Methanogenic potential of an anaerobic sludge in the presence of anionic and nonionic surfactants

Abstract

The methanogenic potential of an anaerobic sludge in the presence of nonionic surfactant Alcohol Ethoxylate (AE) (GENAPOL® C-100) and anionic surfactant Linear Alkylbenzene Sulfonate (LAS) from laundry wastewater was evaluated in anaerobic batch reactors. For this purpose yeast extract, sucrose, sodium bicarbonate, salt solution plus AE (7.2 ± 0.9 mg L−1 – 123.4 ± 34 mg L−1) or LAS (16.3 ± 2.5 mg L−1 – 75.4 ± 7.5 mg L−1) were used as synthetic substrate. The reactors were kept under agitation of 130 rpm at 30 ± 1 °C for 28 days. The highest concentrations of AE and LAS provided higher methane yields. The highest surfactant degradation observed was for the AE (99%), compared to LAS (71.10% ± 11.3). The presence of other compounds in the laundry wastewater may have impaired this degradation, but favored higher COD removal efficiencies (86.2% ± 2.8). High concentrations of AE influenced COD removal efficiency resulting in less COD removal. Although higher concentrations of surfactants have favored higher methane production, lower similarity indices were observed for both Domains (Archaea and Bacteria).