Toxicity and Biodegradability Behavior of Xenobiotic Chemicals Before and After Ozonation: A Case Study with Commercial Textile Tannins

Abstract

Ozonation of a natural tannin (NT; CODo = 1195 mg/L; TOCo = 342 mg/L; BOD5,o = 86 mg/L) and a synthetic tannin ST; CODo = 465 mg/L; TOCo = 55 mg/L; BOD5,o = 6 mg/L) being frequently applied in the polyamide dyeing process was investigated. Synthetic wastewater samples containing these tannins individually were prepared and subjected to ozonation at varying ozone doses (625– 1250 mgO3/L wastewater), at pH = 3.5 (the application pH of tannins) and pH = 7.0 at an ozone dose of 1125 mgO3/L wastewater. The collective environmental parameters COD, TOC, BOD5, UV254 and UV280 (UV absorbance at 254 nm and 280 nm, representing aromatic and unsaturated moieties, respectively) were followed during ozonation. Changes in the biodegradability of the tannins were evaluated in terms of BOD5 measurements conducted before and after ozonation. In addition, activated sludge inhibition tests employing heterotrophic biomass were run to elucidate the inhibitory effect of raw and ozonated textile tannins towards activated sludge ...