Industrial production of enzyme treated kraft pulp from radiata pine

Celulosa Arauco y Constitucion SA from Chile operates three pulp mills. One of them produces about 1,200 tons per day of market Kraft pulp from radiata pine. The bleaching sequence most commonly employed to reach the target brightness of 90 degrees ISO is D100E0D1ED2. With the aim of reducing the consumption of chlorine dioxide, during two years the mill explored the feasibility of using xylanases prior the application of the chemical sequence. Since results obtained first at a laboratory scale and then in mill trials were encouraging, the mill decided to incorporate enzymes to the production line about 15 months ago. Since then, biobleaching has been operating at Arauco mill on a regular basis, with savings of ClO2 of about 2.8 kg/ADT of pulp. In turn, the consumption of sodium hydroxide and sulfuric acid has increased about 1.0 and 4.5 kg/ADT of pulp, respectively. The AOX of the effluent is about 15 % lower than that observed with the standard bleaching procedure.