The Process and Water Quality Specialists
Membrane filtration (MF) can be used to provide effective solids-liquid separation and have small enough pore sizes to exclude many particulates, bacteria, and cysts of concern in water and wastewater treatment. The MF effluent contains very low levels of bacteria, suspended solids and significantly reduced turbidity because membranes provide a positive barrier against colloidal and microbial material by physically straining out the solids.
Membrane filtration has been conventionally categorized into microfiltration and ultrafiltration membranes. Microfiltration membranes have the largest pore size (0.1 - 3 micron) of all membrane types, require low transmembrane pressure (1- 30 psi), and are used for turbidity reduction, removal of suspended solids, parasites (e.g. giardia and cryptosporidium) and bacteria. Ultrafiltration (UF) membranes provide all the same benefits as a microfiltration membrane, but also provide some virus removal. For drinking water in California, the Department of Public Health provides 1-log virus removal for UF membranes and any additional credit must be demonstrated. Membrane filtration technologies are all capable of achieving significant cryptosporidium and Giardia log removal values (LRV), but this must be demonstrated with continuous indirect integrity monitoring and daily direct monitoring