Removal of nonylphenol ethoxylate surfactant in batch reactors: emphasis on methanogenic potential and microbial community characterization under optimized conditions.

Nonylphenol ethoxylate (NPE) is an endocrine-disrupting chemical that has bioaccumulative, persistent and toxic characteristics in different environmental matrices and is difficult to remove in sewage treatment plants. In this study, the effects of the initial concentration of NPE (0.2 ± 0.03 - 3.0 ± 0.02 mg. L) and ethanol (73.9 ± 5.0-218.6 ± 10.6 mg. L) were investigated using factorial design. Assays were carried out in anaerobic batch reactors, using the Zinder basal medium, yeast extract (200 mg. L), vitamin solution and sodium bicarbonate (10% v/v). The optimal conditions were 218.56 mg.L of ethanol and 1596.51 µg.L of NPE, with 92% and 88% of NPE and organic matter removal, respectively, and methane yield (1689.8 ± 59.6 mmol) after 450 h of operation. In this condition, bacteria potentially involved in the degradation of this surfactant were identified in greater relative abundance, such as (1.68%), (1.52%), (0.91%), (0.57%) and (0.47%), as well as archaea and , mainly involved in hydrogenotrophic pathway.