Combination of ozonation and photocatalysis for purification of aqueous effluents containing formic acid as probe pollutant and bromide ion

- Photocatalysis oxidizes organics and reduces hazardous bromate to innocuous bromide.
- Photocatalytic ozonation is more efficient than either photocatalysis or ozonation.
- Formation of bromate is inhibited by the presence of oxidizable organics.
- Photocatalytic ozonation followed by photocatalysis does not produce bromate ion.

The treatment by advanced oxidation processes (AOPs) of waters contaminated by organic pollutants and containing also innocuous bromide ions may generate bromate ions as a co-product. In the present work heterogeneous photocatalysis and ozonation have individually been applied and in combination (integrated process) to degrade the organic compounds in water containing also bromide anions. The results show that: i) the sole photocatalysis does not produce bromate ions and in the case of its presence, it is able to reduce bromate to innocuous bromide ions; ii) the integration of photocatalysis and ozonation synergistically enhances the oxidation capabilities; and iii) in the integrated process bromate ions are not produced as long as some oxidizable organics are present.

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