WATER POLLUTION CONTROL RESEARCH SERIES 14010 DYK 03/70
Treatment of Acid Mine Drainage
by Reverse Osmosis
U.S. DEPARTMENT OF THE INTERIOR FEDERAL WATER QUALITY ADMINISTRATION
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WATER POLLUTION CONTROL RESEARCH SERIES
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Treatment of Acid Mine Drainage
by Reverse Osmosis
by
Rex Chainbelt, Inc.
Milwaukee, Wisconsin 53201
for the
Commonwealth of Pennsylvania
Department of Mines and Mineral Industries
Harrisburg, Pennsylvania 17102
and the
FEDERAL WATER QUALITY ADMINISTRATION
U.S.DEPARTMENT OF THE INTERIOR
Program Number
FWPCA Grant No. 14010 DYK
March 1970
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington. D.C., 20402 - Price 5S cents
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ABSTRACT
This report documents a study on the treatment of acid mine drainage
by reverse osmosis. The objective of the study was to determine the
feasibility of utilizing reverse osmosis to abate pollution due to acid
mine drainage, and produce a water which could be used by industry or as
a municipal water supply.
A test site in Shickshinny, Pennsylvania was selected as a source of
acid mine water for the study. A sample of this water was tested in a
laboratory reverse osmosis unit to determine the design parameters for
a 10,000 gallon per day demonstration unit. This unit was operated
for a period of 35 days on acid mine drainage as received from the
Mocanaqua discharge near Shickshinny. Operation during this period was
continuous, i.e., 24 hours per day. Daily samples of feed water, product
water, and waste concentrate were analyzed to determine the effectiveness
of the demonstration unit.
The results obtained during the demonstration period indicated that the
reverse osmosis process has potential application in acid mine drainage
treatment. A high quality water was produced which was suitable for
use by industries or municipalities with a minimum of additional treat-
ment. There are, however, operational problems which must be solved
prior to utilizing reverse osmosis on a large scale. These include
maintenance of high permeation rates through the membrane by reducing
membrane fouling and determination of the optimum flow sheet for an
acid mine treatment system utilizing reverse osmosis.
To provide the information necessary to effectively utilize reverse
osmosis In treating acid mine drainage, it is recommended that:
1) The mechanisms and methods of reducing iron fouling of
reverse osmosis membranes be evaluated in the laboratory
using synthetic acid mine water.
2)' The optimum flow sheet for treating acid mine drainage by
reverse osmosis be determined by laboratory evaluation of
synthetic acid nine water.
3) The laboratory data be confirmed by a field evaluation
period.
This study was performed by the Technical Center of Rex Chainbelt Inc.
under a contract with the Commonwealth of Pennsylvania, Department of
Mines and Mineral Industries in fulfillment of project No. CR-86 under
the partial sponsorship of the Federal Water Pollution Control
Administration (Grant Number 14010 DTK).
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TABLE OF CONTENTS
Page
INTRODUCTION «... 1
SUMMARY AND CONCLUSIONS 1
RECOMMENDATIONS 2
REVERSE OSMOSIS AND ITS APPLICATION TO
ACID MINE DRAINAGE TREATMENT 3
DESIGN OF THE DEMONSTRATION UNIT 9
FIELD OPERATION AND EVALUATION 9
DISCUSSION OF RESULTS, 17
BIBLIOGRAPHY 25
ACKNOWLEDGMENTS 26
PUBLICATIONS 26
APPENDIX 27
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LIST OF FIGURES
Page
Figure 1 DESCRIPTION OF OSMOSIS 4
Figure 2 ESSENTIAL ELEMENTS OF A REVERSE OSMOSIS SYSTEM 5
Figure 3 SPIRAL WOUND MEMBRANE 6
Figure 4 SKETCH OF HOLLOW FINE FIBER RO MODULE 8
Figure 5 SKETCH OF THE TUBULAR MODULES USED IN THIS STUDY 8
Figure 6 SCHEMATIC FLOW SHEET FOR DEMONSTRATION UNIT 11
Figure 7 SUMMARY OF FLOW DATA 13
Figure 8 VARIATION OF PERMEATE WATER QUALITY 15
Figure 9 TITRATION - PERMEATE FROM REVERSE OSMOSIS TEST UNIT.. 19
Figure 10 TITRATION CURVE - ACID MINE DRAINAGE
SHICKSHINNY, PENNSYLVANIA 20
Figure 11 COMPARISON OF THE RATE OF FLUX DECLINE IN THE
FIELD AND LABORATORY 24
LIST OF TABLES
Table 1 SUMMARY LABORATORY RESULTS 10
Table 2 WATER QUALITY DATA 16
Table 3 IRON REJECTION WITH VARIOUS POROSITY MEMBRANES
WITH SYNTHETIC ACID MINE WATER 18
Table 4 PERMEATE QUALITY FROM INDIVIDUAL MODULES 21
Table 5 PRODUCT WATER ION BALANCE 28
Table 6 FEED WATER ION BALANCE 29
Table 7 CONCENTRATE ION BALANCE 30
Table 8 IRON (II) MASS BALANCE 31
Table 9 MAGNESIUM MASS BALANCE 32
Table 10 CALCIUM MASS BALANCE 33
Table 11 SULFATE MASS BALANCE 34
Table 12 MANGANESE MASS BALANCE 35
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INTRODUCTION
Drainage from mining operations in the United States has resulted in
a serious water pollution problem (1). To abate this pollution, many
methods have been proposed which utilize source control. These
include mine sealing, water diversion, mine flooding, improved mining
techniques, and land reclamation. While these techniques are effect-
ive, they do not completely solve the mine drainage problem. Since
40% of the mine drainage comes from active mines which are usually
not amenable to source control, treatment of some mine discharges
will be necessary (1)(2), and several states have enacted laws
requiring treatment of the drainage from active mines.
The primary pollutants present in mine drainage include sulfate,
iron, manganese, calcium, magnesium and acidity (2). Removal of
the pollutants from acid mine drainage can be accomplished with a
variety of processes. Iron and manganese can be removed by
neutralization, aeration and settling, since they easily form insol-
uble hydrates. These processes, however, do not remove the other
dissolved salts present in acid mine drainage such as SO^, Ca,
Mg, etc., and therefore do not produce a high quality, low dissolved
solids water. Almost complete removal of the dissolved solids in
mine drainage could be accomplished by ion exchange, distillation,
and reverse osmosis. The objective of this study is to determine
the feasibility of using reverse osmosis to treat acid mine drain-
age and produce a high quality water which can be used by muni-
cipalities or industry.
To accomplish this objective the project was divided into two phases.
In Phase 1, a sample of acid mine water from the Mocanaqua discharge
near Shickshinny, Pennsylvania, was evaluated in a laboratory reverse
osmosis unit. The results of this evaluation allowed selection of
the proper membrane for design and construction of a 10,000 gpd
reverse osmosis demonstration unit. Phase 2 consisted of operating
this unit on the Mocanaqua discharge. Parameters evaluated during
this field operation included water quality, water permeation rates,
membrane cleaning techniques, and water conversion rates.
SUMMARY AND CONCLUSIONS
This study has demonstrated the potential use of reverse osmosis in
treating acid mine drainage. A high quality water was produced which
is suitable for reuse with a minimum of additional treatment. Some
operational problems, however, must be investigated before reverse
osmosis can be applied to treat acid mine drainage on a large scale.
The main problem is maintenance of high water permeation rates through
the membrane by proper operating techniques to reduce membrane fouling.
Specific conclusions which can be drawn from this study are:
1) Reverse osmosis can produce a water of about 50 mg/1 TDS
and about 3 mg/1 of iron based on the AMD treated in this
study.
-1-
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2) This water is suitable for use as a water supply for
industrial or municipal purposes.
3) To meet drinking water standards, treatment of the permeate
from reverse osmosis will generally be required when the iron
content in the feed water exceeds 100 mg/1.
4) Iron (II) in the presence of oxygen at a pH of 3.5 caused
serious iron fouling of the membranes which resulted in a
rapid decrease in product water flow.
5) This iron fouling is apparently a purely chemical reaction
at the membrane surface.
6) A 5% solution of sodium hydrosulfite will effectively remove
the iron precipitates from the membrane surface without
impairing product water quality.
7) Water recovery rates of 80% can be obtained if the iron
fouling problem is minimized.
8) Ten percent of the modules failed after 813 hours of operation.
9) Module failures were always associated with chemical cleaning
of the membranes using sodium hydrosulfite.
RECOMMENDATIONS
Based on the results of this study, it is recommended that:
1) The mechanisms and methods for reducing iron fouling in
reverse osmosis be evaluated in the laboratory using
synthetic acid mine water.
2) Various sources of acid mine drainage be sampled at points
within the mines or mine shafts to determine if acid mine
water with extremely low dissolved oxygen can be obtained.
3) Possible alternate flow schemes be investigated in the
laboratory to determine the most economical method of
utilizing reverse osmosis in treating acid mine drainage.
This would include possible preoxidation of the iron to
reduce the fouling potential.
4) The significance of the laboratory data be evaluated by a
field test period.
5) A detailed cost analysis for using reverse osmosis to treat
acid mine drainage be prepared.
-2-
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REVERSE OSMOSIS AND ITS APPLICATION TO ACID MINE DRAINAGE TREATMENT
Osmosis occurs if two solutions of different concentrations in the same
solvent are separated from one another by a membrane. If the membrane
is semipermeable, i.e., permeable to the solvent and not to the solute,
solvent flow occurs from the more dilute to the more concentrated
solution. This solvent flow continues until the two solutions are of
equal concentration or the pressure on the more concentrated side of
the membrane rises to a value called the osmotic pressure. If a
pressure in excess of the osmotic pressure is applied to the more
concentrated side of the membrane, the solvent can be caused to flow
into the more dilute solution. This is termed reverse osmosis and is
illustrated in Figure 1. From the above discussion, it may be concluded
that the reverse osmosis process can be used to separate dissolved
solids from water without a phase change (i.e., freezing or distilla-
tion) .
The basic elements of a reverse osmosis system are shown in Figure 2.
It may be seen from this figure that the reverse osmosis process
produces two liquid streams. One stream, highly concentrated with the
dissolved salts originally present in the feed stream, is called the
concentrate or brine stream, while the water which has passed the
membrane is called the permeate, or product water. The concentrate
stream represents a potential pollution problem and disposal of this
concentrate must be carefully considered in all reverse osmosis
applications. The permeate is of high quality containing only small
amounts of dissolved solids (1 to 3% of the salts in the feed stream),
and is suitable for a wide variety of uses. The reverse osmosis system
is very simple and consists basically of a pump and a membrane bank.
A back pressure valve is required to hold the system at the desired
pressure. These are usually spring loaded valves. Also shown in
Figure 2 are the associated safety switches to provide for safe operation
of the unit. The basic schematic shown in Figure 2 is common to all
reverse osmosis systems. The difference between systems lies in the
membrane bank which is discussed below.
There are a number of membrane systems (i.e., the method of packaging
the membrane) available (3). However, there are only three forms
which are commercially available in large quantities. These are spiral-
wound, tubular, and hollow fiber membranes.
A spiral-wound (4) reverse osmosis module is shown in Figure 3. The
module consists of one or more leaves wrapped around a product water
take-off tube. These leaves consist of the membrane, porous in-
compressible product-water-side backing material, and brine-side flow
spacer. The membrane is bonded along the two sides, at the end, and
around the product water tube, forming a sealed envelope that encloses
the backing material except at the product-water-tube open end. The
brine-side flow spacer is placed on the membrane, and the several
layers are then wrapped around the product-water-tube to form a
cylindrical module. Modules are contained in a suitable pressure
vessel, and the pressure vessels are grouped together to form the
membrane bank por'tion of the reverse osmosis system. Membrane available
-3-
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Pressure
f
Fresh
Water
*
Osmotic
Pressure
Saline
Water
i
1
t
Fresh
Water
Saline
Water
Semi-permeable Membrane
Semi-permeable Membrane
a) Normal Osmosis
b) Reverse Osmosis
FIGURE 1
DESCRIPTION OF OSMOSIS
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Low Pressure
Cut Out
Feed
Water
V7
High
Pressure
Pump
600-800 psl
Membrane
Bank
High Pressure
Cut Out
0
Brine or Waste
Concentrate Flow
Back
Pressure
Valve
>H±gh Salinity
Cut Out
Product Water or Permeate Flow
FIGURE 2
ESSENTIAL ELEMENTS OF A REVERSE OSMOSIS SYSTEM
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Roll to
Assemb
Feed Side
Spacer
f
Permeate Out
Permeate Flow
(After Passage
through
Membrane)
Feed Flow
Permeate Side Backing
Material with Membrane on
Each Side and Glued Around
Edges and to Center Tube
FIGURE 3
SPIRAL-WOUND MEMBRANE
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for the spiral wound configuration are cast from a cellulose acetate
solution.
A relatively new type of commercially available membrane is the hollow
fiber. Hollow fiber membranes are spun into fine fibers of about
50 microns diameter. The fibers are then potted in epoxy resin in a
sheet and tube configuration similar to a single ended heat exchanger.
A sketch of a hollow fine fiber module is shown in Figure 4. The fiber
wall is about 25 microns thick making a pipe type structure which can
withstand the pressures needed in reverse osmosis. The flow of water is
generally from the outside of the hollow fiber to the inside, which is
exactly opposite conventional tube type reverse osmosis systems. Hollow
fiber membranes are available in cellulose acetate and nylon (5).
In tubular membrane systems, the membrane is formed in a. tubular shape
generally one-half inch in diameter and several feet long. There are a
number of different tubular systems which are commercially available.
In some systems the membrane is cast directly onto a supporting tube,
while in others the membrane is cast separately and later inserted into a
supporting tube. Tubular type membranes were utilized in this study.
They consisted of 1/2 inch diameter spun fiber glass tubes. The cellulose
acetate membrane was cast directly onto the fiber glass tubes. Eighteen
tubes connected in a series comprised a module, and 70 modules were
utilized to form the membrane bank portion of the reverse osmosis system.
A sketch of the tubular modules used in this study is shown in Figure 5.
There is no doubt that the reverse osmosis systems available today can
produce a high quality water from acid mine drainage. There are,
however, areas which must be investigated to determine the engineering
feasibility and economic feasibility of operating this process on acid
mine waters in large scale plants. These areas include maintenance of
high flux rates, i.e., water permeation rate per square foot of membrane
area, membrane life, permeate water quality, methods of disposal of the
concentrate stream, membrane cleaning techniques, and the economic
effects of these factors on water production costs.
There has been a limited amount of work done in the area of reverse
osmosis application in acid mine drainage. Riedinger and Schultz (6)
found that high quality water could be produced from acid mine drainage
via reverse osmosis. The membrane system which was utilized was a spiral
wound system (4). Feed water pH was 3 or less and contained about
100 mg/1 of iron. Water recoveries in excess of 90% were reported, but
some iron fouling of the membrane did occur, decreasing the product water
output. Other investigations have also indicated problems with iron
fouling of reverse osmosis membranes (7) (8) and it appears iron fouling
and subsequent membrane cleaning is the most critical area in applying
this process to the treatment of acid mine waters. Hill (1), however,
reported on work being done at Norton, West Virginia, and indicated no
problems with iron fouling were experienced. Salt rejections were 99%,
but no permeation rates nor the length of the test run were reported.
The majority of the iron was in the trivalent state and this may have
some Influence on membrane fouling. It is apparent from the above
discussion that many technical areas require investigation in order to
successfully apply reverse osmosis to the treatment of acid mine waters.
-7-
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Concentrate Outlet
Assembled Module
Cylinder Packed with
Hollow Fine Fibers
Feed Water In
Product Water Outlet
FIGURE 4
SKETCH OF HOLLOW FINE FIBER
REVERSE OSMOSIS MODULE
Assembled Module
Single Tube
FIGURE 5
SKETCH OF THE TUBULAR MODULES
USED DURING THIS STUDY
-8-
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DESIGN OF THE DEMONSTRATION UNIT
To provide basic design criteria for the reverse osmosis test unit,
a 200 gallon sample of acid mine drainage (AMD) from the Mocanaqua
discharge (a drain tunnel from an anthracite mine) was sent to Havens
International, the supplier of the reverse osmosis test equipment for
this study. Laboratory tests were performed on this water to determine
the salt rejection properties and select the type of membrane to be
utilized for the demonstration unit. The results of these tests are shown
in Table 1. When collected the iron in the sample was predominately in
the Fell state. By the time the sample reached the laboratory (one week),
the iron had precipitated as a ferric oxide and the sample had the color
of dilute orange juice. Laboratory testing was performed on the sample
as received. Average total dissolved solids rejection was 96% at a water
recovery of 85%. Values for specific ions are listed in Table 1. A
continuous run of 70 hours showed no appreciable decrease in permeate flow
rate. Based on these results, type 300 membrane was chosen for the
demonstration unit. This membrane has a better than 95% rejection of
divalent ions and a 60-90% rejection of monovalent ions, according to the
manufacturer. The sizing of the unit resulted in the flow sheet presented
in Figure 6. Seventy tubular modules were utilized in a three bank
arrangement, each module containing 17.35 sq ft of membrane area, or a
total of 1215 sq ft. The first bank which receives the raw feed water
contains six rows of seven modules each (for a total of 42 modules). The
concentrate from the first bank is routed into the second bank of modules,
which contains four rows of five modules each (for a total of 20 modules).
The third bank of modules receives the concentrate from bank two and
contains two rows of four modules each (for a total of 8 modules). The
concentrate from bank three was routed to waste. The permeate or product
water from all banks is collected in a common header. The flow of
permeate and concentrate is monitored using totalizing water meters.
Associated hardware such as high and low pressure safety switches,
salinity alarm, pH alarm, elapsed time meter, pressure gauges, and
auxiliary pump is also provided. The main pressurizing pump is a Moyno
progressive cavity pump. The entire system is mounted on a frame with
openings for a fork lift truck. The unit is wired for 230/115 volt
operation.
FIELD OPERATION AND EVALUATION
For ease of transportation and operation, the demonstration unit was
mounted on a truck and transported to the test site near Shickshinny,
Pennsylvania. The unit was operated continuously (24 hours per day)
from October 10 through November 14, 1969 on AMD which had received no
pretreatment. This represents 840 hours of possible operating time.
Actual operating time recorded on the meter was 813.4 hours. The
remaining hours (26.6) was down time due to module failures, power
failures, and system maintenance. This represents a 97% on stream time
which could be improved, since some module failures and/or power
failures occurred during the night and were not corrected until morning
when the operator came to check the unit. There were seven module
failures which represents 10% of the modules in the unit. These module
failures were always associated with a tube rupture and could be easily
spotted by disassembling the module. The modules were then repaired by
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Table 1
SUMMARY OF LABORATORY TEST RESULTS
Analysis
Raw Acid Mine
Drainage
(me/1)
Product Water
from
Reverse Osmosis
(mg/1)
Sodium (Na)
Potassium (K)
Calcium (Ca)
Magnesium (Mg)
Manganese (Mn)
Iron (Fe) (Total)
Chlorides (Cl)
Sulfate (S04)
Nitrate (N03)
Silica (Si02)
Total Dissolved Solids (Analysis)
Total Dissolved Solids (Calculated)
pH
4.0
2.0
144.0
80.0
17.0
38.4
5.0
750.0
0.9
14.0
1228.0
1055
3.2 units
1.6
1.0
5.6
4.4
0.5
4.0
32.0
0.6
12.0
50
61
4.3 units
Test Conditions:
Operating Pressure
Product Water Recovery
Average Permeate Rate
Feed Temperature
Length of Test
Sample Taken in May 1969
Type 300 membrane
Tests Run 12-16 May 1969
600 psig
85%
8.2 gsfd
20-25° C
70 hours
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7 Modules in Series
I
rt
tpHXI-HXHTr
ixH
-IX-
4 Modules in Series
Bank 3
8 Modules
5 Modules in Series
Bank 2
20 Modules
Bank 1
42 Modules
Permeate Discharge
C>»Pressure "In" Gauge
V>»High Pressure Cutout
Switch
Pressure
Safety Relief Valve
pH Sensor Probe
Feed
Moyno 9P4 Pump
O
TDS Sensor
Q Pressure "Out" Gauge
> Low Pressure Cutout Switch
Manual By-Pass Valve
-cxi-
\ Back Pressure
Regulator
Concentrate
Discharge
FIGURE 6
SCHEMATIC FLOW SHEET
FOR DEMONSTRATION UNIT
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replacing the ruptured tubes.
The feed water and permeate flow data for the entire experimental run is
plotted in Figure 7. The permeate rate in both gal/hr and gal/sq ft (day)
is plotted as a function of operating time. During the first 250 hours of
operation the permeate rate declined steadily from 400 gal/hr to
150 gal/hr. During this decline the concentrate stream remained clear;
however, a very small amount of orange and black particles were occasionally
observed during the twice daily 5 minute flush at reduced pressure. The
permeate rate then remained steady for about 100 hours at an average value
of 140 gal/hr. At about 330 hours, the flux again began to decline. This
decline was possibly due to the discharge of gelatinous precipitated iron
slurry near the intake of the RO unit. This discharge was a result of the
coal washing operations in the area. This ferric precipitate was observed
in the concentrate stream shortly after the discharge at the intake. At
403 hours a module was removed from the unit and disassembled. Upon
inspection, it was found that the membranes were coated with a brown
precipitate. Analysis of this material indicated 47% was iron (as Fe),
4.7% sulfate, and less than 1% calcium. The fouling was, therefore, due
mainly to oxidation of iron (II) to iron (III) and precipitation of the
ferric compounds at the membrane surface, i.e., the point of highest
concentration. In an attempt to clean the membranes, they were flushed
with a 5% solution of ammonium per sulfate [(NH^)28203], This chemical
did not dissolve the scale, but loosened it and caused it to slowly slough
from the membrane. Red flakes were evident in the concentrate stream
during the two daily reduced pressure flushes, which were at this time
increased from 5 to 15 minutes. At 450 hours the unit was flushed
overnight with a phosphoric acid solution. This also caused flaking of
the coating on the membrane and a slow but steady increase in permeate
flow rate.
The module which had been disassembled was tested to determine what
chemical could best be utilized to dissolve the iron coating from the
membrane. After discussions with the membrane manufacturer, it was
discovered that a 5% sodium hydrosulfite (Na2&20^) solution would remove
the scale. At 609 hours the unit was flushed with sodium hydrosulfite,
resulting in a dramatic increase in permeate flow rate from 100 to
310 gal/hr. This represents essentially a complete restoration of flux,
considering some of the original flux would be lost due to compaction of
the membrane when operating at 600 psig. The expected flux decline due
to compaction has been plotted in Figure 7, and indicates a 100 percent
restoration of flux would have resulted in a product water rate of about
320 gallons per hour instead of the 310 gph observed. Shortly after the
sodium hydrosulfite wash a module failed. This was the first module
failure in over 600 hours of operation, but it did not seem likely that
the chemical flushing should cause this failure.
After putting the unit back on stream the permeate rate again began to
decline. At 733 hours 50% of the permeate flow had been lost. Another
sodium hydrosulfite wash was performed, and again the permeate rate was
increased from 150 to 300 gal/hr. Shortly after this second wash two
modules failed and it appeared that there may be some correlation between
washing and module failure.
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500
<*00
1
>*
01
4J
a
t. I
y (*
300
200
100
Operating Pressure 600 psig
Operating Temperature 53°F
eed Water Flow
Sa2SOa Fed
Continuously
200 mg/1
Flux Decl
Alode
Con paction
Spillage of Iron
Gel at Intake
HgPO,,
Flush
300 i»00 500
Elapsed Operating Time (hr)
o
U4
n
o>
0)
800
FIGURE 7
SUMMARY OF FLOW DATA
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The acid mine discharge was monitored for dissolved oxygen and was
found to contain 2.9 mg/1 of oxygen at the point of discharge from
the mine and 4.9 mg/1 of oxygen at the intake of the demonstration
unit. Sodium sulfite was added in the feed line to remove the oxygen.
It was thought that removal of the oxygen would eliminate the flux
decline due to iron fouling, by eliminating iron oxidation. Sodium
sulfite was added at a rate of 200 mg/1, but even at this concentra-
tion it was not possible to remove all the oxygen as the concentrate
(brine) still contained 1.4 mg/1 of 02. The inability to obtain "0"
dissolved oxygen could have been caused by the slow reaction of
sodium sulfite with the oxygen present in the mine water, since the
sodium sulfite was not cobalt catalyzed, and the water temperature
was quite cold. Other possibilities include air entering the system
through the hoses or pumps. The permeate rate continued to decline
during the sulfite addition. It was also noted that the sulfite did
cause a precipitate to form in the feed stream and this also could
have had an effect on the permeate flow rate. As a result of these
problems, reduction of iron oxidation and permeate rate decline did
not occur.
At 813 hours the unit was taken off stream and again washed with
sodium hydrosulfite to remove any iron fouling. After washing, the
unit was put into operation on tap water and a module failure occurred
within two hours, further supporting the possibility that sodium
hydrosulfite washing could be linked to module failures.
The water recovery rates may also be seen in Figure 7. In general,
the feed water to the unit was reduced as the permeate rate declined.
Because of the flow configuration of the unit, there was a limit to
how low the feed flow rate could be reduced and still maintain
turbulent flow throughout the unit. This lower limit was selected as
1 gpm per module row, which was equivalent to 360 gallons per hour
total raw flow. As a result of this limitation, the water recovery
varied from 80% to as low as 15%. The recovery was held essentially
constant over the first 200 hours at 75-80%. During this period
no precipitation was noted in the brine stream. This would indicate
that an 80% recovery is attainable, if a solution to the flux decline
problem is found.
The water quality of the permeate is plotted as a function of time
in Figure 8. As may be observed, permeate water quality was essentially
constant during the first 400 hours of operation, even though the
permeate flow rate was steadily decreasing. After 400 hours, when
the precipitated iron began to flake from the membranes, a general
increase in all measured values was observed. The values again
stabilized shortly after 400 hours and remained relatively constant
throughout the remainder of the test. By again observing Figure 8,
it can be seen that no change in permeate quality occurred after
flushing the unit with sodium hydrosulfite at 617 and 733 hours.
This indicates the permeate rates can be restored without impairing
permeate water quality. A summary of the water analyses is shown in
Table 2. The analyses which were performed included calcium, mag-
nesium, manganese, iron, copper, sulfate, chloride, nitrate, nitrite,
and phosphate. Of these analyses, chloride, nitrate, nitrite, phos-
phate and copper were present in only trace quantities (0.1 - 0.3 mg/1).
Analyses for these ions were discontinued after 100 hours of operation.
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*>
2
4J
100
4)
«J
0)
tO
« 10
09
0)
5
-------
Table 2
WATER QUALITY DATA
Analysis Performed
i
i
i
Ion
Calcium
Magnesium
Manganese
Iron ^
Sulfate
pH
Total Dissolved
Feed
Water
(mg/1)
141 * 1
101 * 5
16 * 2
118 * 5
1106 * 35
3.6
1150
in Field -
Product
Water
(mg/1
0-400 hrs)
3.2 * 0.9
2.9 * 0.3
0.43 * 0.2
3.0 * 0.4
31.4 * 5
4.1 - 4.4
47
Shickshinnv
Rejection
97.7
97.1
97.4
97.3
97.2
, Pennsylvania
Product
Water
(mg/1
400-800 hrs)
13.9 * 2.8
8.2 * 2.1
1.5 * 0.2
9.3 * 1.4
98.0 * 10
4.1 - 4.4
130
Rejection
90.1
91.8
92.1
90.5
91.1
Analysis Performed at
Rex Chainbelt Laboratory - Milwaukee
Feed
Water
(mg/1)
143
100
16.4
131
792
3.2
1760
Product
Water
(mg/1
0-400 hrs)
2.8
1.9
0.4
3.7
36
4.1
57
Product
Water
(mg/1
400-800 hrs)
11.3
8.1
0.4
6.6
40
4.6
128
Solids
All iron in Fe4"*" state.
Field data based on approximately 35 separate analyses.
Confidence level at 99%.
IDS analysis by conductivity meter in field and by
evaporation in laboratory.
-------
It may be seen from Table 2 that rejection ratios for the first 400 hours
ranged from 97 to 98% and that this ratio decreased to 91 to 92% during
the second half of the run. During the field testing three sets of
samples were shipped to Rex's laboratory in Milwaukee for analyses. These
analyses were conducted in accordance with Standard Methods (9). The
average of these analyses (shown in Table 2) compared well with the field
analyses which were performed with a Hach water analysis kit (//EL-DR).
The only analysis which did not correlate well was sulfate, and in both
analysis procedures a turbidimetric method was utilized in which a ±10%
accuracy is the best to be expected (9). By assuming the only ions
present were calcium, magnesium, manganese, iron and sulfate, an ion
balance was performed. These balances are shown in the Appendix (Tables
5, 6, 7). An excess of negative ions (sulfate) was almost always present,
indicating that the actual sulfate concentration was probably closer to the
laboratory analysis than the field analysis of Table 2.
DISCUSSION OF RESULTS
The quality of the permeate during the first 400 hours of the experiment
was very good. Total dissolved solids was about 50 mg/1. Iron and
manganese were, however, higher than the recommended drinking water quality
standards set by the Public Health Service (10) of 0.3 mg/1 iron plus
manganese. The excess iron and manganese should be removable by a
variety of processes in conventional water treatment plants (11). Hence,
the permeate would be suitable as a drinking water source. The iron and
manganese content in the permeate could also be reduced by using a
reverse osmosis membrane which would reject a higher percentage of the
dissolved salts. The results of a laboratory study to determine iron
rejections with various types of membranes is shown in Table 3. The iron
content was reduced to as low as 0.5 mg/1 which represents a 99.7 overall
iron rejection at 85% water recovery. To achieve these rejections, the
rate of permeate flow per square foot of membrane area is reduced, requir-
ing significantly more membrane area. Even at 99.7% rejection, the iron
content does not meet drinking water standards. It appears, therefore,
that some type of post treatment of the permeate will be required
whenever the iron content in the feed water is above 100 mg/1 and it is
desirable to meet drinking water standards. When treatment of the
permeate is required, the use of a more open type of membrane will generally
produce the most economical operation.
The permeate produced during this study had very little buffering capacity.
Titration curves of a sample of permeate and raw acid mine drainage are
shown in Figures 9 and 10. The raw water had an acidity of 400 mg/1 while
the permeate had only 36 mg/1. This represents 91% removal of acidity,
and indicates that neutralization of the permeate by adding a base or
dilution with an existing water supply would pose no problems and be
relatively inexpensive.
The permeate water quality change which occurred at about 400 hours of
operation (Figure 8) was initially thought to be caused by a leaking
module. At 498 hours a check on the permeate salinity from each
individual module was made. The results of these analyses are shown in
Table 4. The highest individual module salinity was 230 mg/1. In
-17-
-------
Table 3
Membrane
IRON REJECTION WITH VARIOUS POROSITY MEMBRANES
SYNTHETIC ACID MINE WATER2
Relative
Flux Rate
%
100
75
50
Iron in
Feed
mg/1
125
125
125
Iron in
Permeate
(^30% Recovery)
mg/1
1.0
0.65
0.28
Iron in
Permeate
@ 88% Recovery^
mg/1
1.9
1.2
0.5
300
400
500
1
Membranes manufactured by Havens International.
o
Test run on synthetic acid mine water of same composition as
shown in Table 2.
q
Calculated value.
-18-
-------
10
1
3
w
(4
0)
VO -H
I S
Phenolphthalein
Acidity 36 mg/1 as
CaC03
250 ml sample
Sampled November 14,'69
7
PH
1U
FIGURE 9
TITRATION CURVE - PERMEATE FROM REVERSE OSMOSIS TEST UNIT
-------
20
I
15
8 §
10
Phenolphthalein
Acidity « 400 mg/1 as CaC03
200 ml sample
Sampled November 14, .1969
6
pH
FIGURE 10
TITRATION CURVE - ACID MINE DRAINAGE
MOCAHAQUA, PENNSYLVANIA
-------
Table 4
PERMEATE QUALITY FROM INDIVIDUAL MODULES
Module Row Module Number
Bank No. 1 2 3 4
62
117
122
100
110
131
173
130
160
150
148
171
150
142
175
155
142
180
178
158
129
166
200
220
220
162
150
160
190
200
230
170
180
200
160
170
165
222
203
173
222
170
1 1
1 2
1 3
1 4
1 5
1 6
2 1 180 183 150 174 189
2 2 193 190 196 209 210
2 3 160 168 210 173 194
2 4 133 152 175 184 200
3 1 137 102 116 102
3 2 129 113 115 106
Data taken at 498 hours.
All values in mg/1 total dissolved solids with Myron L Dissolved
Solids Meter.
Average salinity 160 * 20 at 99.999% confidence level.
-21-
-------
general, the salinities were very consistent throughout the unit,
indicating the permeate quality deterioration was not due to an in-
dividual module failure. Other events which occurred at about the time
of this marked salinity change include a phosphoric acid wash, and an
ammonium persulfate wash. Both of these washes were conducted at a pH
of 3 or above, so accelerated hydrolysis of the membrane does not seem
likely. During the ammonium persulfate wash the unit was accidently
drained of water for a period of about 15 minutes. It was thought that
this drainage caused partial dehydration of the membranes and was the
cause of the change in permeate water quality. The manufacturer of the
membranes, however, indicated that this period of time should not have
caused membrane damage. Another event occurring in the range of 400-450
hours was the presence in the concentrate stream of red flakes of iron.
Apparently the chemical flushing had loosened the iron scale which was
on the membrane and caused the flaking. This flaking could possibly have
caused membrane damage. Although it is not possible to definitely determine
the cause of this increased salt flux, it is felt, had the membranes not
been allowed to become so heavily coated with iron, the observed change
in salt flux would not have occurred.
Another extremely important problem which developed during this study was
that of maintaining high permeation rates. As was shown in Figure 7, the
product water output from the unit would decline rapidly until very little
product water was being produced. Sodium hydrosulfite was found to be
effective in restoring the product water rate, but of course did not
remove the source of the fouling. The fouling was definitely associated
with the oxidation of iron (II) to iron (III) and subsequent precipita-
tion of a ferric hydrate on the membrane surface. This precipitate was
not present in the brine stream and therefore was occurring only at the
membrane surface where the concentration of ions is greatest. This
precipitation could have been a result of chemical oxidation, biological
oxidation, or a combination of both types of oxidation.
The rate of chemical oxidation of iron (II) to iron (III) is a function
of iron (II) and oxygen concentrations at the pH values of the mine water
in this study (12) (13). Singer and Stumm (13) report only 2 to 3% of the
iron (II) present in a synthetic acid mine water at pH 3 was oxidized in
three months time. Kim (12), however, reports much higher rates on
natural acid mine samples, but this could be accounted for by possible
bacterial oxidation of the iron. Since the Iron is being removed at the
surface of the membrane, and the concentration at the surface of the
membrane could reach as high as 5-10 times the feed stream concentration
(14), this could greatly accelerate the oxidation. Considering the
concentration of iron present in the feed waters utilized in this study,
about 10 pounds of iron was pumped through the unit daily. Assuming the
reaction rates presented by Singer and Stumm (13) were Increased 5 fold
due to the concentration at the membrane surface, this would represent
about a tenth of a pound of iron per day being oxidized to the trivalent
state and deposited on the membranes. Mass balances for iron as well as
the other ions present in the mine drainage are presented in the
Appendix (Tables 8 through 12). The iron balances check within ±6% and
show no trend which would indicate plating of iron on the membrane. This
is expected, since the probable amount of iron being precipitated is much
lower than the error in the mass balance. It seems reasonable to assume
-22-
-------
that this quantity of iron could cause a serious flux decline, since
other investigations have indicated iron fouling problems at much lower
iron concentrations than those found in this study.(7)(8)
In an attempt to determine if bacterial oxidation was a factor in the
iron fouling problem, a synthetic acid mine water sample was prepared.
Three modules from the experimental field unit were installed in a
laboratory test rig and operated on this synthetic water for a period of
46 hours. The water was disinfected with "Recall" a commercial dis-
infectant to insure a minimum of biological activity. The synthetic
water was mixed to closely simulate the composition of the actual mine
drainage shown in Table 2. The permeate rate from this test is plotted
as a function of time in Figure 11, and also plotted in Figure 11 is the
change in permeate rate of the field unit over a comparable time period
using the average permeate decline rate during the first 250 hours of
the field test. As may be seen, the slopes of the lines for the two
curves are almost identical. This would indicate that the iron fouling
problem is due to a purely chemical reaction at the membrane surface.
More research, however, is needed in this area to define adequately the
fouling mechanisms. Regardless of the exact mechanism of fouling, if
there were no oxygen in the feed stream, neither chemical or biological
oxidation could occur, since the iron bacteria are strict aerobes and
need oxygen in their metabolic cycle (15). These facts indicate complete
removal of oxygen from the feed stream could eliminate or greatly reduce
the fouling problems associated with iron.
Based on the data obtained in this study, it appears that it will be
technically feasible to utilize reverse osmosis in the treatment of acid
mine drainage, and a product water of high quality can be produced. More
research is needed on the causes of iron fouling, so that adequate steps
can be taken to minimize this problem. Until additional studies are made,
it is not possible to accurately predict the cost of treating acid mine
drainage by reverse osmosis, since membrane life and chemical costs for
cleaning the membrane are unknown.
Another important area of consideration is determination of the best
position for the reverse osmosis unit in the flow sheet for an acid mine
drainage treatment system. Preoxidation of the iron may result in longer
membrane life and reduction in chemical cleaning costs. Since membrane
life is also a function of pH, more economical operation may be obtained
by operating on preoxidized feed waters at near neutral pH. Other
factors which influence the flow sheet configuration include brine
disposal and raw water quality. Hence, many factors must be evaluated to
determine the best flow sheet for economical treatment of acid mine
drainage using reverse osmosis.
-23-
-------
7.0
0)
i s
£ |
* 2
6.0
Average Flux Rate during
first 250 hours of
Field Test
5.0
Operating Pressure 600 psj.g
Operating Temperature 53°
Laboratory Test on Synthetic,
Sterile Acid Mine Water
10
20
30 <*0 50
Operating Hours
60
70
80
FIGURE 11
COMPARISON OF THE RATE OF FLUX DECLINE
IN THE FIELD AND LABORATORY
-------
BIBLIOGRAPHY-
1. Hill, Ronald D. "Mine Drainage Treatment State-of-the Art and
Research Needs". U.S. Department of the Interior, Federal Water
Pollution Control Administration, Mine Drainage Control Activities;
Cincinnati, Ohio 45226, December 1968.
2. Barnes, H. L. and Romberger, S. B. "Chemical Aspects of Acid Mine
Drainage", Journal Water Pollution Control Federation, 40:3:371 (1968).
3. Patterson, D., "Membrane Compete for Separations Market", Chemical
Engineering, p. 38, (June 3, 1968).
4. Sudak, R. G., and Nusbaum, K., "Pilot Plant Operation of Spiral-Wound
Reverse Osmosis Systems", Gulf General Atomic Bulletin GA-8515.
5. Anonymous. "It's Full Speed Ahead for Reverse Osmosis", Chemical
Week. Aug. 3, 1968, pg. 40.
6. Riedinger, A., and Schultz, J. "Acid Mine Water Reverse Osmosis Test
at Kittanning, Pennsylvania. Research and Development Progress
Report #217, Office of Saline Water, Washington, D.C. (1966).
7. Furukawa, D., "Flushing Techniques to Restore Flux in Reverse Osmosis
Plants", Division of Research, U.S. Bureau of Reclamation, December 16,
1968.
8. Nusbaum, I., et al, "Reverse Osmosis Membrane Module", Research and
Development Report #338, Office of Saline Water, Washington, D.C.
(March 1968).
9. "Standard Methods for Examination of Water and Waste Waters", APHA,
AWWA, WPCF. American Public Health Association, New York, New York,
Twelfth Edition (1965).
10. "Drinking Water Standards", U.S. Department of Health, Education and
Welfare", Public Health Service, Washington, D.C. (1962).
11. American Water Works Association "Water Quality and Treatment",
AWWA Manual, Second Edition, 1951, ppg. 359-368.
12. Kim, Am G., "An Experimental Study of Ferrous Iron Oxidation in Acid
Mine Water". Presented Second Symposium on Coal Mine Drainage
Research, Mellon Institute, Pittsburgh, Pennsylvania, May 14-15, 1968.
13. Singer, P. and Stumm, W., "Kinetics of the Oxidation of Ferrous Iron".
Presented Second Symposium on Coal Mine Drainage Research, Mellon
Institute, Pittsburgh, Pennsylvania, May 14-15, 1968.
14. Merten, U., "Desalination by Reverse Osmosis". The M.I.T. Press,
Cambridge, Massachusetts, 1966.
-25-
-------
15. Starkey, Robert L., "Transformations of Iron by Bacteria in Water",
Journal American Water Works Association. 37:(1945) pg. 963.
ACKNOWLEDGMENTS
The study reported herein was performed by the Technical Center of
Rex Chainbelt Inc., Milwaukee, Wisconsin, via a contract with the
Commonwealth of Pennsylvania, Department of Mines and Mineral
Industries. The report was authored by Donald G. Mason, Manager,
Systems Research. Partial funding for this project was provided by
the Federal Water Pollution Control Administration, Department of
the Interior under Grant No. 14010 DYK. Technical assistance was
provided by Havens International. Assistance in site selection and
obtainment of easements was provided by personnel of the Department
of Mines and Mineral Industries, Commonwealth of Pennsylvania.
PUBLICATIONS
Results of this study will be presented in a paper entitled, "Treat-
ment of Acid Mine Drainage by Reverse Osmosis." This paper will be
presented at the Third Symposium on Coal Mine Drainage Research, at
the Mellon Institute, Pittsburgh, Pennsylvania on May 19-20, 1970.
-26-
-------
APPENDIX
-27-
-------
Table 5
PRODUCT WATER
Elapsed
Operating
Time
30
310
355
452
465
480
506
530
555
580
605
634
650
675
720
739
755
807
Calcium
10
0
5
35
36
39
40
45
43
40
47
33
31
34
32
38
33
33
Magnesium
15
20
17
35
35
40
44
45
42
38
33
36
33
32
32
32
32
30
(PERMEATE)
Maganese
(MtfH-)
.9
0
.5
3.1
2.3
3.3
3.2
3.6
3.9
3.2
2.0
2.3
2.7
2.5
2.7
2.6
2.5
2.7
ION BALANCE
Iron
(Fe++)
6.1
7.9
6.8
16.1
17.0
18.8
20.6
21.0
21.0
19.3
11.9
17.0
15.2
15.0
14.3
16.8
14.5
15.0
Sulfate
(S04)~~
41.6
49.9
30.2
106.1
109.2
119.6
122.7
131.0
124.8
114.4
78.0
105.0
93.6
91.5
88.4
99.8
95.7
87.4
Summation
of Ions
-9.6
-22.0
-0.9
-16.9
-18.9
-18.5
-14.9
-16.4
-14.9
-13.9
+15.9
-16.7
-11.7
-8.0
-7.4
-10.4
-13.7
-6.7
All values in mg/1 as Ca(X>3.
-28-
-------
Table 6
FEED WATER ION BALANCE
Elapsed
Operating
Time
30
124
165
256
310
355
390
410
452
465
480
506
530
555
580
605
634
650
675
720
739
755
807
Calcium
(Ca'H')
350
350
340
175
180
250
350
350
360
358
360
360
358
360
357
356
355
360
356
370
365
360
365
Magnesium
(Mg-H-)
425
425
440
605
520
500
430
430
420
417
395
416
418
420
419
409
425
420
444
450
455
460
455
Manganese
(MtfH-)
29
35
__
32
24
26
27
32
35
29
28
20
28
28
34
33
32
32
Iron
(Fe"H")
202
260
188
206
215
215
213
204
206
211
204
211
213
215
202
208
209
215
Sulfate
(S04f
1196
1352
1040
1144
1144
1196
1196
1118
1092
1144
1108
1118
1066
1118
1092
1118
1118
1378
Summation
of Ions
-190
__
-392
-67
__
-126
-130
-200
-180
-106
-71
-128
-111
-107
-45
-75
-36
-57
-57
-311
All values in mg/1 as CaC03.
-29-
-------
Table 7
BRINE (CONCENTRATE) ION BALANCE
Elapsed
Operating
Time
30
310
355
452
465
480
506
530
555
580
605
634
650
675
720
739
755
807
All values in mg/1 as CaC03.
Calcium
Ca++
1600
275
350
434
453
470
490
550
538
520
463
875
885
870
635
910
920
740
Magnesium
(M£++)
1800
900
700
534
557
555
610
540
662
570
537
925
1065
1030
715
1190
1230
925
Manganese
(Mn**)
146
400
56
32
27
41
42
49
53
43
45
81
74
68
50
82
84
65
Iron
(Fe^)
997
394
252
265
249
281
277
299
303
301
249
519
532
496
358
537
546
430
Sulfate
(SO^)
5824
1872
1331
1378
1274
1456
1560
1690
1690
1612
1430
2756
2834
2600
2080
2912
2964
2314
Summation
of Ions
-1281
+97
+27
-113
+12
-109
-141
-252
-134
-178
-136
-356
-278
-136
-322
-193
-184
-1054
-30-
-------
Table 8
Feed
gpm x mg/1
30 8.3 113
124 7.87 113
165 7.10 112
225 7.20 118
256 6.40 143
310 6.35 145
355 7.00 105
390 6.35 114
410 6.55 114
436 6.26 109
452 7.16 115
465 6.32 120
480 6.17 120
506 6.52 119
530 6.55 114
555 6.50 115
580 6.45 118
605 6.54 114
634 7.42 118
650 7.45 119
675 7.35 120
720 7.70 113
735 7.50 116
755 7.30 117
807 6.80 120
IRON (II) MASS
Concentrate
gpm x
1.9
2.7
2.5
4.4
4.2
4.15
4.80
5.40
5.55
4.93
4.75
4.85
4.50
4.25
4.10
4.10
4.10
4.40
2.70
2.80
2.90
4.30
2.45
2.40
2.8
mg/1
540
350
330
205
223
220
141
133
134
135
148
139
157
155
167
169
168
139
290
297
277
200
300
305
240
BALANCE
Permeate
Mass
in
+ gpm x mg/1 (gpm) (mg/1)
6.40
5.17
4.60
2.8
2.2
2.2
2.2
0.95
1.00
1.33
1.41
1.47
1.67
2.27
2.45
2.40
2.35
2.14
4.72
4.65
4.65
3.40
5.05
4.9
4.0
3.4
2.7
2.65
2.6
4.0
4.4
3.8
.75
6.2
8.5
9.0
9.5
10.5
11.5
11.75
11.75
10.8
6.65
9.5
8.5
8.4
8.0
9.4
8.1
8.4
937.9
889.3
795.2
849.6
915.2
940.8
735.0
723.9
746.7
682.3
823.4
758.4
740.4
775.9
746.7
747.5
761.1
745.6
875.6
886.6
882.0
870.1
870.0
854.1
816.0
Mass
out
(gpm) (mg/1) Error
1047.8
959.0
837.2
909.3
945.4
922.7
685.2
718.9
739.9
676.9
715.7
688.1
724.0
684.9
713.5
721.1
714.2
625.8
827.8
871.1
840.7
887.2
782.5
771.7
705.6
-11.73
-7.84
-5.28
-7.03
-3.03
-0.21
+6.78
+0.69
-0.43
+0.79
+13.08
+9.27
+2.22
+11.73
+4.45
+3.53
+6.16
+16.07
+5.46
+1.75
+4.68
-1.97
+10.06
+9.65
+13.53
-31-
-------
Table 9
MAGNESIUM MASS BALANCE (as CaC03)
Time
Hours
30
124
165
256
310
355
390
410
452
465
480
506
530
555
580
605
634
650
675
720
739
755
807
Feed
gpm x
8.3
7.87
7.10
6.40
6.35
7.0
6.35
6.55
7.16
6.32
6.17
6.52
6.55
6.50
6.45
6.54
7.42
7.45
7.35
7.70
7.50
7.30
6.80
mg/1
425
425
440
605
520
500
430
430
420
417
395
416
418
420
419
409
425
420
444
450
455
460
455
Concentrate
« gpm x
1.9
2.7
2.5
4.2
4.15
4.8
5.4
5.55
4.75
4.85
4.50
4.25
4.10
4.10
4.10
4.40
2.70
2.80
2.90
4.30
2.45
2.40
2.80
mg/1
1800
1300
1200
950
900
700
538
530
534
557
555
610
540
662
570
537
925
1065
1030
715
1190
1230
925
Permeate
+ gpm x
6.4
5.17
4.6
2.2
2.2
2.2
0.95
1.00
1.41
1.47
1.67
2.27
2.45
2.40
2.35
2.14
4.72
4.65
4.45
3.40
5.05
4.90
4.00
mg/1
15
10
12
20
20
17
7
20
35
35
40
44
45
42
38
33
36
33
32
32
32
32
30
Mass
in
(gpm) (mg/1)
3528
3345
3124
3872
3302
3500
2731
2817
3007
2635
2437
2712
2738
2730
2703
2675
3154
3129
3263
3465
3413
3358
3094
Mass
out
(gpm) (mg/1)
3516
3562
3055
4034
3779
3397
2912
2962
2586
2753
2564
2692
2324
2815
2426
2433
2667
3135
3129
3183
3077
3109
2710
%
Error
40.33
-6.49
+2.20
-4.18
-14.45
+2.94
-6.63
-5.15
+14.00
-4.48
-5.21
+0.74
+15.12
-3.11
+10.25
+9.05
+15.44
-0.19
+4.11
+8.14
+9.84
+7.42
+12.41
-32-
-------
Table 10
CALCIUM MASS BALANCE (as Ca3)
Time
Hours
30
124
165
256
310'
355
390
410
452
465
480
506
530
555
580
605
634
650
675
720
739
755
807
Feed
gpm x
8
7
7
6
6
7
6
6
7
6
6
6
6
6
6
6
7
7
7
7
7
7
6
.30
.87
.10
.40
.35
.00
.35
.55
.16
.32
.17
.52
.55
.50
.45
.54
.42
.45
.35
.70
.50
.30
.8
mg/1
350
350
340
175
180
250
350
350
360
358
360
360
358
360
357
356
355
360
356
370
365
360
365
Concentrate
» gpm a
1.9
2.7
2.5
4.2
4.15
4.80
5.40
5.55
4.75
4.85
4.50
4.25
4.10
4.10
4.10
4.40
2.70
2.80
2.40
4.30
2.45
2.40
2.8
t mg/1
1600
1000
950
400
275
350
406
405
434
453
470
490
550
538
520
463
875
885
870
635
910
920
740
Permeate
gpm x
6.40
5.17
4.60
2.2
2.2
2.2
0.95
1.00
1.41
1.47
1.67
2.27
2.45
2.40
2.35
2.14
4.72
4.65
4.45
3.40
5.05
4.90
4.0
mg/1
10
10
8
0
0
5
6
25
35
36
39
40
45
43
40
47
33
31
34
32
38
33
33
Mass
in
(gpm) (mg/1)
2905
2754
2414
1120
1143
1750
2222
2292
2577
2262
2221
2347
2344
2340
2302
2328
2634
2682
2616
2849
2737
2628
2482
.0
.5
.0
.0
.0
.0
.5
.5
.6
.6
.2
.2
.9
.0
.7
.2
.1
.0
.6
.0
.5
.0
.0
Mass
out
(gpm) (mg/1) Error
3104.0
2751.7
2411.8
1260.0
1141.3
1691.0
2198.1
2272.8
2110.9
2250.0
2180.1
2173.3
2365.3
2309.0
2226.0
2137.8
2518.3
2622.2
2674.3
2839.3
2421.4
2369.7
2204.0
-6.85
+0.12
+0.09
12.50
+0.15
+3.37
+1.12
+0.88
+18.12
+0.57
+1.84
+7.40
-0.87
+1.32
+3.34
+8.85
+4.39
+2.23
-2.19
+0.34
+11.56
+9.83
+11.20
-33-
-------
Table 11
30
124
165
225
256
310
355
390
410
436
465
452
480
506
530
555
580
605
634
650
675
720
739
755
807
Feed
gpm x
8.3
7,
7,
87
10
7.2
6,
6.
7.
6,
7.
6.
,40
.35
,00
,35
6.55
6.26
6.32
.16
.17
6.52
6.55
6.5
6.45
6.54
.42
.45
.35
7.7
7.5
7.3
6.8
7,
7,
7,
1150
1160
1150
1100
1060
1300
1000
1075
1125
1000
1100
1100
1150
1150
1075
1050
1100
1065
1075
1025
1075
1050
1075
1075
1325
SULFATE MASS
Concentrate
gpm x
1.9
2.7
2.5
4.4
4.2
4.15
4.8
5.4
5.55
4.93
4.85
4.75
4.50
4.25
4.1
4.1
4.1
4.4
2.7
2.8
2.9
4.3
2.45
2.4
2.8
mg/1
5600
3600
3250
1700
1600
1800
1280
1100
1150
1375
1225
1325
1400
1500
1625
1625
1550
1375
2650
2725
2500
2000
2800
2850
2225
BALANCE
Permeate
+ gpm x
6.40
5.17
4.60
2.8
2.2
2.2
2.2
0.95
1.0
1.33
1.47
1.41
1.67
2.27
2.45
2.4
2.35
2.14
4.72
4.65
4.45
3.4
5.05
4.9
4.0
mg/1
40
29
28
28
27
48
29
23
79
40
105
102
115
118
126
120
110
75
101
90
88
85
96
92
84
Mass
in
(gpm) (mg/1)
9545
9129
8165
7920
6784
8255
7000
6826
7369
6260
6952
7876
7096
7498
7041
6825
7095
6965
7977
7636
7901
8085
8063
7848
9010
Mass
out
(gpm) (mg/1)
10896
9870
8254
7558
6779
7676
6208
5962
6462
6898
6096
6438
6492
6643
6971
6951
6614
6211
7632
8049
7642
8889
7345
7291
6566
Z
Error
-14.15
-8.12
-1.09
44.57
40.07
+8.23
+11.31
+12.66
+12.31
-10.19
+12.31
+18.26
+8.51
+11.40
+0.99
-1.85
+6.78
+10.83
+4.32
-5.41
+3.28
-9.94
+8.90
+7.10
+27.13
-34-
-------
Table 12
MANGANESE MASS BALANCE
Total
Hours
30
355
452
465
480
506
530
555
580
605
634
650
675
720
739
755
807
Feed
gpm x
8.3
7.00
7.16
4.32
6.17
6.52
6.55
6.50
6.45
6.54
7.42
7.45
7.35
7.7
7.5
7.3
6.8
mg/1
16.0
19.0
17.4
13.4
14.5
15.0
17.5
14.0
15.8
15.2
11.2
15.2
15.3
18.8
18.0
17.7
17.5
Concentrate
- gpm x
1.9
4.80
4.75
4.85
4.50
4.25
4.10
4.10
4.10
4.40
2.7
2.8
2.9
4.3
2.45
2.4
2.8
mg/1
80
31
17.4
15.0
22.5
23.0
27.0
29.0
23.8
24;5
44.5
40.5
37.3
27.5
45.2
46.4
35.5
Permeate
+ gpm x
6.4
2.2
1.41
1.47
1.67
2.27
2.45
2.40
2.35
2.14
4.72
4.65
4.45
3.4
5.05
4.9
4.0
mg/1
0.50
0.3
1.7
1.25
1.80
1.75
2.00
2.15
1.75
1.10
1.25
1.50
1.40
1.50
1.42
1.40
1.50
Mass
in
(gpm) (mg/1)
132.8
133.0
124.6
84.7
89.5
97.8
114.6
123.5
101.9
99.4
83.1
113.2
112.5
144.8
135.0
129.2
119
Mass
out
(gpm) (mg/1)
155.2
149.5
85.0
74.6
104.3
101.7
115.6
124.1
101.7
110.2
126.1
120.4
114.4
123.4
117.9
118.2
105.4
%
Error
-16.87
-12.41
+31.78
+11.92
-16.54
-3.99
-0.87
-0.49
+0.20
-10.87
-51.74
-6.36
-1.69
+14.78
+12.67
+8.51
+11.43
-35-
HO. S. GOVERNMENT PRINTING OFFICE : 19TO O - 387-88 J
-------
BIBLIOGRAPHIC:
Technical Center, Rex Chainbelt, In-
corporated, Treatment of Acid Mine
Drainage by Reverse Osmosis, F/JviA. Pub-
lication Ho. 14010DYK Q3/70, llarch 1970
ABSTRACT
The objective of the study was to
determine the feasibility of utiliz-
ing reverse osmosis to treat acid mine
drainage, and produce a water which
could be used by industry or as a
municipal water supply.
| A 10,000 gpd demonstration unit was
i
ACCESSION NO.
KEY WORDS:
Reverse Osmosis
Acid Mine Drainage
Demineralization
BIBLIOGRAPHIC:
Technical Center, Rex Chainbelt, In-
corporated, Treatment of Acid Hine
Drainage by Reverse Osmosis, F.VQA Pub-
lication No. 14010DYK Q3/70, I-5arch 1970
ABSTRACT
The objective of the study was to
determine the feasibility of utiliz-
ing reverse osmosis to treat acid mine
drainage, and produce a water which
could be used by industry or as a
municipal water supply.
A 10,000 gpd demonstration unit was
ACCESSION NO.
WORDS:
Reverse Osmosis
Acid Mine Drainage
Deraine ralizat ion
BIBLIXRAPHIC:
Technical Center, Rex Chainbelt, In-
corporated, Treatment of Acid iline
Drainage by Reverse Osmosis, FJviA. Pub-
lication No. 14010DYK 03/70, March 1970
ABSTRACT
The objective of the study was to
determine the feasibility of utiliz-
ing reverse osmosis to treat acid mine
drainage, and produce a water which
could be used by industry or as a
municipal water supply.
A 10,000 gpd demonstration unit was
ACCESSION NO.
KEY WORDS:
Reverse Osmosis
Acid Mine Drainage
Demineralizat ion
-------
constructed and tested for 35 days on
acid mine drainage near Shickshinny,
Pennsylvania. The results obtained
indicated that the reverse osmosis pro-
cess has potential application. There
are, however, operational problems
which must be solved prior to utiliz-
ing reverse osmosis on a large scale.
These include maintenance of high per-
meation rates through the membrane by
reducing membrane fouling and deter-
mination of the optimum flow sheet for
an acid mine treatment system utiliz-
ing reverse osmosis.
constructed and tested for 35 days on
acid mine drainage near Shickshinny,
Pennsylvania. The results obtained
indicated that the reverse osmosis pro-
cess has potential application. There
are, however, operational problems
which must be solved prior to utiliz-
ing reverse osmosis on a large scale.
These include maintenance of high per-
meation rates through the membrane by
reducing membrane fouling and deter-
mination of the optimum flow sheet for
an acid mine treatment system utiliz-
ing reverse osmosis.
constructed and tested for 35 days on
acid mine drainage near Shickshinny,
Pennsylvania. The results obtained
indicated that the reverse osmosis pro-
cess has potential application. There
are, however, operational problems
which must be solved prior to utiliz-
ing reverse osmosis on a large scale.
These include maintenance of high per-
meation rates through the membrane by
reducing membrane fouling and deter-
mination of the optimum flow sheet for
an acid mine treatment system utiliz-
ing reverse osmosis.
-------
As the Nation's principal conservation agency, the Department of the
Interior has basic responsibilities for water, fish, wildlife, mineral, land,
park, and recreational resources. Indian and Territorial affairs are other
major concerns of America's "Department of Natural Resources."
The Department works to assure the wisest choice in managing all our
resources so each will make its full contribution to a better United
States-now and in the future.
14010 DYK 03/70
------- |