ABSTRACT
Storage and equalization facilities are used to precede treatment facilities to attenuate the flow to the facilities. There are two equalization techniques. The first is to treat flow and constituent equalization as separate issues. In this case, constituent equalization occurs in a constant volume device receiving relatively constant flow. The second approach treats combined flow and constituent equalization in terms of mass. Using a statistical technique similar to that used for constituent equalization from the first approach, the retention time requirements for mass equalization can be estimated. The hydraulic and constituent equalization volumes are additive, and are not the same volumes. Placement of the equalization tank after solids and floatable removal eliminates problems with solids and floatables in the tank. Equalization tanks are normally above ground, round, usually steel tanks. If the tank is used as a pre-aeration tank, then the aeration could make up part or all of the mixing requirement.
