Post on 24-May-2020
In Situ Bioreactors for In-Well Groundwater Remediation
Eric J. Raes, P.E., LSRPKerry Sublette
The Bio-Sep In Situ Bioreactor (ISBR)
• Enhancement of in situ bioremediation in groundwater with compact bioreactor installed in-well
• Overcomes common limitations of bioremediation of groundwater
– Low contaminant concentrations
• A threshold concentration of substrate is required for growth
– Substrate inhibition
• At high concentrations some biodegradable contaminants can be toxic to the organisms that have the ability to degrade them
In the beginning…..
The Bio-Trap® Sampler:
• Rapidly colonized by indigenous bacteria forming active biofilms
• Thousands used worldwide for over a decade for forensic analysis of groundwater microbiology
Cell division inside of Bio-Sep® Bead within a Bio-Trap Sampler
X-Section of Bio-Sep® Bead Interior of Bio-Sep® Bead
Bio-Trap® Sampler with Bio-Sep® Beads
Nomexand PAC
• Adsorptive surface• High surface area
The Bio-Sep ISBR
• Bio-Sep beads provide an incredible surface area for microbial growth
• Gas sparging (air or N2) creates an airlift for circulation of groundwater through the bioreactor.
• Contaminated groundwater is treated as it moves through the column of Bio-Sep beads
• Nutrient addition (N, P, electron donors, electron acceptors) support growth of desired indigenous microbes
• Water exiting the reactor carries contaminant-degrading microbes into the aquifer
1 ¼” PVCFits in 2” well
Air or N2 and nutrient delivery
Topside control
• Nutrient reservoirs and pumps
• Air pump• Air flow control
• Petroleum hydrocarbons• Aerobic
• Anaerobic
• Chlorinated hydrocarbons• Anaerobic
• Fuel oxygenates (MTBE, TBA)
• Emerging contaminants (1,4-Dioxane)
Bio-Sep ISBR Applications
Case Study – Aerobic ISBR – Low Concentrations of Hydrocarbons
• Fuel oil release impacting soil and groundwater beneath a private residence
• The bioreactor well & four monitoring wells were installed in the basement
• Wells spaced 1 ft. apart
ISBR Timeline
• Days -67 through -34: Air sparging only (no Bio-Sep)
• Days -34 through 0: Air sparging and nutrient delivery (no Bio-Sep)
• Day 0 onward: Complete bioreactor system operational (Bio-Sep beads added)
• Bio-traps® (Microbial Insights, Inc) used through out testing to monitor microbiology of bioreactor well and monitoring wells
qPCR Analysis of BR1 Bio-traps During ISBR Testing
Didn’t see much difference in hydrocarbon catabolic genes with DNA. This is common observation since hydrocarbon degraders are ubiquitous in the environment.
RT-qPCR Analysis of BR1 Bio-traps During ISBR Testing
No expression of hydrocarbon catabolic genes until the complete bioreactor system was in service.
0
10
20
30
40
50
60
70
80
90
-200 -100 0 100 200 300
Co
nc
en
tra
tio
n (µ
g/L
)
Day
BTEX Concentrations Over Time
Benzene
Ethylbenzene
Toluene
Xylene (total)
Anaerobic ISBRs, the same but different
N2 sparger
1 ¼” PVCFits in 2” well
Case Study – Anaerobic ISBR
• Chlorinated solvent impacted site
• Fractured bedrock aquifer
• Deep groundwater impacts (140’ bgs)
• Unfavorable geochemistry
• Low but measureable DO
• DO increase with rain event
Case Study – Anaerobic Bioreactor
• ISBR installed at a depth of 30’ BGS
• “Liquid carbon” electron donor
• Groundwater monitoring
• Contaminant concentrations
• Geochemistry
• qPCR for Dehalococcoides and functional genes for reductive dechlorination (bio-traps and groundwater)
Groundwater Contaminants & Microbiology
0
200
400
600
800
1000
1200
1400
1.0E+00
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E+06
0 1 2 3 4 5
Co
nce
ntr
atio
n (m
g/L
)
Cel
ls/m
L
DHC BVC VCR DHBt PCE TCE cDCE Ethene VC
Quarters
Dehalococcoides (DHC)Concentration with Depth
(Monitored by Bio-traps)
1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04
-140
-105
-85
-60
Cells or gene copies/bead
Ele
vati
on
(ft
)
ND
1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04 1.00E+05
-140
-105
-85
-60
Cells or gene copies/bead
Ele
vati
on
(ft
)
Pre-ISBR Post-ISBR
1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04
-140
-105
-85
-60
Cells or gene copies/bead
Ele
vati
on
(ft
)
Vinyl Chloride RDases with Depth
Post-ISBR
1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04
-140
-105
-85
-60
Cells or gene copies/bead
Ele
vati
on
(ft
)
ND
ND
ND
ND
ND
ND
ND
Pre-ISBR
ISBRs Will Transfer Degraders from One Well to Another
In situtreatment and colonization of ISBR
Inoculation and/or kick start degradation
Transfer of DHC in a TCE Plume
0
500
1000
1500
2000
2500
3000
-900
-870
-840
-810
-720
-630
-540
-450
-360
-270
-180
-90 0
30
60
90
120
150
Time (days)
[VO
C],
ug
/L TCE
cis-DCE
VC
Ethene
nZVI/
Emulsified oil
Colonized ISBR installed
When to consider an ISBR
• Inhibitory contaminant concentrations
• Dilute plumes (persistent low levels of contaminants)
• Following ISCO
• Difficult situations
• Limited physical access
• Where one-time amendment injection is not feasible
• Where bioremediation has failed previously
ISBR Limitations
• Aerobic operation limited to low concentrations of reduced iron (fouling)
• Radius of influence decreases with increasing hydraulic conductivity of aquifer matrix
• Works best with contaminants adsorbed by activated carbon
ISBR O&M and Costs
• O&M
• System checks every 2-4 wks
• Power
• Nutrients
• Water level (ISBR must be totally submerged to function)
• Costs
• Life of project rental
• $10,000 for one unit (ISBR and controller)
• $15,000 for two units
• Decreasing per unit costs with addition of more units at a given site
Eric RaesBioEnhance, LLCeric@bio-enhance.com(973)219-6185
Kerry SubletteBioEnhance, LLCksublette@microbe.com(918)691-0639
Chemical Oxidation & Aerobic ISBR
Case study: Fuel oil release
Naphthalene degraders Pre- and Post-ISCO
0
2000
4000
6000
8000
10000
1.0E+00
1.0E+02
1.0E+04
1.0E+06
1.0E+08
1.0E+10
Pre-ISCO ISCO Post-ISCOBiostimulation
Post-ISCOMNA
d1
3C
DIC
(‰
)
Ge
ne
Co
pie
s/b
ead
NAH Population (DNA) NAH Expression (RNA) DIC Del (‰)
Present but not active
Present & active Aerobic naphthalene
degraders are present but not
active
0
2000
4000
6000
8000
10000
1.0E+00
1.0E+02
1.0E+04
1.0E+06
1.0E+08
d1
3C
DIC
(‰
)
Ge
ne
Co
pie
s/b
ead
NAH Population (DNA) NAH Expression (RNA) DIC Del (‰)
ND NA
Naphthalene degraders ISBR – Post-ISCO
No ISBRPresent but not active
ISBR DeactivatedNo activity or mineralization
ISBR InstalledActive &
mineralizing
ISBR Re-installedActive &
mineralizing