Start-Up and Performance of an Anaerobic Contact Plant as Part of a Dissolving Sulfite Mill Treatment System, 1990 Environmental Conference Proceedings

Two 25,000 cubic meter anaerobic reactors designed by Purac Engineering to treat 14,000 cubic meters per day (170,000 kg COD) of evaporator condensate and caustic extraction liquor were integrated into the operation of Alaska Pulp’s dissolving sulfite mill during 1989. This paper reviews the construction, commissioning, and integration of anaerobic treatment into the overall effluent control system of the mill. Stainless steel and urethane coatings were extensively specified for corrosion protection. Hydrostatic testing of the reactor vessels was accomplished while floating the reactor domes (constructed on the tank floor) into position. Integration of anaerobic treatment with existing mill systems presented significant problems throughout design, construction and commissioning. Operating problems experienced during the fifteen months since start-up include initial heating of the seed sludge, purging air from the reactors during tank filling, VFA response to CEL loading, mixer seal integrity, bio-solids retention, H2S gas safety, and NPDES compliance.