Successful treatment of dilute ethylene glycol based-aircraft de-icing fluid (ADF) was achieved using a four compartment, anaerobic baffled reactor (ABR). Three ADF concentrations (0.04, 0.07, and 0.13% v/v) were continuously fed at different hydrological retention times (HRTs: 24,12, 6 and 3 h) with concomitant organic loading rates (OLRs) varying between 0.3 and 6 kg chemical oxygen demand (COD)/m(3)/d. ABR achieved over 75% soluble COD removal and an average methane production potential of 0.30 +/- 0.05 L CH(4)/g COD(removed) at 33 degrees C for the experimental conditions evaluated. The different experimental conditions tested and a four-month summer shut-down simulation had no significant effect on reactor performance or on the settling characteristics of the granular biomass, which remained almost constant during the study. Biomass specific acetoclastic activity however, changed through the study: increasing two fold for the last three compartments and decreasing almost the same magnitude for the first compartment compared to inoculum, suggesting that a new distribution of microbial consortia was established in each compartment of the reactor by the end of the study. (C) 2009 Elsevier Ltd. All rights reserved.