Fungus could cheaply desulfur crude oil

Researchers in Iran have identified a fungus that can remove sulfur from heavy crude oil in conditions slightly higher than room temperature.

The WS4 strain of the Stachybotrys fungus, which is found in “sick buildings” where water damage has caused mold growth, can selectively remove sulfur and nitrogen from heavy crude oil at 30 degrees Celsius (86 degrees Fahrenheit).

The work could lead to a simpler and cheaper method the oil industry could use to remove sulfur from crude oil to meet emissions standards that continue to drop worldwide.

The work was done by scientists at the Sharif University of Tehran as part of a project overseen by the Petroleum Engineering Development Company, a subsidiary of the state-owned National Iranian Oil Company.

The Iranian researchers tested the fungus using heavy crude oil obtained from two Persian Gulf oil fields. Their results, published in the Oct. 1 issue of Industrial & Engineering Chemistry Research, showed the WS4 strain removed 65 percent to 76 percent of the sulfur content within three-to-six days.

The stricter sulfur emissions standards have been imposed in part because of sulfur’s role in causing acid rain, which damages water ecosystems, crops and forests.

The standard sulfur removal process involves heating the crude oil by several hundred degrees and applying high atmospheric pressures to extract hydrogen sulfide gas that is later converted to sulfur.

Ultra-low sulfur diesel, for example, may not exceed 15 parts per million of sulfur, 97 percent less than regular diesel. Fuels classified “sulfur-free” have less than 10 parts per million of sulfur content.

Companies such as Sinclair Oil and ConocoPhillips (NYSE: COP) announced alliances last year that would enable them to sell ultra-low sulfur diesel (see Wyoming facility to make diesel with clean coal process  and ConocoPhillips and food processor Tyson partner for biofuels).