Pilot-Scale Evaluation of Bioaugmentation of Chlorinated...
Transcript of Pilot-Scale Evaluation of Bioaugmentation of Chlorinated...
Pilot-Scale Evaluation of Bioaugmentation
of Chlorinated Solvents in Groundwater
Laurie LaPat-Polasko, PhD, QEP
ENVIRON International Corporation
Overview of presentation
• Background information on biodegradation
of chlorinated solvents and the site
• Bench-Scale Study: Evaluate Various In Situ
Bioremediation Options for chlorinated
solvents in groundwater
• Pilot-Scale Study: Evaluate most effective
option from Bench-Scale Study
–Selected in situ biostimulation and
bioaugmentation for implementation
Background Site Information
• 1.1 acre site in Southern California
• Site is currently used as a solvent recycling
facility
• Also used for storage and transfer of
hazardous wastes
• Important not to disrupt current operations
–Numerous trucks in and out of the facility on
daily basis
Background Site Information
• High levels (>10 mg/L) of chlorinated
solvents in groundwater including:
– Tetrachloroethene (PCE) up to 73 mg/L
– Trichloroethene (TCE) up to 118 mg/L
–Cis-1,2-Dichloroethene (cis-DCE) up to 47.8
mg/L
–Vinyl chloride (VC)
– 1,1,1-Trichloroethane
• Groundwater velocity is very slow due to
flat horizontal hydraulic gradient in
vicinity of site
Background Site Hydrogeology
• Zones 1 and 2– from ground surface to about 75
ft. below ground surface (bgs); fine-grained
sediments of silty sands, silts, clayey silts, clayey
sands, and clays.
• Zone 3 (Semiperched Aquifer) – from about 75
to105 ft. bgs; contains courser-grained sediments
of silty sands, sands, and gravelly sands. Water
table occurs at about 92 ft bgs.
• Zone 4 (Aquitard) – from about 105 to150 ft bgs
with a local zone of low permeability clay and silt
from depths of approximately 105 to 115 ft bgs.
Background Groundwater Data
Well Number MW-2 MW-3 MW-6
Sampling
Parameter
Concentrations: milligrams per
liter
Nitrate 2.38 13.2 51.4
Dissolved Iron <0.10 <0.10 <0.10
Manganese 0.924 0.416 0.021
Sulfate 33.9 27.8 37.6
Total Kjeldahl
Nitrogen
0.364 0.543 0.253
Total Phosphorus <0.050 0.126 0.057
Dissolved Organic
Carbon
0.78 1.5 0.41
Reductive Dechlorination Pathway
Desulfuromonas, Dehalobacter
Desulfitobacterium, Sulfurospirillum,
Geobacter
Courtesy of: Dr. Krajmalnik-Brown
Cl H
TCEPCE cis-DCE VC Ethene
Dehalococcoides ethenogenes strain 195
Dehalococcoides sp. strain BAV1
Dehalococcoides sp. strain GT
Bench-Scale Study Objectives
• Establish potential for in situ biodegradation
of various chlorinated volatile organic
compounds (cVOCs) in groundwater
• Evaluate various types of electron donors:
quick release (e.g. lactate) and slow-release
(e.g. EOS)
• Evaluate potential need for bioaugmentation
• Evaluate biodegradation rates
• Develop design criteria for pilot-scale
system, if appropriate
Bench-Scale Testing Approach
• Set up series of
microcosm bottles
• Sterile & MNA Controls
• Biostimulation options
• Biostimulation &
Bioaugmentation
options
• Monitored periodically
for cVOCs, nutrients,
VFA, methane, ethene,
& ethane
Sodium Lactate: Biostimulation vs.
Bioaugmentation
EOS: Biostimulation vs. Bioaugmentation
EHC: Biostimulation vs Bioaugmentation
Pilot Study Objectives
• Evaluate radius of influence of injected
substrates: bromide and microbial
consortium
• Evaluate effect of carbon substrates on
biodegradation rate of cVOCs
• Evaluate effect of bioaugmentation on
biodegradation rate of cVOCs
• Develop design criteria for full-scale
system
Pilot Study Program
• Based on result of bench-scale testing,
identified appropriate amendments.
• Groundwater Recirculation System
–Groundwater extracted and amended with
carbon source or microbes and reinjected.
– Biostimulation with QRCS
• Injection of a Wilclear Plus Sodium Lactate
and tracer compound (sodium bromide)
– Bioaugmentation with KB-1 Consortium
• Injection of KB-1 microbial consortium
– Biostimulation with SRCS
• Injection of a EOS®
Groundwater Recirculation System
Pilot Scale Injection Set-Up
• Injection set-up
included site
groundwater amended
with:
–sodium bromide
– lactate
–KB-1 microbial
consortium
–emulsified oil
substrate
–pH adjustment
compounds.
Baseline Water Quality Data
GROUNDWATER FIELD PARAMETER
MEASUREMENTS
Well
No.
Sample
Date pH
Temp
(°C)
DO
(mg/L)
ORP
(mV)
MW-1 08/03/00 5.62 22.8 -- --
MW-2 04/04/13 6.79 21.7 0.91 -103
MW-3 04/04/13 6.83 20.2 0.69 -146
MW-11 04/04/13 6.76 19.5 0.62 -32
Bio-Trap Unit Including Bio-Sep Beads
Baseline Microbial Population Results
Analyte
Unit
MW-3
GCW-1
OW-1
Dehalococcoides
(DHC)
cells/
bead
<2.50E
+01
<2.50
E+01
1.87
E+01
Total Biomass cells/
bead
1.64
E+05
9.35
E+04
1.12
E+05
Anaerobic Metal
Reducers
% PLFA
0.8
0
1.4
Proteobacteria % PLFA 68.41 67.3 70.7
Monitoring Program
• Monitored for field parameters: pH, DO, ORP,
conductivity, temperature
• Monitored following analytical parameters:
–Chlorinated (cVOCs)
– Total Organic Carbon
– Terminal Electron Acceptors (O2, nitrate, Fe,
Mn, sulfate)
–Volatile Fatty Acids (acetate, propionate, etc.)
–Major Nutrients N and P
–Dissolved Gasses: methane, ethane, ethene,
–Microbial Biomass: key microbes:
Dehalococcoides, PLFA
Methane, Ethane and Ethene Results
Well
Number
Sample
Date
Methane
Ethane
Ethene
Concentrations: microgram per
liter
MW-3
2013 0.961 0.309 <1.00
2014 0.852 0.246 <1.00
GCW-1
2013 1.16 0.649 0.366
2014 1440 0.068 78
OW-1
2013 0.556 0.16 0.048
2014 387 0.14 42
Observation Well- 1 (OW-1) Chlorinated
VOC Results
Chlorinated VOCs vs Time in GCW-1
MW-3 Non-impacted well
Conclusions
• Bench-scale testing provide key information for
pilot-scale design
• Two-phased approach: quick-release carbon
substrate followed by slow-release carbon
substrate
• Initial biostimulation provided rapid increase in
TOC and Volatile Fatty Acids
• Increase in TOC lead to increase in microbial
population and reduction in cVOCs
• Bioaugmentation lead to increase in VC and 3-4
order of magnitude increase in ethene
production