Biodegradability, toxicity, and photochemical treatment of a textile surfactant

This study investigates the biodegradability, ecotoxicity, and photochemical treatment of a segregated textile bath discharge carrying a commonly applied nonionic surfactant. The wastewater having a total COD of 1,085 mg/L is completely soluble in nature. The COD distribution of this wastewater at different molecular size cut-off levels shows a fluctuating nature. Around 40% of the COD originates from a molecular weight cut-off range less than 30 kDa fraction. The wastewater is observed to contain an initially inert soluble COD of about 20 mg/L and the residual COD level achieved after passing it from aerobic biological treatment is only 40 mg/L indicating high biodegradability. After 120 min of UV-C application similar TOC removal efficiencies of 35 and 42% are obtained at pH 4 and pH 7, respectively. Photochemical treatment does not yield significant TOC removals at pH 11. The raw discharge is highly inhibitory toward Vibrio fischeri. 60 min of UV-C application lowered ecotoxicity toward V. fischeri.