Anaerobic digestion of swine manure: Sung-Hwan farm-scale biogas plant in Korea

In order to increase the use of biogas plants in Korea, a farm-scale biogas plant with a working volume of 200 m was constructed at the pig farm in Sung Hwan, Korea as a demonstration project supported by the Korean government. This plant mainly consists of an anaerobic digester processing daily 10 m pig manure and a dual-fuel engine-generator to produce heat and electricity. Digestion takes place in a semi-continuous, single stage, completely stirred anaerobic digester under mesophilic temperatures with maximum 0.8°C deviation per day from the setting temperature of 35°C. The digester was constructed as cylindrical flat-bottomed tanks instead of general conical bottoms. But it did not cause any serious mixing trouble. The results of solids profiles and temperature profiles inside the digester showed very small variations, which mean adequate mixing performances. During anaerobic digestion, 55% of volatile solids (VS) reduction in average was stably achieved. However no further VS reduction was occurred due to its inherent nonreadily biodegradable materials. The average biogas yield was 0.70 m per kg of added volatile solids. The biogas composition was relatively constant for the entire run with the 68-73% methane(V/V) and 27-30% carbon dioxide(V/V). The produced biogas was effectively used in a dual-fuel engine-generator to produce heat and electricity.