Toxicity assessment of raw and ozonated textile biocides

The acute toxicity of two biocides frequently used in textile finishing as broad-spectrum antibacterial/antifungal agents was studied using the marine algae Phaeodactylum tricornutum and a standard activated sludge inhibition test (ISO 8192). The influence of ozonation on several environmental sum parameters was also assessed. Both biocides exhibited significant toxicity toward the test organisms studied. Ozonation at elevated pH (11.5) and high doses (3.0-3.4 mg O₃/mg COD₀) was necessary for an acceptable reduction in the examined collective environmental parameters. The activated sludge inhibition tests revealed that 30 min of ozonation corresponding to a dose of 1.7-1.9 mg O₃/mg COD₀ accounted for practically complete detoxification of the aqueous biocides, while for the marine algae test, complete toxicity reduction could not be achieved after 30 min of ozonation.