3.2. Performance of one stage fermentation
Methane was produced after 12 h incubation for all F/M ratios (Fig. 5A). CH4 content was in the range of 36–46%. Maximum of CH4 potential, rate and yield were obtained at F/M of 7.5, and the trend of these parameters versus F/M ratios was found in similar patterns to those in the two stage process (Fig. 5B). Little VFAs were leftover after 96 h fermentation (Fig. 6). The energy recovery from the one stage fermentation is equivalent to 3.4 × 10−3 kW-h.