Produced water treatment

What are the different stratagiess for produced water treatment?On what basis the stratagies are executed?

For injection purposes; Target Formation lithology and compatibility defines the strategies for water treatment. It may include desalination, salination, filtration, descaling, degassing, skimming etc.
For disposal purposes: It depends how you are disposing either at surface or underground. For surface disposal, you will have to consider environmental constraints. However, for disposing underground, various other constraints will define the strategy.

Let me know which case you are concerned about.