The effect of injected ozone on the microbial metabolic characteristics in biofilters treating gaseous toluene

• O3 in 40–300 mg m−3 improves microbial metabolic activities in VOCs biofilters.
• Metabolic patterns changed significantly at early stage after O3 injection.
• Utilizations of some non-biodegradable carbon sources were enhanced by O3.

O3 injection technique was developed recently and successfully shown the ability of controlling biomass, allowing enhanced VOCs removal efficiency in biofilters. However, the effect of injected O3 on microbial metabolic patterns is still unknown. In this study, six biofilters treating gaseous toluene were set up and operated continuously for 97 days with different inlet O3 concentrations ranging from 0 to 300 mg m−3. The metabolic functions and characteristics of the microbial communities in the biofilters were monitored by Biolog microplates cultivation method periodically. According to the profile of average well color development (AWCD), the metabolic activity of microorganisms in the biofilter with 300 mg m−3 O3 was increased by 100%. Principle components analysis (PCA) result demonstrated significant changes in biofilters exposed to O3, but eventually had little difference with those without O3 after long-term operation. Among 31 carbon sources in Biolog microplate, the utilization of some non-biodegradable carbon sources including γ-hydroxybutyric acid, d-galactonic acid γ-lactone, d-mannitol, d-cellobiose and β-methyl-d-glucoside were obviously enhanced by injected O3. The analysis on DQ-fd plot showed that the variation trends of metabolic diversity and dominance in biofilters with and without O3 were in some extent different.