From Oil-Spill Soil to Fertile Ground

New methods for revitalizing oily soil were found by Rice University scientists who discovered that heating contaminated soils in the absence of oxygen is not only a fast remediation, but also saves energy.

"Our original goal was to speed the response to oil spills, but our aspiration was to turn contaminated soil into fertile soil," Pedro Alvarez, Rice environmental engineer and George R. Brown Professor and chair of Rice's Civil and Environmental Engineering Department, said in a statement.

The researchers used a process known as pyrolysis, which Alvarez explained is better for the environment than standard incineration techniques. He also stated that while off-shore oil spills get the most attention, 98% of spills occur on land. This amounts to more than 25,000 per year, which cost industries and governments worldwide more than $10 billion annually.

According to their study, published in the journal Environmental Science and Technology, Rice researchers were able to not only reduce the amount of petroleum hydrocarbons to well below regulatory standards, but to enhance the soil's fertility by pyrolyzing contaminated soil for three hours.

"We initially thought we could turn the hydrocarbons into biochar," Alvarez explained in a statement. "We turned out to be partly wrong: We didn't get biochar, but [we got] a carbonaceous material that we call char and resembles coke."

However the team was correct in assuming that by removing the soil's toxic pollutants and hydrophobicity--or water-repelling nature--so that plants could take in water from the soil, they would be able to enhance plant growth. They proved this by successfully growing lettuce in treated soil in the lab.

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