Importance

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Abstract

In the particular embodiments of the waste water treatment system described in the specification, a waste water treatment basin has spaced-apart, moving aerator chains extending across the basin in a direction transverse to the flow of waste water through the basin. When an aerator chain is provided with air, bottom aerators suspended from the chain adjacent to the bottom of the basin move with respect to the basin to mix sludge collected on the basin with the waste water and to supply air to the waste water. A control system supplies air selectively to the aerator chains to provide zones of full aeration and intermediate zones with little or no aeration and the selection of the aerator chains is changed periodically in a progressive manner along the basin so that the zones move progressively through the basin. As a result, sufficient air is supplied to the waste water in the basin for purification of the waste water and to maintain sludge in suspension as required in the waste water at minimum expense of energy. In addition, the oxygen potential of the waste water in the zones is controlled so that successive reactions relating to the purification process are accomplished in successive zones, for example, including nitrification of the waste water in zones having a relatively high oxygen potential and denitrification in adjacent zones having relatively low oxygen potential. Phosphorus removal is accomplished in a similar manner.

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First Claim