Carbon dioxide kills viruses, bacteria in water

A new low-cost way to treat waste water and kill ­viruses and bacteria harnesses the power of carbon dioxide.

The big advantage of the system, developed by scientists at University of NSW and ANU, is it does not require expensive membranes, high temperatures or pressures, making it low-cost.

A new low-cost way to treat waste water and for the first time kill ­viruses and bacteria including E-coli harnesses the power of an unlikely ally — carbon dioxide.

Results of the breakthrough research, published today in ­Nature, could have huge impli­cations for some of the world’s most pressing environmental problems. It has the potential to remove billions of plastic bottles from the global waste stream and tackle deadly health outbreaks including Ebola in Africa.

The secret to the method is humble bubbles and it can be as simple as hooking the exhaust of a diesel motor to a low-tech treatment plant.

The big advantage of the system, developed by scientists at University of NSW and ANU, is it does not require expensive membranes, high temperatures or pressures, making it low-cost.

Co-author and 2016 winner of the Matthew Flinders medal of Australian Academy Sciences Barry Ninham said research had found CO2 killed viruses and was nature’s protection against ­infection. He said the big problem with all previous methods of water treatment had been that while one could deal with bacteria, it was impossible to deal with viruses or drugs.

He said the new water treatment method, which had been proved successful in treating water from a piggery, was part of a suite of research that included new low-cost forms of desalin­ation and for removing heavy metals such as arsenic, lead, mercury and radioactive waste.

“The work is the culmination of 40 years of pure undirected curiosity-driven research,” Professor Ninham said.

The paper in Nature said the availability of clean water was a major problem facing the world.

“In particular, the cost and destruction caused by viruses in water remains an unresolved challenge and poses a major limitation on the use of recycled water,” it said. “Here, we develop an environmentally friendly technology for sterilising water.

“The technology bubbles heated unpressurised carbon dioxide or exhaust gases through wastewater in a bubble column, effectively destroying both bacteria and viruses. The process is extremely cost-effective, with no concerning by-products.”

An editorial in Nature said the team led by Richard Pashley demonstrated a CO2 bubbling process for water sterilisation that didn’t require the CO2 to be pressurised.