Denitrification driven by additional ferrous (Fe2+) and manganous (Mn2+) and removal mechanism of tetracycline and cadmium (Cd2+) by biogenic Fe–Mn oxides.

Zoogloea sp. MFQ7 achieved excellent denitrification of 91.71% at ferrous to manganous ratio (Fe/Mn) of 3:7, pH of 6.5, nitrate concentration of 25 mg L−1 and carbon to nitrogen ratio of 1.5. As the Fe/Mn ratio increasd, the efficiency of nitrate removal gradually decreased, indicating that strain MFQ7 had a higher affinity for Mn2+ than Fe2+. In situ generated biogenic Fe–Mn oxides (BFMO) contained many iron-manganese oxides (MnO 2 , Mn 3 O 4 , FeO(OH), Fe 2 O 3 , and Fe 3 O 4) as well as reactive functional groups, which play an significant part in tetracycline (TC) and cadmium (Cd2+) adsorption. The adsorption of TC and Cd2+ by BFMO can better fit the pseudo-second-order and Langmuir models. In addition, multiple characterization results of before and after adsorption indicated that the removal mechanism of BFMO on TC and Cd2+ was probably surface complexation adsorption and redox reactions. [Display omitted] • Strain MFQ7 exhibited excellent denitrification with ferrous and manganous. • Different ferrous to manganous ratios had a large effect on denitrification. • Bioprecipitation were mainly consist of MnO 2 , Mn 3 O 4 , FeO(OH), Fe 2 O 3 , and Fe 3 O 4. • The adsorption mechanism was probably surface complexation and redox reactions. [ABSTRACT FROM AUTHOR]