Activated sludge wastewater treatment process
US4961854A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 30, 1988 |
| Grant date | Oct 9, 1990 |
| Priority date | — |
| Expiry date | Jun 30, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S210/906
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
Wastewater and recycled activated sludge are homogeneously mixed in a first aeration zone by injecting an oxygen-containing gas such as air into the lower portion of the zone under conditions which produce a complete mix reaction and sufficient oxygen is supplied to meet the biological oxygen demands of the mixed liquor. The gas is introduced, preferably by a plurality of fine bubble membrane diffusers, in the form of fine bubbles having a diameter less than about 4 mm. The bubbles provide both the mixing to keep solids in suspension and the oxygen required to maintain the overall dissolved oxygen content in the first aeration zone as close to 0 as possible. The mixed liquor is sequentially contacted with an oxygen-containing gas in second and third aeration zones under conditions which produce a complete mix reaction, preferably by fine bubble membrane diffusers, clarified and a portion of the settled sludge is recycled to the first aeration zone.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.