Bioremediation is a relatively new technology used to remediate contaminated soil that involves oil degrading microorganisms.
Adequate aeration is essential for oil degrading microorganisms to be active. Methods of promoting aeration are tillage, pumping
air into the soil, and adding btilking agents to increase porosity. More knowledge is needed regarding the interaction between
bulking agents and other technologies in enhancing aeration for bioremediation of oil-contaminated soil. An experiment was
undertaken using oil-contaminated soil from an oil production site in east Texas to evaluate different methods to promote
aeration. Each treatment contained 10% total petroleum hydrocarbons (TPH) on a dry weight basis. Treatments were bulking
agents (non-bulked control, chopped bermudagrass hay, sawdust, and vermiculite) and aeration (static, tillage, and forced
aeration). Treatments were arranged in a 4 x 3 factorial with three replications in a completely randomized design. Sawdust and
vermiculite were added at equal volumes with the contaminated soil and chopped bermudagrass hay at a ratio of 1 volume of
hay to 2 volumes of contaminated soil. Experimental units were 1001 barrels open at the top. The TPH content was determined
every 6 weeks during a 30 week period. During this time the TPH content decreased in all treatments. Bulked soils showed a
more rapid reduction in TPH compared to the non-bulked control. Tilling increased the rate and extent of remediation more
than soil receiving forced aeration or left static. The most rapid rate of remediation occurred during the first 12 weeks from the
tilled-hay treatment, where the TPH decreased 82%. The slowest remediation rate occurred in the non-bulked-static treatment
where the TPH content decreased 33% in 12 weeks. By week 30 the TPH content of the treatments ranged from 90% degraded
in the tilled-hay and tilled-vermiculite treatments to 77% degraded for the non-bulked-static treatment. Tillage and adding
bulking agents enhanced remediation of oil-contaminated soil.