Removal of o-xylene from off-gas by a combination of bioreactor and adsorption

Biofiltration is an effective technology for the treatment of gaseous waste. However, a biofiltration system needs a bioreactor of large volume and it is slow to adapt to fluctuating concentrations in waste gas. To overcome these disadvantages, a bench-scale system integrating a biofilter and an adsorption unit for the treatment of gases containing o-xylene was investigated in this study. The adsorption unit was packed with granule active carbon (GAC). The results showed that 90% of o-xylene could be removed in the biofilter at an inlet concentration below 900 mg/m3. The maximum elimination capacity was 80 g/m3h when the o-xylene loading rate was less than 100 g/m3h. High o-xylene concentration in inlet gas resulted in an overload of the biofilter. Using the adsorption unit, the outlet concentration of o-xylene could be reduced significantly. The surface properties of GAC and the factors affecting the adsorption performance were investigated, and GAC regeneration method was also evaluated. The combination of adsorption and microbial processes not only led to a high and stable efficiency of o-xylene removal, but also improved the capacity of resisting the shock loads.  2008 Curtin University of Technology and John Wiley & Sons, Ltd.