With the intensified consciousness of envioronment protection and the require of the environment protection law, the paper industy moves on gradually, from the tradional CEH processes to the low or no pollution ways-ECF or TCF bleaching. There are more and more attention paied to ECF bleaching which based on chlorine dioxide bleaching, due to its good strength and low cost, compared to TCF bleaching. Therefore ECF bleaching has been becoming a way to reduce pollution and improve the pulp quality. In ...