Current and aeration system for wastewater plant

Abstract

A defined current and aeration system for the aeration chamber of an aerobic wastewater treatment plant is disclosed. It includes the release of oxygenation gas or air into the aeration chamber through a diffuser or the like at a position such that the air injected into the tank provides the necessary amount of oxygen for aerobic bacterial digestion of the waste while creating a current or circulation pattern in the chamber that forces every portion of the fluid within the aeration chamber into circulation thus preventing the accumulation of solids as sludge in the wastewater treatment plant.

Description

BACKGROUND OF THE INVENTION[0001]This invention relates to an improved system for supplying air to the aeration chamber of an aerobic wastewater treatment plant.[0002]In remote areas, newly developed subdivisions, or other locations where a municipal sewer system is not available, small anaerobic or aerobic wastewater treatment plants are used to handle the wastewater produced. Septic tanks use anaerobic bacteria to convert the organic solid waste in the wastewater stream. Usually, however, most of the organic solids settle as sludge to the bottom of the septic tank and must be pumped out periodically.[0003]Aerobic wastewater treatment plants use “extended aeration” to efficiently encourage aerobic bacteria growth. Extended aeration includes contacting the wastewater with a large number of small bubbles of oxygen-carrying gas, thus maximizing the surface area for oxygen transfer. Air or oxygen is generally pumped into the tank through diffusers that break up the air into thousands o...

AI Technical Summary

Benefits of technology

[0018]The introduction of diffused oxygenation gas or air in a single location close to the substantially flat bottom and the cylindrical side wall of an aeration chamber produces a defined current or circulation pattern which generally maintains all solids in circulation and forces all fluid within a wastewater treatment plant into motion, overcoming dead spots created by interference patterns when two or more diffuser locations are used. The diffuser location close to the side wall and the bottom of the aeration chamber of the wastewater treatment plant forces a specific current or pattern of circulation which sweeps fluid from every portion of the plant such that solids will remain well mixed in solution instead of accumulating as sludge. This exposes all solids to efficient digestion by aerobic bacteria. In a preferred embodiment, an external oxygenation gas source supplies oxygenation gas, preferably air, through a flexible drop line or air line to the diffuser for release into the aeration chamber. The release of oxygenation gas at the diffuser location forces the defined current pattern in the tank while providing a sufficient supply of oxygen for the growth of the aerobic bacteria which digests the organic solid wastes. While the diffuser location can be a single location close to the side wall and near the bottom of the wastewater treatment plant, a preferred embodiment includes placing the diffuser close to the side wall and close to the bottom such that the difuser is substantially below the wastewater treatment plant inlet. When multiple air lines and diffusers must be used to provide sufficient quantities of oxygen, a preferred embodiment includes grouping all drop lines and diffusers in close proximity below the wastewater treatment plant inlet. Thus, the diffuser system, if comprised of multiple diffusers, is positioned such that the individual diffusers are in sufficiently close proximity to one another and adjacent the intersection of the side wall and the bottom wall such that the upwardly generated wastewater currents induce a branched current at the surface of the liquid in the aeration chamber, the branched current having a first run that moves in a first direction around the periphery of the aeration chamber and a second run that moves in the opposite direction around the periphery of the aeration chamber, the first and second runs meeting in an area generally diametrically opposite the inception of the branched current.

[0019]A preferred embodiment of the current invention includes the use of an aerobic wastewater treatment plant with an inverted truncated conical partition dividing the aeration chamber from the clarifier chamber. A preferred embodiment uses no deflector under the clarifier chamber. The diffuser forces a pattern of circulation which produces exposure to oxygen to all fluid in the aeration chamber as shown in FIG. 4 and minimizes the formation and depositing of sludge on the bottom of the plant.

Problems solved by technology

One problem associated with aerobic wastewater treatment plants is the failure of the flow of air in the aeration chamber to keep some of the solids from continuously settling to the bottom, where they build up a layer of sludge in the aeration and clarifier chamber, requiring periodic removal.

It is desirable that a minimum of sludge removal be required since, in addition to the high maintenance requirement, disposal of the sludge presents an ecological problem.

An accumulation of sludge within the unit further results in a deterioration of the wastewater treatment process because the high concentration of bacteria in the sludge rapidly consumes the available oxygen in the immediately surrounding water, whereupon, the bacteria begins to break down nitrogen compounds in the sludge to release bonded oxygen.

This results in a release of nitrogen gas, which rises to the surface producing scum and disrupting the bacterial conversion.

Wastewater treatment plants of all shapes suffer from an accumulation of sludge in the tank.

Dead spots may also occur with the use of diffusers in two or more locations due to the interference pattern produced in the circulation or currents by the diffusers.

It has been determined, that sludge tends to accumulate at the base of deflectors and, even worse, directly below the clarifier chamber.

When the sludge is below the clarifier chamber, the nitrogen bubbles up into the clarifier chamber producing scum and interfering with the operation of the clarifier.

While the use of diffusers in multiple locations necessarily creates the problem of circulatory dead spots where sludge accumulates, this problem is accentuated since air entering into multiple lines is not emitted evenly.

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