Modelling transport and degradation of hydrophobic pollutants in biofilter biofilms

Our results support a novel mechanism of biofiltration whereby a biologically mediated transformation is taking place with α-pinene being oxidised into a more soluble compound. This model provides an explanation for relatively high removal rates of hydrophobic compounds. A simple transport and reaction model based on zero-order kinetics was developed that fit results seen in a diffusion cell using active α-pinene leachate immobilised in low melting point agarose. The proposed identity of this more soluble by-product, is cis-2,8-p-menthadien-1-ol, a menthadienol, a novel metabolite of α-pinene degradation. By extension, this model fits biofiltration data collected from Raschig ring biofilters treating α-pinene. The paper also discusses implications of the model for the treatment of hydrophobic pollutants.