Glossary of Terms - E
A B C D E F G H I J K L M N O P Q R S T U V W Z
E. Coli - The common abbreviation of Escherichia Coli.
eductor - A device utilizing a nozzle and throat, installed in a stream of water to create a partial vacuum to draw air or liquid into the stream; commonly used to draw regeneration chemicals into an ion exchange water treatment system, such a softener or deionizer.
effective size - A measure of the diameter of particles in a media bed or resin bed. Effective size is that mesh size which will permit 10 percent of the bedís particles to pass and will retain the remaining 90 percent.
efficiency - The ratio of output per unit input or the effectiveness of performance of a system; in an ion exchange system, often expressed as the amount of regenerant required to produce a unit of capacity, such as the pounds of salt per kilo-grains of hardness removal.
effluent - The stream emerging from a unit, system or process, such as the softened water from an ion exchange softener.
ejector - A device which used to disperse a chemical into a water being treated (See eductor).
electrodialysis - A dialysis process using semi-permeable membranes in which ions migrate through the membranes from a less concentrated to a more concentrated solution as a result of the ionsí attractions to a positive electrode (anode) and a negative electrode (cathode) created by direct electric current.
electrolysis - The decomposition of a material by an outside electrical current. (See galvanic corrosion.)
electrolyte - 1. A nonmetallic substance which can carry an electric current by movement of ions instead of electrons. 2. A substance which, when dissolved in water, separates into two or more ions which can carry an electric current. (See conductance, ionization.)
electron - A fundamental particle found in the atom which carries a single negative charge.
element - See cartridge.
elution - The stripping of ions from an ion exchange material by other ions, either because of greater affinity or because of much higher concentration.
endpoint - The point at which a process is stopped because a predetermined value of a measurable variable is reached.
equilibrium - The state in which the action of multiple forces produce a steady balance or seeming lack of change.
equilibrium reaction - A chemical reaction which proceeds primarily in one direction until the concentrations of reactants and products reach an equilibrium.
equivalent weight - The weight in grams of an element, compound or ion that yields (or per) one ionic valence charge (or one reactive proton).
erosion - The process in which material is worn away by a stream of air or liquid, often due to the presence of abrasive particles in the stream; a physical or mechanical wearing process rather than a chemical or electrochemical wearing away process.
Escherichia Coli (E. Coli) - One of the members of the coliform bacteria group normally found in human and animal intestines and indicative of fecal contamination when found in water. Determination of whether E. Coli is present is often used to measure the microbiological safety of drinking water supplies. (See fecal, coliform.)
exchange velocity - The rate with which one ion is displaced in favor of another in an ion exchanger.
exhaustion - The state of an ion exchanger or other adsorbent that is no longer capable of effective function due to the depletion of the initial supply of exchangeable ions. (See ion exchange, endpoint.)