**Abstract**

The purpose of this chapter is to study the interactions that are established between inorganic auxiliaries and the by-products of contaminants present in effluents coming from dyeing operations during oxidation treatment processes using ozone, and the influence of auxiliaries and by-products on the behavior of dyes in subsequent dyeing processes using the treated water. Carrying the treatment until the complete elimination of the contaminants present in it is a very expensive operation. Because of this, it is chosen to discolor and reuse the spent dyebaths treated as many times as possible to take advantage of the water and the inorganic salts contained therein. The variable composition of the dyebaths involves kinetic aspects during the treatment, which is important to take into account in the design of the process. Various by-products are already generated from the beginning of the treatment, which will have an influence on the following stages of the same treatment process, as well as on the kinetics of the dyeing processes carried out using the treated water and on the results obtained in such dyeing processes. All this will depend on the chemical and dyeing class to which the dyes used during the subsequent dyeing processes belong.

**Keywords:** water reuse, oxidation, ozone, textile, dyes
