What are advanced oxidation processes (AOPs) and what is their role in water treatment?

• A. They rely on distillation alone.
• B. They use reactive radicals to oxidize organics and remove trace contaminants.
• C. They are used to heat water.
• D. They add nutrients.

Answer: (B)

Advanced oxidation processes are about creating highly reactive radicals that oxidize organic pollutants in water. The key idea is that these radicals, especially hydroxyl radicals, attack and break down difficult organics and even remove trace contaminants that conventional treatment can miss. AOPs generate these radicals in situ by combining oxidants like ozone, hydrogen peroxide, UV light, or catalysts, so the pollutants are rapidly oxidized rather than simply filtered out. This approach can transform persistent pesticides, pharmaceuticals, taste and odor compounds, and other microcontaminants into smaller, less harmful molecules, sometimes fully mineralizing them to carbon dioxide and water.

Distillation relies on evaporation and condensation to separate substances, which is a physical process rather than oxidation. Heating water is an energy input method and doesn’t inherently oxidize organics. Adding nutrients is unrelated to contaminant removal and serves other purposes like promoting biological growth.