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[Display omitted] • Strain MFG10 exhibits excellent denitrification and manganese reduction abilities. • MnO 2 promoted the metabolism and induced extracellular secretion by MFG10. • SMP composition changed to improve degradability and redox activity. • The EET process was enhanced by the trapping-solubilizing MnO 2 mechanism of EPS. • Tryptophan-like proteins and PS become potential electron donor precursors. In this study, the manganese (Mn) reduction-coupled denitrification strategy of dissimilatory Mn reducing bacteria was insightfully investigated. Different parameters (MnO 2 level, pH, and temperature) were optimized by kinetic fitting to improve denitrification and Mn reduction effects. The 300 mg L−1 MnO 2 addition achieved 98.72% NO 3 –-N removal in 12 h, which was 54.62% higher than blank group without MnO 2. Scale-up studies showed that the metabolic activity of the bacteria was effectively enhanced by the addition of MnO 2. Besides the deepening of humification in the system, tryptophan-like protein and polysaccharide as potential electron donor precursors revealed remarkable contributions to the extracellular secretion-dependent denitrification process of DMRB. The effect of EPS on Mn reduction depends mainly on the capture of MnO 2 by the LB-EPS layer versus its dissolution in the TB-EPS layer. Ultimately, the EPS possess a dual effect of accelerated denitrification and Mn reduction efficiency due to the enhanced EET process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Modified loofah with rough porous structure exhibited great immobilization effect. • Maximum NO 3 –-N, Mn (II) and TC removal efficiency were 91.97, 71.25, and 57.39%. • Adsorption, oxidation and co-metabolism were responsible for TC removal. • Zoogloea sp. was regarded as dominant contributor in the operation of bioreactor. • Metagenome revealed the potential of reactor for NO 3 –-N, Mn(II), and TC removal. The remediation of multiple pollutants in water, for instance, nitrate, heavy metals, and antibiotics is urgent and necessary for the global water resources protection. Herein, a modified loofah bioreactor was designed for simultaneous denitrification, manganese (Mn) oxidation, and tetracycline (TC) removal. The maximum removal efficiencies of NO 3 –-N (91.97%), Mn(II) (71.25%), and TC (57.39%) were achieved at a hydraulic retention time (HRT) of 9 h, Mn(II) concentration of 20 mg L-1, and TC concentration of 1 mg L-1. SEM and XRD were carried out to characterize the bioprecipitation in the operation of bioreactor. TC addition affected the gaseous denitrification products, dissolved organic matter, as well as reduced the OTU in the bioreactor. The Zoogloea were regarded as the dominant species in the microbial community and played an essential role in the operation of bioreactor. Metagenomic analysis proved the great potential for denitrification, manganese oxidation, and antibiotic removal of loofah bioreactor. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new microbial immobilized carrier, PVA/SA@sponge cube was synthesized. • Immobilized bioreactor has the ability to simultaneously remove NO 3 −-N, Mn(II) and TC. • As an electron donor, Mn(II) was transformed into MnO 2 and MnCO 3 by microorganism. • Zoogloea was proved as the dominant contributor in reactor operation. The co-existence of nitrate, manganese (Mn), and antibiotics are of a wide concern. In this study, a denitrifying and manganese-oxidizing Zoogloea Q7 bacterium was immobilized using polyvinyl alcohol/sodium alginate with sponge cube (PVA/SA@sponge cube) in the reactor. The optimal operation parameters of the bioreactor were explored. Maximum nitrate, Mn(II), and tetracycline (TC) removal efficiencies of 93.00, 72.34, and 57.32% were achieved with HRT of 10 h, pH of 6.5, Mn(II) concentration of 20 mg L−1, and TC of 1 mg L−1, respectively. Fluorescence excitation-emission matrix (EEM) proved that the microorganism in the bioreactor was greatly active. Scanning electron microscope (SEM) images demonstrated that Zoogloea Q7 was commendably immobilized on the novel material. X-ray diffraction (XRD) analysis suggested that the bioprecipitate was mainly composed of MnO 2 and MnCO 3. Through high-throughput analysis, Zoogloea sp. Q7 was considered to be the dominant bacteria present in the bioreactor. [ABSTRACT FROM AUTHOR]