Improvement of air biofiltration by injecting contaminated air into the soil layer of a mini-biowall

Biofiltration of contaminated air using plants have received a lot of attention recently as an environment-friendly and cost-effective way to purify indoor air. This study aimed to increase the efficiency of air phytoremediation via plants using an active mini-biowall and by injecting contaminated air into the soil of the mini-biowall. A mini-biowall with three layers (plant, soil, and air injection layer) was developed. Epipremnun aureum was grown on the biowall and the capacity for toluene and xylene removal for 10 h was studied in 1 m3 chamber. Toluene removal was 105% more efficient using an active mini-biowall compared to a passive one. Similar trends for ethylbenzene and xylene were also observed, with 80% and 102% higher removal with active biowall, respectively. Further improvement of the active mini-biowall system was done by introducing airballs (4- and 8-airballs) to inject air through the soil media. The 4-airball system have higher toluene removal efficiency than the 8-airball biowall system from the 1st hour to before the 8th hour of exposure. At 8 h, the two systems have the same toluene removal. Removal of toluene and xylene from indoor air significantly increased using an active mini-biowall and improvement of the system by injecting air into the soil media using airballs enhanced rate of removal especially with the 4-airball system. The mini-biowall system is a potential indoor air-purifier, thus further improvements of the system should be done to make it more acceptable to home owners or other clienteles.