The effect of toluene on biofiltration of ethyl acetate- and toluene- contaminated air stream by using PVA-immobilized cell beads

摘要

To investigate the interactive effects of mixed cultures on biodegradation of ethyl acetate and toluene mixtures in air biofilters, three bacterial strains using ethyl acetate or toluene as selective substrates were grown in suspension and immobilized into the PVA entrapped-cell beads. The results show that the optimal inoculant weight, pH and temperature for the mixed cultures were 20% (w/w), 7, and 28degC. Simultaneously increasing the T/E loading (T/E beyond 8:8) at the same rate, or increasing only the toluene loading will cause inhibition on biodegradation of ethyl acetate. The phenomenon was more significant when the loading become more and more, but it can be reduced or prevented with the immobilization technology. In the group of strain AC6 and strain B5, mixed cultures show a synergy effect to improve the biodegradation of toluene. However, the group of strain B5 and strain F1 with the same target of food shows the completely different results. Strain B5 is very sensitive and vulnerable to strain F1. The substrate inhibition and microbial population competition were the major cause for inhibition on biodegradation of ethyl acetate or toluene under control conditions.