The temperature, pH and oxidation/reduction potential of the sample were 53.1 uC, pH 6.8 and less than 2300 mV, respectively. Mineral medium (W medium) and saline mineral medium (WS medium) were used to enrich the methanogen. W medium was composed of (l21) 0.535 g NH4Cl, 0.136 g KH2PO4, 0.204 g MgCl2 . 6H2O, 0.147 g CaCl2 . 2H2O, 2.52 g