Xylem trials AOP treatment system

Xylem’s Promix AOP system.
Xylem’s Promix AOP system.

UK water companies can now face large financial penalties if they do not reach these limits, the company says.

The eight-month trial, which was completed earlier this year in partnership with Anglian Water Innovations, involved the use of ozone oxidation, in combination with hydrogen peroxide, to create an advanced oxidation process (AOP).

The aim of the trial was to establish whether Xylem’s Promix AOP system can remove background and spiked levels of contaminants, such as metaldehyde and clopyralid, from surface water.

Carcinogen issues

In addition, the trial was tasked with assessing Promix’s ability to maintain bromate levels below 5 µg/l. When oxidised, bromide becomes bromate, which is a human carcinogen and a listed compound by the World Health Organisation and the US Environmental Protection Agency.

“The trial clearly demonstrated that when applying relatively high ozone doses in the range of 8-10mg/l provided reduction rates on metaldehyde of approximately 70-75%,” said Tony Swierk, Ozone sales manager at Xylem. “At similar dose rates, approximately 50% reduction of clopyralid was achieved. At dose ratios of 2.5:1 (H2O2/O3) bromate levels did not exceed 5µg/l at any stage.”