Paper recycling operations
When fibers are recovered from recycled papers, a wider spectrum of contaminants  will be present due to the variability in the nature of the used paper materials, their  contamination during paper's use and recovery, and the additives that are used for  dispersing the fibers, removing ink, and bleaching  Such waters are characterized by a high organic dissolved load, which typically has an anionic characte .Difficulties in gravitational separation of solids from deinking  operations might be attributable to the dispersants that are widely used to separate the ink  particles from the fibers.In this case, adequate coagulants and flocculants are required to  destabilize the colloidal material and promote the aggregation of particles for their removal  by sedimentation or dissolved air flotation (DAF).