Consequences of Increasing Effluent Concentration on Secondary Treatment Performance, 2002 Environmental Conference Proceedings

A. Elliott and R. Voss

Many pulp and paper mills have adopted, or will be adopting, water reduction strategies. Increasing the degree of water system closure reduces the volume of effluent flowing to the wastewater treatment system with contaminant loading likely being maintained. In a study of a TMP newsprint mill that had a low water usage of 20 m3/adt, we investigated the impact that progressively more concentrated newsprint mill effluent would have on a laboratory biological treatment system. We used reverse osmosis to concentrate the primary clarified effluent being fed to the treatment system in order to simulate effluent volume reductions of 25, 50, and 75% corresponding to mill water usages of 15, 10, and 5 m3/adt, respectively. With reduced flows, the performance of the treatment system remained unchanged in terms of BOD, COD, TSS, and toxicity removal compared to a reference system. Improved sludge properties were found during the 75% effluent volume-reduction phase.