Use of biotechnology coupled with bake-out exhaust to remove indoor VOCs

A new technical development of biological treatment coupled with bake-out exhaust was applied to deal with indoor volatile organic compounds (VOCs). Bake-out exhaust method was used to significantly accelerate the release of VOCs from building materials. Biotechnology was used in order to avoid the baked indoor air with high level of VOCs being exhausted outdoors directly, which may cause pollution problems in dense building areas without sufficient urban ventilation. Experiments show that baking 10 h at 40°C, the emission rate and concentration of VOCs increased significantly compared with less baking time and temperature. The gas was moved into the biotrickling filter after baking. Under the conditions of gaseous flow rate of 0.6 m3•h-1, surface liquid velocity of 3.14 m•h-1, pH of 6-7 and inlet temperature of 40°C, VOCs were biotreated. For formaldehyde, benzene, toluene and xylene in the air stream with the concentration of 10.6 mg•m-3, 46.0 mg•m-3, 39.8 mg•m-3 and 42.1 mg•m-3, the removal efficiencies of biotrickling filter were about 100%, 48.9%, 66.2% and 66.3%, respectively. Four high-efficient bacteria were optimized and screened out from the biotrickling filter. After bioaugmentation, benzene, toluene and xylene removal efficiencies increased to 14.7%, 6.2% and 11.7%, respectively.