What is the principle of filtration?

The principle of filtration is the physical or mechanical separation of solid particles from a fluid (liquid or gas) by passing the mixture through a medium that retains the solids while allowing the fluid to pass through. This process relies on differences in particle size, where the filter medium has pores small enough to block larger particles but large enough to let the fluid flow. Filtration can occur through several mechanisms, including straining, where particles larger than the pore size are physically blocked; interception, where particles collide with and stick to filter fibers; and diffusion, where smaller particles move randomly and adhere to the filter media. In water treatment, filtration removes suspended solids, sediment, rust, and sometimes microorganisms, improving clarity and safety. Different types of filters, such as sand, carbon, ceramic, or membrane filters, are used depending on the size of particles to be removed and the desired purity level. The efficiency of filtration depends on factors like pore size, flow rate, and the nature of the contaminant, making it a fundamental process in industries ranging from healthcare to manufacturing.