Scientists find a way to take Valium out of recycled water
A breakthrough by the University of Johannesburg could make water-recycling safer
Cape Town’s Day Zero crisis has pushed water-recycling to the top of the agenda, and a University of Johannesburg breakthrough could make it safer.
Researchers headed by Professor Vinod Kumar Gupta, from the applied chemistry department, have invented a low-cost method to remove the anxiety drug diazepam from recycled water and wastewater.
Now a pilot plant is being planned at the university to manufacture the titanium dioxide nanofibres used in the technique.
“Later the pilot plant will be followed by a demonstration waste water treatment plant, to show how nanotechnology can remove a range of pharmaceutical impurities efficiently, rapidly and at low cost,” said Gupta.
Recycling would be vital in cities like Cape Town that were running out of water, he said. “For a city in a developing country, removing pharmaceuticals from waste water needs to happen in an efficient, cost-effective and speedy way.
“The treated water can then be added back in low volumes to the city’s water supply, as is already done in Orange County in California, Singapore and Perth.”
In December, scientists from the Western Cape’s top universities warned that desalinated sea water poses a probable health risk to Capetonians, partly because of the presence of pharmaceuticals in sewage discharged through three marine outfalls.“The full impact of chronic exposure to pharmaceuticals, antibiotics and cleaning products on the marine food chain and human health is not fully known, but their ubiquitous presence in trace levels in desalination intake water poses a potential risk to human health,” said a team led by Professor Leslie Petrik, of the environmental and nano-science group at the University of the Western Cape.
Writing in the South African Journal of Science, Petrik said pharmaceuticals found in seawater off Granger Bay included anti-inflammatories, antibiotics, epilepsy drugs, anti-retrovirals and paracetamol.
Gupta said prescription drugs like diazepam — better known as Valium — tended to slip through waste-water treatment plants, which were not designed to remove the thousands of different pharmaceuticals in use globally.
“Existing processes that can remove diazepam and other drugs at large scale from waste water are expensive, time-consuming, inefficient, or all three. Some also consume a lot of energy in multiple steps, or use toxic and hazardous compounds unfriendly to the environment,” he said.
“Also, diazepam is not easy to remove from waste water using traditional methods. It is partially soluble and has a small particle size. For efficient, targeted removal, advanced hybrid nanomaterials are needed.”
The researchers found that the presence and concentration of psychoactive drugs (such as diazepam) is roughly the same in treated waste water and untreated waste water. Lower-income countries are worse affected.
The titanium dioxide nanofibres developed at UJ remove diazepam and related drugs in a targeted way, and Gupta said they could be used as filters in municipal or industrial treatment plants.