BLEACHING DEINKED PULPS

While efficient fiber use has always been a hallmark of any pulp and paper operation, recent environmental and legislative pressures have necessitated serious consideration of the use of recycled waste in newsprint production. Since newsprint brightness demands have also increased, bleaching deinked pulp has become necessary. Using newsprint and magazine secondary fiber deinked by washed or flotation-washed systems, we examine a number of bleaching systems: sodium hydrosulfite, (Y); formamidine sulfinic acid, (Y(FAS)); hydrogen peroxide, (P); and hydrogen peroxide followed by sodium hydrosulfite, (PY). Both Y and the two-stage PY technologies are effective low-cost technologies to bleach these pulps.