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A biofiltration system was tested to remove low levels of acetone from an indoor space. The biofilters were subjected to a range of air fluxes and concentrations of acetone between 100 and 500 ppbv. Passing low levels of acetone through a canopy of green plants did not improve the quality of the air. However, acetone removal by the biofilters with living moss as a principle substrate, reached a maximum of between 1 and 1.6 μmol s-1 m-2 with a loading rate of approximately 2 μmol s-1 m-2. Generally the removal efficiency decreased with increased loading rates over a range of air fluxes (0.05 to 0.2 m s-1) but appear to increase with loading within the slower fluxes. Neither ZERO nor FIRST order kinetics could adequately describe removal. Instead an empirical model that described the natural logarithm of the unloading rate as a function of the natural logarithm of the loading rate and the natural logarithm of the inverse of the air flux fit the data well.

A biofiltration system is currently being tested as an alternative to maintain indoor air quality within an office building setting. The system is based on a complex plant community with both terrestrial and aquatic components. CO2 dynamics within the space offer a means of evaluating its potential efficacy. A model is presented based upon both exponential and linear processes, which accurately describes diurnal changes in CO2 levels and the removal of introduced CO2. The exponential dynamics indicate increasing rates of sequestering with increasing exposure levels. The CO2 is eventually fixed through the process of photosynthesis, but is most likely initially sequestered in the aquatic component of the system. The removal of the contaminant from the atmosphere and into the aquatic phase where it is subsequently metabolized by the biomass suggest the system may be an effective filter for removing contaminants from indoor settings.