DRAFT
DEVELOPMENT DOCUMENT FOR
EFFLUENT LIMITATIONS GUIDELINES
AND STANDARDS OF PERFORMANCE
RUBBER PROCESSING INDUSTRY
PREPARED BY ROY F. WESTON, INC.
FOR UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY
UNDER CONTRACT NUMBER 68-01-1510
DATED: June, 1973
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DRAFT
NOTICE
The attached document is a DRAFT CONTRACTOR'S REPORT. It includes
technical information and recommendations submitted by the Contractor
to the United States Environmental Protection Agency ("EPA") regarding
the subject industry. It is being distributed for review and comment
only. The report is not an official EPA publication and it has not
been reviewed by the Agency.
The report, including the recommendations, will be undergoing
extensive review by EPA, Federal and State agencies, public interest
organizations and other interested groups and persons during the coming
weeks. The report and in particular the contractor's recommended
effluent limitations guidelines and standards of performance is
subject to change in any and all respects.
The regulations to be published by EPA under Sections 30Mb) and 306
of the Federal Water Pollution Control Act, as amended, will be based
to a large extent on the report and the comments received on it.
However, pursuant to Sections 30Mb) and 306 of the Act, EPA will
also consider additional pertinent technical and economic information
which is developed in the course of review of this report by the
public and within EPA. EPA is currently performing an economic
impact analysis regarding the subject industry, which will be taken into
account as part of the review of the report. Upon completion of
the review process, and prior to final promulgation of regulations,
an EPA report will be issued setting forth EPA's conclusions con-
cerning the subject industry, effluent limitations guidelines and
standards of performance applicable to such industry. Judgments
necessary to promulgation of regulations under Sections 30A(b) and
306 of the Act, of course, remain the responsibility of EPA. Subject
to these limitations, EPA is making this draft contractor's report
available in order to encourage the widest possible participation
of interested persons in the decision making process at the earliest
possible time.
The report shall have standing in any EPA proceeding or court
proceeding only to the extent that it represents the views of the
Contractor who studied the subject industry and prepared the infor-
mation and recommendations. It cannot be cited, referenced, or
represented in any respect in any such proceedings as a statement
of EPA's views regarding the subject industry.
U.S. Environmental Protection Agency
Office of Air and Water Programs
Effluent Guidelines Division
Washington, D.C. 20^60
ii
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DRAFT
ABSTRACT
This document presents the findings of an extensive study of the
rubber processing industry by Roy F. Weston, Inc. for the Environmental
Protection Agency, for the purpose of developing effluent limitation
guidelines, Federal standards of performance, and pretreatment standards
for the industry, to implement Sections 30*f, 306, and 307 of the
Federal Water Pollution Control Act, as amended (33 USC 1251, 131^,
and 1316; 86 Stat 816).
Effluent limitation guidelines contained herein set forth the degree
of effluent reduction attainable through the application of the best
practicable control technology currently available and the degree of
effluent reduction attainable through the application of the best
available technology economically achievable, which must be achieved
by existing point sources by July 1, 1977 and July 1, 1983, respectively.
The Standards of Performance for new sources contained herein set
forth the degree of effluent reduction which is achievable through
the application of the best available demonstrated control technology,
processes, operating methods, or other alternatives.
The development of data and recommendations in the document relate to
the overall rubber processing industry, which is divided into two
major groups, tire and inner tube and synthetic rubber, and further
into five sub-categories, on the basis of the characteristics of
the manufacturing processes involved. Separate effluent limitations
were developed for each category on the basis of the level of raw
waste load as well as on the degree of treatment achievable by sugges-
ted model systems. These systems include both biological and physical/
chemical treatment, and for the synthetic rubber sub-categories treat-
ment of the secondary effluent by carbon adsorption.
Supportive data and the rationale for development of the proposed
effluent limitation guidelines and standards of performance are
contained in this report.
iii
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
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DRAFT
CONTENTS
Section page
ABSTRACT j i I
CONTENTS iv
FIGURES vii
TABLES viii
I CONCLUSIONS 1-]
II RECOMMENDATIONS |)-]
Mi INTRODUCTION Ill-l
Purpose and Authority Ill-l
Summary of Methods Used for Development of the
Effluent Limitation Guidelines and Standards
of Performance
General Description of the Industry
Tire and Inner Tube Industry
Tire Manufacture
Inner Tube Manufacture
Synthetic Rubber Industry
General
Synthetic Rubber Production
Emulsion Crumb Production
Solution Crumb Production
Latex Production
Summary
1-2
1-4
1-4
1-4
1-15
1-15
1-15
1-21
I-21
I-27
1-30
1-34
IV INDUSTRY CATEGORIZATION IV-1
Introduction IV-1
Tire and Inner Tube Industry IV-1
Synthetic Rubber Industry IV-7
V WASTE CHARACTERIZATION V-1
Tire and Inner Tube Industry V-1
Synthetic Rubber Industry V-7
General
Emulsion Crumb Rubber Subcategory V-7
Solution Crumb Rubber Subcategory V-11
Latex Rubber Subcategory V-14
Iv
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DRAFT
CONTENTS
(continued)
Section Page
VI SELECTION OF POLLUTION PARAMETERS Vl-1
Tire and Inner Tube Industry Vl-1
Synthetic Rubber Industry VI-3
VII CONTROL AND TREATMENT TECHNOLOGY VI1-1
Survey of Selected Plants VI 1-1
General Approach and Summary VI1-1
Tire and Inner Tube Plants VII-4
Synthetic Rubber Plants VI1-15
Summary of Control and Treatment Technology VI 1-32
Tires and Inner Tubes VI 1-32
In-Plant Control VI 1-32
End-of-Pipe Treatment VI 1-35
Synthetic Rubber VII-3&
In-Plant Control VI 1-36
End-of-Pipe Treatment VI 1-38
VIII COST, ENERGY AND NON-WATER QUALITY ASPECTS VI I 1-1
Tire and Inner Tube Industry VI 1-1
Synthetic Rubber Industry VI 1-7
Emulsion Crumb Sub-category VI 1-7
Solution Crumb Sub-category VI 1-11
Latex Sub-category VI 1-12
IX BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
AVAILABLE-EFFLUENT LIMITATIONS IX-1
Tire and Inner Tube Facilities IX-1
Identification of Best Practicable Control
Technology Currently Available IX-1
Effluent Loadings Attainable With Proposed
Technologies IX-4
Synthetic Rubber Industry IX-5
Identification of Best Practicable Control
Technology Currently Available IX-5
Emulsion Crumb Sub-category IX-5
Solution Crumb Sub-category IX-7
Latex Sub-category IX-8
Effluent Loadings Attainable With Proposed
Technologies IX-8
Emulsion Crumb Sub-category IX-8
Solution Crumb Sub-category IX-9
Latex Sub-category IX-9
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DRAFT
CONTENTS
(continued)
Section Page
X BEST AVAILABLE TECHNOLOGY LIMITATIONS ECONOMICALLY
ACHIEVABLE—EFFLUENT LIMITATIONS X-1
Tire and Inner Tube Industry X-1
Synthetic Rubber Industry X-2
Identification of Best Practical Control
Technology Currently Available X-2
Emulsion Crumb Sub-category X-2
Solution Crumb Sub-category X-5
Latex Sub-category X-5
Effluent Loading Attainable with Proposed Technologies X-6
Emulsion Crumb Sub-category X-6
Solution Crumb Sub-category X-6
Latex Sub-category X-7
XI NEW-SOURCE PERFORMANCE STANDARDS XI-1
Tire and Inner Tube Production Facilities XI-1
Synthetic Rubber Industry XI-1
Pretreatment Recommendations XI-2
Tire and Inner Tube Industry XI-2
Synthetic Rubber Industry XI-2
XII ACKNOWLEDGEMENTS XI1-1
XIII REFERENCES XII 1-1
XIV GLOSSARY XIV-1
XV METRIC UNITS AND CONVERSION FACTORS XV-1
VI
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DRAFT
FIGURES
Figure No. Title Page No.
I I 1-1 Flow Diagram for Typical Tire and
Camelback Production Facility I I 1-8
I 11-2 Flow Diagram for a Typical Inner Tube
Production Facility 111-16
I 11-3 General Water Flow Diagram for an Emulsion
Polymerized Crumb Rubber Production
Facility 111-22
III-** General Water Flow Diagram for a Solution
Polymerized Crumb Rubber Production
Facility 111-28
I I 1-5 General Water Flow Diagram for an Emulsion
Latex Rubber Production Facility 111-33
IV-1 Location of Tire Manufacturing Plants,
Production Greater than 20,000 Units/Day,
and Synthetic Rubber Production Plants,
Production Greater than 60,000 Long Tons/
Day, Within the U.S., 1972 " IV-1*
VI1-1 Plant J: Chemical Coagulation and Clarifi-
cation Plus Sludge Handling System Followed
by Bio-Oxidation Treatment VM-17
VM-2 Plant K: Air Flotation and Bio-Oxidation
Wastewater Treatment Facility VII-20
VI1-3 Plant N: Activated Sludge Wastewater
Treatment Facility VI1-2?
IX-1 Hypothetical Wastewater Segregation and
Treatment Facility for Tire and Inner
Tube Plants IX-3
IX-2 Hypothetical End-of-Pipe Secondary Wastewater
Treatment Facility for Synthetic Rubber
Plants IX-6
X-l Hypothetical End-of-Pipe Advanced Wastewater
Treatment Facility for All Sub-categories
of Synthetic Rubber Plants X-3
vil
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DRAFT
TABLES
Table No. Title Page No.
I I 1-1 U.S. Tire and Inner Tube Production from
1967-1971 I I 1-6
I I 1-2 Summary of Potential Process-Associated
Wastewater Sources from the Tire and
Inner Tube Industry 111-14
I I 1-3 U.S. Synthetic Rubber Production by Type
for 1967-1971 and the Projected Growth
Rate to 1980 I M-18
I I 1-4 Families of Synthetic Rubbers Included in
SIC 2822, Polymerization Processes, and
Annual U.S. Production (1972) 111-20
IM-5 Summary of Potential Process-Associated
Wastewater Sources from Crumb-Rubber
Production via Emulsion Polymerization
Processing I 11-26
I I 1-6 Summary of Potential Process-Associated
Wastewater Sources from Crumb-Rubber
Production via Solution Polymerization
Processing . 111-31
I I 1-7 Summary of Potential Process-Associated
Wastewater Sources from Latex Production
via Emulsion Polymerization Processing I I 1-35
IV-1 Major Tire Production Facilities in the
United States IV-3
V-l Raw Waste Loads of Untreated Effluent from
Tire and Inner Tube Facilities V-2
V-2 Average Values of Raw Waste Loads for Tire
Industry V-4
V-3 Raw Waste Loads of Process Wastewaters from
Tire and Inner Tube Facilities V-5
viii
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DRAFT
TABLES
(Continued)
Table No. Title Page No.
V-4 The Sources and Characteristics of Process
Wastewaters from the Tire and Inner
Tube Industry V-6
V-5 Raw Waste Loads for Emulsion Crumb Rubber
Plants V-8
V-6 Raw Waste Loads of the Principal Individual
Wastewater Streams in an Emulsion Crumb
Rubber Plant " V-10
V-7 Raw Waste Loads for Solution Crumb Rubber Plants V-12
V-8 Raw Waste Loads for Latex Rubber Plants V-15
VI 1-1 Wastewater Control and Treatment Technologies
at Exemplary Tire and Inner Tube Plants VI1-2
VI 1-2 Wastewater Control and Treatment Technologies
at Exemplary Synthetic Rubber Plants VI1-3
VI I 1-1 Estimated Wastewater Treatment Costs
- Old Tire and Inner Tube VI 11-3
VI I 1-2 Estimated Wastewater Treatment Costs
- New Tire VI 11-4
VIM-3 Estimated Wastewater Treatment Costs
- Emulsion Crumb Rubber VI I 1-10
VIII-U Estimated Wastewater Treatment Costs
- Solution Crumb Rubber VI I 1-13
VI11-5 Estimated Wastewater Treatment Costs
- Latex Rubber VI I 1-15
ix
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DRAFT
SECTION I
CONCLUSIONS
Two major and distinct categories exist within the rubber processing
industry: 1) the tire and inner tube industry; 2) the synthetic rubber
industry.
For the purpose of establishing limitations, the tire and inner tube
industry has been sub-categorized according to the age of the production
facility. Waste loads and costs of control technologies substantiate
this. Factors such as the manufacturing process, final product, raw
materials, plant size, geographic location, air pollution equipment,
and the nature and treatability of wastewaters do not justify further
sub-categorization of this industry group.
Process wastewaters for both sub-categories of the tire and inner tube
industry include discharges of solutions used in the manufacturing pro-
cess, washdown of processing areas, run-off from storage areas, and
spills and leakage of cooling water, steam, processing solutions, or-
ganic solvents and lubricating oils. Primary pollutants in these
wastewaters are oil and grease and suspended solids.
In the tire and inner tube industry, the emphasis of present environ-
mental quality control and treatment technologies is placed on the
control of particulate emission and the reduction, of pollutants in
non-process wastewaters. Control and treatment of many process waste-
waters has been given secondary priority. As a result, no adequate
overall control and treatmen technology is employed by plants within
the industry. A treatment system, practicable and available to the
industry, has therefore been proposed for both sub-categories. It
encompasses a combination of the various technologies employed by
the different segments of the industry to control one or more con-
stituents in the process wastewaters.
Proposed effluent limitations and standards for the best practicable
control technology currently available (Level 1) are:
Suspended Solids 0.064 kg/1000 kg raw material
Oil and Grease 0.008 kg/1000 kg raw material
No additional reduction is proposed for Level II limitations and
standards or for new sources coming on stream after the guidelines
are put into effect.
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
1-1
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DRAFT
For the purpose of establishing effluent limitations guidelines and
standards of performance, the synthetic rubber industry has been
sub-categorized, on the basis of processing techniques, product type,
and wastewater characterizations, into three separate sub-categories:
1. Emulsion crumb
2. Solution crumb
3. Latex
All three sub-categories generate wastewaters which contain the same
constituents. However, the concentration and loading of these con-
stituents, termed "raw waste load", vary between the sub-cateogories.
The significant wastewater constituents are COD, BOD, suspended solids,
and oil and grease. Latex production wastewaters, although lower in
flow per unit of production than the other two categories, have the
highest raw waste loads.
The wastewater parameters selected to be the subject of the effluent
limitations are COD, BOD, suspended solids, and oil and grease. These
parameters are present in the wastewater as a result of organic con-
tamination. Heavy metals or toxic materials were not found in
significant quantities in synthetic rubber wastewaters.
Existing control and treatment technology, as practiced by the industry,
emphasizes end-of-pipe treatment rather than in-plant reductions. This
is because in-plant modifications which might lead to improved waste-
water management appear to adversely affect processing techniques or
quality of the final product.
Current treatment technology for both emulsion crumb and latex plants
involves primary clarification with chemical coagulation of latex
solids, followed by biological treatment. As an alternative to chemi-
cal coagulation, air flotation clarification of primary and secondary
solids is successfully practiced. Biological treatment systems in-
clude activated sludge plants and aerated lagoon and stabilization
pond systems. Level I control .and treatment technology for emulsion
crumb and latex plants has been defined as equivalent to chemical
coagulation and biological treatment.
Current treatment technology for solution crumb requires conventional
primary clarification of rubber solid fines followed by biological
treatment. Existing biological treatment systems employ aerated lagoon
and stabilization pond systems or activated sludge plants. Level 1
control and treatment technology for solution 'crumb production facili-
ties has been defined as equivalent to primary clarification and
biological treatment.
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
1-2
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DRAFT
Level II technology for the three sub-categories has been defined as
equivalent to dual-media filtration followed by activated carbon treat-
ment of the effluent from the biological treatment system to achieve
acceptable COD removal. The applicability of this technology for
Level II is based on very limited data. The performance capabilities
of the proposed Level II treatment systems must be confirmed by further
testing and evaluation before approval of this document.
Level III control and treatment has been defined as identical to
Level II; that is, equivalent to activated carbon adsorption treatment
of the secondary effluent.
The proposed effluent limitations and standards of performance for
plants within the three synthetic rubber sub-categories can be sum-
marized as follows, expressed as kilograms of pollutant- per 1,000
kilograms of production:
Level 1
Emulsion Crumb Solution Crumb Latex
Plants Plants Plants
kg/1,000 kg kg/1,000 kg kg/1,000 kg
COD 8.00 3.94 6.85
BOD 0.40 0.40 0.34
Suspended solids 0.65 0.65 0.55
Oil and Grease 0.16 0.16 0.14
Level I I and Level I 11
Emulsion Crumb Solution Crumb Latex
Plants Plants Plants
kg/1,000 kg kg/1,000 kg kg/1,000 kg
COD 2.08 2.08 1.78
BOD 0.08 0.08 0.07
Suspended Solids 0.16 0.16 0.14
Oil and Grease 0.08 0.08 0.07
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
1-3
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DRAFT
SECTION II
RECOMMENDATIONS
Implicit in the recommended guidelines for the tire and inner tube
industry is the fact that process wastes can be isolated from non-process
wastes such as utility discharges and uncontaminated storm runoff. Segre-
gation of process sewers is therefore the first recommended step in the
accomplishment of the reductions in oil and suspended solid loading neces-
sary to meet the guidelines. Treatment of process wastewaters in a com-
bined process/non-process system is ineffective due to dilution by the
relatively large volume of non-process wastewaters.
It is further suggested that uncontaminated waters, such as storm run-
off, be segregated from outdoor areas where the potential exists for
contamination by oil or solids. This would include roofing and curb-
ing of storage areas and the collection and treatment of runoff which
cannot be isolated from such areas.
The training of operators and maintenance personnel is important in
any control technology. Negligent dumping of various processing solu-
tions and lubricants into unsegregated drains within the plant must be
eliminated or at least severely diminished. Washdown of potentially
contaminated areas must be eliminated whenever possible. The number
and location of in-plant drains should be kept at a minimum, to reduce
the possibility of process wastewater contamination to as few sources
as possible.
Wet air-pollution equipment should be kept to a minimum. Discharges
from wet equipment already in service should be recycled when possible.
The use of dry-type pollution equipment is consistent with recovery
efficiencies and prevention of wastewater control problems.
In-plant modifications which will lead to reductions in wastewater
flow, increased quantity of water used for recycle or reuse, and im-
provement in raw wastewater quality should be implemented providing
that these modifications have minimum impact on processing techniques
or product quality.
End-of-p!pe treatment technologies equivalent to secondary treatment
should be applied to the wastewaters from all synthetic rubber sub-
categories to achieve Level I standards. For emulsion crumb and latex
plants, chemical coagulation and clarification should be provided prior
to secondary treatment.
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
II - 1
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DRAFT
To achieve Level II standards, end-of-pipe treatment technologies equiva-
lent to activated carbon adsorption of secondary treatment effluent is
required on all wastewaters originating in synthetic rubber plants.
Confirmatory tests are necessary to insure that activated carbon adsorp-
tion is applicable to secondary effluent wastewaters from synthetic
rubber plants. These tests should be performed and evaluated prior
to approval by EPA of this document and its findings.
The evaluation of carbon adsorption techniques on synthetic rubber plant
wastewaters should include investigation into the character of the re-
fractory or non-biodegradable portion of the organics in the raw waste
load. These investigations should be aimed at minimizing their presence
in the wastewater as well as changes in their chemical or molecular
structure to make them amenable to biological oxidation or alternative
treatment or removal methods.
Level III control and treatment standards, to be applied to new sources,
are identical to Level II for all synthetic rubber sub-categories; that
is, equivalent to activated carbon treatment of secondary treatment
effluent.
The treatment, control theory, and effluent guideline recommendations
for non-process wastewaters, such as boiler blowdowns, cooling tower
blowdowns, and water treatment plant wastes, in the rubber processing
industry should be covered by the Steam - Electric Power Generation
and Water Treatment effluent guideline documents or by a separate EPA
study.
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
11-2
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DRAFT
SECTION I I I
INTRODUCTION
Purpose and Authority
Section 301(b) of the Act requires the achievement, by not later than
July 1, 1977. of effluent limitations for point sources (other than
publicly-owned treatment works) which are based on the application of
the "best practicable control technology currently available" as defined
by the Administrator pursuant to Section 304(b) of the Act. This best
practicable control technology will be referred to as Level I Control
and Treatment Technology.
Section 301(b) also requires the achievement, by not later than July 1,
1983, of effluent limitations for point sources (other than publicly-
owned treatment works) which are based on the application of the "best
available technology economically achievable" which will result'in
reasonable further progress toward the national goal of eliminating
the discharge of all pollutants, as determined in accordance with
regulations issued by the Administrator pursuant to Section 30Mb) to
the Act. The best available technology economically achievable as
stated above will be called Level I I Control and Treatment Technology.
Section 306 of the Act requires the achievement by new sources of a
Federal standard of performance providing for the control of the dis-
charge of pollutants that would reflect the greatest degree of effluent
reduction which the Administrator determines to be achievable through
the application of the "best available demonstrated control technology,
processes, operating methods, or other alternatives", including, where
practicable, a standard permitting no discharge of pollutants. The best
available control technology for new sources as discussed above is to be
termed Level I I I Control and Treatment Technology.
Section 30Mb) of the Act requires the Administrator to publish, within
one year of enactment of the Act, regulations providing guidelines for
effluent limitations setting forth:
1. The degree of effluent reduction attainable through the ap-
plication of the best practicable control technology currently
available.
2. The degree of effluent reduction attainable through the ap-
plication of the best control measures and practices achievable
(including treatment techniques, process and procedure in-
novations, operation methods, and other alternatives).
111-1
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DRAFT
The regulations proposed herein set forth effluent limitations guidelines
pursuant to Section 30A (b) of the Act for the tire and inner tube and the
synthetic rubber subcategories of the Rubber Processing Industry.
Section 306 of the Act requires the Administrator, within one year after
a category of sources is included in a list published pursuant to Section 306(b)
(1) (A) of the Act, to propose regulations establishing Federal standards
of performances for new sources within such categories. The Administrator
published, in the Federal Register of January 16, 1973 (38 F.R. 162A) , a
list of 27 source categories. Publication of the list constituted announce-
ment of the Administrator's intention of establishing, under Section 306,
standards of performance applicable to new sources within the tire and
inner tube and synthetic rubb'er subcategories of the rubber processing
industry which were included in the list published on January 16, 1973.
The guidelines in this document identify (in terms of chemical, physical,
and biological characteristics of pollutants) the level of pollutant
reduction attainable through the application of the best practicable con-
trol technology currently available (Level I), and the best available
technology economically achievable (Level II). The guidelines also
specify factors which must be considered in identifying the technology
levels and in determining the control measures and practices which are
to be applicable within given industrial categories or classes.
in addition to technical factors, the Act requires that a number of other
factors be considered, such as the costs or cost-benefit study and the
non-water quality environmental impacts (including energy requirements)
resulting from the application of such technologies.
Summary of Methods Used for Development of the Effluent
Limitations Guidelines and Standards of Performance
The effluent limitations guidelines and standards of performance proposed
herein were developed in a stepwise manner.
The development of appropriate industry categories and subcategories
and the establishment of effluent guidelines and treatment standards
require a sound understanding and knowledge of the rubber industry, the
processes involved, water use, recycle and reuse patterns, characteristics
of wastewater, the respective raw waste loadings, and the capabilities
of existing control and treatment methods.
Initial categorizations and subcategorizations were based on raw materails
used, product produced, manufacturing process employed, and other factors
such as plant age. Published literature was consulted to verify the raw
waste characteristics and treatabi1ities in order to support the initial
industry categorizations and subcategorizations.
111-2
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DRAFT
The raw waste characteristics for each tentative subcategory were then
fully identified. Factors considered in this analysis were: the supply
and volume of water used in the process employed; the sources of waste
and wastewaters in the plant; and the constituents, including thermal,
of al 1 wastewaters together with those contaminants which are toxic
or result in taste, odor, and color in water or aquatic organisms. The
constituents of wastewaters which should be subject to effluent limitations
guidelines and standards of performance were identified.
The full range of control and treatment technologies existing within each
subcategory was identified. This involved an identification of each distinct
control and treatment technology (including both in-plant and end-of-pipe
technologies) which are existent or capable of being designed for each
subcategory. It also included an identification in terms of the amount
of constituents (including thermal), the chemical, physical, and biological
characteristics of pollutants, and the effluent level resulting from the
application of each of the treatment and control technologies. The prob-
lems, limitations/reliability of each treatment and control technology,
and the required implementation time were also identified. In addition,
the non-water quality environmental impact, such as the effects of the
application of such technologies upon other pollution problems (including
air, solid waste, noise, and radiation) was also identified. The energy
requirements of each of the control and treatment technologies were iden-
tified as well as the cost of the application of such technologies.
The information, as outlined above, was then evaluated in order to deter-
mine what levels of technology constituted the "best practicable control
technology currently available" (Level I), the "best available technology
economically achievable" (Level II), and the "best available demonstrated
control technology, processes, operating methods, or other alternatives
for new sources" (Level III). In identifying such technologies, various
factors were considered. These included the total cost of application of
technology in relation to the effluent reduction benefits to be achieved
from such application, the age of equipment and facilities involved, the
process employed, the engineering aspects of the application of various
types of control technique process changes, the non-water quality environ-
mental Impact (including energy requirements), and other factors.
Raw wastewater characteristics and treatability data, as well as infor-
mation pertinent to treatment reliability and cost evaluations, were
obtained from several sources, including: EPA research information,
published literature, Corps of Engineers Permit to Discharge Applications,
industry historical data, and expert industry consultation. On-site
visits and interviews were made to exemplary tire, inner tube, and
synthetic rubber production plants throughout the United States to con-
firm and supplement the above data. All references used in the develop-
ment and preparation of the guidelines for effluent limitations and
standards of performance, as implied by Levels I, II, and III Control
and Treatment Technologies, are included in Supplement B to this document.
111-3
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DRAFT
General Description of the Industry
The categories of the rubber processing industry covered by this docu-
ment are the tire and inner tube (SIC 3011) and the synthetic rubber
(SIC 2822). The manufacture of tires and inner tubes utilizes completely
different processing techniques than the production of synthetic rubber.
In a tire or inner tube plant, stock rubber production follows a very
definite formulation or recipe, and is a batching operation.
The mixed stock production is used to produce the four main ingredients
of a tire: tire beads, tire treads, treated fabric, and cord fabric.
These four components enter the tire building plant, where a significant
amount of hand and machine Igy-up is required to produce the green tires.
The synthetic rubber (or vulcanizable elastomer) industry is characteri-
zed essentially by the chemical process and unit operations necessary to
convert the particular monomer or starting-block material into a stabi-
lized, granulated, extruded, or baled material suitable for more conven-
tional rubber processing. The processes are characterized by separation
of unreacted monomer, recovery, purification and recycle of the monomer,
and processing of the converted elastomer. These reactions are normally
carried out batch-wise or batch/continuous.
In view of the fact that these two industry classifications, tire and
inner tube manufacture and synthetic rubber production, differ consider-
ably it is appropriate, from this point on, to describe and evaluate
their water uses and wastewater generations separately.
Tire and Inner Tube Industry
Tire Manufacture
There are many events that have had a significant effect on the tire and
inner tube industry. The first is the discovery, by Charles Goodyear in
1839, that rubber could be cured or vulcanized with sulfur. Thus,
Goodyear was able to overcome the tacky, plastic properties of rubber,
thereby creating a product of commercial applicability (1).
The year 1906 saw the development of the first organic accelerators.
Accelerators are substances which affect the rate of vulcanization. With
the entry of such substances, better products could be produced in a
shorter period of time (1,2).
The next major event to affect the tire industry was the advent of the
Second World War. With the drastic reduction in the supply of natural
rubber, new sources had to be developed. The first substitute was re-
claimed rubber which, by 19^3, had completely replaced natural rubber
as the basic tire material. It was not until the mid 19^0's that syn-
thetic rubber, made available due to a major governmental effort, became
MI-4
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DRAFT
the major substitute for natural rubber. By 19^5, approximately 98 per-
cent of the natural rubber had been replaced by this synthetic substi-
tute (3). The years following the war saw the return, to a great extent,
of natural rubber. However, with the technological boost given the syn-
thetic rubber industry, it would soon again become the larger portion of
the ti re.
The next major event occurred in the mid 1950's and concerned the intro-
duction of tubeless tires as original equipment on new cars. The 1950's
ushered in the first tubeless tire, and major changes were made in tire
design. Butyl rubber became a major constituent of automobile tires.
At the same time, it sent the inner tube industry into a rapid decline.
The total number of inner tube units produced declined from over A9'
million in 1951* to under 25 million in 1955 (A).
The tire industry has had three eras of rapid expansion to coincide with
these events. The post World War I era (1916-1929) brought the first
such development. As the automobile and truck industry expanded, so did
the tire industry. Large capacity tire plants were built in Ohio, Cali-
fornia, and New England. The depression reversed this trend however,
and it v/as not until World War II created an increased demand for tires
that the tire industry again began to expand. New plants were erected
in Ohio, New England, and the South. The third building expansion
started in the early 19&0's and is still proceeding, again occurring
simultaneously with the expansion of the economy.
With the current expansion, tire companies are now located throughout
the United States. Whereas the older plants of the first two expansions
are located in the urban areas of Ohio, California, and New England, the
newer plants are being located in rural areas with no particular emphasis
placed on georgraphy.
Today's tire manufacturer produces many types of tires designed for a
multitute of uses. General product categories include passenger, truck
and bus, farm tractor and implement, and aircraft. Table I I 1-1 presents
a breakdown of these products for the last five years.
The key to the performance of all tires is the selection of the raw rubber
and compounding materials and the proportion of these materials in any
particular part of the tire. Basically, the tire consists of five parts,
namely: the tread, the sidewall, the cord, the bead, and the inner liner.
Each part has different service requirements; therefore, each requires a
different proportion of the raw materials. For example, longevity and
good traction are requirements of the tread, whereas a high degree of
flexibility is the requirement for sidewalls. Basic tire ingredients in-
clude synthetic rubber, natural rubber, various fillers, extenders and
reinforcers, curing and accelerator agents, antioxidants, and pigments.
A wide variety of synthetic rubbers are used inlcuding SBR, polybutadiene,
butyl, polyisoprene, and EPDM. Of the three categories of compounding
111-5
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Table I I 1-1
U.S. Tire and Inner Tube Production (Including Retreading)
for 1967-1971
Tires (in million units)
Year
1967
1968
1969
1970
1971
Passenger
Cars
100.006
128.967
134.540
123.356
138.151
Trucks and
Buses
21.165
25.533
27.211
25.680
28.461
Farm Tractor
and Implement
5.55^
5.741
4.058
3.568
4.099
Ai rcraf t
0.772
1 .040
0.892
0.822
0.731
Mi seel laneous
16.445
17.870
18.421
6.866
9.409
2
Inner Tubes
mi 1 1 ion units
60.479
65.840
60.875
51.534
55.067
Retreading
Rubber2
mill ion pounds
563.307
610.108
598.417
622.413
608.476
- Includes motorcycle, Industrial, garden tractor, and bicycle tires.
Includes all tire classifications.
Source: "Rubber Industry Facts", Statistical Department, Rubber Manufacturers Association, New York.
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DRAFT
materials used, the fillers, extenders and reinforcers are the most im-
portant. These are used:
1. To dilute the raw crumb rubber in order to produce a greater
weight or volume.
2. To Increase the strength, hardness, and abrasion resistance to
the final product.
Of this group, carbon black and oil are the most common. A typical
rubber compound might be described as follows (1):
100 parts rubber
50 parts fillers, extenders, and reinforcers
3.5 parts curing and accelerator agents
8.0 parts antioxidants and pigments
The typical tire manufacturing process consists of the following:
1. Preparation or compounding of the raw materials.
2. Transformation of these compounded materials into the five tire
components.
3. The building, mol-ding, and curing of the final product.
A flow diagram for the typical plant is shown in Figure I I 1-1.
The basic machinery units used in the compounding operation are the
Banbury mixer and the roller mill. A Banbury mixer is a batch-type in-
ternal mixing device and is the hub of this compounding operation. The
Banbury is used for two operations. In the first, the fillers, extenders
and reinforcing agents, and the pigments and antioxidant agents are added
and mixed into the raw rubber stock. The resulting mixture is known as
non-productive or non-reactive rubber stock. Because no curing agents
have been added, this material will have a long shelf life, thus allowing
large quantities of a particular recipe to be made and stored for later
use. In the second operation, the curing and accelerator agents, in
additon to a small quantity of the original list of elements, are added.
This mixture, known as productive or reactive rubber stock, now meets
the particular compounding requirements of its final destination. Since
it contains the curing agents, this mixture has a short shelf life and
will be used almost immediately.
Carbon black and oil are usually added automatically in the compounding
operation. The other compounds (including the raw rubber) are manually
weighed and fed to the Banbury. The reasons for the automatic handling
equipment are:
1. The large quantities of these materials consumed.
2. To ease the maintenance and housekeeping problems created by
both the oil and carbon black.
111-7
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FIGURE Ill-l
FLOW DIAGRAM FOR TYPICAL TIRE AND CAMELBACK PRODUCTION FACILITY
INTAKE WATER
i
WASTEWATER
*
WASTEWATER
LEAKAGES
DIASHDOWN
SLOWDOWN
I
WASTEWATER
REGENERATION
WASTE
I
WASTEWATER
•ASTEWATER
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DRAFT
Carbon black is a finely divided amorphous material that has the con-
sistency of dust. Once left unconfined, it creates a massive air pol-
lution problem. The compounding area is equipped with air pollution
equipment to control this problem. Normal procedure is to use a bag
house.
After mixing, the compound is sheeted out in a roller mill, extruded
into sheets, or pelletized. The process depends on the type of batch
(reactive or non-reactive) and the manufacturer. Pelletizing of a non-
reactive batch enables the weighing and mixing of the reactive stock to
be done automatically. The reactive compounded rubber is always sheeted
out.
The sheeted material is tacky and must be coated with a soapstone solu-
tion. This solution is a slurry which, when allowed to dry on the sheet-
ed materials, prevents them from sticking together during storage.
Because it is a slurry the soapstone solution is usually recirculated.
Releasing the material into a wastewater stream would create a difficult
solids problem. Spills in the soapstone area are common and do create a
maintenance and wastewater problem.
If a manufacturer wishes to exclude soapstone in his final effluent, he
must provide a method for coping with these spills. Current techniques
include the blocking of all drains in the area, diking of the area, and
the use of steel grates on the floors. The diking and sealing of drains
prevents the slurry from entering the drainage system. The use of steel
grates helps decrease the risk of workers slipping on spilled soapstone.
Maintenance and housekeeping problems in this area are further compli-
cated by the leakages of oil and water from the oil seals in the mills,
and oil and dust from the dust ring seals of the Banburys. Each has the
potential to become a wastewater pollutant if allowed to mix with the
cooling water discharges or to be washdowned and discharged without
treatment.
The rubber stock once compounded and mixed must be molded or transformed
into the form of one of the final parts of the tire. This consists of
several parallel processes by which the sheeted rubber and other raw
materials, such as cord and fabric, are made into the following basic
tire components: tire beads, tire treads, tire cords, and tire belt
(fabric). Tire beads are coated wires inserted in the pneumatic tire at
the point where the tire meets the steel rim (on which it is mounted);
they insure a proper (and possibly air tight) seal between the rim and
the tire (2). The tire treads are the part- of the tire that meets the road
surface; their design and composition depend on the use of the tire.
Tire cords are woven synthetic fabrics (rayon, nylon, polyester) im-
pregnated with rubber; they are the body of the tire and supply it with
most of its stregth. Tire belts stabilize the tires, prevent the lateral
I I 1-9
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DRAFT
scrubbing or wiping action that causes tread wear, and reduce heat build
up, a major cause of tread wear (2).
In the formation of tire treads, the rubber stock as it is received from
the compounding section is manually fed to a warm-up roller mill. Here
the rubber is heated and further mixed. Heat is provided by the con-
version of mechanical energy. Temperature control is provided by the
use of cooling water within the rolls of the mill.
The heated stock passes from the warm-up mill to a strip-feed mill where
it receives its final mixing. This mill is also cooled to control the
temperature of the stock. The stock is peeled off the rollers of the
mill in a thin strip which is. fed continuously to ah extruder. The mix-
ing of the stock in these mills insures that the final tread will have
homogeneous properties. The heating or temperature control of the stock
is necessary to insure a proper extrusion with a minimum consumption of
power (2).
At the extruder, two types of rubber stocks originating from two-differ-
ent strip mills are joined together to form the tire tread and sidewalls.
The tread leaves the extruder as a continuous trip while still hot and
therefore tacky. Next a cushioning layer is attached to the lower side
of the tread. The tread is then cut to the proper width, cooled in a
water trough, labeled, cemented, and then cut to the proper length.
Trimmings are either manually or automatically transferred back to the
proper strip-feed mill and reprocessed. Having been cut, the ends are
cemented, and the tread is placed in a "tread book" and sent to the tire
buiIding machines.
Wastewater problems in this area arise from the spillage of the solvent
base cements, from oil and water leakages from the various mills, and
from accidental overflows from the cooling water system. The cooling
water overflow would not normally be a problem since the rubber tread is
relatively inert and therefore does not contaminate the water. However,
it does serve as a washdown agent for an area contaminated with the ce-
ments and oils.
To produce tire cords and belts, rubber stock must be impregnated onto a
pretreated fabric. The fabric is let off a roll, spliced onto the tail
of the previous roll (either adhesively or by a high-speed sewing machine),
and fed under controlled tension (via a festooner) to a latex dip tank.
After dipping and while still under tension, the fabric is fed past vacu-
um suction lines or rotating beater bars to remove the excess dip before
the fabric rises through a drying and baking oven.
After pretreatment, and still under tension, the fabric is passed through
a calendering machine where rubber is impregnated into the fabric. The
rubber fabric is next cooled by large water or refrigerant cooling drums;
after cooling, the tension can be released. This treated fabric is still
111-10
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DRAFT
not ready for the tire building operation. To achieve the proper bias
it must be cut to the proper angle and length, and then spliced together
again. The angle and length will vary depending on the size of the tire
for which it is used and whether it is a cord or belt. Once spliced to-
gether, the fabric is rolled in cloth and sent to tire building.
The rubber used to impregnate the fabric proceeds through an operation
similar to that of the tread process. It passes through both a warm-up
mill and a strip-feed mill prior to impregnation onto the fabric. Waste-
water problems in this area arise due to the latex dripping operation
and to problems with oil and water leaks and spillages which are similar
to those of the tread process.
Many tire manufacturers are transferring their latex dip operations from
individual plants to one large central facility. In most cases, the
reasons behind such a decision are as follows:
1. A minimal dipping operation requires a large capital expenditure.
2. The fabric dipping and coating operation is one of the fastest
operations in the plant and, as such, is readily capable of
over-supplying the plant with fabric.
3. Dipped fabric is not that more expensive to ship then undipped
fabric.
4. The maintenance and housekeeping requirements of the dip oper-
ation are limited to one facility.
In the processing of rubber stock to tire beads, the rubber is extended
onto a series of copper-plated steel wires, then cemented, wrapped, and
cut. The rubber stock is pretreated, as before, in a warm-up mill and
strip-feed mill. Excess rubber is trimmed from the bead before it leaves
the extruder and is fed back to the strip feed mills. To apply cement
the coated wire is passed through a trough or set of brushes. The ce-
ment is necessary to insure the proper adhesive of the bead when it is
wrapped.
Wastewater problems can arise due to the use of the mills or from the
spillage or overflow of the cement. They will be similar in nature to
those found in this tread formation process.
The inner lining of the two is formed by calendering or extruding the
rubber stock in a manner similar to either the formation of cord fabric
or tread rubber. It is this inner liner that enables a tire to be tube-
less since it is light and relatively air impervious.
The tire is built up as a cylinder on a collapsible, round rotating drum.
First the inner liner is applied to the drum. Then layers of cord are
111-11
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DRAFT
applied, one layer tying the beads together in one direction and another
layer in the other direction. The beads are stiched to the tire by
folding over the ends of the cord fabric. Next the tire belt fabric is
laid onto the cord. Finally the tire tread is placed over the cords and
fabric and wrapped around the beads. The cylinder is removed. These
green tires (uncured tires) are now ready for final processing.
Washdown of solvents from this area can create a wastewater problem; how-
ever, this is normally dry and therefore very pollution free. Before
molding and curing, the green tire must be sprayed with release agents.
These agents aid in the release of air from the tire during molding and
of the tire from the mold after curing. Both water- and solvent-based
spray are used. Excess spray is released to the atmosphere. Most plants
now place the tires in a hood before spraying in order to meet federal
air quality standards.
The potential for wastewater streams exist due to the possibility of sol-
vent spills within this area. If wet scrubbers are used to scrub the ex-
cess spray from the air, another wastewater stream will exist. .
The tire is molded and cured in an automatic press. Here an inflatable
.rubber bladder bag is blown up inside the tire, causing the tire to take
its characteristic doughnut shape. The mold is simultaneously closed
over the shaped tire. Heat is applied by steam via the mold and bladder
bag. Excess rubber and trapped air escape through weepholes. After a
timed, temperature-controlled cure, the press is cooled, the bladder is
deflated via a vacuum, and the tire is removed. The tire is next in-
flated with air and left to cool in the atmosphere. This last inflation
insures product quality and uniformity by allowing the tire to "set up"
or achieve the final limits of its cure under controlled conditions.
Because of the large number of presses in the typical plant, there is
always the potential for a mold to leak or for a bladder to break. This
water is released and scavenges some of the large amounts of lubricating
oil used in this area. This oily water creates a water contamination
problem if it is discharged.
After the molding and curing operations, the tire proceeds to the grind-
ing operation where the excess rubber which escaped through the weepholes
is ground off. If the tire is designated to be a whitewall, additional
grinding is performed to remove a black protective strip. More expen-
sive tires receive further grinding of the tread in order to balance the
tire.
The weepholes which are ground off are relatively large particles of
rubber which fall to the floor and are swept up. Their final destina-
tion is a landfill. The grindings from the white sidewall operation are
relatively small and will stay airborne for long periods of time. The
industry generally uses a particulate collection device such as cyclone
111-12
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DRAFT
or wet scrubber to control these emissions. The discharge from a wet
scrubber will have a high solids content and will therefore be a waste-
water problem. The balancing operation suffers the same problems as the
white sidewall grinding operation.
After the grinding operations, the wh'itewall portion of a tire receives
a protective coat of paint. The paint is generally water based. This
operation usually occurs in a hooded area. Again, any wet air pollution
equipment or runoff due to over spraying of the paint will create pol-
lution problems. After inspection and possibly some final repairs, the
tire is ready to be shipped.
Table I I I-2 presents a review, of the potential sources of wastewater
streams as discussed above.
The discussion thus far has described a typical tire plant, and applies
most readily to the production of the passenger tire. There are several
variations. The first of these is due to the production of truck and in-
dustrial tires. Truck tires tend to have a greater amount of natural
rubber in their treads. Natural rubber, as received in the plant, is
much harder to handle than synthetic rubber. Additional roller mills
are needed to break up and soften the rubber before it enters the
Banbury mixer. There are also major differences in the building and
molding of the tires as the larger sizes are approached. The building
of a "giant off-the-road tire" requires the services of two men each for
a half a day, whereas the passenger tire can be built in less than 5
minutes. Larger tires are cured in giant molds which are not automati-
cally operated. Cranes or hoists are required to open and close this
mold. Curing can take up to 2k hours. Hot water, instead of steam, is
used in the curing operation. The process variations associated with
truck and industrial tire production do not have a significant effect on
the quantity and quality of the wastewaters generated when compared to
those from automobile tire production.
Another variation in the typical tire production is the manufacture of
camelback. Camelback is tread used for tire retreading (2). It is pro-
duced in the same manner as tread used for new tires'. (See flow diagram,
Figure 111-1.)
Camelback production operations are usually part of a tire production
facility feeding off the same machinery. Wastewater problems will be
similar to those already discussed.
Radial tire production offers another variation to the overall process.
Radial tires, like truck tires, contain more natural rubber, thus re-
quiring more machinery in the compounding area. Whereas bias-ply tires
are built in the form of a hollow cylinder, radial tires are built in
the doughnut shape of the final product. Like truck tires, radial tires
are cured using hot water instead of steam. Again wastewater problems
will be very similar to those of the typical passenger tire manufacture.
111-13
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Table IN-2
Summary of Potential Process-Associated Wastewater
Sources from the Tire and Inner Tube Industry
Plant Area
Oil Storage
Compounding
Bead, Tread, Tube
Formation
Cord and Belt
Formation
Green Tire Painting
Molding and Curing
Tire Finishing
Source
Run off
Washdown, spills, leaks,
discharges from wet air
pollution equipment
Washdown, spills, leaks
Washdown, spills, leaks
Washdown, spills.air
pollution equipment
Washdown, leaks
Washdown, spills, air
pollution equipment
Nature and Origin of Wastewater Contaminants
Oil
Solids from soapstone dip tank
Oil from seals in roller mills
Oil and solids from Banbury seals
Solids from air pollution equipment discharge
Oil and solvent-based cements from the cementing operation
Oil from seals in roller mills
Organics and solids from dipping operation
Oil from seals, in roller mills, calenders, etc.
Organics and solids from spray painting operation
Soluble organics and solids from air pollution
equipment discharge
Oil from hydraulic system
0 i1 from presses
Solids and soluble organics from painting operation
Solids from air pollution equipment discharge
o
30
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DRAFT
Inner Tube Manufacture
Inner tube manufacture is very similar to tire manufacture in that the
process consists of the following steps:
1. Preparation or compounding of the raw materials.
2. The extension of these compounded materials to form a tube.
3- The building, molding, and curing to form the final product.
A flow diagram for the typical process is shown in Figure I I 1-2.
The basic machinery used in the compounding operation is identical with
that used in the tire manufacture, namely, Banbury mixers and roller
mills. Both non-reactive and' reactive stocks are used. Differences
arise since inner tubes are manufactured primarily from butyl rubbers.
In addition, a soap rather than a soapstone solution is sometimes used
to coat the non-reactive stock. Wastewater problems arising from this
section are identical to those of the typical tire compounding area,
i.e., leakages and dripping of oily and particulate material.
The process by which the tube is formed is similar to the extrusion of
the tread. The compounded rubber is fed to an extruder via a warm-up
mill and strip-feed mill. Here the rubber is extruded into a continuous
cylinder, after which it is cooled and labeled. To keep the inside of
the tube walls from sticking to each other, a dry soapstone powder is
sprayed inside the tube as it is formed in the extruder. After cooling,
the water is blown out of the tube and the same powder is sprayed on the
outside of the tube. Excess powder must be collected in each dry or wet
collection device. If a wet collection device is used, the discharge
will be heavily laden with solids. Other wastewater problems are simi-
lar to those found in the tread formation process of tire manufacture.
Once extruded, the tube must be cut to length and the ends spliced to-
gether. A valve must also be attached. There is no potential waste-
water problem arising from this area of operation.
Once formed, the tube must be molded and cured. Again, this operation \s
very similar to that of the tire manufacture. Wastewater problems in-
clude only water leakage and spills.
After curing, the tube is inspected for defects, packaged and sent to
warehousing and shipping. Table I I I-2 summarizes the potential sources
of wastewater streams as discussed above.
Synthetic Rubber Industry
General
The synthetic rubber industry is responsible for the sythesis of vulcan-
izable elastomers by polymerization or co-polymerization processes. For
II1-15
-------
CARBON
BLACK
STORAGE
FIGURE 1U-2
FLOW DIAGRAM FOR A TYPICAL INNER TUBE PRODUCTION FACILITY
COOLING WATER
RETURN 1
COOLINR
^ COOLING WATER irr^ TOWER
SLOWDOWN
1
COOLING WATER
ror » TUC UT
1
1
1
REGENERATION
WASTE
I
RAW INTAKE
WATER
WASTEWATER
WASTEWATER
RUBBER
AND QRY
COMPOUND
STORAGE
EXTENDER
OIL
STORAGE
SPI'LLS
RUNOFF
I
+
KASTEfATER
-6
\
COMPOUNDING:
R1W
n/itinunY -_--_.
MILLS STOCK
1 L+400L
I
4i LEAKAGE _WB..T
WASKOOWN
SOAP AND
SOAPSTONE
SOLUTIONS
\
SPILLS
LEAKAGE
WASHDOWN
WASTEWATER
TUBE FORMATION
MILLS
"* EXTRUDER UHCUR
COOLING Tt,orc
TANKS TUB£S
NG " [
j
EWATER • Bftiit-^
LEAKAGE WATER
T WASHnOWN
COOLING 1
WATER '
T
WASTEWATER
SUPP
~« *\
STEA*
TUBE
EO ^ SLICING
AND
CURING
— «C» INSPECTION —
PACKAGING
PRODUCT
M» STORAGE
AND
SHIPPIH9
fl$]
I VSTEAM
LEAKAGE
WASHDOWN
BOILER
V
(
BLOWOOWN
i
WASTEWATER
CONOENSATE
RETURN
i
4 MTFR
TREAT
A R**
KENT INTAKE
REGENE'RATION WTER
WASTE}
WASTEWATER
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DRAFT
the purpose of this classification, an elastomer is a rubber-like ma-
terial capable of vulcanization.
The U.S. Synthetic Rubber Industry was fostered by the commencement of
World War II when it was realized that supplies of natural rubber could
be shut off by the enemy. The rubber first chosen for production was
called GR-S (Government Rubber-Styrene) and would now be grouped under
SBR (styrene-butadiene rubber). Since the war the price of natural
rubber has been subject to great fluctuations, whereas the price stabili-
ty of synthetic rubbers has undoubtedly contributed to their acceptance
by the consumer. Since the introduction of GR-S, many new synthetic
rubbers have been synthesized and produced on a commercial scale.
The demand for the various types of synthetic rubber is greatly affected
by the needs of the tire manufacturers. Not only are tire sales impor-
tant, but process and product changes within the tire industry also in-
fluence the relative demands for the various rubbers. For example,
radial tires at present contain considerably more natural rubber than
conventional tires. At this moment, this has little effect on the con-
sumption of synthetic rubber because radial tires constitute a small
percentage of total tire production, but it does illustrate the kind of
factor which can influence synthetic rubber consumption. The U.S. pro-
duction of the principal synthetic rubbers for the last several years
is presented in Table I I I-3 together with the growth projections for the
period between now and 1980. it can be seen that production of SBR-type
rubber overshadows other synthetic rubber. Although the greatest growth
rates over the next several years will be associated with polyisoprene^
and ethylene-propylene terpolymer (EPT) productions, overall the relative
levels of synthetic rubber production will not be appreciably different
from what they are today because the present base productions of polyisoprene
and EPT are considerably lower than that of SBR, the principal synthetic
rubber (5). This supports the assumption that there will be no radical
changes in the industry, its products, and even its production processes
in the foreseeable future.
The synthetic rubbers as listed under SIC 2822 include both the so-
called tire rubbers and the specialty rubbers. The tire rubbers are
typically high production volume commodities, and, as their name suggests,
they are used predominantly by the tire industry. Rubber used in the
tire industry is supplied in a solid form termed crumb rubber. Several
different families of tire rubber are made in order to provide all the
essential and varying properties required in a modern vehicle tire.
Not all tire rubber production is used in tire manufacture however.
Much is used to manufacture rubber hose, belting, electrical wire and
cable, footwear, mechanical rubber goods, and many other rubber-based
products. Due to their superior oil and heat resistance, both nitrile
and neoprene type rubbers are used more for hose, seals, gaskets, and 0-
rings than for tire manufacture. However, because their annual production
111-17
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Table II1-3
.U.S. Synthetic Rubber Production by Type (1,000 Long Tons) for
1967 to 1971 and the Projected Growth Rate to 1980
Ethylene
—
1
00
Years
1967
i r\£.Q
19&0
1969
1970
1971
S-Type
1 ,244
1 ,389
1,403
1,331
1,417
Butyl
11/1
MH
11 o
13
130
118
106
Nitrile
62
'
69
67
65
Polybutadiene
9D1
i.\j i
217
263
280
254
Polyisoprene Pi
____________ i lin_.
109
120
117
•opy lene
75
63
60
Misc.
186
9fi1
201
218
222
Total
1 Q1 9
1 >y > <-
•) i -Ji
t- 1 1 j <
2,250
2,197
2,241
Projected Growth
2.7
5.2
7.0
16.0 to 1975
8.0 to 1980
16.0 to 1975
10.0 to 1980
Includes Polychloroprene (Neoprene) rubber
Sources: Production data from "Rubber Industry Facts", Statistical Dept., Rubber Manufacturers Association.
Growth rate production furnished by Chem System, Inc., New York.
-------
DRAFT
volume is comparable with four of the other five major synthetic rubbers
used in tire manufacture, they will be considered here as tire rubbers.
The tire rubbers are grouped into seven families based on their monomeric
ingredients as shown in Table III-A. The annual U.S. production, poly-
merization process, principal end-use and other family members are also
presented.
By contrast, the speciality rubbers are low production volume commodities
with more diverse compositions and end uses. The largest production
volume family of the speciality rubbers are the butadiene rubbers.
Butadiene rubbers are generally sold in latex form. The production is
similar to the production of all synthetic rubber latexes (2). Epi-
chlorohydrin is solution polymerized with various co-polymers to produce
the family of epichlorohydrin rubbers. The process is similar to that
for solution tire rubbers. Epichlorohydrin rubbers are.used for seals,
gaskets, and 0-rings, etc. (6). The acrylic rubbers are produced by an
emulsion polymerization process similar to the emulsion processes used
for drive-train and axle seals, hose, tubing, and molded parts. Poly-
isobutylene is produced by a solution polymerization process similar to
that for butyl rubber (l). It is used primarily as a blend in caulking
compounds, adhesives, and plastics.
Three of the so-called specialty rubber families (silicone rubbers,
urethane rubbers, and fluorocarbon derivative rubbers) are being studied
as part of the plastics industry and, as such, are not covered in this
document. The chlorinated and chlorosulfonated polyethylene rubbers are
manufactured by processes similar to those employed for the polyethylene
type plastics and are not covered in this document (2). The polysulfide
rubbers are produced by a condensation process which is different from
the general emulsion and solution polymerizations (2). In addition, the
wastewaters generated by polysulfide production are highly contaminated
and deemed more difficult to treat than the wastewaters produced by con-
ventional emulsion or solution polymerization processes. It is therefore
recommended that a separate study be made of the polysulfide rubber sec-
tor of the synthetic rubber industry.
The various methods of production of the synthetic rubber have much in
common. The monomers are not particularly difficult to handle at reason-
able pressures, and suitable inhibitors have been developed to impart
storage stability. Dissipation of the heat of polymerization is frequent-
ly the controlling consideration. Adjustment of reaction rate to dis-
tribute the heat generation over a reasonable period of time, the use of
refrigeration cooling, and operation in dilute media such as emulsions
or solutions are necessary for the adequate control of polymerization re-
actions.
Control of molecular weight and of molecular configuration has become
a very important quality consideration. The ability to control molecular
weight has led to the development of oil-extended rubber. It has been
found that rubber of unusually high molecular weight and normally too
111-19
-------
Principal Synthetic Rubber
Ti re Rubbers
,ren*-Butadiene rubbers ionitri le-Butad iene rubbers (Nitrile)
1 > chl crop rene rubber (Neoprene)
Tire Rubber Sub-Total:
Specialty Rubbers
t a client rubbers
'cMorshydrin rubber
r, 1 !c rubbers
1 icone rubbers
lyurethane rubbers
3
l+
lysulfide rubbers
Specialty Rubber Sub-Total
Synthetic Rubber Total
Annual U.S. Production
(1 ,000 Metric Tons/year)
1.678
!39
368
139
163
169
159
177
2,992
6A
9
2
U
10
14
1
15
10
129
3J2I
Process
Emu 1 s t on
Solut ion
Solution
Solut i on
Solution
Solut ion
Emu Is ion
Emulsion
Emulsion
Solut ion
Enu 1 S i on
Solution
Condensat ion
Condensat ion
Emu Is ion
Post-polyrnertza-
t ion chlor inat ion
Condensation
Principal End-use Other Family Members
Genera) tire use
Tire treads
Tire treads
Tire treads
Inner tubes
General tire use, non-tire EPDH
goods
Hose, seats, gaskets,
0-rings
Chloroprene rubber
Adhesives, dipped goods, Pyr idine-Butadiene
paints rubber
Caul king, adhesives ,
plast ics
cat tape
Solid tires, rollers, Adiprene, Estane, 1 so-
foams, fibers cynate type rubber
Seals, gaskets, 0-ring, Viton, Ftuoro rubber
high temperature service
Wire and cable, shoes. Chlorinated rubber,
linings, paints Hypalon
Sealing, glazing, hose Thiol
* I though Nitrite and Neoprene-type rubbers are not normally termed tire rubber, they are relatively large production volume rubbers and, for convenience.
can be included with the major tire rubbers.
Silicone. Polyurethane and Fluorocarbon derivative rubbers are considered part of the Plastics and Synthetics Industry and are not covered by this
document.
Chlorosulfonated and chlorinated polyethylenes should be considered part of the Plastics and Synthetics Industry. They are not covered b, this
document.
Polvsulfide rubbers are produced by a condensation-type reaction vAich is not directly comparable to either emulsion or solution polymerization.
Per unit of rubber production, generated wast.~aters are of considerably poorer quality and more troublesome to treat than those of e.ther emuls.on
or solution or solution processes. Polysulfide rubber production is not covered by this document. It is recommended that , separate study be mad.
of the ool ysu If i de rubber industry.
Source: "The Rubber Industry Statistical Report" - C.F. Ruebensaal, International Institute of Synthetic Rubber Producers, Inc.
-------
DRAFT
tough to process through factory equipment can be made workable by the
addition of up to 50 parts of petroleum-base oils per 100 parts of rubber.
These extending oils make the rubber easier to process without sacrifice
in physical properties. Another improvement has been the preparation of
black masterbatches, the name given to mixtures of carbon black and rubber
without the curing ingredients. This process is of great importance to^
small manufacturers and tire retreaders who lack facilities for mixing in
carbon black or who wish to avoid atmospheric pollution with the fine
black.
Synthetic Rubber Production
Emulsion Crumb Production
Of the several methods of polymerization employed to produce synthetic
rubber, the two most commonly used processing techniques are polymerization
in homogeneous solution and polymerization in emulsion. Solution polymer-
ization may be considered to include bulk polymerization where excess
monomer serves as a solvent. Emulsion polymerization may be considered
as the bulk polymerization of droplets of monomers suspended in water.
Emulsion polymerization is performed with sufficient emulsifier to main-
tain a stable emulsion. Solution polymerizations generally proceed by
ionic mechanisms. However, polymerization initiators which operate by
ionic mechanisms are usually too reactive to be stable in water; there-
fore, emulsion polymerization systems are initiated by agents which pro-
duce free radicals (2).
Emulsion polymerization is the traditional process for the production of
synthetic rubber. Since World'War II (and for the foreseeable future),
the bulk of synthetic rubber has been produced via emulsion polymerization.
The use of emulsion polymerization systems is common because both high
conversion rates and high molecular weights are possible. In addition,
other advantages are: a high rate of transfer of the heat of polymer-
ization through the aqueous phase, ready removal of unreacted monomers,
and high fluidity even at high concentrations of polymer. The majority
of stvrene-butadiene rubber (SBR), the principal synthetic rubber, is
produced by emulsion polymerization. The emulsion polymer,zation process
Is used to produce either rubber latex or rubber crumb. Crumb is solid
and is usually formed into 75 pound bales.
Figure 11 1-3 shows a generalized materials flow diagram for the continu-
ous production of crumb SBR by the emulsion polymerization Process. This
schematic is essentially typical of all emulsion processes. In the typi-
cal production facility, operation is 2k hours per day, 365 days per
year Each plant consists of several production 1•"« where d,fferent
process recipes can be applied and various types of SBR can be produced,
including non-extended, oil extended, and carbon black masterbatch van-
eties.
I 11-21
-------
FIGURE 111-3
GENERAL WATER FLOW DIAGRAM FOR AN EMULSION POLYMERIZED CRUMB RUBBER PRODUCTION FACILITY
5lE«ATER
TREtTED PROCESS
•HER
sir «
SUPPLt +
»*STEIHE«
EQUIPMENT ^ CLEANUP ^
»»STE*HER »»STE»»TEB
EXTENDER OIL
CARBON BIACH SURRT
fOUIPKEKT'CLEAKUP
I
I
»*STE»»TER
LIVE
STEU
CONOENSIITE
TREATED
PROCESS
IITER
SUPPLY
STREM
It
BOILER
HOUSE
1
IUN
i
*e
I i
J
LER FEED WATER
>
t
VATER RAW INTAKE
UK ITS "U*
BLONDOm
vurEimrEii
Ei»l
REGENERMIOK
IMSTE
»»STE»»TER
-------
DRAFT
Styrene and butadiene (referred to as monomers) are either piped to the
plant from adjacent suppliers, or shipped in by tank car or tank truck.
The monomers are stored in a tank farm which is diked to retain major
monomers spills and leakages and, in the case of fire, to control the
spread of flaming liquid. The fresh monomers are piped to the plant
from the tank farm and, if necessary,' passed through a caustic soda
scrubber before mixing with recycle monomers. Some monomers, such as
butadiene, have inhibitors added to prevent premature polymerization
during shipment and storage. These must be removed before the monomer
can be polymerized. The inhibitor is removed in the caustic scrubber by
the circulation of a caustic soda solution, approximately 20 percent.
The caustic soda solution is discarded periodically or can be subjected
to continual make-up and blow.down.
Soap solution, catalyst, activator, and modifier are added to the monomer
mixture prior to entering the polymerization reactors, the soap solu-
tion is used to produce an emulsion of the monomers in an aqueous medium.
The principal ingredients of this solution are generally a rosin acid
soap and a fatty acid soap. Thy catalyst is a free radical init-iator and
can be a hydroperoxide or a peroxysulfate. The catalyst initiates and
promotes the polymerization reaction. The activator assists in generat-
ing the free radicals more rapidly and at lower temperatures than by
thermal decomposition of the catalyst alone. The modifier is an^ad-^
ditive which adjusts the chain length and molecular weight distribution
of the rubber product during polymerization. It is necessary that all
the above solutions be made with high quality water. Usually city or
well water is deionized for the preparation of the solutions.
The polymerization proceeds stepwise through a train of reactors. The
reactor system is capable of producing either "cold" (AO-*»5°F, 0-15 psig)
or "hot" (122°F, AO-60 psig) rubber. The "cold" SBR polymers, produced
at the lower temperature and stopped at 60 percent conversion, have im-
proved properties when compared to "hot" SBR's. The "hot" process is
the older of the two. For "cold" polymerization, the monomer-additive
emulsion is cooled prior to entering the reactors, generally by using an
ammonia refrigerant cooling medium. Depending on the polymerization tem-
perature, the medium could be chilled brine or chilled water. In ad-
dition, each reactor has its own set of cooling coils, usually contain-
ing ammonia refrigerant, and is agitated by a mixer. The residence t.me
In each reactor is approximately one hour. Any reactor in the train can
be by-passed. The reactor system contributes significantly to the high
degree of flexibility of the overall plant in producing different grades
of rubber. The overall polymerization reaction is ordinarily carried to
no greater than 60 percent conversion of monomer to rubber since the rate
of reaction falls off beyond this point and product quantity beg.ns to
deteriorate. The product rubber is formed in the emulsion phase of the
reaction mixture. The reaction mixture is a milky white emuls.on called
latex.
111-23
-------
DRAFT
Short stop solution is added to the latex leaving the reactors to stop
the polymerization at the desired conversion. Two common short stop
ingredient are sodium dimethyl dithiocarbamate and hydroquinone. The
"stopped" latex is held in blowdown tanks prior to the stripping operation.
The blowdown tanks act as flow regulating holding tanks.
Recovery of the unreacted monomers and their purification is an essential
step in economic synthetic rubber production. Butadiene, which has a lower
boiling point than styrene, is first vacuum stripped from the latex. The
stripping operation is generally carried out in a vacuum flash tank at
about 80-90°F. The butadiene vapors are compressed and condensed before
entering a receiver. A very small quantity of water collects in the
receiver and is discharged periodically. The condensed butadiene is re-
cycled to the feed area and mixed with fresh monomer prior to the polymer-
ization step. Styrene recovery from the latex usually take's place in
perforated plate stripping columns. These operate with steam injection
at approximately 140 F. The steam-styrene vapor mixture is condensed
and sent to a receiver where the styrene and water are decanted. The
top styrene layer is recycled to the monomer feed stage; the bottom layer
of the receiver, which is styrene-laden water, is discharged. Both the
vacuum and steam strippers foul periodically with rubber solids. These
must be removed by hand, followed with both steam or water jets. This
cleaning operation puts the stripper out of commission and produces large
quantities of wastewater.
An antioxidant to protect the rubber from attack by oxygen and ozone is
added to the stripped latex in a blend tank. The latex is now stabilized
and, as a result, different batches, recipes, or dilutions can be mixed.
These mixing operations take place in the blend tanks. The latex is
pumped from the blend tank to the coagulation step where dilute (pH A-4.5)
sulfuric acid and sodium chloride solution are added. The acid brine
mixture is called the coagulation liquor and causes the rubber to pre-
cipitate from the latex. Theoretically, precipitation will occur with
a coagulation liquor consisting of any combination of electrolyte and
dilute acid. However, the quality and intended end use of the rubber
limit the choice of coagulants. For example, some types of "hot" SBR
which are used as insulation covering on electrical wire are coagulated
with an acid-polyamine solution in order to produce a rubber with low
electrical conductivity.
As mentioned earlier, rubber can be extended to improve its properties
by using oils and carbon black. Carbon black and oil can be added to the
latex during the coagulation step to produce a more intimate mixture than
can be obtained by the subsequent addition of these materials^ the
crumb rubber as is the case with conventional rubber compounding. Waste-
waters generated subsequent to the masterbatch operation (addition of
carbon black) are usually black due to colloidal carbon black particles.
The oil is added as an aqueous emulsion, and carbon black is blended
-------
DRAFT
into the latex as an aqueous slurry (approximately 5 percent by weight).
There are various types of extending oils; some are staining and others
non-staining. Non-stained rubber is required for some non-tire uses.
If a non-stained rubber is to be produced, not only must the extender
oil be non-staining, but also lighter-colored soaps, short stops, and
antioxidants must be used.
The coagulated crumb is separated from the coagulation liquor on a
shaker screen. The coagulation liquor is recycled after make-up with
fresh acid and brine and blowdown of part of the diluted liquor. The
screened crumb is resuspended and washed with water in a reslurry tank.
This operation serves to remove extraneous compounds from the rubber,
particularly residual coagulation liquor. The crumb rubber slurry is
then dewatered, generally using a vacuum filter, and the filtrate wash
water is recycled to the reslurry tank for reuse with fresh water make-
up and as an overflow. The overflow is necessary to blowdown accummulat-
ing rubber solids and contaminants. The coagulation liquor blowdown and
crumb slurry water overflows are usually passed through separators.
These facilities, called crumb pits, are generally outside the process-
ing building and trap the floatable crumb rubber. The clarified under-
flow is discharged.
The rinsed and filtered rubber crumb is finally dried with hot air in a
continuous belt or screen dryer. After drying, the rubber is weighed
and pressed in bales and stored prior to shipment. Normally rubber
bales weigh 75 pounds and are wrapped in polyethylene film. The balers
are operated hydraulically with oil or water as the hydraulic fluid.
Due to the jarring baling action and the high hydraulic pressures, fluid
leaks are frequent and, in the case of oil-driven balers, the leaked oil
should be prevented from entering the plant drain system.
In addition to the processing operations described above, other opera-
tions are carried out regularly, though not necessarily continuously,
which generate considerable quantities of wastewater. These include
equipment cleanout and area washdown operations. Principal equipment
cleanouts include the polymerization reactors, blowdown tanks, butadiene
flash tanks, styrene stripping columns, and latex blend tanks. In most
cases, high volumes of wastewater are produced that are laden with un-
coagulated latex solids and are characterized by a milky white appearance.
When the flash tanks and stripping columns are cleaned, the wastewaters
contain rubber solids, due to premature coagulation of the latex, in ad-
dition to uncoagulated latex. Area wash downs are frequent, and the
wash waters pick up primarily latex, rubber solids, and oil. The carbon
black slurrying area is generally contaminated with carbon powder. Area
washdowns and storm run off typically pick up the carbon, resulting in a
fine carbon suspension.
It is opportune at this point to review the potential wastewater sources
in a typical emulsion plant. Table I I I-5 summarizes the principal waste-
waters and the nature or appearance of their constituents.
111-25
-------
Table I I 1-5
Summary of Potential Process-Associated Wastewater Sources from
Crumb Rubber Production via Emulsion Polymerization Processing
Processing Unit
Source
Nature of Wastewater Contaminants
Caustic Soda Scrubber Spent caustic solution
ro
Monomer Recovery
Coagulation
Crumb Dewatering
Monomer Strippers
Tanks and Reactors
Al 1 Plant Areas
Decant water layer
Coagulation liquor overflow
Crumb rinse water overflow
Stripper cleanout rinse water
Cleanout rinse water
Area washdowns
High pH, alkalinity, and color. Extremely
low average flow rate.
Dissolved and ^separable organics.
Acidity, dissolved organics, suspended and
high dissolved solids, and color.
Dissolved organics, and suspended and dissolved
sol ids.
Dissolved organics, and high suspended and
dissolved solids. High quantities of uncoag-
ulated latex.
Dissolved organics, and suspended and dissolved
solids. High quantities of uncoagulated latex.
Dissolved and separable organics, and suspen-
ded and dissolved solids.
-------
DRAFT
Solution Crumb Production
As pointed out earlier, solution polymerization is a newer, less tradi-
tional, process for the commercial production of crumb rubber in the U.S.
Solution polymerization systems permit the use of stereospecific catalysts
of the Ziegler-Natta or alkyl-1ithium' types which have made it possible
to polymerize monomers, such as isoprene or butadiene, in a suitable
organic solvent so as to obtain the cis structure (up to 98 percent)
characteristic of the natural rubber molecule and with a high degree of
regularity. Rubbers with the cis structure are desired since they are
usually rubbery, whereas the trans-configuration is more rigid and
similar to plastics. Cis-polybutadiene, for example, has higher abrasion
resistance than the usual SBR. type and is being used mainly to extend
and partially replace both SBR and natural rubber in tires. Reports in-
dicate that tread wear is improved by up to 35 percent rn a 50-50 blend
of polybutadiene and SBR.
A relative newcomer on the rubber scene is based on the cheap monomers,
ethylene and propylene. Although not stereo-regular, these polymers can
be produced in solution plants and can use similar catalysts. The polymer
chain, based on ethylene and propylene, does not contain sufficient un-
saturation for conventional curing. The incorporation of a third monomer,
usually a diene (thus EPDM - ethylene propylene diene monomer), adds un-
saturation and facilitates conventional curing.
The production of synthetic rubbers by solution polymerization processes
is a stepwise operation, and, in many aspects, is very similar to pro-
duction by emulsion polymerization. There are distinct differences in
the two technologies however. For solution polymerization, the monomers
must be extremely pure and the solvent (hexane, for example) should be
completely anhydrous. In contrast to emulsion polymerization, where
the monomer conversion is taken to approximately 60 percent, solution
polymerization systems are polymerized to conversion levels which are
typically in excess of 90 percent. The polymerization reaction is also
more rapid, usually complete in one to two hours.
Figure III-1* is a generalized materials flow diagram for the production
of crumb SBR by a solution polymerization process. The processing steps
shown are essentially typical of all solution polymerization processes.
As in the case with emulsion plants, solution plants comprise several
processing lines where different types of rubber for distinct end uses
can be produced (including non-extended, oi1-extended, and carbon black
master batch varieties). Plant operation is typically 24 hours per day,
365 days per year.
The fresh monomers are pumped to the plant from the tank farm. Inhibited
monomers are passed through a caustic soda scrubber to remove the in-
hibitor. The monomers are then sent to fractionator drying towers where
extraneous water is removed. Fresh and recycled solvent (for example,
111-27
-------
FIGURE 111-4
GENERAL WATER FLOW DIAGRAM FOR A SOLUTION POLYMERIZED
CRUMB RUBBER PRODUCTION FACILITY
NOTE:
SOLVENT
STORAGE
UN
t
•ONDNER
CATALYST
VOUCHER
INHIBITED N
INHIBITED
MONOMER
ONOMER
MONOMER
INHIBITOR
REMOVAL
AND DASH
1
.
'I
•AU
TO MONOMER
RECOVERY
HtAYY ™" ••^— "
„ MONOMER ,_ SOLVE"T
5 SEPARATION ^- SF.PARATION
! t*\ n i
' fl~ IT'
i 1 ' STEAM—* 1 1
HtSTE '
~ »ASTE»ATER
HEAVY
SLOPS
POLYMER-
• ^ FEED ^ !7IT.ny
ORTIIIG REACTOR ""
JC -
STIC
••^•ia^B^^
•i^t
TO MON
RECOVE
t
i L 1 GHT
^ MOHOM
\^ StfURA
n
STEAK JJ |
T
WASTF.N
CEMENT
•*
EXTENDER Oil AND CARBON
SLACK ARE NOT ADDED TO
NON-EXTENDED RUBBER
mts.
COOLING
IdTEfl
SUPPLY
MAKEUP
DATED
OVERFLOK
KASTE«ATER
EXTENDER OIL
I »> IASTE»m«
DRYING
r^l
BALINC
PRODUCT
STORAGE
ANO
SHIPPING
STEAM:
WATER
•ASHDOWN
REGENERATION
fUSTES j
WASTE»ATER
-------
DRAFT
hexane) is also passed through a drying column to remove water and ex-
traneous light and heavy components. The light- and heavy-components
build up in the system as unwanted by-products or unrecovered monomer
during the polymerization step and must be removed. The purified sol-
vent and monomers are then blended. The mixture is generally termed the
"mixed feed". The mixed fixed can be further dried to remove final traces
of water using a desiccant column.
The dried mixed feed is now ready for the polymerization step and catalysts
can be added to the solution (solvent plus monomers). The catalyst sys-
tems used vary. Typically they are titanium halide plus aluminum alkyl
combinations or butyl lithium compounds. The catalysts can be added to
the mixed feed just prior to .the polymerization stage or to the lead
polymerization reactor.
The blend of solution and catalysts is polymerized in a series of re-
actors. The reaction is highly exothermic and heat is removed continu-
ously by either an ammonia refrigerant or by chilled brine or glycol
solutions. The reactors are similar in both design and operation to
those used in emulsion polymerization. The mixture leaves the reactor
train as a rubber cement, i.e., polymeric rubber solids dissolved in
solvent.
A short stop solution is added to the cement after the desired conversion
is reached. The stabilized cement is pumped to cement storage tanks
prior to subsequent processing. At this point other ingredients, such as
antioxidants, can be added. If the rubber is to be oil extended, oil
can be added to the cement. The oil is usually blended with the cement
at some point between the storage tanks and the steam stripping operation.
The rubber cement is pumped from the storage tank to the coagulator
where the rubber is precipitated into crumb form with hot water under
violent agitation. Wetting agents (surfactants) can be added to promote
the control of crumb size and to prevent reagglomeration. In addition
to coagulation, much of the solvent and unreacted monomer are stripped
overhead. For carbon black masterbatch rubbers, the carbon black slurry
is added to the coagulator in much the same manner as for emulsion crumb
rubber.
The resultant crumb slurry passes to a series of strippers where steam
stripping drives off the remaining monomers and solvent. The strippers
are generally a flash tank or agitated kettle strippers. The steam,
solvent, and monomer vapors are condensed and sent to a decant system.
The bottom decant layer, saturated in monomers and solvent, is discharged.
The organic layer is sent to a multi-stage fractionator (described earlier)
Light fractions are removed in the first column and generally consist of
unreacted light monomer (for example, butadiene). This is normally re-
claimed at the monomer supply plant. The second column produces purified
solvent, a heavy monomer-water fraction, and extraneous heavy components.
111-29
-------
DRAFT
The heavy monomer (for example, styrene) is condensed, decanted, and re-
cycled. The bottom water layer is discharged. The purified solvent is
dried and reused. The heavy monomer is a waste stream which can either
be decanted before disposal or can be incinerated as a slop oil.
The stripped crumb slurry is separated and further washed with water on
vibrating screens. The slurry rinse water is recycled in part to the
coagulation stage with water or steam makeup. The remaining portion of
the slurry rinse water overflows and is discharged. This water contains
floating crumb rubber fines and is generally passed through a crumb pit
before discharge. The crumb fines are trapped in the pit. The screened
rubber is passed through an extruder-dryer for further dewatering and
drying. Dewatering and drying can also be carried out with a rotary
filter and hot air oven dryer. The dried rubber is pressed into 75-pound
bales and is usually wrapped in polyethylene for shipment.' Balers, identi-
cal to those employed in emulsion processing, are used in solution-
polymerized rubber production. Oil leaks are a potential problem.
In addition to the processing operations described above, area wash-
downs occur. These are frequent and produce large volumes of wastewater
which can be contaminated with dissolved organics, floating organics,
oils, and suspended solids. Since the majority of the processing steps
are operated on a strict water-free basis, there is little need for
equipment cleanout operations with water. The processing units which
are kept free of water are cleaned out with solvent when necessary. This
cleaning solvent is stored separately and is used solely for the cleanout
operation. Process pumps, handling in particular the dried mixed feed
prior to and during the polymerization stage, use a non-aqueous fluid
(usually an oil) as a seal in lieu of water to prevent contamination of
the process streams with water. Leaking fluid is a potential source of
oil which can be picked up by area washdown waters. The carbon black
slurrying area is a source of wastewaters laden with carbon fines.
The main wastewater sources in a typical solution polymerization plant
are summarized in Table I I 1-6.
Latex Production
In addition to solid crumb rubber, emulsion polymerization is also used
to produce latex rubber. Latex production follows the same processing
steps as emulsion crumb production with the exception of latex coagulation
and crumb rinsing, drying, and baling. Only about 5 to 10 percent of
SBR is used as latex, but approximately 30 percent of the nitrile rubbers
(NBR) enter the market as latex. Commercially ,avallable SBR latexes con-
tain about 45- to 55-percent solids, although some can be as high as
68 percent. Most NBR latexes are in the k$- to 55-percent solids class.
The polymerizations are taken essentially to completion (about 98 to
99 percent conversion) as opposed to emulsion crumb rubber production
where conversion per polymerization pass is approximately 60 percent.
111-30
-------
Table I I 1-6
Summary of Potential Process-Associated Wastewater Sources from
Crumb Rubber Production via Solution Polymerization Processing
Processing Unit
Source
Nature of Wastewater Contaminants
Caustic Soda Scrubber Spent caustic solution
Solvent Purification
Monomer Recovery
Crumb Dewatering
Fractionator bottoms
Decant water layer
Crumb rinse water overflow
High pH, alkalinity, and color. Extremely
low average flow rate
Dissolved and separable organics.
Dissolved and separable organics.
Dissolved organics, and suspended and dissolved
sol ids.
All Plant Areas
Area washdowns
Dissolved and separable organics, and suspended
and dissolved solids.
-------
DRAFT
As a result, the recovery of unused monomer is not economical. Process
economics are directed towards maximum conversion on a once-through
basis.
Figure I I I-5 is a generalized materials flow diagram for the production
of latex SBR by emulsion polymerization. The steps shown are typical of
all latex production processes. Although latex plants are generally
operated 2*4 hours per day and 3&5 days per year, the production runs for
each recipe or type of latex are shorter than in emulsion or solution
crumb rubber plants because latex consumption is on a smaller scale and
latex consumers are usually outside companies with varying product needs.
By contrast, the majority of crumb rubber is made for tire manufacture,
is consumed by major tire companies, and is produced by their own syn-
thetic rubber producing divisions. This has the effect of limiting the
number of types of product and recipe, rationalizing production schedules,
and, in the finaJ analysis, leading to long production runs. Latexes^are
used to manufacture dipped goods, paper coatings, paints, carpet backing,
and many other commodities.
The monomers are piped from the tank farm to the processing plant.
Monomer inhibitors are scrubbed out by using caustic soda solution.
Soap solution, catalysts, and modifiers are added to the monomer to pro-
duce a feed emulsion prior to feeding to the reactors. The water used
in the preparation of the above solutions is generally deionized city
or well water. The number of reactors in the reactor train is usually
smaller than that used for emulsion crumb production. The temperature
is generally kept at approximately kO to **5°F and, therefore, most
latexes are made by the "cold" process. When the polymerization is com-
plete, the latex is sent to a blowdown tank for intermediate storage or
holding. Stabilizers are usually added to the latex at this point to
stop the polymerization and to stabilize the latex.
The latex passes from the blowdown tanks to a vacuum stripper where the
unreacted butadiene is removed. The butadiene is vented to the atmos-
phere. The vacuum is pulled with either a vacuum pump or steam jet.
The excess styrene is stripped from the latex in a steam stripper. The
steam and styrene are condensed and sent to a receiver. The bottom
water layer is decanted off and discharged. The styrene layer is not
recycled and requires disposal.
The stripped latex is passed through a series of screen filters to re-
move unwanted large rubber solids. The latex is finally stored in blend-
ing tanks where various additives (for example, antioxidants) are mixed
with the latex. The latex is shipped from the blending tanks by tank .
car or tank truck, or is drummed ready for dispatch.
Since short production runs are common to the industry, the major waste-
waters generated in a synthetic latex plant stem from equipment cleanout
operations. When production is switched from one type of rubber to an-
other, reactors, blowdown tanks, strippers, and filters requ.re clean,ng
111-32
-------
FIGURE 111-5
GENERAL WATER FLOW DIAGRAM FOR AN EMULSION LATEX RUBBER PRODUCTION FACILITY
DAI INTAKE WATER _
COOLING
TOIER
TREATMENT
COOL
TO«E
KG
R
II
COOLING
WATER
RETURN
COOLING
WATER
SUPPLT
LIGHT MONOMER
TO ATMOSPHERE
STEAM
COJtDENCATE
RETURN
TREATED
PROCESS
HATER
SUPPLY
4-""'.. «-.
BOILER
HOUSE
1
, *
WATER
TREATMENT
UNITS
IA« INTAKE
IATER
SLOWDOWN
I
WASTEWATEB
•ASTEWATEd
-------
DRAFT
for the new product. In addition, tank cars and tank trucks owned or
leased by the plant require cleaning after each trip. Area washdowns
are frequent inside the processing buildings and at the vehicle loading-
unloading areas. All the above wastewaters will contain oils, dissolved
organics, and high concentrations of latex solids.
Table III-? summarizes the origins and nature of the principal waste-
water sources generated in a typical synthetic latex plant.
Summa ry
The growth of the tire and inner tube industry has been closely linked
to the growth of the automobile industry. Current production is over
210 million tires per year with one quarter of this production destined
for original equipment on new vehicles. The production of both tires and
inner tubes consist of the compounding, extruding, calendering, and mold-
ing of solid raw materials. There is considerable heat generated by
these processes and it must be dissipated and controlled to insure the
quality of the final product. Water used in the process, other than for
utilities, consists of makeup water for soapstone solution and latex dip
solutions.
The production capacity and output of the synthetic rubber industry are
expanding steadily and are linked very closely to consumption by the tire
industry. The relative production levels for the various types of syn-
thetic rubber will not change significantly over the next several years
to affect the operations or wastewater impact of the industry as a whole.
Two distinct processing technologies (emulsion and solution) exist. Pro-
cess variations within each of these two technologies are only minor.
Two different types of rubber product are manufactured: crumb and latex
rubbers. The so-called specialty rubbers are manufactured by processes
similar to those used to produce the so-called tire rubbers and are in
similar product forms, i.e., solid and latex rubbers.
-------
Table I I 1-7
Summary of Potential Process-Associated Wastewater Sources from
Latex Production via Emulsion Polymerization Processing
Processing Unit
Source
Nature of Wastewater Contaminants
Caustic Soda Scrubber
Excess Monomer Stripping
Tanks, Reactors, and Strip-
pers
Tank Cars and Tank Trucks
Al1 Plant Areas
Spent caustic solution
Decant water layer
Cleanout rinse water
Cleanout rinse water
Area washdowns
High pH, alkalinity, and color. Extremely
low average flow rate.
Dissolved and separable organics.
Dissolved organics, suspended and dissolved
solids. High quantities of uncoagulated
latex.
Dissolved organics, suspended and dissolved
solids. High quantities of uncoagulated
latex.
Dissolved and separable organics, and sus-
pended and dissolved solids.
-------
DRAFT
SECTION IV
INDUSTRY CATEGORIZATION
Introduction
Industry categories and subcategories were established so as to define
those sectors of the rubber industry where separate effluent limitations
and standards should apply. In the final analysis, the underlying dis-
tinctions between the various categories and subcategories have been
based on the wastewater generated, its quantity, characteristics, and
applicability of control and treatment. The factors considered in deter-
mining whether such categorizations are justified were the following:
1. Manufacturing Process.
2. Product.
3. Raw Materials.
k. Plant Size.
5. Plant Age.
6. Plant Location.
7. Air Pollution Control Equipment.
8. Nature of Wastes Generated.
9. Treatability of Wastewaters.
As indicated in Section III, there are inherent differences between the
tire and inner tube sector, and the synthetic rubber sector of the rubber
industry; therefore, the two have been separated to produce the two prin-
cipal industry categorizations.
Tire and Inner Tube Industry
Manufacturing Process
The process steps by which tires are made are similar throughout the
industry Although there are variations due to equipment manufacturer
and automation, these differences do not lead to significant variations
in the volume or constituents of process waters.
Product
Examination of existing plants indicates that the end product is not a
reasonable basis for categorization. Manufacturing steps ?£ all t re
production are similar; inner tube manufacture, although d.fferent in
some respects, generates the same type of'process wastewater streams as
does tnTtire'production. The characteristics^ the waste stream and
the potential treatment technologies are not significantly d.fferent.
Radial tire manufacture is different in the building, molding, and
curing operations; however, these differences do not sign.f.cantly
IV-1
-------
DRAFT
impact on wastewater quantity or quality. In addition, radial tires are
generally produced in the same plants as bias tires.
Raw Materials
Since the basic raw materials for the entire industry are rubber, carbon
black and oil, categorization based on raw material usage is not rea-
sonable. The quantities and form of the different raw materials re-
ceived varies, but these do not significantly affect the control or
treatment technologies applicable to the industry. The handling of raw
materials, particularly the carbon black, also varies within the indus-
try. However, this again does not affect the process wastewaters or
the!r treatabi1ity.
Plant Size
A listing of most plants currently operating and their production rates
is given in Table IV-1 . The distribution of these is presented in
Figure IV-1. From inspection of existing and plant visit data, it was
learned that plant size has no significant effect on the quality or
treatabi1ity of wastewaters. Process effluent quantities varied signi-
ficantly but was not directly related to plant size. The only signifi-
cance of size is the cost of treatment of wastewater streams, which, of
course, is related to other factors.
Plant Age
The age of plants currently in operation will fall into three basic
categories depending on the expansion period in which the plant was
built. The oldest plant in operation is an inner tube facility built
in I
As constructed, production facilities built during the first two expan-
sion periods tend to be multi-storied, with process lines located on
many floors and confined to small areas. In addition, plants from^the
first expansion period most probably have undergone modifications in
order to update their machine processing technology (for example, the
installation of internal mixers). Most likely this would further con-
gest the processing area. Much of the equipment in these older plants
is old and of designs that have since been updated to reduce mainte-
nance and operational costs. Process, non-process, and domestic waste-
water sewers exist as a combined sewer, thus making process contaminants
difficult to locate or treat once they reach the drainage system. Engi-
neering diagrams of sewers within the plant are dated and possibly non-
existent. Drains that do exist were located for ease of washdown of
contaminants, thus making their position inappropriate by current think-
ing and standards.
The newer plants of the last expansion period have the benefit of modern
IV-2
-------
Table IV-1
Major Tire Production Facilities in the United States
Company
Armstrong
Carlisle
Cooper
Corduroy
Denman
Dunlop
Fi res tone
Location
Gates
General
DesMoines, la.
Hanford, Cal.
Natchez, Miss.
W. Haven, Conn.
Carlisle, Pa.
Findlay, Ohio
Texarkana, Tex.
Grand Rapids, Mich.
Warren, Ohio
Buffalo, N.Y.
Akron, Ohio
Albany, Ga.
Barberton, Ohio
Bloomington, 111.
Dayton, Ohio
Oecatur, 111.
DesMoines, la.
Los Angeles, Cal.
Memphis, Tenn.
Pottstown, Pa.
Salinas, Cal.
Denver, Colo.
Nashvilie, Tenn.
Akron, Ohio
Bryan, Ohio
Charlotte, N.C.
Mayfield, Ky.
Waco, Tex.
Unjts/day
20,000
10,500
14,600
13,500
13,000
11,500
27,000
17,000
8,500
50
20,700
22,000
22,000
15,500
28,000
30,000
15,500
18,200
10,000
9,050
30
12,000
23,000
16,000
Company
Goodrich
Goodyear
Mansfield
McCreary
Mohawk
Schenuit
Uni royal
Locat ion
Akron, Ohio
Ft. Wayne, Ind.
Los Angeles, Cal.
Oaks, Pa.
Tuscaloosa, Ala.
Akron, Ohio
Conshohocken, Pa.
Cumberland, Md.
Danvilie, Va.
Freeport, 111.
Gadsden, Ala.
Jackson, Mich.
Los Angeles, Cal.
Topeka, Kans.
Tyler, Tex.
Union City, Tenn.
Mansfield, Ohio
Tupelo, Miss.
Indiana, Pa.
Akron, Ohio
Salem, W. Va.
W. Helena, Ark.
Baltimore, Md.
Chicopee FalIs,
Detroit, Mich.
Eau C lai re, Wis.
Los Angeles, Cal
Opeli ka, Ala.
Mass.
Units/day
6,000
18,000
11,500
19,000
21,000
38,000
13,000
20,500
4,100
14,000
44,000
30,000
30,000
15,000
30,000
14,000
12,500
3,500
6,000
4,700
10,000
29,000
39,745
30,000
16,500
13,500
Source: "Rubber Reuse and Solid Waste Management," U.S. Environmental Protection Agency, 1971.
-------
FIGURE IV-1
LOCATION OF TIRE MANUFACTURING PLANTS, PRODUCTION GREATER THAN 20,000
UNITS/DAY, AND SYNTHETIC RUBBER PRODUCTION PLANTS, PRODUCTION GREATER
THAN 60,000 LONG TONS/YEAR, WITHIN THE U. S. 1972.
• A A .- ILL. | 1ND> \ onIQ.O. A
• /..), .!«* • •
Xr'WK."K ' '
\l / WMrv T
"^*i n^* • 1^" *^" *" * ^ *^T ^™ A */ n« ^ •
• I UAlft. *«DK ^"TEMH /" •—«
• .-.. i P o • A i & *. OR. \_ S. U. i
LEGEND
A TIRE MANUFACTURING PLANTS
• SYNTHETIC RUBBER PLANTS
'i
-------
DRAFT
design criteria and updated thinking in both the sanitary and mainte-
nance engineering fields. Buildings are single-story and contain more
area per process line. Equipment and area locations have been designed
for a cleaner, more maintenance-free operation. Sewers are no longer
combined, thus making process sewer wastewaters easier to locate and
treat. Drains are not located in areas where contaminants can gain easy
entrance.
By the above reasoning, the process wastewater streams from older plants
should be larger in volume and should contain higher loadings of both
oily and solid materials.. Control and treatment should be more diffi-
cult. Examination of plant wastewater streams from all these areas
bears this out.
The years between 1950 and I960 are the transition period between the
second and third expansion period. Plants constructed in the early
1950's were built during the Korean War and will most likely have the
same problems as those built in the World War II era. Few (if any)
plants were built after the Korean War until 1959, when the current
expansion began. The year 1959, therefore, is the demarcation point
between old and new facilities.
Plant Location
From inspection and wastewater sampling of plants located in three
geographical areas of the country and from analysis of existing data,
plant location will have no effect on the quality or quantity of the
process wastewater streams. These geographical areas included the
South, the Far West, and the Northern Midwest. Geographical location
has a significant effect on the supply of water; therefore, management
of non-process streams such as cooling water and steam varied from region
to region. Recirculation of cooling water is very common in the Far
West (where water supplies are short), whereas it is less common in other
sections of the country. Reduction of non-process wastewaters by re-
cycle increases the treatability of process wastewaters when combined
with non-process wastewaters in an end-of-pipe treatment facility.
Treatability of process wastewater streams, however, is more effectively
carried out before combination with non-process streams. In addition,
geography does not limit the use of recirculated water to the Far West.
Plants in other parts of the country are also using recycle, though not
necessarily for the same reasons.
Plants visited also represented both rural and urban areas. Plants lo-
cated in urban areas tended to occupy and own less land, thus increasing
treatment cost where available open land is a consideration. However,
both the location and the characteristics and quantity of the water to
be treated are better related to the age of the plant. Urban plants are
older facilities, whereas rural plants tend to be newer. Therefore,
IV-5
-------
DRAFT
location is not a reasonable basis for categorization.
Air Pollution Control Equipment
The type of air pollution equipment employed by a facility can have a
great effect on the characteristics and treatability of the process
wastewater streams. The use of dry equipment or the recycling of dis-
charges from wet equipment was observed in all areas of the plant which
are currently served by such devices. Therefore, since company policy
(rather than the situation to be controlled) dictates the type of equip-
ment used, air pollution equipment does not form a suitable basis for
categorization.
Nature of Wastes Generated
From evaluation of all available data, the type of wastes generated by
all facilities in the tire and inner tube industry are similar. The
addition or subtraction of the latex dipping of fabric from the process
line can affect the characteristics of the process wastewaters. However,
as supported by existing data, this discharge is not large and can be
easily contained. Therefore, it does not necessarily affect the treat-
ability of process wastewaters and does not form a basis for categoriza-
tion.
Treatability of Wastewaters
The treatment technologies employed by companies throughout the industry
are similar. Wastewater constituents are also very similar: mainly oil
and solids. Treatability is more a factor of age than of the specific
pollutant and, therefore, does not form a basis for categorization.
Summary
Only the age of the production facility forms a rational basis for
categorization. As indicated, tire manufacturing facilities built in
earlier periods, although using similar manufacturing techniques, have
greater wastewater problems than do new plants built in recent times.
On this basis, there should be two separate categories: old plants, and
newer plants. Plants built prior to 1959 are considered old; those
built during and after 1959 are considered new. Inner tube facilities,
although producing a different product, incur the same difficulties as
do the older plants and should be included in the "old" category.
Camelback operation, a small segment of the industry, should also be
included in the "old" or "new" categorization of tire plants depending
on the tire facility of which it is a part. If located by itself, the
camelback should meet standards according to the date of its^construc-
tion. Compounding operations, another small segment of the industry,
should fall into the category of the plants with which they coexist. If
IV-6
-------
DRAFT
located by itself in a separate location, the compounding facility
should meet standards of "old" or "new" tire plants depending on its
original date of operation.
As a consequence, only two categories are indicated for SIC code 3011,
namely "old" and "new" tire facilities. The demarcation date between
the categories is the year 1959.
Synthetic Rubber Industry
Manufacturing Process
As described in Section I I I of this document, there are two basic pro-
cessing techniques in common use in the industry to produce synthetic
rubber: emulsion polymerization processing and solution polymerization
processing.
Emulsion polymerization as a commercial process dates back to World War
II. No significant changes have been made in the basic process since
the first emulsion polymerization plants were built. Emulsion polymeri-
zation processing is used, however, to make both emulsion crumb and latex
rubber. From both operccional and wastewater points of view, crumb and
latex production techniques should be considered separately.
Solution polymerization production facilities are different from emul-
sion plants from both process and wastewater points of view and have
been considered as a separate sub-category. Differences among solution
rubber production plants are minor. All solution plants consist of
feed preparation, polymerization, solvent and monomer recovery, coagu-
lation, and rubber finishing operations. The operations that have the
greatest wastewater impact in solution plants are those operations which
are most similar plant to plant.
It was therefore concluded that there are essentially three manufacturing
process variations which merit separate subcategories: emulsion poly-
merization to crumb rubber; solution polymerization to crumb rubber; and
emulsion polymerization to latex.
Product
There are two principal product sub-categories in the synthetic rubber
industry, crumb and latex product.
Within the crumb sub-category there are several product variations which
involved the type of rubber (styrene-butadiene, or polybutad.ene, etc.)
and whether the rubber is extended or not. The two principal products
made by emulsion polymerization are SBR and nitrile rubber. The process
ooerations for the two rubbers are identical, and the same or similar
equipment is used? Several types of rubber are produced by solut.on poly-
mer zat?on processes; in many cases similar solvents and monomers are used,
equivalent processing operations are carried out, and Identical process,ng
lv-7
-------
DRAFT
equipment is used.
The processing variations involved in the manufacture of either oil-
extended or carbon-black-extended rubber are minor. In addition, the
oil and carbon black are very effectively tied up with the rubber, thus
reducing the potential for wastewater impact.
The effects that the various types of latex rubber (for example, SBR and
NBR) have on the production operations and wastewaters are minor. The
same equipment and processes are used for all types.
As pointed out in Section III, the specialty rubbers are essentially
similar to the tire rubbers from a processing point of view, and no
separate categorization is deemed necessary.
It has been concluded that only two principal product subcategories are
required to adequately define the synthetic rubber industry. They are
crumb and latex rubber.
Raw Materials
The monomeric raw materials used to produce the various types of syn-
thetic have similar properties. They are usually unsaturated hydrocar-
bons with extremely low solubility in water. Chloroprene, a chlorinated
hydrocarbon used to make neoprene rubber, is also insoluble in water. In
addition to low solubility, most of the monomers used have high volatil-
ity and, consequently, a monomer floating on wastewater soon evaporates.
Most solvents used also have low solubility and high volatility and do
not remain in a wastewater. The catalysts, modifiers, antioxidants,
etc. used in polymerizations are generally similar and are used in such
low concentrations that their effect on wastewater is minimal. Their
presence is generally undetectable in the wastewaters.
In conclusion, there is no need for a subcategorization based on the
raw materials used.
Plant Size
Most emulsion and solution crumb rubber plants consist of several par-
allel and integral processing lines. Each of these lines tends to be
of similar size. The wastewaters generated by a plant, therefore, are
normally directly proportional to the production capacity.
Small production facilities (for example, latex plants), will bear a
somewhat higher treatment cost than larger plants. However, these plants
are generally part of a larger synthetic rubber or organic chemical
complex, and the treatment cost can be shared. In any case, latex
plants are considered as a separate sub-category.
For these reasons, sub-categorization according to plant size is not
necessary.
IV-8
-------
DRAFT
Plant Age
Many emulsion plants (crumb and latex rubber) were built during or
shortly after World War II. Few have been built since. In addition,
technology has not changed appreciably since that time.
Solution plants are generally newer, but all have been built in the
last 13 years. The technology has not changed radically during that
time period.
It has been concluded that plant age is not a significant factor for
separate subcategorization.
Plant Location
Most of the larger synthetic rubber plants are located in one geogra-
phic region. (Refer to Figure IV-1.) This fact is closely connected
to the availability of the monomeric raw materials. The location of
the plants does not influence the processing operation. However, geo-
graphic location can influence the performance of aerated lagoons and
stabilization ponds. Comparable secondary wastewater treatment alter-
natives, such as activated sludge, do exist, but the performance is not
dependent on geographic location. It is not necessary to subcategorize
the synthetic rubber industry by plant location.
Air Pollution Control Equipment
Generally, air pollution control devices are not required by the indus-
try. Odor problems do exist at some plants, but these are controlled
by devices which are either dry or which do not impact on the waste-
waters of the plant.
Air pollution control is not a subject for subcategorization of the
synthetic rubber industry.
Nature of Wastes Generated
The differences in the characteristics of wastewaters generated by
production of non-extended, oil-extended, and carbon-black-extended
emulsion crumb rubber were not discernible. Similarly, the wastewater
characteristics produced by non-extended, oi1-extended, and carbon-
black-extended solution crumb plants were essentially identical; however,
wastewaters from emulsion crumb, solution crumb, and latex rubber produc-
tion facilities were significantly different to warrant subcategor.zat.on.
These facts indicate that separate subcategories are required only for
emulsion crumb, solution crumb, and latex rubber product.on.
IV-9
-------
DRAFT
Treatability of Wastewaters
Since the wastewaters generated by emulsion crumb and latex production
require chemical coagulation prior to primary clarification whereas the
wastewaters produced by solution crumb plants do not, there is a dif-
ference in the treatability of synthetic rubber wastes. In addition, the
COD and BOD loading from latex plants is considerably higher than from
emulsion and solution crumb plants, and requires more extensive treat-
ment.
It was concluded that, based on the treatability of the wastewaters,
three subcategories were required: emulsion crumb, solution crumb,
and latex rubber production.
Summary
For the purpose of establishing effluent limitations guidelines and
standards, the synthetic rubber industry should be separated into three
subcategories which are based on distinct processing and product dif-
ferences. These subcategories are:
1. Emulsion crumb rubber.
2. Solution crumb rubber.
3. Latex rubber.
IV-10
-------
DRAFT
SECTION V
WASTE CHARACTERIZATION
Tire and Inner Tube Industry
A general process flow diagram for a typical tire production facility is
presented in Figure I I I-1 . Figure I I I-2 presents a typical inner tube
production process diagram.
The primary water usage in a tire and inner tube facility is for non-
contact cooling and heating. . Discharges from service utilities supplying
cooling water and steam are the major source of contaminants in the final
effluent. Characteristics of these wastewaters are COD, BOD, suspended
solids, and dissolved solids.
Table V-l presents the raw waste loading for the combined process and
non-process wastewaters of the plants visited. Flow variations are due
mainly to the use of once-through cooling water in certain plants as
opposed to recirculating cooling water. Plants A and B are new plants
using totally recirculated cooling water. Plants E and G are old facili-
ties also using recirculated water. A comparison of these four plants
indicates that no significant variations in flow exist due to age of
the plant.
Plant F typifies a plant using once-through water as its primary source
of process cooling. COD and BOD loadings vary to a great degree by the
type and amount of chemicals used in the treatment of boiler and cooling
tower makeup waters. Larger loadings for older plants indicate an in-
creased amount of process wastewater pollutants in the effluent. Load-
ings measured in Plant A are high due to the practice of discharging
washdowns of soapstone and latex dip areas noticed during the sampling
period. This plant uses holding lagoons. Because all wastes are con-
tained within the plant's boundaries, Plant A discharges contaminants
which other exemplary plants (using different technologies) can not ac-
complish. These contaminants lead to a correspondingly higher loading.
Suspended solid loadings evolve primarily due to water treatment blowdowns,
wastes and boiler blowdowns. In addition, the suspended solid loadings
in process wastewater can increase due to spills, leakage, and soapstone
discharge. Loadings for old plants tend to be higher than those for new
plants. This is due in part to the use of older water treatment tech-
niques and the larger volumes of process wastewater containing solids
discharged by older facilities.
The quantity of dissolved solids discharged is related to the amount of
recirculated non-process water and the water supply source. Plants using
well water typically have higher dissolved solid loadings, than those
using municipal or river water sources.
V-1
-------
TABLE V - 1
Raw Waste Loads of Untreated Effluent From Tire and Inner Tube Facilities
FLOW COO BOD S£ TDS OIL
Gate- liters/1,000 kg liters/1,000 kg liters/1,000 kg liters/1,000 kg liters/1,000 kg liters/1,000 kg
Plant gory of raw material of raw material of raw material of raw material of raw material of raw material
A .'Jew 6344.0 1.890 0.067 0.960 4.800 0.243
B New 3430.0 .184 0.002 0.047 0.159 0.075
C1 .Jew 8251.0 - - 1.155 - 0.794
D New 10883.0 0.142 0.012 0.092 0.879 0.009
E Old 5453.0 0.100 0.001 0.440 0.001 0.0272
f Old 123480.0 3.398 0.296 1.358 0.001 0.650
«<•
* G Old 3220.0 0.645 0.093 3.429 0.000 0.267
H Old 72427.0 0.001 0.036 0.676 0.000 0.167
1 Old 10610.0 0.615 0.148 2.812 1.810 0.172
Estimated, raw material consumption not known.
2
Includes treatment by in-plant sumps.
-------
DRAFT
Table V-1 also shows that the plant's final end product has no significant
effect upon the raw waste loading in the final effluent. Data from
Plant H, which produces primarily truck and industrial tires, is not
substantially very different from Plants E, F, or G, which, while pro-
ducing a combination of products, produce mainly passenger tires. Load-
ings from Plant I are similar to the others, even though this plant's
primary product is the manufacture of inner tubes.
To substantiate the data and conclusions on total final effluent, Corps
of Engineers water discharge permit applications were obtained for a
large segment of the tire and inner tube industry. Comparison of Corp.
permits for plants considered old and new revealed that the above find-
ings and conclusions are substantially correct. Table V-2 lists the
main characteristics and the loadings corresponding to a typical old
and typical new tire production facility.
Raw waste loads in the process wastewaters leaving the production facili-
ty are presented in Table V-3. Flows rates are estimates only, mainly
due to the intermittent nature of the waste discharges. Although there
appears to be no significant difference in the measured flow rates as
shown by data, the composition of the flows originating from old and new
plants differs greatly. New Plant A uses large amounts of washdown water
which comprises the bulk of their process wastewaters. New Plant B pro-
cess wastewaters consist largely of discharges from an extensive wet air
pollution train. The discharges from this equipment are the primary con-
stituent of the process wastewaters. The process wastewater flow rates
leaving older plants are due to other factors such as spills, leakage,
runoff from storage areas and inherent plant practices of older facili-
ties. Therefore the data indicate that, given the same housekeeping poli-
cies and the same degree of wet air pollution equipment and controls, the
process wastewater flow rates from older plants will be higher than from
newer plants.
Two important characteristics of the process wastewaters are suspended
solids and oil. The suspended solids are generally higher from older
plants due to greater maintenance and poorer housekeeping and control
practices. The same can be said for the oil. Suspended soi1 ids evolve
from the powdered substances used in the compounding area and from the
collection of particulates by wet air pollution equipment. The oil is
primarily lubrication and hydraulic oils from in-plant sources, and ex-
tender and fuel oil from run-off in storage areas. Both parameters can
be treated successfully. Plant B is using a sedimentation lagoon to
settle solids collected in the compounding area from wet air pollution
equipment. It has been demonstrated by Plants A and E that solids col-
lected in other areas can be separated easily by convential equipment.
American Petroleum Institute (API) type separators are being used to
treat oily waste effluents of Plants B, D, and E.
The primary constituents of the process wastewaters are presented in
Table V-4, along with their sources and characteristics.
V-3
-------
TABLE V - 2
Old Tire Facilities
(to 1958)
Minimum
Maximum
Average
New Ti re Fac ?1it ies
(1959 to Present)
Minimum
Maximum
Average
Average Valves of Raw Waste Loads for Tire Industry
FLOW COD S£
liters/1,000 kg liters/1,000 kg liters/1,000 kg
of raw material of raw material of raw material
6267.0
386478.0
37000.0
2303.0
43070.0
10500.0
0.088
7.29^
0.7*0
0.083
2.020
0.580
0.001
5.854
1.000
0.032
1.397
0.310
TDS
OIL
1 iters/1,000 kg
of raw material
0.349
105.660
12.000
0.387
1 2 . 980
5.535
1 iters/1,000
of raw mater
0.003
3.363
0.120
0.011
0.187
0.042
kg
ial
Source: Corp of Engineer Permit Applicati
ons
-------
TABLE V - 3
Raw Waste Loads of Process Wastewaters From Tire and Inner Tube Facilities
FLOW1
COD
BOD
SS
TDS
OIL
• L. W »T WWIS \J \J \J »J iJ 1 L* sJ VJ ) l_
Cate- 1iters/1,000 kg liter?/!,000 kg liters?!,000 kg liters/I,000 kg liters/I,000 kg liter?/!,000 kg
Plant gory of raw material of raw material of raw material of raw material of raw material of raw material
A
B
c2
D
E
F
G
H
I
New
New
New
New
Old
Old
Old
Old
Old
290.0
1650.0
110.0
700.0
590.0
4300.0
769.0
1.57
0.193
0.0^6
2.199
0.067
0.001
0.010
0.000
0.356
0.882
0.013
0.06^
0.017
0.57
0.001
0.520
2.610
5.12
0.3739
3.210
0.019
19.765
.075
0.008
0.027
0.650
0.260
0.163
0.172
1
Estimated
No data available from Plant C
-------
TABLE V - k
The Sources and Characteristics of Process Wastewaters from
the Tire and Inner Tube Industry
Wastewater Type
Soapstone
Source
Compounding Area: Washdown and
System Cleanout; Runoff from
Spi11s and Leakage
Flow
1
Intermittent
0 - 5,7000 Liters
Characterist ics
Suspended Sol ids,
BOD, COD, Oil
Latex Dip
Fabric Dipping Area: Discharge
of Waste Solution; Washdown; Run-
off from Spills and Leakage
Intermittent
0 - 200 Liters
Suspended Sol ids,
BOD, COD
In-Plant Sp?lIs and
Leakage
All Areas of Plant where Water
Cooled Machinery is used; also
Latex and Soapstone Dipping
Areas
Intermi ttent
0 - 220 Liters
Oil, Suspended
Sol ids
Oil and Solvent Stor-
age and Maintenance'
Area Runoff
Storm and Washdown Runoff from
these areas
Intermi ttent
Oil
Ai r Pollution Equip-
ment Discharges
Compounding Areas, Tire Finish-
ing Areas
7 - 3^0 Liters/
minute
Suspended Sol ids
Part Cleaning Dis-
charges
Steam Cleaning; Spillages in
Solvent Cleaning Area
Intermittent
Oil, Suspended
Sol ids
Maximum and minimum flows from plant visit data are presented here.
-------
DRAFT
Synthetic Rubber Industry
Gene ra1
Wastewater characterization data was obtained from literature, EPA docu-
ments, and company records. Plant visits (refer to Section VII) were
made to selected plants to confirm existing data and fill the data gaps.
Figures I I 1-3, IN-1*, and I I I-5 are generalized flow diagrams of emulsion
crumb, solution crumb, and latex production facilities, respectively;
they indicate the location of water supply and wastewater generation.
Data on total effluent flow and characteristics include utility waste-
waters. It is virtually impossible to determine meaningfully total plant
effluent flows and characteristics exclusive of utility wastes. It should
be noted here that utility wastewaters are amenable to treatment by the
existing treatment facilities in use and commonly practiced by the in-
dustry.
Emulsion Crumb Rubber Subcategory
Flow Analysis
Table V-5 lists the total effluent flows for plants producing various
emulsion crumb rubber products based on a unit of production. This data
was obtained by plant visits. Although three plants were sampled, six
cases of emulsion crumb production were studied. The wastewater con-
tributions of other facilities included solution crumb production and
non-rubber commodities.
It can be seen from Table V-5 that, for similar products, separate plants
appear to have different effluent flows. However, different products at
the same plant seemingly produce identical wastewater flows. This is due
to the following distinct facts:
1. The water use practices in one plant for different emulsion
crumb products are based on one technology, namely that of the
company's process design and engineering.
2. The inability of the sampling team to discern small differences
in effluent flows for different products at the same plant.
It can also be noted that there is no significant trend in wastewater
generation rate between the various types of emulsion crumb rubber pro-
duct (non-extended, "hot", oil extended, and carbon black extended).
The average effluent flow rate for emulsion crumb is 16,600 liters per
metric ton (1,000 kg) of production.
V-7
-------
00
TABLE V - 5
Raw Waste Loads for Emulsion Crumb Rubber Plants
Plant Product
J SBR and NBR Part
01 1 and Carbon Black
Extended
K SBR Part Oil Ex-
tended
K SBR Oil Extended
L SBR Oil and Carbon
Black Extended
' L SBR "Hot", 'ton-
Extended SBR
1. SBR ;:on-Extended
Average Value
FLOW
Liters/1 ,000 kg
15,000
18,500
18,500
16,500
15,500
15,500
COD
kg/ 1,000 kg
11.93
22.23
19.76
8.72
29.24
25. 37
19.63
BOD
kg/1 ,000 kg
N.A.
2.13
2.13
2.84
2.84
2.84
2.56
ss2
kg/ 1,000 kg
3.73
2.30
11.31
3.94
N.A.
11.94
6.64
OIL
kg/ 1,000 kg
2.09
0.13
3.54
0.48
1.31
1.45
1.5
1
Includes utility wastewaters.
Raw waste load determined downstream of crumb pits, where the suspended solids and oil levels'are reduced.
N.A. Data not available.
o
30
-------
DRAFT
Raw Waste Loads
Table V-5 also summarized the raw waste loads for the six cases. It can
be seen that the parameter with the highest concentration is COD. The
BOD values are generally much lower. The high COD to BOD ratio is in-
dicative of the high resistance of many of the constituents in the waste-
waters to biological oxidation.
The raw suspended solids concentration in the emulsion crumb wastewaters
were determined after separation of the rubber fines in the crumb pits.
Since all emulsion crumb plants have separation pits, this raw waste load
data is applicable to the industry. Much of the suspended solids con-
tribution is due to uncoagulated latex solids. The concentration of oil
does not appear to be related to the degree to which the crumb rubber is
oil extended. The oil analysis cited is really "carbon tetrachloride ex-
tractables" and will also include insoluble monomers.
Another significant parameter in emulsion crumb wastewaters is total dis-
solved solids. This has two principal sources:
1. The crumb coagulation and rinse overflows.
2. The utility wastes (boiler and cooling tower blowdowns, and
water treatment regeneration wastes).
Surfactants are another characteristic produced by the emulsifying agents.
The level of surfactants in the wastewater is considerably lower than the
parameters reported in Table V-A.
Individual Waste Streams
Table V-6 presents the major constituent loadings of the principal waste-
water streams in an emulsion crumb plant. The most significant parameter
Is total dissolved solids which is produced by the acid and brine coagu-
lation liquors. The coagulation liquor and crumb rinse overflows, along
with the utility wastes, provide the bulk of the total dissolved solids in
the plant effluent. It can be seen that the quantity of surfactants pro-
duced are much lower than the other parameters. Surfactants are not gener-
ated in appreciable quantities by waste streams not included in Table V-5.
The suspended solids are much higher than in the total effluent since the
crumb pits remove much of the suspended solids in the crumb rinse overflow.
Removals better than 95 percent are common. Oil entrained in the rubber
is also removed along with rubber crumb solids.
When comparing the sub-total parameter values of Table V-6 with the average
total effluent loads of Table V~5, it can be seen that the three streams
listed in Table V-6 are the major contributors to the total effluent.
The spent caustic scrub solution is an extremely low flow rate wastewater
which has very high COD, alkalinity, pH, and color characteristics. It
V-9
-------
TABLE V - 6
Raw Waste Loads of the Principal Individual Wastewater Streams in an Emulsion Crumb Rubber Plant
COO BOD SS1 IDS OIL1 SURFACTANTS
Wastewater Stream kg/1,000 kg kg/1,000 kg kg/1,000 kg kg/1,000 kg kg/1,000 kg kg/1,000 kg
Monomer Recovery 0.66 O.lU 0.08 1.26 0.11 0.0001
Coagulation Liquor Overflow 1.30 N.A. N.A. ^6.25 0.10 N.A.
1s Crumb Rinse Overflow2 6.39 0.*+6 33.^ ^2.33 1.^6 0.0077
Sub-Total 8.35 0.60 33.52 39.7^ 1.67 0.0078
Raw waste load determined prior to crumb pit, where the suspended solids and oil levels are reduced.
2
In one case, the crumb rinse overflow is combined with the coagulation liquor overflow and discharged as one
combined stream.
N.A. Data not available.
o
73
-------
DRAFT
is not, however, a significant waste stream when combined in the total
effluent. It is usually bled-in at low flow rates into the effluent.
Area washdown and equipment clean-out wastewaters are highly loaded with
COD and suspended solids, and, by nature, are intermittent in flow. They
cannot be characterized because they are generated on an irregular basis
and have greatly variable concentration loadings.
Chromium and zinc are present in low concentrations (1 mg/L) in the final
effluent. They are present due to cooling water treatment, and can be
eliminated by substitution of chromium-free corrosion inhibitors. Heavy
metals from catalysts and other reaction ingredients are not present in
measurable concentrations in emulsion plant wastewater effluents.
Solution Crumb Rubber Subcategory
Flow Analysis
Table V-7 presents the total effluent wastewater flows for facilities
producing various solution crumb rubber products. The flow data is given
in terms of liters per kilogram of production. Five plants were visited
and eight types of solution crumb product were sampled. Some plants are
multi-product facilities, and the contributions of the solution crumb
facilities were accounted for.
Table V-7 shows that there is no discernible difference in the effluent
flows between types of product. There appears to be more correlation
between products at the same plant site. This is similar to the findings
for emulsion crumb rubber production.
One plant (Plant M) has a considerably lower effluent flow than all the
other facilities. The apparent reason for this difference is the use of
a special rubber-finishing process which generates very little or no
wastewater.
The average effluent flow for solution plants is similar to emulsion
plants, and typically approximates 16,600 liters per metric ton of pro-
duction.
Raw Waste Loads^
Table V-7 also presents the raw waste loads for the four main parameters.
It can be seen that the constituent levels are approximately one half of
those present in emulsion crumb wastewaters. This supports literature
and company data which indicate that the solution production processes
are "cleaner" than their emulsion counterparts. The main factor behind
this is the absence of coagulation liquor and uncoagulated latex. The
COD to BOD ratio is high which indicates that a considerable proportion
of the raw wastewater components are not readily biologically oxidizable.
V-11
-------
TABLE V - 7
Raw Waste Loads for Solution Crumb Rubber Plants
Plant
K
K
L
L
M
: n
N
0
Product
SBR Oi 1 Extended
SBR Carbon Black Ex-
tended
PBR Oi 1 Extended
SBR Non-Extended
PBR Non-Extended
1 R Non-Extended
PBR Part Oil Extended
PBR, IR EPDM
Part Oil and Carbon
FLOW
Liters/1 ,000 kg
10,500
17,800
28,500
14,700
3,400
11,900
11,900
29,000
COD
kg/I ,000 kg
4.04
20.80
11.40
13.28
0.17
3.61
3.01
5.33
BOD
kg/ 1,000 kg
0.09
0.18
1.55
0.82
0.06
1.37
1.37
3.57
ss1
kg/ 1,000 kg
0.81
2.20
5.72
1.79
0.05
N.A.
5.38
3.71
OIL
kg/1 ,000 kg
N.A.
N.A.
2.43
1.43
0.07
0.01
2.32
0.23
Black Extended
Average Value 9.03 1.13 2.81 1.03
1
Raw waste load determined downstream of crumb pits, where the suspended solids and oil levels are reduced.
N.A. Data not available.
-------
DRAFT
The total dissolved solids content of solution crumb wastewater is con-
siderably lower than for emulsion crumb plants. This again is mainly due
to the absence of the coagulation liquor.
Surfactant concentrations in the total plant effluent are low. Surfactants
are used to de-agglomerate the crumb rubber during coagulation and rinsing.
The solvent recovery systems do not produce any significant effect on the
COD or BOD content of the effluent.
One plant (Plant M) has considerably lower loadings than the others. This
is probably due to the fact that rubber for non-tire use is produced at
this plant. This rubber is used to manufacture impact-resistant resins,
and its quality and production controls are extremely critical. In ad-
dition, special finishing equipment appears to be used.
Individual Waste Streams
The crumb rinse overflow produced at a solution crumb plant is similar
to that produced at an emulsion crumb plant, with the exception that un-
coagulated latex is not present. The suspended solids, mostly crumb
rubber fines, are similar to those in emulsion crumb rinse overflows;
the crumb pits produce the same reductions.
The monomer and solvent recovery wastes are comparable to the monomer
recovery wastes from emulsion plants. Although heavy slops are produced
in some plants, these are usually disposed of by drumming or incineration,
Since monomer purities must be high, recovered butadiene, for example,
Is returned to the monomer supply plant and has no impact on the solu-
tion crumb rubber wastewater.
Equipment clean-out wastewaters are less of an environmental problem in
a solution plant because much of the processing equipment must be kept
dry or water free. Area washdowns are similar in volume, but do not con-
tain latex. These washdowns do pick-up rubber solids and oil from pumps
and machinery areas.
The spent caustic scrub solution, where used, is identical to that used
in emulsion crumb production. In plants where emulsion and solution
crumb rubber is produced, the same caustic scrub system is used for both
facilities.
Catalysts and other reaction ingredients do not produce discernible
quantities of heavy metals or toxic constituents. Chromium and zinc in
cooling tower blowdown are present in some plant effluents, but in very
low concentrations. These can be eliminated by using chromium-free cor-
rosion inhibitors.
V-13
-------
DRAFT
Latex Rubber Subcategory
Flow Analysis
Table V-8 lists the total effluent flows for latex rubber plants. Only
two plants are presented, but the similarity between the data values is
good. Latex plants are generally part of larger complexes, and flow
data for latex operations is difficult to obtain. The flow from latex
plants appears to be lower than from either emulsion crumb or solution
crumb facilities. The major flow contributions at latex plants originate
with equipment cleaning, area washdown operations, and waters from vacuum
pump seal systems.
Raw Waste Loads
The raw waste loads of latex plant wastewaters are considerably higher
than either emulsion or solution crumb plants. Equipment cleanout and
area washdowns are frequent due to smaller produce runs, and considerable
quantities of uncoagulated latex are contained in these wastewaters. The
high COD to BOD ratio is typical of all synthetic rubber subcategories
and underlines the resistance to biological oxidation of the wastewater
constituents. Oil concentration is lower than in emulsion or solution
crumb facilities and is contributed by separable monomers, such as styrene,
in the wastes. The suspended solids in the effluent are due mainly to
uncoagulated latex. Total dissolved solid levels are lower than for
emulsion plants because of the absence of the coagulation liquor stream.
Surfactants are present, but in much lower concentrations than the other
parameters.
Individual Waste Streams
Tank, reactor, and filter cleaning produces considerable quantities of
wastewater. These are characterized by high COD, BOD, and suspended
solids. In addition, unloading and product loading areas and general
plant areas are frequently washed down. The characteristics'of these
wastes are similar to those produced by usual equipment cleaning in this
industry. Vacuum pump seal waters contain small quantities of organics
which produce moderate levels of COD from the vacuum stripping operation,
The stripping condensates contain condensed monomers. Most of these
monomers are decanted from the water and re-used. The water layer over-
flow from the decanter has high COD and BOD concentrations.
Spent caustic scrub solution is an extremely low flow waste and has simi-
lar characteristics to spent solutions produced in emulsion crumb and
solution crumb plants.
-------
-!.A. Data not available.
TABLE V - 8
Raw Waste Loads for Latex Rubber Plants
Plant
Product
FLOW
COD
BOD
SS
OIL
liters/1,000 kg kg/1,000 kg kg/1,000 kg kg/1,000 kg kg/1,000 kg
SBR and NBR
36.37
5.61
6.70
N.A.
SBR
12,500
33.52
5.01
5.63
0.33
Average Value
5.31
6.17
0.33
o
73
-------
DRAFT
SECTION VI I
CONTPxOL AND TREATMENT TECHNOLOGY
Survey of Selected Plants
General Approach and Summary
In order to review and fully evaluate the wastewater control and treat-
ment technologies used in the rubber processing industry, selected plants
were visited to conduct operation analyses, review water and wastewater
management programs, and evaluate wastewater treatment facilities. The
plants were selected as being exemplary or advanced in their wastewater
control and treatment technologies, based on effluent'and treatment data
from the technical literature, EPA documents, Corps of Engineers Permit
to Discharge Applications, and individual company treatment data.
Plants producing passenger tires(both bias and radial ply), truck tires,
camelback , and inner tubes were visited and studied to determine if the
type of product affected the quality and quantity of wastewater streams
and/or the control and treatment technology employed. Both single-pro-
duct and multi-product plants were included so that the effects of com-
bined lines on the plant wastewaters could be evaluated; likewise, plants
of various sizes were studied to determine the impact of production
levels. Age was a major consideration because determination of the
effect, if any, of newer processing technology and machinery on the con-
trol and treatability of process waste streams was one of the principal
objectives of the invest i gat i've phase of this project. Table VI 1-1
is a summary of the products manufactured, raw material usage, and waste-
water control and treatment technologies utilized at the tire and inner
tube plants visited.
In the synthetic rubber production segment of the industry, the field
visits included plants employing emulsion and solution polymerization
processing methods and involving all types of synthetic rubber products:
"cold crumb", "hot crumb", non-extended, oil-extended, carbon-black-
extended, and latex rubbers. As in the tire and inner tube segment,
the effects of single- and multi-product lines, plant size, and plant
age on wastewater volume and characteristics and related control and
treatment technology were evaluated. A summary of the products, processes,
production capacities, and wastewater control and treatment technologies
of the exemplary synthetic rubber plants visited is presented in Table
VII-2.
VI 1-1
-------
Plant
Product
Passenger Tires,
Implement Ti.res,
Front Tractor Tires
Passenger Tires,
Industrial Tires
Passenger T ires
Passenger Tires, Truck
Tires, Tractor Tires,
Camelback
Passenger Tires,
Truck Tires
Passenger Tires, Truck
Ti res. Inner Tubes,
Camelback
Passenger Tires,
Truck Ti res
Truck Tires, Industrial
Tires
Inner Tubes
Table VI1-1
Wastewater Control and Treatment Technologies at Exemplary Tire and Inner Tube Plants
Control Measures
Raw Material Usage
(Kg/day)
120,000
310,000
s&o.ooo
210,000
681 ,000
2<»6,000
75,000
Recirculation of Soapstone,
Absence of Drains in Dirty
Areas
Recirculation of So.ipstone,
Baffled Oil Separator for Oil
Storage Area, Absence of Drains
in Dirty Areas
Recirculation of Soapstone
Recirculation of Soapstone,
Oil Separator, Loca! Oil Sumps
Blockage of Drains, Local Oil
Sumps and Gravity Separators,
Curbing of Soapstone Area, Re-
circulation of Soapstone
Recirculation of Soapstone,
Oil Sump for Oil Storage Area
Recirculation of Soapstone, Oil
Sump and Curbs for Oil Storage
Area
Recirculation of Soapstone
Containment of Soap and Soapstone
Solutions
Primary Effluent
Treatment
Sedimentation and
Holding Lagoon
Sedimentation and
Lagoons
Primary Settling Basins
Gravity Separator for
Boiler Slowdown, Some Water
Treatment Wastes and Wash-
down of Soapstone Area
None
Primary Settling Basin
and Clarifying Basin
None
Sedimentation Basins for
Boiler Slowdown, Cooling
Tower and Water Treatment
Wastes
None
Secondary Effluent
Treatment
No Discharge due to Spray
Irrigation and Evaporation
of Wastewaters
None
None
Discharge of Some Water Treat-
ment Wastes to Municipal Treat-
ment FadIi ty
Discharging of Process Waste
to Municipal Treatment Facility
None
Discharge of Treated Wastes
to Municipal Treatment Facility
None
-------
Table VI1-2
Wastewater Control and Treatment Technologies at Exemplary Synthetic Rubber Plants
Plant Product
J Crumb SBR
Crumb NBR
K Crumb SBR
L Crumb SBR
Crumb, hot SBR
Crumb PBR
Crumb SBR
M Crumb PBR
N Crumb IR
Crumb PBR
0 Crumb PBR
Crumb IR
Crumb EPOM
P Latex SBR
Latex NBR
-------
DRAFT
Tire and Inner Tube Plants
Plant A
This plant, built in 1961 and located In an arid rural community, pro-
ducies passenger tires, small-implement tires, and front tractor tires.
Production rate for passenger tires at the time of the visit was
12,000 units per day. In addition to the normal tire processing and
production lines, this plant has a latex fabric-dip operation. Raw
material consumption was over 120,000 kg(264,000 Ibs) per day.
The actual production facility occupies approximately ^0 acres of land.
The plant boundaries surround another 350 acres of land currently devoted
to agricultural use.
The only source of raw water supply is well water. It is used for cooling,
steam generation, domestic use, and all other plant needs.
The principal process wastewaters from this plant are water and steam
leakages, and wash waters from the cleaning of equipment and general
work areas. Water leakage occurs at various water-cooled machinery
units, including mills, Banburys, tread extruders, and tread-cooling
tanks. In addition, water can escape from the hydraulic water system
used in the Banbury and press areas. Water and steam occur in the process
wastewater in the press area as the result of broken seals or failing
bladder bags. Oil and solid matter which have collected on the floors
are carried along by these various water streams into the area drainage
system. The oil is lubrication oil which has dripped or leaked from oil
seals on mills, pumps and like equipment, from open gears, from gear boxes,
and from the hydraulic water system. Additional oil and soild materials
result from leakages at the Banbury dust and oil rings.
Daily washdowns include steam and solvent cleaning of the tread books
and miscellaneous machinery parts and the cleaning of the latex dip tank.
Weekly cleanups, which occur on the weekends(non-production days), include
washdown of the steel grates in the soapstone area.
This plant was specially laid out and engineered so as to keep spills and
leakages from becoming a problem. Drains are non-existent in the soap-
stone area and in many of the mill areas. Removable steel grates have
been provided in the soapstone dip area so that spilled soapstone solution
will not create a work hazard. Housekeeping practices and schedules have
been set up to keep leaks and spills of lubricating oil on the floors of
the flant to a minimum. When steam and water leakages do occur, they are
directed(along with all other process and non-process wastes) to a collec-
tion pond. Equipment-cleaning wastewaters are also discharged to this pond.
VI 1-1
-------
DRAFT
The principal non-process wastewaters are boiler and cooling pond
blowdowns. In addition, there is a hot-water-sump overflow. The hot-
water sump is used as a collection point for recycled press cooling
water. Contaminants in these wastes are suspended and dissolved
sol ids.
End-of-pipe treatment at this plant includes pH control and the lagoon-
ing of all effluents, both process and non-process. The wastewaters,
after pH adjustment, are directed to the 11 million liter(3 million
gallon) collection and storage pond. The residence time in this pond
is approximately four days. Settling of suspended solids and the
reduction of both COD and oil occur during this period of time. From
here, the wastewaters are fed to a second pond. Water leaving the
second retention pond can be used for any of three functions. It can
be used for irrigation on the company-owned farm acreage around the
production facllity(its primary function), it can evaporate, or it
can percolate into the sandy ground below the pond. (The water table
at this plant is approximately 76 meters(250 ft.) below the surface.)
In addition to containment of all process and non-process wastewaters,
all storm runoff from within and around the plant confines is directed
to and contained in these lagoons.
Plant B
This plant, located in a rural area, started operating in 196^. Plant-
owned ground is now almost entirely utilized by processing and ware-
housing buildings, parking lots, and wastewater treatment facilities.
The facility produces passenger tires and heavy off-the-road tires.
Production rates are currently running at 2k,000 passenger and 2,000
off-the-road tires per day.
Water for all plant uses, including makeup for the cooling towers, boiler
and various dipping solutions, is supplied by the municipality.
The principal process wastewaters from this plant are: water and steam
leakages, runoff from the process oil storage area, and discharges from
wet air-pollution control equipment.
Water and steam leakages occur in the press room of both the passenger-
tire and truck-tire facilities. These streams become contaminated with
oil scavenged off machinery parts and the floor. Runoff from the oil
storage area is continuous due to the placement of a steam blowdown pipe
nearby; oil is scavenged from the area and becomes entrained with the
condensate wastewater stream.
VII-5
-------
DRAFT
Wet scrubbers are used to control air emissions from the compounding area
and from the green tire painting area. Collectively, these scrubbers
represent the largest single discharge in the plant. Contaminants
include COD and suspended solids, as well as some oily matter.
Maintenance and housekeeping practices at this plant are directed at
keeping leakage at a minimum and wel1 contained. Runoff from the process
oil-storage areas is pretreated in a baffled oil separator chamber before
flowing to the end-of-pipe treatment facilities. The separator unit ef-
fectively removes oil from the small volume of water in the influent.
Water discharged from air pollution equipment passes into the plant's end-
of-pipe treatment facility untreated.
The principal non-process wastewaters are boiler and cooling tower blow-
downs, and water treatment wastes; these are segregated from the process
wastewaters and are discharged, without subsequent treatment, into the
storm drainage system.
In addition, there are blowdowns from various presses throughout the plant;
these contain COD, suspended solids, and dissolved solids.
End-of-pipe treatment at this plant involves the use of two lagoons. The
wet scrubbers and steam blowdowns flow into the first lagoon, which is used
to separate settleable solids and separable oil. This pond has a surface
area of 0.52 acres and a baffled effluent weir. Wet scrubbers, and some
once-through cooling water flow to the second lagoon. This has approximately
O.Jk acres of surface area and is also used to remove separable solids and
oil from the influent.
Plant C
This production facility consists of two plants, the older of the two
dating from 19^5 and the newer one coming on stream within the last decade.
The facility is located in an industrialized area on the fringes of an
urban center. Most of the land within the plant boundaries is occupied
by production buildings and by the necessary auxiliary buildings, waste
treatment facilities, and parking areas. The facility produces only passen-
ger tires(both bias ply and radial). Raw material consumption is approxi-
mately 3^9,000 kilograms(770,000 pounds) per day. Exact unit production
rates are unknown, although the figure is known to be well above 20,000
units per day.
The principal process wastewaters are water and steam leakages, overflow
from various sumps, and runoff from oil storage areas. Water leakages
occur throughout the plant wherever there is water-cooled machinery, such
VII-6
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DRAFT
as mills and Banburys. Water and steam leakages occur In the press
area due to leaking seals, failing bladder bags, and leakages in the
hydraulic water system. The process wastewaters scavenge oil and solid
materials, which flow to the nearest drain. Oil and solid material
accumulate on the floor and in the various machinery basins due to drip-
ping and leaks from the Banbury dust rings, mill and pump oil seals,
open gears, and the hydraulic water system. Runoff from oil storage areas
occurs during rainstorms and washdowns, and is another source of oily
process wastewater.
This plant at one time had a process wastewater discharge of soapstone
solution. After extensive studies showed that this solution caused
excessive BOD and total solids in the wastewater, this discharge
was eliminated. The current practice is to recycle this solution.
Wastewater streams resulting from the use of other solutions in the plant,
such as the latex dip, have also been eliminated. These streams are
dumped into a sump, which is periodically emptied into drums and sent
to a landfi11 s ite.
The principal non-process wastewaters are boiler and cooling tower blow-
down, once-through tread cooling water, and water treatment wastes. In
all cases, dissolved solids are a problem, and suspended solids will be a
problem in the water treatment waste and boiler blowdown.
Process wastewaters and all the non-process wastewaters(with the exception
of boiler blowdown) are combined and then directed to a primary treatment
facility. This treatment facility consists of two settling basins, oper-
ating in parallel. Each provides 24 hours retention for the waste streams.
Settleable solids are removed periodically(approximately every two years),
and floating oil is removed by a belt filter. Boiler blowdown and sani-
tary wastes are treated in a package extended aeration sanitary waste-
water treatment plant. All treated wastewaters are discharged to the
river.
Plant D
This plant, started up in the early 19^0's, is located in an urban, indus-
trialized area. It has recently undergone extensive modifications, and,
therefore, production levels are not well established. However, past data
indcate that the plant is producing 22,000 passenger, truck, and tractor
tires per day. The plant also produces camelback. Raw material consump-
tion is in the neighborhood of 840,000 kilpgrams(1.85 million pounds) per
day.
Raw water is supplied by the municipality and from company-owned deep
wells. The city water is used to supply domestic and air conditioner
VI 1-7
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DRAFT
cooling needs. The wells supply once-through cooling water, cooling tower
makeup, boiler feed water, and processing solution makeup.
The principal process wastewaters from this plant include: water leakages,
steam leakages, a weekly washdown of the soapstone recirculation system,
equipment and floor cleaning washdowns, and minor runoff from the oil
storage area.
Water leakages arise from the oil seals and open gears on mill calendars
and pumps and from the hydraulic water system used in the Banburys and
presses. Steam leakages occur in the press room from broken or leaking
seals and failing bladder bags. Both types of leakage are heavily laden
with oil picked up from the seals and from lubricating oil drippings. The
soapstone recirculation system is cleaned out once a week, and the effluent
has high BOD and suspended solids loadings. The floors are cleaned with
an automatic sweeper that uses a soapy water solution as a cleaning agent.
Drainage from this system also has a high BOD and suspended solids load-
ings. Steam cleaning is used for small machinery parts, and the discharges
are significantly contaminated with oil.
Water and steam leaks in the press area are pumped to an oil separator,
where the floating oil is removed and disposed of by an outside contractor.
Water leakages in the mill area are kept at a minimum by careful house-
keeping and maintenance practices, and do not appear to be a serious pro-
blem. Runoff from oil storage areas is collected in sumps, which are
pumped out on an "as required" basis.
Floor-cleaning machinery discharges and steam-cleaning discharges flow
into the sanitary sewer.
The principal non-process wastewaters are boiler and cooling tower blow-
downs, water treatment wastes, and once-through cooling water. In the
first three cases, dissolved solids constitute a problem. Boiler blowdowns
and water treatment wastes may also contain high concentrations of suspended
solids, depending on the treatment process being used. COD and pH may also
be problems.
There is no end-of-pipe wastewater treatment facility which covers the
entire process wastewater stream. Some non-process wastewater and the
weekly dump of the soapstone slurry are directed to a holding basin
for removal of settleable solids before discharge.
VII-8
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DRAFT
Plant E
This facility which was started up in 1920, is a sprawling complex
occupying 25 major buildings and more than Ik acres of ground. Although
it is located in a very congested urban area, the plant boundaries en-
close approximately 13 acres of open ground.
The plant was originally set up to produce many rubber products, includ-
ing tires, belting, and inner tubes. However, with the passage of time
and because of specialization, production of all rubber products with the
exception of tires has been discontinued. Current production levels are
10,400 passenger tires per day and 4,400 truck tires per day. Total raw
material consumption is 210,160 kilograms(462,900 pounds) per day.
Production facilities are located in three buildings. The Banburys and
mills of the compounding operation and the presses of the molding and
curing operations are located in separate buiIdings(Banbury and Press
Buildings). The mills, extruders, calendars, etc. of the tread and bead
formation lines and of the fabric-coating operations are all located in a
large buiIding(Rubber Mill Building) located between the compounding and
curing buildings. The buildings are interconnected so as to approximate
a continuous product ion line. Fabric is shipped to this plant pretreated,
and no additional dipping operations are performed.
The plant has two separate sources of raw water supply: well water and
municipally supplied water. The well water is used primarily for cooling
tower makeup, and the municipal(city) water is used as boiler makeup,
after treatment. The city water is also used in making the soapstone
and other solutions used in tire manufacture.
The principal process wastewaters include water and steam leakages, steam
cleaning, and wet air-pollution equipment discharges. Water leakages
arise from water-cooled machinery, such as mills, Banburys, tread extruders,
and tread cooling tanks. In addition, water can escape from the hydraulic
water system used in the Banbury and press areas. Wjter and steam leakages
occur in the press building due to broken seals and failing bladder bags.
These wastewater streams are heavily laden with oil picked up from the seals
and from floor areas and basins. Machinery parts such as gears and bearings
are cleaned with steam, and the resulting waste contains both oil and suspend-
ed solids. Grinding operations within the plant are equipped with wet par-
ticulate collectors. Effluents from these collectors are small in volume
but contain a high concentration of heavy rubber as suspended particles.
Zinc and chromium are used as corrosion inhibitors and will therefore be
present in the collector discharge.
VI 1-9
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DRAFT
Leakages, both steam and water, are collected in two sumps, one located
In the press building and the other in the rubber mill building. These
sumps separate the oil, and the resulting underflow is released to a
sanitary sewer. Sanitary sewers within the plant are connected to the
municipal sanitary sewer system and eventually to the municipal waste-
water treatment plant. Oil from the sump is removed periodically by
maintenance personnel.
Steam cleaning of machinery parts is carried out in a non-congested out-
door area of the plant. Curbing and concrete flooring are used to direct
the wastewaters into three small basins connected in series. The area
is supplied with a roof to prevent storm water from diluting the wash
water and upsetting the settling operation. Storm runoff from this area
is directed into the storm-water catch basins. These catch basins act
as gravity separators, allowing the separable suspended s.olids to settle
out and oil to float to the surface. The effluent from the basin dis-
charges into the sanitary sewer. Solids and oil are removed from these
basins periodically.
The effluent from the wet particulate collectors flows into a set of
similar settling basins, where most of the solids are settled out. The
effluent then discharges into the sanitary sewer. These basins are
equipped with automatic solids-removal equipment.
All solids and oil removed from the various treatment facilities are
containerized and disposed of by contract hauler to a landfill.
The principal non-process wastewaters are boiler and cooling tower blow-
downs, and water treatment wastes. In all cases, dissolved solids are
present in the wastewater, generally at high concentrations. Boiler blow-
downs and water treatment wastes also contain high concentrations of sus-
pended solids. The water makeup for the cooling tower which supplies cool-
ing water to the press building is treated with a corrosion inhibitor con-
taining chromium and zinc, and these metals are present in the blowdowns.
At this plant, there is no end-of-pipe treatment facility. All contam-
inated process and non-process wastewaters (with the exception of the main
cooling tower) are discharged to a municipal treatment facility.
Plant F
This production facility, built in 1928, is located in a minor urban
area, on a large (more than 2.8 billion square meters (700 acres)) plot
of ground, of which the actual production facility occupies only a small
proportion.
Production lines include passenger tires, truck tires, inner tubes, flaps,
bladders, and camelback. The plant, as currently designed, is divided up
Into separate product unit buildings for each end product. Daily production
rates are currently running at 40,000 passenger and truck tires, 36,000
VII-10
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DRAFT
inner tubes, 13,000 bladders and flaps, and 60,000 Ibs. of camelback.
Daily raw material consumption is 681,000 kilograms (1.5 million pounds).
This plant utilizes river water for production and utility purposes and
city water for domestic purposes.
The principal process wastewaters from this plant include: water and steam
leakages and overflows, runoff from process oil-storage areas, soapstone
solution spillages, and wash downs and runoff from process or storage areas.
Water leakages occur at various water-cooled machinery units, including
mills, Banburys, tread extruders, and tread cooling tanks. In addition,
water can escape from the hydraulic water system used in the Banbury and
press areas. Water and steam leakages occur in the press area duetto
broken seals, failing bladder bags, and overflows from the collection
pumps, 051 and solid matter which have collected on the floor are
scavenged by these various water streams and are carried untreated to the
drainage system. Oil on the floor spaces is lubricating oil which has
dripped or leaked from oil seals on mills, pumps, and like equipment,
from open gears, from gear boxes and from the hydraulic water system.
Oil and solid materials result from leakages at the Banbury dust and
oil rings.
Soapstone solution which has spilled and dripped on the floor is^washed
down periodically and enters the drainage system untreated. Typical
contaminants are BOD, suspended solids, and dissolved solids.
Washdown water and storm runoff are allowed to drain through the process
oil-storage area, where oil is scavenged and carried to the drainage system.
Before discharge to the sewer, this stream is pretreated in a baffled
sump, where oil is separated, removed by a belt filter, and disposed of
at a sanitary landfill. The sump is baffled, but provides no excess
capacity for oil separation during a storm runoff.
The aforementioned process wastewaters are mixed with non-process waste-
waters in the drainage system. The non-process wastewaters include once-
through river water, boiler blowdown, and a small overflow from the num-
erous small pump sumps located throughout the plant.
End-of-pipe treatment facilities consist of a two-stage detention basin.
The primary facilities provide approximately 2,000 square meters for
bottom and surface removal of separable materials. During dry-weather
flow the surface loading is ^9,000 1iters/day/sq. m. (1,200 gals/day/sq. ft.),
which is too high for effective treatment of wastewater of this character.
It is estimated that the facilities provide little or no treatment whatso-
ever during periods of significant runoff. The primary facilities are-
followed in series by a pond baffled down the middle to retain floatable
materials. Some additional settleable materials are also contained, but
no facilities are provided for removal of floatable or settleable materials
except on "as required" basis.
vii-n
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DRAFT
The secondary pond provides a theoretical detention time of twelve hours
during dry-weather flow. However, this is significantly reduced by short
circuiting attributable to the location of the inlet and outlet connections.
Surface loading on this pond is adequate for removal of separable materials
during dry-weather flow as well as during storm weather runoff conditions.
However, the surface of the pond is subject to wind turbulence, which may
remix the separated floatable materials.
Plant G
This production facility, built in 1928 is located in a highly congested,
highly industrialized suburban area. Built and originally operated by
another company, it was bought by the current operator in the 1930's and
converted to tire manufacture. The facility produces passenger and truck
tires. Daily production rates are currently running at 18,300 passenger
tires and 1,150 truck tires. Raw material consumption is over 2^6,000
ki lograms (5^-1 ,000 pounds) per day.
The plant occupies approximately 280 million square meters(70 acres) of
ground, with most of the land occupied by production and warehousing
buildings. Because of the industrial development around the plant, there
are no foreseeable plans for expansion at the current facility.
Well water is the only source of raw water supply to this plant, and is
used for all plant water needs.
The principal process wastewaters from this plant are water and steam
leakages, and washdown and runoff from the machine shop area. Water
leakages occur in the press are due to broken or leaking seals and
failing bladder bags. These process wastewaters scavenge oil and solid
materials as they flow to the drains. Oil and solid materials accumulate
on the floor and in various machinery basins due to drippings and leaks
from the Banbury dust rings, mill and pump oil seals, open gears, and
the hydraulic water system. In the machine shop area, steam used for
cleaning of parts and runoff from painting and washdown operations is
allowed to enter the storm drain; these wastewaters may be contaminated
with both oil and solid material.
Runoff from the oil-storage is not a problem in this plant, because the
drain in this area has been surrounded by a curb which prevents normal
spills from entering the sewer system. In addition, there is a straw
filter covering the drain inlet. Oil that spills in this area is pumped
into a special storage tank which is periodically emptied; this waste oil
is sent to a landfill site.
Both process and non-process wastewaters flow to a common sewer, where they
are discharged to the municipal storm sewer. Before leaving the plant, all
wastewaters must flow through a shredded plastic filter which retains float-
able oil. This filter is replaced periodically. The oil trapped behind
the filter is also removed periodically.
VII-12
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DRAFT
Plant H
This facility, built in 19^5, is located in highly congested and highly
industrialized area. Essentially all of the plant-owned land is utilized
for production and warehousing facilities, utility systems, and wastewater
treatment facilities. Expansion of the current plant would necessitate
the leasing of land from adjacent landowners.
The facility produces truck tires, industrial and farm tires, giant off-
the-road tires, and various other minor products including bladders and
rubber gaskets for the curing presses.
Current production levels for the major products are 6,850 truck tires
and 2,*t30 industrial, farm and giant off-the-road tires per day.
Sources of raw water include surface water from a nearby river and muni-
cipally supplied water. Surface water is used as the primary source of
once-through cooling water and for makeup to the cooling tower and other
recirculating water systems. City water is used as for boiler feed
water and also as a backup for the surface water in recirculating water
systems.
The principal process wastewaters are from water and steam leakages from
presses and mills. These leakages occur at the oil seals of mills, at the
hydraulic water system, and at the curing presses. The leakages scavenge
oil and soilds spilled in press and mill basins due to open bearings and
lubrication of machinery parts.
The principal non-process wastewaters are the overflows and blowdowns from
various recirculating water systems, the once-through cooling water, boiler
blowdown, and water treatment wastes. Contaminants in these wastewaters
include suspended and dissolved solids; these wastewaters also require pH
adjustment.
Whenever possible, oil that leaks or spills onto the floors or basin areas
is collected. This oil either is drummed and sent to a sanitary landfill
or is filtered and reused. Plant engineers are currently examining the
feasibility of using this oil as a fuel admixture in the boilers. With the
oil on the floor kept at a minimum, less can be scavenged by water or steam
contact. There is however, no treatment at this plant for the oily waste-
waters that do occur; they would be discharged with either once-through
cooling water or the utility wastewaters.
There is no end-of-pipe treatment for the once-through(non-contact) cooling
water; except for oil picked up due to leakages and spills this water is
VII-13
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DRAFT
uncontaminated, and discharges back to the river. Discharges from
the other utility systems, such as boiler blowdown, cooling tower blow-
down, and water treatment wastes are directed to an effluent basin, where
settleable solids are removed. The surface loading is (600 1 iters/day/sq.
meter), and the theoretical detention time is 24 hours. There is no provision
for continuous removal of solids or oil. Discharges from the effluent
basin are directed via a sanitary sewer system to a municipally operated
treatment plant.
Plant I
This plant, built in the late 19th century, is now involved in the manu-
facture of inner tubes, valves, flaps, and simlar items associated with
automobile tire applications. Raw material consumption is approximately
75,000 kilograms (165,000 Ibs.) per day. This amounts to an equivalent of
over 50,000 inner tubes per day.
The production facilities occupy a multi-story building in the downtown
area of a major city. There has been no expansion at this plant for the
last fifty years. Because of the extremely tight land situation and
because of the relatively stable tire-tube market, no expansion is planned
In the foreseeable future.
All the raw water used in this facility is provided by the city.
Principal process wastewaters are water and steam leakages, and the wash-
down of dusty areas within the plant. These streams become contaminated
with oil and dust that is scavenged from floor and machinery areas. These
wastewater streams flow into a sewer and are combined with non-process
wastewaters before discharge from the plant. Non-process wastewaters
include once-through cooling water, cooling tower and boiler blowdowns,
and water treatment wastes. Suspended solids will be present in substan-
tial quantities in the blowdowns and water treatment wastes.
The city sewers are combined sewers; consequently, domestic, process, and
non-process wastewaters are mixed and treated in the municipal wastewater
treatment faci1ity.
The housekeeping practices in the plant are unique. Spillages of soap and
soapstone solutions do occur, but the quantities are so slight that they
tend to evaporate on the spot; soapstone solution is neither dumped nor
recirculated. In processing areas, water is not used for washdown. Dust
is such a Problem(due to the use of soapstone in dry form) that any attempt
to use water for washdown merely complicates the problem.
There were no wastewater treatment facilities operating at the plant
at the time of the visit. The upgrading of air quality within the
plant has completely occupied the attention of the engineering staff,
thus relegating concern for water effluent quality to a secondary
pos i t i on.
\l\\-\k
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DRAFT
Synthetic Rubber Plants
Plant J
Emulsion styrene-butadiene (SBR) and acrylonitrile-butadiene (NBR) synthe-
tic rubbers are produced at this plant. The annual production capacity is
390,000 metric tons of SBR and approximately 10,000 metric tons of NBR.
The plant is located in an industrial area with land available for expan-
sion.
Both SBR and NBR are produced by emulsion polymerization processes. The
monomers are shipped into the complex from adjacent plants. The SBR
crumb is produced in non-extended, oi1-extended, and carbon-black-extended
forms, while the NBR is produced in non-extended form only. The crumb
rubber is used principally as tire rubber. There are sixteen coagulation
and finishing lines in the plant.
The plant's intake water comes from two sources. River water is used for
cooling tower makeup, crumb rubber washing-slurrying, and area washdown.
Plant well water is softened and then used for solution preparation. The
plant does not have its own steam generating plant and purchases steam
from an adjacent facility.
The main process wastewaters are generated at monomer recovery, crumb coag-
ulation, and rubber washing operations. Decant water from the monomer de-
cant system is recycled in part to the crumb slurrying operation. The
remainder, containing styrene and acrylonitrile, is discharged to the pro-
cess sewer system and has a significant COD. The coagulation liquor over-
flow is a brine-sulfuric acid mixture, with a low pH, high total dissolved
solids, and moderate COD. The crumb slurry overflow contains COD, crumb
rubber particles as suspended solids, and oi1(when oil-extended forms are
produced). The crumb-laden slurry overflow and the overflow of coagulation
liquor pass through crumb settling pits where the crumb separates and is
removed periodically by a scoop. The cleaning of the crumb pits results
in a temporary upset as the settled crumb is disturbed and re-suspended.
This results in poor effluent quality from the pits for a short period.
The cleanup wastes from the latex vacuum and steam stripping units are
another process wastewater source. This wastewater is characteristically
high in COD and suspended solids, and contains uncoagulated latex. ^The
units are cleaned periodically and large volumes of water are used in this
operation. The resulting wastewaters are passed through settling sumps,
where rubber solids settle out.
Clean-out wastewaters from reactors and holding tanks are also produced
on an intermittent basis. These wastewaters, containing COD and suspended
solids, both as rubber solids and as uncoagulated latex, are also passed
through settling pits. Spent caustic soda scrub solution used to remove
VII-15
-------
DRAFT
inhibitor from butadiene prior to its polymerization, is bled into the
plant effluent; this waste stream has high COD, pH, alkalinity and
color, and contains some phenols. Its flow rate, however, is very low.
The carbon black storage facilities, consisting of railroad unloading
equipment, a storage hopper, and slurrying equipment, generates a waste-
water which is laden with fine carbon black particles. This wastewater
is the result of the washdown and cleanup of carbon black spills and
air-borne fallout. These wastewaters pass through two settling pits,
which operate in parallel. When one pit is full of carbon black waste-
water, the wastewater is allowed to settle and the second pit is filled.
The settling pits achieve satisfactory clarification of the wastewater.
The utility wastewaters consist of cooling tower blowdown and water soft-
ener regeneration wastes. (There is no boiler blowdown, since the plant's
steam is purchased.) One cooling tower has a very low blowdown rate,
since a high proportion of the tower's makeup is steam condensete. The
other cooling tower has a normal blowdown rate and generates wastewater
containing chromium, zinc, and other heavy metal ions.
The plant's effluent treatment system consists of chemical coagulation
and primary settling, followed by an aeration lagoon and a settling
lagoon. The primary settling facility and the sludge handling system
are shown in Figure VI1-1. In the chemical coagulation process, the pH
of the influent wastewater is first adjusted using sulfuric acid and
caustic soda. Coagulation chemicals (alum and polyelectrolyte) are added,
together with clay. The latex and fine suspended solids coagulate
around the clay, which causes the coagulated solids in the primary clari-
ffer to sink. The solids from the primary clarifier are thickened and
pressure filtered, using a lime slurry and filter aid. The filter cake
is hauled away by truck to a landfill. The thickener supernatant Is
returned to the head end of the plant, and the filtrate is discharged to
the aeration lagoon. The plant effluent quality is good:
COD 325 mg/L
BOD 25 mg/L
SS 30 mg/L
The high residual COD concentration is typical of the high biological
resistance of the wastewater components. The plant currently is conduct-
ing pilot studies to investigate the feasibility of using activated car-
bon to reduce the residual COD. The results to date indicate that a final
effluent COD of 130 mg/L could be reached, but the company concluded that
the costs to implement this system would be prohibitive.
VII-16
-------
FIGURE VIM
PLANT J-. CHEMICAL COAGULATION AND CLARIFICATION PLUS SLUDGE HANDLING SYSTEM FOLLOWED BY BIO-OXIDATION TREATMENT
EFFLUENT TO
At TREATMENT
7^
FINAL
EFFLUENT
tL ADCITION
PEED MIX
i
r*
^- — •-
t
FINAL
EFFLUENT
OISCHARGE
CftSCftOE
SETTLING
ZONE
SLOW
MIX
U
t
L
z
r.
\L
pH CONTROL
SLO» MIX SLUOGE
CONDITIONING
15 PLATE
HIGH PRESSURE FILTER
AIR
.CORE
BLOf
FILTER CAKE TO
HOPPER FOR
FINAL DISPOSAL
RAW
INFLUENT
-------
DRAFT
Plant K
The plant complex consists of emulsion and solution styrene-butadiene
rubber (SBR) production facilities. The annual production capacity of
emulsion SBR is 200,000 metric tons and of solution SBR is 130,000 metric
tons. The complex is located in an industrial area with virtually no
land available for further expansion.
The emulsion crumb rubber is produced in non-extended, oil-extended, and
carbon-black-extended forms. The emulsion rubber processing plant is
arranged into essentially two parallel operations; each operation con-
sists of a solution preparation building, a polymerization area, a coag-
ulation and finishing building, and a monomer recovery complex. The
solution crumb rubber is produced also in non-extended, oil-extended and
carbon-black forms. The solution rubber processing facilities are simi-
larly divided into two parallel units; each unit consists of a polymer-
ization area, a crumb slurrying and finishing building, and a solvent
and monomer recovery complex. The solvent used is hexane.
The plant water supply is from on-site wells. The boiler feed water is
subjected to hot lime softening and normal boiler feed treatment chemi-
cals. The cooling tower makeup is treated with corrosion inhibitors,
anti-seal ing agents, and slimicides. The process water used in emulsion
rubber production is zeolite softened. Untreated well water is used for
slurrying, rinsing, and washdown.
The principal emulsion process wastewaters are the coagulation liquor
overflow, the crumb rinse overflow, and the monomer recovery streams. The
coagulation liquor is a sulfuric acid-brine mixture with a low pH, high
total dissolved solids, and moderate COD. The crumb rinse overflow con-
tains floatable crumb rubber as suspended solids. In addition, the slurry
overflows have high total dissolved solids and moderate COD.
The coagulation liquor and crumb slurry overflow pass through settling
pits, where the rubber solids separate. Under normal operation, the
separator pits work well, but they are not cleaned frequently enough, and
short-circuiting occurs. Furthermore, during the cleanout operation the
pit is disturbed, and the once-separated rubber escapes into the effluent.
Some pits contain an oil layer because baler hydraulic fluid or extender
oil leaks onto the floor and is washed down into the settling pit.
The wastewaters from the monomer recovery area are characterized by high
COD and suspended solids. These wastewaters originate at monomer decant
systems and cleanup operations, and contain uncoagulated latex. The waste-
waters from the periodic cleaning of the monomer recovery stripping columns
VII-18
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DRAFT
contain hi gh concentrations of COD and of latex and rubber solids. These
waters pass through settling sumps to separate the rubber solids and the
floating oils. These pits are also cleaned out periodically.
The caustic scrub solution is discharged to the final effluent when it
becomes saturated with inhibitor. This wastewater is of very low flow
(less than 1 gpm), but has high COD, pH, alkalinity and color. When the
latex storage and the blend tanks are cleaned, the latex-laden rinse
water can be used for latex blending if its solids content is greater
than 2 percent. Tankage rinse waters with rubber solids levels of less
than 2 percent are discharged to the plant effluent. The major contamin-
ant in this water is uncoagulated latex.
The carbon black slurrying area is equipped with a settling pit which
receives spillages and washdown wastewaters. The carbon black settles
out, and the wastewater overflows at a very low flow rate into the final
effluent. The settling pit is cleaned out periodically with a vacuum
truck.
The solution rubber process wastewaters are very similar to those of other
solution rubber production facilities. The principal streams originate
at the crumb slurrying operation and the solvent-monomer recovery areas.
The crumb slurry overflow has moderate COD, suspended solids, and total
dissolved solids. It passes through a settling sump, where suspended
solids are removed. The wastewaters from the solvent and monomer recov-
ery areas are stripped condensates and decants, and are characterized by
moderate amounts of COD and floating oils.
The utility wastewaters are boiler and cooling tower blowdown and water
treatment wastes. The boiler blowdown has high total dissolved solids and
a high pH. The cooling tower blowdown contains high total dissolved solids
and moderate levels of chromium and zinc from chemical inhibitors. The
spent lime slurry from the hot lime water treatment system exhibits a high
pH and suspended solids level. The lime slurry settles out in the plant
drain and must be mechanically removed at periodic intervals. The waste
from the zeolite softener regeneration is a concentrated brine solution
with high total dissolved solids.
The wastewater treatment system consists of air flotation clarification
and biological treatment (refer to Figure VI1-2). The wastewater first
passes through a mechanical bar screen which removes large rubber solids,
and is neutralized to pH 7.0 and dosed with coagulant and flocculant aids
in a rapid-mix tank. The wastewater then.passes through a flocculator
tank and into the primary clarifier, where a slip-stream laden with air
is released near the bottom of the unit. The rising air bubbles carry
the suspended solids and oil-type contaminants to the surface, where they
VII-19
-------
FIGURE VII-2
PLANT K: AIR FLOTATION AND BIO-OXIDATION WASTEWATER TREATMENT FACILITY
N>
O
FINAL EFFLUENT
HAW
WAJTEIATER
k
i
k
i
k
FEED TANK -
Qj
txj—
£*
ALUM
COAGULATION
TANK
CAT. POLYMER
FEED TANK
ANIONIC POLYELECTROLTTE
KAKE-UP TANKS
AERATED LABOON
FEED
TANK
O
73
ALUM FEED TANK
-------
DRAFT
are skimmed off. The clarified effluent flows into an aerated lagoon,
equipped with six aerators, where it is retained for 2k hours.
Effluent from the aerated lagoon is pumped to the secondary air flota-
tion clarifier, where biological solids are removed. Operations include
rapid mix of coagulation chemicals, flocculation, and clarification.
The primary and secondary sludges are pumped to an on-site sludge lagoon
for dewatering and drying. Studies are being conducted to dispose of
this sludge by off-site landfill or via incineration. The treatment plant
produces a high-quality effluent. Pollution parameters which are still
present at substantial levels after treatment are total dissolved solids
and COD. The residual COD underlines the inherent biological resistivity
of some of the wastewater const!tutents.
Plant L
This plant has SBR, polybutadiene, resin, and oil-additive production
facilities. In addition, there is a rubber compounding facility which
produces sheet rubber as a customer service. The annual production
rates are:
Cold-emulsion SBR 120,000 metric tons
Hot-emulsion SBR 3,700 metric tons
Solution-type polybutadiene 52,000 metric tons
Solution SBR 10,000 metric tons
The plant is located in a rural area with land available for expansion.
Emulsion rubber production stared in 19^3, solution type polybutadiene
in 1960, and solution type SBR in 1963.
The cold-emulsion type SBR is produced in non-extended, oil-extended,
and carbon-black-extended forms. It is used primarily in tire manu-
facture. This type of emulsion SBR is similar to that produced at the
other plants described in this section. The process for hot-emulsion
SBR is a higher-temperature polymerization and is non-extended; this
product is used primarily for electrical wire covering. The solution
type polybutadiene is produced as non-extended and oil-extended rubbers
and is used primarily in tire manufacture; toluene is the solvent.
Solution SBR is non-extended and has several end uses. The butadiene
used in the plant is received by pipeline from a neighboring plant,
and the styrene is shipped in by tank truck.
The plant's water supply consists of well water. The plant does not have
steam generating facilities but purchases steam from an^adjacent plant.
The well water is treated with corrosion inhibitors, slimicides, and dis-
persants for cooling tower makeup and is softened to provide process water
for preparation of the emulsion rubber solution.
VII-21
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DRAFT
The process wastewaters from emulsion rubber production originate
principally in two areas: crumb slurrying and monomer recovery oper-
ations. These wastewaters are typical of emulsion rubber production
facilities. The slurry overflow is passed through a crumb pit to
separate the crumb rubber fines. The monomer strippers are cleaned
periodically. The vacuum stripping vessels and steam stripping columns
are flooded with wash water, and the residual latex and rubber solids
are discharged with the wash water. The units are finally rinsed, pro-
ducing more wastewater with additional suspended solids.
Both of the solution type rubbers are produced by similar processes.
The main process wastewaters are the crumb slurry overflow and the
solvent-monomer recovery wastes. The slurry overflow is passed through
a pit, where the crumb rubber is separated and periodically removed.
As is the case with all the plants visited, the crumb pits are not
cleaned regularly, and during cleaning the crumb is disturbed and
escapes the pit. The wastewaters from the solvent-monomer recovery
area are condensates from monomer decant systems and solvent distil-
lation condensates. They are characteristically high in COD, BOD, and
total dissolved solids.
The plant's utility wastewaters are cooling tower blowdown and zeolite
softener regeneration wastes. The blowdown has high chromium and zinc
concentrations, from the corrosion inhibitor. The softener regeneration
waste is a strong brine solution and therefore has a high total dis-
solved solids concentration.
The plant's wastewater treatment facilities consist of settling ponds,
followed by aerated and stabilization lagoons. The plant's final ef-
fluent is treated with alum and polyelectrolyte to obtain proper coagu-
lation of latex solids and fine rubber crumb particles.
The wastewater flows through two parallel sets of two settling ponds
each, where the settleable solids and oils separate. The wastewater then
flows through two further settling ponds in series. The total detention
time in the six settling ponds is four days. Troublesome oil is skimmed
from the ponds. The wastewater then passes to a mechanically aerated
lagoon, which provides approximately three days of detention. The
aerated lagoon effluent passes through two oxidation ponds, which
stabilize the wastewaters and settle the biological solids. The total
detention time in the oxidation ponds is approximately thirteen days.
Although overall treatment provided by the facilities is good, the
effluent quality (BOD particularly) does not meet the State requirements.
It has been established by analyses that the stabilization ponds are not
producing the soluble BOD removals that were expected, but the cause of
VI1-22
-------
DRAFT
the problem has not been determined. There are indications that the
effectiveness of the ponds is dependent on the water temperature (and,
therefore, the time of the year) but this hypothesis has yet to be
confi rmed.
Plant H
The total plant complex consists of a butadiene plant and a polybutadiene
production facility. The butadiene plant started production in 1957 and
the polybutadiene facility in 1961. The polybutadiene production facility,
which uses butadiene as a feed monomer, has a capacity of 85,000 metric
tons per year and is adjacent to the butadiene facility. The complex is
located in a rural area with good potential for expansion and land
acqu i s ition.
The polybutadiene is produced by a solution-type polymerization process
using butadiene as the feed monomer and hexane as the solvent. The crumb
polybutadiene rubber is used principally as a tire rubber. In addition,
a high-grade variety is used as an ingredient in the manufacture of
impact-resistant plastic. The rubber is not oil- or carbon-black-extended.
The polybutadiene plant has two sources for water supply, well water
and river water. The well water is used primarily for boiler and
cooling tower makeup, while the river water (after clarification,
filtration, and softening) is used in the crumb slurrying operation and
for general plant cleanup.
The principal process wastewaters originate in the solvent-monomers
reclaim area and in the crumb slurrying operation. The wastewaters
produced in the reclaim area originate from several operations:
solvent recovery, monomer recovery, and feed drying. The major
component of these wastewaters is produced by a decant system fed from
the solvent and monomer stripping operation. This wastewater is
relatively clean, its only contamination being due to hexane at satura-
tion solubility. The other wastewater streams from the reclaim area
have very low flow and are essentially innocuous with the exception of
dissolved hexane.
Impure recovered butadiene monomer is returned to the butadiene production
plant for purification. Heavy slops (oily wastes) produced in the hexane
recovery operation are sent to the butadiene plant for disposal or are
used as a waste fuel. The other major process wastewater, the crumb
slurrying overflowiis laden with rubber crumb in the form of suspended
solids. The suspended solids are significantly reduced by in-plant
screening and clarification in a pit.
At least one finishing line recovers the solid rubber product directly
from the rubber cement. No water rinse system is used. The "finishing
VII-23
-------
DRAFT
machine" takes cement and produces material ready for baling and
packaging. This machine was not seen, and presumably is some type of
extruder for removing solvent. It obviously has a potential for reducing
the effluent flow and leading attributable to the crumb rinse overflow.
There are two other process-associated wastewaters. Spent caustic soda
solution, from scrubbing of butadiene inhibitor (to prevent premature
polymerization during storage and shipping), is batch discharged. This
stream has extremely high COD, pH, alkalinity, and color, and contains
phenols. The batch discharge is containerized in a pit and bled into
the plant effluent at a very low flow rate. With such handling or
pre-treatment, it poses no wastewater problem.
The other wastewater which should be mentioned results from frequent
area washdowns. This picks up primarily crumb rubber and oils. The.
oils originate from leaks in baler hydraulic systems and leaks of pump
seal oil. In solution-type polymerization, water must be eliminated
from much of the process equipment. Oil is used to seal and lubricate
the process pumps. The washdown wastewaters contribute the major
proportions of suspended solids, soluble organics, and oils in the final
effluent.
The principal non-process wastewaters are boiler and cooling tower
blowdowns and water treatment wastes. The wastewater characteristics
of these streams are high total dissolved solids, and moderate COD,
suspended solids, and pH. The cooling tower makeup is treated with a
corrosion inhibitor containing chromium and zinc. These metals appear
in the cool ing tower blowdowns.
The total effluent from the butadiene and polybutadiene plants passes
through an oil separator and straw filter before discharge. Since the
quantity and loading of the wastewaters from the butadiene plant are
far greater than those from the polybutadiene plant, no meaningful
treatment data could be obtained. The raw wastewater flow and loading
of the polybutadiene plant were the lowest of any of the synthetic
rubber plants visited.
It is planned to expand the synthetic rubber plant production facilities
shortly. This expansion will approximately double the existing synthetic
rubber production capacity.
Plant N
The plant complex consists of isoprene, polyolefin resin, polyisoprene,
and polybutadiene production facilities. The complex was completed in
1962. The polyisoprene production capacity is 65,000 metric tons per
year and the annual production of polybutadiene is 110,000 metric tons.
The complex is located in a rural area with expansion capability and
undeveloped land of its own.
VI1-
-------
DRAFT
The polyisoprene is produced by solution polymerization with hexane as
the solvent, using isoprene from the neighboring isoprene plant as feed
monomer. Several types of polyisoprene are produced in this facility.
Each type requires a separate production run on common processing
equipment. The crumb rubber is used mainly for tire manufacture and is
not oil or carbon black extended.
There are two polybutadiene lines which employ slightly different
processing techniques. There is no significant difference in the over-
all wastewater flows and loadings from these two processes. The
polybutadiene is consumed principally in tire manufacture, and
approximately 50 percent of the polybutadiene is oil extended.
The plant's water supply is river water. Process and boiler makeup
water receives extensive treatment, consisting of coagulation, clari-
fication, filtration, chlorination, and softening.
The main process wastewaters are produced in the monomer-solvent reclaim
area and the crumb slurry ing operation. The wastewaters generated in
the reclaim area have low flow rates and, with the exception of saturatin
with solvent or monomers, are relatively clean.
Part of the recovered isoprene is sent in a slip stream to the isoprene
production plant for purification. This procedure serves to blow down
the accumulated impurities. Impure butadiene recovered from the poly-
butadiene plant is hauled from the plant as a waste. The crumb slurrying
overflows are passed through settling pits where the crumb is trapped
and periodically removed. Surfactants are added to the crumb-water
mix during the coagulation operation to prevent the crumb from
agglomerating into masses which are too large. These surfactants enter
the crumb slurry overflow.
One type of polyisoprene produces a crumb slurry effluent which has a
considerably higher dissolved organic loading than the other polyisoprenes
or the polybutadiene types. This difference is inherent in the chemistry
of the process and is not a general or widespread problem in the
synthetic rubber industry.
Area wash-down and cleanup is a major contributor of contaminants to
the final effluent. Crumb screens used inside the processing areas
are hosed down to remove coagulated rubber. The resulting wastewater
has high suspended solids levels and is passed through the crumb
settling pits. Spent caustic solution from the inhibitor removal system
is containerized and bled into the final effluent. It has the typical
high, COD, pH, alkalinity, and color.
VII-25
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DRAFT
Typical utility wastewaters, principally boiler and cooling tower
blowdowns and water treatment wastes, are generated at this plant.
Characteristics of these wastes are high total dissolved solids, with
moderate COD, suspended solids, and pH. The cooling tower makeup is
treated with a low chromium corrosion inhibitor. This produces chromium
levels in the cooling tower blowdown that are less than one quarter of
those associated with conventional cooling tower corrosion treatments.
The wastewater treatment system consists of an equalization basin
(four-day detention), a neutralization sump, with nutrient addition,
followed by an activated sludge plant (refer to Figure VI1-3). The
waste activated sludge is first thickened and then pumped to a sludge
drying basin on the plant property. The treatment plant gives very
good BOD effluent levels (10 mg/L), however, the effluent COD level is
considerable (250 mg/L). This 5s due to the biological stability of
many of the wastewater components such as the monomers and solvents,
which, although generally considered insoluble, do have some solubility
in water.
An apparent characteristic of the plant's wastewater which can be
attributed to the synthetic rubber production is foaming in the
aeration basins and in the final outfall. This is apparently caused
by excessive use of surfactants by the production personnel in the
crumb rinse operation. Another problem is poor settling of the
biological sludge in the secondary clarifier. Efforts were made to
assist settling, and achieve additional COD removal, by adding activated
carbon granules to the aeration basins upon which biological solids
could nucleate. This did not produce satisfactory results. The current
technique which is proving more successful is the addition of coagulation
aids to the clarifier influent. This, however, is proving to be
expensive on an annual-cost basis. A less frequent problem, but more
serious, is an apparent high BOD slug loading, with associated toxicity,
that unpredictably occurs in the plant influent. This problem is
uncontrolled at present, but appears to originate with the production
of either the polyolefin resin or one type of polyisoprene.
Plant 0
The plant complex consists of polybutadiene, polyisoprene and ethylene-
propylene diene terpolymer (EPDM) rubber production facilities. The
commissioning of all the production facilities occurred between 196?
and 1970. The annual production capacities are: polybutadiene 56,000
metric tons, polyisoprene 50,000 metric tons, and EPDM 25,000 metric tons,
The plant is located in a rural area and has considerable land for
expansion.
VI1-26
-------
FIGURE VII-3
PLANT N: ACTIVATED SLUDGE WASTEWATER TREATMENT FACILITY
RAN INFLUENT
WASTE SLUDGE
TANK
RAW SANITARY
WASTEWATER
EQUALIZATION
BASIN
TOWBRO CLARIFIER
AERATION BASINS
RETURN SLUDGE
CHLORINATOR
SANITARY WASTE
SECONDARY TREATMENT
EFFLUENT
KON! TORINO
STATION
NUTRIENTS
NEUTRAL-
IZATION
BASIN
•ACID
•ALKALI
FINAL
EFFLUENT
-------
DRAFT
Each of the three synthetic rubber products has its own production
facility and is produced in a solution polymerization process. Poly-
butadiene rubber is carbon black extended. The principal end-use of the
crumb rubbers is in tire manufacture.
The plant's water supply is well water. Well water is treated with
corrosion inhibitors and slimicides for use as cooling tower makeup,
and softened for use as boiler quality water.
Principal process wastewaters originate in the crumb slurrying overflow
and presumably in the solvent, monomer, and reclaim areas. Carbon
black added at the coagulation-slurry ing stage is essentially trapped
in the crumb rubber matrix. Carbon black spills and leaks pass through
a settling sump and are allowed to overflow into the final effluent.
The settled carbon black is removed by vacuum truck.
Extender oil that is not entrained in the rubber crumb can contaminate
the slurry overflow wastewater. It is understood that screens, with
higher crumb removals than conventional equipment, have been installed
in this plant. The butadiene monomer is inhibited and presumably there
is an associated spent caustic scrub solution discharge. Area washdown
and cleanup is on a shift-by-shift basis. Whenever possible, the
material is cleaned up in such a manner to eliminate wastes from the
wastewater system.
The plant's utility wastewaters are characterized by high levels of
total dissolved solids and moderate pH. The cooling tower blowdown
has high chromium and zinc content originating from the cooling tower
corrosion inhibitors used.
The plant's wastewaters are first passed through skimming and settling
basins where the rubber crumb is trapped. The waste crumb rubber is
removed every two to three months by dip bucket. The effluent from
these pits flows into two 12,000 sq. meter (3-acre) lagoons. The
process effluent from the lagoons combines with treated sanitary, storm,
and utility wastewaters before entering first a 60,000 sq. meter (15-acre)
lagoon and finally a 120,000 sq. meter (30-acre) lagoon before discharge
to the receiving waters. The final wastewater quality is good. COD, BOD,
and suspended solids are at an approximate level of 50, 5, and 10 mg/L,
respectively. This plant, however, is particularly fortunate in having
considerable land for use as wastewater lagoons. It is not possible^
for all synthetic plants to have the same or even comparable facilities.
Plant P
This plant produces styrene-butadiene (SBR) and aerylonitrile-butadiene
(NBR) latexes. In addition, the plant produces polyvinyl acetate
emulsions and hot melt adhesives. The annual production rates of the
latexes are: styrene-butadiene latex 18,000 metric tons, acrylo-
VI1-28
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DRAFT
nitrile-butadiene latex 3,000 metric tons. The plant is located in a
rural area with land available for expansion.
The butadiene latexes manufactured at the plant are made similarly
utilizing equipment trains of a similar nature. The monomers are
shipped into the plant by both tank car and tank truck. The latexes
produced are used for carpet backing, dipped goods, and adhesives.
The plant's water comes from on-site wells. The water is treated in
a dual-bed demineralizer to supply boiler quality makeup water and
process water for solution preparation. The cooling tower water
is treated with a corrosion inhibitor and algicide.
The principal process wastewaters produced in the plant are generated by
equipment cleanout, area washdown, and stripper condensates. Tank cars
and tank trucks are rinsed with water and the contaminated water is
discharged to the wastewater treatment facility. These wastewaters will
contain monomers and uncoagulated latex. Reactors and strippers are
cleaned of solid deposits with a high pressure watergun and then water
rinsed. Blowdown tanks, filters, compound tanks, and storage tanks
are rinsed with water. In all cases the wastewaters discharged to the
wastewater treatment facility contain organic compounds and latex.
Latex spills and leakages are first coagulated with alum, cleaned up
in-place, and finally washed down. The washings are sent to the treatment
faci1i ty.
Excess monomers are stripped from the latex with steam under vacuum.
The vacuum is produced using steam jets and not vacuum pumps. The
excess styrene, or aerylonitrile, is condensed and discharged to a
receiver. Although the receiver is periodically decanted and the con-
densed styrene or acrylonitrile drummed for disposal, styrene and
acrylonitrile still enter the effluent wastewaters. A caustic scrub
solution is used to remove the butadiene inhibitor, which is bled
gradually to the final effluent. Characteristics of this stream are
high COD, pH, alkalinity, and color.
The plant utility wastewaters enter the storm sewer system. The boiler
blowdown has a low flow rate but high total dissolved solids. Demineral-
Jzer regeneration wastes are both acidic and alkaline and may potentially
produce pH peaks. The cooling tower blowdown is high in total dissolved
solids but, because the corrosion inhibitors used are chromium and
zinc free, these heavy metals do not appear in the blowdown. The vacuum
pump seal water is currently discharged on a once-through basis to the
storm sewer system. This water picks up small quantities of organic
compounds but has only a moderate COD concentration. Studies are being
made to recycle the bulk of the seal water and discharge the blowdown
only to the treatment facility.
VI1-29
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DRAFT
The plant's treatment facility consists of chemical coagulation and
clarification followed by activated sludge secondary treatment. The
final effluent after secondary treatment is discharged to a municipal
treatment plant. All the latex plant process wastewaters are discharged
to two coagulation pits. They operate so that one pit is being filled
with wastewater, while water in the second pit is being treated, settled,
and emptied. The pH of the wastewater is first adjusted with lime
and then treated with ferrous sulphate, a polyelectrolyte, and limestone.
The latex solids coagulate around the limestone which serves to sink
the solids. The settled solids are removed from the pits periodically
when the solids depth becomes excessive. The clarified wastewater enters
four aeration basins operated in parallel. The basins are equipped with
four 15-horsepower aerators. The aeration basin effluent enters a
secondary clarifler and overflows to a sump from which it is pumped
to the city treatment plant. The clarifier underflow is sent to^a
sludge thickener, while the supernatant is returned to the aeration
basins. The biological sludge in the thickener Is periodically removed
and landfilled. The coagulation pit solids and the thickened biological
solids are not suitable for satisfactory landfill because of their high
water content. Studies are currently underway to determine adequate^
techniques for dewatering and disposing these sludges. The coagulation
pits provide good quality primary effluent. The COD and BOD of this
effluent are high, however. The secondary treatment plant produces a
final effluent having a COD and BOD of approximately 600 and 50 mg/L
respectively. The high COD:BOD ratio indicates high biological resistance
of the wastewater constituents from this latex plant. Although the BOD
level (50 mg/L) would not be suitable for direct discharge, it is very
amenable to acceptable discharge to secondary treatment plants.
Plant Q.
This plant is responsible for the manufacture of styrene-butadiene
latexes. The annual production rate is approximately 21,000 metric
tons. The plant commenced production in 1952 and is located in an
urban area with limited room for expansion. The plant also has a
research facility and a pilot plant.
The styrene-butadiene family of latexes produced at the plant can be
classified by three groups: styrene-butadiene latex, styrene-butadiene
carboxylated latex, and styrene-butadiene-vinyl pyridine latex. All
these latexes are produced by similar processing techniques and equip-
ment. The monomers used (styrene, butadiene, organic acids, and vinyl
pyridine) are shipped to the plant by tank car and tank truck. The
latexes produced are used for tire fabric coating, backing material,
and paper coatings.
VI1-30
-------
DRAFT
The plant uses city water for process water, boiler makeup water, and
cooling tower makeup. The boiler makeup is softened before injection.
The cooling tower makeup is treated with a dispersant, corrosion inhibitor,
and slimicide. The process water, used for solution preparation, is
deionized before use.
The principal process wastewaters generated in the plant originate from
equipment cleanout, area washdown, and stripper condensates. Excess
monomers are not recovered. Reactors, strippers and storage tanks are
periodically cleaned of rubber build-up by hand and then rinsed with
water. Generally, large quantities of water are used for each cleanout.
The latex filters are frequently cleaned. This involves first removing
the trapped rubber solids and flushing the filter with water. The
rinse waters contain suspended solids, COD, and uncoagulated latex.
Floors and loading-unloading areas are flushed with water. These waste-
waters contain COD, suspended solids, and uncoagulated latex. The
vapors from steam stripping operations are condensed and discharge into
a receiver. The receiver waters which overflow to the plant sewers
have a high organic loading with correspondingly high COD and oil
levels. The seal water for the vacuum pump serving the vacuum stripping
equipment is slightly contaminated with organics, and presently discharges
on a once-through basis. Studies are being made to collect individual
seal water discharges and recycle the bulk of them with a controlled
blowdown of contaminated water. This will reduce the total volume in
the plant's final effluent.
The regeneration waste from the boiler water makeup softener is a
concentrated salt solution and therefore contributes high total dissolved
solids to the effluent. The process water deionizer is regenerated with
sulphuric acid and caustic soda. The discharge of these solutions will
produce both acid and alkali peaks in the effluent, although there is
generally an excess of sulphuric acid in the daily regeneration discharges.
The boiler and cooling tower blowdowns contribute high total dissolved
solids and moderate COD to the plant's final effluent.
The treatment of the plant's wastewaters includes equalization, chemical
coagulation and settling, and secondary treatment in the local munici-
pality's treatment plant. The wastewaters are first pumped from the
plant effluent trench into an equalization basin, which provides
approximately 2k hours detention and is aerated with two aerators. The
pH of the equalized wastewater is adjusted from normally alkaline by
addition of sulfuric acid to the neutralization sump. The wastewaters
are pumped from the sump to a reactor-clarifier where alum, coagulant,
and polyelectrolyte are added in the mixing chamber. The latex and
fine rubber particles are coagulated and collected as a sludge from the
bottom of the clarifier. The clarified effluent overflows the clarifier
to the city's sanitary sewer for secondary treatment. The clarified
sludge is sent to a thickener .and finally to a sludge holding tank, and
is then loaded into a tank truck for disposal. The supernatant from
the thickener is returned to the reactor-clarifier. The treatment
VI1-31
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DRAFT
system described above produces a good quality primary effluent. COD
and BOD are reduced by approximately 70 and 50 percent, respectively.
The suspended solids and oil are decreased by 80 and 50 percent each.
Summary of Control and Treatment Technology
In-plant control technology covers segregation and measures for handling,
reuse, modification of processing, and disposal of various types of
wastewaters, including spills and leakage, washdowns, control of runoffs,
and housekeeping practices. End-of-pipe treatment technology covers
the treatment of various combinations of process and non-process waste-
waters. Separate discussions are presented for the Tire and Inner Tube
and the Synthetic Rubber segments of the industry.
Tires and Inner Tubes
In-Plant Control
In-plant measures included the proper handling of soapstone, of the
latex dip, and of discharges from air pollution equipment.
Soapstone
Soapstone is a slurry normally consisting of clay, an emulsifying agent,
and water. According to one plant representative, soapstone, if
continually discharged, will contribute a high solids and BOD loading
to the process wastewaters. The standard method of eliminating a continuous
discharge of large quantities of soapstone is the use of a closed-loop
recirculation system. Such a system needs periodic cleaning, usually
on a weekly basis. This cleaning operation can, but does not necessarily,
lead to a discharge. Prior to cleaning, the soapstone solution in the
system is generally transferred to storage tanks. The alternative to
recirculation is to discharge the solution directly into the process
sewers. Both practices were observed during the field survey, the first
being the better from a wastewater control standpoint. Soapstone wash-
water is potential discharge which is commonly sent to end-of-pipe
treatment. However, it was observed that this washwater could be stored
and used as makeup for the soapstone solutions for future operations.
Alternative methods for controlling discharges from weekly washdown
include the use of substitute solutions which require the system to be
cleaned on a less frequent basis.
Control of minor discharges of soapstone, such as spills and leakage,
Is achieved by the use of curbing and by blocking off drains in the
dipping area. In addition, drip pans are provided for stock during
the air-drying operation. Soapstone that is spilled into the curbed
VI1-32
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DRAFT
area is periodically vacuumed out and sent to a landfill site. Newer
plants are constructed without drains in this area, thus eliminating
the possibility of soapstone contamination of process wastewaters.
Instead of curbing, steel grates are placed on the floor; these can be
removed when cleaning the area.
Latex Dip
The most common practice of the larger manufacturers is to eliminate
this operation from the tire facility. Fabric is dipped by a centrally
located facility and then shipped to the tire plant. However, in
plants that still dip fabric, the accepted procedure is to seal off
drains in the immediate area, supply the area with curbing, and drum
the waste solutions for disposal at landfill sites. The alternative is
to dump the waste solutions into process sewers which are destined for
end-of-pipe treatment systems. The amount of waste from this operation
is small, less than 230 liters (60 gals) per day. Drumming of the
solution is therefore preferred, since treatment of this stream once
diluted with other streams is difficult.
Air Pollution Control Residues
It is not common for manufacturers to use large quantities of wet
particulate-collection systems. In the compounding area, in particular,
bag-houses, rather than wet scrubbers are used. Wet systems are more
common in the tire-finishing area, where they collect the grindings from
the white sidewall grinding machines, balancing machines, and the
tire-repair area.
Discharges from wet scrubbers contain high loadings of settleable
solids, which must be removed before final discharge. The solids
collected from the tire-finishing area can be settled out in a small
sump. The particulates are large, and with a properly designed separator,
the clarified water can be, and frequently is completely reused.
The discharges from wet scrubbers used in the compounding area are much
finer and require longer settling times. Only one plant visited used
wet scrubbers in this area. This plant used a 2,100 sq. meter (0.52-acre)
lagoon to separate the solids from this discharge. Unless specifically
required to meet air pollution ordinances, wet scrubbers in this area
are not recommended.
Additional air pollution equipment can be found in the tire-painting
areas. Stricter air emission standards and OSHA standards are forcing
tighter control Is on particulate and solvent emissions from this area.
Consequently, the industry is currently attempting to substitute water-
VI1-33
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DRAFT
based paints and sprays for solvent-based materials, but with only
limited success. Wet air pollution equipment in this area was found
at only one plant; there was no wastewater discharge, because all the
scrubber water was reused.
Spills and Leakage
To control oily wastewaters resulting from spills and leakage, the common
practice is to provide curbing and oil sumps and to seal drains. In
older plants, the roller mills are located in basins. The blocking off
of drains in these basins as a control measure is not feasible because
electrical machinery is located in the basins. A broken water pipe
would fill the basin, thus shorting out the machinery. Curbing is used
to keep normal area washdown and periodic leakages and spills from
entering the basin and thus contaminating process waters. In newer
plants, machinery is located on the floor surface. Updated seal designs
prevent the leakage of oil. In many cases, potentially contaminating
areas have no drains, thus eliminating the possibility of oil in these
process wastewaters.
In plants where recirculated water is the primary source for cooling,
the process and non-process sewers are separate. Oil sumps and API
separators can therefore be provided to treat oily process wastewaters.
The separable oil from these devices is removed either periodically by
maintenance people or continuously by a belt filter: the continuous
removal is considered the better practice. During periodic removal of
oil, the agitation supplied will result in a large quantity of oil
being released to the effluent,thus reducing the separator's overall
average removal efficiency.
In plants where the primary source of cooling is once-through water,
process and non-process sewers are combined. Removal of oil must be
accomplished in an end-of-pipe treatment facility. Dilution by non-
process wastewaters directly affects the removal efficiencies of oil
in the end-of-pipe treatment facility.
Washdowns and Machine Cleaning
Common practice for prevention of process-area washdowns from contaminat-
ing wastewaters is the use of dry sweeping equipment. These include
automatic sweepers, brooms, and shovels. Oily spills are cleaned using
solvents and rags, the resulting contaminated material being drummed
and sent to a landfill. Practices employed in non-process areas (such
as the boiler house and storage areas) are similar.
-------
DRAFT
Machines and machinery parts are normally cleaned with solvents or
steam. Spent solvents are drummed and sent to a landfill. The use
of steam requires a special area supplied with curbing and an API
separator to remove separable oil and solids. Discharges of un-
treated oil- and solid-contaminated steam condensate occur and con-
stitute a significant source of process wastewaters. Although steam
cleaning has the disadvantage of having a continued discharge that
must be treated, it eliminates the possibility of a careless operator
discharging large quantities of organic solvents into an untreated
process wastewater stream.
Molds from the curing presses are normally cleaned by sand- or air-
blasting equipment. Tnese are dry, and involve no wastewater problem.
Runoff
Runoff from oil-storage areas occurs due to oil spills, storm water,
and various blowdowns which occur in the storage area. Handling
practices vary within the industry. Minimal control involves the
diking of all oil-storage areas to prevent contamination of waste-
water by large oil spillages which can occur during unloading or due
to leaking tanks. These dikes generally are provided with drainage
ports to prevent normal storm water from filling the diked area.
This allows minor oil spills, attributable to operator negligence,
to contaminate storm runoff. A better system involves the diking
of the storage area, the roofing of storage area to prevent storm
runoff contamination, and use of an oil sump to collect minor spills
and leakage. Collected oil is drummed and sent to a landfill. To
prevent oil from unloading areas from contaminating the wastewaters,
drains are diked and covered with straw filters. This control tech-
nique suffers from the possibility of storm runoff contamination.
Other treatment schemes include the use of separators to treat oil
storage runoff. The primary emphasis here is to treat runoffs due
to continual water running through the area. The systems generally
are not designed to handle increased loads due to storm runoff.
Solvent storage and maintenance areas are normally confined to build-
Ings. To decrease the possibility of contamination due to operator
or maintenance negligence, these areas are not supplied with drains.
End-of-Pipe Treatment
End-of-pipe treatment in this segment of the industry generally in-
volves the treatment of combined process and non-process wastewater
in a primary sedimentation basin or lagoon. Once-through, non-contact
cooling water usually is not treated even though the possibility exists
for oil contamination from process wastewater. Primary emphasis is on
removal of separable solids from the non-process boiler blowdowns and
VI 1-35
-------
DRAFT
water treatment wastes and from the process washdown waters (if any)
from the soapstone area.
The most effective system, although not generally applicable because
of land requirements, is the use of judicious water management tech-
niques to minimize non-process discharges and of holding lagoons to
contain all wastes including process, non-process, and storm runoff.
Other lagooning systems used for treatment of all process (including
once-through cooling water) and non-process wastewaters were observed.
Residence times varied from twelve to twenty-four hours with surface
loadings as high as 12,000 15ters/min/sq meter (1,200 gal/min/sq ft).
Auxiliary equipment observed included oil skimmers and sludge handling
equipment.
From the standpoint of treating process wastewaters, these systems
suffer heavily from dilution, particularly in the treatment of grease
or oily wastes. Dilution by process streams was as high as 75 to 1.
Dilution by heavy storm runoff was an additional problem at many
locat ions.
Synthetic Rubber
In-plant Control
Since the synthetic rubber industry is highly technological, involving
many proprietary and confidential processing techniques, many potential
in-plant wastewater control methods would call for radical changes in
processing or product quality. Such techniques are obviously not
feasible. However, some potential control methods deserve mention so
that the!r applicabi1ity may be evaluated.
Crumb Rinse Overflow
It was observed that some crumb rubber plants generate crumb rinse
overflows which have a lower loading of rubber fines than other plants.
Generally, however, such losses cannot be reduced with finer in-plant
screens since they are a function of both the type and the coagulation
properties of the rubber. One plant did use a proprietary method to
finish the rubber cement in which a water slurry is not used. This
system eliminates the crumb slurry overflow and the contained rubber
fines. It is not necessarily applicable wholesale to crumb rubber
production, but does merit investigation by industry.
Coagulation Liquor Overflow
Most emulsion crumb rubber processes use an acid and brine coagulation
liquor. One plant, however, coagulates the latex with an acid-
polyamine liquor which reduces- the quantity of total dissolved solids
discharged in the coagulation liquor overflow. The use of this type
VII-36
-------
DRAFT
of coagulation liquor is not always possible, but if employer could sig-
nificantly reduce the total dissolved solids in the final effluent.
Vacuum Sys terns
Several plants are converting vacuum systems from steam jet ejectors to
vacuum pumps for efficiency and wastewater reasons. In order to maximize
the wastewater benefits derived from the use of vacuum pumps, the seal
water should be recycled. An overflow is generally required from the
seal water recycle system; this overflow is normally slightly contaminated
with oil but has a better quality than the steam jet condensate.
Caustic Scrubbers
In some plants, the caustic soda solution used to remove inhibitors from
some monomers (notably butadiene) is replaced batchwise. The spent
caustic soda solution, usually 10-20% sodium hydroxide, should not be
discharged batchwise. It should be containerized and bled into the total
plant effluent, thereby diluting its high pH, alkalinity, COD, and color
contribut ions.
Carbon Black Slurries
The usual method is to slurry the carbon black for addition to the rubber
with water. One plant visited employs a steam grinding-slurrying tecn-
nique which reduces carbon black spillage and consequently washdown and
Runoff wastewaters laden with black fines; this technique avoids the need
for carbon black settling pits and the associated pit cleaning costs.
Latex Spi11s
Latex spills and leakages occur from time to time in all emulsion crumb
and^atei plants. In most cases, the spill is washed to the nearest
plant driin using a water hose. In many cases, this produces unnecessary
washdown water and dilutes the latex so that subsequent treatment by
coagulation is much more difficult. An alternative techn.que ,s to
coaqu ate the latex in situ with alum, for example, and remove the
coaguated rubber solids with scrapers. The volume of subsequent wash-
£2 water required is less and the latex solids in the washdown water
are greatly reduced.
Baler Oi 1
-^££si«!SS S1~-
*- ««""» " _ = . r u_i_r 0:i ipakc; and can
VI1-37
-------
DRAFT
installed to keep leaked oil from leaving the baler area. Balers using
water as the hydraulic fluid are also available and are being used in
some plants; oil leakage with this type of machine is obviously elimi-
nated.
End-of-Pipe Treatment
Emulsion Crumb Plants - Primary
It is normal practice for crumb rubber producers to recycle part of the
crumb rinse water. The remainder of the crumb rinse water is discharged
in order to blow down accumulating fine rubber solids and dissolved
solids and organics. The rinse water discharge or overflow is clarified
before final treatment in a crumb separation pit. The trapped rubber
solids are removed periodically by scoop. A very common shortcoming of
these separators is that they are operated as single units and are not
cleaned frequently enough. This results in short-circuiting followed
by poor separation. In addition, when the pits are cleaned, the sepa-
rated rubber solids are disturbed and rubber solids that had previously
separated recombine with the pit effluent until the condition of the pit
stabilizes. Dual pits would solve this problem: one pit would stay in
operation while the other was cleaned and allowed to stabilize.
Since wastewaters from emulsion crumb plants contain considerable quan-
tities of latex, it is necessary to coagulate the latex in order to
achieve a good quality effluent. Chemical coagulation by itself is
seldom sufficient, because the density of the coagulated rubber is
normally close to that of water. Therefore, it is customary to add
a "sinker" (clay or limestone) to the coagulation mixture to sink the
coagulated rubber and effect the separation. For a small wastewater
flow, chemical coagulation using (for example) alum, polyelectrolyte,
and clay in a rapid mix tank can be followed by flocculation in a
flocculator tank. Clarification can then be accomplished in a rectan-
gular clarifier equipped with solids removal equipment. Larger
wastewater flows can be treated in a reactor-clarifier with rim
overflow and central sludge draw-off.
The collected sludge can be thickened and dewatered before disposal
in a landfill. Dewatering studies on this type of sludge concluded
that a plate-and-frame pressure filter performed well. The installed
filter was automatically controlled for feed shut-off, silter opening,
core blowout, filter closing, precoating, and feed restoration (refer
to Plant J).
One plant (Plant K) uses chemical coagulation followed by air flotation
for primary clarification (6). Instead of sinking, the rubber solids
are floated to the clarifier surface with air bubbles and removed by
surface solids removal equipment. This treatment facility is rela-
tively new and has had start-up troubles, although they have been
satisfactorily resolved. Air flotation in this application produces
primary effluent of good quality.
VI1-38
-------
DRAFT
The collected surface solids are pumped to a sludge impoundment lagoon
where they dry out. The use of this lagoon is limited and a long-term
solids dewatering and disposal technique will have to be found.
Where adequate land is available, rubber solids separation has been
achieved using primary settling ponds. Chemical coagulation of the
solids prior to discharge to the ponds is usually necessary. The
settled and floating solids (since both types are produced) are re-
moved from the ponds periodically by vacuum truck or scoop.
Emulsion Crumb Plants - Secondary
Biological oxidation of the primary effluent is achieved in aerated
lagoons or in activated sludge plants. Generally, a nutrient must be
added. Both technologies obtain satisfactory oxidation of the dis-
solved contaminants; problems can arise in the clarification of the
secondary effluent. Good secondary clarification of effluent from an
aerated lagoon has been obtained with the aforementioned air flotation
plant, which is a dual system with both primary and secondary air flota-
tion clarifiers.
If sufficient land is available, the effluent from the aerated lagoons
can be clarified and stabilized in stabilization ponds. This type of
facility is temperature dependent, of course, and performs better in
warmer climates.
Clarifiers are commonly used for secondary clarification in activated
sludge plants. They are generally adequate, but cases exist where
high solids carryover is a problem. Secondary clarification can be
assisted with coagulation chemicals in much the same manner as for
primary clarification, but the additional chemical cost is high.
One plant in the industry, in an area where water is in short supply,
is evaluating evaporation to remove wastewater contaminants (7).
Problems encountered have included severe scaling problems and high
operating costs. The scaling problems stem from the fact that the
scale-producing characteristics of the wastewater vary greatly on a
day-to-day basis, and are greatly affected by the inherent opera-
tional variations in the rubber plant.
Emulsion Crumb Plants - Advanced
After secondary treatment, emulsion crumb wastewaters still contain
high levels of COD. A high COD level appears to be a common charac-
teristic of secondary effluents from emulsion crumb, solution crumb,
and latex plants, and appears to indicate that certain constituents
of the wastewaters generated in synthetic rubber plants are refractory
to biological oxidation.
VI 1-39
-------
DRAFT
Solution Crumb Plants - Primary
Primary clarification of the solution crumb plant wastewater is carried
out in crumb pits. These pits are similar in design to thoss for emul-
sion crumb production facilities. To avoid re-suspending the separated
rubber solids, dual crumb pits should be used.
Other forms of primary treatment are not required for solution crumb
wastewaters, since uncoagulated latex is not present and the fine
rubber solids separate readily.
Solution Crumb Plants - Secondary
Secondary treatment technology uses both activated sludge and aerated
lagoon systems. Good BOD removals are achieved, but poor secondary
clarification is a problem in most cases. The reasons for this are
not certain. A high level of COD remains after biological treatment,
indicating that much of the wastewater constituents are biologically
refractory.
Solution Crumb Plants - Advanced
Advanced or tertiary treatment technologies have not been used on
secondary effluents from solution crumb plants. It is very probable
that activated carbon treatment would give COD removals similar to
those for emulsion crumb wastewater, since the raw wastewater con-
stituents (for example, traces of monomer) are similar for both types
of wastewater.
Latex Plants - Primary
Since latex plant wastewaters contain uncoagulated latex solids,
primary clarification is with chemical coagulation and sinking.
In much the same manner as for emulsion crumb wastewaters, clarifica-
tion can be effected in reactor-clarifiers or systems with separate
rapid mix, flocculation, and clarification tanks. Latex wastewaters
can also be clarified by air flotation.
Latex Plants - Secondary
Activated sludge plants are used for the secondary treatment of latex
wastewater. High residual COD levels are a problem. These levels are
higher than for either emulsion crumb or solution crumb plants, because
the COD loading of the raw wastewater from latex plants is much higher.
It is feasible that aerated lagoons and stabilization ponds will produce
satisfactory oxidation and stabilization of latex wastewaters.
VI1-
-------
DRAFT
Latex Plants - Advanced
Advanced or tertiary treatment technologies have not been used on latex
wastewaters. It is probable that COD removals similar to those achieved
by emulsion plants could be achieved for latex wastewater by using
activated carbon columns.
VII-
-------
DRAFT
SECTION VI I I
COST, ENERGY AND NON-WATER QUALITY ASPECTS
Tire and Inner Tube Industry
Selection of Control and Treatment Technologies
Based on Costs
Two alternative approaches exist for the control and treatment of
process wastewaters from both old and new tire and inner tube pro-
duction plants.
The first approach is to combine process and non-process wastewaters and
to treat the entire plant effluent. Where land is available, end-of-
pipe treatment is the approach favored by many of the tire manufacturers,
Generally, the reasons supporting this approach are as follows:
1. In older plants, in-plant sewers for process and non-process
wastewaters are usually combined, thus making combined
treatment more attractive.
2. Process flows are usually small relative to non-process flows.
3. The treatment of non-process wastewaters has received the
bulk of industry's attention. High suspended solid loadings
in blowdown and water treatment wastes are the major pollutant
in the combined plant effluent from tire facilities.
However, end-of-pipe treatment systems also have several disadvantages:
1. The combined effluent treatment system usually requires one
or two lagoons for settlement and retention. Lagooning of
the wastes requires large land area, which is not readily
available at many plant locations.
2. Because of dilution, the effectiveness of treatment for oil
removal from process wastewater is reduced. In several of
the systems observed, oil passed through untreated (although
it was present in significant quantities), because its concen-
tration was below the capabilities of the treatment system
emp1oyed.
The second approach employed is control and treatment of a segregated
and undiluted process wastewater. This approach has been followed
in plants having partially or wholly segregated process and non-
process sewers. This would, of course, include any plant using recir-
culated cooling water. The main advantages for this treatment scheme
over combined end-of-pipe treatment are:
VI11-1
-------
DRAFT
1. Higher pollutant removal rates.
2. Smaller land area required for treatment facilities.
The primary disadvantage of a segregated system approach is that
separate process and non-process sewers are required.
Upon examining these alternatives, control and treatment of segregated
process wastewaters was considered to be most applicable to the
tire producing industry. End-of-pipe treatment of combined wastewaters
is not feasible for pollution control because of: 1) the ineffectiveness
of such systems in removal of process wastewater contaminants; and
2) the large land requirements. All costs, therefore, are related to the
treatment of a segregated process waste stream.
With proper in-plant control, the process streams consist of readily
separable lubricating and extender oils and settleable solids.
Volumetric flow rates for process wastewaters are small. Therefore,
the initial treatment applicable from a cost and proven operation basis
Is an API-type gravity separator. The performance and efficiency
of a gravity separator can be improved by addition of an absorbent
filter.
Effluent quality data for old tire and inner tube and for new tire
facilities are presented (along with cost data) in Tables Vlli-1 and
VII I-2. The treatment technology involves the isolation of wastes
with curbing, the protection of oily areas to prevent storm runoff
contamination, and the separation of settleable solid and oily material
from the wastewater.
A more detailed description of recommended facilities is presented in
the tire and inner tube portion of Section IX, and a flow diagram of
the system used as a basis for costing is presented in Figure IX-1.
Treatment Cost Data
Data from Corps of Engineers permit applications and plant data^obtained
during inspection visits were used to obtain the average or typical
plant size and wastewater discharge flows, and raw waste loadings
as described in Section V.
From these data, a typical process wastewater flow was estimated to
be 3.785 liters/sec (60 gal/min) for a plant consuming 205,000 kg
(450,000 Ibs) of raw materials per day. For the old tire and inner
tube plant sub-category the average oil loading is 0.2^6 kg/1,000^
kg of raw material consumed. The suspended solids load.ng for^th.s
sub-category is estimated to be 0.319 kg/1,000 kg of raw material.
Vlll-2
-------
TABLE VIII - 1
Old Tire and Inner Tube Production Facility Subcategory
Estimated Wastewater Treatment Costs for Different Degrees of Treatment
based on a Typical Raw Material Consumption of 205 metric tons/day
Investment
Annual Costs
Capital Costs
Deprec iation
Operating and Maintenance Costs
(excluding energy and power costs)
Energy and Power Costs
2
Total Annual Costs
Parameters
O^ kg raw material)
Suspended Sol ids
0 i 1 and Grease
Treatment or Control Technology
1
ists
• costs)
Raw
Waste Loads
0.319
0.120
_A_
$299,000
$ 30,000
60,000
24,000
1,000
$115,000
A
0.064
0.048
B
$328,000
$ 33,000
66,000
27,000
1,000
$127,000
Effluent Oual ity
B
.064
.008
Technology A is Isolation of Wastewaters followed by API Gravity Separator
Technology B is Technology A followed by an Absorbent Filter
2
August 1971 Dollars
73
T|
-i
-------
TABLE VI I I - 2
New Tire Production Facility Subcateqory
Estimated Wastewater Treatment Costs for Different Degrees of Treatment
based on a Typical Raw Material Consumption of 205 metric tons/day
Investment
Annual Costs
Capital Costs
Depreciation
Operating and Maintenance Costs
'excluding energy and power costs)
Energy and Power Costs
< 2
— Total Annual Costs
i
-P-
Treatment or Control Technology
__
$276,000
$ 28,000
55,000
22,000
1,000
$106,000
JL
$305,000
$ 31,000
61,000
25,000
1.000
$118,000
Parameters
(kg/10^ kg raw materfal)
Suspended Sol ids
Oi 1 and Grease
Raw
Effluent Ouality
Waste Loads
0.319
0.083
A
0.064
0.048
B
0.064
0.008
Technology A is Isolation of Wastewaters followed by API Gravity Separator
Technology B is Technology A followed by an Absorbent Filter
>
August 1971 Dollars
o
73
•
-------
DRAFT
Based on these typical profiles for old and new production facilities,
treatment cost data were generated and are presented in Tables VII 1-1
and Vlll-2. Costs typically are higher for older production facilities,
primarily due to the fact that a new in-plant process sewer system
would be needed. Separation of the present combined system was
considered unrealistic for older production plants.
Investment costs have been factored to August 1971 dollars using Engin-
eering News Record cost indices. Depreciation was calculated on the
basis of straight-line depreciation with a five year life and zero
salvage value.
Designs for the proposed model treatment systems were costed out in
order to aid EPA in its efforts to evaluate the economic impact of
the proposed effluent limitations. The design considerations (i.e.,
the influent raw waste loads) were selected to represent the expected
raw waste load within each sub-category. This results in the generation
of cost data which should be conservative when applied to most of the
plants in this category. Relatively conservative cost figures are
preferred for this type of general economic analysis.
The capital costs were generated on a unit process basis, with the
following "percent add on" figures applied to the total unit process
costs in order to develop the total installed capital cost requireme
requirements.
Percent of Unit
..
I tern
Electrical 12
Piping 1j>
Instrumentation °
Site work '
Engineering Design and Con-
struction Supervision Fees 10
Construction Contingency 15
Since land costs vary appreciably between plant locations, it was
decided to exclude land cost from the total capital cost estimates
Land costs must be added on an individual case basis.
Annual costs were computed using the following cost basis:
VIII-5
-------
DRAFT
ltem Cost Allocation
Capitalization 10 percent of investment
Depreciation 5-yr straight line with zero salvage value
Operations and Includes labor and supervision, chemicals,
Maintenance sludge hauling and disposal, insurance and
taxes (computed at 2 percent of the capital
cost), and maintenance (k percent of capital cost)
Power Based on $0.01 kw-hr for electrical power.
The short-term capitalization and depreciation write-off period is
what is currently acceptable under current Internal Revenue Service
Regulations pertaining to pollution control equipment.
All costs were computed in terms of August, 1971 dollars, which corres-
pond to an Engineering News Record Index (ENR) value of 1580.
Energy Requirements
Energy input is related to the need for electric pumps to pump process
wastewaters from the plant area and through the treatment system.
Electricity costs are estimated at one cent per kilowatt hour. The
extra power required for treatment and control systems is negligible
compared to the power requirement of the tire manufacturing equipment.
Non-Water Quality Aspects
The primary non-water quality aspect deriving from use of a separator
is the need for disposal of oil and solids. Additional solid waste
results from the use of a non-regenerative type absorbent filter.
Solid waste disposal is a major problem confronting the industry as
a whole. Typically, 3,100 kg (6,800 Ibs) of solid waste are generated
by a tire plant each day. Additional solid waste results from the drum-
ming of the waste solutions for off-site disposal. Many manufacturing
plants, particularly in the northern states, are finding it difficult
to locate and arrange for service at satisfactory landfill sites.
Fortunately, the additional solid waste generated by the proposed
treatment technology is very small relative to the normal solid waste
generated by the production facility; consequently, the impact will
not be significant.
Land requirements for the treatment system are small; nevertheless,
certain older facilities located in highly congested urban areas will
find it difficult to allocate space for even this minimal treatment
facility. These plants may be forced to turn to other control measures
and/or to pre-treat for disposal and discharge of the process wastewaters
.to publicslly owned treatment works.
VI I I-6
-------
DRAFT
Synthetic Rubber Industry
Emulsion Crumb Sub-category
Selection of Control and Treatment Technologies
Four degrees of control and treatment were considered in weighing
treatment effectiveness versus cost of treatment: primary clarifica-
tion; biological oxidation; and advanced treatment to two levels
of COD removal.
Since emulsion crumb wastewaters contain uncoagulated latex solids,
it is necessary to coagulate these solids prior to clarification. The
cost alternatives for the primary clarification of emulsion crumb
wastewater have been developed on the basis of a treatment model invol-
ving chemical coagulation, with a sinking material such as clay to sink
the coagulate.d solids. This, however, is only one of several possible
methods of achieving primary clarification. Air flotation is another
approach to primary clarification which has been applied to emulsion
crumb wastewaters with success. Chemical coagulation has been used to
develop the cost data because there are more cases of its successful
application for this type of wastewater, and, therefore, there is less
uncertainty about the effectiveness of this technology for this sub-
category.
After primary clarification, emulsion crumb rubber wastewaters in-
variably have high BOD and COD concentrations. Biological treatment
is necessary (and is commonly practiced by the industry) to remove
these contaminants. In order to develop the cost alternatives for
biological treatment, activated sludge processes were used as a
model treatment. It is, of course, only one method for obtaining
biological oxidation, since other comparable technologies, such as
aerated lagoons and stabilization ponds exist and are used to some
extent by the industry. The activated sludge process was chosen
as a model treatment because its performance is not as temperature-
and climate-dependent as is an aerated lagoon or stabilization pond
system and because the resulting cost data are independent of geo-
graphic location. In addition, an aerated lagoon or stabilization
pond system requires considerably larger areas, which are not always
available. Activated sludge facilities, by contrast, require minimal
land.
The major pollutant remaining in emulsion crumb wastewaters after bio-
logical treatment is COD. Its concentration is much higher than the
other principal parameters and if advanced wastewater treatment is to be
carried out, it is logical that the treatment technology should be
applied to reduction of the high COD levels. For the wastewater flow
rates involved in emulsion crumb rubber production, activated carbon
VIII-7
-------
DRAFT
treatment is the only technology applicable for COD removal. In order
to prevent blinding of the carbon beds and columns with fine suspended
solids, a dual-media filtration system is required upstream of the
columns. Activated carbon adsorption of emulsion crumb secondary
effluent has been studied in pilot-scale test equipment. However,
because of the technical risk with respect to performance and the
uncertainty of the associated capital and operating costs, two levels
of activated carbon treatment have been modeled. These two levels are
equivalent to overall COD reductions of 75 and 90 percent.
Basis of the Treatment Cost Data
An emulsion crumb industry profile was made, based on industry produc-
tion capacity data, to determine the typical size of an emulsion
crumb production facility. The average, or typical, plant is rated
at 128,000 metric tons per year. The wastewater flow for such a plant
would approximate 66 liters/second (1,050 gallons per minute). The
model treatment plant, using chemical coagulation and clarification
followed by activated sludge biological treatment, is shown in Figure
IX-2. The degree of treatment afforded by this technology is equi-
valent to Level I Control and Treatment. The recommended treatment
technology to attain Level II control and treatment is presented in
Figure X-1. This treatment technology includes dual-media filtration
followed by activated carbon adsorption.
Designs for the proposed model treatment systems were costed out in
order to aid EPA in its efforts to evaluate the economic impact of
the proposed effluent limitations. The design considerations (i.e.
the influent raw waste loads) were selected to represent the highest
expected raw waste load. This results in the generation of cost
data which should be conservative when applied to most of the plants
In the emulsion crumb sub-category. Relatively conservative cost
figures are preferred for this type of general economic analysis.
The capital costs were generated on a unit process basis, with the
following "percent add on" figures applied to the total unit process
costs in order to develop the total installed capital cost requirements,
Percent of Unit
I tern Process Capital Cost
Electrical 12
Piping 15
Instrumentation 8
Site Work 3
Engineering Design and Con-
struction Supervision Fees 10
Construction Contingency 15
VII I-8
-------
DRAFT
Since land costs vary appreciably between plant locations, it was decided
to exclude land cost from the total capital cost estimates. Land
costs must be added on an individual case basis.
Annual costs were computed using the following cost basis:
I tern Cost Allocation
Capitalization 10 percent of investment
Depreciation 5-yr straight line with zero salvage value
Operations and Includes labor and supervision, chemicals,
Maintenance sludge hauling and disposal, insurance and
taxes (computed at 2 percent of the capital
costs), and maintenance (computed at k per-
cent of the capital cost).
Power Based on $0.01/kw-hr for electrical power.
The short-term capitalization and depreciation write-off period is
what is currently acceptable under current Internal Revenue Service
Regulations pertaining to industrial pollution control equipment.
All costs were computed in terms of August, 1971 dollars which corres-
pond to an Engineering News Record Index (ENR) value of 1580.
The total capital and annual costs for the model treatment techno-
logies are presented for a typical emulsion crumb plant in Table VIII-3,
together with raw waste load and treated effluent quality.
Energy Requirements
The primary clarification and biological oxidation treatment tech-
nologies require electrical energy only for operation of equipment such
as pumps and aerators. The filtration and activated carbon treat-
ment system, in addition to power requirements, needs a fuel source
to regenerate the carbon. The energy and power needs of the recommended
treatment technologies are deemed to be modest.
Non-Water Quality Aspects
Sludge cake is produced by vacuum filtration of the primary coagulation
solids and the digested biological solids. Sludge disposal costs were
based on sanitary landfill. Sludge incineration costs were not eval-
uated because the economics depend, to a large degree, on the accessi-
bility of a landfill site and on the relative costs for sludge haulage
and site disposal. The annual quantities of solid waste generated are:
VII1-9
-------
TABLE V I I I - 3
Emulsion Crumb Rubber Subcategory
i
o
Investment
Annual Costs
Capital Costs
Deprec iat ion
Operating and Maintenance Costs
(excluding energy and power costs)
Energy and Power Costs
2
Total Annual Costs
Parameters
(kg/10-3 kg product
COD
BOD
Suspended Solids
0 i 1 and Grease
Raw
Wastewater
ter Treatment Costs for Different Degrees of Treatment
cal Production Capacity of 128,000 metric tons/year
$1
$
$
A
,180,000
118,000
236,000
1^7,000
10,000
511,000
A
12.80
2.00
1.2S
0.32
Treatment or Control
t! (Level 1)
$2,002,000
$ 200,000
400,000
230,000
20,000
$ 850,000
Effluent <"ual ity
B (Level 1)
8.00
0.40
0.65
0. IS
Technoloq ies
C
$2,907,000
$ 291,000
581,000
349,000
25,000
$1,246,000
C
5.04
0.08
0.08
0.03
D aevel 1 1)
$2,993,000
$ 299,000
599,000
396,000
29,000
$1,323,000
D (Level 1 1)
2.08
0.08
0.16
0.08
20.00
2.13
7.20
1 .40
Flow (L/10 kg production) 16,600
Technology A is Chemical Coagulation followed by Clarification.
Technology B is Technology A followed by Activated Sludge Secondary Treatment
Technology C is Technology B followed by Dual Media Filtration plus Activated Carbon Treatment to produce 75% overall
COD reduction.
Technology D is Technology U followed by Dual Media Filtration plus Activated Carbon Treatment to produce 90% overall
COD reduction.
2August 1971 Dollars.
o
73
•
-------
DRAFT
Primary coagulated solids 2,9^0 cu. meters (3,900 cu. yds)
Biological solids 2^5 cu. meters (325 cu. yds)
Solution Crumb Sub-category
Selection of Control and Treatment Technologies
Only two degrees of control and treatment have been considered in the
evaluation of treatment effectiveness versus cost data. Since latex
solids are not contained in wastewaters from solution crumb plants,
clarification with chemical coagulation is not required; clarifi-
cation in crumb pits is sufficient. In addition, after biological
treatment, the residual COD concentration is much lower than is the
case in the emulsion crumb couterpart. Consequently, carbon adsorption
to only one level of overall COD reduction (65 percent removal) is
reasonable. COD reductions greater than this would involve additional
risk and uncertainty in the costing processes.
The first degree of treatment proposed includes primary clarification
of crumb-laden wastewater in dual-unit crumb pits, followed by bio-
logical treatment to remove soluble organics. The cost data have
been developed on the basis of an activated sludge system for the same
reasons as given previously for the emulsion crumb sub-category.
Depending on land availability, biological treatment could be aerated
lagoons and stabilization ponds. The second degree of treatment
consists of dual-media filtration followed by activated carbon, adsorp-
tion. Carbon adsorption was selected because it is the most feasible
technique for reducing the soluble COD content.
Basis of the Treatment Cost Data
A profile of the solution crumb rubber industry defined the typical
size of a solution crumb production facility as 30,000 metric tons
per year. The wastewater flow for such a plant would approximate
15.75 liters/second (250 gallons per minute).
The model treatment plant using activated sludge biological treat-
ment is shown in Figure IX-2. The treatment given by the proposed
system is equivalent to Level I Control and Treatment.
The recommended treatment technology to attain Level II Control and
Treatment, presented in Figure X-1, consists of dual-media filtration
followed by activated carbon adsorption.
The influent raw waste loads upon which the treatment system designs
were based were selected to represent the highest expected raw waste
load in this sub-category. The same cost criteria used for emulsion
crumb plants were applied for solution crumb rubber facilities.
VIII-11
-------
DRAFT
The total capital and annual costs for the model treatment techniques
for a typical solution crumb plant are presented in Table VI I 1-4,
together with the raw waste loads and treated effluent qualities.
Energy Requirements
The only energy or power need is electricity, and electricity consump-
tion is moderate. The carbon is not regenerated on-site because of
the unfavorable economics of small-scale carbon regeneration systems.
Non-Water Quality Aspects
Solid waste generation with this treatment system is associated with
biological solids and spent activated carbon. The activated carbon
canisters may be returned for regeneration off-site by the supplier.
However, annual operating data have been based on disposal of the
spent carbon at a landfill site. The annual quantities of solid waste
generated are:
Biological solids 102 cu. meters (135 cu. yds)
Spent carbon 1*fO cu. meters (185 cu. yds)
Air quality and noise levels will not be significantly affected by
the operations proposed in these treatment systems.
Latex Sub-category
Selection of Control and Treatment Technologies
Four degrees of control and treatment were considered in weighing the
treatment effectiveness versus cost of treatment. These degrees of
treatment are the same as for emulsion crumb wastewater and include
primary clarification, biological oxidation, and advanced treatment
to two levels of COD removal.
Latex rubber wastewaters contain uncoagulated latex solids and the
proposed primary treatment (chemical coagulation and clarification)
is similar to that recommended for emulsion crumb wastewaters. The
biological treatment cost data have been based on activated sludge
for the same reasons as were cited for the emulsion crumb sub-category.
The advanced treatment cost data were modeled on two levels of overall
COD reduction, 8? and 95 percent. Overall removals greater than 95
percent would call for undue technical risk, and uncertainty about
capital and operating costs.
VII 1-12
-------
TABLE VI I 1-4
Solution Crumb Rubber Subcateqory
Estimated Wastewater Treatment Costs for Different Degrees of Treatment
based on a Typical Production Capacity of 30,000 metric tons/year
Treatment or Control Technologies
Investment
Annual Costs
Capital Costs
Deprec iat ion
Operating and Maintenance Costs
(excluding energy and power costs)
Energy and Power Costs
2
Total Annual Costs
Parameters
(kg/10-3 kg production)
COD
BOD
Suspended Sol ids
Oi 1 and Grease
1
>sts
• costs)
Raw
Wastewaters
6.00
0.80
2.20
0.25
_£L
$810,000
$ 81,000
162,000
68,000
4,000
$315,000
A (Level
3.9^
0.40
0.65
0.16
B_(Level ||
$1,182,000
$ 182,000
236,000
1^5,000
6,000
$ 569,000
Effluent Dual ity
1) B (Level 1 I)
2.08
0.08
0.16
0.08
1
Technology A is Primary Clarification of Crumb Rinse Wastewaters followed by Activated Sludge Secondary
Treatment.
Technology B is Technology A followed by Dual Media Filtration plus Activated Carbon Treatment to pro-
duce 65% overall COD reduction.
I
"August 1971 Dollars.
-------
DRAFT
Basis of the Treatment Cost Data
A latex rubber industry profile was made to determine the typical size
of a latex rubber production facility. The average, or typical, plant
has an annual capacity of 10,000 metric tons, and its wastewater flow
approximates k.k liters/second (70 gallons per minute).
The model treatment plant, consisting of chemical coagulation and
clarification followed by activated sludge biological treatment, is
illustrated in Figure IX-2. This is equivalent to Level I Control and
Treatment.
The recommended treatment technology to achieve Level II Control and
Treatment technology, presented in Figure X-1, includes dual-media
filtration followed by activated carbon adsorption.
The treatment designs upon which the cost data are based correspond
to the highest expected raw waste load within each category.
The same cost criteria used for the emulsion crumb sub-category
were applied to latex rubber. See Table VI I 1-5.
Energy Requirements
Since on-site carbon regeneration is not proposed for economic reasons,
the only power or energy requirement of these treatment systems is
electric power for pumps and other motive equipment.
Non-Water Quality Aspects
Solid wastes are produced by chemical coagulation and clarification,
wasted biological sludge, and spent activated carbon. For cost purposes,
it is proposed that these all be hauled to a landfill. The annual
quantities of solid wastes are listed below:
Primary coagulated solids 21*t cu. meters (283 cu. yards)
Biological solids 62 cu. meters (82 cu.yards)
Spent carbon 126 cu. meters (167 cu. yards)
Neither air quality nor noise levels will be adversely affected by
the proposed treatment technologies.
-------
TABLE VI11-5
Latex Rubber Subcateqory
Investment
Annual Costs
Capital Costs
Depreciat ion
Operating and Maintenance Costs
'excluding energy and costs)
Energy and Power Costs
2
Total Annual Costs
Parameters
(kg/10^ kg production)
COD
BOD
Suspended Sol ids
0i 1 and Crease
Raw
Wastewater
33.52
5.61
5.63
0.70
ater Treatment Costs for Different Degrees of Treatment
ypical Production Capacity of 10,000 metric tons/yr.
Treatment or Control Technologies
A
$361,000
$ 36,000
72,000
33,000
1 ,000
$142,000
.,-/,•—
14.75
4.77
0.93
0.34
J_ (Level 1)
$637,000
$ 64,000
127,000
57,000
3,000
$251 ,000
Effluent Cual ity
_B_ (Level 1)
6.35
0.34
0.55
0.14
JL
$784,000
$ 78,000
157,000
100,000
3,000
$33^,000
V
4.31
0.07
0.07
0.07
JL (Level II)
$784,000
$ 78,000
157,000
117,000
3,000
$355.000
JL (Level II)
1.78
0.07
0.14
0.07
Technology A is Chemical Coagulation followed by Clarification.
Technology B is Technology A followed by Activated Sludge Secondary Treatment.
Technology C is Technology B followed by Dual Media Filtration plus Activated Carbon Treatment to produce 37% overall
COD reduction.
Technology D is Technology B followed by Dual Media Filtration plus Activated Carbon Treatment to produce 95% overall
COD reduction. g
2 >
August 1971 Dollars. Z{
-------
DRAFT
SECTION IX
BEST PRACTICABLE CONTROL TECHNOLOGY
CURRENTLY AVAILABLE — EFFLUENT LIMITATIONS
Tire and Inner Tube Facilities
Identification of Best Practicable Control Technology
Currently Available
The best control and treatment technologies currently in use emphasize
in-house control of solution wastes with end-of-pipe treatment of com-
bined process and non-process wastewaters. However, as discussed
previously, end-of-pipe treatment of process wastewaters after combi-
nation with non-process wastewaters is considered ineffective.
Of the exemplary plants visited, only one plant performs a totally
adequate end-of-pipe treatment of all process wastewater streams.
The treatment facility involves the use of holding lagoons for com-
bined process and non-process effluents and the re-use of the
wastewater for irrigation of farm land. The very large land re-
quirements involved keep this type of treatment from being applied
to the industry as a whole. Other end-of-pipe treatment facilities
examined were not very effective in removal of the oil constituent
in the wastes, due to dilution by non-process wastewaters.
There are many in-plant control and treatment facilities. Recircula-
tion of the soapstone solution was considered adequate and effective.
However, the weekly washing and dumping of the system in most plants
reduced this effectiveness. Oil sumps and separators are common to
the tire industry, but their effectiveness is reduced by dilution
with other wastes or by improper maintenance.
Since process wastes are best treated before dilution with non-process
wastewaters and because no plant obtained effective control and treat-
ment for all the wastewaters it generated, the proposed Level 1
treatment technology for a typical plant is_a combination of the best
features of various plants examined and visited.
Since only the loadings vary between the Old Tire and Inner Tube
Production Facilities sub-category and the New Tire Production
Facilities sub-category, the treatment schemes described below
will be the same for both.
Basically, the technology employed consists of:
1 Elimination of any discharge of soapstone or latex-dip solution.
2. Segregation, control, and treatment of all oily waste streams.
NOTICE- THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
TTTHTS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECE.VED-
AND FURTHER INTERNAL REVIEW BY EPA.
IX-1
-------
DRAFT
A flow diagram of the proposed system is shown in Figure IX-1.
Zero discharge of soapstone and latex solutions is currently practiced
by production facilities in each of the sub-categories. Elimination
of soapstone solution discharges involves:
1. Recycle of soapstone solution.
2. Installation of curbing around the soapstone dipping area.
3. Sealing of drains in the dipping area.
k. Re-use of the recirculating system washwater as make-up
for fresh soapstone solution.
The re-use of the recirculating system washwater is the key to zero
discharge of this waste. In emptying the system for cleaning, the
soapstone used should be stored in tanks. The washwater used should
also be collected and stored. Once the system is cleaned, stored
soapstone can then be returned to the system for use in the new
production batch. The collected and stored washwater can then be
re-used as make-up water to the soapstone bath during the normal
production run.
Eliminating the discharge of latex solution is achieved by:
1. The use of curbing around the latex dipping area.
2. Sealing of all drains in the dipping area.
3. Containment of all wastewaters from the area.
Several plants have already achieved zero discharge by these methods.
The contained and collected wastes are disposed of off-site in a land-
fill.
Control and treatment of oily waste streams involves segregation, col-
lection, and treatment of these wastes. The wastes to be segregated
include runoff from oil storage and unloading areas and leakage and
spills in the process areas, as shown in Figure IX-1. Press and mill
basins, when present, are included in the process area.
To achieve proper segregation of wastes, any possibility of mixing
process and non-process streams must be eliminated. This^requires
two completely segregated sewer systems, proper plant piping, and
good housekeeping and employee awareness. As a basis for this study,
it was assumed that plants categorized as "old" have combined sewers.
To segregate sewers properly in plants of the "old" sub-category, it
was deemed necessary to install completely new drains and sewer lines;
existing drains would be sealed off. Older plants often have a sig-
nificant number of drains and sewer runs in which the location and
interconnection are often doubtful because of outdated eng.neermg
and installation drawings. It would, therefore, be less costly to
install new plant sewers properly segregated than attempt to red.rect
the existing ones.
NOTICE- THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
JFTTHTS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
IX-2
-------
FIGURE IX-1
HYPOTHETICAL WASTEWATER SEGREGATION AND TREATMENT FACILITY FOR TIRE AND INNER TUBE PLANTS
ROOFED TANK CAR UNLOADING AREAS
ROOFED TANK TRUCK UNLOADING AREAS
i\.
P—• —- — o^>~
H
n n__ n n n
0"
t^
tntir.f UilN
SUUPS
STORAGE
1ANK ^
FURTHER
TREATMENT
FOR OIL
REMOVAL
0!L
STRA*
FILTER
SIMP
SANITARY
UNDF!U
GENERAL PAVED AREAS
£)
+
I
I
I —
PROCESS EFFLUtNT
MONITORING STATION
1
1
;
ADSORBENT
FILTER
EFFLUENT
FINAL EFFLUENT
MONITORING STATIW
-------
DRAFT
Once isolated, these wastewaters are collected in sumps located in
strategic areas throughout the plant. Waste flows will be intermittent
by nature and, therefore, a sizable flow rate will hardly ever be ob-
tained without first collecting all wastes in centralized locations.
Wastewaters collected in these sumps will be periodically pumped to
an API-type gravity separator, where the separable oil and solids
fraction is removed. To provide for large spills or leakage of a
major water supply line, a 37,850-liter (1,000-gal.) storage tank
is provided.
Separated oil is removed by a manually operated slotted pipe. A decant
tank is provided to allow water removed with the oil to settle out.
Concentrated oi1-water mixtures are then removed from the decant tank,
drummed, and sealed, and sent to a landfill. Water removed from the
tank is pumped back to the separator.
Settleable solids collected in the separator are periodically removed
and also sent to a landfill. The separator is provided with two dual-
operating chambers in order to provide for uninterrupted service during
clean-out.
The gravity separator is provided with a straw filter to remove any
large oil globules still remaining due to possible short circuiting
or unforeseen peak overload conditions. Additional treatment for oil
removal is obtained by passing the effluent from the separator through
an absorbent filter.
Effluent Loadings Attainable With Proposed Technologies
Based on the control technology data obtained from tire manufacturer
sources, and treatment data obtained from industries having similar
wastewater problems, it was determined that the proposed Level 1 control
and treatment technologies will result in the following effluent quality
for both Old Tire and Inner Tube and New Tire Facilities:
Oi1 and Grease 5 mg/L
Suspended Solids ^0 mg/L
It is expected that the use of an API separator will result in an ef-
fluent oil concentration of 30 mg/L. The use of an absorbent filter
will further reduce the effluent oil concentration to 5 mg/L.
A reduction in suspended solids concentration will result from the use
of the proposed API-type gravity separator. Additional reduction in
suspended solids is deemed likely after passage through the absorbent
filter. However, no reliable data are available for making such a
determination. As a result, recommended standards for Level 1 are
as follows:
Suspended Solids 0.6** kg/103^kg raw material
Ojl 0.008 kg/10 kg raw material
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
IX-4
-------
DRAFT
Synthetic Rubber Industry
Identification of Best Practicable Control Technology
Currently Available
In view of the fact that all sub-categories of the synthetic rubber
industry are highly technical and proprietary in nature, it is not
possible to base effluent limitation guidelines and standards of
performance on in-plant control technologies which might impact on
processing procedures and product quality. Instead, these guidelines
have been formulated around the best practicable end-of-pipe treat-
ment technologies employed by the synthetic rubber industry. In order
to achieve the contaminant reductions recommended for this guideline,
the synthetic rubber industry v,-i 1 1 require better housekeeping and
maintenance practices, as well as in-plant processing modifications,
to assist the end-of-pipe treatment plant in attaining the required
reductions. The effluent limitations have been based on the effluent
quality and contaminant removal efficiencies of well-designed and
properly-operated treatment facilities. Level 1 technology has been
defined as equivalent to secondary treatment.
Emulsion Crumb Sub-category
The coagulation liquor and crumb rinse overflow stream should be passed
through crumb pits to remove crumb rubber fines. These pits should be
be dual units so that good crumb separation can be achieved during pit
unit cleaning operations. Figure IX-2 shows a hypothetical end-of-pipe
secondary treatment facility applicable to the treatment of emulsion
crumb wastewaters. This treatment includes chemical coagulation and
clarification, and biological treatment. The total plant effluent
should be passed through an equalization basin, providing approximately
2k hours detention, to smooth out waste load peaks and to equalize
hydraulic flow. The equalization basin should be aerated to insure^
good mixing, prevent anaerobic conditions, and assist in the biological
oxidation removal process.
From the equalization basin, the wastewaters are pumped to a mixing
basin, where the pH of the wastewaters is adjusted to achieve optimum
coagulation conditions. The desired pH value is approximately neutral
(pH=7) and is suitable for biological treatment with no changes. ^
Nutrients to facilitate biological treatment will also be added in this
basin.
After pH adjustment, the wastewaters flow into a reactor-clar if ier ,
where coagulating chemicals (alum and polyelectrolyte) are added in
the reactor compartment. A clay slurry is also added, to weight down
the coagulated rubber solids. The wastewater flows from the reactor
compartment to the clarifier, where the settleable solids and coagulated
solids settle and are removed. The clarified wastewater overflows the
clarifier and enters the biollgical treatment system.
THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
R™ORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED.
AND FURTHER INTERNAL REVIEW BY EPA.
IX-5
-------
FIGURE IX-2
HYPOTHETICAL END-OF-PIPE SECONDARY WASTEWATER TREATMENT FACILITY
FOR SYNTHETIC RUBBER PLANTS
ACID
CLAY
I
X
r
*. 12 J»OVANC ED JIL* ™ 2iT_
(REFER TO SECTION X)
pH ADJUSTMENT
AND NUTRIENT
ADDITION
BASIN
-------
DRAFT
The clarified wastewater flows into aeration basins where it is well
mixed with biological solids. Micro-organisms synthesize new biologi-
cal solids from organic matter contained in the wastewater. At the
same time, some soluble matter is consumed for energy purposes using
oxygen supplied by aerators in the basin. The result is that soluble
material is converted to insoluble biological solids and the BOD of
the wastewater is reduced. The mixed liquor containing biological
solids suspended in the wastewater overflows the aeration basin to
the secondary clarifier.
The solids in the mixed liquor are settled in the secondary clarifier,
and the clarified wastewater overflows and enters an effluent monitor-
ing station, where the flow is recorded and an automatic 24-hour
composite sample is collected.
Part of the settled biological solids is returned to the aeration basins
to maintain the mixed liquor solids concentration in the basin. The re-
mainder of the bio-solids must be wasted from the system as a sludge.
The waste sludge is first thickened in a gravity thickener with the
supernatant returning to the head of the aeration basins. The thickened
sludge underflow enters an aerobic digestor, where the biological sludge
is wasted by endogenous respiration utilizing oxygen to aerate and re-
duce the bio-solid bulk. This process is referred to as aerobic
digestion.
This digested sludge is then mixed with the primary solids underflows
from the reactor-clarifier unit and enters a secondary thickener. The
clear supernantant from this thickener is also recycled to the aeration
basins. The thickened underflow is then discharged to a vacuum filter
for further conditioning and concentration.
A drum-type vacuum filter separates thickened sludge into a dewatered
cake, which discharges by belt conveyor to a dumpster bin and into a
filtrate that is recycled to the aeration basin. The dewatered sludge
cake is biologically stable and can be disposed of at a sanitary land-
fill. Filter aid and precoat preparations are used to assist and
maintain the quality of the filtrate.
Solution Crumb Sub-category
The plant wastewaters are first passed through crumb pits to remove
rubber crumb fines. As previously noted in the discussion of the
emulsion crumb sub-category, these pits should be dual units.
Figure IX-2 represents a hypothetical secondary treatment alternative
which is applicable to solution crumb rubber wastewaters, as well as
to the emulsion crumb wastewaters previously discussed. Since solution
crumb wastewaters do not contain uncoagulated latex solids, and if ade-
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED .
AND FURTHER INTERNAL REVIEW BY EPA.
IV-7
-------
DRAFT
quate separation of the rubber fines has been achieved in the crumb pits,
neither the chemical coagulation process nor the primary clarifier is re-
quired. The wastewaters can then pass from the pH and nutrient addition
basin directly into the aeration basin (refer to Figure IX-2). In addi-
tion, since there are no primary solids, the second thickener is not
necessary and the wasted biological sludge passes directly from the
digester to the vacuum filter. The solution crumb secondary wastewater
treatment facility is similar to the emulsion crumb wastewaters in all
other aspects.
Latex Sub-category
The model secondary wastewater treatment facility illustrated in
Figure IX-2 is also applicable at latex rubber plants. Since latex
plant wastewaters contain uncoagulated latex solids, primary clarifica-
tion assisted by chemical coagulation is required. However, because
latex plants are considerably smaller than emulsion crumb plants, the
wastewater flow rate is much lower. The lower flow rates indicate the
use of separate rapid-mix, flocculator, and clarifier units, since
small reactor-clarifiers are not practicable in small diameters due to
reduction in efficiency, mixing, and settlement of solids.
Other than this basic difference (due to flow rate only) in the design
of the primary clarification equipment, the secondary treatment facility
for latex plant wastewaters is identical to that described for emulsion
crumb wastewater.
Effluent Loadings Attainable With Proposed Technologies
Emulsion Crumb Sub-category
Based on raw waste load and the control and treatment data from emulsion
crumb plants, it was determined that the described proposed control and
treatment technologies will result in the following effluent quality:
COD 500 mg/L
BOD 25 mg/L
Suspended Solids 40 mg/L
Oil and Grease 10 mg/L
Effluent quality can also be expressed in terms of effluent waste loads,
which are independent of wastewater flow. These effluent waste loads,
resulting from the application of treatment technologies equivalent to
chemical coagulation with clarification and biological treatment, con-
stitute the best practicable control and treatment technology standards
currently available (Level 1) for the emulsion crumb sub-category.
Recommendations for proposed limitations for Level 1 are:
NOTICE- THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
IX-8
-------
DRAFT
8.00 kg/10^ kg production
0.40 kg/10^ kg production
Suspended Solids 0.65 kg/10^ kg production
Oil and Grease 0.16 kg/103 kg production
Solution Crumb Sub-category
Industry raw waste load and the control and treatment data indicate that
proposed control and treatment technologies for solution crumb rubber
wastewater will achieve the following effluent quality:
COD 245 mg/L
BOD 25 mg/L
Suspended Solids 40 mg/L
Oil and Grease 10 mg/L
Effluent quality can also be expressed in terms of effluent waste loads,
which are independent of wastewater flow. These effluent waste loads,
resulting from the application of treatment technologies equivalent to
primary clarification and biological treatment, constitute the best
practicable control and treatment technology standards currently avail-
able (Level 1) for the solution crumb sub-category. Recommendations
for proposed limitations for Level 1 are:
COD 3.94 kg/10^ kg production
BOD 0.40 kg/10^ kg production
Suspended Solids 0.65 kg/10:; kg production
Oil and Grease 0.16 kg/1015 kg production
Latex Sub-category
Raw waste load and the control and treatment data indicate that the
proposed control and treatment technologies for latex rubber waste-
waters will achieve the following effluent quality:
COD 500 mg/L
BOD 25 mg/L
Suspended Solids 40 mg/L
Oil and Grease 10 mg/L
Effluent quality can also be expressed In terms of effluent waste loads,
which are independent of wastewater flow. These effluent waste loads,
resulting from the application of treatment technologies equivalent to
primary clarification with chemical coagulation followed by biological
treatment, constitute the best practicable control and treatment tech-
nology standards currently available (Level 1) for the latex rubber
sub-category. Recommendations for proposed limitations for Level 1
are:
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
IX-9
-------
DRAFT
COD 6.85 kg/10^ kg production
BOD 0.34 kg/10^ kg production
Suspended Solids 0.55 kg/10^ kg production
Oil and Grease 0.14 kg/10^ kg production
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
IX-10
-------
DRAFT
CHAPTER X
BEST AVAILABLE TECHNOLOGY ECONOMICALLY
ACHIEVABLE -- EFFLUENT LIMITATIONS
Tire and Inner Tube Industry
Effluent limitations commensurate with best available technology econom-
ically achievable and best practicable technology currently available
are identical.
Old Tire and Inner Tube Production Facilities
Suspended Solids 0.064 kg/10^ kg raw materials
Oil and Grease 0.008 kg/10 kg raw materials
New Tire Production Facilities
Suspended Solids 0.064 kg/10^ kg raw materials
Oil and Grease 0.008 kg/10 kg raw materials
Based on a typical plant size of 205 metric tons of raw materials per
day, and process wastewater flow rate of 3.?85 liters/sec (60 ppm), a
loading of .008 kg/1000 kg raw materials results in an effluent con-
centration of 5 mg/L.
This concentration of oil represents the lower accuracy limit based on
currently approved EPA analytical techniques. Further reductions would
therefore be academic, and cost data could then not be equated to addi-
tional beneficial reduction.
A suspended solids loading of .064 kg/1000 kg of raw material consumed
is equivalent to a concentration of 40 mg/L. This concentration is not
significant and will have minimal impact on the receiving stream.
Further reduction in suspended solids does not appear to be justified
either on a cost or on a benefit basis.
AND FURTHER INTERNAL REVIEW BY EPA.
X-l
-------
DRAFT
Synthetic Rubber Industry
Identification of Best Practical Control Technology
Currently Available
After review of the data and control and treatment technologies, it is
clear the principal pollutant load after biological treatment, for all
sub-categories in the Synthetic Rubber Industry waste, is due to COD.
The other parameters (BOD, suspended solids, and oil and grease) are
reduced to comparatively low levels. Therefore, advanced treatment should
be addressed to COD removal and reduction.
None of the end-of-pipe systems observed in use by this industry was con-
sidered completely adequate for establishing effluent limitations com-
mensurate with the best available technology economically achievable
(Level II).
Emulsion Crumb Sub-category
After biological treatment, emulsion crumb wastewaters have low BOD,
suspended solids, and oil and grease concentrations, and high COD concen-
trations (about 500 mg/L). The most feasible technique to reduce residual
COD content after biological treatment is by using an activated carbon
adsorption technique. This technology has been studied in pilot scale
apparatus using as feed stock emulsion crumb wastewaters which had been
subjected to secondary treatment. After treatment with carbon, the
resultant COD level was reduced to about 130 mg/L. This degree of removal
has been used to establish Level I I COD effluent limitations and standards
of performance for the emulsion crumb sub-category.
Because both the quantity and quality of the data available for supporting
the adoption of this level of treatment for secondary wastewaters from
emussion crumb facilities are sparse, the proposed limitations of perfor-
mance will be confirmed by the EPA National Environmental Research Center,
Cincinnati, Ohio prior to approval of this document by the EPA.^ The
technology proposed here involves no more than acceptable technical risk
and uncertainty of costs.
Figure X-l shows a hypothetical advanced wastewater treatment facility using
activated carbon treatment to achieve COD removals adequate for Level II
control and treatment technology.
The secondary effluent discharges into a holding tank which is normally
maintained full by a level-control signal to the feed pumps. The feed
pumps produce sufficient line pressure to pump the wastewater through the
dual multi-media filters and the carbon columns.
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
X-2
-------
FIGURE X-l
HYPOTHETICAL END-OF-PIPE ADVANCED WASTEWATER TREATMENT FACILITY
FOR ALL SUB-CATEGORIES OF SYNTHETIC RUBBER PLANTS
REGENERATED CARBON
MAKEUP CARBON
ECU LSI OX CRUMB
PLANTS ONLY
REGENERATION
FURNACE
CARBON
CHARGE
HOPPERS
BACKWASH TO
AERATION BASINS
BACKWASH TO «-
AERATION BASINS
WASTEWATER
FROM
SECONDARY
TREATMENT
WASTEWATER
HOLDING
TANK
RECHARGE CARBON
DUAL MEDIA
FILTER(S)
FEED
PUMPS
SPENT CARBON
STORAGE
SPENT
CARBON
ACTIVATED
CARBON
COLUMNS
FILTER
BACKWASH
BONITORING
STATION
SPENT CARBON
"•"DISPOSAL
(SOLUTION
CRUSB
MO LATEX
PLANTS)
FINAL
DISCHARGE
COLUMN
BACKWASH
BACKWASH PUMPS
-------
DRAFT
The wastewater is first filtered to remove the residual suspended solids
from secondary treatment. Filtration before the carbon bed will prevent
fine particles from plugging the carbon. The filtration media used generally
are anthracite and fine graded sands. The filters are dual or multiple
units depending on the wastewater flow rate and standard equipment sizes
available. Periodically, these filters require backv/ashing indicated by
a pressure buildup upstream or a pressure drop across the filter bed.
When filter backwashing is necessary, the feed is switched to the dual
unit, the backwash pumps are activated, and the unit undergoes the complete
backwash cycle. Backwash water containing trapped solids is piped to the
aeration basins of the secondary treatment facility. The backwash cycle
usually includes an air scour and a final service flow period for resettle-
ment of the filter media. The flow rate during the backwash cycle is con-
siderably higher than during the normal service cycle and therefore requires
a holding tank of sufficient capacity to furnish the necessary water for the
backwash operation.
The filtered wastewater flows down through the activated carbon columns.
Depending on the wastewater flow rate, two or more parallel carbon bed
columns may be required. Due to solids builup in the carbon columns,
periodic backwashing is also required. Each column is backwashed when the
pressure drop across the column exceeds a pre-set value. The backwashing
water is discharged to the aeration basins of the secondary treatment
faci1i ty.
The carbon in the columns is replaced with fresh or regenerated carbon
when its activity is depleted. This is indicated by breakthrough or
leakage as detected in an automatic total carbon analyzer. The spent
carbon is discharged to a spent carbon storage bin, and a regenerated or
fresh charge of carbon is provided to the columns from a charge hopper.
The effluent from the carbon bed columns has low COD, BOD, suspended solids,
and oil and grease. The flow of this effluent is monitored through a
monitoring station where a 24 hour composite sample is collected.
In most emulsion crumb plants, the carbon usage is sufficiently high to
justify on-site regeneration. Regeneration may be carried out in an oil-
fired, multiple-hearth furnace. The spent carbon is continuously fed from
the spent carbon storage bin to the furnace. The regenerated and cooled
carbon Is then returned to a carbon charge hopper and is ready for re-charging.
Overflow carbon quench and slurry waters from the regeneration process are
discharged to the aeration basins of the secondary treatment plant. Makeup
carbon (to replace carbon lost during unloading, transfer, loading, and
regeneration) is added at the charge hopper. Losses normally amount to
approximately 5 percent of the regenerated carbon weight.
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
X-k
-------
DRAFT
In smaller emulsion crumb production facilities, carbon usage is low and
on-site regeneration may not be feasible. The carbon can then either be
returned to the supplier for regeneration or can be disposed of as solid
waste in a landfill site.
Solution Crumb Sub-Category
The hypothetical advanced wastewater treatment facility illustrated in
Figure X-1 is also applicable to a secondary effluent from solution crumb
wastewater. The illustrated facility will produce an effluent satisfactory
for Level II control and treatment technology.
Although this technology has not been used by plants in the solution crumb
sub-category, it has been studied for emulsion crumb secondary effluent.
Because of the many similarities between solution crumb and emulsion crumb
wastewater (e.g., use of the same monomers and similar processing techniques
by the two sub-categories), it is reasonable to propose this advanced treatment
technology for secondary solution crumb wastewater. The level of treatment
representative of this technology will be confirmed by the EPA National^
Environmental Research Center, Cincinnati, Ohio prior to approval of this
document by the EPA. The technology proposed here to achieve Level II in-
volves no more than acceptable technical risk and cost uncertainty.
The advanced treatment facility for solution crumb is similar to that for
emulsion crumb, except that in most cases the carbon will be disposed of or
regenerated off-site, instead of being regenerated on-site. This is due
primarily to the fact that solution crumb plants are generally smaller than
emulsion crumb plants, and on-site carbon regeneration is not economically
feasi ble.
Latex Sub-Category
Again, the hypothetical advanced wastewater treatment facility illustrated
in Figure X-1 is recommended for treatment of secondary effluent latex rubber
wastewaters. This facility corresponds to the proposed Level II control and
treatment technology for latex rubber plants.
This technology has not been used by latex rubber plants, but it has been
studied, on a pilot scale, for the advanced treatment of secondary ef-
fluent emulsion crumb rubber wastewaters. There are many similarities
in materails used and processing operations between latex and emulsion
crumb production, and hence similarities in their wastewaters D.fferences
tend to revolve around the level of loadings rather than the character.st.es
and constituents. It is, therefore, reasonable to recommend this advanced
treatment technology for secondary effluent latex rubber wastewaters. The
level of treatment attainable by this technology will be conf,rmed by the
EPA National Environmental Research Center, Cincinnati, Oh.o pr.or to ap-
proval of this document by the EPA. This technology involves no more than
acceptable technical risk and cost uncertainty.
NOTICE- THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
m THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
X-5
-------
DRAFT
The hypothetical facility will be similar to that proposed for emulsion
crumb wastewaters. However, it is most probable (because of unfavorable
economics) that on-site carbon regeneration will not be practiced. Off-
site regeneration by the carbon supplier or landfill disposal of the ex-
hausted carbon appears more feasible from a technology and cost basis.
Effluent Loading Attainable with Proposed Technologies
Emulsion Crumb Sub-category
Based on secondary treatment data and pilot studies of activated carbon
adsorption, the proposed control and treatment technologies will result
in effluent quality better than or equal to the following values:
COD 130 mg/L
BOD 5 mg/L
Suspended Solids 10 mg/L
Oil and Grease 5 mg/L
The proposed treatment will probably produce an effluent of higher quality
for BOD, Suspended Solids, and Oil and Grease than the above values. How-
ever, the resultant limitations on these parameters are governed by the
accuracy of the analytical methods.
Effluent quality can also be defined in terms of effluent waste loads,
which are independent of wastewater flow. These effluent waste loads,
resulting from the application of treatment technologies equivalent to
multi-media filtration and activated carbon adsorption, constitute the
best available treatment economically achievable (Level II) for the
emulsion crumb sub-category. The proposed limitations for Level II
are as follows:
COD 2.08 kg/103 kg production
BOD 0.08 kg/103 kg production
Suspended Solids 0.16 kg/103 kg production
Oil and Grease 0.08 kg/103 kg production
Solution Crumb Sub-category
Industry secondary treatment data and data extrapolated from the pilot-
scale activated carbon adsorption studies on secondary effluent emulsion
crumb wastewaters were used to quantify the effluent quality of solution
crumb wastewaters following advanced treatment. The effluent quality is
given as follows:
COD 130 mg/L
BOD 5 mg/L
Suspended Solids 10 mg/L
Oil and Grease 5 mg/L
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
X-6
-------
DRAFT
The effluent values for BOD, Suspended Solids, and Oil and Grease are
dictated by the lower limit of accuracy for the currently accepted
analytical methods.
Effluent quality can also be expressed in terms of effluent waste loads,
which are independent of wastewater flow. The effluent waste loads fol-
lowing multi-media filtration and activated carbon adsorption constitute
the best available treatment economically achievable (Level II) for the
solution crumb sub-category. The proposed limitations for Level II are
as follows:
COD 2.08 kg/103 kg production
BOD 0.08 kg/103 kg production
Suspended Solids 0.16 kg/103 kg production
Oil and Grease 0.08 kg/103 kg production
Latex Sub-category
Latex industry secondary treatment data and data extrapolated from pilot-
scale plant studies on the activated carbon adsorption treatment of emulsion
crumb secondary effluent were used to formulate the following effluent
qual i ties:
COD 130 mg/L
BOD 5 mg/L
Suspended Solids 10 mg/L
Oil and Grease 5
The effluent levels for BOD, Suspended Solids, and Oil and Grease are
dependent on the accuracy of the best accepted analytical methods.
Effluent quality can also be expressed in terms of effluent waste loads
which are independent of wastewater flow. The effluent waste loads re-
sulting from the application of treatment technologies equivalent to multi
media filtration and activated carbon adsorption form the basis for the
best available treatment economically available (Level II) for the latex
sub-category. The proposed limitations for Level II are:
COD 1.78 kg/103 kg production
BOD 0.07 kg/103 kg production
Suspended Solids O.lA kg/103 kg production
Oil and Grease 0.07 kg/103 kg production
NOTICE: THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
X-7
-------
DRAFT
SECTION XI
NEW-SOURCE PERFORMANCE STANDARDS
Tire and Inner Tube Production Facilities
Recommended effluent limitations for new sources are identical and com-
mensurate with best available technology economically achievable and
best practicable technology currently available. These effluent limita-
tions are presented in Sections IX and X of this report.
Synthetic Rubber Industry
Because all stated sub-categories of the synthetic rubber industry are
highly technical and involve proprietary processes, in-plant control
technologies cannot be fully defined or enumerated; such in-plant
measures might impact on manufacturing practices and product quality.
Since advanced wastewater treatment technologies have been proposed for
the best available end-of-pipe treatment economically achievable by
existing plants, no improvement upon those standards can be recommended
for new sources. No additional treatment technologies or controls are
proposed for beyond Level II. It should be noted at this time that the
application of activated carbon adsorption for COD removal after second-
ary treatment involves acceptable but certain technical risks and
unconfirmed costs. The performance of this proposed advanced treatment
technology will be confirmed by the EPA National Environmental Research
Center, Cincinnati, Ohio, prior to approval of this document by EPA.
The effluent waste loads resulting from the application of the best
available treatment economically achievable for new sources (Level III)
for synthetic rubber plants are as follows:
Emulsion Crumb Sub-category
COD 2.08 kg/10;
BOD 0.08 kg/10;
Suspended Solids 0.16 kg/10;
Oil and Grease 0.08 kg/10'
Solution Crumb Sub-category
COD 2.08 kg/10:
BOD 0.08 kg/10:
Suspended Solids 0.16 kg/10:
Oil and Grease 0.08 kg/10'
kg
kg
kg
kg
kg
kg
kg
kg
product ion
production
production
production
production
production
production
production
NOTICE
IN THIS
AND FURTHER
THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
INTERNAL REVIEW BY EPA.
Xl-l
-------
DRAFT
Latex Sub-category
COD K78 kg/10^ kg production
BOD 0.07 kg/10^ kg production
Suspended Sol ids 0.14 kg/10^ kg production
Oil and Grease 0.07 kg/10 kg production
Pretreatment Recommendations
A minimum level of pretreatment must be given to new production facilities
which will discharge wastewater to a publicly owned treatment works. In
addition, potential pollutants which will inhibit or upset the performance
of publicly owned treatment works must be eliminated from such discharges.
Tire and Inner Tube Industry
Pretreatment recommendations for process wastewaters from the tire and
inner tube industry include the separation of oils and solids in an API
gravity separator and the use of an equalization basin to prevent shock
loads of oi 1, suspended solids or batch dumps of dipping solutions from
entering and upsetting the performance of a publically owned treatment
works. Oily wastes, after dilution in a public sewer system,will remain
untreated and therefore must be controlled before discharge from the
plant boundaries.
Pretreatment of other non-process wastewaters from the tire and inner
tube industry will pose more difficult problems. These include alkalinity
in boiler blowdowns and both acidity and alkalinity in water treatment
wastes. Both boiler blowdowns and water treatment wastes will contain
high concentrations of suspended and dissolved solids. Cooling tower
water treatment wastes may contain heavy metals such as chromium and
zinc used for corrosion inhibition. Potential problems such as acidity,
alkalinity, solids, oils, and heavy metals may require control at the
plant to conform to local ordinances for discharge to a publicly owned
treatment works. The control techniques and treatment methods are de-
scribed in earlier sections of this report. Equalization of the waste
load and wastewater flow is the key step in the control of batch dumps
of production chemicals and solutions.
Synthetic Rubber Industry
Emulsion crumb and solution crumb slurry overflow wastewaters should be
passed through crumb pits to remove floatable rubber crumb. Few pub-
licly owned treatment works have primary clarification equipment ade-
quate to handle large quantities of agglomerated rubber crumb solids.
Wastewaters from emulsion crumb and latex production facilities are
invariably laden with uncoagu-lated latex solids. Since publicly owned
treatment works do not generally have coagulation capabilities, these
wastewaters should, at least, be chemical coagulated with a sinking
agent and clarified.
NOTICE- THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
IN THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
XI-2
-------
DRAFT
Utility wastes often exhibit extreme pH peaks which should be neutra-
lized or, at least equalized, prior to discharge to the publicly owned
treatment works. This problem is not so severe with emulsion crumb
and latex plants, where pH adjustment is required prior to chemical
coagulation, as it is with solution crumb production facilities where
adjustment of the wastewater pH is normally not necessary. Heavy
metals, present in cooling tower blowdowns for example, should be
eliminated by substitution of inhibitor or equalized prior to discharge
to a publicly owned treatment works.
No compounds or species present in synthetic rubber wastewater can be
considered toxic or inhibitory to the performance of publicly owned
treatment works.
In summary, the following pretreatment requirements apply to wastewater
discharges to publicly owned treatment works from synthetic rubber
plants:
Emulsion Crumb Subcategory - Gravity separation of crumb fines
in crumb pits, chemical coagulation and clarification of latex-
laden wastewaters, and neutralization or equalization of utility
wastes.
Solution Crumb Subcategory - Gravity separation of crumb^fines
in crumb pits, and neutralization or equalization of utility
wastes.
Latex Subcateqory - Chemical coagulation of latex-laden waste-
waters, and neutralization or equalization of utility wastes.
NOTICE- THESE ARE TENTATIVE RECOMMENDATIONS BASED UPON INFORMATION
m THIS REPORT AND ARE SUBJECT TO CHANGE BASED UPON COMMENTS RECEIVED
AND FURTHER INTERNAL REVIEW BY EPA.
XI - 3
-------
DRAFT
SECTION XII
ACKNOWLEDGEMENTS
Roy F. Western, Inc. wishes to express appreciation to the Rubber
Manufacturers Association (RMA) and its Environment Committee. RMA
and the RMA Environment Conmittee (Daniel G. Pennington, Secretary)
provided valuable assistance in the selection of representative process
plants within the rubber processing industry.
Roy F. Weston, Inc. also acknowledges the assistance of the personnel
at the EPA Regional Centers who were contacted to obtain assistance
in identifying plants in the rubber processing industry known to be
achieving effective waste treatment. Special mention should be given Messrs
Herbert S. Skovronek, John Lank, Paul Ambrose, and Marshall Dick.
Acknowledgement is made of the cooperation of industry personnel in many
plants in the rubber processing industry who provided valuable assistance
in the collection of data relating to process RWL and treatment plant
performance. Special acknowledgement is made of those plant personnel^
and company officers who cooperated in providing detailed plant operating
data to support this study.
Acknowledgement is made also of the assistance and direction provided
by the Project Officer, Mr. John E. Riley, and others associated with
the Effluent Guidelines Division: Messrs. Allen Cywin, Ernest P. Hall,
Walter Hunt, and others who provided helpful suggestions and comments.
XI 1-1
-------
DRAFT
SECTION XI I I
REFERENCES
1. Shreve, R.N., Chemical Process Industries. CPI; McGraw Hill, Inc.,
New York, (19&7).
2. Standen, A., ed., Kirk-Othmer. Encyclopedia of Chemical Technology;
Vol. 17, John Wiley and Sons, New York, (1968).
3. Kestein, B., "SBR and Polybutadiene Rubbers," Symposium on Tire
Material Decisions, AICHE 7^rd National Meeting, Minneapolis, Minnesota,
(August 29, 1972).
k. "Rubber Industry Facts", Rubber Manufacturers Association, New York,
1972.
5. Private Communications from Chem Systems, Inc., New York.
6. "Air Flotation-Biological Oxidation of Synthetic Rubber and Latex
Wastewater", Firestone Synthetic Rubber and Latex Company, Lake
Charles, Louisiana (October 15, 1972).
7 "Industrial Wastewater Reclamation with JtOO.OOO-gal lon-per-day Vertical
Tube Evaporator, Design, Construction and Initial Operation", The
General Tire and Rubber Company, Akron, Ohio (September, 1972).
GENERAL BIBLIOGRAPHY
Rostenbach, R.E., "Status Report on Synthetic Rubber Wastes "Sewage
and Industrial Waste. Vol. 2k; No. 9, (September 1952), 1138-1 U»3.
Placek, O.R. and Ruchhoft, C.C., "A Study of Wastes from the Synthetic
Rubber Industry." Sewage and Industrial Waste. Vol. 18, No. 6,
(November 19^6), 1160-1181.
Martin, A.E. and Rostenbach, R.E., "Industrial Waste Treatment and
Disposal." Industrial and Engineering Chemistry. Vol. ^5, No. 1Z,
(December 1953), 2680-2685.
"Putting the Closed Loop into Practice." Environmental Science and
Technology. Vol. 6, No. 13, (December 1972), 1072-1073.
XIM-1
-------
DRAFT
Dougan, L.D. and Bell, J.C., "Waste Disposal at a Synthetic Rubber
Plant." Sewage and Industrial Wastes. Vol. 23, No. 2, (February 1951),
181-187.
"A Study of Pollution Control Practices in Manufacturing Industries."
Marketing Services Division, Research Services Department, Dun and
Bradstreet, Inc., (June 1970.
Hebbard, G.M., Powell, S.T. and Rostenbach, R.E., "Rubber Industry."
Industrial and Engineering Chemistry, Vol. 39, No. 5, (May 19^7), 589-595.
Ne-nerow, N.L., Theories and Practices of Industrial Waste Treatment,
Addison-Wesley Publishing Co., New York,(1963).
Alliger, G. and Weissert, F.C., "Elastomers." Industrial and Engineering
Chemistry. Vol. 59, No. 8, (August 1967), 80-90.
Herzlich, H.J., "Tire Compounding." Chemical Engineering Progress,
Vol. 69, No. 2, (February' 1973), 77-?8.
Montgomery, D.R., "Integrated System for Plant Wastes Combats Stream
Pollution." Chemica1 Engi neer ing, Vol. 63, No. 4, (February 19&7),
108-110.
Ruebensaal, C.F., "The Rubber Industry Statistical Report and Changing
Markets and Manufacturing Patterns in the Synthetic Rubber Industry."
International Institute of Synthetic Rubber Producers, Inc., New York,
(1972).
Anderson, E.V., "Rubber, A $16 Billion Industry Turns on Tires."
Chemical and Engineering News, (July \k, 19&9), 39-83.
Hofmann, W., Vulcanization and Vulcanizing Agents; Palmerton Publishing
Co., Inc., New York, (1967).
Hawley, G.G., The Condensed Chemical Dictionary, Reinhold Co., New York,
(1970.
Fawcett, R.J. and McDone, E.T., "Special Rubbers in Tires." Symposium
on Tire Material Decisions, AICHE 73rd National Meeting, Minneapolis,
Minnesota, (August 29, 1972).
Lund, H.F., ed., Industrial Pollution Control Handbook; McGraw-Hill, Inc.,
New York, (1971).
XIM-2
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DRAFT
"Methods for Chemical Analysis of Water and Wastes." Environmental Pro-
tection Agency, National Environmental Research Center, Analytical Quality
Control Laboratory, Cincinnati, Ohio, (1971),
Taras, M.J., ed. , Standard Methods for the Examination of Water and
Wastewater. American Public Health Association, Washington, D.C., (1971).
Water; Atmospheric Analysis, Part 23, "Standard Method of Test for Bio-
chemical Oxygen Demand of Industrial Water and Industrial Wastewater."
1970 Annual Book of ASTM Standards, American Society for Testing and
Materials, Philadelphia, Pennsylvania, (1970).
Eckenfelder, W.W., Industrial Water Pollution Control; McGraw-Hill, Inc.,
New York, (1966).
Perry, J.H., ed., Chemical Engineers' Handbook, 4th Ed.; McGraw-Hill, Inc.,
New York, (1963).
XIII-3
-------
DRAFT
SECTION XIV
GLOSSARY
Act
The Federal Water Pollution Control Act Amendments of 1972.
Act i va to r
A metallic oxide that makes possible the crosslinking of sulfur
in rubber vulcanization.
Antioxidant
An organic compound added to rubber to retard oxidation or deterioration.
Accelerator Agents
A compound which greatly reduces the time required for vulcanization of
synthetic or natural rubber.
Banbury Mixer
Trade name for a common internal mixer manufactured by Farrel Corporation
used in the compounding and mixing of tire rubber stock.
.Best Available Technology Economically Achievable (BATEA)
Treatment required by July 1, 1983 for industrial discharges to surface
waters as defined by Section 301 (b) (2) (A) of the Act.
Best Practicable Control Technology Currently Available (BPCTCA)
Treatment required by July 1, 1977 for industrial discharges to surface
waters as defined by Section 301 (b) (1) (A) of the Act.
Best Available Demonstrated Control Technology (BADCT)
Treatment required for new sources as defined by Section 306 of the Act.
BOD
Biochemical Oxygen Demand.
Bag House
An air emission control device used to collect intermediate and large
particles (greater than 20 microns) in a bag filter. A bag filter is con-
structed of fabric. Common usage in the tire industry is to control and
recover carbon black in a dry state from vapors leaving the compounding area.
XIV-1
-------
DRAFT
Butyl Rubber
A synthetic rubber made by the solution polymerization of isobutylene
and isoprene.
Camelback
Tire tread used in the retreading of tire carcasses.
Capital Costs
Financial charges in August 1971 dollars which are computed as the cost
of capital times the capital expenditures for pollution control. Cost
of capital is assumed to be 10 percent.
Carbon Black
A reinforcing agent used in large quantities in tire rubber compounds.
Catalyst
A substance that initiates a chemical reaction and enables it to proceed
at a greatly accelerated rate.
Category and Subcategory
Divisions of a particular industry which possess different traits which
affect water quality and treatabi1ity.
Cement
A solution of synthetic rubber particles.
Chain
A revolving metal belt upon which the newly formed glass fibers fall
to form a thick mat. There are two general types of chains: wire
mesh chains and light conveyors. The latter are hinged metal plates
with several holes to facilitate the passage of air.
Coagulation
The combination or aggregation of previously emulsified rubber particles
into a clot or mass.
COD
Chemical Oxygen Demand.
XIV-2
-------
DRAFT
C rumb
Small coagulated particles of synthetic rubber.
Curing Agent
Curing or vulcanization agents are substances which bring about the
rubber crosslinking process. The most important agent is sulfur. See
vulcanizat ion.
Depreciation
Accounting charges reflecting the deterioration of a capital asset over
its useful life. Reported as straight line over five years with zero
salvage value.
Dry Air Pollution Control
The technique of air pollution abatement without the use of water.
Emulsi on
A stable mixture of two or more immersible liquids held in suspension by
small percentage of substances called emulsifiers.
Endogenous Respiration
Auto-oxidation of the microorganisms producing a reduction and stabilization
of biological solids.
EPDH
A synthetic rubber based on ethylene-propylene and a controlled amount of
non-conjugated diene. Polymerization is carried out in solution.
Extender
A low specific gravity substance used in rubber formulations chiefly to
reduce costs.
Extrude
To shape by forcing a material through a die. The operation is carried
out in a device known as an extruder. In tire and inner tube manufacture
treads and inner tubes are formed by extrusion.
XIV-3
-------
DRAFT
Filler
A high specific gravity (2.00-^.50) compound used in rubber mixtures to
provide a certain degree of stiffness and hardness and used to decrease
costs. Fillers have neither reinforcing or coloring properties and are
similar to extenders in their cost-reducing function.
qpm
Gallons per minute.
Polyisoprene rubber, the major component of natural rubber, made syn-
thetically by the solution polymerization of isoprene.
Investment Costs
The capital expenditures reported in August 1971 dollars required to bring
the treatment or control technology into operation. Included are
expenditures for design, site preparation, purchase of materials, con-
struction and installation. Not included is the purchase of land on
which the system is to be built.
Liter
Latex
A suspension of rubber particles In a water solution. Coagulation of
the rubber is prevented by protective colloids. A colloid is a surface
active substance that prevents a dispersed phase of a suspension from
coalescing by forming a thin layer on the surface of each particle.
Masterbatch
A compounded rubber stock applicable to a wide variety of uses. Main
ingredients are rubber, carbon black and extender oil.
mq/1
Milligrams per liter. Nearly equivalent to parts per million concentration.
Mod? fier
An additive which adjusts the chain length and molecular weight dis-
tribution of the rubber during polymerization.
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Honome r
A compound of a relatively low molecular weight which is capable of
conversion to polymers or other compounds.
NJ3R
Nitrite rubber, a synthetic rubber made by emulsion polymerization of
acrylonitrile with butadiene.
New Source
Any building, structure, facility, or installation from which there is
or may be a discharge of pollutants and whose construction is commenced
after the publication of the proposed regulations.
Non-Productive Rubber Stock
Rubber stock which has been compounded but which contains no curing agents.
Synonym for non-reactive rubber stock.
Non-Reactive Rubber Stock
Rubber stock which has been compounded but which contains no curing
agents. Synonym for non-productive rubber stock.
Operations and Maintenance
Costs required to operate and maintain pollution abatement equipment.
They include labor, material, insurance, taxes, solid waste disposal, etc.
PBR
Polybutadiene rubber, a synthetic rubber made by solution polymerization
of butadiene.
jjH
A measure of the relative acidity or alkalinity of water. A pH of 7.0
indicates a neutral condition. A greater pH indicates alkalinity and
a lower pH indicates acidity. A one unit change in pH indicates a 10
fold change In acidity and alkalinity.
Pigment
Any substance that imparts color to the rubber. Pigment substances such
as zinc oxide or carbon black also act as reinforcing agents.
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Plastic
Capable of being shaped or molded with or without the application of heat.
Process Water
AH waters that come into direct contact with the raw mater ials, inter-
mediate products, final products, or contaminated waters or air.
Productive Rubber Stock
Compounded rubber which contains curing agents and which can be vulcan-
ized. Synonym for reactive rubber stock.
Reactive Rubber Stock
Compounded rubber which contains curing agents and which can be vulcan-
ized. Synonym for productive rubber stock.
Reinforcers or Reinforcing Agent
Fine powders used to increase the strength, hardness and abrasion
resistance of rubber. Reinforcing agents used in the rubber processing
include carbon black, zinc oxide and hydrated silicas.
Styrene Butadiene Rubber, a synthetic rubber made either by emulsion or
solution polymerization of styrene and butadiene.
Soapstone
A substance used to prevent tire and inner tube rubber stocks from sticking
together during periods of storage. Used in both a dry and solution form.
The major ingredient is usually clay.
Solution
A uniformly dispersed mixture of the molecular level of one or more
substances in one or more other substances.
_St ripper
A device in which relatively volatile components are removed from a mixture
by distillation or by passage of steam through the mixture.
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Surface Waters
Navigable waters. The waters of the United States including the
territorial seas.
Tire Bead
Tire beads are coated wires inserted in the pneumatic tire at the point where
the tire meets the steel rim on which it is mounted. They insure an air
tight seal between the tire and rim.
Tire Cord
Woven synthetic or natural fabrics impregnated with rubber. They form the
body of the tire and supply it with most of its strength.
T i re T read
Tire tread is riding surface of the tire. Their design and composition
are dependent on the end use of the tire.
Vulcanization
Vulcanization is the process by which plastic rubber is converted into the
elastic rubber or hard rubber state. The process is brought about by linking
of macro-molecules at their reactive sites.
Wet Air Pollution Control
The technique of air pollution abatement utilizing water as an
absorptive media.
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Enqlish Unit
SECTION XV
METRIC UNITS AND CONVERSION FACTORS
Abbreviation
Conversion Factor by
Metric Unit
Abbrevi at ion
•ere
acre - feet
cubic feet
cubic feet
cubic inches
cubic yards
feet
gal Ion
gal Ion /mi nute
horsepower
inches
pounds
million gallons/day
square feet
square inches
tons (short) (2,000 Ibs)
tons (long) (2,2
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