The purpose is to reduce the process cost of the cellulose and paper production.
The purpose of paper pulp bleaching is remove the impurities of dark lignin. The pre-bleaching with Oxygen allows the reduction of effluents volume and the consumption of high cost chemical bleachers. The most used bleaching methods are: ECF (Elemental Chlorine Free), where is used Chlorine Dioxide with chemical products chlorine free and the ECF (Elemental Chlorine Free) where are used Oxygen, Hydrogen Peroxide, Ozone and peracetic, completely chlorine free.
The advantages of the reinforced alkaline extraction are the economy of Chlorine Dioxide with low Oxygen consumption, flexibility on process conditions.
The advantages of the washing of paper pulp with CO2 are the increasing of washing capacity, lower vapor consumption once it reduces the washing water quantity necessary to keep a certain level of transference and additives reduction.