What type of process is membrane filtration classified under?

Membrane filtration is classified as a physical separation process because it operates based on physical mechanisms rather than chemical reactions or biological activities. In this process, a semi-permeable membrane is employed to separate particles from liquids or gases based on size, charge, or other physical characteristics. The driving force for this separation typically involves pressure or concentration gradients, allowing only certain molecules or particles to pass through the membrane while retaining others.

This process is distinct from chemical processes, which involve chemical changes or reactions affecting the substances, and from biological processes, where living organisms or their byproducts play a crucial role in treatment. Additionally, thermal processes involve significant temperature changes, which are not a factor in membrane filtration. Overall, the classification as a physical separation process underscores the nature of membrane filtration in wastewater treatment applications.