What process involves adjusting the chemical state of waterborne contaminants?

The process that involves adjusting the chemical state of waterborne contaminants is oxidation. This method involves the addition of oxidizing agents to the water, which react with contaminants, changing their chemical structure and often rendering them less harmful or more easily removable. This process is commonly used in water treatment to break down organic materials, kill bacteria, and neutralize various pollutants.

In contrast, filtration physically removes particles and impurities from water but does not chemically alter them. Desalination primarily focuses on removing salt and other minerals from seawater to produce fresh water, primarily using processes like reverse osmosis. Ion exchange, on the other hand, is used to remove specific ions from the water by replacing them with other ions, but it does not fundamentally change the chemical state of the contaminants involved. Thus, oxidation is the correct answer as it specifically addresses the chemical transformation of contaminants.