Mill Studies on Closure of the Effluent Cycle in a Newsprint Mill, 1996 Minimum Effluent Mills Symposium Proceedings

J. Dorica, P. Ramamurthy, R. Crotogino, A. Elliott - Paprican

A. Chatterjee & W. Vrooman - Avenor Inc.

P. Wong - PO Wong Associates

The potential feasibility of recycling biologically-treated effluent from a newsprint mill back to the mill through the fresh water purification plant was evaluated at a mill site using full scale primary treatment, followed by pilot plant activated sludge treatment. Coagulant-aided primary treatment plus biological treatment of newsprint mill effluent removed 95-99% of both BOD and RFA and 91% of COD. The final treated effluent samples were non-toxic to trout (96-h LC50 > 100%). The final treated effluent exceeded the intake surface water in terms of COD, colour, sulphate, aluminum, calcium, chloride and SiO2 . Performance simulation of mill water purification plants was performed on a bench scale. An approximation of the steady-state concentrations of dissolved components in a purified 1:1 mixture of final treated effluent and surface water indicated that the expected steady-state levels would be within the range presently encountered in pulp and paper operations.