Anaerobic removal of 1-methoxy-2-propanol under ambient temperature in an EGSB reactor.

Two laboratory-scale expanded granular sludge bed (EGSB) reactors were operated at 18 and 25 °C, respectively, for the treatment of synthetic wastewater composed of ethanol and 1-methoxy-2-propanol (M2P) in a mass ratio of 4:1. Reactors were operated first with continuous wastewater supply and after with discontinuous substrate supply (5 days a week, 16 h a day) to simulate shift working conditions. Under continuous wastewater supply chemical oxygen demand (COD), removal efficiency higher than 95 % was achieved at the end of the trial applying organic loading rates (OLR) of 29 and 43 kg COD m(-3) day(-1) at 18 and 25 °C; thus, corresponding to M2P OLR of 6.4 and 9.3 kg COD m(-3) day(-1), respectively. During intermittent supply of substrate, good performance was recorded at both temperatures with an OLR of 30 kg COD m(-3) day(-1) (M2P OLR of 6.6 kg COD m(-3) day(-1)). After 56 h without substrate supply, a decline in methane yield of 15-30 % was observed due to the deactivation of the biomass. Specific methanogenic activity (SMA) assays were carried out at the end of the experiments. SMA values using 1-methoxy-2-propanol as substrate were 24.3 and 7.8 ml CH4 gVSS(-1) day(-1) at 25 °C and at 18 °C, respectively. This is the first attempt to investigate the removal of 1-methoxy-2-propanol by EGSB reactors.