Manganese-oxidizing Bacterium Research Articles

Mechanisms of manganese-tolerant Bacillus brevis MM2 mediated oxytetracycline biodegradation process

Addressing the environmental threat of oxytetracycline (OTC) contamination, this study harnesses the bioremediation capabilities of Bacillus brevis MM2, a manganese-oxidizing bacterium from acid mine drainage. We demonstrate the strain's exceptional efficiency in degrading OTC under high manganese conditions, with complete removal achieved within 24 h. The degradation is facilitated by the production of Bio-MnOx, utilizing their high redox potential and large specific surface area, which significantly enhance the adsorption and oxidation of OTC. Advanced characterization techniques, including X-ray diffraction, scanning electron microscopy, High Resolution-Transmission Electronic Microscope and X-ray photoelectron spectroscopy, provide a detailed analysis of the structural and functional properties of Bio-MnOx. The study also reveals the crucial role of Mn(III) intermediates and reactive oxygen species in the OTC degradation process, with quenching experiments validating their substantial impact on efficiency. Laccase activity, a key manganese-oxidizing enzyme, is assessed spectrophotometrically, further highlighting the enzymatic contribution to Mn(II) oxidation and OTC breakdown. This research contributes valuable insights and approaches for the targeted bioremediation of OTC-contaminated aquatic environments, offering a promising strategy for combating pollution from antibiotics and analogous compounds.

Biogenic Mn Oxide Generation and Mn(II) Removal by a Manganese Oxidizing Bacterium Bacillus sp. Strain M2.

Mn(II)-oxidizing bacteria (MOB) are widely distributed in natural environments and can convert soluble Mn(II) into insoluble Mn(III) and Mn(IV). The biogenic manganese oxides (BioMnOx) produced by MOB have been considered for remediating heavy metal pollution and degrading organic pollutants in an eco-friendly manner. In this study, a manganese-oxidizing bacterium was isolated from Mn-polluted rivulet sediment and identified as Bacillus sp. strain M2 by PCR, phylogenetic tree construction, transmission electron microscopy (TEM), and physiological and biochemical indices. Strain M2 grew well under Mn(II) stress. BioMnOx with nanosized irregular geometric shapes and loose structures generated by strain M2 were found on the surface of the bacterial cells. The content of Mn in the bacteria was as high as 5.36%. Approximately 71.24% and 47.52% of Mn(II) was oxidized to Mn(III/IV) in the cell and in the deposits, respectively, within 3 d of cultivation with Mn(II). Extracellular enzymes contributed to the Mn removal and oxidation. In conclusion, Bacillus sp. strain M2 has a high potential for use in the remediation of Mn-contaminated sites.

Surface reactivity of the iron and manganese-oxidizing bacterium Leptothrix cholodnii SP-6

Surfaces of prokaryotic cells play a significant role in the adsorption of metals from aqueous solution and the formation of authigenic minerals (Konhauser 2006). Although most studies focus on the cell wall, it is known that many bacteria synthesise an extracellular layer of polysaccharides and proteins, including what are known as sheaths. It has been shown that the cyanobacterium Calothrix sp. produces as sheath which is neutrally charged at circumneutral pH values, and it was hypothesized that such a sheath might allow the cyanobacterium to survive in geothermal settings with high silicification rates (Phoenix et al. 2002). Specifically, the dominance of hydroxyl sites on Calothrix’s sheath surface facilitates hydrogen bonding with aqueous silica species, inducing the precipitation of amorphous silica on the sheath and thus protecting the underlying cell (Phoenix et al. 2002). Leptothrix cholodnii is a sheathed, iron and manganese-oxidizing bacterium that frequently inhabits minerals seeps, where Fe2+ and Mn2+ discharge into oxygenated surface waters (Spring et al. 1996). As a result, the sheath becomes encrusted with Fe(III) and Mn(IV) oxyhydroxides while the underlying cells are protected from mineralization (Emerson and Ghiorse 1992, Emerson et al. 2010). However, unlike Calothrix, Leptothrix’s sheath composition suggests that it might behave differently at circumneutral pH (Emerson and Ghiorse 1993). To investigate the surface reactivity of Leptothrix's sheath and cell wall we analyzed isolated sheaths, sheathless cells, and intact filaments of L. cholodnii SP-6. We studied these components using potentiometric titration, zeta-potential, Cd-adsorption, and Fourier transform infrared (FTIR) spectroscopy to elucidate changes in surface charge between the cell wall and sheath. For the isolated sheaths and intact filaments, titration data were fit using a two-site protonation model, resulting in the following pKa values: 6.05 (±0.29) and 9.34 (±0.11); and 7.77 (±0.17) and 10.50 (±0.20), respectively. For the sheathless cells, the best fit was obtained by using a three-site protonation model, resulting in the following pKa values: 5.40 (±0.59), 8.11 (±1.64) and 10.73 (±0.45). Total proton-active site concentrations were lower in isolated sheaths compared to intact filaments. Additionally, at circumneutral pH, net negative charge was lower for sheathless cells compared to intact filaments and isolated sheaths (Fig. 1). This information agrees with the Cd adsorption behaviour found for the three materials (Fig. 2). Thus, our preliminary results suggest that Leptothrix’s sheath is less reactive than the intact filaments at circumneutral pH, leading us to hypothesize that the outermost layer would sequester relatively lower amounts of cations, including Mn2+, from solution and potentially would protect the underlaying cell from deleterious mineralization. In addition to that, the less reactive sheath’s surface would also contribute to cell attachment, which is important for a species commonly found in streams (Phoenix et al. 2002, Emerson et al. 2010).

The cryptic step in the biogeochemical tellurium (Te) cycle: Indirect elementary Te oxidation mediated by manganese-oxidizing bacteria Bacillus sp. FF-1

Tellurium (Te) is a rare element within the chalcogen group, and its biogeochemical cycle has been studied extensively. Tellurite (Te(IV)) is the most soluble Te species and is highly toxic to organisms. Chemical or biological Te(IV) reduction to elemental tellurium (Te0) is generally considered an effective detoxification route for Te(IV)-containing wastewater. This study unveils a previously unnoticed Te0 oxidation process mediated by the manganese-oxidizing bacterium Bacillus sp. FF-1. This bacterium, which exhibits both Mn(II)-oxidizing and Te(IV)-reducing abilities, can produce manganese oxides (BioMnOx) and Te0 (BioTe0) when exposed to Mn(II) and Te(IV), respectively. When 5 mM Mn(II) was added after incubating 0.1 mM or 1 mM Te(IV) with strain FF-1 for 16 h, BioTe0 was certainly re-oxidized to Te(IV) by BioMnOx. Chemogenic and exogenous biogenic Te0 can also be oxidized by BioMnOx, although at different rates. This study highlights a new transformation process of tellurium species mediated by manganese-oxidizing bacteria, revealing that the environmental fate and ecological risks of Te0 need to be re-evaluated.

Antimony(III) removal by biogenic manganese oxides formed by Pseudomonas aeruginosa PA-1: kinetics and mechanisms.

In this study, Pseudomonas aeruginosa PA-1, a manganese-oxidizing bacterium screened from the soil at a manganese mining area, was found to be tolerated to Sb(III) stress during the Mn(II) oxidation, and the generated biological manganese oxide (BMO) outperformed the identical type of Abiotic-MnOX in terms of oxidation and adsorption of Sb(III). Adsorption kinetics and isotherm experiments indicated that Sb(III) was primarily adsorbed through chemisorption and multilayer adsorption on BMO; the maximum adsorption capacity of BMO was 143.15mg·g-1. Removal kinetic studies showed that the Sb(III) removal efficiency by BMO was 72.38-95.71% after 15min, and it could be up to 96.32-98.31% after 480min. The removal procedure could be divided into two stages, fast (within 15min) and slow (15 ~ 480min), both of which exhibited first-order kinetic behavior. Dynamic fitting in two steps revealed that the removal speed correlated to the level of dissolved Sb(III) with low Sb(III) concentrations, but with the initial concentration being high, the removal speed rate was independent of dissolved Sb(III). During the whole process, the Sb(III) removal speed by BMO was also higher than that by the Abiotic-MnOX. Combining multiple spectroscopic techniques revealed that Sb(V) was generated through the Sb(III) oxidation by BMO and replacing surface metal hydroxyl groups to form the complex internal Mn-O(H)-Sb(V) or generating stable Mn(II)-antimonate precipitates on the surface. In addition, microbial metabolites, including tryptophan and humus, in BMO may be complex with Sb(III) and Sb(V) to achieve the treatment of Sb(III). This research investigates the factors and mechanisms influencing the adsorption and removal of Sb(III) by BMO, which could aid in its future engineering applications for the BMO.

Isolation and Identification of a Manganese-Oxidizing Bacterium from Produced Water: Growth and Manganese-Oxidation Ability of Bacillus zhangzhouensis in Different Manganese Concentrations

Isolation and Identification of a Manganese-Oxidizing Bacterium from Produced Water: Growth and Manganese-Oxidation Ability of Bacillus zhangzhouensis in Different Manganese Concentrations

Manganese removal and product characteristics of a marine manganese-oxidizing bacterium Bacillus sp. FF-1.

Biogenic manganese oxides (BioMnOx) have been found all over the world, and most of them were formed by Mn(II)-oxidizing bacteria (MnOB). In this study, a MnOB designated as FF-1 was isolated from marine surface sediments in the Bohai Sea, China. This strain was identified as Bacillus sp. and can tolerate more than 5% salinity. It can grow in the presence of 0-7mM Mn(II) and pH range from 5.0 to 7.0. When the initial Mn(II) was 5mM, the percentage of Mn(II) oxidation reached the highest value of 16% after 10days of incubation. The initial pH (5.0 to 7.0) affected the percentage of Mn(II) oxidation, but the ability of the strain FF-1 to self-regulate pH resulted in the final pH being almost 7.6. The removal of Mn(II) by the strain FF-1 involves extracellular and intracellular adsorption as well as Mn(II) oxidation. Intracellular Mn adsorption contributed a small part to the total Mn removal, and extracellular adsorption was dominant in the initial stage of Mn removal. The solid products after Mn removal were a mixture of MnOx and MnCO3. The layered MnOx formed in the extracellular space could be easily collected and used for adsorption and oxidation of pollutants.

Removal of pharmaceutical in a biogenic/chemical manganese oxide system driven by manganese-oxidizing bacteria with humic acids as sole carbon source

Bioaugmented sand filtration has attracted considerable attention because it can effectively remove contaminants in drinking water without additional chemical reagent addition. In this study, a synthesized chemical manganese dioxide (MnO2)-coated quartz sand (MnQS) and biogenic manganese oxide (BioMnOx) composite system was proposed to simultaneously remove typical pharmaceutical contaminants and Mn2+. We demonstrated a manganese-oxidizing bacterium, Pseudomonas sp. QJX-1, could oxidize Mn2+ to generate BioMnOx using humic acids (HA) as sole carbon source. The coaction of MnQS, QJX-1, and the generated BioMnOx in simultaneously removing caffeine and Mn2+ in the presence of HA was evaluated. We found a synergistic effect between them. MnQS and BioMnOx together significantly increased the caffeine removal efficiency from 32.8% (MnQS alone) and 21.5% (BioMnOx alone) to 61.2%. Meanwhile, Mn2+ leaked from MnQS was rapidly oxidized by QJX-1 to regenerate reactive BioMnOx, which was beneficial for continuous contaminant removal and system stability. Different degradation intermediates of caffeine oxidized by MnQS and BioMnOx were detected by LC-QTOF-MS analysis, which implied that caffeine was oxidized by a different pathway. Overall, this work promotes the potential application of bioaugmented sand filtration in pharmaceutical removal in the presence of natural organic matter in drinking water.

Removal of manganese in acidic solutions utilizing Achromobacter sp. strain QBM-4 isolated from mine drainage

Biological approaches with the core of manganese-oxidizing bacteria (MnOB) are cheap and environmentally friendly solutions for the removal of bivalent manganese (Mn(II)). These bacteria typically worked well in the pH range of 5.5 – 8.0 but poorly under pH below 5.5. In this study, we isolated an acid-tolerant manganese-oxidizing bacterium (Achromobacter sp. strain QBM-4) from acid mine drainage (AMD), which was effective for Mn(II) removal at pH 4.0. Under optimized treatment conditions (i.e., 60.0 mg·L−1 Mn(II), 100.0 mg·L−1 Fe(III), and 35.0 °C), the Mn(II) removal efficiency reached 93.6 ± 0.8% at an initial pH of 4.0. Approximately 68.0% of the Mn(II) was removed through adsorption, and the remainder was attributed to oxidation. The Mn(II) oxidation rate was ~ 0.05 mM·d−1 (initial pH of 4.0), comparable with other MnOB performing under near-neutral solutions. Ferric ions (Fe(III)) can form amorphous iron hydroxides, facilitating sorptive removal and catalytic oxidation of Mn(II). In contrast, ferrous ions (Fe(II)) reductively dissolve manganese oxides, inhibiting Mn(II) removal. A mechanism for the biological removal of Mn(II) was proposed, and the performance of Achromobacter sp. strain QBM-4 was further verified in three types of mine drainage.

Combination of the endophytic manganese-oxidizing bacterium Pantoea eucrina SS01 and biogenic Mn oxides: An efficient and sustainable complex in degradation and detoxification of malachite green

Recently, Mn oxides (MnOxs) have been attracting considerable interest in the oxidation of organic pollutants. However, the reduction of MnOx in these reactions leads to the deactivation of the catalyst, which must be frequently regenerated. We evaluated the application of a manganese-oxidizing bacterium (MOB) and MnOx in removing toxic dyes. We studied the co-function of a plant-endophytic MOB, Pantoea eucrina SS01, with its bio-generated MnOx and evaluated the detoxification activity and chemical transformation mechanisms of the complex in malachite green (MG) degradation. We found a synergistic effect between MnOx and the strain. Particularly, strain SS01 could adsorb MG but could not degrade it, whereas the addition of Mn(II) promoted MG degradation by the formation of a complex containing the bacterium and MnOx aggregates (SS01-bio-MnOx), with distinct morphology characteristics. The complex showed a marked sustainability in the degradation of MG into less toxic or non-toxic metabolites. In this process, strain SS01 might have enhanced the regeneration of MnOx, accelerating MG degradation. Our data not only contribute to understanding the mechanism of MG removal by the SS01-bio-MnOx complex, but also provide a scientific basis for the future application of MOB and MnOx.

Degradation of ofloxacin by a manganese-oxidizing bacterium Pseudomonas sp. F2 and its biogenic manganese oxides

Fluoroquinolone antibiotics like ofloxacin (OFL) have been frequently detected in the aquatic environment. Recently manganese-oxidizing bacteria (MOB) have attracted research efforts on the degradation of recalcitrant pollutants with the aid of their biogenic manganese oxides (BioMnOx). Herein, the degradation of OFL with a strain of MOB (Pseudomonas sp. F2) was investigated for the first time. It was found that the bacteria can degrade up to 100% of 5 μg/L OFL. BioMnOx and Mn(III) intermediates significantly contributed to the degradation. Moreover, the degradation was clearly declined when the microbial activity was inactivated by heat or ethanol, indicating the importance of bioactivity. Possible transformation products of OFL were identified by HPLC-MS and the degradation pathway was proposed. In addition, the toxicity of OFL was reduced by 66% after the degradation.

Manganese Removal by Biofiltration Using Activated Carbon-barium Alginate-entrapped Cells: Morphology, Durability, Settling Velocity, and Treatment Efficiency

Occurrence of manganese in water supplies causes colored water and pipe rusting in water treatment and distribution systems. Moreover, consumption of manganese-contaminated water may lead to neurotoxicity in humans. Biofilters have the potential to alleviate the manganese issue through bio-oxidation, particle separation, and adsorption processes. Biofiltration performance can be enhanced by augmentation of the manganese-oxidizing bacterium entrapped in polymeric materials. This study aimed to investigate the potential of barium alginate-entrapped cells supplemented with powdered activated carbon (PAC) for manganese removal. Streptomyces violarus strain SBP1, an effective manganese-oxidizing bacterium, was selected. The experiments were divided into 2 parts, including 1) characterization of barium alginate bead and 2) manganese removal testing. Effect of PAC content (1, 5, and 10% w/v) in the entrapment material on bead morphology, bead durability, and settling velocity (relative to a filtration medium) was investigated. Micro-structural observation using a scanning electron microscope showed that the PAC was distributed through intra-porous structure of the beads. The PAC-supplemented barium alginate beads improved durability (up to three-time higher Young’s modulus values). The PAC-supplemented barium alginate beads gave similar settling velocity compared to a filtration medium. The manganese removal efficiencies by the PAC-supplemented beads (no cells) ranged from 48 to 53%. Based on barium alginate bead characterization and manganese removal performance, the bead with 5% PAC content was selected for cell entrapment. The investigation revealed that the entrapped cells achieved faster manganese removal rate than free cell system. The findings from this study indicated high potential of the entrapped cells for use in future biofilter applications.

Growth inhibition of Microcystis aeruginosa by sand-filter prevalent manganese-oxidizing bacterium

The utilization of algicidal bacteria is becoming an attractive method for the inhibition of algae growth. However, the previous research has mainly focused on the control of harmful blooms in eutrophic waters by the addition of algicidal bacteria. This study aims to investigate the growth of algal cells in the presence of a sand-filter prevalent manganese-oxidizing bacterium, which might alleviate the algae-induced clogging problem in sand filters via bioaugmented sand filtration. The manganese-oxidizing bacterium Pseudomonas sp. QJX-1 exhibited an inhibiting effect on algae growth. Compared with a control group, the chlorophyll a content of M. aeruginosa could be significantly decreased by 60% after exposure to 10% QJX-1 culture supernatant. The decrease in photosynthetic parameters demonstrated the damage to the photosynthetic system of algal cells exposed to QJX-1 cell-free supernatant. The results indicated that QJX-1 inhibited the growth of M. aeruginosa by excreting an algicidal compound, 2,4-di-tert-butylphenol (2,4-DTBP), without directly contacting algal cells. The photosynthetic system structure of algal cells could be damaged through 2,4-DTBP excretion by QJX-1, which could explain the weakened photosynthetic activity of algal cells exposed to QJX-1. Our findings highlight the algicidal effect of the manganese-oxidizing bacterium Pseudomonas sp. QJX-1 on M. aeruginosa via the excretion of 2,4-DTBP.

Manganese-contaminated groundwater treatment by novel bacterial isolates: kinetic study and mechanism analysis using synchrotron-based techniques

The occurrence of manganese in groundwater causes coloured water and pipe rusting in water treatment systems. Consumption of manganese-contaminated water promotes neurotoxicity in humans and animals. Manganese-oxidizing bacteria were isolated from contaminated areas in Thailand for removing manganese from water. The selected bacterium was investigated for its removal kinetics and mechanism using synchrotron-based techniques. Among 21 isolates, Streptomyces violarus strain SBP1 (SBP1) was the best manganese-oxidizing bacterium. At a manganese concentration of 1 mg L−1, SBP1 achieved up to 46% removal. The isolate also successfully removed other metal and metalloid, such as iron (81%) and arsenic (38%). The manganese concentration played a role in manganese removal and bacterial growth. The observed self-substrate inhibition best fit with the Aiba model. Kinetic parameters estimated from the model, including a specific growth rate, half-velocity constant, and inhibitory constant, were 0.095 h−1, 0.453 mg L−1, and 37.975 mg L−1, respectively. The synchrotron-based techniques indicated that SBP1 removed manganese via combination of bio-oxidation (80%) and adsorption (20%). The study is the first report on biological manganese removal mechanism using synchrotron-based techniques. SBP1 effectively removed manganese under board range of manganese concentrations. This result showed the potential use of the isolate for treating manganese-contaminated water.

Simultaneous manganese adsorption and biotransformation by Streptomyces violarus strain SBP1 cell-immobilized biochar

Consumption of water containing high proportions of manganese could cause Parkinson's like symptoms and damage the central nervous systems. This study aims to investigate the potential of manganese removal through the development of microbial cell-immobilized biochar. The wood vinegar industry generates a large volume of carbonized wood waste (natural biochar) from the pyrolytic process. This is the first investigation utilizing this low value waste combined with biological treatment for water purification. Raw and hydrogen peroxide-modified biochars were used to immobilize an effective manganese-oxidizing bacterium, Streptomyces violarus strain SBP1 (SBP1). The results demonstrated that the modified biochar had a higher proportion of oxygen-containing functional groups leading to better manganese removal. Manganese adsorption by the modified biochar fitted pseudo-second-order and Langmuir models with the maximum adsorption capacity of 1.15 mg g−1. The modified biochar with SBP1 provided the highest removal efficiency at 78%. The advanced synchrotron analyses demonstrated that manganese removal by the biochar with SBP1 is due to the synergistic combination of manganese adsorption by biochars and biological oxidation by SBP1.

Draft Genome Sequence of Manganese-Oxidizing Bacterium Massilia sp. Strain Mn16-1_5, Isolated from Serpentine Soil in Taitung, Taiwan.

Massilia sp. strain Mn16-1_5 was isolated from serpentine soil. This strain is able to oxidize manganese and has the potential for bioremediation of chromium. Here, we present a 5.53-Mb draft genome sequence of this strain with a G+C content of 64.8% that might provide more information for species delineation and oxidase genes in this strain.

Simultaneous remediation of As(III) and dibutyl phthalate (DBP) in soil by a manganese-oxidizing bacterium and its mechanisms

Soils are experiencing increasing pollution with arsenic (As) and phthalate esters (PAEs), which is threatening human health. In this study, the feasibility of simultaneous remediation of soil As(III) and a PAE, dibutyl phthalate (DBP), by a manganese-oxidizing bacterium (MnOB) was evaluated. As immobilization and DBP degradation were simultaneously enhanced by MnOB addition. The effects of initial concentrations of As(III), DBP, and Mn(II), and moisture content on the removal of As(III) and DBP were investigated. The results indicated that there was a competitive interaction between As(III) and DBP removal, and 40 mg/kg of Mn(II) dosage and 20%–30% soil moisture content were recommended for optimal and simultaneous removal of As(III) and DBP. Microbial community analysis revealed that community structure and diversity were not changed significantly by MnOB addition. Taken together, the findings from this study indicated that DBP was degraded primarily by microorganisms, whereas As(III) was removed largely by biogenic Mn oxides and immobilized by adsorption onto Mg/Fe oxides and/or formation of metal arsenate precipitates/co-precipitates. This study offers a novel and high-efficiency strategy to remediate the combined contamination of As and PAEs in soils.

Manganese Oxidation Characteristics and Oxidation Mechanism of a Manganese-Oxidizing Bacterium Arthrobacter sp. HW-16

Manganese is a common inorganic pollutant, which is difficult to remove from the environment. In this research, a high efficient manganese-oxidizing bacterium Arthrobacter sp. HW-16 was isolated from the manganese-rich soil using selective media. Besides, high-throughput sequencing revealed that there were significant differences of the microbial community compositions when bacteria were acclimated in different conditions, and Arthrobacte was the dominant genus in Mn(Ⅱ) containing media. In this paper, the microbiological properties of strain HW-16 and Mn(Ⅱ) oxidation mechanism were investigated. The results indicated that the maximal Mn(Ⅱ) tolerance mass concentration of strain HW-16 was 5000 mg·L-1,and it exhibited a decent Mn(Ⅱ) oxidation efficiency with the highest value of 66.28% at a Mn(Ⅱ) concentration of 3000 mg·L-1. Single factor experiments demonstrated that environmental factors could affect the growth and Mn(Ⅱ) oxidation efficiency of strain HW-16. At 30℃ or pH 7.0, at 1% or 3% salinity, and at 200 r·min-1, strain HW-16 got the highest biomass. While the highest Mn(Ⅱ) oxidation efficiency occurred at high temperature (≥40℃), high pH (≥7), high shaking speed and low salinity. Strain HW-16 could oxidize Mn(Ⅱ) by producing Mn(Ⅱ) oxidizing active factor and turn Mn(Ⅱ) into precipitation by synthesizing alkaline metabolites.

The key role of biogenic manganese oxides in enhanced removal of highly recalcitrant 1,2,4-triazole from bio-treated chemical industrial wastewater

The secondary effluent from biological treatment process in chemical industrial plant often contains refractory organic matter, which deserves to be further treated in order to meet the increasingly stringent environmental regulations. In this study, the key role of biogenic manganese oxides (BioMnOx) in enhanced removal of highly recalcitrant 1,2,4-triazole from bio-treated chemical industrial wastewater was investigated. BioMnOx production by acclimated manganese-oxidizing bacterium (MOB) consortium was confirmed through scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analysis. Pseudomonas and Bacillus were found to be the most predominant species in acclimated MOB consortium. Mn2+ could be oxidized optimally at neutral pH and initial Mn2+ concentration below 33mgL-1. However, 1,2,4-triazole removal by BioMnOx produced occurred optimally at slightly acidic pH. High dosage of both Mn2+ and 1,2,4-triazole resulted in decreased 1,2,4-triazole removal. In a biological aerated filter (BAF) coupled with manganese oxidation, 1,2,4-triazole and total organic carbon removal could be significantly enhanced compared to the control system without the participation of manganese oxidation, confirming the key role of BioMnOx in the removal of highly recalcitrant 1,2,4-triazole. This study demonstrated that the biosystem coupled with manganese oxidation had a potential for the removal of various recalcitrant contaminants from bio-treated chemical industrial wastewater.

Simultaneous Removal of Mn(II) and Nitrate by the Manganese-Oxidizing Bacterium Acinetobacter sp. SZ28 in Anaerobic Conditions

ABSTRACTA novel bacterium, strain SZ28, identified as Acinetobacter sp., showed anaerobic denitrification ability using Mn(II) as the electron donor. Nitrate-nitrogen concentration decreased from nearly 16.52–mg L−1 to 4.4–mg L−1, without accumulation of nitrite as an intermediate, with a maximum of 0.063–mg NO3−-N L−1 h−1, reaching a peak of 0.085–mg NO3−-N L−1 h−1 in sodium acetate. The nitrate removal rate reached 0.067–mg NO3−-N L−1 h−1, 0.059–mg NO3−-N L−1 h−1, and 0.078 mg NO3−-N L−1 h−1 using Mn(II), S(II), and Fe(II) as electron donors, respectively. The optimum pH was 6.0, with a removal rate of 0.063–mg NO3−-N L−1 h−1