Dissolved sulfide and COD were analyzed following standard methods (APHA, 1998). The analyses of cellulose, hemicelluloses,lignin contents and volatile fatty acids (VFAs) were the same as described in a previous publication (Wen et al.,2010). The pH and Eh were measured using a portable pH/mV/temperature meter (HACH, sensION1, USA) fitted with a
gel-filledpHelectrodeand a combination Ag/AgClEh electrode.