You may not have realised it, but you have probably swum in a pool where the water is kept safe with ozone rather than chlorine. Now, under plans by one of England’s biggest water companies, the rivers of Leamington Spa and beyond may be kept clean with the gas, paving the way for designated bathing areas.
Walking alongside the Leam river through the Pump Room Gardens of the spa town, Wilfred Denga says ozone offers a “window into the future” for how we go even further to cleaning up our waterways.
Huge strides have already been taken through the existing three stages of treatment at sewage works. In particular, upgrades at sewage plants in the noughties drove down phosphorus concentrations in rivers. In the Thames they fell by 85 per cent between 1998 and 2010. Ozone — best known for absorbing the sun’s ultraviolet radiation high up in the Earth’s atmosphere — could be the next big step.
“The idea with the ozone technology is it is an additional treatment process at the end of our normal sewage treatment works. Existing processes take out nutrients and pathogens. But the final effluent is not bacteria-free, and does have some nutrients,” said Denga, bathing rivers lead at Severn Trent, which covers a region from Scunthorpe in the north to Gloucester in the south.
The company will install ozone treatment equipment at three sewage treatment works, at Frankton and Itchen Bank in Warwickshire and Ludlow. Designs are being finalised, and contractors are expected to be appointed this autumn to begin construction. It would mark the first time the technology has been deployed at a sewage plant in the UK.
Advertisement
“The ozone technology will further act on the bacteria. It creates a step change in bacterial levels. If we’re saying people might potentially be swimming downstream of these works, this helps with that public health aspect of it,” Deng said. Ozone is produced at the treatment works and dissolved in water to destroy bacteria including E. Coli.
Unlike other technologies such as ultraviolet treatment, it could also be used to act on pharmaceutical pollution reaching rivers via human waste and when medicines are poured down sinks. It could also potentially help to tackle the spread of superbugs, the antibiotic-resistant bacteria that have been found in rivers near pig and chicken farms.
The downside to ozone, which has the chemical formula O3 and is much less stable than O2, is its cost and high energy consumption. “It means more energy, more maintenance,” Denga said. He said society had to ask itself whether it wants to pay to tackle such pollution, and thinks there might be more appetite in the next regulated spending period for water firms, 2025 to 2030.
Severn Trent’s “green recovery” programme is spending £78 million to improve two stretches of river to a standard fit to swim in by 2025, on the Leam and Teme, Shropshire.
Infrastructure such as ozone technology will lower the pollution entering those rivers. But winning the official bathing designation that brings regular monitoring from May to September and peace of mind for swimmers, paddleboarders and other river users may prove harder.
Advertisement
At least seven applications for bathing water designation around England were rejected by the government this month, at sites along the Thames, Ribble, Deben, Tamar, Kent, Wharfe and Stour. Only four sites were given a green light, and are now being consulted on.
Communities and campaigners have been frustrated by the Department for Environment, Food and Rural Affairs not explaining why bids were turned down. Reasons can include not providing evidence of enough swimmers at a site, or a lack of lavatories and parking.
“We need much more transparency on the decision-making process for designation, clarity on the criteria which are being used to reject applications, and a much more proactive approach from Defra to support and encourage communities who are fighting to protect their rivers,” said Michelle Walker, technical director at the Rivers Trust charity.
The Times is calling on the government to make it easier for communities to apply for bathing water designation, and for many more than the two sites in England today.
“Why bathing rivers as a project? It’s because of engagement. Rather than just us, how do we work with everyone? This has to be farmers, about everyone else, and you can solve the problem,” Denga said.
Advertisement
The Times is demanding faster action to improve the country’s waterways. Find out more about the Clean It Up campaign.
