Biofiltration based on bioactive coatings for the abatement of indoor air VOCs

Biotechnologies are a feasible alternative for indoor air pollutant abatement. Among biotechnologies, bioactive coatings consist of microorganisms embedded in polymeric matrices, allowing a direct contact between microorganisms and gas pollutants, thus enhancing their abatement. Three bioreactors (BR1, BR2 and BR3) were inoculated with a VOC-degrading enriched culture, a latex bioactive coating with the VOC-degrading enriched culture, and a latex bioactive coating with fresh activated sludge. The influence of empty bed residence time (EBRT) and inlet concentrations on the removal of toluene, alpha-pinene and n-hexane was assessed. BR1 and BR2 achieved steady-state toluene and pinene removals >90% down to 30 s. BR3 lower removals could be attributed to the lack of acclimation of activated sludge. When inlet concentrations were progressively reduced to <2 mg m-3 at 15 s of EBRT, toluene removals increased to >80% in BR1 and BR2, but only to 64.2% in BR3. Pinene removals reached 90.9% in BR1, and >70% in BR2 and BR3. The bacterial population was dominated by Rhodococcus, Mycobacterium, Devosia and Rhodobacteraceae members in BR1 and BR2. No significant and robust hexane removal was observed regardless of the inoculum or operational conditions, probably due to mass transfer limitations, which entailed a low dominance of organisms with this metabolic capability.

Automated summary

Biotechnologies, particularly bioactive coatings, are effective in reducing indoor air pollutants by allowing direct contact between microorganisms and gas pollutants. The removal efficiency of toluene, alpha-pinene, and n-hexane was assessed in three bioreactors with different inoculum and operational conditions. Toluene and alpha-pinene removals >90% were achieved in two bioreactors, while hexane showed low removal efficiency due to mass transfer limitations.