New insight into CO2-mediated denitrification process in H2-based membrane biofilm reactor: An experimental and modeling study

Nitrate Removal and Dynamics of Microbial Community of A Hydrogen-Based Membrane Biofilm Reactor at Diverse Nitrate Loadings and Distances from Hydrogen Supply End

“…According to a preceding reference [27], the biofilm depth (from the bulk liquid side) that the electron donor (H 2 ) could reach was negatively correlated with NO 3 − loading; thus the activity of the nitrite reductase in DNB that grew in the vicinity of the HFM side might suffer from the shortage of H 2 . Regarding the nitrous oxide reductase genes, the counts in phase I were found to be strikingly greater than those in phases II and III.…”

“…The start-up processes of the reactor were as follows: a relatively low influent NO 3 − concentration of 10 mg N/L was initially used to facilitate the start-up of the reactor, and the influent flowrate was set at 1 mL/min, resulting in a hydraulic retention time (HRT) of 10 h; once the complete removal of NO 3 − was achieved, the influent flowrate was increased to 2 mL/min, corresponding to an HRT of 5 h. Following experiments, in which the influent NO 3 − concentration was sequentially maintained at 10, 20, and 30 mg N/L in phases I, II and III, respectively, were carried out to investigate the effects of NO 3 − availability on the denitrification performance of the system and the dynamics of concentrations inside the biofilm were determined by a microsensor measuring unit, and the detailed analytical procedure can be found in our previous research [27]. NO 3 − removal flux of the system (J in g/(m 2 •d)) was calculated by Equation (1) [15,28].…”

“…Although the nitrite reductase genes were more enriched in phase III rather than phase II, a considerable amount of NO2 − was accumulated in the effluent in phase III (Figure 3). According to a preceding reference [27], the biofilm depth (from the bulk liquid side) that the electron donor (H2) could reach was negatively correlated with NO3 − loading; thus the activity of the nitrite reductase in DNB that grew in the vicinity of the HFM side might suffer from To figure out the nitrogen reductase involved in the nitrogen metabolism pathway, copy numbers of functional enzymes relating to the autotrophic denitrification process including nitrate, nitrite, nitric oxide, and nitrous oxide reductases were examined, as exhibited in Figure 7. The results regarding the counts of predictive functional genes encoding for nitrate reductase consisting of alpha subunit, beta subunit, gamma subunit, cytochrome, and electron transfer subunit are shown in Table 1.…”

Synchronous N and P Removal in Carbon-Coated Nanoscale Zerovalent Iron Autotrophic Denitrification─The Synergy of the Carbon Shell and P Removal

“…The measurement methods are described in Supporting Information Text S4. H 2 was analyzed using gas chromatography (Nexis GC-2030, Shimadzu, Japan) with a barrier discharge ionization detector (BID) . The functional gene prediction was achieved based on PICRUSt2 combined with the Kyoto Encyclopedia of Genes and Genomes (KEGG) database.…”

Simultaneous Partial Nitrification and Denitrification Maintained in Membrane Bioreactor for Nitrogen Removal and Hydrogen Autotrophic Denitrification for Further Treatment

“…Here, nitrate and nitrite diffuse from water into biofilm being reduced [14,15]. The advantages of this hydrogenotrophic denitrification compared with conventional heterotrophic denitrification technology include the utilization of nontoxic and inexpensive H 2 as electron donors, no requirement for the addition of external organic carbon, a small footprint, relatively low cost, and low production of biological sludge [16,17]. Promising outcomes have been reported with MBfR for treating nitrate-and nitrite-contaminated water for research and commercial applications.…”