Civil engineering graduate student Zengquan Shu simulates the solar UV/chlorine treatment process.
Civil engineering graduate student Zengquan Shu simulates the solar UV/chlorine treatment process. (Photo Courtesy University of Alberta)

Researchers at the University of Alberta have shown that oil sands tailings can be cleaned up with a new technique that uses solar energy to accelerate the process.

Instead of using UV lamps as a light source to treat oil sands process affected water (OSPW) retained in tailings ponds, professors Mohamed Gamal El-Din and James Bolton found that using sunlight treats the wastewater just as efficiently and at a much lower cost.

Oil sands tailings ponds contain a mixture of suspended solids, salts and other dissolvable compounds like benzene, acids and hydrocarbons. Typically, it takes at least 20 years before these ponds can be reclaimed. The solar UV/chlorine treatment process developed by the University of Alberta team would make OSPW decontamination and detoxification immediate, the university said.

The sun's energy alone partially removes organic contaminants in the wastewater, but when sunlight reacts with chlorine (or bleach) added to the pond it produces hydroxyl radicals (powerful oxidative reagents) that remove the remaining toxins more efficiently. No residuals are left by the chlorine as the sunlight causes it to decompose.

Laboratory-scale tests showed that the solar UV/chlorine treatment process removed 75 to 84 percent of these toxins.

The development may also have wider applications, Gamal El-Din explained: "This alternative process not only addresses the need for managing these tailings ponds, but it may further be applied to treat municipal wastewater as well. Being a solar-driven process, the cost would be minimal compared to what's being used in the field now."