Abstract: Stimulation of Indigenous Microbes to Bioremediate Oil-Contaminated Soils

James R. Stewart, Deborah L. Williams, Kimberly D. Kriel, Greg A. Stewart, Robert C. Hulse

The purpose of this study was to determine the effectiveness of bioremediation of two oil-contaminated soils by stimulating indigenous oil-degrading microbes. The soil treatment consisted of tilling, liming, and fertilizing, and bioremediation was monitored by changes in the microbial populations (MPs) and by changes in total petroleum hydrocarbons (TPHs) in the soils. Location one was a 12 × 12 ft plot that had been repeatedly contaminated with pressure pump oil for eight years. After treatment, the MP increased 400-fold in three weeks and remained unchanged for six more weeks. The initial TPH was 18,500 ppm and it declined steadily to 3000 ppm by seven weeks. Location two was a rectangular plot roughly 20 × 500 ft on a hillside where about 50 bbl of crude oil had been spil ed. MPs and TPHs were made at the three sites: site 1, top of hill where spill occurred; site 2, midway of hill; site 3, about 22 ft below site 1. The initial MPs at the three sites increased a thousandfold in 10 weeks after treatment. The initial TPHs at the three sites ranged from 15,000-20,000 ppm and remained unchanged for 26 weeks. At week 30, the TPHs of sites 1 and 2 were less than 10,000 ppm; site 3 required an extra treatment and 12 more weeks before the TPH was below 10,000 ppm. At locations one and two, the decreases in TPHs were roughly inversely proportional to the increases in MPs. Bioremediation by stimulating indigenous microbes was effective and, in terms of materials and labor, efficient.

AAPG Search and Discovery Article #90983©1994 GCAGS and Gulf Coast SEPM 44th Annual Meeting, Austin, Texas, October 6-7, 1994