noun
: a watertight bed filled with coke or other coarse material and used for purifying sewage which after being run into the bed and left for some hours in contact with the material to promote bacterial action is filtered off and the bed aerated
noun
: a watertight bed filled with coke or other coarse material and used for purifying sewage which after being run into the bed and left for some hours in contact with the material to promote bacterial action is filtered off and the bed aerated
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012