Biofiltration for Trace Contaminant Control in ALS Systems

1
Biofiltration for Trace Contaminant Control in
ALS Systems

• John A. Hogan, Feng Qiao and Peter F. Strom
• Department of Environmental Sciences
• Rutgers, The State University of New Jersey
• hogan_at_aesop.rutgers.edu
• Habitation 2004Conference on Space Habitation
  Research and Technology Development
• 01/07/2004

Picture(s) courtesy of NASA
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Background

• Air Revitalization System (ARS) Functions -
• Monitoring/control of total atmospheric pressure
  and partial pressures of O2, N2 and CO2
• Temperature and humidity control
• Circulation and exchange between modules
• Airborne particulate matter and microbe control
• Detect, respond to, and recover from rapid
  decompression, fire and hazardous atmospheres
• Trace gaseous and vapor contaminant control

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ISS Trace Contaminant Control System
Adapted From Perry NASA/TP-1998-207978
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Rationale

• Equivalent System Mass (ESM)
• ESM to be reduced by a factor of 3 by 2010
• Must decrease consumables (activated charcoal,
  LiOH, catalysts, filters) and power
• Regenerative systems are needed - long duration
  missions
• Future Air Contaminant Streams
• New compounds will be encountered
• Highly increased loading rates
• SMACs may be altered (e.g., ethylene)

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Potential Air Contaminant StreamsEvolved Mars
Base Using ALS Technologies (without ISRU)
From Advanced Life Support Reference Missions
Document CTSD-ADV-383
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Potential Integration Schemes

• Direct Coupling to Concentrated Streams

TCCS/THC Systems
Biofilter

• Low Flows
• Low Reactor Volume
• High Humidity
• High C
• High NH3 (?)

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Biofiltration Overview
Exit Air 100 Humidity
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Internal Biofilter Mechanisms
Solid Phase
Air, CO2, H2O
Air Phase
O2
CO2
Liquid/Biofilm Phase
Contaminant Conc.
Laminar Flow
Turbulent Flow
Contaminated Air
Liq./Biofilm Phase
Air Phase
Derived from Devinny, et. al. (1999)
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Experimental Design
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Air Flowmeters
Mass Flow Controllers w/ Safety Valves
Condenser
Chambers
Humidifier
Incubator
Source Gases
Exit Acid Traps
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Biofilter Chamber
Incubator
28 oC
Sampling Port
7 cm
Layer 4
Perlite 10.5 L
Layer 3
10 cm
33 cm
Mineral Salt Media Solution
Layer 2
10 cm
Layer 1
6 cm
100 Humidified Air Methane and/or Ethanol,
(Ammonia)
EBRT 2 min.
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Methane Biofilter Reactor Parameters
Nitrogen is supplied by the mineral salts medium
added to the biofilter matrix during
preparation. Methane loading was decreased to
5.62 g carbon/m3-hour on the 19th day of
operation in both CH4-only and CH4 NH3 reactors
(CN 1001). Delivery rate for ammonia is
in mg/m3-h.
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Methane Biofilter Reactor Results
Methane-only Biofilter
Methane Ammonia Biofilter
CH4-NH3 methane removal vs. reactor length
1.2
y 1.2541x - 0.0997
1
R2 0.92
R2 0.90
0.8
Removal port/total
total removal vs distance
0.6
0.4
0.2
0
0
0.2
0.4
0.6
0.8
1
Port distance/total distance
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Reactor Profile (45th Day of Operation)
Methane NH3 Reactor
Methane - only Reactor
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11
pH 9.2 H2O56 Biomass 25.9
pH 9.4 H2O56 Biomass 23.9
14
4
4
9.8
7.2
pH 9.2 H2O57 Biomass 28.4
pH 9.3 H2O58 Biomass 23.5
0.7
3
3
4.6
9.8
pH 9.3 H2O55 Biomass 26.1
pH 9.4 H2O57 Biomass 21.0
0
2
2
5.7
pH 7.9 H2O44 Biomass 22.3
pH 9.3 H2O56 Biomass 26.8
9.0
1
4.1
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Initial Conditions
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Non-N Methane Biofilter
Organic-N Methane Biofilter
CH4 Removal Efficiency
CH4 Removal Efficiency
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Ethanol-only
Ethanol Ammonia
N Source
CN ratio
NH3 Conc.
NH3(gas)
C2H6O Conc.
Carbon Loading
Chamber
NO3-
---
---
---
250 ppm
9.8
C2H5OH-only
NO3-
1801
2.5 ppm
54.5
250 ppm
9.8
C2H5OHNH3
Note The loading rate of ethanol is given in g
carbon/m3-hour.
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Perlite Profile (53rd Day of Operation)
EthanolNH3 Biofilter
Ethanol-only Biofilter
pH 6.8 H2O67 Biomass 15.0
4
pH 7.3 H2O67 Biomass 18.5
3
pH 5.0 H2O67 Biomass 53.7
2
pH 6.2 H2O47 Biomass 76.5
1
Initial
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Summary

• Methane removal is mass transfer limited - may
  drive reactor volume
• Ammonia likely inhibited methane degradation in
  the CH4 NH3 reactor (CN ratio of 1001).
• Ethanol readily removed - Organic acid
  production due to thick biofilm (O2 limitation)
• Nitrate assimilation increased pH of the perlite
  biofilter matrix
• Organic nitrogen (peptone) is preferable nitrogen
  source
• The competing forces of nitrification (acidic)
  and ammonium accumulation (basic) moderated
  matrix pH changes.
• The C/NH3 loading rates, CN ratio, species used
  for matrix nitrogen supply, and carbon compound
  characteristics will drive biological air
  treatment design and operation.
• Multiple-stage reactors and mid-course matrix
  management are likely needed to improve control
  of the microbial environment.

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Thank you!

• Questions or Comments?

Acknowledgements NASA NJ-NSCORT NJAES Dr. Harry
Janes