Aeration can remove contaminants through air stripping. Which listed…

Concept

Aeration is a gas–liquid mass-transfer process in which air and water are brought into close contact so that suitable dissolved substances can move between the two phases.

A contaminant transfers efficiently from water to air when its volatility and Henry’s-law behavior favor the gas phase.

Application

1. Air is dispersed through the water or passed counter-current to it, creating a large gas–liquid contact area.

2. Volatile organic compounds partition from the liquid phase into the moving air stream and are stripped from the water.

3. Persistence alone does not make a substance suitable for air stripping; treatment of persistent organics depends on each compound’s volatility and other physicochemical properties, while metals and inorganic ions require nonvolatile-species removal processes.

Cross-check and contrast

• Persistent Organic Pollutants: persistence describes resistance to degradation, not the volatility-based classification criterion used to select air stripping.

• Volatile Organic Compounds: appreciable vapor pressure enables transfer from water into air during aeration.

• Metals: aeration may oxidize dissolved species, but a subsequent precipitation and filtration step performs the actual separation.

• Inorganic ions: their charge and nonvolatile dissolved form call for precipitation, ion exchange, or membranes.

Therefore, aeration is efficiently used to remove Volatile Organic Compounds.