Breathing new life into oil-contaminated soil

Their work, which appears in the American Chemical Society journal Environmental Science and Technology, involves a process called pyrolysis, where contaminated soil is heated in the absence of oxygen. After three hours of pyrolysis, the amount of petroleum hydrocarbons in the soil had been reduced to well below the 0.1 per cent threshold outlined in US environmental regulations. The process also increased the soil’s fertility by transforming the remaining carbon into char.

“We initially thought we could turn the hydrocarbons into biochar,” said Pedro Alvarez, chair of Rice’s Civil and Environmental Engineering Department. “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.”

“But we were correct in thinking that by removing toxic pollutants and the hydrophobicity that repels water that plants need, and by retaining some of the carbon and perhaps some of the nutrients, we would enhance plant growth.”