EPA
Development Document for Effluent Limitations Guidelines
and New Source Performance Standards for the
BASIC FERTILIZER CHEMICALS
Segment of the
Fertilizer Manufacturing
Point Source Category
MARCH 1974
\ U.S. ENVIRONMENTAL PROTECTION AGENCY
I Washington, D.C. 20460
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DEVELOPMENT DOCUMENT
for
EFFLUENT LIMITATIONS GUIDELINES
and
NEW SOURCE PERFORMANCE STANDARDS
for the
BASIC FERTILIZER CHEMICALS SEGMENT OF THE
FERTILIZER MANUFACTURING
POINT SOURCE CATEGORY
Russell E. Train
Admini strator
Roger strelow
Acting Assistant Administrator for Air & Water Programs
Allen Cywin
Director, Effluent Guidelines Division
Elwood E. Martin
Project Officer
March, 1974
Effluent Guidelines Division
Office of Air and Water Programs
U.S. Environmental Protection Agency
Washington, D. C. 20U60
For sale by the Superintendent of Documents, U.S. Government Printing Office, Wellington, D.C. 20402- Price $2
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ABSTRACT
This document presents the findings of an extensive study of the
fertilizer industry for the purpose of developing effluent
limitation guidelines for existing point sources and standards of
performance and pretreatment standards for new sources to
implement sections 304, 306 and 307 of the Federal Water
Pollution Control Act, as amended (33 U.S.C. 1551, 1314, and
1316, 86 Stat. 816 et. seg.)(the "Act").
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
categorization, recommendations on effluent guidelines, and
definition of treatment technology. The fertilizer industry was
divided into five categories for more meaningful separation and
division of waste water treatment and development of effluent
guidelines. These subcategories are phosphate, ammonia, urea,
ammonium nitrate and nitric acid products. The phosphate
subcategory includes all ancillary operations necessary for
phosphate production (e.g. sulfuric acid and phosphoric acid).
Effluent guidelines for best practicable control technology
currently available, best available technology economically
achievable, and new source performance standards are recommended
for each category.
Treatment technologies such as either in-process or end-of-
process add on units are available or are in advanced development
stages to enable existent and future fertilizer plants to meet
the recommended effluent guidelines.
iii
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CONTENTS
I Conclusions 1
II Recommendations 3
III Introduction 7
IV Industry Categorization 65
V Waste Characterization 69
VI Selection of Pollutant Parameters 81
VII Control and Treatment Technology 95
VIII Cost, Energy and Nonwater Quality Aspect 131
IX Effluent Reduction Attainable Through the
Application of the Best Practicable Control
Technology Currently Available — Effluent
Limitations Guidelines 143
X Effluent Reduction Attainable Through the
Application of the Best Available Technology
Economically Achievable — Effluent Limitations
Guidelines 151
XI New Source Performance Standards 155
XII Acknowledgments 159
XIII Bibliography 161
XIV Glossary 165
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FIGURES
1. Nitrogen Fertilizers Plant Locations 17
2. Phosphate Fertilizers Plant Locations 21
3. . Sulfuric Acid Plant Single Catalysis 26
4. Sulfuric Acid Plant Double Catalysis 27
5. Rock Grinding 31
6. Wet Process Phosphoric Acid H2SOf£ Acidulation 34
7. NPK Process Nitric Acid Acidulation 36
8. Wet Phosphoric Acid Concentration 38
9. Merchant Grade Phosphoric Acid Clarification 49
10. Normal Superphosphate 42
11. Triple Superphosphate (Run-of-Pile R.O.P.) 45
12 Granulated Triple Superphosphate 47
13. Monoammonium Phosphate Plant 50
14. Diammonium Phosphate Plant 51
15. Ammonia Plant 54
16. Urea Plant 58
17. Ammonium Nitrate Plant 51
18. Nitric Acid Plant 53
19. Sulfuric Acid Effluent Control 97
20. Pond Water Treatment
21. Gypsum Pond Water Seepage Control
22. DAP Self Contained Process 106
23. Wet Process Phosphoric Acid System 108
24. Sulfuric Acid Dilution with Pond Water
25. Ammonia/Condensate Stripping
26. Integrated Ammonia/Condensate Stripper Unit 113
27. Ammonia/Condensate Air Stripping 115
VI
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28. Urea Hydrolysis 119
29. Urea Hydrolysis 120
30. Biological Treatment 124
31. Ion Exchange 126
32. Oil/Grease Removal System 128
33. Ammonium Nitrate Effluent Utilization 129
vii
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TABLES
1. Integration of Production in the Fertilizer Industry 15
2. Water Effluent Treatment Costs Phosphate Subcategory 134
3. Water Effluent Treatment Costs
Nitrogen Fertilizer Subcategories 137
U. Metric Units Conversion Table 168
viii
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SECTION I
CONCLUSIONS
The basic fertilizer chemicals segment of the fertilizer
manufacturing category can be grouped into five subcategories for
treatment and identification of plant effluent waste water:
phosphate, ammonia, urea, ammonium nitrate and nitric acid. The
phosphate subcategory includes sulfuric acid (sulfur burning),
phosphoric acid (wet process), phosphoric acid concentration,
phosphoric acid clarification, normal superphosphate, triple
superphosphate, and ammonium phosphates. In these subcategories
the treatment technology does exist, and in some cases is being
used, that would permit every existing fertilizer plant to meet
the proposed best practicable control technology currently
available.
Additional treatment methods, in the form of development
projects, pilot plant studies and plant prototype units, along
with technology from other industries are being refined, updated
and adapted so that their use will enable fertilizer plant
effluent to conform with the proposed best available technology
economically achievable.
Process modifications and plant waste water separation/collection
systems along with existing treatment methods will provide the
necessary technology to enable new fertilizer manufacturing
plants to meet the proposed new source standards.
The remainder of the fertilizer industry not covered in this
study will be included in a later study.
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SECTION II
RECOMMENDATIONS
Phosphate Subcategory
- The proposed effluent limitation representing the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available to
the phosphate subcategory is no discharge of process waste
water pollutants to navigable waters except as allowed under
the following conditions.
a. A process waste water impoundment, which is designed,
constructed and operated so as to contain the
precipitation from the 10 year, 24 hour rainfall event
as established by the U.S. National Weather Service for
the area in which such impoundment is located may
discharge that volume of precipitation that falls within
the impoundment in excess of that attributable to the 10
year, 21 hour rainfall event, when such event occurs.
b. During any calendar month in which the precipitation
exceeds the evaporation for the area in which a process
waste water impoundment is located, as established by
the U.S. National Weather Service (or as otherwise
determined if no monthly evaporation data have been
established by the National Weather Service) in the area
in which a process waste water impoundment is located
there may be discharged from such impoundment either a
volume of process waste water equal to the difference
between the precipitation and the evaporation for that
month or a volume of process waste water equal to the
difference between the mean precipitation and the mean
evaporation for that month as established by the U. S.
National Weather Service for the preceeding 10 year
period, whichever is greater.
c. Any process waste water discharged pursuant to
subparagraph(b) above shall not exceed each of the
following requirements:
Parameter
phosphorus (P)
fluoride as (F)
total suspended
nonfilterable
solids
Maximum daily
concentration
mg/1
70
30
50
Maximum average of daily values
for periods of discharge covering
10 or more consecutive days
mg/1
35
15
25
The pH of the water discharged shall be within the range
of 8.0 to 9.5 at all times.
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2. The proposed effluent limitation representing the degree of
effluent reduction attainable by the application of the best
available technology economically achievable is no discharge
of process waste water pollutants to navigable waters. A
discharge is only allowed under the following condition. A
process waste water impoundment which is designed,
constructed and operated so as to contain the precipitation
from the 25 year, 24 hour rainfall event as established by
the U.S. National weather Service for the area in which such
impoundment is located, may discharge that volume of
precipitation that falls within the impoundment in excess of
that attributable to the 25 year, 24 hour rainfall event,
when such event occurs.
3. The standard of performance representing the degree of
effluent reduction obtainable by the application of the best
available demonstrated control technology, processes,
operating methods, or other alternatives is no discharge of
process waste water pollutants to navigable waters. The same
conditions listed for best available technology economically
achievable apply.
Ammonia Subcategory
The proposed effluent limitations for the ammonia subcategory are
listed in the table below. The following abbreviations apply:
BPCTCA - best practicable control technology currently available
BATEA - best available technology economically achievable
BADCT - best available demonstrated control technology
BPCTCA BATEA BADCT
SJOStJSlY. daily monthly daily Ejonthly daily
Ammonia (as N)
kg/kkg (lb/1000)
of product O.C625 0.125 0.025 0.05 0.055 0.11
The above monthly limitations represent the maximum average of
daily values for any period of 30 consecutive days. The daily
maximum average is twice the 30 day maximum average. pH shall be
within the range of 6.0 to 9.0 at all times.
Urea Subcategpry
The proposed effluent limitations for the urea subcategory are
listed in the following table:
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Ammonia (as N)
kg/kkg (lb/1000 Ib)
of product
nonprilled urea
prilled urea
BPCTCA
monthly daily
BATEA
0.0375 0.075 0.015
0.05 0.1 0.015
0.03 O.C325 0.065
0.03 0.0325 0.065
Organic Nitrogen (as N)
kg/kkg (lb/1000 Ib)
of product
nonprilled urea 0.175
prilled urea 0.50
O.UU 0.025 0.05 0.12 0.2H
1.25 0.0375 0.075 0.35 0.7
The above monthly limitations represent the maximum average of
daily values for any period of 30 consecutive days. The daily
maximum average is greater than the 30 day maximum average as
shown. pH shall be within the range of 6.0 to 9.0 at all times.
Ammonium Nitrate Subcategory
The proposed effluent limitations for the ammonium
subcategory are listed in the following table.
nitrate
BPCTCA
Ammonia (as N)
kg/kkg (lb/1000 Ib)
of product
nonprilled AN
prilled AN
Nitrate (as N)
kg/kkg (lb/1000 Ib)
of product
nonprilled
prilled
BATEA BADCT
monthly
0.0375 0.075 0.0075 0.015 0.025
0.1 0.2 0.0075 0.015 0.05
0.05 0.1 0.0125 0.025 0.0125
0.11 0.22 0.0125 0.025 0.025
0.05
0.10
0.025
0.05
The above monthly limitations represent the maximum average of
daily values for any period of 30 consecutive days. The daily
maximum average average is twice the 30 day maximum average. pH
shall be within the range of 6.0 to 9.0 at all times.
Nitric Acid subcateggrv
The proposed effluent limitation representing the degree of
effluent reduction attainable by the application of the best
practicable control technology currently available, best
available technology economically achievable, and best available
demonstrated control technology, processes, operating methods, or
other alternatives is no discharge of process waste water
pollutants to navigable waters.
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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 Administrator 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
practicable control technology currently available and the degree
of effluent reduction attainable through the application of the
best control measures and practices achievable including
treatment techniques, processes and procedure innovations,
operation methods and other alternatives. The 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 within the fertilizer manufacturing category of point
sources, which included within the list published January 16,
1973.
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Summary of Methods Used for Develogment of the Effluent
LilDiiliiSnS 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 separate 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 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 aquatic organisms. The constitutents
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
in-plant and end-of-process technologies, which are existent or
capable of being designed for each segment. It also included an
identification of, 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 each was also
identified. In addition, the nonwater impact of these
technologies upon other pollution problems, including air, 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 technology economically achievable," and 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.
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Delineation of Study
The effluent limitations guidelines and standards of performance
proposed in this report were developed from operating data,
sampling and information gathered from some twenty-five (25)
plants. The methods and procedures used in the accumulation of
that overall information is described in the following
paragraphs.
Initial consideration was directed to identification and
categorization of the various processes defined as comprising the
fertilizer industry.
These processes and the corresponding standard Industrial
Classification codes are defined as:
Chemical sic
Sulfuric Acid
Sulfur burning only. 2819
Phosphoric Acid
Including phosphate rock grinding when it is performed
on the immediate vicinity of the acid production unit. 2874
Phosphoric Acid concentration 2874
Phosphoric Acid Clarification 2874
Normal Superphosphate 2874
Triple superphosphate 2874
Both run-of-pile and granulated processes
Ammonium Phosphates 2874
Ammonia 2873
Urea 2873
Ammonium Nitrate 2873
The objective was to categorize the many processes into the least
number of units that are practical for the end purpose of water
effluent monitoring and structuring of specific fertilizer
complexes for EPA and State enforcement officials.
Categorization inherently included determination of those point
sources which required separate limitations and standards. The
overall concept was to provide sufficient definition and
information on an unitized basis to allow application of a
building block principle. Such classification of data readily
permits the structuring of total water effluent information for
any specific fertilizer complex regardless of the multiplicity of
processes comprising its make-up.
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3ases 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,
information from qualified consultants, and cross reference with
related non-fertilizer technologies utilized in other industries.
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. Criteria developed for this purpose of
plant evaluation and subsequent sampling consideration are listed
below.
1) Discharge Effluent Quantities
Installations with low effluent quantities and/or the
ultimate of "no discharge".
2) Effluent^ cont aminant^Leyel
Installations with low effluent contaminant concentrations
and quantities.
3) Effluent Treatment Method and^Effectiveness
Use of best currently available treatment methods, operating
control, and operational reliability.
**) Water^Manaofement Practice
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.
5) Land Utilization
10
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Consideration of land area involved in water effluent control
system with the most acceptable being those with the least
area.
6) Air Pollution Control
Those plants with the most comprehensive and effective air
pollution control. In turn liquid effluent from such plants
may represent the most serious water effluent condition.
7) Geographic IjOcation
Those facilities in close proximity to sensitive vegetation,
high population density, land availability, and areas where
local or state standards are most restrictive.
8) Management^Ogerating^jPhilosQphy
Plants whose management insists upon effective equipment
maintenance and housekeeping practices.
g) Raw Materials
Installations utilizing different raw materials where
effluent contaminants differ in impurity type or
concentration.
10) Divers it Y^of_Proc.esses
On the basis that other criteria are met, then consideration
was given to installations having a multiplicity of
fertilizer processes.
11) Production
On the basis that other criteria are equal, then
consideration was given to the degree of above design
production rate realized from equipment that is water
pollution sensitive.
Each of the above criteria were, in turn, assigned a range of
numerical grade values to allow an overall numerical evaluation
of each plant and the selection of exemplary plants in each
category.
A tentative exemplary plant list was compiled. The initial list
was composed chiefly from the input of three organizations
(Section XII - ref. 30, 34, 37). These organizations had data
and plant information obtained from permit application, in-house
knowledge of the nitrogen and phosphate fertilizer industries
which together with information obtained through private
conversations with knowledgeable industry personnel completed the
list. This list was then presented to the trade association for
comments and suggestions.
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Contact was then made with the plants on the list. Initial
contact was made by the EPA Project Officer to the corporate
official suggested by the trade association. This was followed
with a second contact by the contractor to the specified plant
manager with the objective of scheduling a plant screening visit.
The screening visit served to acquaint the plant manager with the
purpose and intent of the study as well as the opportunity to
consider whether or not there should be participation.
Participation in the study was kept on a strictly voluntary
basis. It is well to clarify that every plant contacted,
willingly cooperated and that industry cooperation was
outstanding.
The screening visit also served as either a confirmation of the
initial tentative listing of a plant in an exemplary category or
a reconsideration of that rating. Such an evaluation was made
after a discussion on data availability, review of the facilities
for segregation and flow monitoring of individual processes, and
a plant inspection trip. A variety of situations were
encountered. These ranged from decisions not to include a
specific plant, although exemplary, to learning of another
facility which more completely fulfilled the study objectives.
Some plants had complete individual process effluent records
together with sample validation from other private or state
agencies. It was found that the majority of the plants monitor
only the main complex effluent streams and have little or no
knowledge of individual process effluents. Consequently, the
screening visits prompted decisions to both delete and add to the
list of plants exhibiting exemplary water effluent conditions.
Sample 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 work.
Six persons were used. The fertilizer plant operating experience
of these six people ranged from a minimum of 14 years to 24 years
with the average being 20 plus 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
12
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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 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 types; shift,
daily or weekly frequency, etc. All samples collected by the
contractor were composite samples composed of a minimum of
four with the vast majority containing eight or more grab
samples all caught at regular time intervals throughout the
sample period. Sample periods except for special conditions
were a minimum of four (4) hours.
6) Validation of data via intimate knowledge 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 commerical laboratory, was
conducted on each plant visited. A total of 25 plants were
inspected. Of these 10 plants were selected, based upon the
6 criteria for verification of effluent limits data.
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GENERAL DESCRIPTION^QF THE INDUSTRY
The U.S. fertilizer industry has undergone such significant
changes in the past thirty years that it has lost its old stigma
of "mud chemistry". The sledge hammer and shovel days have been
replaced by large, modern, fume free, plants operated from an air
conditioned control room.
Eighty percent of the volume of agricultural chemicals used today
are materials that were not available in their present form at
the time of World War II. Fertilizer use today, in terms of
plant nutrients, is four and one quarter times as great as it was
in 1940. On the assumption that this fertilizer is properly
used, it represents one of the major reasons why farm yields are
up and unit costs are lower. It has been estimated that the use
of commercial fertilizer saves the U.S. public $13 billion a year
on food bills or about $70 a year per person. Large scale
centrifugal compressor ammonia plants, increasing single train
plant capacities from 90-180 to 1400-1800 kkg/day (100-200 to
1500-2000 tons/day) ; sulfuric acid plant capacity increased from
270~t»50 to 1800 kkg/day (300-500 to 2000 tons/ day) ; and
development of ammonium phosphate granule fertilizers illustrate
the dramatic technology change.
This study considers the production of two of the three basic
fertilizer ingredients - nitrogen (N) and phosphate (P2O5), the
third being potassium oxide (K£0). The following tabulation
indicates the past and predicted North American consumption
growth of the former two ingredients.
Year •65-70 '70-80
Growth Growth '65-80
Ingredient 19.65 1970 1975 19£0 _Rate_ _Rate Increase
N 4.5 7.2 11.6 16.9 10% 9% 215%
P205 3.6 5.0 6.3 8.0 7% 5% 122%
Figures represent millions of metric tons
It can be noted that N consumption is expected to show the
greatest future growth rates as well as the largest increase in
absolute tonnage. Somewhat coincidentally the N and P2O5 type of
ingredient separation also applies to production facilities.
That is, various N type fertilizer materials are usually produced
in a plant complex which has only N type process units.
Similarly, various phosphate fertilizer materials are usually
produced in a plant complex which has only P2O5 type process
units. This is demonstrated by Table 1. As a result: of this
natural separation, each of the two types will be discussed
separately throughout this report.
Fertilizer industry jargon identifies two types of product -
nonmixed and mixed. Straight fertilizers are defined as those
14
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Table 1
Intergration of Production in the Fertilizer Industry
No. of
Companies NH3 U N.A. A.N. S.A.
22 X
2 X
2 X
X X
3 X X X
3 11
1
3 I/
6
1 XX
7 I/
3 11
IX ll
1 I/
3 X
IX X
2 X X
13 XX
5 X XX
3 XXX
1 XXX
16 X X X X
1 XX
2 X XX
1 XXX
4 X X X X
1 X X X X I/
1 X XX
i x x x x
2 X X
1 X
2 X
2 X X
1 X X X
1 X
1 x x
3 X
7 X
1 X
IX X
IX XXX
1 X X X X X
No. of
Wet A. P. TSP SPA Plants
22
2
2
12
9
X 3
X 1
X X 6
X 6
X 3
XX 14
XXX 9
XXX 4
X X X X 4
6
3
4
26
15
9
3
64
X 3
X 8
X 4
X 20
XX X 7
4
5
4
XX 6
XX 8
XX 5
XXX 4
XXX 5
X XXX 15
14
XX 4
XXX 6
4
5
_ _
160
_ 7
390
J^/ Not identified individually in data used to develop this list, but must assume existence
of sulphuric acid facility as intermediate to wet acid production.
21 Only 109 firms — includes more than one location of plant operations for some firms.
U Urea
N.A. Nitric acid
A.N. Ammonium nitrate
S.A. Sulfuric acid
Wet Wet phosphoric acid
A. P. Ammonium phosphate
TSP Triple Superphosphate
SPA Superphosphate acid
15
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which contain only a single major plant nutrient. Mixed
fertilizers are defined as those which contain two or more
primary plant nutrients. Mixed fertilizers can be produced by
chemically reacting different ingredients and utilizing the
chemical reaction as the binding force; or simply by mechanically
blending together straight fertilizers. The following tabulation
lists the principal straight and mixed fertilizers produced in
the U.S.
Straight Fertilizers Mixed_Fertilizers
Nitrogen Fertilizers
Ammonia
Urea
Ammonium Nitrate
Phosphate Fertilizers
Phosphoric Acid Ammonium Phosphates
Normal Superphosphate
Triple Superphosphate
Nitrogen Fertilizer Industry
Nitrogen based fertilizers have in the past realized both the
greatest consumption and industry growth rates of the three basic
fertilizer nutrients (N, P2O.5 and K2O) and are predicted to
continue to do so for the near future. A possible reason for
this may be due to the fact that application of N-based
fertilizers can create spectacular crop responses. Such response
however is comparatively short lived and can result in disastrous
crop failures unless the N fertilization is followed with P2O!5
and K2O fertilization within one or two years. This lead time
and/or the realization of the need for P2.O5 and K2O addition is
certainly contributary to the lag time between N and P2O5 - K2_O
usage and production.
The compounds used and means of applying nitrogen to the soil
have undergone radical changes since the early nineteen hundreds.
Prior to this time practically all fertilizer nitrogen came from
natural organic materials. Then between 1900 and 1920 the
combination of natural nitrates and by-product ammonia from coke
oven gas, supplied the majority of the nitrogen used by the
fertilizer industry. This period concluded with the development
of the Haber-Bosch process which made possible the conversion of
atmospheric nitrogen into ammonia. Refinement of this process
and development of single pieces of reliable, large scale
mechanical equipment has been responsible for ammonia becoming
the principal fertilizer material.
Today in the U.S., there are 171 ammonia plants located in 25
different states producing in excess of 17,000,000 kkg/year
(18,700,000 tons/year). These plants have annual capacities
ranging from 10,000 to 435,000 kkg/year (11,000 to 480,000
16
-------
FIGURE 1
AMMONIA
PLANT LOCATIONS
AMMONIUM NITRATE
PLANT LOCATIONS
UREA
PLANT LOCATIONS
NITRIC ACID
PLANT LOCATIONS
-------
tons/year). Locations of nitrogen fertilizer plants are
indicated on Figure 1. Ammonia plant locations are selected on
the basis of raw material supply and proximity to market area
with the former being the dominating consideration.
Since atmospheric nitrogen can be obtained at any location, the
raw material of importance is hydrogen. Hydrogen feedstock
sources for modern ammonia plants are natural gas and petroleum
fractions. In turn this has selectively placed the highest
industrial concentrations of ammonia plants near sources of these
two raw materials, namely Louisiana, Texas, California, Iowa,
Mississippi and Arkansas. The midwest agricultural section is
the major sales market area with Iowa being the largest consumer
state.
Ammonia plants are classified into two categories - those
operating with reciprocating gas compressors and those operating
with centrifugal gas compressors. Generally speaking, those
single train plants with annual capacities of less than 150,000
kkg/year {165,000 tons/year) are operated with reciprocating
compressors while all larger plants, representing the more modern
type, operate with centrifugal compressors. The breakpoint
between the two is strictly economic. That is, in order to
realize low per ton production costs industry has been building
ever larger single train plant capacities. Introduction of the
centrifugal unit in this process permitted dramatically increased
single unit compressor capacity which is directly reflected in
lower capital costs. To appreciate the effect of the centrifugal
compressors on ammonia processing requires only a review of what
has occurred since 1955. In 1955 single train capacities of 270
kkg/day (300 tons/day) were considered large plants. Today, 900
kkg/day (1000 tons/day) plants are common, several 1360 kkg/day
(1500 tons/day) units are in operation and plans are being made
to build 2300 kkg/day (2500 tons/day) plants. These larger units
have not been without problems in regard to on-stream time but it
is unlikely that future U.S. plants will be less than 900 kkg/day
(1000 tons/day) capacity.
As previously mentioned, it is modern practice to use an ammonia
plant as a basic unit and then integrate it with other process
units to manufacture a range of different products. An important
process unit usually associated with an ammonia plant in a
nitrogen fertilizer complex is nitric acid. There are
approximately 124 operating nitric acid plants in the U.S. with
capacities ranging from 7,000 to 2UO,000 kkg/year (8,000 to
265,000 tons/year). Output from these plants is used as an
intermediate feed stock for the production of ammonium nitrate.
Ammonium nitrate ranks second only to ammonia as a source of
fertilizer nitrogen. Production of this material for fertilizer
purposes increased very rapidly in the period 1950-1965 to the
point that it provided 32% of the total fertilizer N market.
Since 1965, use of this fertilizer in terms of market percentage
has been decreasing. This decrease is expected to continue at a
slow rate for the foreseeable future. The reason for this
18
-------
decline is the increased usage of higher N analysis materials
such as ammonia and urea, 82% and 46% N respectively, as compared
to the 34% N in ammonium nitrate.
Currently there are 83 plants located (see Figure 1) in the U.S.
ranging in capacity from 9yOOO to 295,000 kkg/year (10,000 to
325,000 tons/year). Approximately 50% of the production from
these plants is used as fertilizer and the balance as explosives
and other industrial use. The majority are small and have been
in service for many years.
Use of urea (46%N) as a source of fertilizer N has been a fairly
recent development which was prompted by shipping costs. In 1957
approximately 2% of the U.S. fertilizer nitrogen was supplied by
urea. Consumption has increased at an annual 17% a year rate to
approximately 12% of the total in 1971, a four fold increase in
the past 10 years. It is expected that this growth rate will
continue.
There are 59 operational plants (see Figure 1) in the U.S.
ranging in capacity from 7,000 to 350,000 kkg/year (8,000 to
385,000 tons/year). Approximately 75% of the total production is
used as fertilizer N with the balance used for cattle feed and
urea-formaldehyde resins. Urea contains the highest percent N of
any solid fertilizer. This, plus the fact that there are no
storage and handling explosion hazards, ensures that urea will
continue to be a popular fertilizer material.
PhosphateFertilizer Industry
The phosphate fertilizer industry has not had the spectacular
technical developments that the nitrogen industry has shown, but
in the past 20 years there have been dramatic changes in
production facilities, costs and industry image.
Prior to 1955 phosphate was considered to be the major U.S.
fertilizer nutrient. The majority of phosphate nutrient was in
the form of normal superphosphate which has a nominal P2O5
percentage of 19- 20%. The low production costs and simplicity
of this process resulted in the material being produced in a
myriad of small plants throughout the market area. Since 1955
normal superphosphate's share of the phosphate market has
steadily decreased and has been replaced with more concentrated
phosphate materials necessitating utilization of special unit
operations equipment and instrumentation designed to optimize
system control and efficiencies. In short, art and mud chemistry
was displaced with scientific methods, definition of process
variables, and development of control methods. In order to
manufacture merchant grade phosphoric acid, triple superphosphate
and ammonium phosphate in quantity, it was first necessary to
modernize and increase capacity of the essential intermediate -
phosphoric acid. Phosphoric acid manufacture in turn required
larger quantities of sulfuric acid (approx. 2.8 kkg 100% sulfuric
acid for each kkg of P2C^5 as phosphoric acid) . In the early
1960's, 550 kkg/day (600 tons/day) sulfuric acid plants were
19
-------
considered large. By 1965, single train sulfuric acid plants of
900-1100 kkg/day (1000-1200 tons/day) capacity became common with
additional capacity increases to 1400 - 180C kkg/day (1600-2000
tons/day) by 1967. Similarly, large wet process phosphoric acid
plants in the early 1960's were 180-270 kkg/day (200-300
tons/day) P2O5 units with multiple pieces of equipment required
to perform single unit operations such as acidulation and filtra-
tion. By 1965, single train phosphoric acid units and single
unit operations equipment with capacities of 450 kkg/day (500
tons/day) P2O5_ became commonplace followed with an 800 kkq/day
(900 tons/day) unit by 1967. Several plants in the design stages
will have capacities of 900-1100 kkg/day (1000-1200 tons/day).
As a result normal superphosphate's share of the fertilizer
market has been steadily decreasing. It is expected that normal
superphosphates share of the phosphate market will finally
stabilize at approximately 18%. This steady market loss caused
several of the smaller plants to shut down. Today there are
approximately 214 plants with capacities ranging from (15,000 to
300,000 tons/year) still in operation. These plants are located
over a wide cross-section of the market area (See Figure 2). In
contrast to the other phosphate processes, normal superphosphate
plants are usually not integrated with phosphoric acid complexes
but are most generally connected with fertilizer mix plants.
Essentially all the other phosphatic fertilizer process units are
like the nitrogen fertilizer industry and are integrated into
phosphate complexes. The majority of these large complexes are
located near the phosphate rock source in Florida. There are a
few fairly isolated complexes located along the Mississippi
River, North Carolina, Idaho, Utah and California. The North
Carolina and Western units (except California) utilize locally
mined rather than Florida mined phosphate rock.
Generally wet process phosphoric acid is used as an intermediate.
Steadily increasing quantities of merchant grade acid are
annually being sold but such acid is in turn used either in
fertilizer mixing plants or in preparing liquid fertilizer
solutions. Merchant grade acid is low strength (30% P2O5) acid
which has been concentrated to 52-54% P.2O5 and then processed to
remove a sufficient quantity of solid impurities to enable it to
be shipped and distributed without difficulty. An additional
near future market for merchant grade acid is in the production
of high quality technical grade acid. This is presently
dominated by phosphoric acid produced via the electric furnace
process (see the phosphate manufacturing, development document).
To date, there are no facilities producing technical grade acid
from merchant grade acid in the U.S., but serious consideration
is being given to such projects. One procedure for producing
such a quality acid is to treat merchant grade, wet process
phosphoric acid via solvent extraction to remove impurities.
A limited number of phosphoric acid plants also produce
fluosilicic acid (15^25% H2SiF6) as a by-product of the
phosphoric acid concentration or sulfuric acid digestion steps.
20
-------
FIGURE 2
I'HOIH'IIOKIC ACID
IH.ANT UH'ATIONS
GTSP,ROP,TSP
PLANT LOCATIONS
MAP/DAP
AMMONIUM PHOSPHATE
PLANT LOCATIONS
21
-------
The equipment required for this product is essentially "add on"
equipment which does not affect the overall process. Such
production significantly reduces the total amount of fluorine in
the raw waste load.
Currently there are 39 wet process phosphoric acid plants
operating in 15 states with capacities ranging from 41,000 to
360,000 kkg/year (45,000 to 400,000 tons/year) P2O5 (See Figure
2) . Five sizeable, new plants are currently in design and
construction stages and will be brought on stream in 1974 and
1975. These new units will primarily add to existing plant
capacities and will include only one new manufacturer.
Triple superphosphate (46-48% P2O5) , a concentrated fertilizer,
has partially displaced normal superphosphate. This material has
enjoyed a very rapid market growth since 195C to the point where
it is the second largest quantity of fertilizer phosphate
produced. There are two types of triple superphosphate (TSP)
produced. One is a non-uniform pulverized material designated as
run- of-pile (ROP) TSP. The other is a hard, uniform pelletized
material designated as granular TSP or GTSP. ROP is the older
process and from an overall standpoint is a difficult process to
environmentally control. In addition, the product is a
troublesome material to store, handle, and ship. Consequently
within the TSP family, ROP production is at best remaining
constant and GTSP production is constantly increasing. There are
several plants which process ROP into a granular material but
this imposes an additional process step and cost. Practically
all new future facilities will utilize the GTSP process.
TSP production units are always located within a phosphate
complex due to their dependency on phosphoric acid supply. There
are approximately 20 ROP production units ranging in capacity
from 32,000 to 440,000 kkg/year (35,000 to 600,000 tons/year).
Currently, there are 5 GTSP plants in operation and 3 new plants
in design and construction stages. The majority of the GTSP
process units are located within the same complexes as the ROP
units.
Ammonium phosphates are the concentrated, mixed fertilizer
products which in the past 20 years have been the growth
phenomenon of the phosphate industry. This category includes
both monoammonium (MAP) and diammonium (DAP) phosphate grades.
The only difference between grades is the degree of ammoniation.
Annual compound rate of growth over the past ten years has been
19.8%. Such popularity is due to a number of factors which are
are so prominent that ammonium phosphates are certain to continue
as a most important mixed fertilizer material. DAP has emerged
and will continue to be the dominant grade. Both products are
made by neutralizing 30-40% P2O^ phosphoric acid with the proper
quantity of ammonia.
As with most production processes, plant capacities are
constantly being increased to effect capital cost and production
economies. Commonplace capacities prior to 1973 have been 32-45
22
-------
kkg/hr (35-50 tons/hour), but new plants scheduled for completion
in 1974 will have instantaneous single train capacities of up to
90 kkg/hr (100 tons/hour). Currently there are 53 operating
ammonium phosphate plants located in the U.S. ranging in capacity
between 9,000 and 550,000 kkg/year (10,000 and 600,000 tons/year)
(See Figure 2) .
23
-------
Specific
Process^DescriPtions
Phosphate Fertiliser Industry
The phosphate fertilizer industry is defined as eight separate
processes: sulfuric acid, phosphate rock grinding, wet process
phosphoric acid, phosphoric acid concentration, phosphoric acid
clarification, normal superphosphate, triple superphosphate, and
ammonium phosphates.
The two important basic units are sulfuric and wet process
phosphoric acid. The sulfuric acid unit is essential to the
phosphoric acid plant not only for the basic sulfuric acid raw
material but also to produce steam for operation of vacuum and
evaporation equipment. Sulfuric acid is also a basic raw
material for normal superphosphate production. Phosphoric acid
is the basic raw material for all the other processes.
Essentially all existing phosphate fertilizer complexes are
separated either by geographic location or by area within a
general fertilizer plant from the nitrogen fertilizer operations.
Such separation was a significant factor in establishing the
separate fertilizer categories.
Since phosphate fertilizer processes have either sulfuric acid,
phosphate rock, or phosphoric acid in common, the effluents from
the separate processes also have common contaminants which vary
only in concentration. Primary contaminants in the effluents
from these units are fluorine (F) and phosphorus (P). The only
contaminant not common to all units is nitrogen (N) . Ammonia is
a basic raw material to the ammonium phosphate process and is the
only source of N injection to a phosphate process effluent.
Therefore, with the exception of N, a common effluent treatment
system can be established to treat the F and P contaminants from
all phosphate fertilizer processes. In actual practice,
practically all complexes combine the various unit effluents into
a large recycle water system. This large contaminated recycle
water system is self contained for a large portion of the year.
It is only when the quantity of recycle water increases beyond
capacity to contain it, that effluent treatment is necessary.
Increases in recycle water inventory is usually due to an
imbalance between rainfall and evaporation. In Florida this
means that some plants discharge treated effluent up to four
months per year.
24
-------
Sulfuric Acid
Process Description
General
In the United States, essentially all sulfuric acid utilized in
the manufacture of fertilizer products and intermediates is
produced by the contact process. The process is so named due to
the use of a catalyst surface to speed the oxidation reaction
between sulfur dioxide (SO2) and oxygen (O2). This reaction
occurs when the two gaseous components "contact" each other on
the surface of palletized vanadium pentoxide catalyst to form
resultant sulfur trioxide (SO3) gas. In turn, the sulfur trioxide
(SO3) gas is hydrolyzed by the addition of water to form sulfuric
acid (H2S04) .
Prior to 1930 the contact process was used primarily in Europe
for the manufacture of high strength sulfuric acid (98 + %) and
oleums. From this date forward, American process innovations
improved materials of construction and operating costs to the
point that the process became the most economical method of
producing sulfuric acid from elemental sulfur. In addition to
these factors the process is designed to capture a high
percentage of the energy released by the exothermic chemical
reactions occurring in the oxidation of sulfur (S) to sulfur
trioxide (SO3J • This energy is used to produce steam which is
then utilized for other plant unit operations or converted to
electrical energy. It is the raw water treatment necessary to
condition water for this steam production that generates
essentially all the water effluent from this process.
In the period between 1930 and 1971, practically all contact
sulfuric acid plants built in the U.S. were designed with a
"single absorption" step (see Figure 3). The term "single
absorption" refers to the process point when sulfur trioxide
(SO3) gas is hydrolyzed with water to form product sulfuric acid
(H2.SCW) . This process step is performed after the gas has passed
through all the catalysis stages. Exit gas from a "single
absorption" stage generally contains sulfur dioxide (SO2) at a
concentration level appreciably in excess of the standard
established by EPA of 1.81 kg/kkg (4.0 lb/ ton) 10056 acid
produced. Since 1971, however, a process modification is being
offered which will allow compliance to the EPA standard. The
modification is the addition of a second absorption step and is
known as the "double absorption" process (Figure 4). It is most
likely that all future plants will utilize the double absorption
technique. Such a process modification will not affect the
characteristics or quantity of sulfuric acid plant water effluent
in any manner.
Process - Single Absorption
25
-------
k. TO ATMOSPHERE
FEED STREAM
TREATED H2O
(310 ~ 400 GAL/TON)
1300- 1670 l/kkg
SULFUR
FURNACE
CONVERSION
ABSORPTION
t BOILER SLOWDOWN
(5-10 GAL/TON)
j 21-40 l/kkg
1
(18,000
75,000
ACID
CIRC. TANK
PROCESS I-LO
2080 l/kkg
(450 ~ 500 GAL/TON)
(15- 20 GAL/TON)
63 - 83 l/kkg
STREAM LEGEND
—• MAIN LIQUID
— — — MAIN GAS
•_ '_\ MINOR
TON - SHORT TON
FIGURE 3
SULFURIC ACID PLANT (SINGLE CATALYSIS)
FLOW RATES PER TON 100% H2SO4
20,000 GAL/TON)
83,000 l/kkg
-------
STREAM LEGEND
MAIN LIQUID
t
I
OFF GAS
FEED STREAM
1670 l/kkg
1875 ~ 2080 l/kkg
(450 ~ 500 GAL/TON)
BLOW DOWN
T
MAIN GAS
[ MINOR
75,000 ~ 83,500 l/kkg
(8,000 ~ 20,000 GAL/TON)
ED
R
:E
i_| r\ 1
H20 |_
BOILER
r*
v 1
STEAM
1
WASTE
HEAT
BOILER
BLOWDOWNl .
5-10 GAL/TON) 21
t
i
^
T
*-*
CONVERSION
+-T-
|_ 1
~ 40 l/kkg ~~1 !
i !
ACID
COOLING &
PUMPING
ABSORPTION
-J
INTERSTAGE
ABSORPTION
PRODUCT
PROCESS WATER
(15
63.
20 GAL/TON)
83 l/kkg
TON - SHORT TON
FIGURE 4
SULFURIC ACID PLANT - DOUBLE CATALYSIS
FLOW RATES PER TON 100% H,,SO4
-------
The raw materials used to produce sulfuric acid by the contact
method are elemental sulfur, air and water. Molten elemental
sulfur is sprayed into a dry air stream inside a furnace. The
elevated furnace temperature auto-ignites the atomized liquid
sulfur to oxidize it to sulfur dioxide (S0£). This reaction
releases a large quantity of heat which causes the temperature of
the resultant SO2 - excess air mixture to rise to 980 - 11UO°C
(1800-2000°F) as it exits from the furnace. The heated gas
mixture flows to a boiler for heat removal. Sufficient heat is
removed to reduce the gas mixture temperature to the initial
reaction condition for optimum chemical conversion of SO2 to S03.
SO2 conversion to SO3_ takes place in a series of three or four
steps. Each conversion~step takes place under a a different
reaction condition to achieve the most complete conversion of SO2_
to S03 possible. This conversion efficiency in a single
absorption process is approximately 98%.
Following the conversion stages, the SO3 gas flows to the bottom
of an absorption tower. In the tower the SO3_ gas flows upward
through ceramic packing and counter-current to downward flowing
98-99% H2SOU. The SO3 is readily hydrolyzed to H2SOU by the
water in the acid. Hydrolysis of the SO3 to E2SOJ4 also releases
heat which increases the temperature of the enriched 98-99% H2SCW
acid. After the acid exits the tower it flows through cooling
coils to offset the temperature increase and then to the pump
tank. From this tank it is again recycled through the absorption
tower.
At the start of the process discussion, it was mentioned that the
molten sulfur is burned in a dry air stream. The drying of the
atmospheric air used in the process is accomplished in the drying
tower. Here moist atmospheric air enters the base of the tower
and flows upward counter-currently to concentrated sulfuric acid
pumped from the pump tank. This acid has, however, been diluted
from the normal 98-99% H2SOU. acid in the pump tank to
approximately 93%. The resultant moist air, 93% acid contact,
removes moisture from the air stream yielding dry air and a
slightly further diluted acid. In turn the dry air flows to the
furnace and the diluted acid flows back to the pump tank for
mixing with the stronger 98-99% acid flowing back from the SO3_
absorption tower.
The product is that acid flowing into the pump tank which is in
excess of drying and absorbing tower recycle requirements.
Adjustments to the rate of product acid removal from the pump
tank are determined by monitoring the pump tank level and
maintaining it at a constant level. The excess (product) acid is
diluted with water to the desired product acid concentration
(normally 93% H2SOU) before it is pumped to storage.
Process - Double Absorption
As previously mentioned it is most likely that all new plants
built in the United States in the future will be double
28
-------
absorption process units. The feature which makes this process
different from the single absorption process described above is
the addition of a second absorption tower. This second tow^r is
installed at a point intermediate between the first and final SO2
to SO3 catalytic conversion steps. Utilization of this second
absorption tower permits the achievement of a greater SO2J
conversion to SO3 and thus a significantly reduced quantity of
SO2 in the plant effluent gas stream. Double absorption plants
realize SO2 conversion efficiencies of 99.5+ % as compared to
single absorption plant efficiencies of approximately 98%. Both
processes have the same water effluent in respect to both
quantity and contaminant levels.
29
-------
Phosphate Rock_Grinding
Process Description
General
Phosphate rock that has been mined and beneficiated is generally
too coarse to be used directly in acidulation to phosphoric acid.
The rock is, therefore, processed through equipment to
mechanically reduce it to the particle size required for optimum
phosphoric acid plant process efficiency.
Process
Size reduction is accomplished with ball, roll or bowl mills.
Phosphate rock is fed into the mills and mechanically ground
(Figure 5). After the rock enters the mill system, all flow
through the sizing and reclamation circuits is by pneumatic
means. Air is constantly exhausted from the mill system to
prevent precipitation of moisture generated from the rock as a
result of grinding. Normally, the exhaust air passes through a
bag type air cleaner to remove entrained rock particulates before
discharge to the atmosphere.
Phosphate rock size reduction in all existing fertilizer plants
is an entirely dry processing circuit and does not directly
involve liquid streams. Minor quantities of water are used for
indirect cooling of lubricating oil and mechanical equipment such
as bearings.
Some future rock grinding operations will utilize a wet grinding
circuit rather than the current dry grinding practice. This
change is prompted by a combination of lower capital costs and
the elimination of the gas effluent streams associated with both
the rock drying and grinding operations. Use of this new
technique will not change the self-contained nature of the rock
grinding circuit. There will be no liquid effluents other than
those mentioned in the dry grinding process.
30
-------
u>
LEGEND
— MAIN ROCK
MINOR ROCK
1 pun?; RnrK 1 ^
COOLING WATER
(8~ 150 GAL/TON) |
EXHAUST AIR
t
33~625l/kkg GRINDING ^ DUST
MILL * COLLECTOR
COOLING WATER ]
(8~ 150 GAL/TON)
33 ~ 625 l/kkg
1
'ON ~ SHORT TON
t 1
' ^ oo/-vrvi I/~T
FIGURE 5
ROCK GRINDING
FLOW RATE PER TON ROCK
-------
Phosphate Rock_pigegtionm6.Filtration
Process Description
General
Phosphoric acid is the basic building block from which
essentially all mixed fertilizer used in the U.S. is made. The
overwhelming majority of this acid is manufactured by the wet
process method. The process involves changing the state of the
phosphate content in phosphate rock from a practically water
insoluble to a water soluble compound. This is accomplished by
solubilizing the phosphate rock with a highly ionized acid. Acid
type is selected through a combination of factors including cost,
simplicity of process, materials of construction, and the desired
end products. In the U.S., sulfuric acid is by far the most
commonly used acid, but other acids, such as nitric and
hydrochloric, can be utilized.
A statistical compilation of U.S. phosphoric acid producers is
shown below. The figures show the relative importance of the
three mentioned acid treatment processes and indicates the most
prominent process.
Annual
Type of Acidulation Number of Operat- P2O5 % of Total
Process i_ing_Plants kkg;/y.ear Production
Sulfuric Acid
Nitric Acid
Hydrochloric Acid
35*
4
0
4,879,000
61,000
0
98.77
1.23
o
39
4,940,000 100.00*
*Including three plants restarted in 1973.
All the acidulation processes have inherent problems with process
effluents, both gaseous and water, as well as by-product
disposal. Successful and acceptable by-product storage and
processing of plant effluents is to a large degree dependent upon
the considerations made for such items during the original plant
layout stages. It is much more difficult and possibly
economically impractical in some cases to add such facilities to
an existing plant. Sizable acreage and reasonably good soil
compaction characteristics are required to handle the effluent
and by-product processing arrangements. Those plants located in
areas where land is not available and/or soil stability is poor
are at a great disadvantage. Particular reference is to those
installations in Texas and Louisiana.
32
-------
Phosphoric Acid
Process Description
Sulfuric Acid Acidulation
The raw materials used in this process are ground phosphate rock,
93X sulfuric acid, and water. Phosphate rock is mixed with the
sulfuric acid after the acid has first been diluted with water to
a 55-70X H2SOU concentration. This mixing takes place in an
attack vessel of sufficient size to retain the raw material mix-
ture for several hours (Figure 6) . The simplified overall
chemical reaction is represented by the following equation:
3 Ca3 (PO4)2 (solid) + 9 H2S04. (liq) + 18 H2O (liq)
Phos. Rock Sulf. Acid Water
-> 6 H3POU (liq) + 9 CaSOU . 2H2O (solid)
Phos. Acid Gypsum
In reality phosphate rock is not the pure compound indicated
above, but a fluorapitite material containing minor quantities of
fluorine, iron, aluminum, silica and uranium. Of these the one
presenting the most serious overall process problem is fluorine.
Fluorine is evolved from the attack vessel and other plant
equipment as either the gaseous compound silicon tetrafluoride
(SiFjf) or hydrofluoric acid (HF) . SiFj* hydrolyzes very quickly
in moist air to fluosilicic acid (H2SiF6) and silica (SiO2) . Both
and HF can be collected in a wet scrubber unit.
Additional fluorine remains in the by-product gypsum in a variety
of fluorine compounds. The combination, therefore, of absorbed
gaseous fluorine effluent and the soluble fluorine compounds in
the gypsum are a major contaminant in the phosphoric acid plant
effluent streams.
Following the reaction in the digester, the mixture of phosphoric
acid and gypsum is pumped to a filter which mechanically
separates the particulate gypsum from the phosphoric acid
(approx. 3Q% P2O5 concentration) . The magnitude of the by-
product gypsum is best appreciated by the fact that the
production of each kkg of P2°j> as phosphoric acid creates
approximately five (5) kkg of gypsum. Normally the gypsum is
sluiced with contaminated water from the plant to a disposal
area. The phosphoric acid separated from the gypsum is collected
for further processing.
33
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PHOSPHATE
ROCK
CONTAMINATED
WATER
u>
-p-
(0 ~ 4500 GAL/TON)
0~ 19,000 l/kkg
COOLING WATER OUT
(2500 ~ 3500
GAL/TON)
11000~ 14500
j l/kkg
OFF GAS
_^_
I
I
I
TO ATMOSPHERE
•CONTAMINATED WATER
(1300~ 1500 GAL/TON)
5400 ~ 6300 l/kkg
(1300~ 1500 GAL/TON)
5400 ~ 6300 l/kkg
CONTAMINATED
WATER
14,500 l/kkg
3500 GAL/TON)
PRODUCT
ACID
STREAM LEGEND
MAJOR LIQUID
MINOR LIQUID
MINOR GAS
FIGURE 6
WET PROCESS PHOSPHORIC ACID - H2SO4 ACIDULATION
FLOW RATE PER TON PO
-------
Phosphoric Acid
Process Description
Nitric Acid Acidulation
There are two different nitric acid acidulation processes which
have been used commercially in the United States. One of these
has been discontinued within the past year and currently only one
is being used for fertilizer production.
Nitric acid acidylation differs from the sulfuric acid
acidulation process in that phosphoric acid is not separated as a
product from the acidulation reaction mixture. Consequently, the
division of process steps between acidulation and the final
fertilizer product is not possible.
The raw materials used are generally unground phosphate rock and
57% nitric acid. Nitric acid and the rock are mixed together in
a series (12-15) of violently agitated small reactor vessels
(Figure 7). The first few vessels serve primarily to dissolve
the rock according to the following chemical reaction.
Ca3(POl)2 + 6HN03 —+ 3Ca (NO3) 2 + 2H3POU
Phos. Rock Nitric Acid Calcium Phos. Acid
Nitrate
This reaction essentially places both the reaction products,
calcium nitrate and phosphoric acid, in a mixed liquid form. At
this point either purchased phosphoric or sulfuric acid is added
to the process together with ammonia to produce a specific mix of
calcium compounds, ammonium nitrate, and phosphoric acid. This
mixture is then converted to a dry product. The fertilizer
grades produced from this mixture are limited both as to number
and water soluble phosphate content.
35
-------
FEED STREAM
TON ~ SHORT TON
DIGESTION &
AMMONIATION
DRYING
GRANULATION
SIZING
TO ATMOSPHERE
I
i
i
—i
PRODUCT
OFF GAS
SCRUBBER
FIGURE 7
NPK PROCESS NITRIC ACID ACIDULATION
STREAM LEGEND
MAIN FLUID
MAIN GAS
CONTAMINATED
WATER
1000'
(240-
2300 l/kkg
540 GAL/TON)
CONTAMINATED
WATER
1000- 2300 l/kkg
(240 ~ 540 GAL/TON)
FLOW RATE PER TON P2O5
-------
Phosphoric_Acid Concentration
Process Description
General
Phosphoric acid as produced in the sulfuric acid acidulation
process is generally of too low in concentration (26-30% P205) to
qualify as either a salable product or to be used for processing
a final dry fertilizer product. This P205 level can be increased
to the 40-5456 P2O5 range by processing the acid through water
evaporation units.
Process
Phosphoric acid concentration to 54% P£C)5 is performed with low
pressure steam as the heat energy source for the evaporation of
water from the acid. Evaporation is accomplished by circulating
acid at a high volume rate consecutively through a shell and tube
heat exchanger and a flash chamber under vacuum pressure
conditions. The flash chamber serves to provide a comparatively
large liquid surface area where water vapor can be easily
released without incurring significant phosphoric acid en-
trainment losses. Inherent with the water evaporation is also
volatilization of minor acid impurities, the principal one being
fluorine. The evolved fluorine together with very minor
quantities of phosphoric acid pass to a barometric condenser and
contaminate the condenser water.
37
-------
STEAM
CONTAMINATED WATER
PHOSPHORIC ACID
00
STEAM
CONDENSATE
f"
J
EJCT
EVAP.
I
PUMP SEAL WATER
(.2 ~ .4 GAL/TON)
.83 ~ 1.6 l/kkg
STREAM LEGEND
MAIN LIQUID
MAIN GAS
| MINOR
CONCENTRATED
PHOSPHORIC ACID
CONTAMINATED WATER
(550 ~ 570 GAL/TON)
2500 ~ 2600 l/kkg
TON ~ SHORT TON
FIGURE 8
WET PHOSPHORIC ACID CONCENTRATION
FLOW RATE PER TON PO
-------
Phosphoric Acid Clarificgtion
Process Description
General
Phosphoric acid after concentration to a 52-54% P2O5 level
becomes a supersaturated solution to a variety of minor acid
impurities, namely iron and aluminum phosphates, soluble gypsum,
and fluosilicates. These impurities are present in quantities
sufficient to create an appreciable solids accumulation during
acid storage. In turn this causes tank car unloading and
customer processing problems. It is, therefore, necessary to
remove these precipitated impurities before the acid can be
considered a salable product.
Process
The process used in the U.S. for removal of precipitated solids
from 54% P2O5 phosphoric acid involves only physical treatment of
the acid rather than the more complicated and expensive solvent
extraction processes utilized in Europe and Mexico (Figure 9).
The acid is conditioned at the proper temperature and time
necessary to realize the degree of solids precipitation required
to meet the clarified acid product specifications. The
precipitated impurities are then physically separated from the
acid by settling and/or centrifugation.
Water usage in this process is limited to indirect cooling of the
acid and minor quantities for equipment washing.
39
-------
CONCj PHOS. ACID
WATER IN
,165~ 770 GAL/TON)
690 ~ 3200 l/kkg
WATER OUT
(165 ~ 770 GAL/TON)
690 ~ 3200 l/kkg
SOLIDS
REMOVAL
SOLIDS PLUS
ACID
MERCHANT GRADE ACID
TO DRY FERTILIZER
MANUFACTURER
TON ~ SHORT TON
FIGURE 9
MERCHANT GRADE PHOSPHORIC ACID CLARIFICATION
FLOW RATE PER TON P0OC
-------
Normal Superphosphate
Process Description
General
Normal superphosphate was, for many years, by far the most
popular phosphate fertilizer. Since the mid-fifties, however,
this popularity has been in a sharp decline and only in the past
few years has the rate of decline started to moderate. The
market share of this fertilizer has fallen from 68% in 1957 to
42% in 1965 and now appears leveling off at approximately 18%.
The major reasons for this decline include such items as low P205
content (2C%) with the associated increased cost of
transportation per ton of nutrient and the trend to larger size
plants.
Normal superphosphate can be manufactured in small inexpensive
plants with low production costs per ton of P2.O5. The process is
simple and easy to operate requiring less sulfur per ton of P205_
than the production of phosphoric acid. The combination of low
investment and simplicity together with recognition of the
adverse fertilization effect of sulfur deficiency in the soil
assures that normal superphosphate production will not die out
but sales will be limited to an area in close proximity to the
plant site.
Process.
The two raw materials used in the production of normal superphos-
phate are 65-75% sulfuric acid and ground phosphate rock. Re-
action between these two materials is both highly exothermic and
rapid (Figure 10). The basic chemical reaction is shown by the
following equation:
Ca3(POU)2 + 2H2SOU + H2O —*• 2CaSOU.2H2O + Ca (H2POU) . H20
Phosphate Sulfuric Water Gypsum Normal Superphos-
Rock Acid phate
The interval of fluidity before the two reactants solidify is
very brief and the mixture is quickly transferred to an enclosed
space referred to as a den. This den may be either an
essentially stationary structure or a continuous slow moving
conveyor. In the den the material becomes plastic relatively
quickly. During this phase there is a copious evolution of
obnoxious gas as the crystallization process progresses.
Retention time in the den can range from 1 to U hours dependent
on the overall process conditions. At the end of this time the
material becomes a porous mass resembling a honeycomb and is
removed from the den to storage. A storage period of 3 to 8
weeks is required for "curing" before the normal superphosphate
is an acceptable product for shipment. The "curing" time serves
to allow completion of the chemical reaction between the rock and
41
-------
CLARIFIED OR CONTAMINATED WATER
940- 1040 l/kkg
(225 ~ 250 GAL/TON)
TO ATMOS.
SULFURIC ACID
PHOSPHATE ROCK
c
STREAM LEGEND
——— MINOR PROCESS
GAS
MAIN PROCESS
TONS ~ SHORT TONS
I
t
CONTAMINATED WATER
(225 ~ 250 GAL/TON)
940- 1040 l/kkg
N.S. TO CURING
FIGURE 10
NORMAL SUPERPHOSPHATE
FLOW RATE PER TON N.S.
-------
acid with the subsequent decrease in free acid and citrate
insoluble P2O5 content.
43
-------
Triple Superphosphate
Process^Description
General
Triple superphosphate (TSP), with its 46.0% - 48.5% P2O5 content,
is a high analysis phosphate fertilizer. As such, it provides
transportation economy which has been instrumental in enlarging
its share of the phosphatic fertilizer market.
This product has in the 1950-1965 period taken over much of the
market lost by normal superphosphate and currently accounts for
approximately 24% of the total phosphatic fertilizer market.
TSP's share of the market for the near future is expected to
remain relatively constant primarily because of the tremendous
growth of the ammonium phosphates. TSP production, unlike normal
superphosphate, can be most economically produced close to the
phosphate rock source. In the U.S. this means that approximately
83% of the total production is manufactured in Florida.
Process
There are two principal types of TSP, Run-of-Pile (ROP) and
Granular Triple Superphosphate (GTSP). Physical characteristics
and processing conditions of the two materials are radically
different. ROP material is essentially a non-uniform pulverized
material which creates difficult air pollution problems in
manufacture as well as difficult materials handling problems in
shipment. GTSP is a hard, uniform, pelletized granule produced
in process equipment which permits ready collection and treatment
of dust and obnoxious fumes. Most new plants will be of the GTSP
type.
Both processes utilize the same raw materials, ground phosphate
rock and phosphoric acid. The basic chemical reaction is shown
by the following equation:
Ca3 (P04J2 + 4H3P04 + 3H2O —*• 3Ca (H2PO4)2.H2O
Phosphate Phosphoric Water Triple Superphosphate
Rock Acid (Monocalcium phosphate)
At this point the similarity between the two processes ends.
The ROP process is essentially identical to the normal superphos-
phate process with the exception that phosphoric rather than sul-
furic acid is used as the acidulating acid (Figure 11). Mixing
of the 46-54% P2O5 phosphoric acid and phosphate rock normally is
done in a cone mixer. The cone depends solely on the inertial
energy of the acid for mixing power. On discharge from the mixer
the slurry quickly (15-30 sec) becomes plastic and begins to
solidify. Solidification together with the evoluation of much
obnoxious gas takes place on a slow moving conveyor (den) enroute
to the curing area. The solidified material because of the gas
evolution throughout the mass takes on a honeycomb appearance.
44
-------
CLARIFIED OR CONTAMINATED WATER
940 ~ 1040 l/kkg
(225 ~ 250 GAL/TON)
STREAM LEGEND
MAIN PROCESS
GAS
MINOR PROCESS
PHOSPHORIC ACID
PHOSPHATE ROCK
C
Ln
TON ~ SHORT TON
TO ATMOS.
CONTAMINATED WATER
ROP ~ TSP TO CURING
(225 ~ 250 GAL/TON)
940 ~ 1050 l/kkg
FIGURE 11
TRIPLE SUPERPHOSPHATE
(RUN-OF-PILE R.O.P.)
FLOW RATE PER TON ROP ~ TSP
-------
At the point of discharge from the den the material passes
through a rotary mechanical cutter which breaks up the
honeycombed ROP before it discharges onto the storage (curing)
pile. Curing occurs in the storage pile and takes 2-U weeks
before the ROP is ready to be reclaimed from storage, sized and
shipped.
GTSP is produced quite differently (Figure 12). The phosphoric
acid in this process is appreciably lower in concentration (U0%
P2O5) than the U6-5U% P2O5 acid used in ROP manufacture. Forty
percent P2_O5 acid and ground phosphate rock are mixed together in
an agitated tank. The lower strength acid maintains the
resultant slurry in a fluid state and allows the chemical
reaction to proceed appreciably further toward completion before
it solidifies. After a mixing period of 1-2 hours the slurry is
distributed onto recycled dry GTSP material. This distribution
and mixing with the dry GTSP takes place in either a pug mill or
rotating drum. Slurry wetted GTSP granules then discharge into a
rotary drier where the chemical reaction is accelerated and
essentially completed by the drier heat while excess water is
being evaporated. Dried granules from the drier are sized on
vibrating screens. Over and under-size granules are separated
for use as recycle material. Product size granules are cooled
and conveyed to storage or shipped directly.
46
-------
STREAM LEGEND
" MAIN PROCESS
GAS
MINOR PROCESS
CLARIFIED OR CONTAMINATED WATER
660
(158
750 l/kkg
180 GAL/TON)
TO ATM OS.
CONTAMINATED
WATER
(5 ~ 10 GAL/TON)
21 ~ 40 l/kkg
TON ~ SHORT TON
GTSP OUT
FIGURE 12
GRANULATED TRIPLE SUPER PHOSPHATE
FLOW RATE PER TON GTSP
-------
AmmQnium^Phosphates
Process Description
Gengral
The ammonium phosphate fertilizers are highly concentrated
sources of water soluble plant food which have had a spectacular
agricultural acceptance in the past twenty years. Production
capacity of diammonium phosphate (DAP) has increased at a
compounded rate of 19.8% annually over the last ten years. The
popularity of the ammonium phosphates results from a combination
of factors. These include the ready adaptability of the
production processes to ever increasing single plant capacities
with thei£ associated lower production costs; favorable physical
characteristics which facilitate storage, handling, shipping and
soil application; compatibility with all common fertilizer
materials; transportation economies effected by the shipment of
high nitrogen (18%N) and phosphate (46% P2O5) nutrient content at
a single product cost; and the ability of an N-P-K fertilizer
producer to realize up to twice the profit margin per kkg of P2O5
from DAP than from concentrated superphosphate. Such an
impressive number of plus factors insure that ammonium phosphate
processing (particularly DAP) will continue to be an important
segment of the fertilizer industry.
Ammonium phosphate fertilizers include a variety of different
formulations which vary only in the amounts of nitrogen and phos-
phate present. The most important ammonium phosphate fertilizers
in use in the U.S. are:
Mgnoammonium (MAP} Phosphates
"""11 -~48~- 0
13-52-0
11-55-0
16-20-0
Diammonium Phosphates (DAP)
16 -~48~- 0
18-46-0
Diammonium phosphate formulations are produced in the largest
tonnages with DAP (18-46-0) being the most dominant.
Process
The two primary raw materials used to produce ammonium phosphates
are ammonia and wet process phosphoric acid. Sulfuric acid is of
secondary importance but is used in the production of the mono-
ammonium phosphate grade 16-20-0. As mentioned above, the
various grades vary only in the amounts of nitrogen and phosphate
present. It is primarily the nitrogen that varies and this is
accomplished by controlling the degree of ammoniation during
neutralization of the phosphoric acid. The chemical reactions
involved are indicated by the following equations:
48
-------
H3PO4 + NH3 —*• NH4H2P01
Phosphoric Ammonia Monoammonium
Acid Phosphate
* H2S04 + 2NH3 —* (NH4)2SOU
Sulfuric Ammonia Ammonium
Acid Sulfate
* This reaction occurs only in the production of 16-20-0 and
occurs concurrently with the mon©ammonium phosphate reaction.
The processing steps (Figures 13 and 1U) are essentially
identical to those described in the triple superphosphate GTSP
process. Ammonia, either gaseous or liquid, is reacted with 30-
HQ% P2O5 phosphoric acid in a vertical cylindrical vessel which
may or may not have mechanical agitation. The resultant slurry
is then pumped to a mixer where it is distributed onto dry
recycled material. Distribution and mixing takes place in either
a pug mill or rotating drum. Wetted granules then discharge into
a rotary drier where the excess water is evaporated. Dried
granules are separated for use as recycle material. Product size
granules are cooled and conveyed to storage or shipped directly.
49
-------
Ul
o
CLARIFIED OR CONTAMINATED WATER
5000 ~ 6500 l/kkg
(1200 ~ 1500 GAL/TON)
PHOSPHORIC ACID
NH,
^— fc,
1
'f"
REACTOR
NH-
f-
I I
I
1
GRANULATOR
1' I
DRYER
TO ATMOS
CONTAMINATED
WATER ^
(0~ 72 GAL/TON)
0 ~ 300 l/kkg
MAP TO STORAGE
TON ~ SHORT TON
STEAM LEGEND
• • MAIN PROCESS
GAS
MINOR PROCESS
FIGURE 13
MONOiAMMONIUM PHOSPHATE PLANT
FLOW RATE PER TON MAP
-------
PROS. ACID
Ln
CONTAMINATED WATER
(1200 ~ 1500 GAL/TON)
5000 ~ 6500 l/KKg
, r CONTAMINATED WATER
(1200- 1500 GAL/TON)
5000 ~ 6500 l/KKg
GRANULATION
DRYING
SIZING
DAP
TON-SHORT TON
FIGURE 14
Dl AMMONIUM PHOSPHATE PLANT
FLOW RATE PER TON DAP
-------
Nitrogen Fertilizer^Industry
The nitrogen fertilizer industry is composed of four basic
process plants: ammonia, urea, ammonium nitrate and nitric acid.
Ammonia is the basic nitrogen fertilizer constituent. It car.
either be used as the raw material feed stock for urea ammonium
nitrate and nitric acid or it can be used directly as a
fertilizer providing the highest amount of available nitrogen per
kkg of any of the nitrogen fertilizers.
For the most part, nitrogen fertilizer plants exist, or will be
built, without the interference of a phosphate fertilizer plant.
That is, if there happens to be phosphate fertilizer units at the
same plant site as nitrogen fertilizer units, they are or would
be sufficiently separated so that their waste water effluent
streams can be treated individually. However, the nitrogen
fertilizer plants, in many cases, are very closely integrated and
their waste water effluent streams intermixed.
The dependency of the three other plants on an ammonia plant can
be seen from the process descriptions. Although there are
isolated ammonia plants there are few cases where any of the
other process plants, whose production goes for nitrogen
fertilizers, exist by themselves. A nitric acid plant will be at
the same site as an ammonium nitrate plant and an urea plant will
be located next to an ammonia plant. In many cases all four of
these plants will be at the same plant site. (See Table 1).
52
-------
Ammonia
Procegs^Description
Ammonia, being the base component for the nitrogen fertilizer
industry, is produced in larger quantities than any other
inorganic chemical except sulfuric acid. The total U.S.
production in 1971 was 16,000,000 kkg (17,650,000 short tons)
with an expected 1972 total close to 16,500,000 kkg (18,200,000
short tons). The size of an ammonia plant will range from less
than 90 kkg/day (100 tons/day) to larger than 1,360 kkg/day
(1,500 tons/day) with the newer plants being the larger sizes.
Ammonia is produced by the reaction of hydrogen with nitrogen in
a three to one (3:1) volume (mole) ratio.
N2 + 3H2 —» 2NH3
This reaction is carried out in the presence of an iron promoted
metal oxide catalyst at elevated pressure, which favors the
ammonia formation, in a special reaction vessel (converter)
(Figure 15). Pressure in the converter will range from 130 atm
(1930 psig) to 680 atm (10,100 psig) for the smaller plants, less
than 550 kkg/day (600 tons/day), using reciprocating compressors
to operate at higher pressures and for larger plants, greater
than 550 kkg/day (600 tons/day), operating at lower pressures
using centrifugal machines for gas (syn gas) compression. This
reaction is exothermic and care must be taken to obtain the
optimum temperature which favors both the ammonia equilibrium and
rate of reaction. Most of the ammonia converters will operate at
temperature from 338°C (550°F) to 421°C (700°F).
Since at these operating conditions, the conversion of hydrogen
and nitrogen to ammonia is on the order of 10% to 20%, a
considerable quantity of reaction gas (hydrogen, nitrogen,
methane, argon, other inerts, and ammonia) must be cooled to
condense ammonia, recompressed, mixed with fresh make-up gas (syn
gas) and reheated for recycle to the ammonia converter.
The ammonia product, after pressure reduction, is stored in
either large atmospheric tanks at a temperature of -33°C (-28°F)
or in large spheres or bullets at pressures up to 20 atm (300
psig) at ambient temperatures.
The above process description normally describes the "back end"
of an ammonia plant, the ammonia synthesis section, with the
"front end" being designed for the production of the syn gas
(make-up feed to ammonia synthesis section). The "front end" of
an ammonia plant may range from a very simple gas mixing
operation to a very complex gas preparation operation depending
on the raw materials used. The raw material source of nitrogen
is atmospheric air and it may be used in its natural state as
compressed air to a gas preparation unit or as pure nitrogen from
an air plant to a gas mixing unit. Hydrogen, on the other hand,
is available from a variety of sources such as: refinery off-
53
-------
STEAM
MAKE-UP
WATER
STEAM
CARBON DIOXIDE
WASTE HEAT
BOILER
BOILER FEED
WATER BOILER
BLOW DOWN
(5 ~ 30 GAL/TON)
HEAT 20-125 l/KKg
01 I
o J
o I
GAS
REFORMING
£ I FUEL
NATURAL |
GAS
RAW
GAS
GAS
PURIFICATION
SYN. GAS
COOL
WATER
AIR
COMPRESSOR
SYN. GAS
COMPRESSOR
REFRIGERATION
COMPRESSOR
AIR
COMPRESSOR
SLOWDOWN
(30 ~ 50 GAL/TON) 125 ~ 200 l/KKg
PROCESS CONDENSATE
(5 ~ 200 GAL/TON)
20 ~ 835 l/KKg
AMMONIA
CONVERTER
tO
<
C3
CO
68
o
O
HEAT
EFFLUENT
| RECYCLE GAS
AMMONIA
CONDENSER
REFRIGERANT
AIR FROM ATMOS
COOLING WATER
TON - SHORT TON
FIGURE 15
AMMONIA PLANT
FLOW RATE PER TON AMMONIA
FROM CLARIFICATION
3 ~ GAL/TON
12.5~ 20.0 l/kkg
PRODUCT-LIQUID AMMONIA
COOLING TOWER
BLOW-DOWN
(400 ~ 800 GAL/TON)
1600~ 3200 l/KKg
-------
gas, coke oven off-gas, natural gas, naphtha, fuel oil, crude oil
and electrolytic hydrogen off-gas. At the present time, more
than 92% of the total ammonia produced in the United States uses
natural gas as its hydrogen source and feed to a gas preparation
unit, better known as a steam-methane reforming unit.
Since the steam-methane reforming unit is the most widely used
for syn gas preparation, its process description will be used for
describing the "front end". The steam-methane reforming "front
end" can be divided into the following:
a. Sulfur Removal & Gas Reforming
b. Shift Conversion
c. CO2 Removal
d. Methanation
In the sulfur removal and gas reforming section, natural gas at
medium pressures 14 atm (200 psig to 600 psig) is treated for the
removal of sulfur and high molecular weight hydrocarbons by
passing the gas through a bed of activated carbon. The natural
gas is then mixed v;ith steam and heated before being passed
through a bed of nickel catalyst in the primary reformer. In the
primary reformer the natural gas is reacted at temperatures
around 790°C (1,450°F) with the steam according to the following
reactions:
CxHy. + H2O —+ xCO + (y + y/2) H2 (Reform)
CO + H20 —* C02 + H2 (Shift Conversion)
The reforming reaction is only partially complete and the shift
conversion reaction proceeds only as far as the operating
temperature and pressure will permit.
The next piece of process equipment, the secondary reformer, is
•the location for the introduction of nitrogen as compressed air
at a quantity that will result in a 3:1 volume ratio (hydrogen to
nitrogen) in the final syn gas. The reactions which occur are
the completion of the reforming reaction above and the oxidation
of hydrogen to consume the oxygen in the compressed air feed.
One result of these reactions is an exit temperature in excess of
930°C (1,700°F). These hot gases then enter a high pressure
steam boiler, m atm to 102 atm (600 psig to 1,500 psig), and
then into the shift conversion section. The shift reaction (see
ahove) is favored by low temperatures and is carried out in two
steps with heat recovery between each step. The first step, high
temperature shift conversion, is carried out by passing the gas
through a bed of iron oxide catalyst while the second step, low
temperature shift conversion, takes place in conjunction with a
copper, zinc, chromium oxide catalyst at temperatures around
22C°C (425°F). Following additional heat recovery and cooling,
where necessary, the gas passes to the CO2 recovery section.
55
-------
The C02 recovery system is not complicated, but there are a
number of types of systems available and each one has its
advantages and disadvantages. The two systems most used in the
U.S. are one based on monoethanolamine (MEA) and a second one
based on hot potassium carbonate and its variations. In each of
these cases a circulating solution either absorbs or reacts with
the C02 in the gas stream reducing its concentration below 0.1%.
The CO2 rich solution is then regenerated in a stripper using
previously recovered heat with the CO2 and some water vapor being
exhausted to the atmosphere.
The final stage in syn gas preparation is to remove any traces of
CO and CO2 remaining. This is accomplished in a methanation unit
where the" gas is passed through, a bed of nickel catalyst
resulting in the following reactions:
C02 * 4H2 -» CH4 * 2 H20
CO + 3H2 —* CH4 * H20
After heat recovery and any necessary cooling the syn gas is
ready for compression and feeding to the ammonia synthesis
section.
56
-------
Urea
Process^Descriptiori
Urea is another major source of nitrogen fertilizer produced in
the United States. Some 4,900,000 kkg (5,400,000 short tons) of
urea were produced in the U.S. in 1971.
Basically, there are three urea production processes which differ
primarily in the way the unreacted ammonia and carbon dioxide are
handled.
A. Once-through Process - In this process, no attempt
is made to recycle these gases to the urea process.
The off-gases containing ammonia and carbon dioxide are
used in the production of fertilizer products.
B. Partial Recycle Process -» Excess ammonia is recycled
back to the process while any excess carbon dioxide is
vented to the atmosphere or used in another process.
C. Total Recycle Process - Both the ammonia and carbon dioxide
in the off-gas are recycled back to the urea process.
Currently, the total urea production is divided as follows: once
through, 18%; partial recycle, 12%; and total recycle, 70%.
All of the urea production in the United States is produced by
the reaction of ammonia with carbon dioxide which forms ammonium
carbamate (Figure 16). The ammonium carbamate is then dehydrated
to form urea.
2NH3 + C02 —* NH4CO2NH2
NH4C02NH2 —* NH2CONH2 + H2O
Most urea plants are located at the same plant site as a
correspondingly sized ammonia plant. The ammonia plant not only
supplies the needed ammonia, but also the high purity carbon
dioxide.
The carbon dioxide-ammonia reaction to form urea, ammonium
carbamate and water takes place in a reactor vessel at pressures
ranging from 137 atm (2,000 psig) to 341 atm (5,000 psig) and at
temperatures from 121°C (250°F) to 182°C (360°F) . Unreacted
ammonia and carbon dioxide are also present in the reactor exit
stream. The carbamate forming reaction is highly exothermic
while the carbamate dehydration reaction is slightly endothermic.
Under reactor operating conditions, the dehydration reaction
proceeds to 40% to 60% completion resulting in an overall net
exothermic heat effect. After separation of the ammonia, carbon
dioxide and ammonium carbamate, the resulting solution will be
about 70% to 80% urea. Depending upon product specification this
70-80% solution can be used as is or it can be further
concentrated to a solid product. This solid product can be
formed by prilling, crystallation or a combination of both. The
57
-------
PROCESS WATER,
BOILER FEED
WATER
TREATMENT
3.
EFFLUENT
(10 ~30 GAL/TON)
40~125l/KKg
AMMONIA v
(115~230GAL7TON)
CARBON DIOXIDE
Oi
oo
COOLING H2O
MAKE-UP
WATER
i
ERY ~*
DE
i
UJ
Q
>• X
O
CAR BOND
* COOLING H20
CARBON DIOXIDE
COMPRESSOR
1
FOR -
|
-+
TO
AMMONIA & CARBON"
DIOXIDE
480~960l/KKg
OTHER PROCESSES
R& WATER VAPOR
<
^
EVAPORATOR
HEAT
*•••«••
STRIPPER
1'
— ¥
L
AIR & WATER VAPOR
HEAT
t
COOLING TOWER
PRILL
TOWER
CLARIFICATION
8.3
EFFLUENT
- 3 GAL/TON)
1251/KKg
AIR
UREA PRILLS
, ,UREA SOLUTION
TON-SHORT TON
BLOW - DOWN
(90 ~ 350 GAL/TON)
375 ~ 1460 l/KKg
FIGURE 16
UREA PLANT
FLOW RATE PER TON UREA
-------
concentration step takes place in flash evaporators designed with
minimum residence time to prevent the formation of biuret.
(NH2CONHCONH2 • H2O) This biuret has a deleterous effect on
crops. The basic disadvantage in selecting prilling versus
crystallization or a combination is the degree of biuret
formation. Prilling gives a product with about It biuret while
crystallization only has .IX. A combination of the two processes.
results in a biuret content of about .5%.
59
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Ammon i urn Ni trate
Process Description
Ammonium nitrate is a major source of nitrogen fertilizer in the
United States. The total production in the U.S. in 1971 was
7,800,000 kkg (8,600,000 short tons). It is an excellent
fertilizer being high in nitrogen (35%) and relatively low in
cost.
Ammonium nitrate is made by reacting ammonia with nitric acid:
NH3 + HNO3 -*• NH4N03
This reaction is carried out in a low pressure vessel called the
neutralizer (Figure 17). The high heat of reaction causes flash
vaporization of water with some ammonia and nitrate going
overhead leaving behind a liquid product which is 83% by weight
ammonium nitrate. This product known as AN solution can be sold
or it can be further processed into a dry product. The overhead
vapors from the neutralizer may lead to an air pollution problem
or if condensed, will have to be treated before being discharged.
If a dried product is desired, then the 83% AN solution is first
concentrated up to 95% AN and then either prilled or
crystallized. If prills are to be the final form of the ammonium
nitrate, the concentrated solution is pumped to the top of a 15
meter (150 ft.) to 61 meter (200 ft.) tower where it is sprayed
downward into a rising flow of air. As the ammonium nitrate
droplet forms it is solidified before it hits the bottom of the
tower. These prills are then further dried to reduce the
moisture to less than 0.5%. Following cooling, the prills are
then coated with an anti-caking agent such as clay. Concentrator
and prill tower air exhausts can contain significant amounts of
fine particulate ammonium nitrate which represents both a
significant air pollution problem and an indirect water pollution
source via runoff and washoff.
A final dry crystalline ammonium nitrate product requires that
the solution from the concentrator (95% AN) be fed to a
continuous vacuum evaporation crystallizer. The cooling of the
solution in the crystallizer causes crystals to form. A side
stream of crystal solution is taken from the crystallizer and fed
to a centrifuge for crystal separation. The centrifuge supernate
is recycled back to the crystallizer. The crystals are removed
from the centrifuge, dried to less than 0.1% water, cooled and
coated with an anti-caking agent.
60
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B FW
TREATMENT
EFFLUENT
(3 ~ 17 GAL/TON)
12.5 ~ 71 l/KKg
AIR & WATER VAPOR
PROCESS
CONDENSATE
(50 ~ 110 GAL/TON)
200~460l/KKg
AMMONIA
NITRIC ACID
NEUTRALIZER
HEAT
LU
X
EVAPORATOR
LU
X
CLARIFICATION
AMMONIUM NITRATE
SOLUTION
AAAA
PRILL
TOWER
CLARIFIED
WATER
AIR
COOLING TOWER
COOLING, DRYING
& COATING
BLOW - DOWN
(20
83.5
40 GAL/TON)
~ 167 l/KKg
AMMONIUM NITRATE PRILLS
EFFLUENT
(2 ~ 350 GAL/TON)
8.35 ~ 12.5 l/KKg
FIGURE 17
TON - SHORT TON
AMMONIUM NITRATE PLANT
FLOW RATE PER TON AMMONIUM NITRATE
-------
Nitric_Acid
Process Description
Nitric acid is produced by a number of processes in strengths
from 55% to 100% acid. In 1971 there were some 8,450,000 kkg
(9,300,000 short tons) of acid produced of which better than 80%
was used for and/or produced at nitrogen fertilizer complexes.
While varying strengths of acid are produced, the fertilizer
industry uses a dilute acid (55% to 65%).
Nitric acid is produced in the United States by the ammonia
oxidation process (Figure 18). In this process, ammonia .is
reacted with air to produce oxides of nitrogen which are then
further oxidized and absorbed in water producing a 55 to 65%
nitric acid. The following reactions occur in the process:
2NO + O2 —*• 2NO2
3N02 + H20 —> 2HN03 + NO
The initial ammonia oxidation reaction takes place in the
converter in the presence of a platinum-rhodium gauze catalyst at
pressures from atmospheric up to 9.2 atm (120 psig). The exit
gases from the converter may be in the temperature range of 705°C
(1,300°F) to 980°C (1,800°F) and are used to superheat steam and
preheat process air. The gases then pass through a waste heat
boiler to generate steam for the air compressor drive turbine and
for export. The quantity of steam generated by the process will
range from 500 to 1,000 kg/kkg (1,000 to 2,000 Ib/ton) of nitric
acid. By this time, due to the lower temperature, the second
reaction involving the oxidation of nitric oxide to nitrogen
dioxide has begun to occur. Following some additional cooling to
38-49°C (100-120°F), where some of the water is condensed and
forms nitric acid, the gases are passed up through an absorptipn
column. Some additional air is also passed up through the column
to oxidize the nitric oxide formed during the absorption step to
nitrogen dioxide. Water (fed to the top of the absorber) acts as
the absorbant giving product nitric acid out the bottom of the
column. The absorber temperature is held constant by cooling
water to improve the absorption efficiency. Cooling water
requirements will range from 104,000 to 146,000 1/kkg (25,000
to 35,000 gal/ton) of product.
The gases leaving the top of the absorber are fairly low in
nitrogen oxides but may be catalytically reacted to further
reduce these levels andf then depending on the process pressure,
passed through a hot gas expander to recover some of the energy
needed to drive the process air compressor. The differential
energy required for the air compressor can be supplied by a
helper turbine driven by the steam generated by the process.
62
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MAKE-UP WATER
TAIL GAS
1250 ~ 2500
,'KKg
1
COOLING
TOWER
(300 - 600
GALTONi
COOLING TOWER
BLOW DOWN
(20,000 ~ 40,000 GAL/TON)
83,000 - 167,000 l/KKg
AMMONIA
TON - SHORT TONS
(10 ~ 15 GAL/TON)
42 ~ 63 l/KKg
FIGURE 18
NITRIC ACID PLANT
FLOW RATE PER TON 100% NITRIC ACID
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SECTION IV
INDUSTRY CATEGORIZATIQN
The task of dividing the many fertilizer processes into specific
categories was considered one of the most important aspects of
the study. A particular objective was to have the least possible
number of categories in order to simplify the work of both
enforcement officials and industry in the monitoring of effluent
streams.
The factors considered in the overall categorization process
included the following:
1. Industry division
2. Problems with separation of individual process effluents
within a plant complex
3. Plant size
U. Plant age
5. Effect of raw material variations
6. Existence, type and efficiency of air pollution control
equipment
7. Land area available for waste water containment
utilization of wastes
8. Waste load characteristics
9. Treatability of wastes
10. Effect of rainfall - evaporation discrepancies
After completing the majority of the twenty-five (25) separate
plant visits it became clear that only a small number of the
above listed items had real overall meaning for categorization.
All items effect plant effluent conditions and quantities.
However, they do not all necessarily contribute to the
categorization of processes. The final factors used to establish
the categorization were:
1. Natural industry division
2. Waste load characteristics
3. Treatability of waste streams either by inter
process reuse or treatment technology
The application of these listed criteria resulted in the
establishment of 5 subcategories for the industry. These
together with their component processes are listed below:
A. PHOSPHATE SUBCATEGORY
1. Phosphate Rock Grinding
2. Wet Process Phosphoric Acid
3. Phosphoric Acid Concentration
a. Phosphoric Acid Clarification
5. Normal Superphosphate
6. Triple Superphosphate
7. Ammonium Phosphates
8. Sulfuric Acid
B. AMMONIA SUBCATEGORY
65
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C. Urea Subcategory
D. Ammonium Nitrate Subcategory
E. Nitric Acid Subcategory
Industry^Diyision
The fertilizer industry is composed of multi-product plants.
With few exceptions a phosphate complex does not include nitrogen
type processes (ammonia, urea, ammonium nitrate and nitric acid) .
This natural separation of the industry by the industry coupled
with the other following factors indicates that phosphate
fertilizer chemicals should constitute a separate category from
nitrogen fertilizer chemicals.
with Separation of Individual Process Effluent Within a
A somewhat surprising fact brought to light in the study was the
lack of information available on specific process effluents
within a complex. Fertilizer complexes are generally not
physically designed to keep individual process streams separate.
The reasons for this include: there previously was no reason to
do so; simplification of underground sewer systems meant joint
sewers and the practice of using effluent from one process as a
liquid in another process.
This rationale is appropriate for phosphate fertilizer complexes,
mainly because of the similar treatment technologies involved.
However, at nitrogen fertilizer complexes inadequate treatment of
pollutants will frequently result if the process waste waters
from each component chemical are not dealt with separately.
Plant Size
There is a wide range of plant sizes for most chemicals in the
fertilizer industry. However, plant size will not affect waste
water characteristics or treatability.
Plant Age
There is also a wide range of plant ages in the fertilizer
industry. This should not affect waste water characteristics or
treatability to the degree where any additional subcategorization
is required.
Effect of Raw Material Variations
Variations in the raw material will affect waste water
characteristics in operations involving phosphate rock and the
resultant phosphoric acid or phosphate. However, the effluent
limitations in such cases take these variations into account.
Another problem is that these variations are unpredictable and
difficult to monitor, making subcategorization based upon this
topic impracticable.
66
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Existence, Type and Efficiency of Air Pollution Contro1 Equipment
A major source of process waste water is from air scrubbers
employed at all plants. The treatment technologies proposed are
practicable regardless of the type or efficiency of air pollution
control devices, and subcategorization is not warranted.
Land Area Available for Waste Water Containment
Confinement of process waste water in large ponds is universally
practiced at phosphate fertilizer plants. These ponds range in
size from 65 to 570 hectares (160 to 1UOO acres). However,
extremely large ponds are not necessary to achieve the degree of
treatment necessary to recycle the process waste water. The
principal point is that the ponds now exist and need not be
expanded. Use of biological treatment of ammonia and nitrates in
nitrogen fertilizer plants would require space for treatment
ponds. If land availability is a problem, alternate methods of
ammonia and nitrate removal are available.
Waste Load Characteristics
The phosphate and nitrogen segments of the fertilizer industry
have different waste water characterics. For instance a
phosphate complex effleunt would be acidic due to phosphoric,
sulfuric, or nitric acids used in the process. A nitrogen
fertilizer complex would generally be alkaline due to ammonia.
Phosphates and fluorides will be present in the waste waters from
a phosphate complex, nitrogen compounds from a nitrogen
fertilizer complex. Within a nitrogen fertilizer complex the
different chemicals will involve different forms of nitrogen.
For instance, ammonia will naturally result from ammonia
synthesis. Ammonia and nitrates will result from ammonium
nitrate production. Ammonia and organic nitrogen will result
from urea synthesis. Such differences warrant subcategorization
of these latter chemicals.
TreatabilityofWastes
This is the principal factor used in determining
subcategorization. Production of all phosphate fertilizer
chemicals requires similar treatment methods (i.e.
neutralization, lime precipitation, and settling). The only need
for a discharge is during periods of excessive rainfall. No
process waste water is even generated in manufacturing nitric
acid. On the other hand urea, ammonium nitrate and ammonia can
each require a different treatment technique to achieve best
practicable and best available technologies.
Effect of Rainfall - Evaporation Discrepancies
Because of the almost universal use of ponds in the phosphate
fertilizer subcategory lengthy periods where rainfall exceeds
evaporation and/or periods of rainfall of abnormally high-
intensity necessitate a discharge. Rather than create a separate
67
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subcategory, this problem is better handled as a factor by which
the standards can be varied, since for any given month rainfall
could exceed evaporation at any location.
68
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SECTION V
WASTE CHARACTERIZATION
General
The intent of this section is to describe and identify the water
usage and waste water flows in each individual process. Each
type water usage and effluent is discussed separately and in-
cludes a tabulation indicating ranges of flow and contaminant
concentrations for each process. Flow figures are presented on a
per kkg of product basis to permit ready calculation of flow for
any specific production rate. Water flow information is also
presented on individual process water usage flowsheets to
pictorially indicate the various water flows relative to the
process equipment.
Phosphate Fertilizer Industry
The eight process operations - sulfuric acid, phosphate rock
grinding, wet process phosphoric acid, phosphoric acid
concentration, phosphoric acid clarification, normal
superphosphate, triple superphosphate, ammonium phosphates - in
the phosphate fertilizer subcategory have the following types of
water usage and wastes.
A. Water Treatment Plant Effluent
Includes raw water filtration and clarification, water
softening, and water deionization. All these operations
serve only to condition the plant raw water to the
degree necessary to allow its use for process water and
steam generation.
B. Closed Loop Cooling Tower Slowdown
C. Boiler Slowdown
D. Contaminated Water (Gypsum Pond Water)
E. Make-up Water
F. Spills and Leaks
G. Non-Point Source Discharges
These include surface waters from rain or snow that
become contaminated.
H. Contaminated Water (Gypsum Pond Water) Treatment
Each of the above listed types of water usage and wastes are
identified as to flow and contaminant content under separate
69
-------
headings. Detailed flow diagrams were previously presented in
Figures 3 through 14.
A.Water Treatment Plant Effluent
Basically only the sulfuric acid process has a water treatment
effluent. This 1300-1670 1/kkg (310-UOO gal/ton) effluent stream
consists principally of only the impurities removed from the raw
water (such as carbonates, bicarbonates, hydroxides, silica,
etc.) plus minor quantities of treatment chemicals.
The degree of water treatment of raw water required is dependent
on the steam pressure generated. Generally medium-pressure 9.5-
52 atm (125-750 psig) systems are used and do require rather
extensive make-up water treatment. Hot lime-zeolite water
treatment is the most commonly used.
There are phosphate complexes particularly along the Mississippi
River which use river water both for boiler make-up and process
water. In these plants it is necessary to treat the river water
through a settler or clarification system to remove the suspended
solids present in the river water before conventional water
treatment is undertaken. Effluent limitations for water
treatment plant effluent components are not covered in this
report. They will be established at a later date.
B•Closed Loop Cooling Tower Slowdown
The cooling water requirements and normal blowdown quantities are
listed in the following table. Effluent limits with respect to
thermal components and rust and bacteria inhibiting chemicals is
cooling tower blowdown or for once through cooling water are not
covered in this report, but will be established at a later date.
70
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Cooling Water
Process
Circulation Requirement
1/kkg gal/ton
Discharge Requirement
1/kkg gal/ton
Sulfuric Acid 75000-83000
(per ton 100%)
H2SOJJ
18000-20000 167C-2500
Rock Grinding
(per ton rock)
Phosphoric Acid
(per ton P2O5)
Phos. A. Cone.
(per ton P2O5)
33-625
0-19000
None
Phos. A. Clarifi- 690-3200
cation
(per ton P2O5)
Normal Super None
(per ton product)
Triple Super None
(per ton product)
Ammon Phos. None
(per ton product)
8-150
0-t500
None
165-770
None
None
None
33-625*
0-19000*
None
690-3200*
None
None
None
UOO-600
8-150*
0-4500*
None
165-770*
None
None
None
* Non-contaminated only temperature increase in
discharge water.
Closed loop cooling systems function with forced air and water
circulation to effect water cooling by evaporation. Evaporation
acts to concentrate the natural water impurities as well as the
treatment chemicals required to inhibit scale growth, corrosion,
and bacteria growth. Such cooling systems require routine
blowdown to maintain impurities at an acceptable operating level.
The blowdown quantity will vary form plant to plant and is
dependent upon overall cooling water circulation system.
The quality of the cooling system blowdown will vary with the
make-up water impurities and inhibitor chemicals used. The type
of process equipment being cooled normally has no bearing on the
effluent quality. Cooling is by an indirect (no process liquid
contact) means. The only cooling water contamination from
process liquids is through mechanical leaks in heat exchanger
equipment. Such contamination does periodically occur and
continuous monitoring equipment is used to detect such equipment
failures.
The table below lists the normal range of contaminants that may
be found in cooling water blowdown systems.
71
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Contaminant concentration
mg/1
Chromate 0-250
Sulfate 500-3000
Chloride 35-160
Phosphate 10-50
Zinc 0-30
TDS 500-10,000
SS 0-50
Biocides 0-100
Cooling tower blowdown can be treated separately or combined with
other plant effluents for treatment. The method to be employed
is dependent upon the chemical treatment method used and cost.
Those plants which utilize chromate or zinc treatment compounds
generally treat the blowdown stream separately to minimize
effluent treatment costs.
c • Bo j.ler^ Blowdown
The only steam generation equipment in a phosphate complex other
than possibly auxiliary package boilers is in the sulfuric acid
plant. Medium pressure, 9.5-52 atm (125-750 psig), steam systems
are the most generally used.
Boiler blowdown quantities are normally 1300-1670 1/kkg (310-400
gal/ton). Typical contaminate concentration ranges are listed
below. Separate effluent limitations for boiler blowdown with
respect to both thermal discharge and specific contaminants are
not covered in this report. They will be established at a later
date.
Contaminant Concentration
mg/1
Phosphate 5-50
Sulfite 0-100
TDS 500-3500
Zinc 0-10
Alkanlinity 50-700
Hardness 50-500
Silica (Si02) 25-80
D.Contaminated water (Gypsum Pond Water)
Contaminated water is used to supply essentially all the water
needs of a phosphate fertilizer complex. The majority of U.S.
phosphate fertilizer installations impound and recirculate all
water which has direct contact with any of the process gas or
liquid streams. This impounded and reused water accumulates
sizeable concentrations of many cations and anions, but
particularly F and P. Concentrations of 8500 mg/1 F and in
72
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excess of 5000 mg/1 P are not unusual. Concentration of radium
226 in recycled gypsum pond water is 60-100 picocuries per liter.
Acidity of the water also reaches extremely high levels (pH 1-2).
Use of such poor quality water necessitates that the process
equipment materials of construction be compatible with the
corrosive nature of the water.
Contaminated water is used in practically all process equipment
in the phosphate subcategory except sulfuric acid manufacturing
and rock grinding. The water requirements of such major water
using equipment as barometric condensers, gypsum sluicing, gas
scrubbing equipment, and heat exchangers are all supplied by
contaminated water. Each time the water is reused, the
contaminate level is increased. While this contaminated water is
a major process effluent, it is not discharged from the complex.
The following table lists ranges of contaminated water usage for
each process.
Process
Sulfuric Acid
Rock Grinding
Wet Process Phosphoric Acid
NPK Process-Nitric Acid
Acidulation
Phosphoric Acid Concentra-
tion
Phosphoric Acid Clarifica-
tion
Normal Superphosphate
Triple Superphosphate
Ammonium Phosphate
E.Make-up water
1/kkq
None
None
16400-20800
1000-2300
2500-2600
690-1040
940-1040
660-1040
5000-6500
Usage
gal/ton
None
None
3800-5000
240-540
550-57C
225-250
225-250
158-250
1200-1500
Make-up water in a phosphate complex is defined as fresh water
untreated except for suspended solids removal. Normally fresh
water use to all process units is held to an absolute minimum.
Such restraint is necessary because all make-up water used finds
its way into the contaminated water system. Excessive fresh
water use will therefore needlessly increase the contaminated
water inventory beyond the containment capacity. This in turn
means contaminated water must undergo costly treatment before
discharge to natural drainage whenever such discharge is
permitted.
Normal ranges of make-up water use are listed below for each of
the process units. There is no discharge except into a process
stream or to the contaminated water system.
73
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Process Make-up Water Usage
1/kkq gal/ton
Sulfuric Acid 63*83 15-20
Rock Grinding None None
Wet Process Phosphoric Acid None None
Phosphoric Acid Concentration 0.8-1.6 0.2-0.4
Phos Acid Clarification None None
Normal Superphosphate None None
Triple Superphosphate NNone None
Ammonium Phosphates None None
F.Spills and Leaks
Spills and leaks in most phosphate fertilizer process units are
collected as part of the housekeeping procedure. The collected
material is, where possible, re-introduced directly to the
process or into the contaminated water system. Spillage and
leaks therefore do not normally represent a direct contamination
of plant effluent streams that flow directly to natural drainage.
G.Non-Point Source Discharge
The primary origin of such discharges is dry fertilizer material
which dusts over the general plant area and then dissolves in
rain or melting snow. The magnitude of this contaminant source
is a function of dust containment, housekeeping, snow/rainfall
quantities, and the design of the general plant drainage
facilities. No meaningful data was obtained on this intermittant
discharge stream.
H.Contaminated Water ^Gypsum Pond^Water} Treatment System
The contaminated water treatment system discharge effluent is the
only major discharge stream from a phosphoric acid complex other
than the water treatment and blowdown streams associated with the
sulfuric acid process. Discharge from this system is kept to an
absolute minimum due to the treatment cost involved. In fact,
several complexes report that they have not treated and
discharged water for several years. The need to treat and
discharge water has been previously mentioned to be dependent
upon the contaminated water inventory. As a result, water
discharged from the treatment system is not done continuously
throughout the year. Once the necessity for treatment occurs,
however, the flow is continuous for that period of time required
to adjust the contaminated water inventory. Normally, this
period is 2-4 months per year, but is primarily dependent upon
the rainfall/evaporation ratio and occurence of concentrated
rainfall such as an abnormal rainy season or a hurricane. Some
phosphate fertilizer installations in the Western U.S.
perennially have favorable rainfall/evaporation ratios and never
have need to treat or discharge water. The quantity of water
discharged from the contaminated water treatment system is
74
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strictly dependent upon the design of the treatment system and
has no direct connection to production tonnage. Contaminated
water treatment systems generally have capacities of 2085-4170
1/min (500-1000 gpm).
The common treatment system is a two-stage liming process. Three
main contaminated water parameters, namely pH, Ff and P are
addressed.
Cadmium, Arsenicj Vanadium, Uranium and Radium 226
The amounts of cadmium, arsenic, vanadium and uranium present in
Florida and Western phosphate rocks were reviewed. These
elements are present in small concentrations in the rocks as
shown by the following table. In general, these elements are
solubilized by the phosphate rock acidulation process and tend to
be retained in the acid rather than discarded with the gypsum
waste. Only cadmium will be found in measureable quantities in
the gypsum pond, although small. A toxic limitation for this
pollutant will be established which will cover any discharge of
cadmium from the fertilizer categories. Radium 226 is a decay
product of uranium that occurs in the recycled gypsum pond water
in the 60-100 picpcuries/ liter range. However, its presence in
the effluent is controlled with control of phosphorus and
fluoride.
Phosphate^ Rock
(ppm)
Element Florida Western
Arsenic as As03 5-30 6-140
Cadmium as CdO~ 10 150
Uranium as U30J3 100^200 50-100
Vanadium as V203 10-200 400-4000
75
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Nitrogen Fertilizer Industry
The four process operations - ammonia, urea, ammonium nitrate,
nitric acid - in the nitrogen fertilizer category, discharge the
following types of waste water.
A.Water treatment plant effluent (includes raw water filtration
and clarification, water softening, and water deionization)
B.Closed loop cooling tower blowdown
C.Boiler blowdown
D.Compressor blowdown
E.Process condensate
F.Spills and leaks that are collected in pits or trenches
G.Non-point source discharges that are "collected" due to rain or
snow.
Detailed process flow diagrams have previously been presented in
Figures 15 through 18.
A•Water Treatment Plant Effluent
The total effluent stream from a combined water treatment system
will range from 8 to 20 1/kkg (2 to 5 gal/ton) of product with
an ammonia plant having the larger amount due to the large
amounts of raw water used. The contaminants in this effluent are
mainly due to the initial contaminants in the raw water and
therefore would be specific to the area and geographic conditions
rather than the process plants involved. If the water treatment
plant effluent contains ammonia due to the use of stripped,
process condensate as process or boiler water makeup (replacing
raw water makeup), then the ammonia - N discharge allowance is
applicable. Effluent limitations for specific components (other
than ammonia - N) for treatment, plant effluent are not covered in
this report. They will be studied at a later time.
B•Cooling Tower Blowdown
The cooling water requirements and expected blowdown requirements
for the four process plants in the nitrogen fertilizer industry
are listed in the table below.
76
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Cooling Water
Circulation Circulation Slowdown Slowdown
Requirement Requirement Requirement Requiremen
1/kkg gal/ton 1/kkg gal/ton
Ammonia 104,000 to 25,000 to 1,670 to 400 to 700
417,000 100,000 2,920
Urea 41,700 to 10,000 to 375 to 90 to 350
167,000 40,000 1,470
Ammonia Nitrate 8,350 to 2,000 to 84 to 20 to 60
29,200 7,000 250
Nitric Acid 104,000 to 25,000 to 1,250 to 300 to 600
146,000 35,000 2,500
In this closed loop cooling tower system, chemicals are added to
inhibit scale formation, corrosion and the growth of bacteria.
Due to the nature of the make-up water, the inhibitor chemicals
and the evaporation water loss from the tower, a quantity of
blowdown is required to prevent excessive build up of chemicals
and solids in the circualtion system. This quantity will vary,
as shown in the above table, from plant to plant depending on the
total circulation system.
The quality of this cooling system blowdown will vary mostly with
make-up water condition and inhibitor chemicals and will not be
greatly affected by the process plant associated with it. Any
leaks that might develop in process or machinery exchangers
should not significantly affect the contaminant concentration of
the cooling water. The largest contaminant in the cooling water,
that is neither intentionally added as an inhibitor nor comes in
with make-up, is ammonia. Due to the proximity of the cooling
tower in relation to any of the four nitrogen fertilizer
operations, some atmospheric ammonia is absorbed in the cooling
water.
The table below represents some possible range of concentration
for some of the contaminants that might be contained in the
cooling water blowdown.
mg/1 mg/1
Chromate 0-250 Zinc 0-30
Ammonia 5-100 Oil 10-1,000
Sulfate 500-3,000 TDS 500-10,000
Chloride 0-40 MEA 0-10
Phosphate 10-50
This blowdown can be either treated by itself if necessary or
combined with other effluents for total treatment. However, it
is recommended that this stream be treated separately for
chromate-zinc reduction since this is main source of these
contaminants (Cr and Zn) to the total plant effluent. Effluent
77
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limitations for noncontact cooling water are not covered in this
report. They will be established at a later date.
C.Boiler Slowdown
The four nitrogen fertilizer processes will generate up to 6,000
kg of steam/kkg (12,000 Ib of steam/ton) of product depending on
what processes are at the plant site. Ammonia will have the
highest steam load followed by nitric acid, urea and ammonium
nitrate. The pressure of the steam generated by and/or used in
these plants will range from atmospheric up to 103 atm (1,5CO
psig).
Depending on the operating pressure of the steam system, the
treatment of the boiler feed water will vary from extensive,
including deionization, at 103 atm (1,500 psig) down to not much
more than filtration at atmospheric pressure. Inhibitor
chemicals are also added to boilers to prevent corrosion and
scale formation throughout the system.
The combination of make-up water quality and the addition of
inhibitor chemicals necessitates blowdown periodically to remove
contaminants from the boiler. Based on the actual steam
generated in a nitrogen fertilizer complex, this blowdown
quantity will range from 42 to 145 1/kkg (10 to 35 gal/ton) of
product.
Typical compositions of contaminants in boiler blowdown from
nitrogen complex boilers are as follows:
mg/1 mg/1
Phosphate 5-50 Suspended Solids 50-300
Sulfite 0-100 Alkalinity 50-700
TDS 500-3500 Hardness 50-500
Zinc 0-10 Si02 10-5C
This effluent stream may be treated separately if necessary or
combined with the total effluent for treatment. Effluent
limitations for boiler blowdown will be established at a later
date.
D.Compressor Blowdown
This waste water effluent stream has been separated out because
it should contain the largest proportional amount of oil and
grease. Primarily, the blowdown containing oil will come from
interstage cooling-separation in the reciprocating compressors
operating on ammonia synthesis gas, on ammonia process air and on
urea carbon dioxide. If these streams can be contained then oil
separation equipment can be kept to a minimum.
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Due to the nature and expense of reciprocating compressors they
are usually replaced by centrifugal compressors, when the ammonia
plant capacity reaches 550 kkg/day (600 ton/day). The use of
centrifugal compressors results in much less oil and grease in
the blowdown effluent. The quantity of this blowdown will vary
and can run up to 208 1/kkg (50 gal/ton) of product.
E•Process^Condensate
Process condensate, although it may have many of the similar
contaminants, will be handled separately for each of the four
process plants.
Ammonia Process Condensate
Process steam supplied to the primary reformer is in excess of
the stoichiometric amount required for the process reactions and,
therefore, when the synthesis gas is cooled either by heat
recovery or cooling water, a considerable amount of process
condensate is generated. The quantity of this condensate will
range from 1,500 to 2,500 kg/kkg (3,000 to 5,000 Ib/ton) of
product. The contaminants in this condensate may be ammonia,
methanol, some organics from the CO2 recovery system and possibly
some trace metals. The ammonia discharged in this waste stream
can range from 1,200 - 1750 kg/1000 kkg (2400 - 3500 lb/1000
ton) .
Urea Process Condensate
Following the urea forming reactions the pressure is reduced to
allow ammonia, carbon dioxide and ammonium carbamate to escape
from urea product. Partial condensation of these flashed gases
along with the condensation of water vapor from the urea
concentration step results in a condensate containing urea, am-
monium carbamate, ammonia and carbon dioxide. The quantity of
this stream will range from 417 to 935 1/kkg (100 to 225 gal/ton)
of product. Ammonia discharge in this stream has been observed
at the level of 9,000 kg/1000 kkg (18,000 lb/1000 ton) of urea
product. Urea discharge at the rate of 33,500 kg/1000 kkg
(67,000 lb/1000 ton) of urea product has also been cited.
Ammonium Nitrate Process Condensate
The nitric acid-ammonia reaction being highly exothermic causes a
large amount of water to be flashed off taking with it ammonia,
nitric acid, nitrates and some nitrogen dioxide. If climatic
conditions or air pollution regulations require that this strearr
be condensed then this contaminated condensate will range between
208 and 458 1/kkg (50 and 110 gal/ton) of product. Ammonia
discharges in the stream could be at the levels of 150 kg/100C
kkg (300 lb/1000 ton) and ammonium nitrate at 7000 kg/1000 kkc
(14,000 lb/1000 ton) of ammonium nitrate product.
Nitric Acid Process Condensate
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Using the ammonia oxidation process for production of 55% to 65%
strength acid there are no process condensate effluent streams.
F.Collected Spills and Leaks
In all process plants there will be a small quantity of material
either spilled, during loading or transferring, or leaking from
some pump seal or bad valve. When this material, whether it be
cooling water, process condensate, carbon dioxide scrubbing
solution, boiler feed water or anything else, gets on a hard
surface where it can be collected in a trench, then it will
probably have to be treated before being discharged. The
quantity of this material is not dependent on plant size, but
more on the operating philosophy and housekeeping procedures.
G.Non-Point Discharges
Rain or snow can be a collection medium for a sizable quantity of
contaminants. These contaminants may be air borne ammonia that
is absorbed as the precipitation falls, or it may be urea or
ammonium nitrate prill dust that is lying on the ground around
prill towers. Dry fertilizer shipping areas may also have urea
and/or ammonium nitrate that can be washed down by rain or snow.
Pipe sweat and drip pots are another potential source of
contaminants.
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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 includi
in process effluent streams
PHOSPHATE FERTILIZER INDUSTRY
Effluent waste water from the phosphate fertilizer processes must
be treated to reduce the following primary factors and con-
taminants to achievable levels: pH, phosphorus, fluorides, and
suspended solids.
Secondary parameters which should be monitored but do not warrant
establishment of guidelines are: ammonia, total dissolved
solids, temperature, cadmium, total chromium, zinc, vanadium,
arsenic, uranium and radium 226. The chief reason for not
establishing standards for the secondary parameters is that
treatment of the primary parameters will effect removal of these
secondary parameters. Another reason is that insufficient data
exists to establish effluent limitations.
NITROGEN FERTILIZER INDUSTRY
Effluent waste waters from a nitrogen fertilizer complex must be
treated to maintain the following primary parameters within the
recommended guidelines: ammonia nitrogen, organic nitrogen,
nitrate nitrogen, and pH.
Secondary parameters which should be monitored but do not warrant
the setting of guidelines at this time are: chemical oxygen
demand (COD), total dissolved solids (TDS), suspended solids, oil
and grease, total chromium, zinc, iron, and nickel. The chief
reason for . not establishing standards for the secondary
parameters is that treatment of the primary parameters will
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effect removal of these secondary parameters. Another reason is
that insufficient data exists to establish effluent limitations.
These selections are supported by the knowledge that best
practicable control technology currently available does exist to
control the chosen parameters and that improved technology is
being developed and refined to meet best available technology
economically achievable and best demonstrated technology.
Rationale for Selecting Identified Parameters
Phosphorus
During the past 30 years, a formidable case has developed for the
belief that increasing standing crops of aquatic plant growths,
which often interfere with water uses and are nuisances to man,
frequently are caused by increasing supplies of phosphorus. Such
phenomena are associated with a condition of accelerated
eutrophication or aging of waters. It is generally recognized
that phosphorus is not the sole cause of eutrophication, but
there is evidence to substantiate that it is frequently the key
element in all of the elements required by fresh water plants and
is generally present in the least amount relative to need.
Therefore, an increase in phosphorus allows use of other, already
present, nutrients for plant growths. Phosphorus is usually
described, for this reasons, as a "limiting factor."
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 a 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.
Fluorides
As the most reactive non-metal, fluorine is never found free in
nature but as a constituent of fluorite or fluorspar, calcium
fluoride, in sedimentary rocks and also of cryolite, sodium
aluminum fluoride, in igneous rocks. Owing to their origin only
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in certain types of rocks and only in a few regions, fluorides in
high concentrations are not a common constituent of natural
surface waters, but they may occur in detrimental concentrations
in ground waters.
Fluorides are used as insecticides, for disinfecting brewery
apparatus, as a flux in the manufacture of steel, for preserving
wood and mucilages, for the manufacture of glass and enamels, in
chemical industries, for water treatment, and for other uses.
Fluorides in sufficient quantity are toxic to humans, with doses
of 250 to 450 mg giving severe symptoms or causing death.
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.
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.
EH» Acidity and Alkalinity
Acidity and alkalinity are reciprocal terms. Acidity is produced
by substances that yield hydrogen ions upon hydrolysis and
alkalinity is produced by substances that yield hydroxyl ions.
The terms "total acidity" and "total alkalinity" are often used
to express the buffering capacity of a solution. Acidity in
natural waters is caused by carbon dioxide, mineral acids, weakly
dissociated acids, and the salts of strong acids and weak bases.
Alkalinity is caused by strong bases and the salts of strong
alkalies and weak acids.
The term pH is a logarithmic expression of the concentration of
hydrogen ions. At a pH of 7, the hydrogen and hydroxyl ion
concentrations are essentially equal and the water is neutral.
Lower pH values indicate acidity while higher values indicate
alkalinity. The relationship between pH and acidity or
alkalinity is not necessarily linear or direct.
Waters with a pH below 6.0 are corrosive to water works
structures, distribution lines, and household plumbing fixtures
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and can thus add such constituents to drinking water as iron,
copper, zinc, cadmium and lead. The hydrogen ion concentration
can affect the "taste" of the water. At a low pH water tastes
"sour". The bactericidal effect of chlorine is weakened as the
pH increases, and it is advantageous to keep the pH close to 7.
This is very significant for providing safe drinking water.
Extremes of pH or rapid pH changes can exert stress conditions or
kill aquatic life outright. Dead fish, associated algal blooms,
and foul stenches are aesthetic liabilities of any waterway.
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.
Metalocyanide complexes can increase a thousand-fold in toxicity
with a drop of 1.5 pH units. The availability of many nutrient
substances varies with the alkalinity and acidity. 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 components include sand, silt, and clay. The
organic fraction includes such materials as grease, oil, tar,
animal and vegetable fats, various fibers, sawdust, hair, and
various materials from sewers. These solids may settle out
rapidly and bottom deposits are often a mixture of both organic
and inorganic solids. They adversely affect fisheries by
covering the bottom of the stream or lake with a blanket of
material that destroys the fish-food bottom fauna or the spawning
ground of fish. Deposits containing organic materials may
deplete bottom oxygen supplies and produce hydrogen sulfide,
carbon dioxide, methane, and other noxious gases.
In raw water sources for domestic use, state and regional
agencies generally specify that suspended solids in streams shall
not be present in sufficient concentration to be objectionable or
to interfere with normal treatment processes. Suspended solids
in water may interfere with many industrial processes, and cause
foaming in boilers, or encrustations on equipment exposed to
water, especially as the temperature rises. Suspended solids are
undesirable in water for textile industries; paper and pulp;
beverages; dairy products; laundries; dyeing; photography;
cooling systems, and power plants. Suspended particles also
serve as a transport mechanism for pesticides and other
substances which are readily sorbed into or onto clay particles.
Solids may be suspended in water for a time, and then settle to
the bed of the stream or lake. These settleable solids
discharged with man's wastes may be inert, slowly biodegradable
materials, or rapidly decomposable substances. While in
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suspension, they increase the turbidity of the water, reduce
light penetration and impair the photosynthetic activity of
aquatic plants.
Solids in suspension are aesthetically displeasing. When they
settle to form sludge deposits on the stream or lake bed, they
are often much more damaging to the life in water, and they
retain the capacity to displease the senses. 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 and
therefore decomposable nature, solids use a portion or all of the
dissolved oxygen available in the area. Organic materials also
serve as a seemingly inexhaustible food source for sludgeworms
and associated organisms.
Turbidity is principally a measure of the light absorbing
properties of suspended solids. It is frequently used as a
substitute method of quickly estimating the total suspended
solids when the concentration is relatively low.
Ammonia and Nitrate Nitrogen
Ammonia is a common product of the decomposition of organic
matter. Dead and decaying animals and plants along with human
and animal body wastes account for much of the ammonia entering
the aquatic ecosystem. Ammonia exists in its non-ionized form
only at higher pH levels and is the most toxic in this state.
The lower the pH, the more ionized ammonia is formed and its
toxicity decreases. Ammonia, in the presence of dissolved
oxygen, is converted to nitrate (NO.3) by nitrifying bacteria.
Nitrite (NO2) , which is an intermediate product between ammonia
and nitrate, sometimes occurs in quantity when depressed oxygen
conditions permit. Ammonia can exist in several other chemical
combinations including ammonium chloride and other salts.
Nitrates are considered to be among the poisonous ingredients of
mineralized waters, with potassium nitrate being more poisonous
than sodium nitrate. Excess nitrates cause irritation of the
mucous linings of the gastrointestinal tract and the bladder; the
symptoms are diarrhea and diuresis, and drinking one liter of
water containing 500 mg/1 of nitrate can cause such symptoms.
Infant methemoglobinemia, a disease characterized by certain
specific blood changes and cyanosis, may be caused by high
nitrate concentrations in the water used for preparing feeding
formulae. While it is still impossible to state precise
concentration limits, it has been widely recommended that water
containing more than 10 mg/1 of nitrate nitrogen (NO3.-N) should
not be used for infants. Nitrates are also harmful in
fermentation processes and can cause disagreeable tastes in beer.
In most natural water the pH range is such that ammonium ions
(NH^*+) predominate. In alkaline waters, however, high
concentrations of un-ionized ammonia in undissociated ammonium
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hydroxide increase the toxicity of ammonia solutions. In streams
polluted with sewage, up to one half of the nitrogen in the
sewage may be in the form of free ammonia, and sewage may carry
up to 35 mg/1 of total nitrogen. It has been shown that at a
level of 1.0 mg/1 un-ionized ammonia, the ability of hemoglobin
to combine with oxygen is impaired and fish may suffocate.
Evidence indicates that ammonia exerts a considerable toxic
effect on all aquatic life within a range of less than 1.0 mg/1
to 25 mg/1, depending on the pH and dissolved oxygen level
present.
Ammonia can add to the problem of eutrophication by supplying
nitrogen through its breakdown products. Some lakes in warmer
climates, and others that are aging quickly are sometimes limited
by the nitrogen available. Any increase will speed up the plant
growth and decay process.
Organic Nitrogen
Organic nitrogen contaminants in the waste waters consist mainly
of urea and lesser amounts of organic CO2. scrubbing solutions.
Such compounds can supply nutrient nitrogen for increased plant
and algae growth in receiving waters.
The organic scrubbing solution - monethanolamine (MEA) - can add
a slight BOD load to the effluent waste stream.
Dissolved Solids
In natural waters the dissolved solids consist mainly of
carbonates, chlorides, sulfates, phosphates, and possibly
nitrates of calcium, magnesium, sodium, and potassium, with
traces of iron, manganese and other substances.
Many communities in the United States and in other countries use
water supplies containing 2000 to 4000 mg/1 of dissolved salts,
when no better water is available. Such waters are not
palatable, may not quench thirst, and may have a laxative action
on new users. Waters containing more than UOOO mg/1 of total
salts are generally considered unfit for human use, although in
hot climates such higher salt concentrations can be tolerated
whereas they could not be in temperate climates. Waters
containing 5000 mg/1 or more are reported to be bitter and act as
bladder and intestinal irritants. It is generally agreed that
the salt concentration of good, palatable water should not exceed
500 mg/1.
Limiting concentrations of dissolved solids for fresh-water fish
may range from 5,000 to 10,000 mg/1, according to species and
prior acclimatization. Some fish are adapted to living in more
saline waters, and a few species of fresh-water forms have been
found in natural waters with a salt concentration of 15,000 to
20,000 mg/1. Fish can slowly become acclimatized to higher
salinities, but fish in waters of low salinity cannot survive
sudden exposure to high salinities, such as those resulting from
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discharges of oil-well brines. Dissolved solids may influence
the toxicity of heavy metals and organic compounds to fish and
other aquatic life, primarily because of the antagonistic effect
of hardness on metals.
Waters with total dissolved solids over 500 mg/1 have decreasing
utility as irrigation water. At 5,000 mg/1 water has little or
no value for irrigation.
Dissolved solids in industrial waters can cause foaming in
boilers and cause interference with cleaness, color, or taste of
many finished products. High contents of dissolved solids also
tend to accelerate corrosion.
Specific conductance is a measure of the capacity of water to
convey an electric current. This property is related to the
total concentration of ionized substances in water and water
temperature. This property is frequently used as a substitute
method of quickly estimating the dissolved solids concentration.
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 activity 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.
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
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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 benthinc 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 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.
Cadmium
Cadmium in drinking water supplies is extremely hazardous to
humans, and conventional treatment, as practiced in the United
States, does not remove it. Cadmium is cumulative in the liver,
kidney, pancreas, and thyroid of humans and other animals. A
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severe bone and kidney syndrome in Japan has been associated with
the ingestion of as little as 600 ug/day of cadmium.
Cadmium is an extremely dangerous cumulative toxicant, causing
insidious progressive chronic poisoning in mammals, fish, and
probably other animals because the metal is not excreted.
Cadmium could form organic compounds which might lead to
mutagenic or teratogenic effects. Cadmium is known to have
marked acute and chronic effects on aquatic organisms also.
Cadmium acts synergistically with other metals, copper and zinc
substantially increase its toxicity. Cadmium is concentrated by
marine organisms, particularly molluscs, which accumulate cadmium
in calcareous tissues and in the viscera. A concentration factor
of 1000 for cadmium in fish muscle has been reported, as have
concentration factors of 3000 in marine plants, and up to 29,600
in certain marine animals. The eggs and larvae of fish are
apparently more sensitive than adult fish to poisoning by
cadmium, and crustaceans appear to be more sensitive than fish
eggs and larvae.
Chromium
Chromium, in its various valence states, is hazardous to man. It
can produce lung tumors when inhaled and induces skin
sensitizations. Large doses of chromates have corrosive effects
on the intestinal tract and can cause inflammation of the
kidneys. Levels of chr ornate ions that have no effect on man
appear to be so low as to prohibit determination to date.
The toxicity of chromium salts toward aquatic life varies widely
with the species, temperature, pH, valence of the chromium, and
synergistic or antagonistic effects, especially that of hardness.
Fish are relatively tolerant of chromium salts, but fish food
organisms and other lower forms of aquatic life are extremely
sensitive. Chromium also inhibits the growth of algae.
In some agricultural crops, chromium can cause reduced growth or
death of the crop. Adverse effects of low concentrations of
chromium on corn, tobacco and sugar beets have been documented.
Occurring abundantly in rocks and ores, zinc is readily refined
into a stable pure metal and is used extensively for galvanizing,
in alloys, for electrical purposes, in printing plates, for dye-
manufacture and for dyeing processes, and for many other
industrial purposes. Zinc salts are used in paint pigments,
cosmetics, Pharmaceuticals, dyes, insecticides, and other
products too numerous to list herein. Many of these salts (e.g.,
zinc chloride and zinc sulfate) are highly soluble in water;
hence it is to be expected that zinc might occur in many
industrial wastes. On the other hand, some zinc salts (zinc
carbonate, zinc oxide, zinc sulfide) are insoluble in water and
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consequently it is to be expected that some zinc will precipitate
and be removed readily in most natural waters.
In zinc-mining areas, zinc has been found in waters in
concentrations as high as 50 mg/1 and in effluents from metal-
plating works and small-arms ammunition plants it may occur in
significant concentrations. In most surface and ground waters,
it is present only in trace amounts. There is some evidence that
zinc ions are adsorbed strongly and permanently on silt,
resulting in inactivation of the zinc.
Concentrations of zinc in excess of 5 mg/1 in raw water used for
drinking water supplies cause an undesirable taste which persists
through conventional treatment. Zinc can have an adverse effect
on man and animals at high concentrations.
In soft water, concentrations of zinc ranging from 0.1 to 1.0
mg/1 have been reported to be lethal to fish. Zinc is thought to
exert its toxic action by forming insoluble compounds with the
mucous that covers the gills, by damage to the gill epithelium,
or possibly by acting as an internal poison. The sensitivity of
fish to zinc varies with species, age and condition, as well as
with the physical and chemical characteristics of the water.
Some acclimatization to the presence of zinc is possible. It has
also been observed that the effects of zinc poisoning may not
become apparent immediately, so that fish removed from zinc-
contaminated to zinc-free water (after 4-6 hours of exposure to
zinc) may die U8 hours later. The presence of copper in water
may increase the toxicity of zinc to aquatic organisms, but the
presence of calcium or hardness may decrease the relative
toxicity.
Observed values for the distribution of zinc in ocean waters vary
widely. The major concern with zinc compounds in marine waters
is not one of acute toxicity, but rather of the long-term sub-
lethal effects of the metallic compounds and complexes. From an
acute toxicity point of view, invertebrate marine animals seem to
be the most sensitive organisms tested. The growth of the sea
urchin, for example, has been retarded by as little as 30 ug/1 of
zinc.
Zinc sulfate has also been found to be lethal to many plants, and
it could impair agricultural uses.
Vanadium
Metallic vanadium does not occur free in nature, but minerals
containing vanadium are widespread. Vanadium is found in many
soils and occurs in vegetation grown in such soils. Vanadium
adversely effects some plants in concentrations as low as 10
mg/1.
Vanadium as calcium vanadate can inhibit the growth of chicks and
in combination with selenium, increases mortality in rats.
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Vanadium appears to inhibit the synthesis of cholesterol and
accelerate its catabolism in rabbits.
Vanadium causes death to occur in fish at low concentrations.
The amount needed for lethality depends on the alkalinity of the
water and the specific vanadium compound present. The common
bluegill can be killed by about 6 ppm in soft water and 55 ppm in
hard water when the vanadium is expressed as vanadryl sulfate.
Other fish are similarly affected.
Specific conductance is a measure of the capacity of water to
convey an electric current. This property is related to the
total concentration of ionized substances in water and water
temperature. This property is frequently used as a substitute
method of quickly estimating the dissolved solids concentration.
Arsenic
Arsenic is found to a small extent in nature in the elemental
form. It occurs mostly in the form of arsenites of metals or as
pyrites.
Arsenic is normally present in sea water at concentrations of 2
to 3 ug/1 and tends to be accumulated by oysters and other
shellfish. Concentrations of 100 mg/kg have been reported in
certain shellfish. Arsenic is a cumulative poison with long-term
chronic effects on both aquatic organisms and on mammalian
species and a succession of small doses may add up to a final
lethal dose. It is moderately toxic to plants and highly toxic
to animals especially as AsH3.
Arsenic trioxide, which also is exceedingly toxic, was studied in
concentrations of 1.96 to 40 mg/1 and found to be harmful in that
range to fish and other aquatic life. Work by the Washington
Department of Fisheries on pink salmon has shown that at a level
of 5.3 mg/1 of As2CX3 for 8 days was extremely harmful to this
species; on mussels, a level of 16 mg/1 was lethal in 3 to 16
days.
Severe human poisoning can result from 100 mg concentrations, and
130 mg has proved fatal. Arsenic can accumulate in the body
faster than it is excreted and can build to toxic levels, from
small amounts taken periodically through lung and intestinal
walls from the air, water and food.
Arsenic is a normal constituent of most soils, with
concentrations ranging up to 500 mg/kg. Although very low
concentrations of arsenates may actually stimulate plant growth,
the presence of excessive soluble arsenic in irrigation waters
will reduce the yield of crops, the main effect appearing to be
the destruction of chlorophyll in the foliage. Plants grown in
water containing one mg/1 of arsenic trioxides showed a
blackening of the vascular bundles in the leaves. Beans and
cucumbers are very sensitive, while turnips, cereals, and grasses
are relatively resistant, old orchard soils in Washington that
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contained 4 to 12 mg/kg of arsenic trioxide in the top soil were
found to have become unproductive.
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 similar
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. 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 radio-
nuclides 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 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 radioactive
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
92
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or grinding of phsophate rock would liberate radon and its decay
products to the surrounding atmosphere.
It is generally agreed that unlilke 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 radiaiton, 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,
1960)."
Oil and Grease
Oil and grease exhibit an oxygen demand. Oil emulsions may
adhere to the gills of fish or coat and destroy algae or other
plankton. Deposition of oil in the bottom sediments can serve to
exhibit normal benthic growths, thus interrupting the aquatic
food chain. Soluble and emulsified material ingested by fish may
taint the flavor of the fish flesh. Water soluble components may
exert toxic action on fish. Floating oil may reduce the re-
aeration of the water surface and in conjunction with emulsified
oil may interfere with photosynthesis. Water insoluble
components damage the plumage and costs of water animals and
fowls. Oil and grease in a water can result in the formation of
objectionable surface slicks preventing the full aesthetic
enjoyment of the water.
Oil spills can damage the surface of boats and can destroy the
aesthetic characteristics of beaches and shorelines.
Nickel
Elemental nickel seldom occurs in nature, but nickel compounds
are found in many ores and minerals. As a pure metal it is not a
problem in water pollution because it is not affected by, or
soluble in, water. Many nickel salts, however, are highly
soluble in water.
Nickel is extremely toxic to citrus plants. It is found in many
soils in California, generally in insoluble form, but excessive
acidification of such soil may render it soluble, causing severe
injury to or the death of plants. Many experiments with plants
in solution cultures have shown that nickel at 0.5 to 1.0 mg/1 is
inhibitory to growth.
Nickel salts can kill fish at very low concentrations. Data for
the fathead minnow show death occurring in the range of 5-43 mg,
depending on the alkalinity of the water.
Nickel is present in coastal and open ocean concentrations in the
range of 0.1 - 6.0 ug/1, although the most common values are 2 -
3 ug/1. Marine animals contain up to 400 ug/1, and marine plants
93
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contain up to 3,000 ug/1. The lethal limit of nickel to some
marine fish has been reported as low as 0.8 ppm. Concentrations
of 13.1 mg/1 have been reported to cause a 50 percent reduction
of the photosynthetic activity in the giant kelp (Macrpcystis
pyrif era) in 96 hours, and a low concentration was found to kill
oyster eggs.
METHODS OF ANALYSIS
The methods of analysis to be used for quantitative determination
are given in the Federal Register 40 CFR 130 for the following
parameters pertinent to this study:
alkalinity (and acidity)
ammonia nitrogen
arsenic
cadmium
chromium
fluoride
hardness
nitrate nitrogen
nitrogen, total kjeldahl
oxygen demand, chemical
phosphorus
solids, total
suspended nonfilterable solids, total
temperature
zinc
Organic nitrogen should be analyzed according to Standard Methods
for the Examination of Water and Waste Water (SMWW) (ref W)
method 215. ~
Oil and grease should be determined by Methods for Chemical
Analysis of Water and Wastes (ref.X), page 217.
Vanadium should be determined by SMWW method 164.
94
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SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
The factors and contaminants in fertilizer process effluent
streams have for the most part been quite well identified and
fairly 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-of-pipe 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 it. Additional or future
corrective measures are for the most part going to require
capital expenditures which will do nothing towards improving
operational economics and will, in fact, increase operational
costs.
With an appreciation of the above mentioned facts, it must be
considered that future expenditures for waste water treatment
should be well documented as to the need, the degree of water
quality required, and assurance that the specified treatment is a
workable and viable technology before the associated effluent
limitation it is stipulated as an absolute requirement. It was
with these conditions in mind that the following criteria were
established as a basis for investigating treatment technology.
- to determine the extent of existing waste water control
and treatment technology
to determine the availability of applicable waste water
control and treatment technology including that available by
transfer from other industries
- to determine the degree of treatment cost reasonability
Based upon these stated criterion the effort was made to
factually investigate overall treatment technologies dealing with
each of the primary factors and contaminants listed in Section
VI. The results of that investigation are covered separately for
phosphate and nitrogen fertilizers.
CONTROL AND TREATMENT TECHNOLOGY
PHOSPHATE FERTILIZER INDUSTRY"
Process technology does exist for treatment and reduction of the
primary factors and contaminants present in phosphate fertilizer
process effluent streams to the levels proposed. These treatment
technologies are reviewed in the following paragraphs.
95
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Sulfuric Acid Plant Effluent Control
A sulfuric acid plant has no inherent water pollutants associated
with the actual production of acid. An indispensible part of the
process, however, is heat removal. This heat removal is
accomplished with steam generating equipment and cooling towers.
Both of these cooling methods require blowdown and subsequent
disposal to natural drainage. The amount and degree of impuri-
ties discharged vary widely with the raw water quality.
An inherent hazard of any liquid handling process is the occur-
rence of an occasional accidental break and operator error. In a
sulfuric acid plant the sulfuric acid cooling coils are most
prone to an accidental break. On these occasions the cooling
tower water quickly becomes contaminated. In turn, the normally
acceptable practice is to take care of that break as soon as it
is discovered and protect the natural drainage waters.
Process Description
The facilities are relatively simple. It involves the instal-
lation of a reliable pH or conductivity continuous monitoring
unit on the plant effluent stream (preferably the combined plant
effluent stream but at least on the cooling tower blowdown). A
second part of the system is a retaining area through which non-
contaminated effluent normally flows. This retaining area can be
any reasonable size but should be capable of retaining a minimum
of 21 hours of the normal plant effluent stream. The discharge
point from the retaining area requires a means of positive cut-
off, preferably a concrete abutment fitted with a valve. A final
part of the system is somewhat optional. For example, the
retaining area could be provided with lime treatment facilities
for neutralization. In addition equipment for transfering this
acid water from the retaining area to a contaminated water
holding or recirculating system could also be provided. Plants
002 and 009 provide such systems to control process leaks.
The procedure is that an acid break is detected by the water
monitoring instrument, located at the inlet of the cooling tower,
and causes an audible alarm to be sounded. It is preferable to
also have the instrument automatically activate the positive cut-
off at the discharge of the retaining area although this can be
done manually. Activation of this system in turn necessitates a
plant shutdown to locate the failure and initiate repairs. The
now contaminated water in the retaining area must then be either
neutralized in the pond or moved to a contaminated water storage
area where it can be stored or neutralized through a central
treatment system.
Figure 19 depicts a sketch of the suggested treatment facilities.
Such a system provides continuous protection of natural drainage
waters as well as means to correct a process failure. The
primary factor to control is pH. Sufficient neutralization to
raise the contaminated water pK to 6 is required. Neutralization
is preferably by use of lime. Lime serves not only to neutralize
96
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SULFURIC ACID
PROCESS PLANT
TO EFFLUENT DISPOSAL
/ , TO GYPSUM POND
( _!._ (ALTERNATE)
— CONTROLLED DISCHARGE RETENTION
POND
SITE VARIES WITH AREA AVAILABLE AND PLANT SIZE
(SIZE MIGHT BE 300' x 30' x 6'
MAY BE BLOCKED/DAMMED
TO PERMIT POND WATER PH
CONTROL IF REQUIRED
I EXCHANGER
FROM 4th CONVERTER
TO ATMOSPHERE
FROM HT.
EXCHANGER
A
I
I
CLARIFIED WATER
CLARIFIED WATER
TO PUMP
TANK -4
COOLING
TOWER
COOLING
TONER
SLOWDOWN
TO PUMP
TANK
NOTE-
CIRCLED ITEMS ADDED
FOR EFFLUENT CONTROL
FIGURE 19
SULFURIC ACID EFFLUENT CONTROL
NOTE: THIS APPLIES TO BOTH
SINGLE AND DOUBLE
ABSORPTION PLANTS
-------
the hydrogen ion concentration (low pH) but also removes sulfate
(SO*t) as an insoluble calcium sulfate according to the following
reaction:
H2SO£ + CaO + H20 —> CaSO4 »2H20
Sulfuric Lime Water Calcium Sulfate
Acid
98
-------
Gypsum Pond (Contaminated) Water Treatment
As described in Section V, all phosphate complex process
effluents (contaminated water) are collected and impounded. The
impoundment area,ranging in size from 65 to 570 hectares (160 to
1400 acres) serves two functions. One function is as a storage
area for waste by-product gypsum from the phosphoric acid
process. The second is as an area for atmospheric evaporative
cooling of the contaminated water prior to its reuse back in the
various process units. This pond system functions in a closed
loop mode the majority of the time. The time interval that it
can function as a no discharge closed loop system is dependent on
the quantity of rainfall it can accept before the 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 bodies.
Process Description
Contaminated water can be treated effectively for control of the
pollution parameters identified in Section VI, namely pH,
phosphorus, and fluorides. Treatment is by means of a "double
liming" or two stage lime neutralization procedure.
At least 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 phosphoric acid with some minor amounts of
soluble calcium phosphates.
The first treatment stage provides sufficient neutralization to
raise the contaminated water containing up to 9000 mg/1 F and up
to 6500 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 lime addition and the
constancy of the pH control. At a pH level of 3.5 to 4.0, the
fluorides will precipitate principally as calcium fluoride (CaF2!)
as shown by the following chemical equation.
H2SiF6 + 3 CaO + E2Q —> 3 CaF2 + 2 H20 + Si02
Fluosilicic Lime Water Calcium Water Silica
Acid fluoride
This mixture is then held in a quiescent area to allow the
particulate CaF2 to settle.
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,
settling rate thickener or settler. The partially neutralized
99
-------
water following separation from the caF2, (pH 3.5-4.0) now
contains 30-60 mg/1 F and up to 5500 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 H3PO.4 + CaO
Phosphoric Lime
Acid
+ Ca (H2P04) 2 + CaO
Monocalcium Lime
Phosphate
H2O
Water
H2O
Water
Ca(H2P04) 2
Monocalcium
Phosphate
2CaHPO4
Dicalcium
Phosphate
2 H20
Water
Water
2 H20
Water
As before, this mixture is retained in a quiescent area to allow
the CaHPOf* and minor amounts of CaF.2 to settle.
The reduction of the P value is strongly dependent upon the final
pH level, holding time, and quality of the neutralization
facilities, particulary mixing efficiency. Figure 20 shows a
sketch of a well designed "double lime" treatment facility.
Plants 002, 007, 008, 009, 010, 014 and 019 all practice some
degree of liming.
Laboratory and plant data for phosphorus and fluoride removal
presented below:
is
PH
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
Phosphorus (mq/1)
laboratory plant
500
330
200
120
20
3
1.2
42
24
18
14
12
8
6
3
1.2
Fluoride jmg/l\
laboratory plant
17
14
12.5
12.5
12.5
12.5
12.5
12.5
12.5
13
8.5
6.8
5.8
5.2
4.8
4.6
12.5
Although the starting concentrations are either arbitrary or
specific to that plant only, the data does show significant
removal at high pH.
At plant 008 results from lime treatment show that phosphorus
concentrations decrease with time as well as increasing pH.
Phosphorus concentration vs pH with a 46 hour holding period
were:
100
-------
P. STEAM
TO GYPSUM POND
FIGURE 20
POND WATER TREATMENT
CALCIUM PHOSPHATE
POND
TO RIVER OR
PROCESS UNITS
-------
£H mq/1 P
5.8 20
6.5 9.1
8.3 3.6
The time effect on phosphorus concentration is:
Time-hours joH mg/1 P
0 7.85 60
5 7.6 29
22 6.7 19
H6 6.U 9
Data from three years of double lime treatment of gypsum pond
effluent from plant 008 at a pH of 5 to 7 shows a phosphorus
concentration (as P) of 10 to UO mg/1.
Radium 226 is also precipitated by lime treatment increasingly
with increasing pH as presented below:
pH Radium 226
picocuries/1
2.0 91
1.5 65
U.O 7.6
8.0-8.5 O.OU
Up to this point, nothing has been mentioned about the pollutant
ammonia N in contaminated water. Any phosphate complex
containing an ammonium phosphate unit will have NH3-N in the
contaminated water system. "Double lime" treatment will not
reduce the N quantity, although at high pH (greater than -9.0) r
significant ammonia loss to ambient air can occur. To date there
is no proven means of economically removing NH3-N from aqueous
solutions having such weak concentrations as 20-60 mg/1. The
best method to keep the NH3-N contaminant level low is to prevent
its entry into the main contaminated water system. More about
the manner that this can be done is discussed in the DAP self-
contained process discussion.
102
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Gypsum Pond Water Seepage Control
The contaminated (gypsum pond) water storage areas are surrounded
by dikes. The base of these dikes are normally natural soil from
the immediate surroundings. As the need develops to increase the
height of the retaining dikes, gypsum is dug from inside the
diked area and added to the top of the earthen base. Dikes in
Florida now extend to a 100-120 ft. vertical height. These
combined earth/gypsum dikes tend to have continual seepage of
contaminated water through them. In order to prevent this
seepage from reaching natural drainage streams, it is necessary
to collect and re-impound it.
Seepage collection and re-impoundment (Plant 002) is best
accomplished by construction of a seepage collection ditch all
around the perimeter of the diked area. The seepage collection
ditch needs to be of sufficient depth and size to not only
collect contaminated water seepage but to permit collection of
seepage surface water from the immediate outer perimeter of the
seepage ditch. This is best accomplished by erection of a small
secondary dike as depicted on Figure 21. The secondary dike also
serves as a back-up or reserve dike in the event of a failure of
a major dike.
The design of the seepage ditch in respect to distance from the
main impounding dike and depth is a function of the geology of
the area and the type material used for the dike. In Florida,
where the largest number of phosphate complexes are located, the
soil condition is such that little, if any, vertical water
percolation occurs. The soil at 4.5 - 7.5 meter (15-25 ft)
depths is unconsolidated ancient beach sands which lay on top of
the underlying Hawthorne matrix deposit. This Hawthorne matrix
deposit is basicly a nonporous material made up of impervious
clay-sand-phosphate pellet mixture. Surface drainage or
impounded waters percolate down to this Hawthorne layer. Then,
due to the nonporous nature of Hawthorne layer, are forced to
migrate horizontally following the interface between the
unconsolidated surface soil and the Hawthorne layer. Some data
suggests that the gypsum pond bottoms tend to be self-sealing.
That is, compacted gypsum plus clay fines and aluminum and iron
silicates forced into the interstices may form an artificial
"cement" like layer on the bottom of old gypsum ponds which is
both acid resistant and of very low permeability. In conclusion,
the design of seepage ditches must consider the area geology and
the phreatic water level of the impounding dike material to
achieve an effective seepage control system. An installation of
a pump station at the low or collection point of the seepage
ditch completes this seepage control system. The pumps serve to
move the collected seepage water back into the contaminated water
storage area. Normally these pumps are operated only a few hours
per day but this is entirely dependent upon the seepage and
rainfall conditions.
103
-------
GYPSUM POND
SEEPAGE DITCH
RETURN TO GYPSUM
POND BY PUMP
OUTSIDE OF PLANT
GYPSUM POND
BED \ \
\ x
SEEPAGE'"' v\
*— APPROXIMATELY^
10 FT. WIDE BY
ABOUT 3 FT. DEEP
.^4^^^^
Hi
SURFACE DRAINAGE
DITCH EXTERNAL TO
THE PLANT
FIGURE 21
GYPSUM POND WATER SEEPAGE CONTROL
-------
gjnrngrtiyrn[[[rPhosghate self-Contained Process
It was mentioned in the "double lime" treatment description that
the best means of reducing NH3-N from appearing in the contami-
nated water system was to prevent its entry into the water. NH3-
N enters the contaminated water principally through the ammonium
phosphate plant gas scrubber system. A secondary entry point is
by way of washdown or water spillage into a surface drainage
system. Both of these process waste streams can be segregated
along with the ammonium phosphate scrubber waters from the gypsum
pond water system and can be either introduced back into the
process or treated for ammonia removal prior to discharge into
the gypsum pond.
One means of doing this is to adjust the in-process water balance
to permit the absorption of these collected NH3-N containing
waters (Plant 001). The degree of water balance adjustment is
dependent upon the quantity of water in the two identified
streams. Reduction of these water streams to a minimum may
require design changes to maximize scrubber water recirculation.
The principal means of adjusting the ammonium phosphate process
water balance is to increase the concentration of the phosphoric
acid feed used in the plant. Normally 30-40% P2O5 phosphoric
acid is required to produce ammonium phosphates. It may be
necessary to increase this concentration to as high as 5H% P2OJ5.
This is dependent upon the water quantity to be absorbed and the
acid concentration required to produce the specific ammonium
phosphate product. Figure 22 is a sketch of this procedure.
105
-------
PUMP
CONCENTRATED
PHOSPHORIC ACID
REACTOR
TO PROCESS
FIGURE 22
DAP SELF CONTAINED PROCESS
-------
Wet Process Phosghoric Acid - Pond JJater Dilution of Sulfuric
Acid
general
The need to treat phosphate fertilizer process contaminated water
is almost entirely dependent upon the local rainfall/evaporation
ratio. This means that barring poor water management and concen-
trated periods of heavy rainfall the complex fresh water use and
pond water evaporation are essentially in balance. Therefore,
any means of making an in-process change to significantly reduce
fresh water use will create a negative water balance. In turn,
this will eliminate the need for treatment of contaminated water
and effect a no discharge condition.
There are two different methods to make an in-process phosphoric
acid process modification to permit the use of contaminated water
for dilution of sulfuric acid. Currently, the necessity of fresh
water for this dilution step represents approximately 5Q% of the
total fresh water intake to a phosphoric acid plant. Not only
does use of contaminated water for sulfuric acid dilution elimi-
nate (except for extreme weather conditions) water effluent from
a phosphate complex, but the overall P2O5 recovery of the
phosphoric acid complex is increased by that amount of P2O5 in
the contaminated water.
Both methods of accomplishing sulfuric acid dilution with pond
water are proprietary. One method is considered a trade secret.
The other is protected by patent. Either process can be added to
existent plants or included in the design of a new facility.
The trade secret procedure involves two points. One is the
mechanical means by which the dilution is made so as not to
create a pluggage problem. The second involves redesign of the
phosphoric acid reactor cooling system to remove the heat load
formerly removed by the sulfuric acid dilution cooler (Fig. 23).
The patented process was developed and has been placed in
commercial operation.
It involves sulfuric acid dilution by a two-step procedure in a
manner radically different from current practice. The details of
process control, vessel design, and materials construction are
all proprietary information (Fig. 24).
107
-------
SLURRY FEED
TO FILTER
POND WATER
WASH
i I
FRESHWATER
WASH
SLURRY TO
FILTER
o
Co
FILTER
TO DISPOSAL
AREA
A
RECYCLE ACID
TO REACTOR
HAND WATER
SLUICE
CONCENTRATED SULFURiC ACID
POND WATER FOR DILUTION
FIGURE 23
WET PROCESS PHOSPHORIC ACID SYSTEM
POND WATER USE FOR SULFURIC ACID DILUTION TO REACTOR SYSTEM
-------
FEED STREAM-POND WATER
CONCENTRATED SULFURIC ACID
PRODUCT STREAMS
DILUTED ANDCOOLED
SULFURIC ACID CONTAINS
RECOVERED P205
TO POND
FIGURE
SULFURIC ACID DILUTION WITH
POND WATER
-------
CONTROL AND TREATMENT TECHNOLOGY
NITROGEN FERTILIZER INDUSTRY
Proven technology exists and additional technology is being
developed, which will enable the nitrogen fertilizer
manufacturer, when used properly, to attain the proposed effluent
limitations.
Most of these treatment processes are reviewed in the following
paragraphs of this Section.
Ammonia Stri ppjng
This treatment method can be used on process condensate, boiler
blowdown or cooling tower blowdown from ammonia plants, urea
plants and ammonium nitrate plants for the removal of ammonia
from these streams. However, due to the large volumes of cooling
tower blowdown and the presence of scale forming contaminants in
cooling tower and boiler blowdowns this method is best suited for
the treatment of process condensate or effluent from urea
hydrolysis.
The stripping medium can be either air or steam depending on the
desired end use of the overhead vapors, the availability of a low
level heat sink and the local and national air pollution
regulations.
1.Steam Stripping
There are a number of ammonia steam stripping units in operation
in nitrogen fertilizer plants in this country. (Plants 006, 011,
015, 017, 020, and 024). These range from completely integrated
process units producing boiler feed water quality condensate to
separate units treating a process condensate effluent before dis-
charge. The concentration of ammonia in the condensate feed to
the stripper varies from 100 mg/1 to 1,300 mg/1 with the stripped
effluent ranging from 5 mg/1 to 100 mg/1 giving reductions in
some cases of better than 95H. However, the best consistent
results from an ammonia stream stripper is in the range of 20 to
30 mg/1 and this is highly dependent on the amount of steam
supplied and the pH of the contaminated feed condensate. The
stripping of ammonia from water depends on how the ammonia exists
in the water. In neutral solutions ammonia exists as NH4- while
at higher pH (11 to 12) ammonia exists as dissolved NH3_ gas. The
following equilibrium prevails:
NHU+ —*• H+ + NH3 (g)
H+ + OH- —*• H20
As the pH is increased towards 12.0 and as the temperature is
increased the reaction proceeds further to the right. Therefore,
if the stripped condensate is to be discharged, consideration to
artificially raising the pH with caustic should be made. If the
condensate is to be reused as boiler feed water then operation of
110
-------
the stripper at a higher temperature (and pressure) would be the
preferred design method.
The design and operation of an efficient ammonia steam stripping
system is not simple or straight forward. Due to deviations from
ideal conditions, the stripping column requires considerably more
transfer units than theoretical to produce a low residual ammonia
level in the stripped condensate (bottoms). One example of a
separated condensate stripping system which will produce a bottom
condensate with a residual ammonia concentration of 25 to 30 mg/1
has a process condensate feed rate of from 8.8 to 10.7 I/sec (110
to 170 gpm). The stripper column has a diameter of 0.915 meters
(3 feet) and is 12.2 m. (40 ft.) high. The column is packed with
stainless steel Pall Rings. (Figure 25)
A second ammonia steam stripping system, operating on process
condensate from an ammonia plant, employs two columns operating
in parallel with a total contaminated condensate feed of 7.6
I/sec (120 gpm). This unit recently operated for a 22 day period
producing a stripped condensate effluent averaging less than 20
mg/1 ammonia while using slightly in excess of .12 kg of steam/
liter (1 Ib. of steam/gallon) of condensate fed.
A third steam stripping unit operating satisfactorily is
completely integrated with an ammonia plant. This stripping
column takes process condensate and steam turbine vacuum
condenser condensate and steam strips the ammonia to a level that
is acceptable for boiler feed water in a 102 atm (1500 psia)
steam system. The trayed stripping column is 1.37 m (4.5 ft.) in
diameter and about 12.2 m (40 ft.) high. Some recent data
indicates that this unit is handling some HI I/sec (700 gpm) of
total condensate input. The effluent from the stripper has less
than 5 mg/1 ammonia (Fig. 26). A fourth ammonia steam stripping
unit that is completely integrated within an ammonia plant is
handling process condensate and producing a stripped effluent
that is acceptable for high pressure boiler feed water. This
plant has been in operation for more than two years.
-------
COOLING
WATER IN
OUT
TO C02 SYSTEM ~
HOT CARBONATE SYSTEM'
TO ATMOSPHERE
STRIPPER
CONDENSER
Tj
AMMONIA
STRIPPER
REBOILER/
STEAM
LEVEL
CONTROLLED
VESSEL~
CONDENSATE
POSSIBLE CAUSTIC
ADDITION
IF DESIRED/REQUIRED
CONDENSATE
FEEDTANK
TO COOLING TOWER ~
TOSEWER~
TO BOILERS~
TO RAW WATER
TREATMENT SYSTEM
FIGURE 25
AMMONIA/CONDENSATE STRIPPING
112
-------
—o
OVERHEAD
ACCUMULATOR
STRIPPER
SECOND SHIFT
CONVERTER
I
FT
R ^ ^
CONDENSATEFROM ^__
TRAP *"
4 :.--,
~~*
r S
AMMONIA
CONDENSATE
STRIPPER
J^EXCHANGERj | ^~y-^
r t i
RETURN TO HP
BOILER
1 r
I—
i
JL
KO
POT
4,br
~
^
^
^ .
•:«•_
L_T
i
Lf^5\ .
KO
POT
k^^ CONDENSATE
1 FROMVADHJM
xfxSYSTEM SYNTMFS1S
1 ^--L. ARSORRFR
| | KO
^\ SYNTHESIS
SYNTHESIS GAS FROM jf*-Z, ^"^riJ^^^o
MFTHAJMATflR ^T COMPRESSOR
MtlHAIMAIUH ^ KO
POT
Sr
SEWER
FIGURE 26
INTEGRATED AMMONIA/CONDENSATE STRIPPER UNIT
-------
Stripping
A considerable amount of work has been done on air stripping of
ammonia from waste water, but this has been in the field of
municipal waste water treatment. Although this process does have
some drawbacks, it is worth mentioning because of its possible
use in connection with nitrogen fertilizer plant waste waters.
The major drawbacks of air stripping are the very low
efficiencies in cold weather and the deposition of calcium
carbonate scale from the water on the column packing or internals
resulting in plugging.
On the other hand, test data and installation performance to date
show that the ammonia in the effluent air will not exceed 10
mg/m3 (13 ppmv) . The threshold limit for odor of ammonia is 35
mg/m3 (46 ppmv). With this type of discharge there probably
would not be any air pollution problem.
As mentioned under steam stripping, temperature and pH have an
effect on the stripping operation. However, since temperature
will be controlled by the climatic conditions, pH must be
controlled to assure complete stripping.
Although most air stripping to date has been with contaminated
waste water with less than 60 mg/1 ammonia, the results obtained
by using the proper bed depth, the proper transfer medium and the
proper surface loading rate with good control of pH have given
better than 90% removal of the ammonia. The resulting aqueous
discharge can have less than 5 mg/1 ammonia (Fig. 27).
Contrary to some reports, cooling towers are not good stripping
units for ammonia contaminated waters. Due to their construction
and air flow they are actually absorbers of air-borne ammonia
with the result that their blowdowns may contain up to 50 mg/1 of
ammonia.
114
-------
WATER IN
i
DISTRIBUTION
BASIN
FAN
AIR OUT
AIR IN
'TYPICAL FILL
• BAFFLE (TYPICAL!
WATER OUT
CATCH BASIN
FIGURE 27
AMMONIA/CONDENSATE AIR STRIPPING
From Slechta And Gulp 196?
115
-------
3.High Pressure Air/Steam Stripping
One engineering firm <30) has proposed the use of the process
steam required for the primary reformer or the process air
required for the secondary reformer as the stripping mediums for
process condensate. In each case, the stripping would be
performed at medium to high pressure (pressure high enough to get
into the primary or secondary reformer). This would require the
process condensate to be boosted up to this pressure, but if the
condensate is then an acceptable boiler feed water make-up there
would be very little energy lost since boiler feed water would
have to be boosted to the boiler pressure anyway. The overhead
vapors, whether steam/ammonia or air/ammonia, could be be
injected into the primary or secondary reformers, respectively,
without any expected problems, ammonia would be dissociated into
its elements in either the primary or secondary reformers and any
carbon dioxide that might be stripped from the condensate is
present in the reformers anyway. Any organic compounds which
strip over should also be dissociated in the reformers.
If the stripped condensate is not to be used at these high
pressures then it can be flashed to lower pressures in stages to
release any additional ammonia.
116
-------
Urea Hydrolysis
This effluent waste water treatment system is designed to process
condensate from urea plants by converting the urea through a
series of intermediate products back to ammonia and carbon
dioxide. This process is carried out at temperatures above 100°C
(212°F) and under pressures of up to 18 atm (250 psig).
Following the conversion or hydrolysis, the ammonia and carbon
dioxide are stripped off and returned to the urea process Plants
006 and 015.
One of the proprietary (38) variations of this treatment is
presented in Fig. 28. This flowsheet depicts a unit capable of
treating 4.2 I/sec (66 gpm) of process effluent, containing 4000
mg/1 urea and 3000 mg/1 ammonia. Aqueous discharge from this
treatment unit will contain 100 mg/1 and 50 mg/1 of urea and
ammonia respectively. Steam requirements for this unit are 2200
kg/hr (4840 Ib/hr) of 19 atm (265 psig) steam and 4000 kg/hr
(8800 Ib/hr) of 4 atm. (44 psig) steam. It is understood that
this unit will be offered commercially with a urea plant and a
guarantee will be given that the effluent will not contain more
than 42.5 kg (85 Ibs) of Org-N and 37.5 kg (75 Ibs) of NH3-N per
1000 kkg (1000 ton) of urea produced.
A second proprietary urea hydrolysis system is available (39,
40). This treatment unit has been installed in a urea plant in
the spring of 1973 (Fig. 29). Although only limited information
is available to date, the new unit has with some difficulty
processed the urea plant condensate giving very mixed, but in
some cases, good results. This medium size installation is being
modified from a control instrumentation standpoint and is then
expected to operate satisfactorily. Although this unit is not
completely operative yet, it is expected that, with continued
operating experience and future design modifications, this
process will be commercially available with respectable
guarantees regarding ammonia and urea levels in the effluent.
This unit consists of a steam heated vertical tower operated
under pressure, to which the contaminated condensate is fed. A
feed-'effluent heat exchanger is included to conserve energy. The
contaminants are decomposed, stripped off and recovered in the
urea synthesis section of the main plant.
h third type of urea hydrolysis treatment system is in operation
at a fairly large urea plant. The process was developed and
installed by the owner and therefore, very little detail is
available. Data obtained from this plant, however, does show
that the hydrolysis unit is operating very well. Data from the
plant with this treatment system including prill tower fallout
show organic nitrogen (as N) monthly average values as follows:
117
-------
kg/kkcr (lb/1000 Ib)
0.09
0.230
0.205
0.031
0.052
0.087
0.054
Average 0.115
118
-------
TO LP CAR BAM ATE
CONDENSER
A
I
FROM CONDENSERS
AMMONIA
WATER TANK
FIRST
DESORBER
t
HYDROLYZER
i
rr
i
STEAM
\ 7
HEAT EXCHANGER
WASTE WATER
COOLER
FIGURE 28
FT
f
TO SEWER
UREA HYDROLYSIS
-------
TO UREA SYNTHESIS
SECTION
Ni
o
PROCESS
CONDENSATE
HEAT
EXCHANGER
CONDENSATE
RECOVERY
STRIPPER
STEAM
CONDENSATE
TANK
k
^^
1
FEED PUMP
EFFLUENT
FIGURE 29
UREA HYDROLYSIS
-------
ADDENDUM
Urea Manufacturing Data
The information provided by one of the respondants was labeled in
a misleading manner in that a part of the waste water coming from
a prill tower operation was identified as shipping and blending
loss. This led to an incorrect interpretation of the data
supplied by the respondant, and of the data collected by EPA
during the preparation of urea manufacturing limitations. As a
result of comments received after the close of the public comment
period, the matter was further investigated and the correct
interpretation discovered.
A special visit was made to the exemplary plant in question,
which had been used as the basis for establishing effluent
limitations, to confirm the validity of the above referenced
comment and to collect additional data. On the basis of this
investigation it was confirmed that the comment was valid. On
the basis of the previously available data plus new data
collected during this visit, a re-evaluation of the organic
nitrogen limitations was made resulting in a substantially
increased discharge level for urea manufacturing based on best
practicable control technology currently available and best
available control technology.
The data and re-evaluation for best practicable
technology currently available is summarized as follows:
Plant 006
Monthly Averages for Organic Nitrogen
(as N} effluent from Urea Manufacturing
control
Primary
Manufacturing
kg/kkg
(lb/1000 Ib)
of product
0.130
0.132
0.204
0.109
0.057
0,098
0.266
0.109
0.070
0.112
0.083
0.095
Prill Tower
Fallout
kg/kkg
lb/1000 Ib)
of product
0.067
0.222
0.165
0.297
0.318
0.121
0.394
0.136
0.502
0.535
0.272
0.051
Total
kg/kkg
(lb/1000 Ib)
of product
0.197
0.354
0.368
0.415
0.375
0.219
0.660
0.244
0.573
0.644
0.356
0.146
Rainfall
for
Month
inches
0.70
1,
1,
85
65
3.10
1.20
1.00
5.64
3.35
4.95
50
92
5
1
4.35
Average
0.123 0.239
Revised Guidelines No,
0.175
0.379
0.500
2.93
121
-------
This data is based on daily analysis sheets supplied by plant
006.
The fallout from the prill tower is collected in the discharge
system due to seepage and rainfall washing of the area where the
dust falls. When a month of high rainfall follows a month of low
rainfall, levels of discharge increase to exceed, in some cases,
the established limitation. This is bourne out in the above
data. Depending on local conditions, it may be necessary to
average a low rainfall month and the following two high rainfall
months to achieve the established limitation.
122
-------
B:Lg|og4caJ. JtTreatmen-t^-^Nitrification and Denitrification
This possible treatment is based on the reaction of ammonia
nitrogen with oxygen in an aerated pond or basin to form nitrates
via biological oxidation. The nitrates are in turn reacted in an
anaerobic pond in the presence of a biodegradable carbon compound
to form elemental nitrogen. Although there has not been any
significant industrial use of this combination, municipal wastes
have been treated in this manner for years. Recently more and
more investigations into this type of treatment for industrial
use have been made (Fig, 30)«
The first step-nitrification-takes place in the presence of
aerobic bacteria which convert the ammonia nitrogen to nitrates.
This reaction is promoted by the degree of aeration and warm
temperatures. This step can be carried out in a lagoon, pond or
a trickling filter according to the following equations:
2NH3 + 302 —*• 2NO2- + 2H+ + 2H2O
2NO2- + 02 —"*" 2N03-
The denitrification step is an anaerobic process which occurs
when the biological micrO"»organisms cause the nitrates and
available carbon to be broken down into nitrogen gas and carbon
dioxide. The initial breakdown of the nitrates requires that
organic carbon be present. This can be in the form of methanol
in which case the following overall reaction would occur:
6NO3- * 5CH3OH —^ 3N2 + 5CO2 + 1H2Q + 6OH~
Thie reaction must be carried out in a pond, lagoon or tank under
anaerobic (all dissolved oxygen must be consumed) conditions. It
is essential that complete nitrification be obtained in a
previous pond, lagoon, etc. before the denitrification process
starts; this usually requires longer retention time and lower
load factors than are found in conventional activated sludge
plants. Continuous addition of organic carbon (e.g. methanol)
and inorganic carbon (e.g. bicarbinate) to accelerate the
denitrification step rate is possible, but costs are elevated
accordingly.
The overall oxidation-reduction process functions best with
initial ammonia-nitrogen concentrations around 25 mg/1 but
expected removals of 90% can be achieved with carefully
controlled operations.
However, there are drawbacks, with by-products and side reactions
which can give rise to odorous compounds such as hydrogen sulfide
plus the ever present sensitivity to shock loads, e.g. ammonia
spills, etc.
123
-------
AERATION PUMPS
WASTE WATER INFLUENT
TO
OUTFALL
NITRIFICATION
LIFT STATION
FIGURE 30
BIOLOGICAL TREATMENT
-------
^Exchange
Ion exchange is a unique effluent waste water treatment method in
that it not only removes the contaminants from the waste water
but it can also produce a useful end product. An ion exchange
system may consist of a cation unit, an anion unit or both, this
depends on the nature of the ions to be removed from the waste
water.
1. cation/toioni:jSegaration^Unit
The first ion exchange system that will be covered is the
integrated or combined unit containing a cation resin column and
a separate anion resin column. This unit can be used for the
treatment of waste waters containing both ammonium ions and
nitrate ions (Eig. 31). The ammonium nitrate contaminated waste
water first flows through a bed of strongly acidic cation resin
operating in the hydrogen form. The ammonium ion combines with
the cation while the H+ ion combines with the nitrate ion to form
nitric acid.
NH4N03 + R2H+ —*• R2NH« + HNO3
The acidic waste water, minus the ammonium ion, then passes
through a bed of weakly basic anion resin where the nitrate ion
combines with the resin and water is formed.
HNO3 + R2OH —> R2NO3 + H2O
The effluent water from this second bed is low in ammonia and
nitrates and can then be discharged or reused within the plant as
make-up boiler feed water, cooling tower make-up or recycled back
to the raw water treatment unit.
Each of the ion exchange resins must be regenerated. The cation
resin holding the ammonium ion can be regenerated using nitric
acid to form ammonium nitrate solution and a regenerated strongly
acidic cation resin. The anion resin holding the nitrate ion is
regenerated using a solution of ammonium hydroxide. This will
form more ammonium nitrate and a regenerated weakly basic anion
resin. The major difference between the incoming waste water and
the regenerate by-product is that the latter has a 10% to 20%
concentration of ammonium nitrate versus a few hundred mg/1 in
the raw waste water. This means that, depending on available
fertilizer products on site, this by-product may be used as is or
it may be concentrated for sale.
h continuous unit, similar to that above, is operating at Plant
022. Information to date indicates that both the ammonium ion
and the nitrate ion are being removed to levels for ammonia-N of
12 to 50 mg/1 and for nitrate -N of 6 to 40 mg/1 for a waste
stream of one million gallons per day.
2. Se 1 ective Ion Exchange for Ammonia Removal
125
-------
FROM PLANT POND
NITRIC ACID
TANK
fT"
PRODUCT
AMMONIUM
NITRATE
* N
DEMINERLIZER
— WATER
AMMONIA
FIGURE 31
ION EXCHANGE
-------
Although this treatment process has not been industrially
installed there has been enough testing to indicate that greater
than 90% of ammonia nitrogen can be removed from waste streams
containing approximately 25 mg/1 ammonia. This process (U3) is
based on a natural zeolite ion exchange resin clinoptiloite. The
resin can be regenerated with lime slurry yielding an alkaline
aqueous ammonia solution, that can be air stripped to remove the
ammonia. The stripped slurry can then be recycled to regenerate
more zeolite. The regeneration of the clinoptilolite can be
improved by the addition of sodium chloride to the recirculated
lime slurry.
04 Jr^
Oil and grease in waste water effluents from nitrogen fertilizer
complexes can be a problem especially when large rotating
machinery, such as reciprocating compressors in small ammonia and
urea plants are in use.
Oil and grease can be removed from the waste water effluents to
levels below 25 mg/1 in properly designated A* P. I. Separators
(Fig. 32) . To assist in the design of these separators, The
A.P.I, in Washington, D.C., has published "Manual on Disposal of
Refinery Wastes." The information contained in this manual is
applicable to nitrogen plants effluent waste water. Plants 003,
016 and 022 practice oil removal treatment of their waste
streams. Oil and grease from many such sources can be kept out
of the effluent by housekeeping techniques at the source. This
can be accomplished by such containment devices as drip pans.
Ammonium Hitr ate Condensate ...... ; Reuse
Flashed vapors from the neutralizer carry with them ammonia,
ammonium nitrate and some oxides of nitrogen. Partial
condensation of these vapors results in a contaminated condensate
that requires treatment before discharge.
One possible "treatment" method for this condensate stream is to
collect it and use it as the absorber feed in the associated
nitric acid plant. Refer to Figure 33 for a process description
of this treatment method. Such use would create an internal
recycle of streams from this condensate waste in which both the
ammonia and nitrate values would be recovered, i.e. overall
yields for both the ammonia and nitric acid units increased in
terms of product ammonium nitrate.
127
-------
INCOMING OIL/GREASE
NJ
CD
OIL/GREASE BEARING
STREAM
FROM PLANT
SUMP OR TANK
SAWAGED
OIL/GREASE
CLEAR WATER
EXIT
OIL/GREASE
MECHANICAL SKIMMER
TO REMOVAL
AREA
POND OR SUMP
CLEAR WATER
EXIT
FIGURE 32
OIL/GREASE REMOVAL SYSTEMS
-------
I ^ TAILGAS
NITRIC ACID
AMMONIA
TO VENT SCRUBBER
i
1
i_
COND
r*
I
i
1
»ir
REACTOR
4 ' " COOLING WATER
ENSER
-inn. nfr COOLING WATER
CONDENSED
WATER
PROCESS
RECYCLE
-' ^ TO CONCENT RA1
POR—i
SURGE
TANK
-e
MAKE-UP ACID
NITRIC ACID
A
[OR
GAS FROM CONVERTER _fc
AND HEAT EXCHANGERS ""^
r i
3SORPTIC
COLUMN
C
t
c
N
1,',"^" f, WATFR
.,_,,~_^ TRAYS
PRODUCT
^ NITRIC ACID
AMMONIUM NITRATE PLANT
NITRIC ACID PLANT
FIG01E 33
AMMONIUM NITRATE EFFLUENT UTILIZATION
-------
Page Intentionally Blank
-------
SECTION VIII
COST, ENERGY ANDNON-WATER QUALITY ASPECT
General
A detailed cost analysis of the various treatment methods
pertaining to the fertilizer industry have been summarized in the
tables of this section.
The costs discussed are listed under subcategories as
follows:
(1) Phosphate Table 2
(2) Ammonia, urea, ammonium Table 3
nitrate and nitric acid
All investment cost figures and related annual costs have
been reported in August 1971 dollars.
The treatment technologies summarized in some cases may be
utilized in series with each other to meet more advance
levels of control.
HaterjiitEffluentcTreatment^Co9t .Tables
An explanation of the water effluent treatment cost tables is set
forth to aid in understanding the magnitude of the figures set
forth therein,
Investments
This includes the traditional expenditures, such as design;
purchase of land and materials; site preparation; construction
and installation; plus those additional expenditures necessary or
required to place the treatment method into operation including
expenditures for related or needed solid waste disposal. Because
of the broad general scope, methods and processes covered,
nothing has been shown in the investments for losses due to
downtime; i.e. production halts needed to install pollution
abatement equipment. This is treated separately.
In terestgn
This is more or less self-explanatory. It is the cost of the
money used for investments on an annual basis.
Depreciation
There are numerous methods of accounting and depreciating
equipment. Because of the nature of the treatment technology and
the way it may be installed for utilization, all capital is
depreciated over a ten year period by the straight line method.
131
-------
Ogerating_and Maintenance Cogts
This is exclusive of energy and power which has been covered
under a heading of its own. Costs here include materials,
insurance, taxes, solid waste disposal, operating labor and
maintenance.
It is anticipated that maintenance, as it is normally thought of
in most processes, will be lower for the add on technology to
achieve pollution abatement. Therefore, the costs are adjusted
accordingly to reflect a lower maintenance cost.
Energy and Power Costs
Costs for energy and power include such items as electricity and
steam for pumps, agitators and evaporators/heat exchangers.
Eg fluent_Quality
The items covered are the expected parameters of the resulting
effluent after the pollution abatement technology has been
installed and placed into operation.
The raw waste load flow has been given in liters per second and
gallons per minute. Effluent level parameters are given in units
of milligrams per liter and kg/kkg of product where appropriate.
Supplemental Data
This heading is for miscellaneous data that is considered useful
in understanding or using the tables. All items are identified
as to their nature or use.
Installationand operation of Treatment Methods
It is difficult to show exactly how much will be involved in an
installation. This is attributed to the fact that no two plants
are exactly alike nor would they require the same amount of work,
equipment and land to be installed. However, hypotheses have
been made in order to permit reasonable estimations as to the
time and effort involved. All plants are of 900 kkg/day (1000
tons/day) and for the main part, considered to be existing
plants. The explanation for these items are covered in order for
Tables 2 and 3.
Since there is so much variation in time for certain types of
work to be done and equipment to be shipped, a total possible
elapsed time will be given under each treatment method. This
time span will include: engineering, procurement and construc-
tion.
Also listed separately, as it applies, will be the amount of
downtime to make equipment tie-ins and length of time for start-
up and placing the unit
-------
Phosphat e_ Subcateggry (Table 2)
Sulfuric Acid Effluent Control
Total elapsed time for engineering, procurement and construction
should be five months.
It should be possible to arrange for this work to be accomplished
and put into service with no downtime to the plant operations.
No start-up is required for this item. It should be noted that
as an alternate the effluent may be discharged back to a
retention pond or gypsum pond until control has been restored.
Pond_ifaterjTreatrnent
The elapsed time for this method in engineering, procurement and
construction should be about fifteen to eighteen months.
There should be no need to shut any plant down to install or make
tie-ins of this method of treatment.
For start-up and operations to be stabilized it will take
approximately one twenty-four hour day of continuous operation.
jypsum Pond Water Seepage control
Since this is only a secondary dike arrangement it should not
.nterfere with plant operations both in construction and placing
jump system into service.
instruction time is considered the prime requirement here. The
fork around a 80-100 hectare (200-250 acre) pond area should be
.ccomplished in ten weeks. It is not anticipated that much
tart-*up -time will be consumed to start the pumps, so time for
his effort will not be considered.
133
-------
TREBLE 2
fao&HKm SBOUEOaiBf
JUWUftU i JSgf&UEHT QURLFIY
*<^^atihg * felntespnQe
Wafer to figure I *lnteiest On. Costs {Sxplaairag Bwergy *Emsxg¥ and *!flofeal Afinual
TBS3GMNT jy^EEKSECVE ftn: ftefer^toe *InwstraSit ^^^f *Deptreeiatian aid PoMSrt Power Costa CtStS
B SaJ.£urie JkaLd $ •$ $ 5 $ $
EffltMit Control IS 232,760 17,470 23,280 9,310 5,000 S5.060
B Etm Water Treating 20 349,600 26,220 34,960 13,990 SO-.05/1QOQ 90!
treated
C Qapsun Pond lfe£fir 21 163,680 12,375 16,370 6,550 5fOOO 40,295
Seepage OczitmL
C Additimal LlBKtng
C We Self Oonkaina 22 312,800 23,468 3I,2fl» S8rSlQ 344,650 457,900
i*£0aess
D Bami Wbtec Uaei Fa 23 310,9S) 23,320 31,000 1Z^40 16S.SOO 235,260
SuUEtnrlc Acid
DUUddon to Baifctar
D POifl HEfefar Iteed Rr 23 110,400 B,280 11,040 4,420 168,500 192, 240
Sulforie Add
Biluticn to B&ae&or
D Sulfniie Add Diliition 24 368, DOS 27(6flK> 36/SOQ 14,720 22,400 101,520
Midh Bond Water
Htespgy HN toiv' ^^ Kaste l^w Ifeste Itesiiifcing Effluent gNapploamtal Data
tear I^aa3 l£iad level
litera^Sec GMP Mg,?*L
.31 63.0 1000 pH 6,0-9.0
63,0 1000 1*1 6,0-9,0 F 30
P 40, N 40 See note beLcw
*31 252 4000 HO disetenp
PH 6-0-9, F 15
F 30
21-5 Not ftppli™ Not: finxUL- No diac*iarg& this is &n «*n*i^e»rator to
cabla cable ooeKsentrate feed st!i^wi
10 . 5 Ktafc flppli- ftat ftp^ili.^ Ho diadhaige
cabte cable CoBt, of mM on to
10,5 Hot flppli- sot ftppli* Sb dlseha»3» Ccst of ^KUng this aystaB
qable C^Jle to a rsarf pl^it (B)
JU t !*ofc ^jpll* He* j^pli* ND diSEJiarge CB)
1 All out tigaam an fcar'"^juat
EW material $1.40 ier 1000
SO.SA px 1000 gaUms tnslaii; tutal ownll cost
31,90 per 1000 gallam
-------
PAIL.Se 1 f nr.Cont.ained: Process
This system is one that is to be added to an existing unit and
will require installation of an evaporator and related
auxiliaries to concentrate the feed acid stream. This creates
the negative water balance necessary, to utilize the water from
the local area.
Engineering, procurement and construction time should be about
twelve months.
The system can be pre-constructed ready for tie-in. Only one
eight-hour day will be required to tie the unit in. If this work
is scheduled around a routine wash day in the phosphoric acid
plant there will be no downtime in production.
The start-up and operations should be done and the unit
stabilized in approximately twenty-four to forty-eight hours.
Operational coverage for this unit should be no more than one
half a man per shift at an annual cost of approximately $40,000
to $46,000.
Pondwater^Use^For^Suj.f uric_Rc|d_pj.lut ion-i:E JInternal _Method)
There are two types of costs listed here. One is for adding to
an existing system and the other is for a new plant installation.
The time required for a new plant installation is not involved
with causing a plant shutdown for tie-in; therefore, it will not
be considered for engineering, procurement and construction.
Similarly it is not considered for start-up or operations.
Time required to revise an existing plant is rather complicated
and complex. The hard part of this job is installing a new
larger flash cooler system in place of the existing flash cooler
system.
The entire elapsed time for engineering, procurement and
construction should be about six to eight months.
After considerable pre-fabrication has been completed, the plant
will then have to be shut down for three to four weeks of
intensive change out work on the equipment.
This type work could be planned and executed around an annual
turn around which would reduce the unproductive plant downtime to
one to two weeks.
The new system would be so similar to the existing system that
there should be no additional time required for start-up and
operation of the modified system.
135
-------
EFFUJEtfl QUALITY
SLBCPBfOCKf
Ammonia
Urea
Anmonium
Nitrate
Refer to Figure 1 *lnterest On
TREAnMUfl? ALTERNATIVES Par Reference Investment Mcney *Dspreciatir
$ $ $
B AnracniaA*»3ensate 25 217,920 16,335 21,790
Stripping
B Integrated Armenia/
Condensate Stripping 26 112,700 8,455 11,270
System 32 20,424 1,530 2,040
C Biological Treatnent
Nitrificaticn-^enitrificaticn 30 110,000 8,250 11,000
E AnnoniaA^ondensate Air
Stripping 27 96,600 7,245 9,660
B Hydrolysis Urea 28 231,000 17,325 23,100
C Urea Hydrolysis 29 153,180 11,490 16,650
B Nitrate Removal by Ion
Exchange 31 580,000 43,500 58,000
C Biological Treatment
Nitrttlcation-DMiitrification
E Anncnium Nitrate Effluent
Utilization 53 132 ,020 9 ,900 13,200
* All oast figures are for August 1971
•Operating & Maintenance
Costa (Excluding
$
8,720
4,510
817
24,400
1,260
9,240
6,130
183,200
5,280
*Energy and
Fewer Costs
$
196,815
120,500
5,600
12,300
5,250
149,220
54,650
132,000
29,200
*Total
Animal
Costs
$
243,660
144,735
10,000
55,950
23,415
198,910
88,920
418,000
57,585
Energy *M kwh/ Raw Waste
Year Load
Liters/Sec
12.3 17.6
7.5 17.6
.35 6.3
.77 27.4
.33 17.3
9.3 4.15
3.4 1.6
8.2 63.5
1.8 5.05
Raw Waste Resulting Effluent
Load Level
GPM Mj/L
280 25 NH3-N
280 25 NH3-N
100 >25 Oil
5 NH3-N
435 5 NO3-H
275 10 NH3-*I
50 NH3-N
66 100 ORG-N
26 30 NH3-K
60 OfiG-N
40 t«3-N
1010 40 NH3-N
80 —
Resulting Effluent
Level
lb/1000 ten
84 KH3-N
84 NH3-N
>30 Oil
33 H**
40 NH3-N
80 ORG-N
9.4 NH3-N
19 ORG-N
485 NH3-N
485 N03-N
-
Supplemental Data
(A)
(A)
(A)
'
(A)
(B)
(B)
(C)
See Anocnia Alternative C
Use effluent as nitric a*-*'*
ahoccber mekeif) (O
(A) 900 kkg/dcy (1000 ten/day) AmrOTia Plant
(B) 900 kkg/day (1000 ton/day) Urea (Total ftscycle) Plant
(C) 900 kkq/day (1000 tnVaay) amcnium Nitrate Plant
-------
The start-up and operation should be very similar to that
mentioned for ammonia/condensate stripping. There is no need for
extra personnel to give this unit coverage.
Ammonia/Condensate Air Stripping
The easiest way to explain this system is to say that it is very
similar to a cooling tower. To design, procure and construct.
such a unit can be from twelve to fourteen months.
The tie-in to the plant will require about twelve to twenty- four
hours.
Also there is no anticipated need for extra personnel to operate
this unit.
Proprietary Urea Hydrolysis
The design engineering, equipment procurement and construction
should be completed in approximately ten months.
The plant will be shut down for equipment tie-ins for about
•twelve to thirty-six hours.
This treatment method is a little more complex. Therefore, it is
more involved to start up. The unit is brought on line
simultaneously as the plant start up, but to gain positive and
stable control of the unit could vary from twelve to thirty
hours.
The unit in the early stages of st.art-up and operation could
involve one half to one man per shift, when the unit becomes
checked out and the operators educated as to the operations of
the unit the extra personnel may be phased out. This increased
need may exist for four to six weeks. The cost, of extra coverage
could vary from $4,400 to $12,500.
Proprietary Urea Hydrolysis
The unit is not considered complex and should take about ten to
twelve months for design, procurement and construction.
The tie-in of the unit should involve no more than six to eight
hours of down time for the plant.
When the unit is ready it will come on line when the plant is
started. Although the operator may not become very involved
during the start-up, the unit will require increased monitoring
until the operating and plant personnel are familiar with the
unit and its limitations. This could involve one half to one man
per shift for two to four weeks. After the unit is stabilized
the extra personnel may be phased out..
The increased opera-ting surveilance could amount from $2,000 to
$9,000.
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Biological Treatment {Njtrification-Denitrification)
Design, procurement and construction time could be twelve to
fourteen months.
There is not enough start-up time involved to be considered.
However, there will be monitoring time involved during the normal
unit operations. It is estimated that about one quarter of a man
will be utilized at an approximate cost of $19,000 to $20,000.
Ammonium Nitrate Removal by Ion Exchange
This system is somewhat more complex and involved than most of
the treatment methods discussed thus far.
To design, procure and construct the ion exchange system will
take from fourteen to sixteen months.
The start-up and operation of this unit to date has experienced
some difficulty; mainly mechanical. This makes it somewhat
difficult to delineate the exact needs for operation of future
installations.
It is anticipated that two persons per shift will be required to
operate the unit. The cost of such labor will be approximately
$145,000 to $160,000 on an annual basis.
Oil/Grease Removal
The oil/grease removal systems may be used as single units or in
series. For this study they are used in series.
To design, procure and construct such a unit would take
approximately eight months.
There is no start-up and operation time involved so this is not
considered. It is not felt that these units will require
additional personnel to monitor or operate them.
Ammonium Nitrate Effluent Utilization
There is not much involved in this system. It should take about
eight to ten months to design, procure and construct the modified
system.
The plants should be down not more than two to three hours for
the final equipment tie-ins.
This system is unique in its possible mode of operation. It must
be so designed to enable the ammonium nitrate and nitric acid
plants to operate independently of one another or in tandom with
one another. The start-up of either unit should require a few
minutes to set up and initiate. The switching from one unit to
the other should be very easy and quick to execute with no ill
effect on the operations of the nitric acid plant.
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With the above in mind, no time is considered for start-up and
operation of the system.
There is no increase in requirements for operating labor.
140
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Non-Water Quality Aspects of Treatment and Control Technologies
Phosphate Fertilizers
The treatment and control technology proposed for use by the
phosphate fertilizer industry to meet the guidelines does not
have any deleterious non-water quality aspects. There are no air
pollution, noise pollution or identifiable solid waste disposal
problems associated with the proposed waste water treatment
methods.
Containment of contaminated recirculated (gypsum) water must not
be accomplished with fluorine loses from scrubbers or ponds. Nor
must containment be achieved by percolation to ground waters (or
horizontal subsurface loses).
Nitrogen Fertilizers
There is one possible and one real air pollution control problem
that may exist with some treatment methods. At present, there
are no air pollution regulations on ammonia. When considering
the ammonia stripping process using either air or steam, one must
be concerned about where the ammonia is going, most of the time
into the air. Tests have shown that with air stripping, the off
gas concentration contains less than 10 mg/m3 (13 ppmv). Since
the threshold odor for ammonia is about 35 mg/m3 (46 ppmv) there
would not be any noticeable odor around the stripping operations.
The maximum allowable OSHA concentration of ammonia in air (on a
time weighted basis) is 35 mg/m3 (46 ppmv). Since this also is
greater than the expected gas effluent and surrounding air
concentration, air/steam stripping of ammonia is not expected to
cause any air pollution problems.
Although the anaerobic (without free oxygen) denitrification
process has been used for years, especially in the municipal
sewage treatment plants, it is a process that tends to be more of
an art than a science. The operations of an anaerobic treatment
of denitrification pond can take a great deal of care. The
internal reaction occurring can lead to the formation of hydrogen
sulfide if there is any sulfur present that can create an odor
problem. Therefore, care should be taken when considering the
installation of a denitrification pond as to the location of the
plant site in relation to the wind direction and the nearest town
or inhabitants.
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SECTION IX
BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
AVAILABLE
GUIDELINES AND LIMITATIONS
INTRODUCTION
The effluent limitations which must Jbe 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 fertilizer 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 technology currently available
emphasizes treatment facilities at the end of a manufacturing
process but also includes the control technology within the
process itself. Examples of in-process control techniques which
are used within the industry are:
Manufacturing process controls *recycle and alternative uses
of water "recovery an/or reuse of waste water constituents
*dry collection of airborne solids instead of (or prior to)
wet scrubbing.
Consideration was also given to:
a. The total cost of application of technology in relation
to the effluent reduction benefits to be achieved from
such application;
b. The size and age of equipment and facilities involved;
c. The process employed;
d. The engineering aspects of the application of various
types of control techniques;
e. Process changes;
f. Nonwater quality environmental impact (including energy
requirements).
PROCESS WASTE WATER GUIDELINES
Process waste water is defined as any water which during the
manufacturing process, comes into direct contact with raw
materials, intermediates, products, or by-products. Cooling
tower water is not covered in these limitations but will be the
subject of a later study by EPA. All values of guidelines and
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limitations are expressed as consecutive 30 day averages in units
of kilograms of parameter per metric ton and pounds of parameter
per 1000 pounds of product produced except where they must be
expressed as a concentration.
Maximum daily values of two times the 30 day averages are
established. Because extensive long term data is not available
for each of the subcategories it is necessary to rely on data
from other parts of the fertilizer industry as well as data from
other similar industrial categories. Based on this information
and using good engineering judgement on the reliability of the
treatment systems involved, a factor of two appears generous.
Based upon the information contained in Sections III through VIII
of this report, the following determinations were made on the
degree of effluent reduction attainable with the application of
the best practicable control technology currently available to
the fertilizer manufacturing industry.
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PHOSPHATE SUBCATEGORY
GENERAL DESCRIPTION
Eleven phosphate fertilizer plants were surveyed and studied to
determine the levels of pollutants being discharged and the
effluent treatment methods being used for control. Phosphate
fertilizer plants do not need to discharge process waste water
(gypsum pond water) continuously. The pond water is re-used in
the process and a discharge is needed only when there is rainfall
in excess of evaporation. For this reason limitation quantities
are not based on production but on rainfall conditions. The
effluent quality is based on the characteristics of properly
treated water released from the gypsum pond.
Best Practicable control Technology Currently Available includes:
A. Gypsum Pond ^Contaminated) Water Treatment
Double lime treatment of gypsum pond water has been in
industrial use for some 15 years. First stage treatment
takes the pH to 3.5 to 4.O. second stage treatment takes the
pH to 6.0 to 9.0. This reduces the phosphate (as P)
concentration to 10-40 mg/1 and the fluoride (as F)
concentration to 15 or less mg/1. Radium 226 is precipitated
to a sufficiently low concentration by lime treatment to a pH
of 8.0. Pond design and operation to leave enough freeboard
to contain a 10 year storm is required as best practicable
control technology. Operation to maintain the required
freeboard can include proper treatment and release of water.
B. Sulfuric Acid Plan-L Effluent Control
This effluent control and treatment technology is in current
industrial use. The technology is primarily one of
preventing contamination of natural drainage water from
accidental equipment break or operator error. It provides
for a monitoring system to signal that an emergency exists
followed by facilities for contaminated water isolation and
subsequent reuse. A more detailed discussion of this
technology is included in Section VII.
Effluent Limitations Guidelines
The following limitations constitute the quantity or quality of
pollutants or pollutant properties which may be discharged after
application of the best practicable control technology currently
available by a point source.
1. Subject to the provisions of paragraphs (2), (3) and (4)
there shall be no discharge of process waste water
pollutants into navigable waters.
2. A process waste water impoundment which is designed,
constructed and operated so as to contain the
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precipitation from the 10 year, 24 hour rainfall event
as established by the National Climatic Center, National
Oceanic and Atmospheric Administration for the area in
which such impoundment is located may discharge that
volume of process waste water which is equivalent to the
volume of precipitation that falls within the impound^
ment in excess of that attributable to the 10 year, 24
hour rainfall event, when such event occurs.
3. During any calendar month there may be discharged from a
process waste water impoundment either a volume of
process waste water equal to the difference between the
precipitation for that month that falls within the
impoundment and the evaporation for that month, or, if
greater, a volume of process waste water equal to the
difference between the mean precipitation for that month
that falls within the impoundment and the mean
evaporation for that month as established by the
National Climatic Center, National Oceanic and
Atmospheric Administration for the area in which such
impoundment is located (or as otherwise determined if no
monthly data have been established by the National
Climatic Center).
4. Any process waste water discharged pursuant to paragraph
3 of this section shall comply with each of the
following requirements:
Parameter Maximum daily Maximum average of daily
concentration values for periods of discharge
covering 10 or more consecutive days
mg/1 mg/1
phosphorus as(P) 70 35
fluoride as (F) 30 15
total suspended
nonfilterable
solids 50 25
The pH of the water discharged shall be within
the range of 8.0 to 9.5 at all times.
Rationale for Best Practicable control Technology
Currently Available
The criteria used for selection of the treatment technology was
information obtained at exemplary plants through sampling;
inspection and review of plant operations; collection of
validated historical effluent data; and direct discussions with
responsible plant operational personnel for positive definition
of treatment methods and analytical procedures. Additional
information was gathered from technical literature, direct
contacts with experts and consultants, and discussions with
/endors of treatment equipment and services. Consideration was
also given to application of industry transfer technologies for
specific contaminant treatment.
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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 proposed effluent limitations for fluorine, phosphate, and pH
represent an unusual effluent situation which warrants further
discussion. Several factors need to be recognized. One is there
is only a periodic need for effluent treatment and discharge.
This need.always results from excessive rainfall.
Another factor is the treatment limitations. Particular
reference is to the residual P levels after even the second lime
neutralization step. The degree of P reduction is a function of
pH level. At a pH of 6 the residual P in the treated water will
range 10-60 mg/1. Additional neutralization (third stage) to
raise the treated water pH to 9-11 will effect a P level
reduction to the 2-25 mg/1 range.
A limitation for ammonia (as N) was established in the proposed
guidelines but was dropped from the requirement. This was done
because control required a process change and because ammonia
levels in existng gypsum ponds are very high. Lime treatment
does not reduce the ammonia content of the effluent. The control
technology for control of ammonia is the ammonium phosphate self-
contained process. During normal operation this process does not
release ammonia to the gypsum pond water system. The source of
ammonia in the pond water is equipment wash out contaminated
water sprays from other process units and other non-point
sources. One plant that uses the self-contained ammonium
phosphate technology has an N concentration in the range of 25-66
mg/1 in the gypsum pond water. The higher levels to 600 mg/1
occur when there is no pond water discharge. Additional
collection and treatment of ammonia laden wastes can be carried
out if necessary to maintain low ammonia nitrogen concentration.
Double lime treatment to a pH of 8.0 ato 9.5 is required to
achieve Optimum removal of radium 226 to minimize its hazards.
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NITROGEN FERTILIZER INDUSTRY
GENERAL DESCRIPTION
The survey (described in detail under section III) of exemplary
nitrogen fertilizer plants was conducted as part of this project
to determine what level of contaminants was in the effluents from
these plants and what were the treatment methods in use to
maintain these levels. This survey data did indicate that there
were some process plants which could be considered exemplary.
Verifying the present treatment methods in use and those
treatment methods that are still being developed, the following
technology is considered to be the best practicable and currently
available which is needed to meet the 1977 requirements:
Best Practicable control Technology Currently Available Includes:
A. Ammonia Steam Stripping
This treatment technology is in operation today in the plants
whose effluents are within the newly proposed guidelines for
ammonia-N. Although each nitrogen fertilizer complex is
different, steam stripping of ammonia contaminated waste
water is the best practicable method of control.
B. Urea Hydrolysis
This type of technology is used in various forms and to
various degrees in urea plants today to give an effluent
waste water that will meet the newly proposed ammonia-N
guidelines. Although some of these hydrolysis units are
company designed, commercial units that will meet the
effluent limitations are available from several different
sources.
C. Containment (Ammonium Nitrate)
Leak control, spill control, containment and re-use of waste
material and good housekeeping is the technology to be used
to meet effluent limitations for ammonium nitrate.
D. Containment /Nitric Reid)
Nitric Acid is produced with no process waste water
discharge. Leaks and spills are controllable and can be re-
used in a nitrogen fertilizer complex. Cooling water will be
the subject of a later EPA study.
2. Oil Separation
Design technology for API oil separators has been used
effectively for years and can now be applied to the nitrogen
fertilizer industry. Segregation of oil laden streams and
148
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separation of oil from these streams will be needed to
achieve a satisfactory effluent.
Proposed Effluent Limitations Guidelines
The following guidelines are the effluent waste water limitations
for the ammonia, ammonium nitrate, nitric acid, and urea
sufccategories.
Parameter Units Subcategory
Ammonia U£ea. Ammonium Nitrate
NH3-N kg/kkg of product 0.063 0.0375 0.0375
~~ (lb/1000 Ib) 0.05* 0.1*
Organic N kg/kkg of product - 0.175
(lb/1000 Ib) 0.5*
NO3^N kg/kkg of product - - 0.05
(lb/1000 Ib) 0.11*
*Effluent limitations for plants that prill their product.
The above limitations apply to the maximum average of daily
values for any period of 30 consecutive days. For ammonia (as N)
and nitrate (as N) the maximum for any one day is twice the 30
day maximum average. For organic nitrogen (as N) the maximum for
any one day is 2.5 times the 30 day maximum average. pH shall be
within the range of 6.0 to 9.0 at all times.
No discharge of process waste water pollutants is the limitation
for the nitric acid subcategory.
Rationale 6 Assumptions for Selection of Technology
The guidelines used for selection of the treatment technology
which is required to meet the proposed 1977 effluent limitations
have been based on material obtained through sampling, data
taking, information gathering, and direct conversation with plant
operating personnel at each of the fifteen plants contacted on
the exemplary plant survey. Additional information in the form
of available literature, direct contacts and vendor contacts was
also considered. Treatment methods which are being successfully
used in other industries were analyzed for their possible use in
the fertilizer industry.
The limitation numbers are based on the best judgment of what is
reasonably obtainable after careful analysis of time weighted
data over periods of up to two years. These guideline numbers
represent effluent levels that have been met by some of the
exemplary plants and can be conformed with by any of the nitrogen
fertilizer plants which will employ best practicable control
technology currently available.
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Ammonia steam stripping is one treatment method which is being
used by the fertilizer industry successfully at a number of
locations. Ammonia steam stripping is also in use in the
petroleum industry. Steam stripping of ammonia has the drawbacks
of what to do with the ammonia. Under present circumstances, it
is proposed that this ammonia be vented to the atmosphere either
through the carbon dioxide stripper, reformer stack, or an off
site boiler stack. The ammonia concentration in the gases from
these stacks is not expected to be above 35 mg/m3(46 ppmv) which
is the threshold odor limit for ammonia and, therefore, should
not present an air pollution problem.
The urea hydrolysis units that are operating in the industry can
produce an effluent v?hich is acceptable for the guidelines.
Existing units have had some mechanical problems but these
problems can be solved with improved engineering and additional
operating experience. Also there are a number of contracting
companies who will offer this treatment method.
The ammonium nitrate limitations are based on the average of the
best three plants studied that do not use ion exchange. They
achieve this level of performance by leak control, spill control,
good housekeeping and containment and reuse of waste material.
Ion exchange for treatment of ammonium nitrate wastes is being
developed but has been judged to be very expensive and
incompletely developed for use as best practicable control
technology currently available.
Limitation for oil and grease was considered for the ammonia and
urea subcategories where compresssors are used. However, the
reproducibility of the oil and grease test is poor at the low
concentrations that occur when properly controlled in this
industry. For this reason, no limitation is established but
control based on appearance of the effluent and water quality
will require segregation and separation for oil removal.
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SECTION X
BEST AVAILABLE TECHNOLOGY ECONOMICALLY
ACHIEVABLE
INTRODUCTION
The effluent limitations which must be achieved by July lr 1983
are based on the degree of effluent reduction attainable through
the application of the best available technology economically
achievable. For the fertilizer manufacturing industry, this
level of technology was based on the very best control and
treatment technology employed by a specific point source within
the industrial category or subcategory, or where it is readily
transferable from one industry process to another. Best
available technology economically achievable places equal
emphasis upon in-process controls and control or treatment
techniques employed at the end of a production process.
Those plant processes and control technologies which at the pilot
plant, semi-works, or other level, have demonstrated both
technological performances and economic viability at a level
sufficient to reasonably justify investing in such facilities
were also considered in assessing best available technology
economically achievable. This technology is the highest degree
of control technology that has been achieved or has been
demonstrated to be capable of being designed for plant scale
operation up to and including no discharge of pollutants.
Although economic factors are considered in this development, the
costs for this level of control reflect the top- of-the-line of
current technology subject to limitations imposed by economic and
engineering feasibiligy. However, best available technology
economically achievable may be characterized by some technical
risk with respect to performance and with respect to certainty of
costs. Therefore, this technology may necessitate some
industrially sponsored development work prior to its application.
The following factors were taken into consideration in
determining best available technology economically achievable:
a. The age of equipment and facilities involved;
b. The process employed;
c. The engineering aspects of the application of various
types of control techniques;
d. Process changes;
e. cost of achieving the effluent reduction^resulting fron
application of best available technology economically
achievable
f. Non-water quality environmental impact (including energy
requirements).
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PROCESS WASTE WATER GUIDELINES
Process waste water is defined as any water which, during the
manufacturing process, comes into direct contact with raw
materials, intermediates, products, or by-products.
Based upon the information contained in Sections III through IX
of this report, the following determinations were made on the
degree of effluent reduction attainable with the application of
the best available control technology economically achievable in
the various subcategories of the fertilizer manufacturing
industry.
PHOSPHATE SyBCATEGQRY
Best available technology economically achievable includes:
Wet Process Phosphoric Acid - Pond Water
Dilution of Sulfuric Acid
This technology serves to insure a negative water balance in a
phosphate fertilizer complex. That is, there will always be need
for fresh water addition to the process units under the
assumption that reasonable water management is practiced. With a
negative balance, no discharge is required except under extreme
weather conditions in which the recirculating water containment
volume is exceeded.
The treatment involves an in-process change in the procedure for
diluting sulfuric acid. Two different methods have been
developed to circumvent the problems of equipment pluggage
formerly experienced when contaminated (gypsum pond) water was
used for such dilution. As previously mentioned, both of these
methods are proprietary but are commercially available.
Proposed Best Available Technology Economically Achievable
The proposed effluent limitation representing the degree of
effluent reduction obtainable by the application of the best
available technology economically achievable is no discharge of
process waste water pollutants to navigable waters. A discharge
is only allowed under the following condition. A process waste
water impoundment, which is designed, constructed and operated so
as to contain the precipitation from the 25 year, 24 hour
rainfall event as established by the U.S. National Weather
Service for the area in which such impoundment is located, may
discharge that volume of precipitation that falls within the
impoundment in excess of that attributed to the 25 year, 24 hour
rainfall event, when such event occurs.
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RATIONALE FOR BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
The use of the best available technology economically achievable
on sulfuric acid dilution in a phosphoric acid plant is only
recently proven commercially in the U.S. This is also true of
both the described processes. There is, however, sufficient
industrial experience, confidence, and warranty available on one
of the treatment methods to justify its incorporation into the
design of two other large new units which will come on stream in
1974. The other method has had a unit very similar to the
patented method in commercial operation for approximately two
years. The unit now in operation is a more refined version of
the same process and has proven its ability to function well by
use of correct construction materials. Both methods are
considered to be technically proven and viable technologies.
The use of pond water for sulfuric acid dilution reduces fresh
water consumption by approximately 50% in a phosphoric acid
plant. It also provides an attractive financial payout on
phosphoric acid operating efficiency by reclamation of water
soluble P2IO.5 values in the gypsum pond water. It is also
possible through better reclamation procedures of uncontaminated
steam condensate streams to make the negative fresh water balance
even more negative.
Based upon the above discussion regarding best available
technology economically achievable, it is considered practical
and economical to establish a no discharge limitation on
phosphate complex effluent.
NITROGEN FERTILIZER INDUSTRY
The following technology is considered to be the best available
technology economically achievable:
A. Ammonia steam stripping followed by either high flow ammonia
air stripping or biological nitrification-denitrification.
This combination can be designed to keep the ammonia nitrogen
well within the 1983 guidelines.
B. Continuous ion exchange followed by denitrification. This
treatment system can provide the technology to maintain the
nitrate nitrogen within the effluent guidelines.
C. Advanced urea hydrolysis followed by high flow ammonia air
stripping. The urea hydrolysis technology is fast improving
and will be capable of meeting the proposed guidelines.
Proposed Best Available Technology Economically Achievable
The following guidelines are recommended as the effluent waste
water limitations from the ammonia, nitric acid, urea and
ammonium nitrate subcategories:
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Parameter Units Subcategory
Ammonia Urea Ammonium_Nitrate
NH3-N kg/kkg of product 0.025 0.015 0.0075
(lb/1000 Ib) 0.015* 0.0075*
Organic N kg/kkg of product - 0.025
(lb/1000 Ib) 0.0375*
N03-N kg/kkg of product - - 0.0125
(lb/1000 Ib) 0.0125*
* Effluent limitations for plants that prill their product.
The above limitations apply to the maximum average of daily
values for any period of 30 consecutive days. The daily maximum
average is twice the 30 day maximum average. pH shall be within
the range of 6.0 to 9.0
No discharge of process waste water pollutants is recommended for
the nitric acid subcategory.
Rationale and Assumptions for Selection of Technology
Because there will be changes before 1983, the economic analysis
of any treatment system will change. Therefore, the selection of
1983 technology is based more on the availability of processes
than on detailed economics. The possibility of new improved
technology being developed between now and 1983 can only enhance
the owner-operators choice of treatment methods capable of
meeting these guidelines.
Much of the technology proposed is still in the development stage
such as high flow air and steam stripping, continuous ion
exchange and advanced urea hydrolysis. However, progress to date
shows that much of the remaining work deals with mechanical
improvement, control instrumentation and equipment modifications
which should make each one of these processes completely
functional.
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SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
AND PRETREATMENT RECOMMENDATIONS
INTRODUCTION
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); and
f. Recovery of pollutants as by-products.
PROCESS WATER GUIDELINES
Phosphate Subcateqory
It is recommended that new source performance standards be
identical to the 1983 limitations for all new phosphate
fertilizer plant sources.
155
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Nitrogen^Fertilizer Industry
General Discussion
In addition to the treatment technologies listed under the 1977
and 1983 technologies the following process modifications and
plant arrangements may be considered.
Best Demonstrated Technology (Process Improvements}
A. Integration of an ammonia process condensate steam stripping
column into the condensate-boiler feed water system of an
ammonia plant with or without further stripper bottoms
treatment depending on boiler quality make-up needed.
B. Building of adequate sized urea and ammonia plants so that
centrifugal rather than reciprocating compressors can be
used.
C. Designing in contaminated water collection systems so that
common contaminant streams can be segregated and treated in
minor quantities for improved efficiencies and reduced
treatment costs.
D. Location of plant cooling tower up wind of the prevailing
wind direction to minimize the chance of absorbing ammonia in
the tower water.
E. Design of a low velocity air flow prill tower for urea and
ammonium nitrate to minimize the dust loss. This can reduce
the yield loss around the prill tower from 3% down to less
than 0.5% with a corresponding reduction in the raw waste
load.
F. Design for a lower pressure steam level, say 41.8 atm (600
psig) to 62.2 atm (900 psig), in an ammonia plant to make
process condensate recovery easier and less costly.
G. Install air cooled condensers and exchangers where possible
to minimize cooling water circulation and subsequent
blowdown.
Proposed New Source Performance Standards
The following guidelines are recommended for new source effluent
waste water standards from the ammonia, urea, nitric acid,
ammonium nitrate and subcategories:
156
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Parameter Units SubcatecrorY
Ammonia Urea Ammonium Nitrate
NH3-N kg/kkg of product 0.055 0.0325 0.025
(lb/1000 Ib) 0.0325* 0.05*
Organic-N kg/kkg of product - 0.12
(lb/1000 Ib) 0.35*
NO3--N kg/kkg of product - - 0.0125
(lb/1COO Ib) 0.025*
* Effluent limitations for plants that prill their product. The
above limitations apply to the maximum average of daily values
for any period of 30 consecutive days. The daily maximum average
is twice the 30 day maximum average. pH shall be within the
range of 6.0 to 9.0 at all times.
No discharge of process waste water pollutants is recommended for
the nitric acid subcategory.
Rationale 6 Assumptions in the Development of New Source
Performance standards
One major problem in trying to treat waste water contaminants is
that of dealing with large quantities of water with very dilute
contaminant concentrations. Most existing plant complexes have
very limited facilities for keeping different waste waters
separated and, therefore, any treatment system installed has to
handle large amounts of effluent waste water. The construction
of a new process plant and more noticeably a nitrogen fertilizer
complex allows the design of a contaminated water separation/
collection system to allow more efficient, less costly treatment
of contaminants. More improved use of plant water including
recycling should also aid in treating waste effluents.
Best available technology currently available is applicable to
new sources as it becomes available on a commercial basis;
however, all best practicable control technology currently
available can be up-graded to treat "concentrated/separated"
waste water effluents from new plants to meet the New Source
Performance Standards. Therefore some effluent limitations for
new sources are less stringent than those for the 1983 standards
because the technology is still being refined. Of particular
importance is the placement of cooling towers in relation to the
ammonia, air emissions sources. Downwind absorption of ammonia
by recycled cooling water can significantly contribute to the raw
waste load. New plants have the freedom of plant arrangement
that existing plants do not. Furthermore, through good
engineering design, new plants should be able to eliminate the
problem at the source by minimizing air leaks. Since much of the
1983 technology is not commercially available, the above
limitations represent engineeringing judgment as to what
157
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improvements can be implemented beyond best practicable control
technology currently available.
Pretreatment Requirements for New sources
The type of waste water effluent that is discharged from a
nitrogen fertilizer complex contains compounds, such as ammonia
nitrogen and nitrate nitrogen, that would pass through a typical
activated sludge or trickling filter waste water plant and
therefore this waste water at its normal concentration levels
would not be amenable to treatment by conventional biological
treatment processes. No discharge of process waste water
pollutants from new sources to publicly owned treatment works is
recommended for the phosphate and nitric acid subcategories. For
the remaining subcategories pretreatment and treatment provided
by the publicly owned treatment works must sum to equal the
effluent limitations for discharge to navigable waters for new
sources if a discharge to publicly owned treatment works is to be
allowed.
158
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SECTION XII
ACKNOWLEDGEMENTS
The Environmental Protection Agency would like to thank Mr.
Robert Heinz, Mr. Edgar Bailey and Mr. Donald Ross of Davy
Powergas, Inc. for their aid in preparation of this report.
The project officer would like to thank his associates in the
Effluent Guidelines Division, particularly Messrs Allen Cywin,
Ernst P. Hall, Walter J. Hunt and Michael W. Kosakowski for their
valuable suggestions and assistance.
Special appreication is given to the secretarial staff,
especially Ms. Sharon Ashe, Ms. Kay Starr, Ms. Chris Miller and
Ms. Nancy Zrubek, for typing and revision of this and the
accompanying documents. Appreication is also given to Ms. Kit
Krickenberger who coordinated the secretarial staff assignments.
Thanks are also given to the members of the members of the
EPA working group/steering committee for their advice and
assistance. They are:
Mr. Walter J. Hunt, Effluent Guidelines Division, Chairman
Mr. Elwood E. Martin, Effluent Guidelines Division, EPA.
Mr. Harry Trask, Office of Solid Waste Management Program, EPA.
Mr. John Savage, Office of Planning and Evaluation.
Mr. Srini Vasan, Region V,
Dr. Edmond Lomasney, Region VI,
Mr. Paul DesRosiers, Office of Research and Monitoring,
Dr. Murray Strier, Office of Permit Programs,
Mr. Ray McDevitt, Office of General Counsel,
Mr. Richard C. Insinga, Office of Planning and Evaluation.
Dr. Robert R. Swank, Jr., Office of Research and Development,
NERC - Corvallis, Athens, Georgia.
Mr. Michael w. Kosakowski, Effluent Guidelines Division,
Acknowledgement and appreciation is extended to the following
companies, institutions, associations, laboratories, agencies,
and persons for their help, assistance and cooperation in
providing information:
1. Borden Chemical company, Piney Point, Florida
2. Royser Fertilizer Company, Mulberry, Florida
3. American Cyanamid, Brewster, Florida
U. Agrico Chemical company, South Pierce, Florida
5. W. R. Grace, Mulberry, Florida
6. Gardinier (USPP), East Tampa, Florida
7. Apple River Chemicals, East Dubuque, Illinois
8, cooperative Farm Chemicals Association, Lawrence, Kansas
9. Phillips, Hoag, Nebraska
159
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10. Cominco-American, Hoag, Nebraska
11. Chevron Corporation, Ft. Madison, Iowa
12. North Carolina Nitrogen Complex, Tunis, North Carolina
13. central Farmers, Incorporated, Tyner, Tennessee
14. J. R. Simplot, Pocatello, Idaho
15. Valley Nitrogen, Helm, California
16. Vistron Corporation, Lima, Ohio
17. Terra Chemicals International, Inc., Sioux City, Iowa
18. National Phosphates, Taft, Louisiana
19. Triad Chemical, Donaldsonville, Louisiana
20. Mississippi Chemical Corporation, Yazoo City, Mississippi
21. Mississippi Chemical Corporation, Pascagoula, Mississippi
22. Socal, Pascagoula, Mississippi
23. Freeport Chemical Company, Convent, Louisiana
24. St. Paul Ammonia Products, St. Paul, Minnesota
25. Farmland Industries, Fort Dodge, Iowa
26. Thornton Labratory, Tampa, Florida
27. Serco Laboratory, Minneapolis, Minnesota
28. Harris Laboratories, Lincoln, Nebraska
29. Stewart Laboratory, Knoxville, Tennessee
30. James Engineering, Armonk, New York
31. Mr. A. L. West, Lakeland, Florida
32. Dr. James A. Taylor, Lakeland, Florida
33. Mr. W. A. Lutz, Weston, Connecticut
34. The Fertilizer Institute
35. The Environmental Committee, The Fertilizer Institute
36. Florida Phosphate Chemists Association
37. Davy Powergas, Inc., P.O. Box 2436, Lakeland, Florida
38. Stamicarbon N.V, Dutch State Mines, Geleen, Netherlands
39. IVO MAROVIC, Consultant, New York, New York
40. Technip, Inc., 437 Madison Avenue, New York, New York
41. Battelle Northwest, Richland, Washington
42. United States Steel Agricultural Chemicals Corporation,
Bartow, Florida.
160
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SECTION XIII
REFERENCES
A. Inorganic Fertilizer and Phosphate Mining Industries - Water
Pollution and control
prepared by Battelle Memorial Institute Richland, Washington
for the Environmental Protection Agency, Grant No. 12020FPD,
September 1971, U.S. Government Printing Office, Washington,
D.C., 20402.
B. Advanced Wastewater Treatment
by Russell L. Gulp and Gordon L. Gulp, Van Nostrand Runhold,
Environmental Engineering Series, Copyright 1971 by Litton
Educational Publishing, Inc., New York, Library of Congress,
Catalog Card Number 78-147192.
C. Ammonia Rempyal in a Physical-Chemical Wastewater
Treatment Process
by Robert A. Barnes, Peter F. Atkins, Jr. Dale A. Scherger;
Prepared for Office of Research and Monitoring, U.S.
Environmental Protection Agency, Washington, D. C., 20460,
EPA-R2-72-123, November, 1972.
D. Ammonia and Synthesis Gas
by Robert Noyes; Noyes Development Corporation, Mill Road at
Grand Avenue Park Ridge, New Jersey, 07656.
E. Industrial Pollution Control Handbook
by Herbert F. Lund; McGraw Hill Publishing Co., New York,
Library of Congress Catalog card Number 70-101164.
F. Gauging and sampling Industrial Wastewater
by Joseph G. Robasky and Donald L. Koraido Calgon
Corporation; Chemical Engineering Magazine, Vol. 80, No. 1,
January 8, 1973, Pages 111-120.
G. Environmental Protection Agency Study Report Industrial Waste
Studies Program
Group 6 Fertilizers prepared by Wellman-Powergas, Inc.;
Lakeland, Florida, 33803, for Environmental Protection
Agency, July, 1971, Contract No. 68-01-0029.
H. The Phosphate Industry in the United States
by E.G. Houston Tennessee Valley Authority, Office of
Agricultural and Chemical Development, Division of Chemical
Development, Muscle Shoals, Alabama, July, 1966.
161
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I. commercial Fertilizer Yearbook ~ 1970
Walter W. Brown Publishing Co., Inc. 75 Third Street, N.W.
Atlanta, Georgia, 30308.
J. Characteristics of the World Fertilizer Industry - Phosphatic
Fertilizers ~
by Travis Hignett, Director of Chemical Development,
Tennessee Valley Authority, Muscle Shoals, Alabama, December
1967, TVA Report No. S-422.
D- World Fertilizer Forecast 1965-1980
by Wellman-Lord, Inc. Lakeland, Florida, Copyright 1967,
Paramount Press, Inc., Jacksonville, Florida.
L. Economic Impact of Water Pollution Control Requirements on
the Fertilizer Manufacturing Industry
by Development Planning and Research Associates, Inc., P.O.
Box 727, Manhattan, Kansas, 66502. Interim Report to
Environmental Protection Agency, Contract No. 68-01-0766,
November, 1972.
M. World Nitrogen Plants 1968-1973
Chemical Products Series Report-May 1969, Stanford Research
Institute; Menlo Park, California, 9U025.
N. Phosphatic Fertilizers - Properties and Processes
by David W. Bixby, Delbert L. Rucker, Samuel L. Tisdale,
Technical Bulletin No. 8, October 1966, The Sulphur
Institute, 1725 "K" Street Northwest Washington, D.C. 20006.
O. New Developments in Fluoride Emissions From phosphate
Processing Plants
by Frank L. Cross, Jr. and Roger W. Ross JAPCA, Volume 19,
No. 1, Page 15, January, 1969.
P. The Chemical Indus-try Facts Book by Manufacturing Chemist
Association, Inc., 5th Edition 1962, 1825 Connecticut Ave.,
Washington, D.C., Library of Congress Catalog card No. 59-
15407.
Q. Water Quality Criteria
National Technical Advisory Committee, Federal Water
Pollution Control Administration, Washington, D.C., 1968.
R« Handbook of Dangerous Materials
N.I Sax, Reinhold Publishing Corp. New York, New York, 1951.
• 162
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S. Nitrates in Human Health
C. J. Mansfield, Missouri Agricultural Experiment Station,
Special Report No. 55, Pages 37-38, 1965.
T. Industrial Water Pollution control
W. W. Ekenfelder, McGraw-Hill Publishing Co., New York,
Published 1966, Library of Congress Catalog Card No.66 -
17913.
U. Phosphorus and ;Ets Compounds
John R. Van Wazer, Interscience Publishers, Inc., New York
(1961), Library of Congress Card No. 58-10100.
V. Cadmium in Rock Phosphate Ores
H.P. Nicholson, PH.D., Director Southeast Environmental
Research Laboratory (6/19/73).
W. Standard Methods for the Examination of_ Water and Waste
HaterT 13th edition, American Public Health Association
(1971).
X. Methods for Chemical Analysis of Water and Wastes, EPA,
National Environmental Research Center, Analytical Quality
Control Laboratory, Cincinnati, Ohio (1971) .
163
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Page Intentionally Blank
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SECTION XIV '
GLOSSARY
All underlined numbers within a chemical formula represent
normally subscripted numbers. For example, H^O represents water.
Physical limitations of the printing device make this system
necessary.
Aerobic
Living in the presence of oxygen.
Algae
A group of aquatic nonvascular plants with chlorophyll.
Anaerobic
Living in the absence of free oxygen.
Apatite
A natural calcium phosphate usually containing fluorine occuring
as phosphate rock. *
Biological Process
The process by which bacteria and other micro-organisms in search
of food, breakdown complex organic materials into simple, more
stable substances.
Biuret
NH2CONHCONH2 • H2O. Also referred to as allophanamide and
cabamylurea.
Boiler Slowdown
A small amount of boiler feed water wasted to remove the build up
of contaminants from the boiler.
Boiler Feed Water Make-up
Water that is acceptable for steam generation in high pressure
boilers.
Contaminated Waste Water
Effluent waste water that has been contaminated due to contact
with process water (could be cooling tower, boiler blowdown or
pond water)
165
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Cooling Water Blowdown
Small quarvti-ty of cooling water discharged from a recycling
cooling water system to remove concentrated contaminants from the
tower.
Deionized Water
Water (raw, filtered or treated) that had certain ions removed by
an ion exchange unit.
Denitrification
An anaerobic process which converts nitrate nitrogen to nitrogen
gas.
Dissolved Oxygen
Amount of free oxygen dissolved in water.
Exemplary
The term used for plants or units within plants that exhibit well
operated treatment schemes or in-plant techniques that qualify
them as best practicable control technology currently available,
best available technology economically achievable, or best
demonstrated technology. Such plants or units may belong to
another industrial category whose technology may be transferred
to the industry under study.
GTSP
Granulated triple superphosphate.
Nitrification
Conversion of nitrogenous matter into nitrate by bacteria.
Pond Water
Water used in the manufacture of phosphoric acid and related
compounds to remove heat, convey gypsum and scrub contaminants.
Prills
Small round or acicular aggregates of a material that are
artificially prepared.
Process Water
Any water which, during the manufacturing process, comes into
direct contact with any raw material, intermediate, product, by-
product, or gas or liquid that has accumulated such constituents.
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Raw Water
Water that has not been treated in any way, taken from a well, a
river, a lake, or other non-contaminated source.
ROP
Run-of-pile triple superphosphate.
Single Train Plant
A plant (especially an ammonia plant) that employs a single very
large production unit with a high degree of maintenance-free
reliability. This is in contrast to a double train plant which
employs 2 identical units run in parallel with a lesser degree of
reliability, but which has the advantage of maintaining some
production when one unit is down.
Ton
All uses of the term "ton" imply short ton equal to 2000 Ib.
Treated Water
Raw water or filtered water that has been treated to make it
suitable for plant needs (such as softening).
TSP
Triple superphosphate.
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METRIC UNITS
CONVERSION TABLE
CTl
GO
MULTIPLY (ENGLISH UNITS)
ENGLISH UNIT ABBREVIATION
acre ac
acre - feet ac ft
British Thermal BTU
Unit
British Thermal BTU/lb
Unit/pound
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 Hg
pounds Ib
million gallons/day mgd
mile mi
pound/square inch psig
(gauge)
square feet sq ft
square inches sq in
tons (short) ton
yard yd
by
CONVERSION
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
TO OBTAIN (METRIC UNITS)
ABBREVIATION METRIC UNIT
ha
cu m
kg cal
kg calAg
cu m/min
cu m/min
cu m
1
cu on
°C
m
1
I/sec
kw
cm
atm
kg
cu m/day
km
atm
sq m
sq on
kkg
m
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
kilowatts
centimeters
atmospheres
kilograms
cubic meters/day
kilometer
atmospheres
(absolute)
square meters
square centimeters
metric tons
(1000 kilograms)
meters
*Actual conversion, not a multiplier
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