chlorine dioxide dose is approx 5 30 kg metric ton and a preferable per compound dose is 2 10 kq metric ton the chelating agents can be used together with chlorine dioxide and for example a combination of chlorine dioxide and peracetic acid in these stages the ph is typically on the acid side with chlorine dioxide lt 4 delignification or 4 5 bleaching and with peracetic acid it is 5 7 with a combination of chlorine dioxide and a per acid the optimum ph is approx 5 6 this ph range is highly suitable for the above mentioned chelating agents it has additionally been observed that the bceea u2014 bceeaa mixture does not break down under the effect of these bleaching chemicals but instead is capable of even stabilizing peracetic acid in the conditions concerned furthermore it has been observed that the said chelating agent mixture forms metal complexes in a more or less normal manner in spite of the presence of strongly oxidizing bleaching chemicals what has been gained by this procedure is that it is possible to enhance especially bleaching carried out using low chlorine dioxide doses i e so called ecf light bleaching because owing to the improved metal control the consumption of.