ECF bleaching technology uses oxygen delignification and, in later stages, chlorine dioxide in combination with other chemical agents, in a sequence of treatments to achieve full brightness.
TCF bleaching combines oxygen delignification with peroxide brightening in a series of treatment stages. Enzymes may be used to enhance the bleaching process. A chelating agent is added to bind the metal ions contained in the pulp to prevent them from decomposing the hydrogen peroxide.
Neither ECF nor TCF bleaching produces any harmful chloro-organics, but both processes are likely to yield less pulp per ton of wood fiber than conventionally bleached pulp as the increased number of bleach/wash stages results in greater fiber loss. TCF, which has the most protracted bleaching cycle, has the lowest yield.