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1. (WO2014191345) METHOD OF BIOLOGICAL WASTEWATER TREATMENT

Pub. No.:    WO/2014/191345    International Application No.:    PCT/EP2014/060809
Publication Date: Fri Dec 05 00:59:59 CET 2014 International Filing Date: Tue May 27 01:59:59 CEST 2014
IPC: C02F 3/12
C02F 3/30
Applicants: SLUSARCZYK, Jerzy
Inventors: SLUSARCZYK, Jerzy
Title: METHOD OF BIOLOGICAL WASTEWATER TREATMENT
Abstract:
A method of biological wastewater treatment, wherein a biological reactor comprising an anaerobic zone (B), an anoxic zone (A) and an aerobic zone (T), sequentially connected to each other, is used, wherein raw wastewater is brought to the anaerobic zone located at the beginning of the said zone sequence of the reactor, or in part or in its entirety to the zone preceding it, then, the wastewater is directed to the anoxic zone (A) and eventually to the aerobic zone (T), afterwards, in the process of internal recirculation, a part of the content of the aerobic zone (T) is returned to the anoxic zone (A), and the rest of the wastewater from the aerobic zone (T) is directed together with the sludge, directly or through additional zones, to a secondary settling tank where the treated wastewater is separated from the sludge which sediments on the bottom of the secondary settling tank, and the treated wastewater and excess sludge located on the bottom of the secondary settling tank are discharged outside the secondary settling tank, and the rest of the sludge accumulated in the secondary settling tank is recycled to the anaerobic zone (B) directly or via the anoxic zone (A) in the process of external recirculation. In this method, between the anoxic zone (A) and the aerobic zone (T), a medium-aerobic zone (S) is maintained, where residence time of wastewater is selected from 2.0 to 8.0 hours, and oxygen concentration is maintained in the range of 0.6 to 1.3 mg of 02/litre.