Enhancing integrated denitrifying anaerobic methane oxidation and Anammox processes for nitrogen and methane removal: A review

Abstract

The integration of denitrifying anaerobic methane oxidation (DAMO) and anaerobic ammonium oxidation (Anammox) simultaneously converts ammonium, methane, and oxidized nitrogen species (nitrite and nitrate) to harmless N₂ and CO₂. This integrated and complementary process achieves the nitrogen and carbon cycles in wastewater with the potential to be applied widely at full scale to realize energy-positive wastewater treatment plants (WWTPs). In this review, we summarize the collaborative and competitive interactions of DAMO–Anammox microorganisms and systematically evaluate the challenges for the full-scale application of integrated DAMO–Anammox for wastewater treatment, including their extremely slow growth rate, low metabolic activity, and limited nitrogen and methene removal rate. We examine comprehensively the critical role of bioreactor design (attached, suspended, and granular sludge systems) for biomass retention and substrate transfer. The paper also discussed strategies involving trace elements (Cu(II) and Fe(II)), Zero Valent Iron (ZVI), and External Electrostatic Fields (EEFs) to enhance the DAMO–Anammox microbial activities. Further review is provided on the addition of Humics, quinone-compound anthraquinone-2,6-disulfonate (AQDs), Fe(III), Mn(IV) as electron acceptors through extracellular electron transfer (EET) and couple with autotrophic denitrification (AuDen) (H₂S and Fe(II)) to accelerate nitrogen and methane removal. Finally, a conceptual design of innovative WWTPs based on the integrated DAMO–Anammox was proposed.

Graphical abstract

Keywords:

• Denitrifying anaerobic methane oxidation
• anaerobic ammonium oxidation
• interactions
• metabolic activity
• wastewater treatment

HANDLING EDITORS:

• Eakalak Khan and Lena Ma

Acknowledgment

Y. Chen would like to acknowledge the financial support from the China Scholarship Council and an International Postgraduate Tuition Award (IPTA) from University of Wollongong, Australia. The research is supported by the ARC Discovery project (DP190100385). All the pictures are drawn by using BioRender.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.