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For many years the PDC has worked closely with the pulp and paper industry to develop new and effective bleaching sequences. We can perform a wide range of bleaching sequences on mechanical, recycled and chemical pulps.

The main objective of bleaching is to produce a brighter pulp. This is accomplished in chemical pulps primarily through lignin removal. The removal of other compounds is another objective of the bleaching process. These compounds include resins, fatty acids and other extractives.

Both Totally Chlorine Free (TCF) and Elemental Chlorine Free (ECF) sequences are routinely performed here at the PDC’s labs. The sequences may be comprised of a variety of stages, including chelation, enzyme, oxygen, ozone, chlorine, chlorine dioxide, extraction and hydrogen peroxide stages. Oxygen delignification and hydrogen peroxide bleaching at high temperature and high pressure are carried out in reactor vessels. Ozonation at high consistency takes place in a rotating glass vessel. For liquid bleaching agents, PDC researchers utilize the more conventional technique involving polyester bags.

Bleaching Equipment

  • Medium consistency oxygen reactor
  • Quantum reactor
  • Laboratory bag bleaching apparatus (Cl2, ClO2, H2O2, E stage, H, FAS, etc.)
  • Ozone generator and reactor
  • 100% ClO2 generation reactor
  • Stainless steel handsheet set-up

Bleach Effluent Analysis

  • Residuals and pH
  • Absorbable Organic Halide (AOX)
  • Chemical Oxygen Demand (COD)
  • Biological Oxygen Demand (BOD)
  • Total Dissolved Solids (TDS)
  • Color


  • Oxygen delignification of hardwood and softwood pulps
  • Optimization and kinetics of oxygen delignification
  • Evaluation of effects of pulping on bleachablity
  • ECF and TCF bleaching of hardwood and softwood pulps
  • Bleaching of mechanical and secondary fibers

To begin working with us, visit our Planning Your Project page.