Glossary of Water and Wastewater Terms
A B C D E F G H I J K L M N O P Q R S T U V W Y Z5 random terms from our glossary
substrate
(1) The base on which an organism lives. The soil is the substrate of most seed plants; rocks, soil, water, or other plants or animals are substrates for other organisms. (2) Chemical used by an organism to support growth. The organic matter in wastewater is a substrate for the organisms in activated sludge.
odor threshold
The minimum odor of a gas or water sample that can just be detected after successive dilutions with odorless gas or water. Also called threshold odor.
hairline crack
A stress crack in a pipe; the crack looks like a piece of hair.
hexavalent chromium
Wastewaters bearing hexavalent chromium (Cr6+) are produced in chromium electroplating, chromium conversion coatings, etching with chromic acid, and in metal finishing operations carried out on chromium as a basis metal. Hexavalent chromium must be reduced to trivalent chromium (Cr3+) before chromium can be removed from metal wastestreams by hydroxide precipitation. Hexavalent chromium is highly toxic in comparison with trivalent chromium. Also see chrome plate, chromium, and trivalent chromium.
television monitor
The television set or kinescope where the picture is viewed on a closed-circuit system.
