Repeated Regeneration of Granular Activated Carbon Used for Tertiary Treatment of Kraft Pulp Waste Water

Abstract

The carbon used for the tertiary treatment of kraft pulp waste water viz., spent carbon was repeatedly regenerated for 35 minutes at 830 C via eight use-regeneration cycles. The amount of steam introduced into a rotary kiln per minute was 80 ml (cdnverted into water)
. The yield of regenerated carbons was kept at 95 1 percent by volume on fed spent carbon. The bulk density and strength decreased with the number of repeated regeneratien cycles. On the other hand, the internal surface area and total pore volume increased gradually, in a similar manner as the adsorptive capacity for 12, methylene blue or DBS did. But the adsorr ptive caPacity for kraft lignin showed a maximum at 5 th regeneration. The median value of particle size distribution shifted to smaller size with repeated regeneration.
The strength of the regenerated carbdn containing virgin carbon, the amount of which corresponds to the carbon lost at regeneration step, was calculated and ifound that its decrease in strength is less than not containing virgin carbon.