Orlando, FL 32816.
M. Lynn Ape! is the EPA Project Officer /see below).
The complete report, entitled "Evaluation of New and Emerging Technologies in
the Metal Finishing Industry.-" (Order No. PB 85-216 562/AS; Cost: $11.50.
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, V'A 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Water Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use S300
EPA/600/S2-85/072
0063240
LOU W TILLEY
REGION V EPA
LI3RARHN
j ST
60604
GOVERNMENT PRINTING OFFICE.1985—559-01fa/27112
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