Microbial presence and potential in eastern oil shale

Abstract Samples of Indiana New Albany oil shale have been examined for their content of microorganisms and for the potential of using isolates to reduce the sulfur content prior to fluidized bed hydroretorting. Shale samples have been used as inocula for culture development. Standard microbial culture methods revealed the presence of 1 × 10 5 to 1 × 10 6 microorganisms/gram of shale. The organisms found appeared to be primarily a mixture of unidentified Gram-positive bacteria and several fungi. An electron microscope procedure was developed to quantitatively examine microparticulates and to obtain their X-ray spectra. Pieces of shale several hundred grams in weight were ground in a ball mill or by mortar and pestle and wet or dry sieved into three fractions designated +200, −200 and −325, based on the mesh size of the sieve used. Equal weight samples of the ground-sieved shale were taken up in distilled, demineralized water and passed through a 0.45 μM nitrocellulose filter. The dried filters were softened, coated with a thin layer of carbon, dissolved and recoated with carbon to prepare a carbon film sandwich which entraps microparticulates and is suitable for examination in the TEM. Results of the direct TEM examination of shale indicated that the ground material contained about 1 × 10 9 to 1 × 10 10 microbial cells/gram of shale in a surprising variety of sizes and shapes. Examination of X-ray spectra from individual microparticulates was inconclusive but suggested variability in particulate content. Quantitative X-ray analysis of bulk sieved samples was also performed. Shale, used as a growth medium supplemented with glucose but limited in sulfur, was inoculated with shale isolates. Reduction in sulfur content was measured quantitatively using the X-ray spectrometer. Results suggest that about 63–65% of the total sulfur could be removed when you include a pretreatment with HNO 3 acid.