Enrichment of Denitrifying Bacterial Community Using Nitrite as an Electron Acceptor for Nitrogen Removal from Wastewater

Abstract

This work aimed to enrich a denitrifying bacterial community for economical denitrification via nitrite to provide the basic objects for enhancing nitrogen removal from wastewater. A sequencing batch reactor (SBR) with continuous nitrite and acetate feeding was operated by reasonably adjusting the supply rate based on the reaction rate, and at a temperature of 20 ± 2 °C, pH of 7.5 ± 0.2, and dissolved oxygen (DO) of 0 mg/L. The results revealed that the expected nitrite concentration can be achieved during the whole anoxic reaction period. The nitrite denitrification rate of nitrogen removal from synthetic wastewater gradually increased from approximately 10 mg/(L h) to 275.35 mg/(L h) over 12 days (the specific rate increased from 3.83 mg/(g h) to 51.80 mg/(g h)). Correspondingly, the chemical oxygen demand/nitrogen (COD/N) ratio of reaction decreased from 7.9 to 2.7. Both nitrite and nitrate can be used as electron acceptors for denitrification. The mechanism of this operational mode was determined via material balance analysis of substrates in a typical cycle. High-throughput sequencing showed that the main bacterial community was related to denitrification, which accounted for 84.26% in the cultivated sludge, and was significantly higher than the 2.16% in the seed sludge.

Temperature Sensitivity and Composition of Nitrate-Reducing Microbiomes from a Full-Scale Woodchip Bioreactor Treating Agricultural Drainage Water

“…Species of Flavobacterium are generally aerobic heterotrophs, many of which are psychrotolerant [ 62 ], but the genus also harbors aerobic and facultative anaerobic denitrifiers, thus demonstrating metabolic versatility [ 63 , 64 , 65 ]. The genus was also found in relatively high abundance in previous studies of denitrifiers from wastewater treatment facilities [ 66 ] and bioreactors [ 19 , 47 ]. The absence of Flavobacterium in our denitrifying enrichment cultures indicated the limitations of the enrichment approach, which was performed under anoxic conditions but apparently introduced selective pressures hampering competitive proliferation of Flavobacterium .…”

Metagenomic assessment of nitrate-contaminated mine wastewaters and optimization of complete denitrification by indigenous enriched bacteria

“…For instance, wastewater samples and treatment plants can serve as excellent sources of indigenous bacteria capable of bioremediation of contaminated wastewater (Correa-Galeote et al, 2013;Nascimento et al, 2018). In fact, several authors have successfully enriched NO 3 − -reducing bacteria from a wastewater treatment plant and used the enrichment cultures as inoculum for bioremediation research studies (Liu et al, 2016;Yao et al, 2020). The readily available NO 3 − and SO 4 2in the samples serve as terminal electron acceptors in the metabolic activities of large groups of nitrogen-and sulfur-metabolizing bacteria.…”

Development of Bio-Electrochemical Reactor for Groundwater Denitrification: Effect of Electric Current and Water Hardness

“…On the other hand, Flavobacterium (27.1%) and Brevifollis (14%) became more abundant in the BER-20. Flavabacterium was capable of using a nitrogenous compound for anaerobic respiration, with a high NO 2 -N denitrification rate of 275.35 mg/L-h and a high specific removal rate of 51.80 mg/g-h [30]. In addition, Flavabacterium was able to grow in an aeration condition (DO > 5 mg/L) [31].…”