Autotrophic Fe-Driven Biological Nitrogen Removal Technologies for Sustainable Wastewater Treatment

Abstract

Fe-driven biological nitrogen removal (FeBNR) has become one of the main technologies in water pollution remediation due to its economy, safety and mild reaction conditions. This paper systematically summarizes abiotic and biotic reactions in the Fe and N cycles, including nitrate/nitrite-dependent anaerobic Fe(II) oxidation (NDAFO) and anaerobic ammonium oxidation coupled with Fe(III) reduction (Feammox). The biodiversity of iron-oxidizing microorganisms for nitrate/nitrite reduction and iron-reducing microorganisms for ammonium oxidation are reviewed. The effects of environmental factors, e.g., pH, redox potential, Fe species, extracellular electron shuttles and natural organic matter, on the FeBNR reaction rate are analyzed. Current application advances in natural and artificial wastewater treatment are introduced with some typical experimental and application cases. Autotrophic FeBNR can treat low-C/N wastewater and greatly benefit the sustainable development of environmentally friendly biotechnologies for advanced nitrogen control.

Coupling Iron Sludge Addition and Intermittent Aeration for Achieving Simultaneous Methanogenesis, Feammox, and Denitrification in a Single Reactor Treating Fish Sludge

“…In this study, the DO concentrations in all reactors were not higher than 0.2 mg/L, the pH levels were maintained at 6.7–7.6, and the TCOD levels were 15–80 times higher than the inhibitory threshold for Anammox bacteria, which were not suitable for the growth of nitrifying bacteria, ammonia-oxidizing archaea, or Anammox bacteria. Currently, the investigation on Feammox-related microbes is still in the infancy, but studies have suggested that IRBs (e.g., Longilinea, Bacteroides, Deltaproteobacteria, Acidobacteria, and Anaerolinea) are the primary functional bacteria mediating Feammox. ,, The relative abundances of IRBs are shown in Figure c. As shown, the total abundance of IRBs increased by 5.0–9.4% in the four Fe­(III)-supplemented reactors when compared with the control group, confirming that the addition of iron sludge could enrich the IRBs, and this was in agreement with the increased organic and NH 4 + -N removal efficiencies.…”

“…Currently, the investigation on Feammox-related microbes is still in the infancy, but studies have suggested that IRBs (e.g., Longilinea, Bacteroides, Deltaproteobacteria, Acidobacteria, and Anaerolinea) are the primary functional bacteria mediating Feammox. 11, 17,41 The relative abundances of IRBs are shown in Figure 5c. As shown, the total abundance of IRBs increased by 5.0−9.4% in the four Fe(III)-supplemented reactors when compared with the control group, confirming that the addition of iron sludge could enrich the IRBs, and this was in agreement with the increased organic and NH 4 + -N removal efficiencies.…”

Thauera sp. in Hydrogen-Based Denitrification: Effects of Plentiful Bicarbonate Supplementation on Powerful Nitrite Reducer

“…Autotrophic denitrification is an alternative process for the abatement of NO 3 − and NO 2 − contaminated water [1][2][3]. It can overcome the high sludge formation problem requiring post-treatment in heterotrophic denitrification since autotrophic denitrification provides lower sludge yields [4,5].…”

“…It can overcome the high sludge formation problem requiring post-treatment in heterotrophic denitrification since autotrophic denitrification provides lower sludge yields [4,5]. Additionally, several non-toxic inorganic elements can be used as an electron donor for autotrophs, such as ferrous iron, sulphur and H 2 gas, which could lead the denitrification system to a satisfactory performance [1][2][3]. Since H 2 can be considered as an environmentally friendly substance due to its non-toxicity and non-harmfulness [6,7], using H 2 gas is a favorable option as it provides decent efficiency compared to other known electron donors for the autotrophic denitrification system [8].…”