EPA-600/2-80-052
June 1980
EVALUATION OF SORBENTS FOR INDUSTRIAL SLUDGE LEACHATE TREATMENT
by
Paul C. Chan
John W. Liskowitz
Angelo Perna
Richard Trattner
New Jersey Institute of Technology
Newark, New Jersey 07102
Grant No. R 803717 02
Project Officer
Mary K. Stinson
Industrial Pollution Control Division
Industrial Environmental Research Laboratory
Environmental Protection Agency
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publi-
cation. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
ii
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FOREWORD
When energy and material resources are extracted, processed, converted
and used, the related pollutional impacts on our environmental and even on '
our health often require that new and increasingly more efficient pollution
control methods be used. The Industrial Environmental Research Laboratory
Cincinnati (TERL-Ci) assist in developing and demonstrating new and improved
methodologies that will meet these needs both efficiently and economically.
This report deals with the investigation of leachate contaminant control
using sorbents. Ashes, clays, and refined materials were tested under
laboratory and pilot-scale conditions to determine their capacity to remove
leachate contaminants produced from three industrial sludges — calcium
fluoride, metal hydroxide, and petroleum. The report will provide useful
data to government agencies and industries contemplating control of residue
leachate from industrial sludge impoundment via sorbent contact.
For further information concerning this subject the Industrial
Pollution Control Division should be contacted.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
ill
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ABSTRACT
A laboratory and outdoor pilot-scale investigation was conducted on the
use of selected sorbents for removing leachate contaminants from three in-
dustrial sludges.
The laboratory results indicated that rather than a single sorbent, a
combination of acidic and basic sorbents is required in a layered system for
removal of all the measurable contaminants from the leachates. These com-
binations are illite, vermiculite, and a natural zeolite for the acidic
leachate; illite, acidic fly ash for the neutral leachate, and illite,
kaolinite, and a natural zeolite for the alkaline leachate. The sorbent
capacities exhibited by the natural sorbents are comparable to those ex-
hibited by refined sorbents.
The outdoor pilot study, which was limited to the treatment of the
calcium fluoride sludge leachate, using lysimeters, some 80 times larger
than the laboratory lysimeters, revealed that the sorbent effectiveness
depends on the velocity of the leachate through the sorbents and the sorbent
removal capacity for specific contaminants. Except for magnesium effective
reductions of the measurable leachate constituents were achieved with the
use of illite, acidic fly ash, and a zeolite in the weight ratio of 2:2:1.
Sorbent costs have been estimated for various combinations required
for treating leachate from calcium fluoride sludge over a 10 year period
of landfill operation. For the illite/acidic fly ash/zeolite combination
and the illite/acidic fly ash/basic fly ash combination, costs are $1.37
and $0.45 per ton of sludge, respectively.
This report was submitted in fulfillment of Grant No. R-803717-02 by
New Jersey Institute of Technology under the sponsorship of the U.S. Environ-
mental Protection Agency. This report covers the period June 1, 1976 to
September 30, 1978 and work completed as of June 1, 1979.
iv
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CONTENTS
Page
Foreword
Abstract
v
Figures [[[ vi
Tables [[[ vii
Acknowledgment ..................................... viii
1. Introduction ........................... i
2 . Conclusions ................................ 3
3 . Recommendat ions ............................ 5
4 . Materials and Methods ............................. 6
5 . Results and Discussion .......................... 11
6. Proposed Designs for a Calcium Fluoride Sludge Leachate
Treatment System ............................... 37
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FIGURES
Number Page
1 Laboratory Arrangement of Lysimeters 7
2 Schematic Diagram of Pilot Scale Study 9
3 Lysimeter Effluent pH for Calcium Fluoride Sludge Leachate.. 13
4 Lysimeter Effluent pH for Metal Finishing Sludge Leachate... 14
5 Lysimeter Effluent pH for Petroleum Sludge Leachate 15
6 Effect of Leachate Velocity on Fluoride Removal in Calcium
Fluoride Sludge Leachate 24
7 Effect of Leachate Velocity on COD Removal in Calcium
Fluoride Sludge Leachate 25
8 Effluent Calcium Concentration in Pilot-Scale Lysimeter
Study 30
9 Effluent Copper Concentration in Pilot-Scale Lysimeter Study 31
10 Effluent Magnesium Concentration in Pilot-Scale Lysimeter
Study 33
11 Effluent Fluoride Concentration in Pilot-Scale LysjLmeter
Study 34
12 Effluent Cyanide Concentration in Pilot-Scale Lysimeter Study
Study 35
13 Effluent Organics (COD) Concentration in Pilot-Scale
Lysimeter Study 36
14 System 1 Design for Leachate Treatment System 46
15 System 2 Design for Leachate Treatment System 47
vi
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TABLES
Number
Page
Concentrations of Specific Cations, Anions, and Organics in
the Three Industrial Sludge Leachates 12
Net Sorbent Removal Capacities for Treating Acidic Petroleum
Sludge Leachate 17
Net Sorbent Removal Capacities for Treating Neutral Calcium
Fluoride Sludge Leachate 18
Net Sorbent Removal Capacities for Treating Basic Metal
Finishing Sludge Leachate. ; 19
Capacity of Natural Sorbents for Removing Specific
Contaminants from Acidic, Neutral and Basic Leachate 20
Relationship of Copper and Zinc Concentrations to Leachate pH. 22
7 Sorbent Capacity Exhibited by Illite for Removal of Fluoride
and COD at Different Leachate Velocities Through Sorbents 23
8 Comparison of the Most Effective Natural Sorbent for Specific
Contaminants with Activated Alumina and Activated Carbon in
Acidic, Neutral, and Basic Leachates 27
9 Removal Capacities of Combined Srobents in Various Lysimeter
Arrangements for Neutral Calcium Fluoride Sludge Leachate 28
10 Analysis of the Neutral Calcium Fluoride Sludge Leachate
Used to Obtain Sorbent Combinations for Optimum Treatment 29
6
vii
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ACKNOWLEDGMENT
The authors are deeply indebted to Mary K. Stinson, Metal and Inorganic
Chemical Branch, Industrial Environmental Research Laboratory, U.S. Environ-
mental Protection Agency, Cincinnati, Ohio, for her guidance in this project
They also wish to express their appreciation to the following companies
for their cooperation in supplying the sorbents used in this study: Georgia
Kaolin Company, Elizabeth, New Jersey (kaolinite); Double Eagle Petroleum
and Mining Company, Casper, Wyoming (zeolite); Public Service Electric and
Gas Company, Hudson Generating Station, Jersey City, New Jersey (fly ash).
The efforts of Mung Shium Sheih and Tak Hoi Lee, graduate students in
the Institute are acknowledged in conducting the various experiments. In
particular, they thank Mr. Sheih for his large contribution in various
phases of the project.
The authors are especially appreciative of Mrs. Irene Mitchell and
Mrs. Julia Martucci for their patience and skillful typing of the entire
manuscript.
viii
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SECTION 1
INTRODUCTION
.rsSLrs.-S1B
The disposal of sludges by landfill can lead to heavy metal
anion, and organic contamination of surface and ground watlrs by i
h
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A number of investigators have shown that the following pollutants in 1
leachates and waste streams are attenuated by clay minerals, soils and waste
products: organics (e.g., phenols2, surfactants3, pyridine^»5 and other or-
ganics characterized by chemical oxygen demand (COD)6), pesticides (e.g.
parathion7, DDT, dieldrin and heptachlor8), herbicides (e.g., paraquet*),
heavy metals (e.g., lead, cadmium, mercury, zinc, mangenese, copper 10-14)
and toxic anions (e.g., chromium VI, arsenic and seleniumIS). However, no-
one has really explored the use of fly ash-clay sorbent mixtures to any
great extent.
This investigation has been concerned with: (1) defining the clay/
fly ash combinations that are most effective in removing the heavy metals,
toxic anions, and organics present in leachates originating from industrial
sludges; (2) examining the effect on contaminant removal of such factors as
leachate pH and velocity through the sorbent, and (3) establishing a design
approach for this treatment.
The sludges used in this study were a calcium fluoride sludge (of the
type generated by the electronics and aircraft industries), a metal finishing
sludge, and a petroleum sludge. These sludges were selected because their
annual production is of significant magnitude to present disposal problems.
The leachate from these sludges exhibited pH's that were neutral, basic, and
acidic. Also, they were expected to contain a cross section of heavy metal
hydroxides, cyanide, fluoride, and organics.
The sorbents selected for this study were acidic and basic fly ashes,
vermiculite, illite, kaolinite, and a natural zeolite. Activated alumina
and activated carbon, which are presently being used for the removal of
cations, anions, and organics in industrial waste streams and potable water
supplies, were included in the study for comparison purposes.
This investigation consisted of two phases: (1) continuation of the
laboratory study described in a recent report by the U.S. Environmental
Protection Agency (EPA)16 to define design parameters for treating industrial
sludge leachates, and (2) an outdoor pilot-scale study designed to treat 5JU
liters of leachate. The pilot study was limited to calcium fluoride sludge
leachate because the fluoride levels of this sludge range from 5 to 20 mg/1
and there is currently no inexpensive treatment process to reduce the fluo-
ride concentration to 1 mg/1 or less.
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SECTION 2
CONCLUSIONS
^
-y^^
respectively C1h1Um "T^' \nd baSiC metal fi*is^ sludge leachates,
respectively. The capacities exhibited by these sorbents for the removal
of contaminants from these three leachates are comparable to those exhibited
and flvV^h 3 K^ actlvated carb°n- The combinations of naturaf clay
t»ln V beCaUSe "° Slngle sorbent can rem°ve all of the con-
taminants present in the industrial sludge leachates examined.
anH flBOt\PH C°ntr01 °f the leachate and the order that the natural clays
and fly ashes are used in a layered bed influence the removal of the cations
'1 *" 1"du '
'1 *" 1"dus"ial slud^ leachates.
a-s illite . Acidic sorben s
acidic
^^
are
Alkaline conditions at the base of the bed are desirable, since thev
favor the removal of both the cations in the leachate and the heavy" meta!
cations initially leached from specific sorbents at leachate
"
thtl e h ve n -n
this initial leaching of heavy metal ions by the acidic sorbents.
In the design of a sorbent system, the total amount of a specific
" ? " °r8aniC? rem°Ved ±S indlcated ^ the sorbent removal
^^
sra;;^^^^
^^^^^^ ZZXttX ZZ* bed
material added to the clays to regulate their permeability, or by varying
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the particle size of the sorbents in the bed.
The illite, acidic fly ash, and zeolite combination in the weight
ratio of 2:2:1 was found to be effective for treating the measurable con-
taminants (except magnesium) in calcium fluoride sludge leachate on a pilot
scale. The copper and fluoride ions, which are considered toxic, were re-
duced to concentration levels generally acceptable for potable water supplies
A calcium ion concentration of over 300 mg/1 in leachate was reduced to 80
mg/1; a copper ion concentration of 0.12 mg/1 was reduced to 0.04 mg/1; the
fluoride ion concentration was reduced from 15 to 1 mg/1; the total cyanide
was reduced from 0.37 to about 0.06 mg/1, and the COD was reduced from about
45 to 15 mg/1. The magnesium ion concentration was only reduced from^76 to
about 53 mg/1. In addition, except for magnesium and COD, the resulting
effluent concentration was found to be independent of influent concen-
trations. Thus, variations in the concentrations of the contaminants in a
leachate should not influence the effectiveness of a treatment system con-
taining the natural clay/fly ash sorbent combinations.
Sorbent cost for the illite, acidic fly ash, and zeolite combination
in the weight ratio of 2:2:1 required for the treatment of the leachate
during a 10-year period of landfill operation was estimated to be $1.37/ton
of sludge disposed of in the landfill. This cost is based on an annual
rainfall of 102 cm (40 in) and assumes that all the precipitation that falls
on the landfill becomes leachate. This cost may be reduced to only $0.45/
ton of sludge disposed of in the landfill if the illite, acidic fly ash, and
basic fly ash combination in the weight ratio of 2:2:1 is used. Based on
the laboratory lysimeter results, the illite, acidic fly ash, and basic fly
ash combination appears promising for the treatment of the measurable con-
taminants except for the calcium ion in the calcium fluoride sludge leachate.
This combination was not evaluated on a pilot scale because of the limited
time available under this grant.
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SECTION 3
RECOMMENDATIONS
dicatedt 3 reSUU °f ^^ StUdleS> three additional investigations are in-
r.
combinations for treatment of industrial ^/^"u^ fly ash/clay ^orbent
conditions. Test cells containi^^ , ^ S\leaChateS Under actual "*"
field. Both the use of a sorbent'bed andl^ " "' Constructed *» the
combination should be evaluated ™ „ "" Contalnin8 the sorbent
by other potential users But beforfthis project 3Vallable/°r inspection
scale evaluation of the illite/acidlr fit Z,l* initiated, a pilot
examined l-'S.^.loS^SiS^^i^ 'b^" ^^ ^
for treating nickel, in neutrafand Lli ?! " S°rbent combinations
cadmium, mercury and arsenic in ^d^ "eutr'l^d Ssi'T' ?*' ^^^
^
leachate through the sorbents should b^ f f ^ ^^^ velocity of
*° ""6 the m°St
removal of all of the above constituents £ *° "T"6 the m°St e««ti
for potential users to set UD Dilof ?' ^° results would Provide data
data necessary for fielfuse! PllOt-SCale studles s° °btain the engineering
technology LPtheefield°ondleLhnter,taken tO demonst"te the use of this
landfill^ Means to collet "e lelch^te'ffrr^:11 ^ ^ eXiS"n8 ^dustrial
Analysis of the leachate ^ould be carried o'ut 'rS-r^K "" reqUlred'
^L^::^
^^.^LTS
up in the field to identifv tL ™« ?' Test.sorbent beds would then be set
*
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SECTION 4
MATERIALS AND METHODS
The preparation of the industrial sludge leachates and the analytical
procedures utilized in this study are discussed in the final report*6 cover-
ing the first phase of this study.
LABORATORY LYSIMETER STUDIES
Laboratory lysimeter studies were conducted using 500 g of each sor-
bent material. Since "pure" clay lysimeters did not exhibit adequate per-
meability characteristics, illite, kaolinite, vermiculite, and zeolite were
prepared as a mixture consisting of 80 percent inert Ottawa sand and 20
percent clay. This ratio was arrived at after a series of studies estab-
lished that this figure would permit adequate flows of leachate through
these sorbents.
Lysimeters used in the laboratory were constructed of plexiglass
tubing (6.2-cm ID, 0.6-cm wall thickness, 90-cm length) supported in a
vertical position. The laboratory arrangement of the lysimeters is shown
in Figure 1. A 164-micron pore size corundum disc (6.10-cm diameter, 0.6-cm
thickness) was placed in each column directly over the drain hole to prevent
clogging of the outlet and also to support the sorbent material. The column
was packed with the preweighed sorbent, with 3 to 4 cm of Ottawa sand below
and above the sorbent to prevent disturbing the geometry of the sorbent
column during addition of leachate or water. The packed column was then
slowly wetted with leachate to allow total saturation and to force all
entrapped air in the soil voids out of the column packing. After a satur-
ation period of at least 24 hours, the column was filled with leachate to
the level of an overflow drain that had been tapped into the top side of the
column in order to maintain a constant head condition. Leachate was fed to
the top of the column through a valved manifold that distributed the leachate
simultaneously to 10 lysimeters, from a central reservoir. The central
reservoir, a 100 liter polyethylene carboy, delivered the leachate to the
manifold system by means of a gravity syphon feed arrangement. Any overflow
from the constant head drains was collected and pumped back up to the central
reservoir. All tubing in the system was made of Tygon tubing 9.5 mm ID
(3/8 in). A constant hydraulic head was maintained in the lysimeters at all
times, and the volume of leachate passing through the columns was continu-
ously monitored. Samples of leachate effluent were analyzed at predetermined
intervals for pH and the concentrations of all measurable constituents re-
maining in the effluent. This procedure was continued until breakthrough
for all measurable contaminants had occurred or until excessively low
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permeabilities were encountered. Breakthrough was defined as that condition
when the concentration of the species of concern in the collected effluent
sample approached or exceeded that in the influent. After breakthrough was
achieved, water was continually passed through the spent sorbent bed until
the cations, anions and organics removed by the sorbents were below measur-
able levels in the effluent. The sorbent capacity exhibited by each sorbent
represents the total amount of specific cation, anion, or organic retained
by the sorbent after extensive water washing.
PILOT STUDIES
To evaluate the use of the clay/fly ash combination for the treatment
of industrial sludge leachates on a pilot scale, two large vertical lysi-
meters were set up outdoors. This outdoor system consisted of an agitator,
filtration column, storage tank, and constant head lysimeter. (See Figure 2).
Calcium fluoride sludge was collected from the same source over a
period of a year to take advantage of changes in production schedules and
processes that could lead to compositional changes in the leachate. In this
manner, the effect of compositional changes on the removal efficiency of
the natural clay/fly ash sorbent combinations could be studied.
The preparation of sludge leachate for the outdoor study was as
follows: A sample of each batch of sludge was dried at 103°C to constant
weight to determine its moisture content. The unaltered sludge was then
mixed with water in a ratio of 2.5 ml water/g of dried sludge and mechani-
cally stirred for 24 hours. The resulting mixture was then filtered through
a multimedia filter bed. The filter bed, which was housed in a stainless
steel column, consisted of 5 layers of filter sand and gravel: The top
layer was uniform medium gravel with D5Q - 19.1 mm (particle sizes are such
that 50 percent passed through a sieve with a spacing of 19.1 mm) and a
thickness of 7.6 cm; the second layer from the top was a fine gravel with
D0[. = 16.8 mm and D = 14.2 mm, and a thickness of 7.6 cm; the third layer
85 15
was a coarse sand with Dg = 6.3 mm and D15 =5.1 mm, and a thickness of
10.2 cm; the fourth layer was medium sand with Dg<- = 1.47 mm and D^5 = 1.2
mm, and a thickness of 10.2 cm; and the bottom layer was #20 - #30 Ottawa
sand with D n = 0.715 mm and a thickness of 22.9 cm. This arrangement of
gravel and sand in the filter bed was based on the results of a series of
measurements using different sizes of gravel and sand to provide an effluent
whose suspended particles would not clog the bed.
The outdoor lysimeters were constructed of PVC pipe (40.6 cm OD)
4.8 mm wall thickness and 1.52 m length supported by lucite plates in a
vertical position. The general configuration and features of the field
lysimeter are similar to those of the laboratory lysimeters described
earlier. The use of identical lysimeters provided a measure of the repro-
ducibility of the sorbent system. Both lysimeters were packed with enough
preweighed sorbent to treat 530 liters of leachate. Five to 10 cm of Ottawa
sand was placed below and above the sorbents to prevent disturbing the
8
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Agitation
Filtration
Column
Storage
Reservoir
Constant Head
Lysimeter
Chemical
Analysis
Figure 2. Schematic diagram of pilot scale study.
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geometry of the sorbents during addition of leachate. Leachate was fed to
the top of the column through a valved manifold that distributed it to both
lysimeters simultaneously from the storage reservoir. The lysimeters were
designed for constant hydraulic head. Thus overflow from the constant head
drain was collected and pumped back to the storage reservoir. All tubing in
the system was made of Tygon tubing (9.5 mm ID). The volume effluent was
monitored as a function of time, and samples of leachate effluent were
analyzed at intervals to determine the concentration of all measurable con-
stituents remaining in the effluent after a known volume of leachate had
passed through the column. This procedure was continued for three different
calcium fluoride sludge leachates collected from the same source at different
times.
A stainless steel, 200 liter tank equipped with drainage outlet was
used as the storage reservoir. This tank was located between the filter bed
and field lysimeters to serve as both a reservoir and an overflow receiver.
10
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SECTION 5
RESULTS AND DISCUSSION
LABORATORY STUDIES
Leachatas from the petroleum, calcium fluoride, and metal finishing
sludges, prepared and analyzed (Table 1) according to procedures described
elsewhere!6, were passed through individual lysimeters that contained one of
the following sorbents: acidic fly ash, basic fly ash, zeolite, vermiculite,
illite, kaolinite, activated alumina, and activated carbon. The volume of
effluent from each of these lysimeters was monitored, and effluent samples
were analyzed for pH, calcium, copper, magnesium, zinc, nickel, cadmium,
chromium, lead, fluoride, total cyanide and organics. This monitoring and
analysis were carried out through repeated washings of the spent sorbents
until no measurable contaminants appeared in the wash effluent.
Effect of Sorbents on Lysimeter Effluent pH
Monitoring results showed that in general, the pH of the lysimeter
effluent from the three sludge leachates was initially influenced by the
sorbents. Considerable variations were observed in the pH of the effluents
collected initially (Figures 3, 4, and 5). However, as the leachate was
passed through the sorbents in the lysimeters, effluent pH eventually be-
came the same as that of the influent. The effluent from the illite lysimeter
is a particularly good example of this effect (Figures 3, 4, and 5). Thus
the pH at which the removals of the cations, anions, and organics in the
industrial sludge leachates occur is influenced initially by the sorbents
and finally by the leachate.
Effects of Leachate pH
Leachate pH and Sorbent Removal Capacity —
The pH of the industrial sludge leachate was found to influence the
different sorbent capacities for the removal of the cations, anions and
organics present in these leachates.
Calcium, Copper, and Magnesium— Based on the removal capacities shown
in Tables 2, 3, and 4, the three most promising sorbents for a specific
leachate constituent were compared (Table 5). As the pH was raised, increases
occured in the removals of calcium, copper, and magnesium ions.
For example, the zeolite, acidic fly ash, and kaolinite sorbent removal
capacities for copper are 5.2, 2.4, and 0 yg/g, respectively, in the presence
11
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TABLE 1: CONCENTRATIONS OF SPECIFIC CATION, ANIONS, AND ORGANICS IN THE
THREE INDUSTRIAL SLUDGE LEACHATES (m/1)
*
Measured
pollutant
Ca
Cu
Mg
7n
F
COD
Acidic petroleum sludge
leachate
34-50
0.09-0.17
27-50
_ 4.
0.95-1.2
090 1 9
251-340
Neutral calcium
fluoride sludge
leachate
180-318
0.10-0.16
4.8-21
6.7-11.6
44-49
Basic metal
finishing sludge
leachate
31-38
0.45-0.53
24-26
1.2-1.5
45-50
Fe, Cd, Cr, and Pb contents were analyzed, but found to be below
measurable levels.
Dashed line indicated amounts below measurable levels.
12
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of acidic leachate (Table 5). But these figures become 8.2, 2.1 and 6.7 yig/g
in the presence of neutral leachate, and 85.4, 13.0, and 23.7 yg/g with basic
leachate. Griffin, et al.^-2 have also reported similar results. In their
study, which was limited to kaolinite and montmorillonite, removals of copper,
cadmium, and zinc increased as the pH of the leachate progressed from acidic
to alkaline conditions. Maximum removals were obtained at a pH of about 8.
The reason for the zero sorbent capacities exhibited by the illite and
zeolite for the calcium and magnesium in the neutral leachate is not under-
stood at this time (Table 5).
Zinc, Nickel, Iron, Cadmium, Chromium, and Lead—The influence of
leachate pH on the different sorbent removal capacities for zinc, nickel,
iron, cadmium, chromium and lead could not be established in this study. Un-
fortunately, measurable concentrations of zinc and nickel were encountered
only in the acidic and basic leachates, respectively, whereas the concen-
trations of iron, cadmium, chromium and lead were all below measurable levels
in the three types of leachates examined.
Fluoride—The sorbent removal capacities for fluoride are also dependent
on leachate pH, but they are the reverse of those encountered with cations.
In the case of fluoride, sorbent capacities increase as the pH of the leachate
decreases from alkaline to acidic. For example, the sorbent capacities for
illite, acidic fly ash, and kaolinite are 2.2, 0, and 2.6 yg/g, respectively,
for removal of fluoride in the basic leachate, these increases to 9.3, 8.7,
and 3.5 yg/g for the acidic leachate (Table 5). Griffin at al.12 aiso showed
this to be the case for the anion HAs04= using kaolinite and montmorillonite.
Maximum removal of this anion was achieved under acidic conditions (about pH
6).
Organics—Organics removal also appears to be pH dependent. The sorbent
removal capacities for the COD in both acidic and basic leachates are signifi-
cantly higher than those achieved with the neutral leachate (Table 5). How-
ever, a trend in the change of sorbent capacity with pH is difficult to iden-
tify in our study, since the concentration of organics in the acidic leachate
is significantly higher than that measured in the basic leachate (Table 1).
But Lub and Baker^ did report maximum sorption of pyridine by sodium kaolinite
and sodium montmorillonite in a pH range of 4.0 to 5.5. Thus it appears that
both the pH and the organics concentration influence the removal of organics
from the acidic leachate.
Leachate pH and Leaching of Ions from Specific Sorbents—
The leachate pH in the lysimeter also influences the leaching of ions
from specific sorbents. When the leachate in the lysimeter was initially
acidic, as indicated by its initial effluent pH, the concentration of a
specific ion in the effluent was found to exceed the concentration of this
ion in the influent. But as the effluent pH approached 6 (and above), the
leaching of the specific ion ceased, and in some cases, the sorbent actually
began to remove the specific ion that was leached from it under more acidic
conditions. As shown in Table 6, for example, when the pH of the effluent
approached 6, as indicated by the final effluent pH, the illite and acidic fly
ash either ceased to leach copper or began to remove it. The removal of
16
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TABLE 5. NATURAL SORBENTS AND THEIR CAPACITY FOR REMOVAL
OF SPECIFIC CONTAMINANTS IN ACIDIC, NEUTRAL, AND BASIC LEACHATES
Ion
Acidic leachate
(petroleum sludge)
Sorbent Capacity
(yg/g)*
Basic leachate
(metal finishing sludge)
Sorbent Capacity
(yg/g)*
Ca
Cu
Mg
Zn
Ni
F
Zeolite
Illite
Kaolinite
Zeolite
Acidic F.A.
Kaolinite
Zeolite
Illite
Basic F.A.
Zeolite
Vermiculite
Basic F.A.
Illite
Acidic F.A.
Kaolinite
1,390
721
10.5
5.2
2.4
0
746
110
1.7
10.8
4.5
1.7
9.3
8.7
3.5
Zeolite
Kaolinite
Illite
Zeolite
Kaolinite
Acidic F.A.
Basic F.A.
Zeolite
Illite
_
-
-
Illite
Kaolinite
Acidic F.A.
5,054
857
0
8.2
6.7
2.1
155
0
0
175
132
102
Illite
Zeolite
Kaolinite
Zeolite
Kaolinite
Acidic F.A.
Zeolite
Illite
Basic F.A.
_
-
-
Zeolite
Illite
Acidic F.A.
Kaolinite
Illite
Acidic F.A.
1,280
1,240
733
85
24
13
1,328
1,122
176
13.5
5.1
3.8
2.6
2.2
0
Total
CN
COD
Illite
Vermiculite
Acidic F.A.
Vermiculite
Illite
Acidic F.A.
12.1
7.6
2.7
6,654
4,807
3,818
-
-
-
Acidic F.A.
Illite
Vermiculite
690
108
0
—
—
-
Illite
Acidic F.A.
Vermiculite
1,744
1,080
244
* yg of contaminant removed/g of sorbent used.
20
-------
copper is indicated when its concentration in the effluent falls below the
influent concentration. This same behavior was observed with the zinc ion
(Table 6). Similar results for fly ash have been recently reported by Theis
and Wirth.17 Their work, which was carried out under batch condition on a
laboratory scale showed that the average leaching of the heavy metals (zinc,
copper, nickel, chromium, lead, and cadmium) from the sorbents was minimal at
a pH 6 and above.
Thus, the results show that regulation of the leachate pH is essential
for optimum removal of anions, cations, and organics while minimizing the
leaching of specific ions from the sorbents. Initial control of leachate pH
so that it is slightly acidic favors the removal of anions and organics while
minimizing the leaching of specific ions. Further adjustment of the leachate
pH so that it is slightly alkaline favors the removal of cations.
Effects of Leachate Contaminants
The concentration of the contaminants in the leachate also appears to
influence the sorbent removal capacity. As the contaminant concentration in-
creases, the sorbent removal capacity also increases. The large zeolite,
acidic fly ash, and kaolinite sorbent removal capacities for copper (85, 13,
and 24 yg/g) obtained with the basic leachate (Table 5) could be due both to
the influence of pH and to the relatively high concentration of copper ion
found in this leachate. Copper concentrations range from 0.45 to 0.53 mg/1
in the basic leachate compared to only 0.09 to 0.17 and 0.10 to 0.16 mg/1 in
the acidic and neutral leachates, respectively (Table 1). This effect of
contaminant concentration on sorbent removal capacity is also seen with the
other cations and the fluoride anion. The highest concentrations of calcium
and fluoride are encountered in the neutral leachate (Table 1). The zeolite
sorbent capacity for calcium in the neutral leachate is 5,054 yg/g (Table 3)
as opposed to only 1,240 yg/g in the basic leachate (Table 4), even though
alkaline conditions favor the removal of cations. Similarly, the illite
sorbent capacity for the fluoride is 175 yg/g in the neutral leachate (Table
3) as opposed to 9.3 and 2.2 yg/g in the acidic and basic leachates (Tables
2 and 4), respectively.
The influence of the concentration of a specific constituent in the
leachate on the sorbent removal capacities is as expected. If it is assumed
that an equilibrium relationship exists between the bound and unbound ions in
the leachate, the higher the ion concentration is in the leachate, the
greater the tendency will be for binding. As a result, greater amounts of
the ion will be removed from the leachate in the presence of a given amount
of sorbent.
Effects of Leachate Velocity Through the Sorbent Bed
The leachate velocity through the sorbent bed in the lysimeters was
also found to influence the removal of cations, anions, and organics in the
leachates. The velocity does not affect the total amount of contaminant
that can be removed by a sorbent (sorbent removal capacity), but it does
define the volume of leachate that, can be treated with maximum contaminant
removal.
21
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For example, different leachate velocities were obtained when neutral
calcium fluoride sludge leachate was passed through four lysimeters that con-
tained different amounts of illite. The fluoride and COD concentrations re-
maining in the effluent were monitored until breakthrough was achieved. The
results are shown in Figures 6 and 7,where the fractions of fluoride and COD
remaining in the lysimeter effluent are plotted against the volume of
leachate treated per gram of illite used. These figures show that as the
velocity of the leachate decreases, the removal efficiency of the sorbent
increases. For example, when the leachate velocity is reduced from 0.140
cm./min. to 0.049 cm./min., the fraction of fluoride remaining in the
effluent after 20 1 of effluent has been collected has been reduced from
0.50 to 0.02.
The sorbent removal capacities, however, are not influenced by the
velocity of the leachate through the sorbent bed. For example, velocity
was found to have no significant effect on the sorbent removal capacity ex-
hibited by illite for fluoride and COD removals (Table 7).
TABLE 7. SORBENT CAPACITY EXHIBITED BY ILLITE
FOR REMOV.AL OF FLUORIDE AND COD
AT DIFFERENT LEACHATE VELOCITIES THROUGH SORBENTS
Leachate velocity Sorbent capacity for Sorbent capacity
through the bed (cm/min) fluoride (yg/g)
0.140
0.138
0.079
0.042
190
186
179
175
"» <-<=>• <=>'
185
192
198
216
An examination of the curves in Figure 6 reveals that the optimum
velocity for treating the largest volume of leachate with maximum fluoride
removal is less than 0.049 cm/min. The curve representing operation at the
optimum leachate velocity should allow the greatest volume of leachate to be
treated with a sharp rise in fraction of fluoride in effluent (C/CO) to
breakthrough.
Natural versus Refined Sorbents
The most effective natural sorbents for the removal of each cation,
anion, or organic present in measurable quantities in the acidic, neutral,
and basic leachates are listed in Table 8. No single sorbent can remove
all the measurable constituents present in the three leachates. A combi-
nation of illite, vermiculite, and natural zeolite is the most effective
for treating the acidic leachate. Illite, acidic fly ash, and zeolite or
basic fly ash are the most effective combinations for treating the neutral
leachate. Illite, kaolinite, and zeolite are the most effective for treating
the basic leachate.
23
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The combinations that is effective in treating one leachate can also
be used to treat the other leachates. But optimum removal of a specific
constituent for a given weight of sorbent would not be achieved, because
the magnitude of the sorbent capacities are influenced by the leachate pH.
Thus a sorbent such as illite, which is the most effective for removing the
fluoride ion in the acidic and neutral leachates, could also be used for re-
moving the fluoride in the basic leachate. But it would be less effective
than kaolinite (Table 5).
The removal capacities exhibited by the most effective natural sorbents
for the removal of cations, anions, and organics are comparable to the more
expensive refined sorbents, activated alumina and activated carbon, in all
cases but one— the removal of the fluoride ion in the basic leachate (Table
8). Here, the sorbent capacity exhibited by the activated alumina is some
four times that exhibited by the kaolinite.
The above results are significant in that they indicate that the in-
expensive natural sorbents can be utilized in the same manner and are as
effective as the more expensive activated alumina and activated carbon for
the treatment of leachates from industrial sludges. In addition, regenera-
tion of the natural sorbents is not required; thus the capital investments
associated with the regeneration equipment commonly used with activated
alumina and activated carbon can be avoided.
Unfortunately, the natural sorbents that are effective for the removal
of zinc in the neutral and basic leachates and nickel, iron, cadmium, chro-
mium, and lead in the acidic and neutral leachates could not be identified
since these ions were found to be below measurable levels in the leachates
obtained from industrial sludges selected for this investigation.
Natural Sorbent Combinations for Optimum Contaminant Removals from Calcium
Fluoride Sludge Leachate
Although the above results show that natural clay/fly ash combinations
are feasible for treating acidic, neutral, and basic industrial sludge
leachates, only the combinations that would provide optimum removals of
cations, anions, and organics in calcium fluoride sludge leachate were in-
vestigated further. The most effective sorbents natural zeolite, acidic and
basic fly ashes, and illite, were combined in different proportions in a
layered system to define the optimum arrangement for removal of the measur-
able cations, anions, and organics present in this leachate.
The two sorbent combinations selected were: (1) illite, acidic and
basic fly ashes, and (2) illite, acidic fly ash, and zeolite. These were
placed in lysimeters in a layered system in the weight ratios of 1:1:1 or
2:2:1. The illite was the top layer, followed by acidic fly ash, or vice
versa. Either the basic fly ash or the zeolite was used as the bottom layer
to remove the cations such as copper and zinc that are initially leached from
the illite and acidic fly ash during the period when the leachate is acidic
(Table 6). Both the basic fly ash and natural zeolite show zinc and copper
removals during the initial period when these ions are leaching from the
illite and acidic fly ash.
26
-------
TABLE 8. COMPARISON OF THE MOST EFFECTIVE NATURAL SORBENT
FOR SPECIFIC CONTAMINANTS WITH ACTIVATED ALUMINA AND
ACTIVATED CARBON IN ACIDIC, NEUTRAL, AND BASIC LEACHATES
Ion
Ca
Cu
Mg
Zn
Ni
F
Total
CN
COD
Acidic leachate
(petroleum sludge)
Sorbent Capacity
(yg/g)*
Zeolite
Act. alumina
Act. carbon
Zeolite
Act .alumina
Act. carbon
Zeolite
Act .alumina
Act. carbon
Zeolite
Act. alumina
Act. carbon
-
—
~
Illite
Act. alumina
Act. carbon
Illite
Act .alumina
Act. carbon
Vermiculite
Act .alumina
Act .carbon
1,390
200
128
5.2
.35
0
746
107
8.6
10.8
.40
1.1
9.3
3.4
1.2
12.1
0
2.4
6,654
411
1,270
Neutral leachate
(calcium fluoride)
Sorbent Capacity
(yg/g)*
Zeolite 5
Act. alumina 6
Act. carbon
Zeolite
Act .alumina
Act. carbon
Basic Fly Ash
Act. alumina
Act .carbon
_
-
-
-
—
—
Illite
Act. alumina
Act . carbon
-
-
-
Acidic Fly Ash
Act .alumina
Act .carbon
,054
,140
357
8.2
2.9
2.0
155
514
3.0
175
348
0
690
0
956
Basic leachate
(metal finishing sludge)
Sorbent Capacity
(yg/g)*
Illite
Act .alumina
Act .carbon
Zeolite
Act .alumina
Act. carbon
Zeolite
Act. alumina
Act .carbon
_
-
Zeolite
Act .alumina
Act. carbon
Kaolinite
Act .alumina
Act. carbon
-
-
-
Illite
Act .alumina
Act. carbon
1,280
737
212
85
6.2
16.8
1,328
495
188
13.5
2.3
4.7
2.6
11.4
0
1,744
0
1,476
of contaminant removed/g of sorbent used,
27
-------
The results showed that the use of illite followed by acidic fly ash and
basic fly ash in the weight ratios of 1:1:1 generally yields greater sorbent
capacities than .the arrangement with acidic fly ash first, than illite and
basic fly ash in the weight ratio of 1:1:1 (Table 9).
TABLE 9. REMOVAL CAPACITIES1 OF COMBINED SORBENTS IN VARIOUS LYSIMETER
ARRANGEMENTS FOR NEUTRAL CALCIUM FLUORIDE SLUDGE LEACHATE
Pollutant +
Ca
Mg
Zn
F~
CN~
COD
Weight ratio
I+Fa+Fb *
0
849
5.9
110
1.3
199
Sorbent
of 1:1:1
Fa+I+Fb
0
528
7.2
105
1.5
133
Capacity (yg/g)*
Weight ratio
I+Fa+Fb
0
515
6.1
128
3.9
241
of 2:2:1
I+Fa+Z
406
866
9.5
148
1.7
218
* Sorbent Capacities are expressed in yg of contaminant removal of sorbent
used.
+ Cd, Cr, Cu, Fe, Ni, and Pb were analyzed and found to be below measurable
levels.
+ I = Illite, Fa = Fly Ash (Acidic), Fb = Fly Ash (Basic), Z = Zeolite.
The sorbent removal capacity exhibited by the illite, acidic fly ash, and zeo-
lite combination (2:2:1) is the most effective for treating all the measurable
contaminants (except for total cyanide) in the calcium fluoride sludge lea-
chate. The next most effective combinations is the illite and the acidic
and basic fly ashes (2:2:1).
Leaching of zinc and copper occurred only when illite and fly ash are
used in combination. This leaching amounted to copper and zinc concentration
of 4 mg/1 and 1.7 mg/1, respectively ,in the initial 1.4 1 of effluent. The
use of zeolite or basic fly ash as the bottom layer along with Illite and
acidic fly ash in a 2:2:1 combination reduced the copper and zinc in the in-
itial 1.4 1 of effluent to the influent concentration of 0.1 mg/1 and 0.6mg/l,
respectively.
In this latter part of the study, different calcium fluoride sludge lea-
chate was used than in the first part because the volume of leachate required
was greater than the amount that remained from the earlier tests. Analysis
of this leachate (Table 10) reveals the presence of measurable concentrations
of total cyanide and zinc that were not present in the earlier leachate
(Table 1), even though both samples were obtained from the same source, but
at different times. Discussions with plant personnel revealed that zinc and
cyanide were used in several of thoiir processes during the period that this
latter sludge was collected.
28
-------
TABLE 10. ANALYSIS OF THE NEUTRAL CALCIUM FLUORIDE SLUDGE LEACHATE USED TO
OBTAIN SORBENT COMBINATIONS FOR OPTIMUM TREATMENT
*
Pollutant Concentration (mg/1)
Ca 119
Mg 89
Zn 0.60
F 15.5
CN 0.61
COD (organics) 36
* Cd, Cr, Cu, Fe, Ni, and Pb, contents were analyzed but found to be below
measurable levels.
PILOT STUDIES
Since the combination of illite, acidic fly ash, and zeolite (2:2:1)
showed the most promise for treating the neutral calcium fluoride sludge lea-
chate in the laboratory, two large vertical lysimeters were set up outdoors
with a sufficient amount of this sorbent combination to treat 530 liters of
neutral calcium fluoride leachate. The leachate was collected three different
.times over a period of a year to study the effect of variations in leachate
composition resulting from changes in plant operation. The pilot studies were
designed for fluoride removal from the leachate. The combination sorbent re-
moval capacity for fluoride (Table 9) defined the amount of sorbent required
in the lysimeters. The permeability of the clay fractions was adjusted by
admixing it with inert sand to obtain a leachate velocity of 0.01 cm/min
through the sorbent bed and thus insure adequate removal of the fluoride ion.
This leachate velocity was selected because it is only a fourth of the 0.049
cm/min shown earlier to approach the required leachate velocity needed to
treat the largest volume of leachate with maximum fluoride removal. The re-
sults of this study are shown in Figures 8 through 13.
The influent calcium concentrations in the three calcium fluoride samples
collected over a period of a year were 309, 115, and 228 mg/1. The illite,
acidic fly ash, and zeolite combination (2:2:1) reduced these concentrations
in the effluent to approximately 80 mg/1 (Figure 8). During the addition of
the initial leachate sample, poor removal of calcium was observed. This was
probably due to channeling of the leachate through the sorbent as a conse-
quence of adding the sorbent to the columns in the dry state rather than in
slurry form. Elimination of the channeling resulted in rapid reduction of
calcium concentrations to 80 mg/1.
Copper concentrations in the three leachate samples (0«12, 0.10, and
0.07 mg/1) were reduced to 0.04 mg/1 (Figure 9). Also, the leaching of copper
29
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from the illite and acidic fly ash (discussed earlier) is effectively con-
trolled by the natural zeolite. The copper concentration in the effluent
from the leachate initially treated was 0.08 mg/1, which is well below the
influent concentration of 0.12 mg/1.
The effect of channeling on copper removal can again be seen by the sud-
den rise in effluent copper concentration after about 40 liters of leachate
was treated. However, once the channeling was minimized, by expanding the
bed with reverse flow using collected effluent, the copper concentration in
the effluent was again reduced to 0.04 mg/1. This channeling effect points
out the need for proper dispersion of the leachate stream through the bed.
Magnesium removal by the illite, acidic fly ash, zeolite combination
(2:2:1) showed a dependency on the influent concentration (Figure 10). In-
fluent magnesium concentrations of 29.6, 75.7 and 18.5 mg/1 gave effluent
concentration of approximately 25, 53, and 15 mg/1, respectively. One would
expect results similar to those observed for the calcium and chopper removals,
which appeared to be independent of the influent concentration. There is
presently no explanation for these results.
The effective fluoride removal also achieved with this sorbent combina-
tion comes as no surprise, since the amount of sorbent and the leachate
velocity used were designed for fluoride removal. An effluent fluoride con-
centration of 1 mg/1 was achieved with an influent concentration that varied
in the three leachate samples from 10.2 to 15.3 mg/1 (Figure 11). Again, as
was the case for calcium and copper, the fluoride concentration in the treat-
ed^leachate was independent of the influent concentration.
This independence also appeared to hold true for the removal of the cya-
nide ion. Where the concentration of cyanide in the influent cyanide was
significant (i.e., 0.25 and 0.37 mg/1 in the first two leachates samples),
the sorbents reduced these concentrations to approximately 0.06 mg/1 (Figure
12). But, for the third leachate, where the influent concentration was ex-
tremely low (0.02 mg/1, no significant removal of cyanide was observed. The
minimum concentration to which the cyanide can be reduced with this sorbent
combination appears to be about 0.06 mg/1. However, if the illite, acidic
fly ash, and basic fly ash sorbent system (2:2:1) had been used instead of the
illite, acidic fly ash, and zeolite combination (2:2:1), the effluent cyanide
concentration would probably have been significantly lower than 0.06 mg/1.
Such a result would have been due to greater sorbent removal capacity achieved
with the non-zeolite combination (3.9 mg/g) than with the natural zeolite
combination (1.7 mg/g) (Table 9).
The minimum effluent concentration of the organics achieved with the
illite, acidic fly ash, and zeolite combination (2:2:1) appears to be depend-
ent on the organic influent concentration. As the concentration of organics
in the influent increased from 24.2 up to 44.8 mg/1, the concentration of
organics remaining in the treated leachate also increased from a low of about
2.5 to 18 mg/1 (Figure 13). The reason for this behavior is not clear, but
the overall results indicate that the illite, acidic fly ash, and zeolite
combination is extremely effective in removing not only the cations and 4nions,
but also the organics present in the neutral calcium fluoride sludge leachate.
32
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SECTION 6
PROPOSED DESIGNS FOR A CALCIUM FLUORIDE SLUDGE LEACHATE TREATMENT SYSTEM
In view of the results of the pilot study, several designs are
considered for a treatment system for leachate that will originate from a
landfill (62.5 x 62.5 x 3.7 m.) which will contain an estimated 10 years
production (2.49 x 10^ metric tons) of calcium fluoride sludge. The 3.7m.
depth is presently being used in the storage pit at the plant where the
sludge is generated.
The designs are based upon the use of the illite, acidic fly ash,
zeolite combinations and the illite, acidic fly ash, basic fly ash combina-
tions in the weight ratio of 2:2:1. The pilot study results indicated that
the combination sorbent capacity of 148yg F~/g of sorbent used (Table 9) and
a leachate velocity of 0.01 cm/min through the illite, acidic fly ash, and
zeolite combination (2:2:1) were effective in treating all the measurable
constituents (Ca, Mg, Cu, F, CN, and organics) in 530 liters of leachate with
no breakthrough.
SYSTEM 1
One approach- (.System 1, Figure 16) involves lining the sludge pit with an
impermeable liner to prevent groundwater intrusion. A 1-ft. filter bed is
placed at the base of the landfill to remove the suspended solids. The
leachate is collected at the bottom of this filter bed and pumped on to an
adjacent bed of illite, acidic fly ash, and zeolite (2:2:1),
the dimensions of which are 8.5 x B.5 x 2.7 m. The bed contains sufficient
sorbent to treat a year's production of leachate at a rate of 7.5 1/min with-
out ponding and still maintaining a maximum leachate velocity through the bed
of 0.01 cm/min-(see calculation in Appendix). The 7.5-1/min flow rate was
determined by assuming that the annual average rainfall is 102 cm, and that
all the rain that falls on the landfill becomes leachate.
SYSTEM 2
The second approach (System 2, Figure 17) is to line the sides of the
sludge pit with an impermeable liner to prevent the escape of leachate from
the landfill and to place at the bottom of the landfill a 2-ft. layer of the
illite, acidic fly ash, and zeolite (2:2:1). This sorbent layer is covered
with a 1-ft. layer of filter media to prevent clogging of the sorbent bed by
the suspended solids in the leachate (Figure 17). The 62.5x62.5x0.6 m layer
of sorbent combination would be adequate to treat 10 years production of
leachate containing an average 10 mg/1 of fluoride at a flow rate of 7.5
1/min (see calculation in Appendix) .This approach would be limited, however,
37
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to areas where the groundwater table is well below the landfill so that
groundwater intrusion through the sorbent bed into the landfill would not in-
crease the rate of leachate production beyond 7.5 1/min.
1°** *** ***** the illite* acidic fl? ash » and zeolite Com-
(2:2:1) is estimated to be $1.37/ton of calcium fluoride sludge
disposed of in landfill. Prices of $10/ton for illite and $50/ton for zeolite
were used to estimate the sorbent cost. No cost was associated with obtain-
ing the acidic fly ash, since it is a waste product and the utility is
presently paying to have it hauled away.
,. o the lllite> acidic fly ash and basic fly ash sorbent combina-
tion (2:2:1) was not evaluated on the pilot scale because of the time con-
straints of the grant, the laboratory studies (Table 9) show this combination
to be effective for treating the measurable constituents (except for calcium)
in the calcium fluoride sludge leachate. The illite, acidic fly ash and
basic fly ash combination offers a far less expensive approach than the
illite, acidic fly ash, and zeolite combination. If the calcium ion concen-
tration encountered in this leachate (Table 1) presents no significant
problems, the sorbent cost for disposing of 1 ton of calcium fluoride sludge
decreases from $1.37 to $0.45. All bed or layer dimensions remain the same
(see calculation in Appendix).
Presently, one disadvantage does exist to using basic fly ash rather
than zeolite. The supply of basic fly ash from the utility that has been
supplying it is somewhat limited, since the power station generates more
acidic than basic fly ash.
38
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REFERENCES
1. Fuller, W., McCarthy, C., Alesii, B.A., and Niebla, E. Liners for
Disposal Sites to Retard Migration of Pollutants. Residual Management
by Land Disposal. In: Residual Management by Land Disposal, BPA-
600/9-76-015, U.S. Environmental Protection Agency, Washington, D.C.,
(1976).
2. Rios. C. B. Removing Phenolic Compunds from Aqueous Solutions with
Absorbents. U.S. Patent #2,937,142.
3. Bhargava, R., and Khanna, M.P. Removal of Detergents from Wastewater
by Adsorption on Fly Ash. Indian Journal Environmental Health
16, 109-120 (1974).
4. Baker, R., and Hah, M. Pyridine Sorption from Aqueous Solutions by
Montmorillonite and Kaolinite. Water Research, 5^ 839-848 (1971).
5. Luh, M., and Baker, R. Sorption and Desorption of Pyridine-Clay in
Aqueous Solution. Water Research, _5, 849-859 (1971).
6. Nelson, M.D., and Quarino, C.F. The Use of Fly Ash in Wastewater Treat-
ment and Sludge Conditioning. J.W.P.C.F., 4^2,, R-125-135 (1970).
7. Kliger, L. Parathion Recovery from Soils After a Short Contact Period.
Bulletin of Environmental Contamination and Toxicology, 13, 714-719
(1975).
8. Liao, C.S. Adsorption of Pesticides by Clay Minerals. A.S.C.E.
Sanitary Engineering Div. 96^ 1057-1078 (1970).
9. Damanakis, M., Drennan, D.S.H., Fryer, J.D., Holly, K. The Adsorption
and Mobility of Paraquat on Different Soils. Water Research, 10, 264-
277 (1970).
10. Emig, D.D. Removal of Heavy Metals from Acid Bath Plating Wastes by
Soils. Diss. Abst. _B, 2661 (1973).
11. Griffin, R.A., Cartwright, K., Shrimp, N.F. Steele, J.D., Ruch, R.R.,
White, W.A., Hughes, G.M., and Gilkeson, R.H. Alternation of Pollutants
in Municipal Landfill Leachate by Clay Minerals: Column Leaching and
Field Verification. Environmental Geology Notes, 78, 1-34 (1976).
39
-------
Attenuation of ?%l ,' A"' A'K' ' Robblns°n' ^.D. and Shrimp, N.F.,
Mln^8 « ^1U*antS ln Municipal Landfill Leachate by Clay
1-47 ^977^ Ads"P"°n- Environmental Geology Notes, 79,
"' Cn*ffi\' J;°" and Miller- R'J- Lead, Cadmium and Calcium Selectivity
Coefficients on a Montmorillonite, Illite, and Kaolinite. Journal of
Environmental Quality, 3^, 250-253(1974). ouurnai 01
14. Babich, H and Stotzky, G. Reduction in Toxicity of Cadmium to Micro-
™ baMln and Environmental Microbiology?
' Journat'?'^-EXC=an?e Behavlor of C°PPer' Manganese, and Zinc Ions.
Journal Indian Society Soil Science, 6., 71-76 (1958).
16. Chan, P.C., Dresnack, R. , Liskowitz, J.W., Perna A and
ant Control. EPA-600/2-78-024, U.S.^viron^en *^ po ec n Agen
Washington, D.C. (1978). ^-uueccion Agency,
A^h"' I'L'' and Wirth> J'L- Sorptive Behavior of Trace Metals on Fly
1096-1100Ua977)!Stei°S- EnVir°nmental Scien" -d Technology II,
40
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APPENDIX
TREATMENT SYSTEM DESIGN CALCULATIONS
1. Amount of Calcium Fluoride Sludge Production (10 Years)
Annual sludge production estimated by sludge producer:
2,740 tons = 2.74 x 1010 g
10 years production = 2.74 x 10 g
2. Volume of Sludge Pit
3
Assume the compacted sludge density = 1.76 g/cm
Therefore, the sludge pit volume for 10 years = 2.74 x 10 g/1.7 g per
cm3 = 1.55 x 1010 cm3
3. Calculation of Surface Area of Sludge Pit
Depth of sludge in existing storage pit = 3.66 m
4 3
Mean surface area required = 1.56 x 10 m /3.66
= 4.26 x 103 m2
Assume thepit has a wall slope for 1 vertical on 1 horizontal with a
square configuration for both of top and bottom surface.
Let top surface dimension = a (m) x a (m)
and bottom dimension = b (m) x b (m)
then (a2 + b2)/2 = 4.26 x 103 m2
a = b + 12 x 2
The top and bottom areas will be:
3 2
a x a = 62.5 m x 62.5 m = 3.91 x 10 m
b x b = 54.9 m x 54.9 m = 3.01 x 103 m2
41
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*• Volume of Sludge Leachate Generated by Rainfall
Assuming the annual rainfall is 1.02 cm per year, the annual leachate
generated is:
1.02m x 3.91 x 103 = 3.99 x 103 m3
Assuming that all the rain that falls on the sludge becomes leachate,
the amount of sludge leachate generated in 10 years:
= 3.99 x 104 m3
5. Total Sorbents Required for Each Year
Average leachate concentration of fluoride is 10 mg/1 (based on
laboratory and pilot studies) using the illite, acidic fly ash, and
natural zeolite:
System 1: Using the illite, acidic fly ash, and zeolite combination
(2:2:1), the sorbent removal capacity for fluoride is
0.148 mg/g; therefore, amount of sorbent required annually:
- 3.99 x 109 x 10~3 10 T 0.148 = 2.70 x 108
System 2: Using the illite, acidic fly ash, and basic fly ash combina-
tion (2:2:1), the sorbent removal capacity for fluoride is
0.128 mg/1; therefore, amount of sorbent required annually:
= 3.99 x 109 x 10~3 10 T 0.128 = 3.12 x 108
6« Average Flowrate of Leachate to be Treated
Q = 3.96 x 106 / (365 x 24 x 60) = 7.35 1/min.
1 - Required Sorbent Bed Area to^Avoid Ponding
K = Ql/Ah (assume 1 = h)
The permeability of clay will be adjusted by mixing with inert material
(i.e., sand) to provide a coefficient of permeability.
-4
K = 1.8 x 10 cm/sec (i.e., exhibited by the fly ash)
A = Q/K = 7.53 cm /sec (1.84 x 10~4 cm/sec x 60 sec/min)
*• 6.97 x 105 cm2 = 8.35 m x 8.35 m
42
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8. Volume of Sorbent Bed
System 1: Using the illite, acidic fly ash, and zeolite combination
(.the illite requires 40 percent sand, and zeolite requires
80 percent to achieve the above coefficient of permeability):
Q
Amount of sorbents = 2.68 X 10 g
Sand for illite = 4.29 x 109 g
9
Sand for zeolite = 4.29 x 10 g
Q
Total amount of materials = 3.54 x 10 g
3
Packing density = 1.76 g/cm
3
Total volume = 201 m
= 8.55 m x 8.55 m x 2.75 m
System 2: Using the illite, acidic fly ash, and basic fly ash combina-
tion:
Q
Amount of sorbents = 3.09 x 10 g
Sand for illite - 4.94 x 107 g
Q
Total amount of materials = 3.58 x 10 g
Q O
Total volume = 2.03 x 10 cm
= 8.55 m x 8.55 m x 2.78 m
9. Cost of Sorbents
System 1: Using the illite, acidic fly ash, and zeolite combination,
Illite cost = $10/ton
Natural zeolite cost = $50/ton
Fly ash cost = $0
8 -6
Total sorbent cost = 2.68 x 10 x 0.4 x 10 x 10
+ 2.68 x 108 x 0.2 x 10"~6 x 50 - $3,752
or $3,752/2,740 ton of sludge produced annually
Sorbent cost per ton of sludge = $1.37
43
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Sample 2: Using the illite, acidic fly ash, and basic fly ash combina-
tion,
Illite cost = $10/ton
Fly ash cost = $0
Total sorbent cost = 3.09 x 108 x 0.4 x 10~6 x 10 = $1,240
or $1,240/2,740 ton = $0.45/ton of sludge produced annually
Sorbent cost per ton of sludge = $0.45
10. Design of Liner Bed
System 1: Using the illite, acidic fly ash, and zeolite combination,
total sorbent,
3
Volume = 201 m /year
Depth of sorbent bed = 54^9 ^54.9 = 0.67 m
System 2: Using theillite, acidic fly ash, and basic fly as combination,
q
Total sorbent volume = 203 m /year
Depth of sorbent bed = 54^ 54^ = 0.67 m
11. Sorbent Cost
System 1: The illite, acidic fly ash, and zeolite combination weight
and cost of sorbents required for 10 years are:
Fly Ash (acidic) = 1,072 tons x $0/ton = 0
Illite - 1,072 tons x $10/ton - $10,720
Zeolite = 536 tons x $50/ton = $26,800
Total 2,680 $37,520
Tons of sludge produced in 10 years = 27,400
Sorbent cost/ton of sludge = *An - = $1.37
z 7,400 tons
44
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System 2: The illite, acidic fly ash., and basic fly ash combination
weight and cost of sorbents required for 10 years are:
Fly Ash (basic) = 620 tons x 0 ton = 0
Fly Ash (acidic) = 1,240 tons x 0/ton = 0
Illite = 1,240 tons x $10/ton = $12,400
Total = 2,100 tons = $12,400
Tons of sludge produced in 10 years = 27,400
Sorbent cost _ $12,400 _ ^Q ,,-
Tons of sludge produced 27,400
45
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1. REPORT NO.
EPA-600/2-80-052
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
2.
3. RECIPIENT'S ACCESSION NO.
EVALUATION OF SORBENTS FOR INDUSTRIAL SLUDGE LEACHATE
5. REPORT DATE
June 1980
6. PERFORMING ORGANIZATION CODE
Paul C. Chan, John W. Liskowitz, Angelo Perna, and
Richard
„
New Jersey Institute of Technology
323 High Street
Newark, New Jersey 07102
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
1BB610
11. CONTRACT/GRANT NO.
R 803717 02
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Lab
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
15. SUPPLEMENTARY NOTES ' " "
- Cinn, OH
13. TYPE OF REPORT AND PERIOD COVERED
Final 6/76-9/78
14. SPONSORING AGENCY CODE
EPA/600/12
Project Officer: Mary K. Stinson (201) 321-6638
16. ABSTRACT — -
A laboratory and outdoor pilot-scale investigation was conducted on the use of
selected sorbents for removing leachate contaminants from three industrial sludges
The laboratory results indicated that, rather than a single sorbent, a combination
of acidic and basic sorbents is required in a layered system for removal of all the meas-
urable contaminants from the leachates. These combinations are illite, vermiculite and
a natural zeolite for the acidic leachate; illite, acidic fly ash for the neutral leach-
ate; and illite, kaolinite, and a natural zeolite for the alkaline leachate. The sorbent
capacities exhibited by the natural sorbents are comparable to those exhibited by refinec
sorbents.
The outdoor pilot study, which was limited to the treatment of the calcium fluoride
sludge leachate, using lysimeters, some 80 times larger than the laboratory lysimeters
revealed that the sorbent effectiveness depends on the velocity of the leachate through
the^sorbents and the sorbent removal capacity for specific contaminants. Except for mag-
nesium, effective reductions of the measurable leachate constituents were achieved with
the use of illite, acidic fly ash, and a zeolite in the weight ratio of 2:2:1.
Sorbent costs have been estimated for various combinations required for treating
leachate from calcium fluoride sludge over a ten-year period of landfill operation. For
the illite/acidic fly ash/zeolite combination and the illite/acidic fly ash/basic fly :
ash combination, costs are $1.37 and $0.45 per ton of sludge, respectively
KEY WORDS AND DOCUMENT ANALYSIS
Waste treatment
Sorbents
Regeneration
Fluoride
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
EPA Form 2220-1 (Rev. 4-77)
Treatment cost
Fly ash
Clay
b.IDENTIFIERS/OPEN ENDED TERMS
Fly Ash-Clay Sorbent
Combination
Batch Treatment
Sorbent Bed
Polishing Treatment
19. SECURITY CLASS {This Report)'
!0. SECURITY CLASS (Thispage)
UNCLASSIFIED
PREVIOUS EDITION IS OBSOLETE
48
22. PRICE
5-657-146/5683
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