EFFECTS OF SURFACTANTS AT LOW CONCENTRATION ON BIODEGRADATION OF CRUDE OIL CONTAMINATED SOIL

Surfactants are being actively investigated as promising agents to enhance the bioremediation of spilled out over soil. The aim of this work was to evaluate the addition of surfactants in order to improve the bioremediation of petroleum contaminated soil. Regarding this purpose, three surfactants were used: a synthetic nonionic and two anionic (biological-rhamnolipid and a synthetic). Biodegradation essays with aforementioned surfactants were conducted at 50 % of Critical Micelle Concentration and 100 % of Apparent Critical Micelle Concentration, with previously established process conditions: 50 % of soil field capacity (F/C) and nutrient enrichment. These experiments were monitored by generation of CO2 during 42 days and by organic matter determination, utilizing ignition methods and thermal analysis. The anionic presented greater efficiency of biodegradation in concentration above the CMC. Below the CMC, there was no improvement in the biodegradation efficiency for both conditions in which the anionic were added. In the other hand, a little improvement of hydrocarbons consumption was observed in the presence of the nonionic