There are obvious advantages of biosurfactants over chemical surfactants. The developing shortage of oil and rapid increase of oil prices is putting pressure on oil companies to recover as much oil as possible from the wells to sustain the oil economy. Therefore, there is a need to research some "super bugs," which can produce active and stable biosurfactants in good yields. Five bacterial strains presently isolated from the oil-contaminated soil were selected for the screening for biosurfactant production, via three different methods: surface tension measurements, drop-collapsing test, and emulsification index (EI 24 ) test. Two thermophillic isolates coded as SGI and LFA were found to be the suitable candidates for biosurfactant production. In fact, the biosurfactant produced by the isolate SGI led to the reduction of surface tension up to 26 m/N/m; thus, SGI was selected for the further studies. Biosurfactant production by the thermophillic isolate SGI was found to be growth-associated in all conditions tested. Biosurfactant production using different cheaper carbon substrates was studied. The production of biosurfactant was also studied using isolate SGI, under different conditions of high temperature, NaCl concentration, pH, carbon source, and initial nitrogen concentration. The biosurfactant was found to produce a relatively stable emulsion with hydrocarbons at a wide range of pH. It was also found to be stable at various pH ranges (7.0-14.0) for SGI and was also found to be thermostable for 1 hr at 125 ı C, based on the value of surface tension. There is a wide array of further studies in the area of microbial enhanced oil recovery (MEOR) including further boosting the activity of the isolate by using adaptation, enrichment, and nutrient enrichment techniques.
Petroleum coke (petcoke) is an inexpensive potential fuel. However, its use has been limited because of the low volatile content and high sulfur contents. Moreover, research work has been extended for reducing the sulfur contents in petcoke. However, there is still no commercially established process of desulfurization of petcoke. Studies have been extended on the desulfurization of two petcoke samples. Interesting results were obtained by employing the techniques such as organorefining; that is, solvent extraction using N-methyl-2-pyrrolidone containing small amounts of ethylenediamine, morpholine, ethylenediamine, and other solvents. Acids and alkalis were also used for the desulfurization of petcoke. Biodesulfurization using Pantoea agglomerans D23W3 and Acidithiobacillus ferrooxidans showed interesting results. The present work also resulted in the development of some integrated processes of desulfurization of petcoke.
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