Filtration methods are techniques used to separate solids from liquids or gases by passing the mixture through a filter. Common types include mechanical filtration, where a physical barrier captures particles, and membrane filtration, which uses a semi-permeable membrane to allow certain substances to pass while blocking others. These methods are widely used in various industries, including water treatment to purify drinking water and air filtration systems to remove pollutants. Each method is chosen based on the specific requirements of the process, such as the size of particles to be removed and the desired purity of the final product.