Pilot-Scale Evaluation of Bioaugmentation of Chlorinated ...seminario.ekosbrasil.org/wp-content/uploads/2016/... · Overview of presentation •Background information on biodegradation

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