AWWA B116-15 pdf download.Electrodialysis and Ion-Exchange Membrane Systems
24. Electrodeionization (EDI): A variant of ED in which diluate (and sometimes concentrate) solution compartments are flled with ion-exchange mate- rial to reduce the resistance to current fow and achieve improved salt removal. EDI systems are typically used for production of low-conductivity water.
25. Electrodialysis (ED): A demineralization process in which ions are transferred through ion-selective membranes by application of an electromotive force, voltage-driven direct electric current, from a less concentrated solution to a more concentrated solution. Note: ED is not a “membrane fltration” process because the demineralized (product) water does not pass through the membrane barrier. Related term: Electrodialysis reversal (EDR).
26. Electrodialysis metathesis (EDM): A type of ED process that utilizes repeating units of two distinct cell-pairs and four process streams (two concentrate streams and two diluate streams). Te two distinct cell-pairs may employ diferent types of anion or cation exchange membranes (e.g., monovalent selective mem- branes). Related term: Electrodialysis (ED).
27. Electrodialysis reversal (EDR): A type of ED process in which the polarities of the electrodes are periodically reversed to change the direction of ion movement for membrane scaling and fouling control. Related term: Electrodialysis (ED).
40. Membrane: An engineered material designed to remove solids (dis- solved or suspended) that are rejected from the system as either backwash or a concentrate stream, and that produces a stream containing less solute or particles (the product or fltrate stream). This standard focuses on treatment processes that employ IEMs, which selectively allow or restrict ionic transport. Membrane types in pressure-driven standards include low-pressure membranes such as MF and UF, as well as higher-pressure membranes such as nanofltration (NF) and reverse osmosis (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 engineered barrier.”
41. Membrane cleaning system: Tanks, fltration devices, pumps, and asso- ciated equipment and appurtenances that are periodically used to prepare and feed chemical solutions to the membrane element(s) to recover lost performance.AWWA B116-15 pdf download.