Modelling mass transfer properties in a biotrickling filter for the removal of isopropanol

A study was carried out to model mass transfer properties in biotrickling filters, treating isopropanol as the target pollutant. This study was extended to the mass transfer of oxygen related to the fact that the treatment of hydrophilic compounds by biotrickling filtration is often limited by oxygen. A simple method for each compound was developed based on their physical properties. The influence of temperature on Henry's law constant of isopropanol was determined. An increase of 1.8 per 10 degrees C for the dimensionless Henry's law constant was obtained. The determination of the overall mass transfer coefficients of isopropanol (K(G)a) was carried out, obtaining values between 500 and 1800 h for gas velocities of 100 and 300 m h(-1). No significant influences were observed for either the liquid velocity or packing material. Also, the determination of overall mass transfer coefficients of oxygen (K(L)a) were carried out, obtaining values between 20 and 200 h depending on the packing material for liquid velocities between 2 and 33 m h(-1). Structured packing materials exhibited greater mass transfer coefficients, while for random packing materials, the mass transfer coefficients clearly benefited from the high specific surface area. Mathematical correlations found in the literature were compared with the empirical data, showing that neither was capable of reproducing the mass transfer coefficients obtained empirically. Thus, empirical relationships between the mass transfer coefficients and the gas and liquid velocities are proposed to characterise the system. (C) 2014 Elsevier Ltd. All rights reserved