Influence of cosubstrates for linear anionic sulfonated alkylbenzene degradation and methane production in anaerobic batch reactors

Abstract This study evaluated the influence of cosubstrates, acetate, formate, and fumarate on the anionic surfactant degradation (linear alkylbenzene sulfonated - LAS), using anaerobic batch reactors at 30 °C, 50 rpm at 25.8 ± 0.2 mgLAS/L. Cosubstrates were tested separately for LAS degradation and methane production. Organic matter removal efficiency were 23 ± 1.2%, 65 ± 2.8%, 60 ± 5.6%, 59 ± 0.8% and 75 ± 2.7%, for control without LAS (67 ± 11.9 mg/L), control with LAS (129 ± 27.2 mg/L), reactors with acetate (172 ± 19.8 mg/L), formate (126 ± 13.7 mg/L) and fumarate (332 ± 16.3 mg/L). Methane production for the experimental series was 0.072 ± 0.002 µmol, 0.6 ± 0.07 µmol, 1.69 ± 0.11 µmol, 1.51 ± 0.15 µmol and 2.18 ± 0.24 µmol in control reactors in the absence and presence of LAS and with the acetate, formate and fumarate, respectively. Under the nutritional conditions with cosubstrates, there was a higher LAS degradation in both dissolved and adsorbed fraction in anaerobic biomass. These cosubstrates can directly assist the metabolic pathways of microorganisms for energy generation and toxic removal. Among the cosubstrates tested, fumarate favored greater LAS degradation reaching a removal efficiency of 98.3 ± 0.8% for 26 ± 1.13 mg/L of surfactant and also provided higher methane production in anaerobic batch systems.