The invention relates to apparatus for treating water by skimming, the apparatus comprising:

• a reaction chamber (8);
• injector means (4) for delivering the water for treatment via an injection orifice into the reaction chamber;
• means (20) for forming microbubbles of gas in the water to be treated; and
• condensation means (10) for collecting the resulting foam,
• the apparatus being characterized by the fact that the microbubbles are injected into the reaction chamber (8) together with the water for treatment.

The invention also provides a method of treating water by skimming, in which:

• the water for treatment is injected into a reaction chamber (8);
• microbubbles of gas are formed in the water for treatment; and
• the foam that is produced is separated from the water for treatment,

  the method being characterized by the fact that the microbubbles are injected into the reaction chamber (8) together with the water for treatment.