Membrane filters are thin barriers made from various materials that allow certain substances to pass through while blocking others. They are commonly used in water purification, pharmaceuticals, and food processing to remove contaminants, bacteria, and particles from liquids. The size of the pores in the membrane determines what can pass through, making them effective for different filtration needs. These filters can be categorized based on their pore size, such as microfiltration, ultrafiltration, and nanofiltration. Each type serves specific applications, from removing larger particles to filtering out viruses. Membrane filters are essential tools in maintaining the quality and safety of products in various industries, including water treatment and biotechnology.