Pulp and paper plants are amongst the most polluter industries in this country and elsewhere. Most of the organic halides (AOX) and colour from pulp bleaching units are discharged to the receiving basins without being fully treated. A fungus, which is able to affect over 50% AOX and colour removals from soft-wood bleachery effluents within two days contact time, have been isolated in this laboratory. Optimum condition for dechlorination by this fungus in batch tests was determined as pH 5.5 and 25 degrees C. The low agitation speeds required by the fungus indicated its tendency towards immobilisation on a solid substrate. Glass wool was chosen as a suitable immobilising matrix to be used in the continuous experiments. An up-flow column was packed with glass wool and operated successfully for over one and half years with AOX removals around 70% in 7-8 hours contact time. Fungal dehalogenation required very low supplemental carbon and no DO. The fungal reactor was also effective in dechlorinating polychlorinated aromatics, e.g. PCP, though dehalogenation ability decreased considerably with the chlorinated aliphatics. High PCP concentrations presumably toxified the fungus, even at short exposures, thereby irreversibly damaging the column reactor. (C) 1999 Published by Elsevier Science Ltd on behalf of the IAWQ. All rights reserved.