EP
Group I, Phase II
Developmental Document for
Effluent Limitations Guidelines and
New Source Performance Standards
for the
OTHER NON-FERTILIZER
PHOSPHATE CHEMICALS
Segment of the
PHOSPHATE
MANUFACTURING
Point Source Category
**
UNITED STATES ENVIRONMENTAL
PROTECTION AGENCY
JUNE 1976
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DEVELOPMENT DOCUMENT FOR
EFFLUENT LIMITATIONS GUIDELINES
AND NEW SOURCE PERFORMANCE STANDARDS
FOR THE
OTHER NON-FERTILIZER PHOSPHATE
CHEMICALS SEGMENT OF THE
PHOSPHATE MANUFACTURING
POINT SOURCE CATEGORY
Russell E. Train
Administrator
Andrew W. Breidenbach
Assistant Administrator for Water
and Hazardous Materials
Eckardt C. Beck
Deputy Assistant Administrator for
Water Planning and Standards
Robert B. Schaffer
Director, Effluent Guidelines Division
Chester E. Rhines
Project Officer
June 1976
Effluent Guidelines Division
Office of Water and Hazardous Materials
U.S. Environmental Protection Agency
Washington, D.C. 20460
For sale l)y the Superintendent of Documents, U.S. Government Printing Oilier
Washington, D.C. 20401' - Price $1.80
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ABSTRACT
A study was carried out on the non-fertilizer phosphate
chemical segment of the phosphate manufacturing point source
category for the purpose of developing effluent limitation
guidelines, federal standards of performance, and pretreat-
ment standards. This was done to implement sections 304,
306, and 307 of the Federal Water Pollution Control Acts
Amendments of 1972.
The study included a detailed and extensive exemplary plant
survey, contacts with consultants and government officials,
and literature search.
The industry survey involved data gathering, sample
collection and analysis, and personal visitation with
responsible plant operating personnel to obtain first-hand
information on treatment technology in commercial use and
technology in development and pilot plant stages.
The three main outputs from the study were: industry
subcategorization, recommendations on effluent guidelines,
and definition of treatment technology. The non-fertilizer
phosphate chemicals consisted of three subcategories which
were considered separately for more meaningful separation
and division of waste water treatment, and subsequent
development of effluent guidelines. These subcategories are
defluorinated phosphate rock, defluorinated phosphoric acid
and sodium phosphates. Notice of interim final effluent
limitations guidelines has been drafted for existing sources
for both best practicable control technology currently
available, and for best available technology economically
achievable. Notice of proposed standards of performance for
new sources and notice of pretreatment standards for
existing sources and for new sources has, likewise, been
drafted for each subcategory (FR 40, 4102 and FR 40, 4110,
January 27, 1975). The interim final regulations have been
amended and promulgated for existing and new sources in the
Federal Register notice associated with this document.
Pretreatment standards are being reserved at this time.
Treatment technologies such as in-process or end-of-process
add on units are available singly or in combination to meet
the recommended effluent guidelines.
111
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Index
TITLE PAGE
ABSTRACT
TABLE OF CONTENTS
Section I
Section II
Section III
Section IV
Section V
Section VI
Section VII
Section VIII
Section IX
Section X
Section XI
Section XII
Section XIII
section XIV
Conclusions
Recommendations
Introduction
Industry Subcategorization
Waste Characterization
Selection of Pollutant Parameters
Control and Treatment Technology
Cost, Energy and Non-Water
Quality Aspects
Best Practicable Control Technology
Currently Available, Final
Guidelines and Limitations
Best Available Technology Economically
Achievable, Final
Guidelines and Limitations
New Source Performance
Standards and Pretreatment Standards
Acknowledgments
References
Glossary
Page
1
5
9
21
23
45
57
71
79
89
93
99
101
105
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FIGURES
Page
III-l Defluorinated Phosphate Rock
Plant Locations 17
III-2 Defluorinated Phosphoric Acid
Plant Locations 18
III-3 Sodium Phosphates Plant Locations 19
V-l Defluorinated Phosphate Rock
Fluid Bed Process 24
V-2 Defluorinated Phosphoric Acid
Vacuum Process 33
V-3 Defluorinated Phosphoric Acid
Submerged Combustion 34
V-4 Defluorinated Phosphoric Acid
Aeration Type 35
V-5 Sodium Phosphate Process from
Wet Process Phosphoric Acid 40
VII-1 Contaminated (Pond) Water Treatment 64
vil
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TABLES
Page
VIII-1 Water. Effluent Treatment Costs 73
VIII-2 Summarized Estimated Wastewater
Treatment Costs of Phosphate
Manufacturing Plants 74
XIV-1 Metric Conversion Table 106
1x
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SECTION I
CONCLUSION
This study was conducted for the purpose of extending
effluent limitations guidelines and standards of performance
to all the major chemical products of the Phosphate
Manufacturing Point Source Category, and was directed at
products neither covered in the Phase I phosphate
manufacture study, nor included among the fertilizer
phosphate products. The Phase I phosphate study covered the
production of phosphorus, and products derived from
phosphorus. This Phase II study covers phosphate chemicals
produced by the defluorination of phosphate rock, the
defluorination of phosphoric acid, and the sodium phosphates
produced from wet process phosphoric acid. The
subcategories previously established for the Phosphate
Manufacturing Point Source Category were:
The Phosphorus Derived Chemicals Segment
Subpart A - Phosphorus Production Subcategory
Subpart B - Phosphorus Consuming Subcategory
Subpart C - Phosphate Subcategory.
The Other Non-Fertilizer Phosphate Chemicals Segment,
now added, include:
Subpart D - Defluorinated Phosphate Rock Subcategory
Subpart E - Defluorinated Phosphoric Acid Subcategory
Subpart F - Sodium Phosphates Subcategory
The study of Subparts A, B and C (Phase I) has been
completed and regulations published in the Federal Register,
Title 40, Part 422, page 6580, February 20, 1974. This
Phase II study deals only with Subparts D, E, and F.
The major waste water pollutant problems for Subparts D, E
and F processes of phosphate chemicals manufacture are much
closer associated with the fertilizer phosphate industry
problems than with Subpart A, B and C phosphate
manufacturing problems. The phosphoric acid raw material
utilized for making defluorinated phosphoric acid, for
making sodium phosphates, and used as a reagent in
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defluorination of rock, is exclusively produced by the wet
phosphoric acid process. "^he purification processes carried
on constantly in this segment create fluoride waste water
problems. Residues from salt purification processes contain
phosphate residues along with salt contaminants that create
problems if recycled indefinitely, and require blowdown.
The contaminated water recycle pond, heart of the fertilizer
phosphate waste water treatment system, provides the best
known means of dealing with most of these components.
Fluorides, sulfates and phosphates are precipitated by lime
treatment. Under favorable water balance circumstances,
operation is without discharge of process waste water. The
radium 226 problem is similar to that in the fertilizer
phosphate industry. Radium 226 can be and is controlled by
an adequately alkaline coagulation reaction and effective
clarification while carrying out the double lime effluent
treatment process. Extremely rigorous controls are
essential to prevent flow into ground water through channels
left open by improper lagoon lining operations. Dikes must
be built and maintained in a manner that eliminates failure.
Dike failures have occurred in the slime ponds of phosphate
mining operations and in phosphate manufacturing operations,
recirculation and reuse ponds. Dike failure is a serious
potential hazard from contaminated water ponds. Dike
failure leads to massive pollution by at least 5 highly
objectionable pollutants, radium 226, fluoride, acidic
wastes, phosphate and suspended solids. Recommendations
that drastically reduce the dike failure hazard are provided
in this development document.
The information on fertilizer phosphates in the Development
Document for Effluent Limitations Guidelines and New Source
Performance Standards for the basic fertilizer chemicals
segment of the fertilizer point source category is fully as
important as the information gathered in this study for
dealing with the other non-fertilizer phosphate chemicals
segment of the phosphate manufacturing point source
category. Practicable treatment is available to these
manufacturing operations only through utilization of the
recirculation and reuse lagoon developed for waste water
treatment in wet phosphoric acid manufacture.
In the defluorinated phosphate rock and defluorinated
phosphoric acid processes the techniques and treatment
technologies do exist and are commercially practiced to
achieve essentially no process waste water effluent
discharge to navigable waters. The exception to this
situation would be an adventitious condition such as
abnormal rainfall accumulation. Under such a condition
treatment technology does exist to treat contaminated
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process waste waters for reduction of contaminants on a
commerically demonstrated basis to the effluent limitation
guideline levels.
In the sodium phosphates process, technology does exist to
continuously treat the process waste water effluent to
commercially demonstrated levels that meet the promulgated
effluent limitation guideline levels.
In-process modifications and end-of-process plant waste
water treatment technologies are in current industrial use
to enable new non-fertilizer phosphate chemicals
manufacturing plants to meet the promulgated new source
standards.
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SECTION II
RECOMMENDATIONS
These amendments to the phosphate manufacturing point source
category are being introduced to include the defluorinated
phosphate rock subcategory (Subpart D), the defluorinated
phosphoric acid subcategory (Subpart E) and the sodium
phosphates subcategory (Subpart F).
Final effluent limitations have been written for existing
sources, covering both best practicable control technology
currently available (BPCTCA), and best available technology
economically achievable (BATEA). New source performance
standards (NSPS) have also been promulgated. Pretreatment
has been reserved.
The regulations are about to appear in the Federal Register;
the Federal Register presents the regulations in official
form.
Defluorinated Phosphate Rock and Defluorinated Phosphoric
Acid Subcategories
The effluent guidelines limitations written for the
defluorinated rock and the defluorinated acid subcategories
include specifications on the capacity of the recirculation
and reuse lagoon. The lagoon must maintain reserve capacity
to retain the heaviest expected 24 hour rainfall for a 10
year (or 25 year) period. The treated effluent that may be
discharged in periods of excessive rainfall must meet
specified concentration limits. The surge capacity must
hold the heaviest expected 10 year 24 hour rainfall for
BPCTCA, and the heaviest expected 25 year 24 hour rainfall
for BATEA and NSPS. The guidelines written for the sodium
phosphates subcategory are based on weight units of
pollutant per weight unit of product.
Concentrations of pollutant components permitted in process
wastewater discharges for BPCTCA, BATEA and NSPS:
Effluent Effluent
Charact eristic Limitations
Maximum for Average of daily
any one day values for thirty
consecutive days
shall not exceed
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(Metric units, mg/1)
Total phosphorus 105 35
(as P)
Fluoride 75 25
TSS 150 50
pH Within the range 6.0 to 9.5
The total suspended solid limitation set forth in this
paragraph shall be waived for process wastewater from a
calcium sulfate storage pile runoff facility, operated
separately or in combination with a water recirculation
system, which is chemically treated and then clarified or
settled to meet the other pollutant limitation^ set forth in
this paragraph.
Concentration of pollutants discharged in contaminated non-
process wastewater shall not exceed the values listed in the
following table:
Effluent Effluent
Ch a r a c ter i stic Limitations
Maximum for Average of daily
any one day values for thirty
consecutive days
shall not exceed
mg/1
Total phosphorus 105 35
(as P)
Fluoride 75 25
pH Within the range 6.0 to 9.5
Pretreatment standards are reserved.
Sodium Phosphates Subcategory
The following limitations establish the quantity or quality
of pollutants or pollutant properties controlled by final
regulations for best practicable control technology
currently available:
Effluent Effluent
Characteri stic Limitations
Maximum for Average of daily
any one day values for thirty
consecutive days
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shall not exceed
(Metric units, kg/kkg of product)
(English units, lb/1000 lb of product)
TSS
Total phosphorus
(as P)
Fluoride
pH
0.50
0.80
0.25
0.40
0.30 0.15
Within the range 6.0 to 9.5
The following limitations establish the quantity or quality
of pollutants or pollutant properties controlled by final
regulations for best available control technology
economically achievable and for new source performance
standards:
Effluent
Characteristic
Maximum for
any one day
Effluent
Limitations
Average of daily
values for thirty
consecutive days
shall not exceed
(Metric units, kg/kkg of product)
(English units, lb/1000 lb of product)
TSS
Total phosphorus
(as P)
Fluoride
pH
0.35
0,56
0.18
0.28
0.21 0.11
Within the range 6.0 to 9.5
Pretreatment standards are reserved.
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SECTION III
INTRODUCTION
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
Administration pursuant to Section 304 (b) of the Act.
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. These
are to be 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 304 (b) of the Act. Section 306 of the
Act requires the achievement by new sources of a Federal
standard of performance providing for the control of the
discharge of pollutants which reflects 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.
Section 304(b) of the Act requires the Administrator to
publish within one year of enactment of the Act, regulations
providing guidelines for effluent limitations setting forth
the degree of effluent reduction attainable through the
application of the best control measures and practices
achievable including treatment techniques, processes and
regulations proposed herein set forth effluent limitations
guidelines pursuant to Section 304(b) of the Act for the
fertilizer manufacturing category of point sources.
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. 1624), a list of 27 source categories.
Publication of the list constituted announcement of the
Administrator's intention of establishing, under Section
306, standards of performance applicable to new sources
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within the fertilizer manufactuirng category of point
sources, which included within the list published January
16, 1973.
The effluent limitations guidelines and standards of
performance proposed in this report were developed from
operating data, sampling, and information gathered from six
plants. These plants represent a very high percentage of
the total number of the industrial units in two of the three
study processes. The methods and procedures used in the
accumulation of the overall information are described in the
following paragraphs.
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 the following
manner. The point source category was first studied for the
purpose of determining whether separate limitations and
standards are appropriate for different segments within the
category. This analysis included a determination of whether
differences in raw material used, product produced,
manufacturing process employed, age, size, waste water
constituents, and other factors require development of sepa-
rate limitations and standards for different segments of the
point source category.
The raw waste characteristics for each such segment were
then identified. This included an analysis of (1) the
source flow and volume of water used in the process employed
and the sources of waste and waste waters in the plant; and
(2) the constituents (including thermal) of all waste
waters, including toxic constituents and other constituents
which result in taste, odor, and color in the water or
unfavorable influence on aquatic organisms. The
constituents of the waste waters which should be subject to
effluent limitations guidelines and standards of performance
were identified.
The range of control and treatment technologies existing
within each segment was identified. This included an
identification of each distinct control and treatment
technology, including both inplant and end-of-process
technologies, which are existent or capable of being
designed for each segment. It also included an
identification in terms of the amount of constituents
(including thermal) and the effluent level resulting from
the application of each of the treatment and control
technologies. The problems, limitations and reliability of
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each were also identified. In addition, the nonwater impact
of these technologies upon other pollution problems,
including airf solid waste, noise and radiation were also
identified. The energy requirements of each control and
treatment technology was identified as well as the cost of
the application of such technologies.
The information, as outlined above, was then evaluated in
order to determine what levels of technology constituted the
"best practicable control technology currently available",
the "best available demonstrated control technology,
processes, operating methods, or other alternatives". 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
techniques, process changes, nonwater quality environmental
impact (including energy requirements), and other factors.
Delineation of Study
The industry is characterized by a relatively small number
of plants. Only 1 plant exists for the sodium phosphate
subcategory. Some of the plants did not cooperate with the
study because of trade secret factors. Fortunately, the
technology developed for the phosphorus derived segment of
phosphate manufacturing, and for the phosphate subcategory
of fertilizer manufacturing is extremely well suited for
handling the waste water problems of this segment of the
industry. The background technology has been utilized
extensively in establishing standards for the industry.
The effluent limitations guidelines and standards of per-
formance proposed in this report were developed from
operating data, sampling, and information gathered from 6
plants. The methods and procedures used in the accumulation
of that data is described in the following paragraphs.
Identification and categorization of the 3 processes covered
in this report were made during the preparation of the Phase
I portion of the industry report on Phosphorus Derived
Chemicals. These are:
Defluorinated Phosphate Rock (Subpart D)
Defluorinated Phosphoric Acid (Subpart E)
Sodium Phosphates (Subpart F)
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(produced from wet process phosphoric acid)
Basis for Definition of Technology Levels
The validated data and 'samples described in the foregoing
pages were the primary basis for choosing the levels of
technology which were considered to be the "best practicable
control technology currently available", the "best available
technology economically achievable", and the "best available
demonstrated control technology, process operating methods,
or other alternatives". This selection of the separate
technologies, of necessity, required consideration of such
additional factors as evaluation of the engineering and
operational problems associated with the technology, effect
on existing processes, total cost of the technology in
relation to the effluent reduction that would be realized,
energy requirements and cost, the range of control
variations on contaminant concentration and/or quantity, and
non-water quality environmental impact. Information
regarding the influence of these diverse factors was
obtained from a number of sources. These sources include
government research information, published literature, trade
organization publications. United States process patents,
and qualified consultants. Final levels were set after
extensive discussions between legal and technical divisions.
Implementation
The value of a study such as this is entirely dependent upon
the quality of the data from which it is made. Particular
attention was, therefore, directed to selecting criteria for
determining the commercial installations to be visited and
from which to collect information.
In this Phase II phosphate study the selection of individual
plants for participation in the survey required a minimum of
consideration after the initial U. S. industry plant identi-
fication. Two of the three processes had less than five
total U. S. operating plants. The third process represented
a slightly larger number of operating plants, eleven, and
was found to have essentially identical water usage, water
management and effluent treatment characteristics as one of
the Phase I Phosphate Fertilizer Industry processes.
Because of the relatively few plants involved in each of the
Phase II processes, the consideration of exemplary plant
selection for the survey was not used. For one process, all
U. S. plants were included. For another, all except one U.
S. plant were included. For the third process, its close
relationship to a similar Phase I process necessitated that
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only two plants representing each of the two different
process variations in industrial use be included in the
survey. Full consideration of exemplary plants has now been
covered in cost studies.
Contact was then made with each of the plants selected in
the separate processes to establish a time for a screening
visit. The screening visit had the objective of informing
the plant manager on the purpose and intent of the study.
Information acquired during the visit was used to determine
whether that particular plant was to be included in the
study or whether other plants and/or conditions better
exemplified industry standards. The plants included in the
survey were found to have good effluent monitoring programs
in effect and were maintaining comprehensive records. Study
covered the important fluoride, suspended solids, phosphate,
radium 226, and pH parameters. In some cases the plant
records did not necessarily isolate the liquid streams to
and from the specific process unit involved in the survey
but did provide valuable information on water management
control.
A comparative evaluation was made of the various plants
visited. This evaluation was based upon the criteria used
in the Phase I study. Tt consisted of the following points:
1. Discharge Effluent Quantities
Installations with low effluent quantities including
some plants operating with no discharge of process waste
water.
2. Effluent Contaminant Level
Installations with low effluent contaminant concen-
trations and quantities.
3. Effluent Treatment Method and Effectiveness
Installations utilizing the best currently available
treatment methods, and control equipment.
H. Water Management Practice
Installations with utilization of good management
practices such as main water re-use, planning for
seasonal rainfall variations, in-plant water segregation
and proximity of cooling towers to operating units where
airborne contamination can occur.
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5. Land Utilization
Consideration of land area involved in waste water
effluent control system with the most acceptable being
those with the least area.
6. Air Pollution Control
Consideration given to those plants with the most
comprehensive and effective air pollution control. In
turn liquid effluent from such plants may represent the
most serious waste water effluent condition. Major air
pollution problems considered were fluorine, sulfur
dioxide and radon 222.
7. Geographic Location
Consideration given to those facilities in close
proximity to sensitive vegetation, and with high
population density. Land availability and local and
state restrictions and standards were considered. The
greatest attention was directed to rainfall and
evaporation conditions in the area.
8. Management Operating Philosophy
Plants whose management insists upon effective equipment
maintenance and housekeeping practices.
9. Diversity of Processes
On the basis that other criteria are met, then
consideration was given to installations having a
multiplicity of processes.
Each above criterion was assigned a range of numerical
values to allow a comparative evaluation of the different
plants visited in each process category.
Sampling Collection and Validation of Data
The most important item in a study of this nature is to
obtain data representative of a given process under all
conditions of operation and range of production rates.
Steps and procedures used in selecting data, stream
sampling, and sample analysis were all designed to
accomplish this goal to the best possible degree.
An important step toward this objective was the assignment
of only highly experienced operating personnel to the field
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work. Three persons were used. The fertilizer plant opera-
ting experience of these three people ranged from a minimum
of 16 years to 24 years. With such operational knowledge it
was possible to expeditiously select data, identify specific
process streams for sampling, and conduct sampling under
readily discernible plant operating conditions. The points
considered and identified in all data collection, sampling,
and validation were:
1. Segregation of process effluent streams so that only
an identifiable single process and/or piece of equipment
was represented.
2. Collection of data and samples at different states
of process conditions such as normal steady state, plant
washout when such a procedure is followed on a routine
basis, upset process condition, operation at above/below
plant design rate, and during shutdown conditions if
effluent flow occurs.
3. Evaluation of the effect, if any, of seasonal
rainfall, particularly on non-point source effluent and
ponds.
4. Establishment of the existence of flow measurement
devices and/or other means of quantitatively measuring
effluent flows.
5. Making positive identity of the type, frequency, and
handling of the samples represented by collected data
i.e., such items as grab, composite, or continuous type;
shift, daily or weekly frequency, etc. All samples col-
lected by the contractor were composite samples.
6. Validation of data through determination of plant
laboratory analytical procedures used for sample
analysis, check samples analyzed by independent
laboratories, and/or DPG sampling under known and
defined process conditions with sample analysis by an
accredited commercial laboratory, was completed at each
plant. A total of 6 plants were visited and data were
collected at each plant.
GENERAL DESCRIPTION OF THE INDUSTRY
The segment of the U.S. phosphate industry included in this
Phase II survey includes phosphate manufacturing processes
which utilize phosphate rock or wet process phosphoric acid
as basic raw materials. Phosphate products manufactured
from these processes are utilized as animal feed
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ingredients, fertilizer intermediates, and high quality
sodium phosphate salts.
One of the phosphate processes is the defluorination of
phosphate rock. During the early stages of World War II
bone meal for use as an animal feed supplement came into
short supply. This short supply situation spurred activity
for finding an alternate source and/or process to satisfy
this material so important to the production of animal
foodstuffs. Bone meal supplies two important animal mineral
requirements, namely calcium and phosphorus. Lack of
adequate levels of these ingredients can result in such
animal disorders as aphosphorosis, rickets or infertility.
Materials which can furnish these calcium and phosphorus
ingredients can be derived from two general sources. The
natural occurring type materials used for these minerals are-
such items as bonemeal, meatmeal and fishmeal. An alternate
source was through processing phosphate rock. The problem
with phosphate rock as a direct source lay in the need to
reduce the 3 to 4 percent fluorine content in the rock to a
level which was not harmful to animals upon ingestion.
The outcome of this animal feed supplement supply problem
was that three methods were developed and put into
commercial operation. Over the past years process and
equipment improvements have gradually proven one process to
have the better overall commercial values. This process is
described in detail on the following pages of this section
and is the process used at the three plants included in the
survey.
The estimated annual U.S. production of defluorinated
phosphate rock for recent years is indicated below.
Estimated Annual U.S. Production
Thousands of kkg (tons)
Defluorinated Rock
18% P Content
1968 1969 1970 1971 1972 1973 1974
373(410) 394(435) 380(430) 394(435) 444(490) 485(535) 485(535)
Plant site locations for U.S. plants are indicated on Figure
III-l.
A second phosphate process included in the study is the
defluorination of wet process phosphoric acid. Acid
defluorination is accomplished commercially by two methods.
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DEFLUORINATED PHOSPHATE ROCK
PLANT LOCATIONS
FIGURE III-l
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DEFLUORINATED PHOSPHORIC ACID
co
PLANT LOCATIONS
FIGURE III-2
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SODIUM PHOSPHATES
PLANT LOCATIONS
FIGURE III-3
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The method in most common use is the manufacture of
superphosphoric acid. This process essentially involves the
concentration of phosphoric acid from a 52-54% P2O5
concentration level to a 68-72% P_2°.5 level. In the process
of evaporating water from the acid, fluorine is also
removed. The degree of fluorine removal is dependent upon
the initial fluorine level and the final phosphoric acid
concentration. In most cases the fluorine removal is
sufficient to permit use of the concentrated phosphoric acid
for manufacture of animal feed supplements.
Two types of phosphoric acid evaporators are used to produce
superphosphoric acid. One type uses the principle of acid
circulation in a vessel maintained at sub-atmospheric
pressure. This is the type most prominent in the United
States. A second type uses the principle commonly referred
to as submerged combustion. In this type hot gases directly
from a fuel fired combustion chamber are bubbled through the
acid.
The second method of acid defluorination in commercial use
is the combination of the addition of an additive to the
acid which in turn facilitates fluorine removal by aeration.
Defluorinated acid has several end uses. A large percentage
of the defluorinated acid is mixed with limestone to produce
dicalcium phosphate for animal feed supplement use.
Increasingly greater quantities are being used for liquid
fertilizer production. This use, however, does not require
low fluorine content acid. There is also an increasing use
of superphosphoric acid as an intermediate in the production
of dry mixed fertilizer. The advantage in this latter usage
is a combination of reducing fluorine evolution from the
manufacturing process and savings on raw material freight
costs.
The current annual U.S. production of defluorinated
phosphoric acid is estimated at 760,000 kkg (835,000 tons)
P2O5_. Plant site locations for U.S. plants are indicated
on Figure III-2.
The third phosphate process included in the survey is the
production of high quality sodium phosphate salts.
Conventionally, high purity phosphoric acid as produced from
thermal or electric furnace operations is used as the raw
material for such compounds. Wet process acid is however,
used by one U.S. manufacturer to produce these compounds
primarily for use as intermediates in the production of
cleaning compounds. The plant site location map for this
type unit is indicated as Figure III-3.
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SECTION IV
INDUSTRY SUBCATEGORIZATION
The subcategorization developed for this segment of the
phosphate industry was largely determined in the course of
the Phase I phosphate study and the Phase I fertilizer
phosphate study. Phosphoric acid derived from phosphorus is
a much purer product than the wet process acid of the
fertilizer industry. Human food grade calcium phosphates,
most reagent chemical quality phosphate compounds and sodium
tripolyphosphate are made from phosphorus derived acid.
A comparative list of the impurities and physical
characteristics of furnace acid and wet process acid are
indicated in the following table.
Impurities Furnace Acid Wet Process Acid
Weight Percent
F
S03i
A120 3
O.C07
0.003
0.001
0.0007
-
0.6-1
2.7
0.9
1.2
0.8
.0
Water Insolubles
Total Impurities 0.012 6.2 - 6.6
Density kg/1 (Ib/gal) 1.57 (13.1) 1.72 (14.3)
3) 27°C (80°F)
Viscosity, cp 18 85
Color Colorless Pale green to
dark brown
Although the phosphate compounds of highest purity require-
ments are made from phosphorus derived acid, a substantial
demand developed for products of adequate quality for many
uses, but cheaper than the furnace acid derived materials.
Ma-jor products in this area are calcium phosphates for
animal feed, defluorinated phosphoric acid and sodium
phosphates. The industry supplied this demand through
defluorination of phosphate rock, and defluorination of
phosphoric acid. The sodium phosphate demand is supplied by
products derived from the purification of wet process
phosphoric acid, derived from calcined rock.
-------
Within this group of chemicals, the defluorination of
phosphate rock is carried out by dry calcining, which
distinguishes it sharply from the remaining products derived
through defluorinating liquid phosphoric acid. The most
favorable water balance within the segment is held by this
defluorinated rock process. Substantial evaporation loss
occurs in stack washing to control fluoride emission. The
water used for stack washing picks up substantial fluorine
pollution, much the same as the scrubber water for
fertilizer phosphate plant acid. The major problem is best
handled by recirculation through a contaminated water pond
type of recycle system.
Water is collected from the defluorination of phosphoric
acid. This is water driven from the acid by heat, aided by
air streams and/or vacuum. This water contains the fluoride
contaminant common to phosphoric acid production. The
defluorination processes in use are accompained by the
formation of dehydrated and polymer forms of phosphate from
the orthophosphate in rock and in wet process acid. These
phosphate varieties have high calcium salt solubility; this
introduces a treatment problem lacking in fertilizer
phosphate production if the defluorinatied products get to
the waste water.
Sodium phosphates are produced from conventional wet process
phosphoric acid, which has been derived from calcined rock.
The cacining improves product color through destruction of
organic components. The production of sodium phosphates is
associated with waste water problems similar to the
fertilizer phosphate problems. The conversion of rock to
phosphoric acid is by the usual fertilizer phosphate
process. The purification steps conducted in phosphate salt
manufacture required the blowdown of process water with
fluorine, sulphate and phosphate waste water components, as
well as other salts and solids.
Conventional wet acid production is carried out prior to
production of both defluorinated acids and the sodium salts.
These plants have typical wet acid problems. As a result of
these considerations, and factors developed in the following
sections on manufacturing technology and waste water
characteristics, 3 subcategories have been established for
this segment of phosphate manufacturing:
Subpart D - The Defluorinated Phosphate Rock Subcategory
Subpart E - The Defluorinated Phosphoric Acid
Subcategory
Subpart F - The Sodium Phosphates Subcategory.
22
-------
SECTION V
WASTE CHARACTERIZATION
The technical aspects of the manufacturing processes are
described in this section, along with identification of
water usage, and the development of waste water flow.
DEFLUORINATED PHOSPHATE ROCK - PROCESS DESCRIPTION
General
As mentioned earlier in Section III, the early World War II
shortage of bonemeal produced the necessary incentive to
find an alternate source of animal feed supplement. The two
ingredients required were calcium and phosphorus and these
two elements were prominently present in apatite type
phosphate rock. The one natural apatite rock ingredient
which prevented its use as an animal feed material was the
relatively high (3.0 - U.0%) fluorine content. Basically
the problem was to find an economical means of
defluorinating the rock and still have an end product which
would be palatably acceptable to primarily cows, chickens
and pigs. Three general methods were developed to
defluorinate the phosphate rock.
One method involved treatment of normal superphosphate-
produced by mixing phosphate rock with sulfuric acid.
Reaction of the phosphate rock and sulfuric breaks the
chemical bond that holds the fluorine in the fluorapatite
lattice. This superphosphate is then subjected to
temperatures which volatize essentially all the fluorine.
The mono and dicalcium phosphate compounds in the material
are converted to alpha and beta tricalcium phosphate during
the heat treatment.
A second method involves treating a prescribed mixture of
phosphate rock and silica in an oil fired shaft furnace.
This also volatizes the fluorine and yields a fused
tricalcium phosphate mass. The hot mass is quenched in
water immediately upon exit from the furnace. Chemical
composition of the product is approximately 28% phosphorus
pentoxide and O.U% fluorine.
The third method is described as the calcination of
phosphate rock without fusion. It has demonstrated the most
favorable commercial characteristics and has become the most
prominent U.S. defluorination process. There have been
several significant modifications to this process since its
23
-------
DEFLUORINATED PHOSPHATE ROCK
FLUID BED PROCESS
Fluidizing Gas
> Atmosphere
Contaminated
Recycle
Agglomerated and
Defluorinated
Phosphate
Product
Contaminated
Water to
Retention
Pond
45,894 1/kkg
11,000 g/s.t.
Figure V-I
-------
initial commercial operation in 1944. Initially the process
utilized a mixture of phosphate rock and silica as a feed
material. The silica used was sand that is a by-product
from phosphate rock beneficiation. Ratio of silica to
phosphate rock was an important criterium in the defluorina-
tion process. This charge of silica and phosphate was then
introduced to a rotary kiln. In the interim years these two
original steps - use of silica ratio and rotary kiln - have
been modified. Silica has been partially replaced with
sodium compounds and the rotary kiln has been replaced by a
fluid bed reactor. Not all U.S. production units utilize
both of these modifications but both are practiced by the
major producers. A more detailed process description of the
process using both these modifications is presented on the
following pages.
The defluorination of phosphate rock as practiced at U.S.
commercial production plants is a process on which there is
a limited amount of published information available. Plant
visits included only guarded technical discussions and
limited plant observations. One of the primary reasons for
these practices is the protection of trade secret
information. U.S. patents were therefore the major source
of process information.
The fluorapatite type of phosphate rock is the primary raw
material. Phosphate content of the rock is typically 35%
P2O5. Other raw materials used in lesser amounts but very
critical to the process include sodium containing reagents,
wet process phosphoric acid and silica. The quantity, point
of addition of these materials to the process, and how they
are mixed with the phosphate rock constitute some of the
know-how involved to realize a workable process and a
consistent product quality. These raw materials are added
in specific quantities or ratios dependent upon the feed
phosphate rock analysis.
The sodium containing reagent is commonly soda ash (sodium
carbonate) which has a Na_20 content of approximately 58% or
over 98% Na^CO3. The wet phosphoric acid reagent
concentration used is 45-54% P.2Oj>. Silica addition is in
the form of sand and is dependent on the silica present in
the basic phosphate rock feed. As previously mentioned the
point of addition and how these materials are mixed together
either as a physical mixture or agglomerated into nodular
form is one of the trade secrets. The above described
mixture or charge is then fed into either a rotary kiln or a
fluid bed reactor. In the case of a fluid bed reactor, it
is desirable that the charge be nodular and dried prior to
beinct fed into the reactor. This is in consideration of the
25
-------
fluid bed characteristics of effecting particle
classification and loss in the exhaust gas. In the kiln or
fluid bed reactor, temperature control and retention time
are the process variables which require close control.
Reaction temperatures are maintained in the 1205 - 1366°C
(2200- 270 0°F) range with the rotary kiln requiring the upper
portion of the range.
Retention time ranges from 30 to 90 minutes with the fluid
bed reactor generally requiring the lesser time.
The state of the charge in the kiln or fluid bed reactor is
highly dependent upon the ratio of the raw materials added
to the phosphate rock. That is, whether the fluorine is
evolved in a minimal time period or in sufficient quantity
and/or whether the charge fuses into an unmanageable mass
that rings or solidifies in the unit. Another critical
factor in these units is that water vapor content be
maintained at a sufficiently high percentage to effect the
required fluorine evolution. The equation representative of
the chemical reaction and fluorine release in the kilns and
fluid bed reactors cited in preceding text is:
Ca.lOF2 (PO4)€i * Hl° * SiO2! = 3Ca3(PO4)2 + CaSiO2 + 2HF
phosphate rock water silica tricalcium calcium hydrogen
phosphate silicate fluoride
The reaction is actually much more complex. Dehydration,
not hydrolysis, occurs in the kiln. The product phosphates
are primarily in the poly or dehydrated form. Hydrolysis of
silicon fluoride to silica and hydrofluoric acid occurs on
water scrubbing of the tail gas.
From the kiln or fluid bed reactor the defluorinated product
is quickly quenched with air or water. This is necessary to
maintain the product in the alpha rather than beta
tricalcium phosphate form. The alpha form is the high
solubility material most desirable in the final product.
From this point the product is crushed and sized for storaae
or shipment.
Defluorinated Phosphate Rock - Waste Water Characterization
As previously mentioned, the detail and amount of specific
information on water usage and effluents received and
verified in this survey was minimal. There were two general
reasons for this situation. One was that none of the plants
had operable flow metering equipment. A second reason is
the point already mentioned - that of reluctance to give
26
-------
technical data and free access to the plant operating area
due to the many items regarded as trade secrets. From a
practical standpoint such information in this case would
serve only as background data and a better understanding of
the overall process water balance. On those items which are
important to the study such as water management practices,
effluent analyses, and permission to conduct sampling of
inlet and outlet effluents there was excellent industry
cooperation and information input.
The following types of water usage and effluents were
identified.
A. Contaminated Process Waste Water from Stack
Scrubbing and Reuse Pond
B. Water Supply
C. Spills and Leaks
D. Non-Point Source Discharges
Each of the above listed items are further identified below
as to flow and contaminant content under their respective
headings.
A. C ontaminated Process Waste Water from Stack
Scrubbing (Recycle and Reuse Pond)
The greatest single process wastewater source is
from water used in scrubbing contaminants from the
gaseous effluent streams. This has an
instantaneous water requirement is of appreciable
magnitude and process conditions do permit use of
recirculated contaminated water for this service.
The quality of this contaminated water is similar
to that in fertilizer process circulation systems.
The waste water volume is not normally dependent on
the rainfall and evaporation conditions prevalent
at the plant site. Most plants are on complete
recycle. Evaporation losses are so great that
excessive wastewater accumulations will require
treatment and discharge only in periods of
excessive rainfall.
Complete recycle does not eliminate the need for
lime trestment. Hydrofluoric acid is released
constantly in the high temperature calcining
process, along with sulfurous and sulfuric acids
derived from fuel. Each plant must take measures
27
-------
to control the accumulation of acid to prevent
excessive air pollution. Air pollution control is
achieved by adding lime to the recirculating
wastewater at the stack, adding lime to the pond,
or by constantly liming a portion of the
recirculating pond water, removing the calcium
fluoride, the calcium sulfate and the calcium
phosphate precipitates, and returning the
supernatant fraction to the pond. Solid wastes are
always formed by the measures essential to control
air pollution. The wastewater composition may be
unusual at sites where manufacture of products
other than defluorinated rock is carried out and
the wastewater from these products discharged into
the recycle and cooling pond. system. A water
analysis obtained from a Plant B sample during the
survey is typical of contaminated water used in
defluorinated phosphate rock process units.
Contaminated Water Constituents
Parameter Cone entr at i on
pH 1.65
Total Suspended Solids 16.00 mg/1
Total Solids 2,267.00 mg/1
CMoride (Cl) 101.00 mg/1
Sulfate (SO4) 350.00 mg/1
Calcium (Ca) UO.OO mg/1
Magnesium (Mg) 12.00 mg/1
Aluminum (Al) 58.00 mg/1
Iron (Fe) 8.30 mg/1
Fluorine (F) 1,930.00 mg/1
Arsenic (As) 0.38 mg/1
Zinc (Zn) 5.20 mg/1
Phosphorus (P) 600.00 mg/1
BOD5 3.00 mg/1
COD 48.00 mg/1
Color #120 (after filter)
Turbidity 15.00 Jackson
Candle Units
The following figures indicate a representative water usage.
These figures will vary within reasonable limits between
plants and at different seasons of the year but are
representative of the magnitude of usage required in the
process.
1/kkg (gal/ton)
28
-------
45,894 (11,000)
B. Water Supply
Water supply water is defined as essentially
uncontaminated water from such sources as wells,
commercial or municipal water systems, and
impoundment areas for natural rainfall or runoff.
Such water is added to the process for such reasons
as process functions where contaminated water use
is prohibited due to process requirements, make-up
water to the contaminated water system and
equipment, or area wash downs. The following
figures indicate the usage range.
1/kkq (gal/ton)
877 (210)
C. Leaks and Spills
Various sources of contaminated non-process waste-
water have been established by the definition of
"contaminated non-process wastewater" that appears
in the regulations pertaining to defluorinated
phosphate rock manufacture:
The term "contaminated non-process wastewater"
shall mean any water including precipitation
runoff, which during manufacturing or processing,
comes into incidental contact with any raw
material, intermediate product, finished product,
by-product or waste product by means of (1)
precipitation runoff, (2) accidental spills, (3)
accidental leaks caused by the failure of process
equipment and which are repaired or the discharge
of pollutants therefrom contained or terminated
within the shortest reasonable time which shall not
exceed 24 hours after discovery or when discovery
should reasonably have been made, whichever is
earliest, and (4) discharges from safety showers
and related personal safety equipment, and from
equipment washings for the purpose of safe entry,
inspection and maintenance; provided that all
reasonable measures have been taken to prevent,
reduce, eliminate and control to the maximum extent
feasible such contact and provided further that all
reasonable measures have been taken that will
mitigate the effects of such contact once it has
occurred.
29
-------
While an allowance has been made for the discharge
of treated contaminated non-process wastewater, it
is the responsibility of every manufacturer to
exercise diligence in repairing leaks or in
correcting other conditions that create
contaminated non-process wastewater, so that
contamination is held to the lowest possible level.
Many manufacturers have demonstrated that spurious
contamination from leaks and spills and other
sources can be kept at a very low level.
Continuous analysis of pH, conductivity or total
organic carbon is being conducted on large cooling
water streams so that serious leaks are almost
immediately detected. Corrective measures are put
into action immediately on detection. In many
circumstances, the system salvages products of
sufficient value to more than pay for the
monitoring system. Good housekeeping practices,
efficient operation and prompt maintenance will
minimize contamination of water from leaks and
spills. Techniques for achieving control and
prevention of such losses are described in
"Guidelines for Chemical Plants in the Prevention,
Control and Reporting of Spills" by the
Manufacturing Chemists Association, 1972.
Shipping losses were excluded from the data base
and regulations. These losses are egually amenable
to control and prevention as leaks and spills.
Good housekeeping, prompt and regular maintenance,
and careful operations will tend to minimize losses
from shipping operations.
D. Non-Point Source Discharge
The origin of this discharge is dry materials -
both raw material and product - which dust over the
plant area usually emitted from conveying
equipment. These materials are then solubized or
sluiced by rain or melting snow into the plant
drainage system.
DEFLUORINATED PHOSPHORIC ACID - PROCESS DESCRIPTION
General
Defluorinated phosphoric acid is to a degree a bit
misleading to persons associated with the fertilizer
industry. The reason being that acid defluorination is
30
-------
inherently included in the process of evaporating commercial
wet process 54% P2O5 phosphoric acid to the superphosphoric
acid (68-72% P2Oj>) concentration level. To fertilizer
people therefore, the principal U. S. defluorinated acid
process is better known as a superphosphoric acid unit. Two
different type superphosphoric units are in commercial use
in the U. S.
Another method of defluorinating wet process phosphoric acid
has come into commercial use in the past few years. This
process also uses commercial wet process 54% P2Oj> phosphoric
acid as the raw material. In this process an additive is
mixed with the phosphoric acid to aid in the release and
volatilization of fluorine from the liquid. The mechanism
for fluorine removal from the acid is aeration.
Defluorinated phosphoric acid is used primarily as a raw
material for production of mixed fertilizer goods - both dry
and liquid types. It is also mixed with limestone in the
manufacture of dicalcium phosphate for use as an animal feed
supplement. Approximately 67% of the estimated U. S.
835, ^00 annual tons P2Oj> quantity of def luorinated acid is
used in fertilizer manufacture and 33% in the production of
dicalcium phosphate. The degree of defluorination required
to meet animal feed regulations is that the P to F ratio be
at least 100 to 1.
DEFLUORINATED ACID - VACUUM TYPE EVAPORATION
The vacuum type evaporation method for defluorination of wet
process phosphoric acid is essentially identical to the
procedure and equipment used to produce 54% P2O5 phosphoric
acid from 26-30% P2O5 strength acid.
Concentration of 54% P2O5 acid to a 68-72% P2O5 strength is
performed in vessels which use high pressure (450-55C psig)
steam or externally heated Dowtherm solution as the heat
energy source for evaporation of water from the acid. These
units effect evaporation by circulating acid at a high
volume rate consecutively through a shell and tube heat
exchanger and a flash chamber under low absolute (vacuum)
pressure conditions. In the heat exchanger, steam or
Dowtherm solution is applied to the shell side and acid
flows through tubes. Acid flow through the tubes is of the
wetted wall type rather than full tube flow. The flash
chamber serves to provide a large liquid surface area where
water vapor is released without significant acid entrainment
loss. Fluorine removal from the acid occurs concurrently
with the water vapor release. Both of these gases pass to a
31
-------
barometric condenser and are absorbed in the condenser
water. Dependent upon the quality of superphosphoric acid
being produced (e.a. 30 or 50-6055 conversion to
polyphosphates), either a single unit or a series of two
units may be used to accomplish the evaporation and/or
defluorination required.
DEFLUORINATED ACID - SUBMERGED COMBUSTION
A second method of phosphoric acid defluorination is by the
direct contact of hot combustion gases with the acid. In
this method a combustion chamber fitted with one or more
fuel oil or gas burners is mounted directly on top of an
acid containment chamber. Pressurized hot gases from the
fuel combustion are bubbled through the acid to an immersion
depth of up to approximately 46 cm (18 inches). Acid in the
containment chamber is maintained at a constant level by
control of the low concentration feed acid flow. The
production of evaporated and defluorinated product acid from
the unit is continuous and is controlled by acid boiling
point or temperature.
(evaporated water, stripped hydrogen fluoride and
silcon tetrafluoride) from the evaporation chamber flow to a
series of gas cleaning and absorption equipment. First,
entrained phosphoric acid is recovered from the gas stream
and re-introduced to the unit or to the phosphoric acid
plant. Following acid removal, the gases pass to a multi-
stage direct contact condenser system where a high
percentage of the contaminants are removed before exhaust to
the atmosphere. Water can be used in all or only the final
stages of the condenser system as a condensing and scrubbing
medium.
DELUORINATED ACID - AERATION
This method of defluorinating phosphoric acid is the most
recent proprietary method to come into commercial use.
Relatively small quantities of diatomaceous silica or spray
dried silica gel with high surface area characteristics are
mixed with commercial 54% V2O5 phosphoric acid. This silica
material addition serves to supply sufficient silica for
conversion of the minor quantity of hydrogen fluoride (HF)
present in the impure phosphoric acid to fluosilicic acid
(H2SiF6). Fluosilicic acid at an adequate temperature in
turn breaks down to SiF4_ and by simple aeration is stripped
from the heated mixture. The gaseous effluent stream is
maintained above its dew point until it enters the gas
32
-------
Water
DEFLUORINATED PHOSPHORIC ACID - VACUUM PROCESS
(Super Phosphoric)
Water
Water
water i
Steam 1
—— — "^^ T P\
54% Phos-
phoric Acid
No. 2
Evapo-
rator
Shipping
Pump
Product
Cooler
To Cooling Pond
70,510 1/kkg
16,900 g/s.t.
Alternate Heat
Medium
"I
Alternate Heat Medium
i—... — i Combustion
j Gases
Fuel
Process
Water
43 1/kkg
14 g/s.t.
Figure V-2
-------
DEFLUORINATED PHOSPHORIC ACID
(Submerged Combustion)
Gas
Air
Feed Acid
>
Burner
i i
1 Dip Tube i
*v X
X s
v_ /
\
1
r*.
_?>
^
Pond
Water
18,024
7 1/kkg
4,320
g/s.t.
To Atmosphere
t
OJ
V
/
Evaporator
f
hosphoric
d
scruoce
•f\
-^
-------
Process
Water
Silica
DEFLUORIN'ATED ACID - AERATION TYPE
Contaminated
Water
54%
Phosphoric
I
P205
Acid
Product to
Shipping
To
Atmosphere
Scrubber
Fan
To
Contaminated Water
Pond
Steam
Heat
Exchanger
^Condensate Return
Circulation Pump
Figure V - 4
-------
scrubbing unit. At this point the gas stream is contacted
with water to remove contaminants before release to the
atmosphere. Phosphoric acid (5H% P2()5) can be defluorinated
to a weight ratio of 100 to 1 or better P to F by this
method.
Defluorinated Phosphoric Acid - Waste Characterization
Information on water usage and effluents was obtained on two
of the three defluorination methods described, namely,
Defluorinated Acid - Vacuum Type Evaporation and
Defluorinated Acid - Submerged Combustion. No commercial
operating data or sampling information was obtained on the
Defluorinated Acid - Aeration method. This method of
defluorination has been commercial for a relatively short
time and patent protection had not yet been granted either
the original inventor or the licensee on his additional
modifications. As a result of this situation no detailed
information was attainable on this process. It is known
however, that the method's usage is confined to removal of
air contaminants from the gaseous effluent stream and
possibly a minor quantity of process water for seal water
use. Both of these usages will qualitatively and
quantitatively be equal to or less than those indicated for
the other two methods.
The following types of water usage and effluents were
identified:
A. Contaminated Process Waste Water from Tail Gas or
Stack Scrubbing Operation (Recycle and Reuse Pond)
B. Water Supply
c- Leaks and Spills
Various sources of contaminated non-process wastewater have
been established by the definition of "contaminated non-
process wastewater" that appears in the regulations
pertaining to defluorinated phosphoric acid manufacture:
The term "contaminated non-process wastewater" shall mean
any water including precipitation runoff, which during
manufacturing or processing, comes into incidental contact
with any raw material, intermediate product, finished
product, by-product or waste product by means of (1)
precipitation runoff, (2) accidental spills, (3) accidental
leaks caused by the failure of process equipment and which
are repaired or the discharge of pollutants therefrom
contained or terminated within the shortest reasonable time
which shall not exceed 24 hours after discovery or when
36
-------
discovery should reasonably have been made, whichever is
earliest, and (4) discharges from safety showers and related
personal safety equipment, and from equipment washings for
the purpose of safe entry, inspection and maintenance;
provided that all reasonable measures have been taken to
prevent, reduce, eliminate and control to the maximum extent
feasible such contact and provided further that all
reasonable measures have been taken that will mitigate the
effects of such contact once it has occurred.
While an allowance has been made for the discharge of
treated contaminated non-process wastewater, it is the
responsibility of every manufacturer to exercise diligence
in repairing leaks or in correcting other conditions that
create contaminated non-process wastewater, so that
contamination is held to the lowest possible level.
Many manufacturers have demonstrated that spurious
contamination from leaks and spills and other sources can be
kept at a very low level. Continuous analysis of pw,
conductivity or total organic carbon is being conducted on
large cooling water streams so that serious leaks are almost
immediately detected. Corrective measures are put into
action immediately on detection. In many circumstances, the
system salvages products of sufficient value to more than
pay for the monitoring system. Good housekeeping practices,
efficient operation and prompt maintenance will minimize
contamination of water from leaks and spills. Techniques
for achieving control and prevention of such losses are
described in "Guidelines for Chemical Plants in the
Prevention, Control and Reporting of Spills" by the
Manufacturing Chemists Association, 1972.
Shipping losses were excluded from the data base and
regulations. These losses are equally amenable to control
and prevention as leaks and spills. Good housekeeping,
prompt and regular maintenance, and careful operations will
tend to minimize losses from shipping operations.
A. Contaminated Water
The only significant water usage in these defluorinated
acid methods is for use in scrubbing contaminants from
the gas effluent streams. The scrubber equipment may be
in the form of either a barometric condenser or the more
conventional gas scrubber type. In either case, the
instantaneous water requirement is of appreciable
magnitude. As in the defluorinated phosphate rock, the
process conditions do permit use of contaminated water
for this service. Water quality similar to that
37
-------
prevailing in wet process phosphoric acid recycle
systems. A common recycle system is utilized at some
plants for wet acid and for deflurinated acid
production. Wastewater volume is dependent on rainfall
and evaporation conditions at plant site. The amount of
acid collected in the wastewater at a defluorinated acid
plant is determined by the amount of hydrofluoric acid
removed from the raw product wet phosphoric acid, and
the phosphoric and sulfuric acids entrained and
separated in the fluoride removal process. A water
analysis obtained from a Plant D sample during the
survey is typical of contaminated water used in
defluorinated acid process units.
Contaminated Water Constituents
Parameter Concentration
pH 1.29
Total Suspended Solids 30.00 mg/1
Total Solids 28,810.00 mg/1
Chloride (Cl) 65.00 mg/1
Sulfate (SOU) 4,770.00 mg/1
Calcium (Ca) 1,700.00 mg/1
Magnesium (Mg) 106.00 mg/1
Aluminum (Al) 260.00 mg/1
Iron (Fe) 180.00 mg/1
Fluorine (F) 967.00 mg/1
Arsenic (As) 0. 83 mg/1
Zinc (Zn) 5. 30 mg/1
Total Phosphorus (P) 5,590.00 mg/1
BOD5 15.00 mg/1
COD 306.00 mg/1
Color #120 (after filter)*
Turbidity 45 Jackson
Candle Units
* Unit of color - potassium chloroplatinate
The following figures indicate a representative water usage.
These figures will vary within reasonable limits between
plants and at different seasons of the year but are
representative of the magnitude reguired in the process.
Method 1/kkg (gal/ton)
Defluorinated Acid - 70,510 16,900
Vacuum Type Evaporation
38
-------
Defluorinated Acid - 18,024 4,320
Submerged Combustion
B. Water Supply
Water supply water is defined as uncontaminated water from
such sources as wells and commercial or municipal water
systems. The water is used for pump seal water. Usage
figures are listed below:
Method 1/kkg (gal/ton)
All Methods 43 14
C. Spills and Leaks
Spills and leaks are collected as part of process efficiency
and housekeeping. Sources of this water are pump seals and
plant wash up. The quantity is minor and/or periodic.
SODIUM PHOSPHATE - PROCESS DESCRIPTION
General
The high quality standards set by detergent manufacturers
for their products necessitates that an essentially pure
sodium phosphate solution be used as a raw material. This
high purity standard has greatly limited the use of wet
process phosphoric acid as a phosphate source for this
industry. One U. S. manufacturer however, does commercially
purify wet process acid to the degree necessary to allow its
use in the manufacture of sodium phosphate compounds for
detergent manufacture.
Wet process acid contains an appreciable number and quantity
of impurities which must be removed to achieve the
acceptable detergent purity requirements. The more
significant impurities to be removed include excess sulfuric
acid, sodium fluosilicate, iron phosphate, aluminum
phosphate and calcium sulfate. Many of the process pro-
cedures and techniques used for removal of these impurities
are regarded to be trade secrets.
Sodium Phosphates - Process Description
Removal of impurities from the wet process acid used in this
process begins with the phosphate rock used in the acid
39
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Wet Process Phosphoric Acid
SODIUM PHOSPHATE PROCESS
FROM WET PROCESS
PHOSPHORIC ACID
MONO SODIUM
PHOSPHATE
7640-10013 1/kkg
(1830-2400 gal/s.t.)
DISODIUM PHOSPHATE
DUOHYDRATE OR
ANHYDROUS
DISODIUM PHOSPHATE
CRYSTAL
TETRA SODIUM PYRO
PHOSPHATE
Figure V-S
-------
manufacture. Calcined phosphate rock ' is used in the
acidulation step to yield a nearly colorless acid to start
the purification steps. Rock calcination destroys the
organic matter inherent in mined rock. It is organic matter
which causes the brown coloration that normally
characterizes wet process phosphoric acid.
After the initial 20-25% P205 acid is produced, the acid is
treated in a series of separate neutralization steps to
individually remove the various acid impurities. The first
partial neutralization with recycled sodium phosphate liquor
is designed to remove the fluosilicates. In this step
granular sodium fluosilicate is precipitated and removed
from the acid solution by filtration. This precipitate has
commercial value as 98-99% sodium silicofluoride (Na^SiF6).
The next step consists of adding sodium sulfide to the
remaining solution to precipitate the minor quantity of
arsenic present. Concurrently with this precipitation,
barium carbonate can be added to remove the excess sulfate
present as barium sulfate. Barium carbonate is not used at
the plant producing sodium phosphates at the present time.
Precipitates are now removed by another filtration step.
The quantity of precipitate is small and is disposed of as
solid waste. Local landfill authorities should be notified
of the arsenic component.
At this point the partially neutralized acid still contains
iron and aluminum phosphates, and some residual fluorine. A
second neutralization is now made with soda ash to an
approximate 4.0 pH level. This induces precipitation of
essentially all the remaining impurities. These
precipitated impurities are both quite voluminous and
difficult to separate from the remaining solution. Special
techniques of heating, agitation, and retention are
necessary to adequately condition the slurry so that a
filtration separation of the impurities can be made. These
impurities contain a relatively high quantity of P2pj> (40-
50%) and have value as a fertilizer material. Following
this neutralization step, the remaining solution is
sufficiently pure for the production of monosodium
phosphate.
Monosodium phosphate is crystallized from the purified
solution by concentrating the solution in an evaporator.
The monosodium crystals, with further dehydration,
neutralization and crystallization, can be converted to such
other compounds as sodium meta phosphate, disodium
phosphate, and tri-sodium phosphate. The several chemical
41
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equations and steps involved in this process are indicated
on the process flowsheet.
Water effluents from these different processes are from
spills and leaks, filtration washes, and gas scrubber
liquors.
Sodium Phosphates - Waste Characterization
The survey of this process was limited by the same type of
conditions and for the same reason which existed in the
defluorinated phosphate rock process. This was that many of
the various unit operations are considered trade secret and
therefore plant access was necessarily limited to
observations of effluent streams external to the process
buildings. As previously stated, from a practical
standpoint this restricted access takes nothing away from
the value of the study other than background information and
a better understanding of the overall process water balance.
On those items' which were basic and important to the study,
the industry cooperation and response to information
requests was excellent. The installed process effluent
measurement and monitoring facilities were found to be well
developed and maintained.
The following types of water usage and effluents were
identified.
A. Water Supply
B. Contaminated Effluent
C. Spills and Leaks
D. Non-Point Source Discharges
Each of the above listed items are further identified below
as to flow and contaminant content.
A. Water Supply
Water supply is defined as uncontaminated water from
wells. The water is used for pump seal water and in
various product filtration and washing procedures.
Usage figures are listed below.
kkg (gal/ton)
9,992-12,349 2,395-2,960
B. Contaminated Effluent
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This effluent is essentially the used process water with
impurities that were added from the process function in
which it was used. An effluent analysis typical of an
effluent sample from Plant E is listed below.
Contaminated Water Constituents
Parameter
Concentration
pH
Total Suspended Solids
Total Solids
Chloride (Cl)
Sulfate (SO4)
Calcium (Ca)
Fluorine (F)
Total Phosphorus (P)
BOD5
COD
Temperature
The following figures represent the range of water effluent
quantities found.
7.8
460
2,100
90
240
95
15.0
250
31.0
55.0
78<>F
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
1/kkg
7,640-10,013
(gal/ton)
1,830-2,400
C. Leaks and Spills
Many manufacturers have demonstrated that spurious
contamination from leaks and spills and other sources
can be kept at a very low level, continuous analysis of
pH, conductivity or total organic carbon is being
conducted on large cooling water streams so that serious
leaks are almost immediately detected. Corrective
measures are put into action immediately on detection.
In many circumstances, the system salvages products of
sufficient value to more than pay for the monitoring
system. Good housekeeping practices, efficient
operation and prompt maintenance will minimize
contamination of water from leaks and spills.
Techniques for achieving control and prevention of such
losses are described in "Guidelines for Chemical Plants
in the Prevention, Control and Reporting of Spills" by
the Manufacturing Chemists Association, 1972.
Shipping losses were excluded from the data base and
regulations. These losses are equally amenable to
control and prevention as leaks and spills. Good
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housekeeping, prompt and regular maintenance, and
careful operations will tend to minimize losses from
shipping operations.
No special allowance has been made for discharge of
cooling water and other non-process wastewater that
becomes contaminated by spills and leaks or incidental
contact with raw materials, reagents or products. The
contaminated process wastewater allowances are adequate
to take care of these incidental sources of water
contamination. It is the responsibility of the
manufacturer to exercise diligence in repairing leaks or
correcting other conditions that create contaminated
non-process wastewater so that contamination is held to
the lowest possible level.
D. Non-Point Source Discharge
The origin of this discharge is primarily dry product
which dusts over the plant area from conveying
equipment. This product is periodically solubilized by
rain or melting snow and collected by the plant waste
sewer system. In this process the non-point discharge
is considered to be a significant periodic influence on
the plant effluent contaminant level.
RAW WASTE LOADS
The raw waste loads are summarized below:
Defluorinated Phosphate Rock
Flow: 46,000 1/kkg (11,000 gal/ton)
Total Phosphorus (P) 600 mg/1
Fluoride (F) 1,930 mg/1
TSS 16 mg/1
pH 1.65
Defluorinated Phosphoric Acid
Flow: Vacuum Type Evaporation 70,500 1/kkg (16,900 gal/ton)
Submerged Combustion 18,000 1/kkg (4,300 gal/ton)
Total Phosphorus (P) 5,590 mg/1
Fluoride (F) 967 mg/1
TSS 30 mg/1
pH 1.29
Sodium Phosphates
Flow: 7,600 - 10,000 1/kkg (1,830 - 2,400 gal/ton)
Total Phosphorus (P) 250 mg/1
Fluoride (F) 15 mg/1
TSS 460 mg/1
pH 7.8
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SECTION VI
SELECTION OF POLLUTANT PARAMETERS
General
The selection of pollutant parameters was a necessary early
step of the study. Collection of meaningful data and
sampling was dependent on knowing what fertilizer process
contaminants are important so far as degradation of natural
water resources are concerned.
The general criteria considered and reviewed in the
selection of pollutant parameters included:
- quality of the plant intake water
- products manufactured
- raw materials used
- environmental harmfulness of the compounds or elements
included in process effluent streams
Other Non-Fertilizer Phosphate Chemicals
Effluent waste waters from the three processes included in
this survey are similar to those associated with the
phosphate fertilizer industry. The primary factors and
contaminants to be controlled to achievable levels are:
suspended solids, pH, phosphorus and fluorides.
Radium 226 is considered to be a very important raw waste
load component. Radium 226 coprecipitates with most
sedimentary fractions, particularly at a reasonably high pH
level. The pH 6.0 to 9.5 range set for effluent discharges,
along with the limitations as suspended solids, deals
effectively with the effluent problem. The Environmental
Protection Agency has ongoing studies and is initiating new
studies on the problem of radium-226 in recycle pond waters.
Such studies indicate that double lime treatment to a pH
range of 6.0 to 9.5 is reguired to achieve optimum removal
of radium-226. Additional information obtained from these
studies will be evaluated, and where appropriate, current
effluent guidelines may be amended. Procedures currently
proposed are judged to be adequate and provide for rigorous
control of radium-226. A more detailed discussion of this
problem can be found in references N and O.
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Secondary parameters which should be monitored but do not
warrant definitive guidelines are: temperature, total
dissolved solids, chemical oxygen demand (COD), arsenic, and
cadmium. The prime reason for not setting guidelines for
these secondary parameters is that treatment for the primary
parameters will effect removal of also the secondary ones.
A considered additional reason is that insufficient data
exists from which to establish responsible guidelines.
Selection of these parameters is justified by the fact that
best available technology economically achievable as well as
best demonstrated technology is in current commercial use.
Rationale for Selection of Parameters
Temperature
Temperature is one of the most important and influential
water quality characteristics. Temperature determines those
species that may be present; it activates the hatching of
young, regulates their activity, and stimulates or
suppresses their growth and development; it attracts, and
may kill when the water becomes too hot or becomes chilled
too suddenly. Colder water generally suppresses
development. Warmer water generally accelerates activitv
and may be a primary cause of aquatic plant nuisances when
other environmental factors are suitable.
Temperature is a prime regulator of natural processes within
the water environment. It governs physiological functions
in organisms and, acting directly or indirectly in
combination with other water quality constituents, it
affects aquatic life with each change. These effects
include chemical reaction rates, enzymatic functions,
molecular movements, and molecular exchanges between
membranes within and between the physiological systems and
the organs of an animal.
Chemical reaction rates vary with temperature and generally
increase as the temperature is increased. The solubility of
gases in water varies with temperature. Dissolved oxygen is
decreased by the decay or decomposition of dissolved organic
substances and the decay rate increases as the temperature
of the water increases reaching a maximum at about 30°C
(86°F). The temperature of stream water, even during
summer, is below the optimum for pollution-associated
bacteria. Increasing the water temperature increases the
bacterial multiplication rate when the environment is
favorable and the food supply is abundant.
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Reproduction cycles may be changed significantly by
increased temperature because this function takes place
under restricted temperature ranges. Spawning may not occur
at all because temperatures are too high. Thus, a fish
population may exist in a heated area only by continued
immigration. Disregarding the decreased reproductive
potential, water temperatures need not reach lethal levels
to decimate a species. Temperatures that favor competitors,
predators, parasites, and disease can destroy a species at
levels far below those that are lethal.
Fish food organisms are altered severely when temperatures
approach or exceed 90°F. Predominant algal species change,
primary production is decreased, and bottom associated
organisms may be depleted or altered drastically in numbers
and distribution. Increased water temperatures may cause
aquatic plant nuisances when other environmental factors are
favorable.
Synergistic actions of pollutants are more severe at higher
water temperatures. Given amounts of domestic sewage,
refinery wastes, oils, tars, insecticides, detergents, and
fertilizers more rapidly deplete oxygen in water at higher
temperatures, and the respective toxicities are likewise
increased.
When water temperatures increase, the predominant algal
species may change from diatoms to green algae, and finally
at high temperatures to blue-green algae, because of species
temperature preferentials. Blue-green algae can cause
serious odor problems. The number and distribution of
benthic organisms decreases as water temperatures increase
above 90°F, which is close to the tolerance limit for the
population. This could seriously affect certain fish that
depend on benthic organisms as a food source.
The cost of fish being attracted to heated water in winter
months may be considerable, due to fish mortalities that may
result when the fish return to the cooler water.
Rising temperatures stimulate the decomposition of sludge,
formation of sludge gas, multiplication of saprophytic
bacteria and fungi (particularly in the presence of organic
wastes), and the consumption of oxygen by putrefactive
processes, thus affecting the esthetic value of a water
course.
In general, marine water temperatures do not change as
rapidly or range as widely as those of freshwaters. Marine
and estuarine fishes, therefore, are less tolerant, of
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temperature variation. Although this limited tolerance is
greater in estuarine than in open water marine species,
temperature changes are more important to those fishes in
estuaries and bays than to those in open marine areas,
because of the nursery and replenishment functions of the
estuary that can be adversely affected by extreme
temperature changes.
Acidity and Alkalinity - pH
Although not a specific pollutant, pH is related to the
acidity or alkalinity of a waste water stream. It is not a
linear or direct measure of either, however, it may properly
be used as a surrogate to control both excess acidity and
excess alkalinity in water. The term pH is used to describe
the hydrogen ion - hydroxyl ion balance in water.
Technically, pH is the hydrogen ion concentration or
activity present in a given solution. pH numbers are the
negative loqarithm of the hydrogen ion concentration. A pH
of 7 generally indicates neutrality or a balance between
free hydrogen and free hydroxyl ions. Solutions with a pH
above 7 indicate that the solution is alkaline, while a pH
below 7 indicates that the solution is acid.
Knowledge of the pH of water or waste water is useful in
determining necessary measures for corrosion control,
pollution control, and disinfection. Waters with a pH below
6.0 are corrosive to water works structures, distribution
lines, and household plumbing fixtures and such corrosion
can add constituents to drinking water such as iron,
copper, zinc, cadmium, and lead. Low pH waters not only
tend to dissolve metals from structures and fixtures but
also tend to redissolve or leach metals from sludges and
bottom sediments. The hydrogen ion concentration can affect
the "taste" of the water and at a low pH, water tastes
"sour".
Extremes of pH or rapid pH changes can exert stress
conditions or kill aquatic life outright. Even moderate
changes from "acceptable" criteria limits of pH are
deleterious to some species. The relative toxicity* to
aquatic life of many materials is increased by changes in
the water pH. For example, metalocyanide complexes can
increase a thousand-fold in toxicity with a drop of 1.5 pH
units. Similarly, the toxicity of ammonia is a function of
pH. The bactericidal effect of chlorine in most cases is
less as the pH increases, and it is economically
advantageous to keep the pH close to 7.
*The term toxic or toxicity is used herein in the normal
scientific sense of the word and not as a specialized
term referring to section 307 (a) of the Act.
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Acidity is defined as the quantitative ability of a water to
neutralize hydroxyl ions. It is usually expressed as the
calcium carbonate equivalent of the hydroxyl ions
neutralized. Acidity should not be confused with pH value.
Acidity is the quantity of hydrogen ions which may be
released to react with or neutralize hydroxyl ions while pH
is a measure of the free hydrogen ions in a solution at the
instant the pH measurement is made. A property of many
chemicals, called buffering, may hold hydrogen ions in a
solution from being in the free state and being measured as
pH. The bond of most buffers is rather weak and hydrogen
ions tend to be released from the buffer as needed to
maintain a fixed pH value.
Highly acid waters are corrosive to metals, concrete and
living organisms, exhibiting the pollutional characteristics
outlined above for low pH waters. Depending on buffering
capacity, water may have a higher total acidity at pH values
of 6.0 than other waters with a pH value of U.O.
Alkalinity; Alkalinity is defined as the ability of a water
to neutralize hydrogen ions. It is usually expressed as the
calcium carbonate equivalent of the hydrogen ions
neutralized.
Alkalinity is commonly caused by the presence of carbonates,
bicarbonates, hydroxides and to a lesser extent by borates,
silicates, phophates and organic substances. Because of the
nature of the chemicals causing alkalinity, and the
buffering capacity of carbon dioxide in water, very high pH
values are seldom found in natural waters.
Excess alkalinity as exhibited in a high pH value may make
water corrosive to certain metals, detrimental to most
natural organic materials and toxic to living organisms.
Ammonia is more lethal with a higher pH. The lacrimal fluid
of the human eye has a pH of approximately 7.0 and a
deviation of 0.1 pH unit from the norm may result in eye
irritation for the swimmer. Appreciable irritation will
cause severe pain.
Total Suspended Solids
Suspended solids include both organic and inorganic
materials. The inorganic compounds include sand, silt, and
clay. The organic fraction includes such materials as
grease, oil, tar, and animal and vegetable waste products.
These solids may settle out rapidly and bottom deposits are
often a mixture of both organic and inorganic solids.
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Solids may be suspended in water for a time, and then settle
to the bed of the stream or lake. These solids discharged
with man's wastes may be inert, slowly biodegradable
materials, or rapidly decomposable substances. While in
suspension, they increase the turbidity of the water, reduce
light penetration and impair the photosynthetic activity of
aquatic plants.
Suspended solids in water interfere with many industrial
processes, cause foaming in boilers and incrustations on
equipment exposed to such water, especially as the
temperature rises. They are undesirable in process water
used in the manufacture of steel, in the textile industry,
in laundries, in dyeing, and in cooling systems.
Solids in suspension are aesthetically displeasing. When
they settle to form sludge deposits on the stream or lake
bed, they are often damaging to the life in water. Solids,
when transformed to sludge deposits, may do a variety of
damaging things, including blanketing the stream or lake bed
and thereby destroying the living spaces for those benthic
organisms that would otherwise occupy the habitat. When of
an organic nature, solids use a portion or all of the
dissolved oxygen available in the area. Organic materials
also serve as a food source for sludgeworms and associated
organisms.
Disregarding any toxic effect attributable to substances
leached out by water, suspended solids may kill fish and
shellfish by causing abrasive injuries and by clogging the
gills and respiratory passages of various aquatic fauna.
Indirectly, suspended solids are inimical to aquatic life
because they screen out light, and they promote and maintain
the development of noxious conditions through oxygen
depletion. This results in the killing of fish and fish
food organisms. Suspended solids also reduce the
recreational value of the water.
Turbidity; Turbidity of water is related to the amount of
suspended and colloidal matter contained in the water. It
affects the clearness and penetration of light. The degree
of turbidity is only an expression of one effect of
suspended solids upon the character of the water. Turbidity
can reduce the effecteveness of chlorination and can result
in difficulties in meeting BOD and suspended solids
limitations. Turbidity is an indirect measure of suspended
solids.
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Fluorides
Fluorine is the most reactive of the nonmetals and is never
found free in nature. It is a constituent of fluorite or
fluorspar, calcium fluoride, cryolite, and sodium aluminum
fluoride. Due to their origins, fluorides in high
concentrations are not a common constituent of natural
surface waters; however, they may occur in hazardous
concentrations in ground waters.
Fluoride can be found in plating rinses and in glass etching
rinse waters. Fluorides are also used as a flux in the
manufacture of steel, for preserving wood and mucilages, as
a disinfectant and in insecticides.
Fluorides in sufficient quantities are toxic to humans with
doses of 250 to 450 mg giving severe symptoms and 4.0 grams
causing death. A concentration of 0.5 g/kg of body weight
has been reported as a fatal dosage.
There are numerous articles describing the effects of
fluoride-bearing waters on dental enamel of children; these
studies lead to the generalization that water containing
less than 0.9 to 1.0 mg/1 of fluoride will seldom cause
mottled enamel in children, and for adults, concentrations
less than 3 or 4 mg/1 are not likely to cause endemic
cumulative fluorosis and skeletal effects. Abundant
literature is also available describing the advantages of
maintaining 0.8 to 1.5 mg/1 of fluoride ion in drinking
water to aid in the reduction of dental decay, especially
among children. The recommended maximum levels of fluoride
in public water supply sources range from 1.4 to 2.4 mg/1.
Fluorides may be harmful in certain industries, particularly
those involved in the production of food, beverages,
pharmaceutical, and medicines. Fluorides found in
irrigation waters in high concentrations (up to 360 mg/1)
have caused damage to certain plants exposed to these
waters. Chronic fluoride poisoning of livestock has been
observed in areas where water contained 10 to 15 mg/1
fluoride. Concentrations of 30 - 50 mg/1 of fluoride in the
total ration of dairy cows is considered the upper safe
limit. Fluoride from waters apparently does not accumulate
in soft tissue to a significant degree and it is transferred
to a very small extent into the milk and to a somewhat
greater degree into eggs. Data for fresh water indicate
that fluorides are toxic to fish at concentrations higher
than 1.5 mg/1.
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Phosphorus
Phosphorus occurs in natural waters and in waste waters in
the form of various types of phosphate. These forms are
commonly classified into orthophosphates, condensed
phosphates (pyro-, meta-, and polyphosphorus) , and
organically bound phosphates. These may occur in the
soluble form, in particles of detritus or in the bodies of
aquatic organisms.
The various forms of phosphates find their way into waste
waters from a variety of industrial, residential, and
commercial sources. Small amounts of certain condensed
phosphates are added to some water supplies in the course of
potable water treatment. Large quantities of the same
compounds may be added when the water is used for laundering
or other cleaning since these materials are major
constituents of many commercial cleaning preparations.
Phosphate coating of metals is another major source of
phosphates in certain industrial effluents.
The increasing problem of the growth of algae in streams and
lakes appears to be associated with the increasing presence
of certain dissolved nutrients, chief among which is
phosphorus. Phosphorus is an element which is essential to
the growth of organisms and it can often be the nutrient
that limits the aquatic growth that a body of water can
support. In instances where phosphorous is a growth
limiting nutrient, the discharge of sewage, agricultural
drainage or certain industrial wastes to a receiving water
may stimulate the growth, in nuisance quantities, of
photosynthetic aquatic microorganisms and macroorganisms.
The increase in organic matter production by algae and
plants in a lake undergoing eutrophication has ramifications
throughout the aquatic ecosystem. Greater demand is placed
on the dissolved oxygen in the water as the organic matter
decomposes at the termination of the life cycles. Because
of this process, the deeper waters of the lake may become
entirely depleted of oxygen, thereby, destroying fish
habitats and leading to the elimination of desirable
species. The settling of particulate matter from the
productive upper layers changes the character of the bottom
mud, also leading to the replacement of certain species by
less desirable organisms. Of great importance is the fact
that nutrients inadvertently introduced to a lake are, for
the most part, trapped there and recycled in accelerated
biological processes. Consequently, the damage done to a
lake in a relatively short time requires a many fold in-
crease in time for recovery of the lake.
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When a plant population is stimulated in production and
attains a nuisance status, a large number of associated
liabilities are immediately apparent. Dense populations of
pond weeds make swimming dangerous. Boating and water
skiing and sometimes fishing may be eliminated because of
the mass of vegetation that serves as an physical impediment
to such activities. Plant populations have been associated
with stunted fish populations and with poor fishing. Plant
nuisances emit vile stenches, impart tastes and odors to
water supplies, reduce the efficiency of industrial and
municipal water treatment, impair aesthetic beauty, reduce
or restrict resort trade, lower waterfront property values,
cause skin rashes to man during water contact, and serve as
a desired substrate and breeding ground for flies.
Phosphorus in the elemental form is particularly toxic, and
subject to bioaccumulation in much the same way as mercury.
Colloidal elemental phosphorus will poison marine fish
(causing skin tissue breakdown and discoloration). Also
phosphorus is capable of being concentrated and will
accumulate in organs and soft tissues. Experiments have
shown that marine fish will concentrate phosphorus from
water containing as little as 1 ug/1.
Radioactivity
Ionizing radiation, when absorbed in living tissue in
quantities substantially above that of natural background
levels, is recognized as injurious. It is necessary,
therefore, to prevent excessive levels of radiation from
reaching any living organism humans, fishes, and
invertebrates. Beyond the obvious fact that radioactive
wastes emit ionizing radiation, they are also simile:, in
many respects to other chemical wastes. Man's senses cannot
detect radiation unless it is present in massive amounts.
Plants and animals, to be of any significance in the cycling
of radionuclides in the aquatic environment, must accumulate
the radionuclide, retain it, be eaten by another organism,
and be digestible. However, even if an organism accumulates
and retains a radionuclide and is not eaten before it dies,
the radionuclide will enter the "biological cycle" through
organisms that decompose the dead organic material into its
elemental components. Plants and animals that become
radioactive in this biological cycle can thus pose a health
hazard when eaten by man.
Aquatic life may receive radiation from radionuclides
present in the water and substrate and also from
radionuclides that may accumulate within their tissues.
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Humans can acquire radionuclides through many different
pathways. Among the most important are through drinking
contaminated water, and eating fish and shellfish that have
concentrated nuclides from the water. Where fish or other
fresh or marine products that have accumulated radioactive
materials are used as food by humans, the concentrations of
the nuclides in the water must be further restricted, to
provide assurance that the total intake of radionuclides
from all sources will not exceed the recommended levels.
In order to prevent unacceptable doses of radiation from
reaching humans, fish, and other important organisms,, the
concentrations of radionuclides in water, both fresh and
marine, must be restricted.
Radium-226
Radium-226 is one of the most hazardous radioisotopes of the
uranium decay scheme, when present in water. The human body
preferentially utilizes radium in lieu of calcium when
present in food or drink. Plants and animals concentrate
radium, leading to a multiplier effect up the food web.
Radium-226 decays by alpha emission into radon-222, a radio-
active gas with a half life of 3.8 days. The decay products
of radon-222, in turn, are particulates which can be
adsorbed onto respirable particles of dust. Radon and its
decay products has been implicated in an increased incidence
of lung cancer in those workers exposed to high levels
(Bureau of Mines, 1971). Heating or grinding of phosphate
rock would liberate radon and its decay products to the
surrounding atmosphere.
It is generally agreed that unlike other materials, there is
no threshold value for radiation exposure. Accordingly, the
Federal Radiation Council has repeatedly stated that all
radiochemical material releases are to be kept to the
minimum practicably obtainable. The Council states "It
should be general practice to reduce exposure to radiation,
and positive efforts should be carried out to fulfill the
sense of these recommendations. It is basic that exposure
to radiation should result from a real determination of its
necessity (Federal Radiation Council, I960)."
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METHODS OF ANALYSIS
The methods of analy.sis to be used for quantitative
determination are given in the Federal Register 40 CFR 136
for the following parameters pertinent to this study:
Alkalinity (and Acidity)
fluoride
oxygen demand, chemical
total phosphorus (as P)
solids, total
suspended nonfilterable solids, total
temperature
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SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
The factors and contaminants in non-fertilizer phosphate
chemical process effluent streams have for the most part
been well identified and well known for many years. As a
consequence considerable effort has been expended to correct
or minimize the majority of those which are particularly
detrimental to natural water receiving bodies. Much of this
work has been directed at correcting the source of the
contamination or an in-process improvement rather than an
end-ofpipe type of treatment. A large part of the
motivation for such improvement has been economics - that
is, improved operating efficiency and costs. Such
improvements are just plain good business and justify
capital expenditure required to achieve them.
With an appreciation of the above mentioned facts, the
following criteria were established as bases for
investigating treatment technology.
- A determine the extent of existing waste water control and
treatment technology
- A determine the availability of applicable waste water
control and treatment technology regardless of whether it be
intra-industry transfer technology
- A determine the degree of treatment cost reasonability
Based upon these stated criteria the effort was made to
factually investigate overall treatment technologies dealing
with each of the primary factors and contaminants listed in
Section VI.
Process technology does exist both for containment and for
treatment and reduction of the and contaminants present in
the non-fertilizer phosphate chemical wastewaters as defined
in Section VI. These processes have been divided into two
separate technologies to make them better adaptable to all
the processes. For example, in two of the processes it is
very possible that both technologies need to be used and
therefore be considered as a single treatment method. In
another process however it would be somewhat impractical to
consider using more than one of the technologies although
they are closely inter-related. These two technologies are
therefore described separately even though it is recognized
that they may be essentially integral in some cases.
57
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Containment and Cooling Pond
The above title provides a reasonably precise description of
this technology. The pond retains sufficient wastewater to
meet the high demand for cooling water, particularly for
stack and tail gas scrubbing operations. The pond surface
provides cooling. An indication of the land area used for
this purpose is shown by the fact that survey plant A
utilizes approximately 0.11 hectare (0.26 acre) per daily
production ton. This figure also includes area adequate to
provide collection of excessive rainfall until normal
conditions can be restored.
Acids are collected in the wastewater diring the
manufacturing operations. Insufficient basic substances are
present to neutralize these acids. Lime neutralization is
provided in some manner at each plant to prevent excessive
air pollution by stack or tail gases. Lime may be applied
to the wastewater pumped to the stack, directly to the pond
in a clarifier treating a fraction of the pond recycle
water. The clarifier removes sulfate fluoride and phosphate
as precipitate. The neuralized supernatant fraction is
returned to the pond. One plant manufactures sodium
fluosilicate from the fluoride derived from the distillation
process.
Factors in Pond Construction and Management that Provide
Pond Reliability and Efficiency of Operation
A. Prevention of Dike Failure
Dike failure has been by far the greatest cause of navigable
water contamination from phosphate mining operations. Many
slime pond dike failures have occurred. These have caused
massive contamination of surface waters. Dike failures have
also been reported for containment and cooling ponds.
A potential hazard, therefore, exists from gyp-pond and
recirculation cooling pond dikes, although these are
generally much smaller structures than the slime pond dikes.
Gypsum derived from total manufacturing and waste water
treatment practices is the only dike material readily
available at many sites. It is not an ideal material for
construction of dams. A dam constructed entirely of gypsum
has a uniform and relatively high permeability. Water seeps
through the structure. Saturation is maintained in much of
the dam mass unless special provision is made for drainage
of the toe. Some States maintain a degree of regulation of
dikes. The State of Illinois requires some underdrainage of
gyp-pond dikes at Joliet, Illinois.
58
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A saturated dam is weakened in a number of ways. Piping
occurs in the outer toe. The water in the dam buoys the
structural material, reducing the dikes effective weight.
Granular materials saturated with water will become
momentarily fluid if an earthquake or a shock wave of any
type sets up a tremor.
Hazardous conditions are common in pond dams. The
contractors diagram of a typical dam, supplied with this
study, indicates, no provision of underdrainage. The lack
of specifications that make dikes safe, and/or the lack of
enforcement of these specifications can lead to dike
failures.
A gyp-pond or recirculation pond dike must be constructed in
a manner that maintains effective drainage in the outer half
of the dike. If gypsum is the sole material in the dike, a
farm tile (or other equally effective) underdrainage system
should be provided in the toe of the dike. The tile lines
must be close enough together, located below sufficiently
permeable liner materials and sloped adequately. The tile
field must remain operational and drain effectively
throughout the entire period of waste water containment.
The engineering details of any new gyp-pond utilized for
treating the waste water in the other non-fertilizer
phosphate chemicals segment of the phosphate manufacturing
should be based on sound engineering fundamentals and should
be in compliance with applicable local, State or federal
regulations.
In the event of declining efficiency of a drainage system,
relief wells should be provided to maintain the drainage
function.
Both a relief well system or a farm tile underdrainage
system leading to an underground sump have many advantages
over the open ditches commonly utilized to catch seepage.
The underground systems permit return of seepage without
lowering the outer edge of the dam. This strongly favors
dike safety. The ditch alone provides none of the
underdrainage required to make the dam safe.
An inherent advantage of the underground sump or relief well
system is that seepage can be returned to the lagoon free of
outer slope rain run-off water. A ditch is not essential to
collect this runoff water where a sound underdrain seepage
control system is provided.
Planting the dam slopes with low plants can be utilized to
improve the water balance and to stabilize the dam surface.
59
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Tall plants that reduce wind velocity over the pond surface
must be avoided. Wind is an aid to cooling.
The U.S. Department of Interior, Bureau of Reclamation, book
"Design of Small Dams" (Reference L) presents discussions
and diagrams of toe draining systems, with a horizontal
drainage blanket, an underground drainage trench, and an
underground pipe conduit leading to an outfall. This system
can readily replace the open seepage interceptive ditch in
common use. The intercepted seepage can be pumped back to
the pond from an underground sump. This system does not
return runoff from outer slopes to the lagoon.
The reliability of a properly installed underground drainage
system is extremely high. A soundly designed system assures
a safe dam for its full service life.
If some local factor introduces a reliability problem two
control measures should be considered:
1. Install a conduit to the top altitude of the drain
system for periodic drain pipe flushing to prevent
plugging.
2. Install a vertical permeable pipe at the center of the
dam, through which the phreatic line may be measured.
The design engineer should specify the maximum safe
height of this phreatic line for each dam. Various
instruments can be installed in the dike to monitor the
height of the phreatic line. These must be of fully
established reliability.
B. Control of Seepage
A pond, to be acceptable for use in waste water treatment,
must have an interceptor system that collects and returns
seepage, or should be provided with a liner that prevents
significant percolation, and that blocks flow to groundwater
through underground channels. Furthermore, any waste water
seepage must have no dissolving action on underlying layers.
It is particularly important to prevent acidic waste water
seepage through limestone formations. Some liming may be
required, particularly at start-up, to protect limestone
layers, to provide sediment for plugging of the bottom
liner, and to prevent seepage of fluoride, radium-226 and
phosphate components.
Relief wells, underdrainage or other provision must be made
to prevent upflow of groundwater into the lagoon. Upflow
into a lagoon normally breaches the liner and permits flow
60
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of waste water through existent channels to groundwater when
lagoon hydrostatic pressure exceeds the groundwater
pressure.
Groundwater monitoring by ifieans of wells in the percolation
area should be installed whenever the lagoon is provided
with a liner of questionable impermeability. The addition
of lime to bottom sediments in lagoons will lead to
neutralization of waste water seeping into ground water.
The use of lime will also provide sedimentary conditions
that tend to block seepage.
The liming of pond water can be utilized to aid both air
pollution control and to reduce loss of waste water
pollutants by seepage.
C. Deposits of Objectionable Substances at
Phosphate Manufacturing Plants
Various deposits of objectionable waste water components
occur in ponds or landfill areas. Examples of these are
calcium fluoride, radium-226, arsenic and sulfide. Local
State and EPA authorities with jurisdiction over this
landfill problem should be notified of the deposits and the
control measures required should then be established. It is
vital that percolating water does not carry these substances
into ground water or into surface waters.
D. Ponds in Regions with Severe Cold Seasons
The cooling problem for a reuse and cooling pond varies
drastically from summer to winter seasons in cold climates.
It is essential to install conduits underground, or
otherwise protect from freezing. Provision must be made for
isolation of a pond with a limited surface area for winter
operation. The heat discharged to the pond in normal
operation will then prevent troublesome freezing incidents.
The winter pond must be deep enough to remain operable after
a plant shutdown. A defluorinated rock plant has been
operating a recycle pond in Montana. No difficulty has been
reported.
National standards are not being proposed for recirculation
and reuse ponds. Some State and local authorities have set
standards. Monitoring should cover the factors that control
loss of waste water to surface and ground waters, and local
authorities should be notified of conditions threatening
navigable and ground waters with pollution.
61
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Contaminated (Pond) Water Treatment
This technology is identical to that treatment technology
designated as gypsum pond (contaminated) water treatment in
the phosphate fertilizer section of the development document
for the Basic Fertilizer Chemicals Manufacturing Industry.
The Containment and Cooling Pond technology described above
is intended to function as a no discharge closed loop system
the majority of the time. This "no discharge" situation is
however dependent upon the quantity of rainfall it can
accept before its water storage capacity is exceeded. Once
the storage area approaches capacity it is necessary to
begin treating the contaminated water for subsequent
discharge to natural drainage areas. Similarly, in those
processes in which a containment pond is impractical it may
be necessary to continuously treat the contaminated process
effluent water. This technology in part or as a whole is
capable of treating the contaminated effluent of either the
containment pond or the process effluent streams.
Process Description
Contaminated water can be treated effectively for control of
the pollution parameters identified in Section VI, namely
suspended solids, pH, phosphate, radium-226, and fluorides.
The treatment described is by means of either single or two-
stage lime neutralization procedure. In the Sodium
Phosphate process there are indications that only single
liming is required for removal of the impurities.
Normally two stages of liming or neutralization are
necessary to effect an efficient removal of the fluoride and
phosphate contaminants. Fluorides are present in the water
principally as fluosilicic acid with small amounts of
soluble salts as sodium and potassium fluosilicates and
hydrofluoric acid. Phosphorus is present principally as
orthophosphoric acid with some minor amounts of soluble
calcium orthophosphates in the conventional wet phosphoric
acid production process. Polyphosphates that require
special pretreatment prior to lime sedimentation may be
present in lagoons accepting waste water from defluorination
processes, and from the manufacture of defluorinated (poly)
phosphates.
The first treatment stage provides sufficient neutralization
to raise the contaminated water containing up to 9,000 mg/1
F and up to 6,500 mg/1 P from pH 1-2 to pH 3.5-4.0. The
resultant treatment effectiveness is, to a significant
degree, dependent upon the mixing efficiency at the point of
62
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lime addition and the constancy of the pH control. At a pH
level of 3.5 to U.O, the fluorides will precipitate
principally as calcium fluoride (CaF2_) as shown by the
following chemical equation.
H2SiF£ +
Fluosilicic
Acid
3 CaO + H20 = 3 CaF2 + 2 H20
Lime
Water
Calcium
Water
This mixture is then held in a quiescent area to
particulate CaF2 to settle.
Silica
allow the
Equipment used for neutralization ranges from crude manual
distribution of lime with localized agitation to a well
engineered lime control system with a compartmented mixer.
Similarly the quiescent areas range from a pond to a
controlled, settlina rate thickener or settler. The
partially neutralized water following separation from the
CaF2_r (pH 3.5-4.0) now contains 30-60 mg/1 F and up to 5,500
mg/1 P. This water is again treated with lime sufficient to
increase the pH level to 6.0 or above. At this pH level
calcium compounds, primarily dicalcium phosphate plus
additional quantities of CaF2 precipitate from solution.
The primary reactions are shown by the following chemical
equation:
2 H3P04 +
Phosphoric
Acid
Ca(H2POj*) 2
Monocalcium
Phosphate
CaO +
Lime
CaO
Lime
H20
Water
H20
Water
Ca (E2PQI4) 2 + 2 H_20
Monocalcium Water
Phosphate
2CaHPO4_ + 2 H20
Dicalcium Water
Phosphate
As before, this mixture is retained in a quiescent area to
allow the CaHPOJ4 and minor amounts of CaF2_ to settle.
After settlement, the clear, neutralized water will contain
15-30 mg/1 F and 30-60 mg/1 P at a pH of 6-8. The reduction
of the P value is strongly dependent upon the final pH level
and quality of the neutralization facilities, particularly
mixing efficiency. Neutralization to pH levels of 9-11 will
reduce P values to 15-30 mg/1 or less. Figure VII-1 shows a
sketch of a well designed "double lime" treatment facility.
Plants B, C and D all practice some degree of liming.
63
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TO GYPSUM POND
CALCIUM PHOSPHATE
POND
CONTAMINATED (POND) WATER TREATMENT
TO RIVER OR
PROCESS UNITS
FIGURE VII-1
-------
A number of pollutants may cause interference with lime
precipitation. Silicates are normal components of most
recycle ponds and exert an interfering action through
formation of fluosilicates. Some boron componds will
complex fluorine and interfere with precipitation. Borax
has a chelating action on calcium ion and therefore, like
many other chelating agents, has an interfering action on
lime precipitation. Spurious contaminants that interfere
with lime precipitation must be excluded from recycle ponds
if satisfactory lime precipitation is to be maintained.
Some special precautions are essential at a plant producing
sodium phosphates. All meta, tetra, pyro and polyphosphate
waste water in spills should be diverted to the reuse pond.
These phosphates will not precipitate satisfactorily in the
lime treatment process and will interfere with the removal
of fluoride and suspended solids.
Polyphosphate in waste water will exert a desirable anti-
fouling action if diverted to the cooling water stream from
the reuse lagoon. Furthermore, the compound will hydrolyze
and precipitate in the lagoon.
Domestic waste, unless completely bio-oxidized, has
undesirable effects in sodium phosphate plant effluent. The
amino acids and other organic components interfere with both
precipitation and flocculation. The high calcium level of
the recycle pond is lacking in the waste water stream from
the sodium phosphate plant. Lime and/or calcium salts may
be required for acceptable removal of P and F pollutants.
Adequate precipitant reagent use must be supported by
effective clarification for control of F, P and SS.
In some circumstances it may be desirable to strip carbon
dioxide from the waste stream before lime treatment so that
carbonate does not compete with phosphate in the
precipitation reaction.
The sodium phosphates subcategory manufacturing process
utilizes a series of salting out processes for separating
various crystallized products. The resultant waste water
streams contain a variety of contaminants that cannot be
recycled in the process without degenerating product
quality. The manufacturing processes isolate some of the
potential waste water pollutants from the waste stream.
Sodium silicofluoride is precipitated out and sold as a
byproduct; this process disposes of most of the troublesome
fluoride problem. Radium 226 is segregated into various
sediment fractions. Arsenic is separated as sulfide
precipitate. Sedimentation occurs in the waste streams from
65
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the sodium phosphate processes and the sediments are removed
by clarification. The technical details of these processes
have not been fully disclosed by the manufacturer.
A recirculation pond is available on the site for handling
difficult waste water streams to the same extent that this
lagoon system is available for defluorinated rock and acid
waste water.
Modified forms of phosphate create a unique treatment
problem at defluorination plants. Phosphoric acid and/or
phosphate salts undergo polymerization and molecular
rearrangement reactions when subjected to severe dehydration
treatment. The acid defluorination treatments applied are
predominantly operated with application of heat and a gas
stripping action. These heating and/or stripping actions
induce a substantial degree of molecular conversion in the
defluorinated acids. The conversion is particularly high in
super-acid grades concentrated to a high P.205 content.
Likewise, the high temperatures applied for rock
defluorination convert the raw orthophosphate rock to
polyphosphates.
These modified phosphates differ sharply from
orthophosphates in solubility. Calcium orthophosphates have
extremely low solubility in moderately alkaline solutions;
the calcium salts of the modified phosphates have
appreciable solubility. In fact, these modified phosphates
are applied extensively as chelating agents to combat
calcium induced hardness. These modified phosphates are
relatively stable at ambient temperatures. The half life
varies from compound to compound and is poorly defined; this
half life is commonly taken to be about 2 days in acidic
waters, but is several weeks in neutral or alkaline waters.
These modified phosphates enter the process waste water from
various sources. Stack washing introduces some dust from
rock defluorination. Spray carryover to barometric
condenser water is a common source of contamination in acid
defluorination. Spills and leaks carry polyphosphates into
waste water in all the subcategories. Rain run-off from
drying, packaging, loading and shipping areas carry these
modified phosphates into the waste water stream.
It is vitally important that waste water bearing these
modified phosphates be excluded from streams flowing to lime
treatment facilities; this is especially objectionable
without impoundment. The calcium salts of these modified
phosphates are much more soluble than the calcium
orthophosphate salts. Satisfactory phosphate precipitation
66
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will not occur on lime treatment. Furthermore,
polyphosphates exert an objectionable interference action on
clarification processes. And still further, the soluble
calcium salts of molecular species other than orthophosphate
act as individual agejits in the calcium precipitation
process. Thus, a system with only orthophosphate will
remain saturated with calcium orthophosphate. The mixed
system will remain saturated with calcium orthophosphate and
with each component calcium phosphate. The sum of the
phosphate components in solution will be higher than the
orthophosphate component alone.
Where waste water contamination does occur with these
modified phosphates, the resultant waste streams, should be
directed to a special holding pond, along with acidic wastes
that speed hydrolysis. Completing of hydrolysis can be
promoted further by discharge into the contaminated water
recirculation pond. The modified phosphates continue the
hydrolysis to orthophosphate in the recirculation lagoon.
This factor adds another plus value to the desirability of
the recirculation and reuse lagoon at a phosphate facility
with defluorination processes. The holding is especially
beneficial at the typical low pH levels prevailing in
typical contaminated water ponds. Acidity hastens
hydrolysis to the orthophosphate form.
A unique condition prevails in the waste water discharge
from the single plant producing sodium phosphates. This
stream also contains the domestic waste discharge from the
septic tanks' accepting the plant's domestic sewage. An
efficient aerobic bio-oxidation step applied to this waste
water would destroy most of the organic substances that
interfere with sedimentation; furthermore, this bio-
oxidation process will catalyze the hydrolysis of
polyphosphates present in the waste water to orthophosphate.
Bio-oxidation may be the most practicable means of
converting any polyphosphates present to orthophosphate in
this situation. The waste stream is neutral; hydrolysis of
polyphosphates will be extremely slow unless bio-catalytic
action is induced in the system. Many microorganisms
produce enzymes that catalyze the hydrolysis of
polyphosphates. Reference P brings out the observation that
no problem was encountered in precipitating phosphates in
domestic waste water following bio-oxidation of the waste
water.
It must be recognized that pH alone does not indicate the
total effectiveness of the precipitating reagent. The
calcium content in the pond water will also be a factor and
will vary widely. The sulfate ion competes for the calcium
67
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ion; a high sulfate content will tend to reduce the calcium
content of a pond and create a condition relatively
unfavorable for fluoride and phosphate precipitation. The
pH change induced by lime addition, gives a general
indication of the precipitation potential in the system. A
pH rise from lime addition is accompanied by a rise in
soluble calcium content. In normal circumstances, lime to
pH 6.0 will be adequate for precipitating fluorine and
phosphate to meet required limitations, but lime will have
to be added, as required, if fluoride and phosphate
limitations are not met.
Soluble iron and aluminum compounds are present at high
concentrations in many ponds. The iron and aluminum cations
exert a strong influence on phosphate precipitation.
Strong winds interfere with sedimentation in lagoons. A
covered terminal sedimentation basin, or a covered final
segment of a sedimentation basin will be indispensable for
attaining satisfactory suspended solids removal under many
conditions. A cover is particularly beneficial in periods
of cold weather. Temperature inversion currents cause
severe disturbance of sedimentation in open basins in cold
weather. Inlet and outlet arrangements are critical.
Poorly designed inlets and outlets permit excessive short
circuiting. Arrangements that direct flow tangentially are
vastly superior to arrangements that direct flow from inlet
toward outlet structure.
Monitoring Treatment After Rainfall Breaches the
Required Freeboard of a Lagoon
The authority monitoring a lagoon should specify a treatment
rate for the waste water breaching the required freeboard
high enough to restore the required freeboard in a
reasonable time period. If treatment is delayed, or
conducted at an unreasonably slow rate, overflow will occur
from rains considerably below the heaviest expected rainfall
in a 10 or 25 year period.
Personnel concerned with monitoring recirculation and
cooling water lagoons may find it prudent to define several
stages of freeboard that relate to control of surge capacity
and to hazard of breaching the lagoons capacity:
A. The spillway level capacity, as established by the
elevation of the spillway, should be clearly
defined.
68
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B. A crest should be provided around the pond above
the spillway elevation. This is essential to
prevent breaching of the structure by wave action
in windy weather. The height of this crest should
be related to wind problems at the lagoon site.
C. A maximum permissible operating level to avoid
breaching in periods of excessive rainfall should
be established. This is now set by the regulation.
Operational experience should be recorded to
provide data for reconsideration if excessive
breaching is noted in operation under the
promulgated regulations.
Control of Unusual Discharges to Pond
Monitoring authorities should require a report on all waste
water streams discharged to the recirculation and reuse
pond. Problems may arise at plants discharging waste water
from processes other than phosphate manufacturing or
fertilizer phosphate production. Ponds should also be
managed and located in a manner that limits ammonia and
organic compound intrusion.
The recirculation and reuse pond will have considerable
capacity to absorb noncontact cooling water that has become
contaminated by leaks and process waste waters from
ancillary phosphate manufacturing operations at most sites;
however, the situation at a point source should be monitored
to make certain that the point source is not utilizing the
pond as a device for evading regulations on waste water
discharges from unrelated manufacturing operations.
Many objectionable metals are kept under control by the
sedimentation processes in the pond and by the terminal lime
treatment process. The presence of ammonia and of some
organic compounds interfere seriously with these treatment
processes. Particular care should be taken around plants
producing ammonia and other nitrogenous fertilizers; drying
towers and other facilities losing ammonia gas to the
atmosphere are particularly troublesome sources of
contamination. Domestic wastes interfere with metal
precipitation processes and with flocculation and
clarification processes.
The pH range was extended from the proposed 9.0 top limit to
9.^ because of the difficulty experienced at some plants in
meeting the suspended solids, phosphate and fluoride
limitations on liming to the proposed 9.C pH limit.
69
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No suspended solids limitation was set in discharge of
treated contaminated non-process wastewater. The major
volume is coolinq water with no significant content of
supsended solids.
70
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SECTION VIII
COST, ENERGY AND NON-WATER QUALITY ASPECT
General
The costs - capital and operating - have been estimated for
the two treatment technologies described in Section VII.
These costs are given as August 1971 dollar values. In the
case of the costs indicated for Containment and Cooling Pond
technology, there is additional explanation made on what
they represent and how they might be used. The costs
indicated for the Contaminated (Pond) Water Treatment
technology are based on a specific treatment capacity such
as would be found at a moderate size production unit. The
following paragraphs provide identification of the cost
elements used in this section and indicated on Table VIII-1.
Cost Elements
Investment
This is the capital cost associated with the engineering;
site preparation; construction and installation; and such
other costs required to place the technology in operation.
It does not include production loss or profits loss that may
be encountered from tying the new facilities into the
existing plant operations.
Interest
This cost is based on the assumption that the capital
expenditure was borrowed at a 7.5% annual interest rate.
Depr ec iati on
The nature and service life expected of this type equipment
were the bases for selection of an assumed ten year straight
line depreciation.
Operating and Maintenance Costs
The items included in this cost element are operating
supplies, replacement parts, insurance, taxes, operating
labor and maintenance labor.
Energy
71
-------
This item is the power costs to operate the mechanical
equipment. Electrical energy is assumed at the cost of 10
mils per KWH.
Total Annual Costs
An accumulation of the various cost items described above.
Installation and Operation of Technologies
Containment and Cooling Pond
The cost of this technology is difficult to estimate due to
the need of a specific design for each individual plant.
Pond size is a function of many items including the water
temperature (cooling) required for process, the economics of
land availability, provision for rainfall, and geographical
location. The indicated investment cost is that to
establish a 10' high dike around one (1) acre. This cost
also assumes that the dike will be established from earth at
the site and strictly by large earth-moving equipment - no
transportation of earth to the site. Cost of earth moving
has been estimated at $1.50 per cubic yard.
It can be stated that a minimum containment and cooling pond
for a moderate size plant would be 10 - 20 acres.
Construction time is estimated at 80 hours per acre.
There would be no interruption of plant operation during
construction.
Contaminated (Pond) Water Treatment
This is the same technology and costs estimated for Pond
Water Treatment in the phosphate fertilizer section of the
Basic Fertilizer Chemicals Survey.
Time required for engineering, procurement, and construction
is 15 - 18 months.
There would be no interruption of plant operation during
construction.
Start-up and initial operation would require approximately
24 hours of continuous operation to establish stabilized
conditions.
Table VIII-1 cites 1971 cost figures derived from the
oriainal contract study. These figures have been expanded
72
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73
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TABLE VIII-2
SUMMARIZED ESTIMATED WASTEWATER TREATMENT COSTS OF PHOSPHATE MANUFACTURING PLANTS
(Costs Per Model Plant)*
Subcategory and Plant Size
Defluorinated Phosphate Rock
Medium (175,000 ton/yr)
Large (310,000 ton/yr)
Defluorinated Phosphoric Acid
Snail (193,000 ton/yr)
Large (720,000 ton/yr)
Sodium Phosphates
Average (140,000 ton/yr)
Capital Costs
77,000
100,000
574,000
1,249,000
548,000
BPCTCA
,$ O&M Costs, $
7,200
10,840
120,900
431,700
120,100
BATEA and
Capital Costs, $
155,000
220,000
(c)
(c)
(c)
NSPS W
O&M Costs, $
9,600
11,300
(c)
(c)
(c)
(b)
(a) Incremental costs after achieving BPCTCA
(b) Does not include taxes, interest, or depreciation
(c) No additional costs to meet BATEA
* Derived from Reference T. Investment costs are on a June, 1973 basis
and operation and maintenance costs on a November, 1973 basis.
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to cover the entire industry in the Economic Analysis of
Proposed Effluent Guidelines, EPA, September, 197U and
revised in the economic analysis study conducted for
promulgation. Table VIII-2 presents an independent study
result derived from Reference T.
No cost estimate was made for BAT practice for the Sodium
Phosphates Subcategory. It was the opinion of the review
committee that the BAT standards can be easily achieved.
The plant was building an expanded lagoon system for the wet
process phosphoric acid plant and for hydrofluoric acid
manufacture. This lagoon will be available to handle
difficult streams from the sodium phosphate plant. Cost
increase from BPT to BAT should be less than five percent.
The 1.3 area factor originally utilized in calculating
rainfall accumulation in lagoons is no longer utilized.
This factor did not appear in the contractor's original cost
estimates. There is no reason to include it now. There is
no change in wastewater flow due to the change in the
guidelines.
Our contractor did not include seepage interceptor ditches
or underdrainage systems for lagoons. These costs need not
be added. The problem is State and non-point source and not
handled by Effluent Guidelines.
Air Pollution Control
Air pollution control poses a serious problem in the
industry, particularly in the defluorinated phosphate rock
subcategory. The fluoride expelled from the rock on heating
would cause an extremely serious air pollution situation
without the stack scrubbing applied in the industry. The
EPA air pollution control authorities are initiating studies
to determine the status of the air pollution problem, and
the relationship to the water pollution problem.
Defluorinated phosphate rock plants and submerged combustion
defluorinated phosphoric plants lose much water by
evaporation, and have no normal need to discharge wastewater
from their recirculation and cooling ponds. However, all of
these must lime treat at some place to control the pH to
prevent excessive air emission of fluoride.
Information must also be gathered on radon-222 and the
radioactive breakdown solid substances derived from radon-
222. Radon-222 is an inert gas with a very short half life.
Exposure of human beings to these radioactive products must
be held to safe levels. Hopefully, more definite
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information will soon be available on how to deal with this
problem. The use of solid wastes, particularly gypsum, for
home construction is inadvisable unless found to be free of
radioactive component hazard.
Solid Wastes
Many solids residues are left as solid wastes.
The proper management of solid wastes resulting from air
pollution control systems must be practiced. Air pollution
control technologies generate many different amounts and
types of solid wastes and liquid concentrates through the
removal of pollutants from air emissions. These substances
vary greatly in their chemical and physical composition and
may be either hazardous or non-hazardous. A variety of
techniques may be employed to dispose of these substances
depending on the degree of hazard.
If thermal processing is the choice for disposal, provisions
must be made to ensure no re-entry of the pollutants into
the atmosphere. Consideration should also be given to
recovery of materials of value in the wastes.
For those waste materials considered to be non-hazardous
where land disposal is the choice for disposal, practices
similar to proper sanitary landfill technology may be
followed. The principles set forth in the SPA's Land
Disposal of Solid Wastes Guidelines (40 CFR 241) may be used
as guidance for acceptable land disposal techniques.
For those waste materials considered to be hazardous,
disposal may require special precautions. In order to
ensure long-term protection of public health and the
environment, special preparations and pretreatment may be
required prior to disposal. If land disposal is to be
practiced, these sites must not allow movement of pollutants
such as fluoride and radium-226 to either ground or surface
water. Sites should be selected that have natural soil and
geological conditions to prevent such contamination or, if
such conditions do not exist, artificial means (e.g.,
liners) should be provided to ensure long-term protection of
the environment from hazardous materials. Where
appropriate, the location of solid hazardous materials
disposal sites should be permanently recorded in the
appropriate office of the legal jurisdiction in which the
site is located.
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Pretreatment
No manufacturer in these subcategories is known to discharge
wastewater to a publicly owned treatment plant.
Pretreatment standards have been reserved for the present
time because of ongoing studies with incomplete
administrative decisions.
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SECTION IX
BEST PRACTICABLE CONTROL TECHNOLOGY
CURRENTLY AVAILABLE
Int.roduct.ion
The effluent limitations which must be achieved by July 1,
1977 are based on the degree of effluent reduction
attainable through the application of the best practicable
control technology currently available. For the non-
fertilizer phosphate chemicals manufacturing industry, this
level of technology is based on the best existing
performance by exemplary plants of various sizes, ages and
chemical processes within each of the industry's categories.
In some cases where no truly exemplary plants were surveyed,
this level of technology is based upon state-of-the-art unit
operations commonly employed in the chemical industry.
Best practicable control technologies currently available in
the non-fertilizer phosphate chemicals industry involve both
in-process techniques and end-of-process treatment.
Based upon the information contained in Section III through
VIII of this report, the following determinations were made
on the degree of effluent reduction attainable by
application of the best practicable control technology
currently available in the individual process of the non-
fertilizer phosphate chemical industry. Each process is
presented separately in the following paragraphs.
Specialized Definitions
(a) Except as provided below, the general definitions,
abbreviations and methods of analysis set forth in 40 CFR
U01 shall apply to this subpart.
(b) The term "process waste water" means any water
which, during manufacturing or processing, comes into direct
contact with or results from the production or use of any
raw material, intermediate product, finished product, by-
product, or waste product. The term "process waste water"
does not include contaminated non-process waste water, as
defined below.
(c) The term, "contaminated non-process wastewater"
shall mean any water including precipitation runoff which,
during manufacturing or processing, comes into incidental
contact with any raw material, intermediate product,
finished product, by-product or waste product by means of
(1) precipitation runoff (2) accidental spills (3)
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accidental leaks caused by the failure of process equipment
and which are repaired or the discharge of pollutants
therefrom contained or terminated within the shortest
reasonable time which shall not exceed 24 hours after
discovery or when discovery should reasonably have been
made, whichever is earliest, and (4) discharges from safety
showers and related personal safety equipment, and from
equipment washings for the purpose of safe entry, inspection
and maintenance; provided that all reasonable measures have
been taken to prevent, reduce, eliminate and control to the
maximum extent feasible such contact and provided further
that all reasonable measures have been taken that will
mitigate the effects of such contact once it has occurred.
(d) The term "ten year 24 hour rainfall event" shall
mean the maximum precipitation event with a probable
recurrence interval of once in 10 years as defined by the
National Weather Service in technical paper no. 40,
"Rainfall Frequency Atlas of the United States," May, 1961,
and subsequent amendments or equivalent regional or State
rainfall probability information developed therefrom.
(e) The term "25 year 24 hour rainfall event" shall
mean the maximum precipitation event with a probable
recurrence interval of once in 25 years as defined by the
National weather Service in technical paper no. 40,
"Rainfall Frequency Atlas of the United States," May, 1961,
and subsequent amendments or equivalent regional or State
rainfall probability information developed therefrom.
(a), above, applies to all three subcategories; (b), (c),
(d) and (e) apply to the defluoririated phosphate rock and
the defluorinated phosphoric acid subcategories.
Subpart D - Defluorinated Phosphate Rock Subcategory
The provisions of this subpart are applicable to discharges
resulting from the defluorination of phosphate rock by
application of high temperature treatment along with wet
process phosphoric acid, silica and other reagents.
In establishing the limitations set forth in this section,
EPA took into account all information it was able to
collect, develop and solicit with respect to factors (such
as age and size of plant, raw materials, manufacturing
processes, products produced, treatment technology
available, energy requirements and costs) which can affect
the industry subcategorization and effluent levels
established. It is, however, possible that data which would
affect these limitations have not been available and, as a
result, these limitations should be adjusted for certain
plants in this industry. An individual discharger or other
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interested person may submit evidence to the Regional
Administrator (or to the State, if the State has the
authority to issue NPDES permits) that factors relating to
the equipment or facilities involved, the process applied,
or other such factors related to such discharger are
fundamentally different from the factors considered in the
establishment of the guidelines. On the basis of such
evidence or other available information, the Regional
Administrator (or the State) will make a written finding
that such factors are or are not fundamentally different for
that facility compared to those specified in the Development
Document. If such fundamentally different factors are found
to exist, the Regional Administrator or the State shall
establish for the discharger effluent limitations in the
NPDES permit either more or less stringent than the
limitations established herein, to the extent dictated by
such fundamentally different factors. Such limitations must
be approved by the Administrator of the Environmental
Protection Agency. The Administrator may approve or
disapprove such limitations, specify other limitations, or
initiate proceedings to revise these regulations.
The following limitations establish the quantity or quality
of pollutants or pollutant properties, which may be
discharged by a point source subject to the provisions of
this subpart after application of the best practicable
control technology currently available.
(a) Subject to the provisions of paragraphs (b) , (c)
and (d) below:
The following limitations establish the quantity or
quality of pollutants or pollutant properties, controlled by
this section, which may be discharged by a point source
subject to the provisions of this subpart after application
of the best practicable control technology currently
available: there shall be no discharge of process wastewater
pollutants to navigable waters.
(b) Process waste water pollutants from a cooling water
recirculation system designed, constructed and operated to
maintain a surge capacity equal to the runoff from the 10-
year, 24-hour rainfall event may be discharged, after
treatment to the standards set forth in subparagraph (c)
below, whenever chornic or catastrophic precipitation events
cause the water level in the pond to rise into the surge
capacity. Process waste water must be treated and
discharged whenever the water level equals or exceeds the
mid point of the surge capacity.
(c) The concentration of pollutants discharged in
process wastewater pursuant to the limitations of paragraph
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(b) shall not exceed the values listed in the following
table:
Average of Daily
Values for 30
Effluent Maximum for Consecutive Days
Character!stic Any 1 Day Shall Not Exceed
mg/1
Total Phosphorus(P) 105 35
Fluoride 75 25
TSS 150 50
pH Within the range 6.0 to 9.5
The total suspended solid limitation set forth in this
paragraph shall be waived for process wastewater from a
calcium sulfate storage pile runoff facility, operated
separately or in combination with a water recirculation
system, which is chemically treated and then clarified or
settled to meet the other pollutant limitations set forth in
this paragraph.
(d) The concentration of pollutants discharged in
contaminated non-process wastewater shall not exceed the
values listed in the following table:
Average of Daily
Values for 30
Effluent Maximum for Consecutive Days
Characteristic Any 1 Day Shall Not Exceed
mg/1
Total Phosphorus(P) 105 35
Fluoride 75 . 25
pH Within the range 6.C to 9.5
Rationale for Best Practicable Control Technology
Currently Available
The criteria used for selection of the technology was
information obtained at three of the four total operating
plants in the U.S. Two of the three plants (survey plants A
and B) have the Containment and Cooling Pond Technology in
service and to date have never found it necessary to treat
or discharge water to navigable waters. Survey Plant C
stated plans of installing this technology in the near
future.
The proposed limitations are based on composite (not grab)
sampling and years of historical effluent data. These
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limitations represent values which are being achieved by the
better exemplary plants surveyed.
The volume of process waste water that may be discharged is
determined by the rainfall-evaporation circumstances at the
site, and by the definitions and regulations pertaining to
the structure of the recirculation and reuse pond. Process
waste water discharge is not necessary at some sites.
Plants that discharge process waste water normally do this
only in periods of heavy rainfall.
Discharged effluent must be lime treated. This is a
relatively costly operation. Diligent water conservation
and reuse practices have proven to be the most economical
means to handle the waste water problem.
Subpart E - Defluorinated Phosphoric Acid Subcategory
The provisions of this subpart are applicable to discharges
resulting from the defluorination of phosphoric acid. Wet
process phosphoric acid is dehydrated by application of heat
and other processing aids such as vacuum and air stripping.
The acid is concentrated up to 70-73 percent P.2O5 in the
defluorination process.
The technology described as Containment and Cooling Pond is
defined as the best practicable control technology currently
available. This technology confines all process waste
waters to the plant area. Recirculation of these
contaminated process waters to the process together with
good water management practices essentially eliminate the
need for treatment or discharge of treated contaminated
process water to navigable waters. In the event of a need
for emergency type discharge, then the Contaminated (Pond)
Water treatment technology or a facsimile of it would also
be indicated.
The following limitations establish the quantity or
quality of pollutants or pollutant properties, which may be
discharged by a point source subject to the provisions of
this subpart after application of the best practicable
control technology currently available:
(a) Subject to the provisions of paragraphs (b) , (c)
and (d) below:
The following limitations establish the quantity or
quality of pollutants or pollutant properties, controlled by
this section, which may be discharged by a point source
subject to the provisions of this subpart after application
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of the best practicable control technology currently
available: there shall be no discharge of process wastewater
pollutants to navigable waters.
(b) Process waste water pollutants from a cooling water
recirculation system designed, constructed and operated to
maintain a surge capacity equal to the runoff from the 10-
year, 24-hour rainfall event may be discharged, after
treatment to the standards set forth in subparagraph (c)
below, whenever chornic or catastrophic precipitation events
cause the water level in the pond to rise into the surge
capacity. Process waste water must be treated . and
discharged whenever the water level equals or exceeds the
mid point of the surge capacity.
(c) The concentration of pollutants discharged in
process wastewater pursuant to the limitations of paragraph
(b) shall not exceed the values listed in the following
table:
Average of Daily
Values for 30
Effluent Maximum for Consecutive Days
Characteri stic Any 1 Day Shall Not Exceed
mg/1
Total Phosphorus(P) 105 35
Fluoride 75 25
TSS 150 50
pH Within the range 6.0 to 9.5
The total suspended solid limitation set forth in this
paragraph shall be waived for process wastewater from a
calcium sulfate storage pile runoff facility, operated
separately or in combination with a water recirculation
system, which is chemically treated and then clarified or
settled to meet the other pollutant limitations set forth in
this paragraph.
(d) The concentration of pollutants discharged in
contaminated non-process wastewater shall not exceed the
values listed in the following table:
Average of Daily
Values for 30
Effluent Maximum for Consecutive Days
Characteristic Any 1 Day Shall Not Exceed
mg/1
Total Phosphorus(P) 105 35
Fluoride 75 25
pH Within the range 6.0 to 9.5
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Rationale for Best Practicable Control Technology
Currently Available
The criteria used for selection of the technology was
information obtained at three of the four total operating
plants in the U.S. Two of the three plants (survey plants A
and B) have the Containment and Cooling Pond Technology in
service and to date have never found it necessary to treat
or discharge water to navigable waters. Survey Plant C
stated plans of installing this technology in the near
future.
The proposed limitations are based on composite (not grab)
sampling and years of historical effluent data. These
limitations represent values which are being achieved by the
better exemplary plants surveyed.
The volume of process waste water that may be discharged is
determined by the rainfall-evaporation circumstances at the
site, and by the definitions and regulations pertaining to
the structure of the recirculation and reuse pond. Process
waste water discharge is not necessary at some sites.
Plants that discharge process waste water normally do this
only in periods of heavy rainfall.
Discharged effluent must be lime treated. This is a
relatively costly operation. Diligent water conservation
and reuse practices have proven to be the most economical
means to handle the waste water problem.
Subpart F - Sodium Phosphates Subcategory
The provisions of this subpart are applicable to discharges
resulting from the manufacture of purified sodium phosphates
from wet process phosphoric acid.
The technology described as Contaminated (Pond) Water
Treatment is defined as the best practicable control
technology currently available, and/or in-process technology
- whichever will achieve the same results. Process waste
water is also continuously treated and discharged to
navigable waters. A lagoon recirculation system is in use
for treatment of the process waste water from production of
the raw product acid required for sodium phosphates
manufacture, and can be utilized for disposal of troublesome
waste water streams.
The following limitations establish the quantity or
quality of pollutants or pollutant properties, controlled by
this section, which may be discharged by a point source
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subject to the provisions of this subpart after application
of the best practicable control technology currently
available:
Effluent Effluent
Char a ct er i st i c Limitations
Maximum for Average of daily
any one day values for thirty
consecutive days
shall not exceed
(Metric units, kg/kkg of product)
(English units, lb/1000 Ib of product)
TSS 0.50 0.25
Total phosphorus 0.80 0.40
(as P)
Fluoride 0.30 0.15
pH Within the range 6.0 to 9.5.
Rationale for Best Practicable Control Technology
Currently Available
The criteria used for selection of the treatment technology
included a variety of items ranging from consideration of
the process characteristics to the known commercial limits
of capability.
In this process, the conditions are such that contaminated
process water cannot be re-used or treated due to the
product purity specifications and the unit operations
required to attain that purity. Therefore, fresh water use
is a process requirement and continuous discharge of process
water is a necessity. Based on this consideration, the
capability of treating the contaminated process water to
achieve significant reduction of contaminants to acceptable
levels has been commercially proven. The recognition that
this end-of-process treatment is sensitive to water quantity
variations with subsequent adverse quality effects indicated
the need to base limitations on production tonnage rather
than the best possible treatment results and concentrations.
Six different process areas contribute to the contaminated
process water stream and process water effluent quantity is
a function of the number of units in instantaneous
operation.
Another consideration was that the proposed guidelines
coincide with commercial operations for reduction of
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parameters within limits that would not initiate the need
for additional treatment facilities. That is, the
guidelines proposed coincide with contaminant levels
attainable at the proposed pH 6.0 to 9.5 treatment range.
This pH range permits direct discharge of clarified
effluent, without neutralization. All waste streams that
bear any of the dehydrated products, metaphosphate through
polyphosphate, can be diverted to the recirculation pond
when flow to the clarifier is sufficient to cause a
discharge violation. These modified phosphates create
problems in the usual clarification process. The treatment
system will require a hydrolytic process that converts
phosphate components to the orthophosphate form if
significant quantities of polyphosphate waste water
components are in the stream undergoing lime precipitation
and clarification. These processes are discussed in Section
VII.
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SECTION X
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
The effluent limitations which must be achieved by July 1,
1983, are based on the degree of effluent reduction
attainable through application of the best available
technology economically achievable. This level of
technology was based on the very best control and treatment
technology employed by a specific point source within the
industrial category and on sound, established waste water
management and treatment processes.
Specialized definitions are the same as for the best
practicable control technology currently available except
that the surge capacity must hold the heaviest 25-year-24-
hour rainfall instead of the 10-year event rainfall.
Subpart D - Defluorinated Phosphate Rock Subcategory
The following limitations establish the quantity or
quality of pollutants or pollutant properties, which may be
discharged by a point source subject to the provisions of
this subpart after application of the best available
technology economically achievable:
(a) Subject to the provisions of paragraphs (b) , (c)
and (d) below:
The following limitations establish the quantity or
quality of pollutants or pollutant properties, controlled by
this section, which may be discharged by a point source
subject to the provisions of this subpart after application
of the best available technology economically achievable:
there shall be no discharge of process wastewater pollutants
to navigable waters.
(b) Process waste water pollutants from a cooling water
recirculation system designed, constructed and operated to
maintain a surge capacity equal to the runoff from the 25-
year, 24-hour rainfall event may be discharged, after
treatment to the standards set forth in subparagraph (c)
below, whenever chronic or catastrophic precipitation events
cause the water level in the pond to rise into the surge
capacity. Process waste water must be treated and
discharged whenever the water level equals or exceeds the
mid point of the surge capacity.
(c) The concentration of pollutants discharged in
process wastewater pursuant to the limitations of paragraph
(b) shall not exceed the values listed in the following
table:
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Average of Daily
Values for 30
Effluent Maximum for Consecutive Days
Characteristic Any 1 Day Shall Not Exceed
mg/1
Total Phosphorus(P) 105 35
Fluoride 75 25
TSS 150 50
pH Within the range 6.0 to 9.5
The total suspended solid limitation set forth in this
paragraph shall be waived for process wastewater from a
calcium sulfate storage pile runoff facility, operated
separately or in combination with a water recirculation
system, which is chemically treated and then clarified or
settled to meet the other pollutant limitations set forth in
this paragraph.
(d) The concentration of pollutants discharged in
contaminated non-process wastewater shall not exceed the
values listed in the following table:
Average of Daily
Values for 30
Effluent Maximum for Consecutive Days
Characteristic Any 1 Day Shall Not Exceed
mg/1
Total Phosphorus(P) 105 35
Fluoride 75 25
pH Within the range 6.0 to 9.5
Rationale for the Best Available Technology Economically
Achievable
The rationale is identical to that for best practicable
control technology currently available, except that a
greater freeboard is required for retention of heavier
rains. The required technology to achieve BATEA has been
established at exemplary plants.
Subpart E - Defluorinated Phosphoric Acid Subcategory
The following limitations establish the quantity or
quality of pollutants or pollutant properties, which may be
discharged by a point source subject to the provisions of
this subpart after application of the best available
technology economically achievable:
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(a) Subject to the provisions of paragraphs (b) , (c)
and (d) below:
The following limitations establish the quantity or
quality of pollutants or' pollutant properties, controlled by
this section, which may be discharged by a point source
subject to the provisions of this subpart after application
of the best available technology economically achievable:
there shall be no discharge of process wastewater pollutants
to navigable waters.
(b) Process waste water pollutants from a cooling water
recirculation system designed, constructed and operated to
maintain a surge capacity equal to the runoff from the 25-
year, 24-hour rainfall event may be discharged, after
treatment to the standards set forth in subparagraph (c)
below, whenever chronic or catastrophic precipitation events
cause the water level in the pond to rise into the surge
capacity. Process waste water must be treated and
discharged whenever the water level equals or exceeds the
mid point of the surge capacity.
(c) The concentration of pollutants discharged in
process wastewater pursuant to the limitations of paragraph
(b) shall not exceed the values listed in the following
table:
Average of Daily
Values for 30
Effluent Maximum for Consecutive Days
Characteristic Any 1 Day Shall Not Exceed
r mg/1
Total Phosphorus (P) 105 35
Fluoride 75 25
TSS 150 50
pH Within the range 6.0 to 9.5
The total suspended solid limitation set forth in this
paragraph shall be waived for process wastewater from a
calcium sulfate storage pile runoff facility, operated
separately or in combination with a water recirculation
system, which is chemically treated and then clarified or
settled to meet the other pollutant limitations set forth in
this paragraph.
(d) The concentration of pollutants discharged in
contaminated non-process wastewater shall not exceed the
values listed in the following table:
Average of Daily
Values for 30
Effluent Maximum for Consecutive Days
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Characteristic Any 1 Day Shall Not Exceed
mg/1
Total Phosphorus (P) 105 35
Fluoride 75 25
pH Within the range 6.0 to 9.5
The rationale is identical to that for BPCTCA except that a
greater freeboard is required for retention of heavier
rains. The required technology has been established at
exemplary plants.
Subpart F - Sodium Phosphates Subcategory
The best available treatment economically achievable
includes the use of the contaminated water pond and
continuous lime treatment of some waste water streams.
The best available treatment economically achievable
standards for the sodium phosphates subcategory are set at
70 percent of the discharge levels for suspended solids,
fluoride and phosphate waste water components proposed for
the best practicable control technology currently available.
It is the opinion of the Environmental Protection Agency
staff and its advisors that this reduction can be readily
achieved. Improvements of this order and greater are common
in fertilizer phosphate plants facing the need for improved
water conservation practices to avoid excessive costly lime
treatment. The recirculation lagoon is available to handle
waste streams that present difficult treatment problems.
The following limitations establish the quantity or
quality of pollutants or pollutant properties, controlled by
this section, which may be discharged by a point source
subject to the provisions of this subpart after application
of the best available technology economically achievable:
Effluent Effluent
Characteristic Limitations
Maximum for Average of daily
any one day values for thirty
consecutive days
shall not exceed
(Metric units, kg/kkg or lb/1000 Ib of product)
TSS 0.35 0.18
Total phosphorus 0.56 0.28
(as P)
Fluoride 0.21 0.11
pH Within the range 6.0 to 9.5.
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SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
AND PRETREATMENT STANDARDS
New Source Performance Standards
This level of technology is to be achieved by new sources.
The term "new source" is defined in the Act to mean "any
source, the construction of which is commenced after
publication of proposed regulations prescribing a standard
of performance." New source performance standards are to be
evaluated by adding to the consideration underlying the
identification of best practicable control technology
currently available, a determination of what higher levels
of pollution control are available through the use of
improved production processes and/or treatment techniques.
Thus, in addition to considering the best in-plant and end-
of-process control technology, new source performance
standards are to be based upon an analysis of how the level
of effluent may be reduced by changing the production
process itself. Alternative processes, operating methods or
other alternatives are to be considered. However, the end
result of the analysis identifies effluent standards which
would reflect levels of control achievable through the use
of improved production processes (as well as control
technology), rather than prescribing a particular type of
process or technology which must be employed. A further
determination which was to be made for new source
performance standards is whether a standard permitting no
discharge of pollutants is practicable.
The following factors were to be considered with respect to
production processes which were analyzed in assessing new
source performance standards:
a. The type of process employed and process changes.
b. Operating methods.
c. Batch as opposed to continuous operations.
d. Use of alternative raw materials and mixes of raw
materials.
e. Use of dry rather than wet processes (including
substitution of recoverable solvents for water).
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f. Recovery of pollutants as by-products.
Subpart D - Defluorinated Phosphate Rock Subcategory
The following effluent limitations establish the
quantity or quality of pollutants or pollutant properties,
which may be discharged by a point source subject to the
provisions of this subpart after application of the
standards of performance for new sources.
(a) Subject to the provisions of paragraphs (b) , (c)
and (d) below:
The following limitations establish the quantity or
quality of pollutants or pollutant properties, controlled by
this section, which may be discharged by a point source
subject to the provisions of this subpart after application
of new source performance standards: there shall be no
discharge of process wastewater pollutants to navigable
waters.
(b) Process waste water pollutants from a cooling water
recirculation system designed, constructed and operated to
maintain a surge capacity equal to the runoff from the 25-
year, 24-hour rainfall event may be discharged, after
treatment to the standards set forth in subparagraph (c)
below, whenever chronic or catastrophic precipitation events
cause the water level in the pond to rise into the surge
capacity. Process waste water must be treated and
discharged whenever the water level equals or exceeds the
mid point of the surge capacity.
(c) The concentration of pollutants discharged in
process wastewater pursuant to the limitations of paragraph
(b) shall not exceed the values listed in the following
table:
Average of Daily
Values for 30
Effluent Maximum for Consecutive Days
Characteristic Any 1 Day ShallNot Exceed
mg/1
Total Phosphorus(P) 105 35
Fluoride 75 25
TSS 150 50
pH Within the range 6.0 to 9.5
The total suspended solid limitation set forth in this
paragraph shall be waived for process wastewater from a
calcium sulfate storage pile runoff facility, operated
separately or in combination with a water recirculation
system, which is chemically treated and then clarified or
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settled to meet the other pollutant limitations set forth in
this paragraph.
(d) The concentration of pollutants discharged in
contaminated non-process wastewater shall not exceed the
values listed in the following table:
Average of Daily
Values for 30
Effluent Maximum for Consecutive Days
Characteristic Any 1 Day Shall Not Exceed
mg/1
Total Phosphorus (P) 105 35
Fluoride 75 25
pH Within the range 6.0 to 9.5
Subpart E - Defluorinated Phosphoric Acid Subcategory
The following limitations and guidelines establish the
quantity or quality of pollutants or pollutant properties,
which may be discharged by a point source subject to the
provisions of this subpart after application of the
standards of performance for new sources:
(a) Subject to the provisions of paragraphs (b), (c)
and (d) below:
The following limitations establish the quantity or
quality of pollutants or pollutant properties, controlled by
this section, which may be discharged by a point source
subject to the provisions of this subpart after application
of the standards of performance for new sources: there shall
be no discharge of process wastewater pollutants to
navigable waters.
(b) Process waste water pollutants from a cooling water
recirculation system designed, constructed and operated to
maintain a surge capacity equal to the runoff from the 25-
year, 24-hour rainfall event may be discharged, after
treatment to the standards set forth in subparagraph (c)
below, whenever chronic or catastrophic precipitation events
cause the water level in the pond to rise into the surge
capacity. Process waste water must be treated and
discharged whenever the water level equals or exceeds the
mid point of the surge capacity.
(c) The concentration of pollutants discharged in
process wastewater pursuant to the limitations of paragraph
(b) shall not exceed the values listed in the following
table:
Average of Daily
Values for 30
95
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Effluent Maximum for Consecutive Days
Character!stic Any 1 Day Shall Not Exceed
mg/1
Total Phosphorus(P) 105 35
Fluoride 75 25
TSS 150 50
pH Within the range 6.0 to 9.5
The total suspended solid limitation set forth in this
paragraph shall be waived for process wastewater from a
calcium sulfate storage pile runoff facility, operated
separately or in combination with a water recirculation
system, which is chemically treated and then clarified or
settled to meet the other pollutant limitations set forth in
this paragraph.
(d) The concentration of pollutants discharged in
contaminated non-process wastewater shall not exceed the
values listed in the following table:
Average of Daily
Values for 30
Effluent Maximum for Consecutive Days
Cbaracteri s t i c Any 1 Day Shall Not Exceed
mg/1
Total Phosphorus(P) 105 35
Fluoride 75 25
pH Within the range 6.0 to 9.5
Subpart F - Sodium Phosphates Subcategory
Performance standards for new sources are the same as for
best available technology economically achievable:
The following standards of performance establish the
quantity or guality of pollutants or pollutant properties,
controlled by this section, which may be discharged by a new
source subject to the provisions of this subpart:
Pollutant or Effluent
Pollutant Property Limitations
Maximum for Average of daily
any one day values for thirty
consecutive days
shall not exceed
(Metric units, kg/kkg of product)
96
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(English units, lb/1000 Ib of product)
TSS 0.35 0.18
Total phosphorus 0.56 0.28
(as P)
Fluoride 0.21 0.11
pH Within the range 6.0 to 9.5
Pretreatment Standards for Existing and New Sources
All pretreatment standards are reserved for the present time
because of ongoing studies and incomplete administrative
decisions.
97
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SECTION XII
AC KNOWL EDGMENT
This report was prepared by the Environmental Protection
Agency on the basis of a comprehensive study performed by
Davy Powergas, Inc., under contract no. 68-01-1508, model
#2. Mr. R. W. Heinz, Project Manager, prepared the original
(contractor's) report. Mr. Heinz was assisted in the
preparation of this report, by the following personnel: Mr.
D. W. Ross, Mr. Charles T. Harding, Mr. Gerald T. Fields,
Mr. N. V. Fry, Mr. George Telatnik, Mr. Jack Frost, Mr. E.
Singler, and Mr. H. Honey.
This study was initiated under the supervision and guidance
of Elwood E. Martin. The final phases of the study were
supervised by Chester E. Rhines, with extensive transition
assistance from Mr. Martin.
Overall guidance and excellent assistance was provided by
the author's associates in the Effluent Guidelines Division,
particularly Messrs. Allen Cywin, Director, Ernst P. Hall,
Deputy Director, and Walter J. Hunt, Branch Chief.
The cooperation of manufacturers who offered their plants
for survey and contributed pertinent data is greatfully
appreciated. The operations and the plants visited were the
property of the following companies:
Borden Chemical Company, Plant City, Fla.
Occidental Chemical Co., Houston, Tex.
Olin Corporation, Stamford, Conn.
J. R. Simplot Co., Pocatello, Idaho
Thornton Laboratory, Tampa, Fla.
The members of the working group/steering committee who
participated in the internal EPA review are:
Mr. Walter J. Hunt, Chairman, Effluent Guidelines
Di vi si on
Dr. Chester E. Rhines, Project Officer,
Effluent Guidelines Division
Mr. Elwood Martin, Effluent Guidelines Division
99
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Mr. Lamar Miller, Effluent Guidelines Division
Dr. Robert Swank, NERC, Corvallis (Athens)
Mr. Paul Desrosiers, ORM, Headquarters
Mr. Louis W. DuPuis, Economic Analysis Section
Dr. Edmund Lomasney, Region IV
Mr. James Rouse, NFIC, Denver
Acknowledgement and appreciation is also given to Ms. Kaye
Starr, Ms. Nancy Zrubek, Ms. Brenda Holmone, Ms. Alice
Thompson, and Ms. Ernestine Christian of the Effluent
Guidelines Division secretarial staff and to the secretarial
staff of Davy Powergas, Inc., for their efforts in the
typing of drafts, necessary revisions, and the final
preparation of this and the contractor's draft document. .
100
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SECTION XIII
REFERENCES
A. Phosphoric Acid, Phosphates and Phosphatic Fertilizers
by William Henry Waggaman, University Microfilms, Inc.,
Ann Arbor, PP. 233-236, original volume copyright 1927,
1952, by Reinhold Publishing Corporation, Library of
Congress Card Number 52-9791.
B. Defluorination of Phosphate Rock by Clinton A.
Hollingsworth, Lakeland, Florida, assignor to Smith-
Douglas Company, Inc., Norfolk, Va., United States
Patent Office Number 2,995,137, Patented Aug. 8, 1961.
C. Method of Def luorinatinq Phosphate Rock in a. Fluid Bed
Reactor by Clinton A. Hollingsworth and John H. Snyder,
Lakeland, Fla., assignors to the Borden Company, New
York, N.Y., a corporation of New Jersey, United States
Patent Office Number 3,364,008, Patented January 16,
1968.
D. Method of Agglomerating Phosphate Material by Clinton A.
Hollingsworth and Jack F. Lewis, Lakeland, Fla.,
assignors, by mesne assignments, to The Borden Company,
United States Patent Office, Number 3,189,433, Patented
June 15, 1965.
E. Chemical Economics Handbook, Stanford Research
Institute, Phosphorus and Compounds, 762.2030 A,
762.2030 B, 762.2030 C, December 1969.
F. Phosphorus and Its Compounds, John R. Van Wager,
Interscience Publishers, Inc., New York (1961) Library
of congress Card No. 58-10100.
G. 1972 Fertilizer Summary Data, Norman L. Hargett,
National Fertilizer Development Center, Tennessee Valley
Authority, Muscle Shoals, Alabama.
H. Development Document for Effluent Limitations Guidelines
and New Source Performance Standards for the Phosphorus
Derived Chemicals Segment of the Phosphate Manufacturing
Point Source Category, United States Enivronmental
Protection Agency, EPA 440/1-74/006, January, 1974.
I. Development Document for Effluent Limitations Guidelines
and New Source Performance Standards for the Basic
Fertilizer Manufacturing Point Source Category, United
101
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States Environmental Protection Agency, EPA 440/174-011-
a, March, 1974.
J. Engineering Field Manual for Conservation Practices,
U.S. Department of Agriculture, Soil conservation
Service Section I, 1969 and Section 2, 1971.
K- Earth Manual, U.S. Department of the Interior, Bureau of
Reclamation, First Edition, Denver, Colorado, July, 1940
(a new edition is being printed).
k« Design of Small Dams, U.S. Department of the Interior,
Bureau of Reclamation, Second Edition, 1973.
M. Those Nasty Phosphatic Clay Ponds, Environmental Science
and Technology, page 312, April, 1974.
N. Reconnaissance Study of Radiochemical Pollution from
Phosphate Rock Mining and Milling, National Field
Investigations Center-Denver, Denver, Colorado, Revised
May, 1974.
O. Interim Radium-226 Effluent Guidance for Phosphate
Chemicals and Phosphate Fertilizer Manufacturing,
Statement of Considerations - August 5, 1974, Criteria
and Standards Division, Office of Radiation Programs,
Environmental Protection Agency, Washington, D.C.
20460.
P. Black & Veatch, Consulting Engineers, Process Design
Manual for Phosphorus Removal, U.S. Environmental
Protection Agency Program 17010 GNP, Contract 14-12-936
(October 1971) .
Q. "Water Quality Criteria 1972," National Academy of
Sciences and National Academy of Engineering for the
Environmental Protection Agency, Washington, D.C. 1972
(U.S. Govt. Printing Office Stock No. 5501-00520).
R. R.E. Kirk and D.F. Othmer, Encyclopedia of Chemical
Technology, Interscience, N.Y., 1966.
S. EPA Report, Suspect Carcinogens in Water Supplies, by
Office of R S D, April, 1975.
T. Final Report on "Cost of Implementation and Capabilities
of Available Technology to Comply with P.L. 92-50C",
Industry Category 18, Phosphate Manufacturing for
National Commission on Water Quality, R.A. Ewing,
102
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Battelle's Columbus Laboratories with assistance from
Burgess & Niple, Ltd., July 3, 1975.
U. Technical Note ORP/CSD-75-3 Radioactivity Distribution
in Phosphate Products, By-Products, Effluents, and
Wastes, The U.S. EPA, Office of Radiation Programs,
August, 1975.
V. Technical Note, ORP/CSD-75-4 Preliminary Findings, Radon
Daughter Levels in Structures Constructed on Reclaimed
Florida Phosphate Land, U.S. EPA, Office of Radiation
Programs, September, 1975.
103
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SECTION XIV
GLOSSARY
Apatite
A natural calcium phosphate usually containing fluorine
occurring as phosphate rock.
PPG
Davy Powergas
Gyp-pond
This term is widely used at fertilizer phosphate plants to
indicate the pond receiving waste water and . acting as a
recirculation, cooling and water reuse pond. Many plants
have ponds with a variety of functions such as receiving the
calcium sulfate residue from acid treatment of rock,
receiving calcium fluoride from first stage of lime
precipitation, receiving calcium phosphate and calcium
fluoride sediment from second stage of lime precipitation,
recirculation of stack washing and tail gas scrubber water
and simultaneously removing heat and sediment, and
deposition of troublesome solids, as arsenic sulfide. Local
authorities will have to determine specific pond uses in
order to establish essential solid waste control and
groundwater pollution control measures.
kkg
1,000 kilograms
1
liter
Process Waste Water
The term "process waste water" means any water which, during
manufacturing or processing, comes into direct contact with
or results from the production or use of any raw material,
intermediate product, finished product, by-product, or waste
product.
Ton
All uses of term "ton" imply short ton equal to 2,000
pounds.
105
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TABLE XIV-J.
METRIC TABLE
CONVERSION TABLE
MULTIPLY (ENGLISH UNITS)
ENGLISH UNIT ABBREVIATION
acre ac
acre - feet ac ft
British Thermal
Unit BTU
British Thermal
Unit/pound BTU/lb
cubic feet/minute cfm
cubic feet/second cfs
cubic feet cu ft
cubic feet cu ft
cubic inches cu in
degree Fahrenheit °F
feet ft
gallon gal
gallon/minute gpm
horsepower hp
inches in
inches of mercury in Kg
pounds Ib
million gallons/day mgd
mile mi
pound/square
inch (gauge) psig
square feet sq ft
square inches sq in
ton (short) ton
yard yd
* Actual conversion, not a multiplier
by TO OBTAIN (METRIC UNITS)
CONVERSION ABBREVIATION METRIC UNIT
hectares
cubic meters
kilogram - calories
kilogram calories/kilogram
cubic meters/minute
cubic meters/minute
cubic meters
liters
cubic centimeters
degree Centigrade
meters
liters
liters/second
killowatts
centimeters
atmospheres
kilograms
cubic meters/day
kilometer
atmospheres (absolute)
square meters
square centimeters
metric ton (1000 kilograms)
meter
0.405
1233.5
0.252
0.555
0.028
1.7
0.028
28.32
16.39
0.555(°F-32)*
0.3048
3.785
0.0631
0.7457
2.54
0.03342
0.454
3,785
1.609
(0.06805 psig +1)*
0.0929
6.452
0.907
0.9144
ha
cu m
kg cal
kg cal/kg
cu m/min
cu m/min
cu m
1
cu cm
°C
m
1
I/sec
kw
cm
atm
kg
cu m/day
km
atm
sq m
sq cm
kkg
m
106
A U.S. GOVERNMENT PRINTING OFFICE: 1976- 210-810/151
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U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
WH 552
POSTAGE AND FEES PAID
ENVIRONMENTAL PROTECTION AGENCY
EPA-335
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