TREATMENT OF OFF GAS

PURPOSE:To enable the treatment of an off gas at a low treatment cost by maintaining an active carbon holdup facility under low humidity and packing the active carbon therein in the amt. corresponding thereto. CONSTITUTION:The active carbon holdup facility is operated while said facility is controlled at the low relative humidity of about 40%. The required amt. G of the active carbon is calculated from the equation (I) by using the relative humidity (x) of this time, the required amt. G(0) of the active carbon when the relative humidity is 0, the factor alpha expressing the influence that the moisture content of the active carbon exerts on the stagnation time, the specific surface area S of the active carbon, and the factor beta expressing the influence that the relative humidity exerts on the stagnation time of the active carbon. The active carbon is packed in this amt. into the active carbon holdup facility. The treatment is thereby executed without degrading the adsorption treatment performance of the facility even if the relative humidity is not maintained at nearly 0 by using a drying machine, etc. and, therefore, the energy for the purpose of dehumidification is reduced and the off gas is efficiently treated at the low treatment cost.