Fate of tolyltriazoles and nonylphenol ethoxylates in upflow anaerobic sludge blanket reactors

The fate of tolyltriazoles, nonylphenol and nonlyphenol ethoxylates during anaerobic treatment of ethylene glycol (EG) based wastewater during batch or continuous upflow anaerobic sludge blanket reactors was investigated. Equilibrium sorption studies indicated that there was minimal sorption of benzotriazole (BT), 5-methyl-1 H-benzotriazole (MeBT), and 5,6-dimethyl-1 H-benzotriazole (DiMeBT) to anaerobic granules. Nonylphenol (NP), a reported biodegradation product of NP ethoxylates, had a higher sorption capacity to anaerobic biomass and was described by the Freundlich isotherm. Batch serum bottle EG degradation experiments indicated that BT, MeBT, DiMeBT, and the nonionic NP ethoxylate surfactant Tergitol NP-4 had no significant effects on acidogenesis and methanogenesis at the concentration levels studied. Significant inhibition of acetoclastic activity was observed for the biodegradation intermediate NP at 100 mg/L, with acetic acid consumption rate at 38% of the controls. No evidence for anaerobic degradation of benzotriazole and its derivatives was observed for both batch and continuously fed anaerobic systems. Continuously fed anaerobic experiments provided evidence that indicated that anaerobic degradation of nonylphenol ethoxylates and the biodegradation intermediate NP occurred.