Functional Interrelationships of Microorganisms in Iron-Based Anaerobic Wastewater Treatment

Abstract

This study explicated the functional activities of microorganisms and their interrelationships under four previously reported iron reducing conditions to identify critical factors that governed the performance of these novel iron-dosed anaerobic biological wastewater treatment processes. Various iron-reducing bacteria (FeRB) and sulfate reducing bacteria (SRB) were identified as the predominant species that concurrently facilitated organics oxidation and the main contributors to removal of organics. The high organic contents of wastewater provided sufficient electron donors for active growth of both FeRB and SRB. In addition to the organic content, Fe (III) and sulfate concentrations (expressed by Fe/S ratio) were found to play a significant role in regulating the microbial abundance and functional activities. Various fermentative bacteria contributed to this FeRB-SRB synergy by fermenting larger organic compounds to smaller compounds, which were subsequently used by FeRB and SRB. Feammox (ferric reduction coupled to ammonium oxidation) bacterium was identified in the bioreactor fed with wastewater containing ammonium. Organic substrate level was a critical factor that regulated the competitive relationship between heterotrophic FeRB and Feammox bacteria. There were evidences that suggested a synergistic relationship between FeRB and nitrogen-fixing bacteria (NFB), where ferric iron and organics concentrations both promoted microbial activities of FeRB and NFB. A concept model was developed to illustrate the identified functional interrelationships and their governing factors for further development of the iron-based wastewater treatment systems.

Achieving Ammonium Removal Through Anammox-Derived Feammox With Low Demand of Fe(III)

“…However, A6 was not detected in the Feammox sludge obtained in this study. Most of the other studies reported that Feammox was positively related to the enrichment of IRB, for example, Geobacter (Zhou et al, 2016 ; Yang et al, 2018b ; Ahmed et al, 2021 ; Zhu et al, 2021 , 2022 ), Geothris (Ahmed et al, 2021 ), Pseudomonas (Li et al, 2019 ; Yang et al, 2019 ; Zhu et al, 2021 ), Desulfovibrio (Zhou et al, 2016 ), Desulfosporosinus (Yang et al, 2019 ), Desulfomicrobium (Yang et al, 2019 ), Dechloromonas (Yang et al, 2019 , 2021a ), and Clostridium (Yang et al, 2021a ). Based on these previous studies and typical clarification of IRB (Lovley et al, 2004 ), the bioreactor in this study enriched five IRB genera including Desulfovibrio, Thiobacillus, Desulfomicrobium, Geobater , and Desulfobacterota .…”

Effects of Elevated Fe (III) on Anaerobic Ammonia Oxidation Biofilm Process: Inhibition and Recovery

“…Ahmed et al observed that the presence of Fe (III) had a significant impact on the microbial population and functional capabilities. They also discovered a collaborative association between iron-reducing bacteria and nitrogen-fixing bacteria in a unique anaerobic biological treatment method for wastewater [31][32][33]. High Fe (III) doses were commonly detected in industrial wastewater.…”