The invention relates to a method for the treatment and utilization of waste liquor containing at least polyester degradation products and originating from an alkaline pulping process for the extraction of cellulose raw material from blended textile waste which contains at least a cellulose component and a polyester component. In order to make the method environmentally friendlier and more resource-efficient, it is proposed that the method comprises the following steps: the evaporation of water from the waste liquor in order to precipitate the polyester degradation product from the waste liquor and to obtain a two-phase mixture having an aqueous phase and a solid phase including the polyester degradation product, b) the separation of the solid phase from the liquid phase, and c) the thermal/energetic utilization of the solid phase.