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Combined Perchlorate and RDX Treatment in Biological Fluid Bed Reactors

PRESENTATION AT THE

NDIA 30TH ENVIRONMENTAL AND ENERGY SYMPOSIUM

APRIL 7, 2004

Presented byWilliam J. Guarini

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Acknowledgements

AerojetU.S. Army

U.S. Army Corps of EngineersU.S. NavyUS FilterSERDPESTCPAMEC

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Presentation Overview

•Biodegradation of Perchlorate/RDX/MNX •Fluidized Bed Reactor•Case Histories – Full Scale FBR- Aerojet- Longhorn

•MMR Demo – Perchlorate/RDX/MNX•Summary

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Perchlorate Biodegradation

Cl- + H2O

Biomass + CO2 Substrate

ClO4-

ClO3-ClO2

-

* Highly Favorable Reaction (-801 kJ/mol acetate)

* Several Different Genera Isolated (Wolinella, Ideonella, Dechlorospirillum, Dechlorisoma)

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Chemical Structures

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)

C

NC

N

CN

N

N N

O O

OO

O O

2,4,6-Trinitrotoluene (TNT)

CH3

NN

N

O

O

O

O

O O

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)

N

NN

N

N

N

N

N

OO

O

O

OO

O

O

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Generalized Biodegradadtion

In most cases, transformation and/or biodegradation appears to be a gratuitous activity, often times “cometabolic” in nature.

Ability to transform explosives seems to be widespread, and has been observed in:

bacteria (both Gram+ and Gram- genera)fungi (mostly white rot species)Plants

Most commonly observed mechanism is sequential reduction of the NO2- groups, followed by eventual ring cleavage.

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Generalized Biodegradation Pathways

RDX

Hexahydro-1-nitroso-3,5-dinitro-

1,3,5-triazine (MNX)

DNX TNX

FormaldehydeMethanolHydrazine

CO2

N2OO2NN N NO2

H H

N

NO2

HOH2C CH2OH

MethylenedinitramineBis(hydroxymethyl)

nitramine

C

N

CN

CN

NO2

O2N NO2

C

N

CN

CN

NO2

O2N NO

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Utilization of Electron Acceptors

O2 H2O

Groundwater+ Substrate

NO3- N2

Denitrification

ClO4- Cl-

SO4- S-

CO2 CH4 Methanogenesis

+ 800

Redox (mV)

- 250

Sulfate Reduction

Perchlorate Reduction

Aerobic Respiration

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FLUIDIZED BEDREACTOR

EFFLUENT

FEEDCONTAMINATEDGROUNDWATER

NUTRIENT(S)

ELECTRON DONOR

INFLUENT

RECYCLE

Distribution Headers

Biomass Control

Fluidized Bed Reactor Flow Schematic

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Fluidization of Media

FBR

Post Start-up

25-30%

FBR

Set Specific Density of Sand

Particles

As the Biomass Grows, the

Specific Density Decreases as

Combined Volume of the GAC and

Biomass Increases

Microbes

40-60%

Start-up

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FBR Advantages

• High biomass concentration means long SRT and short HRT

• High volumetric efficiency translates to compact system;

• Simplicity of operation minimizes need for operator attention

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Key Mechanical Components

• Device and method used to distribute influent flow to the reactor

• Device and method used to control the expansion of the fluidized bed due to biofilm growth

• Method to control electron donor dosage rate

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• FBR SYSTEM– 2 - 8 mg/L perchlorate– 6,000 GPM flow rate– Four 14-ft diameter units– Ethanol as electron donor– GAC media

Aerojet Facility - Rancho Cordova California

Full-Scale Perchlorate Treatment System

Atlas V

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Aerojet

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Aerojet FBR Performance

aInsufficient ethanol dose during system tests.

0

1

2

3

4

5

Operation Time (weeks)

Nitrate

Perchlorate

0 3 6 9 12 15 18 21 24 27 30 33

aa

Start-up data shown:<4 g/L for > 5 years

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Full-Scale FBR System #2

Longhorn Army Ammunition Plant – Karnack, Texas

• FBR System– 15 mg/L perchlorate design– 50 gallons per minute flow rate– One 5-ft diameter unit– Acetic acid as electron donor– GAC media

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18

19

Longhorn

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LHAAP FBR Performance

Longhorn Army Ammunition Depot

ENVIROGEN FBR System Performance

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

0 60 120 180 240 300 360 420 480 540 600 660

Days Since Inoculation

Perc

hlor

ate

Conc

entra

tion

(ppb

)

Series3 Series4Influent Effluent

Currently operating 3+ years.Effluent consistently <4 µg/L.

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Other FBR Sites

• McGregor NWIRP• Kerr-McGee Chemical, LLC• Jet Propulsion Lab

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MMR FBR Site Evaluation

• Can FBR systems remediate low concentrations of perchlorate?– Less than 100 g/L (ppb)

• Can FBR systems concurrently degrade explosives as well as perchlorate?– Both biological processes are anoxic reductive

processes requiring electron donors• Can a single FBR replace traditional lead-lag

arrangement of FBR and GAC?• What treatment levels are attainable?

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MMR Groundwater Contaminant Concentrations

Perchlorate 100 g/LRDX 190 g/LHMX20 g/LNitrate 8 mg/L

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FBR Treatability Study - Set-up

• Granular activated carbon (GAC)• FBR #1 fed acetate (simple organic

substrate)• FBR #2 fed molasses (complex

organic substrate)• FBR #3 was a control (no substrate or

nutrients)• Each column fed groundwater until

perchlorate effluent concentrations approached influent concentrations meaning GAC saturated with perchlorate

• Each column wrapped with cooling coil to maintain temperature at ~17C

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FBR Treatabililty Results - Perchlorate

0

50

100

150

200

250

300

350

400

04/20/02 05/04/02 05/18/02 06/01/02 06/15/02 06/29/02 07/13/02 07/27/02

Date

Perc

hlor

ate

Conc

entr

atio

n (u

g/L)

Ceimic - FBR #1

Shaw E&I - FBR #1

Ceimic - FBR #2

Shaw E&I - FBR #2

Ceimic - FBR #3

Shaw E&I - FBR #3

Phase 1 (Start-up)Phase 3

(HRT 1, 3 = 35 min)(HRT 2 = 80 min)

Phase 2 (HRT = 80 min)

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FBR Treatability Results - RDX

0

1

2

3

4

5

6

7

8

9

05/18/02 06/01/02 06/15/02 06/29/02 07/13/02 07/27/02 08/10/02

Date

RDX

Conc

entr

atio

n (u

g/L)

Phase 3 (HRT = 35 min) Phase 2 (HRT = 80 min)

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RDX Mass Balance

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RDX Intermediates and Other Explosives

Samples Collected End of Phase 2

Replicates Average Replicates Average Replicates Average Replicates Average Replicates Average Replicates AverageFBR #1 - Top 4.6 0 0 0 0 1.5Acetic Acid 3.4 4 0 -- 0 -- 0 -- 0 -- 2.8 2

2.8 0 0 0 0 0.9FBR #1 - Bottom 3.0 0 0 0 0 1.3Acetic Acid 2.5 3 0 -- 0 -- 0 -- 0 -- 1.3 1

4.1 0 0 0 0 0FBR #2 - Top 638.1 0 10.0 0 8.4 2.1Molasses 599.5 626 0 -- 9.3 10 0 -- 7.7 10 3.2 2

641.1 0 10.1 0 12.4 1.0FBR #2 - Bottom 653.6 0 9.5 0 9.8 3.8Molasses 461.1 558 0 -- 8.5 9 0 -- 7.9 9 1.3 2

558.8 0 8.5 0 8.4 1.1FBR #3 - Top 889.7 0 11.5 0 21.3 4.7Control 805.7 837 0 -- 10.6 11 0 -- 15.4 17 1.5 2

816.1 0 10.5 0 14.6 0FBR #3 - Bottom 711.0 0 8.8 0 13.2 10.8Control 746.2 718 0 -- 8.9 9 0 -- 14.8 14 1.2 4

697.3 0 8.1 0 12.8 0

Sample Location within FBR

RDX (ug/g of GAC) MNX (ug/g of GAC) DNX (ug/g of GAC) TNX (ug/g of GAC) HMX (ug/g of GAC) TNT (ug/g of GAC)

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FBR Treatability Study Conclusions

• Success with FBR utilizing acetate and electron donor substrate (FBR #1)

• At HRT of 80 minutes– Perchlorate reduced from 100 g/L to < 1.5 g/L– RDX reduced from 190 g/L to < 2 g/L

• HRT of 35 minutes– Perchlorate reduced from 100 g/L to < 1.5 g/L– RDX could be removed by secondary GAC unit

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FBR Treatability Study Conclusions

• The molasses fed FBR (FBR #2) degraded perchlorate and RDX, but to a lesser extent

• RDX that sorbed to the GAC in FBR #1 (acetate) was consistently 2 orders of magnitude lower than in FBR #2 and FBR #3 (control). This tells us that the biologically active film on the GAC in FBR #1 was effective at destroying a significant amount of sorbed RDX

• FBR can perform as a stand alone alternative to traditional lead-lag multiple step treatment trains for perchlorate and explosives