Using Mycelium-Based Air Filtration to Remove Volatile Organic Compounds in Spacecraft

Exploring Fungal Networks as Sustainable Biofilters for Confined Space Environments

The Challenge of Air Quality in Spacecraft

Maintaining air quality in confined spacecraft environments presents unique challenges. Volatile organic compounds (VOCs) accumulate from:

• Off-gassing from synthetic materials
• Human metabolic processes
• Equipment operation
• Cleaning chemicals

Traditional filtration systems require significant energy input and periodic replacement, creating logistical challenges for long-duration missions.

Mycelium as a Biological Filtration Solution

Fungal mycelium networks demonstrate remarkable capabilities for VOC remediation through:

• Metabolic breakdown: Enzymatic transformation of complex compounds
• Physical adsorption: Hyphal surface area capturing particulates
• Bioaccumulation: Storage of contaminants within fungal tissue

Scientific Basis for Mycoremediation

Research indicates mycelium can degrade various VOCs commonly found in spacecraft environments:

VOC Compound	Degradation Mechanism	Fungal Species Demonstrated
Formaldehyde	Oxidation via formaldehyde dehydrogenase	Pleurotus ostreatus, Trametes versicolor
Benzene	Cytochrome P450-mediated breakdown	Phanerochaete chrysosporium
Toluene	Peroxidase enzyme systems	Bjerkandera adusta

System Design Considerations

Structural Configuration Options

Potential mycelium filter implementations for spacecraft include:

1. Modular cartridge systems: Replaceable fungal colonies in standardized housings
2. Wall-integrated panels: Living mycelium composites as structural elements
3. Airflow channel coatings: Thin fungal layers on ventilation surfaces

Environmental Parameters

Critical factors for maintaining fungal viability in space applications:

• Humidity control: 70-90% RH optimal for most species
• Temperature range: 20-30°C for mesophilic fungi
• Aeration requirements: Oxygen exchange needs versus CO₂ production
• Nutrient supply: Sustained substrate availability without excessive mass

Comparative Advantages Over Conventional Systems

Performance Metrics

Mycelium filters offer distinct benefits compared to HEPA/activated carbon systems:

• Sustainability: Self-regenerative capacity reduces consumable mass
• Multifunctionality: Simultaneous particulate and chemical filtration
• Resilience: Adaptive biological response to contaminant mixtures

Mass and Volume Efficiency

The high surface-area-to-volume ratio of mycelial networks (reaching 200-300 m²/g in some species) enables compact system designs. NASA studies suggest potential mass savings of 30-40% compared to conventional regenerative systems for equivalent air processing capacity.

Implementation Challenges and Solutions

Microgravity Adaptations

Key modifications required for spaceflight conditions:

• Fluid management: Capillary-based hydration systems
• Structural support: Polymer matrices for mycelium containment
• Contamination prevention: Spore containment protocols

Long-Term Viability Maintenance

Sustained operation requires addressing:

1. Nutrient recycling: Integration with waste processing systems
2. Colony senescence: Phased cultivation approaches
3. Performance monitoring: Biosensor integration for activity assessment

Current Research and Development Status

Terrestrial Analog Testing

The BIO-Plex (Biological Planetary Life Support Systems Test Complex) at NASA Johnson Space Center has evaluated mycelium filters in simulated mission conditions. Preliminary data shows 60-75% reduction in target VOCs over 90-day test periods.

Spaceflight Demonstration Projects

The European Space Agency's MELiSSA program has included fungal filtration components in their closed-loop life support research. Recent ISS experiments with Pleurotus species demonstrated basic viability in microgravity.

Future Development Pathways

Genetic Optimization Approaches

Potential enhancements through biotechnological methods:

• Enzyme overexpression: Boosting degradation pathway efficiency
• Stress tolerance: Radiation and desiccation resistance traits
• Sensing capabilities: Reporter gene integration for system monitoring

Hybrid System Integration

Combining biological and physical-chemical approaches may yield optimal performance:

1. Cascade filtration: Mycelium pretreatment extending adsorbent life
2. Bioelectric coupling: Microbial fuel cell integration for power recovery
3. Triboelectric enhancement: Combining fungal fibers with electrostatic effects

Regulatory and Safety Considerations

Crew Health Protocols

Essential measures for biological system implementation:

• Aerosol control: Particulate emission thresholds
• Allergen management: Hypoallergenic strain selection
• Contingency procedures: System isolation and sterilization methods

Planetary Protection Aspects

The use of living systems raises forward contamination concerns requiring:

1. Containment verification: Multiple barrier designs
2. Termination systems: Reliable deactivation methods
3. Documentation standards: Rigorous biological load accounting

Material Science Innovations Supporting Implementation

Mycelium Composite Materials

The development of structural fungal materials combines filtration with other functions:

• Self-healing properties: Autonomous damage repair through continued growth
• Tunable porosity: Controlled hyphal density for optimized airflow
• Multifunctional materials: Combining filtration with radiation shielding