Membrane filters or "membranes" are polymer films with specific pore ratings. MCE Membranes retain particles and microorganisms that exceed their pore ratings by acting as a physical barrier and capturing such particles on the surface of the membrane. MCE membranes are available in a variety of polymers, pore sizes, diameters, and surface types. Most membranes can be sterilized by autoclaving. MCE gridded membranes are designed for the recovery and retention of bacteria in microbiological analysis applications. White gridded disks are designed for the recovery and retention of E. Coli bacteria in water/wastewater analysis as well as other microbiological tests. The filters are certified to meet specifications listed in APHA Standard Methods.