TREATMENT OF CHLORINATED ORGANICS IN BLEACHED KRAFT MILL EFFLUENTS BYACTIVATED-SLUDGE PROCESS

Combined effluents from a bleached Kraft pulp mill using annual plants were treated in a lab-scale activated sludge (AS) system. The effects of operating solids retention time (SRT) and concentration of additio nal carbon source on AOX removal were investigated. Higher AOX removal s (30%) were observed with long SRTs, 99% of which was pure metaboliza tion. As SRT was decreased AOX removal efficiency also decreased (4%) and principal AOX removal mechanism changed to adsorption onto wasted biomass. The AOX removal efficiency was lower (10%) on a 20% decrease in the supplemental carbon source, with no apparent effect on the remo val mechanism. (C) 1997 IAWQ. Published by Elsevier Science Ltd.