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:
Jul. 03, 2001
Filed:
Mar. 02, 1999
Degremont, Rueil-Malmaison, FR;
Abstract
The invention is a biological process for purifying waste water in order to produce an effluent with a low content of carbon and of oxygenated nitrogen compounds. The process includes an initial step of mixing the waste water in a biological reactor with activated sludge to denitrify the resulting mixture. Then, air is introduced into the mixture to form an anoxic sludge thereby directly oxidizing carbon present in the anoxic sludge and removing carbon therefrom, simultaneous with the denitrification. The anoxic sludge is clarified to separate it from a denitrified intermediate effluent. The clarified anoxic sludge is recycled to the biological reactor. Then, intermediate effluent is nitrified to form a nitrified liquor and a portion of the nitrified liquor is recycled into the anoxic sludge that is present in the biological reactor, thereby subjecting the anoxic sludge to oxygen present in nitrified compounds and consequently further removing carbon from the anoxic sludge, simultaneous with the denitrification. The rate of removal of carbon is controlled as a function of the flow rate/pollution characteristics of the anoxic sludge while a redox potential of the anoxic sludge is continuously measured. A nitrate concentration of the intermediate effluent is continuously measured. There is an adjustment of an amount of air introduced into the anoxic sludge in accordance with the measured redox potential and measured nitrate concentration. A recycling flow rate of the nitrified liquor is adjusted in accordance with the measured redox potential and measured nitrate concentration. The remaining nitrified liquor is the final effluent.