ABSTRACT
Elimination of toxic contaminants through source control is the most satisfactory corrective measure, but will require massive investment for in-plant modifications. The activated sludge (AS) process, operated in an extended aeration mode, is considered a technically effective and practical biological treatment process for consistent control of conventional and persistent toxic contaminants. An alternative in-plant source control is anaerobic reductive dechlorination, which is a biological treatment process that could be used to treat segregated bleach plant wastewaters. Achievement of virtual elimination of toxic contaminants will require a massive investment for in-plant modifications. Anaerobic biological treatment has shown promise as an option for the dechlorination of chlorinated organic compounds. Based on the investigations, the AS process, operated under relatively conservative conditions, is considered to be the most effective biological treatment technology for consistent control of conventional contaminants and persistent toxic substances in pulp and paper mill effluents.
