Mutagenic activity in wastewater concentrates from dye plants.

Wastewater concentrates from the wastewater treatment systems of three dye plants were tested for mutagenic activity in Salmonella typhimurium TA98 and Escherichia coli WP2uvrA using a fluctuation assay. Concentrates were prepared by passing samples of wastewater (5-6 or 30 litres) through two porous resins (XAD-2 and XAD-7) in series. S. typhimurium in the presence of microsomal activation proved to be the more sensitive marker of mutagenicity. Mutagenic responses were observed in concentrates from all three plants tested. The results show that mutagenic activity was particularly high in the incoming waters and increased after active, biological treatment. Physico-chemical treatment may be effective in decreasing mutagenic activity, but only if appropriately used.