INTERIM PHASE I REPORT
ELECTROPLATING WASTEWATER
SLUDGE CHARACTERIZATION
AES-EPA Cooperative Agreement
No. R880026-01
August 24, 1979
Revised September 12, 1979
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DISCLAIMER
This report has been reviewed by the Industrial Environmental
Research Laboratory-Cincinnati, U. S. Environmental Protection
Agency and approved for release as a prepublication manuscript.
Approval does not signify that the contents reflect the
views and policies of the U. S. Environmental Protection
Agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.
This document is provided to the gener-al public for
comment on technical merit. Comments may be returned to
A. B. Craig, Jr., Industrial Environmental Research Laboratory,
U. S. Environmental Protection Agency, Cincinnati, Ohio.
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Acknowledgments
This report is an interim report of work completed under EPA
Grant No. R880026-01 to the American Electroplaters' Society
(AES). This grant was funded by the Metals and Inorganic
Chemicals Branch of the Industrial Environmental Research
Laboratory, U. S. Environmental Protection Agency, Cincinnati,
Ohio (George Thompson, Branch Chief). The EPA Project Officer
is Fred Craig. Kenneth Coulter served as Technical Project
Director. Mr. Douglas Thomas served as AES Task Force Chairman.
Task Force members were: Dick Crain, Irv Ireland, George
O'Conner and Fred Steward. J. Howard Schumacher served as the
AES coordinator. CENTEC Corporation and CENTEC Analytical
Services, Inc., were the primary subcontractors for the sampling
and for laboratory and engineering analysis.
Please contact the Metals and Inorganic Chemicals Branch at
(513) 684-4491 for discussion of these results.
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TABLE OF CONTENTS
Section Title Page
SECTION 1
INTERIM PHASE I REPORT
INTRODUCTION 1-1
CONCLUSIONS & RECOMMENDATIONS 1-6
SECTION 2
DISCUSSION OF EXPERIMENTS
2.1 EPA EXTRACTION PROCEDURE 2-1
2.2 EXPERIMENT I - EFFECT OF pH 2-2
2.3 EXPERIMENT II - EFFECT OF pH 2-7
2.4 EXPERIMENT III - VOLUME OF EXTRACTION WATER . 2-17
2.5 EXPERIMENT IV - REPRODUCIBILITY 2-18
2.6 EXPERIMENT V - TEMPERATURE 2-22
2.7 EXPERIMENT VI - ASTM EXTRACTION PROCEDURE . . 2-22
2.8 EXPERIMENT VII - AGE OF bLUDGE 2-25
2.9 EXPERIMENT VIII - TOTAL METAL CONTENT . . . .2-26
2.10 EXPERIMENT IX - ANION CONTENT 2-27
2.11 EXPERIMENT X - X-RAY DIFFRACTION 2-30
2.12 EXPERIMENT XI - FILTRATE ANALYSIS
AND WASHING 2-30
2.13 EXPERIMENT XII - FILTRATION VERSUS
CENTRIFUGATION 2-34
2.14 OTHER RELATED STUDIES 2-35
APPENDIX A
ANALYTICAL QUALITY CONTROL A-l
APPENDIX B B-l
iii
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TABLE OF CONTENTS
(Continued)
Section Title Page
APPENDIX C
PLANT WASTEWATER TREATMENT SYSTEMS C-l
APPENDIX D
PRELIMINARY PHASE II RESULTS D-l
iv
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SECTION 1
INTERIM PHASE I REPORT
INTRODUCTION
The American Electroplaters' Society (AES) and the U.S. Environ-
mental Protection Agency (EPA) Industrial Environmental Research
Laboratory (IERL) are cooperating in a three-phase study of
sludges from electroplating wastewater treatment systems. Phase
I was designed to physically and chemically characterize repre-
sentative sludges of this type, to test their response to the
Extraction Procedure (EP) proposed by the EPA as the primary test
of the toxic nature of wastes under RCRA and to determine the
sensitivity of the variables in the EP. Phase II will involve
laboratory testing to simulate actual segregated landfill condi-
tions and the performance of electroplating sludges in that
environment. Phase III will validate the results of Phase II by
conducting field tests on actual landfills. The ultimate goal of
the study is to enable the prediction of the dissolution rate of
toxic metals in electroplating sludges in a segregated landfill
environment. This will hopefully lead to environmentally safe
landfill designs while avoiding the economic problems associated
with overdesign. This report presents the data obtained as a
result of experiments conducted during Phase I of this study, and
some Phase II results, along with conclusions based on these
results.
1-1
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As mentioned above, Phase I had three goals: (1) to character-
ize the response of representative electroplating sludges to
the Extraction Procedure (EP) developed by the EPA, (2) to phys-
ically and chemically characterize the sludges, and (3) to
determine the sensitivity of the EP to its variables.
Table I describes the experiments that were run to achieve these
goals.
The AES Task Force recommended a set of 12 waste treatment
sludges that adequately represent the electroplating industry,
along with the plant sites where the sludges could be obtained.
It was determined that the characterization of 12 sludges was
within the budget of the study, based on the proposed testing.
Table II lists the plant code and the major processes at the
plant contributing to the sludge.
During the sampling visit, an effort was made to collect readily
available information concerning plant operations and wastewater
handling techniques as they pertained to the sludges. No effort
was made to perform an in-depth plant survey or to collect ideal
samples. Where possible the sludge samples were collected as
they came out of the dewatering process, although some samples
were collected from dewatering beds and may have been several
months old. The intent was to collect samples in the form that
they would be shipped to a disposal site.
Several of the experiments conducted were intended to be screen-
ing tests to determine if further investigation would be warranted.
Insufficient data precluded firm conclusions.
1-2
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Table I
Description of Experiments
Experiment Title
I Effect of pH
II
III
IV Reproducibility
V Effect of
Temperature
VI ASTM Procedure
VII Effect of Age
of Sludge
VIII Total Metal
Content
IX Anion Content
X X-Ray
Diffraction
XI Filtrate
Analysis
and Washing
Description
Three different sludges were run at
pH = 4, 5, 6, 7, 8, 9, 10 and 11.
Two sludges were run in duplicate
to evaluate the reproducibility
of results obtained.
A few extractions were run utiliz-
ing the ASTM extraction procedures
for comparison to the EP.
One sludge will be allowed to age
for 3 and 6 month periods, then
analyzed as in Experiment II.
Anions were tested for because of
their potential impact on the
solubility of metal ions.
X-ray diffraction was run on each
of the sludge samples to identify
the crystalline structures present
in the sludge.
The initial filtrate from the EP
was analyzed to determine the
presence of toxic metals and their
impact on the results of the EP
test. Washing experiments were
run to determine the impact of
interstitial water quality on EP
results.
Effect of pH Nine additional sludges were run
at pH = 5, 7, 8, 9 and 10.
Effect of Volume One sludge was run according to
of Extraction the EP, except that 5 and 10 mis
Water of extraction water per gram of
solid were used instead of 16.
One sludge was run at a tempera-
ture of 40°C (104°F) which repre-
sents the upper extreme allowed
by the EP.
The total metal content was
determined for each sludge.
1-3
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Table I
(Continued)
Experiment
XII
XIII
Title
Filtration
versus
Centrifugation
Organic Content
Description
Filtration versus centrifugation
as separation techniques was
evaluated in this test.
TC and TOC for the sludges were
measured to indicate the potential
for biological action.
1-4
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Table II
Plant Descriptions
Plant Code Primary Plating Process
1A Segregated Zn
2A Segregated Cd
3A Zinc Plating and Chromating
4a Cu-Ni-Cr on Zn
5a Al Anodizing
6A Ni-Cr on Steel
7A Multi-process Job Shop
8A Electroless Cu on Plastic, Acid Cu, Ni, Cr
9A Multi-process with Barrel or Vibratory Finishing
10A Printed Circuits
11A Ni-Cr on Steel
12A Cd-Ni-Cu on Brass and Steel
1-5
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Twelve different sludges and slurries collected by the AES/CENTEC
sampling team were characterized to determine the aqueous leach-
ability of several metallic components. The EPA Extraction
Procedure^ (EP) was used as the primary leaching method-
ology. In the descriptions which detail the experiments of the
Phase I study, modifications to and deviation from the EP are
clearly noted. All results are presented in mg/1 unless noted.
CONCLUSIONS
Two variables were found to have a major effect on the results
obtained by the leaching procedures tested:
• The composition and amount of interstitial wastewater
present:
Many of the tested sludges with low solids concentrations
had sufficient interstitial wastewater present at such a concen-
tration so as to cause them to fail the EP, regardless of the
properties of the sludges. Sludges with high solids concentra-
tion consistently performed better in the leaching tests. In
addition, preliminary dynamic tests showed a radical reduction in
metal content of the leachate once the interstitial wastewater
\
had been flushed from the sludge. It is likely that dewatering
of low solids content sludges would greatly improve the results
of the leaching test.
(1)Federal Register, Dec. 18, 1978, pp. 58956-7, Vol. 43, No. 243.
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• The pH of the final extract:
Metal hydroxides follow a generally predictable solubility
curve with pH. When the effects of the interstitial water are
taken into consideration, the sludges tested generally followed
this relationship. Thus at a continually maintained pH of 5.0
used by the EPA extraction procedure, relatively large amounts of
metals are and would be expected to be solubilized; at values
closer to neutral or those produced by the natural alkalinity of
the sludge, greatly reduced amounts of metal are leached. In a
segregated landfill, the alkalinity of the sludges would maintain
a pH much higher than the 5.0 used to simulate the conditions in
a co-disposal situation.
There is limited data to indicate additional factors may
be important.
• Mass transfer limitations;
This effect, which is not measured by any equilibrium
type of leaching test, tends to further reduce the amount of
metals transferred to leachate in a segregated landfill.
Preliminary dynamic testing (requiring further verifica-
tion) has indicated lower metal values in the leachate than
reported by the equilibrium type of test.
(See Appendix D)
1-7
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RECOMMENDATIONS
Since continued investigation into solubilization phenomena may
provide relatively inexpensive but environmentally safe methods
for the disposal of metal finishing sludges, specifically through
the use of segregated landfills, it is recommended that:
• An•equilibrium type of laboratory test which would be
more appropriate for predicting the behavior of hydroxide
sludges in a segregated landfill should be developed.
• Dynamic testing as already planned for Phase II should be
continued.
• Field verification of these hypotheses for segregated
landfills, as planned for Phase III, should be continued.
• A rapid acceptance test suitable for use by generator and
disposal site operators is needed.
• The relationship of wastewater treatment to sludge floe
formation and subsequent leachate/elutriate generation
should be investigated.
1-8
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SECTION 2
DISCUSSION OF EXPERIMENTS
2EPA EXTRACTION PROCEDURE
Because the EPA-proposed EP is used as the basic extraction
procedure for the tests in this study, a general description of
the EP follows to assist the reader in understanding and inter-
preting the data.
A 100-gram sample (minimum) of the sludge is separated into its
component phases by either filtration or centrifugation. The
filtrate is set aside and stored at 1 to 5°C (34 to 41°F). The
solid portion is prepared for extraction by reducing the particle
size so that it will pass through a standard 9.5 mra (3/8") sieve.
After being weighed, the solids are placed in an extraction
container where 16 grams of water are added for every gram of
solids. This mixture is stirred sufficiently to assure that all
sample surfaces are continuously brought into contact with well
mixed extraction fluid and to prevent any stratification. The pH
is adjusted to 5.0 + 0.2, using 0.5N acetic acid. The total
amount of acetic acid is limited to 4 ml per gram of solid,
beyond which no more may be added. The extraction is maintained
between 20 to 40°C (68 to 104°F) for 24 hours. The mixture is
separated as before into solid and liquid components. The liquid
is diluted to a total volume equal to 20 times the weight of the
initial solid material. To this is added the original filtrate
from the raw sludge. This combined liquid is the Extraction
2-1
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Procedure Extract upon which analyses are made for toxic metal
ions.^
The sludge samples were collected in 2-gallon Nalgene™
rectangular polyethylene carboys. Upon reaching the laboratory,
the samples were stored in a refrigerator at 4°C and only with-
drawn to obtain samples for the experimental study. A represent-
ative sample for each test was secured by emptying the sludge
into a large aluminum tray, breaking up the solids into smaller
pieces (approximately 3/8") and withdrawing portions from several
sections of the sample. Slurries were thoroughly mixed prior to
sampling. The unused material was returned to the carboy and
stored in the refrigerator. The sludges collected for this phase
of the study are described in Table III.
2.2 EXPERIMENT I - EFFECT OF pH
Sludges from Plants 6A, 7A, and 9A were the first plants sampled
and were therefore selected to be characterized in the experiment
and extracted at pH 4, 5, 6, 7, 8, 9, 10 and 11. For Experiment I,
lOOg (+ l.Og) of sludge was transferred to a 2000 ml borosilicate
glass beaker and 1600 g of deionized water (D.I.) added (only
plastic and glass equipment are used in these tests). Any
lumps of solid were broken up with a plastic stirring rod.
Breaking up the lumps is a departure from the EP protocol and
may have resulted in higher metal levels in the extract. It was
done in an effort to improve the reproducibility of the experi-
ment. Filtering or centrifuging was considered unnecessary for
(1)Federal Register, Dec. 18, 1978, pp. 58956-7, Vol. 43, No. 243
2-2
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Table III
Sludge Descriptions
Plant
Initial
PH
%
Dry
Solids
Apparent
Density
(q/ml)
Particle
Density
(q/ml)
Description
1A
9.3
11
White liquid slurry,
rubbery particles
2A
9.8
6
1.08
0.76
Deep brown slurry
3A
8.7
3
1.04
1.56
Yellow-brown slurry
4A
8.5
7
1.04
1.06
Gray-green slurry
5A
7.4
17
1.01
0.81
Gray-gritty paste,
with visible water
6A
10.2
34
1.12
0.66
Black paste with
visible water
7A
7.4
15
1.24
0.90
Green-brown paste,
moist, but no visible water
8A
9.0
29
1.25
1.07
Blue-green, clay-like
material
9A
9.1
36
1.26
1.06
Gray-green hard lumps,
dry appearance and quite
compact
10A
9.0
24
1.18
2.44
Dark muddy brown slurry
11A
9.4
19
Homogenous forest green
slurry
12A
9.1
23
Dark blue-gray chunky
paste
2-3
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these sludges, based on their physical appearance. Finally, the
solids were dispersed in the water with a Tekman Company Ultra-
Turrax" homogenizer. The pH of each sample was adjusted to the
desired level with 0.5N acetic acid or 0.5N NaOH. The extractions
were made using a Phipps and Bird™ Apparatus Model 300 equipped
with borosilicate glass stirrers. All tests were run at 60 RPM.
In all experiments, this agitation was adequate to keep the
solids dispersed. The PhipFs-Bird™ Apparatus is so constructed
that up to six samples may be extracted at one time.
The pH of each solution was checked at 15-minute intervals during
the first, second, third and fourth hours. The pH remained
within +0.2 pH units of the desired value after the fourth hour
when tests were run in the pH range of 5 to 10. A pH of 4.0
could not be reached or maintained in any of the extractions. In
the case of pH 4, 50 ml of 8 percent acetic acid was added which
maintained a pH of 4.2 to 4.5 throughout the test. A pH of 11
was difficult to hold for more than several hours, but small
additions of 0.5N NaOH would maintain the level at 11.0. The
sludge-water suspension was agitated for 24 hours. The beakers
were then removed from the Phipps-Bird™ Apparatus covered with a
parafilm cover and allowed to stand and settle overnight.The
mixtures were decanted into a 1-gallon glass bottle fitted with a
2
Teflon™ lined cap. The residual slurry was centnfuged at 2300 rpm
for 30 minutes and decanted. These decants were added to the
first decant and diluted so that the final water volume was
"'"This is a departure from the proposed EP. The liquid-solids
separation can be performed immediately.
^A 0.45 micron filter would prevent carryover from decanting
but separation was very slow using this method."
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20 times the original sample weight (2000g in these three cases).
The combined solution was analyzed for the following metals:
Metals were analyzed by atomic absorption techniques using EPA
protocols. A description of the Analytical Quality Control is
given in the appendix.
Filtrates from samples of Plant 6A and 9A separated rapidly,
remained clear, and were easily decanted. Plant 7A sample
contained a colloidal suspension which did not separate and could
3
not be filtered through a #42 filter paper. These samples were
permitted to set for several days, then decanted.
In each of the three sludges, the extraction solutions at pH 4.5
were highly colored. The other extractions remained colored to
nearly the same as the original suspension.
Experiment I was run with a broad range of pH's to get a more
complete picture of the sludge's response to pH. Experiment II
was run at fewer pH levels as an economy measure and also because
the extreme pH's proved to be difficult to maintain experimentally
and thus were of limited value. The metals analysis for
Experiment I are given in Table IV. All values are in mg/1.
Because of the similarity between Experiments I and II, the
results are discussed together below.
3This was done to confirm the collordal nature of the suspension
and is not part of the EP.
Arsenic
Lead
Chromium
Silver
Barium
Cadmium
Mercury
Selenium
2-5
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TABLE IV
Sludge Characterization - pH Study
Experir ent I
(mg/1)
Proposed Hazard Limit^
0.1
0.5
0.5
Metal
Cd
Pb
Cr
Plant 6A
pH4
<0.01
.027
184
(34% Solids)
pH5
<0.01
.001
25.4
pH6
<0.01
.002
3.64
pH7
<0.01
.003
1.21
pH8
<0.01
<.001
0.05
pH9
<0.01
<.001
0.06
pHlO
<0.01
<•001
0.08
pHll
<0.01
<.001
0.16-
Plant 7A
pH4
0.60
.006
25.3
pH5
2.16
.003
0.24
(15% Solids)
pH6
0.35
.002
0.16
pH7
0.04
.005
0.50
pH8
1.21
.25
18.2
pH9
1.54
.28
24.0
pHlO
2.00
.40
29.5
pHll
1.22
.28
19.2
Plant 9A
pH4
0.04
.020
5.38
pH5
0.03
.010
0.32
(36% Solids)
pH6
<0.01
.002
0.05
pH7
<0.01
.001
0.05
pH8
<0.01
.002
0.04
pH9
<0.01
<.001
0.05
pHlO
<0.01
.001
0.06
pHll
<0.01
<.001
0.09
Note: As, Ag, Ba, Hg, and Se are at or near the detection
limits for Plants 6A, 7A and 9A
(1) As proposed in FR 43, No. 243, pp 58956.
2-6
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2.3 EXPERIMENT II - EFFECT OF pH
The conditions and procedure for Experiment II were the same as
for Experiment I. Samples from plants 1A, 2A, 3A, 4A, 5A, 8A and
10A, 11A and 12A were extracted at pH levels of 5, 7, 8, 9 and
10. The separation procedure of the slurry samples followed the
EPA proposed methodology, with the centrifuge procedure being
applied to these samples. A sample of each sludge
was placed into a centrifuge bottle and spun at 2300 RPM
for 30 minutes. The height of the solids was measured and the
centrifuging repeated until solids were no longer being separated.
The mixture was decanted and stored in a refrigerator.
The solids were extracted with 16 times their weight of D.I.
water for 24 hours on the Phipps and Bird™ Apparatus. After the
final separation of solids and liquids, and dilution to volume,
the retained initial decant, which was stored in the refrigerator,
was added to the solution. The metals listed in Experiment I
were analyzed for in these solutions.
The pH of each solution was checked each hour after the initial
pH adjustment. In nearly all cases the pH level remained constant
within +0.1 units of the desired pH throughout the 24-hour
test.
Tests run on Plant 5A sludge at pH's of 7 to 10 contained a
colloidal suspension which cou^d not be filtered through #40 or
#42 paper. The quantity of colloidal suspension increased with
pH.
4
This was done to confirm the collordal nature of the EP and is
not part of the EP.
2-7
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The results from Experiment II are presented in Table V.
The concentration levels of metals extracted from the sludges were
highly dependent upon the pH of the extraction, as is clearly
presented in Tables IV and V and Figures 1 through 12. As a
general rule, the metal concentrations followed what would be
expected based on general chemistry, i.e, most metals were highly
soluble at low pH's and decreased in solubility as pH increased,
while some metals reached a minimum and began increasing in
concentration again.
Several of the sludges have one or two metal concentration levels
in the EP extract liquid higher than the hazardous limits proposed
by EPA. Chromium is the metal most frequently observed over the
limit; however, there is some confusion over the type of chrome
+ 3 +6
intended to be controlled. Chromium was found as Cr , Cr ,
+ 2
and possibly Cr in different sludges. The standards on Cr under
RCRA are stated to be based on the EPA National Interim Primary
+12
Drinking Water Standards. Experiment X indicates Cr is possibly
present in sludge from Plant 3A. Qualitative tests for Cr
indicated its presence in sludges from Plants 2A and 4A onlv.
Both of these sludges are low solids (6 and 7 percent, respectively)
and results from Experiment XI indicate that there is enouah Cr
in the supernatant water of the sludge to account for the levels of
Cr found in the EP extract liquid from Plant 4A. In Plant 2A the
2-8
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TABLE V
Effect of pH
Experiment II
Proposed Hazard
Limit
0.5
0.1
0.5
0.5 0.02 0.5
Metal
Cr
Cd
Pb
As Hg Ag
1A (11%
Solids)
PH
5
1.22
0.23
0.041
0.073 <0.01
PH
7
<0.05
0.01
<0.001
0.076
PH
8
<0.05
<0.01
<0.001
0.035
PH
9
<0.05
<0.01
<0.001
0.114
PH
10
<0.05
<0.01
.007
0.082
2A ( 6%
Solids)
PH
5
1.89
126
< Q.Q 01
0.005 <0.01
PH
7
1.68
1.42
PH
8
1.85
0.48
PH
9
1.41
0.20
PH
10
1.74
0.25
3A ( 3%
Solids)
PH
5
85.0
6.00
0.009
PH
7
10.4
0.13
0.045
PH
8
17.2
0.04
0.146
PH
9
20.6
0.02
0.020
PH
10
34.2
0.04
0.042
4A ( 7%
Solids)
pH
5
21.8
0.038
.02
PH
7
10.8
0.005
.02
PH
8
15.7
0.012
.02
PH
9
25.4
0.011
.02
PH
10
42.2
0.008
.02
5A (17%
Solids)
PH
5
<0.01
<0.001
<0.01
PH
7
0.18
<0.001
PH
8
3.67
0.031
PH
9
4.28
0.067
pH
10
1.58
0.005
8A (29%
Solids)
PH
5
400
0.032
0.0450 .02
pH
7
1.69
<0.001
0.0395 .01
pH
8
0.86
<0.001
0.0166 .01
PH
9
1.34
<0.001
0.0075 .01
PH
10
0.30
<0.001
0.0047 <.01
10A (24%
Solids)
PH
5
0.12
0.88
PH
7
<0.05
0.075
PH
8
<0.05
0.055
PH
9
<0.05
0.082
PH
10
<0.05
0.058
-Continued
2-9
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TABLE V - Continued
Effect of pH
Experiment II
Proposed Hazard Limit 0.5 0.1 0.5 0.5 0.02
Metal Cr Cd Pb As Hg
<0.01 0.004 0.035
0.002 0.006
0.002 0.039
0.002 0.048
0.002 0.052
268 0.031 <0.001
1.65 0.004
0.46 0.004
0.27 0.002
0.34 0.002
11A
(19%
Solids)
pH
5
4.22
PH
7
0.18
PH
8
0.19
pH
9
0.46
PH
10
0.35
12A
(23%
Solids)
pH
5
4.85
PH
7
0.38
pH
8
0. 38
PH
9
0.26
pH
10
0.56
Blanks, Ba, and Se were at or below detection limits.
2-10
-------
0.30
PLANT NUMBER 1A 1\% SOLIDS
0.25
^PROPOSED HAZARD LIMIT
0.20
at pH5
Cd = 0.1 mg/I
cn
E
Refer to Table V for
Concentration at pH 5.
A Cd
# As
~ Pb
*Cd
cO-,
0.05
13 \k
it
6
B
5
10
12
8
7
pH
Figure I
2.0
5
PLANT NUMBER 2A 6% SOLIDS
.0
*PROPOSED HAZARD LIMIT
Refer to Table v for
Concentration at pH 5.
0.5
A Cd
o Cr
3
k
6
10
13 H
11
12
9
7
5
PH
Figure II
2-11
-------
O Pb
A Cd
20
PLANT NUMBER 3A 3% SOLIDS
Ol
E
10 -
PROPOSED HAZARD LIMIT
at pH5
Cd = 0.1 mg/Jl
Refer to Table V for
Concentration at pH 5.
0.20
0.05
11
h
12
5
6
10
8
7
9
pH
Figure III
O Cr
~ Pb
o>
E
PUNT NUMBER i»A 7% SOLIDS
PROPOSED HAZARD LIMIT
at pH5
Refer to Table V for
Concentration at pH 5
0.05
0.03
0.01
8
7
9
6
10
12
11
pH
Figure IV
2-12
-------
PLANT NUMBER 5A M% SOLIDS
PROPOSED HAZARD LIMI1
mg/l at pH5
cn
E
o Cr
~ Pb
(Refer to Table V for
\ Concentration at pH 5.
0.05
h
6
8
7
5
12
10
PH
Figure V
~ Pb
*Cd
0.08
O)
0.06
PLANT NUMBER 6A lk% SOLIDS
0.04
PROPOSED HAZARD LIMIT
0.02
0.01
Refer to Table V for
Concentration at ptt 5.
0.002
8
6
7
5
10
11
12
PH
Figure VI
2-13
-------
.0
.8
.6
.k
PLANT NUMBER 7 A 15% SOLIDS
.2
^PROPOSED HAZARD LIMIT
.0
.8
O Cr
A Cd
~ Pb
. 6
*Pb,
A
.2
Refer to Table V for
Concentration at pH 5
5
8
4
6
9
12
13
11
10
pH
Figure VII
PLANT NUMBER 8A 23% SOLIDS
^PROPOSED HAZARD LIMIT
Refer to Table V for
Concentration at pH 5.
O)
E
~ Ag
A Hg
0.05
0.03
~ Pb
0.01
k
6
S
11
12
7
3
10
pH
Figure VIII
2-14
-------
A Cd
~ Pb
o Cr
0.06
0.05
PLANT NUMBER 9A 362 SOLIDS
cn
E
PROPOSED HAZARD LIMIT
0.03
PROPOSED HAZARD LIMIT
0.02
Refer to Table V for
Concentration at pH 5.
A
0.01
13 1*»
6
8
k
5
9
12
11
10
PH
Figure IX
0.30
PLANT NUMBER 10A SOLIDS
0.60
*PR0P0SED HAZARD LIMIT
0.20
O Cr
~ Pb
0.075
0.05
0.025
Refer to Table V for
Concentration at pH 5
5
8
6
9
12
10
-------
0.30
PLANT NUMBER 11A ]S% SOLIDS
0.20
PROPOSED HAZARD LIMIT -
cn
£
• As
~ Pb
0.06
Refer to Table V for
Concentration at pH 5.
0.02
£3i
it
8
13
6
12
10
5
7
pH
Figure XI
0.50
Refer to Table V for
Concentration at pH 5.
0.30
"cn 0.20 -
PLANT NUMBER 12A 23% SOLIDS
PROPOSED HAZARD LIMIT
0.10 -
0.05
0.0k
0.03
~ Pb
0.02
0.01
11
6
7
8
13
12
10
k
pH
Figure XII
2-16
-------
levels of Cr in the supernate are high enough to show results
over the proposed limits. Because of the soluble nature of
Cr+6, it is doubtful that any significant quantities of it will
be found in the solid portion of the sludge. One conclusion
to be drawn from this is that some electroplating sludges will
produce EP extract liquids with Cr levels over the proposed limit
due to the Cr in the liquid and not in the solid portion of the
sludge. The same argument holds for Cd. The distinction is
important because in a landfill the liquid portion flushes out
with the first portion of the leachate and inclusion of this is
not representative of long-term leaching from the sludge.
Filtrate analysis will be discussed further under Experiment XI.
2.4 EXPERIMENT III - VOLUME OF EXTRACTION WATER
The EP states that the solids are to be extracted with a quan-
tity of water which is 16 times the weight of the sample. In
this experiment, a sludge sample from Plant 7A was extracted with
a quantity of water that was five and ten times the weight of
solid, thus increasing the solids to water ratio. The samples
were extracted at a pH of 5, 7, 8, 9, and 10. After extraction
the EP extract liquid was diluted to 20 grams of liquid per gram
of solids in the waste.
If the extraction were limited by solubility, the volume of ex-
traction water should have a directly proportional effect on the
metal concentration levels. That is, if the extraction ratio was
5:1, one would expect lower metal levels than at 16:1 after the
extract liquid is diluted to its final 20:1. In contrast, this
2-17
-------
experiment showed that at pH 5 the volume ratio of extraction
water has no or very little impact on the amount of metals
extracted. At higher pH's the 16:1 ratio leached dramatically
higher metals values than the lower ratios — greater than can be
accounted for by the final dilution to 20:1. One possibility is
that at higher pH's the lower extraction ratios do not provide
adequate liquid-solid contact to effect equilibrium during the
24-hour extraction period. At pH = 5 the same amount of metal is
being extracted without regard for the extraction ratio. It
would be tempting to conclude that all of the leachable metal is
being extracted at pH = 5 except that we know this is not the
case. A satisfactory explanation of these phenomena has not been
developed. The results are given in Table VI.
2 *5 EXPERIMENT IV - REPRODUCIBILITY
Solid sludges from Plants 7A, 9A and slurry from Plant 2A were
extracted at pH 5, 7, 8, 9 and 10, and the resultant solutions
analyzed for those metals which were found in measurable amounts
in Experiment I. These data are given in Table VII (Plants 7A,
9A and 2A). Samples of the EP extraction liquid for two plants
were submitted to two independent laboratories for verification
of CENTEC's analytical accuracy. Both laboratories reported
excellent concurrence, verifying the accuracy and reproducibility
of the analytical results. Samples of the sludges were sent to
Oak Ridge National Laboratories for duplicate EP's but no results
have been received to date. Table VIII illustrates the independent
laboratory confirmation of analytical results.
2-18
-------
TABLE VI
Volume of Extraction Water
Experiment III
Plant 7A CI5% Solids)
Cmg/1)
PH
Dilution
Pb
Cr
Cd
5
5
<0.001
0.65
1.91
10
<0.001
0.24
2.22
16
0.003
0.24
2.16
7
5
<0.001
0.32
0.02
10
<0.001
0.09
0.02
16
0.005
0.50
0.04
8
5
0.003
1.84
0.11
10
0.005
2.58
0.11
16
0.25
18.2
1.21
9
5
0.004
1.68
0.08
10
<0.001
1.24
0.07
16
0.28
24.0
1.54
10
5
0.03
4.12
0.28
10
0.008
3.99
0.22
16
0.40
29.5
2.00
2-19
-------
TABLE VII
Reproducibility of EP*
Experiment IV
(mg/1)
Cd Pb Cr
Plant 2A
Run 1
Run 2
Run 1
Run 2
Run 1
Run 2
pH 5
126
114
<.001
.002
1.9
4.7
pH 7
1.42
2.75
<•001
<.001
1.7
1.3
pH 8
.48
.28
<.001
<.001
1.8
1.0
pH 9
.20
.18
<.001
<. QQ1
1.4
1.2
pH 10
.25
.22
<.001
<.001
1.7
1.5
Plant 7A
Run 1
Run 2
Run 1
Run 2
Run 1
Run 2
pH 5
2.16
1.26
.003
<.001
.24
.42
pH 7
.04
.10
.005
<.001
.50
1.64
pH 8
1.21
.82
.25
.13
18.2
12.0
pH 9
1.54
-
.28
.15
24.0
-
pH 10
2.0
.90
.40
.27
29.5
21.0
Plant 9A
Run 1
Run 1
Run 2
Run 1
Run 2
pH 5
.03
.010
<.001
.32
.48
pH 7
<.01
.001
<.001
.05
.08
pH 8
<.01
.002
<.001
.04
.08
pH 9
<.01
<.001
<.001
.05
.08
pH 10
<.01
.001
<.001
.06
.15
*The EP was duplicated in—house with split samples sent to
Oak Ridge. The ORNL data is not available yet. The elutriate
from duplicate in^house EP's was sent to separate laboratories
for confirmatory analysis.
2-20
-------
Table VIII
Experiment IV
Independent Laboratory Confirmation
of Analytical Results*
Plant CENTEC
7 A Cd 0.3 5
Cr 0.16
Pb 0.002
8A Cr 1.69
Hg 0.0395
Pb <0.001
LAB 1 LAB 2
Run 1 Run 2
0.36 0.36 0.35
0.18 0.18 0.23
0.005
1.68 1.70 1.55
0.0016 0.0017
0.001
*All results in mg/1
2-21
-------
The approximate reproducibility of the significant metal ion
concentrations Irased on CENTEC's testing are: Pb + 13 percent,
Cd + 30 percent, and Cr + 25 percent. These values represent the
combined experimental and analytical variations of two experiments.
2 .6 EXPERIMEIST V - TEMPERATURE
All of the preceding experiments were made at room temperature,
22°C + 1.0°C. To determine if temperature influenced the solu-
bility of tie metal ions, an extraction of Plant 9A solid sludge
was made a; 40°C at a pH of 5, 7, and 8. These pH levels were
chosen because the data from Experiment I indicated that the
metals are at their highest concentrations at the lower pH
levels.
The sludge was prepared as described in Experiment I. The
beakers were immersed in a water bath maintained at 40°C (+
l.CC). Results are given in Table IX. Temperature appears to
have very limited impact on the results over the 18°C range
tested.
2.7 EXPERIMENT VI - ASTM EXTRACTION PROCEDURE
Sludges from Plants 7A and 9A were extracted following the ASTM
extraction procedure. Plant 7A sludge was extracted with D.I.
water, and Plant 9A sludge extracted both with D.I. water and the
acetic acid and sodium acetate buffer solution.
Results from this experiment are presented in Table X, along with
relevant data from Experiment I.
2-22
-------
TABLE IX
Temperature Study
Experiment V
(mg/1)
Plant 9A (36% Solids)
Pb Cr
22°C - pH 5 0.013 0.32
pH 7 <0.001 0.05
pH 8 <0.001 0.04
40°C - pH 5 0.003 0.10
pH 7 <0.001 0.19
pH 8 <0.001 0.24
2-23
-------
TABLE X
The ASTM Leaching Test 1
Experiment VI
(mg/1)
Proposed Hazard Limit 0.10 0.50 0.50
Metal Cd Pb Cr
Plant 7A
ASTM (pH-7) (D.I.Water) 0.03 0.001 0.63
Experiment I (pH-7) 0.04 0.005 0.50
E. P. (pH-5.0) 2.16 0.003 0.24
Plant 9A
ASTM (D.I. Water)
(pH-9.2) - <0.001 0.04
Experiment I (pH-9.0) <0.01 <0.001 0.05
ASTM (Acetic Acid)
(pH-4.5) - <0.001 0.12
E. P. (pH-5.0) 0.03 0.010 0.32
2-24
-------
The ASTM extraction procedure is considerably different from the
EPA EP. Any reasonably sized sample of sludge can be used in the
extraction. The sample is weighed without being separated and
four times this weight of water is added for the extraction. The
container is capped, shaken for 48 hours, allowed to separate and
then decanted. The decant is used for toxic metals analyses. A
second test uses a pH 4.5 water, buffered with acetic acid and
sodium acetate; otherwise, the test is the same. No pH mainte-
nance of the extraction mixture is attempted.
The pH's shown for the ASTM tests indicate the natural pH of the
extraction. The test from Experiment I which had the closest pH
to the ASTM test is shown for comparison. For both plants the
results from Experiment I and the ASTM tests were very similar.
The results of the EP are also shown for comparison. The ASTM
extraction done on Plant 9A with the buffered extraction water
shows dramatically different results from the EP because the pH
is not maintained on the ASTM test. While the EP is designed to
simulate the hostile environment of a municipal landfill, the
non-pH regulated procedure more closely resembles the environment
of a segregated hydroxide landfill where only hydroxides or
carbonates are stored and no acid environment exists.
2.8 EXPERIMENT VII - AGE OF SLUDGE
A lOOOg sample of Plant 7A sludge has been set aside in an open
beaker to age for several months. Extractions at pH 5 and 7
2-25
-------
were run on a portion of the sample after 3 months and the tests
will be run again at 6 months. The results at 3 months were
rather dramatic as illustrated below:
Plant 7A
Cd
Pb
Cr
pH 5
Fresh
2.16
0.003
0.24
Aged
0.30
0.002
<0.05
pH 7
Fresh
0 .04
0 .005
0.50
Aged
0 .01
0 .001
0.15
The most
evident
change i
due to aging was in the dryness
of the
sample.
One explanation
for the drop
in leachability of
the
toxic metals may
be that
some form of
curing took place
during
the drying process which structurally tied up the metals making
them unavailable for dissolution. Further testing on other
sludges is necessary before firm conclusions can be made.
2.9 EXPERIMENT VIII - TOTAL METAL CONTENT
Varying quantities of the several sludge samples were oven dried
to constant weight at 105°C to determine the percent dry solids.
These dried solids were crushed and ground to a fine powder and
retained in plastic Lab-Tech™ sample bottles. One gram samples
were treated with aqua-regia, heated to drive off the nitrogen
oxide, and diluted with water. Only two of the twelve samples
were completely solubilized. The solution was filtered and the
filtrate diluted to 150 ml. An aliquot of these solutions were
analyzed for metals. All samples were analyzed for Ba, Cr, Cd,
As, Ag, Hg, Se, and Pb; however, the analyses of the dry solids
are incomplete. These data are reported for information and
2-26
-------
calculation purposes only. The metal analyses of the solids are
given in Table XI.
Because values for chromium were found in every sludge, a regres-
sion analysis was run on chromium to determine if a correlation
existed between the amount of Cr in the dried sludge and the
amount measured in the EP extract liquid (pH = 5). The correla-
tion was R = 0.77, which indicates a very strong relationship.
This may or may not hold for other metals (more data is needed)
but the implication is that the more metal there is in the
sludge, the higher will be the levels found in the EP extraction
liquid.
2.10 EXPERIMENT IX - ANION CONTENT
Separate samples of the dry solids were taken for anion analyses
to determine the presence of chlorides, sulfates, nitrates,
nitrites, and total phosphorous. Chlorides were determined by
the Volhard Titrimetric method using silver nitrate; sulfate by
the Barium Sulfate gravimetric method; and the nitrogen and
phosphates by the Auto-Analyzer procedure. Nitrogen was deter-
mined as a diazo compound and phosphate as the phosphomolybdenum
complex. Anions present in each of the sludges are shown in
Table XII as a weight percent of the dry solids.
Several attempts were made to determine the alkalinity of the
electroplating sludges using the potentiometric technique on the
aqueous fraction of the sample. As expected, due to the buffer-
ing capacity of the sludge, no meaningful value for alkalinity
could be obtained.
2-27
-------
TABLE XI
Analysis of Dry Solids
Experiment VIII
(% by wt.)
Plant
(% Solids)
Pb
Cr
Cd
6a
1A
11
*
.02
*
~
2a
6
*
6.20
2.20
*
3A
3
1.00
6.50
0.11
0.03
4A
7
*
0.05
ND
0.06
5A
17
*
0.17
ND
*
6A
34
*
1.40
-
-
7a
15
0.03
2.50
0.15
-
8A
29
0.02
13.7
ND
*
9A
36
*
0.57
-
*
10A
24
0.17
0.35
*
*
11A
19
0.09
7.92
*
0.03
12A
23
0.03
4.89
0.05
0.01
* Detected but <0.01%
ND - Not Detected
Ag, As, Hg detected but <0.01%
Se was detected at Plants 11A and 12A but <0.01%
2-28
-------
TABLE XII
Anion Analysis
Experiment IX
(Weight
percent of dry solids)
Plant
CI"
so4=
N02+N03 (as N)
P
2A
3.35
7
0.09
0.006
3A
1.1
1.27
4A
1.85
2.25
5A
0.169
0.007
6A
<0.1
-
0.001
<0.001
7A
<0.1
0.15
0.004
0.002
8A
0.08
5
9A
<0.1
3
<0.001
0.005
10A
0.6
7
2-29
-------
2.11 EXPERIMENT X - X-RAY DIFFRACTION
X-ray diffraction was utilized in the identification of the
chemical compositions of the crystalline species in the dry
solids. They were determined by the Chemistry Department of
North Carolina State University, Raleigh, North Carolina.
These data are given in Table XIII. Amorphous materials were
present in all of the sludges. The electron microprobe indicates
the presence of metals in the order of the amount present. This
test was run to verify qualitatively the results of the dry
metals analyses. No unexpected results were obtained from this
experiment.
The apparent and particle density of the electroplating sludges
were also determined. The apparent densities were determined on
the "as received" sample by weighing a 500 ml sample. In the
case of the slurries, a well-mixed sample was poured into a 500 ml
graduated cylinder; for the solids, the material was pushed
into a graduated cylinder, which had been cut off at the 50 ml
mark, and then weighed.
The particle density was determined on a dried and crushed powder
using a pycnometer with methylene chloride as the reference
solvent.
Data are given in Table III.
2.12 EXPERIMENT XI - FILTRATE ANALYSIS AND WASHING
Considerable interest has been expressed as to how much of the
soluble toxic metals are contained in the supernatant liquid of
2-30
-------
TABLE XIII
Identification of Dry Solids
Experiment X
Electron Microprobe*
Sample # X-Ray Diffraction (Elements lighter than Mg not read)
2A NaCl CI, Cr, Fe, K, Zn, P, S
3A CrO Cr, Fe, Zn, Sn, Ca, Cu, CI, S
4A CaCC>3,some SiC>2 Ca, Cr, Ni, Cu, Si, Fe, S, Cl
5A Amorphous P, Ca, Al, Fe, Ni, Cr, Cu, Si
6A si02' CaC03' a12°3 Ca' S^' Fe' Cr' Al' N'*'' S
7A Amorphous Zn, P, Cr, Fe, Ca, Ni
8A CaS04, some CaC03 Ca> Qx^ CUf si
9A CaC03 Ca, Si, Fe, Ni, Al, Cl, Zn, K, Cr
10A
CaCO^(synl#CaS04•0.5H20 Ca, Cu, S, Sn, Cr, Fe, Si
* In order of the amount present
2-31
-------
the sludge. The following experiments were run to determine
these metal levels and also to determine the impact of inter-
stitial water quality on EP results.
Approximately lOOg of slurry were centrifuged. The supernatant
layer was separated and analyzed for metals present in measurable
concentrations.
Similarly, for solid samples, a weighed amount of solid sludge
was mixed with an equal weight of water, thoroughly agitated, and
then centrifuged. The liquid layer is separated and treated as
the slurry described above. The data is given in Table XIV.
As stated earlier, many of these filtrates have metal levels high
enough by themselves to cause the EP extract liquid to have metal
concentration over the proposed hazard limits. For example,
Plant 2A has 4.08 ppm Cr in its filtrate, and has only 6 percent
solids in its sludge. If 7 5 grams of water are removed before
the extraction, leaving 25 grams of "solid" sludge, the extraction
liquid would have 500 grams of water. The 75 grams of supernatant
water contain 0.306 mg of Cr. When diluted by 575 grams of water
(when the filtrate and extract are combined), the EP extract
liquid would have a Cr concentration of 0.53 ppm— over the hazard
limit—without anything being extracted from the solid. This
would occur any time there is a low solids sludge and a super-
natant water with metal concentrations of a few ppm.
Sludges from Plants 11A and 12A were not collected in time for
filtrate analyses to be conducted; however, analyses were run
on the effluents from these two plants and are presented in
2-32
-------
Table XIV
Plant
Filtrate Analysis
Experiment XI
(mg/1)
Cr Pb
Cd
2A
•
o
00
<0.001
0.33
3A
47.5
0.014
0.01
4A
1.52
<0 .001
5A
<0.05
6A
0.47
7A
0 .09
0.22
8A
0.30
9A
0.04
10A
0.12
0.50
Proposed
Hazard
Limit 0.50 0.50 0.10
Plant Effluent
Plant Cr Cd Pb Ag As
11A 1.76 <0.01 0.002 0.01 0.017
12A 1.22 2.02 0.001 0.09 0.003
2-33
-------
Table XIV. These effluents should be essentially the same as
the interstitial water.
Experiments being run on washed sludges are incomplete and there
is insufficient data to draw any conclusions from these experi-
ments. Further work will be done on the effect of sludge washing
on EP results in this study.
While concentrations and percents are very important in this kind
of study, it may be illustrative to present some of the data in
physical amounts. The numbers below represent the actual amounts
of chromium present in the sludge solids, the initial filtrate,
and the extract liquid from an extraction run at pH 7. The
values are based on a 100 gram sample.
Plant 2A; Component
Cr
Dry Solids 770.00 mg
Filtrate 1.00 mg
Extract 3.20 mg
Extract Percent of Total 0.5 percent
These numbers indicate that, even with an aggressive EP type of
extraction at pH 7, very little material is being solubilized.
2.13 EXPERIMENT XII - FILTRATION VERSUS CENTRIFUGATION
The EP method gives two methods for separating the solids and
filtrate prior to and after the extraction procedure; namely,
filtration through a 0.45 micron filter or centrifuging followed
by decantation. The EP extract liquid from Plant 10A at pH
2-34
-------
values of 5 and 7, which were centrifuged and decanted, were
filtered through a 0.45 micron filter. The analysis of the
decanted and filtered material and the non-filtered material are
presented in Table XV. The differences in results are greater
than analytical error can account for, and in this case filtering
makes the difference between failing and passing the EP. More
data are needed in this area to form a firm conclusion.
The TOC and TC of the sludges were measured to determine the
organic levels present. Carbon is not unexpected in electro-
plating sludges because activated carbon is commonly used
to purify plating baths and paper is frequently used as a sludge
dewatering media. This experiment was conducted to verify that
organic carbon is present only in very low levels. The data from
this experiment are presented in Table XVI, and do confirm the
low levels expected to be present.
2.14 OTHER RELATED STUDIES
As each set of electroplating sludge samples arrived at the
laboratory, a representative portion was transferred to a plastic
container and sent to:
Mr. Michael Naskarinck
Oak Ridge National Laboratory
P.O. Box X
Oak Ridge, TN 37838
Sludge samples from Plants 2A, 6A, 7A and 9A were shipped May 10,
1979, and from Plants 3A, 3B, 4A, 5A and 8A on June 4. The
sample from Plant 10A was shipped on July 9, 1979. As yet,
no information has been received from the Oak Ridge office. This
2-35
-------
TABLE XV
Comparison of Centrifugation vs Filtration
Experiment XII
Plant 10A (24% Solids)
(mg/1)
Sample Pb Cr
PH
5 Centrifuge
0.88
0.12
Filter
0.38
<0.10
PH
7 Centrifuge
0.08
<0.05
Filter
0.01
<0.05
2-36
-------
TABLE XVI
Organic Content
Experiment XIII
Plant Code TOC % TC %
2 .04 .08
3 .17 .34
4 .32 .57
5 .26 .31
6 3.06 3.96
7 1.24 1.12
8 .14 .27
9 3.22 3.16
10 .53 .98
2-37
-------
facility plans to apply the EP method and analyses to this group
of samples.
2-38
-------
APPENDIX A
ANALYTICAL QUALITY CONTROL
All sample preparation and analysis were performed in accordance
with those procedures set forth by the EPA ("Methods for Chemical
Analysis of Water and Wastes," 1974). This includes the use of
high quality deionized water for samples, blanks and standards;
adequate glassware cleaning procedures, the use of Ultrex'" acids
for wet digestion, and subsequent analysis via flame, cold vapor
(Hg), and furnace AAS.
Ten percent of all samples submitted for analysis were analyzed
in duplicate; an additional 10 percent were spiked. These results
were used to compute precision and accuracy data which was com-
pared to previously generated analytical control data for each
element analyzed. Trouble-shooting was performed if results did
not fall within acceptable limits.
Detection Limit
(mg/1)
Ag
Ba
Cr
Mn
Pb
Zn
0.01
1.00
0.05
0.10
0.001
0.01
As
Cd
Cu
Ni
Se
0.001
0.01
0.01
0.10
0.005
Hg
0.0005
A-l
-------
APPENDIX A (Continued)
Glassware Cleaning Procedure
1. Remove all loose dirt and foreign material with several
tap water rinses.
2. Remove visible solids by scrubbing with detergent and
hot water. Rinse with hot water three times.
3. Rinse with "No-Chromex" (concentrated H2so4 saturated
with ammonium persulfate). Rinse with cold tap water.
4. Rinse with (1-1) HNO^. Rinse with tap water.
5. Rinse with (1-1) HC1. Rinse with tap water.
6. Rinse at least four -times with D.I. water.
A-2
-------
APPENDIX B
12
11
10
a 5
a
3
2
0 L
Mg
+ 2
Lanthanides (R+^)
Cu+2, Cr+3
UO+2
Al+3
In+3, Th+4
Ga+3/ Hg,+2
Ce+4
Sn+2, Fe+3, Zr+4
T1
+3
+2
ca+2
Hg+2
Zn
Co+2, Ni+2
Pb+2
Be+2
Decreasing
basicity
Basicities of metal ions in terms of precipitation pH
values for hydrous oxides and hydroxides.
Re: Inorganic Chemistry - 1957, T. Moeller - p. 502,
John Wiley and Son, Inc.
B-l
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APPENDIX C
PLANT WASTEWATER TREATMENT SYSTEMS
1A No information available.
2A Lancy Integrated Treatment System treating up to 2640 gph.
Settling but no dewatering. NaOH is used as the precipi-
tating agent.
3A Automatic flow-through system with NaOH used for precipita-
tion. Sludge is dewatered by centrifuge. System treats
up to 7000 gph.
4A This plant has a finalizer automatic treatment system with
some evaporative recovery on chrome. Lime is used for
precipitation. Capacity of 35,000 gpd.
5A A vacuum filter is used but no other information is
available.
6A This plant utilizes lime from its vibratory finishing
for precipitation. A paper vacuum filter is used for
dewatering. The system handles 28 gpm.
7A NaOH is used to precipitate metals with a flow rate
of 190 gpm. Dewatering is accomplished with sand beds.
8A This plant treats 80,000 gpd using lime for precipitation.
Sludge is dewatered with an OMI filter.
9A Wastewater at this plant is treated with aluminum sulfate
and calcium chloride before being precipitated with NaOH.
C-l
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APPENDIX C (Continued)
Dewatering is accomplished with an automatic plate and frame
filter. The system has a capacity of 150,000 gpd.
10A This plant has five segregated treatment systems which
sometimes run in series. The basic precipitation chemical
is lime. The main system handles 3300 to 5400 gph. De-
watering is by gravity thickening.
11A A Lancy Integrated System is used here with a dewatering
bed.
12A This plant uses lime for precipitation and a pressure
filter for dewatering.
C-2
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APPENDIX D
PRELIMINARY PHASE II RESULTS
SUMMARY
The initial results from Phase II testing are interesting and
potentially very important. The data are presented below in
tabular form and graphically in Figure D-l. The numbers indicate
that the Cr in Plant 2A sludge is rapidly rinsed away and therefore
was probably present primarily in the supernatant and interstitial
waters, not precipitated in the sludge. Sludges from Plants 4a,
6A and 8A, while showing very high EP (pH = 5) levels for Cr,
leached very little during the tests. While Phase II is just
beginning, this data does indicate that electroplating sludges in
a segregated environment have little tendency to leach Cr after
initial flushing.
Dynamic Testing
Preliminary Results
Cr mg/1
EP
Plant Results 24 Hours 48 Hours 72 Hours 5th day 1 week 2 weeks
2A
1.89
6.5
0.18
0.77
0.29
0.25
0.08
4A
21.8
0.58
0.25
0.20
0.19
0.14
0.15
6A
184.0
0 .10
0.05
<0.05
<0.05
<0.05
0.12
8A
400.0
<0.05
0.10
0.05
<0.05
0.08
<0.05
10A
0 .12
0.05
-
0.04
—
—
—
After being leached for 24 days, the sludges were subjected to an
extraction using the EP equipment, but DI water was used with no
pH maintenance. The results are shown below, along with original
D-l
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PLANT
CODE
Figure D-I, Dynamic Testing of Chromium
Versus Days
D-2
-------
EP results for comparison. Note that these equilibrium extrac-
tions of washed sludges yield far lower concentrations than the
EP, but higher results than dynamic testing.
Cr
Cd
Pb
Final
Original
Original
Original
Plant
PH
Washed
EP
Washed
EP
Washed
EP
2A
8 .2
0 .38
1.89
0.19
126.0
0 .39
<0.001
4A
9.9
0.48
21.8
<0.01
-
0.06
0 .038
6A
10.4
0 .38
25.4
<0.01
-
0.03
0 .001
8A
9.5
0.70
400. C
<0.01
-
0.02
0 .032
10A
10.5
0.12
0.12
<0 .01
-
0.06
0 .88
Metals in mg/1
TEST DESCRIPTION
Figure D-2 illustrates the equipment that will be used in Phase II
dynamic testing. Approximately 0.75 inch of sludge is weighed
into the funnel and DI water is allowed to percolate through.
The leachate is tested for metals on days 1, 2, 3, 5, 7 and every
seventh day thereafter. Conductance and pH are also measured at
this time. The samples are actually composited between test
periods, i.e., the sample on day 14 represents leachate collected
for the previous 7 days.
Note that the results shown above were derived using equipment
that was similar to the above apparatus but allowed some overflow.
While this introduces a possible error, the data is indicative of
the dynamic behavior of the leaching. More data will follow from
further testing without overflow.
D-3
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VARIABLE
HEAD
5 gal DEI ONIZED
WATER
COVERED TOP
WATER
SLUDGE
VACUUM
6
DYNAMIC TESTING APPARATUS
Figure D-2
D-4
•fr U.S. GOVERNMENT PRINTING OFFICE: 1970 OBO-O03/7O#
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