Enhanced toluene biodegradation by novel bioactive coatings applied in continuous flow bioreactors

Volatile organic compounds (VOCs) are common air pollutants from industrial sources. The hydrophobic nature of some of these VOCs limits their removal by conventional biotechnologies. This study evaluates the application of bioactive coatings, a novel biotechnology based on nanoporous polymer matrices embedding active microorganisms, to improve the bioavailability of hydrophobic VOCs in gas-phase bioreactors. Bioactive coatings supported on jute rope and dishcloth strips were tested in a bioreactor for the continuous treatment of toluene and then compared with a conventional biofilm-based system. Jute rope failed to ensure an effective nutrient transport due to the lack of capillarity, while dishcloth strips successfully supported the bioactive coating, significantly enhancing bioreactor's performance. The bioactive coating bioreactor packed with dishcloth strips outperformed the conventional reactor during the first 45 days, achieving steady-state toluene removals of 77% compared to 67%, with peak efficiency at 89%. Toluene biodegradation in both systems was highly dependent on nitrogen availability. From day 45, the conventional bioreactor improved, reaching steady-state removals over 87%. Furthermore, the addition of silicone oil to the bioactive coating-based bioreactor on day 70 increased toluene removal by a factor of 1.23. These findings demonstrate the potential of bioactive coatings and capillary supports to enhance VOC removal in bioreactors.