NOVELTY - An underground fermenter (1) comprising an airtight lid (15) and compost raw material supplied to the fermenter by inserting a container assembly inside, is new. The container (3) has air permeable wire network around the periphery, and holds the raw material (M) which is treated by aerobic system.    USE - To compost organic refuse e.g. various sludge, waste from foodstuffs processing factory, and for fish processing.    ADVANTAGE - Almost the whole of the fermenter is embedded underground which improves the appearance and increases the effectiveness of use. The raw material is packed inside containers, which is loaded and unloaded into the fermenter easily and the use of large size loading installation is eliminated which reduces the installation cost. High quality compost product is produced in a short period.    DETAILED DESCRIPTION - The cylindrical fermenter (1) is installed underground and has airtight lid (15) which is opened for inserting cylindrical container (3) assembly inside the fermenter. The container has a wire network around the periphery which allows the passage of air into the compost raw material kept inside. Air supply is maintained by the feed pipe (21) connecting the blower (2) to the air dispersion device (22) installed at the bottom of the fermenter. A sump pump (7) is installed outside the fermenter and the water absorption end of the drainage pipe (71) connected to the pump opens in the fermenter. Each container (3) has legs (39) at the bottom, connectors at both the top and bottom and hanger (38) at the top to automatically support containers placed above. The container assembly is formed by connecting the containers. An exhaust port (17) is provided to the fermenter lid. The side wall (14) of the fermenter and the lid (15) are attached to the bottom concrete floor panel.    DESCRIPTION OF DRAWING(S) - The figure shows the vertical front view of the composting apparatus.    Cylindrical fermenter (1)    Blower (2)    Cylindrical container (3)    Sump pump (7)    Side wall (14)    Airtight lid (15)    Exhaust port (17)    Feed pipe (21)    Dispersion device (22)    Hanger (38)    Legs (39)    Drainage pipe (71)    Raw material (M)