United States
Environmental Protection
Agency
Industrial Environmental Research EPA-600 2 80-1 39
Laboratory June 1980
Cincinnati OH 45268
Research and Development
v>EPA
Sulfide
Precipitation of
Heavy Metals
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution-sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-80-139
June 1980
SULFIDE PRECIPITATION OF HEAVY METALS
by
Alan K. Robinson and 3oyce C. Sum
Manufacturing Research and Development
Boeing Commercial Airplane Company
Seattle, Washington 98124
Grant: S805413
Project Officer
Hugh B. Durham
Industrial Pollution Control Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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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
publication. Approval does not signify that the contents necessarily 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.
11
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FOREWORD
When energy and material resources are extracted, processed, converted, and used,
the related pollutional impacts on our environment and even on our health often require
that new and increasingly more efficient pollution control methods be used. The
Industrial Environmental Research Laboratory—Cincinnati (lERL-Ci) assists in
developing and demonstrating new and improved methodologies that will meet these
needs both efficiently and economically.
This report describes work undertaken to assess the merits of a method for removing
heavy metals from wastewater by precipitation of the metals as sulfides instead of the
usual hydroxide method. The results of the work can be used as a source of technical and
cost data to compare the relative merits of the sulfide and hydroxide processes for
removing heavy metals from industrial wastewaters.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
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ABSTRACT
This research program was initiated with the objective of evaluating a new process,
the suifide precipitation of heavy metals from industrial wastewaters. The process was
expected to effect a more complete removal of heavy metals than conventional lime
processing because of the much lower solubilities of metal sulf ides than hydroxides.
Five processes were compared in bench-scale, continuous-flow equipment: conven-
tional lime processing, conventional lime processing plus filtration, lime with a suifide
polishing and filtration, lime with suifide, and lime with suifide plus filtration.
Samples of actual wastewaters from 14 metal working industries (including Boeing)
were processed through the bench-scale equipment using all five processes. Reductions in
the concentrations of cadmium, chromium, copper, nickel, and zinc, plus selected other
metals, were measured by atomic absorption chemical analysis.
Capital and operating costs for the five processes were compared for three plant
sizes: 37.85 m3/day (10,000 gal/day), 757 m3/day (200,000 gal/day), and 1,893 m3 /day
(500,000 gal/day).
The report recommends that, to reduce the levels of cadmium, copper, nickel, or zinc
from a wastewater treatment plant using conventional lime processing, the addition of a
final filtration should be considered first. > If filtration does not achieve the desired low
levels, then a suifide polishing process with added filtration is recommended. If reduction
of the levels of chromium, lead, silver, or tin is required, the conventional lime process
plus filtration is recommended. The suifide process did not significantly reduce the levels
of these metals.
Details are included on the use of a specific ion electrode for the control of suifide
additions. The report does not include comparison testing of the commercial Sulfex
process.
This report was submitted in fulfillment of Grant S805413 by Boeing under the
sponsorship of the U.S. Environmental Protection Agency. This report covers a period
from October 1977 to July 1979; work was completed as of July 1979.
IV
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CONTENTS
Foreword '.,....' iii
Abstract iv
Figures vii
Tables x
Abbreviations and Conversions xi
Acknowledgment xii
1. Introduction 1
2. Conclusions 2
Overview .* 2
Effectiveness of processes for removing heavy metals 2
Operating and capital equipment costs 2
Sludge disposal costs . .' 3
Effectiveness of specific processes for removing
heavy metals 3
Control of sulfide concentration by specific ion electrode 5
3. Recommendations 6
i*. Description of the Lime Processes (LO-CL and LO-CLF) 7
General. ' 7
Outline of lime process 7
5. Description of the Lime-With-Sulfide Processes (LWS-CL and
LWS-CLF) 9
General 9
Outline of lime-with-sulfide process 9
Control of sulfide additions 10
6. Description of the Lime, Sulfide Polished and Filtered
Processes (LSPF) 11
General 11
Outline of lime, sulfide polished and filtered process 11
7. Reason for Omission of Tests on the Sulfex Process 13
8. Removal of Cyanides and Hexavalent Chromium From Wastewaters ... 14
General 14
Removal of cyanides 14
Removal of hexavalent chromium 14
9. Bench-Scale Equipment Used in the Tests 15
General 15
Equipment details 15
10. Description of the Fourteen Wastewaters Treated . . 20
11. Presentation of the Analytical Results 21
12. Capital Costs of Full-Scale Plants 24
13. Operating Costs of Full-Scale Plants 28
General 28
Assumptions used in the calculations 28
14. Electron Photomicrographs of Sludges 33
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15. Slide and Cassette Tape Presentation ................ 35
16. Confidence Levels of the Chemical Analyses ............. 3°
General ........................... 36
Analysis of EPA standards ................... 36
Statistical repeatability tests ................. 36
17. Consultant's Report ........................ 38
References
Appendices
A. Case history data of 16 test runs .................. ^2
B. Analytical methods ........................ 59
C. Comparison plots of five metal concentrations for all samples ...... 60
D. Sign test statistical analysis .................... 71
E. Wilcoxon matched-pair, signed-rank statistical analysis ........ 76
F. Capital cost of full-scale plants ................... 78
G. Graphic presentation of results ................... 98
H. Criteria for selecting pH value for precipitation ........... •
VI
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FIGURES
Number Page
1 Lime-only process flow diagram 8
2 Lime-with-sulfide process flow diagram 10
3 Lime, sulfide polished and filtered process flow diagram 11
4 Bench-scale unit for processing industrial wastewater by'the
LO-CL, LO-CLF, LSPF, LWS-CL, and LWS-CLF processes 16
5 . Flow diagram of multipurpose bench-scale equipment 17
6 Bench-scale unit showing instrumentation and air vent hood 18
7 Wastewater being charged into sample reservoir of
bench-scale unit from sample drum 19
8 Electron photomicrograph of lime-with-sulfide
sludge (magnified at 46,500x) 34
C-l Comparison of LO-CL process and LSPF process using
Cd, Cu, Cr, Ni, and Zn effluent metal concentrations
for all wastewater samples 61
C-2 Comparison of LO-CLF process and LO-CL process using
Cd, Cu, Cr, Ni, and Zn effluent metal concentrations
for all wastewater samples 62
C-3 Comparison of LSPF process and LWS-CL process using
Cd, Cu, Cr, Ni, and Zn effluent metal concentrations
for all wastewater samples 63
C-4 Comparison of LWS-CL process and LO-CLF process using
Cd, Cu, Cr, Ni, and Zn effluent metal concentrations
for all wastewater samples 64
C-5 Comparison of LO-CLF process and LWS-CL process using
Cd, Cu, Cr, Ni, and Zn effluent metal concentrations
for all wastewater samples 65
C-6 Comparison of LO-CL process and LWS-CLF process using
Cd, Cu, Cr, Ni, and Zn effluent metal concentrations
for all wastewater samples 66
C-7 Comparison of LSPF process and LO-CLF process using
Cd, Cu, Cr, Ni, and Zn effluent metal concentrations
for all wastewater samples 67
VI1
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Number Page
C-8 Comparison of LWS-CLF process and LSPF process using
Cd, Cu, Cr, Ni, and Zn effluent metal concentrations
for all wastewater samples .................... 68
C-9 Comparison of LWS-CLF process and LWS-CL process using
Cd, Cu, Cr, Ni, and Zn effluent metal concentrations
for all wastewater samples .................... 69
C-10 Comparison of LWS-CL process and LO-CL process using
Cd, Cu, Cr, Ni, and Zn effluent metal concentrations
for all wastewater samples .................... 70
D-l Hierarchy of wastewater treatment processes
established from sign test statistical analysis ............ 71
D-2 Agreement between LO-CLF and LO-CL not significant
at 75-percent confidence level ................... 72
D-3 Agreement between LSPF and LO-CL not significant
at 75-percent confidence level .................. 72
D-4 Agreement between LWS-CL and LWS-CLF not significant
at 75 -percent confidence level .................. 72
D-5 Agreement between LO-CLF and LWS-CL significant
at 75-percent confidence level ................... 73
D-6 Agreement between LSPF and LWS-CL not significant
at 75-percent confidence level ................... 73
D-7 Agreement between LO-CL and LWS-CL not significant
at 75-percent confidence level ................... 73
D-8 Agreement between LWS-CLF and LO-CL not significant
at 75-percent confidence level ................... 74
D-9 Agreement between LO-CLF and LSPF not significant
at 75-percent confidence level
D-10 Agreement between LO-CLF and LWS-CLF not significant
at 75-percent confidence level ..... .N ............. 74
D-ll Agreement between LSPF and LWS-CLF significant
at 75-percent confidence level ................... 75
E-l Hierarchy of wastewater treatment processes established from
Wilcoxon matched-pair, signed-rank statistical analysis ........ 77
F-l Small LO-CL and LO-CLF plant schematic .............. 82
F-2 Small LSPF, LWS-CL, and LWS-CLF plant schematic ......... 83
F-3 Medium-sized LO-CL and LO-CLF plant schematic .......... 84
F-4 Medium-sized LSPF plant schematic ................. 85
F-5 Medium-sized LWS-CL and LWS-CLF plant schematic ......... 86
F-6 Large LO-CL and LO-CLF plant schematic .............. 87
via
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Number Page
F-7 Large LSPF plant schematic 88
F-8 Large LWS-CL and LWS-CLF plant schematic 89
F-9 Small plant layout—all processes (LO-CL,
LO-CLF, LSPF, LWS-CL, and LWS-CLF) 90
F-10 Medium-sized LO-CL and LO-CLF plant layout 91
F-ll Medium-sized LSPF plant layout 92
F-12 Medium-sized LWS-CL and LWS-CLF plant layout 93
F-13 Large LO-CL and LO-CLF plant layout 94
F-14 Large LSPF plant layout . 95
F-15 Large LWS-CL and LWS-CLF plant layout 96
F-16 Cross section of medium-sized arid large plants—all
processes (LO-CL, LO-CLF, LSPF, LWS-CL, and LWS-CLF) 97
G-l Relationship of LO-CL process effluent concentration to raw
feed concentration for Cd, Cu, Cr, Ni, and Zn 99
G-2 Relationship of LO-CLF process effluent concentration to raw
feed concentration for Cd, Cu, Cr, Ni, and Zn 100
G-3 Relationship of LSPF process effluent concentration to raw
feed concentration for Cd, Cu, Cr, Ni, and Zn 101
G-4 Relationship of LWS-CL process effluent concentration to raw
feed concentration for Cd, Cu, Cr, Ni, and Zn 102
G-5 Relationship of LWS-CLF process effluent concentration to raw
feed concentration for Cd, Cu, Cr, Ni, and Zn 103
H-l Effect of pH on effluent concentration of heavy metals
IX
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TABLES
Number Page
1 Comparison of Operating Costs
2 Comparison of Capital Costs
3 Arithmetic Mean Influent and Effluent Concentrations for
the Five Processes
4 Logarithmic Mean Influent and Effluent Concentrations for
the Five Processes
5 Arithmetic Mean Influent and Effluent Concentrations for
the Five Processes ........................ 21
6 Logarithmic Mean Influent and Effluent Concentrations for
the Five Processes ........................ 22
7 Summary of Plant Capital Installation Costs .............. 24
8 Small Plant Construction Costs .................... 25
9 Medium -Sized Plant Construction Costs ................ 26
10 Large Plant Construction Costs .................... 27
1 1 Summary of Operating Costs ..................... 28
12 Operating Costs for Small Plant .................... 30
13 Operating Costs for Medium -Sized Plant ................ 31
14 Operating Costs for Large Plant ............ . ...... 32
15 Analysis of EPA Standards ...................... 37
16 Effluent From LO-CL Process .................... 37
17 Effluent From LO-CLF Process .................... 37
18 Confidence Levels of the Analyses .................. 37
19 Zinc Removal From Waste No. 12 ................... 39
20 Metal Removal From Waste No. 9 ................... 39
Data Sheets for Test Runs 1 through 16 .................. 43-58
E-l T- Values of Wilcoxon Matched-Pair, Signed-Rank Statistical
Analysis ................ ............ 77
H-l Proposed EPA Guideline Levels ................... 105
H-2 Effluent Concentration Related to EPA Proposed Limitations ...... 105
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ABBREVIATIONS AND CONVERSIONS
ABBREVIATIONS
LO-CL —lime only, clarified
LO-CLF —lime only, clarified and filtered
LSPF —lime, sulfide polished and filtered
LWS-CL —lime with sulfide, clarified
LWS-CLF —lime with sulfide, clarified and filtered
Be — Baume degrees
v/v —volume per volume ratio
jumho/cm — micromho per centimeter (same as /iS/cm)
L -liter
METRIC CONVERSIONS
To Convert To Multiply by
gal L 3.785 412 E+00
gal/min L/min 3.785 412 E+00
gal/hr L/h 3.785 412 E+00
gal/day L/day 3.785 412 E+00
gal/mo L/mo 3.785 412 E+00
inches cm 2.540 000 E+00
Ib/hr kg/h 4.535 924 E-01
Ib/day kg/day 4.535 924 E-01
ppb Mg/L . 1.000 000 E+00
ppm mg/L 1.000 000 E+00
XI
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ACKNOWLEDGMENT
We would like to acknowledge the assistance of the following.
For assistance in locating metal finishing companies willing to supply wastewaters: Mr.
E. P. Durkin, president of Metal Finishers Foundation.
For their cooperation in supplying wastewaters:
The Advance Plating Company, Cleveland, Ohio
Dixie Industrial Finishing Company, Atlanta, Georgia
Automation Plating Corporation, Glendale, California
Chrome-Rite Company, Chicago, Illinois
ADI Industries, Inc., Chicago, Illinois
Franke Plating Works, Inc., Fort Wayne, Indiana
Alco Cad-Nickel Plating Corporation, Los Angeles, California
Lincoln Plating Company, Lincoln, Nebraska
Superior Plating, Inc., Minneapolis, Minnesota
Heath Techna Corporation, Kent, Washington
Holley Carburetor Division of Colt Industries, Warren, Michigan
Federated Metals Corporation, New York, New York
For information on the Sulfex process: Mr. R. Schiauch, Mr. M. Scott, Mr. W. Schwoyer,
and Mrs. C. Glover of the Permutit Company, New 3ersey.
Of the many Boeing colleagues who have contributed to this program, particular
acknowledgment goes to Mr. W. Larsen and Mr. I. Woods for chemical analysis.
For consultation services: Dr. D. Bhattacharyya of the Department of Chemical
Engineering, University of Kentucky, Lexington, Kentucky.
To Dr. H. B. Durham and Mr. D. Wilson of the Environmental Protection Agency Labor-
atories, Cincinnati, Ohio, who have been EPA project officers on the program.
Xll
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SECTION 1
INTRODUCTION
The purification of industrial process wastewaters that contain heavy metals, such
as cadmium, copper, chromium, nickel, and zinc, is commonly accomplished by pre-
cipitating these metals as hydroxides. The process is relatively inexpensive and is well
established. However, removal of metals by the hydroxide process is incomplete, either
because of slight solubility of the metal hydroxides or because of incomplete settling out
of small particles of the hydroxides.
A much more complete removal of metals from wastewaters could be expected for
processes using sulfides instead of hydroxides for precipitation. In general, metal
sulfides have solubilities several orders of magnitude smaller than the corresponding
hydroxides.
The work described in this report is a side-by-side comparison of three sulfide
methods and two hydroxide methods of wastewater treatment. The tests were conducted
on actual wastewaters from the nonferrous metal producing and metal finishing industry
in the United States.
The wastewater treatments were conducted on a continuous-flow, bench-scale
model treatment plant. The plant was of a size suitable for providing test runs lasting
several hours from each 190L (50-gal) sample of wastewater.
The Permutit Company's Sulfex process (1, 2, 3), which uses an insoluble iron sulfide,
originally was to be included in this study; however, legal difficulties prevented its
inclusion.
This report is concerned only with soluble forms of sulfide precipitant, such as
Na2S, NaHS, and H2S.
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SECTION 2
CONCLUSIONS
OVERVIEW
Three suifide precipitation processes that use soluble sulfides have been demon-
strated (in a continuously operated bench-scale plant) as practical waste treatment
processes for removing heavy metals from wastewater. the levels to which heavy
metals can be reduced, and the costs of treatment compared to conventional lime
treatment, are developed in this report.
The lime, suifide polished and filtered (LSPF) process is the optimum suifide
process. For many wastewaters, treatment by the lime process followed by filtration is
almost as effective as the LSPF process and costs far less.
EFFECTIVENESS OF PROCESSES FOR REMOVING HEAVY METALS
Based only on the reduction in concentration of five heavy metals (cadmium,
chromium, copper, nickel, and zinc) in the effluents analyzed and without considering
cost:
• The lime only, clarified (LO-CL) process is the least effective.
• Processes lime only, clarified and filtered (LO-CLF) and lime with suifide,
clarified (LWS-CL) are equally effective and better than the LO-CL process.
• Processes LSPF and lime with suifide, clarified and filtered (LWS-CLF) are
equally effective and better than any of the other three.
OPERATING AND CAPITAL EQUIPMENT COSTS
Each of the improvements to the basic LO-CL process carries a cost penalty.
Tables 1 and 2 show that:
• The addition of a filtration operation (conversion to the LO-CLF process) adds
from 0.4 to 0.7 percent to the operating costs and from 0.8 to 1.7 percent to
the capital costs.
• The addition of a suifide polishing operation, which includes filtration (conver-
sion to the LSPF process), adds from 4.8 to 8.6 percent to the operating costs
and from 8.6 to 11.6 percent to the capital costs.
• Conversion to a lime-with-sulfide process increases the capital cost by 6.2 to
11.6 percent; for a small plant, the process increases the operating cost by 7.1
to 7.8 percent, and for a medium or large plant, the process increases the
operating cost by 26.4 to 39.5 percent.
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TABLE 1. COMPARISON OF OPERATING COSTS
\
N. Operating
>v cost of :
N^
Plant ^v
capacity ^v
Conventional lime
plant with no
filtration
LO-CL
37.85 m3/day $5.96/m3
(10,000 gal/day) ($22.6/1 ,000 gal)
757 m3/day $0.90/m3
(200,000 gal/day) ($3.39/1 ,000 gal)
1 ,893 m3/day $0.55/m3
(500,000 gal/day) ($2.08/1 ,000 gal)
Lime plant
with
filtration
added (%)
LO-CLF
+0.7
+0.4
+0.5
TABLE 2. COMPARISON OF
Nv
N. Capital
N. cost of:
N.
>.
Plant ^v
capacity N^
Conventional lime
plant with no
filtration
LO-CL
37.85 m3/day $233,000
Lime plant
with
filtration
added (%)
LO-CLF
+1.7
Lime plant
with sulfide
"polish"
operation,
including
filtration (%)
LSPF
+4.8
+8.0
+8.6
Lime-with-
sulfide plant
with no
filtration (%)
LWS-CL
+7.1
+26.4
+39.0
Lime-with-
sulfide plant
with filtration
added (%)
LWS-CLF
+7.8
+26.8
+39.5
CAPITAL COSTS
Lime plant
with sulfide
"polish"
operation.
including
filtration (%)
LSPF
+11.6
Lime-with-
sulfide plant
with no
filtration (%)
LWS-CL
+9.4
Lime-with-
sulfide plant
with filtration
added (%)
LWS-CLF
+11.6
(10,000 gal/day)
757 m3/day
(200,000 gal/day)
1,893 m3/day
(500,000 gal/day)
$799,000
$1,296,000
+0.8
+1.1
+11.6
+8.6
+9.1
+6.2
+10.0
+7.2
SLUDGE DISPOSAL COSTS
The costs developed here include estimates for sludge disposal, which are based on
the assumption that a sulfide sludge will not carry any significant cost penalty. At this
stage, we do not know the additional surcharge, if any, that might be added to the
disposal charges for a sulfide sludge.
EFFECTIVENESS OF SPECIFIC PROCESSES FOR REMOVING HEAVY METALS
The same order of preference as that given on page 2, with more details about
individual metals, can be seen in Tables 3 and 4, which show the mean levels of the five
metals before and after treatment.
The tables show that cadmium, copper, and zinc follow the same hierarchy as we
established on page 2; that is, LO-CL is least effective, LO-CLF and LWS-CL are more
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effective, and LSPF and LWS-CLF are most effective. The logarithmic mean removal of
these three metals is 96.3 percent or greater for the two most effective processes, with
a logarithmic mean effluent concentration of less than 50
Nickel removal does not follow the established hierarchy completely; when the
logarithmic means are considered, the five processes are roughly equivalent. When the
arithmetic means are considered, the hierarchy is the same as that established for
cadmium, copper, and zinc. The logarithmic mean nickel removal is 88.4 percent or
TABLES. ARITHMETIC MEAN INFLUENT AND EFFLUENT
CONCENTRATIONS FOR THE FIVE PROCESSES
Concentrations in M9/L (values in parentheses are percentage reductions from raw feed)
Heavy metal
Cadmium
Copper
Chromium
Nickel
Zinc
Concentrations
Heavy metal
Cadmium
Copper
Chromium
Nickel
Zinc
* 1 /^rt awora/io .nf
Raw feed
4,805
4,136
26,006
18,617
259,865
TABLE 4.
in jug/L (values
Raw feed
135
673
1,039
976
23,904
v thr^iinH v
LO-CL
144
(97.00)
963
(76.72)
603
(97.68)
2,021
(89.14)
8,385
(96.77)
LO-CLF
103
(97.86)
673
(83.73)
58
(99.78)
1,561
(91.62)
6,629
(97.45)
LWS-CL
25
(99.48)
521
(87.40)
370
(98.58)
1,506
(91.91)
491
(99.81)
LSPF
13
(99.37)
96
(97.68)
58
(99.78)
652
(96.50)
517
(99.80)
LWS-CLF
8
(99.83)
70
(98.31)
86
(99.67)
751
(95.97)
422
(99.84)
LOGARITHMIC MEAN* INFLUENT AND EFFLUENT
CONCENT RA TIONS FOR THE FIVE PROCESSES
in parentheses are
LO-CL
31
(77.04)
109
(83.80)
136
(86.91)
156
(84.02)
820
(96.57)
TT7 l™~1 1 '
percentage
LO-CLF
18
(86.67)
63
(90.64)
24
(97.69)
118
(87.91)
210
(99.12)
'9* \
reductions from raw
LWS-CL
8
(94.07)
49
(92.72)
108
(89.61)
155
(84.12)
195
(99.18)
feed)
LSPF
5
(96.30)
21
(96.88)
24
(97.69)
93
(90.47)
46
(99.81)
LWS-CLF
4
(97.04)
16
(97.62)
32
(96.92)
113
(88.42)
31
(99.87)
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greater for the two most effective processes, and the logarithmic mean nickel level in
the effluents is 113 jug/L or less.
Chromium removal is not significantly improved by the presence of sulfides. That
is, the unfiltered effluents (LO-CL and LWS-CL processes) showed logarithmic mean
concentrations that were about equal at 136 and 108 jug/L, and the logarithmic means for
the filtered effluents (LO-CLF, LSPF, and LWS-CLF) were also about equal at 24, 24,
and 32 /xg/L, respectively. This grouping clearly indicates that filtration after clarifica-
tion had exerted a marked effect. Logarithmic mean chromium removal rates are 86.9
percent or greater for the unfiltered effluents and 96.9 percent or greater for the
filtered. Logarithmic mean chromium levels of 32 jug/L or less were obtained in the
effluents from the filtered processes and 136 /ug/L or less in the unfiltered.
These findings agree with the observation that chromium, unlike the other metals
considered, precipitates a hydroxide, not a sulfide, in the presence of sulfide ions. Thus,
no difference would be anticipated between the removal rates of hydroxides precipitated
by lime and hydroxides precipitated by sulfides. The solubility constant of the hydroxide
would govern in both cases.
Lead was removed effectively in some tests, such as Runs 5, 8, 14, and 15. In each
of these, the removal efficiency is 96.6 percent or greater for all five processes.
However, in many other runs, the efficiency of removal is poor, ranging from 0 to 77
percent. In two cases, Runs 1 and 4, a striking improvement was noted in the effluents
from filtered processes compared with the effluents from unfiltered processes. In Run 1,
the removal efficiency of the filtered process is 91.1 percent or greater, but virtually no
removal took place in the unfiltered process. In Run 4, the filtered-process removal
efficiency is 82 percent or greater, but the efficiency is only 30 to 64 percent for the
unfiltered process. Further work is needed to determine the underlying causes of these
variations in the effectiveness of the processes. Based on the present tests, for lead
removal, the sulfide processes apparently have no advantage over the lime process.
When the sulfide processes are used, silver removal is not significantly different
from conventional lime processing.
Tin is removed efficiently by all processes in Runs 3, 7, and 12, with greater than
95-percent removal efficiency. Runs 4 and 5 are less efficient, with removal ranging
from 19 to 86 percent. The sulfide processes are no more efficient than the conventional
lime processes.
CONTROL OF SULFIDE CONCENTRATION BY SPECIFIC ION ELECTRODE
The dependability of the sulfide specific ion electrodes that were used to control
sulfide levels was excellent during the 6-month period while the bench-scale plant was in
operation. Ruggedness, freedom from drift, and ease of electrode maintenance were
roughly intermediate when compared to those of a typical combination pH electrode and
to those of an oxidation-reduction-potential (ORP) probe.
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SECTION 3
RECOMMENDATIONS
To use conventional lime processing for reducing the levels of cadmium, copper,
nickel, or zinc in the effluent from a wastewater treatment plant, we recommend that:
a. The addition of a filtration operation should be considered;
b. If reduction of these heavy metals to the desired levels cannot be achieved by
filtration alone, the use of the LSPF process described in this report should be
considered.
Details about costs and about the anticipated levels that would be achieved by courses a
and b are given in this report.
The LWS processes are recommended only for small plants (37.85 m3/day or 10,000
gal/day), because of the high consumption of soluble sulfide. The high consumption
results in prohibitive chemical costs in larger plants (757 m3/day or 200,000 gal/day and
larger).
If reduction of the levels of chromium, lead, silver, or tin in the effluent from a
waste treatment plant that uses conventional lime processing is required, we recommend
filtration. The sulfide processes tested in this study did not significantly reduce the
levels of these metals and are not recommended.
Finally, we recommend that research be initiated to determine information about
the leaching and about other characteristics of the sulfide sludges generated by the
processes described in this report and to determine the availability of disposal sites for
such sludges.
-------
SECTION 4
DESCRIPTION OF THE LIME PROCESSES
(LO-CL AND LO-CLF)
GENERAL
The lime process for removing heavy metals from wastewater consists essentially of
raising the pH of the normally acid or neutral wastewater to a predetermined value that
is within the range 8.0 to 11.0 pH. A lime slurry is added, and the resultant precipitate,
containing the bulk of the heavy metals, is separated.
The lime process will not remove chromium in the form of chromates or dichro-
mates (for example, hexavalent chromium Cr6+ ), and it will not remove heavy metals
complexed with cyanide. Therefore, when these ions are present in the wastewater,
pretreatment is necessary to remove them. In this program, the methods used to remove
hexavalent chromium and cyanides are described in Section 8.
OUTLINE OF LIME PROCESS
The sequence of unit operations for the lime process used in this work is shown in
Figure 1. Notes on each operation are provided in the following paragraphs; a
description of the actual test hardware is given in Section 9.
Input Filter
A filter (0.1 p.m nominal) at the input made-sure that a uniform sample, free from
variable amounts of suspended matter, would be processed. The filter was for sample
uniformity only and is not recommended for a full-sized industrial plant.
Lime Slurry
This was composed of a suspension of 50 g/L CaO, continuously stirred.
Flash Mix Tank
In this continuously stirred tank, the pH of the raw feed water was raised to a
preselected value. (Criteria for selecting the pH are given in Appendix H.) The value
was maintained at ±0.1 pH unit by rnetered additions of lime slurry that were controlled
by a pH probe. Polyelectrolyte additions were made to the pH-adjusted stream at the
exit of the flash mix tank.
-------
LIME
SLURRY
FEED
INPUT
FILTER
pH
CONTROLLER
\ '
• *
L \
I
.J
FLASH
MIX
SETTLING
COLUMN
CLARIFIER
POLYELEC-
TROLYTE
FINAL
FILTER
EFFLUENT
SAMPLE POINT
FOR LO-CL
SAMPLE POINT
FOR LO-CLF
Figure 1. Lime only process flow diagram.
Polyelectrolyte
This substance was a freshly prepared concentrate of a proprietary, anionic
polyelectrolyte that improves the flocculation of precipitated metals in wastewaters.
Settling Column Clarif ier
The pH-adjusted wastewater from the flash mix tank was continuously fed upward
through a settling column, and the precipitated sludge was allowed to collect at the
bottom of the column. Clarified effluent was passed continuously from the top of the
column. Liquid rise rate in the column was 10.3 mm/min, and the sludge settling
velocity was generally 40 mm/min or greater; thus good separation was readily obtained.
In all tests, except Runs 1, 2, and 9, sampling of the process effluents was delayed until a
sludge bed at least 50 mm thick had formed; more complete clarification is expected
when the effluent passes through such a bed. For Runs 1, 2, and 9, insufficient
precipitate was generated, and it was impossible to build up a thick sludge bed with the
limited 190L samples that were available.
Final Filter
A final filter (0.1 jum nominal) removed traces of precipitate that were carried over
from the clarifier. Samples drawn from points before and after the filter were used to
determine the amount of carryover; the LO-CL samples were taken before the filter,
and the LO-CLF samples were taken after it.
-------
SECTION 5
DESCRIPTION OF THE LIME- WITH -SULFIDE PROCESSES
(LWS-CL AND LWS-CLF)
GENERAL
The lime-with-sulfide process for removing heavy metals from wastewater is a
modification of the lime process described in Section k. In the modified process, suifide
is added to the flash mix tank simultaneously with the lime slurry. Coprecipitation of
heavy metal sulfides and hydroxides occurs in the tank.
For each wastewater in this study, the same pH value was used for the lime process
and the lime-with-sulfide process.
Suifide additions were made continuously to the flash mix tank to maintain a small
(about 0.5 mg/L) excess of S=.
OUTLINE OF LIME-WITH-SULFIDE PROCESS
The sequence of unit operations of the lime-with-sulfide process, shown in Figure 2,
involves suifide additions controlled by a specific ion electrode. Soluble suifide is added
to the flash mix tank simultaneously with the lime slurry. The input filter, lime slurry,
polyelectrolyte, clarifier, and final filter were operated in the same manner as in the
lime process (see Section 4). A description of the additional test hardware is given in
Section 9. Notes on the additional operation and the flash mix tank are provided in the
following paragraphs.
Soluble Suifide
This was composed of a freshly prepared solution of 10 g/L Na2S'9H2O.
Flash Mix Tank
Metered additions of lime slurry and suifide solution were made to the raw feed
water in this continuously stirred tank. The pH of the raw feed water was raised to a
preselected value. (Criteria for selecting the pH are given in Appendix H.) The value
was maintained at ±0.1 pH unit by metered additions of the lime slurry, as controlled by
the pH probe. Simultaneously, metered additions of the suifide solution, which were
controlled by a reference electrode pair to detect the suifide specific ion, maintained a
preselected potential of -550 mV ±10 mV with respect to the reference electrode.
Polyelectrolyte additions were made to the pH- and suifide-adjusted stream at the exit
of the flash mix tank.
-------
FEED
SULFIDE
CONTROLLER
Ii
l—
1
INPUT
FILTER
>
SOLUBLE
SULFIDE
\
/
1
I
7
i
r
i
1 ' r
* FLASH *
MIX
t
i
POLYELEC-
TROLYTE
^^^H •••••
LIME
SLURRY
4
pH
CONTROLLER
1 1
J 1
A "
J
SETTLING
COLUMN
CLARIFIER
1
SAMPL
FOR LV
k-
r
E P(
VS-<
FINAL
FILTER
EFFLUENT
DINT SAMPLE POINT
2L FOR LWS-CLF
Figure 2. Lime-with-sulfide process flow diagram.
CONTROL OF SULFIDE ADDITIONS
The preselected value of -550 mV corresponds to about 0.5 mg/L of free sulfide and
was selected for two reasons:
• The curve of electrical potential versus sulfide concentration has its maximum
gradient in this region, thus giving a large response to a small change in free-
sulfide concentration.
• The concentration of 0.5 mg/L was the minimum excess sulfide that gave no
detectable odor from solutions at pH 8 to 9.
The electrode was nearly troublefree and had negligible drift. Fouling of the
electrode surface by precipitated materials usually was countered by wiping with a paper
tissue. At about 2-month intervals, the response of the electrode became noticeably
sluggish when tested in a reference solution. Light abrasion with 600-mesh silicon
carbide corrected this condition and restored the response rate. The electrode usually
was used for 6 hours per day and stored overnight in clean water.
10
-------
SECTION 6
DESCRIPTION OF THE LIME, SULFIDE POLISHED
AND FILTERED PROCESS (LSPF)
GENERAL
The lime, sulfide polished and filtered process for removing heavy metals from
wastewater is a modification of the lime process described in Section 4. In the modified
process, sulfide is added to the wastewater after the bulk of the heavy metals has been
removed by a lime process. The precipitation and removal of the small amount of heavy
metals that remain after lime processing is the polishing operation.
OUTLINE OF LIME, SULFIDE POLISHED AND FILTERED PROCESS
The sequence of unit operations of the lime, sulfide polished and filtered process,
shown in Figure 3, involves sulfide additions, controlled by a specific ion electrode, to
the sulfide polishing tank, which contains lime-processed and clarified wastewater. The
input filter, lime slurry, polyelectrolyte, clarifier, and final filter were operated in the
same manner as they were in the lime process (see Section 4). A description of the
additional test hardware used in this process is given in Section 9. Notes on the sulfide
polishing operation are provided in the following paragraphs.
Soluble Sulfide
This was composed of a freshly prepared solution of 10 g/L Na2S'9H2O.
SOLUBLE
SULFIDE
\
i
r
i
SULFIDE
POLISHING
r
1
I
SULFIDE
CONTROLLER
j '
1
1
FINAL
FILTER
EFFLUENT
SAMPLE POINT
FOR LSPF
Figure 3. Lime, sulfide polished and filtered process flow diagram.
11
-------
Suifide Polishing
Metered additions of the soluble sulfide solution were made to the pH-adjusted and
clarified wastewater in this continuously stirred tank. The metered additions, which
were controlled by a reference electrode pair to detect the sulfide specific ion,
maintained a preselected potential of -550 mV ±10 mV with respect to the reference
electrode. The behavior of the electrodes was similar to their behavior in the LWS
process. The notes in Section 5 under "Control of Sulfide Additions" apply also to the
LSPF process.
12
-------
SECTION 7
REASON FOR OMISSION OF TESTS
ON THE SULFEX PROCESS
The Sulfex process for removing heavy metals from processed waste streams by
sulfide precipitation is a proprietary system developed by The Permutit Company (2). It
differs from others described in Sections 5 and 6 of this report in that it uses relatively
insoluble iron sulfide, instead of highly soluble sodium sulfite or hydrosulfide, as its
source of sulfide ions for precipitation. Descriptions of the Sulfex process are given in
References 1, 2, and 3.
Although we originally intended to include the Sulfex process in this study, to enable
its merits to be objectively determined in direct comparison with conventional lime and
soluble sulfide methods, problems with commercial secrecy prevented its inclusion in the
program.
The Sulfex process relies partly on an existing patent (4) and partly on commercially
secret knowledge, some of which is included in a new patent application. The Permutit
Company understandably declined to reveal details of their process until an acceptable
secrecy agreement had been signed between Permutit and Boeing. Protracted negotia-
tions failed to reach this agreement, and the comparative tests on this process were
deleted from the program.
13
-------
SECTION 8
REMOVAL OF CYANIDES AND HEXAVALENT
CHROMIUM FROM WASTEWATERS
GENERAL
Heavy metals complexed with cyanides are not removed by the lime process, and
neither is chromium in the form of chromates and dichromates, that is, hexavalent
chromium (5). Consequently, the removal of cyanides and hexavalent chromium from a
wastewater before subsequent lime processing is a common practice.
REMOVAL OF CYANIDES
The alkaline chlorination process (5, 6) was used to remove cyanides when they were
present in the raw wastewater, that is, in Runs 5 and 9. The process, which was carried
out in 100L batches, is as follows:
a. Raise pH to 10.0 or higher (not necessary with the samples for Runs 5 and 9
because they were already in this condition).
b. Add 5-percent sodium hypochlorite solution until oxidizing conditions are
present, as indicated by an oxidation-reduction potential (ORP) (7) of 400 mV
minimum to convert the cyanide to cyanate.
c. Reduce pH to 2.5 by the addition of sulfuric acid. After about 5 min, the
cyanates in the wastewater are converted to carbon dioxide and nitrogen.
REMOVAL OF HEXAVALENT CHROMIUM
Reduction of the hexavalent chromium found in all raw feed wastewaters (except
Runs 5, 8, 12, and 13) was accomplished by adding sulfuric acid wherever necessary to
lower the pH to 2.5. This was followed by the addition of sodium sulfite until a 10- to
15-mg/L excess of SO3 was indicated by iodometric titration (8). The wastewater was
allowed to stand for a minimum of 1 hour after reduction before treatment in the bench-
scale plant.
-------
SECTION 9
BENCH-SCALE EQUIPMENT USED IN THE TESTS
GENERAL
Wastewaters were processed through a single bench-scale unit (Figure 4) that was
capable of operation in each of the five process modes: LO-CL, LO-CLF, LSPF,
LWS-CL, and LWS-CLF. Changeover from one mode to another was accomplished by
opening the appropriate valves and actuating the necessary feed pumps. Wastewater
flow rate through the equipment was 130 mL per minute.
Process details are given in Sections 4 (lime process), 5 (lime-with-sulfide process),
and 6 (lime, sulfide polished and filtered process). Figure 5 is a flow diagram for the
multipurpose bench-scale unit. Figures 4, 6, and 7 show the actual equipment.
EQUIPMENT DETAILS
Individual items of equipment are detailed in the following list (located by key
number in the flow diagram, Figure 5).
1. Sample drum: ACT 1 poly-drum (black, polyethylene, 55-gal shipping and
storage drum); ACT Poly-drum Division, 1100 South Azusa Ave., City of
Industry, California 91748
2. Tank: 350L stainless steel
3. Stirrer: J£ hp, 1,725 rpm, 32-in stainless steel shaft, with propeller
4. Tank: Polyethylene, 150L, with lid
5. Pump: Peristaltic type, 130 mL per minute
6. Filter: Disposable, wound polypropylene fiber type, nominal removal rating 0.1
jum; Motor Guard Corporation Model D-15, P. O. Box 1834, San Leandro,
California 94577
7. Pump: Peristaltic type, variable speed 6 to 120 mL per minute, Masterflex
7545 drive and 7014 pump head; Cole-Parmer Industrial Co., 7425 N. Oak Park
Ave., Chicago, Illinois 60648
8. Tank: Polyethylene, 7.5L capacity
9. pH controller: Chemtrix type 45 with 500W output and high and low adjustable
setpoints; Chemtrix Inc., 163 S.W. Freeman Ave., Hillsboro, Oregon 97123
10. Sulfide controller: Chemtrix type 45 with 400W output and high and low
adjustable setpoints; Chemtrix Inc., 163 S.W. Freeman Ave., Hillsboro, Oregon
97123
11. Tank: Polyethylene, 3L capacity
12. Clarifier: Plexiglas column, 127-mm (5-in) diameter, 610-mm (24-in) water
height
15
-------
•-
POLYELECTRO-
LYTE FEED PUMP ,
VARIABLE-
SPEED
PUMP FOR
LIME
SLURRY
FEED .
pH ELEC
TRODE
SULFIDE
ELECTRODES
SAMPLE
TANKS
FLASH
MIX
TANK
LIME
SLURRY
TANK
SULFIDE
POLISH
TANK
CONTROLLER
"I FOR VARIABLE
SPEED PUMP
Figure 4. Bench-scale unit for processing industrial wastewater by the LO-CL,
LO-CLF, LSPF, LWS-CL, and LWS-CLFprocesses.
-------
SULFIDE
CONTROLLER
LER
(io)
SULFIDE
TANK
©
1
^
STIRRER
Note.. See text for identity of key-numbered equipment.
Figure 5. Flow diagram of multipurpose bench-scale equipment.
13. Stirrer: Variable-speed laboratory stirrer, 1/75 hp, with 50-mm-diameter stain-
less steel propeller, T-Line No. 101, Tallboys Engineering Corporation,
Emerson, New 3ersey 07630
14. Pump: Peristaltic type, 2.8 mL per minute; Cole-Farmer Industrial Co., 7425
N. Oak Park Ave., Chicago, Illinois 60648
15. Valve: Pinch-type tubing control valve, Dura-Clamp®, United States Plastic
Corporation, Lima, Ohio 45801 ':
16. pH electrode: Chemtrix, No. H005; Chemtrix Inc., 163 S.W. Freeman Ave.,
Hillsboro, Oregon 97123
17. Sulfide specific ion electrode: Orion 94-16A used with reference electrode
Orion 90-02, Orion Research Inc., 380 Putnam Ave., Cambridge, Massachusetts
02139; or, Sensorex S1015M used with reference electrode, Sensorex RD1015F,
Sensorex, 502 Armstrong Ave., Irvine, California 92705
17
-------
SAMPLE
POINT
FILTER
pH CON-
TROLLER
STIRRER
LIME
SLURRY
TANK
SAMPLE
RESER-
VOIR
VENT HOOD
FOR AIR
EXTRACTION
SOLUBLE
SULFIDE
SUPPLY
TANK
SULFIDE
CONTROLLER
SULFIDE
ELECTRODES
pH ELEC-
TRODE
FLASH
MIX
TANK
CONTROLLER
FOR VARIABLE
SPEED PUMP
VARIABLE-SPEED
PUMP FOR LIME
SLURRY FEED
Figure 6. Bench-scale unit showing instrumentation and air vent hood.
-------
VENT HOOD FOR
AIR EXTRACTION
Figure 7. Wastewater being charged into sample reservior of bench-scale unit from sample drum.
19
-------
SECTION 10
DESCRIPTION OF THE FOURTEEN WASTEWATERS TREATED
The wastewaters collected for treatment in the bench scale plant were representa-
tive of wastewaters generated by the nonferrous metal producing and metal finishing
industries in the United States. Because the chelating agents usually present in
electroplating wastewater are known to inhibit precipitation (9, 10), emphasis was placed
on obtaining wastewater samples from as wide a variety of electroplating sources as
possible. Twelve samples of electroplating, anodizing, and other metal finishing rinse
waters plus one nonferrous metal smelter's wastewater (Run 8) and one copper printed
circuit etching wastewater were collected. All the samples were collected in new
polyethylene 190L (50-gal) drums.
The samples were supplied from companies spread over 10 states to minimize the
effects of local geographical conditions. About half of the samples were average
samples collected over a few days; the remainder were "grab" samples.
Brief individual descriptions of each sample are given in Appendix A (case history
data); the identity of the wastewater supplier companies is kept confidential at their
request.
20
-------
SECTION 11
PRESENTATION OF THE ANALYTICAL RESULTS
To simplify the data on the efficiency of removing heavy metals by the five
processes, the detailed results of Appendix A are condensed into two tables and a number
of graphic presentations. v
Tables 5 and 6 show the mean concentrations of cadmium, copper, chromium, nickel,
and zinc in the raw feed and in the effluents from each of the processes. Conventional
mean determinations may be misleading when applied to sets having an extremely wide
range (such as the nickel effluent concentrations, which range from <4 to 11,000 Mg/L f°r
one process). Thus, both the conventional mean and the logarithmic mean are used.
Table 5 shows the conventional mean, and Table 6, the mean based on a logarithmic
scale. That is, for n observations (x. x ):
vn
' I
Conventional (arithmetic) mean =
- log x
Logarithmic mean = log
Tables 5 and 6 also show the percentage reduction of the heavy metal concentra-
tions for each process.
TABLE 5. ARITHMETIC MEAN INFLUENT AND EFFLUENT
CONCENTRA TIONS FOR THE FIVE PROCESSES
Concentrations in M9/L (values in parentheses are percentage reductions from raw feed)
Heavy metal
Cadmium
Copper
Chromium
Nickel
Zinc
Raw feed
4,805
4,136
26,006
18,617
259,865
LO-CL
144
(97.00)
963
(76.72)
603
(97.68)
2,021
(89.14)
8,385
(96.77)
LO-CL F
103
(97.86)
673
(83.73)
58
(99.78)
1,561
(91.62)
6,629
(97.45)
LWS-CL
25
(99.48)
521
(87.40)
370
(98.58)
1,506
(91.91)
491
(99.81)
LSPF
13
(99.37)
96
(97.68)
58
(99.78)
652
(96.50)
517
(99.80)
LWS-CLF
8
(99.83)
70
(98.31)
86
(99.67)
751
(95.97)
422
(99.84)
21
-------
TABLE 6. LOGARITHMIC MEAN* INFLUENT AND EFFLUENT
CONCENTRA TIONS FOR THE FIVE PROCESSES
Concentrations in jug/L (values in parentheses are percentage reductions from raw feed)
Heavy metal
Cadmium
Copper
Chromium
Nickel
Zinc
* Log average of >
Raw feed
135
673
1,039
976
23,904
<1 through xn
LO-CL
31
(77.04)
109
(83.80)
136
(86.91)
156
(84.02)
820
(96.57)
/]C, '°9:
1 u-M 1
log I n
LO-CLF
18
(86.67)
63
(90.64)
24
(97.69)
118
(87.91)
210
(99.12)
A
I
LWS-CL
8
(94.07)
49
(92.72)
108
(89.61)
155
(84.12)
195
(99.18)
LSPF
5
(96.30)
21
(96.88)
24
(97.69)
93
(90.47)
46
(99.81)
LWS-CLF
4
(97.04)
16
(97.62)
32
(96.92)
113
(88.42)
31
(99.87)
Two main types of graphic plots are given in the Appendices. Appendix C plots
compare the effluent concentrations of pairs of processes. Each point plotted has two
coordinates: the concentration of a metal in process A effluent (x-axis), and the
concentration of the same metal in process B effluent (y-axis). A point below the H5-deg
line results when there is a higher concentration of the metal in process A effluent; if all
the points are below the line, then process A is clearly less effective in removing that
metal than process B. For example, in the following diagram the LO-CL process is less
effective than the LSPF process in removing copper.
cr
LU
u-3- iee
O v)
2o
h-O
-------
C-2 diagrams compare the LO-CLF and LO-CL processes
C-3 diagrams compare the LSPF and LWS-CL processes
C-4 diagrams compare the LWS-CL and LO-CLF processes
C-5 diagrams compare the LO-CLF and LWS-CLF processes
C-6 diagrams compare the LO-CL and LWS-CLF processes
C-7 diagrams compare the LSPF and LO-CLF processes
C-8 diagrams compare the LWS-CLF and LSPF processes
C-9 diagrams compare the LWS-CLF and LWS-CL processes
C-10 diagrams compare the LWS-CL and LO-CL processes
£
, Appendix G bar charts show the relationship between the raw feed concentrations
and effluent concentrations for each heavy metal. For example, the following bar chart
shows raw feed and effluent concentrations for copper in the LWS-CLF process.
teeeee
O
u
u_
O
z
O
CE
8-1
leeee
1990
199
COPPER
Raw feed
LWS-CLF process
1 2 3 4 5 6 7 8 9 10 11 1213
TEST RUN NUMBER
16
The bar charts of Appendix G are as follows:
G-l diagrams display raw feed and effluent concentrations of cadmium, copper,
chromium, nickel, and zinc for the LO-CL process
G-2 diagrams display raw feed and effluent concentrations for the LO-CLF process
G-3 diagrams display raw feed and effluent concentrations for the LSPF process
G-4 diagrams display raw feed and effluent concentrations for the LWS-CL process
G-5 diagrams display raw feed and effluent concentrations for the LWS-CLF process
The use of the graphic presentations of Appendices C and G enables rapid visual
comparisons to be made for any desired sets of the experimental results.
23
-------
SECTION 12
CAPITAL COSTS OF FULL-SCALE PLANTS
The estimated costs of installing full-scale wastewater treatment plants are given
in this section. Not included in the estimates are: land acquisition costs; sewer, road,
and other utility connection costs; preparation costs for environmental impact state-
ment; or site survey and test boring costs.
Table 7 compares the estimated capital costs of small, medium-sized, and large
plants for the five treatment processes.
Tables 8, 9, and 10 are detailed cost estimate summaries for constructing plants for
each of the five processes.
TABLE 7. SUMMARY OF PLANT CAPITAL INSTALLATION COSTS
Process
Plant
capacity
Capital costs (thousands of 1978 dollars)
LO-CL
LO-CLF
LSPF
LWS-CL
LWS-CLF
37.85 m3/day 233 237 259 255
(10,000 gal/day)
757 m3/day 799 805 892 872
(200,000 gal/day)
1,893 m3/day 1,296 1,310 1,407 1,376
(500,000 gal/day)
259
879
1,389
-------
TABLES. SMALL PLANT CONSTRUCTION
Plant capacity = 37.85 m3 (10,000 gal) per day
COSTS
Item
Capital Expense
Total
Process 1, LO-CL
Architectural
Mechanical
Electrical
Subtotal
A&Efee + CM,* 12.5%
Total
$ 42,700
139,500
19,000
$5,400
$201,200 $5,400
25,200 700
$226,400 $6,100
$ 48,100
139,500
19,000
$206,600
25,900
$232,500
Process 2, LO-CLF
Architectural
Mechanical
Electrical
Subtotal
A&Efee + CM/ 12.5%
Total
$ 43,464
141,996
19,340
$5,400
$204,800 $5,400
25,600 700
$230,400 * -$6,100
$ 48,864
141,996
19,340
$210,200
26,300
$236,500
Process 3, LSPF
Architectural
Mechanical
Electrical
Subtotal
A&E fee + CM,* 1 2.5%
Total
$ 52,100
152,300
19,000
$6,400
$223,400 $6,400
27,900 800
$251,300 $7,200
$ 58,500
152,300
19,000
$229,800
28,700
$258,500
Process 4, LWS-CL
Architectural
Mechanical
Electrical
Subtotal
A&Efee + CM,* 12.5%
Total
$ 52,100
148,800
19,000
$6,400
$219,900 $6,400
27,500 800
$247,400 $7,200
$ 58,500
148,800
19,000
$226,300
28,300
$254,600
Process 5, LWS-CLF
Architectural
Mechanical
Electrical
Subtotal
A&Efee + CM,* 12.5%
Total
$ 52,945
151,214
19,308
$6,400
$223,467 $6,400
27,933 800
$251,400 $7,200
$ 59,345
151,214
19,308
$229,867
28,733
$258,600
*A&E fee + CM = architectural and engineering fee plus central management
25
-------
TABLE 9. MEDIUM-SIZED PLANT CONSTRUCTION
Plant capacity = 757 m3 (200,000 gal) per day
COSTS
Item
Capital Expense
Total
Process 1, LO-CL
Architectural
Mechanical
Electrical
Subtotal
A&E fee + CM,* 1 2.5%
Total
$287,400
326,900
91,700
$3,800
$706,000 $3,800
88,300 400
$794,300 $4,200
$291,200
326,900
91,700
$709,800
88,700
$798,500
Process 2, LO-CL F
Architectural
Mechanical
Electrical
Subtotal
A&E fee + CM,* 12.5%
Total
$289,770
329,596
92,456
$3,800
$711,822 $3,800
88,978 400
$800,800 $4,200
$293,570
329,596
92,456
$715,622
89,378
$805,000
Process 3, LSPF
Architectural
Mechanical
Electrical
Subtotal
A&E fee + CM,* 12.5%
Total
$296,800
373,500
118,800
$3,800
$789,100 $3,800
98,600 400
$887,700 $4,200
$300,600
373,500
118,800
$792,900
99,000
$891 ,900
Process 4, LWS-CL
Architectural
Mechanical
Electrical
Subtotal
A&E fee + CM,* 12.5%
Total
$296,800
361,200
113,600
$3,800
$771,600 $3,800
96,600 400
$868,200 $4,200
$300,600
361,200
113,600
$775,400
97,000
$872,400
Process 5, LWS-CL F
Architectural
Mechanical
Electrical
Subtotal
A&E fee + CM,* 12.5%
Total
$299,074
363,967
114,470
$3,800
$777,511 $3,800
97,1 89 400
$874,700 $4,200
$302,874
363,967
114,470
$781 ,31 1
97,589
$878,900
Note: Piling costs for medium-
* A&E fee + CM = architectural
sized plants represent 12% to 16% of the total cost.
and engineering fee plus central management
26
-------
TABLE 10. LARGE PLANT CONSTRUCTION COSTS
Plant capacity = 1,893 m3 (500,000 gal) per day
Item
Capital Expense
Total
Process 1, LO-CL
Architectural
Mechanical
Electrical
Subtotal
A&E fee + CM,* 12.5%
Total
$621,800
425,200
93,900
$11,300
$1,140,900
142,600
$1,283,500
$11,300
1,400
$12,700
$633,100
425,200
93,500
$1,152,200
144,000
$1 ,296,200
Process 2, LO-CL F
Architectural
Mechanical
Electrical
Subtotal
A&E fee + CM/ 12.5%
Total
$628,343
429,674
94,872
$11,300
$1,152,889
144,111
$1,297,000
$11,300
1,400
$12,700
$639,643
429,674
94,872
$1,164,189
145,511
$1,309,700
Process 3, LSPF
Architectural
Mechanical
Electrical
Subtotal
A&E fee + CM,* 12.5%
Total
$631,200
487,000
121,000
$11,300
$1,239,200
154,900
$1,394,100
$11,300
1,400
$12,700
$642,500
487,000
121,000
$1,250,500
156,300
$1,406,800
Process 4, LWS-CL
Architectural
Mechanical
Electrical
Subtotal
A&Efee + CM,* 12.5%
Total
$631,200
464,700
115,800
$11,300
$1,211,700
151,500
$1,363,200
$11,300
1,400
$12,700
$642,500
464,700
115,800
$1,223,000
1 52,900
$1,375,900
Process 5, LWS-CLF
Architectural
Mechanical
Electrical
Subtotal
A&Efee + CM,* 12.5%
Total
$637,468
469,315
116,950
$11,300
$1,223,733
152,967
$1,367,700
$11,300
1,400
$12,700
$648,768
469,315
116,950
$1,235,033
154,367
$1 ,389,400
Note: Piling costs for large plants represent 12% to 16% of the total cost.
*A&E fee + CM = architectural and engineering fee plus central management
27
-------
SECTION 13
OPERATING COSTS OF FULL-SCALE PLANTS
GENERAL
Operating costs for three full-scale plants based on the principles of the bench-
scale plants is developed in this section. A summary of the operating costs is presented
in Table 11. Details on which the costs are based are given in Tables 12, 13, and 14.
ASSUMPTIONS USED IN THE CALCULATIONS
a. All costs are in 1978 dollars.
b. Amortization of plant cost (purchase price plus installation cost) is calculated
at 8 percent over a 12-year life.
c. Operating labor costs are $30/hr total, including basic wage, overtime, fringe
benefits, and management and overhead burden.
d. One operator working half of an 8-hr shift will be required for the smallest
plant, 37.85 m3/day (10,000 gal/day). Three part-time operators (with total
labor of 8 man-hours per day), will be required for each of the larger plants, at
757 m3/day (200,000 gal/day), and 1,893 m3/day (500,000 gal/day). A three-
shift operating schedule increases the total operating labor cost but allows a
reduction in capital equipment cost (the major cost item); the equipment can be
sized to handle one-third of the load of a single-shift operation.
TABLE 11. SUMMA RY OF OPERA TING COSTS
^~\^^ Process
Plant ^\^
capacity ^\^
LO-CL
37.85 m3/day 5.96
(10,000 gal/day) (22.57)
757 m3/day 0.90
(200,000 gal/day) (3.40)
1,893m3/day 0.55
(500 ,000 gal /day) (2.08)
Operating cost.
LO-CLF
6.00
(22.72)
0.90
(3.42)
0.55
(2.09)
$/m3 ($/
LSPF
6.24
(23.65)
0.97
(3.68)
0.60
(2.26)
1,000 gal)
LWS-CL
6.38
(24.17)
1.13
(4.30)
0.76
(2.89)
LWS-CLF
6.42
(24.32)
1.14
(4.32)
0.77
(2.90)
28
-------
e. The following items are not taken into account in this study: startup costs,
operating profit, site purchase cost, preparation costs for environmental impact
statement, sewage disposal charges, tax credits, costs of cyanide destruction in
the case of wastewaters that contain cyanides, special additives (such as
antifoaming agents), electric power costs, and laboratory chemical analysis
charges.
f. Costs of process consumables (for example, lime, sulfide) are based on the
average value of each' consumable required for the 14 wastewaters, at prices
published in Chemical Marketing Reporter for December 4, 1978 (12). These
prices are:
Sulfuric acid, 66 B£ $ if9.4I/ton
Sodium sulfite anhydrous, technical* $ 13-75/100 Ib
Lime, pebble quicklime $31.88/ton
Sodium hydrosulfide, 71 percent* $305.00/ton
Polyelectrolyte, Betz Laboratories No. 1110 $ 2.55/lb
For calculations in this report, sodium sulfite and sodium hydrosulfide are assumed to
be used in full-scale plants. Cost savings might accrue through the use of equivalent
forms of these reactants. For example, many treatment plants use sulfur dioxide
acquired in cylinders instead of sodium sulfite. Hydrogen sulfide in cylinders, though
considerably less costly ($0.24/kg of sulfur) than sodium hydrosulfide ($0.827/kg of
sulfur), would incur extensive development costs (to overcome potential mass transfer
problems) and would increase equipment costs (to preclude release to the atmosphere).
For handling convenience, sodium sulfite Na2SO3 and sodium sulfide Na2S-9H2O were
used in the laboratory.
29
-------
TABLE 12. OPERATING COSTS FOR SMALL PLANT
Plant capacity = 37.85 m^/day
(10,000 gal/day)
Equipment amortization*
Operating labor t
Chemicals t
Maintenance**
Sludge disposal Tt
Totals
LO-CL
88.15
120.00
4.35
12.00
1.16
225.66
LO-CLF
89.66
120.00
4.35
12.00
1.16
227 .17
Cost per day ($)
LSPF
98.00
120.00
5.29
12.00
1.16
236.45
LWS-CL
96,53
120.00
11.96
12.00
1.16
241.65
LWS-CLF
98.04
120.00
11.96
12.00
1.16
243.16
* Equipment amortization tt
(LO-CL) $232,500 x
(LO-CLF) 236,500 x
(LSPF) 258,500 x
(LWS-CL) 254.600 x
(LWS-CLF) 258,600 x
0.1326957 350 days
0.1326957 350 days
0.132695 7 350 days
0.132695 7350 days
0.132695 7 350 days
$88.15 pur day
89.66 per day
98.00 per day
96.53 per day
98.04 per day
t Operating labor: $30/hr x 4 hr/day = $120.00 per day
Chemicals
Sulfuricacid: 290 mg/L x $0.0507/kg x 37.85 m3/day
Sodium sulfite: 120 mg/L x $0.280/kg x 37.85 m3/day
Lime (LO and LSPF): 2,090 mg/L x $0.032/kg x 37.85 m3/day =
Lime (LWS): 1.635 mg/L x $0.032/kg x 37.85 m3/day
IMaHS (LWS): 260 mg/L x $0.827/kg x 37.85 m3/day
NaHS(LSPF): 30 mg/L x $0.827/kg x 37.85 m3/day
Polyelectrolyte: 0.8 mg/L x $5.62/kg x 37.85 m3/day
Total chemical cost per day
"Maintenance: 10% of operating labor cost = $12.00 per day
ttSludge disposal: 1 m3/month at $35/m3 = $1.16 per day
ttCapital cost x 0.132695 = annual repayment for annuity, 8%, 12 years (11).
Cost
LO-CL,
LO-CLF
0.55
1.21
2.43
-
-
- ,
0.16
$4.35
per day
LSPF
0.55
1.21
2.43
—
—
0.94
0.16
$5.29
($)
LWS-CL.
LWS-CLF
0.55
1.21
—
1.90
8.14
—
0.16
$11.96
30
-------
TABLE 13. OPERATING COSTS FOR MEDIUM-SIZED PLANT
Plant capacity = 757 m^/day
. (200.000 gal/day)
Equipment amortization*
Operating labor t
Chemicals 4
Maintenance**
Sludge disposaltt
! Totals
Cost per day ($)
LO-CL
302.73
240.00
90.96
24.00
23.20
680.89
LO-CLF
305.20
240.00
90.96
24.00
23.20
683.36
LSPF
338.14
240.00
109.74
24,00
23.20
735.08
LWS-CL
330.75
240.00
242,66
24.00
23.20
860.61
LWS-CLF
333.22
240.00
242.66
24.00
23.20
863.08
* Equipment amortization tt
(LO-CL) $798,500 x
(LO-CLF) 805.000 x
(LSPF) 891.900 x
(LWS-CL) 872.400 x
(LWS-CLF) 878,900 x
0.132695/350 days
0.132695 7350 days
0.132695/350 days
0.132695/350 days
0.132695/350 days
$302.73 per day
305.20 per day
338.14 per day
330.75 per day
333.22 per day
t Operating labor: $30/hr x 8 hr/day = $240 per day
Chemicals
Sulfuric acid: 290 mg/L x $0.0507/kg x 757 m3/day
Sodium suitite: 120 mg/L x $0_280/kg x 757 m3/day
Lime (LO and LSPF);. 2,090 mg/L x $0.032/kg x 757 m3/day =
Lime (LWS): 1,635 mg/L x $0.032/kg x 757 m3/day
NaHS(LWS): 260 mg/L x $0.827/kg x 757 m3/day
NaHS (LSPF): 30 mg/L x $0.827/kg x 757 m3/day
Polyelectrolyte: 0.8 mg/L x $5.62/kg x 757 m3/day
Total chemical cost per day
Cost per day
LO-CL, LSPF
LO-CLF
11.17
25.54
50.83
-
-
_
3.42
$90.96
11.17
25.54
50.83
-
-
18.78
3.42
$109.74
($)
LWS-CL.
LWS-CLF
11.17
25.54
-
39.76
162.77
-
3.42
$242.66
1 Maintenance: 10% of operating labor cost = $24.00 per day
ttSludge disposal: 20 m3/month at $35/m3 = $23.20 per day
ttCapital cost x 0.132695 = annual repayment for annuity, 8%, 12 years (11).
31
-------
TABLE 14. OPERATING COSTS FOR LARGE PLANT
Plant capacity = 1,893 m3/day
( 500,000 gal/day)
Equipment amortization*
Operating labor t
Chemicals t
Maintenance**
Sludge disposal tt
Totals
LO-CL
491.43
240.00
226.19
24.00
58.00
1,039.62
LO-CLF
496.54
240.00
226.19
24.00
58.00
1,044.73
Cost per day ($)
LSPF
533.36
240.00
273.16
24.00
58.00
1,128.52
LWS-CL
521.64
240.00
605.70
24.00
58.00
1,444.69
LWS-CLF
526.76
240.00
605.70
24.00
58.00
1,450.21
* Equipment amortization tt
(LO-CL) $1,296,200 x
(LO-CLF) 1,309,700 x
(LSPF) 1,406,800 x
(LWS-CL) 1,375,900 x
(LWS-CLF) 1,389,100 x
0.132695/350 days
0.1326957 350 days
0.132695/350 days
0.132695/350 days
0.132695/350 days
$491.43 per day
496.54 per day
533.36 per day
521.64 per day
526.76 per day
t Operations labor: $30/hr x 8hr/day = $240 per day
t Chemicals
Cost per day ($)
Sulfuric acid: 290 mg/L x $0.0507/kg x 1,893 m3/day
Sodium sulfite: 120 mg/L x $0.280/kg x 1,893 m3/day
Lime (LO and LSPF): 2,090 mg/L x $0.032/kg x 1,893 m3/day
Lime (LWS): 1,635 mg/L x $0.032/kg x 1,893 m3/day
NaHS (LWS): 260 mg/L x $0.827/kg x 1,893 m3/day
NaHS (LSPF): 30 mg/L x $0.827/kg x 1,893 m3/day
Polyelectrolyte: 0.8 mg/L x $5.62 x 1,893 m3/day
Total chemical cost per day
LO-CL,
LO-CLF
27.79
63.50
126.40
-
-
-
8.50
LSPF
27.79
63.50
126.40
-
-
46.97
8.50
LWS-CL,
LWS-CLF
27.79
63.50
—
98.88
407.03
-
8.50
$226.19 $273.16 $605.70
** Maintenance: 10% of operations labor cost = $24,00 per day
tt Sludge disposal: 50 m3/month, $35/m3 = $58.00 per day
tiCapital cost x 0.132695= annual repayment for annuity, 8%, 12 years (11),
-------
SECTION 1*
ELECTRON PHOTOMICROGRAPHS OF SLUDGES
A few of the sludges obtained from actual wastewaters and from laboratory-made
dilute solutions that contain copper ions were examined at magnifications up to 50,000x.
At low magnifications, the sludges invariably appeared amorphous. Only when magnifi-
cations greater than 10,000x were employed could any structure be seen. At this power,
the sludges showed a granular appearance, with particles about 0.1 to 0.5 /zm in
diameter. No difference could be observed between sludges generated by lime alone and
those generated by lime with sulfide.
The results of these exploratory photomicrographs did not suggest that further work
would be particularly fruitful. Accordingly, research in this direction was discontinued.
Figure 8 shows a typical high-power (46,500x) electron photomicrograph of a
iime-with-sulfide sludge.
33
-------
,
•
rn
r
:
•
i
;
'\
,
,
-------
SECTION 15
SLIDE AND CASSETTE TAPE PRESENTATION
A 35-mm color slide presentation with accompanying synchronized cassette tape
narration is available on request.
The 38-slide presentation lasts about 20 min. It describes the background of sulf ide
precipitation of heavy metals and the purpose of the program; it contains photographs of
the bench-scale equipment; it includes a condensed table of results plus the conclusions
drawn from the program.
The slides are standard 35-mm, 2-in by 2-in format, and the narration is on a two-
track tape cassette with sound on one channel and a 1,000-Hz slide-advance pulse on the
other. Suitable equipment for viewing includes (but is not restricted to) a Kodak
Ektographic projector and a Wollensak Model 2570 AV tape player.
Inquiries regarding the slide presentation should be addressed to Dr. H. B. Durham,
Industrial Environmental Research Laboratory, Office of Research and Development,
U.S. Environmental Protection Agency, Cincinnati, Ohio 45268.
35
-------
SECTION 16
CONFIDENCE LEVELS OF THE CHEMICAL ANALYSES
GENERAL
The primary objective of this program is to document the relative abilities of the
five processes to remove heavy metals from wastewater, so the accuracy and reliability
of the chemical analyses are of fundamental importance. Accordingly, considerable time
and effort were devoted to testing the reproducibility of the results obtained by
chemical analysis.
ANALYSIS OF EPA STANDARDS
Two solutions of composition known only to the EPA were supplied to test the
accuracy of Boeing analyses. The results for the seven principal metals of interest to
the EPA are detailed in Table 15. All Boeing analyses were within the acceptance limits
designated by the EPA.
\
STATISTICAL REPEATABILITY TESTS
Two 12L samples of a treated wastewater (Run 5, LO-CL and LO-CLF) were
analyzed three times over (on three separate days) by the two atomic absorption
methods, flame and flameless, to give a total of six analyses for each of the five heavy
metals tested in this study. Tables 16 and 17 show the results.
Table 18 gives the calculated limits within which the true concentrations would be
expected to fall, with a 90-percent confidence level, for 99 percent of a series of
estimations, based on 8.97 standard deviations (13).
i
The remaining conclusions drawn from the repeatability tests are that:
a. A statistically significant reduction exists at the 0.975 confidence level in the
filtered, compared with the unfiltered, samples;
b. A significant difference exists at the 0.95 confidence level between the flame
and flameless methods so that, in order to compare metal levels, the same
method should be used for both metals being estimated.
36
-------
TABLE 15. ANALYSIS OF EPA STANDARDS
Solution 1
Cug/L)
Metal
Cd
Cr
Cu
Hg
Ni
Pb
Zn
Boeing
analysis
12
79
55
1.5
107
79
71
EPA
actual
10
60
40
3.0
70
80
60
EPA
acceptance
limits
2.84 to 18.0
2 1.2 to 93.6
4.53 to 85.3
0 to 7. 19
21.4 to 119
30.3 to 132
23.8 to 105
Boeing
analysis
65
237
334
2.0
279
381
388,
Solution 2
fofl/U
EPA
actual
70
250
350
8.0
300
400
400
EPA
acceptance
limits
47.5 to 85.8
102 to 368
267 to 415
Oto 17.6
161 to 452
185 to 608
206 to 61 2
TABLE 16. EFFLUENT FROM LO-CL PROCESS
Flame method
Flameless method
-------
SECTION 17
CONSULTANT'S REPORT
Consultant: Dr. D. Bhattacharyya
Department of Chemical Engineering, University of Kentucky
Industries engaged in metal finishing or metal production operations use large
quantities of contact process water, and the spent process wastewater (rinse water)
streams contain heavy metals, such as Cu, Cd, Pb, Zn, Ni, Cr, Sn, Ag, and cyanides.
Although hydroxide (lime) precipitation of heavy metals, followed by settling, is the
process that is used most often to treat industrial wastewaters, the amphoteric nature of
some precipitates [ M (OH)2 (ppt) + OH~ ^ M (OH)^ ] , settling problems, and the
presence of complexing agents may reduce metal removal efficiency. With sulfide
precipitation, the high reactivity of sulfides (S=, HS~, H2S) with heavy metal ions and
the very low solubility of heavy metal sulfides over a broad pH range are attractive
features when this process is compared to the corresponding hydroxide precipitation
process. The optimum sulfide dosage and pH adjustments depend, of course, on the
wastewater characteristics.
Although heavy metals can be precipitated with soluble sulfide salts (Na2S or NaHS)
or with sparingly soluble metal sulfides (such as FeS), the use of FeS often requires
higher than stoichiometric dosages. The Boeing Company conducted extensive
experimental investigation of the soluble sulfide process and lime precipitation process
with various industrial metal finishing (anodizing, metal cleaning, printed circuit etching,
and several types of electroplating) wastewaters.
A side-by-side comparison of continuous-flow sulfide precipitation and hydroxide
precipitation processes has not been reported previously in the literature. Sulfide
precipitation experiments were conducted in the pH 8.0 to 9.0 range. Lime precipitation
with settling followed by sulfide precipitation and filtration (LSPF process) and a
combined lime-sulfide-settling-filtration (LWS-CLF) process were consistently better
than the hydroxide processes. In several cases (moderate Zn and Cu concentration in the
influent), lime precipitation-settling followed by filtration (to remove fine precipitates)
was also highly effective in removing heavy metals from the wastewaters. The
precipitation results also indicated that with several wastes (higher concentrations), the
lime precipitation process produced sludge volumes 1.3 to 1.9 times higher than the LWS
(sulfide) process.
Sulfide precipitation was considerably better than the lime precipitation process for
waste number 12, which contained a high concentration of Zn (440 mg/L), in the presence
of ammonium ion, and for waste number 9, which contained 24 mg/L Cu and 99 mg/L Ni
at a high pH of 11.it (high pH may indicate presence of complexing agents). Table 19
shows the Zn removals (waste No. 12) obtained with various precipitation processes.
With waste number 9, both Cu and Ni removals are considerably better with the sulfide
processes, as shown in Table 20.
38
-------
TABLE 19. ZINC fiEMOVAL FROM WASTE NO. 12
pH
8.5
9.0
Zinc removal (%}
LO-CL
83.0
91.5
LO-CLF
84.1
93.4
LSPF
89.9
99.5
LWS-CL
99.4
99.8
LWS-CLF
99.0
TABLE 20. METAL REMOVAL FROM WASTE NO. 9
Metal removal (%)
IV1GLC1I
Copper
Nickel
yn
8.8
8.8
LO-CL
58.3
83.5
LO-CLF
66.7
87.8
LSPF
" 99.7
98.8
LWS-CL
89.2
92.9
LWS-CLF
98.3
95.8
For all the wastewaters studied, although LSPF and LWS-CLF gave similar effluent
quality, the sulfide polishing (LSPF) process would be preferred on the basis of
considerably lower sulfide dosage (thus lower sulfide chemical cost) requirements. With
the LSPF process, two separate reaction stages would be required. The total operating
costs (NaHS as sulfide) with the LSPF process would be 5 to 9 percent higher than the
conventional lime precipitation process.
Although the sulfide precipitation studies conducted at Boeing were at pH 8 to 9,
the sulfide precipitation of heavy metals is highly effective even at lower pH values.
Among the heavy metals, HgS has the lowest solubility, and ZnS and NiS have the highest
solubility. The precipitates' solubility sequence is HgS < CuS < CdS < PbS < ZnS <
NiS. Hg, Cu, Cd, and Pb can be precipitated with sulfide (Na2S or NaHS) even at pH 3>
without any H2S gas formation. Effective precipitation of Zn and Ni occurs at pH > 6.
Sulfide precipitation is quite effective, even in the acidic pH; thus, selective metal
recovery and the obtaining of effluent water of low calcium content (for possible water
recycling because no lime may be required) are possible.
A full-scale sulfide precipitation process (Na2S as sulfide source) with a capacity of
1.0 x 106 gallons per day is operating at Boliden Metall Corporation of Sweden to treat
smelter (Cu, Pb, Zn smelting) wastewaters. One copper smelter in Japan has a sulfide
precipitation process to recover heavy metals as sulfides. A New Hampshire aluminum
company operates a chrome removal treatment system with FeCl3 and Na2S to remove
both hexavalent and trivalent Cr. The Permutit Company and Holley Carburetor
Division of Colt Industries demonstrated the use of the sulfide process (Sulfex process
uses freshly prepared FeS by reacting NaHS with FeSO4) at Paris, Tennessee, and
obtained effluent waters containing Cr and Zn at less than a 0.05-mg/L level. An
extensive bench-scale study involving lime-sulfide precipitation of heavy metals and
arsenic from smelter (Cu) wastewaters is also in progress at the University of Kentucky.
-------
REFERENCES
1. Schlauch, R.M., and A. Epstein, Treatment of Metal Finishing Wastes by Sulfide
Precipitation. EPA report number EPA-600/2-77-049, Feb. 1977, IERL, U.S.
Environmental Protection Agency, Cincinnati, Ohio 45268, 86 pp.
2. Suliex Heavy Metals Waste Treatment Process, Technical Bulletin, Vol. 13, No. 6,
Code 4413.2002, Oct. 1976, The Permutit Company, E. 49 Midland Avenue, Paramus,
N.3. 07652, 4 pp.
3. Scott, M.C., Sulfex—A New Process Technology for Removal of Heavy Metals from
Waste Streams, Paper presented at Purdue Industrial Waste Conference, May 10,
1977, The Permutit Company, Inc., Paramus, N.3. 07652, 18 pp.
4. Anderson, Cranbury, and Weiss, Patent No. 3,740,331, Method for Precipitation of
Heavy Metal Sulfides, 3une 19, 1973
5. Patterson and Minear, Wastewater Treatment Technology, Illinois Institute of Tech-
nology report number IIEQ 71-4, Illinois Institute of Technology, Chicago, 111., Aug.
1971
6. Water Pollution Control for Metal Machining, Fabricaton, and Costing Operations,
prepared for the U.S. Environmental Protection Agency Technology Transfer
Program by Centec Consultants, Inc., 11800 Sunrise Valley Drive, Reston, Va. 22091,
May 1977, 180 pp.
7. Considine, et al., Process Instruments and Controls Handbook, McGraw-Hill Book
Company, New York, N.Y., 1974, pp. 6.85-6.87
8. Standard Methods for the Examination of Water and Wastewaters, 13th Edition,
1971, p. 337, American Public Health Association, 1015 18th St. N.W., Washington,
D.C. 20036
9. Nilsson, R., Removal of Metals by Chemical Treatment of Municipal Waste Water,
Water Research, Pergamon Press, Elmsford, N.Y., 1971, Vol. 5, pp. 51-60
10. Hartinger, L., Metallkomplexe in der Abwassertechnik, Galvanotechnik D.7698,
Eugen G. Leuze Verlog, Postfach 8, Saulgau, Wurttemberg, Germany, 1975, No. 5,
pp. 366-373
11. Gushee, C.H., Financial Compound Interest and Annuity Tables, Boston Financial
Publishing Company, p. 884
<
12. Chemical Marketing Reporter, December 4, 1978, Schnell Publishing Company, 100
Church St., New York, NY 10007, p. 68
40
-------
13. Rickmers, A.D., and H.N. Todd, Statistics, An Introduction, McGraw-Hill Book
Company, New York, N.Y., 1967, Ch. 18, "Non-Parametric Statistics," pp. 386-407
14. Development Document for Proposed Effluent Limitation Guidelines, Effluent
Guidelines Division, U.S. Environmental Protection Agency, Washington, D.C. 20406,
Aug. 1973, EPA-440/1-73-003, Fig. 6, p. 65
15. Stumm, Werner, "Chemical Interaction in Particle Separation," Environmental
Science and Technology, Vol. 11, No. 12, Nov. 1977, pp. 1066-1070
16. Bowker and Lieberman, Engineering Statistics, Prentice-Hall, 1960, Sec. 8.12 and
Table 8.2
-------
APPENDIX A
CASE HISTORY DATA OF 16 TEST RUNS
The test runs are arranged in this appendix in the order of increasing electrical
conductivity of the raw feed. Each case history includes data on the wastewater sample
raw feed analysis, processed effluent analysis, process consumables, and sludge volume.
The data were generated from 14 wastewater samples that represented nonferrous
metal smelting, electroplating, anodizing, cleaning, and etching operations. Samples
came from industrial plant sources across the United States. Each wastewater sample
was used in a test run at a pH value selected as an optimum for precipitation of its heavy
metals. Two samples were tested at a second pH value where doubt existed as to the
true optimum pH value.
-------
TEST RUN 1
Description of wastewater: Rinse from copper printed circuit etching and copper
deposition (electrolytic and electroless)
Source area: Seattle, Washington
Treatment process details*
Precipitation pH for
lime-only and lime-
with-sulfide processes
8.5
Chemical analysis
Measurement
Cd
Cr (total)
Cu
Ni
Zn
PH
Conductivity*
Color
Cr6+
Hg
Pb
Ag
Sn
Sludge volumet
LO: <2
LWS: < 2
Process consumables (mg/L)
H2S04 for Cr6+ reduction:
IMa2S03 for Cr^+ reduction:
CaO for LO process:
S for LWS process:
S for LSPF process:
120
31
86
18
3.5
(all values except conductivity and pH in jug/L)
Before-
raw feed
8
215
2.3 x 103
209
770
5.2
115
colorless
73
<1
192
<3
3.3 x 103
Value after
LO-CL LO-CLF
2 «1
203 3
1.8x103 200
217 86
430 53
185 17
1 1
308 139
treatment by process of*:
LSPF LWS-CL
«1 1
2 215
67 1.9 x103
77 209
14 424
15 192
1 1
348 432
LWS-CLF
«1
6
5
88
13
13
1
279
* Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
t Volume per volume, percentage after 1 hr settling
t jumho/cmat 18.5°C
-------
TEST RUN 2
Description of wastewater: Rinse from electroplating
Source area: Portland, Oregon
Treatment process details*
Precipitation pH for lime-
only and lime-with-sulfide
processes
Sludge volume
Process consumables (mg/L)
8.5
LO: <2
LWS: < 2
H2S04 for Cr6+ reduction: 264
Na2S03 for Cr6+ reduction: 132
CaO for LO process: 132
S for LWS process: 1
S for LSPF process: 1
Chemical analysis (all values except conductivity and pH in jug/L)
Measurement
Cd
Cr (total)
Cu
Ni
Zn
pH
Conductivity'*
Color
Cr6+
Fe
Hg
Before—
raw feed
LO-CL
268 179
949 459
87 59
19 18
112 100
8.0
217
colorless
396
408 56
<1
Value after treatment by process of*:
LO-CLF LSPF LWS-CL LWS-CLF
22 23 139 19
15 29 484 57
24 14 36 8
18 8 16 7
20 10 78 10
12 20 150 21
*Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
t Volume per volume, percentage after 1 hr settling
at 17°C
-------
TEST RUN 3
Description of wastewater: Rinse from electroplating and metal finishing by carburetor
manufacturer
Source area: Warren, Michigan
Treatment process details"
Precipitation pH for lime-
only and lime-with-sulfide
processes
Sludge volume t
Process consumables (mg/L)
8.75
Chemical analysis
Measurement
Cd
Cr (total)
Cu
Ni
Zn
PH
Conductivity
Color
Cr6+
Hg
Pb
Ag
Sn
H2SO4 for Cr6+ reduction:
L0: 24 Na2S03 for Cr6+ reduction:
CaO for LO process:
LWS: 19 S for LWS process:
Sfor LSPF process:
(all values except conductivity and pH in Mg/D
R , Value after treatment by process of*:
raw feed |_0-CL LO-CLF LSPF LWS-CL
4
200 x103 1,060 76 56 437
30 22 22 14 7
106 10 ~ 17 8 4
90x103 1,000 210 10 490
4.5
550
yellow
91 x 103
<1
<25
20
1.2 x103 <2 <2 <2 <2
370
610
290
43
25
LWS-CLF
58
5
4
15
<2
'Process code: LO = jime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
t Volume per volume, percentage after 1 hr settling
tjumho/cm at 18.5°C
-------
TEST RUN 4
Description of wastewater: Rinse from anodizing and electroplating
Source area: Minneapolis, Minnesota
Treatment process details*
Precipitation pH for lime-
only and lime-with-sulfide
processes
9.0
Chemical analysis
Measurement
Cd
Cr (total)
Cu
Ni
Zn
PH
Conductivity*
Color
Cr6+
Pb
Ag
Sn
(all values except
Rpfnrp • LJ
raw feed
400
12.6 x103
800
3.2 x103
11x103
7.05
700
pale yellow
10.4 x 103
17
29
350
Sludge volume ^
LO: <4
LWS: <4
conductivity and pH in /zg/L)
Value after
LO-CL LO-CLF
98 11
2,200 178
69 20
467 69
2,145 167
<5
12 <2
3 3
215 155
Process consumables (mg/L)
H2S04 for Cr6+ reduction:
Na2S03 for Cr6+ reduction:
CaO for LO process:
Sfor LWS process:
S for LSPF process:
treatment by process of*:
LSPF LWS-CL
16 55
237 957
18 40
102 350
331 1,200
<5 <5
<2 6
3 3
185 169
140
200
20
1
0.5
LWS-CLF
29
470
24
197
560
3
3
213
* Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
t Volume per volume, percentage after 1 hr settling
* jumho/cm at 21°C
-------
TEST RUN 5
Description of wastewater: Rinse from anodizing and electroplating
Source area: Lincoln, Nebraska
Treatment process details*
Precipitation pH for lime-
only and lime-with-sulfide
processes
Sludge volume t
Process consumables (mg/L)
10.5
Chemical analysis
Measurement
Cd
Cr (total)
Cu
Ni
Zn
pH
Conductivity*
Color
Hg
Pb
Ag
Sn
CN
LO: 6
LWS: 4
(all values except conductivity and pH
Before -
raw feed LO-CL
9 3
18 18
24 12
789 125
33 6
7.1
1,320
colorless
<10
211 1
600 2
280 40
1 x 103
H2S04 for Cr6+ reduction : 0
Na2S03 for Cr6+ reduction: 0
CaO for LO process: 98
S for LWS process: 19
S for LSPF process: 14
in Mg/L)
Valu • after treatment by process of*:
LO-CLF LSPF LWS-CL
<3 <3 <3
12 14 9
864
100 100 69
335
1
232
36 131 103
LWS-CLF
<3
13
5
111
5
2
228
*Process'code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
t Volume per volume, percentage after 1 hr settling
t/imho/cm at 22°C
-------
TEST RUN 6
Description of wastewater: Rinse from electroplating
Source area: Cleveland, Ohio
Treatment process details51
Precipitation pH for lime-
only and lime-with-sulfide
processes
Sludge volume
Process consumables (mg/L)
8.5
LO: 5
LWS. 6
H2S04 for Cr6+ reducti on: 339
Na2S03 for Cr6+reduction: 25
CaO for LO process: 145
S for LWS process: 91
S for LSPF process: 67
Chemical analysis (all values except conductivity and pH in jug/L)
Measurement
Cd
Cr (total)
Cu
Ni .
Zn
PH
Conductivity*
Color
Fe
Pb
Ag
Before-
raw feed
<40 <1
1.7x103 109
21 x 103 1,300
119x103 12x103
13x103 625
7.1
1,500
pale green
2
13 7
6
Value after treatment by process of*:
LO-CLF
<1
39
367
9.4 x103
10
<2
5
LSPF LWS-CL
<1 <1
20 187
1 1 2,250
5.3 x103 11x103
5 192
<2 5
3 4
LWS-CLF
<1
17
169
3.5 x103
8
<2
3
*Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
t Volume per volume, percentage after 1 hr settling
t/zmho/cm at 21 °C
-------
TEST RUN 7
Description of wastewater: Rinse from anodizing and electroplating
Source area: Kent, Washington
Treatment process details*
Precipitation pH for lime-
only and lime-with-sulfide
processes
Sludge volume t
Process consumables (mg/L)
9.25
Chemical analysis
Measurement
Cd
Cr (total)
Cu
Ni
Zn
pH
Conductivity *
Color
Hg
Pb
Ag
Sn
(all values except
Before-
raw feed
76
8.5 x103
1.3 x103
944
131
10.6
4,400
yellow
<10
45
44
460
H2S04 for Cr6+ reduction : 972
L0"- 14 Na2S03 for Cr6+ reduction: 211
LWS. 14 CaO for LO process: 389
S for LWS process: 1
S for LSPF process: 1
conductivity and pH in /ug/L)
Value after treatment by process of*:
LO-CL LO-CLF LSPF LWS-CL LWS-CLF
27 16 22 25 20
318 65 139 295 239
244 236 143 212 166
80 49 49 349 250
46 42 40 35 24
15 14 43 23 13
19 11 9 9 8
<10 <10 <10 <10 <10
*Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
f Volume per volume, percentage after 1 hr settling
tjumho/cmat 22°C
-------
TEST RUN 8
Description of wastewater: From a nonferrous metal smelter settling pond fed by water
from a flue gas zinc extractor and by scrubber water from
copper-phosphorus process
Source arear Perth Amboy, New Jersey
Treatment process details'*
Precipitation pH for lime-
only and lime-with-sulfide Sludge volume
processes
8.5
Chemical analysis
Measurement
Cd
Cr (total)
Cu
Ni
Zn
pH
Conductivity
Color
As
Cr6+
Hg
Pb
Ag
Sn
Se
LO: 41
LWS: 29
(all values except conductivity and pH
Before-
raw teed
LO-CL
15x103 80
1 00 1 00
7x103 39
123 40
114x103 511
2.2
4,700
colorless
1.4 x103 54
<4
<1
5x103 38
1
5x 103
<1x103 44
Process consumables (mg/L)
H2SO4 for Cr6+ reduction:
Na2SO3 for Cr6+ reduction:
CaO for LO process:
S for LWS process:
Sfor LSPF process:
in M9/L)
Value after treatment by process of*:
LO-CLF LSPF LWS-CL
7 4 50
23 5 3
0.14 14 38
26 106 108
30 36 309
38 40 44
3 3 27
40 36 44
0
0
1,004
60
4
LWS-CLF
2
2
6
115
15
49
2
44
*Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
t Volume per volume, percentage after 1 hr settling
t Atmho/cmat19°C
50
-------
TEST RUN 9
Description of wastewater: Rinse from electroplating
Source area: Los Angeles, California
Treatment process details'
Precipitation pH for lime-
only and lime-with-sulfide
processes
Sludge volume'''
Process consumables (mg/L)
H2S04 for Cr6+ reduction:
LO : < 2 Na2SO3 for Cr6+ reduction :
8-75 CaO for LO process:
LWS: <2 c, .....
S for LWS process:
Sfor LSPF process:
2,420
97
515
190
65
Chemical analysis (all values except conductivity and pH in /ug/L)
Measurement
Cd
Cr (total)
Cu
Ni
Zn
pH
Conductivity*
Color
Hg
Ag
CN
_ , Value after treatment by process of*:
Before-
raw feed LO-CL LO-CLF LSPF LWS-CL LWS-CLF
<100 97 71 3 12 8
310 40 25 33 90 48
24x103 10x103 8x103 73 2.6 x103 400
99x103 16x103 12x103 1.2 x103 7.0 x103 4.2 x103
253 x 103 400 295 8 567 9
11.4
5,500
yellow
<0.1
4
31 x 103
*Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
t Volume per volume, percentage after 1 hr settling
tjum ho/cm at 19°C
51
-------
TEST RUN 10
Description of wastewater: Rinse from electroplating
Source area: Chicago, Illinois
Treatment process details*
Precipitation pH for
lime-only and lime- Sludge volume*
with-sulfide processes
10.0
Chemical analysis
Measurement
Cd
Cr (total)
Cu
Ni
Zn
PH
Conductivity
Color
Fe
Hg
Ag
Sn
LO: 43
LWS: 37
(all values except conductivity and pH in p.g/L)
Before- Value after
raw feed
LO-CL LO-CLF
58x103 1,130 923
5x103 138 103
2x103 909 943
3x103 2.2 x 103 2.3 x103
290 x103 1.2 x103 510
2.4
5,600
colorless
740 x103 2x103 334
<0.3 <0.3 <0.3
14 14 10
5x103 129 81
Process consumables (mg/L)
H2SO4 for Cr6+ reduction:
Na2S03 for Cr6+ reduction:
CaO for LO process:
S for LWS process:
Sfor LSPF process:
treatment by process of*:
LSPF LWS-CL
<10 26
37 49
929 60
2.6 x103 1.8 x103
12 216
305 563
<0.3 <0.3
8 7
71 71
0
41
2,680
400
141
LWS-CLF
<10
50
160
1.9 x103
38
229
<0.3
7
71
*Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
t Volume per volume, percentage after 1 hr settling
at 19°C
52
-------
TEST RUN 11
Description of wastewater: Rinse from aluminum cleaning, anodizing, and electroplating
Source area: Auburn, Washington
Treatment process details*
Precipitation pH for lime-
only and lime-with-sulfide
processes
Sludge volume
Process consumables (mg/L)
8.5
Chemical analysis
Measurement
Cd
Cr (total)
Cu
Ni
Zn
PH
Conductivity
Color
Pb
LO: 18
LWS: 16
H2SO4 for Cr6+ reduction : 0
Na2SO3 for Cr6+ reduction : 226
CaO lor LO process: 1 ,530
S for LWS process: 8
S for LSPF process: 1
(all values except conductivity and pH in pig/L)
Before-
raw feed inn
45 15
163x103 3,660
4.7 x103 135
185 30
2.8 x103 44
1.7
10,600
yellow
119 119
Value after treatment by process of*:
LO-CLF LSPF LWS-CL LWS-CLF
8 20 11 7
250 159 1,660 68
0.33 3 82 18
38 18 33 31
10 11 26 2
88 120 104 59
*Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified ;CLF = clarified and filtered
t Volume per volume, percentage after 1 hr settling
* Mm ho/cm at 22°C
53
-------
Treatment process details
TEST RUN 12*
Description of wastewater: Rinse from electroplating
Source area: Chicago, Illinois
t
Precipitation pH for
lime-only and lime- Sludge volume* Process consumables (mg/L)
with-sulfide processes
8.5
Chemical analysis
Measurement
Cd
Cr (total)
Cu
Ni
Zn
pH
Conductivity**
Color
Hg
Pb
Ag
Sn
NH4
LO: 20 H2S04 for Cr6+ reduction: 0
Na2S03 for Cr6+ reduction : 0
LWS: 10 CaO for LO process: 760
LSPF: 2 S f or LWS process: 260
S f or LSPF process: 108
(all values except conductivity and pH in /ug/L)
_, , Value after treatment by process of *:
Pf.fnre—
raw feed L0.CL LO-CLF LSPF LWS-CL LWS-CLF
34 20 20 1 1 1
3
20 8 0.8 3 1 1
64 42 42 42 34 50
440 x103 75x103 71x103 4.7 x 103 2.5 x103 4.6 x 103
6.4
12,100
colorless
<10
45 15 17 17 22 15
61 4 4555
200 <10 <10 <10 <10 <10
tt
* Test runs 12 and 13 were made with the same raw feed wastewater: run 12 at pH = 8.5 and run 13 at pH = 9.0
t Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
+ Volume per volume, percentage after 1 hr settling
** Aimho/cm at 25°C
tt Qualitative tests indicated the presence of significant amounts of ammonium
54
-------
TEST RUN 13*
Description of wastewater: Rinse from electroplating
Source area: Chicago, Illinois
Treatment process details|t
Precipitation pH for lime-
only and lime-with-sulfide sludge volume * Process consumables (mg/L)
processes
9.0
Chemical analysis (all
Measurement
Cd
Cr (total)
Cu
Ni
Zn
PH
Conductivity**
Color
Hg
Pb
Ag
Sn
IMH4
LO:
LWS:
values except conductivity and
Before—
raw feed LO_C|_
34 21
3
20 7
64 29
440 x 103 37x103
6.4
12,100
colorless
<10
45 13
61 4
200 <10
tt
H2S04 for Cr6+Veduction:
Na^SOg for Cr reduction :
*CaO for LO process:
~~ S for LWS process:
Sfor LSPF process:
pH in jug/L)
Value after treatment by process of .
LO-CLF LSPF LWS-CL
21 1 1
842
29 31 72
29x103 2x103 730
-
14 13 9
4 4 1
<10 <10 <10
0
0
911
-
LWS-CLF
1
1
34
600
11
3
<10
* Test runs 12 and 13 were made with the same raw feed wastewater: run 12 at pH = 8.5 and run 13 at pH - 9.0
t Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
* Volume per volume, percentage after 1 hr settling
**jumho/cm at 25°C
tt Qualitative tests indicated the presence of significant amounts of ammonium
55
-------
TEST RUN 14"
Description of wastewater: Rinse from electroplating
Source area: Atlanta, Georgia
Treatment process details
Precipitation pH for
lime-only and lime-
with-sulfide processes
Sludge volume'
Process consumables (mg/L)
8.5
LO: 59
LWS: 53
H2SO4 for Cr6+reduction: 0
Na2SO3 for Cr6+ reduction: 156
CaO for LO process: 5,009
S for LWS process: 995
S for LSPF process: 16
Chemical analysis
Measurement
Cd
Cr (total)
Cu
Ni
Zn
pH
Conductivity
Color
Fe
Hg
Pb
Ag
(all values except
Before-
raw feed
1.4 x103
10.3 x103
900
35x103
930 x 103
1.2
75,000
brown
415x 103
1
500
64
conductivity and
LO-CL
432
34
28
1,000
9.6 x 103
19 x 103
16
<2
pH in jug/L)
Value after
LO-CLF
360
5
28
750
1.4 x 103
1.5 x 103
17
<2
treatment by
LSPF
70
9
7
96
340
1.5 x 103
16
<2
process of ^:
LWS-CL LWS-CLF
No tests run. The extremely
high sulfide demand would
make a full-scale process
uneconomical.
'
* Test runs 14 and 15 were made with the same raw feed wastewater: run 14 at pH = 8.5 and run 15 at pH = 10.0
t Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
£ Volume per volume, percentage after 1 hr settling
*;umho/cm at 23°C
56
-------
TEST RUN 15 *
Description of wastewater: Rinse from electroplating
Source area: Atlanta, Georgia
Treatment process details
t
Precipitation pH for
lime-only and lime-
with-sulfide processes
Sludge volume
Process consumables (mg/L)
H2SO4 for Cr6+ reduction:
LO: 62 Na2S03 for Cr6+ reduction:
10.0 LWg. 4g CaO for LO process:
S for LWS process:
Sfor LSPF process:
0
156
5,428
1,400
8
Chemical analysis (all values except conductivity and pH in
Measurement
Cd
Cr (total)
Cu
Ni
Zn
PH
Conductivity**
Color
Fe
Hg
Pb
Ag
Before-
raw feed
1.4 x103
10.3 x103
900
35x103
930 x 103
1.2
75,000
brown
415 x 103
1
500
64
LO-CL
73
19
10
35
3.3 x103
2.0 x 103
17
<2
Value after treatment by
LO-CLF LSPF
66
22
8
21
1.0 x 103
1.6 x 103
15
<2
process of ' :
LWS-CL LWS-CLF
No tests run. The extremely
high sulfide demand would
make a full-scale process
uneconomical.
*Test runs 14 and 15 were made with the same raw feed wastewater: run 14 at pH = 8.5 and run 15 at pH - 10.0
Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
Volume per volume, percentage after 1 hr settling
*>mho/cm at 23°C
-------
TEST RUN 16
Description of wastewater: Rinse from electroplating
Source area: Glendale, California
Treatment process details*
Precipitation pH for lime-
only and lime-with-sulfide Sludge volume t
processes
1st stage*: 6.2
2d stage*: 9.0
Chemical analysis
Measurement
Cd
Cr (total)
Cu
Ni
Zn
PH
Conductivity**
Color
Cr6+
Hg
Ag
. . 78
(LO: 23
LWS: 13
(all values except conductivity and pH in /ug/L)
Before- Value after
raw feed LQ Cj_ LQC]_f
58 7 12
6.3 xlO3 4 2
1.1x103 860 848
160 30 34
650 x103 2.8 x103 2.3 x103
1.2
149,000
colorless
<5 <1 <1
<1
16
Process consumables (mg/L)
H0SOA for Cr6+ reduction:
6+
Na2S03forCr reduction:
CaO for LO process:
Sfor LWS process:
Sfor LSPF process:
treatment by process of*:
LSPF LWS-CL
<5 <5
3 5
132 13
34 33
242 104
<1 <1
0
31
14,380
381
LWS-CLF
<5
7
13
23
19
<1
*Process code: LO = lime only; LSPF = lime, sulfide polished and filtered; LWS = lime with sulfide;
CL = clarified; CLF = clarified and filtered
tVolume per volume, percentage after 1 hr settling
t Because of the exceptionally large volume of sludge generated by this wastewater,
precipitation was carried out in two stages
* Vn ho/cm at 20°C
58
-------
APPENDIX B
ANALYTICAL METHODS
Chemical analyses were made for the following elements, compounds, and values
using the following methods:
a. Arsenic and selenium—Furnace atomic absorption spectroscopy, Some Applica-
tions of the IL 751 Atomic Absorption Spectrophotometer, Engineering and
Applications Staff, Instrumentation Laboratory Inc., Wilmington, Maine 01887
b. Cadmium, total chromium, copper, nickel, zinc, lead, silver, tin, iron:
1. For levels >50 jug/L: Flame atomic absorption method on samples concen-
trated by boiling, Methods for Chemical Analysis of Water and Waste, U.S.
Environmental Protection Agency
2. For levels <50 jug/L: Flameless atomic absorption method, Instrumenta-
tion Laboratory Inc., Analytical Instrument Division, 3onspin Road,
Wilmington, Maine 01887
c. Conductivity—Conductivity meter, YSI Model 33 S-C-T, Yellow Springs Instru-
ment Co. Inc., Yellow Springs, Ohio 45387
d. Cyanide—Measurement by specific ion electrode, Orion Research Analytical
Methods Guide, 7th Edition, May 1975
e. Hexavalent chromium—Diphenylcarbazide colorimetric procedure, Standard
Methods, 13th Edition, p. 426
f. Mercury—Manual cold vapor technique, Methods for Chemical Analysis of
Water and Waste, U.S. Environmental Protection Agency
g. Sludge volume determination—Visual measurement of treated sample in
graduated cylinder after 1 hour settling. Sludge volumes are expressed in terms
of the volume occupied by the sludge as a percentage of the total volume
treated.
59
-------
APPENDIX C
COMPARISON PLOTS OF FIVE METAL
CONCENTRATIONS FOR ALL SAMPLES
The comparison plots show results from five processes using cadmium, copper,
chromium, nickel, and zinc effluent metal concentrations for all wastewater samples.
Each point plotted in the diagrams has two coordinates: the concentration of a
metal in the process A effluent (x-axis) and the concentration of the same metal in the
process B effluent (y-axis). A point below the 45-deg line results when there is a higher
concentration of the metal in process A effluent; if all the points are below the line,
process A is clearly less effective in removing that metal than process B. For example,
the copper diagram in Figure C-l shows that the LO-CL process is less effective in
removing copper than the LSPF process for all I** wastewaters except one. The cadmium
diagram in Figure C-l shows no obvious advantage for either the LO-CL or LSPF process
for removing cadmium.
60
-------
lee ,
1888
CONCENTRATION OF CADMIUM
FOR LO-CL PROCESS
CONCENTRATION OF COPPER
FOR LO-CL PROCESS (ng/L)
5
O
iee
Oco
OQ
1-0
DC0-
t-u.
Zfc
UjtO
o-1
zee
oo
Ou-
CHROMIUM
10 lae 1880
CONCENTRATION OF CHROMIUM
FOR LO-CL PROCESS (ng/D
CONCENTRATION OF NICKEL
FOR LO-CL PROCESS (/jg/L)
CONCENTRATION OF ZINC
FOR LO-CL PROCESS
C-1. Comparison of LO-CL process and LSPFprocess using Cd, Cu Cr, Ni,
and Zn effluent metal concentrations for all wastewater samples.
61
-------
I 0000
10000
100 1000
CONCENTRATION OF CADMIUM
FOR LO-CLF PROCESS (fig/L)
i 10 100 1000 10000
CONCENTRATION OF COPPER
FOR LO-CLF PROCESS (Mg/L)
10000 .
—; 1000
,[2 100
CHROMIUM
1 10 100 1000
CONCENTRATION OF CHROMIUM
FOR LO-CLF PROCESS 0*g/L)
100000
1 10 100 1000 10000
CONCENTRATION OF NICKEL
FOR LO-CLF PROCESS (jiig/L)
1 10 100 1900 10000 100000
CONCENTRATION OF ZINC
FOR LO-CLF PROCESS (Mg/L)
Figure C-2. Comparison of LO-CLF process and LO-CL process using Cd, Cu, Cr,
Ni, and Zn effluent metal concentrations for all wastewater samples.
62
-------
tee
2
Is
O o»
u.3
O w
zffi
Oo
H O
<£
EC Q-
I- u.
Z 0-
ui«g
O -1
z cc
OO
O il-
CADMIUM
i ie lee
CONCENTRATION OF CADMIUM
FOR LWS-CL PROCESS (jug/D
ie lee leee
CONCENTRATION OF COPPER
FOR LWS-CL PROCESS (/jg/L)
lee
O i
u.3
HO
-------
g
I- Q.
§0
o -1
Z DC
O O
OU. i
CADMIUM -
CONCENTRATION OF CADMIUM
FOR LWS-CL PROCESS
i ie lee teee
CONCENTRATION OF COPPER
FOR LWS-CL PROCESS i
03
13
"-S8
Ouj
O -1
z tn
O O
O U- !
CHROMIUM
i te lee teee
CONCENTRATION OF CHROMIUM
FOR LWS-CL PROCESS (jig/L)
O D>
~
O in
z o
lg
I- Q-
o -
Z (T
O O
O u.
NICKEL
i ie 168 leee
CONCENTRATION OF NICKEL
FOR LWS-CL PROCESS
N ~
O LU
Z O
lg
H Q.
te
}- O
U
Z DC
O O
O u-
ZINC
CONCENTRATION OF ZINC
FOR LWS-CL PROCESS (/ug/D
Figure C-4. Comparison of L WS-CL process and LO-CLFprocess using Cd, Cu, Cr,
Ni, and Zn effluent metal concentrations for all waste water samples.
-------
08
I- 0
go
o -1
z cc
o o
O u.
100
1
CADMIUM-
i 10 tee
CONCENTRATION OF CADMIUM
FOR LWS-CLF PROCESS (jig/L)
i ta leo ieea
CONCENTRATION OF COPPER
FOR LWS-CLF PROCESS
i 10 ie>8
CONCENTRATION OF CHROMIUM
FOR LWS-CLF PROCESS Ijig/L)
10 iee 1000 10000
CONCENTRATION OF NICKEL
FOR LWS-CLF PROCESS (M9/D
1 10 100 1000 10000
CONCENTRATION OF ZINC
FOR LWS-CLF PROCESS (M9/L)
Figure C-5. Comparison of LO-CLF process and LWS-CLF process using Cd, Cu, Cr,
Ni, and Zn effluent metal concentrations for all wastewater samples.
65
-------
190 ,
U. uj
O O 19
CADMIUM
o -
z cc
00
O u.
ie 100 leee
CONCENTRATION OF CADMIUM
FOR LO-CL PROCESS
-------
1000
o —
ii f>
": t/>
O LLJ
Z O
O -
z cc
o o
(J LL
10
CADMIUM
1 19 100
CONCENTRATION OF CADMIUM
FOR LSPF PROCESS (M9/L)
1 10 166 1000
CONCENTRATION OF COPPER
FOR LSPF PROCESS
1000 .
O _i
X ™
O ~ 100
O uj
lg
h- 0.
< IL 10
o -1
Z DC
O O
O u. 1
CHROMIUM
1 10 180 1000
CONCENTRATION OF CHROMIUM
FOR LSPF PROCESS
100002
100000
N ~
S«
O tu
1000 (
o -
z cc
o o
O u.
1 10 100 1000 10600
CONCENTRATION OF NICKEL
FOR LSPF PROCESS (fig/L)
ZINC
1 10 100 1000 10000
CONCENTRATION OF ZINC
FOR LSPF PROCESS (»ig/L)
Figure C-7. Comparison of LSPF process and LO-CLF process using Cd, Cu, Cr, Ni,
and Zn effluent metal concentrations for all wastewater samples.
67
-------
iooo
CONCENTRATION OF CADMIUM
FOR LWS-CLF PROCESS (/ig/L)
i 10 100
CONCENTRATION OF COPPER
FOR LWS-CLF PROCESS (/ufl/L)
1000
i 10 100 1000
CONCENTRATION OF CHROMIUM
FOR LWS-CLF PROCESS
10000
o
^
N "
u.
O m
7 03
^ "J
o o
H O
-------
5
53
9 »
< a.
U. C/J
O ui
U
z cc
00
O u.
CADMIUM
CONCENTRATION OF CADMIUM
FOR LWS-CLF PROCESS
CONCENTRATION OF COPPER
FOR LWS-CLF PROCESS (Mg/L)
i 10 100 iiioc1
CONCENTRATION OF CHROMIUM
FOR LWS-CLF PROCESS (»ig/U
10000
5 3
N —
I- Q.
< _1
F9
Z IT
O O
O u.
CONCENTRATION OF NICKEL
FOR LWS-CLF PROCESS
ZINC
10 109 1'XX' 10000
CONCENTRATION OF ZINC
FOR LWS-CLF PROCESS
C-S. Comparison of L WS-CLF process and L WS-CL process using Cd, Cu, Cr,
Ni, and Zn effluent metal concentrations for all wastewater samples.
69
-------
S3
51
Si
z
'«•
o ,M
o -1
z cc
o o
O U.
iee
CONCENTRATION OF CADMIUM
FOR LWS-CL PROCESS (/ug/L)
iee ieee leeee
CONCENTRATION OF COPPER
FOR LWS-CL PROCESS (/jg/L)
ime
o_
EC -I
5s
28
DC-J
Z DC
00
O u.
iee
CHROMIUM
iee
CONCENTRATION OF CHROMIUM
FOR LWS-CL PROCESS (ng/L)
w
oc_i IM
o-1
Z DC
8S
NICKEL i
i IB iee leee
CONCENTRATION OF NICKEL
FOR LWS-CL PROCESS
o -1
Z DC
o o
o u.
ZINC
i le iee leee
CONCENTRATION OF ZINC
FOR LWS-CL PROCESS (jug/L)
C-10. Comparison of LWS-CL process and LO-CL process using Cd, Cu, Cr,
Ni, and Zn effluent metal concentrations for all wastewater samples.
70
-------
APPENDIX D
SIGN TEST STATISTICAL ANALYSIS
Sign test statistical analyses were performed to establish a hierarchy (charted in
Figure D-l) to rank the five wastewater treatment processes. The hierarchy was based
on cadmium, copper, chromium, nickel, and zinc effluent concentration data from the 16
test runs.
The hierarchy was established by successively selecting and comparing two proc-
esses to determine if the pair gave significantly different results and then ranking the
processes accordingly. For example, the LSPF process was compared to the LWS-CL
process. For each of the 16 test runs, a set of five matched pairs was established by
pairing the Cd effluent concentration of the LSPF process with the Cd effluent
concentration of the LWS-CL process; the Cu effluent concentration of the LSPF
process with the Cu effluent concentration of the LWS-CL process; and similarly, for Cr,
Ni, and Zn. Thus, a set of about 80 matched pairs was established for the sign test.
They were used to determine which two processes produce significantly different
effluent concentration levels. Successive pairs of processes were compared until the
hierarchy chart (Figure D-l) was completely established.
The results of the sign test analyses on sets of matched pairs are shown in Figures
D-2 through D-l 1.
LARGEST REDUCTION
IN HEAVY METALS
UJ
e> <
Z tL
UJ
111
u- 2
— O
LSPF * LWS-CLF
LO-CLF * LWS-CL
Based on Cd, Cu, Cr, Ni,
and Zn effluent concen-
tration data and analyzed
at 75-percent confidence
level
LO-CL
SMALLEST REDUCTION
IN HEAVY METALS
Figure D-1. Hierarchy of wastewater treatment processes established from
sign test statistical analysis.
71
-------
PAIRED DIFFERENCES
(LO-CL FROM LO-CLF)*
1 O +
.
; - i>g y| 1
i i
"IHUUU
r
i _j
• Number of positive differences:
• Number of negative differences:
• Computed Z-statistic:
• Tabled Z-value:
7
59
6.278
1.150
20 40 60
MATCHED-PAIR NUMBER
80
100
Figure D-2. Agreement between LO-CLF and LO-CL not significant
at 75-percent confidence level.
PAIRED DIFFERENCES
(LO-CL FROM LSPF)*
I O +
-
- - -y — - u|| - -- -
1 1 1
\
1 1
• Number of positive differences:
• Number of negative differences:
• Computed Z-statistic:
• Tabled Z-value:
6
63
6.742
1.150
20 40 60
MATCHED-PAIR NUMBER
80
100
Figure D-3. Agreement between LSPF and LO-CL not significant
at 75-percent confidence level.
coo
si*
UJ-1
teg
mO n
££ °
OIL
Q_l
Sv
ccto
<§
Q
- If"
U U «
1 1
uurir
TJ
i i
• Number of positive differences:
• Number of negative differences:
• Computed Z-statistic:
• Tabled Z-value:
10
47
4.768
1.150
20 40 60
MATCHED-PAIR NUMBER
80
100
Figure D-4. Agreement between L WS-CL and L WS-CL F not significant
at 75-percent confidence level.
' Differences between effluent concentrations (Cd, Cu, Cr, Ni, and Zn) of paired processes
72
-------
Si
QU.
29 -
CCU)
II
UJ Z~.
OU-
JLO.
Number of positive differences:
Number of negative differences:
Computed Z-statistic:
Tabled Z-value:
20 40 60
MATCHED-PAIR NUMBER
80
100
Figure D-5. Agreement between LO-CLF and LWS-CL significant
at 75-percent confidence level.
l_l_ *;£ A
QU.
29.
cc w
CL -— •
II III
"II
II
u
1 |
P-r
uiy-«(r
Rn
§ i i
• Number of positive differences:
• Number of negative differences:
• Computed Z-statistic:
• Tabled Z-value:
20 40 60
MATCHED-PAIR NUMBER
80
100
Figure D-6. Agreement between LSPF and LWS-CL not significant
at 75-percent confidence level.
29
35
0.625
1.150
19
42
2.817
1.150
mi.
IU-J
QU-
29 -
f£CO
II
20 40 60
MATCHED-PAIR NUMBER
80
• Number of positive differences: 52
• Number of negative differences: 13
• Computed Z-statistic: 4.713
• Tabled Z-value: 1.150
100
Figure D-7. Agreement between LO-CL and LWS-CL not significant
at 75-percent confidence level.
Differences between effluent concentrations (Cd, Cu, Cr, Ni, and Zn) of paired processes
73
-------
C/JU.
LU _|
00
ito
• Number of positive differences:
• Number of negative differences:
• Computed Z-statistic:
• Tabled Z-value:
7
58
6.202
1.150
20 40 60
MATCHED-PAIR NUMBER
80
100
Figure D-8. Agreement between LWS-CLF and LO-CL not significant
at 75-percent confidence level.
Ou-
"DC
Qu-
I
• Number of positive differences:
• Number of negative differences:
• Computed Z-statistic:
• Tabled Z-value:
45
18
3.276
1.150
20 40 60
MATCHED-PAIR NUMBER
80
100
Figure D-9. Agreement between LO-CLF and LSPF not significant
at 75-percent confidence level.
*
t/5 )
LU O
IFFERENC
FROM LO-
o +
Qu.
Q-i -
QjO
DCW
<§
Q
~
. n nil
L
i i i i i
0 20 40 60 80 1C
• Number of positive differences:
• Number of negative differences:
• Computed Z-statistic:
• Tabled Z-value:
45
19
3.125
1.150
MATCHED-PAIR NUMBER
Figure D-10. Agreement between LO-CLF and LWS-CLF not significant
at 75-percent confidence level.
* Differences between effluent concentrations (Cd, Cu, Cr, Ni, and Zn) of paired processes
-------
col-
tu u.
UJ -1
CCS
tl 0
Qu.
DC W
si
20 40 60
MATCHED-PAIR NUMBER
80
• Number of positive differences: 30
• Number of negative differences: 31
• Computed Z-statistic: 0.000
• Tabled Z-value: 1.150
100
Figure D-11. Agreement between LSPF and L WS-CLF significant
at 75-percent confidence level.
* Differences between effluent concentrations (Cd, Cu, Cr, Ni, and Zn) of paired processes
-------
APPENDIX E
WILCOXON MATCHED-PAIR, SIGNED-RANK STATISTICAL ANALYSIS
The Wilcoxon matched-pair, signed-rank statistical method (13) was used to estab-
lish the hierarchy chart (Figure E-l) to rank the five wastewater treatment processes.
The hierarchy was based on cadmium, copper, chromium, nickel, and zinc effluent
concentration data from the 16 test runs.
The hierarchy was established by determining if a pair of processes gave signif-
icantly different results. The processes were ranked accordingly. For example, the
LSPF process was compared to the LWS-CL process. For each of the 16 test runs, a set
of five matched pairs was established by pairing the Cd effluent concentration of the
LSPF process with the Cd effluent concentration of the LWS-CL process; the Cu
effluent concentration of the LSPF process with the Cu effluent concentration of the
LWS-CL process; and similarly, for Cr, Ni, and Zn. Thus, a set of about 80 matched
pairs was established for the Wilcoxon method. They were used to determine which two
processes produced significantly different effluent concentration levels, based on the
T-value reported in Table E-l.
The signed ranks indicated that the LSPF process produced lower effluent concen-
tration levels than those of the LWS-CL process. Thus, the LSPF process was ranked
above the LWS-CL process on the hierarchy chart. If the two processes did not produce
significantly different results, the processes would have had the same rank on the
hierarchy chart, as in the comparison of the LSPF process to the LWS-CLF process.
Successive pairs of processes were compared until the hierarchy chart (Figure E-l) was
completely established.
76
-------
LARGEST REDUCTION IN
HEAVY METALS
LU t/J
D 2
-I O
to w
< u
HI Z
DC O
O U
SMALLEST REDUCTION IN
HEAVY METALS
LSPF = LWS-CL
LO-CLF = LWS-CL
LO-CL
Based on Cd, Cu, Cr, Ni,
and Zn effluent concen-
tration data and analyzed
at 95-percent confidence
level
Figure E-1. Hierarchy of wastewater treatment processes established from
Wilcoxon matched-pair, signed-rank statistical analysis (ref. 13).
TABLE E- 7. T VALUES OF WILCOXON MA TCHED-PAIR, SIGNED-RANK
STATISTICAL ANALYSIS
T-value calculated from
Comparison experimental data (smaller
pair sum of like-signed ranks) •*
LO-CL and LO-CLF
LSPF and LWS-CL
LO-CL and LWS-CL
LSPF and LWS-CLF
LWS-CL and LWS-CLF
LO-CLF and LSPF
LO-CLF and LWS-CL
LO-CLF and LWS-CLF
108
411
401
868
195
385
848
495
Tn^g-value required for a
significant difference at
95% confidence level t
848
717
821
717
620
643
794
794
Significant difference
at 95% confidence level
Yes
Yes
Yes
No
Yes
Yes
No
Yes
* Includes data for only cadmium, copper, chromium, nickel, and zinc heavy metals,
t When the T-value calculated from the experimental data exceeds the Tg^-value, the
two processes are not significantly different at the 95% confidence level,
77
-------
APPENDIX F
CAPITAL COST OF FULL-SCALE PLANTS
The full-scale plants outlined in this appendix were used to provide the basis for
capital equipment cost comparisons. The plants do not include cyanide destruction
systems or hexavalent chromium reduction systems; such processes would be a cost
burden on all five processes. This appendix includes plant schematics, layout drawings,
and construction details.
LIST OF FIGURES
F-l Small LO-CL and LO-CLF plant schematic
F-2 Small LSPF, LWS-CL, and LWS-CLF plant schematic
F-3 Medium-sized LO-CL and LO-CLF plant schematic
F-4 Medium-sized LSPF plant schematic
F-5 Medium-sized LWS-CL and LWS-CLF plant schematic
F-6 Large LO-CL and LO-CLF plant schematic
F-7 Large LSPF plant schematic
F-8 Large LWS-CL and LWS-CLF plant schematic
F-9 Small plant layout-all processes (LO-CL, LO-CLF, LSPF, LWS-CL,
and LWS-CLF)
F-10 Medium-sized LO-CL and LO-CLF plant layout
F-ll Medium-sized LSPF plant layout
F-12 Medium-sized LWS-CL and LWS-CLF plant layout
F-13 Large LO-CL and LO-CLF plant layout
F-l4 Large LSPF plant layout
F-15 Large LWS-CL and LWS-CLF plant layout
F-16 Cross section of medium-sized and large plants—all processes (LO-CL, LO-CLF,
LSPF, LWS-CL, and LWS-CLF)
ENGINEERING SPECIFICATIONS FOR SMALL PLANTS
(Figures F-l, F-2, and F-9)
A. The leveling storage tank will hold a minimum of one day's effluent and will be acid-
resistant. This provides for batch processing, which is the most economical method
for this flow rate.
B. The mixer-clarifier tank will hold the same amount of effluent as tank A. Tank B is
to be acid-resistant lined and will also contain an acid-resistant coated mixer. For
convenient sludge removal, this tank must have a tapered bottom with a view-port
for observation of the sludge bed level. Manually controlled pH levels are tested in
the lab. Sulfide and H2S levels are controlled manually as determined by an
automatic H2S gas detector. Upon completion of sludge removal to the filter press,
item C, the effluent is discharged in the following manner: to the sewer (LO-CL
78
-------
process); to the filter (LO-CLF process); to the aerator (LWS-CL process); and to
the filter and aerator (LSPF and LWS-CLF processes).
C. The filter press dewaters the sludge to 60-percent moisture content. Means for
sludge removal are to be provided.
D. The aerator is used to oxygenate the effluent before discharge; the rate depends
upon system size.
E. The filter is a manifold type for small particulate removal.
F- An automatic audible alarm must be installed in the process area to signal when
tank levels are too high and to detect H2S gas.
G. Flow control should be kept to specifications for efficient operation.
H. An instrument control panel must be easily accessible to the operator and centrally
located to the treatment area. Instruments installed on the panel must include the
following:
H.I. On-off control of all pumps.
H-2. Indicators of water levels in each tank, including a yellow light for above-
normal levels and a red emergency light for critical water levels.
H.3. A flow diagram of the treatment plant process with lights that indicate
equipment operation status: green for equipment operating and valves in
normal position, red for equipment "off" and valves redirecting flow, plus
flashing red for automatic pump switchover.
I. For the lab, sufficient equipment must be provided to perform pH titrations and
sulfide and H2S detection.
J. Adequate storage space (to be as safe as reasonable) must be provided for all needed
process chemicals.
K. For emergency and safety provisions, a sump should be provided, with the tank farm
curbed off in case of accident. Emergency lights must be provided for the control
panel and for the process area.
L. Automatic switchover must be provided for all pumps in case of failure. The pump
between tanks A and B should be acid-resistant.
M. All valves are manual, with one acid-resistant valve before tank A.
N. Acid-resistant pipe is to be provided wherever it may contact untreated wastewater.
Flow rate is assumed to be as indicated in system specifications. An allowance for
equipment for double-pump automatic switchover was not taken into account. All pumps
have been located in the storage area to avoid exposure to weather, thus contributing to
ease of maintenance and increased reliability. Because of the low flow rate, this is a
batch process. The lab is to be used to determine the pH level and the amount ot sullide
needed. The amount of polymer needed can also be determined; for this, proper
equipment should be provided.
79
-------
ENGINEERING SPECIFICATIONS FOR MEDIUM-SIZED AND LARGE PLANTS
(Figures F-3 through F-8 and F-10 through F-16)
A. The lagoon is based on a 2.13m (7-ft) depth because of elevation and tidal conditions
at a proposed site. An acid-resistant coating is to be installed to protect the lagoon
in case of treatment plant breakdown. The use of support pilings around and within
the lagoon is suggested. This provides for the construction of a deck covering the
lagoon, except for a grate that surrounds the treatment plant proper.
B. The deck should be constructed to support the weight of the treatment plant. The
area directly under the plant should be constructed to withstand at least 4,880
kg/m2 (1,000 lb/ft2), and the remaining area, at least 488 kg/m2 (100 lb/ft2).
C. The treatment plant includes the following:
C.I The leveling tank is to be lined with an acid-resistant coating. This is the first
stop for the plant wastewater, unless the wastewater is directed to the lagoon.
C.2 The flash mixer is to be lined with an acid-resistant coating; the mixing blade
is to be coated also. A roof, having H2S detectors, should be provided for the
flash mixer.
C.3 The lime store area is an elevated tank for unslaked lime; the raised position
provides for easy transport to the C-2 area. The tank is to be attached to the
control room building for added support.
C.3.1 The lime slaker mixes fresh, slaked lime and water and passes this
lime slurry to a slurry tank. (The manufacturer-supplied system
includes pumps, pipes, and slaker.)
C.3.2 The lime slurry tank is used for continuous flow to either tank B or
recycle. (The manufacturer-supplied system includes pumps, tank, and
piping up to, and including, the valve.) The valve must be electrically
operated for control by the pH system.
C.3.3 The pH control area is to contain the pH control machinery (automatic
and manual). This includes pH level monitors, controllers, and record-
ers. The pH sensors are to be located on the pipe leading to tank B
from tank A and on the line leaving tank B.
C.4 The polymer feed area includes the mixer, tank, and pipes up to and including
the pumps; this is a continuous process at a designated flow.
C.5 The flocculating tank receives flow from tank B and the polymer feed system.
The tank located on top of the clarifier, is arranged so that overflow will
cascade into the clarifier.
C.6 The clarifier is furnished by the manufacturer and receives flow from the
flocculator and the filter press. The sludge contracted at the clarifier bottom
flows to the sludge storage tank (tank H) by a pump. The clarifier overflow
drains into the sewer.
C.6.1 Clarifier overflow goes to the aerator, tank K, by gravity feed (for
sulfide treatment system only).
C.6.2 Clarifier overflow goes to the aerator, tank 3-3, by gravity feed (for
sulfide polish system only).
80
-------
C-7 The sludge storage tank is designed to hold a day-to-day supply of sludge for
batch processing by the filter press, according to the recommended procedure.
C.8 The filter press is a manufactured item that can process a 2-day supply of
sludge in 12 hr. Means for sludge removal are to be provided. Removed water
is recirculated to the clarifier; this flow can also be directed to the lagoon for
dilution or complete reprocessing. Sludge is dewatered to 60-percent moisture
content.
C.9 The sulfide feed system is supplied by the manufacturer; it includes tank,
motors, pumps, and pipe up to and including the valve (to be electrically
operated). (The system is for sulfide treatment and sulfide polish systems
only.)
C.9.1 The sulfide control area is to contain the sulfide control machinery
(automatic and manual); this includes monitors, controllers, and
recorders. Free-sulfide and H2S level sensors should be installed:
C.9.1.a On the pipe between tanks A and B, and between tanks B
and C (for sulfide treatment system only);
C.9.1.b On the line between tanks G and 3-3, and between tanks 3-3
and L (for sulfide polish system only).
C.9.2 The sulfide slurry tank is a mixer and should have H2 S gas detection
equipment installed around it. The tank receives flow from the
clarifier and sulfide feed tank, which feeds to a filter (manifold type).
(The tank is for the sulfide polish system only.)
C.10 The aerator oxygenates the effluent before discharge. The rate depends on
system size. (For sulfide treatment and sulfide polish systems only.)
C.ll The filter is a manifold type for small particulate removal to be discharged
into the aerator. (For the sulfide polish system only.)
D. An audible alarm and an automatic process water detour are needed. An audible
signal must be installed in the process area to sound when the water in the tanks
reaches critical levels, when the pH level is too acid for the process, or when H2 S
gas is detected. The main valve at the plant process water inlet must automatically
detour process water to the lagoon.
E. The flow control should be kept to specifications for efficient operations.
F. An instrument control panel must be easily accessible to the operator and centrally
located to the treatment equipment. Instruments installed on the panel must
include the following:
F.I On-off control of all pumps.
F.2 Indicators of water levels in each tank, including a yellow light for above-
normal levels and a red emergency light for critical water levels.
F.3 A flow diagram of the treatment plant process with lights that indicate
equipment operating status: green for equipment operating and valves in
normal position, red for equipment "off" and valves redirecting flow, plus
flashing red for automatic pump switchover. Remote indicators must be
provided for all pH and sulfide readings and for H2S gas monitors.
81
-------
G. Adequate storage space is to be allotted for all chemical storage in safe, controlled
areas as near as practical to the location of use.
H. For emergency and safety provisions, the plant must contain the following:
H.I Backup dust equipment must be provided, including switching, valves, and
controls to operate properly.
H.2 Emergency lights must be displayed on the control panel and in the manu-
facturing process area as described under indicators (F.2).
I. For pumps, automatic switchover must be provided in case of failure. Some pumps
should be as acid-resistant as possible, depending on their location in the system.
J. All necessary safety valves should be included. The valve on the effluent receiving
side of tank A should be electrically operated and as acid-resistant as possible, or
coated; the same holds true for the valve on the outlet side of tank A.
K. All pipe that will contact untreated wastewater is to have an acid-resistant liner
and, in the case of lagoon pipes, an acid-resistant coating.
Flow rate is assumed to be as indicated in system specifications. Allowance for
equipment for double-pump automatic switchover was not taken into account. All pumps
have been located in the storage area to avoid exposure to weather, thus contributing to
ease of maintenance and increased reliability.
INFLUENT,
37.85 m3
(10,000 gal)
PER DAY
(NONCHROMATE,
NONCYANIDE)
TANK,
45.42 m3
(12,000 gal)
TANK,
45.42 m3
(12,000 gal)
PUMP,
0.15 m3/min
(40 gal/min)
PUMP,
0.38 m3/min
(100 gal/min)
SLUDGE
FILTER
PUMP,
0.38 m3/min
(100 gal/min) (CLF SYSTEM ONLY)
PUMP,
0.15 m3/min
(40 gal/min)
Plant capacity = 37.85 m3 (10,000 gal) per day
FILTER
SLUDGE
TO SEWER
Figure F-1. Small LO-CL and LO-CLF plant schematic.
82
-------
INFLUENT,
37.85 m3
(10,000 gal)
PER DAY
(NONCHROMATE,
NONCYAIMIDE)
TANK,
45.42 m3
(12,000 gal)
(12,000 gal)
PUMP
0.15m3/min
(40 gal /mini
PUMP,
0.38 m3/min
(100 gal/min)
• Plant capacity = 37.85 m3 (10,000 gal) per day
PUMP,
0.38 m3/min
(100 gal/mini
PUMP,
0.15m3/min
(40 gal/mini
SLUDGE
Omit filter for
LWS-CL system
Figure F-2. Small LSPF, L WS-CL, and L WS-CLF plant schematic.
83
-------
Plant capacity = 757 m3 (200,000 gal) per day
Lagoon
Leveling tank
Lime feed
Flash mixer
Polymer feed
Flocculating tank
Clarifier
Sludge filter press
763 m3 (201,600 gal)
31.8m3 (8,400 gal)
0.95 L/min (0.25 gal/min)
5.3 m3( 1,400 gal)
5.3 L/min (1.4 gal/min)
2.65 m3 (700 gal)
72.5 m2 (780 ft2)
0.3 m3 (10.8 ft3) per day,
60% moisture
INFLUENT,
757m3
(200,000 gal)
PER DAY
(NONCHROMATE,
NONCYANIDE)
LAGOON
LU
LEVELING TANK
LIME FEED SYSTEM
~l
i-1 RECYCLE
U I—I C2?;5°l
itj—M> m . TTT "~i
nwn ! iBiSg/
kh !: T
pH CONTROL
POLYMER FEED
n i SCUM
FLOCCULATING TANK
FILTER
(CLF SYSTEM ONLY)
CLARIFIER
CONTINUOUS FLOW RECORDER ft SAMPLER
TO SEWER OR STREAM
EAR EFFLUENT |
HEAVY 5LU06E FILTER PRESS
SLUDGE STORAGE
D
I
TRUCK OR PUMP TO LAGOON
Figure F-3. Medium-sized LO-CL and LO-CLF plant schematic.
-------
Plant capacity = 757 m3 (200,000 gal) per day
Lagoon
Leveling tank
Lime feed
Flash mixer
Polymer feed
Flocculating tank
Clarifier
Sludge filter press
Aerator
- 763 m3 (201,600 gal)
- 31.8 m3 (8,400 gal)
- 0.95 L/min (0.25 gal/min)
- 5.3 m3( 1,400 gal)
- 5.3 L/min (1.4 gal/min)
- 2.65 m3 (700 gal)
- 72.5 m2 (780 ft2)
- 0.3 m3 (10.8 ft3) per day,
60% moisture
- 0.9g (0.002 Ib) per minute
of 02
INFLUENT,
757m3
(200,000 gal)
PER DAY
(NONCHROMATE
NONCYANIDE)
SULFIDE FEED SYSTEM
0.3 L/min (0.08 gal/min)
LIME FEED
SYSTEM
AERATOR
POLYMER FEED
CONTINUOUS HOW RECORDER I SAMPLER
TO SEWER OR STREAM
FILTER PRESS
SLUDGE STORAGE
TRUCK OR PUMP TO LAGOON
Figure F-4. Medium-sized LSPF plant schematic.
85
-------
Plant capacity = 757 m3 (200,000 gal) per day
Lagoon
Leveling tank
Lime feed
Flash mixer
Polymer feed
Flocculating tank
Clarifier
Sludge filter press
Aerator
763 m3 (201,600 gal)
31.8m3 (8,400 gal)
0.95 L/min (0.25 gal/min)
5.3 m3< 1,400 gal)
5.3 L/min (1.4 gal/min)
2.65m3 (700 gal)
72.5 m2 (780 ft2)
0.3 m3 (10.8ft3) per day,
60% moisture
0.9g (0.002 Ib) per minute of C>2
INFLUENT,
757m3
(200,000 gal)
PER DAY
(NONCHROMATE,
NONCYANIDE)
SULFIDE FEED
SYSTEM, 1.25
L/min (0.33 gal/min)
LINEFEED
SYSTEM
a LI
CLARIFIERj UBHTSLUBBgW-^ J
FILTER
(CLF SYSTEM ONLY)
AERATOR
SLUDGE STORAGE
TO SEWER OR STREAM
TRUCK OR PUMP TO LAGOON
Figure F-5. Medium-sized LWS-CL and LWS-CLFplant schematic.
86
-------
Plant capacity = 1,893 m3 (500,000 gal) per day
Lagoon
Leveling tank
Lime feed
Flash mixer
Polymer feed
Flocculating tank
Clarifier
Sludge filter press
1,908 m3 (504,000 gal)
79.5 m3 (21,000 gal)
2.5 L/min (0.66gal/min)
13.25 rr>3 (3,500 gal)
13.25 L/min (3.5gal/min)
6.6 m3 (1,750 gal)
182m2(l,960ft2)
0.8m3(27ft3)perday,
60% moisture
LIME FEED SYSTEM
INFLUENT,
1,893 m3
(500,000 gal)
PER DAY
(NONCHROMATE,
NONCYANIDE)
LEVELING TANK
POLYMER FEED
|f turn
FLOCCULATING TANK 1
CLARIFIER
[CLEAR EFFLUENT \ |
I I I SETTLING TANK
FILTER
(CLF SYSTEM ONLY)
TO SEWER OR STREAM
HEAVY SLU06E FILTER PRESS
I II SLUDGE STORAGE
|
TRUCK OR PUMP TO LAGOON
Figure F-6. Large LO-CL and LO-CLF plant schematic.
87
-------
Plant capacity = 1,893 m3 (500,000 gal) per day
Lagoon
Leveling tank
Lime feed
Flash mixer
Polymer feed
Flocculating tank
Clarifier
Sludge filter press
Aerator
1,908 m3 (504,000 gal)
79.5m3 (21,000 gal)
2.5 L/min (0.66 gal/min)
13.25m3 (3,500 gal)
13.25 L/min (3.5 gal/min)
6.6 m3( 1,750 gal)
182m2(1,960ft2)
0.8 m3 (27 ft3) per day,
60% moisture
2.7g (0.006 Ib) per minute
of 02
LAGOON
INFLUENT,
1,893 m3
(500,000 gal)
PER DAY
(NONCHROMATE,
NONCYANIDE)
LINEFEED
SYSTEM
LEVELING TANK
SULFIDE FEED SYSTEM.
0.8 L/min (0.21 gal/min)
AERATOR
TO SEWER OR STREAM
FILTER PRESS
SLUDGE STORAGE
TRUCK OR PUMP TO LAGOON
Figure F-7. Large LSPF plant schematic.
88
-------
Plant capacity = 1,893 fr»3 (500,000 gal) per day
Lagoon
Leveling tank
Lime feed
Flash mixer
Polymer feed
Flocculating tank
Clarifier
Sludge filter press
• Aerator
1,908 m3 (504,000 gal)
79.5 m3 (21,000 gal)
2.5 L/min (0.66 gal/min)
13.25 m3 (3,500 gal)
13.25 L/min (3.5 gal/min)
6.6 m3( 1,750 gal)
182m2(1,960ft2)
0.8 m3 (27 ft3) per day,
60% moisture
2.7g (0.006 Ib) per minute
of O2
INFLUENT,
1,893 m3
(500,000 gal)
PER DAY
(NONCHROMATE,
NONCYANIDE)
LIME FEED
SYSTEM
SULFIDE FEED
SYSTEM, 3.2 L/min
(0.84 gal/min)
POLYMER FEED
1 [ MUM
FLOCCULATING TANK
AERATOR
EFFLUENT
I, I
CLARIFIER! I LIGHT SLUDGEN-r-^
CONTINUOUS FLOW RECORDER t SAMPLER
FILTER
(CLF SYSTEM ONLY)
TO SEWER OR STREAM
.FILTER PRESS
SLUDGE STORAGE
TRUCK OR PUMP TO LAGOON
Figure F-8. Large LWS-CL and LWS-CLF plant schematic.
89
-------
INFLUENT,
37.85 m3
110,000 gal)
PER DAY
SLUDGE
REMOVAL
LAB,
CONTROL,
AND
STORAGE ROOM
• Scale 1 in = 10ft
• Plant capacity = 37.85 m3 (10,000 gal) per day
•Aerator used in LSPF, LWS-CL,and LWS-CLF plants only
tFilter bank used in LO-CLF, LSPF, and LWS-CLF plants only
LEGEND:
A Stoiage tank
B Mjxer-clarifier tank
C Filter press
& Pump
® Valve
D Aeiator*
E Filter bankt
Figure F-9. Small plant layout-all processes (LO-CL, LO-CLF, LSPF, LWS-CL, and LWS-CLF).
90
-------
20ft
DISCHARGE
G 0-
¥
E
C+
o
C-3
CD 9
o ig
IP--B
C-2
60ft
SLUDGE
REMOVAL
LJ
u
LEGEND:
A
8
C-1
C-2
C-3
C-4
D
Leveling tank
Flash mixer
Lime store
Lime slaker
Lime slurry
pH control
Polymer feed
E Flocculating tank
G Clarifier
H Sludge storage
I Filter press
L Filter (CLF system only)
63 Pump
Ig) Valve
INFLUENT, •
0.53 m3
(140 gal)
PER
MINUTE
i Plant capacity = 757 m3 (200,000 gal) per day
Figure F-10. Medium-sized LO-CL and LO-CLF plant layout.
91
-------
65ft
••
-L
o
CM
0
co
L
-r.
3m °1 fi7 ft ml
• ~1.b7tt •)
i n
_
G
J'1 E
rO« 6* > -
D C"3 C-2
-H V JSLsu,
r
C-1
| fj I I I I * I -¥l \J= t & ~ I I
L---~.*~ ..«_^[
j-3 «f — r '
" j -USr
L
T
— K *
DISCHARGE
o
H
^^H^J^
9
CONTROL
AND
STORAGE
ROOM
10- | -4
1
[
r 99
3 i
B
L ^ •
"—*"^T
nH
ALP
SYS
A
i
C-l-O-f-" '
2KB
kRM
TEM
fiti
!
* SLUDGE
REMOVAL
nu u u
LEGEND:
A Leveling tank H Sludge storage
B Flash mixer | Filter press
C-1 Lime store H Pump
C-2 Lime slaker Valve
C-3 Lime slurry j-1 Sulfide feed
C-4 pH control J-2 Sulfide control
D Polymer feed J-3 Sulfide slurry
E Flocculating tank K Aerator
G Clarifier L Filter
J
H
n
u
INFLUENT,
PER MINUTE
• Plant capacity = 757 m3 (200,000 gal) per day
Figure F-11. Medium-sized LSPF plant layout.
92
-------
LEGEND
A Leveling tank
B Flash mixer
C-1 Lime store
C-2 Limeslaker
C-3 Lime slurry
C-4 pH control
D Polymer feed
E Flocculating tank
G Clarifier
H Sludge storage
I Filter press
B Pump
® Valve
J-1 Sulfide feed
J-2 Sulfide control
K Aerator
L Filter (LWS-CLF system only)
INFLUENT,—
0.53 m3
(140 gal I
PER MINUTE
• Plant capacity = 757 m3 (200,000 gal) per day
Figure F-12. Medium-sized LWS-CL and LWS-CLF plant layout.
93
-------
LEGEND:
A Leveling tank
B Flash mixer
C-1 Lime store
C-2 Lime slaker
C-3 Lime slurry
C-4 pH control
D Polymer feed
E Flocculating tank
G Clarifier
H Sludge storage
I Filter press
E3 Pump
® Valve
L Filter (LO-CLF system only)
INFLUENT,—I
1.32 m3
(350 gal)
PER MINUTE
Plant capacity = 1,893 m (500,000 gal) per day
Figure F-13. Large LO-CL and LO-CLF plant layout.
-------
23.3 ft
CONTROL
AND
STORAGE
ROOM
DISCHARGE
LEGEND:
A Leveling tank
B Flash mixer
C-1 Lime store
C-2 Limeslaker
C-3 Lime slurry
C-4 rjH control
D Polymer feed
E Flocculating tank
G Clarifier
H
I
J-1
J-2
J-3
K
L
Sludge storage
Filter press
Pump
Valve
Sulfide feed
Sulfide control
Sulfide slurry
Aerator
Filter
INFLUENT. 1
1.32m3
(350 gal)
PER MINUTE
> Plant capacity = 1,893 m3 (500,000 gal) per day
Figure F-14. Large LSPF plant layout.
95
-------
LEGEND:
A
B
C-1
C-2
C-3
C-4
D
E
G
Leveling tank
Flash mixer
Lime store
Lime slaker
Lime slurry
pH control
Polymer feed
Flocculating tank
Clarifier
H Sludge storage
I- Filter press
B Pump
® Valve
J-1 Sulfide feed
J-2 Sulfide control
K Aerator
L Filter (LWS-CLF system only)
INFLUE
1.32m3
(350 gal)
PER MINUTE
• Plant capacity = 1,893 m3 (500,000 gal) per day
Figure F-15, Large L WS-CL and L WS-CLF plant layout.
96
-------
CLARIFIER
o
|CQNTROL[
AND
ISTORAGEJ
ROOM
SLUDGE
STORAGE
60 to 70 ft
NOTE
Treatment plant is above the lagoon on a deck
that covers the entire lagoon. Deck bracing
piles are'not shown; area under plant should
withstand 4,880 kg/m2 (1,000 Ib/ft2), other
areas, 488 kg/m2 (100 Ib/ft2).
FILTER PRESS
DECK
'« 1 ft
7ft
-WALL
BRACE
PILING
LAGOON WITH ACID-
RESISTANT COATING
(~ 200,000 gal,
757 m3/day PLANT)
Figure F-16. Cross section of medium-sized and large plants-all processes
(LO-CL, LO-CLF, LSPF, LWS-CL, and LWS-CL F).
97
-------
APPENDIX G
GRAPHIC PRESENTATION OF RESULTS
Figures G-1 through G-5 graphically compare the raw feed and effluent concentra-
tions of cadmium, copper, chromium, nickel, and zinc heavy metals for the five
precipitation processes:
a. Lime only, clarified (LO-CL)
b. Lirne orily, clarified and filtered (LO-CLF)
c. Lime, sulfide polished and filtered (LSPF)
d. Lime with sulfide, clarified (LWS-CL)
e. Lime with sulfide, clarified and filtered (LWS-CLF)
Figure G-l shows the relationship of LO-CL process effluent concentrations for the
16 test runs. Similar bar graphs in groups of five each (Figures G-2 through G-5) show
the same type of data for the other four processes.
98
-------
DC
LU
Q.
O.
O
O
H
<
IT
Z
III
8J
le
COPPER
4 567 8 9 101112 13141516
TEST RUN NUMBER
1234
5 6 7 8 9 1011 12 13141516
TEST RUN NUMBER
Raw feed
LO-CL process effluent
2 3 4 5 6 7 8 9 1011
TEST RUN NUMBER
14 1516
o
N
o
I-
LU
8J
18
ZINC
12345678 910111213141516
TEST RUN NUMBER
1234
5 6 7 8 9 1011 12 13141516
TEST RUN NUMBER
Figure G-1. Relationship of LO-CL process effluent concentration to raw feed
concentration for Cd, Cu, Cr, Ni, and Zn.
99
-------
Q
O
LL
O
Z
g
H
Lt
\-
8J
CADMIUM
DC
HI
a.
a.
O
O
LL
O
Z
O
<
DC
Z
LU
2
1 2
4 5 6 7 8 9 10 11 121314 1516
TEST RUN NUMBER
COPPER
1234
5678 910111213141516
TEST RUN NUMBER
o
cc
i leeee
o
g
<
DC
01
8-1
lee
CHROMIUM
123456789 10 11
TEST RUN NUMBER
14 1516
Raw feed
LO-CLF process effluent
ai
^
O
g
<
cc
81
NICKEL
123456789 101 1213141516
TEST RUN NUMBER
O
N
LU
O
<
CC
LU
23
8J
tee
ZINC
12345678 910111213141516
TEST RUN NUMBER
Figure G-2. Relationship of LO-CLF process effluent concentration to raw feed
concentration for Cd, Cu, Cr, Ni, andZn.
100
-------
— 10888
5
Q
Q
LL
o
z
O 180
H
UJ
81
CADMIUM
12 4 5 6 7 8 9 1011 12 1314
TEST RUN NUMBER
16
CC
LU
a.
a.
O
O
LL
o
o
UJ
81
180
COPPER
2 3 4 5 6 7 8 9 10 11 121314 16
TEST RUN NUMBER
5
— 100000
O
cc
i 10000
o
° 1890
O
H 100
CC
2
^5
O 5 1
Ch
IRI
OIV
HUM
a
I
I
I
1
!
.....
1 23456789 1011
TEST RUN NUMBER
14 16
Raw feed
I.SPF process effluent
UJ
y.
o
o
UJ
81
\vvvv
NICKEL
1 2 3 4 5 6 7 8 9 10 11 12 1314
TEST RUN NUMBER
16
81
3 4
5 6 7 8 9 1011 12 1314
TEST RUN NUMBER
16
Figure G-3. Relationship of LSPF process effluent concentration to raw feed
concentration for Cd, Cu, Cr, Ni, andZn.
101
-------
Q
O
LL
O
Z
g
cc
i-
z
LU
o1|
o3-
IBB
CADMIUM
12 4 5 6 7 8 9 10 11 12 13
TEST RUN NUMBER
16
LT
LU
Q.
Q-
o
O
U.
O
Z
O
<
oc
z
III
8J
ie
COPPER
2 3 4 5 6 7 8 9 1011 12 13
TEST RUN NUMBER
16
O
cc
I
O
u.
o
z
O
H
<
cr
i-
81
CHROMIUM
123456789 10 11
TEST RUN NUMBER
16
Raw feed
LWS-CL process effluent
leeeee
o
z
LL
O
Z
o
IT
Z
LU
81
NICKEL
1 2 3 4 5 6 7 8 9 10 11 12 13
TEST RUN NUMBER
16
o
z
N
LL
O
z
o
DC
t-
Z
HI
81
tee
ie
ZINC
1 2 3 4 5 6 7 8 9 10 11 12 13
TEST RUN NUMBER
16
Figure G-4. Relationship of L WS-CL process effluent concentration to raw feed
concentration for Cd, Cu, Cr. Ni, andZn.
102
-------
Q
<
o
u.
O
z
g
<
oc
z
LU
§3
8J
1888
lee
CADMIUM
12 4 5 6 7 8 9 10 11 12 13
TEST RUN NUMBER
16
cc
LU
Q.
Q.
O
O
U.
O
Z
o
8J
1008
iee
COPPER
1 2 3 4 5 6 7 8 9 10 11 12 13
TEST RUN NUMBER
16
O
cc
I
o
LL
o
z
o
<
cc
z
LU
8J
ieee
188
i«
CHROMIUM
123456789 10 11
TEST RUN NUMBER
16
Raw feed
LWS-CLF process
1 2 3
4 5 6 7 8 9 10 11 12 13
TEST RUN NUMBER
O
N
LL
o
z
g
N
oc
81
ZINC
1 2 3 4 567 8 9 10 11 12 13
TEST RUN NUMBER
16
Figure G-5. Relationship of LWS-CLF process effluent concentration to raw feed
concentration for Cd, Cu, Cr, Ni, and Zn.
103
-------
APPENDIX H
CRITERIA FOR SELECTING pH VALUE FOR PRECIPITATION
Figure H-l, which indicates theoretical hydroxide solubilities (14), shows that the
optimum pH for maximum precipitation varies for different metals. Consequently, a
treatment plant that receives a mixed heavy metal load must adopt a compromise pH.
The value will depend on the desired reduction levels for specific heavy metals. Two
other factors are also usually taken into account. First, an unnecessarily high pH results
in unnecessarily high lime costs. Second, subsequent acidification may be required, if
the local discharge permit requires a maximum pH of 9.0, as many permits do.
-J
CD
O
c/i
0.01 —
0.001 —
Figure H-1. Effect of pH on effluent concentration of heavy metals.
104
-------
SELECTION OF pH VALUE
For this work, the preferred pH value was one that would reduce the heavy metal
theoretical solubility levels below the EPA "1978 Proposed Effluent Limitation Guide-
lines" (1«0. The limits are listed in Table H-l.
Combination of the solubilities of Figure< H-l with the EPA guidelines generates
Table H-2. Bold numbers in the table are levels below guideline limits.
TABLE H-1. PROPOSED EPA GUIDELINE
LEVELS
Heavy metal
Cr6+
Ag
Pb
Cd
Zn
Cr (total)
Ni
Cu
Proposed 30-day
• average efficient
level Uig/L)
90
340
400
i 500
1,500
1,600
1,800
2,000
TABLE H-2. EFFLUENT CONCENTRATION RELATED TO EPA PROPOSED LIMITATIONS
Concentration (jug/U* at pH values of:
Heavy ———————
metal 8.00 8.25 8.50 8.75 9.00 9.25 9.50 9.75 10.00 10.25 10.50
Cd >1,300 >1,300 >1,300 >1,300 >1,300 >1,300 >1,300 1,300 230 38 11
Cr 30 24 20 21 29 50 100 200 500 850 2,000
Cu 5 2 < 1 < 1 <1 <1 <1 <1 1.5 3 5
Ni
Zn
2,800
8,000 1,400
1,000
300
350
75
120
60
38
75
9
110
4
190
1.5
330
1
550
1
850
'Boldface values are below EPA guideline levels.
105
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-80-139
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Sulfide Precipitation of Heavy Metals
5. REPORT DATE
JUNE 1980 issuing date.
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
A. K. Robinson and 3. C. Sum
8. PERFORMING ORGANIZATION REPORT NO,
D6-42205-5
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Boeing Commercial Airplane Company
P.O. Box 3707
Seattle, Washington 98124
10. PROGRAM ELEMENT NO.
1 BB 610
11. CONTRACT/GRANT NO.
S805413
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory—Cin., OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final, Oct. 77-July '79
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This research program was initiated with the objective
of evaluating a new process, the sulfide precipitation of
heavy metals from industrial wastewaters. The process was
expected to effect a more complete removal of heavy metals
than conventional lime processing because of the much lower
solubilities of metal sulfides than hydroxides.
Five processes were compared in bench-scale, con-
tinuous-flow equipment: conventional lime processing, con-
ventional lime processing plus filtration, lime with a sulfide
polishing and filtration, lime with sulfide, and lime with
sulfide'plus filtration.
Samples of actual wastewaters from 14 metal working
industries (including Boeing) were processed through the
bench-scale equipment using all five processes. Reductions
in the concentrations of cadmium, chromium, copper, nickel,
and zinc, plus selected other metals, were measured by
atomic absorption chemical analysis.
Capital and operating costs for the five processes were
compared for three plant sizes: 37.85 m3/day (10,000
gal/day), 757 mVday (200,000 gal/day), and 1,893 nWday
(500,000 gal/day).
The report recommends that, to reduce the levels of
cadmium, copper, nickel, or zinc from a wastewater treat-
ment plant using conventional lime processing, the addition
of a final filtration should be considered first. If filtration
does not achieve the desired low levels, then a sulfide
polishing process with added filtration is recommended. If
reduction of the levels of chromium, lead, silver, or tin is
required, the conventional lime process plus filtration is
recommended. The sulfide process did not significantly
reduce the levels of these metals.
Details are included on the use of a specific ion elec-
trode for the control of sulfide additions. The report does
not include comparison testing of the commercial Sulfex
process.
This report was submitted in fulfillment of Grant
S805413 by Boeing under the sponsorship of the U.S. Environ-
mental Protection Agency. This report covers a period from
October 1977 to July 1979; work was completed as of 3uly
1979.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
water treatment
wastewater
electroplating
waste treatment
precipitation
sulfides
heavy metals
toxic metals
68D
8. DISTRIBUTION STATEMENT
Release to public
19. SECURITY CLASS (ThisReport)
unclassified
21. NO. OF PAGES
118
20. SECURITY CLASS (Thispage)
unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
U.S. GOVERNMENT PRINTING OFFICE: 1980--657-165/0025
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