Treatment of produced water

1. A method of treating produced water containing hydrocarbons, comprising:

introducing microbubbles of a lift gas consisting essentially of nitrogen gas into the produced water in a separation stage to float oil to a surface of the produced water;

removing a top layer of oil from the surface of the produced water;

introducing microbubbles of an oxidizing gas into the produced water in an aeration stage to oxidize contaminants selected from the group consisting of iron, metals, heavy metals, and BTEX;

introducing an ultra-violet light treated oxidizing agent into the produced water in an advanced oxidation stage to oxidize remaining contaminants.

2. The method of claim 1 , further comprising a step of filtering the produced water to remove precipitates at the end of at least one of the aeration stage or the advanced oxidization stage.

3. The method of claim 1 , wherein the lift gas diffused into the produced water in the oil separation stage consists solely of nitrogen.

4. The method of claim 1 , further comprising a step of injecting a pH-controlling substance into the aeration stage.

5. The method of claim 1 , further comprising a step of degassing the produced water at the end of the advanced oxidization stage.

6. The method of claim 1 , further comprising a step of using atmospheric oxygen as the oxidizing agent in the aeration stage.

7. The method of claim 1 , wherein introducing the ultra-violet light treated oxidizing agent comprises using ozone microbubbles.