Improved peroxidase-mediated biodegradation of toluene vapors in the moving-bed activated sludge diffusion (MASD) process using biosurfactant-generating biomass stimulated with H2O2

Two strategies were attempted to improve the biodegradation and mineralization of toluene vapors in the activated sludge diffusion (ASD) process using biosurfactant-generating Pseudomonas spp. and Bacillus spp. mixture. Different operational parameters including toluene concentration, superficial air velocity, biomass concentration, moving-media insertion and H2O2 were evaluated on toluene removal in the ASD process within 550 days of operation. It was found that complete biodegradation and 79.8% mineralization of toluene vapors at inlet loading rate of 144 g/m3.h could be achieved in the ASD process by inserting moving media (MASD) at a volume ratio of 20% along with stimulation of bacteria with H2O2. The concentration of biosurfactant and peroxidase generated in the integrated process (H2O2-stimulated MASD reactor) was 3.7 and 2.5 times of that in the conventional ASD process. The maximum toluene elimination capacity obtained in the H2O2- stimulated MASD process was 285 g/m3.h at an inlet loading rate of around 430 g/m3.h. Accordingly, H2O2-mediated MASD process could be a promising technique for efficient biodegradation and mineralization of aromatic hydrocarbons in the contaminated air streams.