Recycling of dyehouse effluents by biological and chemical treatment.

A combined biological and chemical process of purification and recycling of residual dyehouse effluents was developed, investigated and installed at a textile finishing company which produces 330,000 m3 colored wastewater effluents per year. The process divided effluent into two streams. Both streams were subjected to anaerobic dye-cleavage, aerobic mineralization of cleavage-products and biomass separation. One stream was also membrane filtered and treated with ozone, which made possible the recycling of 60% of the total discharge. By these means it was possible to increase the quality of the treated streams for recycling purposes, as well as the dye capacity of the textile mill, and to minimize the operating costs. Furthermore, the municipal wastewater treatment plant into which the textile finishing mill's water is discharged, did not need to enhance its capacity.