FATE OF WOOD EXTRACTIVES IN WASTEWATER TREATMENT PLANTS AT KRAFT PULP MILLS AND MECHANICAL PULP MILLS

The activated sludge treatment of 3 Finnish wastewaters treatment plants show that it is an efficient process in order to reduce the toxic sterols and fatty acids-containing effluents from elemental chloride-free and total chlorine-free bleached pulp mill effluents. Reduction of wood extractives by up to 99%. During biotreatment, sterols are mostly transformed than degraded. The transformation products have been found to have androgenic effects on fish.