Mitigating the inhibition of organic matter to mainstream anammox system via electrolytic-enhanced strategy: Efficacy and underlying mechanisms.

Abstract

The organic matter poses a considerable challenge to the stability and broad-scale application of anaerobic ammonium oxidation (anammox) process in mainstream wastewater treatment. In this study, an electrolytic-enhanced anammox biofilm reactor (E-ABR) was developed to fortify the resilience of anammox system against inhibition of organic matter. E-ABR demonstrated superior nutrient removal when treating domestic wastewater, achieving a total nitrogen and phosphate removal efficiencies of 83.80 ± 3.70% and 94.17 ± 7.23%, respectively. Transmission electron microscopy and cell damage detection revealed extensive membrane rupture and intracellular enzyme leakage in ABR. Conversely, the anammox bacteria-denitrifier symbiotic community established under electrolytic conditions could effectively resist the invasion of excessive heterotrophic bacteria under organic shock loads. The electron transfer (ETSA activity increased by 32.26%) and energy synthesis (ATP synthase content increased by 182.37%) were marked enhanced in E-ABR than that of control reactor (ABR). These benefits enabled the maintenance of an NH4+-N removal efficiency of 82.11% in E-ABR, in stark contrast to the mere 44.46% observed in ABR with an influent C/N ratio of 3.0. This study enhanced the theoretical understanding of the mechanisms underlying resistance to organic inhibition within electrochemical bioaugmented anammox systems, thereby offering novel theoretical underpinnings for the application of anammox in mainstream wastewater treatment.