AWWA B112-15 pdf download.Microfiltration and Ultrafiltration Membrane Systems
30. Membrane: An engineered material designed to remove solids (dis- solved or suspended) that are rejected from the system as either BW or a concen- trate stream, and that produces a stream containing less solute or particles (the product or fltrate stream). Membrane types in pressure-driven standards include low-pressure membranes such as MF and UF, as well as higher-pressure mem- branes such as NF and RO. Other defnitions are more restrictive including the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR), which defnes membrane fltration as “a pressure- or vacuum-driven separation process in which particulate matter larger than 1 micron is rejected by a nonfbrous engi- neered barrier.”
31. Microfltration (MF): Membrane fltration process with pore diameter nominally 0.1 to 0.5 µm that provides at least 3-log removal of Giardia cysts, Cryptosporidium oocysts, or similar-sized 3-µm and larger materials or surrogate materials based on challenge testing in accordance with the USEPA Membrane Filtration Guidance Manual.
32. Module: Te smallest component of a membrane unit in which a spe- cifc membrane surface area is housed in a device with a feedwater inlet, fltrate, and concentrate or BW outlet structure.
33. Molecular weight cutof (MWCO): Te rating of a membrane based on the size of uncharged solutes it will reject. Also referred to as nominal molecular weight cutof (NMWCO). Typically expressed in daltons.
34. Nanofltration (NF): Membrane fltration process that removes dis- solved constituents from water—such as dissolved organics, color, calcium and magnesium (hardness) ions, and other ions. NF membrane elements provide a nominal organic molecular weight cutof in the range of about 200 to >500 daltons and sodium chloride rejection of 0 to 95 percent. NF is similar to RO with the key diference being that NF has lower sodium chloride rejection than RO and it exhibits more selectivity in the types of ions that are removed such that NF allows a comparatively higher percentage of monovalent ions to pass to the permeate than multivalent ions.AWWA B112-15 pdf download.