WATER POLLUTION CONTROL RESEARCH SERIES
ORD 17O7ODLYO5/7O
DISPOSAL OF BRINES
PRODUCED IN RENOVATION
OF MUNICIPAL WASTEWATER
U.S. DEPARTMENT OF THE INTERIOR • FEDERAL WATER QUALITY ADMINISTRATION
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WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Reports describe the results
and progress in the control and abatement of pollution of our
Nation's waters. They provide a central source of information on
the research, development, and demonstration activities of the
Federal Water Quality Administration, Department of the Interior,
through in-house research and grants and contracts with Federal,
State, and local agencies, research institutions, and industrial
organizations.
Water Pollution Control Research Reports will be distributed to
requesters as supplies permit. Requests should be sent to the
Planning and Resources Office, Office of Research and Development,
Federal Water Quality Administration, Department of the Interior,
Washington, D. C. 20242.
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DISPOSAL OF BRINES PRODUCED IN RENOVATION
OF MUNICIPAL WASTEWATER
by
Burns and Roe, Inc.
Oradell, New Jersey 07649
for the
FEDERAL WATER QUALITY ADMINISTRATION
DEPARTMENT OF THE INTERIOR
Program #17070 DLY
Contract #14-12-492
FWQA Project Officer, Dr. J. B. Farrell
Advanced Waste Treatment Research Laboratory
Cincinnati, Ohio
May, 1970
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FWQA Review Notice
This report has been reviewed by the Federal
Water Quality Administration and approved for
publication. Approval does not signify that
the contents necessarily reflect the views
and policies of the Federal Water Quality
Administration, nor does mention of trade
names or commercial products constitute
endorsement or recommendation for use.
For sale by the Superintendent of Documents, U.S. Government Printing Ofllcc
Tor »y me P" WiUshiMton_ D.c. 20402 - Price $1.25
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ABSTRACT
Costs of ultimate disposal of brine wastes from municipal water
renovation schemes have been investigated for the sites of El Paso, Texas
Tucson, Arizona and Denver, Colorado. Based on 10 million gallons per
day, 7% fixed charge rate, and 12 mills/Kwhr power cost, estimated
costs are as follows:
Near El Paso, Texas, brine can be dumped on worthless arid land at
a cost of $.052/Kgal. It can be injected into the saline Hueco-Bolson
Basin at $0.13/Kgal. Solar evaporation in local ponds, using 30 mil
liners and a pipeline to convey residual brine 50 miles for ultimate
disposal, costs $0.18 Kgal.
Solar evaporation east of Denver, using ponds with a 30 mil liner,
would cost $0.76/Kgal. Alternately, solar evaporation east of Pueblo,
Colorado in lined ponds would cost $0.96/Kgal., including the pipeline
from Denver. Multistage flash evaporation to 10% solids would reduce
the amount of brine and the size of the solar ponds to a point where
they might be acceptable. Their combined cost, based on $0.46/mbtu
steam and steam-driven pumps is $0.54/Kgal. of brine effluent. Well
injection is unfeasible here, due to earthquakes.
At Tucson, the temporary measure of using injection wells to 3500
feet while awaiting the Southwest Water Plan would cost $0.13/Kgal. A
permanent scheme, using local solar ponds with 30 mil liners would cost
$0.18/Kgal., including costs for a residual brine pipeline to the Wil-
cox Plaza 50 miles eastward.
This report was submitted in fulfillment of Contract 14-12-492 be-
tween the Federal Water Pollution Control Administration and Burns and
Roe, Inc. , (Program #17070 DLY).
Key Words: ultimate disposal, brine wastes, municipal renovation
schemes, deep well injection, solar evaporation, brine
reduction, flash evaporation, disposal costs.
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TABLE OF CONTENTS
ABSTRACT
INTRODUCTION !
Authorization 1
Objective 1
Scope of Work •*•
Technical Approach ^
SUMMARY AND RECOMMENDATIONS 5
Summary
Recommendations
Future Study 5
GENERAL BACKGROUND 9
Salt Buildup Problem 9
Water Renovation to Remove Salts 9
Brine Disposal Means ^
DISPOSAL METHODS 15
Deep Well Injection ^
Solar Evaporation Ponds ^3
Concentration to Saturation and Pipelining 26
Multistage Flash Evaporators 31
Multistage Flash Evaporation with Ion Exchange
Pretreatment ^"
Vapor Compression and Multieffect Evaporation 51
Submerged Combustion 56
Pipeline Conveyance to Disposal Area
Other Methods 66
Impoundment and Controlled Release of Wastes 66
Hauling of Dry Salt or Concentrated Brines 70
Brine Desulfation 72
Direct Contact Oil-Water Evaporation 74
Electrodialysis With Ion-Specific Membranes 77
EL PASO, TEXAS STUDY SITE 79
TUCSON, ARIZONA STUDY SITE 89
DENVER, COLORADO STUDY SITE 97
BIBLIOGRAPHY 1°7
NOMENCLATURE 11]-
APPENDIX 113
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FIGURES
Page
1. Cost of Evaporating Water from Salines 13
2. Hueco-Bolson Basin, Deep Well Injection Design 17
3. Deep Well Disposal Surface Equipment, Flow Diagram 18
4. Deep Well Injection, Costs/Capacity 22
5. Solar Evaporation of Brine to Eventual Dryness
Costs/Capacity 27
6. Disposal Scheme 28
7, Solar Evaporation and Pipeline Conveyance,
Costs/Capacity 30
8. Multistage Flash Preconcentrator Block Diagram -
0.1 MGD Feed 42
9. Multistage Flash Preconcentrator Block Diagram -
1.0 MGD Feed 43
10. Multistage Flash Preconcentrator Block Diagram -
2.5 MGD Feed 44
11. Multistage Flash Preconcentrator Block Diagram -
10 MGD Feed 45
12. Vapor Compression Plant Flow Diagram 52
13. Vapor Compression Evaporation, Costs/Water
Evaporated 54
14. Typical Flow Diagram, Submerged Combustion
Evaporation 60
15. Submerged Combustion Evaporation, Cost/Brine
Feed Capacity 61
16. ORSANCO Water Quality Monitoring Stations on the
Ohio River (Map) 68
17. Cost Surface for Conveyance: Pipeline, Truck and
Rail ($/1000 gal.-mile) 71
18. Sulfate Removal Process, Flow Diagram 73
19. Direct Contact of Oil-Water Evaporation, Process 75
Diagram
20. Electrodialysis Stack 78
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FIGURES
Page
21. El Paso Region (Map) 80
22. Deep Well Injection Area of Hueco-Bolson Basin 83
23. Tucson Region (Map) 91
24. Schematic Representation of Water and Salt Balance for a
197-MGD Water Renovation Plant, Denver, Colorado 99
25. Denver Region (Map) 102
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TABLES
1. Summary Sheet - Comparative Costs of Brine Disposal
at Three Sites
2. Estimated Cost of Injection Well Construction 21
3. Total Cost Per Stage for a 2.5 MGD Wastewater
Desalting Plant 34
4. Summary of MSFE Computer Output 47
5. Water Analysis - Ultimate Disposal - Electrodialysis Brine 49
6. Vapor Compression Evaporator Costs 55
7. Data on Concentrating Inorganic Waste Streams for 7 to 50
Percent Solids by SCE 57
8. Unit Costs for Concentrating Inorganic Waste Streams
from 7 to 50 Percent by SCE (90% Load Factor) 58
9. ORSANCO Water Quality Monitor Stations on the Ohio River 69
10. Unit Disposal Cost by Solar Evaporation, El Paso, Texas 84
11. Pipeline Conveyance Costs in $/Kgal. 85
12. Unit Cost of Disposal by Evaporation Ponds and Pipeline
Combination, El Paso, Texas 87
13. Unit Disposal Cost by Solar Evaporation, Tucson, Arizona 93
14. Unit Cost of Disposal by Evaporation Ponds and Pipeline
Combination, Tucson, Arizona 95
15. Unit Disposal Cost by Solar Evaporation, Denver and
Pueblo, Colorado 104
16. Unit Cost of Disposal for Forced and Solar Evaporation,
Denver, Colorado 105
NOMOGRAMS
1. Optimum Performance Ratio vs. Brine Quantity, Unit Cost
of Evaporator Less Stages,FCR and Steam Cost 38
2. Partial Water Cost er \ Capital Costs vs. RP and
Steam Cost 40
3. Unit Cost of Brine Disposal by Pipeline Conveyance,
$/Kgal. x 100 Miles 64
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INTRODUCTION
AUTHORIZATION
On February 25, 1969 Burns and Roe, Inc. was authorized by the
United States Department of the Interior, Federal Water Pollution Con-
trol Administration - under Contract No. 14-12-492 - to study economical
solutions to the problem of ultimate disposal of brine wastes from ad-
vanced waste treatment processes.
Advanced waste treatment is the processing of waste waters beyond
that required for pollution control to permit beneficial reuse. A
major cost factor associated with advanced waste treatment is the dis-
posal of brines resulting from these treatment processes.
Without ultimate disposal, the pollution problems are simply trans-
ferred from one locality to another. With it, the brines are ultimately
disposed of in as nearly a non-polluting fashion as possible; for ex-
ample, to the oceans, to existing salt beds, or to underground saline
waters.
OBJECTIVE
This investigation has been undertaken for the FWPCA to determine
the cost of brine (liquid-waste) disposal facilities for several sites
in the United States.
The methods of disposal are themselves combinations of one or more
operations. The costs of these separate operations will be determined
at the several sites to be investigated. Total costs of the most eco-
nomical combined disposal schemes will be determined as a function of
brine concentration and quantity.
SCOPE OF WORK
Review the state-of-the-art for feasible methods of concentrating
and disposing of brine wastes. Process design and cost figures will be
obtained or developed for operations such as deep-well disposal, con-
centration to saturation or dryness by submerged combustion, multiple-
effect evaporation and/or solar evaporation, hauling of dry salt, pipe-
line transport, and storage pond impoundment with periodic discharge.
Determine the costs of these separate operations at three separate
locations in the United States to be established in later discussions
with officials of FWPCA. Costs are to be determined as a function of
initial brine concentration, final brine concentration and total brine
throughput. Emphasis will be placed on obtaining accurate cost figures.
Determine the total cost of disposal of brine by several of the
most promising combinations of the separate operations for which costs
have been obtained. Typical schemes may be:
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Concentration of brines to saturation followed by pipelining
to the nearest ocean or salt lake
Concentration of brines to dryness and hauling of dried salt
to nearest salt bed
Deep-well disposal with or without prior concentration
Impoundment of brine wastes with controlled disposition
during spring floods
The cost of the most promising schemes will be determined as a
function of the total amount of brine solids for which disposal is re-
quired and the concentration of the brine. The amount of brine solids
handled at each site will be computed as that from municipal wastewater
renovation plants of 1 MGD, 10 MGD and 100 MGD capacity. The initial
brine concentration for each of the sites studied will be selected as
the most promising value determined by reviewing the state-of-the-art
and by consulting with FWPCA and with vendors for water and wastewater
renovation processes currently proposed (such as electrodialysis and
reverse osmosis).
The influence of variations in brine composition on the cost of
ultimate disposal will be predicted on the basis of current knowledge
of these variations. Equipment, materials, processing and disposal
problems uncovered during this study will be reviewed. Recommendations
will be made as needed for research and development work in these areas.
TECHNICAL APPROACH
Item 1 of the Scope, in which the word "operations" is followed by
a list of possible processes to be studied, allows certain of the
processes which appear to be least feasible to be given merely cursory
treatment, while others that were not included in the original list can
be covered in some detail. Thus, storage pond impoundment with periodic
discharge, barium-zeolite desulfatipn, and multistage flash evaporation
using an immiscible heat exchange liquid, have not been covered in great
detail, since they do not appear to be among the "feasible methods"
applicable to concentrating and disposing of brine wastes under the
ground rules of this study.
On the other hand, additional concentration methods have been added
so as to expand the list of item 1. Electrodialysis with ion-specific
membranes to allow concentration without scaling, and submerged com-
bustion were included among the alternative methods studied. In addition,
the use of vapor-compression evaporators to concentrate all the way to
saturation has been analyzed, and parametric unit cost and operating
cost equations have been developed.
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Item 3 of the Scope lists typical disposal schemes that "may be"
considered. Because "disposal during spring floods" does not appear
applicable to the selected sites, it was not considered under Item 3.
Additional work under this item includes examination of pretreatment
and post-treatment of AWT effluents, to render the effluent suitable
for standard quaternary treatment. Electrodialysis, Reverse-Osmosis,
and Ion Exchange were the wastewater renovation methods chosen.
Particular attention under Item 3 has been devoted to concentration by
conventional multistage flash evaporation as the best alternative to
solar evaporation up to 10% total dissolved solids (tds).
A final selection of sites for the brine disposal study has been
made on the following basis:
1. El Paso, Texas; population 300,000. Needs water. Location,
hot, dry, on Rio Grande River with highly variable flow, used
for irrigation downstream.
2. Tucson, Arizona; population 250,000. Needs water. Location,
hot dry, inland. Probably ideal site for solar evaporation
ponds. Salt pollution of Gila River and tributaries is serious,
3. Denver, Colorado; population 520,000. Seeks maximum water re-
use to meet anticipated growth. Location, cool, dry, inland
on South Platte River. Deep well disposal of waste brines not
feasible due to earthquakes. Suggests creation of a salt
water recreational lake as a possible disposal method.
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SUMMARY AND RECOMMENDATIONS
SUMMARY
The following Summary Sheet (Table 1) lists disposal costs in $/Kgal,
of brine for 3 sizes of disposal plants based on 5% and 10% annual fixed
charge rates at the 3 selected sites. For additional information on
these methods, see the individual sections of the report.
RECOMMENDATIONS
El Paso. Texas
A general solution for the water problems of the region must await
implementation of the Texas Water Plan, whereby storage basins now being
exhausted can be replenished and stabilized with Mississippi River water.
As the best temporary expedient until then for the City of El Paso, in-
jection of brine into the East end of the Hueco Bolson Basin at 3500 ft.
is recommended.
Denver, Colorado
Water here is of pristine quality, and a multiple reuse scheme of
197 mgd is considered only from a hypothetical standpoint. This reuse
scheme, which would satisfy city needs beyond 1985 with no additional
water withdrawal from the Colorado River, would employ multistage flash
preconcentration to 10% solids, with 0.7 mgd of evaporator blowdown
going to solar ponds East of the city for ultimate disposal.
Tucson, Arizona
The need for a reuse scheme here will require the exportation by
1985 of all salt entering the Tucson Basin in amounts equal to the salt
inflow due to importing water from the Parker Dam on the Colorado River.
The most economical scheme will be to provide local solar evaporation
ponds, with the blowdown from these ponds being pipelined 50 miles
East to the closed and already contaminated Wilcox Playa Basin.
FUTURE STUDY
Means whereby the tds removal step of an advanced waste treatment
plant can be made to concentrate the brine as well as purify the sec-
ondary sewage effluent should be investigated. These are outside the
scope of the present study. Such means include:
Selective electrodialysis whereby hardness ions, necessary for non-
aggressive product water, are left in the dialyzate, while monovalent
cations, such as NH4 +, Na + and K+ are concentrated to saturation for
ultimate disposal. For typical municipal effluents, combinations of
pretreatments and post-treatments and ion specific membranes would have
to be investigated.
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Multistage flash evaporators optimized for concentrating secondary
sewage effluent to 10% solids, with lime softening and ion exchange as
a pretreatment, and carbon adsorption as a post-treatment. Brine carry-
over, ammonia carryover, condenser leakage, biological contamination and
odor would be problems that would have to be solved by suitable post-treat-
ments to render the product water fit for reuse.
Combinations of the above processes with reverse osmosis, using in
situ casting and also the new high-efficiency cellulose-acetate-butyrate
membranes. It would seem possible to tailor the tds removal and con-
centrating step to the requirements of any given municipality.
Special handling of cooling tower blowdowns and other unusual
industrial wastes that presently wind up in municipal effluent streams.
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TABLE 1
SUMMARY SHEET
COMPARATIVE COSTS OF BRINE DISPOSAL AT THREE SITES
Brine Quantity (mgd) 0.1
Fixed Charge Rate (%)
EL PASO
Dumping at White Sands
Deep Well in Hueco Basin
DENVER
Lined ponds (30 mils) at Denver
Lined ponds (10 mils) at Denver
Pipelining to Pueblo plus (30 mils) ponding at Pueblo
Pipelining to Pueblo plus (10 mils) ponding at Pueblo
Forced evaporation plus (30 mils) ponds
Forced evaporation plus (10 mils) ponds
Deep Well
1.0
10
10.0
Costs
0.47
0.28
1.26
0.678
4.18
3.71
1.07
1.02
($/Kgal.)
0.19
0.16
1.125
0.54
2.16
1.7
0.84
0.78
0.07
0.16
1.08
0.498
1.35
0.88
0.69
0.63
Not Possible
TUCSON
Lined ponds (30 mils) plus pipelining of
brine concentrate 1.37
Lined ponds (10 mils) plus pipelining of
brine concentrate 1.20
Deep Well 0.28
0.52 0.25
0.35 0.20
0.16 0.16
0.1
1.0
5
10.0
Costs ($/Kgal.)
0.27
0.21
0.63
0.34
2.33
2.09
0.75
0.72
0.10
0.12
0.56
0.27
1.15
0.91
0.61
0.58
0.04
0.11
0.54
0.25
0.69
0.46
0.51
0.48
Not Possible
0.70
0.61
0.21
0.27 0.14
0.18
0.12
0.10
0.11
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GENERAL BACKGROUND
SALT BUILDUP PROBLEM
Many areas in the western portion of the United States are charac-
terized by arid or semi-arid conditions, with resulting shortages of
water supply. As a consequence, water is too valuable a commodity to be
used once and then thrown away. It must be reused. The reuse may be
applied to agricultural, municipal, or industrial requirements, depend-
ing on the ease of treatment. In that area of the country, reuse has
primarily been applied to irrigation for agricultural purposes. Since
with such reuse, there is insufficient water to provide suitable irriga-
tion return flows, or net annual runoffs from the irrigated areas, soluble
soil solids are continually leached to the surface and concentrated there
along with the solids of the irrigation water. The net consequence of
this procedure is the destruction of the irrigated land, usually by
buildup of sodium salts at the surface.
In a typical United States community, reuse of the municipal effluent
can be expected to add 350 mg/1 total dissolved solids (tds) to the water
on each cycle. If the average water supply contains over 150 ing/1 tds,
it follows that a single reuse will raise the tds to over 500 mg/1, the
potability limit recommended by the U.S. Public Health Service, and hence
render the water unfit for municipal reuse. The problem is made more
acute by the nature of industrial pollutants, accounting for about
150 mg/1 of the 350 mg/1 added per use, and frequently containing toxic
as well as refractory substances. Pesticide residues, photographic
wastes, chlorinated phenols, hexavalent chromium, copper and boron com-
pounds are among such objectionable substances and are not removable by
conventional primary and secondary waste treatments. These and many other
refractory substances occur in the municipal wastes from heavily in-
dustrialized areas and must be removed before the water can be considered
fit for reuse.
WATER RENOVATION TO REMOVE SALTS
The above problems due to salt buildup can usually be solved by one
of the modern desalination methods operating on the municipal waste water.
For water sources below 2,000 mg/1, three processes show good potential
for desalination: ion-exchange, reverse osmosis, and electrodialysis.
Ion exchange in combination with chemical processes has the dual potential
of producing potable water while at the same time concentrating the solids
up to 8% by weight. It has the disadvantage of contributing solids to the
salt disposal problem. Reverse osmosis has the advantages of being a non-
selective, highly dependable, low-operating-cost process. It has the dis-
advantages of discharging large volumes of low concentration brine, from
which the pump work must be extracted by turbines for good power economy.
Electrodialysis has the advantages of being fully commercial, having good
power economy, and also having a good concentrating factor for the waste
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brine. Its main disadvantages are membrane poisoning, polarization, an
exfoliation of the membranes by scale when improperly operated. In com
mon with distillation and freezing processes, the above three P™ce;*s*8
produce large volumes of waste brine, containing all of the contaminants
removed in rendering the municipal effluent suitable for multiple reuse.
Determination of the costs for ultimate disposal of these waste brines
is the main objective of this study.
BRINE DISPOSAL MEANS
The amount of waste brine blowdown in a desalting operation is con-
siderable. For example:
- A 100-mgd water renovation plant produces a blowdown of 10 mgd of
brine of about 7000 mg/1 concentration. Disposal of this quantity
of brine is a problem of no small magnitude.
- If concentrated to 30 percent solids, the volume of brine waste is
still considerable - 180,000 gallons per day - and it would still
contain all of the harmful salts.
3
- Even as dry salt with a bulk density of about 125 Ib/ft , the daily
production would occupy almost 5000 cubic feet.
Koenig has considered the following brine disposal alternatives
(Koenig, '58, DePuy, '69):
Disposal may be accomplished by underground injection, land dump-
ing on unusable and worthless areas, sea discharge via pipeline, stream
discharge, or abandonment at the operation site. An intermediate process
of evaporation to saturation or dryness, and conveyance operations may
also be used in combination with the final disposal operations.
Injection disposal involves a comprehensive geologic investigation
and field testing of the disposal zone and reservoir areas to determine
that safe, effective underground disposal is possible, that the injected
brine is compatible with fluids in the reservoir, that it cannot encroach
on or pollute underground fresh water, that future natural resources will
not be contaminated, and that the risk of causing unforeseen phenomena,
such as earthquakes and eruptions, is minimized.
Land dumping is feasible in certain western locations, such as re-
mote deserts and playas having no net annual runoff and no useful aquifers
beneath, or occupying closed basins where the land has already been
rendered useless for agricultural or other human purposes.
Conveyance via pipeline to the sea or to a salt lake basin is
feasible for those inland sites fortunate enough to be located within
150 miles of such an ultimate disposal sump. Outfalls would have to be
located sufficiently offshore out into an ocean current, so that natural
mixing and dispersion could be relied upon to prevent ecological damage.
10
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Stream discharge is generally not feasible in the United States,
and because of the local pollution problem that it introduces, it does
not really qualify as an ultimate disposal method. By impoundment of
brines with controlled release during floods, however, the pollution
problem can be more or less equalized throughout the year and the
periods during which legal limits on pollution are exceeded can be
minimized.
Abandonment at the site of evaporation is feasible in the far west,
where the annual gross evaporation rate greatly exceeds the annual rain-
fall. The salt residues in a lined evaporation pond remain in the pond
and are left to build up continuously over the lifetime of the desalina-
tion plant. Alternately, lined solar evaporation ponds may be used to
preconcentrate to saturation near the desalination facility, and the
concentrated brine from this can be dumped on useless land in a remote
area (DePuy, '69).
Preconcentration techniques, whereby the brine is concentrated to
saturation or dryness before conveyance to the ultimate disposal site
include both chemical and physical methods. The successful application
of one or more of these methods in geographically feasible areas will
depend entirely upon the economics of the local situation. Lime coagu-
lation, precipitation, and ion exchange, are frequently inexpensive
chemical methods. Solar evaporation, multistage flash evaporators, and
vertical tube evaporators are effective preconcentrating devices for
concentrating waste brines to the point where they can be most eco-
nomically disposed of as a liquid, a thick slurry, or a solid. For
disposal as a liquid, part of the wastes is evaporated, and the remain-
ing part is pipelined away to the nearest non-leaching sump or ocean.
For disposal as a slurry, the initial waste brine is concentrated to
the point at which scaling or crystallization occurs. For disposal as
a solid, the initial liquid is concentrated to saturation and then dried
to solids in solar evaporation ponds.
While the costs of solar evaporation in arid areas are always fav-
orable, the costs for forced evaporation by mechanical means can be
expected to be high, particularly when the added costs for crystallizing
and for drying to solids are considered. There are several broad cate-
gories of equipment that have been proved commercially:
To concentrate up to but not exceeding 10% solids, use of the con-
ventional single-effect multistage flash-evaporator that has already
been developed for seawater conversion results in a low cost per
thousand gallons of water evaporated. Use of these units on waste-
water instead of seawater, however, requires a reoptimization to
determine minimum costs since the previous results for seawater are
not directly applicable.
For concentrations from 10% to 40% total dissolved solids, evapora-
tion would have to be carried out by conventional triple, quadruple
effect equipment, or by vapor compression. To prevent scaling of
the heat exchange surfaces pretreatment or cleaning methods would
have to be employed, and concentrations would have to be kept below
saturation.
11
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For concentrations from 40% to dryness, evaporation would have to
be carried out by special drying equipment such as submerged com-
bustion evaporators which are non-scaling, flash dryers, or crystal-
lizing evaporators. Because of their low thermal efficiency and
mechanical complications, these units are generally very costly to
operate.
Previous work on concentration by conventional evaporators has been
done by Koenig and others (Koenig, '63). Koenig has presented his costs
in Figure 1 of the reference cited, which is reproduced here for con-
venience (Figure 1). A utilization factor of 0.9 has been used, defined
as the ratio of average production to the design capability.
In Figure 1 the units described have not been optimized for design
and performance applicable to wastewater renovation. It should also be
noted that economic factors today are different from the economic factors
prevailing in 1962. However, the general approach is valid, and the work
serves as a good background for accurate costing involving the actual engi-
neering criteria and ground rules used in the current study.
A complete bibliography of the general background of disposal of
brine effluents recently issued by the OSW (DePuy, '69) is included in
the Bibliography of this report. See also the Appendix.
12
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I ADVANCED-TREATMENT WASTE
100
QC
o
Q_
§
o
ID
O)
8
1.0
.10
FLASH DRYER t NICHOLS HERRESHOFF FURNACE
30% -100% (WATER NOT RECOVERED)
ELECTRIC
LABORATORY STILLS
STEAM AT 55$'1,000 LB
SINGLE EFFECT EVAPORATED
*- 30%
SALINE WATER
CONVERSION
3.5%-^ca 10%
VC, FORCED
RECIRCULATION
VAPOR'
COMPRESSION
TRIPLE-EFFECT EVAPORATOR
10% -30%
\ \ 52-AND 42-STAGE FLASH
» V *s
7-STAGEFLASH-LTV
10-EFFECTLTV-VC'
(STEEL)
i i i nun i 11 nun i i i nun i iiiiim i mum i i mini i
11 in
100
1M
1m
10M 100M
WATER EVAPORATED, gpd
FIGURE 1. COST OF EVAPORATING WATER FROM SALINES
10m
EVAPORATOR CONSTRUCTION MATERIAL:
OPERATION:
ELECTRIC POWER:
COOLING WATER:
FUEL:
STEAM:
DIRECT LABOR:
STAINLESS STEEL
330 DAYS PER YEAR
UNDER 100,000 kw, 7 MILLS/KWH
40°F RISE
25«
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DISPOSAL METHODS
The following paragraphs describe the important factors considered
in the study of each of the processes. Rather than using a set of fixed
economic conditions, as previous studies have done, the present study
has developed, for each method of disposal, a set of parametric equations,
which allow considerable variation in the economic parameters. Fixed
charge rates over different lifetimes and for both public and private
utilities, and electric power rates for large and small installations
and for different parts of the country, have been considered. A range
of steam costs applicable to all types of fuel has been developed, as
well as capital costs for different materials of construction, and esca-
lation factors for future installations. At the end of this report is
a nomenclature, listing all of the symbols used in the mathematical
developments.
DEEP WELL INJECTION
Abstract
The required pump pressure depends primarily upon the porosity and
permeability of the injection strata and not upon the pipe size of the
well. Therefore, the pumping cost and the capital cost are primarily
dependent upon capacity and well depth, and not upon optimization param-
eters. Thus, well injection unit costs have been developed as functions
of capacity and well depth, based upon practical considerations, rather
than upon an optimization. Different assumed well-head pressures result
in different costs. Unit costs for well injection have been calculated
for a grid of economic factors, based upon fixed charge rates and elec-
tric energy costs. Necessary parametric equations have been developed.
Introduction
Injection disposal of waste brine involves comprehensive geologic
investigation and field testing of the disposal zones and reservoir areas
to determine that safe, effective underground disposal is possible, that
the injected brine can be physically and chemically treated so as to be
compatible with fluids in the reservoir, that there is no danger of pol-
lution of or encroachment on underground fresh water supplies, that future
natural resources will not be compromised by injection and that risks of
unforeseen difficulties, such as earthquakes and eruptions are minimized.
Based upon the geological information available for the three sites
of this study, injection wells cannot be used at all in the Denver area
because of the earthquake hazard. At Tucson, Arizona, however, and also
at El Paso, Texas, suitable injection strata are found at about 3500 feet
depth. At both these locations, water is being taken from the reservoirs
at a faster rate than recharge occurs. As a consequence, the water table
15
-------
is being lowered in both areas. Statewide water plans call for ^
tion of fresh supplies before this decade ends, which will at least partially
alleviate the shortage. It seems possible in the interim to conserve fresh
water supplies by wastewater renovation techniques employing desalination
and recharge. This move would tend to stabilize the water tables to some
degree. Furthermore, if the waste brine from the desalination plant is in-
jected during the interim into saline strata underlying the fresh water
supplies, the result would be to displace the existing fresh water upward
and to raise the water tables. This practice could be continued up until
the time that sufficient imported fresh water supplies become available for
complete recharge of the reservoirs. Then another method for disposal of
the brine would have to be found.
Before injection into the strata, the waste brine should be treated
physically and chemically to render it compatible with fluids in the res-
ervoir. Typical treatments would involve desulfation of brines injected
into formations containing Ba++ and Sr++, deaeration of brines injected
into formations containing Fe++, and softening of brines injected into
carbonate formations.
Conceptual Design of the Injection System
A drawing of the injection well is shown in Figure 2, for a 200,000
gpd well capacity. A 4-1/2" diameter injection tube is carried inside
a 7" inside diameter casing long string to the 3500 foot level, and is
sealed with well cement to form a pressurized annulus around the injec-
tion long string. Any change of pressure in the annulus is indicated
by a pressure gauge, and warns against leakage. This serves to protect
the intermediate fresh water bearing strata from contamination with brine.
The well hole communicates directly with the injection long string and
extends to a suitable depth beneath it to allow the required flow of brine.
The overall concept is that of a well field supplied by treated
waste brine from an inland wastewater renovation facility. Figure 3 shows
a typical arrangement. From the desalination facility, the waste brine
flows first into a stabilizing pond. Here simple treatments, like aging
and pH adjustments are employed to render the brine compatible with fluid
already in the reservoir. Stabilized brine from the pond is transferred
by means of a transfer pump to the injection well area, which, depending
on the local geology may be either adjacent to or remote from the desali-
nation facility. The brine is pressurized to the necessary well-head
pressure by suitable injection pumps. Following these, guard filters
are usually provided to remove suspended solids that otherwise could
plug the permeable injection strata. From the guard filters, the brine
flows into the distribution headers of the well field.
Deep Well Injection Pressure Relationships and Calculations
The operating well head pressure is the vector sum of the bottom
hole injection pressure, the pressure due to the height of the iniected
brine column, and the pressure drop due to pipe friction. The bottom
hole injection pressure is the sum of the reservoir pressure and thp
bottom hole driving pressure or pressure drop due to formation friction
Generally, the operating well head pressure, or surface rictlon>
sure, is lifted to 0.5 psi per foot of depth to the
16
-------
LONG STRING SURFACE PIPE ANNULUS
PRESSURE GAUGE
100 FT.
1400 FT. &
1500 FT.
TUBING PRESSURE GAUGE, READS
3500 FT.
TUBING LONG STRING ANNULUS PRESSURE GAUGE
CONDUCTOR PIPE
•CEMENT
•10-3/4"
•SURFACE PIPE
TOP OF CEMENT
4-1/2" INJECTION TUBE
CEMENT
7" CASING LONG STRING
-TUBING PACKING
OPEN HOLE
FIGURE 2. HUECO-BOLSON BASIN, DEEP WELL INJECTION DESIGN
17
-------
FROM
DESALINATION
PLANT
TRANSFER
PUMP
oo
LINED STABILIZING
POND
INJECTION
PUMPS
GUARD
FILTER
WELL
FIGURES. DEEP WELL DISPOSAL SURFACE EQUIPMENT FLOW DIAGRAM
-------
Thus, for a 3500 foot well depth, the maximum well-head pressure is
limited to 1750 psi. This limitation is based on the consideration that
the bottom hole injection pressure plus the hydrostatic head of the in-
jected fluid should not exceed the fracture pressure.
Both at Tucson and El Paso the permeability of the strata at 3500
feet is sufficient to allow introducing the brine at relatively low well-
head pressures. At some places, in fact, gravity alone suffices for in-
jection at this depth, so that a near zero well-head pressure can be
employed. This condition cannot be expected to last over the lifetime
of the well, however, and so in this study we have assumed that a back-
pressure exists at the well bottom, which including the injection driving
pressure is equivalent to a fluid in the stratum with a specific gravity
of 1.116 and a head of 3500 feet.
Therefore, for injecting 700 mg/1 brine with a specific gravity
of 1.04 at a 3500 foot depth, the well-head pressure exclusive of pipe
friction would be:
P° = 3500 (.4331) (1.116-1.04) psig
P° = 169.75 psig
Assuming a 4-1/2" O.D. injection tube for a 200,000 gpd well,
and using the Hazen and Williams nomogram (p. 386 Ch.E. Handbook 3rd Ed.) the
pipe friction is:
Pf = (2.2 ft/100 ft) (35/2.303) = 33.4 psig
Therefore the total well head pressure required is:
Pw= P° + Pf - 203.1 psig
For a 100,000 gpd well with a 3-1/2" O.D. tubing the same well-head
pressure is required.
Deep-Well Injection Cost
The cost of brine disposal by deep well injection is the sum of the
following components: cost of wells and surface equipments; cost of well
field; cost of operating, labor and maintenance and the cost of pipeline
conveyance. However, the pipeline cost can be found in the pipeline con-
veyance cost section of this report, and is not included in the following
well injection cost summaries.
19
-------
Injection Wells_and Surface Equipment Cost
For a 3500-foot deep well and a design capacity of 0.2 mgd at an
operating pressure of 204 psig using a 4-1/2" O.D. injection string,
the estimated cost is $66,900. An 0.1 mgd capacity well using a 3-1/2"
O.D. injection string, is estimated to cost $63,380. (See Table 2.)
An additional cost is due to the pump and valves. With a pump effi-
ciency of 0.85 and a motor efficiency of 0.93, this amounts to $8500Q,
where Q is mgd well capacity. Since an 0.1 mgd well costs almost as
much as an 0.2 mgd well, the unit well cost for the odd gallonage is
almost twice that of even. Expressing the capacity of the entire in-
jection field by Q leads to two equations depending on whether the field
capacity in 0.1 mgd is odd or even.
Injection wells and surface equipment cost, exclusive of the well
field distribution piping, is as follows:
(la) $ Well Cost = 343000Q (all wells are 0.2 mgd each)
(Ib) $ Well Cost = 343000Q + 29930 (one well is 0.1 mgd)
General Equation for Well Field Costs (SW Res Inst. '66)
Refer to the appendix for layouts of different well fields from
0.1 mgd to 10 mgd capacity. The capital costs for well fields are
given by two equations. These are based on multiples of the 0.2 mgd
well, which is the maximum capacity for a single well in the well field:
(2a) For 0.1 to 0.9 mgd
$ Well field piping cost = (19303) (HxP)"1'2 (1.6558Q2+5.06Q-0-708)
(2b) For 1.0 to 10 mgd
$ Well field piping cost = (19303)(HxP)~1/2(0.382Q2+8.9612Q-3.4773)
General Equation for Operating Cost, excluding Capital Recovery
$/Kgal. = .00777/Q + .00187Z + .0359 - .00048Q
General Equation for the Total Brine Disposal Cost
$/Kgal. = 2.74(10)~6(FCR) £ $Capital Cost/Q
+ .00777/Q + .00187Z -t- .0359 - .00048Q
Conclusions and Summary
The following graph (Figure 4) shows total brine disposal costs cal-
culated from this equation for a 3500 foot deep well with operating
pressure of 204 psig at various well field sizes and fixed charge rates
NOTE:
Capital costs are determined from equations (la,b) and 2a,b).
20
-------
TABLE 2
ESTIMATED COST OF INJECTION WELL CONSTRUCTION
1. Drilling to 3100 feet $13,400
2. Contractor day work 9,000
3. Tubular goods
a. 100 ft 16-inch conduction pipe 1,500
b. 1400 ft. 10-3/4 inch surface pipe 5,600
c. 3500 ft 7-inch long string 8,420
d. 3500 ft 4-1/2 inch injection pipe with PVC lining 7,580
e. Well head and packer 4,000
4. Well services
a. Cementing and associated equipment 4,000
b. Wire line logging and perforating 2,500
c. Formation testing, core analysis and testing 2,500
d. Acidizing, mud and chemicals 3,400
5. Miscellaneous
a. Tubing rentals 1,000
b. Engineering and geological service 1,000
c. Location work, trucking, travel, etc. 3.000
Total Cost for one 0.2 mgd well $66,900
Similarly, for one mgd well, the cost for a 3500 ft and
3-1/2 in./O.D. injection pipe with PVC lining is $4,060 -
Thus, Total Cost for one 0.1 mgd well is $63,380
Reference (Dow Chen. '69)
21
-------
1.
9
8
Ill
—5
3
a.
UJ
tu
Q
to
8
FCR= 5%
9
8
1
Q
LLJ
Z
CC
m
z
0.01
78 9 0.1
4 5 678910
BRINE DISPOSAL CAPACITY, MGD
FIGURE 4. DEEP WELL INJECTION
7 8 9 10
-------
SOLAR EVAPORATION PONDS
Introduction
Solar ponds are feasible only where annual evaporation exceeds the
annual rainfall by over 20", as it does in the far West. Practical con-
siderations govern the size and costs of the solar ponds. The costs are
functions of the concentrating factor, capacity and net annual evaporation
rate. Three sets of costs have been developed: (1) a cost for concentra-
tion to near saturation for ultimate disposal; (2) a cost for evaporation
to near dryness for abandonment at the evaporation site, and (3) a cost
for preconcentrating to saturation plus pipelining the residue away to
the abandonment site, for which a computer program has been developed.
In many arid areas it is possible to evaporate brines to dryness
in properly lined solar evaporation ponds. The general cost equations
presented in this section have been developed upon the basic assumption
that the evaporation pond would be located at the desalination plant
without a pipeline between the pond and the plant.
Solar evaporation pond costs include the original cost of the land,
the cost of stripping the land and providing dike material and fill and
the cost of lining, which is the major cost in this process. Each of
these cost components is described briefly below.
Calculations of Size and Cost
Total Area of Land; In order to accommodate the width of the dike,
the total area of land required is slightly greater (about 3% to 5%)
than the required waste brine surface area. Land cost varies from $50
to $500 per acre. A $250 per acre cost has been used as the standard
land cost in this study.
The waste brine surface area is dependent upon the annual net evapora-
tion rate and the waste brine input rate:
AT7 1.344 x 10 4 Q
AE = — *• in acres.
rjjx
A safety factor of 24% is added to allow for the reduced evaporability
of salt water and the area occupied by dikes, therefore, the total land
requirement becomes:
T = 1.24 x AE, acres
Cost of land is CLND x T
a
Use of Ta area will result in a saturated brine over the lifetime of
the wastewater renovation facility, and a concentration to dryness after
abandonment.
23
-------
Dike Material; The pond is designed to accommodate the waste
brine precipitate as a solid for a period of 30 years. A 3-1/2'
basic pond depth is assumed to allow for heavy rainfall years. It is
assumed that this pond would be square and the dike would have a four-
foot crest with a 2:1 slope on the toe and a 3:1 slope on the heel.
The cost of the dike is assumed to be $1.00 per cubic yard including
equipment, labor and material. The volume of dike material depends
upon the total dike height, the total length of the dike and the thick-
ness of the dike material.
Total dike height depends upon summing the following:
Basic pond depth: 3.5 (ft/yr)
Precipitate depth (ft) :
„ „ ,ft precipN ER ,ftevap, 0 - . - , -.
Pd = Pt ( ft evap > X 12 ( yr > X P°nd Llfe (years)
A 3.0 ft surge capacity depth, freeboard which would be main-
tained to accommodate the summer to winter evaporation rate
variation.
Freeboard for waves. The wave height can be found by the use
of the Stevenson's formula.
HW = 1.5 vj F - -^F -t- 2.5
However, to simplify the calculation, we assumed an average value
of 3.0 ft. Here F, the evaporation pond "Fetch" is taken equal
to the pond length.
Liner Cover. A one-foot soil cover would be placed on the
liner for protection from damage.
Hence: Summing these for a 30 year pond life:
HD = — xERxP +10.5
HD = 10.5 + ER (2.5 P )
But, for brine concentration of 7000 mg/1, ER (2.5 P ) = 0.5' (OSW '66!
Thus, HD = 11.0 ft.
24
-------
Total length of the dike is L = 4 x ^ 4840 x AE, yards
Dike Volume
VD = (L x HD/9) (4 + 2.5 x HD), yd3
Dike cost will be: $1.00 x V
Lining: The area of liner is the total length of the dike multi-
plied by the total pond height plus the total base area. In order to
simplify the calculation, the lining area is assumed to be approximately
equal to the total land area:
ALNR = 43,560 x T ft2
Cost of lining is as follows:
30 mils (PVC) lining is $0.132/ft2 based on 60C/lb
Liner cost = CLNR x ALNR
Volume of Fill to Cover Liner: Cost of one foot of soil to cover
liner is assumed to be $0.40 per cubic yard, including equipment, labor
and material. Total volume of fill will then be:
w ALNR .3
vf - -IT • yd
Cost of liner cover is: $0.40 x V
Stripping of Land: Cost of stripping land is assumed to be $100
per acre. The cost will then be $100 x T .
Si
The total cost for a solar evaporation pond is:
CE = Land cost 4- liner cost + stripping land cost + liner
cover cost + dike cost
CE = CLND x T + CLNR x ALNR + 100 x T + 0.4 x V,. + 1.00 x V_
a a f D
Conclusions and Summary
Substituting all intermediate relations for CE, the unit cost $/Kgal.
of disposal can be expressed in the form:
CE = B. + Bc x
u 4 5
25
-------
where
8
B = 2.74 x 10"6 x ^8~ (1.667 x 104 x CLND + 7.26 x 108 x CLNR
4 t-R
+ 1.242 x 107)
B = 2.74 x 10 x
(1.242 x 106)
Similarly for unlined ponds the unit disposal cost in $/Kgal. of brine is:
2.74 (10)"6 x FCR |^ (1.667 (10)4 x CLND + 1.667 (10)6)
(1.039 (10)6)
Q-ER
The following graph (Figure 5) shows costs of disposal by solar evapora-
tion as a function of fixed charge rate and capacity in mgd at a site
where the net annual evaporation rate is 90". Costs for other conditions
can be obtained by use of the foregoing equation.
CONCENTRATION TO SATURATION AND PIPELINING
Introduction
In considering ultimate waste disposal costs, not only must each
different method be evaluated, but combinations of methods must be studied.
The scope of this report specifically requires investigation of the most
promising combinations of methods.
The purpose of this section is to investigate a solar pond in com-
bination with a pipeline. The objective is to reduce the volume to be
disposed of by means of the solar pond and to pipeline the concentrated
brine to a site where the ultimate disposal will take place (a salt lake
or injection well, for example).
The cost to be evaluated and minimized is the total cost in $/Kgal.
for the disposal of the brine. This cost is the sum of the costs of con-
centrating the brine in a solar pond (to reduce the volume) and convey-
ance of the concentrated brine to the battery limits shown in the figure
below.
Evaluation
Q mgd per day of waste, with a TDS concentration of S, are fed
into a solar pond from the treatment facility as shown in Figure 6 In
the pond the volume is reduced to Qp, and the concentration is increased
to Sp. From here Qp is then transported to the battery limits via a
pipeline.
26
-------
1.0
9
S
7
6
5
oc
2
cc
5
S
> (T.1
00 9
h
Q
LU
z
cc
m
.
01
FCR = 10%
FCR= 5%
FCR=
CLND=$250/ACRE
ER - 90 IN/YR
30 MILS LINER —
10 MILS LINER —
I I I
78901
2 345678 1.0 2
BRINE DISPOSAL CAPACITY, MGD
FIGURE 5. SOLAR EVAPORATION OF BRINE TO EVENTUAL DRYNESS
7 8 9 10
-------
Treatment
Facility
Q,
Q , s
p P
FIGURE 6 DISPOSAL SCHEME
Mathematical Formulation!
S
Let: -^ = S = Concentration ratio
j IT
s i
Therefore, flow in pipeline = Q = Q x — = -g— x Q
P P r
amount evaporated =Q = Q - Q = 0- - «
Total cost of disposal: CT = CP + CE
u u u
The partial unit cost $/Kgal. for pipelining £ miles can be shown
to be:
Here
A xA3+A2
(A3)
5/6 29
5/6'29
10 X
1.447 x A x FCR'
= 5.628 x 10~4 x FCR1 x B* + 2.683 x 10~3 x Z
- (1.508
0.719
The partial cost $/Kgal for evaporation ponds sized for Q can be
shown to be e
n 1/2
28
-------
Replacing Qp and Qe, by Q and S, we get the total cost of disposal at H
miles, $/Kgal.
.001 x B
CT =
$/Kgal.
- Q-385 Sr
Conclusions and Summary
The computer program in the Appendix reveals that:
The cost of disposal for the combined solar pond and pipeline
method can be compared with others and the most economical disposal
method can be chosen. At different sites (different economic conditions),
different methods turn out to be the most economical. Even at the same
site the method chosen depends on capacity. For fixed economic condi-
tions , as the capacity increases preconcentration costs must decrease
in order to get a cheaper cost for the combined method than for pipe-
lining alone. Therefore, there exists a capacity above which pipelining
alone with no preconcentrating should be used. Also at some sites evap-
oration may always be cheaper than pipelining. In such cases, abandon-
ment in lined ponds at the evaporation site should be considered.
In this study we assumed that the concentrated brine was dumped
on useless land. Obviously any added cost for dumping the brine will
affect the optimization.
Costs of brine disposal $/Kgal. at 50 miles for a 90" ER, and 12
mills power cost are shown on the following graph (Figure 7). Other costs
can be obtained by direct substitution into the above equation, preferably
using a computer.
29
-------
10
9
8
7
s,
8
Q.
Q
z
o
< 9
uj 8
5 7
co 6
52 3
Q
LU
ir.
CO
0.1
7 8 9 0.1
1 I
POWER COST 12 MILLS/KWHR 30 MILS LINER
CLND = S250/ACRE 10 MILS LINER
ER =90 IN/YR.
PIPELINE LENGTH = 50 MILES
FCR= 5%
FCR = 5%
3 456789 1.0 2 3
BRINE DISPOSAL CAPACITY (MGD)
FIGURE 7. SOLAR EVAPORATION AND PIPELINE CONVEYANCE
5 6 7 8 9 10
-------
MULTISTAGE FLASH EVAPORATORS
Abstract
Optimum geometries for multistage flash evaporators have been de-
veloped based on the minimum capital investment necessary for the desired
production rate at the optimum performance ratio. A nomogram has been
developed which shows the optimum number of stages and performance
ratio as a function of the plant size, the annual fixed charge rate,
the electrical power cost, and the steam cost. Unit costs and capital
costs for preconcentration by evaporation for ultimate disposal have
been shown on a second nomogram based upon annual fixed charge rates,
unit steam costs, plant size, mgd evaporated, and optimum performance
ratios. Costs are expressed per 1,000 gallons per day evaporated.
Introduction
Recent work in the art of desalination has progressed to the point
where an accurate economic assessment of the costs incurred for pro-
ducing fresh water from brackish water can be made. Conversely, the
cost of concentrating brackish water can be accurately determined.
Consider a brackish stream entering a black box, with two exit streams.
One effluent stream is concentrated brine, and the other is pure water.
The cost of operating the black box (evaporator) includes three basic
costs:
Capital cost of equipment
Cost of fuel
Other operating costs
These three cost parameters determine the cost of separating the influent
brine stream into the two effluent streams. It now becomes a matter of
accounting procedure to determine the cost of each effluent stream. For
example, assume the concentrated brine is the primary product, and the
total cost of separation is $0.50/Kgal. If the pure water produced has
zero value and is pumped to waste via a river, then the entire cost of
separation must be borne by the concentrated brine. If, however, it is
found that the pure water can be sold for agricultural purposes at $0.20
per thousand gallons, then the cost of concentration is $0.50-$0.20=$0.30
per thousand gallons. Obviously, if the disposal costs are greater than
$0.30 per thousand gallons, evaporation may be a usable disposal technique,
Purpose and Concept
Multistage flash evaporation is the most economical fully commercial
method available for concentrating inorganic salts up to 10% tds. In this
process the cost per thousand gallons of water evaporated is of interest,
and the blowdown is to be disposed of by other means. The minimum cost
per thousand gallons of water evaporated can be obtained by finding the
31
-------
performance ratio (defined as the pounds of water evaporated per 1,00
Btu's supplied to the brine heater) at which the total operating costs
are minimum for a given set of operating and economic parameters. _ ine
selection of a suitable set of operating parameters for concentrating
waste brines from municipal wastewater renovation plants is the first
task described in this section. The second task is the selection ot
a general grid of economic parameters to allow accurate costing ot
evaporation for any site selected within the United States. The next
task is to establish optimum performance ratios for the entire grid of
economic conditions. The final task is the conceptual design of a ^
multistage flash evaporator for the specific purpose of concentrating
waste brines from municipal wastewater renovation plants.
Operating Parameters
Where scaling of the brine heater is not a problem, previous studies
(Fluor, '59; Bechtel, '66) have demonstrated for single purpose plants
that:
The practical blowdown concentration for seawater conversion evap-
orators is between 6.0 and 7.0 percent dissolved solids, with the
total optimization being rather insensitive to this parameter. For
waste brine evaporators it is expected to be about 10%.
The optimum brine-heater outlet temperature should be about 350°F.
The evaporation plant pumps should be turbine-driven, and the tur-
bine exhaust steam should be used for the brine heater. This
results in the lowest power generation costs.
Techniques have been developed for optimizing the brine heater and
the brine blowdown temperatures. In no event should the brine blow-
down temperature be allowed to fall below 85° F, because of difficul-
ties in removing non-condensables at such low temperatures.
In cylindrical evaporator vessels, overflow type flashing weirs,
as described by Mulford (1965), should be run longitudinally (e.g.,
parallel to the tubes) between sloping floor sections in order to
provide the maximum economy of construction and still limit the
maximum brine overflow rate to less than 800,000 pounds per hour
per foot of weir. In the coldest stages, the weirs should be longer,
so that a brine rate of not over 400,000 pounds per hour is achieved.
In the current study of concentrating the brine from a municipal
wastewater renovation facility it has been assumed that the preceding
process is electrodialysis which concentrates to 7,000 mg/1 for feed to
multistage flash evaporation. It has been further assumed that a nost
treatment has been used in the electrodialysis plant, so that neutraliza-
tion to 7.0 PH of the 7,000 mg/1 influent brine to the multistage
evaporators will allow scale-free operation of the brine heater at
with blowdown concentrations up to 10% at a temperature of 100°F?
32
-------
Using the foregoing assumptions and operating parameters, the flow-
ing quantities for four sizes of ultimate disposal plants are:
Description Small
AWT WASTE BRINE at 7,000 mg/1, MGD 0.1
Intermediate
1.0
2.5
SLOWDOWN at 100,000 mg/1 for
ULTIMATE DISPOSAL, MGD
Economic Parameters
0.007
.07 0.175
0.7
In an evaporator plant, there are four economic parameters to be
considered:
Capital Cost, for which the total investment cost is used;
Fixed Charge Rate (FCR), or principally the capital recovery factor;
Cost of Heat, or steam cost in $/mbtu at the brine heater;
Pumping Cost, for shaft work in $/Kgal. of production.
Capital Cost; The total investment cost, including engineering
fees and profit, site development and land, must first be itemized to
show costs that depend upon the performance ratio (Ibs water/1000 Btu
at the brine heater), and costs that are independent of performance
ratio because they depend upon capacity only. The accuracy of this
itemization determines the accuracy, and in fact, the validity of the
entire optimization scheme. For the operating parameters previously
described, the total erected cost of the evaporator vessels depends on
the plant capacity and the performance ratio. These costs can be divided
into two parts: those proportional to condenser area and those proportional
to weir length. The cost of condenser bundles, demisters, and product
water trays is given (using Burns and Roe costs) by the equation:
$/ft2 condenser area = 7.5/(MGD)0'22
The cost of stage partitions, floors, and flashing weirs can be expressed
as a function of weir length. Development of these costs is illustrated
for a 2.5 MGD plant in Table 3. Weir length is equal to four times plant
capacity in MGD and is 10 feet for a 2.5 MGD plant. This results in a
brine rate of less than 400,000 lb/(ft)(hr) which prices all plants
conservatively.
The two components of erected cost of evaporator vessels are shown below
for various plant sizes:
Plant capacity (MGD)
Evaporator cost, $/ft2 of condenser
Stage cost, $/ft of weir
0.1
12.50
1400
1.0
7.75
868
2.5
6.25
700
10.0
4.50
504
The above costs are based on the 2.5 MGD plant size, and extrapolations
=>re made to the other sizes using a Chilton factor of 0.78.
33
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COST PER STAGE:
Corrosion
^ ««„ .... C,Ug. Allorc, ™.l «, «. -.I «.
Material ft ft _«1 _3E; i^
Stage Separator 63>g4 1/4 3/3.6
Plate Top C. bteej.
Stage Sep. PI. 50 1/4 3/8
Below Demisters C. Steel 10 ^
Adjustable
Flow Plate
Weir Plate C. Steel 10 1 10 1*
Splash Plate C. Steel 10 3 30 1/4 3/8
Product Tray ^ ^ gl, 1Q80in2
Sloping Floor C. Steel 8-1/4 10 82.5 1/4 3/8
Total Cost
7/16 17.85 1139
5/8 40.80 2040
5/8 25.50 255
5/8 25.50 765
Ib
0.0508 .323 in3 17.44
5/8 40.80 3350
Fabricated Erection
Cost Cost Total
Unit Total Unit Total Cost
$/lb $ $/lb $ $
.90 1,015.10 .125 142.38 1,167.50
.75 1,530.00 .125 255 1,785.00
100.00
.75 191.25 .125 28.13 219.40
.75 573.75 .125 95.63 669.40
1.60 27.90 .10 1.74 29.65
7-; 7S19.00 .125 510.00 3,029.05
7,000.00
$ 700.00
Cost per foot of weir
-------
Fixed Charge Rate; The fixed charge rate is the summation of the
annual capital recovery factor, the annual insurance charges, and income
and property taxes, all expressed as percentages of the total investment
over the lifetime of the plant. A fictitious fixed charge rate based
upon a uniform series must be developed if plant components are added or
replaced during the plant lifetime, or if the actual components of the
fixed charge rate are themselves non-uniform series. The fixed charge
rate used for the optimizations herein included has a constant value over
the plant lifetime, and this fact must be borne in mind when selecting
this factor for an optimum plant at a given site. Values of .05 to .25
have been used in this study.
Cost of Heat; For the purposes of this study, all costs for gen-
erating saturated steam at 357°F, including the annual capital and
operating costs of the boiler, and allowing for normal steam losses,
must be summed and expressed as $/mbtu delivered across the brine heat
exchanger. If the steam power plant is dual-purpose the cost of the
steam will have to be decided arbitrarily, based upon local conditions;
however, if it is single-purpose, turbine drives can be used for the
water pumps, with their exhausts manifolded into the brine heater. All
the generated heat that is not expended by pumping winds up in the brine
heater. A typical scheme would employ a boiler generating 452°F steam
at 245 psia pressure for supplying back pressure turbines. These tur-
bines would exhaust steam to the brine heater of the water plant at 357°F
and 147 psia. The boiler would be priced at about $1800/mbtu/hr at an
applicable annual fixed charge rate. Fuel costs would be adjusted for
an 84% stack efficiency with about a 3% allowance for loss of steam in
ejectors and leaks, plus operating and maintenance labor on the boiler
plant. Steam pricing must be done as carefully as possible, taking all
local conditions into consideration, since this is the prime operating
cost variable upon which the optimization depends. Selecting an incor-
rect cost for steam will result in an incorrect cost for water production
and an off-optimum plant.
Pumpinp Cost: This cost has virtually no effect upon the optimi-
zation, inasmuch as varying the performance ratio of the plant causes
an insignificant variation of the pumping head and no variation at all
in the amount of water pumped. Therefore, it can be calculated as a
fixed cost, dependent only upon the unit power charges in mills/kwhr and
added to the variable water cost. For various power rates, the pumping
cost per 1000 gallons of product water is as follows within the battery
limits of the water plant;
Power Cost, mills/kwhr 5 7.5 10 12.5 15
Pumping Cost, $/Kgal. HZO .046 .0772 .092 0.115 .139
For turbine drives, the pumping cost will average about $.05/Kgal. per
dollar cost of prime steam per million Btu's. Thus, if the steam cost
used in the optimization is $0.50/mbtu, then the pumping cost for the
optimized plant will be $0.025/Kgal. of product water.
35
-------
Optimum Performance Ratios
In this study, performance ratios and stages have been optimized
over a complete economic grid of capital costs, fixed charge rates,
unit steam costs and plant capacities from 0.1 to 10 mgd. Refer to the
Appendix for the mathematical development.
The optimization determines the cost of the water for the optimum
evaporator package, including erection, for a given cost of steam.
The cost of power, chemicals, maintenance, supplies and operating
labor must be added, together with capital costs for product and re-
cycle pumps and all other costs that depend on size and fixed charge
rate. However, the costs of power, chemicals, and expendable supplies
are independent of fixed charge rate. Annual maintenance and operating
labor are independent both of plant size and fixed charge rates. These
costs are included in the fixed cost for the water plant, except for
operating labor, which we have not assessed because it will depend on
local administrative procedure and cost sharing with the much larger
wastewater renovation plant. Operating labor would have to be added as
a separate item in any event.
Base Capital Costs for a 2.5 mgd plant:
Recycle pump $ 30,000
Cooling water pump 20,000
Makeup 8,200
Slowdown and product pumps 8,000
Deaerator 51,000
Steam jet air ejector 9,220
Electric 95,800
Instrumentation 121,600
Piping 140,000
Facility cooling water intake and
outlet piping 24,000
Chlorination ]_ 500
Site development 8 000
Buildings 40^000
Service water and sanitary 7,000
$564^320
Total Markup including shipping
and insurance, Engineering and
Construction and Escalation @ 30%
of Base Capital Cost. 169>300
Base Capital Cost $733,620
36
-------
0.1
.08
.0894
.179
.268
.357
.446
1.0
.495
.0554
.111
.166
.221
.276
2.5
1.0
.0447
.0894
.134
,1785
.223
10
2.92
.0327
.0654
.098
= 131
.163
Base capital cost for 0.1, 1.0 and 10 mgd can be calculated by
simply multiplying a cost factor from the following tables by the base
capital cost for 2.5 mgd or $734,000. Base water cost $/Kgal. is given
directly by the table as a function of fixed charge rate and size.
mgd
Capital cost factor
FCR 5%
10%
15%
20%
25%
Fixed Costs;
Chemicals, $/Kgal. $0,016 (cost of neutralization
to pH 7.0)
Maintenance and supply 0 . 004
Total Fixed Cost $0.02 $/Kgal.
Use of Nomoflrams for Optimum Performance Ratio and Water Costs
The economic conditions for waste brine disposal by evaporation
are most simply shown by nomograms. These alignment charts are arranged
for pivoting about a center key line, and cover a larger range of vari-
ables than required by the ground rules of this study.
Nomogram No. 1 allows the optimum performance ratio and the opti-
mum number of stages to be determined from the unit cost of steam, the
cost of condenser area and the annual fixed charge rate. It solves the
basic equation for optimum performance ratio:
2
RP + RP Q.551(Rp)2 = 846($Stm/$A)(l/FCR)
(l-.023Rp)
along with the basic equation for the optimum number of stages:
N = 5.25Rp - 23.84
To use, align the applicable fixed charge rate (FCR) with the unit
area cost ($A/ft2) for the evaporator condenser and shell. (These costs
are also shown as a function of plant size, mgd, in which case the unit
area costs can be disregarded, with the plant size being directly aligned
with the fixed charge rate.) Mark the point so ascertained on the key,
and then pivot on this point, so as to align the appropriate unit steam
cost ($Stm/mbtu). Both the optimum performance ratio, Rp , and the number
of stages, N, can now be read directly off of the nomogram.
37
-------
OPTIMUM PERFORMANCE RATIO VS. BRINE QUANTITY.UNIT COST OF
EVAPORATOR LESS STAGES. FCR AND STEAM COST, NOMOGRAM 1
BRINE QUANTITY, MOD, EVAPORATED
UNIT COST OF STEAM
$PER 106BTU
_10.0 t
- 9.0
- 8.0
- 7.0
- 6.0
- 5.0
-4.0
-3.0
-2.0
0.1-
1.0
-0.9
.0.8 1 n
-0.7 '
.0.6
-0.5
10.0-
"0.4
-0.3
-0.2
0.1
0.09
0.08
0.07
0.06
0.05
0.04
0.03
.02
01
COST OF EVAPORATOR
/LESS STAGES, $ PER FT2
r-100
I 80
—
- 60
-
- 40
-
- 20
- 10
- 8
_
- 6
_
4
-
- 2
$/STM
1.0 106 BTU $/pT2 KEy FCR N Rp
0.8
0.6
^_
ill ^*i*\ L 3 /
0.4 "*_>
-------
Nomogram No. 2 allows determination of the partial unit cost of
water and the partial capital cost of the plant from the performance
ratio and the cost of steam previously used, according to the equation:
$H_0/Kgal. = 16.6($Stm/mbtu)/Rp, .
i (opt.)
First, align the optimum performance ratio from Nomogram No. 2
with the appropriate steam cost. Read off the corresponding partial
cost of water, $/Kgal. (Fixed costs, base capital costs, power costs and
operating labor must be added.)
Second, align this cost of water with the applicable fixed charge
rate and mark the key line point.
Finally, align the key point with the appropriate plant size and
read from the nomogram the partial capital cost of the evaporator and
stages. (Fixed capital costs and markup must be added to get total in-
vestment costs.)
The nomograms allow optimization and pricing to two significant
figures. If in a particular case, greater accuracy is desired, this
can be achieved by solving the above three equations directly. The
development of these equations along with graphs for their solutions
are given in the Appendix.
Determining the Total Cost of Water Evaporated
Since the water evaporated is also condensed by the multistage
flash process', the cost of water evaporated is also the cost of product
water. In municipal wastewater treatment, the brine fed to the evapora-
tor will probably contain proteins that will decompose upon heating into
ammonia and other odor-producing products. Therefore, this product water
will be of little value, except perhaps for irrigation — unless it is
subjected to some post-treatment — a subject that is outside the scope
of this study. If the water fed to the evaporator, however, is well
water or river water, the product is potable. In either case the eco-
nomics that are presented herein are valid. The optimum performance
ratio charts, therefore, have a utility that is not limited to a muni-
cipal wastewater renovation scheme. These charts may be used for any
non-scaling evaporator feed that can be concentrated up to 10% total
dissolved solids.
The total cost of the water produced is the sum of all the partial
costs $/Kgal. due to:
Base capital cost
Partial water costs from optimization
Pumping costs for water and brine
Fixed costs
Operating labor costs
39
-------
PARTIAL WATER COST AND CAPITAL COSTS VS.
RP AND STM COST, NOMOGRAM 2
UN IT COST OF STEAM
$PER 106BTU
r— 10.0
- 9.0
- 8.0
— 7.0
— 6.0
- 5.0
- 4.0
— 3.0
- 2.0
- 1.0
- 0.9
- 0.8
- .0,7
— 0.6
— 0.5
- 0.4
- 0.3 $STM/106BTU
- 0.2
- 0.1
-0.09
—0.08
-0.07
-0.06
-0.05
-0.04
M(
(l)
^* ^
41
-0.03
-0.02
— 0.01
PARTIAL WATER COST
$PER KSgal.
r 100
BRINE QUANTITY
MGD
EVAPORATED
$/Kgal. K Rp
3D
».••
-— »
Xu)
\
— i*
^. —
(3)
\
N
- 0.01
$
•*.
-C.R
- 0.02
-
- 0.04
- 0.06
- 0.08
- 0.10
— n 2
—
- 0.4
- 0.6
- 0.8
= 1.0
- 2.0
- 4.0
- 6.0
- 8.0
- 10.0
- 20.0
- 40.0
- 60.0
E 80.0
•- 100.0
80
- 60
- 40
- 20
= 10.0
= 8.0
- 6.0
— 4.0
- 2.0
- 1.0
= 0.8
- 0.6
- 0.4
- 0.2
- 0.10
- 0.08
- 0.06
- 0.04
- 0.02
-0.010
-0.008
-.0.006
-0.004
- 0.002
- 0.001
KEY
OPTIMUM
PERFORMANCE
RATIO, RP
\1
\
2.0-
3.0-
4.0-
5.0-
6.0-
7.0-
8.0-
9.0-
10.0-
12.0-
14.0-
16.0-
18.0-
20.0-
25.0-
30.0-
PARTIAL
CAPITAL
COST
$
— 0.01
-0.02
-0.04
-0.06
= 0.08
-0.10
- 0.2
- 0.4
- 0.6
- 0.8
fc 1.0
3
2
107
8
6
A
106
8
- 2
- 105
Z 8
6
—
— 4
FIXED CHARGE h 2
RATE, FCR
1. Align Rp and cost of steam,
read water cost.
2. Align water cost with fixed
charge rate, mark Key.
3. Align key with brine quantity,
MGD, read capital cost.
-------
These different costs are handled as shown in the following example
for a 2.5 mgd evaporator plant.
From Nomogram No. 1, at FCR = 0.10, and Steam Cost = $0.863/mbtu
Rp = 18, N = 71
From Nomogram No. 2, at Rp = 18 and Steam Cost = $0.863,
Partial Water Cost = $0.79/Kgal. and $Cap. Cost = $2.4 million
Total Water Cost (excluding operating labor) = Base Cost + Partial Cost +
Pumping Cost + Fixed Cost = .0894 + 0.79 + .017 + .02 = $0.92/Kgal.
Conceptual Design of Multistage Flash Plant for Brine Disposal
Once the capacity of the evaporator plant has been established, and
the optimum performance ratio has been determined by using the above pro-
cedures, the conceptual design can be started. The performance ratio and
number of stages shown by the nomogram will be optimum provided that the
flashdown of the plant is a total of 250° F, the mean overall heat transfer
coefficient is 630, and the mean effective boiling point elevation, in-
cluding all allowances, is 4.3° F. For other conditions and for cross-
flow condensers a reoptimization will have to be conducted.
Using the three evaporator plant sizes required by this study for
concentrating the waste brine, (0.1 mgd, 1.0 mgd, and 10.0 mgd) and for
steam costing 46C/mBtu (corresponding to natural gas at 35C/mBtu) , together
with an annual fixed charge rate of 10%, optimum performance ratios and
optimum numbers of stages have been determined, using the nomograms.
These values have been fed into a computer using the Oak Ridge ORSEF code.*
This program completely designs the water plant and prints out all of the
design information, so that drawings can be made and detailed. Rectangu-
lar, multi-level modules are assumed for the cost calculations in the com-
puter program, but the engineering information generated can equally well
be applied to cylindrical vessels, and was done in a prior study (Bechtel '66),
Block diagrams (Figures 8 through 11) showing the water plant connec-
tions to the boiler and associated steam turbine drives for the water pumps
are presented on the following pages. These differ from a seawater con-
version plant in one important respect: the cooling of the multistage flash
evaporator plant is done, not with seawater, but with renovated municipal
wastewater, either preceding or following the quaternary electrodialysis
step. This procedure, if used on the feed stream of the electrodialysis
unit prior to acidification would raise the feed to 100° F, and the higher
temperature enhances the operation of the electrodialyzer. The feed water
The ORSEF code approximates the cost of operating labor as being:
Operating Labor, $/Kgal. = 0.351 (MGD)-'675
*See Appendix for computer printouts.
41
-------
0.1 MGD FEED
0.0066 MGD WASTE
0.0934 MGD EVAPORATED 11.2 PERFORMANCE RATIO
PUMPING POWER
-<
'2.86(10)6I
IBTU/HR |
I i
LU
z
.tr
GO
O
z
I
UL
O
o
TURBINES
SATURATED STEAM
3.31 (10)3LB/HR 430°F
220 PSIA
357° F
BRINE HEATER
147 PSIA
MISC. LOSSES
& EJECTORS
(3%)
CONDENSATE
FEEDWATER
SYSTEM
BOILER
NAT. GAS
1.54(10)3 CFH"
33 STAGE
HEAT RECOVERY SECTION
15.00(10)4 LB/HR
3.01(10)4LB/HR
11.97(10)4 LB/HR
COO LING WATER OUT
RENOVATED WASTE 60°F
3.73(10)4 LB/HR
PRODUCT 96°F 3.2K10)4 LB/HR
INFLUENT BRINE 60°F 3.43(10)4 LB/HR
WASTE @ 100°F, 10% SOLIDS 2243 LB/HR
I
4 STAGE
HEAT REJECT
RECYCLE
FIGURES. MULTISTAGE FLASH PRECONCENTRATOR - 0.1 MGD FEED
42
-------
1.0 MGD FEED
0.0655 MGD WASTE
.9345 MGD EVAPORATED PERFORMANCE RATIO 13.5
350° FLASHING BRINE
•
1
[— -u~4-
\ PUMPING POWER ~^ — ^
' ^-—
' ^^
_ _ W SATURATED STEAM
1 * 357°F 147PSIA
23.8(10)6I
3TU/HR BRINE HEATER , —
T
2.74(10)4 LB/HR 450°F
4 242 PSIA
MISC. LOSSES
& EJECTORS
(3%) |
BOILER
FEEDWATER ^
CONDENSATE *" SYSTEM
01
Z
a:
5s
0 t
> f>
o
UJ
tr
43 STAGES
HEAT RECOVERY SECTION
" ' ""N\— -^^^ "^^ *^~ "*"
COOLING WATER OUT
RENOVATED WASTE 60°F
2.47(1 0)5 LB/HR
PRODUCT 96°F 3.21 (10)5 LB/HR
INFLUENT BRINE 60°F 3.43(10)5 LB/HR
WASTE @ 100°F, 10% SOLIDS 2.24(10)4 LB/HR
i
NAT. GAS
1.31(10)4CFH
15.00HO)5 LB/HR
3.04(10)5 LB/HR
11. 96(10)5 LB/HR
J
4 STAGE
HEAT REJECT
% )
• — »l ^
RECYCLE
i
FIGURE 9. MULTISTAGE FLASH PRECONCENTRATOR -1.0 MGD FEED
43
-------
2.5 MGD FEED
0.163 MGD WASTE
2.337 MGD EVAPORATED
PERFORMANCE RATIO 14.5
PUMPING POWER
"\
|55.3(10)6|
IBTU/HR j
i !
DC
QQ
in
uj
cc.
CO
HI
_1
O
o
UJ
cc
TURBINES
SATURATED STEAM
6.39(10)4 LB/HR 452°F
245 PS IA
357°F 147 PS IA
MISC. LOSSES
& EJECTORS
(3%)
BRINE HEATER
CONDENSATE
i~
357° F
FEEDWATER
SYSTEM
BOILER
NAT. GAS
3.06I10)4 CFH
49 STAGES
HEAT RECOVERY SECTION
37.5(10)5 LB/HR
7.64(10)5 LB/HR
29.8(10)5 LB/HR
COOLING WATER OUT
RENOVATED WASTE
5.09(10)5 LB/HR
PRODUCT
8.02(10)5 LB/HR
INFLUENT BRINE
96° F
8.58(10)5 LB/HR
WASTE @ 100°F, 10% SOLIDS
5.607 (10)4 LB/HR
I
4 STAGE
HEAT REJECT
'--"ID
RECYCLE
FIGURE 10. MULTISTAGE FLASH PRECONCENTRATOR - 2.5 MGD FEED
44
-------
10 MGD FEED
0.655 MGD WASTE
9.345 MGD EVAPORATED
PERFORMANCE RATIO 16.3
PUMPING POWER
|197(10)6|
jBTU/HR
I ,
LU
tr
DO
HI
TURBINES
SATURATED STEAM
2.27(10)5 LB/HR 462°F
252 PS IA
357°F 147PSIA
MISC. LOSSES
& EJECTORS
(3%)
BRINE HEATER
CONDEMSATE
357° F
r_
FEEDWATER
SYSTEM
BOILER
NAT. GAS
LL
1.20(10)5CFH
o
o
in
CO
58 STAGE
HEAT RECOVERY SECTION
15.00(10)6 LB/HR
3.07(10)6 LB/HR
11.92(10)6 LB/HR
COOLING WATER OUT
RENOVATED WASTE
1.4(10)6 LB/HR
PRODUCT
96° F
3.2K10)6 LB/HR
INFLUENT BRINE
3.43(10)6 LB/HR
WASTE @ 100°F, 10% SOLIDS
2.24(10)5 LB/HR
I
4 STAGE
HEAT REJECT
RECYCLE
FIGURE 11. MULTISTAGE FLASH PRECONCENTRATOR - 10 MGD FEED
45
-------
in the evaporator heat-rejection tubes, would be adjusted to about 8 pH
so as to be non-aggressive, and so that savings in bundle construction
costs could be made by using non-exotic materials of construction. Addi-
tional savings in evaporator construction costs could be made by elimi-
nating the demisters throughout the plant.
The details of the plant equipment and the layout, except for the
smaller size vessels, would be similar to those developed by Fluor and
Bechtel, (1966). The OSW universal plant is also quite similar (Burns
and Roe, '68).
The design data for MSF Evaporators are summarized in Table 4.
MULTISTAGE FLASH EVAPORATION WITH ION EXCHANGE PRETREATMENT
Introduction
The previous sections of this report have considered the economics
of using multistage flash evaporation as a preferred concentrating means
for brine from the electrodialysis step of an advanced waste treatment
process. In such an evaporator plant, maximum economy is achieved by
running the brine heater at the maximum temperature possible without
scaling. By using cold lime treatment preceding the electrodialysis
step, the hardness of the secondary sewage effluent can, in many cases,
be reduced to the point where concentration to 10% total dissolved
solids is possible without scaling a brine heater operated at 350° F.
In other cases, a post-treatment of the electrodialysis brine will be
necessary. In any event, the concentrate stream will have to be ad-
justed for pH before being fed into an evaporator. A typical pH of the
concentrate stream from electrodialysis units is 4.0. This would have
to be neutralized to a pH of 7.0 with soda ash.
One way to avoid costly post-treatment of the effluent brine from
a conventional electrodialyzer would be to use sodium-cycle cation ex-
change on the feed stream to the evaporator, with the evaporator waste
brine stream itself used as a regenerant for the ion-exchange columns.
Thereby, the principal cost of the post-treatment would be the invest-
ment cost for the ion-exchange unit.
The operating costs for ion-exchange post-treatment at 0.1 mgd,
1.0 mgd, and 10 mgd are developed in the following pages.
Objective
The objective of this investigation is to determine the feasibility
of ion exchanging the calcium and magnesium salts in the electrodialvsis
brine concentrate to sodium salts. The brine concentrate is then further
concentrated by evaporation. The brine concentrate from the evaporator
is used to regenerate the sodium cycle ion exchanger. Concentration tn
saturation with sodium chloride is theoretically possible
46
-------
TABLE 4
SUMMARY OF MSFE COMPUTER OUTPUT
Based on following Design Criteria:
Feed
Concentration Ratio
Heat Rejection Stages
Recovery Ratio
Steam Saturated At
Brine, Maximum Temperature
Slowdown Temperature
Product Temperature
Tubing Outside Diameter
Tubing Wall Thickness
Tubing Material
Fouling Factor
Average Overall U
In-Tube Brine Velocity
Cooling Water Temperature
7000 mg/1
14.3
4
0.214 Ib Product/lb In-Tube Brine
357°
350°
100°
97.4°
0.75 in.
0.035 in.
Cu-Ni
0.0004
630 Btu/ft hr °F
5.25 ft/sec
60°
Feed Capacity; mgd
Product Water; mgd
Optimum Performance Ratio
Steam Flow: Ibs/hr
Pump Power Required; MW
Number of Evaporator Stages
Number of Trains
Brine Heater Surface Area; ft2
Evaporator Surface Area; ft2
Heat Rejection Surface Area; ft2
Number of Tubes; Brine Heater
Number of Tubes; Evaporator
Number of Tubes; Heat Rejection
0.1
0.09
11.2
3,300
0.03
33
1
266
3,750
252
53
53
24
1.0
0.93
13.5
27,400
0.31
43
1
2,380
47,000
2,250
532
527
199
10.0
9.30
16.3
227,000
3.23
58
4
21,100
596,000
19,900
5,319
5,276
1,630
47
-------
Discussion
Technical Approach; The electrodialysis process uses an electric
current to separate cationic and anionic components from the waste water
being renovated. Membranes allow the ions to pass from a dilute solution
on one side of the membrane to a concentrated solution on the other side
with a pH of the concentrated solution of about 4.0.
The total dissolved solids of the electrodialysis concentrate solu-
tion consists of 90% sodium salts and 10% calcium-magnesium salts. If
the calcium-magnesium salts are exchanged to sodium salts, the resultant
water stream is favorable to an evaporation process and the dissolved
solids are further concentrated. The waste stream from the evaporator,
using multistage flash, is a 10% brine solution and can be used as the
regenerant for the sodium cycle ion exchanger.
The composition of the electrodialysis brine concentrate is shown
in Table 5, Column A. The concentrate contains 700 mg/1 Ca and Mg as
CaC03 and 6,300 mg/1 Na as CaC03. The anions are 2,550 mg/1 Cl as CaCOs
and 4,450 mg/1 804 as CaC03. In the sodium cycle ion exchange process
the resin is in the sodium form. The calcium and magnesium ions in the
water are exchanged to sodium ions , producing a water containing sodium
chloride and sodium sulfate.
The effluent from the ion exchanger feeds to an evaporator. The
evaporator produces a distillate yield of 93% of the feed stream. The
waste stream containing the sodium salts is 7% of the feed stream.
The evaporator waste stream is composed of 10% of sodium chloride
and sulfate salts. A portion of this stream could be used for regen-
erating the sodium cycle ion exchange unit. The remainder of the evap-
orator waste stream would be used to rinse the" resins before being dis-
charged to waste. The spent regenerant solution containing calcium and
magnesium salts is also discharged to waste.
Results: The analysis of the electrodialysis brine concentrate fed
to the ion exchange column shown in Column A. The concentrate contains
700 mg/1 calcium and magnesium (as CaC03) and 6300 mg/1 sodium (as CaCO^) .
At a water flux of 5 gpm per square foot, the average Ca-Mg leakage in
the effluent leaving the ion exchanger will be 120 mg/1 Ca-MgH (as CaC03).
This was determined by extrapolating a hardness versus total dissolved
solids curve from 5,000 mg/1 tds to 7,000 mg/1 tds. The expected resin
exchange capacity is 22 kilograins per cubic foot (as CaC03) when re-
generated with 15 pounds NaCl per cubic foot resin. This value was ob-
solvel solL" eXtraP°lated CUrV£ °f eXch-S* capacity versus toSl dis-
For a one million gallon per day treatment plant 27 Qnn A
chloride per day is required. The waste stream fro™ i-h P *
sists of 10% salts or 58,400 pounds per day sodi™ CM * ^^^ ^
proximately 48% of this salt will be'consum^d in "e rtenerat^^' /
ion exchanger. The remaining solution will be used for r ins £ f t
discharged to waste. The spent regeneration solution conta^ and1t^en
and magnesium salts will be discharged to waste al^n °ntain:uiS calcium
of the waste, no dilute brine will be used for rinsin avoid dilution
48
-------
TABLE 5
WATER ANALYSIS-ULTIMATE DISPOSAL-ELECTRODIALYSIS BRINE
Constituents
mg/1 E
as CaCO«
Cations
Calcium
Magnesium
Sodium
Ammonia, Free
Total Cations
Anions
Bicarbonate
Carbonate
Hydroxide
Chloride
Sulfate
Phosphate
Total Anions
Other Analysis
Total Hardness
Total Alkalinity
P Alkalinity
Free Carbon Dioxide
Total Dissolved Solids
"A"
.D. Brine
Cone.
700
6,300
1,000
7,000
0
0
0
2,550
4,450
0
7,000
700
0
0
0
7,000
"B"
Na Cycle
I.X.
120
6,880
1,000
7,000
0
0
0
2,550
4,450
0
7,000
120
0
0
0
7,000
"C"
Evapor.
Distillate
0
0
1,000
-
0
0
0
0
0
0
-
"D"
Evapor.
Slowdown
1,716
98,384
—
100,100
0
0
0
36,465
63,635
0
100,100
1,716
0
0
0
100,000
49
-------
Conclusions and Summary
A one hundred thousand gallon per day sodium cycle treatment
would cost $15,000, and the installation would cost
$8,000. The softening cost with 7% FCR would be 32. U per 1
llons
gallons.
The capital cost of a sodium cycle ion exchange plant to produce one
million gallons softened water per day is $50,000 and $25 000 to inst^
the plant. The softening cost with 7% FCR is 5.0
-------
VAPOR COMPRESSION AND MULTIEFFECT EVAPORATION
Introduction
For concentrating brines beyond 10% tds, vapor compression or multi-
effect evaporators are generally used, and different methods are employed
to handle salt and scale depositions. Practical criteria, rather than
optimization criteria govern. Unit costs are functions of concentration
and capacity. Concentration to saturation, instead of dryness is gen-
erally more feasible. Capital costs and operating costs per 1000 gallons
(Kgal.) of water evaporated have been developed. These costs are directly
additive with conveyance costs to the nearest ultimate disposal site for
the residue to give the total cost for disposal in suitable units.
Objective
To concentrate beyond 10% solids, multieffect evaporators, when
properly designed, have an economic advantage both over single effect
evaporators and over multistage flash evaporators. The latter, because
they are not primarily designed as concentrators, are seldom used above
10% solids. Of the various multieffect arrangements, vapor compression
evaporators, which multieffect by forced recirculation, are particularly
suitable for concentrating brine to saturation for disposal. The purpose
here is to concentrate the brine to a minimum volume for disposal without
going through an expensive crystallization step, involving special heat
exchangers. Trouble in the evaporator can be avoided if concentration
does not proceed beyond saturation, which for sodium chloride is about
25% by weight.
Procedure
The flow diagram (Figure 12) shows how vapor compression
operates. The feed stream first enters a liquid-liquid heat exchanger,
and is preheated to the operating temperature of 228° by cooling the
product water and the saturated brine blowdown. The feed stream is
assumed to be the deaerated brine blowdown from a preceding multistage
flash evaporator and to contain 10% total dissolved solids. It is con-
centrated by vapor compression to 25% solids.
The feed stream next mixes with recycled brine from the evaporator
and enters the recirculating pump. It is pumped upward through a verti-
cal condenser and boils against the tube walls while condensing steam
from the vapor compressor, evolving thereby an equal quantity of steam
to that condensed.
The steam-brine mixture next enters the evaporator dome, where sep-
aration of the two phases occurs. Due to the boiling point elevation of
saturated brine, the steam evolved is superheated about 16° F, at 14.7
psia and reaches the inlet of the vapor compressor in this condition.
It is compressed isentropically to 342° F and then desuperheated to
238° F at 24 psia so as to provide a 10° thermal driving force across
51
-------
WATER VAPOR 0.42 MGD
228°F
COMPRESSOR
EVAPORATOR
RECYCLE BRINE
228° F
,,STEAM CHEST
TUBE BUNDLE
P=14.7PSIA
DESUPERHEATER
238° F
24 PSIA
SUBMERGED
RECIRCULATION
PUMP
CONDENSATE
238°F
CONDENSER
BRINE SLOWDOWN
0.28MGD@25%TDS
PRODUCT WATER
0.42 MGD
FIGURE 12. VAPOR COMPRESSION PLANT FLOW DIAGRAM
52
-------
the condenser. The condenser must be provided with a deaerating section
(not shown) to remove any non-condensables not already removed by the
preceding multistage flash evaporator. The residual brine collects in
the bottom of the evaporator, from which a portion is blown down at 25%
solids, while the remainder mixes with the preheated feed stream to com-
plete the cycle.
Discussion
The fact that the feed stream consists of the blowdown stream from
a preceding multistage flash evaporator means that the feed stream is
almost completely deaerated before entering the vapor compression unit.
Since non-condensables constitute one of the principal irreversibilities
of the vapor compression cycle, a completely deaerated feed can be more
economically processed by vapor compression than by multiple effect, at
ordinary power costs. Moreover, the use of electrical energy saves the
capital cost of the boiler plant otherwise required with multieffect
evaporators. With practical temperature approaches in the heat exchangers,
the total energy consumption of the compressor, at 70% overall efficiency
will run about 132 Kwhr/Kgal. Pumping energy will run about 8 Kwhr/Kgal.,
so that the total energy consumption of the evaporator unit will be 140
Kwhr/Kgal.
A major disadvantage of vapor compression is the large amount of
operating and maintenance labor necessary to keep the compressor blades
in balance and the tube surfaces free from deposits, when operating at
high solids concentrations. For the intermediate size plant, we have
allowed three man-days per month to cover part-time operating labor and
periodic cleaning of the tubes. For a small size unit such as this, when
considered in relation to the size of the complete waste renovation plant
of which it is a part, this proration of man-hours is probably sufficient.
Conclusions and Summary
As an example of the total operating costs for concentrating 10%
brine to 25% brine for 1.0, 10.0 and 100 mgd waste water renovation facil-
ities, with an annual fixed charge rate of 10% and a power rate of 12
mills per kilowatt-hour, the estimated costs from the accompanying graph
(Figure 13) are respectively:
Water Evaporated, Kgal./day 4.2 42 420
Cost in $/Kgal. Evaporated $5.48 $3.31 $2.44
The components of cost making up the total cost given in Figure 13 are
presented in Table 6. The information given in Table 6 was taken from:
Dodge & Eshaya; Chambers & Larsen, '60; and OSW '68.
53
-------
§9-0-1
<
(X
o
Q.
< 8.(H
i 7.oH
DC
O-
I
cc
g
6.0-
5.0-
CD
4.0-
s«
oa 2.0H
fe
O
O
1.0-
S 0.0
POWER COST: 12 MILLS/KWHR
6789 0.01 2 3 4 56789 0.1
WATER EVAPORATED, MGD
FIGURE 13. VAPOR COMPRESSION EVAPORATION
0.001
6 7 8 9 1.0
-------
TABLE 6
VAPOR COMPRESSION EVAPORATOR COSTS
Feed mgd @ 10% Solids
Product HO Gal. /Day
Brine to Disposal
@ 25% Solids
Capital Cost $
$/Daily Gallon
$ /Annual Kgal.
$/Kgal. @ FCR = .05
FCR = .10
FCR = .15
FCR = .20
FCR = .25
Power cost e 14° Kf r
Kgal.
$/Kgal. @ 5 mills
@ 10 mills
@ 12 mills
@ 15 mills
@ 20 mills
@ 25 mills
0. & M. Labor $/Kgal.
0.7
420,000
280,000
714,000
1.70
5.17
0.259
0.517
0.775
1.034
1.293
0.24
0.07
42,000
28,000
126,000
3.00
9.13
0.457
0.913
1.37
1.826
2.28
.70
1.40
1.68
2.10
2.80
3.50
0.72
0.007
4,200
2,800
22,650
5.40
16.40
0.82
1.64
2.46 A
3.28
4.10
B
2.16 C
Total Cost $/Kgal. Evap. = A + B + C
55
-------
SUBMERGED COMBUSTION
Introduction
The brine effluent of the multistage flash evaporator (MSEE) dis-
cussed previously in this report, is about 100 times as concentrated
as the original secondary sewage treatment effluent. However, e^en .
after this degree of concentration has occurred, the volume^of the brine
is still too large to be economically transported to an ultimate dis-
posal site. Where solar evaporation ponds cannot be used, multistage
flash evaporation is the most economical alternative for concentrating
brine to 7%. For concentrating the brine further, another method
which may be more economical is evaporation by submerged combustion.
This technique can be used to increase brine concentration to 50 or
60% tds, a concentration which is more than sufficient for economical
transportation to an ultimate disposal site.
Objective
The objective of this section is to examine the use of submerged
combustion evaporation to concentrate multistage flash evaporation blow-
down from seven to fifty percent tds. Approximate costs have been deter-
mined for 10,000 gpd and 1,000,000 gpd SCE plants.
Discussion
Submerged combustion evaporation (SCE) has two principal economic
advantages for the concentration of MSFE brine effluent. The first is
low capital cost which, for a 1.0 mgd plant large enough for a sewage
effluent of 100 mgd, is $1,520,000 (see Table 7). The second advantage
is low maintenance costs. The addition of an SCE plant to an MSFE plant,
ten times as large, would probably not require any additional personnel.
The low capital and maintenance costs are largely a result of the absence
of condensers and heat exchangers. At an annual fixed charge rate of
10%, total costs for the 1.0 mgd plant are $4.90/Kgal. evaporated and
$0.0435 per/Kgal. of sewage plant effluent (see Table 8). Costs for the
0.1 mgd plant are just slightly higher and total costs for the 10,000
gpd plant, large enough for 1.0 mgd of sewage plant effluent, are $6.58/
Kgal. evaporated and $0.0586/Kgal. sewage plant effluent. In this proc-
ess no heat recovery is attempted, which leads to high operating costs
(see Table 7) , accounting for from 50 to 70% of the total submerged com-
bustion evaporation cost for 10,000 gpd plant, and 75 to 90% of the costs
for the two larger plants (see Table 8). Operating costs could be re-
duced by using the vented gases for preheating'the feed brine, but the
adverse effect on capital costs caused by introducing heat exchangers
would probably outweigh the operating cost reduction and result in an in-
creased total cost of the process. For economical transportation to an
ultimate disposal site, the effluent of an MSFE must be reduced to about
one-seventh its initial volume. This means about 92% of the water in
the MSFE brine must be evaporated by submerged combustion.
56
-------
TABLE 7
DATA ON CONCENTRATING INORGANIC WASTE STREAMS FOR
7 TO 50 PERCENT SOLIDS BY SCE
MGD of Sec. Sewage Effluent
Percent Solids in Feed to Sub.
Comb. Ev.
Feed Rate of 7% Brine Stream (GPD)
Feed Rate of 7% Brine Stream (GPH)
Feed Rate of 7% Brine Stream (Ib/hr)
Solids Rate (Dry Basis) (Ib/hr)
Product Rate at 50% Solids (Ib/hr)
Water Evaporated (Ib/hr)
Firing Rate (106 Btu/hr)
Number of Units
Fuel Cost at $0.35/10 Btu ($/hr)
Electrical Cost at 12 mills/kwh ($/hr)
Total Operating Cost Less Labor ($/hr)
Total Operating Cost Less Labor
($/1000 gal. evaporated)
Approximate Capital Cost Prefabricated
with Scrubber and Installed
Annual Capital Cost at 5%/yr Fixed
Charge Rate ($/yr)
Annual Capital Cost at 10%/yr Fixed
Charge Rate ($/yr)
Annual Capital Cost at 12.5%/yr Fixed
Charge Rate ($/yr)
Annual Capital Cost at 15%/yr Fixed
Charge Rate ($/yr)
Annual Capital Cost at 20%/yr Fixed
Charge Rate ($/yr)
Annual Capital Cost at 25%/yr Fixed
Charge Rate ($/yr)
CASE I CASE II CASE III
1 10 100
7%
7%
10,000 100,000 1,000,000
417 4,170 41,700
3,480 34,800 348,000
243 2,430 24,300
486 4,860 48,600
2,994 29,940 299,400
4 40 400
11 8
$ 1.40 $ 14.00 $ 140.00
$ 0.27 $ 1.80 $ 18.00
$ 1.67 $ 15.80 $ 158.00
$ 4.64 $ 4.37 $
4.37
$55,000 $163,000 $1,520,000
$ 2,750 $ 8,150 $ 76,000
$ 5,500 $ 16,300 $ 152,000
$ 6,875 $ 20,375 $ 190,000
$ 8,250 $ 24,450 $ 228,000
$11,000 $ 32,600 $ 304,000
$13,750 $ 40,750 $ 380,000
57
-------
TABLE 8
7 TO 50 PERCENT BY SCE
Sec. Sewage Effluent (MGD)
Feed Rate 7% Brine Stream (GPD)
Capital Cost at 5%/yr FCR
($/1000 gal. evaporated)
Capital Cost at 10%/yr FCR
($/1000 gal. evaporated)
Capital Cost at 12. 5%/yr FCR
($/1000 gal. evaporated)
Capital Cost at 15% /yr FCR
($/1000 gal. evaporated)
Capital Cost at 20%/yr FCR
($/1000 gal. evaporated)
Capital Cost at 25%/yr FCR
($/1000 gal. evaporated)
Total Cost at 5%/yr FCR
($/1000 gal. evaporated)
Total Cost at 10%/yr FCR
($/1000 gal. evaporated)
Total Cost at 12. 5%/yr FCR
($/1000 gal. evaporated)
Total Cost at 15%/yr FCR
($/1000 gal. evaporated)
Total Cost at 20%/yr FCR
($/1000 gal. evaporated)
Total Cost at 25%/yr FCR
($/1000 gal. evaporated)
Total Cost of SCE 5%/yr FCR
($/1000 gal. of Sec. Effluent)
Total Cost of SCE 10%/yr FCR
($/1000 gal. of Sec. Effluent)
Total Cost of SCE 12. 5%/yr FCR
($/1000 gal. of Sec. Effluent)
Total Cost of SCE 15%/yr FCR
($/1000 gal. of Sec. Effluent)
Total Cost of SCE 20%/yr FCR
($/1000 gal. of Sec. Effluent)
Total Cost of SCE 25%/yr FCR
($/1000 gal. of Sec. Effluent)
(90% LOAD FACTOR)
CASE I
1
10,000
$ 0.98
1.96
2.45
2.93
3.92
4.90
5.62
6.58
7.08
7.56
8.56
9.52
0.0500
0,0586
0.0629
0.0672
0.0760
0.0846
CASE II
10
100,000
$ 0.29
0.58
0.71
0.87
1.16
1.43
4.66
4.95
5.08
5.24
5.53
5.80
0.0414
0.0439
0.0452
0.0466
0.0492
0.0515
CASE III
100
1,000,000
$ 0.27
0.53
0.63
0.81
1.07
1.34
4.64
4.90
5.04
5.18
5.43
5.71
0.0412
0.0435
0.0448
0.0461
0.0483
0.0508
58
-------
The submerged combustion evaporator operates as a direct contact
evaporator (see Figure 14). Fuel gas and air are mixed and then fired
by a high energy release burner into a combustion chamber. Hot com-
bustion products from this chamber are exhausted through a small port.
The liquid to be evaporated, in this case MSFE effluent mixed with re-
cycled product (the product is already at 50% tds) , is injected at a
controlled rate from an annular feed chamber jacket in the exhaust port
of the combustion chamber. A complete exchange of heat takes place in-
stantly as the liquid stream enters the exhaust gas stream.
The heated product is separated from the quenched gas stream in a
cyclonic separator. Spent gases are exhausted and the product is col-
lected and drawn off for ultimate disposal and for recycling with fresh
MSFE effluent.
Conclusions and Summary
Estimates of costs have been prepared for submerged combustion
evaporators for three capacities, 10,000 gpd, 0.1 mgd, and 1.0 mgd
(see Tables 7 and 8). The estimates are predicated on a natural gas
price of $.35 per million Btu, power costs of 12 mills per kwh, and
no maintenance cost. Capital costs for units to be used with 10,000
gpd, 0.1 mgd, and 1.0 mgd plants, including prefabrication with a
scrubber and installation, have been estimated at $55,000, $163,000,
and $1,520,000, respectively. Operating costs per thousand gallons
evaporated have been estimated at $4.64, $4.37, and $4.37, respectively.
The total unit cost for submerged combustion evaporation will, of course,
depend on the fixed charge rate. The total costs for submerged combus-
tion evaporation per thousand gallons evaporated and per thousand gal-
lons sewage plant effluent are given for several fixed charge rates in
Table 8 and Figure 15 respectively. For a 1.0 mgd plant with a 10%
FCR, the cost is $4.90/Kgal. evaporated. Because of the prior combined
concentrating effects of the electrodialysis plant and MSFE, there is
only one gallon evaporated by SCE for each 116.28 gallons of sewage
plant effluent. The resulting cost for concentration by SCE is $0.0435/
Kgal. of sewage plant effluent. Although the above costing procedures
have been based upon evaporating a 7% brine feed, the costs per^ 1,000
gallons of water evaporated should remain essentially the same if a
10% brine feed concentration is used.
59
-------
SCRUBBER
'BLEED
GAS SUPPLY
I SCRUBBER FEED FEED-*
1 CIRCULATING SYSTEM
2 CIRCULATING PUMP
3 FEED CHAMBER
4 COMBUSTION CHAMBER
5 VENTURI
6 SEPARATOR
7 RECIRCULATION
8 PRODUCT DISCHARGE
9 EXHAUST DUCT
10 COMBUSTION AIR BLOWER
11 BURNER
12 MODIFIED VENTURI SCRUBBER
13, SCRUBBER CIRCULATING PUMP
14 SCRUBBER SEPARATOR SECTION
15 EXHAUST
DESCRIPTION OF OPERATION
Feed solution is introduced into the circulation system (1) and pumped (2) to the feed chamber (3)
where it meets the products of combustion jetting from the combustion chamber (4). The combus-
tion products and the solution mix in the Venturi (5) and enter the separator (6) where the
gases and the solution are separated. Some of the solution is recirculated (7) by the circulation
pump (2) as product is drawn off (8) and the gases are vented (9). The liquid level in the separator
is maintained by a level control which regulates the product valve. The feed valve is signalled from
the specific gravity measured ahead of the feed chamber.
Combustion air is supplied by a positive displacement blower (10) equipped with a filter silencer
and a snubber. Fuel gas is regulated by the fuel gas controls and ignited in the combustion chamber
in a burner (11).
The stack gases from the separator are scrubbed in the modified venturi scrubber (12), fed with weak
liquor by the scrubber circulating pump (13). The scrubbed gases are separated from the liquor in
the separator section (14) and discharged (15).
FIGURE 14. TYPICAL FLOW DIAGRAM
SUBMERGED COMBUSTION EVAPORATSON
60
-------
10.0
2 9.0
O
CO
8.0
O
o
a
cc
7.0
6.0
CO
>
m
5.0
3.0
LL
O
§ 2.0
o
1.0
0.0
FCR = 25%
FCR = 20%
FCR = 15%
FCR = 12.5%
FCR = 10%
FCR = 5%
I I i i i i
POWER COST = 12 MILLS/KWHR
j i
j i
i i 11
0.001
5 6789 0.01
6 7 8901
BRINE FEED CAPACITY, MGD
FIGURE 15. SUBMERGED COMBUSTION EVAPORATION
5 6 7 8 9 1.0
-------
PIPELINE CONVEYANCE TO DISPOSAL AREA
Abstract
The optimization of pipeline conveyance costs depends on the pump-
ing velocity as the optimization parameter. As this is a multidimen-
sional problem, a nomogram and a computer program have been developed
to express the results. Parametric equations for the capital costs
and the conveyance costs per Kgal. of brine have been developed as a
function of the distance to the ultimate disposal site.
Introduction
Conveyance by pipeline is an integral part of most ultimate waste
disposal methods. It is also considered as a complete disposal method
in itself.
The effluent brine of the treatment facility is transferred via a
pipeline to the nearest site where it can be ultimately disposed (such
as the sea, a salt lake, an injection well field, or a lined evaporation
solar pond).
Our purpose is to evaluate the unit cost for this method of dis-
posal and compare it with the unit costs of other disposal methods in
order to find the best method to apply to a particular site.
The unit cost for such a disposal method is, in fact, the unit
cost of water conveyance, since the effect of changes in density and
viscosity of the wastes on conveyance cost is minor. (Koenig, '66,
shows that for a 55% concentrated brine, the increase in the cost of
conveyance is only about 3%.)
Cost Analysis of Conveyance by Pipeline
Costs of Pipelines; The total cost of disposal by pipeline is the
sum of the partial costs of the following components: cost of the pipe
(installation and material and OMR) , cost of the pumping stations (pumps
installed and OMR), and the cost of electrical power.
These partial costs are functions of the diameter of the conveyor.
A designer may, in fact, choose almost any arbitrary pipe diameter.
The use of a smaller diameter pipe will result in a lower initial capi-
tal investment, but a greater pressure drop,-requiring larger pumps
and higher power costs. Similarly, the use of a larger diameter pipe
results in higher investment costs but lower pump and power costs.
Accordingly, for every given capacity there is some optimum diameter
that minimizes the cost of conveyance (disposal).
62
-------
Cost Optimization; Finding this optimum diameter has been the
purpose of many previous studies. Burwell ('67) developed an analyti-
cal expression to represent the system. As a result, he was able to
optimize his system analytically to obtain optimum pipe diameter and
cost of conveyance for his particular set of economic parameters.
There are, however, some simplifications in the Burwell report.
An effort has been made to eliminate them in this analysis. For example,
in calculating the friction pressure drops for the flow in pipes, Bur-
well used the Hazen-Williams formula because of the difficulty of apply-
ing the more accurate Darcy's formula in a parametric study. The use
of a*digital computer to perform the calculation allows application of
Darcy's formula. Thus, more accurate results for the pressure drop
and for the optimum diameter and costs have been obtained in this study.
Another major improvement on Burwell's approach is the computer
selection of the nominal, rather than the theoretical, pipe diameter
for the optimized system. In his cost equation, Burwell uses continu-
ous, rather than discrete, values of the pipe diameter, in optimizing
his cost equation mathematically. The resulting diameter is, in most
cases, a non-standard size. However, a standard-size diameter would
have to be used in practice. Its use would result in an off-optimum,
but practical minimum, disposal cost. This limitation was neglected
by Burwell. Comparing the total conveyance costs for the two neighbor-
ing standard-size diameters of the mathematical optimum, the practical
minimum is obtained in this study by choosing the one with the lower
operating cost.
Nomogram; The cost of conveyance has been developed in terms
of dollars paid for conveying 1,000 gallons a distance of 100 miles, or
units of cents per kilo-gallon-miles.
The cost of conveyance is prorated to the capacity of the line
on a yearly basis. It is the sum of the partial costs resulting from the
cost of material and labor invested in the pipe, the cost of pumps required
to overcome the pressure drop, the cost of maintenance of the pumping sta-
tions, and the cost of electrical energy required to drive the pumps.
(Note: Only horizontal pipes have been considered.)
Upon this basis, the following equation has been developed for
the optimum pipeline size. (See Appendix for mathematics.)
D6.29 _ Q? |1>508 x 10-3 x B + 0.719 (Z/FCR')(10)"2] = Q3 x A3
The following nomogram (No. 3) solves this equation.
63
-------
B X2 FCR1 X-j X' Z ADO
[$/Hp] X100 [mills/kwh] [$/Ft] [INCH] [MG
1 Ftfl — «^— - * • l **• -• —• •" M ****
IOU
125 ~
100
85
-
0.40
-
0.30
"
— 0.20 10 —
— 0.10
15 —
0.00
-
3.00 —
2.00 —
-
-
1.00 —
^s
/
^ 0.50 -
0.30
75 (-)U.U/ /!U U-^J
— 4.50
4nn
— 3.00
>-
— 2.00
S
S
s
V1-00^^-*
2. — """
— 0.50
- 0.30
— n IR
20
-
— 15
•
-
10
^— ^^"^^
-
*j
—^ -^
— 15
r\**.
— 34
- 30
— 20
— 10
6
— 5
- 4
- 2.5
— 2
10
— 5
1.0
- 0.5
- 0.2
•0.1
NOMOGRAM NO. 3 UNIT COST OF BRINE DISPOSAL BY PIPELINE CONVEYANCE, $/Kgal. X 100 MILES.
-------
Use of Nomogram to Obtain Optimization Diameter
Required parameters:
FCR' = Fixed charge rate + 0.0025
Z = Power cost; (mills /kwh)
B = Pump cost; ($/HP)
A = Base cost = cost of a 12-in. diameter pipe,($) per linear foot
Using values of Z and FCR', find value of Xr on respective scales.
Using value of B, find corresponding X .
X = Xx + X2
Using values of X' and A, find point on K..,, line (which coincides
with Z line). * A
Using point on key line and desired capacity of pipeline as pivot
points, find optimized' diameter (D) .
Example :
Z = 12; FCR' = (0.1475 + 0.0025) = 0.15; B = 85; A = 10.43
Z and FRC' Xj_ = 0.80
B X2 = 0
X' = 0.80
X1 and A point on key line
for Q = 1 mgd; D 8.0 in.
Use D = 8 inches
The numerical value of D is, in most cases, a non-standard diameter.
In these cases the cost of conveyance must be evaluated for the two stand-
ard pipe sizes adjacent to the calculated value of D, and compared with
them. The standard diameter with the lower cost is then selected.
Conclusions and Summary
Once the optimum pipe diameter has been selected the unit cost $/Kgal,
of conveyance per £ miles can be determined by use of the following cost
equation:
CP = (-i~) [1.447 A(FCR')Dlt29 + 2. 738(10)"4(FCR' )R + (50fd Q3/D5)
(5.628(10)~4(FCR')B + 2.683(10)"3Z) ]
The pipeline sizes and costs appearing in this report were determined
by the computer program appearing in the Appendix.
For the above case, with a friction factor of 0.02 and right-of-way
cost of $5000/mi.,the conveyance cost per 100 miles will run $1.632/Kgal.
65
-------
OTHER METHODS
Introduction
According to the Technical Approach, processes which are ancillary,
such as pretreatments and post-treatments, and processes which appear
to be of dubious feasibility are to be given merely cursory treatment.
Of these methods, Impoundment with Controlled Release of Brines is
not applicable to the selected sites, and therefore has not been devel-
oped in detail; Brine Desulfation employs Barium, which is illegal for
use in water supplies; Direct Contact Oil-Water Evaporation has serious
technical difficulties, and has never been reduced to practice; Electro-
dialysis with ion-specific membranes turns out to be a most promising
process, which however, is generally outside the scope of this study
because it is part of the quaternary treatment process preceding the
operations under study; therefore, in this study it has been considered
as a post-treatment of AWT wastes, and not as a disposal step.
Impoundment and Controlled Release of Wastes
Generally, the purpose of an impounding reservoir is to store a
specific waste during periods of low flow in a receiving stream, for
subsequent discharge during periods of high flow. The objective of this
operation is to maintain a relatively constant concentration of the waste
in the receiving stream. Although the total quantity of polluting wastes
remains the same, impounding reduces very high concentrations that would
occur during periods of low stream flow.
With regard to brine wastes, storage would be accomplished in an
artifical reservoir or lagoon. An impervious liner would prevent seepage
to underlying ground water. The size of the lagoon is determined based
on the historic duration of low flow periods for the specific stream,
the daily brine flow, the brine concentration, and the desired chloride
level in the receiving stream. The lagoon is provided with a controlling
outlet structure to allow discharge proportional to stream flow.
The basic principle of operation of the impounding reservoir is that
the chloride concentration in the receiving stream shall be kept as nearly
constant as possible. Thus, the discharge from the reservoir must be re-
duced or eliminated entirely during periods of low flow, while during
periods of high flow the discharge must be increased until the concentra-
tion of chlorides in the river reaches the design value.
If the flows that will occur during any particular year were known
in advance, and if the contribution of each tributary were proportional
to its drainage area, it would be possible to operate an impounding
reservoir in such a manner as to maintain a constant chloride concentra-
tion at any particular point. In practice this is not possible. It is
66
-------
therefore necessary to select the concentration at one point along the
river as a basis for operating the reservoir. Using the stream flow
records for the chosen point, it is then possible to compute an arbitrary
concentration of chlorides that must be maintained at the point. In
addition, the system may be automated, if desired, by use of a continu-
ous chloride analyzer installed at the selected point in the stream.
An output signal from the analyzer can be utilized to automatically
regulate the control device on the reservoir outlet.
In designing a specific system, regulatory agencies must first be
consulted for assistance in establishing the chloride level to be main-
tained in the stream. A minimum historic stream flow is then selected
for a specific point in the stream. This value would most likely be
based on a minimum monthly average taken for a certain period, such as
10 years. These design parameters, together with information on brine
flow and concentration, are utilized to size the impounding basin. A
system balance is then developed by use of stream flow records for a
two or three year period. If there were no restrictions regarding ex-
penditures or land availability, the system could be designed to main-
tain a constant year-round chloride concentration in the stream. If
restrictions regarding reservoir size do exist, the resulting chloride
concentration in the stream at any time can be determined.
The major part of the cost associated with an impounding reservoir
is the cost of capital expenditures required for initial installation.
Annual operating costs are minimal, particularly where automatic control
of discharge is not employed and there are no resulting charges for in-
strument maintenance. Capital costs include land acquisition, construc-
tion of the reservoir and outlet structure with its regulating device,
purchase and installation of an impervious liner, and purchase and in-
stallation of chloride analyzer, if applicable.
In summary, an impounding reservoir permits the pollution load
caused by the disposal of brine wastes in a stream to be spread over
the entire year. In this way the average chloride concentration in the
stream is not reduced, but peak chloride concentrations during periods
of low stream flow are avoided. The improvements created during these
periods are balanced by the increase in the chloride concentration
during periods of higher stream discharges. Optimum design and opera-
tion of an impounding basin would provide constant chloride concentra-
tion in the stream during all periods.
An operating installation utilizing a storage reservoir of this
type is the Columbia Southern Chemical Corporation Plant at Barberton,
Ohio. This program is operated jointly by Pittsburgh Plate Glass Co.
and the Ohio Kiver Valley Water Sanitation Commission (ORSANCO). Flgure
16 shows the location of the monitor stations of the ORSANCO network.
Information on the stations is given in Table 9.
67
-------
WILKINSBURG
("H
PT. MARION
ORSANCO network of monitor
stations on the Ohio River and
some major tributaries provides
means for continuous checking
of water-quality conditions.
PITTSBURGH
BEAVER FALLS
SO. PITTSBURGH
WEIRTON
POWER
WHEELING
W.NF.ELDDAM
STRATTON
TORONTO
STEUBENVILLE
CABIN CREEK
PARKERSBURG
HUNTINGTON
SANDY
SOUTH POINT
PORTSMOUTH
GREAT MIAMI....
MARKLAND DAM
SYMBOL CODE
ELECTRONIC MONITORS
WATER USERS COMMITTEE STATIONS
.S. GEOLOGICAL SURVEY STATIONS
C r~] U
FIGURE 16.
ORSANCO WATER QUALITY MONITORING STATIONS ON THE OHIO RIVER
68 DAM 53
-------
Pittsburgh, Pa.
South Heights, Pa.
Stratton, Ohio
Toronto, Ohio
Weirton, W. Va.
Steubenville, Ohio
Power, W. Va.
Yorkville, Ohio
Wheeling, W. Va.
Moundsville, W. Va.
Natrium, W. Va.
Willow Island, W. Va.
Parkersburg, W. Va.
TABLE 9
ORSANCO WATER QUALITY MONITOR STATIONS
OHIO RIVER STATIONS
Mile Point
2.3
15.8
55.0
59.1
62.2
65.3
79.3
83.6
86.8
111.0
119.4
161.0
183.7
Type
B
A,B,C
A,C
B
B
B
B
B
B
B
B
A,B
B
TRIBUTARY
New Haven, W. Va.
Addison, Ohio
Huntington, W. Va
South Point, Ohio
Portsmouth, Ohio
Meidahl Dam
Cincinnati, Ohio
Miami Fort, Ohio
Markland Dam
Madison, Ind .
Louisville, Ky.
Cane Run , Ky .
Evansville , Ind .
Dam 53
STATIONS
Mile Point Type
Allegheny River at Kinzua, Pa.
Allegheny River at Oakmont, Pa.
Allegheny River at Wilkinsburg, Pa.
Monongahela River at Pt. Marion, Pa.
Monongahela River at Charleroi, Pa.
Monongahela River at South Pittsburgh,
Beaver River at Beaver Falls, Pa.
Muskingum River at Philo, Ohio
Muskingum River near Beverly, Ohio
New River at Glen Lyn, Va.
Kanawha River at Cabin Creek, W. Va.
Kanawha River at Winfield Dam, W. Va.
Big Sandy River at Louisa, Ky.
Wabash River near Hutsonville, 111.
Pa.
241.6
260.7
304.2
318.0
350.7
436.2
462.8
490.3
531.5
559.5
600.6
616.8
791.5
962.6
A,B,C
B
A,B
B
B
C
A,B
A,B
C
B
A,B
A,C
A.B
C
Mile at which
Tributary Enters
Ohio River
Miles from Sampling
Station to Confluence
of Tributary with
Ohio River TV
0.0
0.0
0.0
0.0
0.0
0.0
25.4
172.2
172.2
-
265.7
265.7
317.1
848.0
198.0
12.3
8.9
90.8
42.5
4.0
5.3
66.8
28.0
93.9
72.0
31.1
20.3
163.8
. — -. . «f .r. 1,
c
A.B.C
B
C
A,B
B,C
A,B
B
A,B,C
B
B
A,C
B
A,C
-------
Hauling of Dry Salt or Concentrated Brines
Hauling has been considered as an ultimate waste disposal method
that would follow some preconcentration technique (solar evaporation,
multistage flash evaporation, multi-effect evaporators, etc.). The
costs of preconcentrating to small volumes, such as can conveniently
be handled by hauling, are generally so high that the overall combina-
tion of disposal schemes becomes unattractive even before the hauling
costs are considered. For this reason, and because of the large volumes
of brine that would have to be handled at the three selected sites^for
this study, hauling of dry salts is not economical at any of the sites
studied. Instead, abandonment at the evaporation site is used.
The costs for hauling by tank-truck and by rail tank-car have pre-
viously been evaluated and have been presented by M.C. Mulbarger. His
results in the graphical form (Figure 17) are reprinted here.
Highway tank-truck hauling costs investigations have shown that
the method is economical for distances of less than 35 miles and for
quantities of less than 17,000 gpd (Koenig, '63).
Rail tank-car hauling is economical for slightly greater distances
but is also limited to small quantities (for less than 50 miles convey-
ance the quantity has to be less than 20,000 gpd).
It can readily be seen that for the distances and quantities investi-
gated in this study, pipelining is the most economical conveyance method,
particularly when compared to the combined costs of preconcentrating plus
a haul. Hauling is therefore not considered to be a realistic alternative
to the other waste disposal methods.
70
-------
1000
100
•tiiiii nun in iihiiiiiniiiiiiiiiiiiiiiiiiii ii iiiiiiiiiiini i mil iiimi^
HORIZONTAL PIPELINE
CONVEYANCE DISTANCE
MILES
1.0 10
DAILY PRODUCTION, Q. 1000 GPD
FIGURE 17. COST SURFACE FOR CONVEYANCE: PIPELINE, TRUCK AND RAIL $/1000 gal.-mile)
100
1000
-------
Brine Desulfation
Purpose and Concept: Brine desulfation is one possible step in the
renovation of wastewater, prior to desalinization by electrodialysis or
reverse osmosis. The only concern of the study itself is ultimate dis-
posal of the brine waste from the quaternary treatment. However, because
the desulfation process will affect the quality and quantity of this ulti-
mate waste, it is necessary to analyze its effect. The motivation for
such consideration is the potential advantage to be gained by removal and
byproduct recovery of the sulfates initially present in the water.
Desulfation techniques have been considered for use as a pretreat-
ment before desalting seawater by multistage evaporation. Since sulfates
cause scale production, the advantages are clear. Higher temperature
operation of the evaporators is possible, as is longer duration of opera-
tion without shutdown because of the lower rate of scale buildup. Sec-
ondly, advantages result from the production of marketable byproducts,
such as sulfuric acid and caustic soda.
Similar potential advantages can be analyzed for applicability to
wastewater renovation processes. Certain disadvantages may also be
present in this case that do not arise in the desalinization of seawater,
in addition to known disadvantages.
Conclusions; The extreme toxicity of barium makes it illegal and
unfeasible to use the desulfation process in the water renovation system.
The other factor which has been considered is the byproduct recovery.
Whether the byproduct has any value depends on whether it can compete
on the local market. It is estimated that 800 tons/day of ^804 should
be produced to be of any competitive value. The largest water renova-
tion plant of 100 mgd could produce only about 100 tons/day of ^304 as
a byproduct. This is not nearly enough to result in any byproduct credit.
The smaller plants of 10 mgd and 1 mgd produce correspondingly smaller
amounts of ^804. Therefore, not only is the desulfation process imprac-
tical from the standpoint of barium toxicity, but also it would not even
be economical to use on this project were barium not present. Thus, the
disadvantages greatly outweigh any of the advantages that can be gained
from use of the process.
A Flow Diagram of the Sulfate Removal Process is shown in Figure 18.
72
-------
NATURAL GAS
COAL
f- -i
1 J
• 1
ROASTING
1
•
LEACHING
MAKEUP BaS04
WATER
BaS04 CAKE
U-—
RESIDUE TO WASTE-*-
FILTRATION
Ba(OH)2« Ba(HS)2
SOLUTION
ION EXCHANGE AND SULFATE PRECIPITATION
SODIUM CARBONATE AND
SULFUR RECOVERY
BARIUM LOADING
NaOH-NaHS SOLUTION
BARIUM RESIN
BARIUM ELUTION AND
SULFATE PRECIPITATION
SODIUM RESIN WASTE
C02
CARBONATION
BaS04 AND
BRINE SLURRY
I CARBON TREATED
SECONDARY SEWAGE
J EFFLUENT
8501000 TDS
THICKENING AND FILTRATION
BaS04
CAKE
J
DESULFATEDFEEDTO
E.D.OR R.O. PROCESS
NaHC03
H2S
TO SULFUR OR
H2S04
CONVERSION
TO Na2C03
RECOVERY
FIGURE 18. SULFATE REMOVAL PROCESS, FLOW DIAGRAM
73
-------
Direct Contact Oil-Water Evaporation
Purpose and Concept; A Multistage Flash-Vertical Tube Evaporator
plant would be used as the solidifying stage of a waste disposal plant
with effluent brine from the tds removal step as the influent or feed
brine to the evaporator. The evaporator would concentrate the brine
to dryness, forming a filter cake plus distilled (product) water.
In order to produce the proposed filter cake, while avoiding the
inherent problems of scaling and corrosion present in an evaporator,
a conceptual process utilizing an oil-brine mixture as the influent
feed to the evaporator has been investigated. (See Figure 19 on the
following page.) In this process, fuel oil and waste brine are mixed
and pumped through the condenser section of the evaporator, absorbing
the latent heat of the flashing mixture as it proceeds up through the
evaporator train. The oil-brine mixture goes to the brine heater where
the mixture is heated above the saturation temperature of the first
evaporator stage. The oil-brine mixture then flows through the flash-
ing section of the evaporator, becoming the flashing mixture. In the
last stage of evaporation the last of the water is removed, and the
solids are carried in suspension by the oil.
The water vapor produced in each stage is condensed on the stage
tube bundle, preheating the feed oil-brine mixture. The condensate
is removed as product water.
The effluent brine-solids mixture from the last stage is fed into
an oil-solids separator producing a filter cake containing the solids
and some residual oil. Makeup oil is added to the remaining clean oil
and recycled for mixing with the influent brine, thereby completing the
cycle.
The caked solids are fired in a moving grate steam generator, and
the heat produced is used in the brine heater. The slag is carried
away for disposal.
Technical Piscussion; A feasibility study has been made of the use
of oil to heat brine by direct contact in a multistage flash evaporator
plant. The plant was assumed to have 16 stages, evaporating equal amounts
of brine per stage. Flow rates of 800,000 Ib/hr/ft of width were assumed.
Oil flow rates into the cold end condenser section were taken as six times
the brine flow rate. The oil and brine were assumed to be thoroughly
mixed before entering the evaporator.
The required length of two stages was calculated for the highest
temperature stage and the low temperature stage.
74
-------
INFLUENT BRINE
DRY SOLIDS ^,
EFFLUENT
DISTILLATE TO
WASTE
OIL-SOLIDS
SEPARATOR
CAKED SOLIDS
FIGURE 19. DIRECT CONTACT OF OIL-WATER EVAPORATION
-------
Very little data is available on the heat transfer characteristics
of direct contact systems. A summary and bibliography applied to the
design of a direct contact saline water conversion plant was published
by Wilke, Cheng, Ledesma and Porter, 1963.
The advantages of direct contact heat transfer over processes using
metallic surfaces are:
No reduction of heat transfer due to scaling
Simplicity of design
Closer temperature approach between the fluids for equivalent
heat transfer
On the other hand, the disadvantages of direct contact systems
include:
The need to handle separate and circulate large volumes of
two fluids
High pumping costs
Large fluid inventory
Product contamination with oil
Results: Using properties of oil-water mixtures computed for a
mixture of 6 parts oil by weight to 1 part brine and the usual correla-
tion equations for heat transfer under turbulent conditions through
tubes, we computed the inside tube heat transfer coefficient. Since
the resistance of the tube wall and of the condensing vapor (h0~2000)
is quite small, the inside coefficient calculated is close to the over-
all clean coefficient. The length of stage required under boiling
conditions, assuming reasonable boiling coefficients was calculated
as 400 feet which is clearly too long to be practical. The need for
packing along the floor of each stage to increase contact area and re-
duce stage lengths is apparent if the system is to work at all. The
paucity of data on evaporation in packed evaporators particularly for
multi-component 2-phase flow makes it difficult to predict the amount
of packing required.
Conclusions: The use of multistage flash evaporators with direct
contact heat transfer between oil and water for waste disposal does not
seem feasible. The length of each stage appears to be excessive and
the process too questionable for practical purposes.
76
-------
Electrodialysis With Ion-Specific Membranes
This process is one of the methods being used for partially demin-
eralizing water. Basically, the process involves using an induced
electric current across a cell containing saline water to separate
cationic and anionic components from the water. Cations migrate toward
the negative electrode, and anions migrate toward the positive electrode.
Cation and anion permeable membranes are placed alternately between the
electrodes; ions will concentrate in alternate passages between the mem-
branes and become more dilute in the intervening passages (see Figure 20).
Pretreatment of the secondary effluent feed stream to the electrodialyzer
would be lime coagulation and softening followed by carbon adsorption.
The pH of the concentrate stream from electrodialysis unit is 4.0.
This would have to be neutralized to a pH of 7.0 with soda ash in order
to establish a minimum requirement for further post-treatment before
being fed into an evaporator. The simplest post-treatment possible is
to have the electrodialyzer act as its own softening and conditioning
plant for both the concentrate stream and the dialyzate or product stream.
However, a modified membrane that is permselective for univalent cations
must be used. Seawater concentration plants in Japan use such membranes
for concentrating sodium chloride from seawater up to 15% brine that is
fed directly to crystallizing evaporators (Yamane, '69). The effluent
brine from this kind of electrodialyzer would require only pH adjust-
ment before being fed into an evaporator and could also be concentrated
all the way to saturation with sodium chloride and sulfate without
scaling. The total hardness of the lime-treated influent stream for
the electrodialysis unit is left in the dialyzate, or product water
stream, and amounts to about 65 mg/1 as calcium carbonate. This mini-
mum hardness is required to render the product water non-aggressive.
The concentrate, or brine stream, is softened, because only univalent
cations are able to pass through the permselective membrane.
The effluent brine from the electrodialyzer concentrated to 7000
mg/1 would be suitable for a non-scaling feed to the multistage flash
evaporator plant developed in other parts of this report, and would
allow the evaporator to concentrate to 10% tds at the costs for product
water shown. In fact, use of an ion-specific electrodialyzer on secondary _
sewage effluent is equivalent to the basic assumption involved for calculating
the evaporator costs.
Alternately, the effluent brine if concentrated to 10% or 15% by
the electrodialyzer itself can go directly to ultimate disposal.
77
-------
RECTIFIER
I I
N
£
JJ
J
s
LU
Q
O
<
]
f '
A C
cc
UJ
O
•4
Q.
CO
u
2
8
_l
<
oc
(_
D
UJ
2
' '
DILUTE SPACER
1
N
A
CONC. SPACER
I
[
1 '
: WASTE
v
z
0
t-
, f
C A C i
u co
TING ANION - i
EMBRANE PAIR
V,
x,
x
X
X
X
^
1
x^
•>w.
X
^\
s
X
X
\
X
x.
^s
X
x
}
,p
•^
„ N
LJhFEt[
A-A
T
CONCENTRATE
MAKEUP
LU
<
DC UJ
^^
S^5
z%
8tt
ACID
TANK
/^^
L
CATHODE WASTE
CONCENTRATED WASTE
C - CATION PERMEABLE MEMBRANE
A - ANION PERMEABLE MEMBRANE
N - NEUTRAL SEMIPERMEABLE MEMBRANE
FIGURE 20. ELECTRODIALYSIS STACK
78
-------
EL PASO. TEXAS STUDY SITK
WATER SUPPLY AND POTENTIAL NEED FOR REUSE
The city of El Paso is located adjacent to New Mexico and across
the Rio Grande from Mexico. It is served by 6 major highways, limited
air service and four major railroads with two connecting lines in Mexico.
The elevation at El Paso is about 3750 feet. The El Paso district,
which includes all El Paso County, obtains its water from well fields
developed in the Hueco Bolson, La Mesa Bolson and in the river alluvium
of the Mesilla and lower Mesilla Valley area. The Hueco Bolson extends
from the Hueco Mountains on the east to the Franklin Mountains on the
west and into New Mexico on the north and Mexico on the south. The La
Mesa Bolson of the lower Mesilla Valley is on the west side of the
Franklin Mountains (see Figure 21) .
The total amount of water that Hueco Bolson and the El Paso River
furnish is 46 to 56 million gallons per day in El Paso. The water sup-
ply from the Hueco Bolson Basin consists of a lens of fresh water which
is floating on salt water. The eastern part of the basin is more saline
and is separated from the western part, which contains the fresh water
lens, for a distance of 10 to 15 miles.
The city of El Paso is 80% dependent on ground water and 20% on sur-
face water from the river for its municipal supply. The expected future
population of El Paso in the years 2000 and 2020 is 615,000 and 913,000,
respectively. The Texas Water Development Board has projected future
demands for water in El Paso as follows:
Projected Water Requirements to 2020
Total Water Demand (Millions of gallons/day)
Municipal water
Industrial water
Total
The annual recharge rate into the Hueco Bolson Basin averages 15
million gallons per day; withdrawals total 30 to 35 million gallons a
day, including the El Paso River contribution. The water tables are
constantly being lowered in the area. To solve this problem, water
could eventually be imported from the Mississippi River via the Texas
Southwest Water Plan, which is slated for sometime in the future.
79
-------
oo
o
DONA ANA CO.
DISPOSAL AREA
V WHITE SANDS
SOUTH FRANKLIN
MOUNTAINS
EL PASO
FORTBLISSINTERNATIONAL AIRPORT
DISPOSAL AREA
UNDERGROUND AQUEDUCT
IMEW MEXICO
UNITED STATES DONA ANA
HEUCO WELLS
SAN ELI2ARIO
MILES
EL PASO REGION
FIGURE 21. EL PASO REGION
-------
The City of El Paso provides its own municipal and industrial
water supply. The water production facilities have a capacity of 160
MGD. Maximum daily use is 90 million gallons, and annual use is 16 7
billion gallons. The average per capita daily use is 165 gallons.
CONSIDERATIONS AFFECTING BRINE DISPOSAL
El Paso has two water treatment plants, one for coagulation and
filtration of Rio Grande River, the other one for chlorinating ground
water.
Sewage treatment is accomplished in three plants utilizing high
rate trickling filters to treat the sewage. Total effluent is about
18.2 MGD. Most of the influent to these facilities is from municipal
and industrial wastes. There is no municipal reuse of the treated
effluent, which ultimately discharges into the Rio Grande.
SPECIFIC BRINE DISPOSAL METHOD (See map of area - Figure 21)
Quaternary Treatment Waste Brines
Assuming that the reclaimed water from the treatment is recirculated
and used by the city, this can be combined with all other municipal run-
offs under existing water right statutes and returned to the Rio Grande
River. By this process no salt beyond that which results from municipal
use is added. Under the existing state legislation, this constitutes
a legitimate use of water, and so it would be permissible to dump the
entire brine effluent from the quaternary treatment into the Rio Grande
River at El Paso even though this really evades the pollution problem.
At 10 mgd of brine, the tds of the river would, however, exceed 3000 mg/1
during the winter months. This would impose undue hardships on downstream
users. In addition to the moral or ethical arguments against this disposal
method there is another consideration. Laws do change so that what might
be legal one day is not legal the next. This is particularly true with
laws concerning environmental protection.
More promising alternatives should be considered: Solar evapora-
tion in lined ponds and unlined ponds, disposal by means of deep well
at zero well-head pressure, solar evaporation and pipelining combina-
tion, and pipelining to a disposal area. For purposes of this study
this section presents cost comparisons for the above alternative ^ waste
trates" t waste brines to 7000
81
-------
Deep-Well Disposal
Preliminary geological investigations indicate that the salt side
of the Hueco-Bolson Basin, 15 miles to the east of the city, could be
used as a disposal zone. The eastern part of the basin is more saline
and is separate from the western part, which contains the fresh water
lens, by a distance of 10 to 15 miles. There is little likelihood at
this distance that the injected waste brine would ever contaminate the
fresh water supplies in the western side of the basin. Thus, this is
a favorable site for deep well injection as an alternative for waste
brine disposal. Injection would be made at about 3500 feet. The perme-
ability at that depth is sufficient to allow zero well head pressure to
introduce the brine. A profile of the basin is shown in Figure 22.
The cost caluclation for this alternative is based on the following
data:
porosity = 30% vol of pore/total vol
height of formation = 100 feet
electrical power cost = 12 mills per kwh
fixed charge rate = 0.05, 0.10
depth of well = 3500 ft
projected life = 30 years
@ 200,000 gpd per well
Brine concentration = 7000 mg/1
From this the deep well injection cost $/Kgal. is:
Total Unit
Capacity Disposal Cost Additional OME Disposal Cost
MGD $/Kgal. Cost $/Kgal. $/Kgal.
FCR=.1Q FCR=.Q5 .10 FCR .05 FCR
0.1 0.151 .075 0.135 0.282 .210
1.0 0.10 .051 0.065 0.165 .116
10.0 0.106 .054 0.054 0.160 .108
Solar Evaporation
In many arid areas it is possible to evaporate waste brine to dry-
ness in properly lined solar evaporation ponds. El Paso is considered
one of the most suitable areas for this process of waste brine disposal.
The city owns some 3,000 acres of land which could be used for solar
evaporation and, in fact, they are now being used for oxidation ponds.
This land was acquired by the city in order to obtain water rights to
the surface and ground water for municipal needs. Thus, the water rights
of the land itself are expropriated and this land cannot, therefore, be
cultivated for farming.
82
-------
HUECO-BOLSON BASIN
15(10)6ACRE/FT RECHARGE
DEEP WELL DISPOSAL
ZERO WELL HEAD PRESSURE GAUGE
WEST
3500 FT
oo
EAST
FIGURE 22. DEEP WELL INJECTION AREA OF HUECO-BOLSON BASIN
-------
The costs presented in this process are based upon the assumption
of the following:
Waste brine concentration = 7000 mg/1
Total evaporation rate = 105 in./yr
Annual rainfall rate = 12 in./yr
Annual net evaporation rate = 93 in./yr
Lining Cost:
30 mils (PVC) = $0.1322/ft2 based on 60«?/lb
Land Cost: $250/acre
Dike Cost = $1.00/yd3 (including equipment, labor and material)
Liner Cover = $0.4/yd3 (including equipment, labor and material)
Stripping Land Cost = $100/acre
From this the solar evaporation costs $/Kgal. at 5% and 10% fixed charge
rates and liner thicknesses are shown in Table 10.
TABLE 10
DISPOSAL COST BY SOLAR EVAPORATION
EL PASO, TEXAS
Brine
Quantity,
mgd
0.1
1.0
10.0
Fixed
Charge
Rate, %
10
5
10
5
10
5
Unlined
Ponds ,
$/Kgal.
0.11
0.055
0.047
0.024
0.026
0.013
Lined Ponds
(30 mils)
$/Kgal.
0.443
0.22
0.366
0.183
0.342
0.171
Lined Ponds
(20 mils)
$/Kgal.
0.35
0.175
0.274
0.137
0.25
0.125
Lined Ponds
(10 mils)
$/Kgal.
0.26
0.13
0.184
0.92
0.16
0.08
Pipeline Conveyance
Fifteen miles to the north of the city, the United States Army owns
the White Sands proving grounds, both in New Mexico and Texas. This is
waste land with no useful aquifers beneath it. Thus, if the Army's per-
mission could be obtained, waste brine from a quaternary treatment could
be pipelined over to this area and dumped on the ground, where it would
create an artificial salt lake bed. The gross annual evaporation in the
area is over 100 inches per year, while the annual rainfall is so light
that any salt deposited on the surface would remain on the surface because
there is no net run-off from the area. In case the Army will not allow
waste brine to be dumped over the area of White Sands, it is still feasi-
ble to pipeline waste brine to some other available waste land about 50
miles away from the city of El Paso.
84
-------
The costs developed for pipeline conveyance disposal alternative
are based on the following data: *xternative,
Fixed charge rate = 0.05, 0.10
Power cost = 12 mills/kwh
Pumps and accessories cost = $207.5/hp
Installed pipe cost = $10.431/ft
(Basis 12" diameter pipe)
Distance of conveyance =15, 50 miles
Right of way cost = $5,000/mile
Pipeline conveyance cost in $/Kgal. from El Paso to White Sands at a
distance of 15 miles and 50 miles to ultimate disposal site is given
in Table 11.
TABLE 11
PIPELINE CONVEYANCE COSTS IN S/KGAL.
Brine
Quantity
mgd
0.1
1.0
10.0
Pipe
Size
(In. ID)
3
8
24
Fixed
Charge
Rate,%
10
5
10
5
10
5
15 Miles
Pipeline
Conveyance
Cost,$/Kgal.
0.47
0.27
0.19
0.104
0.07
0.04
Right of
Way Cost
$/Kgal.
0.205
0.102
0.020
0.01
0.002
0.001
50 Miles
Pipeline
Conveyance
Cost,$/Kgal.
1.575
0.903
0.626
0.346
0.24
0.133
Right of
Way Cost
$/Kgal.
0.684
0.342
0.068
0.034
0.007
0.003
Combined Process - Solar Evaporation and Pipelines
In view of the fact that the accumulation of salt in solar evaporation
ponds, lined or unlined, is frowned upon and in some cases prohibited, the
best alternative is the combined process of solar evaporation and pipelines.
Waste brine would be concentrated in the ponds, thus reducing the volume
of waste brine to be transported by pipelining to some waste land for dumping.
Waste brine from a quaternary treatment plant could be pumped from El
Paso to available lands about 15 miles from the city. There waste brine
would be concentrated in lined solar evaporation ponds and then by pipe-
lining the waste brine from the pond would be transported to some available
waste lands at a distance of about 50 miles for ultimate disposal by dumping.
85
-------
Costs developed in this alternative are based on the following data:
Cost of pipe (1 ft diameter) = $10.431/ft
Cost of pump and standby generator = $207.5/hp
Fixed charge rate = 10% and 5%
Cost of power = 12.0 mils
Cost of right of way = $5,000/miles
Length of pipeline =50 miles
Annual net evaporation rate = 93 in./yr
Cost of liner: 2
30 mils (PVC) lining = $0.132/ft based on 60C/lb
Cost of land = $250.OO/acre
From this the solar evaporation and pipelines combination costs $/Kgal.
for various liner thicknesses are shown in Table 12.
CONCLUSIONS AND RECOMMENDATIONS
Any of the methods for ultimate disposal of waste brine, discussed
above, would have to alleviate pollution of natural resources, in order
to be acceptable in the area of El Paso. The advantages and disadvan-
tages of these methods depend upon the climate and geology of the dis-
posal area as well as the concentration of the brine. For deep well
disposal, pH adjustment is required to render the brine compatible with
the soil.
Based upon ultimate disposal of 10 mgd waste brine at 7000 mg/1,
using a fixed charge rate of 7%, the following are recommended:
With regard to the total costs, the most economical, but undesirable,
brine disposal scheme is to go directly from the quarternary treatment
plant into the river. The brine resulting from electrodialysis or reverse
osmosis can be combined with all other municipal runoffs under existing
water right laws and returned to the Rio Grande River at no disposal cost.
A more desirable economical disposal scheme is to pipeline waste
brine to White Sands, 15 miles from El Paso. No net annual runoff and
no useful aquifers occur in the area, and so the cost of disposal there
by dumping on the ground is simply the pipelining cost. This cost is
5.20/Kgal. brine handled, excluding right-of-way.
Deep well disposal of waste brine into the east end of Hueco Bolson
basin is also favorable. Waste brine from a quarternary treatment plant
will gradually displace, upward and westward, the natural fresh water
ground supply in the area. Cost of this scheme is 13
-------
TABLE 12
UNIT COST OF DISPOSAL BY EVAPORATION PONDS AND PIPELINE COMBINATION, EL PASO. TEXAS
EL PASO, TEXAS
Brine
Quantity
mgd
0.1
1.0
10.0
Fixed
Charge
Rate
%
10
5
10
5
10
5
Lined Ponds
(30 mils)
Pipeline
Concentration
20
20
20
20
t
1.0
1.0
Disposal
Cost,$/Kgal.
0.677
0.353
0.446
0.229
0.24
0.134
Lined Ponds
(20 mils)
Pipeline
Concent ration
20
20
20
20
1.0
1.0
Disposal
Cost,$/Kgal.
0.589
0.309
0.358
0.185
0.24
0.134
Lined Ponds
(10 mils)
Pipeline
Concentration
20
20
20
20
20
20
Disposal
Cost,$/Kgal
0.504
0.266
0.273
0.142
0.190
0.097
Additional
Cost for
Right of Way
0.685
0.342
0.068
0.034
0.007
0.003
-------
Solar evaporation in El Paso is considered one of the most suitable
disposal methods. The annual evaporation rate is over 100 inches while
the average annual rainfall is light. The City owns some 3000 acres
which could be used. Lined ponds would cost between lie and 24C per
Kgal. of brine evaporated, with liner thickness of 10 to 30 mils.
Other alternatives for waste brine disposal are as follows:
If the area of White Sands is prohibited as a disposal area, it
is still feasible to pipeline waste brine to available waste land
about 50 miles away from the city of El Paso. This cost is 17.6c/
Kgal. excluding right-of-way.
If the accumulation of salt in lined solar evaporation ponds is
prohibited, a combined process of solar evaporation and pipelines
would best fit in this case. This cost varies from 13.4
-------
TUCSON. ARIZONA STUDY SITE
WATER SUPPLY AND POTENTIAL NEED FOR REUSF.
The City of Tucson is located in Pima County, Arizona between the
Tortolita and Tucson Mountains on one side and the Santa Catalinas on
the other. The Santa Cruz River flows through the city, entering from
the south, and leaving to the northwest. The northwest passage consti-
tutes a subterranean shelf, over which all subterranean waters must flow
to leave the valley. Sparse rainfall in the basin constitutes the main
source of water at present, since the river is usually a dry bed. The
city takes its water supply from wells in the valley. Some recharge
of the underground supply occurs as a result of crop irrigation, utiliz-
ing the municipal wastewater, but this is insufficient to stabilize the
water table, which has been declining for many years. Reuse of avail-
able supplies by irrigation is almost 100%.
To offset an expected substantial population growth in the near
future, the city expects to import some 300 mgd of Colorado River water
from Parker Dam by the year 2,000, which together with anticipated
reuse and recharge will stabilize the water table at that time. The
Colorado River water by then is expected to contain 1,000 mg/1 tds,
which, together with an expected 300 mg/1 tds added by a single city
use must be removed from the valley, either by irrigation return flow
to the already contaminated Gila River, or by desalination in order to
prevent a major buildup of salt in the ground water supplies.
CONSIDERATIONS AFFECTING BRINE DISPOSAL
Tucson has a sewage plant effluent capacity of 36 mgd. The in-
fluent to this facility is primarily municipal waste with very little
industrial waste, which has picked up only 175 mg/1 tds as a result of
the city use. The effluent, after primary and secondary treatment, is
used to irrigate cotton and wheat crops in the valley. A small amount
of irrigation runoff, together with any bypassed sewage effluent enters
the Santa Cruz River bed, ultimately reaching and drying up in the Gila
River Most of the irrigation water, however, percolates underground
to serve as recharge for the reservoir. As a consequence, the nitrogen
content of the ground water has been increasing recently. To prevent
this buildup, the city is installing an anaerobic denitrificatxon facilxty
as a tertia^ sewage treatment step. Salt buildup in the ground water
a permanent solution.
89
-------
SPECIFIC BRINE DISPOSAL METHODS (See map of area - Figure 23)
Injection Wells
The Tucson basin is composed of sandy alluvium, the depth of which
has never been measured. One well, drilled to 2,000 feet, has produced
fresh water. The permeability of the soil is excellent. Beneath the
useful strata, it is surmised that salt water exists, probably at about
3,000 feet depth. Injection of brine at about 3,500 feet depth would
not be expected to create deleterious effects for a relatively long
period of time. It is thought that any salt added to the aquifer would
remain at the bottom, and would serve to raise the water table of use-
ful water, which would float as a lens over a basin of salt water.
The costs for this disposal method are based on the following data:
Depth of well = 3500 feet; height of formation 10 feet
Porosity, P = 30% (void volume/total volume)
200,000 gpd/well; electrical power cost 12 mills/kwhr
Project life = 30 years; fixed charge rates .05 and .10
Capacity
MGD
0.1
1.0
10.0
Disposal Cost
$/Kgal.
10% FCR
0.1506
0.0996
0.1062
5% FCR
.075
.051
.054
Additional
Oper. & Maint.
Cost
0.1350
0.0652
0.0540
Total Cost
$/Kgal.
5% FCR
0.210
0.116
0.108
10% FCR
0.2856
0.1648
0.1602
Pipelining
Fifty miles to the East of Tucson is a closed salt basin, known
as the Wilcox Playa. In the middle of this basin is a sulfur lake
formerly used as a health resort.
It is feasible to pipeline waste brine to this area. This would
not require soil preparation or liners, since the area cannot be further
contaminated by additional salts.
The net effect of accumulating salt in this area would be to create
a new great salt lake basin, which might ultimately be mined for salable
salts.
The costs that have been developed for this disposal method, were
based on the following data:
90
-------
GRAHAM OCX
COCHISE CO.
-------
Annual fixed charge rate = .05 and .10
Electrical power cost = 12 (mills/kwh)
Pump and accessories cost = 207.5 ($/hp) _
Installed pipe cost = 10.431 ($/ft (for 12" diameter pipe))
Conveyance distance = 50 (miles)
Right-of-way cost = 5000 ($/mile)
Capacity
MGD
0.1
1.0
10.1
Optimized Pipe
Size, In.
3
8
24
Conveyance
Cost,$/Kgal.
10% FCR
1,576
0.626
0.240
5% FCR
.903
.346
.133
Right-of-Way
Cost,$/Kgal.
0.684
0.068
0.007
Total
Cost,$/Kgal.
5% FCR
1.587
0.418
0.140
10% FCR
2.260
0.694
0.247
Solar Evaporation Ponds
The net evaporation rate in the Tucson area is very high. Based on
a gross evaporation rate of 95 in./year and a rainfall of only 5 in./year,
the net evaporation rate is 90 in./year.
With such high evaporation rates, solar evaporation ponds are very
attractive.
There is limited land available writhin the valley, which could be
used for solar evaporation ponds, but linings would be mandatory so that
accumulated salt left in these after abandonment could never contaminate
the useful ground water supply beneath.
The costs developed for this disposal method have been based on
the following data:
Net evaporation rate
Annual fixed charge rate
Cost of land
Dike fill cost
Liner cover cost
Stripping land cost
90 (in./year)
.10 and .05
250 ($/acre)
1.00 ($/yd3)
0.40 ($/yd3)
100 ($/acre)
PVC liner costs based on 60$/lb have been developed for three dif-
ferent thicknesses of the liner - 10 mils, 20 mils, and 30 mils.
30 mils (PVC) lining = $0.132/ft2
The costs have also been developed for unlined solar ponds, which,
however, are not recommended for this site.
92
-------
For aesthetic as well as economic reasons salt and concentrated
brine cannot be allowed to accumulate indefinitely at solar pond loca-
tions within the Tucson Valley itself. These would have to be hauled
or pipelined away to a suitable non-leaching sump, such as the Wilcox
Playa 50 mxles to the East. Therefore, at Tucson, solar evaporation
must be considered as a p re-con cent rating technique preceding ultimate
disposal and not as a complete disposal method in itself Either the
costs of a dry haul or of a pipeline must be added to the solar pond
costs to obtain the complete costs of ultimate disposal.
The solar evaporation costs $/Kgal. at 5% and 10% fixed charge
rate and liner thickness are shown in Table 13.
TABLE 13
UNIT DISPOSAL COST BY SOLAR EVAPORATION, TUCSON. ARIZONA
Brine
Quantity
mgd
0.1
1.0
10.0
Fixed
Charge
Rate,%
10
5
10
5
10
5
Unlined
Ponds
$/Kgal.
0.11
0.055
0.048
0.024
0.027
0.014
Lined Ponds
(30 Mils)
$/Kgal.
0.455
0.228
0.378
0.189
0.354
0.177
Lined Ponds
(20 Mils)
$/Kgal.
0.36
0.18
0.283
0.141
0.258
0.13
Lined Ponds
(10 Mils)
$/Kgal.
0.267
0.133
0.19
0,095
0.165
0.083
93
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Solar Pond and Pipeline Combination
The immediate problem facing the city of Tucson is nitrogen buildup
in the ground water supplies, due to irrigation with secondary sewage
effluent. Preliminary results of experiments with algae ponds in the
area indicate that in these ponds the pH of the effluent builds up to
8.2, and that at this pH, considerable nitrogen is released into the
air in the form of ammonia. Conceivably, the residual nitrogen which
is in the form of nitrates could next be removed by anaerobic denitri-
fication, down to an acceptable level which could be utilized by the
roots of the plants under irrigation. More extended tests of algae
ponds in other areas, however, have demonstrated that continuous re-
moval of ammonia nitrogen is possible if, and only if, the algae bloom
is continuously harvested; otherwise, decay of the accumulating algae
will produce a serious problem. The overall costs of the operation
usually turn out to be quite high.
Quaternary treatment of the sewage effluent so as to remove plant
nutrients offers a way out of this quandary. The quaternary treatment
considered under the ground rules of this study is electrodialysis,
preceded by lime clarification and carbon adsorption. A study of the
composition of the sewage effluent from the city of Tucson, made herein
in connection with ion-exchange pretreatment for Multistage Flash Evapo-
ration, has shown that lime clarification is sufficient to remove the
phosphate nutrients. Following this step, the electrodialysis process
can be arranged stagewise, using permselective membranes that are specific
for monovalent ions (Yamane '69), such as ammonium and nitrate ions, so
that these ions, instead of winding up in the renovated wastewater, will
be concentrated in the brine stream. As the brine stream is to be pumped
out of the area and into the Wilcox Playa Basin, this procedure allows
a portion of the nitrogen pollution problem to be solved at no additional
cost, along with the main salt pollution problem.
There is an additional saving to be made over pipelining away the
waste brine from the electrodialysis unit in the "as received" condi-
tion. The best operation of the electrodialyzer will result in a brine
that has been concentrated only about 10 times, to about 7,000 mg/1.
This can be preconcentrated before pipelining to any desired degree
by the use of local lined solar evaporation ponds. The computer pro-
gram which has been developed for this purpose is useful to determine
for the local site conditions whether preconcentration is economical.
For the three design capacities of this study, the costs developed
for the combined solar preconcentrating and pipeline disposal method
by means of the computer are shown in Table 14 and have been based
upon the same data as the solar pond and separate pipeline disposal
methods.
94
-------
TABLE 14
UNIT COST OF DISPOSAL BY EVAPORATION PONDS AND PIPELINE COMBINATION, TUCSON, ARIZONA
Brine
Quantity
mgd
0.1
1.0
10.0
Fixed
Charge
Rate,%
10
5
10
5
10
5
Lined Ponds
(30 Mils)
Pipeline
Concentration
20
20
20
20
1.0
1.0
Disposal
Cost,$/Kgal.
0.689
0.359
0.457
0.234
0.24
0.134
Lined Ponds
(20 Mils)
Pipeline
Concentration
20
20
20
20
1.0
1.0
Disposal
Cost,$/Kgal.
0.599
0.314
0.367
0.189
0.24
0.134
Lined Ponds
(10 Mils)
Pipeline
Concentration
20
20
20
20
20
20
Disposal
Cost,$/Kgal.
0.510
0.27
0.278
0.145
0.195
0.100
Additional
Cost for
Right-of-Way
$/Kgal.
0.685
0.342
0.068
0.034
0.007
0.003
VQ
Ln
-------
CONCLUSIONS AND RECOMMENDATIONS
Based upon ultimate disposal of 10 mgd waste brine at 7000 mg/1,
using a fixed charge rate of 7%, the following are recommended:
As a temporary measure until imported Colorado River water from
Parker Dam is available, deep well disposal of waste brine into the
Tucson basin at 3500 ft would cost 13(?/Kgal.
Another economical disposal scheme is to pipeline waste brine
into a salt lake at Wilcox Playa, fifty miles to the East of Tucson.
This cost is 18
-------
DENVER. COLORADO STUDY SITE
WATER SUPPLY AND POTENTIAL NEED FOR REUSE
inn °f DenVer 1S located ln Jefferson County, Colorado, some
100 miles south of Wyoming and approximately 100 miles north of Pueblo
Interstate highways 25, 49, 70, 80, 85, 87, 287 and 285 converge in
Denver .
With regard to the water supply, the largest contribution to
Denver's available water is the Blue River Diversion System. The sys-
tem comprises the huge Dillon Dam and Reservoir with a capacity of 1/4
million acre feet annually, almost equal to that of all Denver's other
reservoirs put together, and the 23 mile long Harold D. Roberts Tunnel
under the Continental Divide, the world's longest underground tunnel.
Water first came to Denver through the Roberts Tunnel on July 17, 1964.
In 1968 this and other water supplies yielded more than 190 mgd of water,
with 15 mgd being added to storage.
The transmountain storage facilities furnish over half the water
used in Denver. The metropolitan area itself has small water utilities
utilizing shallow wells and deep well pumping. Surface runoff is the
main supply. Agricultural ditches, which use the majority of the waters,
furnish drinking water by appropriation. The South Platte River itself
is presently overappropriated.
Projections of water requirements for Denver yield an estimate of
municipal and industrial water for 2008 about three times as great as
for 1969. In order to provide for these needs, it has been recognized
that desalting should be considered as one of the possible sources of
future supply. However, according to the Denver Board of Water Com-
missioners, studies indicate that new water supplies primarily from
the Colorado River System will be available. Coupled with transmountain
water, a small additional supply through purchase of water rights should
adequately supply the projected municipal and industrial needs to the
year 2008. Projection of future demands for water in Denver is as
follows :
Projected Water Requirements to 2008
Total Water Demand (MGD)
1970 1980 1985 1990 1995. 2008
Treated Water
Raw Water
Subtotal
Subtotal + 7.5% 271<6 32g>4 400>1 530.5
Operating Loss lyJ.J -^
97
-------
The current and expected future growth trend of the population of
Denver is as follows:
Current and Prelected Population to 2008
1968 1988 2008
1,043,200 1,719,000 2,404,300
With regard to rates charged for water, there are presently 90,000
flat rate residences that were using water prior to metering. The
balance of the residences are now metered.
CONSIDERATIONS AFFECTING BRINE DISPOSAL
The City and State laws forbid the reuse of water of the South
Platte River because the interest of the people has always been in
pristine quality water. The existing legislation, however, did not
anticipate transmountain water, furnished through the aqueduct from
the Colorado River supply near its source, the Blue River. Thus, the
only water that can be considered for reuse is Colorado River water.
Even the reuse of Colorado River water may require court interpreta-
tion, since existing legislation is ambiguous.
The South Platte River water and ground water contain 150 mg/
liter tds average, while for the diverted water from the Colorado
River there are only 50 mg/1 tds, a negligible amount. The consumption
in 1968 was 148 mgd, of which half came from the Colorado River. Thus,
about 75 mgd would be the amount that could be utilized in a direct
water reuse scheme, if the reuse of Colorado River water is determined
to be lawful. Projected to 197 mgd reuse for the future, this would
involve a disposal scheme for 10 mgd of wastewater containing about
7000 mg/1 tds from the reuse, provided salt removal by electrodialysis
or reverse osmosis is used. This would require, in turn, a makeup from
the Colorado River of only 10 mgd.
A smaller wastewater renovation plant of 100 mgd capacity has
already been proposed for Denver. Under a study being pursued by the
University of Colorado, such a plant could be located at the North
Metro Filter Station, 104th Avenue near the South Platte River, where
acreage already owned by the City could be utilized.
Hypothetical 197 MGD Water and Salt Balance for Denver, Colorado
based on Renovating a Portion of its Wastewater for Reuse
The schematic diagram, Figure 24, illustrates a reasonable concept
of water renovation. It covers most of the situations which would be
met under a number of different circumstances. The bypass line would
be needed in a situation where not much salt has to be removed from the
renovated water. It is not practical to run all of the water through
98
-------
SALTS ENTER ING
SEWER SYSTEM
@ 350 mg/l
(1)
(2)
(4)
CITY
I-
(5)
(6)
RENOVATED
WATER f
SAFETY
STORAGE TANKS
L
(3)
BYPASS LINE
(CLOSED)
(8)
•17)
W.W. TREATMENT
AND A.W.T.
(10)
H2S04
MATERIAL STREAMS
DESCRIPTION
1. PRISTINE WATER INPUT
2. TOTAL INPUT TO CITY
3. INPUT WATER WHICH DOES NOT ENTER SEWERS
4. TOTAL SEWAGE LEAVING CITY
5. STORM WATER AND INFILTRATION
6. WASTEWATER LOST OR NOT RECYCLED
7. WASTEWATER FED TO W.W. TREATMENT AND AWT
8. BYPASS OF SALT REMOVAL
9. BRINE DISCHARGED FROM SALT REMOVAL UNIT
10. RENOVATED WATER RECYCLE
11. CONCENTRATE STREAM FEED
12. CONCENTRATE STREAM RECYCLE
STREAM VOLUME, MOD
W
Q
V
q-Y =
s =
P
q-y + s-p =
n =
b
10
197
0
197
0
0
97
0
10
r (=q-Y + s-p-n-b) = 187
F = 10
C = 177
SALT CONCENTRATION
mg/l
Cw
C|
C|
Co
cr
Cf
115
500
500
850
850
7000
521
850
7000
99
-------
a reverse osmosis unit just to remove a small fraction of the dissolved
salts. It would be better to remove a large fraction and blend back
with renovated water. With electrodialysis, however, as used in this
study, a single stage will remove only up to half of the tds, and so
circulating all of the water through the electrodialysis unit turns out
to be the most economical method for influent concentrations of 1000 mg/1
or less, with the effluent concentration being controlled by the applied
voltage.
The addition of sulfuric acid to avoid carbonate scaling is nec-
essary with electrodialysis. This normally adds an increment of about
50 mg/1 in total dissolved solids as a result of the replacement of
carbonate by sulfate. No correction for this increment has been made.
The material balances for the representation as shown involve many
variables which cannot be fixed without reference to a specific location.
Consideration is given to the following simple case for Denver:
S = 0 (transpiration loss equals rainfall)
P = 0 (all wastewater is recycled)
n = 0 (no renovated water bypass desalting)
y = 0
Material balances may now be made.
Overall Water Balance;
W = y + b (1)
Overall Salt Balance;
W Cw + (q-y) (Co-C±) = y C± + b (^ (2)
Dividing both equations through by "b", we obtain
'
Eliminating ~ from equation 4 gives
b C -C. C -C
100
-------
A 197 mgd plant for waste renovation wit-v, +A
would increase the total water supply to 335 M^ ™™*1\ lf installed>
sufficient for the year 1990 without reauiH™ §Pd' Whi°h W°uld be
from the Colorado River than at present Dent T ^^ withdrawals
amounts than this in the future rrom th^ El^l ^ t0 US& larger
not popular in the western pa's of the state. DlVerSi°n SySt6m are
as follows a — -ter capacity of 287 mgd
Moffatt 63
South Platte 72,7
Blue River 151.3 (tributary of Colorado River)
287 mgd
The per capita consumption is steadily increasing primarily as a
result of the rising standard of living. The present 224 gpd per capita
is estimated to reach 255 gpd in the year 2000.
The use of transmountain Colorado River water in Denver area,
however, will not be without difficulties in the future. The people
in western Colorado are already objecting to this exportation because
the potential production of petroleum oil from oil shale is becoming
of increasing importance to the state's economy in the west. This pro-
duction requires forty to fifty barrels of water per barrel of oil pro-
duced for the purposes of extracting the oil from the shale. During
this use, a small portion of water is used for cooling, but the largest
amount is used in direct contact with the hot shale which contains 25
to 60 percent of oil by weight. The resultant water is highly contami-
nated with soluble material from the shale, notably sodium chloride and
bicarbonate. Thus, when oil extraction from this shale becomes opera-
tional in western Colorado, water supply and salt pollution problems will
arise there, and means must be found for augmenting rather than diminish-
ing the available supply of Colorado River water in western Colorado.
SPECIFIC BRINE DISPOSAL METHODS (See map of area - Figure 25)
Of the methods for ultimate disposal of brine, presuming that per-
mission can be obtained for reuse of water in the Denver area, the lined
solar evaporation pond and the combined process of forced and solar evap-
oration seem to be the only methods that would be acceptable to every
agency concerned. The use of deep wells for disposal, because of the
earthquake problem and of the direct correlation of frequency and in-
tensity of earthquakes with the rate of injection by the Denver Arsenal,
forecloses completely the possibility of well injection into the frac-
tured precambrian breccia stratum. Higher strata all communicate directly
with ground water in low lying areas outside of Denver and hence would
™t be sStable. A future possibility for limited storage of very con-
centrated brines would be hydrofracturing of some impermeable stratum
101
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COLORADO
SPRINGS
DISPOSAL AREA
PUEBLO
MILES
FIGURE 25. DENVER REGION
102
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outside the earthquake zone and sealing the brine permanently into the
cavity thus formed. Pipelining of brines to the ocean or the great
salt lakes is, of course, impossible. For purposes of this study, the
following cost comparisons for acceptable alternative waste brine dis-
posal methods at a capacity of 0.1, 1.0, and 10 MGD of brine are pre-
sented :
Solar Evaporation
The net annual evaporation in the vicinity of Denver is about 29
inches, while the average annual rainfall is 13 inches. In the Pueblo
area, some 100 miles south of Denver, the net annual evaporation rate
is much higher, 36 inches, while the annual rainfall is about the same,
12 inches. Thus, the alternatives compare solar evaporation costs in
lined ponds located immediately east of Denver, with costs of a pipeline
to Pueblo and solar evaporation east of Pueblo in a desert area.
The costs presented for these schemes are based upon the following
assumptions:
Waste brine concentration = 7,000 mg/1
Denver, Colorado
Annual evaporation rate = 29 in./yr
Annual rainfall rate = 13 in./yr
Pueblo, Colorado
Annual evaporation rate = 36 in./yr
Annual rainfall rate = 12 in./yr
Lining cost:
30 mils (PVC) = $0.1322/ft2, based on 60C/lb
Fixed charge rate = .05 and 0.10
Land cost - $250/acre
Dike cost = $1.00/yd3 (including equipment, labor and material)
Liner cover = $0.4/yd3 (including equipment, labor and material)
Stripping land cost = $100/acre
Basis for installed pipe cost - $W.431/ft (for 12" diameter pipe)
Power cost = 12 mills/kwh
Pumps and accessories cost - $207.5/hp
Distance of conveyance - 100 miles
Tne solar evaporation costs $/Kgal. ** various liner thicknesses
are shown in Table 15.
103
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TABLE 15
UNIT DISPOSAL COST BY SOLAR EVAPORATION
DENVER COLORADO
Brine
Quantity
mgd
0.1
1.0
10.0
Fixed
Charge
Rate,%
10
5
10
5
10
5
Unlined
Ponds
$/Kgal.
0.222
0.111
0.108
0.054
0.072
0.036
Lined Ponds
(30 Mils)
$/Kgal.
1.26
0.63
1.125
0.56
1.08
0.54
Lined Ponds
(20 Mils)
$/Kgal.
0.966
0.48
0.83
0.41
0.786
0.39
Lined Ponds
(10 Mils)
$/KgaL.
0.678
0.34
0.54
0.27
0.498
0.25
*PUEBLO. COLORADO
Brine
Quantity
mgd
0.1
1.0
10.0
Fixed
Charge
Rate,%
10
5
10
5
10
5
Unlined
Ponds
$/Kgal.
0.194
0.097
0.091
0.045
0.059
0.029
Lined Ponds
(30 Mils)
$/Kgal.
1.035
0.52
0.912
0.46
0.874
0.43
Lined Ponds
(20 Mils)
$/Kgal.
0.796
0.40
0.674
0.337
0.635
0.32
Lined Ponds
(10 Mils)
$/Kgal.
0.564
0.28
0.442
0.22
0.403
0.20
*Add 100 miles (12 Mills/Kwhr) pipeline cost from Denver, excluding
right-of-way:
Brine Quantity
mgd
0.1
1.0
10.0
Fixed Charge
Rate, %
10
5
10
5
10
5
Pipeline Cost
$/Kgal.
3.15
1.81
1.25
0.69
0.48
0.26
104
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Combined Process - Forced and Solar Evaporation
Creating a very large artificial salt lake bed near Denver can be
objectionable from aesthetic and many other viewpoints. The best alterna-
tive for disposal of waste brine in this event is the combined process
of forced and solar evaporation.
Preconcentration of waste brine to 10% solids by multistage flash
evaporators will reduce the volume of waste brine by 93%, with the
evaporator blowdown going to much smaller solar ponds east of the City
of Denver which could conceivably be used as recreational salt lakes.
The cost presented for this process is based upon the assumption
of the following:
Waste brine concentration = 7,000 mg/1 to evaporators
Fixed charge rate = .05 and 0.10
Power cost = $.025/Kgal. (based on L.P. steam turbine drives)
Steam cost = $0.46/mbtu
Chemicals cost = $0.016/Kgal. (cost of neutralization to pH 7.0)
(Note: Solar pond assumptions are based on Denver's annual evaporation rate.)
The forced and solar evaporation cost $/Kgal. at 5% and 10% fixed
charge rate and liner thickness are shown in Table 16.
TABLE 16
UNIT COST OF DISPOSAL FOR FORCED AND SOLAR EVAPORATION
DENVER COLORADO
Brine
Quantity
mgd
0.1
1.0
10.0
Fixed
Charge
Rate,%
10
5
10
5
10
Cost of Lined
Ponds (30 Mils)
$/Kgal
0.169
0.085
0.126
0.063
— — •
0.112
0 056
_ '
Cost of Lined
Ponds (20 Mils)
$/Kgal.
0.14
0.07
0.096
0.048
— . —
0.083
0.041
Cost of Lined
Ponds (10 Mils)
$/Kgal.
0.11
0.055
0.068
0.034
,054
0.027
Cost of Forced
Evaporation
$/Kgal.
0.906
0.661
0.715
0.55
OS7ft
0.454
105
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CONCLUSIONS AND RECOMMENDATIONS
This study reveals that for Denver, Colorado, the lined solar pond
is the best method for waste brine disposal at the present time. Ulti-
mate disposal by deep well injection into the pre-cambrian breccia
at 12,000 feet (which otherwise would be the cheapest method of disposal),
is prohibited because of earthquake problems. Pipelining of brines to the
ocean or the great salt lakes is, of course, prohibitively expensive.
Based upon ultimate disposal of 10 mgd waste brine at 7000 mg/1,
using fixed charge rate of 7%, the following are recommended:
Solar evaporation east of Denver, if land can be found, would
cost between 35
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BIBLIOGRAPHY
Anonymous - ]_
°THER WESTERN BOUNDARY
etn °7issi°n; ***** States and
Anonymous - 2
City of Tucson, Arizona
Anonymous - 3
THE TEXAS WATER PLAN.
Texas Water Development Board. November, 1968
Anonymous - 4
ANNUAL REPORT TO CONSUMERS
Denver Board of Water Commissioners. 1968
Anonymous - 5
ANNUAL STATISTICAL REPORT.
Denver Board of Water Commissioner. Dec. 31, 1968
Anonymous - 6
WATER QUALITY REPORT.
Denver Board of Water Commissioners. Dec. 31, 1968
Anonymous - 1
PLANNING PROGRAM.
Denver Board of Water Commissioners. May, 1969
Bechtel Corp.
OPTIMUM BRINE HEATER OUTLET TEMPERATURE IN SEA WATER
CONVERSION EVAPORATORS.
OSW R&D Report No. 175. 1966
Boegley, W. J. Et Al
DEEP WELL INJECTION OF BRINE EFFLUENTS FROM INLAND DESALTING PLANTS.
ORNL Report TM 2453. January, 1969
Bureau of Reclamation
PACIFIC SOUTHWEST WATER PLAN.
January, 1964 a.
Bureau of Reclamation
PACIFIC SOUTHWEST WATER PLAN - SUPPLEMENTAL INFORMATION REPORT
ON CENTRAL ARIZONA PROJECT, ARIZONA
January, 1964 b.
107
-------
Burns and Roe Corp.
UNIVERSAL SALINE WATER PLANT DESIGN
OSW Contract 14-01-0001-955. Nov., 1968
Burwell, C. C.
EFFECT OF LOW COST POWER ON WATER TRANSMISSION BY PIPELINE.
ORNL TM 1803. May, 1967
Chambers, John T. & Larsen, Paul T.
SERIES STAGING OF VAPOR COMPRESSION DISTILLATION.
University of California Water Resources Center Contribution
No. 25. May 13, 1960
Dean, Robert B.
ULTIMATE DISPOSAL OF WASTE WATER CONCENTRATES TO THE ENVIRONMENT.
Environmental Science and Technology - Volume 2 No. 12
December, 1968 - p. 1079 - 1086
DePuy, G. W.
DISPOSAL OF BRINE EFFLUENTS FROM INLAND DESALTING PLANTS: REVIEW
AND BIBLIOGRAPHY.
OSW R&D Progress Report No. 454. July, 1969
Dodge, Barnett F. and Eshaya, Allen M.
ECONOMIC EVALUATION STUDY OF DISTILLATION OF SALINE WATER BY
MEANS OF FORCED - CIRCULATION VAPOR - COMPRESSION DISTILLATION
EQUIPMENT
OSW R&D Progress Report No. 21. Undated
Dow Chemical Co.
A STUDY OF DEEP-WELL DISPOSAL OF DESALINATION BRINE WASTE.
OSW (Unpublished Report) April, 1969
Dow Chemical Co.
SEA WATER SOFTENING BY ION EXCHANGE AS A SALINE WATER
CONVERSION PRETREATMENT
OSW R&D Progress Report No. 62
Fluor Corp.
PRELIMINARY DESIGN OF AN OPTIMUM NUCLEAR REACTOR SALINE WATER
EVAPORATOR PROCESS.
OSW R&D Progress Report No. 34. 1959
Kern, Donald Q.
PROCESS HEAT TRANSFER
McGraw Hill. 1950
Koenig, L.
DISPOSAL OF SALINE WATER CONVERSION BRINES.
OSW R&D Progress Report No. 20. 1958
Koenig, L.
ULTIMATE DISPOSAL OF ADVANCED-TREATMENT WASTE
Parts 1 and 2 US. P.H.S. AWTR-3. October, 1963
108
-------
Koenig, L.
FURTHER STUDIES ON ULTIMATE DISPOSAL OF ADVANCED TREATMENT WASTES.
u.b. P.H.S. Unpublished -Report. Aug., 1966
Ledesma, V. L.
DESIGN STUDIES OF SEA WATER EVAPORATION WITH DIRECT CONTACT
M.S. Thesis, University of California. 1963
Mulbarger, M. C.
SLUDGES AND BRINES HANDLING, CONDITIONING, TREATMENT AND DISPOSAL
Ultimate Disposal Research Activities, Division of Research.
FWPCA Cincinnati Water Research Laboratory. 1968
Mulford, Stewart F.
UNITED STATES PATENTS 3,160,571 AND 3,172,824.
December 8, 1964 and March 9, 1965, respectively.
Office of Saline Water
MANUAL OF PROCEDURES AND METHODS FOR CALCULATING COMPARATIVE
COSTS OF MUNICIPAL WATER SUPPLY FROM SALINE AND CONVENTIONAL
WATER SOURCES IN TEXAS.
OSW R&D Report No. 257. Nov., 1966
Office of Saline Water
DESIGN AND ECONOMIC STUDY OF A GAS TURBINE POWERED VAPOR COM-
PRESSION PLANT FOR EVAPORATION OF SEA WATER.
OSW R&D Progress Report No. 377. Undated (Drawings are dated 1968)
Parsons, Ralph M. Co.
THE ECONOMICS OF DESALTING BRACKISH WATER FOR REGIONAL, MUNICIPAL
AND INDUSTRIAL WATER SUPPLY IN WEST TEXAS.
OSW R&D Progress Report No. 337. Sept., 1967
Southwest Research Institute
THE POTENTIAL CONTRIBUTION OF DESALTING TO FUTURE WATER SUPPLY IN
TEXAS.
OSW R&D Progress Report No. 250. Nov., 1969
Wilke, Cheng, Ledesma, and Porter
DIRECT CONTACT HEAT TRANSFER FOR SEA WATER EVAPORATION.
Chemical Engineering Progress, Vol. 59 No. 12. Dec., 1963
Yamane, R. , Ichikawa, M. , Mizutani Y., and Onoue Y.
CONCENTRATED BRINE PRODUCTION FROM SEA WATER BY ELECTRODIALYSIS
USING ION EXCHANGE MEMBRANES.
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109
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NOMENCLATURE
A Cost of 12" diameter pipe $ per linear foot (installed)
AE Surface area; acres
ALNR Area of liner; square feet
AWT Advanced waste treatment
B Cost of pump and drive; $/hp
B* Cost of pump and drive, including 50% standby capacity plus
100% diesel standby generation; $/Hp
BTUjbtu British thermal unit
CE Capital cost of solar evaporation pond
CE
u
Unit cost of brine disposal by solar evaporation; $/Kgal.
CFH Cubic feet per hour
CLND Cost of land; $/acre
CLNR Cost of liner; $/ft2
CP Unit cost of brine disposal by pipeline conveyance for £ miles;
U $/Kgal.
CT Total unit cost of brine disposal by solar evaporation and pipe-
line conveyance for Si miles; $/Kgal.
D Inside diameter; ft
ER Net annual evaporation rate, in./yr
F Evaporation pond fetch; miles
FCR Fixed charge rate (annual capital recovery factor, fraction or
% as needed)
FCR' Modified fixed charge rate (including annual maintenance, fraction
FCR + 0.0025)
f Darcy's friction factor, dimensionless
d
gpd Gallons per day
HW Height of wave; ft
H Effective height of formation face; ft
HP Horsepower
h Heat transfer coefficient, BTU/hr - sq ft °F
o
HD Height of dike; ft
Kgal Kilo gallons
Kwhr Kilowatt hour
L Length of dike; yards
£ pipeline distance; miles
mbtu Million british thermal units
111
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NOMENCLATURE (Continued)
MGD;mgd Million gallons per day
mg/1 Milligrams per liter
MSFE Multi-stage flash evaporator
N Number of stages
OMR Operation, maintenance, and repairs
P Average formation porosity; volume of voids/total volume
P, Precipitate depth; ft
d
P Pressure drop due to pipe friction; psig
psia Pounds per square inch, absolute
psig Pounds per square inch, gauge
P Feet of precipitate per foot of water evaporated
PVC Polyvinyl chloride
P° Operating well head pressure; psig
w
P Well head pressure excluding friction; psig
w
Q Brine disposal capacity; mgd
Qe Brine disposal capacity evaporated; mgd
Q Brine disposal capacity for pipeline conveyance; mgd
R Cost of right of way: $/mile
Rp Optimum performance ratio
Sr Brine disposal concentration ratio; S /S (dimensionless)
S Brine disposal concentration from AWT treatment plants, 7000 mg/1
S Brine disposal concentration in pipelining , mg/1
SCE Submerged combustion evaporator
T Total land area; acres
TDS;tds Total dissolved solids
Vjj Volume of dike; cubic yards
Vf Volume of fill to cover liner, cubic ,yard
Z Power unit cost, mills/Kwhr
112
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APPENDIX
It has not been practical to include in this report the details
of all calculations carried out under the contract. Certain material
has been collected together for possible review by those who have need
of the greater detail. The material includes:
1. A more complete list of source documents
2. Mathematics and/or computer write-ups for:
a. deep-well injection
b. solar evaporation
c. combined solar evaporation and pipeline conveyance
d. pipeline conveyance
e. optimization of multistage flash evaporators
f. multistage flash evaporation with ion-exchange pretreatment
g. vapor compression cost versus cost of power
This information, entitled "Supplementary Material under Contract
14-12-492 with Burns and Roe, Inc., Disposal of Brines, etc." is de-
posited in the Library of the Robert A. Taft Water Research Center,
Cincinatti, Ohio, and may be examined there.
113
* U. S. GOVERNMENT PRINTING OFFICE : 1970 O - 410-263
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