METHOD FOR CONVERTING ORGANIC WASTE INTO BIOGAS

摘要

PROBLEM TO BE SOLVED: To digest even organic wastes having a high nitrogen content. SOLUTION: A slurry of organic wastes 1 is heated to 150-350 deg.C in a hydrothermal treater 9 to convert the wastes into hydrothermally solubilized solubles 14. The hot solubles 14 are cooled to about 100 deg.C with a cooler and simultaneously reduced in pressure to the atmospheric pressure by means of a pressure reducing valve 13, and it is transferred to a flashing tank 11 where it is allowed to stay for a necessary time. Most of the ammonia contained in the solubles 14 is stripped by the flashing. The formed ammonia vapor 23 together with steam 22 is withdrawn from the ammonia withdrawal port 15 of the tank 11. The solubles 14 with an ammonia concentration lowered by stripping ammonia is transferred to a digester 4, where it is anaerobically digested to form a biogas 5. The effluent 6 from the digester is denitrified in a wastewater treater 7 and then discharged.