Hydrocarbons biodegradation by activated sludge bacteria in the presence of natural and synthetic surfactants.

Fuels, such as diesel oil, can have a substantial impact on the microbial equilibrium of activated sludge and have a negative influence on work of wastewater treatment plant. The primary objective of the research was to examine the possibility of using the surfactants to improve pollutants biodegradation by bacteria from activated sludge. The results showed that the addition of rhamnolipids allows to increase the hydrocarbon biodegradation from 47% up to 75% in the cultures inoculated with the consortium. The saponins increased the degradation of diesel oil by the two isolated strains: from 27% to 43% for Alcaligenes sp. and from 44% to 64% for Pseudomonas sp. The addition of surfactants to the cultures growth with diesel oil caused a significant decrease of the surface charge for Alcaligenes strain in the presence of saponins, but not in other cases. The obtained results revealed the potential of natural surfactants to support hydrocarbon biodegradation in wastewater treatment plants.