RESUMO
Nonylphenol ethoxylathe (NPEO) is a non-ionic surfactant of increasing concern, used in the formulation of laundry detergents and is frequently found in aquatic environments. The purpose of this study was to evaluate the effects of yeast extract (YE) and sodium fumarate (SF) in NPEO removal from domestic sewage under anaerobic conditions via central composite rotatable design (CCRD) and response surface methodology (RSM). Experiments were designed by varying concentrations of NPEO (1.6-5.8â mgâ L-1), YE (131.8-468.2â mg L-1) and SF (97.7-602.3â mgâ L-1) in batch reactors. SF and YE addition significantly influenced NPEO removal and CH4 production. Optimal values of YE (400â mgâ L-1) and SF (200â mgâ L-1) result in removal efficiency of 97% for 5â mgâ L-1 of NPEO, being mostly removed by biodegradation (86%). Meanwhile COD removal was 95% and methane yield was 134 ± 4 NmLCH4 g-¹CODremoved. The most abundant Bacteria genus identified were Macellibacteroides, Longilinea, Petrimonas and Proteiniphilum, while for Archaea, Methanosaeta and Methanoregula were the genera identified in higher relative abundances in optimized conditions.