The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 02, 1996
Filed:
Dec. 28, 1993
Glen T Daigger, Englewood, CO (US);
Joseph P Stephenson, Kitchener, CA;
Daniel A Nolasco, Hamilton, CA;
Dalton R Stafford, Lethbridge, CA;
Douglas M Kaupp, Lethbridge, CA;
CH2M Hill, Inc., Englewood, CO (US);
Abstract
The present invention relates to a process for treating wastewater utilizing a step feed return activated sludge process. The wastewater is directed via one or more step feed points through a mainstream process. The step feed point includes at least one aerobic zone and at least one anoxic zone, in repeating or alternating sequence. A portion of effluent from the one or more anoxic zones are fed through at least one anaerobic zone to which raw or pretreated wastewater is fed and returned to the upstream portion of the anoxic zone. Additionally, return activated sludge may be recycled to one or more of the anoxic zones.