Macrokinetic determination and water movement in a downward flow biofilter for methanol removal

A steady state model was developed to predict water movement within the biofilter bed. The model's predictions were compared to experimental data from a downward flow biofilter (50 cm x 10 cm W.) using compost for removing methanol with concentrations in the range of 0.46-8.41 g m(-3) and flow rates of 1.36-4.08 m(3) per day. The Wani et al. [J. Chem. Technol. Biotechnot. 74 (1999) 9] method of macrokinetic determination was used to estimate the kinetic parameters, and the predicted results showed that this method could be used for methanol removal systems as long as the conversion rate is not limited by diffusion in the biofilm (reaction-controlled regime). The leachate from the biofilter was collected and compared to the model predictions. The amount of collected water increased much more rapidly with inlet methanol concentration than predicted by the model. This shows that there are effects that are not adequately taken into account, such as the breakdown of compost, or biofilm, resulting in loss of water holding capacity, formation of new biofilm, and changes in physical structure. However, this model can be used to estimate the amount of water to be added to ensure that biofilm activity is maximized. (C) 2002 Elsevier Science B.V. All rights reserved.