Ammonium and organic carbon co-removal under feammox-coupled-with-heterotrophy condition as an efficient approach for nitrogen treatment.

ABSTRACT: Nitrification is the rate limiting step in the nitrogen removal processes since nitrifiers have high oxygen demand, but poorly compete with aerobic heterotrophs. In a laboratory-scaled system, we investigated a process of ammonium oxidation under ferric-iron reducing condition (feammox) in the presence of organic carbon using influents with high NH₄⁺ and COD contents, and ferrihydrite as the only electron acceptor. Batch incubations testing influents with different NH₄⁺ and COD concentrations revealed that the [COD]/[NH₄⁺] ratio of 1.4 and the influent redox potential ranging from?-?20 to?+?20 mV led to the highest removal efficiencies, i.e. 98.3% for NH₄⁺ and 58.8% for COD. N₂ was detected as the only product of NH₄⁺ conversion, whereas NO₂^- and NO₃^- were not detected. While operating continuously with influent having a [COD]/[NH₄⁺] ratio of 1.4, the system efficiently removed NH₄⁺ (>?91%) and COD (>?54%) within 6 day retention time. Fluorescence in situ hybridization analyses using Cy3-labeled 16S rRNA oligonucleotide probes revealed that gamma-proteobacteria dominated in the microbial community attaching to the matrix bed of the system. The iron-reduction dependent NH₄⁺ and COD co-removal with a thorough conversion of NH₄⁺ to N₂ demonstrated in this study would be a novel approach for nitrogen treatment.

SUBMITTER: Le CP 

PROVIDER: S-EPMC7803747 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature