Impacts of organics on the microbial ecology of wastewater anammox processes: Recent advances and meta-analysis.

• Autotrophs and heterotrophs in anammox systems are versatile in using organics. • Endogenous organics facilitate biofilm formation and cross-feeding interactions. • 19 core and 7 keystone taxa are identified based on 149 wastewater anammox samples. • Appropriate organics management is key to enhancing nitrogen removal by anammox. Anaerobic ammonium oxidation (anammox) represents a promising technology for wastewater nitrogen removal. Organics management is critical to achieving efficient and stable performance of anammox or integrated processes, e.g., denitratation-anammox. The aim of this systematic review is to synthesize the state-of-the-art knowledge on the multifaceted impacts of organics on wastewater anammox community structure and function. Both exogenous and endogenous organics are discussed with respect to their effects on the biofilm/granule structure and function, as well as the interactions between anammox bacteria (AnAOB) and a broad range of coexisting functional groups. A global core community consisting of 19 taxa is identified and a co-occurrence network is constructed by meta-analysis on the 16S rDNA sequences of 149 wastewater anammox samples. Correlations between core taxa, keystone taxa, and environmental factors, including COD, nitrogen loading rate (NLR) and C/N ratio are obtained. This review provides a holistic understanding of the microbial responses to different origins and types of organics in wastewater anammox reactors, which will facilitate the design and operation of more efficient anammox-based wastewater nitrogen removal process. Image, graphical abstract [ABSTRACT FROM AUTHOR]