Abstract

Biofiltration is fast emerging as a feasible option for treating odorous compounds and other volatile organic compounds (VOCs) from process waste - gas streams using microorganisms attached to porous support matrix. Compost, owing to its inherent physico-chemical and biological characteristics, has shown to be a promising filter material in biofiltration to treat both hydrophobic and hydrophilic gas - phase VOCs at low concentrations and high gas flow rates. This study aimed at evaluating the potential of a laboratory-scale biofilter, inoculated with mixed culture, to remove gas-phase xylene from a synthetic waste gas stream. The performance of the biofilter was studied by varying the flow rate from 0.024 to 0.072 m³/h, corresponding to empty bed residence times varying between 0.81 - 2.45 min and by changing the inlet loading rates (ILR) between 3.5 to 208 g/m³.h. Removal efficiencies higher than 68% were achieved for xylene loading rates lesser than 60 g/m³.h. However, due to the hydrophobic nature of the pollutant, xylene, that hinders mass transfer, and/or substrate inhibition to the microorganisms, a significant reduction in the removal efficiency was observed at high xylene concentrations. The results demonstrate the potential of compost biofilter to handle microorganism- tolerable xylene loads under steady-state conditions.

Key words: Biofiltration, compost, gas-phase xylene, mixed culture, performance capacity.