Biological treatability and environmental impact of ozonation of spent reactive dyebaths

The effect of ozonation of spent reactive dyebaths on both subsequent biolo gical wastewater treatment systems and ultimate aquatic toxicity of effluen ts from the wastewater treatment plant was determined. Acutal spent dyebath s from a textile plant were ozonated to remove color. The ozonated and untr eated control dyebaths were diluted to produce wastewaters similar in disso lved solids content to wastewaters typically discharged by a textile plant. These wastewaters were subjected to biological treatment, and effluent gen erated by the biological treatment was tested for toxicity to Ceriodaphnia dubia (C. dubia). Higher reproduction in the ozonated wastewaters compared to those receiving only biological treatment suggested that ozonation of th e spent dyebath tended to reduce the toxicity imparted by the wastewater af ter biological treatment.