Bioremediation of water contaminated with motor oil by biological surfactants produced by Streptococcus thermophilus, using cheese whey as a carbon source

The hydrocarbons that contaminate water are difficult to remove, among other things, due to their hydrophobic nature. A surfactant is one way to facilitate contact between the treatment agents. This research prepared a biological surfactant from whey fermentation through Streptococcus thermophilus bacteria. To optimize its production, a complete factorial design was carried out, varying the factors temperature (38, 40, and 42 °C) and time (24, 48, and 72 hours), and the response variable is the amount of surfactant produced. It was found that the highest performance was obtained at 40ºC and 48 hours. The biosurfactant was characterized to determine hemolytic activity, Parafilm, oil dispersion, emulsification index (63.64 %), and surface tension (52.7 mN/m). The ecotoxicity test with Daphnia magna confirmed that the biosurfactant is environmentally friendly. Finally, a bioremediation process was applied during the 45 days when more than 50 % engine oil removal was achieved.