Which method is NOT commonly used for treating liquid radioactive waste?

The method of treating liquid radioactive waste that is not commonly used is landfill disposal. Liquid radioactive waste requires careful handling and treatment to ensure it does not pose a risk to human health or the environment.

Solidification, ion exchange, and evaporation are established methods for managing such waste. Solidification involves converting the liquid waste into a solid form, making it safer for storage and reducing the potential for dispersion into the environment. Ion exchange is a method that removes radioactive contaminants from the liquid waste by passing it through a medium that attracts and captures ions selectively. Evaporation concentrates the waste, allowing for easier handling and later processing.

Using landfills for liquid radioactive waste is not a viable method. Landfills are designed to contain solid waste and may not adequately prevent the contamination of groundwater or surrounding ecosystems if used for liquid waste, particularly hazardous materials. Therefore, the landfill method is not appropriate in the context of liquid radioactive waste treatment.