Transcript Document

Rapid & Complete
In Situ Bioremediation of
Chlorinated Solvents
Using
Enhanced Anaerobic
Dechlorination (EAD)
1
Roadmap
ISD
TM
In Situ
Delivery
Systems
1) Its All About Delivery: Our ISD™
systems provide a powerful delivery
platform to support site-wide
anaerobic degradation of chlorinated
solvents
2) Full-scale Case Study: Field
applications of our ISD groundwater
recirculation approach validates this
remediation strategy
2
ISD Concept
Substrate-amended H2O
ISD System
Delivery
System
Substrate
Nutrient
Metering
Rapid
Solvent
Degradation
Ground
Surface
VADOSE
ZONE
Contact between
substrate and
chlorinated solvents
Confining Layer
SATURATED
ZONE
 Effective substrate delivery via 24/7 GW recirculation - NO SLUG INJECTIONS
 Highly soluble substrate, plus nutrients, to grow active biomass in porespace
 Max. microbial activity,
↓ ORP, methanogenic cond., ↑ dissolution, no rebound3
EAD Process
Competing electron
acceptors:
Food
Electron
donor
O2
NO3Mn4+
Fe3+
SO4
2-
NUTRIENTS:
Chlorinated hydrocarbons:
N
PCE
P
TCE
K
DCE
Trace Metals
VC
N2
Mn2+
Fe2+
H2S
Ethene / Ethane
4
ETEC’s EAD Process

Advantages of Groundwater Recirculation w/ ISD™
–
–
–
–

Programmable Automation
Direct hydraulic influence and capture
Contact – dissolved & adsorbed (source, distal plume)
Biomass generation, site-wide activity
Inexpensive Electron Donor - CarBstrate™
– Nutrient-amended Carbohydrate – low cost ($2/lb)

Installation/Interpretation Services
– Equipment installation & training
– Monthly Interpretation/Evaluation of Data

Timeframe
– ISD results in months vs. years
– Minimal O&M and cost (pulsed vs. continuous)
5
Pilot-scale Data:
Industrial Site
Eugene, Oregon
6
OR Case Study Site Plan
15 m
Groundwater
Flow Direction
MW-2
9m
Mobile ISD
System
MW-3
MW-1
LEGEND
Injection Wells
Extraction Flow Line
Extraction Wells
Monitoring Wells
Injection Flow Line
MW-4
7
TMW-3 Results
TMW-3 Chlorinated Solvent and Ethene/Ethane Concentrations
160
cis-DCE Concentrations (ppb)
1800
1600
1400
PCE
cis-DCE
140
TCE
VC
120
Ethene/Ethane
1200
1000
100
80
800
60
600
40
400
PCE, TCE, VC and Ethene/Ethane
Concentrations (ppb)
2000
20
200
27
0
24
0
21
0
18
0
15
0
12
0
90
60
30
0
0
0
DAYS

Operating Parameters
–
–
–
3 weeks
178,000 liters recirculated
180 kg of CarBstrate™

Observations
–
–
–
–
CAH concentrations increased 2-3 fold during 1st week,
no PCE at TMW-3
DCE from 360 to 2,000 ppb
Initial total CAH 3.8 μmol/L, with a high of 22.3 μmol/L
8 months, no rebound, cis-DCE and VC (6 and <1 ppb)
8
Full-scale Case Study:
Industrial Site
Eugene, Oregon
9
2006 Full-scale RA
• Solid pilot-test data showing rapid, complete
dechlorination of solvents supported fullscale in situ remedial action
• Full-scale conducted from June-Sept 2006 to
remediate source area (122 m x 91 m x 6 m)
using 31 Injection/extraction wells
• 150-lpm ISD system, touch-screen and
flexible PLC system
• 12-18 month estimated timeframe to reduce
CAHs by 90%, achieved goal in 6 months
10
Full-scale
system has 11
EWs and 20
IWs. To date,
most data has
been collected
from EW-3, 6,
7, and 10.
Samples
collected from
EW-7 shows
source zone
concentrations.
11
Over 3 months:
Recirculated
over >8.7
million liters in
3 months
Introduced
3,720 kg
substrate
1-visit/week
Minimal down
time
Minimal
Fouling
Some LNAPL
(diesel and
Bunker C)
12
13
Touch Screen
PLC:
Alarm
Conditions,
Troubleshooting
Flexible injection
times
Autodialer/Telemetry
14
2006 Results
EW-03
600
1400
PCE
1200
PCE, TCE, VC,
Ethene/ethane (ppb)
VC
ethene/ethane
400
cis-DCE
1000
800
300
600
200
400
100
200
0
0
0
20
40
60
80
100
120
140
160
DAYS
–
Cis-DCE increased significantly, then began to decline. A max concentration of 500 ppb PCE should
generate 291 ppb of cis-DCE, but we see up to 1,300 ppb.
15
cis-DCE Concentration (ppb)
TCE
500
EW-3 Molar Concentrations
20.0
18.0
Molar Concentration umol/L
16.0
14.0
12.0
PCE
TCE
cis-DCE
VC
Ethene/ethane
10.0
8.0
6.0
4.0
2.0
0.0
0
16
22
48
Time- Days
83
154
16
2006 Results
EW-6
500
3500
PCE
PCE, TCE, VC,
ethene/ethane
Concentrations (ppb)
TCE
3000
400
VC
350
ethene/ethane
2500
cis-DCE
300
2000
250
1500
200
150
1000
cis-DCE Concentration
(ppb)
450
100
500
50
0
0
0
20
40
60
80
100
120
140
160
Days
17
EW-6 Total Molar Concentrations
Total Molar Concentrations umol/L
35.0
30.0
25.0
PCE
TCE
cis-DCE
VC
Ethene/ethane
20.0
15.0
10.0
5.0
0.0
0
16
22
48
Time- Days
83
154
18
EX-7

Date
PCE
(ppb)
TCE
(ppb)
cis-DCE
(ppb)
VC
(ppb)
Ethene/ethane
(ppb)
8/22/06
Day 48
6,700
4,400
10,000
<200
50
9/26/06
Day 83
330
<100
3,500
1,100
763
12/6/06
Day 154
220
55
160
22
5.1
Observations
–
–
–
–
First sample event shows significant concentrations of PCE/TCE even after 48 days of
recirculation, with dechlorination to cis-DCE ongoing during this time.
No significant VC after 48 days, and ethene still low.
VC increased significantly, but nothing compared to the parent concentrations
Generated biomass expected to continue to stimulate dechlorination for another year
19
Chlorinated Ethanes
EW-3
Chlorinated Ethanes Mole Fractions
80
Mole Fraction (Percent)
70
60
50
40
30
20
10
0
7/5/2006 (B)
07/21/06
07/27/06
08/22/06
09/26/06
12/07/06
1,1,1-Trichloroethane
29.2
53.1
16.6
4.3
1.9
1.7
1,1-Dichloroethane
15.1
30.3
55.2
66.5
57.4
24.3
Chloroethane
55.8
16.6
28.2
29.3
40.8
73.9
Time
20
Full-scale Comments
• Approach rapidly transforms ppm levels SITE-WIDE!
• Enhanced desorption observed during recirculation
• No downgradient change in cVOC concentrations;
hydraulic capture successful!
• LNAPL did not prevent implementation
• Nutrient demand (N and P) higher than calculated
• Results very similar to pilot-test. Shut-down Sept.
2006, TOC low at all locations, now biomass acting
as substrate over the next several months/years. No
cost associated with this, except analytical/sampling
labor.
• Chlorinated Ethanes treated site-wide
• Overall Costs ~$270K, treatment area 68,000 CM:
$4/CM
21
CONCLUSIONS
• Soluble substrate + nutrients + recirculation + infrastructure = rapid
dechlorination
• Works w/ varying conditions (low/high flow, ppm or ppb, co-mingled
or not)
• Control subsurface conditions/microbial needs (NOT ABOUT THE
BUGS)
• Total Mass of Solvents is Higher, Desorption is crucial to achieve low
level remedial goals
• Nutrient Concerns (rapid uptake), higher than theoretical
• Limited Biofouling (pressure inj., pulsed delivery)
• Site Characterization & Infrastructure are CRITICAL!
• Nitrate/phosphate, some metals (hex chrome), perchlorate, 1,4dioxane, treatment possible with this approach
• Cost Range is cheaper than excavation/disposal ($2-8/CM)
• Time comparison is like no other biological approach, kinetics much
higher