The Naturaire® System represents as complex ecosystem which infers operational stability and, in contrast to conventional biofiltration, ecosystem diversity which may promote the degradation of a broader range of contaminants. But the question remains, "why include Green Plants?" Well, there are many reasons. For example:

• Plant material makes an excellent 'packing material' for the biofilter based upon its physical characteristics. The high surface area-to-volume ratios of the plants provide excellent bed characteristics. The high porosity allows for even air flow while high surface area provides for good biofilm contact even with very shallow bed depths (ie < 0.05m).
  
  
• Many alternative conventional, organically-based packings have a limited life span. While supporting contaminant degradation, these other organic materials such as bark/wood mixtures are being degraded themselves. Living plants are a bioregenerative packing medium, replacing constantly replacing itself to maintain a good supply of plant material present. In addition, plant exudates provide alternative carbon sources to maintain biological activity.
  
  
• Plants can alter the composition of its associated microbial population. Careful selection of plants species promotes desirable VOC-degraders. However, care must be taken during the selection process since many plants also produce antibiotic compounds and may actually inhibit biological activity.
  
  
• Plants can quickly adapt to growth on vertical surfaces.
  
  
• The rhizosphere surrounding the roots of the plants in the system contains higher microbial populations than bare soil. Hence, plants are able to enhance degrader populations.
  
  
• Plants can break down some indoor pollutants directly. Plants grown in cell culture could metabolize formaldehyde into cellular components. However, houseplants have limited impact on indoor VOCs due to boundary layer resistance. The incorporation of a biofilter into the air handling system will greatly reduce this resistance and maximize any ability of the plant to break pollutants.
  
  
• Plants may also accumulate airborne contaminants. Organics can either adsorb to plant cuticle or be accumulated internally. Hence, plants may act as a contaminant sink or they may impart some buffering capacity to the biofilter for fluctuating pollutant concentrations.
  
  
• Green plants are a sink for CO₂ which is considered an indoor pollutant. Through photosynthesis, they combine carbon dioxide and water into biomass and evolve oxygen.
  
  
• Green plants have been included for aesthetic purposes. Maintaining an indoor 'green' area may increase employee productivity and lower absenteeism.
  
  
• Plants reduce the amount of dust in an enclosed space.

To learn more about how Naturaire® Systems remove VOCs, click here.