The Blue Ridge Paper Products (formerly Champion), Canton mill, NC, recycles both the Eop and D₀ filtrates to meet strict permit requirements, for water use and effluent colour. As part of Champion International, the mill undertook an aggressive bleach filtrate recycle strategy (the BFR process). This strategy incorporates a metals removal process (MRP, i.e., based on ion-exchange technology) and a chloride/potassium removal process (CRP, i.e., based on evaporation-crystallization of ESP dust) into the recycling operation [1]. BFR uses oxygen delignification followed by three stages of post-oxygen washing and ECF medium consistency bleaching (OD₀EopD), with recycle of bleach plant filtrate to the recovery system. To optimize bleach plant operation, the chlorine dioxide charge in the D₀ stage was reduced from a kappa factor of 0.28 to between 0.18-0.22 before the recycle began [2]. Eop filtrate is recycled to the showers of the last post-oxygen washer, and D₀ filtrate is processed through a metal removal process before being recycled to the D₀ washer. A portion of the final D-stage filtrate is sewered, because of the minimal environmental effect and the higher chloride load that would have to be recovered. Click to continue »