The interest in Indoor Air Quality (IAQ) has increased this past decade due to better knowledge of this kind of pollution. Recent studies have pointed out the Indoor Air Pollution (IAP) impact on health and associated costs. IAQ improvement can be achieved by removal of pollutant with adapted process. Numerous processes, as sorption or UV photocatalysis, have been studied for IAP treatment. However, IAP specificities, including high number of compounds with different physico-chemical properties at low concentrations, still limit process efficiencies. Competition between pollutants and process selectivity are also common limitations. Biofiltration is commonly used to treat effluents containing numerous compounds at low concentration in composting units or wastewater treatment plants. Moreover, since it uses waste as a filtration medium and avoids the addition of chemical products, biofiltration is a sustainable technology. In this study, biofilter performances for IAP treatment are evaluated. The biofilter is packed with compost, a natural medium which has a large range of microorganisms, good physical properties (water retention, pH) and contains nutrients. The model effluent contains 8 compounds (aldehyde, aromatic, chlorinated, inorganic...), at low concentration (sub-ppmv), chosen for their ubiquity in indoor air, their heterogeneous physical and chemical properties (solubility, vapor pressure, biodegradability) and their potential health risk due to chronic exposures. Biofilter performances were evaluated during 75 days in steady state. Three compounds, undecane, limonene and butyl acetate, could not be quantified during the study, removal efficiencies are close to 100 %. Butanol, formaldehyde and toluene were removed with efficiencies close to 100 % during the first 40 days. After this time, efficiency variations were observed and the removal efficiencies decreased to 55.5, 77.8 and 13.9 % for butanol, formaldehyde and toluene, respectively. The decrease of bed moisture content seems to be the main explanation for these phenomena. Removal efficiencies of 86.3 99.6 % were achieved for nitrogen dioxide. Only trichloroethylene, known as a not easily biodegradable compound, was not removed by the biofilter: only sorption and desorption phenomena were observed during this time for this compound. In these starvation conditions, biomass cannot grow and only a fraction of the biomass can be maintained in the biofilter. However, this non-negligible biomass fraction can have a biological activity and removes the different compounds contained in the model effluent.
