PROCESS AND WASTEWATER TREATMENT PLANT FOR THE BIOLOGICAL TREATMENT OF DYE-CONTAINING WASTEWATERS FROM THE TEXTILE AND LEATHER INDUSTRY

: Process and wastewater treatment plant for the biological treatment of dye- containing wastewaters from the textile and leather industry 2.1. To treat dye-containing wastewaters, chemical and physical treatment methods have been used virtually exclusively hitherto. A process and a wastewater treatment plant operating according to this are now sought after, by means of which a biological treatment becomes possible. 2.2 According to the process, the dye-containing wastewaters are passed to an anaerobic preliminary stage having a negative redox potential, then they pass, after a minimum residence time in the anaerobic preliminary stage, depending on the type of the dyes, into a facultatively anaerobic or aerobic activation stage, in which, at a loading per unit volume of > 1.0 kg of BOD/(m3 x d) and at a positive redox potential between 0 mV and +180 mV, activated sludge is cultured which, after sedimentation, is partly recirculated to the activation stage and partly to the anaerobic preliminary stage and is otherwise removed after thickening. Nutrients are added to the wastewaters in the preliminary stage and/or in the activation stage In the preliminary stage, the negative redox potential is maintained. The wastewaters coming from the sedimentation stage are finally conducted into an aerobic secondary treatment stage and the treated wastewaters are thereafter discharged into a receiving body of water or utilised otherwise. 2.3. The process is suitable in particular for the partial stream disposal of wastewaters from the textile industry and leather industry, in particular for disposing of azo-dye-containing and sulphur-dye-containing wastewaters. No. of Pages : 14 No. of Claims : 20