EPA-670/2-74-042
JULY 1974
Environmental Protection Technology Series
WASTE WATER TREATMENT
AND REUSE IN A
METAL FINISHING JOB SHOP
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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EPA-670/2-7U-042
July 1974
WASTE WATER TREATMENT AND REUSE
IN
A METAL FINISHING JOB SHOP
By
S. K. Williams Company.
Wauwatosa, Wisconsin 53225
Project No. 12010DSA
Program Element No. 1BB036
Project Officer
Clifford Risley, Jr.
U.S. Environmental Protection Agency
Region V
Chicago, Illinois 60606
For
Industrial Waste Treatment Research Laboratory
Edison, New Jersey 08817
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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REVIEW NOTICE
The National Environmental Research Center —
Cincinnati has reviewed this report and approved
its 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 pro-
ducts constitute endorsement or recommendation for
use.
11
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FOREWORD
Man and his environment must be protected from the
adverse effects of pesticides, radiation, noise and other
forms of pollution, and the unwise management of solid
waste. Efforts to protect the environment require a
focus that recognizes the interplay between the compo-
nents of our physical environment—air, water, and land.
The National Environmental Research Centers provide this
multidisciplinary focus through programs engaged in
• studies on the effects of environmental
contaminants on man and the biosphere, and
• a search for ways to prevent contamina-
tion and to recycle valuable resources.
The studies for this report were undertaken to demon-
strate an efficient waste water treatment system for a
large metal finishing job shop. Five integrated waste
treatment systems, each designed for a specific type of
waste compound,are used to protect the rinse waters from
contamination by process solution drag-out. The entire
design permits a minimum volume of sludge production,
minimum water usage, reduced chemical consumption and
maximum economy of operation. This new technology could
have a major effect on the industry's efforts to protect
our Nation's water resources.
A. W. Breidenbach, Ph.D.
Director
National Environmental
Research Center, Cincinnati
xxi
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ABSTRACT
A complete waste water treatment system has been installed
as part of the new S. K. Williams Company job plating
facility, to make the effluent suitable for discharge. Most
of the metal finishing processes common to the industry are
included in the plant. Despite the wide range of toxic mate-
rials used in these processes, the new treatment system is
providing an effluent essentially meeting the limitations
on toxic ions given in the U. S. P. H. S. drinking water
standards.1 '
cv
Five integrated waste treatment systems, each designed for a
specific type of waste compound, are used to protect the
rinse waters from contamination by process solution drag-out.
A batch-type treatment system handles miscellaneous and inter-
mittent discharges. The system design aims for a minimum
volume of sludge production and a unique and economical sludge
dewatering technique is included. Improved rinsing efficiency
is achieved through the use of the integrated chemical rinses,
thus permitting the plant to operate on a minimum water supply,
Chemical reaction efficiency was considered in the design of
each phase of the treatment system, to insure reduced chemi-
cal consumption and maximum economy of operation. Data is
presented on the operating and capital costs for the entire
system and operating experiences are described.
This report was submitted in fulfillment of Project No.
12010 DSA by S. K. Williams Company under the partial spon-
sorship of the Environmental Protection Agency. Work was
completed as of February, 1971.
xv
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CONTENTS
Abstract iv
List of Figures vi
List of Tables vif
Acknowledgment s v i i i
*
Sections
I Conclusions 1
II Recommendations 3
III Introduction 4
IV Waste Producing Operations 8
V Waste Treatment System Design Considerations 15
VI Operation of Integrated Treatment System 26
VII Operation of Batch Waste Treatment System 32
VIII Operation of Rinse Water System 38
IX Sludge Handling Operations 48
X General Economic Considerations 52
XI References 57
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FIGURES
Page
1 Plant Layout 10
2 Automatic Nickel-Chromium Plating Machine 12
(Department 100)
3 Manual Hoist Line (Department 200) 13
4 Automatic Programmed Hoist for Zinc and 14
Cadmium Rack Plating (Department 600)
5 Typical Integrated Treatment System 16
6 Sludge Filter Bed 23
7 Waste Treatment Room Equipment Layout 24
8 Batch Acid and Alkali Treatment Tanks 25
9 Caustic Soda Storage Tank 25
10 Rinse Water Settling Tank 38
11 Thickened Sludge in Filter Bed 51
VI
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TABLES
No. Paqe
1 Summary of Integrated Treatment Systems 19
2 Chemical Consumption, of Integrated Treatment 29
Systems - November,. 1970
3 Plant Production for November, 1970 31
4 Sludge Filter Bed Effluent Analyses 35
5 Chemical Consumption of Batch Treatment 37
System - November, 1970
6 Results of Rinse Water Effluent Analyses 42
7 Results of Combined Effluent Discharge 44
8 Relative Consumption of Fresh and Reused Water 45
9 Distribution of Water Consumption by 46
Production Departments
10 Chemical Consumption of Rinse Water System 47
11 Comparison of Sludge Filter Bed Performance 50
12 Summary of Capital Costs 52
13 Summary of Monthly Waste Treatment System 53
Operating Costs - November, 1970
14 Distribution of Treatment Chemical Costs by 55
Production Time
15 Waste Treatment Chemical Costs per Unit of 56
Production
16 Waste Treatment Chemical Costs 57
Vll
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ACKNOWLEDGEMENTS
Supervision of the waste treatment operation and assistance
in gathering data for this report were provided by
S. K. Williams personnel, Mr. Alan Williams, Mr. Robert
Steuernagel, Jr., and Mr. William P. McDonough.
The design of the waste treatment system and preparation of
this report were supervised by Leslie E. Lancy, Ph.D.,
President of Lancy Laboratories, Division of Dart Industries,
Chemical Group, Zelienople, Pennsylvania. The report was
prepared by Mr. F. A. Steward, Project Engineer with
Lancy Laboratories.
The advice and cooperation of Mr. William Lacy, Chief of
Industrial Polltuion Control Branch? Mr. Edward Dulaney,
Program Manager for Metal and Metal Products; and
Mr. Clifford Risley, Jr., Project Officer; all of the
Research and Monitoring Office of the Environmental
Protection Agency, is acknowledged with sincere thanks.
This report was submitted in fulfillment of Project
No. 12010 DSA under the partial sponsorship of the
Environmental Protection Agency, United States of America.
. 4 .
vni
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SECTION I
CONCLUSIONS
1. A waste treatment facility based upon use of the inte-
grated treatment systems allows a job plating shop to
provide complete waste treatment, while maintaining the
flexibility of processing cycles which is essential to
that business.
2. Accomplishing waste treatment with recirculated chemi-
cal rinses is an effective and economical approach with
minimum sludge generation and chemical consumption.
Analytical results spanning a one year period show aver-
age effluent concentrations of:
ph 7.81 Cu 0.09 mg/1
CN 0.03 mg/1 Ni 0.21 mg/1
Cr+6 0.02 mg/1 Zn 1.12 mg/1
Cr+3 0.01 mg/1 Cd 0.25 mg/1
3. The total waste treatment costs, including depreciation,
chemicals, utilities, and labor add only 3.3£ to each
dollar of the company's sales.
4. By improving the conditions under which precipitation,
flocculation, and settling occur, the integrated treat-
ment systems produce metal hydroxide sludges which con-
tain far less water and are more amenable to further
dewatering than those produced by treatment of dilute
rinse water wastes.
5. To accomplish effective and economical waste treatment,
plating shop operators and managers must incorporate
into their thinking some new approaches and attitudes,
such as considering the floor as a collection system
for accidental discharges rather than an extension of
their sewer inlet.
6. Lack of attention to details, such as unnecessary water
running on the floor or acids and cleaners being mixed
prior to treatment, can inflate waste treatment expenses
as indicated by the batch treatment costs in this system.
7. Suppliers of process chemicals for the metal finishing
industry are making increasing use of organic chelating
and complexing agents, and these are creating entirely
new waste treatment problems which may prove to be more
severe and costly than the present ones.
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8. Waste treatment costs do add to the overall operating
expenses of a plating shop, but they can be at least
partially offset by judicious conservation of water and
process chemicals, both of which are commonly wasted.
9. Proper design of a waste treatment system can permit a
reduction in water and sewer charges to offset a major
portion of its operating costs; (47% in this report).
10. Since chemical wash solutions are more effective than
water for rinsing, the integrated treatment systems
actually improve the plating processes as shown by
three examples (see page 26). An additional advantage
of the integrated systems is that conditions inimical to
treatment quality will frequently cause an undesirable
effect on the work pieces (see page 27). This gives the
operators additional incentive to maintain good control
of the treatment systems.
11. Concrete block sludge filter beds, as used in this sys-
tem for dewatering the waste sludges, can be adversely
affected by oil and by the introduction of wastes treated
in the presence of peptizing agents and/or large volumes
of dilution water.
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SECTION II
RECOMMENDATIONS
1. If the practice of stripping work pieces in the acid
pickles cannot be discontinued, an integrated treat-
ment system should be installed to eliminate the carry-
over of zinc and cadmium into the rinse waters.
2. Alkaline cleaners should be neutralized and discharged
to the sanitary sewer system rather than treated with
metal-containing solutions. The cleaning solutions
contain organic peptizing agents and detergents which
do not need chemical treatment and which interfere
with the chemical treatment of the other solutions.
Biological treatment is necessary for these organic
materials and the neutralized cleaning solutions are
suited for discharge into such a sewage treatment system,
3. Suppliers of process chemicals for the metal finishing
industry must begin to appreciate waste treatment
problems when they formulate new materials. If the
use of a particular chelating compound in a process
offers numerous advantages, but also increases waste
treatment costs disproportionately, then it would not
be an improvement in the technology. Under certain
conditions, such as plating on plastics, the use of
such organics is necessary, but their use should be
avoided when possible.
.4. All oil must be kept out of the treatment system, acids
should be discharged in such a manner that they are as
concentrated as possible when treated, and all unneces-
sary waste must be kept off the floor.
5. The north sludge filter bed, which now dewaters sludge
only very slowly, should be equipped with a Sludge
Filter Decant Panel which would restore its effective-
ness and assist in removing the excess water which is
being hauled away with the sludges.
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SECTION in
INTRODUCTION
The S. K. Williams Company has been engaged in the job elec-
troplating business in the Milwaukee area for many years. In
1967, they began plans to erect a new building for consoli-
dation and enlargement of their electroplating and metal
finishing activities. The building project was initiated
due to anticipated future expansion of their activities, and
the building design was such that the plant area could be
expanded to accommodate additional equipment facilities and
to provide storage capacity for work in process for their
customers. The first portion of the new plant was completed
and placed into operation in 1969. Ultimately, about four
times as much area is to be included under roof, but the
present building houses the majority of the types of plating
processes to be used, and will account for the major portion
of the production and waste generation.
Both existing finishing equipment, moved from the former plant
locations, and additional new equipment to automate and stream-
line the operations are housed in the new structure. Metal
finishing activities are performed on various basis materials
such as steel, stainless steel, copper, brass, aluminum, zinc
die castings, magnesium, plastics, etc. The metal finishing
operations, including cleaning and descaling of the basis
metals and electroplating with the finish metals, are processes
requiring water. Without proper treatment, the waste water
from this building would be contaminated with many different
types of toxic chemical compounds, and would be unsatisfactory
for discharge to either a sanitary sewer system or a storm
sewer or surface water course. The requirement for waste
treatment provisions in such a job plating shop is a partic-
ularly demanding one because of the wide variety of waste mate-
rials involved, the severe toxicity of many of the contami-
nants, and the extremely large quantities of water normally
used.
In this particular case, an additional factor to be considered
in designing the plating plant and waste treatment system was
the limited availability of fresh water. The continuation of
past practices would have required a total of 800 gallons per
minute of water after all anticipated expansions had been com-
pleted. The normal water consumption for the portion of the
plant now in operation would have been about 600 gallons per
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minute. However, the State of Wisconsin restricted the per-
missible pumping rate at the company's well to 300 gallons
per minute so as to avoid a reduction in the water table in
the area. Such a reduction would seriously interfere with
the needs of other water users in the vicinity. Thus it was
necessary to design the plant so that it would operate on a
maximum of 50% of the normal water consumption.
The design, installation, and initial operation of a unique
waste treatment system to neutralize all toxic waste con-
stituents, while at the same time drastically reducing water
consumption in the plant, was undertaken as a demonstration
project partially financed by an EPA Research and Develop-
ment Grant. This report describes the new metal finishing
plant and waste treatment system as well as the findings and
conclusions resulting from the initial year of operation.
Lancy Laboratories of Zelineople, Pennsylvania, was chosen
as consultant for the design of the waste treatment system.
Their design centered around the use of Integrated Waste
Treatment Systems for each specific type of contaminant to
be encountered.
The Integrated approach2- consists of a recirculated chemical
treatment wash solution, integrated into the metal finishing
process line. Parts being removed from a toxic process solu-
tion are rinsed in this treatment wash solution before being
rinsed in water. Because the use of this approach greatly
reduces the input of dissolved salts to the rinse water, as
compared to conventional rinsing, far less water is required
to accomplish satisfactory rinsing. For this reason, a
water reuse system was an integral part of the design, and
it was anticipated that as much as 80% of the rinse water,
which would normally be wasted from the plant, could be
pumped back for reuse in the processing lines.
Additional advantages to be expected from the use of the Inte-
grated systems were reduced treatment chemical consumption
and reduced sludge handling expenses, compared with conven-
tional treatment approaches. Finally, a novel method for de-
watering the sludges produced by the waste treatment re-
actions was included in the system. In metal finishing
waste treatment, the final disposition of the sludges pro-
duced is one of the largest factors in the operating expenses3
and the dewatering system used here is a major improvement
in the economical handling of such sludges.
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The fpllowing were considered as objectives for the demonstra-
tion project:
(a) To demonstrate the feasibility of operating a
high-production, job electroplating installa-
tion, utilizing nearly all common electroplating
processes, while maintaining a waste water efflu-
ent of the highest quality in a simple and eco-
nomical manner.
(b) To show that, in view of the uncontaminated
rinse water effluent, it is possible to reuse
80-90% of the waste effluent in the process
rinses without any chemical purification or
mechanical filtration.
(c) To demonstrate that the various chemical rins-
ing steps employed—the Integrated Treatment
Solutions—have no deleterious effect upon the
work pieces and can, in some cases, be advan-
tageous, yielding improved quality, freedom
from staining, better adhesion, and a lower
rate of rejects due to mis-plating.
(d) To demonstrate a simple and economical method
for the complete precipitation and settling of
the metal ions which are in the thin film of
process solution carried by work pieces when they
are removed from the solution. The method relies
upon the fact that the chemical reactions occur
in the presence of a high excess of treatment
chemicals and a relatively high concentration
of precipitated solids as compared to the usual
method of settling these same metallic precipi-
tates from dilute rinse waters.
(e) To demonstrate a new technique for dewatering
the collected sludges, avoiding high-cost
filtration and the usual problems encountered
when pressure or vacuum filtration of metal
hydroxides is attempted.
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The uniqueness of this demonstration project is based upon
the fact that the waste treatment system serves a job plating
plant utilizing an extensive variety of metal finishing pro-
cesses containing various toxic compounds and yet the level
of effluent contamination can be less than the established
criteria for public drinking water supply. Also unique is
the fact that approximately 80% of the rinse water effluent
may be reused in the processing plant because of the very low
level of dissolved salts. (See page 20). Of primary interest
is the fact that these unique benefits are accomplished with
less operating expense than would be encountered in treating
the wastes from the same plant using available alternative
approaches.
The only alternative approaches which are practical and re-
liable for treating a waste water effluent containing the
variety of contaminants involved here are based on the treat-
ment of the flowing rinse waters for removal of the con-
taminants. Since the concentrations of the contaminants
in a rinse water stream would be very low, and the flow rate
of the stream would be relatively high, chemical treatment
and solids separation would both be inefficient and expen-
sive. Furthermore, when the drag-out of process solu-
tions and the additions of treatment chemicals both con-
tribute to the dissolved solids in the rinse water stream,
reuse of the water is far less practical and economical
than with the system here employed.
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SECTION IV
WASTE-PRODUCING OPERATIONS
In a job-plating plant such as this, aqueous wastes re-
quiring treatment normally result from:
(1) Water rinses following the various pro-
cess solutions containing toxic chemicals.
(2) The periodic discarding of expended pro-
cess solutions, such as cleaners, acid
dips, anodizing solutions with high
aluminum content, etc.
(3) Accidental overflows of solutions contain-
ing toxic chemical compounds, and drippage
from work in process between the various
process solution and rinse tanks.
(4) Discharges of contaminated steam condensate
in the event that a heating coil immersed
in a toxic chemical process solution
would develop a leak.
The first of these sources represents the most demanding
waste treatment requirement as the rinse waters consist of
trace quantities of the various contaminants in large
volumes of water. Attempting chemical reactions under such
dilute conditions is cumbersome and inefficient and re-
quires large reaction vessels because of the hydraulic
load. Furthermore, the sludges which result when toxic
metals are precipitated from dilute solutions are very
voluminous and difficult to separate as they have nearly
the same density as the water itself. Typical sludges
resulting from treatment of dilute rinse waters contain
99.5% water and only 0.5% sludge. Thus, the sludge hand-
ling and disposal provisions must be designed for slurries
which are nearly all water. Where the solid wastes must be
hauled away from the plant site, a significant portion of
the total waste treatment operating costs may be attributed
to hauling away water.
Wastes from Sources 2, 3, and 4 are subject to con-
tamination by the same materials as the rinse waters, but
their safe and effective elimination is primarily a problem
of proper waste treatment system design. The discarded pro-
cess solutions are relatively concentrated and can thus be
treated with reasonable chemical efficiency while the floor
8
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spills and contaminated condensate are normally very
low volume wastes.
The general types of processes that are installed in the
plant's various metal finishing lines consist of:
(1) Cleaning, for oil and grease removal;
(2) Acid descaling and pickling of steel, copper,
brass, aluminum, zinc-base die castings, etc.
(3) Metal plating from the cyanide complexes of
zinc, cadmium, copper, silver, and gold;
(4) Metal plating based on the acid complexes
of nickel, copper, and chromium;
(5) Metal plating based on the alkaline complex
of tin;
(6) Sulfuric and chromic acid anodizing of
aluminum;
(7) Chromium-compound-based conversion coatings
on aluminum, cadmium, and zinc;
(8) Dyeing of anodized aluminum surfaces.
Figure No. 1 shows the present layout of the metal finishing
equipment in the plant.
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Figure 1
Plant Layout
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The waste treatment facilities for the plant were designed
to also fill the requirements of additional metal finishing
equipment which may be installed in the future. However,
the present finishing equipment includes nearly all of the
metal finishing processes which will be encountered. There-
fore, it is anticipated that most of the future facilities
will only be duplications of existing processes, but with
different mechanical equipment to handle various types of
work pieces with maximum efficiency. All of the high-
production finishing operations are included at the present
time. The new equipment will be needed for additional
flexibility in handling unusual or small-lot items, so that
most of the rinse water and chemical consumption will be
attributed to this existing equipment, even after all
planned expansions have been completed.
Figures 2, 3, and 4 are photographs of three of the major
high-production plating areas.
11
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Figure 2
Automatic Nickel - Chromium Plating Machine
(Department 100)
12
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Figure 3
Manual Hoist Line (Department 200)
13
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Figure 4
Automatic Programmed Hoist for
Zinc and Cadmium Rack Plating (Department 600)
14
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SECTION V
WASTE TREATMENT SYSTEM DESIGN CONSIDERATIONS
As mentioned earlier, dilute rinse water wastes are the most
expensive and difficult to treat properly. These wastes re-
sult when work pieces, carrying a thin film of process solu-
tion (drag-out), are rinsed in water prior to further
processing.
The Integrated waste treatment systems employed in this
facility prevent the formation of dilute wastes by removing
the process solution film from the parts before they are
rinsed with water. Each chemical wash solution, used to
rinse the parts, is recirculated in a closed-loop system
which includes the treatment wash tanks in the plating lines
and a reservoir tank connected by piping to the wash tanks.
Figure 5 shows a typical integrated treatment system.
Since the treatment wash solutions contain excess treatment
chemicals at all times, the reactions between the contami-
nants and the treatment chemicals occur at the surface of
the work pieces where the process solution film is still in
a concentrated state. Since the reactions occur under con-
centrated conditions, and in the presence of excess treat-
ment chemicals, they are very rapid and the consumption of
chemicals is kept to a minimum. The sludges, which are pro-
duced when the metal ions precipitate, accumulate in a dense,
dewatered condition because they are precipitated under con-
centrated conditions. Furthermore, they are kept within the
closed-loop system so that newly-formed sludge particles
become mixed with older, conditioned sludge, giving excel-
lent flocculation and compacting.
Some of the sludge which accumulates in the treatment reser-
voirs is removed by a periodic "sludge-blowdown" wherein
sludge solution is pumped from the reservoirs to a sludge
filter bed. The volume removed by this operation is re-
placed with fresh water, thus reducing the dissolved salt
concentration of the treatment solution. 'The timing of the
blowdowns controls both the salt level in the solution and the
amount of accumulated sludge.
15
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PROCESS
SOL'N.
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Figure 5 - Typical Integrated Treatment System
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Since the treatment wash solution must be chemically formu-
lated to suit the particular contaminant for which it is in-
tended, a separate closed-loop system must be provided for
each type of contaminant. In this plant, the following types
of toxic contaminants are distinguished:
(1) Cyanide compounds such as sodium and potassium
cyanide and also their metal complexes with
zinc, cadmium, copper, silver, and gold.
(2) Chromic acid waste containing high concentra-
tions of free chromic acid.
(3) Chroma te compounds containing low concentrations
of chromate chemicals.
(4) Nickel from sulfate and chloride-based solu-
tions .
(5) Copper from acid solutions such as sulf uric-
nitric type bright dips, acid copper plating
solutions, and chelated copper complex solu-
tions as used in the process of plating on
plastics.
Thus, five Integrated Systems are provided to protect the
rinse waters from contamination due to drag-out of process
solution. These are known as the Integrated Cyanide,
Chromium I, Chromium II, Nickel and Copper Treatment Systems.
The chemistry of these systems is as follows : **
Cyanide
2NaCN + SNaOH + 5C12 -> 10 NaCl + 2CO2t + N.2+ + 4H2O
Chromium I
2H2CrO4 + 3SO2 ->• Cr2 (80^)3 + 2H2O
Chromium II
+ 3Na2C03 + 2H20 + Cr2 (OH)
2C02t
and
17
-------
2Na2CrOIf + 3Na2S2O1+ + Na2C03 + 2H2O -> Cr2 (OH)
+ 6Na2S03
Nickel
2NiSO4 + 2NaOH + Na2CO3 ->• Ni2 (OH) 2CO3 + 2Na2S0lt
Copper
2CuSO4 + H2SO[f + Na2S2O4 + 8NaOH -»• Cu2OI
+ 2Na2S03 + 3Na2SOif + 5H2O
It should be explained that the Chromium II treatment solu-
tion contains both reducing and neutralizing chemicals/ and
thus provides for both the reduction of hexavalent chromium
to the trivalent form, and the precipitation of trivalent
chromium. It is used as a single-step chromium treatment
wash after low-concentration chromate dips. On the other
hand, the Chromium I treatment solution is operated at a
low pH range and can thus use a much less expensive re-
ducing agent than can the Chromium II system. Following
highly concentrated chromium process solutions, the
Chromium I treatment wash is used first to accomplish re-
duction of the hexavalent chromium economically. The
Chromium II wash, which follows, then neutralizes the
acidic Chromium I film and precipitates the trivalent
chromium as the basic carbonate.
Table 1 lists, for each of the five Integrated Systems, the
type of process accommodated, the primary treatment chemi-
cals added, and the metals precipitated to form the sludge.
18
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Table 1. SUMMARY OF INTEGRATED TREATMENT SYSTEMS
System
Process Treated
Treatment Chemicals &
Concentrations
Metals
Precipitated
Cyanide
Chromium I
Chromium II
Nickel
Copper
Zinc, Cadmium, Copper
Silver and Gold Plating
Chromium Plating;
Etching of Plastics
Chromium Plating; Chro
mate Dipping of Zinc,
Cadmium and Aluminum;
Etching of Plastics;
Chromic Acid Anodizing
Nickel Plating
Acid Copper Plating,
Copper and Brass Bright
Dipping
Chlorine Gas (C12) -
800-2500 mg/1
Caustic Soda (NaOH)
pH 11-12.8
Sulfur Dioxide Gas
1,000-2,500 mg/1
Sodium Hydrosulfite
(NazSaOit) - 200-500 mg/1
Soda Ash
pH 7.5-8.5
Soda Ash (Na2C03) -
pH 8.5^9.5
Caustic Soda (NaOH)
Sodium Hydrosulfite
(Na2S2O4) - 500-700 mg/1
Caustic Soda (NaOH) -
pH 8.5-9.5
Zinc, Cadmium
Copper, Gold
Chromium, Z inc,
Cadmium, and
Aluminum
Nickel
Copper
Zinc
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The total dissolved salt concentration in the Integrated
treatment solutions (typically 75-120 g/1) is much lower
than in the preceding process baths (typically 250-400 g/1),
and the volume of solution film carried on a given work
piece is the same when it emerges from either solution.
Thus, the water which is used to rinse the piece receives
far less salt input when it follows an Integrated Solution
than when it follows a process bath. Furthermore, when
following conventional practice, and removing the toxic
materials with rinse water, all of the treatment chemicals
must also be added to the water. They must be added in
excess of requirements to insure complete reaction. The
result is that the rinse waters in conventional practice
carry approximately four times the concentration of dis-
solved salts found in rinses following Integrated treatment
washes.
All rinse waters in this plant are collected in a common sewer
system which leads to a pH Adjustment Sump. The rinses fol-
lowing toxic process solutions are protected by Integrated
Treatment Washes and the remaining rinses are those follow-
ing alkaline cleaners, acid dips, and other non-toxic pro-
cess solutions. Since the sludges resulting from the
major treatment reactions accumulate in the Integrated
systems, the only sludges to be found in this combined
rinse water stream are traces of precipitated iron, alumi-
num, and water hardness. To remove these traces, a settling
tank is provided following the pH Adjustment Sump. After
passing through the settling tank, the clarified rinse waters
overflow into a chamber from where the Reuse Water Supply
Pump returns a portion (as high as 80%) of the flow to the
plating lines. To control the accumulation of dissolved
salts in the rinse water system, a certain amount of fresh well
water is added at selected rinse tanks in the plating lines.
This amount of fresh water input creates an overflow from
the teuse water pump chamber, and this overflow is the rinse
water effluent discharged from the plant to the storm sewer.
Discharge to a sanitary sewer system was avoided because the
quality of the water, and thus the total discharge of waste
materials to the environ, could not be improved by passage
through a biological treatment plant. Furthermore, dilution
of the input to the sewage plant with essentially pure water
can only reduce the efficiency of the biological processes.
For this reason, discharge of a properly-treated industrial
waste effluent to a sanitary sewer is ecologically harmful.
20
-------
The additional waste chemical load from future expansions
will be countered by increased chemical feed rates in the
five Integrated systems, which are not limited in the amount
of chemical input which can be handled. Even at full antic-
ipated expansion, the plant will have a maximum fresh rinse
water consumption of 300 GPM, and the dissolved salt con-
centration in the water will be less than that which would
be found in 800 GPM with conventional treatment methods.
A batch collection and treatment system is provided for the
discarded process solutions and the accumulated floor spills.
It is essential that the discarded process solutions be
treated in the concentrated form so that chemical reactions
are efficient and sludges are as concentrated as possible.
Thus, an overhead acid collection line is provided with
quick disconnect fittings located throughout the plant. A
portable pump is to be connected to the nearest fitting on
this line and used to transfer the solution directly to
the Batch Acid Treatment Tank. On the other hand, dis-
carded alkaline solutions are drained through the underfloor
sewer to the Alkali Sump from where they are pumped auto-
matically to the Batch Alkali Treatment Tank.
A plating shop will inevitably have an appreciable amount
of floor spill resulting from: drippage as parts are trans-
ferred from tank to tank; overflows of tanks due to over-
filling; spills and drips of the concentrated chemicals
which must be regularly added to the process solutions; and
leaks in tanks, piping, filters, etc. These floor spills
can be contaminated with any of the chemicals used in the
plant, and they can vary widely in concentration. Therefore,
a system to collect the floor spillage and hold it for man-
ual batch treatment is essential. The best approach for
treating this type of waste can only be decided upon after
the operator has examined and analyzed it. The floor in
this plant is designed so that all floor spills are con-
tained and prevented from entering the rinse water sewer
system. Areas of heavy acid usage, such as the hard
chromium plating, and aluminum anodizing areas, have the
floor drained through vitrified clay sewers to an Acid Sump
which is equipped with a pump and level control to automat-
ically pump to the Batch Acid Treatment Tank. All other
processing areas have the floor drains connected with cast
iron sewers to the Alkali Sump mentioned previously.
In the Batch Treatment System, appropriate chemicals are
added to treat the collected wastes, depending upon what
the operator's examination reveals about their composition.
When cyanide is indicated by analysis, caustic soda and
21
-------
chlorine gas or calcium hypochlorite are added. When hexa-
valent chromium is found, it is reduced with sodium meta-
bisulfite (in acid solutions) or sodium hydrosulfite (in
neutral or alkaline solutions). Following treatment for
cyanide and hexavalent chromium, each batch is neutralized
with fresh sulfuric acid or caustic soda to pH 8.0-9.5.
Following the addition of treatment chemicals, the treated
batch is allowed to mix for at least fifteen minutes to
insure that reactions are completed, and then it is analyzed
for toxic materials prior to discharge to the Sludge Filter
Bed.
All sludges from the treatment reactions accumulate as
follows:
(1) Those from treatment of process solution
drag-out accumulate in the five integrated
treatment system reservoirs.
(2) The traces of precipitate in the treated
rinse water effluent accumulate as a sludge
blanket in the bottom of the Rinse Water
Settling Tank; and
(3) The treatment of various wastes in the Batch
Treatment System generates sludges which
are pumped out with each treated batch.
All of these sludges are discharged to a Sludge Filter Bed
of concrete block construction. This device5 serves to de-
water and thicken the sludges through a unique and effective
combination of gravity filtration, capillary dewatering,
and greatly increased evaporation. Thickened sludges from
the filter beds are periodically removed by pumping them
into a septic waste hauling truck which dumps them on a
sanitary landfill.
Figure 6 is a photograph of the two filter beds with the
sludge hauling truck and its suction hose visible.
22
-------
Figure 6 - Sludge Filter Bed
The equipment layout in the waste treatment room is shown
in Figure 7, and photographs of some of the waste treatment
equipment are shown in Figures 8 and 9.
23
-------
I CHROME I SUMP TANK
2. CYANIDE SUMP TANK
3. CHROME II SUMP TANK
4. NICKEL SUMP TANK
5. COPPER SUMP TANK
6. ALKALI SUMP TANK
7. ACID SUMP
8 FLASH MIXING TANK
9. pll CONTROL UNIT
IO. NaOH SUPPLY TANK
II. HjS04 SUPPLY TANK
12. ACID COOLING WATER
HOLDING TANK
II CYANIDE COOLING WATER
HOLDING TANK
14. WATER SEAL UNIT
IS. NasSzQ,- NOzCO, MIXING TANK
16. ELECTRICAL CONTROL PANEL
17. NatCO, MIXING TANK
18. NaaStp(- NaOH MIXING TANK
19. NaOH STORAGE TANK (SOX LIQUID)
20. CYANIDE TREATMENT RESERVOIR TANK
21. CHROME II TREATMENT RESERVOIR TANK
22. NICKEL TREATMENT RESERVOIR TANK
23. COPPER TREATMENT RESERVOIR TANK
24. NajV^ MIXING TANK
29.CHROME I TREATMENT RESERVOIR TANK
29. ALKALI COLLECTION TANK
27. ACID COLLECTION TANK
Figure 7 - Waste Treatment Room Equipment Layout
24
-------
I '
! 'I
Figure 8 - Batch Acid and Alkali
Treatment Tanks
Figure 9 - Caustic Soda Storage Tank
-------
SECTION VI
OPERATION OF INTEGRATED TREATMENT SYSTEM
Treatment chemicals are added to the Integrated Systems
from stock solution mixing tanks, with the exception of
chlorine, which is added to the Cyanide Treatment System
as a gas, and sulfur dioxide which is also fed as a gas to
the chromium Treatment System. The stock feed solutions are
prepared once per shift and added to the system by manually-
set proportioning pumps. Since relatively large excesses
of treatment chemicals are maintained in the treatment
solutions, and the large volumes of solution resist rapid
changes in concentration, chemical control of the systems
is simplified. The reserve of treatment chemical in a
system is adequate for several hours of operation even in
the event of a complete failure of chemical feed. Thus,
periodic checks on the concentration of excess chemical
in a solution serve as adequate controls of the system.
These tests on the Integrated solutions are run by the waste
treatment operator and recorded on a log sheet, which is
kept as a permanent record of the performance of the systems,
As a confirmatory check, the rinse water effluent is tested
once per day for the major contaminants, and it is given a
complete, quantitative analysis once per month.. All of
the routine control analyses are performed using simplified
test procedures6, developed so that plating shops without
elaborate laboratory facilities can operate and control
their waste treatment systems.
Theoretically, chemical rinsing is far more effective in
removing a film of process solution than is normal water
rinsing.7 While such improvements in rinsing efficiency are
very difficult to demonstrate quantitatively in an operating
plant, three instances of the effect were noticed in this
installation. The first was a nearly complete elimination
of chromium staining on parts which had been bright chromium
plated for decorative purposes. Chromium staining results
when chromic acid, which has been trapped in cracks, or in
blind holes, or between the rack tip and the part, bleeds
out onto the plated surface during hot water rinsing and
drying. The Integrated treatment solution eliminates this
problem by chemically attacking the chromic acid solution,
rather than attempting to displace or dilute it, as does
water. The second observed improvement was an increase in
the adhesion of plated nickel coatings to copper substrates
which had been previously deposited from an acid copper
26
-------
plating bath. When the acid-copper-plated part was rinsed
in the Integrated Treatment Solution, subsequent nickel
adhesion was significantly better than when the same part
was water rinsed. Finally, an improvement in the rinsing
of chromic acid etch solution from plas.tic parts was noted.
The etch solution has a high viscosity and is thus diffi-
cult to remove completely from the porous plastic surface.
However, as in the case of chromium staining, the chemical
attack of the treatment wash solution effectively removes all
traces of the etch. The amount of time and labor required
for rinsing the parts where both reduced, but perhaps most
important is the fact that the life of the subsequent process
solution was increased. This subsequent bath is a proprie-
tary "sensitizer" which prepares the etched plastic surface
to receive the deposit of electroless copper plating. This
sensitizer is a relatively expensive solution which is
adversely affected by trace contamination of hexavalent
chromium.
In one case, the chemical treatment wash solution did have
a detrimental effect upon the work pieces in process. After
six months of trouble-free operation, the freshly zinc-
plated parts started to turn a dark gray color when dipped
into the cyanide treatment wash, and the zinc surface then
resisted bright dipping and chromating. All indications
were that ions of a metal more noble than zinc were present
in the treatment solution. Many previous installations
using the same treatment solution for the same mixture of
metals had established that when precipitation of cadmium
and copper from the solution was sufficiently complete, no
problem should exist when rinsing the zinc-plated parts.
However, investigation revealed that a new, "low-cyanide"
zinc plating bath had been put into use a few weeks previous
to the appearance of the problem. As it turned out, the
addition agents used in the new plating solution contained
some complexing or chelating agents which accumulated in
the treatment solution and held excessive copper and/or
cadmium in solution.
A simple modification in the chemical additions to the system
eliminated the problem by replacing the copper and cadmium
in the chelates with harmless calcium and magnesium ions.8
A mixture of calcium and magnesium chlorides was added to
the system with a proportioning pump, thus preferentially
occupying the chelated positions and allowing the heavy
metals to precipitate. After a few months of use, the
new "low-cyanide" brightener system was abandoned because
the complexing-type addition agents for the plating bath
proved more troublesome and expensive than the treatment
of the cyanide which they were to eliminate. However,
27
-------
additions of the calcium and magnesium to the treatment
system have continued because elimination of the complexers
from the plating bath is a very slow process since they
are lost only by drag-out. Complete elimination of the
troublesome compounds from the plating bath could take
years.
Another modification in the operation of the treatment
systems was made after nearly a year of operation. It
involved the use of hydrazine hydrate as the reducing agent
in the Integrated Copper and Chromium II Treatment Systems.
Originally, sodium hydrosulfite (Na2S2C\) was used as the
reducing agent, but this compound is rather unstable and
is readily oxidized by the air in contact with the solution
surface. A large portion of the hydrosulfite added to the
systems each day was lost due to this breakdown, rather
than being consumed in reducing the metal ions. Hydrazine
hydrate was found to be an effective reducing agent for
the application, and it was not lost through wasteful
breakdown. Therefore, the systems were converted to
hydrazine use in early 1970, after nearly a year of opera-
tion, and the costs for reducing chemicals were drastically
reduced. In the copper treatment system, a monthly chemi-
cal cost.of $69.97 (April 21 to May 19, 1970) with hydra-
zine, jumped to $248.24 (May 20 to June 17, 1970) when the
hydrazine supply ran out and hydrosulfite was substituted
for a month.
For purposes of tabulating-operating costs, the month of
November, 1970, was chosen as representative of current
conditions. Prior to this/ some of the processes intended
for inclusion in the plant were not in full production.
Table 2 on the following page lists the chemicals consumed in
each of the Integrated Systems during the subject month,
and indicates the respective cost figures. Three other
factors which enter into the total operating costs for'these
systems are the operator's wages, the sludge disposal costs,
and the power costs for the pumping equipment. These factors
are included in the overall economic summaries given in
Section VIII, but no attempt is made to allocate appropriate
portions of the three factors to the operation of the Inte-
grated Systems.
28
-------
TABLE 2
Chemical Consumption of Integrated Treatment Systems
November, 1970
Treatment System
Cyanide
Chrome I
Chrome II
Nickel
Copper
Chemical Compound
Caustic Soda (50Jf
liquid)
Chlorine
Inhibitor LD
(proprietary)
Calcium Chloride
Magnesium Chloride
Caustic Soda
Sulfur Dioxide
Soda Ash
Hydrazine Hydrate
(85?)
Soda Ash
Soda Ash
Hydrazine Hydrate
Quantity
Consumed
Unit
Price
Monthly
Cost
704 gal. $0.3l8/gal. $223.87
4096 Ib. 9.05/cwt.
12.5 gal. 9.60/gal.
57 Ib.
57 Ib.
44 gal.
390 Ib.
5.20/cwt.
7.50/cwt.
$0.3l8/gal.
8.15/cwt.
370.69
120.00
2.96
4.28
$721.80
$ 13.99
31.79
$ 45.78
193 Ib. $3-50/cwt. $ 6.76
17.75 gal. 8.12/gal. 144.13
560 Ib. $3.50/cwt.
76 Ib. $3.50/cwt,
14.75 gal. 8.12/gal,
Total Chemical Cost for Integrated Treatment
Systems
$150.89
$ 19.60
$2766"
$119.77
$122.43
$1060.50
29
-------
So that these cost figures may be related to the productive
output of the plant, Table 3 lists the amount of work plated
and the dollar sales volume for the same period of time.
The aluminum anodizing facilities were not yet in operation.
30
-------
TABLE 3
Plant Production for November, 1970
Department
No. 100
Nickel-Chrome
Automatic
No. 200
Hoist Line
Quantity of Work Processed
Sales Volume
Nickel Plated
Nickel-Chrome
Plated
Copper-Nickel
Chrome Plated
Nickel Plated
Other
No. 250
Hard Chrome Plating
No. 300
Plastic Plating
No. 400
Miscellaneous
Copper-Nickel
Chrome-Plated
Cadmium Plated
Nickel Plated
Zinc Plated
Other
No. 450
Zinc Barrel
Automatic
No. 500
Passivatlng & Blackening
No. 600
Zinc & Cadmium Rack
Automatic Zinc Plated
Cadmium Plated
45,600 ft'
45,600
91,200 Ft'
22,275 ft'
12,375
14,850 ,
49,500 ft'
6,144 ftz
496 barrels
99
13
12
620 barrels
1060 barrels
68,310 ft'
7.590 .
75,900 ft'
Total
I 7,919.67
22,374.76
6,231.24
4,326.76
7,006.79
3,684.70
6,102.22
12.611.21
$ 70,257.35
31
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SECTION VII
OPERATION OF BATCH WASTE TREATMENT SYSTEM
In the original design, the Batch System was intended pri-
marily for handling discarded process solutions such as acid
pickles, bright dips, chromate dips, cleaners, etc. A
secondary function was to provide treatment for any floor
spillage and contaminated steam condensate which might accu-
mulate. With proper operation, floor spillage and contaminated
condensate would both be very low-volume wastes, with appre-
ciable quantities resulting only accidentally as when a tank
or pipe line would leak or when a hose would be left running
unintentionally. Nevertheless, an overhead acid collection
line was provided so that discarded acidic process solutions
could be delivered to the batch acid treatment tanks fully
concentrated. As mentioned earlier, the minimum chemical
consumption and minimum resultant sludge volume can only be
realized when wastes are treated in the concentrated form.
Since most of the metals which produce sludge upon pre-
cipitation, are found in acidic solutions, the isolated acid
collection line was considered essential. Alkaline cleaners,
which generate essentially no sludge upon neutralization were
to be transferred to the alkali treatment tank via the floor
spill system.
As plant production increased through the first year of opera-
tion, it developed that far more waste was being batch treated
than had been anticipated. Investigation revealed that con-
siderable quantities of water and steam condensate were being
allowed to enter the floor spill system. The water was
backing up out of the rinse water sewer line inlets because the
sewers were hydraulically overloaded, and the condensate was
being discharged to the floor rather than returned to the
boiler as originally planned. The rinse water sewers were
overloaded because large volumes of cooling water were being
discharged into them. Since the pH adjustment sump and
settling tank for the rinse waters could accept only a
limited flow of water before being hydraulically overloaded,
the sewer system feeding them was designed for the anticipated
rinse water flow. Rather than use a conventional recirculated
water system to cool the plating solutions, the Company
elected to use well water on a "once-through" basis and dis-
charge it to the rinse water sewers. Since the flow of cooling
water at times equaled the design rinse water flow, the sewer
system was overloaded and water backed up out of the inlets
and onto the floor.
32
-------
In addition to these problems, the portable pump which was
recommended for discharging acidic process solutions into the
overhead line developed several problems and failed to oper-
ate properly. Because of the pump difficulties/ plant per-
sonnel started discharging acid solutions by draining them
to the floor spill system. This practice exposes the con-
crete floor and other equipment to corrosions and also pre-
sents an opportunity for the acids to be diluted with water
or mixed with alkaline cleaners, both of which are deleterious
to treatment results. Specifications and recommendations
for the purchase of a more suitable portable pump where
supplied to the company in May of 1969.
As a result of these problems, the waste treatment operator
was required to batch treat and test an average of 8,000-
10,000 gallons per day of mixed dilute wastes as opposed
to 2,500-3,500 gallons per day of known process solution,
discarded under controlled conditions. If the intended pro-
cedures were followed, the operator could empty the treat-
ment tank prior to a scheduled dump, and then proceed to
add the amount of treatment chemical which his experience
indicated would be needed for the given process solution.
Because of the water problem, operation of the batch system
was nearly a full-time job during the daylight shift, and
frequent problems arose on the night shifts because of
excessive waste accumulation and flooding of the system.
.Slow, steady progress has been made toward eliminating this
problem by attempts at sealing the rinse water inlets and
returning the steam condensate, but the cooling water is
still wasted into the rinse water system, and the seals on
the sewer inlets are not completely effective. In November,
1970, 159,647 gallons were batch treated while only 54,310
gallons of process solution, waste treatment solution, and
filter backwashings actually required treatment. The dif-
ference of 105,337 gallons consisted of water which should not
have required operator attention and chemical consumption.
In an attempt to improve the situation, two holding tanks
were recommended to receive the cooling waters from acidic
and alkaline process solutions. These tanks will allow
automatic instruments to monitor the waters for possible
contamination by process solution, and they will permit
the water to be pumped back into the plating shop for use
as rinse water in the tanks which now receive fresh well
water. The recommended location of the two tanks is shown
in Figure 4.
33
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To ease the scheduling of batch treatments and allow the
safe accumulation of floor spillage during the night shifts,
the Company has considered installation of two large holding
tanks to supplement the existing collection-treatment tanks,
but the load on the batch system is slowly decreasing, due
to reduced spillage.
In January of 1970, the analyses on the sludge filter beds
began to show excessive levels of copper and nickel and
further investigation showed that ammonium ion was accumu-
lating and probably complexing them. The operation of the
system was then modified to include additions of calcium
(lime) and sulfide (sodium polysulfide) compounds to each
treated batch so as to assist in completely precipitating
the metals.
Following treatment, the wastes from the batch system are
pumped directly into the Sludge Filter Beds. These beds
also receive sludges from the rinse water settling tank
and from the Integrated systems, but 75% of the input is
from the batch treatment system. Therefore, the quality
of the water in the beds is most directly related to the
effectiveness of the batch treatment. Table 4 lists the
analyses done on the supernatant liquid from the beds
during the first year of operation and also for the month
of November, 1970.
34
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Table 4. SLUDGE FILTER BED EFFLUENT ANALYSES
All figures except pH are in mg/1
Sample date
May,
June,
Oct. ,
Nov. ,
Dec. ,
Jan. ,
Feb. ,
Nov. ,
1969
1969
1969
1969
1969
1970
1970
1970
9
9
9
9
9
9
9
7
PH
.63
.50
.11
.20
.20
.60
.40
.60
CN
0
0
0
.01
.04
.02
none
0
0
.02
.02
none
0
.43
Cr+ Cu
0.03
none 0
none 2
0
none 2
1.21 3
none 7
0.13 0
.63
.21
.15
.34
.05
.50
.31
Ni Zn
0
6
1
2
15
8
0
.43
.2
.85
.63 0.72
.23 0.65
.20 1.74
.25 0.14
Cd
4.67
1.74
2.34
0.17
35
-------
The cost of operating the batch treatment system has been
excessive because of the problem with unnecessary water
accumulation described earlier. This situation requires
the operator to be in nearly constant attendance and makes
the chemical consumption unnecessarily high. When treating
cyanide and chromium, the cost of the chemicals required to
adjust the pH of the collected batch before and after the
chlorination (cyanide) or reduction (chromium) can be more
of a factor than the cost of the chlorine or reductant.9
For example, one pound of cyanide (CN ) in one gallon of
waste solution can be treated for approximately $0.92,
while the same amount of cyanide in 800 gallons of solution
costs about $1.68 to treat. The difference is due to the
requirements for acid and alkali for pH correction and to
the inefficiency of the chlorination reaction in dilute
solution. If cyanide and chromium are mixed in a waste,
.these costs are even more excessive. Thus, the regenera-
tion and control of the material entering the batch treat-
ment system are extremely important. The more dilute the
wastes to be treated, the more exhorbitant are the chemi-
cal costs. Table 5 lists the chemical consumption and
cost figures for the Batch Treatment operation during
November, 1970.
36
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Table 5. CHEMICAL CONSUMPTION OF BATCH TREATMENT
SYSTEM - NOVEMBER, 1970
Chemical Consumed
Quantity Unit Price Monthly Cost
Sulfuric Acid
Caustic Soda (50%
liquid)
Sodium Metabisulfite
Sodium Hydrosulfite
Calcium Hypochlorite
Sodium Polysulfide
Hydrated Lime
337 gal.
752 gal.
1072 Ibs.
368 Ibs.
240 Ibs.
399 Ibs.
645 Ibs.
$0.534/gal.
0.318/gal.
10.30/cwt.
29.75/cwt.
30.00/cwt.
52.00/cwt.
10.25/cwt.
$ 179.96
239.14
110.42
109.48
72.00
207.48
66.11
Total Chemical Cost for Batch Treatment System - $ 984.59
37
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SECTION VIII
OPERATION OF RINSE WATER SYSTEM
An automatic pH controller-recorder maintains the rinse water
effluent within the desired range by adding either 10% sul-
furic acid solution or 20% caustic soda solution to the pH
adjustment sump. Following this pH correction, the stream
enters a rectangular, open-basin settling tank for separation
of the precipitated solids. (See Figure 10) The sludge
which accumulates in the settling tank must be removed three
times per year. A portable pump is used to draw the sludge
from the bottom of the tank and transfer it to one of the
adjacent sludge filter beds.
Figure 10 - Rinse Water Settling Tank
38
-------
At the overflow end of the settling tank, a wet well is
provided for the Reuse Water Supply Pump which returns a
portion (see page 45) of the rinse water stream to the
plating shop. That portion not returned overflows the
pump well and is combined with the filtrate from the sludge
filter beds before it is discharged to the storm sewer. It
was intended to control the dissolved salt concentration in the
rinse water system by using fresh well water in selected
rinse tanks in the plating lines. The amount of fresh water
added at these tanks would then determine the rate of over-
flow from the reuse water pump well. This overflow to sewer
would constitute a "blow-down" of the system which could
be regulated to achieve the optimum amount of water reuse.
If too little fresh water were added, inadequate rinsing
would lower the quality of the finishes. It is still
impossible to determine the maximum percentage of the rinse
water^stream which can be reused because the cooling waters
are discharged into the system causing an excessive blow-
down.
However, the total amount of fresh water available to the plant
is limited to 300 GPM by the pumping rate of the well, and the
evidence indicates that there will be no problem in doubling
the plant's production facilities with only this amount of
fresh water input.
Once per day the rinse water is checked for the major con-
taminants using semi-quantitative spot test procedures, and the
results are recorded on the analysis record sheet. Until
recently, the effluent was also given a complete analysis by
an outside laboratory once per month. This work is now done in
the plant's laboratory which is equipped for full colori-
metric analyses. The electrodes of the pH controller are
removed from the control sump bi-weekly for cleaning, inspec-
tion, and standardization against buffer solutions.
One of the advantages shared by the Integrated Treatment Systems
and the water reuse system is that they serve as their own
enforcement of good operating practice. If proper control is
not maintained, and the recirculated solution or water becomes
contaminated, the quality of the metal finishing suffers since
the parts are being rinsed in the contaminated solution.
Ordinarily, when a waste treatment system goes out of control
and the effluent discharge becomes contaminated, the plant
personnel have only their conscience with which to contend.
Here they must also contend with sub-standard production. An
example of this occurred when a night-shift operator on the
aluminum anodizing line mistakenly rinsed his work pieces in
39
-------
the De-ionized water rinse after removing them from the bright
dip solution which is very high in phosphoric acid concentra-
tion. The deionized water is intended to be an ultra-pure
rinse, used only after a normal fresh water rinse. In the
morning, when the mistake was discovered, the deionized water
rinse was immediately discarded. Since this tank has its
drain connected to the rinse water sewers, the entire re-
use water system soon contained phosphate ion in the range
of 8-10 ppm. A mysterious resistance of zinc-plated work to
bright dipping and chromating the next day was traced to the
fact that the fresh zinc surface became passive while sitting
for more than ten minutes in reuse water on the programmed
hoist machine. The combination of unusually long residence
in the rinse station and a few parts per million of phos-
phate thus interfered with production on that machine. Re-
duction of the phosphate level restored normal operation.
After the plant had been in operation for several months,
but before the aluminum anodizing equipment was installed,
Lancy Laboratories recommended that the installation of an
additional Integrated system be considered. The new pro-
cess, which had just been developed, was intended to elimi-
nate the carry-over of large amounts of aluminum to the rinse
water system. The aluminum which precipitates from dilute
rinses is a very voluminous sludge which settles easily,
but does not compact or dewater well. As a result, the fre-
quency of settling tank and sludge filter bed clean-out
would be greatly increased when the anodizing line was placed
in operation, as would the costs for sludge hauling. The
newly developed Integrated Aluminum Treatment System creates
a sludge having less than one-tenth the volume of that pro-
duced by normal neutralization and settling of the rinse
waters, and its cost can be amortized by savings in sludge
handling expenses. However, the system was not installed,
and to eliminate sludge handling, the Company elected to
discharge the rinse waters from the anodizing line to the
municipal sanitary sewer system.
Table 6, which follows, gives the results of a number of
analyses of the Rinse Water Effluent from the plant. This
is the stream which is discharged as a "blow-down" from the
rinse water settling tank, and it is the same water as is
being returned to the plant by the Reuse Water Pump. All are
"grab samples" taken at midday when the contaminant concen-
trations would be at a maximum. Since this is a reuse water
system with more than 50% of the flow being recycled, the need
for composite sampling is obviated. The system itself serves
to average and accumulate contaminants over many hours of
40
-------
operation, and since the samples are taken after several hours
of peak production, the results indicate the worst possible
condition of the system.
The analysis results shown in Tables 6 and 7 were obtained by
use of the following procedure:
Cyanide - "ASTM Standards - Part 23 - Industrial Water;
Atmospheric Analysis" (Oct. 1968)
Dissolved and Suspended Solids - EPA - "Methods for
Chemical Analysis of Water and Wastes" -
Nov. 1969.
All Others - "Standard Methods for the Examination
of Water and Wastewater" - Twelfth Edition -
1965.
Where "none" is reported, the results were below the limits of
detection for the procedure employed. For all parameters
listed, the limit of detection can be considered to be
0.01 mg/1.
41
-------
TABLE 6
Results of Rinse Water Effluent Analyses
ro
Sample Date
April, 1969
May, 1969
June, 1969
July, 1969
August, 1969
September, 1969
October, 1969
November, 1969
December, 1969
January, 1970
February, 1970
April, 1970
November, 1970
February, 1971
pH
7.88
8.26
8.54
7.55
7.99
7-61
7.41
7.86
7.41
7.60
7.70
7-30
8.06
8.23
CN
0.06
0.08
none
none
0.03
none
none
none
0.06
0.12
none
0.02
0.01
none
All
Cr+6
0.10
0.06
none
none
none
none
none
none
none
none
none
none
none
0.13
values except pH are in
Cr+3
-
none
-
none
none
none
none
none
none
none
none
none
none
0.10
Cu
none
none
0.01
0.02
0.06
0.19
0.04
0.02
0.06
0.10
0.02
0.17
0.14
0.40
Nl
0.48
0.10
0.20
0.24
0.12
0.13
0.60
0.46
none
0.20
0.06
0.05
none
0.25
mg/1.
Zn
none
0.13
0.12
0.55
0.79
1.57
1.31
2.02
1.10
1.36
1.06
2.20
0.56
2.94
Hardness
Cd As CaCOa
0.15
0.25
0.07
0.14
0.22
0.32
0.23
0.28
0.21
0.42
0.29
0.45
0.25
0.25
-
-
-
212
218
218
212
212
-
225
255
218
198
219
Suspended
Solids
10.2
15-1
14.0
10.6
16.0
18.1
8.6
13.6
11.6
21.3
17.1
14.9
12.0
16.0
Dissolved
Solids
738
704
1003
564
611
701
1041
724
719
881
647
655
530
540
-------
The levels of zinc and cadmium in the effluent are somewhat
higher than desirable (i.e. - 1.0 mg/1 Zn and 0.01 mg/1
Cd) and this is due to drag-out of these metals from the
acid pickle solutions in the zinc and cadmium plating lines.
The pickle solutions are intended to clean and descale the
surface of the work pieces prior to electroplating. How-
ever, when a rack of parts with bad plating comes off the
machine, it is recycled and the cadmium or zinc on the
pieces is stripped in the pickle solution. As the concen-
trations of these metals increase in the pickle, the levels
in the effluent follow. Additional treatment facilities may
be required if this input of heavy metals to the pickles
cannot be eliminated.
The actual effluent discharged by the plant to the storm
sewer is a combination of the Rinse Water Effluent and the
filtrate which drains away from the Sludge Filter Beds. This
Combined Effluent Discharge is sampled just before it
enters the storm sewer and the results of a number of
analyses are summarized in Table 7.
43
-------
TABLE 7
Results of Combined Effluent Discharge
Analyses
All values except pH
Sample
Date
May, 1969
July, 1969
Aug., 1969
Sept. 1969
Oct. 1969
Nov. 1969
Dec. 1969
Jan. 1970
Feb. 1970
Apr. 1970
Nov. 1970
£H
9.06
7.92
8.34
7-37
7.49
7.65
7.40
9.10
7.80
7-30
8.82
Cn
0.01
none
none
0.15
none
none
none
0.02
none
none
none
Cr+6
0,05
0.18
0.32
none
none
none
none
0.07
none
none
none
Cr+3
none
0.04
_ _
none
none
none
none
none
none
none
0.05
Cu
none
0.02
0.01
0.08
2.21
0.03
0.03
0.11
none
0.15
0.09
Ni
0.04
0.18
0.18
23.4
6.2
0.50
0.05
0.45
0.45
0.60
none
Zn
0.04
0.15
0.28
2.0
1.02
2.25
1.55
0.20
0.88
2.28
0.03
Cd
0.16
0.15
0.14
0.42
0.23
0.28
0.21
0.30
0.35
0.45
0.07
are in mg/1
Fe
-
-
-
-
0.24
0.18
0.25
0.45
0.60
0.75
none
S0««
-
-
-
-
170
272
200
513
480
400
163
Cl
-
-
-
-
142
355
425
106
28
17
7
76 none
Hard- Sus- Dissolved
ness as pended
Oil CaC03 Solids
- - 20.0
- - 66.8
15-2 847
63.1 5940
none 212 9.0 595
none 211 13-1 1727
none 246 14.0 1028
none 225 38.9 3214
none 255 17-1 770
none 218 16.8 773
none 212 12.0 550
-------
While the maximum percentage of the total water flow which
can be reused has not yet been determined, the following
table gives the relative amounts of fresh and reused water
passed through the system over a week of recent production.
Table 8. RELATIVE CONSUMPTION OF FRESH AND REUSED WATER
Date
Fresh Water
Consumption
Reused Water Reused Water
Consumption Percentage
2/22/71
2/23/71
2/24/71
2/25/71
2/26/71
2/27/71
250,100 gallons
327,800
318,600
292,200
270,600
118,300
323,100 gallons
332,700
367,500
332,700
332,700
102,000
1,577,600 gal.
1,790,700 gal.
56.37%
50.37
53.53
53.24
55.15
46.30
53.16% ave,
If the company were required to purchase their water from
the local municipal water supply system, they would be charged
at the rate of $0.22 per 100 cu. ft. At this rate, the re-
used water system would be saving them $526.68 per week based
on the above consumption figures. Since well water is being
used presently, and the pumping costs are negligible, these
savings are merely theoretical. However, they are included
as an example of the economics which would apply to a plating
shop not able to draw so readily on a natural resource. The
distribution of water through the plant is summarized in the
following table. The Department numbers correspond to those
used in Table 3 and Figure 1.
45
-------
Table 9. DISTRIBUTION OF WATER CONSUMPTION BY
PRODUCTION DEPARTMENTS
All values are in gallons per minute.
Dept . No
100
200
250
300
400
450
500
600
800*
850
880*
900
Reuse Water
Dept. Name Consumption
Nickel Chromium Automatic
Hoist Line
Hard Chromium Plating
Plastic Plating
Miscellaneous Barrel Line
Zinc Barrel Automatic
Passivating & Blackening
Zinc & Cadmium Rack Automatic
Zinc Black & Tin Plating
on Aluminum
Anodizing
Iriditing
Stripping
48.6
24.3
15.0
—
60.0
27.9
6.0
70.0
25.0
24.0
48.0
12.0
Fresh Water
Consumption
22.1
49.8
9.1
60.8
49.1
5.1
10.9
8.0
34.1
6.8
360.8 GPM
255.8 GPM
* Areas put into production recently and not shown in
Figure 1.
46
-------
Chemical costs for the rinse water treatment include only
the sulfuric acid and caustic soda used for pH control. For
the same month of November, as considered for the other
systems, the chemical costs are:
Table 10. CHEMICAL CONSUMPTION OF RINSE WATER SYSTEM
November, 1970
Chemical Consumed Quantity Unit Price Monthly Cost
Sulfuric Acid 27 gal. $ 0.534/gal. $ 14.42
Caustic Soda
(50% liquid) 216 gal. 0.318/gal. 68.69
Total Chemical Cost for Rinse
Water System $ 83.11
Offsetting some of the operating costs for the waste treat-
ment systems are the savings due to water reuse. If the
equivalent purchase cost of the reuse water is considered
for the same month of November, it represents a savings
of $2,106.72.
47
-------
SECTION IX
SLUDGE HANDLING OPERATIONS
All precipitates formed by the various treatment reactions
are accumulated in concrete block sludge filter beds which
operate on a unique principle to dewater and thicken the col-
lected sludges. Two beds are provided and they are used
alternately with one being allowed to dewater for several
weeks while sludges are directed into the other. Before the
bed in use is filled, the first one is emptied by a septic
waste hauling truck which carries the thickened slurry to a
sanitary landfill area. At the present time the filters must
be emptied approximately every 2-1/2 weeks. Sludges are pumped
into the filters from each of the five Integrated Systems,
from the batch treatment system, and from the rinse water
settling tank.
The amount of water held by a flocculent metallic precipitate
is directly dependent upon the conditions prevailing when the
precipitated compound is formed. While the sludges can be
"conditioned" after they are formed, the effectiveness of
this conditioning depends upon the initial nature of the
slurry and thus, on the influences present during formation.
As discussed earlier, the sludges in the Integrated Systems
are formed under concentrated conditions and are thus relatively
dense and dewatered when pumped to the filter bed. Ideally,
batch treatment of discarded process solutions would likewise
generate good sludges, but difficulties with this operation
have prevented this desirable result. Sludges formed in the
rinse water system are very light and typically contain only
0.25%-0.50% dry solids, but they are a very negligible portion
of the sludge produced at this plant.
Roughly speaking, the discarded process solutions contain
80-90% of the chemical waste load in a plating operation and
thus the batch treatment system contributes most of the sludge
to the filter beds. The aforementioned difficulties with the
batch treatment operation therefore have a direct and signif-
icant effect upon both the performance of the filter beds and
the costs for sludge hauling.
The principle of operation of the filter bed is complex and
involves a number of phenomena which combine to influence the
overall performance of the unit. However, it is essential that
the input sludges be amenable to flocculation, coagulation,
and settling. If compounds which interfere with these three
functions are present in the slurry pumped into the filter,
its operation will be severely restricted. Some alkaline
48
-------
cleaning compounds contain high levels of peptizing agents
which are effective in holding extremely small particles in
suspension. When precipitates are formed in the presence
of high concentration of these materials, the tiny particles
of precipitated compound which are formed initially, cannot
coagulate so as to form floes large enough to settle. When
such a waste is put into the sludge filter, the water es-
caping through the concrete block wall naturally carries
along the dispersion of fine particles which can deposit
in the pores of the concrete and eventually stop further
seepage. Wastes which are dilute prior to treatment are
more susceptible to the effects of a given concentration
of such a peptizing agent since the initially-formed particles
are more widely separated at formation. Thus, dilution and
the presence of peptizing agents ar6 two factors which ad-
versely affect the filter performance and which are syner-
gistic in their effects. Oil is another material which
interferes with filter performance by collecting in the pores
of the concrete and displacing water thus preventing capillary
attraction which is one of the primary mechanisms in the func-
tioning of the unit.
Of the two filter beds in this installation, one is still
functioning reasonably well, while the other is almost com-
pletely ineffective. The units were constructed at the
same time and of identical materials, and both performed
properly when new. As described earlier, the operation of
the plant and waste treatment system have been such that:
(1) acids are diluted prior to treatment, (2) alkaline
cleaners may be mixed with acids or metal-containing wastes
prior to treatment, and (3) oil was allowed to drain to the
floor inadvertently in Department 500. Thus it may be
assumed that the inoperative filter bed is in its present
condition as a result of one or more instances where a com-
bination of factors caused the concrete block to be adversely
affected. While the south filter bed performs much better
than the north one, neither of them even approaches the
rates which were experienced when they were new. While in
use, both beds require that some clear, supernatant water
be manually decanted to avoid overfilling. This may be
attributed to a combination of the fact that five to ten
times as much waste is put into the beds as v;as antici-
pated during design and the fact that both beds may have
been adversely affected by the methods of operation men-
tioned above. Table 9 compares the performance of the two
beds by indicating the amount of water discharged through
the block wall in a similar period of time.
49
-------
Table 11. COMPARISON OF SLUDGE FILTER BED PERFORMANCES
North Filter
Bed
South Filter
Bed
Time Period
Slurry Input to Filter
Sludge Removed from Filter
at Cleanout
Water Decanted from Filter
Water Removed by Filter
3/6 - 3/25/71 2/22 - 3/5/71
92,940 gal,
11,480 gal.
53,480 gal.
27,980 gal.
93,217 gal.
7,000 gal.
5,460 gal.
80,757 gal.
Recommendations have been made to eliminate the conditions
antagonistic to filter performance by: (1) using the
overhead acid collection line to keep dilution effects to
a minimum; (2) avoiding discharges of oil to the floor;
and (3) discharging the neutralized alkaline cleaning solu-
tions directly to the sanitary sewer system so as to avoid
their being mixed with sludge-producing raw wastes. These are
in addition to the long-standing recommendation to eliminate
unnecessary discharges of water to the floor spill system.
To indicate the effectiveness of the filter beds as sludge
thickening devices, the solids content of the slurries put
into, and removed from, the south bed were checked for
the same period as covered by the above study. A composite
sample of all material pumped into the bed during the two-
week period was collected and the dry solids content found
to be 0.51%. At the end of this period (3/5/71), sludge
discharges were switched to the north bed and the south bed
was allowed to dewater for five days before being emptied
by the sludge hauling truck. The slurry pumped into the
truck had a dry solids content of 5.12%, indicating a ten
to one reduction in the volume of material to be hauled
away. Figure 11 is a photograph showing the condition of
the sludge as it is pumped to the truck. The log is to pre-
vent damage to the concrete block walls by freezing.
50
-------
Figure 11 - Thickened Sludge in Filter Bed
A special sludge filter panel, which works on essentially the
same principles as the concrete block walls has been recom-
mended to improve the performance of the north bed, but it
has not yet been installed.
For the month of November, 1970, about 5,700 gallons of sludge
were hauled away from the Filter Beds at a cost of $103.00.
The slurry, at the time of clean-out of the bed, contained
about 5% dry solids by weight.
51
-------
SECTION X
GENERAL ECONOMIC CONSIDERATIONS
The capital costs associated with the waste treatment system
are summarized in the following table:
Table 12. SUMMARY OF CAPITAL COSTS
A. Equipment Costs
1. Waste Treatment Room $ 44,292.01
2. Treatment Wash Tanks in
Process Lines 20,637.00
3. Miscellaneous 6,465.68 $ 71,394.69
B. Installation Costs
1. Piping $ 60,830.56
2. Electrical 7,248.11
3. Mechanical Construction
and Erection 40,500.00
4. Underground Sewers 30,441.00 $ 139,019.67
C. Engineering Costs
1. Process Design $ 12,500.00
2. Detail and Mechanical
Engineering 4,536.10 $ 17,036.10
Total Capital Cost $ 227,450.46
Monthly operating costs were tabulated for November, 1970,
and are summarized in the following table. The savings
attributed to water reuse are indicated as partially off-
setting the operating costs.
52
-------
Table 13.
SUMMARY OF MONTHLY WASTE TREATMENT
SYSTEM OPERATING COSTS -
NOVEMBER, 1970
Fixed Costs
Depreciation - 15 years
Operating Costs
Integrated Treatment System
Chemicals
Batch Treatment System Chemicals
Rinse Water Treatment System
Sludge Hauling
Electric Power
Laboratory Technician - Operator
Total Monthly Operating Costs
Total Monthly Costs
Savings Due to Reuse of Effluent Water
Adjusted Monthly Costs
$1,060.50
984.59
83.1U
103.00
283.15
752.32
1,263.61
3,221.67
$ 4,485.28
-2,106.72
$ 2,378.56
To make these operating costs more meaningful, they must be
related to the amount of work being processed in the plating
operations. Since many different types of parts and finishes
are involved, it is impossible to relate the treatment costs
to pounds of material plated or square feet of surface plated,
except for specific types of products and finishes. Therefore,
on an overall plant scale, the company's product can be con-
sidered to be one hour of production time having a certain
value. The waste treatment costs may then be expressed per
hour and the two combined to give a figure for the amount
that waste treatment costs contribute to the plant's product
cost. In the month of November, 1970, the plant was opera-
ting 127 hrs. of production, and Tables 3 and 13 indicate
that the product value was $553.20 per hour and the waste
treatment costs were $18.72 per hour. Thus, the operation
of the waste treatment system costs the company $0.033 per
dollar of value added to the product.
*refer to Table 16 for detailed breakdown.
53
-------
A breakdown of the treatment chemical costs by several types
of typical production may be of value to others in the metal
finishing industry. The following table lists the approxi-
mate percentages of the operating costs which may be attrib-
uted to specific types of production.
54
-------
Table 14. DISTRIBUTION OF TREATMENT CHEMICAL COSTS BY PRODUCTION TIME
Figures show percentage of total cost for each system and respective calaulated
cost for month of November
Dept . CN
100 Nickel
Chrome
Cr I
37%
$16.94
Cr II Cu
4%
$6.04
Rinse Water
Ni pH Control Batch
24% 8% 8%
$4.70 $6.65 $78.77
Automatic*
300 Plastic
Plating
450
Zinc Barrel 38%
Automatic $274.28
600 Zn
& Cd Rack
Automatic
14%
$101.05
24% 3% 20% 6% 11% 5%
$10.99 $4.53 $24.49 $1.18 $9.14 $49.23
28%
$42.25
46%
$69.41
11% 9%
$9.14 $88.61
12% 20%
$9.97 $196.92
*Figure for nickel-chromium production only - nickel plated production omitted,
"Note: Percentage figures do not total 100% for the systems because departments
200,250, 400, 500, and the hoist line were omitted from the tabulation.
Collection of data on costs to be assigned to these irregular production
operations was nearly impossible."
-------
Table 15.
WASTE TREATMENT CHEMICAL COSTS PER
UNIT OF PRODUCTION
Cost per Unit
Dept. Production Chemical Costs of Production
100 Nickel-Chrome 45,600 ft.2
Automatic
300 Plastic
Plating
450
Zinc Barrel
Automatic
600
Zn & Cd Rack
Automatic
6,144 ft.2
1060 Barrels*
75,900 ft.2
$113.10 $2.48/1000 ft.2
99.56 $16,20/1000 ft.2
414.28 39.08/100 barrels
377.35 4.97/1000 ft.2
*14" x 36" plating barrels containing approximately
100-200 Ibs. of small parts with a surface area of
40-60 ft.2
The high cost associated with plating on plastics is due to
the very concentrated chromic acid etch solution which must be
used in preparing the plastic to the relatively large number
of surface preparation operations; and to the chelated-type
plating solutions which must be employed.
The unit cost for Zinc and Cadmium Rack Plating is inflated due
to the excessive batch treatment costs discussed previously.
As can be seen from Table 15, the batch treatment expenses
are the largest factor contributing to the chemical cost for
this operation. It is reasonable to assume that at least a
25% reduction in the cost per unit of production could be
achieved by correcting the problems in the batch treatment
operation.
56
-------
TABLE 16
WASTE TREATMENT CHEMICAL COSTS
NOVEMBER 1970
System
Chrome
I
Chrome
II
Copper
Nickel
Cyanide
pH
Control
Acid
and
Alkali
Batch
Treatment
Consumed Chemicals
Liquid Caustic
Sulfur Dioxide
Soda Ash
Hydrazine Hydrate
Soda Ash
Hydrazine Hydrate
Soda Ash
Liquid Caustic
Chlorine
LD Inhibitor
Calcium Chloride
Magnesium Chloride
Sulfuric Acid
Liquid Caustic
Sulfuric Acid
Liquid Caustic
Sodium Metabisulfite
Sodium Hydrosulfite
Chlorine
Calcium Hypochlorite
Sodium Polysulfide
Hydrate Lime
Quantity
Consumed
44 gal.
390 Ibs.
193 Ibs.
17.75 gal.
76 Ibs.
14.75 gal.
560 Ibs.
^
704 gal.
4096 Ibs.
12.5 gal.
57 Ibs.
57 Ibs.
27 gal.
216 gal.
337 gal.
752 gal.
1072 Ibs.
368 Ibs.
0 Ibs.
240 Ibs.
399 Ibs.
645 Ibs.
Unit
Price
$0.318/gal.
8. 51/cwt.
$3. 50/cwt.
8.12/gal.
$3. 50/cwt.
8.12/gal.
$3. 50/cwt.
$0.318/gal.
9.05/cwt.
9.60/gal.
5.60/cwt.
7. 50/cwt.
$0. 534/gal.
0.318/gal.
$0. 534/gal.
0. 318/gal.
10. 30/cwt.
29.75/cwt.
9.05/cwt.
30.00/cwt.
•52.00/cwt.
10.25/cwt.
GRAND TOTAL
Cost
For Month
$ 13.99
31.79
$ 45.78
$ 6. 76
144.13
$ 150.89
$ 2.66
119.77
122.43
$ 19.60
$ 19.60
$ 223.87
370.69
120.00
2.96
4.28
$ 721.80
$ 14.42
68.69
$ 83.11
$ 179.96
239.14
110.42
109.48
0.00
72.00
207.48
66.11
$ 984.59
$2128.20
57
-------
SECTION XI
REFERENCES
1. U. S. Department of Health, Education and Welfare,
Public Health Service Drinking Water Standards (1962)
2. U. S. Patent No. 2,725,314
3. Ceresa, M. and Lancy, L. E., "Waste Water Treatment,"
Metal Finishing Guidebook - Directory pp 766 (1971)
4. McDonough, W. P., and Steward, F. A., "The Use of the
Integrated Waste Treatment Approach in the Large
Electroplating Shop," Chemical Engineering Progress,
67, 107, pp 428 - 431 (1970)
5. U. S. Patent No. 3,325,008.
6. Stevens, F., Fischer, G., and MacArthur, D., Analysis of
Metal Finishing Effluents and Effluent Treatment
Solutions, Robert Draper, Ltd., Teddington, England
(1968)
7. Clarke, M., "Rinsing: Part I - Theory of Recirculating
and Chemical Rinsing," Transactions of the Institute
of Metal Finishing, Vol. 46, pp 201-208 (1968)
8. U. S. Patent No. 3,682,701
9. Lund, H. F., Industrial Pollution Control Handbook,
"Pollution Control in Plating Operations," p. 12-10,
McGraw-Hill, New York (1971)
58
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-670/2-74-042
3. RECIPIENT'S \CCESSION-NO.
.TITLE AND SUBTITLE
WASTE WATER TREATMENT AND REUSE IN A METAL
FINISHING JOB SHOP
5. REPORT DATE
July 1974; Issuing Date
6. PERFORMING ORGANIZATION CODE
.AUTHOR(S)
S. K. Williams Company
8. PERFORMING ORGANIZATION REPORT NO.
.PERFORMING ORGANIZATION NAME AND ADDRESS
S. K. Williams Company
4600 N. 124th Street
Wauwatosa, Wisconsin 53225
10. PROGRAM ELEMENT NO.
1BB036/ROAP 21AZO/TASK 06
11. CONTRACT/GRANT NO.
12010 DSA
2.SPONSORING AGENCY NAME AND ADDRESS
National Environmental Research Center
Office of Research and Development
D.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
5.SUPPLEMENTARY NOTES
16. ABSTRACT
A complete waste water treatment system has been installed as part of a new
S. K. Williams Company job plating facility, to.make the effluent suitable for dis-
charge. Most of the metal finishing processes carman to the industry are included in
the plant. Despite the wide range of toxic materials used in these proceses, the new
treatment system is providing an effluent essentially meeting the limitations on
toxic ions given in the U.S. PHS drinking water standards.
Five integrated waste treatment systems, each designed for a specific type of
waste compound, are used to protect the rinse waters from contamination by process
solution drag-out. A batch-type treatment system handles miscellaneous and intermit-
tent discharges. The system design aims for a minimum volume of sludge production and
a unique and economical sludge dewatering technique is included. Improved rinsing
efficiency is achieved through the use of the integrated chemical rinses, thus
permitting the plant to operate on a minimum water supply.
Chemical reaction efficiency was considered in the design of each phase of the
treatment system, to insure reduced chemical consumption and maximum economy of
operation. Data is presented on the operating and capital costs for the entire
system and operating experiences are described.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
*Metal finishing, Industrial wastes
Cyanides, Chromium, Nickel, Zinc,
Copper, Cadmium, Waste treatment,
Water treatment, Metals
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
*Heavy metals, Waste
water treatment,
Reuse
13B
18. DISTRIBUTION STATEMENT
19. SECURITY CLASS (ThisReport}
UNCLASSIFIED
21. NO. OF PAGES
67
RELEASE TO PUBLIC
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
59
U.S. GOVERNMENT PRINTING OFFICE: !97'i-757-58V5333 Region No. 5-11
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