in sewage, suspended solids that will settle when the sewage is brought to a quiet state for a reasonable length of time, usually two hours. silicate

reverse seepage of water in a distribution system. backwashing

a water right which was not put to beneficial use for a number of years, generally five to seven years. abandoned well

a process in which one substance permeates another; a fluid permeates or is dissolved by a liquid or solid. activated carbon

a variety of argillaceous silicates with similar behavior under certain conditions, but modified in several ways to obtain the desired properties. adhesion

the adhesion of a substance to the surface of a solid or liquid. Adsorption is often used to extract pollutants by causing them to be attached to such adsorbents as activated carbon or silica gel. aeration

soils which are predominantly clay or abounding in clays or claylike materials. air sparging

the measurement of constituents in a water supply which determine alkaline conditions. The alkalinity of water is a measure of its capacity to neutralize acids. See pH. alumina

members of any of the groups of the silicates of aluminum which have the same chemical makeup but with distinct characteristics in terms of refractory/flux and crystalline geometry owing to how each chain their elements’ atoms. amines

a dense, shiny coal that has a high carbon content and little volatile matter and burns with a clean flame. Also called hard coal. attapulgite