Abstract: A method for treating a mechanical pulp plant effluent waste stream by freezing the effluent stream and separating frozen product. The frozen product contains between about 50 to 150 ppm chemical oxygen demand (COD), and may be reclaimed.

Abstract: Apparatus and methods are disclosed for removing concentrated radioactive aqueous waste from an evaporator and delivering the waste to a storage tank. The evaporator drain conduits are maintained full of feed liquor when concentrated waste is not being removed from the evaporator and feed liquor is used to rinse the conduits after the concentrated waste removal through the conduits is completed. The liquid fed through the conduits is carefully controlled by a sequencer or timer. A fast acting evaporator drain valve is used which can be rinsed by feed liquor to avoid plugging and deposition of radioactive solids in the valve.