Which of the following processes does not involve filtration?

The process of oxidation does not involve filtration. Oxidation is a chemical process where a substance loses electrons, often resulting in changes to its chemical composition. It is used in water treatment to break down contaminants or to change them into less harmful substances. This process typically relies on chemical reactions rather than physical separation of particles, which is the main characteristic of filtration.

In contrast, deionization, reverse osmosis, and activated carbon treatment all incorporate filtration methods. Deionization removes ions from the water through ion exchange, effectively filtering out specific charged particles. Reverse osmosis uses a semipermeable membrane to filter water, removing a wide range of impurities, including salts and larger molecules. Activated carbon treatment involves passing water through carbon media that adsorbs organic contaminants and some harmful chemicals, serving as a filtration process.

Understanding these distinctions highlights why oxidation stands apart from the other processes listed, reinforcing the concept that not all water treatment methods involve the physical removal of particles through filtration.