Fig. 2. (a) Gas production during the first few days of anaerobic fermentation; (b) total COD composition at the start and end of each experiment; (c) soluble COD composition at the start and end of each experiment. Tests were carried out at various food to microorganism ratios (F/M, g COD g^–1 VS). F/M = ∞ refers to only substrate (5 g COD L^–1) while F/M = 0 to only inocula (10 g VS L^–1).