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TRANSCRIPT
Joint Technical Advisory Group Meeting
University of Florida and Florida Atlantic University Funded by the Hinkley Center for Solid and Hazardous Waste Management (HCSHWM)
and the Solid Waste Authority of Palm Beach County
MEETING AGENDA
Tuesday, May 27, 2014
10:00 – 10:15 am Opening Address and Introduction of Participants J. Schert10:15 – 11:00 am Leachate Collection System Clogging K. Kohn
D. Purdy
J. Dacey
A. Harris 11:00– 11:15 am Overview of University of Florida Research
Studies
T. Townsend
11:15– 12:00 noon Options for On‐Site Leachate and Groundwater
Management Strategies at Landfills
J. Wally
R. Darioosh
J. Chung 12:00 – 12:35 pm Tool for Assessing Potential Iron Exceedances in
Groundwater at Landfill Sites
L. Sarmiento
N. Blaisi
J. Chung 12:35 Lunch 12:35 –12:55 pm Overview of Florida Atlantic University Studies D. Meeroff12:55 –1:15 pm Groundwater Circulation Well Technology
Experiments
A. Albasri
1:15 –1:35 pm Safe Discharge of Landfill Leachate to the
Environment
J. Lackner
1:35 –1:55 pm Open Forum Participants2:00 pm Adjourn, Thank You J. Schert
For more information, contact Dr. Daniel E. Meeroff at:
Tel.(561) 297‐3099 FAX.(561) 297‐0493 http://labees.civil.fau.edu
Attendance: Denys Purdy, Justin Dacey, Alyssa Harris , Jim Wally, Nawaf Blaisi, Jaeshik Chung,
Linda Monroy, Roja Dasioorh, Chris Moody, Kevin Kohn, Tim Vinson, Jessyca Dalazen, Ahmed
Albasri, Joseph Lakner, Damaris Lugo, Richard Loff, Sam Levin, John Schert, Tim Townsend,
Dan Meeroff
1. Opening address by J. Schert of the Hinkley Center followed by introduction of the
group members and participants (10:05 am) 2. Kevin Kohn (UF) gave an introduction to the leachate collection system clogging
project. He described the nature and history of the clogging issues at the Solid
Waste Authority of Palm Beach County. He discussed the potential mechanisms
including supersaturation with calcium carbonate, degassing of carbon dioxide,
and the role of microorganisms. He described solutions that had been set forth in
the previous studies and the literature including acid addition, loading reduction,
coarse drainage layers, carbon dioxide degassing, limiting mixing of different
leachate streams, organic colloids, stagnant conditions, etc. He described the
different types of rocking observed in the study, the water quality testing, and
sampling methodology used. Next, he showed data profiles with respect to
temperature, pH, alkalinity, COD, etc. He then presented historical leachate
collection system inspection patterns from 2007‐2014. Then he described column
studies to investigate nucleation sites and the role of microorganisms as well as
the effect of stagnant vs. turbulent conditions. Finally, he presented potential
solutions currently being tested by SWA and the UF/FAU/Hinkley Center team
as well as operational and design changes. 3. Alyssa Harris (FAU) presented FAU leachate aeration experiment data and
vibration table experiments. There was a suggestion to run the experiments in a
fume hood to increase evaporation. Sam Levin suggested controls that were open
to the atmosphere and recording the amount of precipitates formed. 4. Denys Purdy (FAU) described leachate loop experiments conducted at FAU. The
first experiment was run for 100 hours with no significant precipitate formation.
This was expected since no air, foam, nucleation sites or flow obstructions were
used. Mr Purdy described planned modifications to the experiment setup to form
the precipitates and then test conditions to prevent formation. Sam Levin
recommended to turn off the pump and let the leachate sit but this was already
done. Then he suggested to use a larger reservoir of leachate. Mr Schert asked if
the leachate was representative with respect to calcium. Ms. Lugo asked if the
size of the pipe in the track plays a role. Mr. Lackner asked if the pipe materials
were the same as in the field, but they are not. Dr. Townsend recommended
hypothesis testing for the experimental design rather than random testing. 5. Tim Townsend (UF) introduced additional leachate research at UF. He described
projects on beneficial use of wastes, landfill design, groundwater issues
associated with landfills, and C&D debris recycling. He described field studies of
beneficial reuse of ash in roadways in Pasco County, modeling efforts for iron in
groundwater and surface water near landfills, and onsite management of iron in
groundwater and leachate. 6. Jim Wally (UF) presented his work on updating a leachate management database
based on Meeroff and Teegavarapu 2008. He asked for the audience to help him
fill holes in the survey. He also addressed the issue of cost data for management
options. 7. Roja Dasioorh (UF) presented her work on leachate water quality database updates
based on Meeroff and Teegavarapu 2008. Her focus is on pH, TDS, COD, BOD, chlorides,
sodium, iron, arsenic, lead, calcium, ammonia, etc. 8. Jaeshik Chung (UF) presented finite element modeling work on vadose zone aeration
venting for iron remediation under passive venting and negative pressure conditions. Dr.
Meeroff raised concerns about biofilm plugging. John Schert asked about ORP
measurements and strength of aeration piping underneath the landfill. Ms. Lugo and
others asked how the hydraulic conductivity, porosity, oxygen profile, ORP, specific
oxygen uptake rate, and overlap of aeration profiles were taken into account in the
model. 9. Richard Lott (UF) presented a brief review of groundwater quality data of iron in
landfills using WACS. He compared groundwater background levels with iron
detections in groundwater with box and whisker plots. 10. Linda Monroy (UF) presented her work on determining the initial concentrations of iron
underneath landfills. She described a preliminary experiment to determine conditions
for determining this value with a 15‐30 day test method with nitrogen purging and a
celluslose carbon source at different liquid/solids ratios using DI water. They tried
various leaching solutions including young and old leachate. Dr. Meeroff suggested
using sterile dilution water with nutrients (such as the water used during the BOD test
instead of DI water or actual leachate which varies too much). 11. Nawaf Blaisi (UF) presented his work with changing the liquid/solid ratio using an
anaerobic glove box and aerobic conditions as well. Dr. Meeroff suggested varying the
carbon content with something like methanol in sterile dilution water with nutrients. 12. Jaeshik Chung (UF) returned to describe his modeling of Fe(II) dissolution underneath
landfills using TOUGH and TOUGH2, which are conservation of mass based models.
He looked at how long it would take to induce the soluble ferrous iron to background
levels. He looked at the effect of sorption using a 0.1 distribution coefficient, and showed
the retardation effect as well as spatial‐temporal variations with aeration downgradient.
He plans to look at other minerals other than iron as well. Sam Levin asked about the
difference in the model if the landfill was lined v. unlined. 13. Break for lunch 14. Dan Meeroff (FAU) introduced FAU research on leachate treatment, iron in
groundwater, membrane treatment of wastewater, sustainability in buildings, water
conservation, water quality, sea level rise, and green lodging.
15. Ahmed Albasri (FAU) presented his work on groundwater circulation wells for
managing iron in groundwater underneath landfills. He presented results from phase 1,
2, and 3. He described his experiments for phase 4 with continuous feeding of
groundwater spiked with iron conducted at the water treatment facility in Boca Raton
with Boca Raton sandy soils in a flow through configuration to determine reaction times,
radius of influence, and other design/cost criteria. Sam Levin asked how to stop the iron
from creating a layer of precipitates at the top. Albasri responded by showing how the
new setup will introduce flow in the subsurface of the tank. The remaining questions are
surrounding the amount of air and how far apart the wells need to be. John Schert raised
concerns about well clogging. Albasri then asked questions of the audience with respect
to cost data, other locations suffering from this problem, the radius of influence equation,
and iron speciation methods. 16. Joseph Lackner (FAU) described the UV/TIO2 photocatalytic process to treat weak
leachates for potential beneficial reuse in applications such as surface water discharge,
irrigation, industrial cooling water use, and dilution water. He described the
modifications done to the pilot unit and described his methodology for upcoming
experiments. The key items were to quantify the fate of ammonia and COD, optimize
the catalyst dose, recovery, cost and energy usage. He talked about varying the UV
wavelengths and lamp energies to reduce the reaction times and decrease the cost of the
process. Dr. Townsend recommended that the water quality parameters for FAC777
could be significantly reduced for efficacy testing. 17. Dr. Meeroff (FAU) thanked everyone for participating and thanked all of the speakers. 18. Meeting adjourned at 2:20 pm
5/29/2014
1
EXAMINATION OF LCS
CLOGGING AT ASH AND
MSW CO-DISPOSAL LANDFILL
May 27, 2014
The Problem
Clogging of:
Leachate collection system (LCS) pipes within the landfill
cells.
Leachate force main “outside” the cells.
Gas condensate “force main” clogging.
The Site
Dyer Landfill
Admin Building
Class III Landfill
New
Mass Burn RDF
Closed Cells 1 - 4
Cells 13, 14
Cells 11, 12 Cells 5,6,7, and 8
N
Leachate Gravity Lines, Gas Condensate
and Force Main
B
Pump
Sta
Why Study?
LCS is critical - limit leachate head
Expect a reduction in LCS efficiency; so,
Design redundant systems
Bottom slope, pipes, drainage layer, separate cells
Apply factors of safety (FOS)
Clean-outs for LCS pipes to allow cleaning.
Complete blockage not anticipated.
Design and FOS may need to change.
The Focus
Our focus has been to better understand both:
The mechanism – how clogs form
Allows assessment of FOS and deign adequacy.
Treating the day-to-day issues to prevent permit
& operation issues.
Dilution
Acid treat
Electrostatic treatment
5/29/2014
2
What We Knew at the Start
(September 2012)
March 1999 – loss of leachate flow Cell 6.
Force main clogged - outside Landfill.
Also, gravity lines clogged in Cell.
Cell 6 constructed: 1995 – 1996.
1st waste: Sept 1996.
< 3 years for significant clog formation.
Annual LCS inspection and maintenance:
Clogging in pipes in Cells 1 - 8
Previous Work
Maliva, Levine, Mullah-Salah, Mayer
Leachate supersaturated with calcite;
CO2 degassing may play a role
Microbes involved
“Passive” as nucleation sites
“Active”
Metabolism affects environment around microbe
More alkaline = CaCO3 solid
Metabolic activities generate ions which form insoluble
solids
Previous Work
Maliva, Levine, Mullah-Salah, Mayer
Particles in leachate and clog: Calcium predominant (90%)
Some Mg, P, Cl, S, CO32-, and Si
Ash a source of calcium and TDS in leachate.
Clogging in Ash/MSW > MSW > ash
Operational and design considerations
Acid treat clogged pipes
Reduce loading – larger pipes closer together.
Coarse drainage layer
“Working” Hypotheses
Multiple factors – not all at play all the time.
Leachate supersaturated with:
Calcium
(source = ash and MSW)
Carbonates
(source = microbial degradation of MSW)
pH increase as CO2 released to atmosphere.
Less CO2 in atmosphere outside Landfill than inside.
CaCO3 less soluble at high pH
Exacerbated by turbulence/pumping
“Working” Hypotheses (continued)
Mixing of different leachate streams, for example:
Low pH (6.9) and high pH (7.8)
Low pH lots of Ca2+ and CO32- in solution mixes with high
pH causing rapid precipitation of CaCO3.
High organic (gas condensate) and high Ca2+
(+) ions surround (-) colloids = agglomeration
“Working” Hypotheses (continued)
Stagnant conditions
“Standing” leachate = more clogging than flowing.
Microbial activity
Source of carbonates - MSW degradation
Nucleation sites for crystal formation
Suspended particles in leachate
Formation of “biofilm”
Secretion of EPS that trap suspended particles
Metabolism affects environment around microbe
5/29/2014
3
“Working Hypotheses” (continued)
Clogging mechanism must account for:
Clogging in disparate environments
LCS pipes deep in Landfill.
Leachate in pipes outside the Landfill.
Formation of very different types of clog material:
Answering the Questions
CaCO3 Forms from Saturated Solutions
Are leachates supersaturated with Ca2+
and CO32- ?
Previous analyses were on mixtures
Liquids mix in manholes; so,
Collect “discrete samples”.
Separate cells, gas condensate
Expand sample points
Collect many samples = confidence
3/8/2013 4/8/2013 5/8/2013 6/8/2013 7/8/2013 8/8/2013 9/8/2013 10/8/2013 11/8/2013 12/8/2013 1/8/2014 2/8/2014 3/8/2014 4/8/2014
Sa…Dates sampled:
Typical Cleanout Sampling
Sampling Cell 7 – Cleanout 9
Langlier Index - All Supersaturated
Location SS or US
PS B & C6 SS
Gas Cond C5 SS
LDS 6 SS
Flare Cond SS
Cl III & Dyer SS
Dyer SS
Gas Cond C6 SS
C7 Composite SS
LDS C7 SS
C10 Composite SS
C10 LDS SS
C12 Composite SS
C12 LDS SS
PS D SS
C11 Composite SS
C10 Lateral SS
Dr. Meeroff’s lab:
Analyzed samples for pH, ALK,
Temperature, TDS, Ca2+
Calculated Langlier & Ryznar
indices.
Indicates propensity to scale
Most supersaturated.
But not clogs everywhere; so,
more involved.
Location SS or US
C11 LDS SS
C9 Composite SS
C9 LDS SS
Cool Tower SS
C8 LDS SS
C8 Lateral SS
C5 LDS SS
C6 LDS SS
PS C SS
Dyer SS
C5 Lateral SS
C11 Lateral SS
C9 Lateral SS
C7 Lateral SS
C12 Lateral SS
Lots of Data – Different Locations
Allows Comparisons to Determine Patterns
6.80
7.00
7.20
7.40
7.60
7.80
8.00
Time (6 mos) 29
30
31
32
33
34
35
36
37
38
39
T
Time (6 mos)
“Natural” T Variation “Natural” pH Variation
6.00
6.50
7.00
7.50
8.00
8.50
4 6 8 10 12 14
Cell #
pH - Same Day all Cells
Cell #
7.00
7.20
7.40
7.60
7.80
8.00
8.20
8.40
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
20,000
4 6 8 10 12
pH
ALK
and C
OD
pH, ALK, COD - Same Day all Cells
Time Check
Halfway
8 minutes left?
Does CO2 Degassing Cause Clogging?
Does CO2 diffuse to air when
leachate leaves landfill?
If yes, what impact?
Samples:
Not exposed to air.
What happens when exposed?
5/29/2014
4
CaCO3 Forms When CO2 Degasses
When leachate degasses:
pH goes up.
CaCO3 forms
Decrease in ALK
Suspended solids less
9000
9200
9400
9600
9800
10000
10200
10400
11-Mar-14
Alk
alin
ity
(m
g/L
)
Effect of CO2 Degassing on Alkalinity
C11 - ALK (No air)
C 11 - ALK (Air)
13.00
13.50
14.00
14.50
15.00
15.50
16.00
Total Dissolved
So
lid
Co
nte
nt
(g/L
)
Effect of CO2 Degassing on Dissolved Solids
Content
Solids (no air)
Solids (air)
7
7.5
8
0 5 10 15
pH
Time (minutes)
pH Increases as CO2 Degasses
Mixing of Leachate Streams – Organic Colloids
Organic colloids
Suspended in solution
Too small to settle
Usually (-) charged
If mixed with Ca2+ in
leachate, then
Repulsive force is reduced
agglomeration.
Effects of Mixing – Organic Colloids
High organic (gas condensate) mixed with high Ca2+ (Cell 9)
If agglomeration, then TS same & DS of mixture decreases.
No decrease in DS after mixing.
20.00
21.00
22.00
23.00
24.00
25.00
26.00
27.00
Apr 8 Apr 22
Solids
(g/L)
C9 & GC
Predicted TS
C9 & GC Actual
TS
C9 & GC
Predicted DS
C9 & GC Actual
DS
TS
TS
DS
DS
Effects of Mixing – Organic Colloids
High organic (gas condensate) mixed with high Ca2+ (calcium standard)
If agglomeration, then TS same & DS of mixture decreases.
No decrease in DS after mixing.
13.40
13.60
13.80
14.00
14.20
14.40
14.60
14.80
15.00
Apr 23
Solids
(g/L)
GC & Ca StdPredicted TS
GC & Ca StdActual TS
GC & Ca StdPredicted DS
GC & Ca StdActual DS
TS
DS
Effects of Mixing - pH Role of Saturated Conditions
Comparison of Annual Pipe Inspections
<--------------------------------------912'--------------------------------------------->
Aug-98
N 2014 Feet
1 o----------------------------------------------------------------------------------------- 875
2 o------------------------------------------------------------------------------------ 830
3 o--------- 90
4 o----------- 110
5 o------ 55
6 o----- 50
7 o---------------------------------------------- 460
8 o------------------------------------------------------------------------------- 780
9 o-------------------------------- 320
10
11
12
13
S
2013
1 o----------------------------------------------------------------------------------------- 900
2 o------------------------------------------------------------------------------------------ 912
3 o---------------------------------- 350
4 o------------ 125
5 o----- 52
6 o--------------- 151
7 o------------------------------------------------------------------------------------ 838
8 o------------------------------------------------------------- 618
9 o------------------------------- 310
10
11
12
13
<-----------------------------------------912'--------------------------------------------->
Aug-98
2008
1 o---------------------------------------------------------------------------------------- 875
2 o-------------------------------------------------------------------------------- 800
3 o----------- 113
4 o--------- 93
5 o----- 51
6 o------------------------ 239
7 o------------------------------------ 361
8 o----------------------------------------------------------------------------- 762
9 o------------------------ 237
10
11
12
13
N 2007
1 o---------------------------------------------------------------------------------------- 875
2 o--------------------------------------------------------------------------------- 806
3 o---------- 104
4 o--------- 86
5 o---- 43
6 o------------------------ 239
7 o---------------------------------------------------------------------------------------- 875
8 o---------------------------------------------------------------------------------------- 875
9 o--------------------- 206
10
11
12
13
o---|------|- -|------|------|------|------|---o
9 8 7 6 5 4 3 2 1
Header (2014)
Laterals Laterals
2007
2008 2014
2013
5/29/2014
5
Do Flooded Conditions Matter?
Different Exit Conditions
Geotextile Drainage material
(1 foot)
Ash
(4 feet)
Water in
Leachate out
Clear Pipe
Make volume through each pipe the same; so,
“loading” is the same for both pipes.
2. Constant Flow
1. Periodic:
Stagnate -> Release -> Stagnate
1% slope on pipe
Experiment in the dark, temperature
maintained at 35 C and nitrogen atmosphere.
Leachate from SWA – replaced every two weeks.
Do Flooded Conditions Matter?
Role of Microbes
Nucleation Sites or More?
Saturated Solution
CaCO3 in
Stir gently
Measure Ca2+
out
Add nucleation sites:
(silica sand, ash, microbes)
Role of Microbes
Nucleation Sites or More?
100 mL Plastic
syringe w
silica sand
Leachate
w and w/o live microbes
Drainage tube
Can create
saturated
conditions
Determine mass
of precipitate
From: Qabany (2012. Factors affecting microbe induced calcite precipitation
Role of Microbes
Precipitate Formation on Microbe Surface
From: Watson-Craik (1995) Selected approaches for the investigation of microbial interactions in landfill sites.
So, What Do We Know?
Virtually all liquids sampled have potential to scale.
Not seen everywhere; so, other factors contribute.
CO2 degasses, pH goes up, and CaCO3 forms.
Pumping and other turbulence seems to exacerbate.
No precipitate riser sampling tube removed from riser but scale on
coupon in manhole and pneumatic gas well pumps
“Inside” “Outside” Effects of Air?
5/29/2014
6
What We Know (continued)
Leachate chemistry
changes rapidly.
-80-60-40-20020406080
25
27
29
31
33
35
25-Mar 26-Mar
OR
P (
mV
)
Tem
pera
ture
(C
)
Temp
ORP
0
20
40
60
80
100
25-Mar 26-Mar
% D
O
% DO
0
5
10
15
20
25
7.82
7.84
7.86
7.88
7.9
7.92
7.94
7.96
7.98
4 6 8 10 12 14
%D
O
pH
Time (minutes)
pH
%DO
“4 mins. sucking air”
“1 day open flange”
What We Know (continued)
Leachate chemistry
changes rapidly with
different conditions.
0%
20%
40%
60%
80%
100%
% G
as
CH4 CO2 O2 Balance
String inside
closed manhole
yellowish
powdery
precipitate
What We Know (continued)
Standing worse than flowing leachate.
Anecdotal but crafting experiments.
To date, not able to demonstrate or rule out mixing
(either different pH or organics with Ca2+ rich
leachate) having effect.
What We Know (continued)
How crystals form and growth of crystal at point of
first formation may be important.
Precipitate formed all along
string but clog formed only
at point where two strings
are close enough together so
crystals can grow.
What to Do?
As from the beginning, SWA pushing forward:
“Treatments” being explored
Acid “drip”
Dilution
Electronic treatment
Operational changes
Limit mixing
Limit atmospheric and other “disturbances”
Limit turbulent conditions
Reduce leachate generation
Internalize cleaning? Less cost? More often?
Additional design changes?
Acknowledgements and Questions
Solid Waste Authority of Palm Beach County
Mark Eyeington
SWA Staff
Ron Schultz, Nathan Mayer, et. al
Dr. Meeroff (FAU)
Hinkley Center
John Schert, Tim Vinson, Rhonda Rogers-Bardsley
Dr. Townsend (UF)
Questions?
6/2/2014
1
Aeration Tests
pH v. time Turbidity v. time
6.8
7.0
7.2
7.4
7.6
7.8
8.0
8.2
0 50 100
pH
Elapsed Time (minutes)
Aerated
Control
0
20
40
60
80
100
0 50 100
Tu
rbid
ity
(N
TU
)
Elapsed Time (minutes)
Aerated
Control
Vibration Table Tests
Emulates aeration test using
foam
Rotates at 1rev in 1.096s
Initial weight: 171.23g
Weight over time:
23 hrs: 127.84g
Control (stationary):
Initial Weight: 179.31
23 hours: 138.36g
6/2/2014
2
Comparison
Initial After 4.5 Hours
After 23 hours
Control (Stationary)
Initial 23 hours
100 mL after 43 hours: 1 rev 1.4s
Additional Experiments
Vary the amount of foam, or leachate
Vary the speed of rotation
Aerate?
How long before crystals start to form?
Run experiment in fume hood
TAG Meeting May‐27, 2013: D Purdy 3‐Jun‐14
1
Leachate Loop 2.0
Circulates leachate continuously from 550 mL/min to 1500 mL/min at 40°C on a 1% slope, in two independent loops
Version 1.0 tested pH buffered and found no significant rock formation
Possible Inhibitors- Lack of air- Lack of a nuclei- Lack of flow obstruction
6/3/2014
Rock Theory Formation
Perforated Aeration Tubing
Aerated Leachate
Formed in Foam at Surface, around just a string
6/3/2014
Modification: Circulate & Aerate
6/3/2014
Aerated Leachate Circulation Video
6/3/2014
What’s Next?
Loop Modifications- Ventilation risers (manholes)- In-line obstructions (pins, tubing irregularities)- Centrifugal pumping
Once Solids Formed- Dilution & flow rates- Acid drip- Temperature differential
Audience Comments & Recommendations?
6/3/2014
5/29/2014
1
Hinkley Center Research at University of Florida
Environmental Engineering Sciences
Current Research Projects
• Beneficial Use of Wastes
• Landfill Design, Operation and Monitoring
• Groundwater Issues at Landfills
• C&D Debris Recycling
• Two current Hinkley Center Projects
Assessing Options for On-site Leachate and Groundwater Management Strategies at Florida Landfills
Developing Tool for Assessing Potential Iron Exceedances in Groundwater at Landfill Sites
Demonstration of WTE Bottom Use in Road
Construction in Pasco County
Overview Construction of field scale test strips using WTE bottom ash as an ingredient in road construction
Project currently underway (UF, Pasco County, Covanta)
• Laboratory environmental testing including LEAF
• Lab scale materials testing
• Development of mix designs
• Asphalt and concrete testing
• Groundwater monitoring
4
Test Strip Base Pavement
1 WTE Bottom Ash Asphalt
2 Limerock Asphalt
1
2
3
4
5
5/29/2014
2
WTE Bottom Ash as Base
5/29/2014
3
Thanks!
• Townsend Research Group Page • http://pages.ees.ufl.edu/townsend/
• Research publications • http://pages.ees.ufl.edu/townsend/publications/refereed-journal-
publications/
5/29/2014
4
5/29/2014
5
HMA with WTE Bottom Ash as Partial Aggregate Replacement
5/29/2014
6
Developing Tool for Assessing Potential Iron Exceedances in Groundwater at Landfill Sites
5/29/2014
7
Two Primary Issues
• Observations of surface water impacted by iron in the vicinity of landfills.
• Exceedances of iron concentrations in landfill groundwater monitoring wells above regulatory standards and health-based risk thresholds.
The iron becomes reduced, turning into a more soluble form (it moves from the soil to the groundwater). This can be caused by both biotic and abiotic conditions.
Fe+3 Fe+2 Ferric Iron Ferrous Iron
If the landfill is unlined, iron reducing bacteria can utilize organic matter in the leachate as food and iron in the soil as an electron acceptor.
solid dissolved
Reductive Dissolution
Summary of Biological Reductive Dissolution
• Iron occurs naturally in the solid phase as Fe+3 . Under reducing conditions, iron can be biologically reduced to Fe+2.
• This results in iron exceedances in groundwater.
• When groundwater hits the atmosphere again (at a seep or creek), the iron precipitates back out of solution.
Fe+2 (dissolved) Fe+3 (solid)
2
2224
7
4
12)(}{
4
1FeOHCOHsFeOOHOCH
Consider conditions prior to a landfill. Since the aquifer is at equilibrium with atmosphere (w.r.t. dissolved oxygen), the iron stays in the solid phase.
Vadose Zone
Aquifer
α-Fe2O3
oxygen
dissolved oxygen
An unlined landfill is constructed.
Vadose Zone
Aquifer
oxygen
dissolved oxygen
If organic matter is discharged into the aquifer, it can be used by bacteria as a food source. Once oxygen is used up (along other more favorable electron acceptors), iron will be utilized, resulting in reductive dissolution.
Vadose Zone
Aquifer
Fe+2
2
2224
7
4
12)(}{
4
1FeOHCOHsFeOOHOCH
5/29/2014
8
What is the role of landfill gas? Displaces oxygen Adds organic matter
oxygen
dissolved oxygen
2
2224
7
4
12)(}{
4
1FeOHCOHsFeOOHOCH
The displacement of air from the vadose zone can limit reaeration and promote oxygen depletion
Consider a liner. Can it have an impact?
2
2224
7
4
12)(}{
4
1FeOHCOHsFeOOHOCH
Can the liner sufficiently cut off reaeration such that iron reducing conditions develop?
oxygen
dissolved oxygen
0.1 mg/L 1 mg/L 10 mg/L 100 mg/L
100 µg/L 1,000 µg/L 10,000 µg/L 100,000 µg/L
0.01 mg/L
10 µg/L
Typical Range of Iron Concentrations
1,000 mg/L
1,000,000 µg/L
SMCL 0.3 mg/L
Health Benchmark (4.2 mg/L)
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
45,000
9/19/1991 6/15/1994 3/11/1997 12/6/1999 9/1/2002 5/28/2005 2/22/2008
Sample Date
Iron (
ug/L
)
Monitoring Well 7S
Iro
n c
on
ce
ntr
atio
n (
g/L
)
101
102
103
104
105
P-17 MW-2 5A 6 7 8D 9 11 12 13 14 15 16 P21 22 24 25 26 27 Leachate
GCTL
Health-based risk level
Potential Factors
• Reduction of DO in underlying groundwater due to physical constraint of oxygen recharge.
• Addition of organic matter as a result of construction activities (clearing, grubbing, new soils) and other site activities?
• Addition of organic matter as a result of storm water recharge?
Groundwater table
Fe+3 (s) Fe+2 (diss)
Fe+3 (s)
Fe+2 (diss)
5/29/2014
9
• Remedial • Install infrastructure to actively
remove/reduce iron concentrations from groundwater (pump and treat, permeable reactive barrier, air sparging)
• Passive • Predict the potential magnitude of
occurrence and adjust site boundary, zone of discharge, and/or monitoring requirements.
• Preventative • Construct the landfill foundation, liner
system and related infrastructure in a manner to prevent the formation of reducing conditions
Subject of recent research
Subject of research being presented today.
Subject of recently proposed research.
Developing a Tool for Assessing Potential Iron Exceedances in Groundwater at Landfill Sites
• Fundamental Objective: Build upon recent research conducted on iron at Florida landfills to develop an approach for evaluating future landfill sites for their potential to result in elevated iron concentrations in groundwater.
Dissolved Iron
(mg/L)
Upgradient Edge of Landfil l
Downgradient Edge of Landfil l
Vadose Zone
Surficial Aquifer
Air is depleted in vadose zone
Dissolved Fe(II) increases
Reaeration of aquifer
Decrease in Fe(II)
Big question: What distance is required
for Fe(II) to return to normal?
Co = Initial Concentration “leaving” the landfill footprint
Landfill
Vadose Zone
Aquifer
Distance from Landfill Edge
Dissolved Iron Concentration
Co
Tasks
1. Determining steady state iron concentrations
2. Modeling zone of discharge requirements
3. Approach development
4. Approach validation and refinement
Assessing Options for On-site Leachate and Groundwater Management
Strategies at Florida Landfills
5/29/2014
10
Research Agenda Item 7
What measures can be taken to prevent "reductive dissolution" of iron and arsenic beneath existing lined landfills? What are some low-cost design and construction options for getting oxygen into the soils? What are the options for new landfills that have not yet been constructed? How can we avoid creating new groundwater contamination problems due to “the shadow effect” underneath new lined cells which have not yet been built?
Research Agenda Items 12 and 13
Can constructed wetlands be utilized for onsite leachate treatment?
What are the onsite leachate treatment options for landfills that have high chloride levels in their leachate from waste-to-energy ash?
Options for On-Site Leachate Management
• Leachate recirculation
• Evaporation
• Wetlands
• On-site treatment plant with discharge to surface water or groundwater • High salt
• Low salt
Study Objectives
• Task 1: Update 2007 state of practice information
• Task 2: Critical review of ash landfill leachate management
• Task 3: Develop an engineering cost model for on site leachate treatment
• Task 4: Develop a tool to disseminate on-site leachate assessment
• Task 5: Develop design options for sub-liner vadose zone venting
• Task 6: Vadose zone venting simulation and economic evaluation
• Task 7: Preparation of final report
Task 1
• Update of current state of practice for leachate management at Florida landfills. The previous Hinkley Center study on leachate management practices in Florida will be updated (Townsend et al., 2007). Additional sites will be identified. Contact information for the majority of the facility operators already exists from the previous work. A specific objective is to identify all facilities with on-site leachate treatment components; these will serve as probable data sources for economic, energy and treatment efficiency data.
5/29/2014
11
Task 2
• Critical review of ash landfill leachate management practices. Given the Center Agenda Item 13, an in depth critical review, beyond those facilities in Florida, will be conducted for ash landfill leachate management. Leachate quality data, treatment experience, economic data and energy consumption information will be gathered from facilities around the country (and internationally if appropriate). The investigator already has contacts with many of the major companies involved in the WTE industry.
Task 3
• Development of an engineering cost model for on site leachate treatment. A spreadsheet economics model, one that includes energy consumption, will be developed for major on-site leachate treatment options. The source of the information will be from industry and facility contacts identified in Tasks 1 and 2, the scientific literature, communications with practicing engineers (included as part of the TAG), and consultation with equipment and technology vendors. The goal of the model will be to allow an interested party to enter site specific information, using defaults where necessary, and predict the costs of implementing various forms of on-site leachate treatment.
Task 4
• Development of a dissemination tool for on-site leachate assessment. The resulting model and associated information will be used to produce a tool for use by interested parties. The exact nature of the tool will depend on feedback from the TAG, but candidate formats are a spreadsheet, an interactive website, or an app.
Task 5
• Development of design options for sub-liner vadose zone venting. The investigator and his team will develop a set of potential design alternatives for meeting the objectives described earlier in this proposal. These design alternative are anticipated to include either air venting (forced aeration, induced soil venting, passive venting) or the addition of aerated water (possibly with amendments) using configurations/materials such as pipes, rock trenches, geonets, and high permeability soil layers. These configurations will be presented to the TAG for feedback before detailed simulation and costing.
Task 6
• Vadose zone venting simulation and economic evaluation. Appropriate design configurations developed in Task 5 will be modeled with respect to the potential to maintain baseline oxygen conditions under a landfill liner system. This will be modeled with standard hydraulic engineering techniques as well as multimedia transport models currently used by the investigator for reductive dissolution research. Based on these results, an engineering economic analysis and energy evaluation will be conducted for those scenarios/designs that are believed to suitably meet the desired objectives. The results will be compared to more traditional remedial alternatives.
Study Objectives
• Task 1: Update 2007 state of practice information
• Task 2: Critical review of ash landfill leachate management
• Task 3: Develop an engineering cost model for on site leachate treatment
• Task 4: Develop a tool to disseminate on-site leachate assessment
• Task 5: Develop design options for sub-liner vadose zone venting
• Task 6: Vadose zone venting simulation and economic evaluation
• Task 7: Preparation of final report
5/29/2014
12
Past Work
• Leachate Database
• Leachate Management in Florida
Source: Wastemap.org
Treatment Options for Landfill Leachate: 1. Discharge to WWTP
Landfill WWTP
61% of landfills surveyed in 2007
Treatment Options for Landfill Leachate: 2. Pretreatment, Discharge to WWTP
Landfill WWTP
22% of landfills surveyed in 2007
Treatment Options for Landfill Leachate: 3. Pretreatment, Onsite Discharge
Landfill
7% of landfills surveyed in 2007
Treatment Options for Landfill Leachate: 4. Recirculation
Landfill Landfill
19% of landfills surveyed in 2007 recirculated leachate 9% managed all leachate through recirculation
Treatment Options for Landfill Leachate: 5. Evaporation
Landfill Landfill Evaporation
5/29/2014
13
Treatment Options for Landfill Leachate: 6. Deep Well Discharge
Landfill
2% of landfills surveyed in 2007
Study Objectives
• Task 1: Update 2007 state of practice information
• Task 2: Critical review of ash landfill leachate management
• Task 3: Develop an engineering cost model for on site leachate treatment
• Task 4: Develop a tool to disseminate on-site leachate assessment
• Task 5: Develop design options for sub-liner vadose zone venting
• Task 6: Vadose zone venting simulation and economic evaluation
• Task 7: Preparation of final report
Waste to Energy Ash
• Burning municipal solid waste (MSW) creates ash which must be disposed of
• Ash can be placed in a landfill by itself (ash monofill) or with MSW (co-disposed)
• This can create leachate with very different characteristics than MSW leachate
Leachate Database • Contains various parameters over multiple years for 95 different lined landfills in Florida
• pH, ammonia, VOCs, heavy metals, TDS, conductivity, alkalinity, etc.
• Data from:
• Landfill operators
• FDEP files (including WACS)
• Allows us to compare leachate characteristics from different landfills over a desired time span
Ash leachate vs. MSW leachate
• Compared leachate data from ash monofill landfills and MSW landfills
• Looked at pH, TDS, COD, BOD, Chloride, Sodium TOC, Arsenic, Iron, and Lead
MSW
pH
• MSW data included 1925 data points from 88 landfills • Ash data included 47 data points from 4 landfills
5/29/2014
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TDS
• MSW data included 2517 data points from 95 landfills • Ash data included 41 data points from 4 landfills
COD
• MSW data included 567 data points from 47 landfills • Ash data included 6 data points from 2 landfills
BOD
• MSW data included 24 data points from 7 landfills • Ash data included 12 data points from 2 landfills
Chloride
• MSW data included 2757 data points from 86 landfills • Ash data included 42 data points from 4 landfills
Sodium
• MSW data included 787 data points from 56 landfills • Ash data included 39 data points from 4 landfills
TOC
• MSW data included 396 data points from 43 landfills • Ash data included 11 data points from 1 landfills
5/29/2014
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Iron
• MSW data included 782 data points from 55 landfills • Ash data included 40 data points from 4 landfills
Arsenic
• MSW data included 803 data points from 55 landfills • Ash data included 40 data points from 4 landfills
Lead
• MSW data included 748 data points from 54 landfills • Ash data included 43 data points from 3 landfills
Calcium Precipitation • Calcium precipitation from leachate
can clog leachate collection systems • Want to calculate a calcium
precipitation index for different types of landfill leachates
• There are many different calcium
precipitation indices • Langelier Saturation Index, Ryznar Index,
Aggressiveness Index, Momentary Excess, Calcium Carbonate Precipitation Potential (CCPP), etc.
Langelier Index for different types of leachate Type of leachate Landfill that samples were taken
from Langelier Index
Ash Monofill West Pasco County 0.45
Co-Disposal Palm Beach County NCRRF Class I Landfill
2.97
C&D West Pasco County 0.88
Mature Leachate New River Regional Landfill 1.31
Fresh Leachate New River Regional Landfill - 0.71
Study Objectives
• Task 1: Update 2007 state of practice information
• Task 2: Critical review of ash landfill leachate management
• Task 3: Develop an engineering cost model for on site leachate treatment
• Task 4: Develop a tool to disseminate on-site leachate assessment
• Task 5: Develop design options for sub-liner vadose zone venting
• Task 6: Vadose zone venting simulation and economic evaluation
• Task 7: Preparation of final report
5/29/2014
16
Cost Variables
• Volume
• COD and BOD
• Ammonical Nitrogen
• pH
• Total Dissolved Solids
Metal Concentrations
• Many exceed GWCTLs
• No direct removal route in biological processes
• Just diluting leachate in conventional WWTPs
Source: 2007 Hinkley Center Report: Lined Landfill Leachate Management in Florida
2007 Report: Biological 2007 Report: Physical/Chemical
Key Treatment Parameters
Source: Quan et al., 2013 – Electrochemical oxidation of….Biologically Treated Municipal Solid Waste Leachate in a Flow Reactor
Engineering Cost Model
Process 1 Process 2 Process 3
Parameters Removed
1
Costs 1 Costs 2 Costs 3
Influent Quality
Effluent Quality
Parameters Removed
2
Parameters Removed
3
5/29/2014
17
Adsorption
• Adsorption media requirements
Source: Halim et al., 2010
Membranes
Operational costs of an AnMBR Source: Lin et al., 2011 Desalination
Biological - Aerobic
Source: Liu et al., 2011
Oxidation
Study Objectives
• Task 1: Update 2007 state of practice information
• Task 2: Critical review of ash landfill leachate management
• Task 3: Develop an engineering cost model for on site leachate treatment
• Task 4: Develop a tool to disseminate on-site leachate assessment
• Task 5: Develop design options for sub-liner vadose zone venting
• Task 6: Vadose zone venting simulation and economic evaluation
• Task 7: Preparation of final report
Task 5: Develop design options for sub-liner vadose zone venting & Task 6: Vadose zone venting simulation and economic evaluation
Presented by Jaeshik Chung (PhD student)
5/29/2014
18
Sub-Liner Vadose Zone Venting Prevent plume migration especially developed under reducing condition (Mn(II), Fe(II)..) Oxidation of residual organic matter, ammonium-nitrogen Reducing risk of some contaminants via transformation to less hazardous form (As(III)
As(V)..) Cost-benefit analysis is required..
Introduction
Fig. Scheme of sub-liner vadose zone venting
Simulation of Vadose Zone Venting using Numerical Simulation Assuming predictable and continuous spatial-temporal variation across discrete points Can incorporate various initial/boundary condition
Simulation tool used in this study
Features (from GEOSLOPE web page)
•Analysis types include steady-state confined and unconfined flow, transient flow, 2-D flow in a cross-section or in plan view, and 3D axisymmetric flow.
•Boundary condition types include total head, pressure head, or flux specified as a constant or a function of time; pressure head; transient flux as a function of computed head; review and adjustment of seepage face conditions.
•Volumetric water content and conductivity functions can be estimated from basic parameters and grain-size functions. •Adaptive time stepping to ensure the use of optimal time steps in transient analyses with sudden changes in boundary
conditions. •Flow path deliniation.
AIR/W 2012 air flow analysis.
AIR/W is a finite element CAD software product for analyzing groundwater-air interaction problems within porous materials such as soil and rock. Its comprehensive formulation allows you to consider analyses ranging from simple, saturated steady-state problems to sophisticated, saturated/unsaturated time-dependent problems
Fig. Example of air-flow modeling into a tunnel
(Saturated) Aquifer
B
Landfill
A
Uniform Flow
Conceptual 2-D Model for Sub-Liner Venting
Vadose zone (K=8.64 m/days)
Replenishment O2
Replenishment O2
Replenishment O2
Replenishment O2
×
(-) (+)
Multiple Venting/Aeration
0 days
Air
Flux
(g/
day
s)
Distance (m)
-20,000
-40,000
-60,000
-80,000
-100,000
-120,000
0
20,000
40,000
60,000
0 10 20 30 40 50 60 70 80 90
Landfill
Effect of the combined Passive-venting/Forced aeration in vadose Zone
Forced Aeration
Passive Venting
Passive venting only
Forced aeration only
Forced Aeration
Passive Venting
Passive Venting
Summary & Further Study
Sub-Liner Vadose Zone Venting can be effective in preventing vadose zone from reducing condition
can prevent secondary contamination (e.g. reductive dissolution) in advance
Dimension and configuration of the venting/aeration pipes should be considered Distance between pipes, amount of pressure should be optimized Verification of the model using lab(field) data
(Saraya et al., 2014)
Study Objectives
• Task 1: Update 2007 state of practice information
• Task 2: Critical review of ash landfill leachate management
• Task 3: Develop an engineering cost model for on site leachate treatment
• Task 4: Develop a tool to disseminate on-site leachate assessment
• Task 5: Develop design options for sub-liner vadose zone venting
• Task 6: Vadose zone venting simulation and economic evaluation
• Task 7: Preparation of final report
5/29/2014
19
Questions?
Developing Tool for Assessing Potential Iron Exceedances in Groundwater at Landfill Sites:
Developing a Tool for Assessing Potential Iron Exceedances in Groundwater at Landfill Sites
• Fundamental Objective:
Build upon recent research conducted on iron at Florida landfills to develop an approach for evaluating future landfill sites for their potential to result in elevated iron concentrations in groundwater.
Dissolved
Iron (mg/L)
Upgradient Edge of Landfil l
Downgradient Edge of Landfil l
Vadose Zone
Surficial Aquifer
Air is depleted in vadose zone
Dissolved Fe(II) increases
Reaeration of aquifer
Decrease in Fe(II)
Big question: What distance is required
for Fe(II) to return to normal?
Evaluation of Iron Concentrations at Landfill Sites from Existing Database
• Database was created to evaluate iron concentrations at landfills which were “nominated” from DEP District staff;
• Study evaluated approximately 76 landfills in 4 DEP Districts: • NE District: 46 • NW District: 15 • SW District: 14 • Central District: 1
• All types of landfills were studied: • Class I: 53 % • Class II: 10 % • Class III: 24 % • Combination of Classes: 13 %
Landfill Study
• Historical monitoring results obtained from DEP’s Water Assurance Compliance System (WACS);
• Historical vs. latest 2-year average; • Box and Whiskers plots for water quality <2 years; • Impacted or monitored aquifers were noted; • Landfills divided into groups:
• Unlined vs. Lined • Background vs. Detected Iron Concentrations
• Background Iron > Detected Iron • Background Iron = Detected Iron • Background Iron < Detected Iron
5/29/2014
20
Box and Whiskers Plots
Wide Range of Fe Concentrations
FeBackground >> FeDetection
High Background Concentrations
Low Fe Background High Fe Detected
Determination of steady state iron concentratio
5/29/2014
21
Incubator
Soil samples
Cellulose (additional organic matter)
& DI water
N2 purging
250 mL Glass bottle
pH ORP Fe+2
Previous Research - Biological reducing test
Method to test potential of soil to undergo reductive dissolution.
Carbon source for iron reductive bacteria
-60
-40
-20
0
20
40
60
80
100
120
140
160
0
10
20
30
40
50
60
70
0 5 10 15 20 25 30 35 40 45 50
OR
P (
mV
)
Ferr
ou
s (m
g/L)
Time (days)
Biological reducing test results for selected soils Niceville Sarasota
Aucilla
Iron concentration increase and ORP decrease over time.
-70
-60
-50
-40
-30
-20
-10
0
10
20
0
20
40
60
80
100
120
140
0 5 10 15 20 25 30 35 40 45 50
OR
P (
mV
)
Ferr
ou
s (m
g/L)
Time (days)
-100
-50
0
50
100
150
0
10
20
30
40
50
60
70
0 5 10 15 20 25 30 35 40 45 50
OR
P (
mV
)
Ferr
ou
s (m
g/L)
Time (days)
0
50
100
150
200
250
0
50
100
150
200
250
0 5 10 15 20 25 30 35 40 45 50
OR
P (
mV
)
Ferr
ou
s (m
g/L)
Time (days)
ORP Fe
Klondike
Research related to this project Anaerobic Batch Tests
• Incubation of soil and DI water at a L:S of 1:1 under an anaerobic environment
• 30 day incubation to allow for steady state
• Photocatalytic reactions were avoided
• Parameters measured: • DI: pH, ORP, DO, conductivity, total Fe and As concentrations, NPOC, TN
• Soil: Moisture content, OM content, extractable NH3, pH, ORP, CEC, AsTOT, FeTOT, amorphous iron
• Extract: pH, ORP, DO, conductivity, total Fe and As concentrations, NPOC, TN, and Fe(II)
Results
SOIL ID SAMPLE DESCRIPTION
Soil 1 Baker Landfill (Okaloosa County)
Soil 2 Aucilla Area Landfill
Soil 3 Klondike Landfill
Soil 4 Sarasota County Landfill
Soil 5 North Central Landfill (Polk County) Soil Sample
1 2 3 4 5
Fe
(II
) m
g/L
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Relating anaerobic batch tests to field data • Mass of iron in the soil beneath the landfill:
• Anticipated percentage of Fe(II) to be released:
• Anticipated mass of Fe(II) to be released:
• Anticipated concentration of Fe(II) under the landfill:
5/29/2014
22
Anticipated concentrations from mass balance calculations
Soil Fe(II) conc.
Soil + DI mg/L
FeTOT mg/L
Anticipated Fe(II)
concentration mg/L
1 0.05 14552 0.53
2 0.10 14038 1.06
3 0.04 10554 0.42
4 0.60 2780 6.36
Landfill Average Fe(II)
Conc. mg/L
Minimum Fe(II) Conc.
mg/L
Maximum Fe(II) Conc.
mg/L
Median mg/L
1 10.4 0.000 120
0.049
2 2.80 0.011 70.8 0.123
3 15.2 0.002 67.9 8.27
4 45.1 0.370 136 40.7
5 9.32 0.010 133 0.551
Fe(II) concentrations from historical groundwater monitoring data
Why is data not correlated? • Lack of organic matter in the DI • Lab conditions did not simulate conditions beneath the landfill
accurately • Incubation period not long enough • L:S not comparable to that in the field
Extraction Solution
DESCRIPTION
Solution A Municipal Solid Waste leachate (Age = 8 months)
Solution B Municipal Solid Waste leachate (Age>15 years)
Solution C Construction and Demolition debris landfill leachate
Solution D Water collected from MSW landfill storm water ponds
Anaerobic Batch Tests with different source of organic matter
Fe(II) released with different organic matter sources
Column Leaching Test
Aerobic Conditions
Anaerobic Conditions
5/29/2014
23
Soil Characterization
Parameter Units Soil sample
pH S.U. 5.44
ORP mV 120
Fe(total) mg/kg-dry 14,038
Amorphous iron mg/kg-dry 625
Organic matter % 1.48
Leachate Characterization
Parameter Units Value
pH S.U. 7.87
ORP mV 189
Conductivity µS/cm 13,910
DO mg/L 1.27
Fe(total) mg/L 8.84
COD mg/L 2171
TOC mg/L 415.4
Column Test Under Aerobic Conditions Using DI Water
Aerobic conditions using DI water
Cumuilative LS Ratios
0 2 4 6 8 10 12
Ferr
ou
s C
on
cen
trati
on
,mg
/L
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
OR
P
105
110
115
120
125
130
135
140
145
Fe(II)
ORP
MDL
Column Test Under Anaerobic Conditions
Anaerobic conditions using DI water
Cumuilative LS Ratios
0 2 4 6 8 10 12
Ferr
ou
s C
on
cen
trati
on
,mg
/L
0.0
0.1
0.2
0.3
0.4
0.5
0.6
OR
P
-400
-300
-200
-100
0
100
200
Fe(II)
ORP
MDL
Column Test Under Anaerobic Conditions Using Leachate
Anaerobic conditions using leachate
Cumuilative LS Ratios
0 2 4 6 8 10 12
Ferr
ou
s C
on
cen
trati
on
,mg
/L
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
OR
P
-330
-320
-310
-300
-290
-280
-270
-260
-250
Fe(II)
ORP
MDL
DI Water and Leachate Column Leaching Ferrous Comparison
Cumilative LS Ratios
0 2 4 6 8 10 12
Cu
mu
ilati
ve R
ele
ase o
f F
err
ou
s,m
g/k
g
0
2
4
6
8
10
12
14
16
18
DI water
Leachate
Bottle leaching test
5/29/2014
24
Presented by Jaeshik Chung (PhD student)
Developing Tool for Assessing Potential Iron Exceedances in Groundwater at Landfill Sites: - Simulation of Fe(II) Front in Terms of Aquifer Reaeration -
What is a modeling? Prediction of future status based on previous data Can be applied to various fields (Finance, medical, Population growth) Creditable Previous data is required
Modeling of solutes (contaminants) transport in subsurface
Advection-Dispersion(-Reaction) equation Reactions: Sorption/desorption, Dissolusion/precipitation, decay (biodegradation), Various initial & boundary conditions can be considered
Methods and software for solving A-D-R equations Analytical (mathematical) methods (models):
Ogata & Banks (1961), Van Genuchten (1981), CXTFIT (1995) Numerical methods (models):
HYDRUS (1998), ModFlow (1998), TOUGH2 (1999) Hybrid..
Introduction
Fig. Example of modeling
(Rockware, PetraSim webpase)
Fig. Examples of fluid (heat) transport modeling in subsurface
C (x , t) = ???
(Saturated) Aquifer: 10% Goethite (FeOOH)
K=1x10-12m2
n=0.3
B
Landfill
A
Uniform Flow
Conceptual 1-D Model for Aquifer Reaeration
V = 0.33 x 10-5m/s Q = 0.001 kg/s
C0: Fe(II) 10-4 mol/L (5.6 mg/L)
Replenishment O2
(Unsaturated) vadose zone
C0 O2 initial
Multi-phase simulation using numerical method, TOUGH2 (Pruess, 1991) Transport of Unsaturated Groundwater and Heat TOUGH2 is a general-purpose numerical simulation program for multi-dimensional fluid and heat flows of multiphase,
multicomponent fluid mixtures in porous and fractured media. PetraSim5 is used for pre/post processing (e.g. mesh generation, data print)
Simulation tool used in this study
Fig. Space discretization and geometry data in the integral finite difference method
(Oldenburg & Pruess, 1993)
Governing Continuity equation (Conservation of mass)
Validation of the Model using Hand-Calculation
Validation of Reaction term using Advection-Dispersion-Reaction equation
One of the solution is provided by Ogata and Banks (1961):
C(x,t) = (Co/2).{ erfc[(x-vxt)/2(Dxt)1/2] + exp(vxx/Dx).erfc[(x+vxt)/2(Dxt)1/2] } (where erfc(b) is called the complementary error function (1 – erf(b)))
The second term in the solution involving the exponential function is almost always small and can be neglected. The simplified solution becomes:
C(x,t) = (Co/2).erfc[(x-vxt)/2(Dxt)1/2]
Effect of Aquifer Reaeration on Fe(II) oxidation
Distance and time required for Fe(II) to return to background level
O2 (Initial)
O2 (transient)
5/29/2014
25
Effect of Sorption on the Fe(II) front
0 years 0.05 years 0.1 years 0.2 years 0.3 years 0.5 years 0.7 years 1 years
kd=0.1 L/kg Retard. factor 2
No Sorption
Effect of Initial O2 in GW on Fe(II) front (3.2 ppm vs. 32 ppm)
Summary & Further Study
Continuous spatial-temporal variation in concentration could be successfully tracked Can estimate the Fe(II) in downgradient according to the Initial condition (C0) and boundary conditions (O2, mineral composition, ..)
Various compositions in aqueous ion and composed minerals other than Goethite Nitrogen, Surfer, Ferryhidrite (Fe(OH)3; Amorphous), Mignetite (Fe2O3; Crystal), …
Incorporating vadose zone physics (2-D expansion) Quantification of O2 (g) diffusion from vadose zone Considering (O2-saturated) rainfall Verification and refinement of the model using lab (field) data
Questions?
1
Technical Advisory Group Meeting
1. “Reducing The Iron Pollution In Landfill Soils By Using
Aeration Wells”
Ahmed Albasri, MSCE Candidate Department of Civil, Environmental & Geomatics Engineering
Laboratories for Engineered Environmental Solutions
Presentation to the HCSHWM Technical Advisory Group
The Problem
• Iron is being detected in monitoring wells downstream of Florida landfills
• State Enforceable Secondary Drinking Water Standard (62-550 FAC) and Groundwater Cleanup Target Level (62-777 FAC) set at 300 µg/L (0.3 mg/L)
• Evaluation monitoring required by 62-701.510(7)(a) if levels are detected significantly above background
• Requires installation of compliance monitoring wells
• Requires additional sampling
• Stipulates corrective measures (62-780 FAC) • Pump & treat with filtration, biological treatment, chemical
treatment
26
Fe
55.845
Presentation to the HCSHWM Technical Advisory Group
Case Study
• Iron presence was detected in 22 observation wells on 29 April 2008 in
North Central Landfill (NCLF) higher than PDWS (Florida Primary
Drinking Water Standard) which is 300 µg /L
• High Iron presence exceed the CTL (Clean-up Target Level) which is
3000 µg /L were observed in 15 monitoring wells including compliance
wells
Presentation to the HCSHWM Technical Advisory Group
Presentation to the HCSHWM Technical Advisory Group
Treatment Method
• Soil aeration is one of the successful decontamination processes used to treat volatiles
• Groundwater circulation well (GCW) systems attempt to create a 3-dimensional circulation pattern in an aquifer by drawing ground water into the well
• The main goal of this system is to oxidize the Iron in the soil from Fe(ll) form to Fe(lll) form, which is insoluble to stop Iron migration with ground water
• The advantage is that treatment of the contaminated groundwater takes place below grade and does not require that it be pumped out the ground
• Another advantage over conventional pump-and-treat is that GCWs induce a groundwater circulation zones that “sweeps” the aquifer
• Pump-and-treat systems cause drawdown around the well, leaving contaminated zones that are not treated
Presentation to the HCSHWM Technical Advisory Group
Air
Sand Filter
Another
Option • In situ remediation
process
• Metals and
radionuclides
• Volatiles
• Biodegradables
• Simple to operate
• Rapid
• Inexpensive
Reaction Zone
2
Presentation to the HCSHWM Technical Advisory Group
Objectives
1. To conduct lab experiments for iron (and possible
co-contaminant) removal in-situ using groundwater
recirculation well technology.
2. To find the required treatment capacity to
decontaminate the high elevated iron for certain
parameter
Presentation to the HCSHWM Technical Advisory Group
Samples Collection
• Boca soil samples were collected
• 4 samples were collected from Polk
County Landfill
• The first 2 samples where collected
from SE & NE of the site on
05/11/2011
• The second set of 2 were collected
from SE & SW on 11/10/2011
• The samples collected after
removing the top 15 cm from the
soil surface
• The soil has a homogeneous profile
• The samples were kept at room
temperature until testing
Presentation to the HCSHWM Technical Advisory Group
Research steps include :
• 1. Show that GCW is valid process to reduce the iron
in soils and elaborate performance charts prove the
desire results.
• 2. develop empirical estimations to set the
parameters depend on the experiment success as
mentioned above.
• 3. estimate the site cost for the treatment technique
after set the empirical parameters
Presentation to the HCSHWM Technical Advisory Group
Aquarium Experiments
• GCW model consists of the following parts:
• Transparent glass aquarium of (11.5 × 5.5 × 7.75) inch
dimensions
• A prototype of sparging well (vinyl tube ½” outside DIA)
• Two well screens with 4 slits/cm and 1 inch long separated
by 1 inch
• Vinyl tube within a tube to create the negative pressure
head of the air bubbles which induces circulation
• Gravel filter around the well with #20 Sieve for a diameter of
1.5 inch around the well
• Aquarium Air pump (elite 799) with 1 cubic ft / min flowrate
and with pressure of 1.0 PSI
Presentation to the HCSHWM Technical Advisory Group
Presentation to the HCSHWM Technical Advisory Group
Phase1 :
Test with Boca Raton soil • For conservative demands the test has started with soil from Boca
Raton to prove the ability of contaminant removal
• Boca soil is sandy as it lies in the Eastern Sandy flatland area
according to physiographic region.
• The geographical distribution of the soil in Florida reflects that Boca
soil is sposdsol type which has an expected iron content of 300 mg/kg
• Iron reference of 1000 mg/L was added to the water and soil in the
aquarium
• Two aquarium tests were running simultaneously to obtain replicate
results
3
Presentation to the HCSHWM Technical Advisory Group
Presentation to the HCSHWM Technical Advisory Group
Results of Boca Soil Tests
• Iron concentration found in Boca Raton was close to the theoretical data (~300 mg/kg) for all samples
• Iron removal readings through the 72 - 264 hr running time show arbitrary numbers as it cannot be decided whether the Iron is in Fe(II) or Fe(III) form as they both can be occur in spectrometric test
• Independent lab results were also inconclusive due to the limitations of the phenanthroline colorimetric method
Presentation to the HCSHWM Technical Advisory Group
0
100
200
300
400
500
1 2 3 4
fFe m
g/K
g
Boca Raton test Results
compare with chen.1999
Fe soil test without rover
Fe with Rover
Spodosols (0.033*10^4)
0
0.5
1
1.5
2
0 1 2 3 4 6 24 48 54 72
Fe(C
/C0)
Time (hours)
Iron reading in Boca Soil
Sample1
Sample2
Presentation to the HCSHWM Technical Advisory Group
Results of Boca Soil Tests
• Further test has been conducted for testing the
samples range (72-234) which where 6 samples
(116.5, 140, 163.5, 180.5, 203.45, 233.5) hours for
each one of the 2 aquariums.
• Rerun the previous 10 samples (0, 1, 2, 3, 4, 6, 24, 48,
54, 72) hours to conduct the complete profile for the
Boca 2 soils aquariums.
Presentation to the HCSHWM Technical Advisory Group
0
5
10
Fe
mg
/L
Time (hours)
Iron Reading in Boca Soil
Sample 1
Sample 2
0
5
10
Fe
(C/C
0)
Time (hours)
Iron reading in Boca Soil
Sample 1
Sample 2
Presentation to the HCSHWM Technical Advisory Group
Conclusion in Phase 1
• The trend of samples collected from running Boca Soils don’t
represent constant removal process which may attribute to several
factors :
1- PH : we discover by contacting Hach company that samples PH
should be set between (3-5) to get best results from the
spectrophotometer
2- Iron Reference: the samples has been tested for process better
performance reading with 1000 mg/L Iron reference but the resulted
Iron after lab. Preparation wasn’t give the desired number.
3- Testing tools : spectrophotometer cuvettes was used for other lab
purposes with different material types may not be well clean and react
with FerroVer that should be added to get the Iron reading, Further
cleaning steps has been taken by rinse with nitric acid path to ensure
that no further interference occur.
4
Presentation to the HCSHWM Technical Advisory Group
Phase2 :
Test with Polk County soils ( 4 Aquariums ) • 3 samples for each one of the 4
samples collected in May and
November -2011 for Iron digestion
Hot Block experiment are
processed
• 2 Aquariums of the SE and NW
landfill soil which was collected in
May 11-2011 are built
• The 2 which were collected in
November are in the dried and built
( they were needing further process)
Presentation to the HCSHWM Technical Advisory Group
Test with Polk county Soils
• 4 Aquariums for the soils Collected from Lakeland landfill were built in
this phase.
• Same Aquarium Construction were adopted for Boca tests in phase 1
• SE & NE soil samples were sandy profile which enable setting them
quickly in their 2 test aquariums.
• SE & SW were need further process as they were clay constructed soil
(soils had been dried for 24 hour with 100 degree Celsius )
• 4 samples were crashed with hammer and settled in 2 aquarium.
• 94 mg/L Iron has been created FeCl2 with HCl
• 4 Aquariums were saturated with Iron for 1 day
• 4 Aquarium test were on 10/31/2012
Presentation to the HCSHWM Technical Advisory Group
Presentation to the HCSHWM Technical Advisory Group
Testing Results
• Spectrophotometer test conducted and samples
collected 1,2,4,6,8 & 12 hours
• The results show fast decreasing after 1 hour of
running the experiment in 4 aquariums
• Iron reading were 0.11-0.08 mg/L for the 4 test
experiments after 1 hour running and keep
decreasing through time.
Presentation to the HCSHWM Technical Advisory Group
0 1 12
FE 94.3 0.1195 0.0909
0
50
100
Iro
n
Fe for NE 05/11/11
0 1 12
FE 94.3 0.08969 0.05764
0
50
100
Iro
n
Fe for SE 05/11/11
0 1 12
FE 94.3 0.08 0.0933
0
50
100
Iro
n
Fe for SW 11/9/11
0 1 12
FE 94.3 0.08 0.04
0
50
100
Iro
n
Fe for SE 11/9/11
Presentation to the HCSHWM Technical Advisory Group
5
Presentation to the HCSHWM Technical Advisory Group
Phase 2 conclusion
• Fast degradation of Iron led to believe that another
factor interfered to that reduction
• Soil chemistry may contribute to accelerate that fast
reduction.
• Iron tested before charging into the soil and it was
shown 94.3 mg/L which draw suspicious that iron
breakdown in the first hour of running the aquariums
test.
Presentation to the HCSHWM Technical Advisory Group
Phase3 :
Test with Polk County soils ( 2 Aquariums )
• Fast degradation of Iron lead to suspect that soil
may play vital rule by adsorbing the Charged Iron.
• Further step developed to charged the 4 Aquariums
with Iron to saturation or to get variance less 10 %
between add and another.
• Charging and monitoring process took 3 weeks
when evaporating process were 4 weeks
Presentation to the HCSHWM Technical Advisory Group
Saturated Aquarium Experimenting
• 365 mg were charged for each Aquarium.
• Aquarium 1 and 2 show less than 10% variance
which make them ready to test
• Aquarium 3 and 4 show higher percent of change.
• The tested samples were diluted 50 time to obtain
reliable spectrophotometer reading
Presentation to the HCSHWM Technical Advisory Group
Iron Reference Charging process
Presentation to the HCSHWM Technical Advisory Group
Phase 3 Results
• Aquarium 1 and 2 were obtain slope close to zero
with less than 10 % variance through saturation
made them qualified for starting the experiments
• 02/24/2013 the qualified aquariums run started.
• Sampling time were concentrated in first hour as
degradation were expected to occur.
Presentation to the HCSHWM Technical Advisory Group
Iron degradation through
experimenting
6
Presentation to the HCSHWM Technical Advisory Group
• The chart show that testing the aeration process
with Aquarium 1 show the desired degradation.
• Aquarium 2 didn’t show any critical change through
the aeration process as the Iron content was low and
not easy to follow in addition to the soil high ability
to adsorb the charged Iron.
Presentation to the HCSHWM Technical Advisory Group
Conclusion Phase 3
• According to the last 2 test conducted on Lakeland
soil, they both showed decreasing occur through
remediation process using sparging well technique.
• Further test for the 2 samples left is going to
consolidate the principle targeted to using that
technology as remediation solution.
Presentation to the HCSHWM Technical Advisory Group
Adjusting the process • Further test planned to be conducted to enhance the results were
obtained by running the 2 aquariums conducted last February
• The non tested Aquariums 3 and 4 whom contain the SE and NE soils
of Lakeland collected in 05/11/2011 are recharged with iron referenced
diluted with lake water to elevate the iron level to the limit removal can
be shown in case of GCW model were run.
• Aquarium 2 were added to consolidate the next run results and it’s
charged from the same iron source aquariums 3 and 4 provided with.
• The R2 value didn’t show significant correlation with recharging
process, that led to standing for more research to show the reason
beyond the iron non increase occurrence despite the increase in patch
recharge from 100 mg/L to more than 200 mg/L.
Presentation to the HCSHWM Technical Advisory Group
y = -0.0002x + 7.5072 R² = 0.5372
0
0.01
0.02
0.03
3/7/2013 3/17/2013 3/27/2013 4/6/2013 4/16/2013 4/26/2013 5/6/2013 5/16/2013 5/26/2013 6/5/2013 6/15/2013 6/25/2013
Ex/C
um
l
Date
Aquarium -2-
exist / Cumulative
Linear (exist / Cumulative )
y = -5E-05x + 1.9645 R² = 0.248
0
0.005
0.01
0.015
2/15/2013 3/7/2013 3/27/2013 4/16/2013 5/6/2013 5/26/2013 6/15/2013 7/5/2013
Ex/C
um
l
Date
Aquarium -3-
exist / Cumutative
Linear (exist / Cumutative)
y = -0.0004x + 15.167 R² = 0.4915
0
0.02
0.04
0.06
0.08
0.1
2/15/2013 3/7/2013 3/27/2013 4/16/2013 5/6/2013 5/26/2013 6/15/2013 7/5/2013
Ex/C
um
l
Date
Aquarium -4-
Exist/Cumulative
Linear (Exist/Cumulative )
Presentation to the HCSHWM Technical Advisory Group
• One more sample had been taken from Aquarium 3
from out side the prototype well, and the result
showed huge difference between the 2 reading till
it’s over what the specterphotomenter can handle
and need for more dilution to realize the amount of
iron, the samples were pipette before recharging the
aquarium with more iron
Presentation to the HCSHWM Technical Advisory Group
7
Presentation to the HCSHWM Technical Advisory Group
• That show obviously that the iron adding process
didn’t show iron percolation in the soil to increase
the soil content of it but stay on the upper layer and
evaporate water leaving the iron as impermeable
layer as shown in the sketch below
Presentation to the HCSHWM Technical Advisory Group
Phase4 :
Test with Boca Raton soil ( 30
gallons Aquariums , continuous
feeding with iron reference)
Presentation to the HCSHWM Technical Advisory Group
Design adjustment
• Research committee suggest to increase the scale of
the aquarium cell to achieve better water head loss
between the feeding side and the collecting side
which included in the system too.
• Suggested aquarium design has been approved by
the committee .
• Simulation was achieved by utilizing soil from Boca
Raton has sandy profile to conduct circulation in
optimal shape.
Presentation to the HCSHWM Technical Advisory Group
New set specification
• The new treatment cell
is 30 gallons bin used
as aquarium holding
the soil and the feeding,
discharging lines, in
addition to the
treatment sparging well.
Presentation to the HCSHWM Technical Advisory Group
• The aquarium has
discharge point to test
the obtained reduction
in iron from treatment
process.
• Feeding Iron set to be
200 mg/L obtained from
delusion of 1000mg/L
patch
Presentation to the HCSHWM Technical Advisory Group
• Aquarium shape is
trapezoid and filled to the
shown dimensions with
Boca Raton sandy soil .
• The aquarium set to be
charged with Iron water and
discharged using O.S.E S40
½”x5’.025 PVC pipe
8
Presentation to the HCSHWM Technical Advisory Group
• The charge and discharge
pipes system includes 2
pipe of 13 inch long each
capped on both sides and
perforated 1 inch c/c to
insure flow continuity and
avoid clogging related to
rust and bacterial growth.
Presentation to the HCSHWM Technical Advisory Group
• Each one of the pipes
system is covered with thin
layer of grovel to permit
water flow through pipes
without get clogged with
silt as system flow
protection step ( compatible
for GCW protection
process)
Presentation to the HCSHWM Technical Advisory Group
Finding ROI
• The soil tested currently to
find the permeability
coefficient value k using
constant head hydraulic
conductivity test .
• The permeability for Boca
Soil is required to
determine (ROI) radius of
influence sparging well
can obtian
Presentation to the HCSHWM Technical Advisory Group
Experiment Run
• The test set to be processed
at Boca water treatment
planet lab for 2 reasons:
1- Ability to provide continues
raw ground water to the
tested system.
2- safe discharge to the water
coming out of the system
which is contain
considerable amount of Iron.
Presentation to the HCSHWM Technical Advisory Group
Step to be Achieved
• Determine the K value to estimate the radius of
influence
• Determine the flow velocity V through the system to
set the feeding system requirements.
• Determine the reaction time needed for adequate
Iron removal using GCW
• Develop design criteria for GCW for iron removal
Presentation to the HCSHWM Technical Advisory Group
Recommendations
• Checking longer range of experiment running may
results in better removal action occurrence.
• Keep feeding the aquarium with water to keep the
GCW active to work as it should be totally
submerged with ground water to obtain maximum
performance
• Cleaning lab tools well as the test is very sensitive
for interference (rinsing with DI water 3 time may not
be sufficient to ensure cleanness)
9
Presentation to the HCSHWM Technical Advisory Group
Acknowledgement
• Dr. Daniel Meeroff ( my Advisor )
• Dr. Khaled Sobhan
• Dr. Fred Blotescher
• All whom keep motivate me toward research
• Audience
Presentation to the HCSHWM Technical Advisory Group
Presentation to the HCSHWM Technical Advisory Group
I Have Questions for YOU
• I am presuming that ROI for recharged well is same
for extraction well with inverted cone of influence,
anything might be against my assumption ?
• Do you have any suggestions for an appropriate test
method to speciate the forms of iron, Fe(II) and
Fe(III), in groundwater and soils?
• Where else is iron reductive dissolution a problem?
• What are the costs associated with remediation of
iron dissolution?
1
Presentation to the Joint Technical Advisory Group MeetingWest Palm Beach, FL, May 27, 2014
Florida Atlantic UniversityCollege of Engineering & Computer Science
“Safe Discharge of Landfill Leachate to the Environment ”
Joseph Lakner.
Laboratories for Engineered Environmental Solutions
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Problem Statement• In South Florida, several landfills combine leachate
for disposal• Active leachate
• Mature leachate
• Partially closed landfill leachate
• The partially closed landfill leachate can account for 10-25% of the overall leachate flow• 20,000 – 200,000 gpd
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Dyer Park Leachate Quantity
0
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
6,000,000
1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013
Lea
chat
e G
ener
atio
n (
gal
lon
s p
er m
on
th)
Year
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Problem Statement
• Current disposal methods is deep well injection.
• Is there a better way to manage these liquids cost effectively?
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Photocatalytic Oxidation• Ultraviolet Radiation +
Semiconductor
• Simple, one stage process
• Ultraviolet Light
• Titanium Dioxide
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
How Does Photocatalysis Work?
h+
e‐Mn+
(aq)
M0(s)
[ Photoreduction ]of metals
+
hν[ Photooxidation ]
of organics
Oxygen
Water
TitaniumDioxide
Proton
Hydroxyl radical
Water and carbon dioxide
2
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Beneficial Use of Closed Leachates
Surface Water
Discharge
• The most complex discharge requirements
Industrial Reuse
• Irrigation, cooling water
• Hardness scaling
Dilution Water
• To reduce leachate clogging
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Leachate Water QualityZX FDEP
Freshwater Criteria Target
(62-777 F.A.C.)
Typical SWA
Leachate
Dyer ParkLeachate Average
Dyer Park Range
pH n/a 7.2 ± 0.3 7.2 ± 0.3 6.9 – 7.7
TDS (mg/L) 500 13,4000 ± 5400 2280 ± 510 1700 – 2845
DO (mg/L as O2) 5.0 0.9 ± 1.3 4.9 ± 0.6 3.9 – 5.3
COD (mg/L as O2) n/a 5380 ± 5300 390 ± 260 74 – 780
NH3 (mg/L NH3-N) 0.02 – 2.8 2390 ± 2740 440 ± 80 360 – 540
Alk (mg/L as CaCO3) n/a 3330 ± 2220 1635 ± 160 1425 – 1850
Ca (mg/L as CaCO3) n/a 1500 ± 2030 535 ± 110 440 – 700
Fe (mg/L) 0.3 – 1.0 12.4 ± 8.0 9.4 ± 4.0 6.2 – 13.8
Pb (μg/L) 0.02 35 ± 41 7.7 ± 4.6 0.02 – 12.1
Color (PCU) n/a 130 ± 110 130 ± 110 40 – 250
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Falling Film Reactor
• Reservoir (10L)
• Temperature Sensor
• Pump (360 L/h)
• Flow Regulator
• Sampling Port
• 3 Way Valve
• Weir Compartment
• UV Power Source (120W)
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Experimental Protocol• Experiments will run for 24 hours
• Samples will be collected at 30 minute intervals
• Sample collection procedure is as follows:
• Do not turn off reactor, take samples from reservoir
• Take a sample (40 ml) and then placed in tubes to be centrifuged.
10
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Experimental Protocol• UV sensor will be used to measure the intensity in
the reactor.
• Monitor offgas to determine where ammonia and COD end up.
11 Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Plan of Study• Objectives
• Collect New Leachate Specimens
• Achieve FAC 62-777 Requirements
• Optimize Falling Film Reactor For:
• Ultraviolet Spectrum
• Catalyst Dose
• Catalyst Recovery
• Update Cost
3
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Plan of Study• Objectives Continued
• Assess Residuals• Determine the recovery number
• Perform TCLP analysis of spent catalysts
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Plan of Study• We will work with FDEP to establish the appropriate
target limits for each beneficial use
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Falling Film Reactor
Titanium Dioxide Absorption Spectrum
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Catalyst Optimization Curve
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
0 5 10 15 20 25 30 35 40 45 50
% COD REm
oval at 24 hours
TiO2 dosage (g/L)
y = 2.9648ln(x) + 19.876R² = 0.9689
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
0 5 10 15 20 25 30 35 40 45 50
% COD Rem
oval at 24 hours
TiO2 dosage (g/L)
• Follows asymptotic curve
• After 10 g/L efficiency only increases slightly
• 160 – 200 hours to reach target removal (800 mg/L) at 4 – 10 g TiO2 per liter
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Leachate Bench Tests• Actual leachate:
• Broward County
• SWA
• Polk County
• COD was reduced to permissible levels in t < 45 min
• Complete mineralization in 4 hrs
• Pre-filtration was not necessary
CODo ~ 1,000 mg/L
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Bench reactor
• UV = 450 W lamp
• Vol = 375 mL
• Time = 240 – 360 min
• TiO2 = 1 – 5 g/L
• pH: 7.1 – 9.2
• Starting COD 1100 mg/L
Titanium Dioxide
Absorption Spectrum
Medium Pressure Mercury-vapor Spectrum
4
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Preliminary Costs• For Monarch Hill, current leachate management costs
(without the cost of sewer disposal)• $3.65 – 8.33 per 1000 gallons
• Based on lab scale treatment of simulated leachate for 20 hr with 13.3 g/L TiO2 with 450 W lamps
Costs 42 MG/year 96 MG/year
TiO2 chemical costs (one time only) $289,630 $662,010
2 x 0.2 MG tanks $90,000
2 x 0.3 MG tanks $140,000
UV lamps/ballast/power supply $40,000 $70,000
Pumps/blowers/plumbing/etc. $21,000 $36,000
Total capital cost $440,630 $908,012
Annualized (6%, 20 years) $38,423 $79,179
O&M costs (est. 10% of capital) $44,063 $90,801
Total annual costs $82,486 $169,980
Cost per 1000 gallons $1.96 $1.77
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Falling Film Reactor
• UV = 150 W lamp
• Vol = 10 L
• Time = 24 hr
• TiO2 = 25 g/L
• pH: 7.1 – 9.2
• Starting COD 6250 mg/L
Titanium Dioxide
Absorption Spectrum
Medium Pressure Mercury-vapor Spectrum
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
• CODo = 6250 mg/L • Ammoniao = 1710 mg/L as NH3-N
• Coloro = 1125 Platinum Cobalt Units (PCU)
COD took the longest to degrade in 24 hr
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Preliminary Costs• For Monarch Hill, current leachate management costs
(without the cost of sewer disposal)• $3.65 – 8.33 per 1000 gallons
• Based on pilot scale treatment of real leachate for 200 hr with 4 g/L TiO2 with 120 W lamps
Costs 42 MG/year 96 MG/year
TiO2 chemical costs (one time only) $871,068 $1,991,014
2 x 1.0 MG tanks $1,736,020
2 x 2.5 MG tanks $3,088,180
UV lamps/ballast/power supply $250,000 $500,000
Pumps/blowers/plumbing/etc. $89,000 $136,000
Total capital cost $2,946,088 $5,715,194
Annualized (6%, 20 years) $256,899 $498,365
O&M costs (est. 10% of capital) $294,609 $571,519
Total annual costs $551,508 $1,069,884
Cost per 1000 gallons $13.13 $11.14
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Summary of Past Reseach• Excellent removal of multiple contaminants in a single process
(essentially first order kinetics)• COD (bench scale 60% removal vs. pilot scale 30% removal)
• Ammonia (bench scale 85% removal vs. pilot scale 82% removal)
• Color (bench scale 65% removal vs. pilot scale 37% removal)
• TiO2 doses were tested from 4 – 40 g/L (0.64 – 5.73 TiO2/COD) • Maximum pilot scale COD removal occurred at 25 g/L (4.7 TiO2/COD)
• Maximum batch scale COD removal was at 35 g/L (6.6 TiO2/COD)
• Reactor design• Reaction time (bench scale 4 hr vs. pilot scale 96 – 200 hr)
• UV power (bench scale 1.5 W per mL vs. pilot scale 0.02 W per mL)
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Previous Work• “Options for Managing Municipal Landfill Leachate”
• Englehardt and Meeroff (2005)• “Investigation of Energized Options for Leachate
Management Year One”• Meeroff and Tsai (2006)
• “Investigation of Energized Options for Leachate Management Year Two”• Meeroff and Tsai (2008)
• “Interactive Decision Support Tool for Leachate Management”• Meeroff and Teegavarapu (2010)
• “Energized Processes for Onsite Treatment of Leachate”• Meeroff (2011)
• “Onsite Treatment of Leachate Using Energized Processes”• Meeroff (2014)
5
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Challenges• To remove desired constitutes in a timely manor at
minimal cost.
• Reach FAC 62-777 standards for all 538 constitutes
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Acknowledgements
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
http://labees.civil.fau.edu/leachate
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
Any Volunteers?
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
292929
website: http://labees.civil.fau.edu
Presentation to Joint Advisory GroupWest Palm Beach, FL, May 27, 2014
What is Landfill Leachate?
Landfill Leachate contains: • COD• BOD• Possible heavy metals :
• Arsenic• Lead• Iron • Copper
• Ammonia• Color• Chlorides • Pathogens