Water and Wastewater Terms Beginning A

A B C D E F G H I J K L M N O P Q R S T U V W Y Z

anaerobic digestion (AN-air-O-bick)

A treatment process in which wastewater solids and water (about 5 percent solids, 95 percent water) are placed in a large tank (the digester) where bacteria decompose the solids in the absence of dissolved oxygen (DO). At least 2 general groups of bacteria act in balance: saprophytic bacteria break down complex solids to volatile acids, the most common of which are acetic and propionic acids; and methane fermenters break down the acids to methane, carbon dioxide, and water.