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Secondary Treatment
Published in David H.F. Liu, Béla G. Lipták, Wastewater Treatment, 2020
Microorganisms using molecular oxygen as electron acceptors are called aerobes, while those using molecules other than oxygen for electron acceptors are called anaerobes. Facultative microorganisms can use oxygen or another chemical compound as electron acceptors. Facultative microorganisms can be divided into two subgroups based on metabolic abilities. True facultative anaerobes can switch from fermentative to aerobic respiratory metabolism depending on the presence of molecular oxygen. Aerotolerant anaerobes, however, have a strictly fermentative metabolism but are insensitive to the presence of molecular oxygen. Obligate aerobes cannot grow in the absence of molecular oxygen, and obligate anaerobes are poisoned by an oxygen presence.
Organic mass and nitrogen removal kinetic modeling in sequencing batch reactor
Published in Journal of Applied Water Engineering and Research, 2023
Estefanía Freytez, Adriana Márquez, María Pire, Edilberto Guevara, Sergio Pérez
In an aqueous medium in the absence of molecular oxygen such as the anaerobic and anoxic phases associated with SBR, some oxidized inorganic compounds (e.g. NO3- (Denitrification), NO2- (Denitrification), SO4−2 (Sulfate reduction), Carbon Dioxide (Methanogenesis) PO4−3 among others) could act as electron acceptors for certain anaerobic organisms of the facultative type. According to Metcalf & Eddy, the organisms that generate energy by fermentation and that can grow, both in the presence and the absence of molecular oxygen, are called facultative anaerobic organisms, and can be classified into two groups, according to their metabolic possibilities. Pure facultative anaerobic organisms can change from fermentative to respiratory metabolism, depending on the presence or absence of molecular oxygen. Aerotolerant anaerobic organisms have a strictly fermentative metabolism, but are relatively insensitive to the presence of molecular oxygen.