Anaerobic co-digestion of three organic wastes under mesophilic conditions: lab-scale and pilot-scale studies

An investigation on the efficiency and compatibility of anaerobic co-digestion of three substrates: food wastes (FW), chicken manure (CM) and digested sludge (DS) was carried out. Mixtures of two and three co-substrates in batch experiments were conducted in 0.5-L bioreactors during 8 days under mesophilic conditions. Parameters analysis such as pH, volatile fatty acids, free ammonia (NH3), total solids (TS) and total volatile solids (TVS) was used to explain the behavior of each substrate and their mixtures. For the anaerobic digestion of two co-substrates (CM/DS with 30/70 ratio), total biogas production was equal to 2.5 L and was greater than the volume obtained for the same ratio of FW with DS. The three co-substrates (FW/CM/DS) digestion with (20/10/70) ratio showed best performances for total volatile solids (TVS) reduction and process stability. On the pilot bioreactor, a ratio of (20/5/75) was used for (FW/CM/DS) anaerobic digestion. After 50 days retention time, the biogas production reached 413.85 L/g TVSadd with TS and TVS reduction of 79 and 87% respectively.