Ozone treatment comes out on top in tap tests

Scientists comparing the effectiveness of water treatment techniques in removing drugs, hormones and residues from cosmetics from the domestic supply believe ozone beats chlorination and UV processes.

The study conducted by a team of American scientists from academia and industry concludes that ozone treatment is the best bet for removing key endocrine disruptors such as testosterone and oestrogen.

In tests simulating conditions in water treatment plants the team contaminated water with 31 harmful chemicals frequently found in the domestic supply.

The ozone treatment reduced 26 of them to at least 30% of their original concentration and was particularly effective against the so-called gender bending chemicals as well as caffeine and the infamous mosquito repellent DEET.

Its most notable failure was an inability to significantly reduce levels of flame retardant TCEP.

Chlorine treatment, by comparison, left a concentration of 70% or more of 15 of the chemicals.

It was also ineffective against TCEP and did little to reduce levels of many of the other substances including caffeine, testosterone or progesterone.

UV treatment proved to be even more of a disappointment, with the scientists claiming it was not particularly effective against any of the pharmaceuticals, hormones or cosmetics residues in doses commonly used in water treatment plants.

But the study fell short of giving ozone its whole-hearted endorsement, recognising treatment with the chemical is not without its own set of problems.

Like chlorination, ozone creates byproducts which can be harmful such as bromate in water with high bromide levels.

UV treatment does not create these problems.

By Sam Bond

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