RECYCLED PULP WASHING, PART II - OPTIMUM WASHING SUBSYSTEM SELECTION FOR A SINGLE-LOOP ONP OMG DEINKING PLANT - ITS A DECISION BETWEEN QUALITY AND PRODUCTION COST/

Results obtained by computer simulation are reported on the effect of different washing equipment and sub-systems on the overall deinking pl ant performance and end product quality in terms of process yield, min imum fresh water consumption,contaminant content and removal efficienc y (ink, dissolved solids, ash, GOD) as well as brightness gain. The re sults obtained show that the optimum washing sub-system depends on the importance given to either end product quality or production cost. Th e approach used in the present study allows to assess the effect of va rious alternatives on the end product quality and production cost, bea ring in mind environmental issues. When considering the end product qu ality results only the two washing sub-systems composed of a screw pre ss and a slusher or a decker give the best performance. When consideri ng factors related to pulp production costs such as, minimum fresh wat er consumption and maximum process yield, the washing sub-system compo sed of a disc filter and a twin wire press gives the best performance. This study can therefore offer guidelines for the design of future de inking plants or for modifications to existing installations.