United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, Ohio 45268
Research and Development
EPA/600/S2-90/055 Mar. 1991
Project Summary
Characterization and
Treatment of Wastes from
Metal-Finishing Operations
The report summarized here details
activities associated with characterizing
and treating metal-finishing wastes to
support the U.S. Environmental Protec-
tion Agency's (EPA) development of
treatment standards for regulations
restricting land disposal of hazardous
wastes. It includes information on the
waste generators' manufacturing and
wastewater treatment plant operations,
the chemical composition of the untreat-
ed wastes, and performance data gener-
ated during bench- and pilot-scale
testing. The treatment technologies
tested were alkaline chlorination, wet-air
oxidation (WAO), ultraviolet light/ozona-
tion (UV/Os), electrolytic oxidation, stabi-
lization/solidification (S/S), and metals
precipitation. WAO bench- and pilot-
scale tests indicated significant cyanide
destruction; whereas, UV/O3 provided
partial cyanide destruction but essen-
tially no iron cyanide destruction.
Cement proved to be the most effective
S/S binder for metals.
This Prefect Summary was developed
by EPA's Risk Reduction Engineering
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
The Resource Conservation and Recov-
ery Act (RCRA) Waste Codes F006, F007,
F008, F009, F011, F012, and F019 are de-
fined in Table 1. The table also presents a
description of each waste, the basis for list-
ing, the waste generators) sampled, the
technology evaluated, and the scale of the
evaluation.
Cyanide Chemistry, Analysis,
and Toxicity
The stability and toxicity of the various
forms of cyanide and analytical methods.for
determining cyanide are important to under-
standing how cyanide compounds respond
to treatment. The characterization of cya-
nide species falls into four general catego-
ries: 1. analytical methods, 2. ionic
structure, 3. strength of the cyanide-metal
complex bond, and 4. compound solubility.
Examples of each category are discussed in
the full report, along with a brief discussion
of the toxicity of free and complexed cya-
nides and the stability of cyanide-metal com-
plexes.
The various methods used in each of the
analytical procedures for cyanide are also
explained in the full report. For example,
procedures for determining total cyanide in-
clude acid reflux/distillation, automated ul-
traviolet digestion, ligand-exchange, and ion
chromatography; free cyanide procedures
include absorption spectrophotometry, vol-
umetric titrimetry, ion-selective electrodes,
gas chromatography, and ion exchange.
Cyanide Oxidation Treatment
The cyanide oxidation treatment technol-
ogies included in this study are alkaline chlo-
rination, WAO, UV/Oa, and electrolytic
oxidation.
Alkaline Chlorination
Alkaline chlorination is the method the
electroplating industry uses most often to
detoxify cyanide. It can be used to destroy
Printed on Recycled Paper
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Table 1. Summary of Metal-Finishing Waste Codes Evaluated Under the Land Disposal Restrictions Program for U.S. EPA's Office of
Research and Development
EPA
Hazardous
Waste Wo.
FOOB
Waste Description
Wastewater treatment sludges from
electroplating operations except from
the following processes: 1) sulfuric
acid anodizing of aluminum; 2) tin
plating on carbon steel; 3) zinc plating
(segregated basis) on carbon steel;
4) aluminum or zinc-aluminum plating
on carbon steel; 5) cleaning/stripping
associated with tin, zinc, and aluminum
plating on carbon steel; and
6) chemical etching and milling of
aluminum
Basis for Listing
Cadmium, hexavalent
chromium, nickel, and
cyanide (complexed)
Generators Sampled
Deere & Company
Amerock Corp.
Master Lock Co.
Evaluation:
Technology/Scale
• Wet-air oxidation at
bench-scale
• Stabilization/solidification
at bench-scale
F007 Spent cyanide plating-bath solutions
from electroplating operations
F008 Plating bath sludges from electroplating
operations where cyanides are used in
the process
F009 Spent strippling and cleaning-bath
solutions from electroplating operations
where cyanides are used in the process
F011 Spent cyanide solutions from salt-bath
pot cleaning after metal heat-treating
operations
F012 Quenching wastewater treatment
sludges from metal heat-treating
operations where cyanides are used in
the process
F019 Wastewater treatment sludges from the
chemical conversion coating of
aluminum
Cyanide (salts)
Cyanide (salts)
Cyanide (salts)
Cyanide (salts)
Amerock Corp.
None
Master Lock Co.
Woodward Governor Co.
Cyanide (complexed) Woodward Governor Co.
Hexavalent chromium and Ford
cyanide (complexed)
• Wet-air oxidation at
bench- and pilot-scale
Not applicable
• Ultraviolet light/ozonation
at bench-scale
• Electrolytic oxidation at
full-scale
• Stabilization/solidification
at bench-scale
• Electrolytic oxidation at
full-scale
• Stabilization/solidification
at bench-scale
• Wet-air oxidation at
bench-scale
free dissolved hydrogen cyanide or to oxi-
dize all simple and many complex inorganic
cyanides in wastewater. The most com-
monly used oxidizing agents are chlorine
gas or hypochlorite salt.
The full report discusses in detail the treat-
ment processes of three companies that use
one- or two-stage alkaline chlorination to
treat cyanide-contaminated metal finishing
wastewalers. The full report also presents
details of the other treatments and pro-
cesses referred to below.
Wet-Air Oxidation
WAO is the liquid-phase oxidation of or-
ganics or oxidizable inorganic components
at elevated temperatures and pressures.
Zimpro/Passavant in Rothschild, Wl, per-
formed bench-scale WAO testing on F006,
F007, and F019, and pilot-scale WAO testing
on F007.
Ultraviolet Light/Ozonation
With UV/Oa, the cyanide stream is mixed
with ozone before it enters a reaction cham-
ber, where UV radiation enhances oxidation
by direct disassociation of the cyanide radi-
cal or through excitation of the various spe-
cies in the waste stream. Some complexed
cyanides may be more effectively oxidized
by ozone in the presence of UV light.
The Illinois Institute of Technology Re-
search Institute (IITRI), Chicago, IL, con-
ducted bench-scale studies of the UV/Os
system for the treatment of F009 waste.
Electrolytic Oxidation
Electrolytic oxidation has been used to
treat wastes containing high concentrations
of cyanide; the full report describes its use
to treat residuals from a salt-bath heat-treat-
ing operation. The concentrated cyanide
waste stream may be subjected to electrol-
ysis for several days. The cyanide gradually
decomposes to carbon dioxide and ammo-
nia, with cyanate as an intermediate.
Chemical Precipitation
Precipitation of metal-laden wastewaters
involves adding chemicals to alter the phys-
ical state of the dissolved or suspended
metals and to facilitate their removal through
sedimentation. Chemicals used to precipi-
tate metals from aqueous streams include
caustic soda, lime, sodium sulfide, phos-
phoric acid, ferrous sulfide, soda ash, and
sodium borohydride. The full report details
a phosphoric acid metal precipitation/-
alkaline chlorination process.
Stabilization/Solidification
S/S entails mixing a hazardous waste with
a binder material to enhance the physical
and chemical properties of the waste and the
chemical binding of any free liquid. The
-------
binder is typically a cement, pozzolan, or
thermoplastic.
The U.S. Army Corps of Engineers Water-
ways Experiment Station (WES) in Vicks-
burg, MS, conducted S/S testing on F006,
F011, and F012 metal-finishing wastes
under an interagency agreement. Three dif-
ferent pozzolan binders (lime/fly ash, port-
land cement, and kiln dust) were tested to
determine their application to these wastes.
Testing Results
Of the six technologies discussed above,
only WAO, UV/Oa, and S/S were tested to
assess their effectiveness in treating cya-
nide. Bench-scale UV/Oa testing proved in-
conclusive in its ability to treat complexed
cyanide.
Wet-Air Oxidation: Bench-Scale
The results of the autoclave oxidations of
F006, F007, and F019 are presented in Ta-
bles 2 through 4. Compared with the dilute
wastes, the COD reductions were in the
range of 92% to 95% for the F006, 79% to
86% for the F007, and 68% to 83% for the
F019. The total cyanide reductions in the
filtrates were in the range of 78% to 99% for
the F006, 99% to 99.5% for the F007, and
98% to 99.9% for the F019. The ammonia-
nitrogen from the cyanide oxidations
reached a maximum of about 300 mg/L for
the F006 tests at 240° and 280°C, 5000 mg/L
Table 2. Wet-Air-Oxidation Results for F006
Oxidized Product
Parameter*
Oxidation temp, °C
Time at temp, min
COD, g/L •
COD reduction, %
pH
WHa-W, mg/L
Total solids, jf/L
Total ash, g/L
Cyanide, total, mg/L
Total cyanide reduction, %
Cyanide, amenable, mg/L
Amenable cyanide reduction, %
Sul fides, mg/L
Fluoride, mg/L
Arsenic, fig/L
Antimony, ftg/L
Barium, mg/L
Beryllium, mg/L
Cadmium, mg/L
Chromium (T), mg/L
Chromium (+6), mg/L
Copper, mg/L
Iron, mg/L
Lead, mg/L
Mercury, mg/L
Nickel, mg/L
Selenium, mg/L
Silver, mg/L
Thallium, mg/L
Vanadium, mg/L
Zinc, mg/L
Autoclave
Feed
-
-
3.7
-
11
-
17.3
15.9
122.4
• -
73.9
-
<1
3.59
<1.2
<5.0
0.54
<0.01
220.5
348.4
Interference
729.1
1177
1.12
0.42
643.9
<0.2
<0.05
<5.0
<0.05
355.1
Filtrate
200
60
0.166
95.5
9.9
203.60
1.92
1.77
26.3
78
26.3
64
<1
2.12
<5.0
<5.0
0.17
0.018
0.53
44.4
33.8
25.9
0.73
<0.5
2.05
2.4
38
<0.05
40
<0.05
0.44
Cake
200
60
197
-
- -
-
700%
85.3%
102 ftg/g
-
102ftg/g
-
-
0.69 mg/g
<2400ftg/g
72.8ftg/g
40ftg/g
0.28ftg/g
241 mg/g
29 mg/g
1980ftg/g
78 mg/g
9.5 mg/g
48fig/g
1.1 ftg/g
62 mg/g
<4000 ftg/g
<1p9/9
<1 4 ftg/g
<1f9/g
33 mg/g
Filtrate
240
60
0.269
93
9.7
305.1
1.25
1.17
0.82
99
0.82
99
<1
1.8
<5.0
<5.0
0.17
0.014
0.25
16.7
15.3
5.4"
0.07
<0.5
5.14
0.12
19
<0.05
50
<0.05
0.26
Cake
240
60
24
-
.
-
700%
86.6%
20 ftg/g
.
20fig/g
_
.
0.7 mg/g .
<2400fig/g
84.8/tg/g
43ftg/g
<0.2ftg/g
254 mg/g
31 mg/g
830 ftg/g
85 mg/g
10.1 mg/g
103ftg/g
0.12ftg/g
63 mg/g
<4000fig/g
<1 ftg/g
<14ftg/g
<1f*glg
35 mg/g
Filtrate
280
60
0.311
92
10.1
306
1.79
1.79
1.1
99
1.1
98
<1
3.5
<5.0
<5.0
0.19
0.015
0.27
<0.09
<0.2
5.9
0.08
<0.5
4.1
0.33
36
<0.05
40
<0.05
0.29
Cake
280
60
29
_
-
Y00%
87.8%
Slfigfg
*
81 ftg/g
.
„
•0.63 mg/g
2400ftg/g
81.4ftg/g
39ftg/g
<0.2ftg/g
241 mg/g
32 mg/g
73 ftg/g
79 mg/g
9.7 mg/g
127ftg/g
0.12ftg/g
62 mg/g
<4000ftg/g
<1 ftg/g
<14fig/g
<1 P9/9
33 mg/g
* Units are specified in this column except as noted elsewhere,
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Table 3. Wet-Air-Oxidation Results forF007
Oxidized Product
Parameter*
Oxidation temp, °C
COD, mg/L
COD reduction, %
Cyanide, total, mg/L
Total cyanide
reduction, %
Cyanide, amenable,
mg/L
Amenable cyanide
reduction, %
Total solids, mg/L
Total ash, mg/L
pH
NHa-N, mg/L
Sullide, mg/L
Arsenic, mg/L
Barium, mg/L
Cadmium, mg/L
Chromium (T), mg/L
Chromium (+6), mg/L
Copper, mg/L
Load, mglL
Mercury, mg/L
Nickel, mg/L
Selenium, mg/L
Sliver, mg/L
Zinc, mg/L ,
Raw
Waste
33,370
-
23,667
-
21,750
-
260,770
242,300
10.8
134
1.36
<1.2
3.23
<0.04
7.5
<0.1
7663
0.81
0.0048
8.46
31.2
<0.05
4180
Dilute
Waste**
16,685
-
11,834
-
10,875
-
130,385
121,150
-
67
0.68
<1.2
1.62
<0.04
3.75
<0.1
3832
0.40
0.0024
4.23
15.6
<0.05
305
Filtrate
200
3,060
81.7
117
99.0
114
99.0
110,000
103,600
9.8
5,000
-
<1.2
0.017
<0.004
3.24
0.90
863
2.3
0.0095
0.38
13.0
<0.05
305
Solids
200
-
-
1 83 fig I g
-
143fig/g
-
9,500*
8,300t
-
-
-
<35
104
<1.15
30.5
/Sn
261,440
464
0.23
1,305
90
<1.4
75,890
Filtrate
240 ,
2,375
86.1
86
99.3
86
99.2
86,600
83,100
9.4
3,104
-
<1.2
0.012
< 0.004
3.33
0.66
553
1.4
0.0106
0.099
9.2
<0.05
159
Solids
240,
-
-
<1.0figlg
-
<1.0nglg
'
9,000*
8,100*
-
-
-
<35
83.4
<1.15
13.5
<3.4
234,600
229
0.14
408
89
<1.4
79,270
Filtrate
280
3,578
78.6
58
99.5
55
99.5
76,200
66,600
9.0
1,187
-
<1.2
0.003
<0.004
3.04
0.18
316
0.80
0.0106
0.067
5.5
<0.05
29.8
Solids
280
-
-
<1.0ftg/g
-
<1.0/tg/g
-
8,800*
7,800*
-
-
-
<32
68.0
<1.07
13.3
<3.9
219,450
172
0.153
337
116
<1.3
82,565
*Units are specified in this column except as noted elsewhere.
** Concentrations calculated on 1:1 dilution of raw wastewater.
* Concentration of suspended solids/suspended ash filtered from oxidized waste.
1f IS = Insufficient Sample.
for the F007 test at 200°C, and about 760
mg/L for the F019 test at 280°C.
Wet-Air Oxidation: Pilot-Study
The WAO study was performed on the
F007 wastes containing total cyanides in
excess of 30 g/L (3%). The 24-hr study was
conducted in a 5.4-gal pilot unit constructed
of titanium. The major oxidation operating
parameters forthis test were reactor temper-
ature of 454°F, a reactor pressure of 1700
psig, and a reactor residence time of 54 min.
Zimpro's analyses showed a 99.99% cya-
nide destruction with a residual concentra-
tion of 1.57 ppm cyanide in the oxidized
liquor.
Stabilization /Solidification
For one source of F006 filter cake, S/S
leaching data showed low concentrations of
metals in the extracts for all three binders
(cement, lime/fly ash, kiln dust). Cadmium
was less than 0.003 mg/L, hexavalent chro-
mium ranged from 0.04 to 0.23 mg/L, and
nickel was 0.025 to 0.042 mg/L. The cement
binder was the most effective in containing
copper and zinc.
The second source of F006 waste did not
demonstrate the same level of S/S effective-
ness for two binder systems. With the kiln
dust binder, extracts contained 42.2 to 77.5
mg/L cadmium, 0.054 to 0.078 mg/L hexava-
lent chromium, 4.63 to 11.3 mg/L nickel, and
106 to 112 mg/L magnesium. The lime/fly
ash binder extracts showed 0.031 to 0.17
mg/L cadmium, 0.30 to 0.37 mg/L hexava-
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Table 4. Wet-Air-Oxidation Results for F01 9
Autoclave
Parameter* Feed
Oxidation temp, °C
Time at temp, min
COD, g/L
COD reduction, %
pH
NHa-N, mg/L
Total solids, g/L
Total ash, g/L
Cyanide, total, mg/L
Total cyanide from solids, mg/L
Total cyanide reduction, %
Cyanide, amenable, mg/L
Amenable cyanide from solids, mg/L
Amenable cyanide reduction, %
Suffides, mg/L
Fluoride, mg/L
Arsenic, ftg/L
Antimony, ftg/L
Barium, mg/L
Beryllium, mg/L
Cadmium, mg/L
Chromium (T), mg/L
Copper, mg/L
Iron, mg/L
Lead, mg/L
Mercury, mg/L
Nickel, mg/L
Selenium, mg/L
Silver, mg/L
Thallium, mg/L
Vanadium, mg/L
Zinc, mg/L
-
7
10.5
-
8.54
27.7
41.7
28.1
293.1
-
-
240.9
-
-
<1
38.9
80.2
<5.0
2.7
0.007
2.11
1231
0.355
189
14.7
0.35
0.875
50.8
<0.01
<140
0.31
4902
Filtrate
200
60
1.75
83.3
7.95
527.50
2.78
1.45
5.07
-
98
5
-
98
<1
24.7
132
<5.0
0.21
<0.001
0.013
1.92
0.053
0.13
0.003
1.1
0.007
250
<0.005
9.5
0.006
4.6
Oxidized Product
Cake
200
60
73.7
-
-
-
98.8%
83.9%
22.9 ftg/g
0.91
-
22.9ftg/g
0.91
-
-
0.17fig/g
114fig/g
465ftg/g
138ftg/g
0.32fig/g
lOZfiglg
72,267ftg/g
48.7ftgfg
1 2,000 ftg/g
816/tg/g
<0.02 ftg/g
46fig/g
<20 fig/g
<0.5ftg/g
< 5 ftg/g
<0.5fig/g
61,000ftg/g
Filtrate
240
60
3.04
68
7.9
668
2.55
1.26
0.058
-
99.9
0.02
-
>99.9
99.9
<1
38.9
<5.0
<5.0
0.77
<0.01
<0.04
24
0.12
0.08
0.916
0.8
0.21
<5.0
0.05
5.0
<0.05
15.2
Cake
280
60
25.3
-
-
•'
100%
89.7%
18ftg/g
0,57
'
18fig/g
0.57
.
-
0.23 ftg/g
109figfg
469fig/g
166ftg/g
0.32fig/g
104ftg/g
74,072 ftg/g
66ftg/g
1 5,238 ftg/g
584 fig Ig
<0.02fig/g
48fig/g
<20ftg/g
<0.5fig/g
<5fig/g
<0.5fig/g
279,000 ftg/g
' Units are specified in this column except as noted elsewhere.
lent chromium, less than 0.03 mg/L nickel,
and 1.04 to 3.47 mg/L magnesium. The
cement binder extracts showed 0.26 to 0.28
mg/L cadmium, 0.023 to 0.074 mg/L hexava-
lent chromium, less than 0.031 mg/L nickel,
and 0.096 to 0.13 mg/L magnesium.
Cement-treated F012 extracts showed av-
erage concentrations of 47.5 mg/L magne-
sium and 2.6 mg/L nickel. Lime/fly ash
extracts showed 1.01 mg/L aluminum, 12.9
mg/L magnesium, and 0.034 mg/L nickel.
Kiln dust extracts showed concentrations of
46.7 mg/L magnesium and 1.47 mg/L nickel.
Conclusions.
Data from the WAO bench-scale test indi-
cated significant destruction of cyanides in
F006, F007, and F019 wastes. Similar re-
sults were obtained for the F007 pilot-scale
tests. The most effective S/S binder system
for F006 metals was cement.
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Thefull report was submitted in fulfillment
of EPA Contract No. 68-03-3389 by PEI
Associates, Inc., under the sponsorship of
the U.S. Environmental Protection Agency.
The project was prepared by the staff of PEI Associates, Inc., Cincinnati, OH 45246.
Ronald J. Turner is the EPA Project Officer (see below)
The complete report, entitled "Characterization and Treatment of Wastes from Metal-
Finishing Operations,"(Order No. PB91-125 732/AS; Cost: $23.00, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Risk Reduction Engineering 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 $300
EPA/600/S2-90/055
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