The Research Of Rhamnolipid Applying At The Treatment Of The Oil-containing Wastewater

Because the natural degradation rate of petroleum hydrocarbons is slow, adding some materials to the polluted environment, and optimizing the degradation condition can often accelerate the biodegradation of the petroleum pollutant. Some researches have indicated that surface-active compounds can promote the emulsification of the petroleum hydrocarbons, increase the solubility and the bioavailability of the petroleum hydrocarbons in the water. Compared with the chemical surfactants, biosurfactants are favored by more and more people because of their unique attributes, various structures, biodegradability, mildness to the environment and so on.Biosurfactants are applied to enhance the oil recovery and bioremediation the site that polluted by the organic matters in recent years. In order to expand the application of the biosurfactants in the pollution control, our research was focus on the following aspects and received several conclusions.(1) There are many oil degrading strains in the nature. Four strains of bacteria that could use diesel oil as the sole carbon source having been screened from soil that polluted by oil-containing wastewater. These bacteria were identified as Serratia sp., Bacillus sp., Azomonas sp. and Acinetobacter sp.(2) The degradation of the petroleum hydrocarbons is influenced by many factors, such as the sort and composition of petroleum hydrocarbons, the physical state, the concentration, temperature, pH, oxygen supply, nutrients, et al. The results showed the biodegradation of diesel oil by the dominant strain was significantly enhanced by the amendment of rhamnolipid biosurfactant, the % biodegradation of diesel oil was 11%~26% higher with rhamnolipid than without. It implied that rhamnolipid was not only no posionous to Azomonas sp., but also can be utilized by microorganisms as carbon and energy sources. Through studying the kinetics, adding rhamnolipid can shorten the half-life of the degradation of petroleum hydrocarbons for one time. By designing orthogonal tests, this paper studied four factors in water which influencing the degradation rate of hydrocarbons, such as culture temperature, culture time, dosage of rhamnolipid and the concentration of petroleum hydrocarbons. It also can be concluded that culture time was the dominant factor effecting on the biodegradation of diesel oil, culture temperature was the second one, followed by the concentration of petroleum hydrocarbons, and the dosage of rhamnolipid. In order to judge the suitability of the chose influence factor, so as to accept or reject the factor, this paper...