The use of surfactants as possible enhancers in bioremediation of creosote contaminated soil

A study on five nonionic surfactants (Arkopal-N-060, Arkopal-N-080, Arkopal-N-100, Hosaf-541-KS and Tween-80) commercially available in South Africa was carried out to determine their effect on the desorption and degradation of creosote in a soil contaminated with 250 000 mg kg(-1) creosote with a view to developing a cost effective methodology for treating creosote contaminated soils. The surfactants were studied in concentrations of 0.01, 0.1, 0.35, 0.5 and 1.0% (v/v) in liquid cultures. Results from the studies showed that all the surfactants studied were able to enhance the desorption and degradation of creosote to different extents. The enhancement ranged from as little as <10% in 0.1% surfactant to as high as 45% in 0.5% surfactant. The effect on degradation of creosote was more obvious (30-65%) in the different surfactants at different concentrations. Arkopal-N-060 was observed to be the most effective in the desorption and degradation of creosote. The effect of Hosaf-541-KS on the degradation of creosote was found to be comparable with those of Arkopal-N-060, however, its desorption capabilities were much lower than those of Arkopa-N-060. The concentration of the surfactant was found to play a significant role in desorption of creosote. It was observed that surfactant concentrations of 0.35 and 0.5% were the most effective in the desorption of creosote. Above and below these concentrations, the effect of the surfactants was observed to decrease. All surfactants studied were not found to inhibit microbial growth at the concentrations studied.