Which of the following methods is not commonly used for landfill leachate treatment?

Thermal methods are not commonly used for landfill leachate treatment due to several practical and economic considerations. Landfill leachate, which is a liquid that has percolated through solid waste and extracted soluble or suspended organic and inorganic matter, often contains a complex mixture of contaminants.

While biological, chemical, and physical methods are well-established and frequently employed for treating leachate, thermal methods can be less efficient and more costly. Thermal treatment typically involves heating leachate to high temperatures to achieve evaporation or incineration, processes that can require significant energy input and specialized equipment.

Biological methods leverage microorganisms to break down organic components, chemical methods usually involve the addition of reagents to facilitate reactions that remove contaminants, and physical methods often focus on filtration or sedimentation for solids removal. Each of these techniques can be tailored to address specific types of leachate composition more effectively than thermal approaches, which are typically reserved for more concentrated or hazardous waste streams where other methods are insufficient.

Thus, while thermal methods have their uses, their practicality for landfill leachate treatment is limited compared to the other options, making them a less common choice in standard landfill leachate management strategies.