United States Office of Water EPA-821-R-97-Q03
Environmental Protection 4303 March 1997
Agency
F P A Preliminary Data Summary for the
Photoprocessing Industry
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for the
States Environmental Protection Agency
Office of Water
Engineering and Analysis Division
401 M Street, S.W,
Washington, D.C. 20460
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Table of Contents
List of Tables
ii
List of Figures ...,,,..,,,,,. ill
Acknowledgments [[[ iv
1. Executive Summary [[[ I
2. Introduction [[[ 3
3, Regulation of Photoprocessing Wastewaters .,,.,.......,..,,,,.,,,,, 5
3.1 Existing Effluent Guidelines , , 5
3,2 Local Limits 6
3.3 Regulatory Drivers and Barriers ....,,..,,..,...,,, 9
4. Photoprocessing Industry Profile ............11
4.] Photoprocessing Industry Overview .....,..,.,....,,,.,,.,,,.,. 11
4,2 Photoprocessing Volume and Revenue: Amateur Market 15
4,3 Production of Photosensitive Papers and Films and Photoprocessing Equipment ,. 19
4.4 New Technologies in Photography: Advanced Photo System and Digital Imaging
20
5, Description of Photoprocessing Operations 22
5.1 Process Descriptions . 22
5.2 Manual and Automated Systems 26
6, Water Use and Wastewater Sources and Characterization 29
6.1 Introduction , 29
6.2 Total Process Water Use , . 30
6.3 Developer ,.,...., 33
6.4 Bleach 36
6.5 Fix 39
6.6 Bleach-Fix . , , 39
6.7 Wash 41
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7.2 Source Reduction ., ,, ......................................... 44
7,3 Silver Recovery Considerations 46
7.4 Silver Recovery from Fixer Solution 48
7.5 Silver Recovery from Rinse Water . 52
7.6 Color Developer Reuse 54
7.7 Ferricyanide Recovery ."..... 54
7.8 Rinse Water Use: Reduction and Recycling 56
7.9 Implementation of Control Technologies , 58
7.10 Control and Treatment Issues , .59
8. Environmental Assessment ,... 61
8.1 Introduction 61
8.2 Pollutants found in Photoprocessmg Effluent 61
8.3 Toxic Weighting Factor Analysis 65
8.4 Loads Associated with Photoprocessing Effluent 66
8.5 Qualitative Enviror aental Impact of Photoprocessing Affluent Constituents ..... 68
8.6 Toxieity and Specu.iion of Silver 70
References 74
Appendix A. Calculation of Total United States Surface Area of Photographic Film and Paper
Developed for Amateur Market 77
List of Tables
Table 4.1 Number of Photoprocessing Facilities by Type for Phoenix, Arizona 12
Table 4.2 Number of Photoprocessing Establishments by SIC Code, 1996 13
Table 43 Photographic Use of Silver, 1993 14
Table 4.4 1994 Photoprocessing Total Exposures by Film Format 16
Table 4.5 1994 Photoprocessing Total Exposures by Film Type 16
Table 4,6 1993 and 1994 Market Share of Photoprocessing by Retail Channel 17
Table 4.7 1993 and 1994 Market Share of Photoprocessing by Retail Channel 18
Table 4.8 Characteristics of Arnateur Film Processing Labs 18
Table 6.1 Aqueous Wastes from Photoprocessing 30
Table 6.2 Estimated Wastestream Volumes for Various Photoprocessors ................. 32
Table 6.3 Photoprocessing Combined Wastestream Effluent Characteristics 33
Table 6.4 Color Developer Untreated Wastestream Pollutant Amounts .................. 35
Table 6.5 EDTA Bleach Untreated Wastestream Pollutant Amounts 37
Table 6.6 Ferricyanide Bleach Untreated Wastestream Pollutant Amounts .38
Table 6.7 Bleach-Fix Untreated Wastestream Pollutant Amounts 40
Table 6.8 Total United States Photoprocessing Amateur Market Waste Stream Quantity
Estimations for 1994 43
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Table ?. 1 Comparison of Silver Recovery and Management Systems .,.,,.,«,.,,.,,,,,,,, 4?
Table 7.2 Commercial Photoprocessor Environmental Controls, 1991 ,.,, 58
Table 7.3 Silver Concentrations After Silver Recovery (mg/L) ,, 59
Table 8,1 Possible Photoproeessing Wastewater Constituents .................... 62
Table 8.2 Pollutant Loadings for Direct Discharge Photoprocessing Facilities, 1995 63
Table 8.3 Pollutant Toxic Weighting Factors ......,,..,....,.66
Table 8,4 Estimated 1994 Loads and Toxic Loads for the Amateur Sector
of the Photoprocessing Industry , ., 67
Tabie 8,5 Solubility and Solubility Product of Some Silver Compounds/Complexes ........ 71
Table 8.6 Percent Mortality of Fathead Minnows Acutely Exposed to Concentrations of
Different Silver Compounds 72
List of Figures
Figure 5.1 Color Negative Film Process ,,.............,..,. 23
Figure 5.2 Color Negative Paper Process , , 24
Figure 5.3 Color Reversal Paper Process 24
Figure 5.4 Black-and-White Development Process ,...,..,,.....,... .26
in
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Acknowledgments
This Preliminary Data Summary was prepared by James Covlngton, Joseph Daly, Eric Strassler
and Kevin Tingley of the Engineering and Analysis Division of the U.S. Environmental
Protection Agency. Questions regarding this study be directed to Mr. Daly at (202) 260-
7186.
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1. Executive Summary
This Preliminary Data Summary for the Photoprocessing Point Source Category'
investigates the slate of the industry and its wastewaters in relation to the existing 1976
Guidelines, and attempts to evaluate the relevance of these guidelines in the current
photoprocessing operating and regulatory environment. The purpose of this document is to
provide technical support towards a decision of possible revision of the 1976 Photoproeessing
Effluent Limitations Guidelines and Standards, This study was conducted to meet the
obligations of the Environmental Protection Agency (EPA) under section 304(m) of the Clean
Water Act (CWA), in accordance with a consent decree in Natural Resources Defense Council
and Public Citizen, Jnc.v, Browner (D.D.C. 89-2980, January 31, 1992).
EPA promulgated an Interim Final Rule for the Photographic Category on July 14, 1976,
establishing best practicable control technology currently available (BPT) limitations for one
subcategory. the Photographic Processing Subcategory, at 40 CFR Part 459, Subpart A,
Facilities falling within this photoprocessing subcd ^?gory use silver haiide-sensitized
photographic materials to produce continuous tone black-and-white or color negatives, positive
transparencies, and prints for delivery to external customers. Commercial photoprocessing
services are available through a variety of retail channels, including drugstores, discount/mass
merchandisers, camera stores, mail order, and stand-alone mini labs, Photoprocessing also plays
a major role in the businesses of portrait studios and motion picture production. About 100,000
establishment were identified in 1996 in Dun & Bradslreel under the commercial
photoprocessing standard industrial classification (SIC) codes. Significant photoprocessing also
occur as an ancillary activity within the health care profession at hospitals, dentists", doctors',
and veterinary offices, and at noncommercial facilities such as schools, police departments, and
to serve heavy construction and transportation needs. Combining all types of facilities* it is
estimated that photoprocessing operations occur at 350,000 to 500,000 locations in the United
States.
Data concerning the amount of film processed was available only for the commercial
sector, which is estimated to represent 44 percent of total photoprocessing volume. For the
commercial sector, it is reported that in 1994, 715,5 million rolls of film were processed,
resulting in 17,58 billion exposures and generating revenue of over $5.5 billion. Over 92 percent
of the film processed was 35mm format, and almost 95 percent was processed as color prints.
Based on the commercial data, it is estimated that in 1994,296 million square feet of film, and .
4,120 million square feet of paper, were processed in the United States, The estimated water use
by the commercial sector of this industry in 1994 is 2,250 million gallons. The major wastewater
constituents of concern, with 1994 estimated commercial sector loadings, include (2.8
million Ibs.), ammonia (3 million Ibs,), silver (190 thousand Ibs.), thiosulfate, and cyanide.
Several technologies are available and employed to either treat the wastestreams, or as common
in this industry, recover the chemicals and metals in the wastewater for resale or reuse. Recovery
of silver is almost always practiced to some extent, both due to the value of silver and to comply
1
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with discharge regulations. Several silver recovery technologies are available, and the
technology of choice depends on installation and recovery requirements. The two most
common methods are metallic replacement with the use of chemical recovery cartridges, and
electrolytic recovery.
None of the hundreds of thousands of photoprocessing establishments have discharge
permits that refer to the existing guidelines found at 40 CFR Part 459 Subpart A. The
facilities are not covered directly by the guidelines is that only BPT regulations have been
published, which cover direct dischargers. However, all except for a few large photoprocessors
discharge to publicly owned treatment works (POTW), which requires pretreatment standards for
existing sources (PSES) or pretreatment standards for new sources (PSNS) for coverage by the
pretreatment standards. For the small percent of facilities that are direct dischargers, there is a
production requirement that the facility process 1600 square feet per day or more of
photosensitive film and paper. As a result of these factors the current guidelines are not
applicable to virtually any photoprocessing facilities.
With the lack of any applicable national pretreatment standards for photoprcccssing
wastestreams, "local limits" as developed by the receiving POTW are the normal means of
controlling photoprocessing discharges. The local limits are normally numeric and
concentration-based, and frequently the only pollutant monitored in the indirect discharge permit
is silver. The predominance of local limits to control photoprocessing discharges leads to a)
mainly concentration based limits, b) variability from municipality to municipality on allowable
discharge concentration, and c) possible changes in discharge limits based on changing water
quality criteria or water body loadings goals, EPA has always encouraged the use of production-
based rather than concentration-based limits for the control of photoprocessing wastewaters to
promote water conservation.
There are questions concerning the environmental fate and effects of silver from
photoprocessing wastes, Man}' of the stringent local limits are based on the highly dissociated
and toxic silver nitrate. While silver nitrate is used in the production of photographic film and
paper, it is not a characteristic pollutant of photoprocessing wastewaters. Rather, silver in
photoprocessing wastewaters is characteristically in the form of silver thiosulfate complex, which
has been shown to be about 20,000 to 40,000 times less toxic, on a concentration basis, to acutely
exposed fathead minnows. The local limits may be overly stringent with regard to concentration
of silver discharged, while lax on total mass of silver or other pollutants, due to lack of technical
expertise and resources available at the local level. Further study is required to accurately predict
the fate and toxicity of silver from photoprocessing wastestreams after entering a POTW.
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2. Introduction
The purpose of this Preliminary Data Summary for the Photoprocessing Industry Is to
provide information for determining whether the existing technology-based effluent guidelines at
40 CFR Part 459 should be revised. This study describes the size and demographics of the
industry, photoprocessing operations and the typical wastewaters generated, as well as the
technologies available to treat these wastewaters. Total national pollutant loadings are estimated,
and resulting environmental effects are qualitatively postulated. This information is presented
against the backdrop of the existing technology-based guidelines and the utility of these
guidelines to the permit writer.
Policy discussions and rankings with other industries for selection of guidelines revision
are not subjects of this study. However, the material herein is a source of information for such
future discussions and rankings.
This study was conducted to meet EPA's obligations under section 304\m) of the Clean
Water Act, as implemented through a consent decree in Natural Resources Defense Council et al,
v. Browner ( D.D.C. 89-2980, January 31, 1992)(the "Consent Decree"). Pursuant to the decree,
the Agency's latest biennial plan for developing new and revised effluent guidelines was
published on October 7, 1996 (61 FR 52582)., in which schedules were established for reviewing
existing effluent guidelines and developing new and/or revised effluent guidelines for several
industry categories. One of the industries selected for review of existing effluent guidelines was
the Photographic Processing Point Source Category (40 CFR 459).
Specifics of the existing guidelines are presented in Chapter 3. This discussion explains
that the existing guidelines are not relevant to the photoprocessing industry, due to the lack of
pretrcatment standards in an industry where most facilities discharge indirectly to a publicly
owned treatment works. Chapter 3 then presents how, in lieu of applicable guidelines, local
limits may be applied. Issues affecting the environmental performance of photoprocessors are
also outlined.
A profile of the industry is given in Chapter 4, detailing what is considered a
"pholoprocessor," where these photoprocessors exist, and their relative market share. For certain
segments of the industry, facilities are primarily engaged in photoprocessing, and these segments
are identified by their Standard Industrial Classification (SIC) codes. Photoprocessing also
occurs as an ancillary activity in a myriad of other public and private institutions as well. These
institutions are identified, and data on market size and photoprocessing volume is presented.
Chapter 5 describes the basic photoprocessing operations. This leads into the discussion
of wastewater sources and pollutant characterization in Chapter 6. Here, information and
are presented in an attempt to define the characteristic pollutants of photoprocessing
wastestreams. and the volume of these wastestreams. Since no has been gathered recently
by the EPA to support the values presented, the characteristic pollutant list may not be accurate.
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and pollutant loadings based on flow concentration can only be estimated. Further
study, possibly including sampling of photoprocessing wastewaters, would be necessary to obtain
more precise loadings values.
Chapter 7 the control and treatment technologies available to photoprocessors.
Silver recovery and management systems are explained, as well as other practicable recover}'
methods such as color developer reuse ferricyanide recovery. The economic motive as well
as regulator}' compliance motive for installing and such and recovery
systems is discussed.
Chapter 8 attempts to provide a qualitative of the effect of discharging
photoprocessing effluent on the environment. This is by identifying the pollutants in the
wastewaters, estimating their discharge quantities, and toxic-weighted factors to these
pollutants to arrive at toxic-weighted pound-equivalents. This analysis is followed with a caveat
concerning the dependence of the toxicity of silver to the speciation of the silver, which dictates
the oxidation state, solubility in water, ionic dissociation in water, of the silver atom or
molecule.
Again, the goal of this Preliminary Data Summary' is to and put into perspective
the readily available information concerning the photoprocessing industry. This study
achieves its purpose in supplying information relevant to the existing guidelines in the current
photoprocessing operating and regulatory environment, to aid in the decision of whether or not to
revise the photoprocessing effluent guidelines.
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3, Regulation of Photoprocessing Wastewaters
3.1 Existing Effluent Guidelines
EPA promulgated an Interim Final Rule for the Photographic Category on July 14, 1976
(41 FR 29078). The rule established practicable control technology currently available
(BPT) limitations for one subcategory. the Photographic Processing Subcategory at 40 CFR Part
459, Subpart A. The Agency determined that further of photographic
processors was unnecessary due to the similarity of pollutants discharged across the industry and
that the pollutant loadings per unit of production among the studied facilities were in a relatively
narrow range,
Subpart A covers "point source resulting from the development or printing of
paper, prints, slides negatives, enlargements, movie film, other sensitized materials except
that facilities processing 150 sq, meters (1600 sq, feet) per day or are not covered," The
scope includes both commercial military' facilities. Thus these regulations apply to facilities
that directly discharge pollutants, but facilities that indirectly discharge to sewer systems are not
covered.
EPA identified the major of wastewater from the industry as photo-processing
solution overflows and wash waters. The rule listed the known significant pollutants as pH, total
suspended solids (TSS), biological oxygen (BOD), chemical oxygen (COD),
cyanide and silver in various forms.
The technology for the limitations consisted of electrolytic silver recovery
bleach regeneration, In-plant measures to reduce silver and cyanide were included in the
technology basis. EPA also considered basing limitations on biological treatment but did not do
so because of estimated cost impacts.
The BPT limitations at §459.12 are as follows:
Parameter
silver
cyanide
pH
Daily Maximum
30-day
average
(kg per 1 ,000 m2 of product)
0.14
0.18
Within of 6,0 to 9,0
0,07
0.09
...
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While most BPT regulations also set limitations for the conventional BOD and TSS,
the rule-making notice stated that by controlling silver and cyanide, BOD and TSS are effectively
co-treated, as well as COD,
The limitations are production based, based on the surface area of film or paper
processed. The EPA determined that concentration based limitations where not appropriate for
this industry because such limitations encouraged high water use and discouraged water
conservation.
In the July 14, 1976 notice, the Agency stated its intent to publish a proposed rule
covering best available technology economically achievable (BAT), new source performance
standards (NSPS), and pretreatment standards for new sources (PSNS) for the industry. Such
regulations would affect facilities that indirectly discharge wastewaters. It also stated it may
propose regulations for the exempted smaller facilities. However, these regulations were never
promulgated.1
EPA considered issuing effluent guidelines for other subcategories of the photographic
industry, but no regulations were issued. For four subcategories, the Agency found very small
quantities of toxic pollutants in the raw waste load: Diazo Aqueous, Diazo Solvent, Photographic
Chemicals, and Thermal Products. The Silver Halide subcategory also had small quantities of
toxics in the raw waste loads, and most of the facilities were-direct dischargers, with NPDES
permits that required effective treatment(EPA 1981b)
It has been approximated that there are 350,000 to 500,000 facilities throughout the
United States which process photographic films and papers.fDufficy, Silver CMP) However, no
permits are issued under 40 CFR 459 Subpart A. This is due to the fact that almost all
photoprocessing facilities are indirect dischargers (discharge to a POTW), but only BPT has been
published which covers direct discharges. Or if they are direct dischargers, their daily production
may fall under the limit of 1600 square feet. Therefore, the existing regulations are not of utility
to the permit writers.
3.2 Local Limits
In lieu of national pretreatment standards for the Photographic Processing Subcategory,
POTWs may use local limits and the general and specific prohibitions established under the
General Pretreatment Regulations (40 CFR Part 403). EPA developed the General Pretreatment
Regulations under the Clean Water Act (CWA) to prevent the discharge to POTWs of pollutants
'The Development Document contains chapters on BAT, NSPS and PSNS limits,
although the regulations were never issued.
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which will interfere with, through2, or which are otherwise incompatible with the POTW
(CWA § 307 (b)(l)). POTWs must establish, develop and specific limits to implement
the general and specific EPA prohibitions. The specific limits developed by the POTWs are
commonly referred to as "local limits" arc enforceable pretreatment standards under the
Clean Water Act.(§ 403.5(d))
Because, by definition within the of 40 CFR Part 403, pollutant Pass Through or
Interference results in a violation of the POTWs NPDES permit, the of the POTWs
NPDES permit generally serves as a in appropriate local limits to prevent
Pass Through or Interference. Accordingly, the effluent limits, quality and
protection conditions, toxicity requirements, and operation maintenance (O&M) objectives
found in a POTWs NPDES permit generally the framework within which the POTW
must operate in order to prevent Pass Through and/or Interference.
In determining the pollutants to be regulated in standards,
another type of pass through analysis is performed. This analysis is on the pollutants
determined to be present in the wastewater from the industry and is not restricted to
only those pollutants contained in the POTWs NPDES permits.
The General Pretreatment Regulations also recognize that local limits which are more
stringent than those set forth in the regulations may be by or local law.
In addition, POTWs may choose to impose local limits which regulate categorical industries
more stringently than under an applicable categorical standard, in which case the local limits will
supersede the categorical as the applicable pretreatment standards,
3 "Pass Through" is defined as "a discharge which exits the POTW into waters of the
United Slates in quantities or concentrations which, alone or in conjunction with a discharge or
discharges from other sources, is a of a violation of any requirement of the POTW's
NPDES permit (including an increase in the magnitude or duration of a violation)," 40 CFR
4033 (n). "Interference" is defined as "a discharge which, alone or in conjunction with a
discharge or discharges from sources, both:
(1) inhibits or disrupt the POTW, its treatment or operations, or its sludge
processes, use or disposal;
(2) therefore is a of a violation of any requirement of the POTW's NPDES permit
(including increase in the magnitude or duration of a violation) or of the prevention of sludge
use or disposal in compliance with the following provisions and regulations or permits
issued thereunder (or more stringent or local regulations): Section 405 of the Clean Water
Act, the Solid Waste Disposal Act (SWDA) (including Title II, more commonly referred to as the
Resource Conservation and Recovery Act (RCRA), and including regulations contained in
any sludge management pursuant to Subtitle D of the SWDA), the Clean Air
Act, the Toxic Substances Control Act, the Marine Protection, Research and Sanctuaries
Act." 40 CFR 403.3 (i).
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While local limit development is required of POTW's under the Clean Water Act and the
General Pretreatment Regulations, neither the federal statute nor the regulations mandate the type
of local limits to be established. Instead, as EPA has recognized in its rulemakings under the
General Pretreatment Regulations, the establishment of local limits is a matter primarily of local
concern which should be left to the discretion of the POTW,(see 46 FR 9494, 9415, Jan. 28,
1981, and 52 FR 1586, 1593, Jan. 14,1987) To help with local limit development, EPA has
issued the "Guidance Manual on the Development and Implementation of Local Discharge
Limitations Under the Pretreatment Program.'5(EPA 1987) Through this guidance, EPA has
indicated that POTWs are to use site-specific data to identify pollutants of concern which might
reasonably be expected to be discharged in quantities sufficient to cause POTW or environmental
problems. Once the pollutants of concern and the sources discharging these pollutants have been
identified, the POTW must select the most effective technical approach for the development of
its local limits.
While numericjimjig have traditionally been used for local (non-categorical) limits, they
ar- no' required by federal statute or regulation. One alternative approach for local limit
development identified by EPA in its guidance is the use of industrial user management practice
plans. Through this approach, a POTW can require dischargers to develop and implement
management practice plans covering their handling of chemicals and wastes. Once incorporated
into local laws and regulations, these plans become an enforceable pretreatment requirement.
The majority of the photoprocessing facilities are small in size (having fewer than ten
employees), and typically discharge less than 1,000 gallons of wastewater per day. For the most
part, these photoprocessing indirect dischargers do not meet the definition of a "Significant
Industrial User" (SIU) in the General Pretreatrnent Regulations because no pretreatment
standards have been incorporated into 40 CFR Part 459 and their discharge of process
wastewater is less than 25,000 gallons per day and/or 5% of the hydraulic or organic capacity of
the POTW.(§ 403.3 (t)) While individual photoprocessors can be designated an SIU by a
POTW, the burden of demonstrating that an individual photoprocessor "has a reasonable
potential for adversely affecting the POTW's operation or for violating any pretreatment standard
or requirement" is high.
3.2.1 Local Limits on Silver
Silver was identified as a "priority pollutant" in the Clean Water Act of 1977 (CWA 307
(a)(l)), following an earlier listing of silver as a drinking water contaminant by the United States
Public Health Service. EPA issued water quality criteria for silver in 1980.(EPA 1980) In 1987,
amendments to the CWA required EPA and the states to establish water quality standards and to
set, where necessary, water quality based effluent limitations for priority pollutants, including
silver, which were causing water quality problems (CWA 304(1)). As a result, POTWs are
beginning to receive monitoring requirements and/or numerical limitations for silver in their
NPDES permits. At the same time, POTWs are finding, through their headworks loading
analyses, discharger surveys and other analyses, that much of the silver is being discharged by
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numerous small sources such as domestic, institutional and commercial sources which are more
difficult to control than photoprocessors. When taken as a whole, photoprocessors have been
found to be a major source of silver. In most cases, silver is the only pollutant in
photoprocessing wastewaters which is subject to local limits.
Since virtually all photoprocessors are not covered by national categorical standards, local
limits are the normal route to control the pollutants discharged by photoprocessors. In an attempt
to provide both photographic processors and POTWs with a cost-effective alternative to numeric
limits and monitoring, the Silver Council, which is an industry association, and the Association
of Metropolitan Sewerage Agencies (AMSA) have developed a "Code of Management Practice
for Silver Dischargers" (Silver CMP). The Silver CMP provides recommendations on
technology, equipment and management practices for controlling silver discharges to POTWs,
The practices recommended vary with the size of the photoprocessor, defined by flow volume of
silver-rich solution and wash water. Through the use of its alternative compliance mechanisms,
the Silver CMP encourages use of pollution prevention technologies, such as water conservation
methods.
The Silver CMP encourages the development of industry-wide performance standards for
silver recovery systems that maximize silver recovery and minimize its release to the
environment. The recommended practices are defined by a minimum recovery of silver from
silver-rich processing solutions (e.g., 90 percent) and alternative combinations of recovery
methods that would achieve those recovery rates, Those developing the Silver CMP estimate
that compliance with the recommendations would reduce silver loadings to POTWs by 25 to 50
percent. Three municipalities have implemented the Silver CMP; Albuquerque, NM; Colorado
Springs, CO; and New York , NY. Over a dozen other municipalities are planning to implement
or have expressed an interest in implementing the recommendations of the Silver CMP,
However, data have not been provided to EPA to demonstrate the reductions in silver and other
pollutants discharged upon implementation of the Silver CMP. Currently (1996), the Silver
Council and AMSA propose to jointly conduct, with EPA, a 3-year program to implement and
measure the effectiveness of the Silver CMP in 5 to 7 cities of various sizes throughout the
United States.
The existence and acceptance of the Silver CMP, and the results of the Silver CMP
demonstration project, will not necessarily have an effect on any future effluent guidelines
development for the photoprocessing industry. In part, this is due to the different means of the
two pollutant discharge control ends; single pollutant versus multi-pollutant, and local
evaluation and acceptance versus national rule.
3,3 Regulatory Drivers and Barriers
A study completed by the EPA in 1994 investigated the factors influencing the
environmental performance of the photoprocessing industry. The goal of the study was to
determine what factors act as incentives to improve environmental performance (drivers) and
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what factors act as barriers or disincentives to improving environmental performance. Some of
the issues raised in the report are outlined below. For the details of the analysis the report should
be reviewed.(EPA 1994)
The report notes that a number of factors contribute to the low local limits concentration
for silver that are imposed in many locations, First, the federal water quality standard is based
on the toxicity of ionic silver. The federal concentration limit for silver in aqueous effluent is 5
parts of silver per million parts of water. Again, this limit is based on tests performed with silver
nitrate in laboratory test water, which yields ionic silver. However, silver nitrate is not a
characteristic pollutant of photoprocessing wastewater. Rather, silver thiosulfate is the
characteristic form of silver, and silver thiosulfate has been shown, on a concentration basis, to
be thousands of times less acutely toxic to fathead minnows than silver nitrate.{Duffiey)
Currently there are no reliable analytical procedures to test for ionic silver, so that for the time
being monitoring and compliance are necessarily based on total recoverable silver. Also,
pretreatment permit limits are practically always expressed on a concentration rather than mass
basis, which discourages aci>; Ming water saving measures such as "washless" technologies or
otherwise reducing water use.
The report also notes that the regulation of silver-bearing wastes under the Resource
Conservation and Recover}' Act (RCRA) increases transportation costs of some photoprocessing
wastewaters to central treatment facilities for silver recover)1, and increases the burden of storing
wastewaters and shipment off-site for centralized waste treatment. On the other hand,
photoprocessors can avoid RCRA regulation by treating and discharging their wastes in
compliance with Clean Water Act requirements, These factors, reportedly, discourage the
recycling of silver, discourage the efficient treatment of photoprocessing wastewaters in
centralized treatment facilities, and encourage discharge of these wastewaters to POTWs. It is
claimed that removal of silver from the RCRA Toxicity Characteristic list would eliminate most
of the added burden, encouraging increased recycling of silver and centralized treatment of
photoprocessing wastewaters.
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4. Photoprocessing Industry Profile
4,1 Photoprocessing Industry Overview
The photoprocessing industry, for the purpose of this study, consists of photographic
processors using silver halide-sensitized photographic materials to produce continuous-tone
black-and-white or color negatives, positive transparencies, and prints for deliver}' to external
customers. The main industrial segments to which this study applies are as follows.
"Photofinishing Laboratories" (SIC 7384), consists of facilities primarily engaged in film
developing and print processing for the trade or the general public. Facilities primarily engaged
in photography for the general public are classified as "Photographic Studios, Portrait" (SIC
7221), Included in this group are portrait photographers and school, home, and transient
photographers. Establishments primarily engaged in providing commercial photography services
for advertising agencies, publishers, and other business are classified in "Commercial
Photography** (SIC 7335), and those providing commercial art or graphic design services for
advertising agencies, publishers, and other business are classified as "Commercial Art and
Graphic Design" ('SIC 7336), The processing of motion picture film falls under "Services Allied
to Motion Picture Production" (SIC 7819).3
In the industries mentioned above, a significant portion of total revenue is in general
derived through the processing of photographic films, slides, and prints. However, as in SIC
7336 and 7819, photoprocessing may occur along with other significant revenue-generating
activities. Photoprocessing operations also occur in a myriad of other public and private
institutions, such as dental offices, hospitals, police departments, industrial X-ray services, and
schools. As an example. Table 4,1 shows the number of photoprocessing facilities by type for
Phoenix, Arizona, In the health care and noncommercial sectors, the processing of photographic
films and papers is an ancillary activity, whereas in the commercial sector it is the main activity.
vfhe terms "photoprocessing," "photoftnishitig.," and "photo developing" are
.angcable. For consistency, the term ""photoprocessing" is used throughout this report.
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Table 4.1 Number of Photoprocessing Facilities by Type for Phoenix, Arizona
Facility type
Health Care
Hospitals*
Dentists
Doctors
Veterinarians
Chiropractors
Commercial
Minilabs
Photofinishers
Prof. Labs
Motion Picture
Microfilm
Graphic arts
Noncommercial
Schools
Police Dept.
Heavy Construction,
Transportation
Fabricated Prods,
Finance/insurance/
real estate
Jewelry/silverware/plated
ware
Number of facilities by
Small
(1 to 19)
14
1,422
91 S*
278
515
184
0
129
1
12
7S3
§
4
269
14
18
0
47
Medium
(20 to 49)
I
16
122
9
6
0
5
9
0
3
101
§
3
57
2
5
0
1
size (in number of employees)
Large
(50 to 499) (More than
61
1
47
2
§
0
5
2
0
1
4?
5
18
58
44
42
22
§
500)
32
0
2
0
0
0
0
0
0
0
3
1
11
4
7
10
10
0
* Does not include university, college, or public hospitals,
h Include offices of podiatrists, osteopaths, and 10% of all medical doctor offices.
Source: WEF 1994
12
-------
Combining all types of facilities, it is estimated that photoproeessrag operations occur at
350,000 to 500,000 locations in the United States.(Dufficy. Silver CMP) The number of
establishments identified under the commercial photoprocessing SIC codes mentioned above are
listed in Table 4,2 below.
Table 4.2 Number of Photoprocessing Establishments by SIC Code, 1996
Standard
Industrial
Classification
(SIC)
7384
7221
7335
7336
7819
SIC Description
Photofmishing Laboratories
Photographic Studios, Portrait
Commercial Photography
Commercial Art and
Graphic Design
Services Allied to Motion
Picture Production
Total:
Number of Establishments
As Primary
Business
10.430
27,607
14,845
31,476
7,656
92,014
As Primary or
Secondary
Business
13,171
32.184
18,414
37,264
9,187
110,220
Source: Dun & Bradstreet
Photographic films and paper are used mainly for the following reasons: a) to diagnose
medical problems, b) to diagnose structural defects of buildings, bridges, and roads, c) document,
record, and transfer information,, and d) record personal events and preserve memories. The
market for photographic services and supplies can be divided into three major segments:
» Medical applications
» Graphic arts, and
» Amateur photography, served by commercial sector
Medical users include large hospitals and diagnostic clinics, as well as doctors' and
veterinarians' offices. The largest single user in the medical market is the Veterans
Administration. The graphic arts industry consists mainly of printers who are partially involved
in photoprocessing. These businesses serve an industrial market through published documents
and advertising. In most cases, photography represents a small part of their business and does
not present their most pressing environmental concern. The amateur photography sector includes
13
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all amateur photographic processing, whether at minilabs, wholesale laboratories, or mail
order processing labs. These individuals taking pictures mainly to preserve memories.
There are the variations the of the three major market segments—medical
imaging, graphic arts, and amateur photography. These requirements affect the constraints on
process and product improvements:
• The medical market is concerned with rapid and accurate diagnosis, and therefore
requires both quality speed, as well as longevity of the image,
• The graphic arts market requires high quality pictures, but is relatively
unconcerned with processing speed.
» The amateur market tends to be more concerned with speed in processing, but
demands increasingly higher quality.
In lieu of revenue and photoprocessing volume data, the relative size of these segments
can be inferred from information of silver consumption. Data on the allocation of silver for
various photographic uses for 1993 are shown in Table 4.3 below.4
Table 4,3 Photographic Use of Silver, 1993
Photographic End-Use
Amateur Picture Taking
(Commercial)
Medical, Excluding Dental
Graphic Arts
Industrial and Dental
Silver Demand; U.S., Japan,
and Western Europe
(MiIlion_Troj^Ounces)_
82
46
41
17
Percent of Total
Photographic Silver
Demand
44%
25%
22%
9%
Source: WSS 1993
4It has been reported that in 1995 the Photographic Industry consumed 29 percent of total
worldwide silver fabrication, for the production of photographic film and paper,(WSS 1996}
14
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4.2 Photoprocessing Volume and Revenue: Amateur Market
Information on photoprocessing volume and revenue is presented below. These
data exclude health and noncommercial photoprocessing because were not available for
these segments, As shown in Table 4.3, by correspondence to silver use it is that the
amateur market accounts for 44 percent of total photoprocessing volume,
In 1994, the total number of rolls 715.5 million, resulting in 17.58 billion
exposures. The predominant film format of choice 35mm, making up 92,1 percent,
color prints were the most popular film type, capturing 94,7 percent, of exposures processed in
1994. Tables 4.4 and 4.5 show the of the various film formats and film types.(PMA
1995)
Original prints are normally 3 V* by 5 inches or 4 by 6 inches, and they can be either
single prints or twin prints. Having plateaued at 36 percent from 1991-93,4" by 6" print market
share jumped 4.5 points in 1994, accounting for 40.6 percent of prints. Twin prints, following a
2.4 point climb in 1992, and gaining 2.7 points in 1993, experience stable market in 1994,
with 46.6 percent. Over three-quarters of photofinishing dollars came from original prints,
while reprints and accounted for 14 percent.(PMA 1995)
This amateur or commercial photoprocessing occurred through various retail channels,
such as drugstores, stand-alone mini-labs, and mail-order processors. The breakdown of market
within each of the retail channels is shown in of roll in Table 4.6, and in terms
of dollar share in Table 4.7. Years 1993 and 1994 are provided to show the industry trends. As
Table 4,7 shows, consumers spent $5.5 billion on photoprocessing in 1994. In 1993, stand-alone
mini-labs had the highest revenue spot, but were overtaken by drugstores in 1994. The
discount/mass merchandiser channel out gains in all other channels, with its dollar
share up 2.9 percentage points. Photoprocessors compete based on price, quality, convenience,
and speed of processing. The trends in demand for photographs are somewhat cyclic
and follow the economic cycles, with a minimum customer below which demand will not
fall. When people become more price sensitive, as in a recession, they are more willing to
sacrifice convenience and for lower prices. (EPA 1994) The characteristics of the various
types of labs are summarized in Table 4.8,
15
-------
Table 4.4 1994 Photoprocessing Total Exposures by Film Format
Film
Format
35mm
110/126
Disc
Other
Total
Source: JPMA
Number of Exposures
(Millions)
16,190
1,195
123
70
17,580
1995
Percent of
Eiposures
92.1%
6.8%
0.7%
0,45%
100%
Table 4.5 1994 Preprocessing Total Exposures by Film Type
Film
Format
Color print
Slide
Black &
White
Total
Number of Exposures
(Millions)
16,648
615
316
17,580
Percent of
Exposures
94,7%
3.5%
1.8%
100%
Source: PMA 1995
-------
Table 4.6 1993 and 1994 Market Share of Photoprocessing by Retail Channel
—Roll Share-
Retail
Channel
Drug Store
Stand-Alone
MInitab
Camera Store
Discount/Mass
Merchandiser
Supermarket
Mail Order
Other
Total
Number of Rolls(MiIIioits)
1993
183,8
104,3
56.0
176,9
98,0
53.1
22.0
694,0
1994
188,9
98,4
52,2
202.6
96,2
54.8
22,5
715,5
Percent Share
1993
26.5%
15,0%
§,1%
25,5%
14,1%
7.7%
3.2%
100,0%
1994
26,4%
13.8%
7.3%
28.3%
13,4%
7.7%
3.1%
100.0%
Source: PMA W5
17
-------
Table 4.7 1993 and 1994 Market Share of Photoprocessing by Retail Channel
—Dollar Share* —
Retail
Channel
Drug Store
Stand-Alone
Mini-Lab
Camera Store
Discount/Mass
Merchandiser
Supermarket
Mail Order
Other
Total
Retail Dollars (Millions)
1993
$1,356
$1,398
$734
$871
$649
$289
$177
$5,475
1994
$1,359
$1,296
$699
$1,039
$653
$312
$180
$5,538
Percent Share
1993
24,8%
25.5%
13.4%
15,9%
11.9%
5.3%
3.2%
100,0%
1994
24.5%
23.4%
12.6%
18.8%
11.8%
5.6%
3.2%
100.0%
Source: PMA 1905
Table 4.8 Characteristics of Amateur Film Processing Labs
Lab Type
Minilabs
Wholesale Labs
{Drug Stores,
Grocer}' Stores)
Mail Order Labs
Price
Two to Three Times
Higher than Others
Medium
Low
Quality
Lower Others
Equal to Minilabs
High
Processing Speed
One Hour
Two to Three
Days
One Week
Source: EPA 1994
Consolidation is occurring in the industry, both from a manufacturing perspective and
from a processing perspective. Some smaller manufactures have been absorbed by the large
market players. In addition, some manufactures are now involved in processing. Kodak owns
approximately half of Qualex Incorporated, which is the largest single photo processing
IS
-------
company. Fuji and Konica have also purchased photo processing labs. As a result, the
largest manufactures are now also full or partial owners of the three largest photoprocessing
chains.(EPA 1994)
Compared to large labs, smaller labs have a limited capital base, and hence tend to be
somewhat less sophisticated. Industry representatives point out that the trend toward
concentration among photoprocessing labs over the past several years is largely a result of
restrictive environmental standards. They claim that compliance has become prohibitively
expensive for small operations to achieve,
While stand-alone mini-labs are listed as a separate retail channel, mini-labs are also
found in all other retail channels as well. Industry data distinguish between retail mini-labs,
regardless of retail channel, versus the larger wholesale, captive, and mail order labs. The data
show that the number of minilabs has grown rapidly over the past decade, from approximately
800 in 1981 to 18,900 in 1994. In 1994. minilabs were located in 3,100 camera stores, 6,124
stand-alone minilab outlets, and 5,153 mass-retail stores. This indicates a significant increase in
the number of mini-labs in mass-retail stores. The number of mini-labs in other types of stores
declined slightly over the same period. In 1994 these mini-labs processed 214.2 million rolls,
accounting for 30 percent of the total 715.5 million rolls, while the wholesale, captive, and mail
order tabs processed the remaining 70 percent, The mini-labs also proved more profitable,
receiving 43.8 percent, or $2,426 million, of the total $5,538 million in revenue and wholesale,
captive, and mail orders made the remaining 56.2 percent or $3,112 miHicm.(PMA 1995) Thus,
while mini-labs processed just 30 percent of the rolls, they collected 43.8 percent of the total
revenues.
4.3 Production of Photosensitive Papers and Films and Photoprocessing Equipment
The photographic equipment and supplies industry is not covered in this study. This
category is mentioned here because of the interface with photoprocessors, and to explicitly
describe what is and is not covered in this study.
Facilities classified under SIC 3861, "Photographic Equipment and Supplies," produces a
wide variety of products for the photoprocessing industry, including photosensitive plates, film,
paper, and cloth, photographic chemicals, and photoprocessing equipment. While the
photoimaging industry is highly diffuse on the processor side, it is highly concentrated on the
manufacturing side. A Dun & Bradstreet count in 1996 indicated 974 establishments under SIC
3861 as a priinary business, and 1,254 establishments under SIC 3861 as a primary or secondary
business. Manufacturers with significant operations in the United States include:
« Eastman Kodak Company
» Polaroid Corporation
• 3M Corporation
-------
•
» Hford (owned by International Paper)
• Artitec Image (also owned by International Paper),
Kodak is by far the U.S. manufacturer. Polaroid Corporation is the second largest but
their primary film product is Instant film.(EPA 1994)
As a whole these more revenue through the of photographic
nondurable goods of film, paper, and photoprocessing supplies, than through the sale of
processing equipment. The 1992 Census of Manufacturers data shows that the value of
shipments of supplies of film and was $4,545 million, but that of the equipment
was only $547 mil!ion.(EPA 1994)
Manufacturers and processors have a close relationship in this industry. Processors rely
heavily on manufacturers for compliance assistance and innovations to address environmental
~nd regulator)-' concerns. Manufacturing is driven in part by the demands placed upon the
processors, both by regulators and by the end consumer. Manufacturers supply processing
systems which include both equipment supplies to customers. Photoprocessors do not have
to purchase supplies from the manufacturer that supplied the equipment, but many,
especially the smaller minilabs, often do. AJ1 of the manufacturers have support systems to assist
the processors with operations environmental compliance. Such systems include
instructional seminars, facility compliance evaluations, compliance kits.(EPA 1994)
4.4 New Technologies in Photography: AdYanced Photo System and Digital Imaging
Two new technologies are introduced because they may affect the volume of
photographic film and paper processed in the future: Advanced Photo System (APS) versus the
relative growth of digital imaging (DI). APS an evolution of silver halide technology
while DI, utilizing electronic means of image capture storage, represents a threat.
The APS system was launched in April, 1996, on basis of a new film format with a
number of features to improve and simplify photography. The most significant
improvements will be the choice of three different print layouts, and the ability to select frames
for printing from an initially produced sheet of miniature prints as opposed to awkward
negatives. The new film cartridge is "dropped*" in for simpler loading, and features such as
a disk to store various types of film information. For example, this information can be by
the cameras to adjust for lighting conditions, and allows the film to be removed mid-real and
reloaded later on without accidental double exposure. The reverse side of the film has a
transparent magnetic layer which can record digital information to be used by the
photoprocessing equipment. Although each frame of film will capture the full image entering
through the lens, the selection of different print layouts allows the processor to magnify a suitable
20
-------
of the to produce with a of aspect rations. The film itself is from a
stronger and thinner and is with more emulsions.
In terms of photoprocessing volume the most important question is whether the APS will
encourage more prints to be of ease of frame selection from the miniature preview
prints and wide range of print layout options, or less prints due to selection from the
miniature previews.
Market penetratioa by digital is perceived as a to silver halide-based
photography, but this emerging technology two significant quality problems. These are the
inferior and expensive image capture and the low quality of the output medium, DI would
to a decrease in film and paper photoprocessing volume because the film is replaced by a
semiconductor chip known as a charge-coupled device. The photographs are then downloaded
onto computer on which they can be and on or ink-jet paper. The
quality of the image is directly proportional to the number of photocell elements in the charge-
coupled device, which ranges from 250,000 in amateur cameras to over 6 million in the
professional market. By contrast, the 35 mm negative contains approximately 10 billion
silver-halide crystals. As of 1996 cameras introduced for the amateur market cost in the region
of $ 1,000 and produce of up to 756 by 504 dots or pixels, making them suitable for
amateur use on a computer but unacceptable for prints. However, much more
expensive digital cameras have become fairly popular with photojoumalists, who can now
photographs across the world via mobile phone computer links. The most significant impact
of digital photography on silver-halide photoprocessing volume may come from the medical X-
ray sector. Some hospitals are investing heavily in sophisticated computer equipment to replace
the conventional X-ray light box.(WSS 1996)
The effects of Dl on silver halide-based photoprocessing volume are beginning to be
seen. While the production of X-ray film marginally in 1995 for both domestic and
export markets, manufacturers reported that growth has curtailed by digital imaging. In the
graphics art sector, photographic paper consumption down 2 to 3 percent, reportedly because
of the impact of digital imaging, The of DJ are, of course, speculative,
However, due to the simplicity and lower cost inherent in silver-halide technology, it appears that
this traditional technology will not be overran by DI in many of the major photoprocessing
markets, such as photography.(WSS 1996)
21
-------
5, Description of Pfaotoprocesslng Operations
5.1 Process Descriptions
The processing of photographic film and paper requires the use of a number of chemicals
to develop and produce finished photographic goods. The waste streams generated vary widely
according to the type and volume of processing, Photoprocessing is dominated by color print
film, prints, and slides, with only about 10 percent of the market involving black-and-white
processing. Because color processing usually represents a greater production volume of the
operations at a given location, it usually generates a larger waste stream volume. An increasing
portion of the color market is being taken by mini-labs, which are automated machines that oc-
cupy little space. These machines are the ones used by the popular one-hour developing centers.
The waste stream volume from most one-hour developing centers has been greatly reduced,
because most centers have converted to "washless" or "plumbingless" processing, which does not
use a conventional wash t ,cle.(EPA 1991a)
5.1.1 Color Processing
Film and paper used for color photography consist of three separate layers of
photosensitive emulsion with intermediate layers. The emulsion layers are coated on clear film
base or on paper, and each layer is sensitive to either red, green, or blue light due to the presence
of selective dyes in the emulsion, Intermediate layers filter out other wavelengths, so that the
silver halide salts in each photosensitive layer are exposed only to light of the specific color. A
colorless dye-forming coupler is present along with the silver halide crystals in each emulsion
layer. When processed in a color-developing solution, an image of "developed silver" is formed
in each layer. The exposed silver halide crystals are reduced to metallic silver, while
simultaneously producing oxidized developer molecules. The oxidized developer reacts with the
dye-forming coupler to produce a dye which is complementary in color to the light to which the
emulsion layer is sensitive. The intensity of the dye formed in a particular portion of the image is
dependent on the quantity of oxidized developer, which is in turn proportional to the extent of
exposure in that area,
A bleach bath renders the color image visible by converting the black metallic silver
image back to a silver halide. AH of the silver on the film, whether exposed or not, can then be
dissolved and removed in the fixer bath. The dye is retained in each layer of the film so that a
negative (complementary) color image remains. Some processes combine the bleach and fix
processes in a single solution, termed bleach-fix or "blix." It is a common practice to introduce
the film into a stabilizer bath after the fixer solution to equilibrate the emulsion and increase the
stability of the dye image to light. A schematic diagram of the color negative film process is
shown in Figure 5,1.(EPA 1991a)
22
-------
Figure 5. i Color Negative Film Process
Repterattt
Rim-*.
ftjpterfsh Rinse Water Replenish Rinse WaK»r PteptefiWi Water Vapor
Color Bteaeh
Develop "*" (Fame EDTA) H
Wi
1
sts
i
»- Wash
I
J». F«
i '
Spent Rirtsewater I
F
i Beach i
fij=j=a
i
i
P
j" "Sw
LfP
J Waste
H»
W«h
-*- Stabilize •
•*. Dry
Spent Rinsewater Waste
4 4
Stlvec
Ftecovery
1
T """"""""" """ " -«•
f
Positive color prints can be made from the film negative recorded by the camera by
exposing color paper or other suitable print medium to light passed through the developed film,
The print medium, which contains the same combination of colorsensitive emulsion layers as
does the film, is then processed through a similar sequence of solutions to obtain the final print,
as illustrated by Figure S.2.(EPA 1991a)
For color slides, a positive color image is produced directly on the film by reversal
processing. The exposed color film is first subjected to black-and-white processing to produce a
negative image consisting only of metallic silver, After washing, the film is immersed in a
reversal bath that renders the remaining silver salts developable, The film is then processed in a
color developer that reduces the remaining silver salts and produces a positive dye image, Then
a sequence of bleach, fixer, and wash steps produces the final color transparency. Color prints
can be made directly from positive slides by a similar reversal process. Figure 5,3 is a schematic
diagram depicting both slide and reversal print operations.(EPA 199la)
Cinemagraphic film processing is similar to processing of color print or slide film. In
commercial operations, a large number of copies are made from one film. A print or "negative
image" film is used for the original exposure and then used to make film copies (much as print
film is used to make prints). Amateur film processing, which usually results in only one copy of
the film, uses film much like slide film that is exposed and processed, producing the positive
image on the originally-exposed film.
23
-------
Figure 5.2 Color Negative Paper Process
Rfcfl •
~ iiiai«
Spent Krasnodar
i. '
•F« !
] Regeneration j
t-, . J
Product
Figure 5,3 Color Reversal Paper Process
Reptentsh
n—+. D»ve
k»
Batch
Overftow
Reptenish
Beach-fix
** f*nfc
r— »•
1
1
f*"***"™*"™*"™"™
Edta
f
Replenish
i
*» Stop
Bateh
Water
-». Wash
Spent HnMMMMr
Water
>. Wart —
Spent Rin&ewater
Replenish
StabAze
Batch
Overflow
^ tMot
Develop
Batch
Overflow
Water
Spray
** W*§h
*
Spent Sn&swal&r
T
^ Wash
1
Speot RJnsswater
Water Vapor
t
*• Diy
1
—*
Product
Waste
24
-------
5,1,2 Black-and-white Processing
The photosensitive medium for black-and-white processing is an emulsion
composed of a dispersion of fine silver halide crystals in a matrix of gelatin. This emulsion is
applied in a layer approximately 1/1000 of an inch thick on a supporting material, either paper or
clear plastic film. Brief exposure to small quantities of light produces a chemical change in the
silver halide crystals, which allows the silver ions in the crystals to be converted to
metallic silver at a rate in crystals. By focusing the light through the
camera lens, the pattern of crystals to the image which light is
reflected. At this point, the exposed silver halide crystals are termed "developable," When the
film is subsequently immersed in the developing solution,, composed of an alkaline solution of
organic reducing agents, the exposed silver crystals are reduced to metallic silver. The
silver is dark in color produces a negative image. The most commonly developing
agents are metoi (p-methylaminophenol sulfate) hydroquinone (p-dihydroxybenzene or
1,4-dihydroxybenzene).
The chemistry of development is complex. For example, hydroquinone in ordinary
sulfite-containing developers (sodium suifite is to most developers as a preservative) is
oxidized to a semi-qutnone free radical, and then reacts with suifite to form mono- and
di-sulfonates, These reaction products may be isolated along with quinone, sodium sulfate
(Na2SO4), and many other compounds with the other ingredients, e.g., metal, sodium
carbonate, and potassium bromide.
If kept in the developer bath, even the imexposed silver halide crystals can be converted
to metallic silver by the developer solution. To prevent this, the action of the developer is
arrested by transferring the film to a bath. The bath is a weakly acidic solution (usually
acetic acid) which neutralizes any of the alkaline developer carried over on the surface of the film
or in the wetted gelatin layer. Following the stop bath, the film is immersed in a fixer solution
that solubilizes and removes the remaining silver salts, rendering the on the film
permanent Fixer solution adhering to the film must be removed in a final rinse step.
The film now a negative of the which the recorded. A
positive print is by exposing a photosensitive of paper to the formed when
light is passed through the negative of the film. The paper is then processed through a
similar set of operations (i.e., developer, bath, fixer, and rinse). A for
black-and-white processing that to both film and is shown in Figure 5.4.
25
-------
Figure 5,4 Black-and- White Development Process
0»wtepsr stop isft
Selufen Solution
MAM
Water
Finished
. Rta or
PHrt
Wattewatsr
Fteoovared
Slivw
As more film is processed, the concentration of various reaction products gradually builds
up in the developer solution. Silver and bromide ions removed from the developed film
accumulate in the fixer solution, and the acidic stop bath is gradually neutralized as the quantity
of alkaline developer carried over increases. At point, these solutions become unusable
and must be discarded. The final rinse is usually conducted in a continuous flow of fresh running
water. As a result, only small amounts of silver and other fixer compounds can he detected in the
spent rinse water waste stream.
Black-and-white reversal film processing, used to create- a positive black-and-white image
directly on the film, requires two development with an intermediate bleach step. Bleach
solution for black-and-white processing contains sodium dichromate. Spent bleach is considered
a hazardous waste because of its chrome content.
5,2 Manual and Automated Systems
5.2.1 Manual Systems
Manual systems include tray and processing. These are often used for low volume
production such as black and white processing, enlargements, or other services that do not
require, or are not amenable to, cost-effective automation. While manual processing wastes can
be significantly reduced, this represents such a small volume for most businesses that the overall
waste reduction impact may not be significant.
26
-------
The tray method allows processing small quantities of film and papers with minimum
chemical consumption. Sheets of film or paper are placed on the bottom of the shallow tray
containing solution. The tray is then rocked back and forth manually to ensure that adequate
fresh solution contacts the emulsion surfaces. The sheets are removed, drained, and transferred
to the next processing bath. The duration of each step in the process is timed according to a
prescribed schedule. Once the processing is completed, the solutions are returned to storage
containers for reuse. With proper storage, solutions can be reused until chemically exhausted, as
indicated by test strips,
Tanks are used for processing large quantities of film and paper sheets. This method is
usually limited to sheets no larger than 8 inches by 10 inches. The sheets are suspended
vertically in the tank from hangers which maintain a lateral separation. The solution level in
each tank covers the entire sheet. The solution is agitated by gentle vertical movement of the
hangers. When not in use, the tanks should be covered to keep foreign materials out of the
processing solutions and to minimize evaporation and oxidation. Oxidation of the developer
solution can be farther reduced by using a tight-fitting "floating lid" of buoyant plastic and
limiting the amount of time the solution is in use.
In addition, strips of camera film are often processed in tanks. The flexible film strip is
inserted in a spiral slot in a reel which fits into a cylindrical tank. Inserting the film into the reel
and loading the reel into the lank must be carried out in the dark. Then, in a lighted area, the
solutions are added, one at a time, through a light-tight port in the; cap. Following a prescribed
schedule, the tank is drained and refilled with the subsequent solutions. During the final wash
step, the cap can be removed to permit easier washing of the reels in the stream of water.fEPA
1991a)
5.2.2 Automated Systems
Automated systems differ primarily by the means used to transfer the film through the
sequence of solutions. The major types of transport systems are discussed in the following
paragraphs.(EP A 1991 a)
Dip and Dunk, The films, in the form of sheets, strips, or short looped lengths, are
clipped to hangers supported on a rack. The rack is removed from the processing machine to
simplify loading. Once replaced in the processor, the rack holding the film is advanced by a gear
chain mechanism. As the rack moves into position, it is lowered into the solution tanks so that
the film is completely immersed. Agitation is provided by vertical movement of the rack to
ensure continuous contact of the emulsion surface with fresh solution. As the rack continues its
advance, it is automatically raised from one bath, allowed to drain, and lowered into the
subsequent solution or wash tank. Finally the rack moves the film through a forced-air drying
unit.
2?
-------
Nip Rollers, A series of small cylindrical wringers transports film or paper through the
sequence of processing solutions. These rollers provide for both vertical and horizontal
movement, and this method is suitable for either strips or sheets. Initially a leader strip or sheet
is threaded and pulled through to a rewind station situated after the final dryer unit. Once the
processing is started, movement of the film or paper through the solutions is continuous,
Belt Systems* The film or paper to be processed is supported on a belt which is conveyed
through the sequence of solutions using guides and rollers. Where desirable, the material being
processed can be transferred from one belt to another to allow for a greater variety of strips,
Initially a leader strip or sheet is treated and pulled through to a rewind station situated after the
final dryer unit. Ctoce the processing is started, movement of the film or paper through the
solutions is continuous,
High-Speed Roller, Long strips of film are mounted on a flexible support which is
attached to a series of racks, A system of guides and immersed rollers conveys the film through
the solutions to wash tanks, Before starting up the : 'cessor, a leader is threaded through the
racks. Generally, the leader is attached to the end of the film and is always left in place between
processing cycles to simplify start-up. Lengths of film to be processed, or tailing leaders, can be
attached with tape or staples. High linear speeds are possible, resulting in greater throughput
than can be obtained with other types of processors.
28
-------
6. Water Use and Wastewater Sources and Characterization
6,1 Introduction
As exposed photosensitive film or paper is processed to develop the image, it is passed
through a series of chemical baths and washes, as described In Chapter 5, In brief, the exposed
film is first subjected to a reducing agent in the developer to form the latent image. Then, if the
film being developed is color film, bleach is used to oxidize the black metallic silver image back
to an invisible halide, so as to reveal the colors and so that the silver can be removed in the fix
bath. Following, in the fix, ammonium or sodium thiosulfate solution is used to fix the silver or
color image to the film base. In the ideal case, the fix solution removes 100 percent of the silver
processed in color work, and the 60 to 80 percent of the silver in a black-and-white picture that
does not contribute to the image as black elemental silver. Finally, one or more washes remove
any remaining chemicals and unexposed silver. As film is passed through the developer, bleach,
and fix, these solutions are replenished with ne-v solutions to maintain their effectiveness, The
rate of replenishment determines the particular wastestrcam amount and the concentration of
chemicals in the wastestrcam.
Table 6.1 introduces the photoprocessing waste streams, their major constituents, and
associated environmental concerns. Following are sections which detail the quantity and
pollutant parameters of the major photoprocessing wastestreams: developer, bleach, fix, wash,
and stabilizer,
29
-------
Table 6.1 Aqueous Wastes from Pbotoprocesslng
Solution
Prehardeners, Hardeners, and
Pre baths
Developers
Stop Baths
Ferricyanide Bleaches
Dichromate Bleaches
Clearing Baths
Fixing Baths
Neutral Izers
Stabilizers
Sound-track Fixer or
Redeveloper
Monobaths
Constituents
Organic Chemicals
Chromium Compounds
Organic Chemicals
Organic Chemicals
Ferricyanide
Organic Chemicals
Chromium Compounds
Organic Chemicals
Organic Chemicals
Silver
Thiocyanate
Ammonium Compounds
Sulfur Compounds
Organic Chemicals
Phosphate
Organic Chemical
Ammonium Compounds
Organic Chemicals
Environmental Concern
Oxygen Demand
Toxic Metals
Oxygen Demand
Oxygen Demand
Toxic Chemical
Oxygen Demand
Toxic Metals
Oxygen Demand
Oxygen Deu.und
Toxic Metals
Toxic Chemicals
Ammonia
Possible H2S Generation
Oxygen Demand
Bio-Nutrients
Oxygen Demand
Ammonia
Oxygen Demand
In addition, photoprocessing solutions may be acidic or alkaline.
Source: I" PA 1 99 la
6.2 Total Process Water Use
Process water used in photoprocessing consists of a) film and paper wash water, b)
solution make-up water, and c) area and equipment wash water. The largest single process water
use is for the washing of film and paper between the various process steps and for final rinse.
The function of the wash step is to clean the photographic emulsion of constituents which must
be removed for successful completion of certain processing steps. Solution make-up water is
blended with the chemicals used in the processing solutions, which are generally supplied to the
processor in the form of liquid concentrates or powdered chemical formulations, to provide
processing solutions of working strength. Waterbome wastes are generated when these solutions
are discarded after becoming exhausted or when allowed to overflow during replenishment, as is
-------
the common practice. Area and equipment wash water is used for the washing and rinsing of
solution mixing utensils, storage tanks, and processing machines for area washdown.
Information on. overall process water use was obtained for a 1981 EPA guidance
document for the control of water pollution in the photoprocessing industry .(EPA 198 la) The
average total process water use for the 70 plants from which data were obtained was found to be
3.85 gallons per square foot of film and/or paper processed, and ranged from a low of 0,220
gal/ft2 to a high of 14 gal/ft2. It was observed that more than 95 percent of the process water use
in each facility was for film and paper washing. The analysis also indicated that overall process
water use was not correlated to production capacity; both small and large facilities showed a
similar range.
The process volumes of silver-rich and silver-poor solutions have been estimated for a.
variety of small, medium, and large photoprocessors, as shown in Table 6.2. In this table, silver-
rich solutions include fix, bleach-fix, washless stabilizer, and low-flow washwaters. Silver-poor
solutions include developers, bleaches, stop-baths, stabilizers used after washes, and washwaters.
It is estimated, that small and medium size photographic processors represent about 90%
of the total number of photographic processing facilities. These small and medium size facilities
include: small hospitals, doctors', dentists', veterinarians* and chiropractors* offices,
neighborhood clinics, schools, portrait studios, minilabs, custom labs, professional processing
labs, small microfilm facilities, printers, motion picture processors, and a large number of
municipal, state, and federal facilities where some in-house photographic processing is done.
Small facilities typically discharge less than 1,000 GPD of process wastewater and produce on
average less than 2 GPD of silver-rich solutions. Medium size facilities typically discharge 1,000
to 10,000 GPD of process wastewater and produce on average 2 to 20 GPD of silver-rich
processing solutions. Large photographic processors, representing about 9 percent of all
photographic processing facilities, typically discharge 10,000 to 25,000 GPD of process waste-
water and produce on average more than 20 GPD of silver-rich processing solution. Significant
Industrial Users (SIU) are facilities using more than 25,000 gallons per day (GPD) of process
wastewater and having the ability to adversely impact the POTW operations or causing
pass-through of a regulated chemical, SIlis represent about 1 percent of the total number of
facilities that process photographic materials. Photographic processing facilities that could be
Sills include the major motion picture film processors, and a few very large hospitals, X-ray
diagnostic clinics, printers and photofinishers.(Silver CMP)
Photoprocessing combined wastestream characteristics are summarized in Table 6.3,
3!
-------
Table 6,2 Estimated Wastestream Volumes for Various Photoprocessors
Facility Type - Size
Dental Office - Small
Dental Office - Medium
Dental Office - Large
Hospital - Small
Hospital - Medium
Hospital - Large
Medical Professional - Small
Medical Professional - Medium
Medical Professional - Large
Microfilm - Small
Microfilm - Medium
Microfilm - Large
Printer/Graphic Art - Small
Printer/Graphic Art - Medium
Printer/Graphic Art - Large
Mini lab - Washless - All Sizes
Minilah - Washwater - All Sizes
Photofmisher/Professional - Small
Photofinisher/Professional - Medium
Photofmisher/Professional - Large
Motion Picture - Smal!
Motion Picture - Medium
Motion Picture - Large
Police Dept, - Smal!
Police Dept, - Medium
Police Dept. - Large
School - Small
School - Medium
School - Large
Silver-Rich1
Solution VolMmejfGPD)
0,1
0.2
0,4
20
40
80
0,2
1.0
5
0.1
0,3
50
1
2
20
23
1.0
10
100
265
25
50
2,000
0.2
0.4
2
1
5
10
Sliver-Poor2
Solution Volume (GPD)
5
10
20
2,600
5,200
10,400
100
500
1,000
15
75
3,750
225
450
4,500
21
100
1,325
13,250
33,000
LOGO
2,000
S0J3GD
25
50
250
125
650
1,250
' Silver-Rich solutions include fix, bleach-fix washless stabilizer, and tow flow washwaters.
1 Silver-poor solutions include developers, bleaches, stop-baths, stabilizers used after washes, and washwaters.
Source; Silver CMP
32
-------
Table 63 Photoprocessing Combined Wastestrearo Effluent Characteristics
Pollutant Parameter
Temperature
pH
Biochemical Oxygen Demand (5-Day)
Chemical Oxygen Demand
Total Dissolved Solids
Total Suspended Solids
Ammonia Nitogen (NH3-N)
Total Kjeldahl Nitrogen (TKN)
Thiosulfate
Sulfaies
Silver (after silver recover)-')
Iron
Zinc
Concentration Range (mg/L)
Conventional Process
80-!10°F
6,5 - 9,5
200 -
400 -
300 -
<5-50
20 - 300
30 - 350
100-1,000
50 - 250
-------
The other major components of a developer solution consist of a pH buffer (typically
carbonate) to maintain pH in the range of 9 to 11, a calcium sequestrant (typically
ethylenediaminetetraaeetic acid (EDTA) or a metaphosphate), and an antioxidant (typically
sulfite or a hydroxylamine). These compounds are present in concentrations generally less i
percent by weight, in the 1 to 10 g/L range. Developer solutions contain more than 90 percent
water by weight.
Because developing agents oxidize on exposure to air, the developing solutions are
unstable and degrade with time. Thus the reducing agents are depleted by both the
photoprocessing operation and by exposure to air. The oxidized ingredients must be replaced to
maintain consistent results. As new solution is added to the developer container, an equivalent
volume is discharged from the processor. This spent developer solution contains more than 90
percent water, with a few grams per liter inorganic salts (carbonate and sulfate) and portions of
developing and sulfonated developing agents. Results of sampling of untreated color developer
waste streams, performed in 1977, are displayed in Table 6,4.
34
-------
Table 6.4 Color Developer Untreated Wastestream Pollutant Amounts
Pollutant Parameter
Total Organic Carbon
Cadmium
Chromium*
Silver
Iron
Lead
Total Suspended Solids
Total Dissolved Solids
Plant Code
6208
7781
7781
6208
7781
7781
6208
7781
7781
6208
7781
7781
6208
7781
7781
620S
7781
7781
6208
7781
7781
6208
7781
7781
Concentration (mg/L)
6,450
15,000
16,700
0.34
86
1.1
0,09
0,10
0.26
1.4
1.5
0.49
2,9
2.4
3.7
0.25
7.5
0.09
9.3
II
10
40,400
78,400
52,600
Amount (lbs/1000 ft2)
-
.
.
4,59 x Iff5
3.5 xlQ-3
7.3 xlO-3
1.2x ID'3
4,1 x 10-'
UxlO-5
1.9 x SO"4
6.1 x IG'1
3.3 x iO's
-
.
.
-
.
.
,
.
_
-
-
-
Source: EPA 198!a
* Since this sampling episode in 1 977, it is reported that the amount ofchromiuro in film emulsion has
been substantially reduced, and is currently used only in the Kodachrome process. (EPA 1994)
35
-------
6,4
Bleach replenishment rates vary from 5 and 30 mL/sq ft for color processes,(WEF 1994,
EPA 198!a) Bleach solution is not used in black-and-white processing. Bleach solutions
contain 10 to 30 percent iron-EDTA complex, typically the ammonium salt of ferric EDTA or
ferric propylenediaminetetraacetic acid (PDTA). Ammonium salts are used because they are
more soluble and transport through the gelatin layers faster than sodium or potassium salts.
Thus, lower concentrations can be used. The bleach also contains 5 to 10 percent acetic acid and
an acetate salt to buffer the pH in the 4 to 6 range, 5 to 10 percent bromide salt, and a small
amount (less than I percent) of sodium or potassium nitrate, which is used to prevent corrosion of
the processing tanks. As it oxidizes the metallic silver, the ferric complex is reduced to ferrous
salt and must be regenerated or replaced. As this solution is replenished, the overflow will
contain 65 to 85 percent water, ferrous and ferric EDTA or PDTA complexes, and inorganic salts
such as bromide, nitrate, and ammonium ion.
For some cinemagraphic films, a bleach containing ferricyanide is used, and could result
in appreciable concentrations of ferri- and ferrocyanide in the waste streams. Most
cinemagraphic processors recover up to 99 percent of the ferrlcyanide for reuse. If not recovered,
ferrocyanide can eventually be converted to free cyanide by sunlight in the presence of oxygen
over a period of several weeks, and is therefore a waste constituent of concern.(EPA 199 la)
Results of sampling of raw EDTA bleach wastestreams, performed in 1977, are displayed
in Table 6.5. and those of raw ferricyanide bleach wastestreams are displayed in Table 6.6,
36
-------
Table 6.5 EDTA Bleach Untreated Wastestream Pollutant Amounts
Pollutant
Parameter
Total Organic Carbon
Cadmium
Chromium*
Silver
Iron
Lead
Total Suspended
Solids
Total Dissolved
Solids
Cyanide
Plant Code
2714
4550
7781
2714
4550
7781
2714
4550
7781
2714
4550
7781
2714
4550
7781
2714
4550
778!
2714
4550
7781
2714
4550
778!
2714
4550
7781
Concentration
(mgfL)
43,600
42,150
23,200
<0.02
0,4
0,09
2.0
12
3,6
268
233
36
16,282
12,102
7.722
<0,02
2,0
0,14
62
112
86
253,000
227,600
206,800
•
3,1
-
Amount
(lto/1000 ft2)
«
.
.
< 23x10'*
Mxlff4
3,9 xlO"6
2,3 xlO"4
4.2 x IQ'3
l.SxlO"1
0.03
0,08
0,016
_
.
_
„
.
_
™
-
-
_
_
_
»
1. IX Iff3
Source: EPA 198 la
* Since this sampling episode in 1977, it is reported that the amount of chromium used in film emulsion has
been substantially reduced, and is currently only in the Kodachrome process, (EPA 1994}
37
-------
Table 6.6 Ferrkvanide Bleach Untreated Wastestream Pollutant Amounts
Pollutant
Parameter
Total Organic Carbon
Cadmium
Chromium*
Silver
Iron
Lead
Total Suspended
Solids
Total Dissolved
Solids
Cyanide
Plant Code
2714
4550
6208
2714
4550
6208
2714
4550
6208
2714
4550
6208
2714
4550
6208
2714
4550
6208
2714
4550
6208
2714
4550
6208
2714
4550
6208
Concentration
13,000
30,750
8,300
<0.02
0.40
<0,02
4.2
1.3
0.09
4.1
8
0.38
5,562
11,118
7,560
0.22
2.0
0.42
30
101
24
128,000
304,750
98,800
15,800
50,200
14,750
Amount
ft2)
-
-
-
-------
45 Fix
Fix replenishment rates range from 15 to 100 mL/sq ft for film and processes, Fix
solutions contain 65 to 85 percent water, 10 to 30 percent ammonium thiosulfate, and 5 to 10
percent sulfite salt that as an antioxidant. Fix solutions are not to oxygen, and
exposure to air slowly thiosulfate to elemental sulfur. As the fix solution is used for
processing, it removes the silver from the film or paper in the form of the soluble silver
thiosulfate complex, and a solution should contain between 1,000 and 5,000 mg/L
silver. As the fix is replenished, the overflow is generally collected for silver recovery.(WEF
1994}
6,6 Bleach-Fix
As discussed in Chapter 5, the bleach fix solutions necessary for color processing are
sometimes combined to form the bleach-fix or Mix solution. Bleach-fix replenishment vary
from 5 to 30 mL/sq ft for color processes.(WEF 1994, EPA 198 la) The composition of the
wastestream is that of the bleach and fix solutions, as above, combined. Results of
sampling of raw bleach-fix wastestreams, performed in 1977, are displayed in Table 6,7.
39
-------
Table 6.7 Bleach-Fa Untreated Wastestream Pollutant Amounts
Pollutant Parameter
Total Organic Carbon
Cadmium.
Chromium
Silver
Iron
Lead
1 ota! Suspended Solids
Plant Code
2714
4550
4550
7781
7781
2714
4550
4550
778!
7781
2714
4550
4550
7781
7781
2714
4550
4550
7781
7781
2714
4550
4550
7781
7781
2714
4550
4550
7781
7781
2714
4550
4550
7781
7781
Concentration (mg/L)
43,600
33,900
47,150
41,600
50,750
<0,02
<0,06
1.0
80
0.24
0.6
5.7
6
1.3
2.9
2,109
2,025
1,582
4,356
2,1 11
4.884
7,718
8,023
5,310
13,236
0.5
1.0
1,4
22
0.7
112
56
82
124
51
Amount (lbs/1000 ft2)
„
.
.
.
.
<1.2x 1G=A
<7.5x 10-"
6.6 x 10~5
5.1 x 10-
1.6x 10-*
3.6x10'"
7.1 x 10-4
3.9x 10"'
8.2 x 10-'
2.0 x 10"'
0.12
0.25
0.10
0,28
0.14
*
.
.
_
.
»
»
.
.
-
*»
.
.
„
,
40
-------
Pollutant Parameter
Total Dissolved Solids
Biological Oxygen Demand
Nitrogen (As Ammonia)
Plant Code
2714
4550
4550
7781
7781
2714
4550
4550
7781
7781
2714
4550
4550
7781
7781
Concentration (rag/L)
205,000
195,400
209,400
292,000
306,200
-
13,300
28,000
-
-
~
38,000
30,000
,
-
Amount (lte/1000 ft1)
«.
,
,
.
.
*>
.
.
-
-
**
.
>
,
.
Source; EPA «Ia
6,7 Wash
Wash waters are replenished at 200 to 1000 mL/sq ft for each wash tank of the process.
After the fix or bleach-fix, the films or papers are immersed in a series of wash tanks lo remove
the silver thiosulfate and other residual chemicals from the gelatin layers. Therefore, the wash
waters typically contain the same pollutants as the fix or bleach-fix, but at lower concentrations.
6.8 Stabilizers
Stabilizers or final rinse solutions are 99 percent water except for washiess color
processes. These solutions contain a wetting agent to prevent water spotting during drying. In
some color film stabilizers, a small amount of formaldehyde (less than 0.2 percent) is present to
harden the gelatin layer or stabilize an image dye. Stabilizers are replenished at rates between 10
and 30 mL/sq ft.
In one amateur film and paper process, the water washes are replaced by a replenished
stabilizer. This stabilizer contains citrate salts and polyvinylpyrolidone to complex or react with
the residual chemicals and provide image stability. As this solution is replenished, the overflow-
is collected for silver recovery, While the image stability is not as good as that provided by water
washing, it is reportedly good enough for most amateur photographers.(WEF 1994)
41
-------
6.9 Total National Photoprocessing Discharge Flow
Chapter 4 provides for the total rolls and produced, and
provides Information on the size and quantities of prints produced from the resulting negatives.
From these values, and the surface per film reported in the literature, it is possible to
estimate the total square feet of film and paper across the United for the amateur
(commercial) market. Values for the health and noncommercial photoprocessing
segments are not available, but it is that this amateur accounts for 44 percent of
the total photoprocessing volume. This derives from the fact that the amateur market
accounts for 44 percent of total photographic silver use. Silver use in the other market segments,
including medical, dental, and industrial, was shown previously in Table 4.3.
The detailed calculations, in the Appendix, the total 1994 film
processed to be 296 million feel, and the total paper processed to be 4,115 million square
feet. From these results of the total film and feet processed, the total flow
requirements for each process can be calculated the process flow demands for the various
waste streams as reported in sections 6,2 through 6,7 above. The are presented in Table
6,8 below,
42
-------
Table 6,8 Total United States Photoprocessing Amateur MarketWaste Stream Quantity
Estimations for 1994
Waste Stream
Total Process2
Developer1
Bleach1
Fix3
Bleach-Fix3
Stabilizer1
Wash1
Flow
Demands
3.85 gal/ft2
pgper
5 - 30 ml/ft2
film
15 -100 mL/ft2
5 - 30 mL/ft2
IS -100 mL/ft2
5 - 30 mL/ft2
10 -30 mL/ft
200- 1000
niL/ff-
Total U.S. Flow1
(Millions of Gallons/Year)
Film
.
4.50
,
-
.
-
,
Paper
-
19.0
-
-
-
.
-
Total Process Calculated as: Developer + Bleach •+ Fix
•f Stabilizer + Three Wash Tanks
Film and Paper
17,000
.
20.4
67.0
20.4
23.3
699/tank
2,250
i . When given a flow demand range, the total U.S. flow is calculated using the average flow value.
2, Flow demand from reference EPA i981a
3, Flow demands from reference WEF 1W4
In Table 6.8 above, the total U.S. flow has been calculated In two ways: the single total
process flow as determined from the EPA 1981 a reference, or the addition of the process
wastestreams as determined from the WEF 1994 reference. The EPA 198 la reference flow
demand leads to a total flow about 7 Vi times greater than the flow calculated from the WEF
1994 flow demands. Here, the EPA 198la value is taken to be outdated and to overstate water
use, and the WEF 1994 values are taken to be more realistic for the current operating
environment.
Two assumptions are implicit In the value of 2,250 million gallons/year as an estimate of
the total U.S. photoprocessing flow requirements for the amateur market. One is that the flow
demands which are not split for paper and film are applicable to both paper and film processing.
The other is that other wastewaters not mentioned, such as equipment wash waters, are
negligible.
43
-------
7. Control aid Treatment Tech oologies
7,1 Introduction
This chapter on control and treatment technologies recommended for photoprocessing
operations begins with a discussion of source reduction methods. Particularly in the
photoprocessing industry, certain management practices have proven highly effective In reducing
waste while requiring almost no investment or loss in product quality. Following the discussion
on source reduction, control and treatment technologies are presented. In addition to the
environmental benefit associated with reducing pollutant discharge loadings, the photoprocessor
is often at an economic advantage to install and maintain these technologies due to the payback
from the recycled or recovered resources, especially with regard to the recovery of silver,
Photoprc^esstng equipment manufacturers and the photoprocessors have a close working
relationship. Manufacturers supply processing systems which include both equipment and
supplies to customers. Photoprocessors do not have to purchase chemical supplies from the same
manufacturer that supplied the processing equipment, but many, especially the smaller mini-labs,
often do. Processors rely heavily on manufacturers for compliance assistance and innovations to
address environmental and regulatory concerns, Manufacturing is driven in part by the demands
placed upon the processors, both by regulators and by the end consumer. For these all of
the manufacturers have support systems to assist the processors with operations and
environmental compliance. Such systems include instructional seminars, facility compliance
evaluations, and compliance kits. By keeping abreast of changes and Implementing applicable
technology Improvements, companies can often take advantage of the dual benefits of reduced
waste generation and a more cost efficient operation.
7.2 Source Reduction
The following management practices are applicable to all sizes of photoprocessing
operations to minimize waste generation. They require almost no investment and have proven
effective in many businesses:
* Control inventories of processing chemicals so they are used before their expiration
dates.
« Make up processing solutions only in quantities needed to meet realistic processing
volumes.
* Use floating lids or balls on developer solution tanks to prevent loss of potency
through oxidation or evaporation.
» Improve quality control for all processes to prevent unnecessary discharges.(EPA
199 la)
Squeegees can be used in all manual and some automated processing systems to wipe
excess liquid from the film and paper, reducing chemical carryover from one process bath to the
44
-------
next by 75 percent or more,(Kodak 1990) Several types are available, including wiper blades, air
squeegees, vacuum squeegees, wringer sling squeegees, and rotary buffer squeegees. Belt
turnarounds with soft-core rollers can be used for slow speed transport of wide films, but
squeegees cannot be used on rack and tank, basket, or drum processors. Minimizing chemical
contamination of process baths increases recyc lability, enhances the life of the process baths, and
reduces the amount of replenisher chemicals required. Some types of squeegees may damage the
film image, if it has not fully hardened,
Accurately adding and monitoring chemical replenishment of the process baths will cut
down chemical waste. Process baths may be protected from oxidation by reducing exposure to
air. Some smaller photo developers store chemicals in closed plastic containers. Glass marbles
are added to bring the liquid level to the brim each time liquid is used. This limits the volume of
air in the container, thereby extending the chemical's useful life.
Proper storage conditions are necessary to maximize the life of paper for color prints.
One writer recommends storing paper in a refrigerator, if it will not be used for a few days, and in
a freezer for longer storage periods. He states that he has used the same box of paper for years by
freezing it.(Sribnick)
Material substitution involves replacing a processing chemical with an alternate material
thai reduces the quantity of waste generated or the degree of hazard associated with the waste.
Opportunities for this type of waste reduction in photoprocessing are limited. Alternate materials
may be unavailable, more expensive, or have undesirable effects on product quality.
The "black box" nature of photoprocessing chemistry generally requires an individual
operator to use established chemical packages with few options for substituting alternate
materials. Photochemical manufacturers and suppliers can aid photoprocessors, however, by
developing new processes which result in lower volume and lower toxicity wastes. For example,
in most processes ferricyanide bleach has been replaced by ferric EDTA
(ethylenediaminetetraacetic acid) complex, resulting in a less toxic waste stream,{Calif. DHSa)
Over the past 20 years, the industry has significantly reduced the content of silver in its
products. The vast majority of silver in film is not used in the image and is recovered from
processing solutions. However, the nature of the image formed determines the amount of silver
used in that image; quality requirements for image and consistency limit the potential for further
reduction.(EPA 1994)
As a result of the reduction in the silver content in film, the industry has also reduced the
amount of hydroquinone in developer. There is a direct relationship between the amount of
silver on the film base and the amount of hydroquinone required to develop the image. The
amount of chromium used in the film emulsion has also been substantially reduced, and is
currently used only in the Kodachrome process. The elimination of chromium in traditional
films was primarily the result of regulatory demands on processors to eliminate it from their
45
-------
effluent, In contrast, the concern about selenium has arisen only recently with Xerox's
development of a heat-based film which contains this element, Although Xerox is promoting the
film on the basis of its silver-free nature, many in the industry claim that selenium is far more
toxic than silver, and that from an environmental perspective, the new technology represents a
step backward.(EPA 1994)
Businesses which operate in-house labs have more flexibility for material substitution,
such as using non-silver film, A company that supplies microfilms of catalogs and standards to
industrial users has switched to diazo and vesicular films. However, it should be noted that these
films are not considered "archival" and may not be acceptable for permanent document storage.
7,3 Silver Recovery Considerations
Metallic silver trades as a commodity in units of Troy ounces (one Troy ounce equals
31,10 g~' us). In recent years the price range has typically been $4 to $6 per Troy ounce,
although during the speculative fever of 1980, the price reached $50 per Troy ounce, before the
market collapsed. Thus, if the market price were $6.00 per ounce, and an effluent contained 31
nig/L silver, the potential recover}' value of silver would be 0,6 cents per liter or nearly 2,4 cents
per gallon of effluent. Since silver recovered from photoprocessing requires further processing,
reclaimers will offer somewhat less than market price for the recovered silver,(EPA 199la)
The quantity of silver entering a processing facility can be estimated based on the number
of rolls processed and the surface area of prints produced. The silver content in Troy ounces of
several types of photographic films and papers, as well as the surface per role of film, is
available in EPA documents. While the silver content of film varies, the most commonly used
films contain about 25 Troy ounces per 1000 square feet. Commonly used papers have about one
tenth the silver content of film per square foot, at about 2,4 Troy ounces per 1000 square
feet,(EPA 199la, EPA 1991b)
Major sources of recoverable silver are: photoprocessing solutions, spent rinse water,
scrap film, and scrap printing paper. The silver in these materials may exist as insoluble silver
halide, soluble silver thiosulfate complex, silver ion, or elemental silver, depending on the type
of process and the stage in the process where the silver is being recovered.
As much as 80 percent of the total silver processed for black-and-white positives and
almost 100 percent of the silver processed in color work will end up in the fixer or bleach-fix
solution. Silver is also present in the rinse water following the fixer or bleach-fix due to
carry-over, The amount or silver in rinse water is only a small fraction of that in the fixer or
bleach-fix solutions, but can be economically recovered when high volumes of rinse water are
used, A variety of equipment types and sizes are available for silver recovery*. Table 7.1
compares silver recovery' methods. More detailed descriptions are given in Section 7.4 below.
46
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Table 7,1 Comparison of Silver Recovery and Management Systems
System
Advantages
Limitations
Metallic
Replacement by
Chemical
Recover)1
Cartridges
(CRCs)"
Can be used for all silver-rich
solutions
Little maintenance, low operating
costs
Low capital costs
Simplest operation
Can achieve 99% recover)- when
2 CRC used in series
Requires metered flow for consistency
Must be replaced on schedule
Tendency to channel and cause concentrated silver
discharge, efficiency diminishes with use
High silver content in effluent unless 2 units in series
Silver recovered as sludge
High smelting and refining costs
Cannot determine amount of silver recovered until
refined
pH dependent
High iron content in effluent precludes reuse in photo
process
Electrolytic
(terminal)
High purity silver flake
Low refining costs
Can determine silver recovered
Capital costs moderate
Can achieve 90% recover)'
No additional chemicals released,
fix solution can be recycled
Cannot achieve 5 mg/L with electrolytic alone
Can sulfidc if not properly maintained
pH dependent
Not suitable for silver-poor solutions
Precipitation
Can attain 0.1 rog Ag*/L
Little operator maintenance
Low to moderate capital costs
Silver recovered as sludge
Smelting costs higher than electrolytic
Requires ongoing additives
Complex operation
Operation costs vary from moderate to high
Potential H:S release
Treated solution cannot be reused
Requires hazardous chemicals
Evaporation'
Distillation
Reduces wastes up to 90%
Virtually zero overflow of silver
High energy requirements
Moderate to high capital costs
Silver recovered as a sludge
Organic contamination buildup
Concentration technology - Requires additional
recovery
Reverse Osmosis
Efficiently recovers silver
dilute photoprocessing
wastestreams
Reduces effluent volume
significantly
No water treatment chemicals
required
Also recovers other chemicals
Purified water is recyclable
Capital costs vary significantly
Size of equipment needed to obtain sufficient flow
Frequent maintenance of membrane and pumps
Works on dilute solutions such as washwater
Large installations can be noisy
Concentration technology - Requires additional
recovery
47
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System
Ion Exchange
Advantages
Efficiently recovers silver from
dilute photoprocessing
wastestreams
Can attain 0. 1 - 2.0 mg AgVL
Limitations
Only for dilute effluent such as washwater
Capital costs vary significantly
Biological growth problems
May require the use of hazardous chemicals
Complex operation
Sources: Silver CMP, EPA 1 99 1 a, EPA 1994
7.4 Silver Recovery from Fixer Solution
The most common methods of silver recovery from the fixer and bleach fix processing
solutions arc metal replacement, electrolytic recovery, and chemical precipitation. Ion exchange
and reverse osmosis are other methods that can be used. However, these are suitable only for
dilute silver solutions such as wash water from a primary silver recovery unit which has been
mixed with wash waters. Some facilities use a primary silver recovery unit, which removes the
bulk of silver, in combination with a "tailing" unit to treat the relatively low silver concentration
effluents from a primary silver recover}' system. Color developer effluent does not flow through
a silver recover}1' unit because the silver content is very low and the high pH developer, if mixed
with other silver-bearing solutions, could reduce the efficiency of silver recovery and could result
in ammonia generation.(EPA 199la)
A silver recovery system can be devoted to a single process line or can be used to remove
silver from the combined fixer from several process lines in a plant. Multiple stream systems are
more typical in large facilities. Sometimes a separate fixer system is used for specialty
processing to reduce the possibility of inner-process contamination, which can occur when
desilvered fixer is recycled to the photo process.
7.4,1 Metallic Replacement
Metallic replacement occurs when a more electrochemically active solid metal such as
iron, contacts a solution containing dissolved ions of a less electrochemically active metal, such
as silver. The more active metal goes into solution as an Jon, being replaced by an atom of the
less active metal in the solid matrix. The dissolved silver, which is present in the form of a
thiosulfate complex, reacts with solid metal.
Silver ions will displace many of the common metals from their solid state. Because of
its economy and convenience, iron in the form of steel wool is used most often. Hypothetically,
zinc and aluminum can also serve as replacement metals; however, both have drawbacks. Zinc is
not used because of its relative toxicity and greater cost. Aluminum is not used because it
simultaneously generates hydrogen gas, which can be an explosion and fire hazard if improperly
handled.
-------
Commercially available of a wool-filled plastic with
appropriate connections. These units are called chemical recovery cartridges (CRCs). Typical
practice is to waste fixer to a of two CRCs in series. The first CRC the bulk
of the silver, the second polishes the effluent of the first. It is a safety factor if the first
unit is overloaded. When the first is exhausted, the second becomes the first, a fresh unit
replaces the second. One supplier recommends changing CRC when the silver in the
effluent of the first cartridge 25 percent of the influent concentration,(Kodak 1980) The
silver concentration in the effluent from a single cartridge 40 to 100 mg/L over the life
of the system, versus a of 0.1 to 50 mg/L when two CRCs are used in series. Fixer
desilvered by this process cannot be recycled, of excessive iron concentration in the
effluent, which can average 4,000 mg/L.
For effective operation, the pH of the solution through the metallic replacement
unit should be between 4 6,5. The optimum is between 5 5.5, Below pH 4, the
dissolution of the steel wool is too rapid. Above pH 6.5, the replacement reactions may be so
slow that silver removal is incomplete. Thus, proper pH control is important to high silver
recover}-. A CRC should recover about 85 percent of the recoverable silver in the form of a
sludge, which must be further processed to produce pure metallic silver.(Calif. DHSa)
7.4.2 Electrolytic Recovery
An electrolytic unit can be for a primary or a tailing waste stream, and can be either
batch or continuous. This silver recovery method applies a direct current across two electrodes in
a silver-bearing solution. Metallic silver deposits on the cathode, Suifite and thiosuJfate are
oxidized at the anode:
FUO + SO,'- -* SO4-? + 2e + 2!f (Anode)
SCV: + S,Oj-2 -> S3(V2 + 2e (Anode)
Ag' + e -» Ag° (Cathode)
Approximately I of sodium sulfite is oxidized for each of silver deposited.
Considerable agitation and large plating surface can achieve good plating efficiency and
silver up to 90-98 percent pure. Lower silver purity levels usually result from tailing unit
applications because of the lower silver concentration in the influent solution, The cathodes are
removed periodically, and the silver is off. An electrolytic system should recover
about 90 percent of the recoverable silver.
Care must be taken to control the current density in the cell because high density can
cause "sulfiding." Sulfiding is the decomposition of thiosulfate into sulfide at the cathode which
contaminates the deposited silver recovery efficiency. The higher the silver
49
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concentration, the higher the current density can be without suifiding. Therefore, as the silver is
plated out of solution, the current density must be reduced.
7.4.3 Hatch Electrolytic Recovery
In batch recovery, overflow fixer from one or more process lines is collected in a tank.
When sufficient volume is reached, the waste fixer is pumped to an electrolytic cell for silver
removal, The desilvered fixer can be discharged to a sewer, disposed of as solid waste, or
reused. If reused, it is transferred to a mix tank where sodium thiosulfate is added to replenish its
strength.
Primary batch system cells are usually designed to desilver the fixing batch at initial
silver concentrations of about 5,000 mg/L. The silver concentration in the effluent is typically
200 to 500 mg/L, Effluent of 20 to 50 mg/L is possible with additional treatment time and
careful current density control. An electrolytic tailing cell tyr" "ally achieves the lower range
because the process can be optimized for low initial silver concentrations.
7.4.4 Continuous Electrolytic Recovery
The volume of a continuous electrolytic unit must be large enough relative to the
incoming flow volume to ensure adequate residence time of the fixer, so two or more units can
be placed in series to achieve this. The continuous flow of incoming fixer supplies a constant
quantity of silver for electrolytic recover}". As a result, the units can be operated at a relatively
stable current density. Such systems can be automatic. Some units can sense silver
concentration in solution and adjust current densities. Usually, continuous flow units discharge
desilvered fixer directly to the sewer.
7.4,5 Recirculating Electrolytic Recovery
Silver can also be removed from an in-use fixer solution at approximately the same rate it
is added by film processing, using a continuously recirculating system. The recover}5 cell is
connected "in-line" as part of the reeirculation system. This continuous removal technique has
the particular advantage of maintaining a relatively low silver concentration in the fixer
processing solution, which minimizes the amount of silver carried out into the wash tank. Also,
the fixer replenishment rate is reduced, decreasing chemical usage and discharge quantities. The
silver concentration in the fixer can be maintained in the range of 500 to 1,000 mg/L without
forming sulfide.
A recirculating silver recovery unit receives a small continuous stream of fixer from an
in-use process tank, removes the silver, then returns the desilvered fixer to the photoprocessor.
50
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Each photoprocessing unit a silver recovery unit. Systems are available for
treating all types of non-bleach that have circulation pumps. Once installed, the unit is
fully automatic, turning itself on by the flow of fixer through the electrolytic cells. The
cells themselves contain no moving parts, the silver is harvested every two to three months.
Desilvered fixer solution can be reused, whether from an "in-line" continuous system or
from batch, This requires adequate monitoring process control to maintain composition and
protect quality. Some manufacturers have special electrolytic fixers for this application.
Parameters (pH, silver, and sulfate concentrations) should be monitored to maintain the physical
and chemical properties of the fixer solution, usually the addition of make-up chemicals.
7.4,6 Chemical Precipitation
Chemical precipitation is the oldest cheapest method for recovery of silver. It is
widely used by manufacturer? of photographic supplies but usually not by photoproeessors, The
two primary are that extremely toxic hydrogen sulfide gas (H2S) can be evolved,
and that the resulting sludge may have to be managed as a hazardous waste, A third
disadvantage is that recover)' of silver from the sludge is more difficult than with other methods,
Sodium sulfide (Na2S) causes silver sulfide to precipitate readily from waste fixer
solutions.
2Ag* + S': -» Ag2S
Silver sulfide is extremely insoluble with a solubility product of 10"50. Precipitation must
be carried out in alkaline media to avoid the of H2S, Silver sulfide tends to form
colloidal suspensions. Its very small particle size filtration difficult, and the filter
generated is extremely dense. However, diatomaceous earth filter aid can be used to improve
filtration. About three grams filter aid are required for of silver, if a conventional
plate-and-frame filter press is used.(Calif. DHSa)
Sodium borohydride (NaBH4) is an effective precipitant for silver:
NaBH4 -» Na" + BH4
BH4 + 2H2O + 8Ag+ -» 8Ag° + 8H* + BO3
The borohydride method requires significantly more than the stoichiometric quantity to
complete the reaction, while sodium sulfide precipitation requires use of very little excess
chemicals, Borohydride many other as cadmium, lead, and
mercury.(Cook) The major difference the two is the resulting silver quality.
Sodium borohydride produces elemental silver of 96 to 98 percent purity. Either method can
reduce silver concentrations to 0,1 mg/L in the fixer waste water,
5!
-------
The process mixes the precipitation agent with the silver bearing wastewater in a batch
reaction tank equipped with automatic pH control. When sodium sulfide is used, the pH must be
maintained above 7 to avoid releasing H2S, The optimum pH range for sodium borohydride
precipitation is 5,5 to 6.5, Solid particles having a size of 1 to 2 microns are formed, and are
allowed to settle before filtering. Usually solutions reacted with either sodium sulfide or sodium
borohydride are not reused in the photographic process.
7.5 Silver Recovery from Rinse Water
Even with an efficient fixer solution silver recovery system and an effective on
the fixer tank, up to 10 percent of the recoverable silver is lost by carry-over into the rinse tank,
The silver concentration in the spent rinse water is typically in the range of 1 to 50 rag/L, too low
for economical recover}' with electrolytic or metallic replacement methods. In addition, the iron
by-product from metallic replacement precludes reuse of the rinse water, although some
photoprocessors use metallic replacement to meet municipal sewer effluent limits. Free' Citation
is uneconomical for rinse water.(Calif. DHSa)
Two methods are currently being used for effective recovery of silver from rinse water:
resin ion exchange and reverse osmosis (RO). A third method, called "low flow prewash," has
been used in a few locations in the United States.
7,5.1 Ion Exchange
Ion exchange is the reversible exchange of ions between a solid resin and a liquid, A
variety of weak and strong anionic resins are effective in silver recovery. Using chloride as the
mobile ion, the following represents the reaction:
(Resin)-CI + AgS3CV -* (Resin)-AgS2O3 + CT
The silver-ihiosulfate complex has a high affinity for the resin, making it difficult to reclaim the
silver and regenerate the resin. Other problems include plugging of the resin by suspended
matter, such as gelatin, but these have also been solved by improved equipment design and
operational procedures. Some ion exchange units produce effluents with silver concentrations as
low as 0.1 ppm, recovering as much as 98 percent of the silver.(Kodak 1990) High-capacity
units can process as much as 500 gallons per hour.(CaIil DHSb)
7.5.2 Reverse Osmosis
In reverse osmosis (RO) techniques, the waste water stream flows under pressure over the
surface of a selectively permeable membrane. Water molecules pass through the membrane and
52
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other constituents are left behind. The extent of separation is determined by membrane surface
chemistry and pore size, fluid pressure, and waste water characteristics, The RO unit has one
inlet to receive the waste stream, and two discharge outlets. Purified water (permeate) exits from
one outlet, and concentrated wastewater exits from the other. This process reportedly can
recover 90 percent of the silver thiosuIfate.(Kodak 1990) Silver can be recovered from the
resulting concentrate by conventional silver recovery methods. The wastewater must be pumped
to high pressure (about 600 psig) before feeding the RO unit, which may incur high energy and
maintenance costs. Operating problems include fouling of the membrane and biological growth.
Proper maintenance and control can alleviate these problems. One plant reported membrane
fouling, which required frequent membrane replacement at high cost. The problem was solved
by installing a sandbed filter upstream of the RO unit.(Calif. DHSa) RO requires more capital
investment than most other silver recovery methods, discouraging its use in photoprocessing.
(Kodak 1990)
7.5,2 Low Flow Prewash
1 ,ow flow prewash involves segmenting the after-fix wash tank to perform the washing in
two stages, with separate rinse water make-up and overflow. It does the after-fix washing in two
stages. Most of the silver carry-over is washed off in the low volume, after-fix prewash tank.
The system lessens dilution of the silver carry-over, but means that concentrations of fixer, silver,
and other chemicals reach high levels in the prewash tank under steady-state conditions. One
problem Is that the work being processed may receive additional fix time and exposure to
concentrated contaminants while immersed in the prewash. Some investigators fear that this may
harm the quality of the processed material. Dye stability tests on color paper processed using the
prewash system showed an increase in yellow stain six months after processing. Another
problem is increased maintenance of the wash tank because of biological growth, although this
can be controlled with biocides.(Calif. DHSa)
7,5.4 Silver Recovery from Scrap
Scrap film and paper result from trimmings, test strips, and leaders. The silver may be
present in the form of silver salts or elemental silver from fogged or developed material. The
processing of solid materials is more cumbersome than for solutions, but there are a number of
silver recover}-' companies in business that will buy solid scrap. If necessary, the silver in scrap
film and paper can be removed in the photo lab by treating the material with a sodium
hypochlorite solution to oxidize elemental silver, assuring that all silver is in the form of salts
that can be removed by fixing. Some photo labs collect fixer overflow in a container and add
unprocessed scrap film or paper as it is generated. Once dissolved in the fixer, the silver can be
recovered through the same silver recovery processes used by the lab for the fixer solutions from
the photoprocessors. This approach can increase the amount of silver recovered on site, but can
53
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also be a bit messy. Digested film or can be difficult to and may even go sour, if
left In the container long enough to be by bacteria.(Calif. DHSa)
Processed or unprocessed film can be in an agitated, hot solution of sodium
hydroxide to remove the emulsion, The silver can then be from the solution by
settling, centrifuging or filtering. If the film is to be as polymer after the silver
bearing emulsion has removed, the film is by type of base.
7.6 Color Developer Reuse
Color developers which can be are available, allowing the photoprocessor to
reduce replenisher 50 percent. One regeneration process requires the addition of
an ion-exchange unit to remove the development by-products from the developer
overflow. Another process accomplishes the objective without ion exchange, using a
different developer solution.(Kodak 1989a)
7.7 Ferricyanide Recovery
Ferricyanide to ferrocyanide during the bleach process. The spent
ferrocyanide can be regenerated either electrolytically or chemically. Chemical methods employ
either ozone or persulfate. Regenerated ferrieyanide can be re-used in photoprocessing.
7,7.1 Electrolytic
Spent bleach is fed to an electrolytic cell, where the following reactions occur:
Anode: Primary: 2Fe(CNV* -» 2Fe(CN)ft'J + 2e'
Secondary: 4OH* -> O, + H, + 2GH" + 2e'
54
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Cathode: Primary: 2H2O + 2e' -» R2 + 2OH'
Secondary: Fe(CNyJ +V -» 2Fe(CN}6'4
The evolution of hydrogen gas presents a potential safety hazard,{Kodak 1990)
7.7.2 Persulfate Regeneration
This method is relatively inexpensive and safe, since it does not liberate any hazardous
gases. The reaction is:
2Fe(CNV4 -f S2GK': -* 2Fe(CN)6-' + 2SO4':
The major disadvantage is that gradual accumulation of sulfate salt reduces bleaching
efficiency.! Kodak 1990)
7,7.3 Ozone Regeneration
Iteone reacts with ferrocyanide to form ferricyanide as follows;
y4 + O, + H20 -* 2Fe(CN)6-J + 20H" + O2
Hydrobromic acid is also added to control pH and to supply the bromide ion needed for the
bleach process. The major advantage of this process is that there is no salt buildup.
Disadvantages include high initial cost for the ozone generator and potential safety problems,
since ozone is corrosive, unstable, and high reactive. Because of these disadvantages, this
process is likely to be used only by large labs,(Kodak 1990)
7,7,4 Ion Exchange
Bleach water containing dilute concentrations of hexaeyanoferrates (either ferricyanide or
ferrocyanide) can be passed through a column containing a weak base anion exchange resin,
which removes the hexacyanoferrate. The resins is then regenerated with sodium hydroxide, and
the recovered hexacyanoferrate reacted with ozone or persulfate to recover ferricyanide as shown
above. Treated effluent from this process can contain as little as 0.075 mg/L (75 parts per
billion) hexacyanoferrate.(Kodak 1990)
55
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7,7.5 Reverse Osmosis
Reverse osmosis can remove up to 95 percent of the salts from fixer solutions, including
nearly all of the hexacyanoferrates. The capital investment is relatively high, which has limited
applicability of this process in photoprocessing.(Kodak 1990)
7.7.6 Precipitation
Fixer overflow can be treated with ferrous sulfate and a floceulent to produce ferrous
ferrocyanide. Then either sodium or potassium hydroxide is added to make the ferrocyanide,
which can be reoxidized with one of the bleach regeneration techniques. The resulting
ferricyanide can be reused as bleach replenisher.
Another method uses calcium chloride to precipitate the salt Ca(NH4):.Fe(CN)<,. This
method can reduce ferrocyanide concentration of some color-reversal fixers to less than I g/L.
(Kodak 1990)
7.8 Rinse Water Use: Reduction and Recycling
To maintain product quality, many photoprocessing operations use continuous rinse water
flows. The result is rinse water waste streams usually are the highest volumes of waste from
photoprocessors, This effluent consists primarily of water with low concentrations of chemicals
from the carry-over of the processing solutions. Commercial rinse water recycling systems are
available for photoprocessing operations. Spent rinse water can be treated to restore purity and
recycled for rinsing. A small portion of incoming clean water is added to the recycled water
stream, and an equivalent overflow goes to the sewer drain after the fixer wash. A single
recycling system can serve several photoprocessor units.
Water conservation is important in certain parts of the United States where either (a) fresh
water is in short supply or (b) local regulations severely limit or prohibit discharge of
photoprocessing effluents to the sewer system. Some operators simply shut off the rinse water
except when film is moving through the processor. However, certain processors require a
continuous water flow to maintain temperature control. Many locales have established
concentration-based limits on aqueous effluents, which encourages greater rinse water use for
dilution. Photoprocessors must check the local requirements to be sure that reducing water
without proportionately reducing all other contaminants will not violate the concentration limit.
-------
7,8,1 Countercurrent Rinsing
Continuous photoprocessing trains may employ a series of rinse steps, designed so that
water flows countercurrent to the process, Thus, fresh water is fed to the final stage. Overflow
water then goes to the next stage upstream. Of course, the rinse water becomes more
contaminated in each succeeding stage. Thus, it may be economical to use squeegees to
minimize carryover of contaminants into each rinse stage, and a squeegee between the processing
solution and the first wash stage is recommended. Otherwise, efficiency will be impaired and
product quality will degrade,
7.8,2 Plumbingless Minilabs
Plumbingless minilabs use a proprietary chemical stabilizer in place of wash water.
While conventional minilabs discharge 20 to 25 gallons of effluent per roll of film processed, this
type of lab discharges less than 0,1 gallon of effluent per roll. Although the volume of effluent is
greatly reduced, the concentrations of contaminants are much higher than for conventional
minilabs. Wherever there are concentration limits on sewer discharges, potential users should
review this point with local authorities if silver can be recovered from this effluent using either
the metallic replacement or electrolytic processes described above,(Kodak 198%)
7,8.3 Evaporation
Another option in managing waste photographic solutions is evaporation, in which the
wastewaters arc collected and heated to evaporate all liquids. This is often done under vacuum to
reduce the boiling temperature. As the water and volatile compounds are removed, soluble
materials remain to form a sludge. The sludge is collected in filter bags, which can be sent to a
silver reclaimer for recovery. Evaporation can accommodate operations that do not have access
to sewer connections or waste water discharge. If the water vapor is condensed and recycled,
instead of being vented to the atmosphere, then this can be considered a source reduction
technique.
One manufacturer has an automatic recirculaling system in which aqueous effluent is
continuously introduced into the evaporation chamber. The water is vaporized, then condensed
and recycled to a rinse water holding tank. As the water evaporates, the solids are collected in
one of two 5-micron filter bags. When the unit senses that the filter bag is full, it switches the
flow to the other filter bag, and alerts the operator to remove the filled bag.
The advantage of this approach is it achieves "zero" water discharge. Virtually all of the
silver in the waste solutions is captured with the solids. There are several disadvantages,
however. One is that volatile organics in the waste solution may be evaporated as well, creating
an air pollution problem. One evaporation unit has a charcoal air filter to capture these organics.
57
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A second disadvantage is that any organics which condense with the water will be recycled also,
causing a potential buildup of their concentrations in the process. Finally, this is an energy
intensive technique and so carries associated high energy costs and fuel-use environmental
effects, (Calif. DHSa)
7.9 Implementation of Control Technologies
As detailed above, photoproeessors practice chemical recover)' and wastewater treatment
for both economical and environmental reasons. The wastewater from photoprocessing
operations has been a focus of regulation because of a number of parameters, including toxic
metals, toxic chemicals, oxygen demand, ammonia, and bionutrients. Table 7,2 below presents
1991 data on the use of environmental controls and chemical recovery methods by commercial
photoproeessors.
Table 7,3 summarizes the silver concentration at typical recover}' efficiencies for end of
process, in combination with low silver solutions, and in combination with process wash waters.
Table 7,2 Commercial Photoprocessor Environmental Controls, 1991
Percent Operating Silver
Recovery' Systems
Type of Silver Recovery
System Used;
* electrolytic recovery
• steel-wool canister
* ion exchange
• evaporation/distillation
Percent that Recycle Water
Percent that Regenerate
Chemistry
Percent of Finns Visited or
Contacted by State or Local
Water Authority in 1 99 1
All
Specialty
Retailers
Combined
80.7%
45,8%
3.6%
2,4%
7,8%
25,8%
Camera
Store with
Minilab
96.3%
82.6%
48.9%
0.9%
0.9%
10.2%
19,6%
13.1%
Stand-
Alone
Minilab
89,5%
81.0%
43.9%
6,3%
0.3%
7,2%
28,6%
25.4%
Mail Order,
Wholesale,
and Captive
Labs
100%
94,7%
57.9%
20.8%
83%
40.9%
86.4%
73.3%
Portrait
Studio
Firms
66.7%
63,2%
36.8%
2,0%
4.1%
10.0%
22.6%
25,0%
Source; EPA 1994
Note: Population basis for these values was unspecified in source report (EPA 1994).
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Table 73 Silver Concentrations After Silver Recovery (mg/L)
Percent Recovery
Ag in Silver-Rich
After Recovery'
When Combined
with Silver-Poor
When Combined
with Wash Water'
90%
95%
99,9%
200 - 800
100-400
20-80
2-8
100-400
50 - 200
10-40
1 -4
10-40
5-20
1-4
0.1-0.4
Source: Silver CMP
1, Silver concentrations after recover}',
2. Silver concentrations when treated silver-rich solutions are combined with silver-poor solutions. Silver-rich
solutions include fix, bleach-fix, washless stabilizer, and low-flow washwaters. Silver-poor solutions include
developers, bleaches, stop-baths, stabilizers used after washes, and washwatcrs,
3. Silver concentrations when treated silver-rich solutions are combined with silver-poor solutions and process
wash waters.
7.10 Control and Treatment Issues
A barrier to the effective treatment of photoprocessing wastewaters is the small size and
lack of technical sophistication of many of the photoprocessors. Processes to remove silver and
other pollutants from wastewaters require careful operation and maintenance to achieve their
design effectiveness. Many photoprocessors, especially the minilabs within drug stores, grocery
stores, and department stores, do not have staff with sufficient training and longevity to operate
this equipment effectively,(EPA 1994)
High prices for certain inputs have encouraged reduced use of those inputs over time. In
addition competition based on product quality has encouraged some environmental
improvements. This congruence between economic and environmental goals was particularly
noted with respect to silver. Past increases in the price of silver encouraged efforts both to
reduce the amount of silver used in sensitized products and to increase silver recover)' and
recycling. The extent to which silver is recycled is sensitive to price, and according to industry
participants is currently hampered by the combination of moderate prices for silver the costs
of complying with RCRA rules. However, actions taken to reduce the amount of silver in
sensitized products also had the effect of improving product quality. According to industry
contacts, competition based on product quality has continued to encourage the use of less silver
over time, independent of fluctuations in the price of silver.(EPA 1994)
The high cost of replacing photoprocessing equipment acts as an economic barrier to
improved environmental performance. Many environmental improvements (e.g., processes that
59
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recycle photoprocessing chemicals) are embedded in the photoprocessing equipment, and
replacement of existing equipment is required to achieve those improvements. Photoprocessors
are reluctant to replace equipment before the end of its useful life, especially minilabs, for whom
the capital investment can be a substantial burden. While the equipment replacement cycle
as some constraint on the speed of environmental improvements, it is not clear that is causes
significant delays. The basic pace of product and process improvements results in a turnover of
photoprocessing equipment in only eight years on average, according to industry experts,(EPA
1994)
Photographic product users' needs are also cited by industry contacts as a factor
influencing the pace and extent of environmental improvements. As described earlier, different
end-use segments present different demands that influence the nature of the leading
photoprocessing chemistry over time. For example, the market demand for one-hour processing
eliminates many opportunities for reducing the chemical content of processing packages. If
chemicals are reduced, the film must remain in the solution longer, extending the time required
for developing. Also, the accurn ~ y an quality requirements of x-ra., film an graphic arts film
limit the potential for alternatives to siIver-halide-based film.(EPA 1994)
60
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8. Environmental Assessment
8,1 Introduction
This chapter examines the effects that the pollutants discharged from the photoprocessing
industry may have on human health, aquatic ecosystems, and Publicly Owned Treatment Works
(POTWs), First, the list of characteristic photoprocessing pollutants, introduced in Chapter 6, is
re-examined. Next, pollutant loads as reported in the national Permit Compliance System (PCS)
database are presented. Total industry pollutant loads are then calculated using estimated flows
and pollutant concentrations from Chapter 6. A toxic weighting factor analysis is performed for
the list of characteristic pollutants. This analysis is used to show the relative toxieity of the
effluent components in a manner consistent with the effluent guidelines program. These toxic
weighting factors are used in conjunction with the calculated pollutant loads to estimate industry-
wide toxic loads.
Next, a qualitative, pollutant-by-pollutant list of potential environmental impacts and fate
is presented for typical photoprocessing effluent constituents. Evidence in the scientific literature
of the negative environmental effects of photoprocessing wastewater is summarized. The three
areas of concern explored here include impacts on activated sludge treatment, impacts on human
health, and impacts on aquatic ecosystems.
A separate section is devoted to the potential impacts and speciation of silver, which is
the pollutant of greatest concern in photoprocessing effluent. It is explained that, although
certain ionic forms of silver are considerably toxic, especially to aquatic invertebrates, more
prevalent compound and cumplexed forms of silver are generally less toxic.
8.2 Pollutants Found in Photoprocessing Effluent
Table 8.1 lists the main pollutants mentioned in Chapter 6 as possible photoprocessing
wastewaler constituents. Two of the pollutant parameters (Temperature and pH) are not
pollutants in the traditional sense and will not be discussed further here. Five (COD, BOD, TSS.
TKN and TDS) are classes of pollutants and not individual pollutants. Discussion of health
effects, environmental effects, and POTW treatment for many of these pollutants follows the
loading analysis in Section 8,4. For other parameters, health and environmental effects and
POTW removal data were not available.
61
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Table 8.1 Possible Photoprocesslng Wastewater Constituents
Pollutant Parameter
Ferri- and Ferro-cyanide
Cyanide
Chromium
Para-pheny lenediamene
Hydroquinone
Sul foliated Hydroquinone
Ascorbic Acid
Ethylcnediaminctetraacetic acid
(EDTA)
Hydroxylamine
Iron-EDTA Complex
Propylenediaminetctraacetic acid
(PDTA)
Ammonia Thiosulfatc
Silver Thiosulfate
Temperature
pH
Biochemical Oxygen Demand (BOD)*
Chemical Oxygen Demand (COD)*
Total Dissolved Solids (TDS)*
Total Suspended Solids (TSSf
Ammonia Nitrogen (NHj-N)*
Total Kjelda'- Nitrogen (TKN)*
Thiosulfate*
Sulfates*
Silver (after silver recovery)*
Iron*
Zinc*
* Pollutants for which data are available to calculate total annual discharge loads
Another source for pollutant information for the photoprocessing industry is the Permit
Compliance System (PCS). PCS is a computerized information management system maintained
by EPA's Office of Enforcement and Compliance Assistance (OECA). PCS contains data on
permit conditions and monitoring, compliance, and enforcement for facilities with National
Pollutant Discharge Elimination System (NPDES) permits. NPDES permits are applicable only
to facilities that discharge directly to surface waters. However, some stales also include data
from facilities that discharge to groundwater in the PCS data base, so these groundwater data are
also available in the PCS data base. Among other items, PCS records indicate the pollutant
parameters listed in the permit, and may also contain information of the loadings of these
pollutants discharged in the facility's wastewater.
Only five facilities in the United States are currently permitted and listed in the PCS data
base under the photoprocessing SIC codes. The pollutants and limits in these permits are based
62
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on ground water controls or water quality load allocations: none are on Subpart A of 40
CFR Part 459, Table 8,2 the pollutants and loadings for facilities for
1995, Loadings for Facilities 1.2,3, and 5 are all to groundwater. Facility 4 discharges its
wastewaters directly to surface water.
Table 8,2 Pollutant Loadings for Direct Discharge Preprocessing Facilities, 1995
Units are pounds per year, except flow is in gallons per year.
"Not Mon," indicates that pollutant was not monitored in the permit.
Pollutant
Flow (gallons/yr)
Fluoride, Total (Ibs/yr)
Copper, Total
Iron, Total
Nickel, Total
Silver, Total
Zinc, Total
Foaming Agents
Nitrogen, Total
Lead, Total
Phenoiics, Total Recov.
Methylene Chloride
Oil & Cirease
Nitrate, Total asN
Magnesium, Total
Sulfate, Total
iron & Manganese,
Total
Boron, Total
Chromium, Total
Manganese, Total
Antimony, Total
Facility 1
1284
0.004394
0.001479
0.000589
0,005958
0
0.009923
0
Not Mon.
Not Mon,
Not Mon,
Not Mon.
Not Mon,
Not Mon,
Not Mon,
Not Mon,
Not Mon,
Not Mon,
Not Mon.
Not Mon,
Not Mon,
FacHftj_2__
12090
Not Mon,
0.035028
0.660947
Not Mon,
0.001382
Not Mon,
Not Mon.
0,32509
0,001888
0
0
Not Mon,
Not Mon,
Not Mon,
Not Mon,
Not Mon.
Not Mon,
Not Mon.
Not Mon.
Not Mon,
_JaciIii^3___
45210
0.053113
0,03201 1
0.058013
Not Mon,
0.014938
0,05080?
0.04808
Not Mon,
Not Mon.
Not Mon,
Not Mon.
1 .029303
1,444289
3,475618
15.86418
0.061863
142
0,002772
0.002772
0.004927
Facility 4
33,480,000
Not Mon,
Not Mon,
Nof Mon.
Not Mon.
Not Mon.
"Not Mon,
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon.
0
Not Mon.
Not Mon.
Not Mon,
Not Mon,
Not Mon,
Not Mon.
Not Mon.
Not Mon,
Facility 5
201,000
Not Mon,
Not Mon.
0.397
Not Mon.
0,044
Not Mon.
Not Mon.
3.925
Not Mon.
0
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon,
Not Mon.
Not Mon.
Not Mon.
Not Mon.
63
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Pollutant
Aluminum, Total
Nitrogen- NH3 as NH,
Phenolic Compounds
Solids, Total Dissolved
Bromide
BOD, 5 day
Solids, Total Suspended
Nitrogen - NH3 as "N
Cyanide, Total
Silver, Dissolved
Silver. Total
Recoverable
Zinc, Total Recoverable
Aluminum, Total
Recoverable
Aluminum, Dissolved
Cadmium, Total
Recoverable
Chromium, Total
Recoverable
Chlorine, Total Residual
COD
Acetone
^JFaciHtjJ.^
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon,
Not Mon,
Not Mon,
Not Mon,
Not Mon.
Not Mon.
Not Mon,
Not Mon,
Not Mon.
Not Mon,
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Facility 2
Not Mon,
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon,
Not Mon.
Not Mon.
Not Mon,
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon,
Not Mon,
Facility 3
0.030341
0.948351
0.003318
115.4557
0.303408
Not Mon.
Not Mon.
Not Mon,
Not Mon,
Not Mon,
Not Mon,
Not Mon.
Not Mon.
Not Mon,
Not Mon.
Not Mon,
Not Mon.
Not Mon,
Not Mon.
Facility 4
Not Mon,
Not Mon.
Not Mon,
131328.1
Not Mon.
1397.108
1229.455
22,0743
5,588431
0.055884
0.111769
2.794216
27.67218
27.94216
2.794216
2.794216
27.94216
10897.44
Not Mon,
Paeilityj5_
Not Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon,
Not Mon.
Not Mon.
Not Mon.
0.044
. 'ot Mon.
Not Mon.
Not Mon.
Not Mon.
Not Mon,
Not Mon.
Not Mon.
Not Mon,
Not Mon.
0.022
This table shows that there is a wide disparity in the pollutants measured (permitted) from
facility to facility. The variation of these photoprocessing pollutant parameters is a subject for
future investigation. Permit writers also have chosen to require measurement of certain
parameters (for example, silver) by different means (total silver, dissolved silver, and total
recoverable silver) at different facilities. The reported loads for most parameters other than
conventional pollutants are below one pound per year, which is very low compared to most other
manufacturing and service industries. The flow values are relatively low as well.
64
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8,3 Toxic Weighting Factor Analysis
EPA's Office of Water uses toxic weighting factors (TWFs) to compare the relative
toxicity of industrial effluent discharges. The toxic weighting factors applied to the
photoprocessing industry are derived using the same methodology employed for other effluent
guidelines, but are based on updated toxicity information, TWFs are used to calculate
copper-based pound-equivalents, and are derived from EPA chronic aquatic life criteria (or toxic
effect levels) and EPA human health Ambient Water Quality Criteria (or toxic effect levels)
established for the consumption offish. For carcinogenic substances, the human health risk level
is set at !G'S, (i.e., protective to a level allowing 1 in 100,000 excess cancer cases over
background). Copper, a toxic metal pollutant commonly detected and removed from industrial
effluent, is selected as the benchmark (i.e., the pollutant to which others are compared), EPA has
used copper previously in TWF calculation for the cost-effectiveness analysis of effluent
guidelines. While the water quality criterion for copper has been revised (to 12.0 ^g/L), the
TWF method uses the former criterion (5.6 /ig/L) to facilitate comparisons with cost-
effectiveness values calculated for other regulations.
The TWF for aquatic life effects and the TWF for human health effects are added for
pollutants of concern. The calculation is performed by dividing the former copper criterion of
5,6 «g/L by the aquatic life and human health criteria (or toxic effect levels) for each pollutant,
expressed as a concentration in micrograms per liter (/ug/L):
TWF 5.6 . 5,6
AQ HHOO
Where:
TWF = toxic weighting factor
AQ = Chronic aquatic life value
HHOO = Human health (ingesting organisms only) value («g/L)
Toxic weighting factors for the 5 pollutants for which loadings are estimated and toxicity
data are available arc given in Table 8.3.
65
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Table 8,3 Pollutant Toxic Weighting Factors
Pollutant
Ammonia
Sulfate
Silver
Iron
Zinc
TWF
0,0022
5.6 X 10'*
47
0.0056
0.0051
Only one of the pollutants (silver) has a TWF greater than 1.0, This value is based on
silver nitrate, however, which is not expected to exist in any appreciable concentration in
photoprocessing effluent, as described in section 8.6.
8,4 Loads Associated with Photoprocessing Effluent
It is useful to estimate the total quantity of pollutants being discharged by the entire
universe of facilities of a certain industrial category in order to compare the relative pollutant
constituent releases within the industry, and also to compare these pollutant to those of
other industries. The total pollutant loading for the amateur photoprocessing industry can be
calculated from the flow and concentration values estimated in Chapter 6, Values for the other
photoprocessing sectors can not be estimated due to lack of processing volume information.
However, it is estimated that the amateur photoprocessing industry accounts for 44 percent of all
photoprocessing, in correspondence to this segment's silver use as compared to all photographic
silver use (data given in Table 4.3), The results presented in Table 6,8 show that the total 1994
amateur photoprocessing flow is estimated to be 2,250 million gallons per year, on the
additive process flow demands as reported in reference WEF 1994, The pollutant concentrations
found in the total combined wastestreams, as presented in Table 6,3, are multiplied by this flow
rate to calculate loads according to the following equation:
Load (Ibs/yr) =
Mean Concentration (mg/L) x 2,250 million gallons
x 3,785 L/gal x 2.205 Ibs/kg x I kg/106 mg
Since the total unweighted load does not sufficiently describe the potential environmental
impact of an industry's dicharge, toxic weighting factors as described above in Section 8.3 are
used to calculate a toxic load, from the following equation:
Toxic Load (Ibs-eq/yr) = Load (Ibs/yr) x TWF
66
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Table 8,4 shows the estimated loads for each pollutant constituent, and the toxic loads for
those pollutants which have a toxic weighting factor.
The table shows that the total expected annual load for the amateur sector this industry is
133 million pounds per year, and that approximately 9 million toxic pounds are discharged
annually (99,9 percent of which are due to silver, for which the given toxic weighting factor is
not representative). Once again, the amateur sector is estimated to account for 44 percent of all
photoprocessing volume.
Table 8.4 Estimated 1994 Loads and Toxic Loads for the Amateur Sector
of the Photoprocessing Industry
Pollutant
Parameter
BOD
COD
IDS
TSS
Ammonia
TKN
Thiosulfate
Sul fates
Silver
iron
Zinc
Concentration*
Mange (mg/L)
200-3,000
400-5,000
300-3,000
<5-50
20-300
30-350
] 00- 1,000
50-250
O.1-5
-------
film and paper used, the quantity processed, and the silver wash-out rates. The silver content of a
variety of films and papers, and the proportions of these film and papers used by type for a
typical photofmishing facility, are available in the literature. Assuming removal of all silver in
color processing, and 80 percent silver removal in black-and-white processing, these values give
the amount of silver rendered, in Troy ounces per 1000 square feet processed, to be 235 for
paper, and 21.3 for film.(EPA 199 la, EPA 1991b) Multiplication by the total film and paper
used for the U.S. amateur market allows the loadings calculation prior to silver recover}':
235 Troy .ounces x 4,1 15 x 106 ft2 paper +
1000 ft2 paper
2_L3. ..... Jjmv-Qiiflces x 296 x 10* ft2 film = 16 million Troy ounce
1000 ft2 film
or 1.1 million pounds silver
Thus, an overall recovery rate of 83 percent of this 1.1 million pounds would lead to the
estimated 1994 amateur market discharge quantity of 190,000 pounds.
8.5 Qualitative Environmental Impact of Photoprocessing Effluent Constituents
This section examines the potential environmental impacts of some of the pollutants
addressed earlier in this chapter as being characteristic of photoprocessing wastewater. Not all
pollutants are listed due to lack of information. Examples of impacts include: impacts on human
health, impacts on the health of aquatic organisms, impacts on operation of biological wastewater
treatment systems, and aesthetics. Removal by typical activated sludge systems is also
addressed,
Ammonia (NH3) is one of the constituents of the nitrogen cycle. It is a concern because it
can increase oxygen demand, promote eutrophication, and, when converted to nitrate, cause
irritation of the gastrointestinal tract. The toxicity of ammonia to aquatic life is dependant on pH
and dissolved oxygen level.(EPA 198 1 a) One study using a simulated photoprocessing waste
stream showed an average removal of ammonia in activated sludge reactors of 53
percent. (Pavloslathis)
Cadmium is an extremely dangerous toxicant. In addition to being classified as a human
carcinogen, cadmium could form organic compounds with mutagenic or teratogenic properties.
In addition, conventional water treatment practices do little to remove cadmium, and it has been
found to accumulate in the liver, kidneys, pancreas, and thyroid of humans and other animals.
Cadmium also acts synergistically with other rnetals; its toxicity is considerably increased when
68
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combined with copper or zinc. Among aquatic organisms, fish eggs and larvae and crustaceans
appear to be especially sensitive. (EPA 198 la)
Chromium
Chromium in industrial wastewaters exists primarily in hexavalent and trivalent states.
Both are hazardous to man and aquatic life, but in photoprocessing wastewaters the trivalent
form, which is considerably less toxic, predominates, Observed toxic effects on man include
lung tumors, skin sensitization, corrosion of the intestinal tract, and inflammation of the kidneys,
Lower forms of aquatic life are extremely sensitive to chromium. As with cadmium, chromium
is not destroyed when sent to a POTW, and it either partitions to the biosolids or passes through
the treatment stream. Removal by activated sludge systems is estimated to be 84 pereent.(EPA
198 1 a, EPA 1982)
Cyanide is generally found in photoprocessiitg effluent in the form of fern- and
ferrocyanide (hexacyano ferrate) ions. These forms exhibit a low order of toxicity to most aquatic
species, notable exceptions being crustaceans and algae, Hexacyanoferrate ions seem to cause no
adverse effect on POTW biomass at typical levels, and treatment plant removal efficiency was
reported at greater than 60 percent. As mentioned in Chapter 6, however, these ions release the
cyanide ion when exposed to sunlight. Some of the cyanide ions will join with hydrogen ions to
form hydrogen cyanide (HCN). depending on the pH of the solution, (The lower the pH. the
greater the percentage of cyanide ions that will be present in the form of hydrogen cyanide). The
cyanide ion is non-accumulative and comparatively non-toxic to humans. Toxicity to fish is
dependent on pH, temperature, dissolved oxygen, and presence of other minerals in the water. It
is generally more toxic to fish that it is to lower organisms.(EPA 198 la, EPA 1982)
iron is an essential nutrient for all forms of growth, and does not have significant toxic
impact on humans at any reasonable concentration. The presence of iron in water may encourage
growth of iron oxidizing bacteria, resulting in formation of slimes that may affect aesthetic
values of water bodies or block pipes. The recommended limit for iron in water supplies is based
not on health concerns but on aesthetic and taste considerations.(EPA 198 la)
Lead is not easily excreted from the human body, and thus accumulates with repeated
exposure over long periods of time. Possible effects include lead poisoning (plumbism) and
cancer. Lead is also a concern among animals. More farm animals are poisoned by lead than by
any other poison. Lead also causes suffocation offish. Studies have shown POTW removal
rates for lead of greater than 90 percent, although 80 percent is more common. Most of this is
partitioned to the hiosolids.(EPA 198 la, EPA 1982)
Sec Section 8.6.
69
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Sulfatcs are not harmful in moderate concentrations (<1,000 mg/L). They occur naturally
in waters, especially in the western United States. Thiosulfates are commonly found in
photoprocessing wastewaters, as described in Chapter 6,(EPA 1981 a). One study using simulated
photoprocessing wastewaters found that about 35 of total COD of the composite
photoprocessing wastewaters thiosuifate and sulfite. COD reductions in the activated sludge
reactors between 84 and 96 percent, including the almost-complete removal of
thiosuifate and sulfite (reduced to suifate). Ammonia removal in the photoprocessing wastewater
amended reactors, meanwhile, lower in the reactor, possibly indicating
inhibition of the highly-sensitive Nitrobacter species.(Pavlostathis)
Oxygen & COD)
Certain levels of oxygen demand, on the receiving water body, will result in
reduced Dissolved Oxygen (DO) levels. Aquatic organisms experience at reduced DO
levels, both at the individual and population levels. Some fish experience delayed
hate1 ing of eggs, interference with food digestion, growth rate, decreased tolerance to
other toxicants (including cyanide and lead), and swimming speed. These
effects are usually more pronounced in livelier (such as trout and salmon), BOD
removal rates by activated sludge are generally 90 percent.(EPA 198la, EPA
1982)
Total Dissolved (IDS)
Dissolved solids include chlorides and other halides, sulfates, phosphates,
nitrates, and trace substances. Although moderately high concentrations of TDS do not have
serious health effects on humans, drinking when TDS exceeds 2,000
mg/L. Tolerances of aquatic organisms for TDS is species specific, but although fish can slowly
become acclimated to higher salinities, sudden exposures can often be fatal(EPA 198la)
Total .Sugpgjid.gd, -Sfilids (TSS)
Suspended solids include organic (oil, tar, waste products) and inorganic (sand,
silt) components. Impacts on aquatic include reduced light penetration, which
hampers photosynthetic activity, dogging of gills respiratory of organisms,
POTW removal of TSS can be as high as 90 percent(EPA 198 la, EPA
8.6 Toxicity and Speciation of Silver
Silver is present in a number of compound and forms in photoprocessing
effluents. The concentrations, solubilities, and toxicities of these silver compounds are widely
varied, and it is essential to have some understanding of their to better comprehend
the possible adverse effect an effluent may on the environment
70
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The most common silver complex found in effluent is silver thiosulfate.
or Ag(S2O3)2. This is a stable complex with a dissociation constant of 3,5 E-l4, meaning that
free silver ions (Ag"| will not normally exist in any significant concentration. Silver nitrate
(AgNOj) is used extensively in the production of photosensitive films and papers, has the highest
solubility of the silver salts, and is classified as a strong irritant to skin and tissue. Silver chlorate
(AgClOj) is moderately soluble, is toxic when ingested. Silver chloride (AgCl) is soluble in
solutions containing an excess of chloride Ions, and in solutions of cyanide, thiosulfate, and
ammonia, and is relatively toxic. Silver bromide (AgBr) and silver sulfide (Ag2S) are insoluble
silver compounds commonly found in precipitate form in photoproeessing effluents. Solubilities
and Solubility Products (Ksp) of select silver compounds are shown in Table 8,5.
Table 8,5 Solubility and Solubility Product of Some Silver Compounds/Complexes
Silver
Compound
chloride
chlorate
bromide
nitrate
sulfide ({§20° C)
Solubility
(p/LH,Oat25*C)
1.9 X10'3
90
1.3X lO"*
2.16X103
1.4X10-4
K,P
1.8 X 10*'°
NA
3,3 X 10'!?
NA
1,0 X10-50
The free ionic form of silver combines rapidly with naturally-occurring substances to
form less toxic substances. For example, stiver chloride complexes arc three hundred times less
toxic and silver sulfide complexes are one million times less toxic than free silver.(Dufficy)
Table 8.6 demonstrates this relative toxicity for fathead minnows.
71
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Table 8,6 Percent Mortality of Fathead Minnows Acutely Exposed to Concentrations of
Different Silver Compounds
Silver
Compound
Silver Nitrate
Silver
thiosulfate
complex a
Silver sulfide
dispersion h
Silver chloride
(2000 ppm Cl) a
Mean
measured
total silver
concentration,
mg/L
0,065
0.029
0,013
0.0058
^80
140
70
240
37
4,6
2.0
0,38
free
silver ion
concentration,
mg/L
0,065
0,029
0.013
0.0058
0.12 X 10-*
0,33X10*
0.80 X10-6
-------
Silver that settles is removed the plant in the form of biosolids. There is
currently no EPA biosolids criteria for silver. POTW biosolids are often disposed by
landspreading or landfilling. Laboratory tests on biosolids containing silver in concentrations
from 19 to 83,000 mg/kg showed no of silver to the elutriate, Field indicated that
silver was effectively bound up by the soil.
No evidence could be found linking photoproeessing to adverse human health
effects. However, silver compounds can be absorbed into the circulatory system and reduced
silver deposited in various of the body, possibly in a greying of the
skin and mucous membranes known as argyria. Also, concentrations from 0.4 -1 mg/L have
been shown to cause kidney, liver, spleen in rats,(EPA 198la) Some local
authorities in the United States consider silver to be a waste in concentrations greater
that 5 mg/L, which is far less than of the effluent silver concentrations as
documented in Chapter 6.(EPA 199la) As mentioned in Section 8.3, several other constituents
in photoprocessing effluent can have carcinogenic and systemic health on humans.
LC50 concentrations of silver for a number of common aquatic organisms varies between
0.004 mg Ag/L and 0,2 mg Ag/L.(Bard) Other silver such as silver chloride and silver
nitrate, are also considerably toxic to fish. One study claims that "anthropogenic inputs of silver
from the Point Loma discharge off San Diego, CA can for essentially all of the silver in
coastal waters along the United States-Mexico during conditions", and that
"silver is one of the most toxic elements for marine invertebrates."(Sanudo)
The silver thiosulfate compiex, however, is considerably toxic; the 96 hour LCSO was
found to be greater 250 mg Ag/L. Other work indicated that a model laboratory' ecosystem
including rotifers, Daphnia, mussels, and fish remained viable during the ten week study
period in spite of continuous exposure to silver thiosulfate at concentrations as high as 5 mg
Ag/L.(Bard) Despite this, it is still desirable to remove as much silver thiosulfate from the
wastestream as possible, since thiosulfate accounts for a major portion of the oxygen demand in
photoprocessing effluent.(Hendrickson)
Bioaccumulation of silver in clams in the vicinity of the Palo Alto Regional Water
Quality Control Plant (RWQCP) has been well documented. Silver concentrations in clams near
the RWQCP discharge channel were to be from 6 to 55 times the levels of silver found in
clams in other of the San Francisco Bay, After initiating a silver reduction pilot program,
silver concentrations in the clams showed a continual decline. However it is not clear if the
original higher concentrations of silver any negative impacts on the dams.(WEF 1994)
73
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References
Bard: Bard, C.C., et al, "Silver in Photoprocessing Effluents," Joiirnajjtf theJWjtgr ..... Eojl.uiioji_
Control Federation. Vol. 48. 1 976. pp 389-394,
Calif. DHSa: California Department of Health Services, Alternative Technology Section, Toxic
Substances Control Division, "Waste Audit Study; Photoprocessing Industry," 1989.
Calif. DHSb: California Department of Health Services, Alternative Technology Section, Toxic
Substances Control Division, "Reducing California's Metal-Bearing Waste Streams,"
1989,
Cook; Cook. MM, and Lander,, J.A., "Use of sodium borohydride to control heavy metal
discharge in the photographic industry." JQuroajofj^p^
Vol. 5, No, 3,1979, pp 144-147,
Dufficy: Dufficy, T.J. et a!, ''Silver Discharge Regulations Questioned,"
., April 1993, p. 54,
EPA 1976: USEPA, Office of Water, PeyebpnieniPQCUgient for Interim Final Effluent
^ EPA
440/1 -76/0601, July 1976,
EPA 1 980; USEPA, Office of Water, AmbienLWa.ter._Q..u.aiity ..... CrijeriaforSilver. EPA 440/5-80-
071. 1980,
EPA 1 98 1 a; USEPA, Office of Water, Guidance Document for the Control of WatgrPollution in
the: ...... I?hotogmphic.Processing.Ind.us.try. EPA 440/1-81/082-9, April 1981.
FPA 1981b: June 15, 1981 Affidavit of EchardtC. Beck, Assistant Administrator,
EPA, submitted under Natural Resources Defense Council et. al. Versus EPA. 12 ERC
1833 (March 9, 1979)
EPA 1982; USEPA, Office of Water, Fate of Priority Pollutants, in Publicly Owned Treatment
Works. EPA 440/1-82/303, September 1982. p 61.
EPA 1 987; USEPA, Office of Water Enforcement and Permits, Q
^
, December 1 987.
74
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EPA 1991 a: USEPA, Office of Research and Development, G.uide§:|Q_PgliuliQn_£re¥ention:
The.Photoprocessing Industry. EPA/625/7-91/012, October 1991,
EPA 1991 b; USEPA, Office of Research and Development, 3Vasle_Minimization. Opportunity
Assessment: A Photofinishing Facility. EPA/600/2-91/039, August 1991
EPA 1994; USEPA Office of Policy, Planning, and EvaliMtion.,_,SMllJnabjeIndasigj_.EiQni.gtlllg
Strategic Environmental Protection in the Industrial Sector - Photoimaging Industry.
Phase 1 Report. June 1994,
Hcndrickson: Hendrickson, T.N. and Dagon, T.J.; U.S. Patent 3,594,157; July 20,1971; assigned
to Eastman Kodak Company,
Lewis: Lewis, R.J. Sr.[Ed.], CojdjjiseJ_CkemicaLD.ic|iQBag. Twelfth Edition, Van Nostrand
Reinhold Company, 1994,
Kirk: Kirk-Gthmer fEds.j, Encygjggedia of Chemical Technology. Volume 21, 1983. pp 16-23,
Kodak 1980: Eastman Kodak Company, "Recovering Silver from Photographic Materials,"
Publication J-10, 1980,
Kodak 1989a: Eastman Kodak Company, "Choices - Choosing the Right Chemicals for
Photofinishing Labs," Publication J-35,1989.
Kodak 1989b: Eastman Kodak Company, "Disposing of Mini-Lab Effluent," Publication J-205
1989,
Kodak 1990: Eastman Kodak Company, "Disposal and Treatment of Photographic Effluent, In
Support of Clean Water." Publication J-55, 1990.
Pavlostathis: Pavlostathis, S.G. and Jugee, S., "Biological Treatment of Photoprocessing
Waste wafers." .W_ater..g.denc£_andJIechnglQgy. Vol. 29, No, 9, 1994. pp 89-98.
PMA 1995: Marketing Research Department., IhgJ,9M-§5-PMAJiidiis^Tffind^JJ£pflrt, Photo
Marketing Association International (PMA), Nov. 1995.
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California Blight: A New Tracer of Sewage in Coastal Waters," En.¥ir,p..pm-e.Pta}_Scifinc£
Technology. Vol.26, No, 11, 1992. pp 2147-2150
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Management Practice for Silver Dischargers," November 1996.
75
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Sribnick: Sribnick, L., "The Color Darkroom - How to tell when your color chemicals and
printing go bad, and how to them last longer." jQgu|g.,£liQtQgrgpby,. April
1986, p. 18.
WEF 1 994: Water Environment Federation, Pollution Prevention Committee,
^ 1994,
WSS 1993; The Silver Institute. Silver Survey 1993. 1993.
WSS 1996: The Silver Institute. Silver Survey 1996. 1996,
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Appendix A. Calculation of Total United Surface Area of
Photographic Film and Paper Developed for Amateur Market
Surface Area per 24
Rolls Processed 1994: 715,5 million -+ 659 million rolls 35mm 0.440
-* 48.7 million rolls II0/126 0.131
~» 5,01 million rolls Not Available
-> 2,86 million rolls other Not Available
Exposures Processed 1994; 17,58 billion -» 16.65 billion color print
-* 615 million slide
—* 316 million black-and-white
Original Print » Single Prints 53/° o versus Twin Prints 46,6%
« 3 */2 x 5 inch 59.4% versus 4x6 inch 40.6%
Assumptions and Simplifications
* Assume all rolls of 24 exposure, supported by result:
17.58 billion exposures/715.5 million rolls = 24.6 exposures/roll
• Based on information that photoprocessors gain 75% of revenue from original prints and 14%
from reprints and enlargements, assume that surface of reprints and enlargements
is 14/75 or 18,6 % of original print area.
• Include back-and-white photoprocessing in with color, while greatly simplifying the
calculation the only waste affected in calculations is bleach, effected by less than
2 percent.
* All values taken from reference PMA 1995, except per roll values from reference
EPA 199 la.
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35mm: 659 million rolls 35mm x 0.440 ft*/roll 24 exposures = 290 million ff
110/126: 48.7 million rolls 110/126 x 0.131 ft2/roll 24 exposures = 6.37 million ft:
Total: 296 million ft2
Note: Total does not include disc and "other" film area due to lack of surface area/roll data.
CaJc.iil.aiiong£EriQl
59.4% 3 Va x 5: (16,65 billion + 316 million) x 3.5" x 5" x 1 ft2/! 44 in2 x .594 = 1 .22 billion ft2
40.6% 4 x 6: ( 1 6.65 billion + 316 million) x 4" x 6" x 1 ft2/! 44 irr x .406 = Li 5.MUim.ft2
Total; 2.37 billion ft:
Total with twin prints (46,6% of exposures): 2.37 billion ft2 x 1 .466 ~ 3.47 billion ft2
Total with reprints and enlargements (18.6% oi" original prints):
3.47 billion ft2 x 1,186 = 4. 12 billion fr?
A-78
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