EPA-R2-73-269
JUNE 1973
Environmental Protection Technology Series
Treatment of
Complex Cyanide Compounds
for Reuse or Disposal
I
55
O
5SSZ
\
LU
CD
Office of Research and Monitoring
. Environmental Protection Agency
Washington, D.C. 20460
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL
PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and
methodology to repair or prevent environmental
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.
-------
EPA-R2-73-269
June 1973
TREATMENT OF COMPLEX CYANIDE
COMPOUNDS FOR REUSE OR DISPOSAL
by
Thomas N. Hendrickson
Dr. Louis G. Daignault
Project #12120 ERF
Project Officer
Thomas Devine
New England Basins Office, EPA
240 Highland Avenue
Needham Heights, Massachusetts 02194
Prepared for
OFFICE OF RESEARCH AND MONITORING
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402
Price $2.10 domestic postpaid or $1.78 GPO Bookstore
-------
EPA Review Notice
This report has been reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the
views and policies of the Environmental Protection Agency,
nor does mention of trade names or commercial products con-
stitute endorsement or recommendation for use.
ii
-------
ABSTRACT
Complex cyanides (fcrro-and fcrricyanidc) in industrial waste
water effluents impose a direct threat upon the environment.
Methods to recover or destroy these compounds were evaluated
in laboratory studies. The techniques tested include electrol-
ysis, ozonation, chlorination and heavy metal ion precipitation.
The study was conducted to determine the feasibility of using
one or more of these methods to reduce the concentration of
ferricyanide in both concentrated (10,000 to 100,000 mg/1) and
dilute (10 to 100 mg/1) waste effluents.
Numerous analytical procedures-were developed to enhance the
accuracy of sample analysis over the concentration range studied.
Ferrocyanide can be oxidized to ferricyanide in overflow photo-
graphic color process bleaches using either electrolysis or
ozone and the waste bleach recirculated for reuse in the process.
Dilute concentrations of ferricyanide can be destroyed using
ozone or chlorine under proper conditions of temperature, pH,
and catalyst addition.
A cost analysis is included for all methods that were judged
acceptable for commercial demonstration. Cost data for -each
procedure is based upon an "average combined" photographic
processor as defined in the report.
This report was submitted in fulfillment of Project 12120 ERF,
under the partial sponsorship of the U.S. Environmental Protection
Agency.
Key Words:
Ozone
Ferricyanide
Complex Cyanides
Photofinishing Wastes
Chemical Recovery
Waste Recycle
Precipitation
Chlorination
111
-------
TABLE OF CONTENTS
Section Description Page
I. Conclusions 1
II. Recommendations 3
III. Introduction 5
IV. Materials § Apparatus 17
V. Procedures 21
VI. Discussion of Results 39
VII. Full Scale Ozone Bleach Regeneration
and Waste Destruction Installation--
Berkey Photo 101
/III. Acknowledgments 107
IX. References 109
X. Glossary US
XI. Appendices 119
-------
FIGURES
Description
1. Bench Top Non-Membrane Electrolysis Cell 23
2. Membrane Electrolysis Cell 25
3. Pilot Plant Non-Membrane Electrolysis
Cell 26
4. Pilot Plant Electrolytic Cell 27
5. Pilot Plant Ozone Regeneration Cell 29
6. Laboratory Ozone Generator and Air
Preparation System 30
7. Pilot Plant Ozonation or Chlorination
Cell 31
8. Precipitation Studies Stirring System 33
9. Continuous Flow Centrifugation System 35
10. Absorbance Curve for Prussian Blue 43
11. Absorbance- -Total Fe(CN)g Concentration
from 0.0 to 1.0 mg/liter at 700 mj: 44
12. Absorbance-r Total Fe(CN)6 Concentration
from 0.0 to 25 mg/liter at 700 my 45
13. Percent Unconverted Ferrocyanide- -Percent
Theoretical Conversion Non-Membrane Electrolysis
at Various Current Density Ratios SO
14. Effect of Current Density Ratio on Conversion
of Ferrocyanide to Ferricyanide in an Electro-
lytic Cell 51
VI
-------
Number Description
15. Effect pf Current Density Ratio on
Ferrocyanide Oxidation Rate for Non-
Membrane Electrolytic Cell 53
16. Comparison of the Actual and theoretical
Conversions of Ferrocyanide to Ferricyanide
in a Membrane Type Electrolytic Cell 54
17. Current-Temperature Relationship for a Mem-
brane Type Electrolytic Cell 55
18. Schematic of an Electrolytic Bleach Regener-
ation System 59
19. Conversion--Time Curve for Ozone Regeneration 61
20. Effect of Solution Flow Rate on Ferrocyanide
During Pilot Plant Ozonation Studies 67
21. Flow Schematic of A Photographic Bleach Re-
generation System Using Ozone 68
22. Rate of Degradation of Total Fe(CN). During
Ozone Oxidation Between 70P-9Q°C ° 72
23. Effect of Temperature on Fe(CN)6 During v
Acid Ozone Oxidation 7\3
.24. Ozone Destruction of Ferrocyanide: A Flow
Schematic 7*
25 Effect of Rotor Speed on Solution Clarity for
Iron Precipitation of Complex Cyanide Using
Various Flocculants S3
26 Effect of Rotor Speed on Solution Clarity for
Manganese Precipitation of Complex Cyanide
Using Various Flocculants 84
vii
-------
Number Description
27. Effect of Rotor Speed on Solution Clarity -
for Cadmium Precipitation of Complex Cyanide
Using Various Flocculants 85
28. Effect of Rotor Speed on Solution Clarity for
Copper Precipitation of Complex Cyanide Using
Various Flocculants 86
29. 1-fi-oct of Rotor Speed on Solution Clarity for
Zinc Precipitation of Complex Cyanide Using
Various Flocculants 87
30. Effect of Flow Rate on Solution Clarity for
Iron Precipitation of Complex Cyanide Using
Various Flocculants 88
31 Effect of Flow Rate On Solution Clarity for
Manganese Precipitation of Complex Cyanides
Using Various Flocculants 89
32 Effect of Flow Rate on Solution Clarity for
Cadmium Precipitation Using Various Flocculants. 90
33 Effect of Flow Rate on Solution Clarity for
Copper Precipitation of Complex Cyanides Using
Various Flocculants 91
34 Effect of Flow Rate on Solution Clarity for Zinc
Precipitation of Complex Cyanides Using Various
Flocculants 92
35 Rate of Loss of Ferricyanide During Ambient
Temperature Chlorine Oxidation 94
36 Rate of Loss of Ferricyanide During Elevated
Temperature Chlorine Oxidation 95
37 Chlorination System: Flow Schematics 99
37A Flow Diagram of Bleach Regeneration System
and Concentrated Waste Oxidation System 100
viii
-------
Number Description
58 Ozone Generation and Distribution
Systems Installed at Berkey Film
Processing Plant, Fitchburg, Mass-
achusetts 102
39 Ferricyanide Bleach Regeneration Tanks
at Berkey Film Processing Plant Fitchburg,
Massachusetts 103
40 Waste Treatment Tanks at Berkey Film Pro-
cessing, Fitchburg, Massachusetts 105
41 Photographic Solution Testing Station at
Berkey Film Processing Plant Fitchburg,
Massachusetts 106
IX
-------
TABLES
Number
II
III
IV
V
VI
VII
VIII
IX
X
XI
XIIA
XIIB
Description
Sodium Ferricyanide [Na^F
Concentration as Determined by
lodometric Titration Methods
Sodium Ferrocyanide [Na^Fe(CN)6* 10 H20]
Concentration as Determined by Cerimetric
Titration Method
Analysis of Ferro-and Ferricyanide With
Nitro Prusside as an Interfering Ion
Conversion Efficiency of Pilot Plant
Non-Membrane Electrolytic Cell
Comparison of Experimental Results ^t.6
Stoichiometric Calculations
Results of Bench Top Ozonation of Used
Photographic Bleach
Results of Ozone Destruction of Ferro-
cyanide at Ambient Temperature
Effect of Initial pH on Ferrocyanide
[Fe(CN)6~4J Concentration
Effect of Initial pH on Heavy Metal
Ferrocyanide Precipitation Rate
Effect of Excess Heavy Metal on Ferro-
cyanide [FeCCN)^"4] Solution Concentration
Effect of Temperature on Heavy Metal
Ferrocyanide [Fe(CN)g"4] Concentration
40
41
48
57
63
64
70
77
77
78
78
Heavy Metal Precipitation of Complex
Cyanides from Solutions Containing Both
Ferro-and Ferricyanide Salts (mg/1 ferrocyanide) 79
Heavy Metal Precipitation of Complex Cyan-
ides from Solutions Containing Both Ferro-
and Ferricyanide Salts (mg/1 ferricyanide) 79
-------
Number Description Page
XIIIA Effect of Settling Time .on
Ferrocyanide Concentration 80
t
XIIIB Effect of Settling Time on
Ferricyanide Concentration 80
xi
-------
SECTION I
CONCLUSIONS
1. Due to its versatility of use for both chemical recovery
and waste treatment, ozone appears to be the best choice for
control of complex cyanide pollution.
2. Photographic bleaches containing ferro-and ferricyanide
can be recovered and reused by either ozonation or electrolysis
with similar processing cost savings. The recovery is economically
justifiable.
3. Ferro-or ferricyanide can be effectively r'emoved from waste
solution by precipitation with a heavy metal ion (especially
cadmium and zinc).
4. Ferro-and ferricyanide destruction is achieved by either
ozone or chlorine oxidation in acid solution.
-------
SECTION II
RECOMMENDATIONS
The results of this project demonstrate successful methods
for eliminating toxic complex cyanides from photographic waste
waters. Since this compound represents a hazard in the form
of toxic cyanide ion, and since it is not biodegraded in munic-
ipal secondary treatment plants, it must be treated at its source*
The results of this report should be made available to:
-regulatory committees establishing chemical limits
for streams and sewers,
-municipal regulatory agencies that must be cohcerned
with the deposition of the compounds in municipal
sewers,
-municipal treatment plant operators, and
-photographic processing plants discharging toxic
complex cyanides.
Since there are obvious economic advantages for reducing the
discharge of ferrocyanides, no plant should be allowed to con-
tinue to dump waste waters containing harmful concentrations
of this compound.
-------
SECTION III
INTRODUCTION
The purpose of this investigation was to evaluate electrolytic
and ozone oxidation techniques for the regeneration of ferro-
cyanide ion for reuse and to evaluate ozonation, precipitation
and chlbrination for the treatment of waste solutions contain-
ing complex cyanides from film processing waste discharges. A
maximum residual ferrocyanide concentration of 0.4 mg/1 was
the goal established for treated waste.
-------
TOXICITY OF FERRO-AND FERRICYANIDE
Ferro-and ferricyanide compounds cause only slight skin irrita-
tion on direct contact. Neither compound is considered to be
toxic to humans. Both compounds have been reported as causing
only slight acute or chronic systemic toxicity upon ingestion.(1)
Burdick and Lipschuetz report that, "Potassium ferrocyanide and
ferricyanide have not been considered as particularly toxic (to
fish)."(2) The toxicity to fish and other acquatic life is re-
ported to be directly associated with strong ultraviolet irra-
diation, as from sunlight. (3) (4) (5) (6)
Lur'e and Panova (7) have shown that ferrocyanide first oxidizes
to ferricyanide with air in water and then photochemically oxi-
dizes to iron hydroxide, hydrocyanic acid and simple soluble
cyanides. The proposed mechanism is:
4 Fe(CN)6'4 + 02 + 2 H2Q -^ 4 Fe(CN)6~3 + 4 OH
4 Fe(CN)6'3 + 12 H20 -»• 4 Fe(OH)3 + 12 HCN + 12 CN~
Overall Reaction:
4 Fe(CN)6-4 + 02 + 14 H20 kV 4 Fe(OH)3 * 12 HCN + 4 OH" + 12 CN'
They report that the rate of oxidation of ferrocyanide in the
presence of sunlight leaves about 251 of the original concen-
tration in five days the ferrocyanide disappearing completely
in 10-12 days.
A recent government report has confirmed the increased toxicity
of complex cyanides from photographic wastes in the presence
of sunlight. The results of various tests show that the con-
version of complex cyanide to volatile cyanide (HCN) is probably
reversible and product limited. The testing was carried out
using an Ektachrome photographic waste similar to all commercial
film processing ferricyanide bleaches. The report states:
"The results of this preliminary experi-
ment indicate the conversion of complex
cyanides to highly toxic HCN occurs rap-
idly and is of great toxicological signi-
figance when disposing of untreated photo-
graphic waste. An EA-4 (Ektachrome photo-
graphic) solution of 4 ml/1 (a concentra-
tion which killed no fish in 96 hours with-
out sunlight present) generated over 220
-------
times the LC (50) of free cyanide (taken
from Water Quality Criteria, McKcc and
Wolf, 1965; California State Water Qual-
ity Control Board as 0.05 mg/1) in six
hours when exposed to sunlight. Obvious-
ly, the cyanide bleach cannot be discharged
untreated without the risk of a major fish
kill. Disposal of untreated bleach under
any circumstances is not recommended." (8)
Eastman Kodak has "Verified the conversion
to cyanide in our rather extreme experi-
ments with fish. A 6,000-W xenon lamp w^s
used to simulate sunlight. The intensity
at the surface of the aquaria was about
6,000 foot candles. Bleach baths were
prepared so that the ferricyanide and
ferrocyanide were of the order of a few
hundred milligrams per liter. Fish were
placed in the aquaria with the ferrocyanide
and ferricyanide content at that relatively
high concentration. In experiments with-
out the xenon lamp, the fish lived during
the test period just as did the fish in
the standard tap water. However, when
the same 96 hour test was repeated with the
xenon lamp illuminating the aquaria con-
tinuously, the fish died."(9)
New York is the only state specifically limiting the discharge
of complex cyanides into receiving waters. The limit is 0.4
mg/1 Fe (CN)6.
Due to the conversion of complex cyanides to toxic simple cyan-
ides, the complex should be converted to the equivalent amount
of cyanide (CN) and compared to sewer and stream limits for
that latter compound. The range of sewer codes for cyanide is
0.0 to 10.0 mg/1 (10) while the range in stream standards is
0.0 to 1.0 mg/1. These values depend upon the specific city,
stream, point of entry, etc. but represent a reasonable range
of concentrations that cyanide treatment equipment should be
capable of meeting- Ferrocyanide (Fe(CN)g'^) ion concentration
can be converted to cyanide (CN") by multiplying the ferrocyan-
ide concentration by 0.7.
Sources of Ferrocyanide and Ferricyanide
The following industries have been listed in the Condensed
Chemical Dictionary, 5th Edition, 1956 as users of ferrocyanide
and ferricyanide. (11)
-------
F ERR I CYAN IDE PliRROCYANTDH
1. Photography 1. Photography
2. Calico Printing 2. Blue Pigments
3. Is'ood Dyeing 3. Blueprint Paper
4. Tempering Steel 4. Metallurgy
S. Etching Liquid 5. Tanning
6. Production of Pigments 6. Dyes
7. Electroplating 7. Medicine
S. Leather Manufacturing 8. Reagents
9. Paper Manufacturing 9. Dry Colors
10. Sensitive Coating Ingre- 10. Tempering Steel
dient on Blue Print Paper 11. Explosives
U. Pigments 12. Process liTTgraving
12, Jjyuing 13. Lithography
13. Printing
However, since the prime contractor for Project 12120 ERF is
a photographic processor, the primary objective was the reduc-
tion of complex cyanides from this source of waste effluent.
The reuse of any waste depends upon a number of parameters,
including solution purity, chemical Concentration, temperature,
etc. Since the variables in the methods of complex cyanide
reuse studied were related specifically to photographic pro-
cessing applications, it is not anticipated that the systems
recommended for this application will have direct application
in other industries.
The study of complex cyanides for total destruction is more
independent of specific industry application, since only the
concentration and volume of solution need be known to design
a preliminary system using data included in this report.
The yearly discharge of ferricyanide salts from photographic
sources has been estimated at 5,000,000 pounds. U2)
Ferricyanide in Photographic Processing Wastes
Ferricyanide bleaches are found in color photographic processing
applications (see Appendix F), where it has been used as a stan-
dard bleaching agent for years. The function of the bleach in
the photographic process is to oxidize the metallic silver in
the photographic emulsion to a silver halide. During that oxida-
tion, the ferricyanide and halide ion concentrations of the bath
decrease, while the ferrocyanide concentration increases. Bromide
ion is the most common halide ion. The reaction for photographic
bleaching is:
Ag° * Fe(CN)6"3 + Br"* AgBr* + Fe(CN)6'4
-------
TO maintain the proper concentration of solution constituents,
the solution is constantly replenished with fresh material.
That distinguishes the two primary solutions for all processing
formulations, the replenisher and working tank solutions. The
following illustration shows some typical chemical concentrations
for a working tank and a replenisher tank from three different
photographic processes.
EXAMPLE A
BLEACH BATH COMPOSITION
FROM A TYPICAL COLOR REVERSAL PROCESS^
WORKING TANK REPLENISHER
(g/D
Sodium Ferrocyanide
(Na4Fe(CN)6-10 H2P) 45.0 5.0
Sodium Ferricyanide
(Na3Fe(CN)6) 120.0 140.0
Sodium Bromide
(NaBr) 25.0 Ts.O
EXAMPLE B
BLEACH BATH COMPOSITION
FROM A TYPICAL COLOR NEGATIVE FILM PROCESSOR
WORKING TANK REPLENISHER
fg/1)
Sodium Ferrocyanide Decahydrate 6.0 2.0
Sodium Ferricyanide 23.0 26.0
Sodium Bromide 15.0 17.0
-------
EXAMPLE C
BLEACH B-ATH COMPOSITION
FROM A TYPICAL COLOR POSITIVE PAPER PROCESSOR
WORKING TANK REPLENISHER
Tg/lT Tg/1)
Sodium Ferrocyanide Decahydrate 13.0 ^2.0
Sodium Ferricyanide 17.0 25.0
Sodium Bromide 7.0 8.0
The overflow bleach from the working tank is one source of ferro-
cyanide wastage from the photographic process. In addition, as
film passes through the processing solutions, it carries a cer-
tain volume of tank solution to the next tank. That carryover
is the total of the surface liquid and the solution absorbed
into the film emulsion. The carryover rate depends upon many
factors, including the speed of the process and the photo pro-
ducts being processed. The carryover loss of solution bleach
into the next bath in the process is a second source of bleach
loss. The bath following the bleach is either a photographic
fixing bath or a wash water.
All processing laboratories are in a position to estimate the
average concentration of ferricyanide discharged from the photo-
graphic laboratory over a specified period of time. That can
be done by calculating the pounds of ferro-or ferricyanide
purchased and dividing by the total volume of water used by the
laboratory during the same period. In the photographic lab,.
every pound of ferricyanide purchased i.s at some time lost to
the s.ewer.. If the average concentration is above stream or
municipal sewer regulations (.for either complex or simple cyan-
ides), methods outlined in this report can be used to reduce
the concentration to acceptable levels.
Since all color photographic bleaches containing cyanide are
different only in concentration by factors of 3-5, the state-
ment that Ektachrome bleaches, "cannot be disposed of without
degradative treatment " (8) would apply to all bleaches
A further statement from the same report that, "Under no cir-
cumstances may untreated EA-4 (Ektachrome) bleach be safely
released into any stream." (8) would thus be applicable to
the full range of photographic bleaches containing complex
cyanides.
Additional information on the pollution problems in the photo-
graphic industry can be found in the Appendices of this report.
10
-------
THEORETICAL APPROACH
The methods used in this study for the conversion of ferro to
ferricyanide, or the destruction of ferrocyanide were: electrol-
ysis, ozonation, chlorination, and chemical precipitation.
Electrolysis of Ferrocyanide
In the electrolytic oxidation of ferrocyanide to ferricyanide,
the most probable anode and cathode reactions are as follows:
Anode Reactions:
Fe(CN)6"4 -»• Fe(CN)6" + e~ (primary reaction) e° = -0.49 Volts (2)
>OH~ -»• 1/2 02 + H20 + e' (secondary reaction) e° = -0.40 Volts (3)
Cathode Reactions:
H20 + e" -*• 1/2 H2 + OH" (primary reaction) e? - -0.828 Volts (4)
Fe(CN)6"3 + e~ -»• Fe(CN)6'4 (secondary reaction) e° = 0.49 Volts (5)
The objective of this study was the conversion of ferrocyanide
to ferricyanide. Thus, minimizing the secondary cathode reac-
tion is mandatory. Two methods of obtaining this result were
studied: increasing the cathode current density relative to
the anode current density, and separating the electrode solution
by an ion permeable membrane.
Increasing the cathode current density (relative to the anode
current density) increases the hydrogen overvoltage. The re-
lationship for increased overvoltage (u) with current density
(C.D.) is as follows:
w « a + B log (C.D.)
An increase in hydrogew overvoltage at the cathode for this
reaction results in a buildup of hydrogen gas bubbles (primary
reaction) at the cathode surface. (13) The gas bubbles insul-
ate the cathode from the ferricyanide solution, reducing the
possibility of the secondary cathode reaction. Thus, hydrogen
overvoltage would result in an increase in the overall ferro-
to ferricyanide conversion. Experimentally, varying the ratio
of anode current density to cathode current density would show
this effect.
When a cation permeable membrane is used to separate the ferro.-
cyanide from the cathode, the conversion can be increased.
With membranes of this type, only the positively charged cations
can produce a current through the membrane. The sodium or
11
-------
potassium ions in the anode chamber pass through the membrane
and are reduced at the cathode. Due to its negative charge
ferricyanidc cannot pass through the membrane- and be reduced
to ferrocyanide. The elimination of this reduction process
results in a higher overall conversion of ferro-to ferricyanide.
The only requirements of the cathode solution are: that it be
conductive, and that it not contribute other reactions at the
cathode that would decrease the cell efficiency.
Ozone Conversion of Ferro-to Ferricyanide
The stoichiometric relationship for the oxidation of ferro-
cyanide to ferricyanide with ozone is as follows:
2 Na4 Fe(CN)6 • 10 H20 + 03 + H20 •*• 2 Na3 Fe(CN)6 + 02 + 2 NaOH +
20 H20 (7)
This reaction shows that 20.2 gm of sodium ferrocyanide can be
converted to 11.7 gm of sodium ferricyanide by one gram of
ozone. (14)
With an oxidant as reactive as ozone, the rate determining step
in the above reaction should be the mass transfer of ozone from
the gaseous to the solution phase.
If the rate of reaction between ozone and ferrocyanide is very
rapid, the solution concentration of ozone will be near zero.
Thus, the rate of absorption is proportional to the partial
pressure of ozone. (15)
O'zone Decomposition of Ferrocyanide
The decomposition of the ferrocyanide ion has been found to be a
very complex mechanism, involving a number of competing reactions. (16)
w (172
2 Fe(CN)6"4 + 03 + H20 -»• 2 Fe(CN)6"3 + 2 OH" + 02 (8)
Fe(CN)6-3 Z Fe*3 + 6 CN" (9)
Destruction of free cyanide ion
CN" ••• 03 -*• OCN" + 02 (10)
Destruction of cyanate ion
OCN" + 2H+ + H20 -»• C02 + NH4+ (11)
OCN" + NH4* + * NH2 CONH2 (12)
2 OCN" + H20 + 303 •*• 2 HCO"3 + N2 + 3 Oa (13)
12
-------
Ferrocyanide hydrolysis
, • light _3
Fe(CN)6 * + H?0 -^~> Fe(CN)5 H20 ° + CN (14)
Free cyanide breaks down readily in the presense of ozone to
the cyanate ion, which is generally considered to be only one
one-thousandth (1/1,000) as toxic as cyanide. The cyanate ion
is not stable under oxidation conditions, but its oxidation
reaction is not well understood. Apparently, the breakdown con-
sists of a combination of reactions, including both hydrolysis
and oxidation.
The rt-action of ferricyanide and ozone apparently involves the
removal of a cyano group from the ferricyanide complex. This
complex then further decomposes to cyanate and ferric ions.
In the presence of mineral acids, iron cyanide complex ions de-
compose via the following reaction:
3 H4 Fe(CN)6 -»• 12 HCN + Fe2 Fe(CN)6 (15)
The ferrous ferrocyanide can, in turn, be oxidized to Prussian
Blue Fe4 [Fe(CN)6]T. The extent of this decomposition depends
upon the acidity of the solution; increasing as the pH decreases.
Ferrocyanide reacts differently in the presence of oxidizing
acj.ds. At temperatures between 70° and 80°C, hypochlorous acid
converts ferrocyanide to ferricyanide, nitroprusside and free
ferric ions. When nitric acid is added to an aqueous ferro-
cyanide, the reaction products are reported as ferricyanide,
nitroprusside, hydrogen cyanide, cyanogen, carbon dioxide,
oxamide and nitrous acid. (16)
Removal of Heavy Metal Complex Cyanides
Heavy metal ferrocyanides" are only slightly soluble in water.
Soluble salts of the heavy metal ions are used to form heavy
metal ferrocyanides in the following manner:
MX "+ H20 •*• M"*"*" + X~ + H20 (Metal lonization) (16)
M** + Fe(CN)6"4 -*• M2 Fe(CN)6+ (Heavy Metal Precipitation) (17)
In the presence of an external field, three forces act on a
particle which is moving through a liquid. These forces are: .
(1) the external force (gravitational or centrifugal); (2) the
bouyant force; and (3) the drag force. By the application of
Stokes law for spherical particles, the rate of settling is
directly proportional to the square of the radius of the par-
ticle and the density of the particle, and inversely propor-
13
-------
tional to the viscosity of the fluid. Therefore, the .a4ditio.ii
of a coagulation agent will increase the rate of settling of
the precipitates due -to an increase in particle size,
Chlorine Destruction of Complex Cyanides
Various reactions have been suggested or observed for chlorine
oxidation of complex cyanides. Chlorine may be added as a
pure gas, as a solution, or in solid form.
Caseous chlorine reacts in an alkaline solution to form the
hypOChiorite ion as follows: (18)
C12 •«• OH" •» OCl" •«• Cl + H* (18)
Several possible competing reactions for the destruction of
ferrocyanide by chlorine are cited in the literatureJ they
are as follows:
Fe(CN)6'4 t Fe"1"1" + 6 CN~ (19)
CN~ + OCl" •+ OCN" + Cl" (20)
2 OCN + 3 OCl" + H20 -»• 2 C02 + N2 + 2 Cl" + OH~ (21).
OCN" * 2H* + H20 * C02 + NH4* (22)
OCN" * NH4* -»• NH2 CONH2 (23)
OCN" + OH" + H.,0 •»• CO ~ + NH_ (24)
iL. 3 3
As in oionation, the destruction of the free cyanide ion is a
rapid and well known process,while the destruction of the cyan-
ate is slower and more complex.
The predominant species in solution,when chlorine is bubbled
into water over the pH range of 2-6,is hypochlorous acid (HOC1)".
As mentioned previously,hypochlorous acid converts ferrocyanide
to ferricyanide, nitroprusside and free ferric ions.
Rate dependence on catalyst concentration is characteristic of
homogeneous catalysis. The catalyst usually acts by providing
a mechanism for the decomposition that has considerably*lower"
activation energy than the uncatalyzed reaction. (19)
Lancy reported that mercuric salts split the iron cyanides in
a catalytic process if the decomposition is coupled with an
alkaline chlorination. The proposed decomposition is as
follows:
14
-------
2 Na5Fe(CN)6 + HgCl2 * 2[Na5Fo(CN) 5]
Hg(CN) + 2 NaOCl
2 NaCNO + 3 NaOCl + H20
+1 + 2 Cl" + Hg(CN)2 (25)
2 NaCNO + HgCl, (26)
6
2 C02 + N2 + 3 NaCl + 2 NaOH (27)
In this work, only one mole of cyanide is chlorinated from the
ferricyanide complex. The pH must be alkaline to insure that
the secondary breakdown of the cyanide compounds will be to
cyanate salts. The procedure used by Lancy was to first hypo-
chlorinate the waste to convert the simple cyanides and oxidize
ferro-to ferricyanide. The HgCl2 catalyst is then added and
hypochlorination continued. This method was found to destroy
one gram per liter of ferricyanide in twenty-four hours at 70°F
or in two hours at 180°F. (20) (21)
Due to the pollution hazards in the use of mercury* it was not
studied in this report. Rather, other catalysts that might
produce a similar oxidation were investigated.
15
-------
SECTION IV
MATERIALS AND APPARATUS
MATERIALS
Chemical
Potassium Ferrocyanide
Potassium Ferricyanide
Hydrochloric Acid
Sodium Hydroxide
Ferrous Sulfate
Manganous Sulfate
Cupric Sulfate
Cadmium Sulfate
Zinc Chloride
Nalcolyte, 670
Purifloc A-23
Steel Wool
Grade
crystal
crystal
37.8%
pellets ,
granular
purified
technical
crystal
technical
nonionic flocculant
anionic flocculant
Grade 3
Source
J. T. Baker
J. T. Baker
J. T. Baker
J. T. Baker
J. T. Batker
J. T. Baker
Will Scientific
J. T. Baker
J. T. Baker
Nalco Chemical Co.
Alken Murray Corp.
Unknown
17
-------
APPARATUS
Analytical
Spectrophotometer; Perkin-Elmer Model 139
pH Meter: Corning Model 12 Research
Balance: Mettler H-10 Macroanalytical Balance; capacity:
160± 0.00005 gms
Burettes: 50.0 ml
Pipets: 1 ml, 5 ml, 10 ml, 20 ml.
E1 e c t roj.y s i s of Fer r o cy ani de s
Variac: Powerstat Variable Autotransformer type 116B, the
Superior Electric Co., 0-140 VAC
Rectifier: Varo, type IN 4437
Ammeter: Western Model 80 Analyzer, 0.100 amperes
Voltmeter: Triplett, Model 310 Miniature VOM
Stirrer: Lab-Stir, hollow spindle, Eberbach Corp.
Non-Membrane Cell
Anodes: Stainless Steel Screen Cylinders, Anrod Screen Cylinder
Co., Cass City, Michigan; 1", 1.5", 2.25", 3..2S"
diameter
Cathodes: Stainless Steel Rods, U.S.S., 1/8, 1/4, 1/2 inch
diameter
Membrane Cell
Reactor: (See Figure 1, Page 22 ) consists of two plexiglass
compartments each 2"W x 3 1/2 "L x 4 1/2"H
Electrodes: Carbon plates 3" H x 3" L x 1/4"W (Electro Carb EC-4)
Sealant: Dow Corning, RTV Cement
Membranes: Ionics Inc., Cation No. Gl-AZL-066, Watertown
Massachusetts
Pilot Plant Cell
Reactor: (See Figure 3 page 26 ) Consists of three cylindrical
plexiglass columns with anodes on inside walls and cath-
odes on central axes 36"H x 3"I.D. x 1/4"Wall Thickness
c
18
-------
Anodes: Stainless Steel Perforated Cylinders, 36" x 3"O.D.
Cathodes: Stainless Steel Rod 1/8" diameter, U.S.S.
Power Supply: Holland Rectifier, J. Holland and Sons, 0-10V
D.C. , 25 amperes.
Pump: March Manufacturing Co., Model LC-2A, 115V A.C., 60 cycle.
Glenview, Illinois.
Flow Meter: F. W. Dwyer Mfg. Co. type VFA-34-BV range; 20-200
ml/min, Michigan City, Indiana.
Ozone Regeneration and Destruction of Complex Cyanides
.All studies used the following equipment:
Air Preparation System: Purification Sciences Incorporated,
Geneva, New York, Model AP-1; Dewpoint:
-40°C; Capacity: 1.8 SCFM at 80 PSIG.
Ozone Generator: Purification Sciences Incorporated, Geneva,
New York, Model LOA-2; Flow: 0-20 SCFH;
Output: 0-3 grams per hour with pure oxygen
feed.
Bench Top Regeneration
Reactor: Hydrometer Column; 18 1/2"H x 2 1/2"O.D. x l/8"Wall
Thickness.
Sparger: Labpor Gas Dispersion Tubes; Bel-Art Products, Pequannock,
New Jersey; polyethylene candles, medium porosity.
Pilot Plant Regeneration - (See Figure 4, page 27)
Reactor: Clear Plexiglass Column; 52"H x 3 1/2"I.D. x 1/4"
Wall Thickness
Pump: March Manufacturing Co.; Model LC-2A, 115 volts, 60 cycle.
Flow Meter: F.W. Dwyer Manufacturing Co.; type VFA-34-BV,
range 20-200 ml/min.
Bench Top Destruction.
Hot Plate: Dylatherm, Model 25202, 500 watts
Reactor: Kimax Beaker, 1000 ml.
Sparger: Labpor Gas Dispersion Tube; Bel-Art Products,
Pequannock, New Jersey; Polyethylene candles, medium
porosity.
19
-------
Removal of Heavy Metal Complex Cyanides
s. •—^^™^^^^^^^—™^
Precipitation
Agitator: Phipps and Bird Six Blade Multiple Stirrer, 0*100
rpm, HSv, 60 cycle, with florescent 1 amp base
illuminator
Pump: Eberbach Circulating Pump, Model AA2G108
Heater: Sethco Immersion Heater
Centrifugation (See Figure 9, page 35 )
Flowmeter: F. W. Dwyer Mfg. Co., Model VFA-34-bv, ranfe
20-200 ml/min
Centrifuge: Sorvall Superspeed Centrifuge with Szent-Gyorgi
Blum Continuous Flow Apparatus; Model SS-1, Ivan
Sorvall Corp., Norwalk, Conn.
Chlorine Destruction of Complex Cyanides
Chlorine: Bottled, Jones Chemical Co., Caledonia, New York
Hypochlorite Solution: Clorox Bleach, Std. SI hypochlorite
concentration
Gas Dispersion Tubes: Labpor Polyethylene candles, Bel-Art
Products, Pequannock, New Jersey, medium
porosity
Heater: Will Gyrathern Stirrer-Hot Plate. Magnetic 60-80 rpn.
0-700°F, Model Ha
20
-------
SECTION V
PROCEDURES
Analytical (Subprogram A)
A search of the literature yielded a number of methods for
measuring the concentrations of ferrocyanide and ferricyanide.
The methods included:cerimetric, iodometric and potentiometric
titrations and one colormetric measurement.
The above methods were tested in the lab and various modifications
were made to improve the accuracy of the measurements.
In addition to the methods found in the literature, a number
of spectrophotometric procedures were developed using both the
ultra-violet and visible light regions. The spectrophotometric
test procedures were compared with the titration procedures to
determine which gave the best accuracy in the shortest time. ,
The selected procedures used in this project can be found in
Appendix D, page 123.
21
-------
Electrolysis of Ferrocyanides (Subprogram B)
N o n -Membranc Cell
The potassium ferrocyanide, K4Fe(CN)6-3H.O solutions were pre-
pared by first dissolving 10.5ot.01 grams of the crystal in
distilled water and then bringing the total volume to one liter.
This produced a 5.03 gram/liter solution of iron complex cyanide
as Fe(CN),. Five hundred milliliters of this solution were
added to a one liter beaker in which the electrodes were immersed,
thus forming the cell. The power supply was connected and the
voltage adjusted to 3.5 volts B.C. The ratio of currenfc. density
on the cathode to current density on the anode varied between
0.1 and 20.3 by using different size anodes and cathodes. Sam-
ples were collected via a pipet for analysis at various times
for each current density ratio.
Temperature studies were conducted measuring the increase in
current over a specific temperature range on a number of cells
with current density ratios between 1 and 16. The cells were
placed on a hot plate.and allowed to come to equilbrium at the
temperature under consideration and the current was then measur-
ed. Electrode depth, applied voltage, and concentration were
held constant for each cell. Temperatures were varied from
25°C to 60°C in five degree intervals.
Me mb r an e C e11
A ca^ionic membrane separates two individual cell compartments
in the membrane electrolysis cell: the anode (+) and the cath-
ode (-). Oxidation reactions occur at the anode, the solution
being referred to as the anolyte. The catholyte solution con-
tacts the cathode.
For tests at ambient temperature, the anolyte compartment was
filled with 350 ml of 0.01 M,potassium ferrocyanide,
K4Fe(CN)6-3H20. The cathode compartment was filled with dis-
tilled water, to which acid (HC1) was added to increase conduc-
tivity. The voltage was set at 3.5 volts D.C. and the current
continously monitored.
Further studies were made at varying temperatures by immersing
the cell in a constant temperature water bath. Temperatures
ranged from 25°C to 50°C in five degree intervals. Amperage
measurements were made at various temperature levels.
22
-------
Stirrer
Rectifier
Bridge
Steel Rod
Cathode
Screen
Anode
Ammeter^
Variac
Figure 1 Bench Top Non-Membrane Electrolysis Cell
2.2
-------
Pilot Plant Regeneration Cell
The cell was designed to run as a continuous flow
10.00±.01 gram/liter'potassium ferrocyanide (I^Fe (CNj^' f1
solution was prepared and placed in a holding tank. ^nls
tion was metered into the cell at various flow rates from 150
ml/min to 300 ml/min through a flowmeter. The cell voltage
was adjusted to 3.5 volts D.C. Overflow samples were taken
periodically and analyzed for ferricyanide. The current was
monitored continuously and the cell efficiency compared to the
theoretical efficiency as computed from Faraday's Law.
24
-------
Carbon Electrodes
Cationic Membrane
Plexiglass
Electrolyte
Compartment
Figure 2 Membrane Electrolysis Cell
25
-------
Regenerated
Ferricyanide
?
Drain «=£><3
To
Cathode
Power
* Exhaust
" t •
— To Anode Power
Ferrocyanide
Figure 3 Pilot Plant Non-Membrane Electrolysis Cell
26
-------
-
Figure 4 Pilot Plant Electrolytic Cell
27
-------
Ozone Regeneration and Destruction of Complex Cyanides
(Subprogram C)
Bench Top Regeneration
One liter of a 10±.01 gram/liter potassium ferrocyanide
{K,Fe(CN)6'3H,,0}, was placed in the reaction column and Jfche flow
of the ozone gas stream into the reactor adjusted to ? SCFH.
Samples were taken at various times during the oxidation and
analyzed for pH and ferricyanide. At the point ozone could be
detected (smelled) above the solution surface, the system was
shut down.
Constant pH studies were also performed using the above method
with the addition of pH monitoring and control; concentrated -
hydrochloric acid was added dropwise to the column to maintain
a constant pH. The volume of acid used and the time of reaction
were recorded with each sample. Solutions were analyzed for
ferrocyanide and ferricyanide; and material balances calculated.
Pilot Plant Regeneration
For the pilot plant studies, 50 gallons of 30 gram/liter po-
tassium ferrocyanide {K4Fe(CN)6'SH-Oi solution were prepared
and placed in a holding tank. The solution was pumped into
the reaction column through a flow meter at flow rates from
50-150 ml/min. The ozone gas stream, containing a 21 (by vol-
ume) ozone concentration, was introduced into the vessel at
5 SCFH through a sparger tube at the bottom.
Samples were taken at selected time intervals and analyzed for
ferrocyanide, ferricyanide, and pH.
Bench Top Destruction
A 0.01 M solution of potassium ferrocyanide '{K^Fe(CN)g'3H20}
was prepared and 500 ml placed in a one liter beaker. The pHwas
adjusted with HC1 or NaOH as required.
Three reaction schemes were investigated. First, ozone was
bubbled into the sample without pH adjustment or temperature
control. Samples were taken periodically and analyzed for
ferricyanide. Temperature and pH were recorded throughout the
reaction. Second, ozone was bubbled into a highly acidified
solution, using a steel wool catalyst. The procedure was as
above,with the addition of 5 grams of steel wool and 20 ml of
HC1 to the solution before ozone was introduced. Third, the
solution was acidified with 20 ml HC1 and heated. When the
desired temperature was reached, ozone was introduced into the
solution. The temperatures studied ranged from 70°C to 90*C.
Samples were taken periodically and analyzed for ferricyanide.
28
-------
Flow
Meter
Stdrage
Tank for
Fresh
Solution
Exhaust Gases
to hood
Sump Pump .
Ozone from Generator
Plexiglass
Column
Storage Tank for
Regenerated Solution
Figure & Pilot Plant Ozone Regeneration Cell
-------
Figure 6 Laboratory Ozone Generator and Air Preparation Systei1
30
-------
Figure 7 Pilot Plant Ozonation or Chlorination Cei-
31
-------
Removal of Heavy Metal Complex Cyanides
(Subprogram D)
Precipitation
Ferro-and ferricyanide precipitates were formed from a solution
containing 750 mg/1 of total complex iron cyanide as Fe(CN)6.
Primary testing was conducted at 20°C±1°C, Secondary tests
were made at 16°C, 26°C and 46°C. The initial pH of all solu-
tions was adjusted to 8.0±,1. For the pH studies,,initial values
of 2.0, 6.0, 8.0, and 11.0 were investigated. Either hydro*
chloric acid or 2.5 N sodium hydroxide was used to adjust the
pH.
750 ml of stock complex cyanide solution was placed in .%, one
liter beaker and the pH adjusted as required. The solution
was then placed on the multiple stirrer and stirred at 100 rpm.
Using an upright graduated pipet, the required amount of heavy
metal salt solution was added to form the precipitate. The
mixture was allotted to stir for five minutes* at which point
the stirring paddles were removed.
A definite line of separation existed between the supernatant
and the cloudy layer. At time intervals of 5, 10, 20 and 30
minutes, the height of this line was measured from the bottom
of the reaction vessel and used to calculate settling rates.
Twenty milliliter samples were collected at a point one quarter
inch below the solution surface at each recording of settling
time.
Centrifugation (For exact test procedure see Appendix C)
The centrifugation tests were conducted using two flocculants,
Nalcolyte 670 and Purifloc A-23, over the concentration range
of 0.0 to 10.0 mg/1 by weight. Tests were conducted on each
of five heavy metal ions (Fe+2, Mn*2> Cu+% Zn*2 and Cd*^) under
conditions of:
Constant flow rate through the system and variable cen-
trifuge rotor speed with various flocculant. concentrations.
Constant rotor speed and variable flow rate with various
flocculant concentrations.
One gallon of a 1.50±0.01 gram/liter solution of potassium
ferrocyanide [K4Fe(CN)6"'3H20] was placed in a carboy on a stand
above the level of the centrifuge (Figure 9, page 35), The pH
of the solution was adjusted to 6.4±0.2 and the temperature
20eC*l°C.
32
-------
u,
Figure 8 Precipitation Studies Stirring System
-------
A stirrer was arranged such that the blade was between 2 and
3 inches above the bottom of the carboy, operated at 100 rpm.
A 10% excess of heavy metal salt solution, over the stoichio-
metric requirement, was added to the carboy and the resulting
slurry agitated for an additional five minutes.
The centrifuge was started and brought to 6500 rpm. The gravity
flow of slurry was initiated and the collection tubes filled.
Flow was discontinued and the contents of the tubes allowed to
stabilize for five minutes at 6500 rpm.
The "rotor study" was conducted by increasing rotor speed step-
wise from 6500 rpm to 15,800 rpm and then back to 6500 rpm.
Flow through the centrifuge during this study was constant.
The "flow study" was conducted by increasing the slurry flow
rate through the system stepwise from 6 ml/min to 200 ml/min
and then decreasing again to 6 ml/min. The rotor speed during
this study was constant.
For each of the five metal ions, a flow study and a rotor study
was conducted at each of the various flocculant concentrations.
Samples were taken at each increment of flow rate or rotor
speed,
Absorbance of the samples was measured at 220 my; an absorbance
peak for ferrocyanide. This measures both dissolved and sus-
pended material.
34
-------
Rotor and Distributor Head
in
Stirrer
Slurry Carboy
Centrifuge
and Motor
1 ' '
1 L-J
L
1
1
"L.
Slurry —*
Inlet
lull phi
4^P%>
x* S* \S\ -- *-s ^ '
xx s
->- Clarified
Liquid
Outlet
^
x:^^.^^^
fa' \ \^
/"' ^^^^
/ ^^^"^ V
Collection Tubes
Sample
Collection
u
-Drive Shaft
Inlet
Outlet
Axis o
Rotationi
Collection Tube
-Trajectory
a
Figure 9 Continuous Flow Centrifugation System
-------
Chlorine Destruction "of Complex Cyanides
(Subprogram E)
Two approaches to chlorination (or hypochlorination) were
evaluated: a hypochlorite solution and chlorine gas.
For the first series of experiments, 500 ml of Clorox bleach
were added to 500 ml of 10.0+_0.1 gram/liter "potassium ferri-
Qr.anide [K3Fe(CN)g] solution. The pH was adjusted to 11.0+1.0.
Measurements were made over the temperature range of 20°C to
mOOQC. Samples were taken at various times and analyzed for
ferricyanide.
For the second series, chlorine gas was bubbled into one liter
of a 10.0±0.1 gram/liter solution of potassium ferricyanide
[K3Fe(CN)5], with and without the addition of NaOH to maintain -
the pH at 11.0±1.0. During the reaction, samples were taken
periodically for analysis and the pH was monitored. These tests
were also conducted over the temperature range of 20°C to 100°C.
The analysis of the chlorinated samples required the addition
of sodium sulfite (Na2S03) to "quench" or stop the reaction by
neutralizing the chlorine.
36
-------
Method of Cost Analysis
For ail cost analysis work a single hypothetical processing
machine was used. The chosen machine was a combined average
of various processes. These include: Kodacolor Color Negative
(process C-22), Ektacolor Color Paper (process Ektaprint C)
Ektachrome Reversal Film (process E-4) and Ektachrome Paper
(process Ektaprint-R). The following table shows the flow
rate, concentration of sodium f erricyanide, and approximate
cost o£ the individual bleaches and the "combined average".
Replenisher
Replenisher Na3Fe(CN)6 Bleach
Flow Rate Concentration Cost
Process (ml/min) (g/1) $/100 gal
Kodacolor
(C-22) 275 25 $ 87.00
Ektacolor Paper
(Ektaprint-C 260 25 $ 48.00
Ektachrome Film
(E-4) US 120 $238,00
Ektachrome Paper
(Ektaprint-R) 150 30 $ 72.00
Combined Average 200 SO $111.00
During film processing, about one sixth of the replenisffer
ferricyanide is assumed to be reduced to ferrocyanide. An
average year was taken as 260 days at eight hours per day.
A "combined average" machine was assumed to handle 800 rolls
of film per day.
37
-------
SECTION VI
DISCUSSION OF RESULTS
Analytical (Subprogram A)
lodometric Determination of Ferricyanide
The concentration of sodium ferricyanide can be determined by
reaction of ferricyanide with iodide ions forming free iodine,
then titration of the iodine with standardized sodium thiosul-
fate. The reactions involved are as follows:
2 Fe(CN)6-3 + 2 I' * 2 Fe(CN)6'4 + I2 (28)
I2 + 2 S203"2 ->• 2 I' + S406 "2 (29)
Table I (page 40) shows the analysis of six samples of pyre
sodium ferricyanide of various concentrations compared to the
actual concentrations. The average deviation of the samples
from the actual values is 0.48 g/1.
The test procedure was applied to an actual bleach solution from
ajKodachrome K-12 processor to determine the precision of the
test on a real sample. Seven analytical measurements of the
same sample produced an average deviation of 0.83 g/1 and a
standard deviation of 1.02 g/1. Expressed as a percentage, the
standard deviation is 0;95 percent of the average value for
the concentration of sodium ferricyanide in a real bleach. This
method of determining sodium ferricyanide concentration for qual-
ity control of the photographic bleach is satisfactory. It is
not sufficiently accurate for use in pollution control.
Cerimetric Determination of Sodium Ferrocyanide
The concentration of sodium ferrocyanide can be determined from
it oxidation in acid solution by means of a standardized eerie
sulfate solution with sodium diphenylamine-sulfonate as an indi-
cator; the reaction being:
Ce+4 + Fe(CN)6'4 -" Ce+3 + Fe(CN)6"3 (30)
Table II (page 41) shows the results of five samples using this
method of analysis. The titration end point is difficult to
observe; especially on used photographic bleach solutions. This
data shows an average deviation of ±2.13 g/1. This test method
is also acceptable for use as a rapid quality control measurement,
but is not satisfactory for pollution control use.
39
-------
TABLE I
Sodium Ferricyanide (Na-Fe(CN).g) Concentrations
as Determined by lodometric Titration Methods
Sodium Ferricyanide Concentration
Sample Actual (g/1) Measured (g/1)
A 10.00 10.26
B 10.00 8.48
C 20.00 20.04
D 30.00 30.16
£ 35.00 34.56
F 50.00 49.55
40
-------
TABI,E II
Sodium Ferrocyanide (Na4Fe(CN)6'10 HO) Concentration as
4>
Determined by Corimetric Titratipn Method
SodiumFgyrpcyanideConcentration
Sample Actual (g/1) Measured
A 20.00 19.94
B 30.00 31.11
C 50.00 52.20
D 70.00 66.04
80.00 76.45
41
-------
Determination of Ferrocyanide using Spectrophotometric Measure-
ment at 700 nm.
The concentration of sodium ferrocyanide (N&^Fe^CN^'lQ H20)
can be determined by adding ferric ion to form Fe^ [Fe(CN)6],
Prussian Blue; and measuring the absorbance of the solution at
700 my (Figure 10, page 43).
Figure 11 (page 44 ) and Figure 12 (page 45 ) show the absorb-
ance --concentration curves at 700 my for the ferrocyanide con-
centration ranges 0-1 mg/1 and 0-25 mg/1, respectively. These
curves show that over the above concentration ranges, the re-
lationship is linear.
A least squares analysis was made on both of the above figures.
For the concentration range 0-25 jng/1 ferrocyanide; Fe(CNjg"4
a4 = 0.0036
ax = 0.0522
Standard Error of Absorbance S = ±0.008
y
-4
For the concentration range 0-1 mg/1 ferrocyanide; Fe(CN)6
a0 » 0.0063
ax - 0.0522
Standard Error of Absorbance S « ±0.00102
This method of analysis for ferrocyanide is extremely accurate
and can be used to determine the concentration of ferrocyanide
in the range of 0.2 to 0.4 mg/1 as required for pollution con-
trol measurements.
Determination of Ferricyanide using Spectrophotometric Measure^
ment at 417 my.
The conccutr.-j i iu;-, o i.' sodium ferricyanide can be determined
directly by measurement of its absorbance at 417 my. The
following absorbance -concentration values were obtained for
sodium ferricyanide at 417 my:
42
-------
WAVELENGTH
600
620
640
660
680
700
720
730
740
760
780
800
ABSORBANCE
.049
,067
.06
.087
.094
.095
.095
.095
.093
.088
.083
.077
S .080
I .070
3
^
0 600 620640 660 680 700 720 740 760 780800
Wavelength,
Figure 10 Absorbance Curve for Prussian Blue
43
-------
.1 .2
.3 .4 .5
total
.6 .7 .8 .$ IJO
Concenttation mg/1
11 Absprbance--fbtal Fe(CN)6 Cbncahtratiori frdm
0.0 to 1.0 mg/liter at 700 my
44
-------
1 1 •
1 0-
9.
-
8,
,
7 ,
./
6,
? A
&
c 1
8 -3
-
ft
x
x
X"
y1
X
X
x
x
s
jf
/
/
/
/
-
/
x
02 4 6 8 10 12 14 16 18 20 22 24 26 28
Total Fe(CN). Concentration (mg/1)
o .
Figure 12 Absorbance--Total Fe(CN)6 Concentration From
0.0 to 25.0 mg/1 at 700 mW
45
-------
Concentration of
Sodium Ferricyanide
gm/1 Absorbance
'0.429 1.512
0.279 1.000
0.215 0.768
0.086 0.316
0,043 0.160
0.008 0.026
A least squares analysis on this data results in,the following:
a0 = 0.016
a. = 3.50
Standard Error of Absorbance Sy - ±0.0631
This method is satisfactory for measuring the concentration of
sodium ferricyanide in solutions containing only ferro-and ferri-
cyanide. It is not suitable for photographic bleach solutions
(due to color interference) or other solutions where the concen-
tration is less than 10.00 mg/1 as Na3Fe(CN)6
Determination of Sodium Ferricyanide using Spectrophotometrie
Measurement at 460. 5 myj.
The concentration of sodium ferricyanide can be determined in
a higher concentration range 0-4 gm/1 by direct measurement of
its absorbance at 460.5 my,. The following absorbance-concentra-
tion values were obtained for sodium ferricyanide at 460.5 mK*
Concentration
Sodium Ferricyanide
gm/1 Absorbance
2.66 0.673
1.70 0.435
1.33 0.337
1.33 0.335
0.85 0,222
0.426 0.115
0.345 0.095
0.255 0.070
0.170 0.050
0.085 0.024
46
-------
A least squares analysis results in the following:
ao * 0.0056
ax • 0.251
Standard Error o£ Absorbance S • ±0.01
This method is similar to the measurement at 417 my,but can be
used in a higher concentration range.
Nitroprusside Intermediate (Fe(CN)5NO)~
It was found early in this work that material balances using
spectroscopy resulted in an overall complex cyanide increase
of the treated solution. It was suspected that some interfer-
ence of an intermediate oxidation product between ferrocyanide
and ferricyanide was the cause of an increased absorbance of
the treated samples. The nitroprusside ion was proposed as the
intermediate. (16) Several tests were conducted using ferro-
and ferricyanide with a known quantity of nitroprusside (Table III,
page 48 ). If this intermediate had a greater absorbtivity at
the absorbance readings for ferro-and ferricyanide, it would
explain the material balance problem. The results (Table III)
confirm the interference of this compound by showing that nitro-
prusside will produce the effect of a higher complex cyanide
concentration than is present.
47
-------
TABLE III
ANALYSIS OF FERRO-AND FERRICYANIDE
WITH NITRO PRUSSIDE AS AN INTERFERING IOR
INCREASE IN
SOLUTION COMPOSITION CONCENTRATION (g/1) ABSORBANGE CONCENTRATION
Ferra Ferri
Sail -
g/1
5-/T
g/1
On i AM _____
Nitro Prusside
0.5 g/1
0.5 g/1
0.5 g/1
0.004M
20 g/1
«; a/1
Ferricyanide
(lodometric) I1
1.65
1.72
Ferrocyanide . .
J (Ceric Sulfate}1-*
4.67
.35
at 700 my
"
5.03
6.10
.00916M
0.0
n.n
(%)
6.7
0.0
22.0
10.5
(1) Method used for chemical analysis
-------
Electrolysis of Ferrocyanides
(Subprogram B)
Non-Membrane Cell; Ambient Temperature
All cells prepared for this study were, compared to a theoretical
cell defined to account for the anode reaction only. To limit
the variables involved to current and time, all cells were charged
with solutions of identical ferrocyanide concentration. At any
current there is a time in which a theoretical cell produces a
1001 conversion (ferro-to f erricyanide) . Thus, the cells can be
compared on a dimensionless time scale defined as a percent of
the theoretical conversion time.
9 s_l (31)
tc
Where 8 - Percent of theoretical conversion
t • Actual time of the reaction (minutes)
tc » Theoretical time for 100% conversion (minutes)
The percent of conversion by each cell at Q « 1 was designated
as the -efficiency of the cell.
Figure 13 (page 50 ) shows the relationship between the con-
version of ferrocyanide and the percent of theoretical conversion,
for various cathode to anode current density ratios (CDR) . As
the current density ratio increases, conversion increases. This
confirms the theory that increasing hydrogen overvoltage of the
cathode (hydrogen evolution per unit area of cathode) increases
the overall oxidation efficiency relative to Faraday's Law.
Although CDR's <1 were evaluated experimentally, they were not
included in Figure 13 because decomposition of the complex occurs.
No pilot plant cell was, therefore, designed with a CDR<1.
Figure 14 (page 51 ) compares the current density ratio and
conversion at 0 - 1. At this 0 value, the maximum in current
usage has been reached. For ©< 1, full conversion has not been
attained. For 0> 1, power efficiency is reduced; due to an in-
crease in the secondary cathode reaction relative to the primary
anode reaction. Using the method of least squares, the -follow-
ing expression was derived.'
In X0 - [-0.744CDR1'152]"1 x V2) .,,
0 Concentration of Ferrocyanide
Where Xo - conversion - 1 - at 0 - 1.0 - „ — ,m
I nitial concentration terrocyanide
CDR » Cathode- to-Anode Current Density Ratio
Standard deviation (average error) is 4.32%
49
-------
0 .20 .40 .60 .80 1.00
Percent Theoretical Conversion
Figure 13 Prr/'r,; UIK oimirted Ferrocyanidc--Percent Theoi^tical
Conversion Non-Membrane Electrolysis at Various
Current Density Ratios
50
-------
"t,W
3.75
3.60
3.25
3.00
2.75
2.50
2.25
72.00
©
" 1.75
^c 1.50
7 1-25
,S 1.00
"9 /»
.75
c r\
.50
^ f
.25
n
/
^/
^/
*
/
s
-
/
f
•
/
/
'
/
'
/
'
/
/
j
'
/
/
/
0 .2 .4 .6 .8 1.0 1.2 1.4 1.6 -18 202.4 *& 2& 3.03.2
Figure 14 Effect of Current Density Ratio on Conversion
of Ferrocyanide to Ferricyanide in an Electrolytic Cell
51
-------
For any required conversion, use of the above expression will
show the maximum current density ratio for optimum current
*t + ^ 1 ^ T •» ^ 4 /%«
utilization.
Figure IS (page 53 ) shows the relationship between the current
density ratio and the increase in oxidation rate with tempera-
ture, over the range from 2S°C to 60°C. The least squares method
of analysis produced the following equation:
1,839 • ,0281 (CDR) (33)
Where A R « Percent change in rate
AT = Change in temperature (C°)
Standard Deviation is 3.601
Using this equation, the rate increase can be calculated for a
selected current density ratio and temperature above 25°C.
The iMembrane Cell; Ambient Temperature
The membrane cells were compared using the percent of theoretical
conversion, 0, in the same manner as was done for the non-mem-
brane electrolytic cells. Figure 16 (page 54) shows the re-
lationship between the percent theoretical conversion and the
actual conversion in the membrane cell. It was found that the
membrane cell was able to affect nearly 1001 conversion of ferro-
cyanide to ferricyanide. Deviations of the actual curve from
the theoretical curve were primarily due to variations in the
current with time. As the reaction proceeded, the current de-"
creased slightly due to the decrease in ferrocyanide concentration.
This was compensated for in the analysis by using the average
current to construct the Faraday's Law plot.
The elevated temperature studies were conducted between 25°C
and 50°C. The resulting relationship between current and temp-
erature at a constant applied potential is shown in Figure 17
(page 56). The equation for the slope of this curve was found
to be:
A-T-- -0(H1
Where A I = change in current (amps)
AT3 change in temperature (°C)
No change in the final conversion («100t) resulted at the ele-
vated temperature.
52
-------
o
(A
rt
1)
t«
0
fi
<0
t>
rt
u
•H
00
•rl
4)
U
4)
t*
oa
t>
Q
O
eu
o
•M
rt
Pi
•H
O
IA
rt
O
M
U
C
3.0
2.5
2.0
1.5
1.0
~'~? . .-..w'n-W*'**
tj,«,*"•'
0 U) 2.0 -3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 120 J3.0 W.O 6.0 16.0
Current Density Ratio
Figure 15 Effect of Current Density Ratio on Ferrocyanide
Oxidation Rate for Non-Membrane Electrolytic Cell
53
-------
.2 .3
.4 .5 .6 .7 .8
Theoretical Conversion(6)
.9
1.0
1.1
1.2
Figure 16 Comparison of the Actual and Theoretical Conversions of Ferrocyanide to
Ferricyanide in a Membrane Type Electrolytic Cell
-------
10 20 30
Temperature (°C)
40
50
Figure 17 Current-Temperature Relationship for a Membrane
Type Electrolytic Cell
55
-------
During the electrolysis,it was observed that the anode solution
would turn light green and Prussian Blue precipitate would build
up on the anode side of the membrane. When the cell was operat-
ed without agitation, the Prussian Blue formed on the surface of
the anode. One explanation for these results is that the ferro-
cyanide complex is completely oxidized at the anode to free ferric
ion and cyanide ions. The ferric ion then reacts with unoxidized
ferrocyanide ion to form Prussian Blue that may either deposit on
the electrode or become imbedded in the membrane.
The carbon anodes were found to flake and decompose during the.
reaction.
Pilot Plant Cell1
A continuous flow electrolytic oxidation cell was designed from
the results of the bench top work on the non-membrane cell. A
cell that would produce a 96% conversion of ferrocyanide to ferri-
cyanide was chosen. From equation (32) it was found that a current
density ratio of 20.3 to 1.0 would produce this, conversion with
the least amount of-power loss. - -
Table IV (page 57 ) is a comparison of the average results of the
pilot electrolytic cell studies with reference to the theoretical
conversion (computed from Faradayls Law). The actual versus the
theoretical conversion agrees well at the highest flow rate, but
the relationship decreases with decreasing flow. Decreases in
cell conversion efficiency from the design maximum of 96% are
attributed to:
- irregularities in anode cylindrical shape
- point sources of high current density on anode
External agitation, effected by bubbling air through the columns,
produced no noticeable change in cell conversion. Apparently,
hydrogen evolution at the cathode produced sufficient agitation
for both electrodes.
Cost Analysis for Electrolytic Regeneration of Bleach
For an average processing machine, bleach regeneration will be
carried out on a continuous flow basis with the required ferri-
cyanide addition and pH adjustment after regeneration. Since*
one-sixth of the ferricyanide is converted to ferrocyanide during
the bleaching process, that amount must be regenerated. Electro-
lytically, that requires 44 amperes/hour, per eight hour day on
the "combined average" machine overflow. A production flow
schematic for the electrolytic system is shown in Figure 18(page
59 ). A summary of equipment cost /estimates follows:
56
-------
TABLE IV
CONVERSION EFFICIENCY OF
PILOT PLANT NON-MEMBRANE ELECTROLYTIC CELL
(Initial Solution Concentration: S.03 g/1 Fe(CN)6'4)
(Applied Voltage: 5.5 VDC Temperature: Ambient)
Flow Rate
300
200
150
300
Applied
Current
(amperes)
5.2
5.0
5.0
6.0
Calculated
Experimental Theoretical
Conversion Conversion
(%) (Faraday's Law) (I)
42.9
55.5
56.2
46.2
41.0
65.5
87.4
47.1
57
-------
Equipment Cost
Electrolytic cell with
pumps for recirculation $1,500
SO gallon polyester
tank $ 100
Mixer 2 hp, rubber
coated steel $ 950
pH controller with probe,
solenoid and metering valve $3,000
Labor and maintenance
(estimated at 10% installed cost) $ 555
Total $6,105
Calculated present bleach cost per 8 hr. day: $28.20 _
Cost of Electrolytic Equipment (per day for 10 year amortization):$2.18
Savings for a 901 bleach recovery: $25.40
Daily savings » Daily bleach savings - Daily Cost of Equipment «
$25.40 - $2.18 » $23.22
Savings per roll 6800 rolls/day • 2.9f/roll
-------
HBr
System
Bleach from Processor
Electrolytic
Cell
Stirrer
pH Controller
Mixing and
Replenishing
Tank
To Storage
Tank
Figure 18 .Schematic o£ an Electrolytic Bleach Regeneration
System
59
-------
Ozone Regeneration and Decomposition of Complex Cyanides
(Subprogram C)
Bench Top Regeneration
The results of two bench top regeneration studies are shown in
Figure 19 (page 61). These curves show a linear relationship
between percent of conversion (Ferrocyanide to ferricyanide)
and time ozonation. The upper curve is the result of a least
squares analysis for ozone treatment without pH control. The
slope is described by the following equation:
Tie re x « Co - Ct an
-------
01 234567 8 '9 10 II 12
Figure 19 Conversion--Time Curve for Ozone Regeneration
61
-------
A comparison of the experimental results and the stoichio-
metric equation for the reaction is shown in Table V (page
63). The stoichiometric equation is given by:
2 Na4 Fe(CN)6 • 10 H20 * 03 *• 2 Na3 Fe(CN)6 + 2 NaOH + 02 +
19 H20 (37)
For every unit weight of ozone, 20.2 unit weights of ferro-
cyanide are oxidized to 11.7 unit weights of ferricyanide.
(The unit of weight can be grams, pounds, tons, ounces, etc.).
The oxidation efficiency of ozone (Table V page 63) is approx-
imately 100% for concentrations of ferrocyanide above aBout
one gram per liter. Below that concentration, ozone is re-
leased from the solution and the ferricyanide complex begins
to slowly decompose. Thus, exhausted ozone is an indicator
of the reaction end point.
A series of tests were conducted with used photographic' bleach-
*es from Ektachrome ME-4 and Kodachrome Krl2 processors.
These tests were conducted to determine the efficiency of
the conversion of ferro-to ferricyanide, using ozone on actu-
al bleach solutions. Table VI (page 64) shows that there is
no apparent decrease in the ozone oxidation efficiency for
actual or simulated photographic bleaches.
At present, there are a number of television news processing
laboratories and commercial photofinishers using an ozone bleach
regeneration system. Some of the ferricyanide bleaches have been
regenerated up to forty times with no observed adverse effects
in the bleaching process.
Pilot Plant Regeneration
For analyzing a continuous flow column -reactor, the following
relationship was used: (15)
B (38)
Where G • Molar flow of gas per square foot o£
reactor cross section moles
62
-------
W
TABLE V
COMPARISON OF EXPERIMENTAL RESULTS TO STOICHIOMETRIC CALCULATIONS
FERROCYANIDE OXIDATION WITH OZONE
Volume of Solution: 1 Liter
Concentration of Sodium Ferrocyanide: 11.45 g/1
Ozone Feed Rate 2.36 g/hr
Na3 Fe(CN)6 Cone, (g/1)
Time of Reaction
(min) Measured
0
2
4
6
8
10
11.45
9.72
8.01
6.30
4.63
2.98
Theoretical
11.45
9.86
8.37
6.69
5.10
3.50
•* ^
Measured
0.00
1.67
2.00
3.01
3.97
4.95
Theoretical
0.00
0.93
1.85
2.77
3.69
4.61
-------
Oi
TABLE VI
RESULTS OF BENCH TOP OZONATION OF USED PHOTOGRAPHIC BLEACH
All Solution Volumes are 1/2 Liter
Initial
Final
Process
K-12F
ME-4
ME- 4
ME-4
Time of
Reaction
(rain)
40
30
50
40
Ozone Feed Rate
- (g/hr)
.665
2.36
1.40
2.00
Ferricyanide
Concentration
(2/D
113
101
104.2
97.7
Ferricyanide
Concentration
(2/D
123
128
131.6
126.0
Efficiency
(%)
100%
98%
100%
91%
-------
YO, Y^ • Moles of ozone per mole of air at the
inlet and at any point in the reactor,
respectively,
L • Molar upward flow of liquid per square
foot of reactor cross section Moles
ft2hr
XQ, X-^ » Moles of ferrocyanide per mole of water
at the inlet (XQ) and at any point in
the reactor (X^)
b » Stoichiometric constant for moles of
ferrocyanide converted per mole of
ozone - 2,0
For a very rapid reaction (ozone with ferrocyanide), the molar
concentration of ozone at the outlet of the column is zero at
equilibrium and under proper design. For convenience, the
change in the concentration of ferrocyanide is expressed by
the following convention:
(X0 - xx) - x0 (i-xi) . x0 c
xo
Where C - The percent of conversion of ferrocyanide
to ferricyanide
Upon substitution of equation (38) into equation (39) the
relationship becomes:
G [Yft - Y,J = L XQ C (40)
The liquid flow function L can be expressed as a constant (k)
times the flow rate (v), or
L = kv (41)
Substituting this into equation (40) yields
65
-------
G [Yo - Y 1 = kv Xo C (42)
1 -HO
For the system under investigation, all the terms in equa-
tion (42) except for the liquid flow rate v and C are con-
stants therefore:
G [Y0 - Y ]b
' - VC - k (43)
__
or
» c
v
This shows that the rate of conversion of ferrocyanide to
ferricyanide is inversely proportional to the flow rate of
solution (at a constant ozone feed rate). The ozone out-
put could not be varied with the generator employed in
this study. A graphical interpretation of this relation-
ship and the experimental data are shown in Figure 20.
Experimental results agree well with the theoretical curve.
except at low flow rates. The error at the low flow rates
is probably due to fluctuations in flow. At no point during
the pilot plant work was ozone exhausted from the reaction
columns.
Cost Analysis for Ozone Oxidation of Ferrocyanide to Ferri-
cyanide for Bleach Reuse
For regeneration of the "combined average" processor ferri-
cyanide bleach solution with ozone, a ten gram per hour
ozone generator is required. A flow schematic is shown
in Figure 21 (page 68).
66
-------
20O
20
0
O .1 .2 .3 .4 .5 .6 .7 .8 .9 I.O
Conversion
Figure 20 Effect of Solution Flow Rate on Ferrocyanide During Pilot Plant Ozonation Studid
-------
HBr Tank
pH Controller
Solenoid Valve
Bleach Feed
Air
Compressor
Ozone
Generator
Sparger System
Figure 21 Flow Schematic of a Photographic Bleach
Regeneration System Using Ozone
68
-------
Process overflow bleach flows to the reactor vessel for ozone
regeneration. Since all bleaches in the photographic process
are used at a pH range of 7 to 9, hydrobromic acid is metered
into the vessel to control that pH range. After regeneration,
the bleach is pumped to a holding tank for reuse. The cost of
equipment is listed below:
Equipment
Ozone Generator
Dry Air Supply System
50 Gallon Polyester Tank
Mixer: 2 hp rubber-
coated steel $ 550
Spargers ami Ac. ivi i'unk $ 300
Pumps $ 250
pH controller with automatic
probe, solenoid and metering
valve $3,000
Labor and Maintenance
(estimated at 10% cost) $ 650
Total $7,200
Calculated present bleach cost per 8 hour day: $28.20
Cost of ozone equipment (per day for 10 year amortization): $2.50
Savings for a 901 bleach recovery: $25..40
Daily savings * Daily bleach savings - Daily Cost equipment -
$25.40 - $2.50 = $22.90
Savings per roll @800 rolls per day • 2.85* per roll
Bench Top Destruction
The results of the ozone destruction at ambient temperature are
shown in Table VII (page 70 ). Only minor changes in the total
concentration of complex cyanide resulted during ozonation of
the standard bleach solution at room temperature. During alka-
line ozonation, the solution became dark red after the stoichio-
metric amount of ozone (for total cyanide destruction) had been
added to the solution. This coloration may have been due to
the formation of small amounts of the red Ferrate ion (FeO/ ),
since the color disappeared upon acidification of the sample.
Ferrate ion is stable only in basic solutions.
69
-------
TABLE VII
RESULTS OF OZONE DESTRUCTION OF FERROCYANIDE
AT AMBIENT TEMPERATURE
Initial
Complex
Concentration
Time of
Ozonation
(min)
Final
Complex
Concentration
Average
pH
(g/1 of Fe(CN)6)
1. 6.35±0.01 60
2. 5.03 240
3. 5.03 300
4. 5.03 420
5. 2.12 300
Fe(CN)6)
6.33+0.01
6.00
4.85
4.86
1.77
8.3±0*.l
11.0
4.0
11.0
7.0
70
-------
Some decomposition of the total complex occurs using ozone under an
acidic condition with a steel wool catalyst. The reaction was
very sensitive to changes in pH. For pH>3.0, decomposition of
the complex ceased. For pH<3.0, the complex is oxidized to iron
hydroxide and cyariate. The iron reacts immediately with free
complex cyanide to form either ferrous ferrocyanide or ferric
ferrocyanide. The reaction continues to follow this path until
no free soluble complex cyanide remains.
Hot acidic ozonations were performed in a temperature range of
70°"- 90°C without the use of catalysts. The pH was held below
l.S. Figures 22 (page 72 ) and 23 (page 73 ) show the results
of those studies. Figure 22 shows the effect of ozonation time
on total concentration of complex cyanide; including any re-
dissolved precipitate. Hot acidic treatment of'the complex with
air alone is also shown. Initially, ozone offers no increase
in the destruction of the complex over simply heating and aerating
under acidic conditions. However, as the reaction proceeds,
ozonation promotes a more complete destruction of the complex.
Figure 23 shows the relationship between the concentration of
soluble complex (in solution) and ozonation time at a constant
ozone feed rate. From Figures 22 and 23, it was concluded that
the complex precipitates from solution faster than it decomposes.
The iron ferrocyanide precipitate started with its characteris-
tic blue color but, as the reaction proceeded, it turned to a
black granular precipitate that settled rapidly. The transition
was generally complete when the total concentration of complex
had been reduced to two-thirds of the original concentration.
The precipitate did not exhibit characteristics of common iron
ferrocyanide mixtures. It dissolved only above pH 13.0. Com-
plex cyanides could be extracted from the precipitate with con-
centrated ammonium hydroxide without changing the physical
appearance of the precipitate. Ammonia was qualitatively iden-
tified as one of the decomposition products. The formation of
ammonia is probably due to a "reversion" reaction of ferricyanide
to ferrocyanide:
4 Fe(CN)6~3 + 6 OH" + 3 H20 + 0^ 2 Fe(CN)6"4 + 2 Fe 0'H20 +
2 NH + 2 C02 + 10 CN~ (45)
A flow scheme for a ferrocyanide decomposition unit is shown in
Figure 24 (page 74). The waste ferrocyanide and hydrochloric
acid are injected into the reactor vessel where they are heated
and ozonated. The overflow from the reactor is then filtered to
remove the precipitate that is formed during the decomposition.
The solution leaving the filter is neutralized with sodium
hydroxide and sewered. The precipitate from the filter is col-
lected and treated with sodium hydroxide solution to extract the
complex cyanides. This slurry is then filtered and the filtrate
is recirculated into the reactor. The final products are sodium
chloride and iron hydrozide totaling about six pounds per day for
the "average" processing machine.
71
-------
10 20 30
40 50 60 70 80 90 100 110 120
Time (Min)
Figure 22 Rate of Degradation of Total Fe(CN)6 During Acid
Ozone Oxidation Between 70° - 90°C
72
-------
.010
.009
.008
o
4J
•H
f.007
r-<
I
^.006
2
U
»_/
O
o
»d
•H
I
.004
4)
(t,
o.003
c
o
•H
+J
U
G
O
U
.001
05 10 15 20 25 30 35 40 45
Time (Win)
Figure 23 Effect of Temperature on Fe(CN). During Acid
6
Ozone Oxidation
73
-------
Exhaust Gases
Liquid-Solid
Separation
.1
Heated
Reaction
Vessel
Ozone
Generation
System
'
^ ~ i
Sodium
iydroxide
Feed
Sodium Hydroxide
Sewer
Cyanide Laden Precipitate
Liquid-Solid Separator
>a
Sparger
System
Acid Feed
Cyanide-Free
Solid Waste
Sodium
Ferrocyani(
Solution
Spent Ferrocyanide
ror
Incineration
Figure 24 Ozone Destruction of Ferrocyanide: A Flow Schematic
-------
Cost Analysis for Ozone Decomposition of Complex Cyanides
The cost analysis for- the destruction of fcrrocyanidc using
osone is again based on the "average" processing machine (page 37).
The running time for the machine was set at eight hours per day.
Equipment size was based on a twenty-four hour destruction cycle.
The equipment cost estimate for this unit is listed below: (25)
Equipment Cost/Unit
Reactor vessel; glass-lined
steel, 50 gal ' $ 2,000
Mixing tanks; polyester
SO gal $ 200
Portable mixers; 2 hp rubber
coated steel $ 550
Heating coil; DuPont Teflon
immersion coil $ 1,000
Pumps; corrosion resistant $ 250
Filter presses; plate and frame $ 1,200
Ozone generation unit (200 gm/hr) $14,000
Labor and maintenance
(estimated at 19% cost) $ 2,480
Total $25,680
Daily Chemical Costs Quantity Cost
1) Oxygen 200 cubic ft $6.60
2) Hydrochloric acid 1 liter $ .75
3) Sodium hydroxide 1 pound $ .30
Daily Cost of Destruction: $17-.S'0 (equipment amortized over
10 years). ... _./ , -
Increase in .cost of processing per roll of film: Z*/roii.
75
-------
Removal of Heavy Complex Cyanides
(Subprogram D)
Precipitation
Copper and zinc were the best metals tested With regard to
completeness o£ heavy metal ferrbcyanide precipitation. How-
ever, the difference between the various metals tested was small.
Table Vin (page 77) shoWs that the best ferrocyanide removal
resulted using zinc ion, (99.8S) while the least effective was
iron (99.41). Copper and zinc precipitates were the slowest to
settle. After thirty minutes, the zinc precipitate had settled
to only 40% of the original solution height. (See Table IX
page 77 ).
Results of varying pH showed a somewhat lower ferrocyanide con-
centration when starting with alkaline solutions. Excess metal
ion, beyond the stoichiometric amount for complete precipitation,
lowered the ferrocyanide concentration in the supernatant only
With copper and zinc. 10% excess metal reduced the complex con-
centration to 251 of that remaining when the stoichiometric amount
of metal was Used. Additional excess did not lower the concen-
tration further. (See Table X, page 78).
Several tests were run with ferricyanide and combinations of
ferro-and ferricyanide. These experiments indicated that ferri-
cyanide Will not precipitate well by itself. A 90 percent re-
duction df pure ferricyanide was obtained using Fe*2 as the pre-
cipitant, while the other metals only removed about 601 of the
Fe(CN)6'3. HoweVer, with both ferro-and ferricyanide in the
solution, reductions of 99.51 or better in both complex cyanides
1 were obtained with Fe*% Cd*2 and Cu+2. (See Tables XI-XIII).
The analytical procedure for ferro-and ferricyanide in this section
called for filtering each sample through Whatman 2V filter paper
as the first step. When distilled water was run through this
paper and its absorbance measured against the same water which
had not been filtered, the values at 220 mu ranged from 0.08 to
0.35, This would correspbnd to a ferrocyanide concentration of
from 0.9 to 4.0 mg/liter. The Water Was apparently leaching a
material from the paper which contributed to the absorbasice at
220 mu, If the water was made acid, it had a higher absorbance
after filtration than a neutral sample. Several different brands
and types of filter paper W6re tried; all with about the same
results. Ther6 did ndt seem to be a useful correction factor
because of the wide daily variations. As a result, the observed
ferrocyanide Concentrations may be higher than the actual concen-
tration.
76
-------
TABLE VIII
EFFECT OF INITIAL pH ON FHRROCYANIDE
(Fe(CN)6~4) CONCENTRATION
(mg/1 after 30 min settling)
Initial
pH
2.0
6.0
8.0
11.0
Fe
4.5
3.5
3.0
2,3
Mn
3.7
3.7
3.2
2.8
Cd
3.0
3.1
3.1
2.4
Cu
2.4
2.5
1.3
1.3
Zn
3.3
*
1.5
1.8
1.9
(Initial Cone. 750 mg/1 Total Complex Cyanide in Each Solution)
TABLE IX
EFFECT OF INITIAL pH ON HEAVY METAL
FERROCYANIDE PRECIPITATION RATE
(% of initial solution height after 30 min settling)
Initial
pH F_£ Mn
2.0 22 8
6.0 29 £
8.0 16 10
11.0 19 12
Cd
11
8
10
15
Cu
34
34
30
28
Zn
38
46
40
35
77
-------
• TABLE X
EFFECT OF EXCESS HEAVY METAL ON
FERROCYANIDE (Fe(CN)6"4) SOLUTION CONCENTRATION
(mg/1 after 30 min settling)
Metal
Ion
Fe
Mn
Cd
Cu
Zn
*90
6.7
4.2
2.4
2.4
0.7
*100
2.9
2.6
2.9
4.5
2.3
*110
2.8
3.0
2.5
1.3
0.6
*125
3.1
3.0
3.1
1.3
0.7
*200
4.1
3.5
2.7
1.4
0.6
* PERCENT STOICHIOMETRIC SALT SOLUTION
(Initial Cone. 750 mg/1 Total Complex Cyanide in Each Solution)
TABLE XI
EFFECT OF TEMPERATURE ON HEAVY METAL
FERROCYANIDE (Fe(CN)6"4) CONCENTRATION
(mg/1 after 30 min settling)
Metal
Ion. 26°C 46°C 56°C
Fe 6.0 4.0 4.4
Mn 3.6 3.0 1.8
Cd 2.3 4.0 1.3
Cu 4*1 5.0 4.1
Zn 0.9 3.0 2.5
(Initial Cone. 750 mg/1 Total Complex Cyanide in Each Solution)
78
-------
TABLE XII A
HEAVY METAL PRECIPITATION OF COMPLEX CYANIDES FROM
SOLUTIONS CONTAIN.INC BOTH FERRO-AND FERRICYANIDE SALTS
(Initial Cone. 750 mg/1 Total Complex Cyanide in Each Solution)
•<
(mg/1 ferrocyanide after 30 min settling)
Metal
Ion
Fe
Mn
Cd
Cu
Zn
*100
2.9
2.6
2.9
4^5
2.3
*95
3.0
2.7
2.2
5.2
4.2
*90
2.3
4.2
2.4
4.0
5.9
*75
2.0
7.0
2.0
3.6
4.8
*50
2,6
12.8
2.2
10.2
10.2
*25
3.3
31.5
2.0
13.4
4.1
*0
0
0
•» o
0
0
*PERCENT FERROCYANIDE IN SOLUTION
TABLE XII B
HEAVY METAL PRECIPITATION OF COMPLEX CYANIDES FROM
SOLUTIONS CONTAINING BOTH FERRO-AND FERRICYANIDE SALTS
(Initial Cone. 750 mg/1 Total Complex Cyanide in Each Solution)
(mg/1 ferricyanide after 30 min settling)
Metal
Ion
Fe
Mn
Cd
Cu
Zn
*100
74
300
327
307
256
*75
1.2
190
2.8
5.7
47
*50
0.5
184
5.0
7.0
55
*25,
1.0
53
3.2
0.8
45
*10
1.1
16
5.2
4.0
46
HJL
1.6
10.2
2.5
3.8
24
*0
••MUM
0
0
0
0
0
*PERCENT FERRICYANIDE IN SOLUTION
-------
TABLE XIII A
EFFECT'OF SETTLING TIME ON
FERROCYANIDE CONCENTRATION
(mg/1 Fe(CN)6-4)
Metal
Ion
Fe
Mn
Cd
Cu
Zn
5 Min
3.5
6.8
2.2
4.1'
4.3
10 Min
3.1
6.2
2.2
4.2
4.1
20 Min
2.9
6.1
1.9
3.8
3.9
30 Min
3.1
5.9
2.0
3.9
4.1
(Initial Gone. 750 mg/1 Total Complex Cyanide in Each Solution)
TABLE XIII B
EFFECT OF SETTLING TIME ON
FERRICYANIDE CONCENTRATION
(mg/1 Fe(CN)6~3)
Metal
Ion
Fe
Mn
Cd
Cu
Zn
5 Min
74
257
410
360
252
10 Min
64
272
397
302
246
20 Min
64
251
330
320
267
36 Min
68
251
435
315
267
(Initial Cone. 750 mg/1 Total Complex Cyanide in Each Solution)
80
-------
Centrifugation
For the purpose of comparison in the centrifugation studies,
clarity of centrifuge effluent was defined as the inverse of
absorbance. As an example, if a sample had an absorbance of
0.50, its clarity was 2.0 (1/0.5). Any solution with a clarity
greater than 3.0 (absorbance less than 0.33) appeared clear to
the unaided eye.
It was expected that increased rotor speed would produce greater
effluent clarity,but that was only partially confirmed. As rotor
speed was increased, the clarity "peaked" (ie., increased then
decreased). The Sorvall centrifuge used in the study produced
very large "g" forces; up to 30,000 times the force of gravity.
This centripetal force may have been enough to break up the rather
loosely bonded aggregate particles,held together by the floccu-
lant.
It was also anticiptatedthat decreasing the slurry flow rate
through the centrifuge (increasing the residence time) would
increase clarity. Again, this was found to be only partly true
with this system design. At low rates, air was probably taken
into the collection tubes and expelled with the effluent. While
inside the tubes, the air bubbles disturbed the settling parti-
cles and offset the benefits of the longer residence time. Clar-
ity, then first increased as the flow rate decreased for this
particular system.
Addition of Nalcolyte 670 or Purifloc A-23 produced visibly
larger precipitate particles. This addition changed the points
where clarity was a maximum under the conditions of variable ^
flow rate or rotor speed. That is, the addition of increasing
amounts of flocculant produced clarity "peak" points at pro-
gressively lower rpm's in the rotor study and at progressively
higher flow rates in the flow study. The flocculant also in-
creased the amount of material removed from solution at these
"peak" points. For example, Figure 25 (page 83) shows a rotor
speed study using Fe*2 ion. Without flocculant, the clarity
peak is 5.0 at 8200 rpm for the rotor study and 50 ml/min for
the flow study.
Purifloc A-23 produced generally greater clarity than Nalcolyte
670 at the same concentration. At concentrations of S.jjpm,
Nalcolyte produced large gelatinous particles which caused
clogging of the inlet ports. The sediment build-up in the col-
lection tubes was quite rapid and required frequent cleaning of
the system.
All of the metal ions studied produced slurries that would cen-
trifuge well enough, under optimum conditions, to give effluents
clear to the unaided eye without the use of flgcculants^ Under
optimized rotor speed and flow rate, Zn+z, Cd * and Mn < slurne
with either flocculant; produced effluents which showed absorb-
ances corresponding to less than 1 mg/liter complex cyanide.
81
-------
Figures 25 -34 show the results of the rotor speed and slurry
flow studies on the centrifuge for each metal and flocculant
investigated.
82
-------
in
\\j
2
o
v/
10
^ fi
7 b
6 A
*r
° ?
N d
/•N
*» O
. 4C4
H lA
• io
« Q
O O
O
c c
rt o
# A
* 4
o .;
W X
5
^. O
*— ' v/
g 10
Tt ft
5 ft
o o
w >T
4
*" «
ft O
0 * r\
*» O
•H
U |X\
rt IO
H «
0 8
4
2
c
o
IT
vo
no f
•MM
1 DD
>"
•^
5 ppir
1^,
••^•M^MMB^MB
5 pp
"^'"V
•••••^••IM^
: 8
CVJ
' 00
:occu
r
#67
\
^
#67C
^=
A- 23
r-
^n
A- 2
~^ — 1
^
0
, 8
Cl
Lint.
^
r~
=
_J
\
M
i
5
—
C
C
, *
r
k—
••••MNM^B^
i^n~m^
^^^^^^^•^^PH
*- —
^•^^^••••^•^
••MmV
> §
r S
*^.l .-
••••••••••MBi
' ' *•
!=
—
1
!O
O
r 5
-^
—
•• "
^^•WIBBB^M^
********
^—***^*m*i*m—
— ^—
C
c
- 00
m
^
'" •
=
1
/
^
XJ
\ 8
'- *
-=
U^
==:
—
/
^--
— f
'O
O
' ^
—
:=^=
U"
I
Jl
J
•^^ 1
-4
^
8
. ^
^j
r
l^
r
1
^4
[
A
s
-,-
o
o
.
-------
10
I8
06
o 10
S 8
•S 6
o
(A
o
c/j
0
10
8
o 4
2
0
>s
4J
•H
rt
IH
U
4
2
No I-'loccullant
5 ppift #67(
O
O
o
o
U> 00
\
10
3! S ppfr A-
o
o
o
"
o
o
o
o
O
O
o
o
o
o
O
o
o
o
o
o
oj-
Of
O
o
Rotor Speed (rpm)
Figure 26 Effect of Rotor Speed on Solution Clarity for
Manganese Precipitation of Complex Cyanide Using Various Flocculants
84
-------
10
8
6
4
p.
c
0
JO
:!8
S6
N4
«2
?o
810
«8
16
I4
"2
Jo
SIO
•"* o
s8
W6
^ yj
o 4
X 9
*J C
'So
olO
8
2
no f
•~"~^>*
1 DP
•M^B^HMMM
\ 5
\
•••^•IH^BBNi
MHH^^HH^^BH
1 PPJ
•*s^_
5
\
V
^•^^••••••Hi
loccu
^-.
* #67
•^•••••••••••1
ppm
^
•liMMBMM^^
A-2.
^^^1-
ppm y
"*• N>.
••^Hi^MHHBI
I. ant
j
(
)
N<^*.
•••••••••••HH
670
•i. *^
^•••••^••HM
•N^
V
-23
X
i
. .... ..
\
—- — »
•••••••l^BBB
. •• •»
•MHVBWBB^^
••••••i^HMMa
^i^^MHBMiHHil
•*~m*~
•— ^-«— _
•««i.i— •
••^••••^•••M
V
•^MBBMI
=a~
••
•r^i,—
••••••••IBiM
^
•^HMB^M*^
^ • "
i^.
•••^^^••^^^•1
1^="
>
/
/
1
^•^^••'•••"•l
^— —
^^L
*«
-
H
F
.Ill
rz
L
J
^
l^K
A
z^h
'4+-
/T
/
s
H
H
.._ . !
1
L^*^ 1 I -
H
voooooooooogoo
§ I I 1 f- 1- I 1 1 1 S 8 1
Rotor Speed (rpm)
Figure 27 Effect of Rotor Speed on Solution Clarity For Cadmium
Precipitation of Complex Cyanide Using Various Flocculants
85
-------
Rotor Speed (rpra)
Figure 28 Effect of Rotor Speed on Solution Clarity for Copper
Precipitation of Complex Cyanide Using Various Flocculants
86
-------
Rotor Speed (rpm)
Figure 29 Effect of Rotor Speed on Solution Clarity for Zinc.
Precipitation of Complex Cyanide Using Various Flocculants
87
-------
Figure 30 Effect of Flow Rate on Solution Clarity for Iron
Precipitation of Complex Cyanide Using Various Flocculants
88
-------
rvj tf>
— f\i
888
Flow Rate (ml/min)
O
m
o
in
m
Figure 31 I-fleet of Flow Rate on Solution Clarity for Manganese
Precipitation of Complex Cyanides Using Various Flocculants
89
-------
10
8
oo m
— eg
O
in
0000
O O O in
— cvj —
Flow Rate (ml/min)
Figure 32 Effect of Flow Rate on Solution Clarity for Cadmium
Precipitation of Complex Cyanides Using Various Flocculants
90
-------
e
0)
u
rt
fi
O
•H
O
CO
rt
IH
U
Flow Rate (ml/min)
Figure 33 Effect of Flow Rate on Solution Clarity for Copper
Precipitation of Complex Cyanides Using Various Flocculants
91
-------
m
OJ
O
O
— c\j
Flow Rate (ml/min)
O
in
in
eg
Figure 34 Effect of Flow Rate on Solution Clarity for Zinc
Precipitation of Complex Cyanides Using Various Flocculants
92
-------
\
Chlorine Destruction of Complex Cyanides
-•
(Subprogram E)
/
Some difficulty was encountered in chlorination studies longer
than 20 to 25 hours in duration due to solution saturation of
various salts. These included sodium chloride, potassium chloride
and sodium hypochlorite. The salts had to be removed by .fil-
tration. In addition, a satisfactory unsophisticated method
of pH control for long term studies was not found.
In general, complex cyanide destruction by alkaline chlorination
at room temperature was found to be very slow (Figure 35, page 94).
On the basis of a one week test, it would require three weeks
for 500 mis of Chlorox to destroy the ferricyanide in 500 ml of
a 20 g/liter potassium ferricyanide {K3Fe(CN)fi} solution at 20°C.
At 605C the same amount could be decomposed in less than three
days, while at 90°C the decomposition would only take about four
hours (Figure 36, page 95).
None of the catalysts (AgNO,, NaN03, CdS04, steel wool) appeared
tp increase the rate of destruction of the complex cyanide at
ambient temperature. The metal ions (Ag+, Cd , Cu ) precipitated
as heavy metal salts of the iron cyanide complexes. The steel
wool showed no effect in neutral or basic solutions, however,
in strong acid solutions it dissolved and precipitated as ferrous
ferricyanide. No free cyanide, hydrogen cyanide or cyanate
were found in the chlorinated solution or in the decomposition .
products. The only products definitely identified were ammonia
and ferric (Fe+3) ion.
Alkaline and acid chlorination of ferricyanide apparently pro-
ceed by different mechanisms. When chlorine was bubbled into
an alkaline solution, the solution darkened slightly and iron
hydroxide, Fe(OH)3, precipitated. Qualitative tests showed
the presence of cyanate and the reaction proceeded to completion.
In acid media, the solution turned red, then darkened to green-
black. As the reaction proceeded, a granular, green-black pre-
cipitate formed and cyanate was not observed. The maximum
attainable decomposition with acid chlorination was 851; the
other 151 of the ferricyanide complex remaining in the precip-
itate. However, if the solution was basified and the resulting
precipitate removed, chlorination of the filtrate would be re-
peated and an additional 85% of the complex removed. This pro-
cess of recycling the precipitate with acid chlorination to the
desired ferricyanide level appears to be the most successful
destruction procedure using chlorine.
93
-------
vo
cid hypochlorite'solution
chlorite solution
02 4 6 8 10 12 14
Time (days)
Figure 35 Rate bf Loss of Ferricyanide During Ambient Temperature Chlorine Oxidation
-------
Chlorination Destruction of Complex Cyanides at Elevated Temperature
-------
Chlorination Destruction Cost Analysis
Destruction of Cerricyanide can be achieved under acidic or
alkaline conditions. Either method would require approximately
the same equipment and each produce ferric hydroxide as an end
product at the rate of about four pounds per day for the "com-
bined average" processor. Ferric hydroxide is not a readily
saleable product.
Acid Chlorination (Figure 37, Page 99)
For acid Chlorination destruction of complex cyanides, the bleach
overflow is first collected and heated to about 90°C. Chlorine
gas is pumped into the solution and allowed to produce an acid
media. When the maximum decomposition has been reached (85%),
NaOH is added to precipitate the iron. The resulting slurry is
pumped through a filter press and the filtrate returned for
further Chlorination.
The "Combined Average" processor requires 5.15 kg of sodium
ferricyanide to process 800 rolls of photographic materials.
Acid Chlorination
Equipment Cost/Unit
Reactor Vessel; glass-lined
steel, 50 gal $2^000
Portable Mixers, 2 hp rubber
coated steel $ 550
Heating Coil: DuPont teflon
immersion coil $1,000
Pumps; Corrosion resistant $ 250
Filter Presses; plate and frame $1,200
Labor and maintenance
(estimated at 20% cost) $1,000
• w
$6,000
96
-------
Daily Chemical Costs
Quantity Cost
Chlorine Gas 176 ft3 $8.00
Sodium Hydroxide 20 Ibs. $5.50
Hydrochloric Acid 1 liter $0.50
Daily Cost of Destruction: $16.25 [equipment amortized over
10 years]
Increase in Cost of Processing per roll of film: 2^/roll
Alkaline Chlorination (Figure 37, page 99 )
Ferricyanide waste bleach overflow would be collected and heated
to 9'0°C. During continuous applied chlorination, NaOH is added
to maintain alkaline conditions. When the reaction is complete,
the solution is pumped through a filter press and the ferric
hydroxide removed and dumped. The filtrate is neutralized with
HC1 and sewered.
Alkaline Chlorination
Equipment Cost/Unit
••.
Reactor Vessel: glass-lined
steel, 50 gal $2,000
Portable Mixers, 2 hp rubber
coated steel » 55°
Heating Coil: DuPont teflon
immersion coil $1,000
Pumps; Corrosion resistant $ 25°
Filter Presses; plate and frame $1,200
Labor and Maintenance . nnn
(estimated at 20% cost) »i,uuu
$6,000
97
-------
Daily Chemical Costs
Quantity Cost
Chlorine Gas 710 ft3 $30.00
Sodium Hydroxide 80 Ibs $25.00
Hydrochloric Acid 4 liters $ 2.00
Daily Cost of Destruction: $59.25 [equipment amortized over
10 years]
Increase in Cost of Processing per roll of film: 7.5{/roll
98
-------
Acid Chlorination;
Bleach Overflow
NaOH
V
Cl.
Heating
Coil
Filter Press
.To Sewer
Alkaline Chlorination:
Bleach Overflow
Clf
NaOH
V
Heating Coil
HC1
Filter Press.
Figure 37 Chlorination System : Flow Schematics
99
-------
Y
9
u__
jL^-^L A 4^ b $ b
8
WMMH
1
1 J
J
7
6
I
Spent
Bleach
— Solutions
r ^
*->w ^
5
4
I
3
••Hli^
I
2
1
P
(
„••'.
1 i 1 i
L I i i i
Processor
Overflow
Wastes
(Cone. Only)
Mix Room
Waste
From T-4
Figure
VII a
0-2
Regenerated Bleach
^ To SanitarJ
Sewer
Recycle to
Mix Room
Key: 1-Black § White Paper Processor
2j4,5-Ektacolor Paper Processor
3-Ektachrome Paper Processor
6-Black § White Film Processor
7-Ektachrome Film Processor
8,9-Kodacolor Film Processor
T-5 thru T-9 - 250 Gallon Holding Tank
T-10, T-ll - 55 Gallon Holding Tank
0-1, 0-2 - OzPAC Ozone Generators
Figure 37 A Flow Diagram of Bleach Regeneration System and Concentrated Waste
Oxidation System
-------
SECTION VII
FULL SCALE OZONE BLEACH REGENERATION
AND WASTE DESTRUCTION INSTALLATION--BERKEY PHOTO
Ozone Generation and Distribution System
The flow diagram of the bleach regeneration system and the con-
centrated waste oxidation system is shown in Figure 37A (page 100).
The main units of the installation are shown in Figure 38 (page 102).
The two units were manufactured under the tradename OzPAC by
Computerized Pollution Abatement Corp., Leicester, N.Y. The unit
on the right is a 100 gm/hr ozone unit, used for the treatment of
waste photographic solutions to reduce the chlorine demand. The
unit on the left is a 60 gm/hr ozone unit, used for bleach regen-
eration and waste treatment*
100 gm/hour Unit
This unit distributes ozone to three different waste treatment
tanks by means of three flow regulators. These regulators are
mounted on the front panel (upper left) of the unit. The upper
right hand front panel contains a pH transmitter and recorder.
These units constantly monitor the pH of the waste effluent prior
to sewering.
60 gm/hour Unit
This unit serves a dual function. Its primary use is for bleach
regeneration, with secondary use for waste treatment. When used
for bleach regeneration, the ozone is piped to the tanks immedi-
ately behind the unit. The pH of the bleach is controlled by
the pH transmitter (mounted on the upper right front panel) and
is automatically maintained at the desired level by the addition
of HBr.
Bleach Regeneration Tanks
Figure 39 (page 103) shows the two tanks used in bleach regen-
eration. The spent bleach flows, by gravity, into the tank at
the left, from the .photographic processors on the floor above.
For regeneration, the desired amount of spent bleach is then
pumped to the tank on the right. After testing for the,, concen-
trations of ferro-and ferricyanide present, the proper amount
of ozone is fed into the bleach. The regenerated bleach is then
pumped upstairs to a mixing room, where a small amount of solid
ferricyanide is added. The bleach is finally pumped to the re-
plenishment tank for reuse.
101
-------
Figure 38 Ozone Generation And Distribution Systems
Installed at Berkey Film Processing Plant,
Fitchburg, Massachusetts
102
-------
Figure 39 Ferricyanide Bleach Regeneration Tanks
at Berkey Film Processing Plant, Fitchburg,
Massachusetts
103
-------
Photographic Waste Treatment Tanks
This system consists of three tanks on different elevations.
After introduction into the highest tank, the waste solutions
to be treated cascade to the lowest tank, from which they are
sewered.
The waste solutions for this system are introduced from three
different points. First, there is a continuous overflow from
the various photographic processors. Second, there is an inter-
mitant flow of desilvered waste fix solution from a series of
electrolytic silver recovery cells. The last source is a small
constant flow from a series of four waste holding tanks, Vhich '
provide storage for large dumps, preventing slugs of material
from passing through the waste treatment tanks too rapidly.
The main source of ozone for this system is the 100 gm/hour unit.
Examples of the ozone distribution are: 50 gm/hr in the first
tank, 30 gm/hr in the second tank, and 20 gm/hr in the last tank.
When the 60 gm/hr unit is not being used to regenerate bleach, a
different ozone distribution can be employed. In this system,
the 60 gm/hr is fed into the first tank and the 100 gm/hr is
distributed into the last two tanks, at an approximate ration of
SO/SO. (Figure '40,, page 105)
Photographic Solution Testing Station
Figure 41, (page 1.06) shows the complete testing station re-
quired for a typical photoprocessing plant. Test solutions are
kept on a shelf, above a glass drying rack. Work areas are
located on either side of a sink. Extra chemicals and glassware,
necessary for testing, are stored in the cabinets under the sink.
Testing which can be conducted at-this type of station are:
concentration of ferro- and ferricyanide, pH of bleach, chlorine
demand of waste solution, and silver concentration in fixer
solution.
104
-------
Figure 40 Waste Treatment Tanks at Berkey Film
Processing Plant, Fitchburg, Massachusetts
105
-------
Figure 41 Photographic Solution Testing Station at Berkey
Film Processing Plant, Fitchburg, Massachusetts
106
-------
SUCTION VIII
ACKNOWLEDGMENTS
The support and cooperation of Mr. Joel Weinstein, Berkey Film
Processing Plant, Fitchburg, Massachusetts, who made this study
possible, is acknowledged with sincere thanks.
The bench scale and pilot plant studies, analytical work, and
report preparation were performed at Computerized Pollution
Abatement Corporation, Leicester, New York.
We also acknowledge the support of the project by the U.S.
Environmental Protection Agency and the help and guidance of:
Mr. William Lacy, Mr. G-eorge Rey, Mr. Arthur H. Mallon, and
Mr. Thomas Devine, the Project Officer.
The additional support of Mr. Thomas McMahon, Director, Division
of Water Pollution Control, the Commonwealth of Massachusetts
is also acknowledged.
J07
-------
SECTION IX
REFERENCES
1. Sax, N. Irving, Dangerous Proper'ties of Industrial
Rheinhold Publishing Co.. New York, 1963"; •• .
2. Burdick, E.'fi. , and Lipschvetz, M., "Toxicity of Ferro-and
Ferricyanide Solutions to Fish, and Determination of the
Cause of Mortality", Trans. Ami Fish Soc. , 78, 192 C1948)
CA 44, 10939P. J
3. Ono, Sinichi and Tsuchihashi, Genichi, "Oxidation of Ferro-
cyanide in Aqueous Solution by Light", Bull. Chem. Soc.,
Jap. 38(6), p. 1052-3, 1965, (Eng.) CA 63, 6530";
4. Emschwiller, Guy and Legros, Jacqueline, "Photochemical
Hydrolysis of Ferrocyanide", Compr. Rend. 261(6), (Group?),
p. 1535-8 (1965) (Fr.) CA 63 17632e.
5. Dainton, F.S. and Airey, P.L», "Primary Processes of
Photoxidation of Aqueous Fe+2 Species", Nature, 207 (5002)
p. 1190-1, (1965), CA 63, 15761a.
6. Kongiel-Chablo, Irena, "Behavior of Complex Cyanides in
Natural Water with High Rate of Contamination", Roczniki
Panstwaowego Zakladu Hig., 17(1), p. 95-102, 1966.
7.' Lur'e, Yu.Yu. and Panova, V.A., "Behavior of Cyano Compounds
in Water Ponds", Hydrochemical Materials, Vol. 37, p. 133-43,
Moscow, Russia, 1964'.
8. "Toxic Effects of Color Photographic processing Waste on
Biological Systems", Report EHL (K) 70-9, USAF Environmental
Health Lab, Kelly Air Force Base, Aug. 1970.
9. West, Lloyd E., "Disposal of Waste Effluent from Motion-
Picture Film Processing" J. SMPTE, 7£, p. 765-771 (1970).
10. Hendrickson, Thomas N./'Pollution and the Television Film
Processing Laboratory". Paper to be presented at the National
Meeting of the National Association of Broadcasters, Chicago,
Illinois, April (1972).
11. Condensed Chemical Dictionary, 5th Edition, 1956.
12. Alletag, Gerald C., "Truth in Pollution Abatement" ^per
presented at Pure Meeting, Washington, D.C., April 6, 1971..
13. Glasstone, S. , Textbook of Physical Chemistry^ D. Van Nostrand
Co., New York,
09
-------
14. Bober, T., and Dagon, T., "Regeneration of Ferrocyanide
Bleach Using Ozone", paper'presented at Society of Photo-
graphic Scientists and Engineers Convention, Chicago, Illinois
April 22, 1971.
IS. Levenspiel, 0., Chemi ca1 Re act ion Engineering, John Wiley §
Sons Inc., New York, IS64.
16. American Cyanamid, The 'Chemistry of Ferrocyanides, Beacon
Press, New York, 195T;
17. Selm, R.P., "Ozone Oxidation of Aqueous Cyanide Waste Solution
in Stirred Batch Reactors and Packed Towers", Advances in
Chemistry Series, 21, American Chemical Society, Washington,
D.C. 1959.
18. Laubusch, E.J., "Chlorination of Wastewater", Water and
Sewage Works, vol. 105, 1958.
19. Moore, W., Physical Chemistry, Prentice-Hall, Englewbod
Cliffs, New Jersey, 196Z.
20. U.S. Patent 2,981,682: Chlorination of Water Soluble Iron
Cyanide Compounds Using Mercuric Chloride Catalyst.
21. U.S. Patent 3,101,320: Conditioning Cyanide Compounds.
22. Kodak Professional Handbook, Motion Picture and Education
Markets Division, Eastman Kodak Co., Rochester, New York,
1967, Procedure 1102-A.
23. Ibid., procedure HOOF
24. Ibid., procedure 1101B
25. Ibid., procedure 1122
26. Dryden, C. and Furlow, R., Chemical Engineering Costs,
Engineering Experiment Station, Ohio State University,
Columbus, Ohio, 1966.
27. G.J. Mohanrao, K.P. Keishnamoorthis and W.M. Deshande,
"Photo-Film Industry Waste: Pollution Effects and Abate-
ment", Third International Conference on Water Pollution
Research, Section 1, No. 9, Water Pollution Control Feder-
ation, 1966.
28. C.J. Terhaar, Ewell, W.S., Dziuba, B.S., and Fassett, D.W.,
"Toxicity of Photographic Processing Chemicals to Fish"
presented to SPSE Meeting, Chicago, April 22, 1971.
«•
29. Sollmann, Torald; "Correlation of the Aquarium Goldfish
Toxicities of Some Phenols, Quinones, and other Benzene
Derivatives with their Inhibition of Autooxidative Reactions.
110
-------
50. T.H.Y, Tebbutt, "Problems of Toxic Effluents" Effluent
and Water Treatment Journal, 6:316-17, 319-21, July, 1966.
31. Greenwell, T.R. and Brewer, P.E.; "Operation of a Two-Staged
Aeration Lagoon <3n Photographic Waste Effluent". Presented
at SPSE conference, April 22, 1971.
32. Disposal of Photographic Wastes, Kodak-Publication No. J-28,
Eastman Kodak Co., Rochester, New York, 14650.
S3, Bober, T,W,, "Pollution Abatement} What You Can Do in the
Cameraroom" Kodak Bulletin for the Graphic Arts No. 21,
Eastman Kodak Company, 1970.
34. Hendrickson, T.N. § Durbin, H.E., "Photographic Wastes as
Pollutants" Credit Line C-PAC, January 1971.
35. LeFebvre, E.E. and Callahan, R.A.;"The Toxic Effects of
Color Photographic Processing Wastes on Biological Systems"
presented at SPSE, April 22, 1971.
36. Zehnpfennig, R.G., "Possible Toxic Effects of Cyanates,
Thiocyanates, Ferricyanides, Ferrocyanides and Chromates
on Streams".
37. Hendrickson, T.N.; "Pollution Problems the Photofinisher
Must Face", Photo Marketing, June, 1970.
38. "The Preparation or Regeneration of a Silver Bleach Solution
by Oxidizing Ferrocyanide with Persulfate" B.A. Hutchins
and L.E. West, J. SMPTE, 66, pp. 764-768, Dec., 1957.
39. "Method for Oxidizing Potassium Ferrocyanide to Potassium
Ferricyanide," U.S. Patent 1,732,117, Oct. 15, 1929.
40. "Electrolytic Preparation of Alkali Metal Ferricyanide,"
U.S. Patent 2,353,781, July 18, 1944.
41. "Electrolytic Preparation of Sodium Ferricyanide," U.S.
Patent 2,353,782, July 18, 1944,
42. "Recovering Silver, from Fix Baths," Eastman Kodak Co.,
Pamphlet #J-10.
43. "Silver Recovery from Exhausted Fixing Bath" J.I. Crabtree
and J.F. Ross, Trans, of SMPE ,, No. 26.
44. "Automatic Silver Recovery" K. Hickman, J. of SMPE, Vol.
XVII, No. 4, pp. 591-603, 1931.
45. "Noninstrumental Determination of Silver in Fixing Baths,"
B.A. Hutchins, J. SMPTE, Vol. 75, No. 1, pp. 12-14, Jan.,
111
-------
46. "A Silver Recovery Apparatus for Operation at High Current
Densities," N.J. Cedrone, J. SMPTE, Vol. 67, Mar. 1958.
47. "The Electrolytic Regeneration of Fixing Baths," K. Hickman,
C. Sanford, W. Weyerts, Communications #471, Kodak Research
Laboratories.
48. "The Argentometer - An Apparatus for Testing for Si ver in
a Fixing Bath", W.J. Weyerts and K.C.D. Hickman, Cor.isrunication
#548, Kodak Research Laboratories, 1935.
49. "The Recovery of Silver from Exhausted Fixing Baths", J. I.
Crabtree and J.F. Ross, Communication #280, Kodak Research
Laboratories.
50. "Electrolysis of Silver Bearing Thiosulfate Solutions" K.
Hickman, W. Weyerts, O.E. Goehler, Industrial and Engineering
Chemistry,, Vol. 25, p. 202, Feb, 19371
51. "Electrolysis of Complex Silver Salt Solutions" Dr. Tibor
Erdey-Gruz and Dr. Vareria Horvathy, Magyar Kim-Lapja,, 4,
pp. 524-531, 1949, Budapest University of Science.
52. "Electrolytic Recovery of Silver from Fixing Baths at Low
Current Density" A.A. Rasch and J.I. Crabtree, Photographic
Science and Technique, Series II, Vol. 2, No. 1, pp. 15-33~
reb. 1955.
S3, 'Electrolytic Recovery of Silver from Used Fixer Bath" H.
Aisenbrey and U. Fritze, Rontgenpraxi s, Vol. 19, No. 11,
pp. 284-302, 1966.
54. "The Problem of Silver Recovery from Exhausted Fixing Solutions'
G.A. Namias, Progresso Fotografico, 44, No. 7, pp. 272-274,
July 1939.
55. "Electrodesposition of Silver with Superimposed Alternating
Current" Larissa Domnikov, Metal Finishing, 63, pp. 62-66s
1965.
56. "Electrolytic Silver Recovery - A Survey" D.C. Britton,
British Kinematography, Vol. 45, No. 1, July 1964.
57. "Electrolytic Recovery of Silver" M.C. Kinsler, Photographic
Processing, Vol. 3, No. 6, June/July, 1968.
58. "Recovery of Silver from Wash Waters by Ionic Exchange
Chromotography" A.B. Devankov, V.M. Laufe;, A.A. Mironon,
T.S. Sishunova, Zhurnal Nauchnoi, Prikladnoi Fotpgrafii
Kinemotagraffi, 13, pp. 14-19, 196~8~;
59. "A Silver-Recovery Apparatus for Operation at High Current
Densities" N. J. Cedrone, SMPTE, Vol. 67, No. 3, pp. 172-174,
March 1958.
112
-------
60. "The Recovery of Silver from Exhausted Fixing Baths" J.I.
Crab-tree and J.F. Ross,' American Annual of Photography.
1927. *—tLJLt
61. "The Recovery of Silver from Fixing Baths by the Electrolytic
Method" Cesare deMitri, Ferrahia Magazine. Vol. XII, No. 1.
1964. '
62. '^Extraction of Colloidal Silver-Sulfide from its Hydrosol
by Emulsification" L.D. Skrylev, V.I. Borisikhina, S.G.
Mlkrushin, Zhurnal Prikladnol Khimii, Vol. 37, No. 3, pp 693-
695, March 1964. ———————
63. U;S. Patent 1,866,701: Method and Apparatus for Recovering
Silver from Fixing Solutions.
64. U.S. Patent 476,985: Process and Apparatus for the Electrolysis
of Photographic Fixing Solutions.
65. U.S. Patent 2,493,396: Recovery of Silver from Solutions
of Silver Salts.
66. U.S. Patent 2,503,104: Process for Precipitating Silver from
Solution.
67. U.S. Patent 2,507,175: Silver Recovery.
68. U.S. Patent 2,529,237: Electro-Recovery of Metals.
69. U.S. Patent 2,545,239: Recovery of Gold or Silver.
70. U.S. Patent 2,579,531: Process for Extracting Gold'or Silver
7i. U.S. Patent 2,607,721: Silver Recovery from Sodium Thio-
sulfate Solutions.
72. U.S. Patent 2,612,470: Selective Electrodeposition of Silver.
73. U.S. Patent 2,619,456: Metal Recovery Apparatus.
74. U.S. Patent 2,791,556: Apparatus for the Recovery of Silver
from Photographic Processing Baths.
75. U.S. Patent 2,905,323: Apparatus for the Recovery of Silver
from Spent Photographic Solutions.
76. U.S. Patent 2,934,429: Silver Recovery Process.
77. U.S. Patent 3,003,942: Electrolytic Cell For Recovery of
Silver from Spent Photographic Fixing Baths.
78. U.S. Patent 3,082,079: Silver Recovery from Photographic
Fixing Solutions.
113
-------
79. U.S. Patent 3,043,432: Apparatus for Recovery of Silver
from Spent Photographic Solutions.
80. U.S. Patent 3,311,468: Silver Recovery Process.
81. Schreiber, M. L., "Present Status of Silver Recovery in the
Motion Picture Industry,: J. SMPTE, Vol. 74, June 1965.
114
-------
SECTION X
GLOSSARY
Absorbance - The negative Iog10 o£ the percent transmission of
radiant energy.
Aerobic - Requiring, or not destroyed by, the presence of free
elemental oxygen.
Anode - The positive electrode of an electrolytic cell where
oxidation occurs.
BOD - Abbreviation for biochemical oxygen demand. The quantity of
oxygen used in the biochemical oxidation of organic matter in a
specified time, at a specified temperature, and under specified
conditions.
Cathode - The negative electrode of an electrolytic cell where
reduction occurs .
Chlorjnation - The application of chlorine to water or wastewater,
generally for the purpose of disinfection, but frequently for
accomplishing other biological or chemical results.
Chlorox-- Registered trade mark, Chlorox Corp., Oakland, California;
contains 5% sodium hypochlorite by weight.
Clarity - The inverse of absorbance.
COD - Abbreviation for chemical oxygen demand. A measure of the
oxygen - consuming capacity of inorganic and organic matter present
in water or wastewater. It is expressed as the amount of oxygen
consumed from a chemical oxidant in a specific test. It does not
differentiate between stable and unstable organic matter and thus
does not necessarily correlate with biochemical oxygen demand.
Also known as OC and DOC, oxygen consumed and dichromate oxygen
consumed, respectively.
Complex Cyanide - Ferrocyanide {Fe(CN)6~4} and/or ferricyanide
U-e
Concentration Polarization - The production of any irreversible
potential at the surface of an electrode by change of ionic cofc-
centration in the immediate vicinity of the electrode.
Conversion - The oxidation of ferrocyanide to ferricyanide.
Coulomb - The current passed when 1 amp flows for 1 second.
Current dcnsiry Current per unit area of electrode surface.
115
-------
Current density ratio - The ratio of current-density, of the
cathode to the current density of the anode.
Cuvette - A cell used for spectrophotometric measurement.
Electrolysis - Affecting a chemical change by means of aa applied
electric current.
Equivalent weight - The amount of a substance which reacts with
one Faraday; usually the formula weight divided by the valence.
Faraday - An amount of electricity equal to 96,487 coulombs
(amp-sec).
Flocculation - In water and wastewater treatment, the agglomeration
of colloidal and finely divided suspended matter after coagulation
by gentle stirring by either mechanical or hydraulic means.
Flow Study - A centrifugation study in which the rotor speed
remains constant while the flow rate is varied.
Ion permeable membrane - A membrane which allows only select ions
to pass through.
K-12F Bleach - Ferricyanide bleach used in processing Kodachrome
reversal film.
Kodachrome - Trade name for color film manufactured by the
Eastman Kodak Co.
Oxidation - The process by which atoms of an element lose electrons.
Ozonation - Affecting a chemical change by means of ozone.
Photochemical - Achemical reaction catalyzed by light.
Prussian Blue - Ferric ferrocyanide.
Reduction - The process by which atoms of an element gain electrons.
Regeneration - The oxidation of ferrocyanide to ferricyanide.
Stoichiometric - Pertaining to or involving substances which are
in the exact proportions required for a given reaction.
Supernatant - The liquid standing above a sediment or precipitate.
•
Synergism - The improvement in performance achieved because two
agents are working together.
116
-------
Theoretical Oxygen Demand CTODj - The theoretical amount of
oxygen that would be consumed if a chemical were to be oxidized
to the highest oxidation state of each element in the compound.
(i.e. C02, H20, etc.) *
Toxicity - The quality of being poisons.
Abbreviations Used
£ - grams
1 - liters
Min - minutes
m£ - milligrams
nl. - milliliters
Mu - millimicrons (10"9 meters) - nm (nanometers)
ppm - parts per million - mg/1 (milligrams per liter)
117
-------
SECTION XI
APPENDICES
A Reagents Used in Various Ferro-Ferricyanide
Analysis Procedures
B Method of Analysis of Ferrocyanide in the
Presence of Ferricyanide
C Centrifugation Procedure
D Detailed Analytical-Procedures
E The Photographic Process and Sources of
Pollution
Figure E-l Ektachrome Reversal Film Process
Table E-l Steps in Color Process
Table E-2
Table E-3
Table E-4
Table E-5
Ions or Compounds Found in Black-and-
White and Color Processing Solutions
Approximate Chemical Concentrations
in Effluents from Photo Processing
Machines
BOD of Chemicals Used in Photographic
Processing
Relative Ineffectiveness of Biological
Type of Treatment of Photographic
Chemicals
F Waste Treatment Facilities Presently in Use
Table F-l Concentration of Chemicals in
Waste Effluent at Typical Photo-
finishing Plants
Table F-2 Chemicals Removed by Treatment
Page No
120
121
122
123
127
134
135
136
139
141
142
143
149
150
119
-------
APPENDIX A
Reagents Used in Various Ferro - Ferricyanide Analysis Procedures
Reagents Used
Procedures in Which Reagents
Are Used
ro
o
1) 0.6 Molar Potassium Iodide
(49.8 gm KI/500 ml)
2) Zinc Sulfate-Sulfuric acid reagent
(125 gm ZnS04'7H70, dissolved in
7.0 N H2S04 dilute to 500 ml)
3) 0.100 Normal Sodium thiosulfate
(24.82 gm Na2S203'5H20/liter
4) Starch Solution: 1.0 gm starch
(in 10 cc cold HO, stir into 200 cc
boiling water)
5) 2.5 Normal Sodium Hydroxide
(110 gm/1)
6) Ferrous - Ferric reagent (.75 gm FeCl2)
20 ml H20 (distilled) (.75 gm FeCl3)
3.0 ml HCL - dilute to 30 ml
7) 7.0 Normal Sulfuric Acid
8) 0.050 Ceric sulfate (26.4 gm/1)
1) Cerimetric determination, of ferricyanide
2) Cerimetric determination of ferricyanide
3) Cerimetric determination of ferricyanide
4) Cerimetric determination of ferricyanide
5) Spectrophotometric determination ferro-
cyanide
6) Spectrophotometric determination of ferro-
cyanide (modified Kodak method)
7) Cerimetric and potentiometric determination
ferrocyanide
8) Cerimetric determination of ferrocyanide
-------
APPENDIX B
Method of Analysis of Ferrocyanide
in the Presence of Ferricyanidc
1) Concentration of ferricyanide measured
using absorbance at 417 my. (Column 1 and 2)
2) Since both ferro-and ferricyanide absorb
at 220 my, absorbance at 220 my includes
contribution from both. (column 3)
3) Calculate contribution to total 220 my
absorbance due to ferricyanide (coulmn 4)
(100 gm/1 ferricyanide has an absorbance
of 1.52 at 220 my )
4) Calculate contribution to total 220 my
absorbance due to ferrocyanide.
(column 3 minus column 4 listed in
column 5)
5) Calculate concentration of ferrocyanide
using absorbance at 220 my as shown in
column 5 (column 6)
Below is a sample run using known concentrations of ferro and ferricyanide.
*% *9 M r* +
1
Total
Absorbance
at 417 my
2
Calculated
Concentration
Ferricyanide
mg/1
3
Total
Absorbance
at 220 my
4
Absorbance
due to
Ferricyanide
at 220 my
5
Absorbance
due to
Ferrocyanide
at 220 my
6
Calculated
Concentration
Ferrocyanide
at220 my
7
Actual concen-
tration mg/1
ferri ferro
1.40
.72
.37
.186
.095
.048
316
162
83
41
20
10
29.5
15.1
8.1
4.0
1.95
1.00
5.
2,
1,
00
45
20
,60
,36
.17
24.5
12.55
6.90
.40
3.
1,
59
.83
236
121
65
33
15
8
320
160
80
40
20
10
256
128
64
32
16
8
-------
APPENDIX C
Centrifugation Procedure
A. Start centrifuge and slowly increase rotor speed to, 6500
rpm. (Manufacturer's recommended minimum speed)
B. Fill collection tubes from carboy at 25 ml/min. When tubes
are filled, stop flow and allow centrifuge to run for five
minutes to stabilize tube contents.
C. Rotor Study (Constant Flow)
1) On the initial run for each metal, a constant flow of
25 ml/min was used; on subsequent runs, the optimum
flow from the previous run was used.
2) Start flow and allow to run for two minutes at 6500 rpm,
take a 10 ml sample and shut off flow.
3) Slowly increase rotor speed to next step and allow two
minutes for stabilization.
4) Start flow and allow to run for two minutes before taking
sample. Shut off flow and increase rotor speed.
5) When maximum speed has been reached, follow same procedure
decreasing rotor speed stepwise.
D. Flow Study (Constant Rotor Speed)
1) Flow study for each metal carried out at the optimum
rotor speed for the particular metal and flocculant
concentration.
2) After rotor speed has been obtained, allow five minutes
for stabilization.
3) Start flow at 6 ml/min and allow to run for four minutes
(two minutes in all other cases) and take a 10 ml sample
Shut off flow for 2 minutes.
4) Start flow at next higher rate and run for two minutes
before taking sample.
5) When- maximum flow rate has been reached, follow same
procedure, decreasing flow rate stepwise.
122
-------
APPENDIX D
Detailed -Analytical Procedures
Potentiometric. determination of ferrocyanide in process K-12F
bleach (22) — r —
Add 250 ml o£ distilled water to a 400 ml beaker and place on
a magnetic stirrer at slow speed using a magnetic stirring bar.
Pipet (held vertically) 5.0 ml of sample into the beaker.
Add 10 drops 0.010 N Sodium Diphenylaminesulfonate indicator.
Place electrodes from a pH-millivolt meter into solution.
Titrate solution, from a 50 ml burette, with 0.050 N Ceric
sulfate in 0.5 ml aliquots, recording both burette and nwter
readings.
Find endpoint by delta method
Calculation: 4.84 x (ml) of 0.050 eerie sulfate added at
endpoint) "grams/liter of Na4Fe(CN)6'10 H.p
in sample.
Ipdometric determination of ferricyanide in process K-12F
Bleach (.23J
Pipet 5.0 ml of sample and 5 ml of distilled water into a 250 ml
Erlenmeyer flask, and place on a magnetic stirrer at slow speed.
Pipet 25 ml of 0.6 M potassium iodide solution and 20 ml of
zinc sulfate-sulfuric acid reagent. (See Appendix A)
Titrate with 0.100 N sodium thiosulfate until color changes to
pale yellow.
Pipet 5 ml of standard starch solution into the flask.
Continue titration until the blue color disappears.
Calculation: 5.6 x (ml of 0.100 N Na2S,0 added at endpoint) -
grams/liter Na3 Fe(CN)6 in Sample.
Ipdometric Determination of ferricyanide in K-12F Bleach (B]
Using an upright pipet, add 5.0 ml sample and 5 ml distUled
water to a 250 ml Erlenmeyer. flask.
Place on magnetic stirrer and stir at low speed.
Pipet 10 ml of 0.7 M zinc acetate solution and 20 ml of 3.0M
sodium acetate buffer into the flask.
123
-------
Add 5.0 grams o£ potassium iodide crystals to the solution
and dissolve.
Rinse down the inside of the flask with distilled water and
immediately titrate with 0.100 N sodium thiosulfate solution
to pale yellow.
Add 5 ml of a standard starch indicator solution and continue
titrating until blue color disappears.
Record burette reading,
Calculation: 5.6 x (ml 0.100 N sodium thiosulfate) • gm/liter
sodium ferricyanide.
Cerimetric Determination of Ferrocyanide in K-12F Bleach (24)
Add 250 ml distilled water to a 400 ml beaker.
Using an upright pipet add 5.0 ml of sample to the beaker.
Pipet 10 ml of 7.0 N sulfuric acid to the beaker.
Add 10 drops of sodium-diphenylamine-sulfonate indicator solution.
Place on magnetic stirrer and titrate with 0.050 eerie sulfate
solution.
Record burette reading.
Calculation: 4.84 x (ml 0.050 eerie sulfate) • gin/liter-
sodium ferrocyanide.
Spectrophptometric Determination of Ferrocyanide, Modified
Kodak Method
Using an upright pipet add 10.0 ml of sample to a 100 ml volumetric
flask and dilute to volume with distilled water.
Stopper flask and shake to mix the solution thoroughly.
Acidify the solution with concentrated hydrochloric acid (using
pH indicator paper) to pH 3-4.
Take 40 ml of the acidified solution and add 2 drops of the
ferrous-ferric reagent. Stir immediately.
Allow sample to stand for fifteen minutes without further
agitation to develop blue color.
Fill one spectrophotometer cell with the solution to which the
ferrous-ferric reagent was added.
124
-------
Fill a matching cell with the solution to which the ferrous-
ferric reagent was not added. This is the blank solution.
Insert both cells into a spectrophotometer and zero the blank
at 700 nm.
Measure the absorbance of the blue sample at 700 nm on the
spectrophotometer. *
Calculation: 22.4 x (Absorbance at 700 nm) x (dilution factor)
mg/liter sodium ferrocyanide.
*If absorbance of blue solution is greater than 0.8, dilute 10.0
ml of the acidified sample to 100 ml and repeat. If solution "
does not visually turn blue repeat test without diluting sample.
Spectrophotometrie Determination of Ferricyanide at 417 nm
Fill one spectrophotometer cell with the solution to be
analyzed.
Fill a matching cell with distilled water. This cell is the
blank.
Place both cells in the spectrophotometer and zero the blank
at 417 nm.
Measure the absorbance.of the sample at 417 nm on the spec-
trophotometer.*
Calculations: 296 x (Absorbance at 417 nm) (dilution factor) -
mg/liter sodium ferricyanide.
Spectrophotometric Determination of Sodium Ferrocyanide at 220 nm
Fill one spectrophotometer cell with the solution to be analyzed.
Fill a matching cell with distilled water. This is the blank.
Place both cells in the spectrophotometer and zero the blank
at 220 nm.
Measure the absorbance of the sample at 220 nm on the spectre-
photometer.*
Calculation: 16.7 x (Absorbance at 220 nm) x (dilution factor) -
mg/1 sodium ferrocyanide
*If the absorbance is greater than 0.8 dilute 10.0 ml of^ample
to 100 ml and repeat the test.
125
-------
Spectrophotometric Determination of Ferricyanide at 460.5 nm
Fill one spectrophotometer cell with the solution to be analyzed.
Fill a matching cell with distilled water. This is the blank.
Place both cells in the spectrophotometer and zero the blank at
460.5 nm.
Measure the absorbance of the sample at 460.5 nm on the spectro-
photometer.*
Calculation: 2.85 x (Absorbance at 460.5 nm) x (dilution factor)-
g/1 sodium ferricyanide.
*If the absorbance is greater than 0.8 dilute 10.0 ml of sample
to 100 ml and repeat the test.
Preparation of Ferro-ferri Reagent
Dissolve in 20 ml of distilled water 0.750 g ferric chloride and
0.750 g ferrous chloride.
Add 3 ml concentrated hydrochloric acid.
Dilute to 30 ml with distilled water.
126
-------
APPENDIX E
The Photographic Process and Sources of Pollution
The color reversal Ektachrome photographic process waste efflu-
ent is representative of pollution problems from the pho-tographic
industry, because it contains all the typical processing solutions.
The film travels through the series of baths, as shown in Figure
E-l, (page 134). These include: the prehardener, neutralize? 1st
developer., 1st stop, water wash, color developer, 2nd stop, water
wash, bleach, fixer, water wash and stabilizer.
The functions of each of these solutions are described in Table
E-l.
It should be noted that combinations of these solutions are used
to make up all other major photographic processes. For example,
the processing of color negative film consists of a color developer,
stop fix, bleach, fix and stabilizer. These solutions are of
a similar composition as the corresponding solutions in the Ekta-
chrome process. However, since the solutions that are used in
these other processes are all contained in this single process,
the Ektachrome process is discussed here. Any cited problem,
with a particular solution in that process, would thus.be analogous
to a problem with the same solution in another process.
Table E-2 shows the range of individual chemicals contained in
the processing solutions mentioned previously. This information
has been published by the Eastman Kodak Co.
Table E-3 lists the approximate average concentration of in-
dividual chemicals contained in the various photographic pro-
cesses. Here it can readily be seen that any one specific chem-
ical may be contained in a -number of photographic processes;
some in all.
Table E-4 lists the primary chemicals discharged from the photo-
graphic process that are organic and thus* would exert an oxygen
demand when discharged to the environment. This list was taken
from Kodak Pamphlet J-28 entitled, "Disposal of ?hotograPhic
Wastes". A primary concern is the specific chemicals that show
a small five-day biochemical oxygen demand (BODS) upon jesting,
but actually require a large amount of oxygen to be totally
oxidized to ine?t end products of carbon dioxide an^ater.
The following general reaction describes what is termed Theoret
ical Oxygen Demand (TOD) :
XC H Szl Nz2 + 02 - aC02 * b H20 * c N0'3 + d S04" (46)
The TOD thus represents the total XJ1""- J^
the environment. A comparison of the TOD to the
individual chemical gives an indication of the relative bio
degradability of the chemical.
127
-------
Table E-5 lists the number and percentage of the 45 chemicals
shown in Table E-4 in categories of the percentage ratio of
BODr to TOD. 20S of'the chemicals had a BOD5 less than 1% of
their TOD; for 51.2S of. the chemicals, it was less than 101.
This means that if. those chemicals were treated in a municipal
» plant that w;i- cMn.iMi* of total BODS removal, 51.25 of the or-
ganic photo^r.rpliU chemicals would still exert 901 of tHeir
'total oxygon demands upon the environment.
A discussion of the specific pollutant chemicals contained in
each of the processing solutions (as listed in Table E-2) follows:
Prehardener
j
The primary chemicals of concern in a prehardener are aluminum
and formaldehyde; although neither is considered to be relatively
toxic. Formaldehyde can be easily oxidized to carbon dioxide
and water in a municipal secondary treatment plant,or with a
strong chemical oxidant.
Black-and-White Developers
Hydroquinone and Elon developing agents in the black-and-white
developers are both highly toxic to fish,if discharged into
streams. When tested to indigenous carp (cyprinidia), Mohanroa, (27)
et.al., found that hydroquinone and elon were toxic (caused fifty
percent of a fish population to die) at 0.3 mg/1 and 5 mg/1
respectively. However, in combination the chemicals showed a
synergistic effect and the effluent became toxic at lower con-
centrations of each. Terhaar (28) et.al., reported that hydro-
quinone and elon were equitoxic at 0.1 mg/1.
Sollman (29) showed that, "Hydroquinone when added t0 the
aquarium water was found to be about a hundred times more toxic
than phenol, to gold fish (and to Daphnia magna), but is only
about twice as toxic when injected into fish or mammals." West (10)
reports that, "Fortunately, hydroquinone is quickly biodfcgrade'd
in a waste-treatment plant".
Color Developers
No specific pollutant effects have been noted for constituents
in the color developer solution,relative to toxicity to fish
and biological organisms. Benzyl alcohol is only slightly toxic
to fish (in the range of 1 to 100 mg/l^but the chemical is con-
sidered to be biodegradable and reported to be treatable in a
secondary plant. Ethylene diamine, hexylene glycol and citra-
zinic acid are also contained in the developer effluent. These*
chemicals may not be highly toxic,but it appears they have a
very low biodegradability in a secondary type treatment plant.
Thus, there may be some persistence of these chemicals in the
environment..
128
-------
Stop Baths
-H™- ^S t/fi° r° S°m? a£ricul]:u*al products at concentrations
above 1 mg/1. Concentrations of greater than 4 mg/1 of boron
usefflr Irrfgallon^ Unsatis£act°^ *•* -ops, especially if
Boron levels of 50 mg/liter have been reported to reduce the
efficiency of biological treatment systems.
Acetate (from acetic acid) is not considered to be toxic to fish.
It does exert a high oxygen demand,if dumped into a stream, but
is readily treated in a secondary plant.
Bleaches
Ferricyanide in a waste effluent is converted to ferrocyanide
by thiosulfate and other chemicals. -Thus, only ferro and not
ferricyanide is normally discharged from photographic processing
plants.
Ferrocyanide is non-biodegradable. Although the compound is not
particularly toxic, it is slowly converted to toxic free cyanide
in the^ presence of sunlight and air. Numerous reports on the
toxic effects of cyanides have been made. Some quotations follow:
"The effluents from treatment plants re-
ceiving photo-waste must be diluted at
least 10 fold by receiving streams to sat-
isfactorily dilute undegraded effluent
cyanides." (35)
"Under no circumstances may the untreat-
ed EA-4 (Ektachrome) bleach be safely
released into any stream. During military
field operations this bleach must be
dumped into a holding tank " (35)
"An unknown amount of iron cyanides and
thiocyanates (less than 3.5 mg/1 assuming
good nlant performance) will be present
in the effluent of an Ektachrome waste.
~ub- .,";";i chlorination and the action
01 suuii-ht may result in substantial
conversion of these chemicals to highly
toxic HCN and CNCT compounds. For these
reasons, at least a ten fold dilution of
is preferable." (35)
129
-------
"Depending on your locality and your re-
gulatory agency, ferricyanide and ferro-
cyanide effluents may need tight control.
Therefore, regeneration of ferricyanide-
bearing bleaches, where practical, is rec-
ommended, both as a pollution-control
measure and for economic reason." (32)
Thiocyanates may also be found in photographic bleaches with
these resulting problems:
"Thiocyanates are toxic in.chronic doses at
relatively low levels. Toxicity is related
to interference with thyroid function.
Plants 'of the cabbage-turnip family may be
able to concentrate thiocyanates from irri-
gation water." (36)
" thiocyanates decompose in sunlight
to release amounts of cyanide toxic to
acquatic life at concentrations of 2
mg/1 or above" (36)
Fixing Baths
Silver is another serious pollutant. In concentrations as low
as 0.005 milligrams per liter, it has a lethal effect on bacteria
necessary to the digestion of sewage. (30) Thus, even minute
traces of silver in the photographic effluent can be harmful
to biological treatment plants or to stream life. It has been
stated that silver will precipitate out as silver halide in
waste effluents and be removed in waste treatment plants. This
is seldom true,because the transit time from photographic lab-
oratory to sewage treatment plant is insufficient to allow pre-
cipitation to occur. Silver goes into the treatment plant as
a silver complex that will kill enough bacteria to reduce signif-
icantly the efficiency of a plant.
Concerning discharge to a treatment plant, Greenwell (31) re-
ported "that silver in photographic processing effluent is in
a complex form and is not toxic to biological treatment systems".
However, that data was based upon a biological system for treating
photographic wastes only. LeFebvre and Callahan reported that
silver destroys activated sludge in a municipal plant at very
low concentrations. (35) It is safe to assume that most muni-
cipal plants now receive some silver and it may be a cause for
reduced plant efficiency. In addition,any silver passing through
the plant will have significant toxic effect on the acquatic or-
ganisms of the treatment plant receiving water.
Silver ion also reduces Biochemical Oxygen Demand results by
preventing the action of microorganisms. A concentration of
0.03 mg/1 silver produced a 25% reduction in BOD measurement,
while a 1.0 mg/1 concentration produced an 81* interference. (30)
130
-------
Thiosulfate and sulfite are not directly toxic to fish How-
ever, if dumped into a lake or stream, these chemicals'rob
oxygen from the water and "suffocate" acquatic life. In that
case,the chemicals are indirectly toxic to the acquatic life
If dumped to a municipal plant having primary and secondary
treatment, these chemicals receive adequate treatment. However.
thiousulfate and sulfite have high chlorine demands. Thus,they
may rob the disinfectant power of chlorine,used to kill bacteria
in effluent from the treatment plant. Many photofinishers are
affected by chlorine demand laws.
Hendrickson and Durbin (34) have thus reported:
"The thiosulfate in the fixing solution,
even after the silver has been removed,
also creates a problem in the treatment
plant. It is a strong reducing agent
which reacts with the disinfectant used
in the plant. When large quantities of
fixing solution are dumped, as they some-
times are, the municipal plant operation
is upset because the thiosulfate has taken
all the chlorine normally used to purify
the waste."
Ammonium ion,contained in some fixers,is a nutrient for algae.
If the pH is too high (>pH 8), ammonium ion forms ammonia.
Ammonia is also used as an agriculture fertilizer and is a
common ingredient in domestic sewage. Disposal through the
municipal waste treatment plant should be effective.
Some specific reported problems with fixers follow:
"Desilvered EA Ektachrome (photographic)
waste cannot be disposed of without de-
gradative treatment unless such action
is justified as defined in Executive Or-
ders 11507 and 11514 (National Crisis).
When so justified, EA-4 waste may be
introduced untreated into streams with
a volume of at least 3.4 cubic feet per
second (CFS) " (35)
"Desilvering EA-4 (Ektachrome) fixer bath
nrior to disposal is mandatory regardless
Sf the disposal technique. *on-delivered
waste is extremely toxic to all biological
systems tested." (35)
131
-------
"(Ektachrome) EA-4 waste must bo dcsilver-
ed prior to stream disposal. Disposal of
wastes containing silver content, oven for
a short period will result in serious
pollution." (35)
"The extreme toxicity of non-desilvered
EA-4 (Ektachrome) waste to activated
sludge organisms is caused by the
accumulation of silver in the sludge." (35)
"Silver removal is a mandatory requirement x
for photowaste being introduced into a
biological treatment system." (35)
"....(fix) disposal presents a serious
pollution problem in view of the fact
that in large scale installations the
volume of fixing solution to be discard-
ed can be very large and further in view
of the fact that the thiosulfate ion which
is present in the solution following
recovery of the silver is a major pollutant
because of its high oxygen demand."
"A photographic laboratory in a moderate
sized sewage system would almost certain-
ly pose a continuing threat to an activated
sludge plant or to sewage digestion..." (36)
"Sodium thiosulfates used in large quantities
in photographic processing is a strong re-
ducing agent and could accelerate the re-
duction of ferricyanide to HCN." (36)
"....the lethal concentration of silver
may be as low as 0.005 mg/1 for fish and
0.01 mg/1 for bacteria so that even minute
traces of silver in photographic effluent
could be harmful to biological treatment
plants or to river life." (30)
Neutralizers
Neutralizers are usually of little concern as part of a photographic
waste effluent. Acetate is the primary organic chemical and it
has been discussed previously under Stop Baths.
132
-------
Stabilizers
Zinc is the primary contaminant of the stabilizer. It has
been reported (30) as being toxic to fish in the range of 1-2
mg/1. The critical level' in raw sewage/for continuous doses
on biological systems,is 5-10 mg/1. (30). The critical level
in raw sewage for a four-hour shock dose,giving a significant
reduction in aerobic treatment,is 160 mg/lj while the maximum
concentration of zinc»that would not impair anaerobic digestion
of primary and secondary treatment plant sludges,is 10 mg/i, (30)
Eine ion will also interfere with Mdehemieal Oxygen Demand
(BOD) measurements. Tebbuts (30) reports that a concentration
of 1 mg/1 reduces BOD measurement by 8%,while a 7.0 mg/l^concen-
tration produced a 251 interference.
133
-------
Prehardener
3
H
Neutralizer
1st Developer
1st Stop
1st Wash
Color Developer
2nd Stop and
Hardener
2nd Wash
Bleach
Fix
3rd Wash
Stabilizer
o>
o
o
I*
PL,
•rt
U<
rt
en
(4
o>
O
o
(H
X
O
(0
+J
^4
W
N
3
taO
•H
(*(
134
-------
TABLE E-l
STEPS- IN COLOR PROCESS
The composition o£ the solutions used in the color process are
shown in Table E-2. The function of each solution is as follows:
a. Prehardener - Reduces emulsion swelling during processing.
bi Neutralise? - Neutralise'! hardening agent§ carried over
by the film to prevent their reaction with the coupling
agents in the film.
c. First Developer - Exposed areas are developed to give a
black-and-white negative silver image.
d. First Stop Bath - Stops action of First Developer and re-
duces emulsion swell.
e. Water Wash - Flushes acid solution off of the film.
f. Color Developer - Develops all remaining silver halide,
resulting in positive images.
g. Second Stop Bath - Stops action of the Color Developer.
h. Water Wash - Flushes the acid solution off of the film.
i. Bleach - All metallic silver is converted to silver halide.
j>' Fixing Bath - Silver halides are removed by reaction with
thiosulfate.
k. Water Wash - Fixing bath flushed off of film
1. Stabilizing Bath - Hardens emulsion and stabilizes^dye
image.
135
-------
TABLE E-2
IONS OR COMPOUNDS FOUND IN
BLACK-AND-WHITE AND COLOR PROCESSING SOLUTIONS
(From Manual J-28, Eastman Kodak Co.)
TYPE OF SOLUTION
AND pH RANGE
10 to 100
CONCENTRATION RANGE IN GRAMS PER LITER
LESS THAN 1
1 to 10
Prehardeners,
Hardeners and
Prebaths
pH 3 to 10
Sulfate
Acetate
Formaldehyde
Aluminum
Trivalent Chromium
Succinaldehyde
Formaldehyde Bisulfite
Sequestering agent
Carbonate ion
Antifoggant
(for example,
5-nitrobenzimidazole
nitrate)
Developer
pH 9 to 12
Sulfite
Borate
Phosphate
Carbonate
Sulfate
Bromide
Developing agents
(hydroquinone or
Kodak Color Developer
Agent CD-3)
Coupling agents
(in Kodachrome process)
Sequestering agent
Hydroxylamine
Diethylhydroxlamine
Benzyl alcohol
Hexylene glycol
Citrazinic acid, sodium salt
Ethylenediamine
Polyethylene glycols
Thiocyanate
Iodide
Antifoggant
Tertiary butylamine
borane
citrate
-------
TABLE E-2
(Continued)
TYPE OF SOLUTION
Ferricyanide
Bleaches
pH 5 to 8
CONCENTRATION RAN'',:. IN GRAMS PER LITER
AND pH RANGE
Stop Baths
pH 2 to 4
10 to 100
Sulfate
Acetate
1 to 10
Aluminum
Borate
Citrate
LESS THAN 1
Ferricyanide
Ferrocyanide
Bicarbonate
Nitrate
Fixing Baths
pH 4 to 8
Chloride
Thiosulfate
Ammonium
Aluminum
Bisulfite
Bicarbonate
Borate
Acetate
Bromide
Silver thiosulfate complex
Ferrocyanide
Formalin
Sequestering agent
-------
TABLE E.-2
(continued)
TYPE OF Sfi.UTION
AND pH :. '.U;
Neutral i:
pH 5
CONCENTRATION RANGE IN GRAMS PER LITER
10 to 100 1 to 10 LESS THAN 1
Bromide Acetate
Sulfate
Hydroxylamine
Stabilizers , Zinc Wetting agent
pH 7 to 9 Formaldehyde Sulfate
Phosphate
Citrate
Benzoate
Sequestering agent
-------
IM
W
<0
TABLE E-3
APPROXIMATE CHEMICAL CONCENTRATIONS IN
EFFLUENTS FROM PHOTO PROCESSING MACHINES
(mg/1 unless otherwise noted)
12 3456
Aluminum Ion
Ammonium Ion
Borax
Bromide Ion
Carbonate Ion
Ferrocyanide
Nitrate Ion
Phosphate Ion
Sulfate Ion
Sulfite Ion
Thiocyanate Ion
Thiosulfate Ion
Zinc Ion
Chromium (+6)
Acetate Ion
Benzyl Alcohol
Color Developer CD- 3
Elon
Formaldehyde
Hydroquinone
Mydroxyl Amine Sulfate
Volume (1/min)
BOD
C-22
70
670
180
90
140
240
190
220
800
120
120
330
70
820
Ekta- Ekta-
Print-C E-4 Print-R
20
80
300
60
310
160
310
130
210
1000
30
140
160
50
360
40
30
1240
40
10
90
110
290
120
200
300
10
120
250
20
60
40
60
60
20
30
380
10
20
50
70
70
40
60
100
160
10
170
80
20
10
190
10
30
60
430
B/W
Film
10
20
130
130
320
20-
20
240
B/W
Paper
10
210
50
.220
710
160
50
10
30
470
ME-4
250
10
400
910
1110
850
1380
2140
50
800
1870
190
430
440
390
190
20
2570
ECO- 2
260
10
400
600
1110
810
2600
1300
70
810
1920
230
210
460
190
190
70
2270
B/W
Reversal
30
130
30
160
480
20
220
10
20
~30
350
-------
TABLE E-3 (continued)
1. Color Negative (Kodacolor, Agfacolor, Fugicolor, Dynacolor)
2. Color Paper (Ektaprint-C, Hunt)
3. Color Reversal Slides (Ektachrome E-4)
4. Color Reversal Paper (Ektaprint -R)
5. Black-and-White Film
6. Black-and-White Paper
7. Color Reversal Movie Film (Process Ektachrome ME-4)
8. Color Reversal Movie Film (Process Ektachrome ECO-2)
9. Black-and-White Reversal
-------
TABLE E-4
Biochemical Oxygen Demand of Chemicals Used in
Photographic Processing Compared to Theoretical Oxygen Demand
(From Pamphlet J-28) '
Kodak Anti-Calcium No. 3
Kodak Anti-Fog No. 1
Kodak Anti-Fog No. 6
Kodak Anti-Fog No. 7
Balancing Developing Agent BD-82
BD-86
BD-89
Benzyl Alcohol
Butanedione
Carbowax 1540
Carbowax 4'000
Citrazinic Acid
Citric Acid, Monohydrate
Color Developing Agent CD-I
CD-2
CD-3
CD-4
CD-5
Coupling Agent C-16
M-40
y-S4
Dicolamine
Elon Developing Agent
Ethylene Diamine
Formalin
Formic Acid
Glacial Acetic Acid
Hardening Agent -HA-2
Hardening Agent -HA-1
Hexylene Glycol
Hydroquinone
Me theIon Developing Agent
Phenidone
Kodak Potassium Ferricyanide
Reversal Agent RA-1
Sodium Acetate
Sodium Bisulfate
Sodium Citrate (2H20)
Sodium Ferrocyanide, Decahydrate
Sodium Formate
Sodium Isoascorbate
Sodium Sulfite
Sodium Thiosulfate (SH20)
Stabilizing Agent-SA-1
Sodium Thiocyanate
Theoretical
Oxygen Demand
TOD Cultimate)
BODc
BOD5
TOD.
x 100
*
0.90
2-fc -~
.98
2. IS
2.70
1.13
1.91
2.70
2.55
1.68
3.59
3.62
1.36
0.68
2.53
2.68
1.58
1.91
2.28
2.47
1.44
2.20
1.96
1.86
3.47
0.62
0.23
1.06
2.22
0.60
2.3
1.9
1.98
2.67
1.52
3.50
0.78
0.16
0.49
1.06
0.24
1.25
0.12
0.32
1.54
1.58
-T-"
0.003
0.04
0.03
0.03
0.07
0.14
0.17
1.80
0.55
0.03
0.02
0.003
0.4
0;13
0.14
0.10
0.13
0.08
, 0.03
0.03
0.03
0.15
0.70
0.03
0.37
0.02
0.74
0.07
0.01
0.003
1.1
0.16
0.16
0.003
0.03
0.58
0.16
0.35
0.003
0.016
0.29
0.12
0.2
0.03
0.03
V
0.33
1.34
1.40
1.11
5.3
W • 4X
7.3
6.3
66.3
33.3
0.84
0.55
0.22
59.0
5.15
5.60
6.33
6.8
3.5
1.2
2.1
1.37
7.65
37.6 '
.865
59.5
9.1
68.0
3.6
1.67
0.13
58.0
8.1
6.0
0.20
0-86
73.5
100.0
68.0
0.28
8.0
23.2
100.0
62.5
1.95
1.90
• ttait weight of oxygen demand per unit weight of chemical (i.e g» 02/g.)
1*1
-------
TABLE E.-5
RELATIVE INEFFECTIVENESS OF BIOLOGICAL
TYPE OF TREATMENT OF PHOTOGRAPHIC CHEMICALS
Percent Range Number of
BODs Chemicals in Percent of
TOD x iuu Each Category Total
0.0 - 0.9i!> 9 20.0
1.0-9.99 23 51.2
10.0 - 49.9 3 6,7
SO.O - 89.9 8 17.7
90.0 -100 2 4.4
45 100.0
142
-------
APPENDIX F
WASTE TREATMENT. FACILITIES PRESENTLY IN USE
Treatment of Photographic Waste "Outside of
The following section was extracted in its entirotv
Pamphlet J-28. "Disposal of Photograp^'was^s"^ Eman Kodak
Co. under the section entitled: Methods of Waste Treatment
"Storm sewers or surface drainage for dis-
charging processing effluents without treat-
ment should not be used because of the
likelihood of violating the stream stand-
ard into which the sewer waste flows."
"Septic tanks are biological systems but
are not recommended for disposal of photo-
graphic processing wastes. Septic tanks
do not degrade the wastes sufficiently,
are generally designed for smaller volumes,
produce toxic and odorous products, can-
not be installed in all locations, and
run the risk of contaminating ground waters.
Septic tanks are anerobic systems, that is,
the biological process proceeds without
air."
"An aerated lagoon is not a practical
solution for many processors because a
large area of land is required. It is
also a safety hazard and runs the risk
of incomplete degradation, the creation
of odors, and contamination of ground
waters. However, if the lagoon is
large enough, is aerated, and has an
impervious liner, it may be satisfactory.
The overflow should be checked to insure
that it does not'contaminate the stream
into which it flows."
"Deep-well injection is legal in some
states, but only after careful study has
been made to prove that the rock struc-
ture of the area is such that there is
no probability of contaminating ground
waters. There is always the inherent
danger of contamination of ground waters.
Furthermore, the cost of investigating,
let alone cost of drilling and operating
the well, is extremely high. However,
Beale Air Force Base in California has
three injection wells for its photographic
processing wastes."
143
-------
"On the basis of our experimental work, wo
recommend treating processing effluents
in an aerobic-biological waste treatment
plant. The biological degradation in the
system destroys most oxygen demanding chem-
icals common to photographic processing
effluents just as it destroys domestic
sanitary wastes. The plant is sometimes
referred to as a secondary plant, the
primary plant being for the purpose of
only separating solids from the waste.
Laws are being formulated or are already
in effect in virtually all states in the
United States to require the equivalent
of secondary treatment of all wastes
entering a stream or lake. A biological
treatment plant makes use of the same
type of aerobic biological activity
that would occur if the waste were to
flow down a stream, except that the wastes
are degraded in a treatment plant in a
matter of hours, rather than the days
that are required in streams. Aeration
insures rapid aerobic degradation in a
waste-treatment plant."
"One type of secondary system is called
a trickling filter, so named because the
aerated waste trickles over a large surface
of small rocks or plastic so that the de-
sired biological degradation is accomplished.1
"Another common type of secondary plant is
the activated-sludge plant, usually built
in long rectangular tanks. It utilized
biological action brought about by air,
bacteria and nutrients. Some of the de-
gradation products are removed as gases,
some remain dissolved, and some precipitate
as a sludge. Municipal treatment plants
dry the sludge and generally use it for
land-fill. More complete biological de-
gradation may be attained by recirculating
some of the sludge and extending the aeration
time. Organic compounds, if degraded com-
pletely will produce carbon dioxide, water
and other products. Processing chemicals
such as hypo are also degraded by the
biological process."
144
-------
"
The biological treatment plant is the
least expensive method known for destruc-
tion of mixed oxygen-demanding wastes,
most of which are organic. Proper oper-
ation of a plant requires careful atten-
tion. The large municipal plants can
operate at much lower cost per unit
amount of waste than small plants. It
is probably less expensive to pay a muni-
cipality to handle the waste from a
processing laboratory compared with con-
structing and operating one for the exclus-
ive use of the laboratory."
In- Plant Treatment via Recovery and Recirculation of Potentially
Toxic Waste Materials.
In-plant treatment of process wastes appears to be the b*st method
of reducing pollution of chemicals that:
-cannot be treated in common treatment plants
(non-biodegradeables having a BODc less than
101 of their TOD: (See Table E-4) and
-adversely affect the treatment method (for
biological plants: thiosulfate, iron, boron,
silver, zinc and thiocyanate) .
Silver Recovery and Fixer Reuse
The profitability of silver recovery from fixing baths in pro-
cessing plants has been well known for many years. The prime
economic considerations are the substantial return for the re-
covered silver, and chemical savings that are possible by using
less fixer. Pollution abatement benefits also result, in that
less silver and less fix are sewered.
23 srs^sa - * «
of smaller storage tanks
145
-------
Methods of Recovery
In fixing baths, sodium thiosulfate (hypo) is used to fix the
image
Ag* + S203"~ * (Ag S203)" soluble C47)
by converting the undeveloped, insoluble, silver halide to a
soluble complex (see equation 47 ). This soluble complex dif-
fuses out of the photographic emulsion into the fixing bath.
As the fixing bath is used, it becomes a very complex mixture.
In addition to the original components of the fixing bath, a
used bath contains:sodium, ferrocyanide, sodium sulfate, sodium
bromide, gelatine, complex silver salts, and varying amounts of
practically all of the chemicals used in processing the material.
Therefore, any method of recovery has to make allowances for
these interfering substances. Fortunately, silver is far re-
moved,in the electromotive series,from any other metallic radical
in the solution. Most recovery methods take advantage of the
noble nature of silver.
Basically,there are two methods of silver recovery: chemical and
electrolytic. The chemical methods include precipitation, metal-
lic replacement, and ion exchange techniques. The electrolytic
methods, are more common in present processing plants/because they
are cleaner, usually require less operating labor, and permit
the reuse of the fixing bath after desilvering, with proper
chemical additions. The following factors affect the purity of
solutions to be reused and the purity of silver collected:
1. Agitation; Agitation is required so that new, silverladen
solution is always in contact with the cathodes. Insufficient
agitation results in a blackened or sulfided deposit on the
cathodes. A badly sulfided deposit fouls the cathodes and
results in a soft deposit»that may drop off and be lost in
the recovery cell.
2< Solution pH; Acid and alkaline fixing baths are quite differ-
ent, but pH changes in the range 7.0 to 10.0 have little effect.
In an acid solution, the plated silver tends to be white even
though the efficiency is low. This is due to the fact that
the sulfide produced goes out of solution in the form of
hydrogen sulfide gas. In alkaline solutions, the plated
silver sulfides easily, yet a slightly darkened silver plate
may still produce a high current efficiency. At a pH of 12,
the plated silver turns brown (sulfides) at any voltage.
3. Solution Filtration: The silver bearing solution is filte'red
to produce a smooth silver deposit on the cathodes. An
electrolytically neutral particle can be occluded in the
silver as it deposits on the cathode. When this occurs, the
silver deposit will form over the particle,producing a spot
146
-------
of sharp curvature. Current density will be higher at this
point: first, causing silver to deposit faster at the point
than on the rest 'of the cathode and finally, initiating the
sulfiding action which fouls the plate.
4. Current Density: The maximum current density depends on
agitation. The independent variable is voltage. If the
voltage is kept above a minimum allowable, value, an increase
in agitation may be used to obtain a higher current density.
5. Electrodes ; The material used in the construction of the
electrodes is important. Graphite is usually used for the
anode because it is resistant to corrosion and its electrical
resistance is low. Stainless steel is this common cathode
material.
6. Control of Silver Concentration: The solution from which
silver is being recovered must contain not less than O.S
grams per liter of silver. If the concentration is- less
than this, silver sulfide will form in the cell. Silver
sulfide is a black, finely divided material, which will
accumulate on the cathode and foul it. If it is not con-
trolled, the sulfide will precipitate from the solution.
In an acid solution, hydrogen sulfide gas will form. The
gas has an obnoxious odor (rotton eggs) and is toxic. If-
it is present, it must be removed by adequate ventilation.
The recirculation of fixer can reduce the chlorine demand dis-
charge from a photographic lab by as much as 90 1, while reducing
the BOD- from 60-90%. Electrolytic methods of silver removal
appear to bo the onlv nethods that allow this reduction* to take
place. Contiguous recirculation of fixers also increase silver
recovery efficiency from about a 701 maximum to a 95* maximum.
Bleach Recovery and
The bleaching reaction in the photographic process is:
Fe(CN)6'3 + Ag + Br" + Fe(CN)6" + AgBr
Overflow bleach solution is then treat ed so ^ to oxidize ferro-
cyanide to ferricyanide, the consumed halide is added and the
chemical concentrations adjusted to the desired replenisher
tank level.
•The most common technique of bleach "j^"*0? /J ^'documented. (38)
potassium persulfate. Persulfate regeneration is
The reaction is :
2 Fe(CN)-4 * S - 2 Fe(CN)6'3 a
147
-------
However, the addition of sulfate increases the specific gravity
of the bleach,which ultimately affects bleaching action. At
that point,the bleach'must be discarded in large volumes,im-
posing a very serious pollution problem.
Regeneration,via ozonation or electrolysis,produces no contam-
inant by-products and thus,there would be no need to discharge
any bleach. It would be continuously recirculated. This later
method allows for 951 reductions of complex cyanides discharged
to the environment.
Other inplant recoveries have not been found satisfactory for
the photographic processing industry, due to potential contaminr
ation, quality control, etc. The concentrations of the chemicals
found in the waste effluent of a typical photofinishing plant
are shown in Table F-l, page 149.
Table F-2 lists the amounts of chemicals, in pounds per day, that
are discharged by a typical photofinisher processing Ektachrome,
Kodacolor and Ektacolor products. Also listed in Table F-2, are
the amounts of the same chemicals that are discharged after the
installation of an in-plant treatment system. The system in-
cludes electrolytic silver recovery, ozone regeneration of ferri-
cyanide bleach and ozone waste treatment.
148
-------
TABLE iv-1
CONCENTRATION OF CHEMICALS IN INDUSTRIAL WASTES
EFFLUENT AT A TYPICAL PHOTOFINISHING PLANT
Ammonium Ion
Borax as B-O-
Bromide Ion
Carbonate
Ferrocyanate
Nitrate
Phosphate
Sulfate
Sulfite
Silver
Thiosulfate
Thiocyanate
Zinc
Acetate
Benzyl Alcolho
Color Developer CD-3
Formaldehyde
Hydroquinone
Elon
Hydroxylamine sulfate
Sodium Citrate
BODc (average-no mixing)
Flow Rate 1/min (peak load)
gpm (peak load)
TOTAL
MIXED EFFLUENT
Cmg/1)
50
268
70
145
120
140
15
75
140
3
500
1
8
400
100
57
260
10
11
17
59
695
450
120
DILUTE WASH
WATER ONLY
(mg/1)
1
3
1
1
1
1
1
4
4
4
1
,1
3
1
7-10
415
110
149
-------
TABLE F-2
TABLULATION OF CHEMICALS REMOVED BY TREATMENT AND REMAINING IN EFFLUENTS AT
A TYPICAL PHOTOFINISHER PROCESSING EKTACHROME, KODACOLOR AND EKTACOLOR PRODUCTS
Volume-gpm
Ammonium lon-lh/day
Borax lon-lb/day
Bromide lon-lb/day
M Carbonate lon-lb/day
-------
TABLE F-2
(continued)
1 Based on average processor operation of 6 hrs/day
2. A: Electrolytic Silver Recovery with Fixer Recirculation
B: Ferricyanide Bleach Regeneration with Ozone or by Electrolysis
j_, C: Chemical Destruction with Strong Oxidant such as Ozone
tn Chlorine, Peroxide or Permanganate.
D: Total of A, B § C
3 As percent of total amount present in industrial waste
-------
SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
/. Report No.
3. Accession Wo.
w
4. Title Treatment of Complex Cyanide for
Reuse or Disposal
7. Author(s)
5. Report Date August "1971
K !**%*•
. 0. 4 ^ 3- t,
H ,,
ff. Performing Organization
Report N&.
Hendrickson, Thomas N.
Daienault. Louis G.
9. Organization
10. Project No.
EPA, 12120 ERF
Berkey Film Processing of R. E.
260 Lunenburg Street
Fitchburg, Massachusetts 01420
11. Contract I Grant No.
112. Sponsoring organization Environmental..Rrote.ct iofnj
15. Supplementary Notes
Environmental Protection Agency Report No, EJ?A73~269, June 1973
i3. Type of Report and ."J,: '*
Period Coveted"- ft,'
' ' *""
stract complex cyanides (ferro-and ferricyanide) in industrial waste
water effluents impose a direct threat upon the environment. Methods to
recover or destroy these compounds were evaluated in laboratory studies.
The techniques tested include electrolysis, ozonation, chlorination and
heavy metal ion precipitation. The study was conducted to determine the
feasibility of using one or more of these methods to reduce the concen-
tration of ferricyanide in both concentrated (10,000 to 100,000 mg/1)
and dilute (10 to 100 mg/1) waste effluents.
Numerous analytical procedures were developed to enhance the
accuracy of sample analysis over the concentration range studied.
Ferrocyanide can be oxidized to ferricyanide in overflow photo-
graphic color process bleaches using either electrolysis or ozone and
the waste bleach recirculated for reuse in the process. Dilute concen-
trations of ferricyanide can be destroyed using ozone or chlorine under
proper conditions of temperature, pH and catalyst addition.
17a. Descriptors
*Analytical Techniques, *Chemical Precipitation, *Chlorination,
*0xidation, *0zone, *Electrolysis, chlorine, coagulation, Chemical
Waste, Laboratory Tests, Electro Chemistry, Flocculation, Heavy Metals,
Toxicity, Costs, Water Treatment, Biochemical Oxygen Demand, Chemical
Oxvgen Demand.
170/iyentiners
*Photofinishing Wastes, *Ferricyanide, Chemical Recovery, *Complex
Cyanides, Waste Recycle.
17c. COWRR Field & Group
18. Availability
19. Security Class.
(Report)
20. Security Class.
(Page)
21. No. of
Pages
22. Price
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
: WASHINGTON. D. C. 20240
Abstractor Louis G. Daignault IIa*titution Computerized Pollution Abatement Con
WRSIC 102 (REV. JUNE 1971)
SPO 9J3.26I
------- |