This invention relates to covered tank structures generally. More specifically the invention is concerned with the withdrawal of noxious and/or odorous gases from a substantially sealed tank structure, as in many sewage treatment plants wherein such gases must be removed.
In many sewage treatment plants, the tanks in which sewage is stored or treated are subject to requirements that the tanks be substantially sealed against escape of noxious or odorous gases to the outside atmosphere. Such substantially closed tanks must be vented, with a slight negative pressure maintained inside, and this requires a system of venting conduits which are connected to an air pump or withdrawal device at a remote location, for pulling the noxious/odorous (and sometimes flammable) gases from above the surface of the liquid in the tank.
In the present invention described below, a portion of such gas withdrawal equipment is integrated with structural members of a tank cover of a particular design.