Design and test of auxiliary heating cluster case type biogas system for animal dejecta

A new type anaerobic fermentation system—auxiliary heating cluster case type biogas system for animal dejecta was designed. This system used solar heating and auxiliary heating, which was composed of independent unit and could assemble different scales of biogas engineering such as 50, 100, 200, 300 and 500 m³ according to farm scale. Then its operating test and techno-economic evaluation of the typical engineering were conducted. The results showed that the yearly average tank volume aerogenesis rate of the system was 0.80 m³/(m³·d), thermal value of biogas produced from it was 25.40 MJ/m³, COD concentration of pig dejecta waste water after treatment decreased from 36500 mg/L to 6500 mg/L, and dislodging rate of COD reached 82.2%. Concentration of suspension decreased from 17000 mg/L to 1900 mg/L, and dislodging rate of suspension was 88.8%. The net present value (NPV) was 183530.5 Yuan, and static period was 3.58 year. The system was feasible in technology and economy and had the good prospect of commerialized operation.