PURPOSE: To reduce the loss of activated carbon with adsorption function deteriorated by adsorbing org. matter, etc. in a sewage treating tank and to elongate the life of the carbon by regenerating the carbon by spark discharge.

CONSTITUTION: The titled apparatus is composed of a dehydrator 7 for dehydrating activated carbon taken out of a water treating tank 1, a drier 14 for drying the dehydrated carbon, regenerating furnaces 30, 30' for regenerating the dried carbon by spark discharge, a carbon conveyor 38 for charging the regenerated carbon into the tank 1, and an incinerator 21 for incinerating org. gas generated from the furnaces 30, 30'. Heat generated from the incinerator 21 is supplied to the drier 14 to recover the waste heat. Said apparatus reduces the loss of activated carbon and elongates the life.