Just under a year ago we reported on a method to clean polluted water and soil by infusing them with pressurized ozone gas microbubbles. The process was developed by Andy Hong at the University of Utah and has now moved out of the lab and is being put the test in a demonstration project in eastern China. If all goes to plan the process has the potential to boost a wide range of environmental cleanup efforts around the world.
The process, which Hong calls heightened ozonation treatment (or HOT), exposes pollutants and makes them easier to remove. Its uses include removing oil and gas byproducts from water, removing organics and heavy metals from industrial sites, and removing harmful algae from lakes.
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The China project has seen the University of Utah partner with Honde LLC, a large Chinese environmental cleanup company, and the Chinese government to remediate an industrial site on the shore of Lake Taihu. The large lake is located adjacent to Wuxi, a major Chinese industrial city west of Shanghai with a population of about 4.5 million. Lake Taihu is polluted by numerous contaminants as it receives runoff from across the region, which is dotted with polluted factory sites that results in nutrients collecting in the lake that feed harmful algae.
"The lake requires extensive environmental cleanup after years of neglect," Hong says. "We hope this restoration project will be the first among many to come for the area. We are fortunate that the Chinese government is aggressively cleaning up this area and willing to tackle challenging issues with new techniques that haven't been used anywhere else. This is a great opportunity for us and China."
The focus of the project, which began in September and is expected to last three months, is removing heavy metals and other contaminants from the soil. The centerpiece of the effort is a HOT reactor – a pressurized metal vessel that produces ozone microbubbles. The reactor is currently being used to treat soil, but it can also be used to treat water, algae or sewage waste.
The HOT reactor is placed on the site to be cleaned and filled with contaminated soil. Organic contaminants (hydrocarbons) are removed first by repeatedly pressurizing and depressurizing the reactor with ozone gas, creating microbubbles that degrade the hydrocarbons. Metal contaminants then are removed by adding a chelating agent to extract them, then adding lime to precipitate the contaminants so they can be filtered out and then disposed of.
"The clean soil will be used for tree planting on public lands, and the water is recycled and reused in subsequent batches of soil cleanup," Hong says.
If the demonstration is successful, Hong expects the project to be replicated at other sites for different types of contaminants around Lake Taihu. He also expects his new method to be applied in the United States and other countries across the world. To that end, in addition to Honde, the technology has been licensed by 7Revolutions Energy Technology Fund – an investment company based in Salt Lake City and a University of Utah startup – which has started a company to explore using the technology in North America and elsewhere.