Simultaneous reduction of antibiotics and antibiotic resistance genes in pig manure using a composting process with a novel microbial agent.

In recent years, in order to promote animal growth and reduce the risk of disease, a variety of antibiotics are frequently added to the animal feed of livestock and poultry. However, these antibiotics can not be fully digested by animals and most of them are excreted with feces, consequently causing the enrichment of antibiotic resistance genes (ARGs) and huge environmental risks. Nowadays, composting is a better option to solve these problems. Accordingly, this study explored the effects of co-composting swine manure with different inoculants dominated by Phanerochaete chrysosporium (p), Aspergillus niger (a), and Bacillus licheniformis (b) on the simultaneous removal of multiple antibiotics and resistance genes and evolution of the bacterial community. The results showed that the highest removal extent of tetracycline and oxytetracycline occurred in pile D (p:b:a=1:5:5, biomass) reaching 89.2% and 87.8%, respectively, while the highest removal extent of doxycycline and enrofloxacin occurred in pile A (p:b:a=1:0:0, biomass) reaching 98.6% and 89%, respectively. Compared with the levels in pile B (control check), in pile D, ARGs, except those for sulfonamides, decreased by 1.059 × 10-3-6.68 × 10-2 gene copies/16S rRNA copies. Inoculation with p alone effectively reduced intI1 and intI2. Canonical correspondence analysis (CCA) that microbial community structure evolution had a greater influence on ARGs than environmental factors. In summary, this study provided a feasible way to efficiently remove the antibiotics and antibiotic resistance genes in pig manure.

Thermal behaviors, combustion mechanisms, evolved gasses, and ash analysis of spent potlining for a hazardous waste management.

An unavoidable but reusable waste so as to enhance a more circular waste utilization has been spent potlining (SPL) generated by the aluminum industry. The combustion mechanisms, evolved gasses, and ash properties of SPL were characterized dynamically in response to the elevated temperature and heating rates. Differential scanning calorimetric (DSC) results indicated an exothermic reaction behavior probably able to meet the energy needs of various industrial applications. The reaction mechanisms for the SPL combustion were best described using the 1.5-, 3- and 2.5-order reaction models. Fluoride volatilization rate of the flue gas was estimated at 2.24%. The SPL combustion emitted CO2, HNCO, NO, and NO2 but SOx. The joint optimization of remaining mass, derivative thermogravimetry, and derivative DSC was achieved with the optimal temperature and heating rate combination of 783.5 °C, and 5 °C/min, respectively. Interaction between temperature and heating rate exerted the strongest and weakest impact on DSC and remaining mass, respectively. The fluorine mainly as the formation of substantial NaF and CaF2 in the residual ash. Besides, the composition and effect of environment of residual solid were evaluated. The ash slagging tendency and its mineral deposition mechanisms were elucidated in terms of turning SPL waste into a benign input to a circular waste utilization.

Sequential extraction for heavy metal distribution of bottom ash from fluidized bed co-combusted phosphorus-rich sludge under the agglomeration/defluidization process.

Agglomeration that occurs during municipal sewage sludge (MSS) fluidized bed co-combustion might affect heavy metal distribution and the transformation of bottom ash. A study on the mobility and speciation of heavy metals that accompanies agglomeration behavior and phosphorus addition should be examined during MSS co-combustion. Meanwhile, the aim of this study was to evaluate the total content and speciation of heavy metals during the MSS fluidized bed co-combustion by the chemical sequential extraction procedure (SEP). The risk assessment code (RAC) and individual contamination factor (ICF) are calculated to evaluate the mobility of heavy metals and their environmental risks in agglomerates. Moreover, identification of agglomerates is established by both characterization (scanning electron microscopy/energy-dispersive spectroscopy, X-ray photoelectron spectroscopy) and thermodynamic simulation (HSC chemistry software). The experimental results indicated that P and Na would form the lower melting-point compounds such as NaPO3 and Na2O in the bottom ash, which promoted agglomeration during MSS fluidized bed co-combustion. According to the simulation, Na and P have a stronger affinity than Si and Cr, and this reaction is not only influenced by particle agglomeration, but also by heavy metal distribution during modified MSS co-combustion. Nevertheless, the results of ICFs and RACs obtained from the SEP indicated that for heavy metals trapped in agglomerates, a weaker binding such as physical covering by eutectics might be considered as the dominant reaction compared with chemical binding to form a metal complex.

Thermodynamic equilibrium predictions of zinc volatilization, migration, and transformation during sludge co-incineration.

The effects of interactions between and among chlorine (Cl), sulfur (S), phosphorus (P), and minerals on migration, transformation, and volatilization of zinc (Zn) were numerically simulated in sludge co-incineration using the chemical thermodynamic equilibrium method. Our results showed that all the minerals of Fe2 O3 , Al2 O3 , Fe2 O3 , and TiO2 except for CaO in the sludge co-incineration system reacted with Zn which inhibited the Zn volatilization. The presence of S and P was beneficial to the formation of ZnSO4 (s) and Zn3 (PO4 )2 (s). Cl weakened the chemical reactions between the minerals and Zn, thus increasing the Zn volatilization. Changes in Zn transformation and migration induced by the coupling of Cl + S were mainly controlled by Cl, S, and the minerals, while those induced by Cl + P and S + P were mainly controlled by P and S + P. The presence of P + Cl, S + Cl, S + P, S + Cl + P, Cl, and Al2 O3 in the coexisting mineral system controlled the reactions between the minerals and Zn.

Thermogravimetric Analysis of Textile Dyeing Sludge (TDS) in N2/CO2/O2 Atmospheres and its Combustion Model with Coal.

The combustion characteristics of textile dyeing sludge (TDS) in N2/O2, CO2/O2, and N2/CO2 atmospheres, and blends of TDS with coal were analyzed using TGA (thermogravimetric analysis). Results showed that the replacement of N2 by CO2 resulted in negative effects on the combustion and pyrolysis of TDS. Comparing N2/O2 and CO2/O2 atmospheres, combustion of TDS was easier in a N2/O2 atmosphere, but the residual mass after TDS pyrolysis in pure CO2 was less than that in N2 by approximately 4.51%. When the proportion of TDS was 30-50% in the blends of coal with TDS, a synergistic interaction clearly occurred, and it significantly promoted combustion. In considering different combustion parameters, the optimal proportion of TDS may be between 20-30%. The activation energy Ea value decreased from 155.6 kJ/mol to 53.35 kJ/mol with an increasing TDS proportion from 0% to 50%, and it rapidly decreased when the TDS proportion was below 20%.

The effect of additives on migration and transformation of gaseous pollutants in the vacuum pyrolysis process of waste printed circuit boards.

The effect of six additives (CaCO3, HZSM-5, CaO, Al2O3, FeOOH and Ca(OH)2) on the generation, migration, transformation and escaping behaviours of typical gaseous pollutants in the pyrolysis process were studied by vacuum pyrolysis experiments on epoxy resin powder from waste printed circuit boards with tube furnace. The results show that the additives Al2O3, CaO, Ca(OH) 2 and FeOOH could reduce the yield of the gas phase. The removal rates of pollutants, such as benzene, toluene, ethyl benzene, phenol, p-xylene, HBr, NO2 and SO2 in the gaseous products, has changed variously with the increasing percentage of the above additives. Judging from the control of gas-phase pollutant discharge, the calcium-base additives are superior to the others. Ca(OH)2 has the best inhibition effect among them. The increase of the pyrolysis temperature and vacuum degree enhanced the volatility of organic pollutants and weakened the Ca(OH)2 inhibition effect on organic pollutants, while it improved the removal rate of SO2. Under the condition of 500 °C pyrolysis temperature and 0.09 MPa vacuum degree, when the additive proportion of Ca(OH)2 was one-fifth, the average removal rate of pollutants in gas phase is up to 66.4%.

Variational Characteristics and Implications of Gaseous Elemental Mercury for Three Continuous Typhoons in China.

Coupling air pollutants with particular meteorological conditions can induce air pollution episodes. To our knowledge, how typhoons influence mercury (Hg) as an extreme weather phenomena has not been reported. Gaseous elemental Hg (GEM) was measured during a time period (from September 16, 2011 to October 9, 2011) that included three typhoons (Haitang, Nesat, and Nalgae) at the Wuzhishan National Atmospheric Background Station. The GEM concentration during these typhoons ranged from 1.81 to 4.73 ng/m(3) (2.97 ± 0.58 ng/m(3)), 1.27 to 4.42 ng/m(3) (2.69 ± 0.83 ng/m(3)), and 1.43 to 2.99 ng/m(3) (2.47 ± 0.32 ng/m(3)), which was higher than for the non-typhoon period (1.14-2.93 ng/m(3), 1.61 ± 0.52 ng/m(3)). Simultaneously, the three typhoon periods exhibited a significant positive correlation between the GEM concentration and wind speed. These results differ from the common belief that lower pollutant concentrations will occur due to a typhoon accelerating pollutant diffusion. Changes in the wind direction and long range pollutant transport from the Chinese mainland can reasonably account for this abnormality. There was a significantly positive correlation between the GEM and SO2, NO x , CO, and O3 levels during the three typhoons periods, which indicates they came from the same sources or areas. A backward trajectory analysis and the concentration weighted field at our monitoring site indicated that clean air masses mainly came from Southeast Asia or the southeast and northeast sea surfaces during non-typhoon periods, while polluted air masses came from the Chinese mainland during the three typhoon periods. The results implied that the increased GEM concentrations in the Wuzhi Mountain were caused by the long-range atmospheric transport of Hg from the Chinese mainland during the typhoon periods. The combustion of coal may be the main emission sources.

Thermal Behavior of Cd During Sludge Incineration: Experiments and Thermodynamic Equilibrium Model.

Experiments and thermodynamic equilibrium calculations were performed to investigate the behavior of Cd during sewage sludge incineration. The chemical equilibrium calculations indicated that chlorine significantly increased the volatilization of Cd in the form of CdCl2. In addition, SiO2-containing materials can function as sorbents for stabilizing Cd. The effect of PVC added to the sludge on the migration of Cd in the sludge was greater than that of NaCl. As the temperature increased, both organic and inorganic chlorides reduced the Cd distribution in the bottom ash. The chloride concentration, and the incineration time exhibited insignificant changes in Cd emission. With the addition of either NaCl or PVC into the sludge, the phases of Cd present in the bottom slag were primarily present in the form of silica-alumina oxides or multi-metal oxide, which could inhabit the Cd volatilization.

Thermodynamic Equilibrium Calculations on Cd Transformation during Sewage Sludge Incineration.

Thermodynamic equilibrium calculations were performed to reveal the distribution of cadmium during the sewage sludge incineration process. During sludge incineration in the presence of major minerals, such as SiO2, Al2O3 and CaO, the strongest effect was exerted by SiO2 on the Cd transformation compared with the effect of others. The stable solid product of CdSiO3 was formed easily with the reaction between Cd and SiO2, which can restrain the emissions of gaseous Cd pollutants. CdCl2 was formed more easily in the presence of chloride during incineration, thus, the volatilization of Cd was advanced by increasing chlorine content. At low temperatures, the volatilization of Cd was restrained due to the formation of the refractory solid metal sulfate. At high temperatures, the speciation of Cd was not affected by the presence of sulfur, but sulfur could affect the formation temperature of gaseous metals.

Unveiling characteristics of a bioelectrochemical system with polarity reversion for simultaneous azo dye treatment and bioelectricity generation.

A novel bioelectrochemical system (BES) operated with polarity reversion was explored for simultaneous anaerobic/aerobic treatment of azo dye and production of bioelectricity under extremely low buffer. The Congo red was first decolorized in anode, with completed color removal in 35 h. The resultant decolorization intermediates were then mineralized after the anode reversed to aerobic biocathode, evidenced by 55 % chemical oxygen demand (COD) removal in 200 h. The mineralization efficiency was further increased to 70 % when the period of the half-cycle was prolonged to 375 h. Meanwhile, the BES produced a continuous stable positive/negative alternate voltage output under 5 mM phosphate buffer because of the self-neutralization of the accumulated protons and hydroxyl ions in electrolyte. The electrode performance was significantly improved, which was indicated by alleviated electrode polarization, due to in situ use of accumulated protons and hydroxyl ions and enhanced electron transfer in the presence of Congo red and its degradation intermediates, which resulted in 1.05-fold increases in maximum power density (67.5 vs. 32.9 mW/m(2)). An analysis of the microbial diversity in the biofilm revealed that the biofilm was dominated by facultative bacteria with functional roles in contaminant degradation and electricity generation.

Enhanced dewaterability of textile dyeing sludge using micro-electrolysis pretreatment.

The effects of micro-electrolysis treatment on textile dyeing sludge dewatering and its mechanisms were investigated in this study. Capillary suction time (CST) and settling velocity (SV) were used to evaluate sludge dewaterability. Extracellular polymeric substances (EPS) concentration and sludge disintegration degree (DDSCOD) were determined to explain the observed changes in sludge dewaterability. The results demonstrated that the micro-electrolysis could significantly improve sludge dewaterability by disrupting the sludge floc structure. The optimal conditions of sludge dewatering were the reaction time of 20 min, initial pH of 2.5, Fe/C mass ratio of 1/1, and the iron powder dosage of 2.50 g/L, which achieved good CST (from 34.1 to 27.8 s) and SV (from 75 to 60%) reduction efficiency. In addition, the scanning electron microscope (SEM) images revealed that the treated sludge floc clusters are broken up and that the dispersion degree is better than that of a raw sludge sample. The optimal EPS concentration and DDSCOD to obtain maximum sludge dewaterability was 43-46 mg/L and 4.2-4.9%, respectively. The destruction of EPS was one of the primary reasons for the improvement of sludge dewaterability during micro-electrolysis treatment.

Effect of K2FeO4/US treatment on textile dyeing sludge disintegration and dewaterability.

The effect of potassium ferrate/ultrasonic (K2FeO4/US) treatment on the physicochemical features of textile dyeing sludge was studied. The soluble chemical oxygen demand (SCOD), deoxyribonucleic acid (DNA), sludge volume index (SVI), sludge viscosity, capillary suction time (CST) and particle size were measured to understand the observed changes in the sludge physicochemical features. The results showed that the combined K2FeO4/US treatment presented great advantages for disrupting the sludge floc structure over K2FeO4 or ultrasonic treatments alone. The optimal parameters of sludge disintegration were found to be a K2FeO4 treatment time of 60 min, a K2FeO4 dosage of 0.5936 g/g SS, an ultrasonic time of 15 min and an ultrasonic intensity of 0.72 W/mL. The initial median diameter of the sludge particles was 15.24 µm, and this value decreased by 35.89%. The CST was initially 59.6 s and increased by 231%, whereas the SVI was 97.78 mL/g and decreased by 25.89%. Scanning electron microscope (SEM) images indicated that the sludge surface was irregular and loose with a large amount of channels or voids during K2FeO4/US treatment. K2FeO4/US treatment synergistically enhanced the sludge solubilization and reached 668.67 mg/L SCOD, which is 31.81% greater than the additive value obtained with K2FeO4 treatment alone (215.95 mg/L) or with ultrasonic treatment alone (240 mg/L).

An experimental and thermodynamic equilibrium investigation of the Pb, Zn, Cr, Cu, Mn and Ni partitioning during sewage sludge incineration.

The effects of different chlorides and operational conditions on the distribution and speciation of six heavy metals (Pb, Zn, Cr, Cu, Mn and Ni) during sludge incineration were investigated using a simulated laboratory tubular-furnace reactor. A thermodynamic equilibrium investigation using the FactSage software was performed to compare the experimental results. The results indicate that the volatility of the target metals was enhanced as the chlorine concentration increased. Inorganic-Cl influenced the volatilization of heavy metals in the order of Pb>Zn>Cr>Cu>Mn>Ni. However, the effects of organic-Cl on the volatility of Mn, Pb and Cu were greater than the effects on Zn, Cr and Ni. With increasing combustion temperature, the presence of organic-Cl (PVC) and inorganic-Cl (NaCl) improved the transfer of Pb and Zn from bottom ash to fly ash or fuse gas. However, the presence of chloride had no obvious influence on Mn, Cu and Ni. Increased retention time could increase the volatilization rate of heavy metals; however, this effect was insignificant. During the incineration process, Pb readily formed PbSiO4 and remained in the bottom ash. Different Pb compounds, primarily the volatile PbCl2, were found in the gas phase after the addition of NaCl; the dominant Pb compounds in the gas phase after the addition of PVC were PbCl2, Pb(ClO4)2 and PbCl2O4.

Levels, composition profiles and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in sludge from ten textile dyeing plants.

As components of synthetic dyes, polycyclic aromatic hydrocarbons (PAHs) are present as contaminants in textile dyeing sludge due to the recalcitrance in wastewater treatment process, which may pose a threat to environment in the process of sludge disposal. In order to evaluate PAHs in textile dyeing sludge, comprehensive investigation comprising 10 textile dyeing plants was undertaken. Levels, composition profiles and risk assessment of 16 EPA-priority PAHs were analyzed in this study. The total concentrations of 16 PAHs (∑16 PAHs) varied from 1463 ± 177 ng g(-1) to 16,714 ± 1,507 ng g(-1) with a mean value of 6386 ng g(-1). The composition profiles of PAHs were characterized by 3- and 4-ring PAHs, among which phenanthrene, anthracene and fluoranthene were the most dominant components. The mean benzo[a]pyrene equivalent (BaPeq) concentration of ∑16 PAHs in textile dyeing sludge was 423 ng g(-1), which was 2-3 times higher than concentrations reported for urban soil. According to ecological risk assessment, the levels of PAHs in the textile dyeing sludge may cause a significant risk to soil ecosystem after landfill or dumping on soil.

Atmosphere-dependent combustion of Ganoderma lucidum biomass toward its enhanced transformability into green energy.

Globally, the circular efficiency of biomass resources has become a priority due to the depletion and negative environmental impacts of fossil fuels. This study aimed to quantify the atmosphere-dependent combustion of Ganoderma lucidum (GL) biomass and its thermodynamic and kinetic parameters toward enhancing its circularity and transformability characteristics. The GL combustion occurred in the three stages of moisture removal, volatile release, and coke combustion. Combustion performance characteristics were more favorable in the N2/O2 atmosphere than in the CO2/O2 atmosphere under the same heating rates. The rising heating rate facilitated the release of volatiles. According to the model-free methods of Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose, the activation energies essential for the primary reaction were 283.09 kJ/mol and 288.28 kJ/mol in the N2/O2 atmosphere and 233.09 kJ/mol and 235.64 kJ/mol in the CO2/O2 atmosphere. The gaseous products of the GL combustion included CH4, H2O, C = O, CO, CO2, NH3, C = C, and C-O(H). Ash prepared in both atmospheres exhibited a tendency for slag formation, with oxy-fuel combustion lowering its risk. This study thus provides a theoretical and practical basis for transforming GL residues into a sustainable energy source.

Microplastics as emerging contaminants in textile dyeing sludge: Their impacts on co-combustion/pyrolysis products, residual metals, and temperature dependency of emissions.

As emerging contaminants in textile dyeing sludge (TDS), the presence and types of microplastics (MPs) inevitably influence the combustion and pyrolysis of TDS. Their effects on the co-combustion/pyrolysis emissions and residual metals of TDS remain poorly understood. This study aimed to quantify the impacts of polyethylene (PE) and polypropylene (PP) on the transports and transformations of gaseous emissions and residual metals generated during the TDS combustion and pyrolysis in the air, oxy-fuel, and nitrogen atmospheres. Thermal degradation of the MPs in TDS occurred between 242-600 °C. MPs decomposed and interacted with the organic components of TDS to the extent that they increased the release of VOCs, dominated by oxygenated VOCs and hydrocarbons under the incineration and pyrolysis conditions, respectively. The presence of PE exerted a limited impact on the concentration and chemical form of metals, while PP reduced the residual amount of most metals due to the decomposition of mineral additives. Also, PP (with CaCO3 filler) reduced the acid-extractable content of cadmium, copper, and manganese in the bottom slag or coke but increased that of chromium. This study provides actionable insights into optimizing gas emissions, energy recovery, and ash reuse, thus reinforcing the pollution control strategies for both the MPs and TDS.

Concentrations and speciation of heavy metals in sludge from nine textile dyeing plants.

The safe disposal of sludge from textile dyeing industry requires research on bioavailability and concentration of heavy metals. In this study, concentrations and chemical speciation of heavy metals (Cd, Cr, Cu, Ni, Zn, Pb) in sludge from nine different textile dyeing plants were examined. Some physiochemical features of sludge from textile dyeing industry were determined, and a sequential extraction procedure recommended by the Community Bureau of Reference (BCR) was used to study the metal speciation. Cluster analysis (CA) and principal component analysis (PCA) were applied to provide additional information regarding differences in sludge composition. The results showed that Zn and Cu contents were the highest, followed by Ni, Cr, Cd and Pb. The concentration of Cd and Ni in some sludge samples exceeded the standard suggested for acidic soils in China (GB18918-2002). In sludge from textile dyeing plants, Pb, Cd and Cr were principally distributed in the oxidizable and residual fraction, Cu in the oxidizable fraction, Ni in all four fractions and Zn in the acid soluble/exchangeable and reducible fractions. The pH and heat-drying method affected the fractionation of heavy metals in sludge.

Characterization and environmental risk assessment of heavy metals found in fly ashes from waste filter bags obtained from a Chinese steel plant.

The environmental risk of exposure to six heavy metals (Cu, Pb, Zn, Cr, Ni, and Cd) found in fly ashes from waste filter bags obtained from a steel plant was estimated based on the mineralogical compositions, total concentrations and speciation of the metals in the fly ashes. The results indicated that the fly ashes mainly consisted of hematite, magnetite, cyanite, spinel, coesite and amorphous materials. The concentrations of Zn and Pb were much higher than that of other materials. After Zn and Pb, Ni was present in the highest concentration, followed by Cu, Cr and Cd. Each heavy metal was distributed differently in fly ashes. The levels of Zn, Cd and Pb in the active fraction were very high, and ranged from 64.83 to 81.96%, 34.48 to 82.4% and 6.92 to 79.65% respectively, while Cu, Cr and Ni were mainly present in the residual fraction. The risk assessment code (RAC) values of fly ashes showed that the Zn and Cd present in the H3 sample presented a very high risk, with RAC values greater than 50%. The Cu present in the H3 sample, Cd in the H2 sample and Zn in the H4 and H5 samples presented a high risk. The Pb present in the H2 sample, Cd in the H4 sample, Ni in the H1 and H5 samples, and Zn in the H1 sample presented a medium risk. A low risk was presented by the Cu present in the H1, H2, H4 and H5 samples, the Pb in the H1, H3 and H5 samples, the Cd in the H1 and H5 samples, and the Ni in the H2 sample. No risk was presented by Cr in any sample.

Development of a loose powder sintering method for the preparation of porous ceramic from municipal solid waste incineration fly ash.

Loose powder sintering was used to prepare porous ceramic from municipal solid waste incineration fly ash (MSWI FA) and waste glass (WG). Sintering experiments at various temperatures, holding times, Al2O3 and SiC were conducted to investigate their effect on the ceramic properties and volatile heavy metal removal efficiency. The results show that increasing temperature from 1100 °C to 1250 °C promoted the transition of the mixtures from loose powder to a densified sintered matrix, with a bulk density increase of 31.10% and an open porosity decrease of 70.41%. The bulk density of the ceramic increased to 2.44 g/cm3 with 3% Al2O3 addition. The removal rates of Pb, Zn, Cu and Cd were higher than 90% at 1200 °C for 90 min, and promoted by the increasing temperature and holding time. Notably, 3% Al2O3 addition inhibited the volatilisation of Zn, Cu and Cd, particularly for Zn, the removal rate of which reduced to 61.66% at 1200 °C. The bulk density of the ceramic decreased to a minimum value of 1.48 g/cm3 with 4% SiC. The ratio of MSWI FA:WG:Al2O3:borax of 28.3:56.7:10:5 was proposed to obtain ceramic with a bulk density of 1.54 g/cm3 and a water absorption rate of 8.59% at 1150 °C. The leaching concentration of the porous ceramic met the Chinese regulatory standard (GB 8978-1996). Preparation of MSWI FA-based porous ceramics using the powder sintering method is a promising route for the harmless utilisation of MSWI FA. The porous ceramic is potentially applicable as a thermal-insulation building material.

Enhanced arsenic(III) sequestration via sulfidated zero-valent iron in aerobic conditions: Adsorption and oxidation coupling processes.

Sulfidated zero-valent iron (S-ZVI) has shown significant potential for the removal of arsenic(III). However, little attention has been paid to the mechanism of As(III) sequestration enhancement and how the phase transformation for S-ZVI strengthens this process in aerobic conditions. In this work, sulfidated ZVI was created by ball-milling (S-ZVIbm) and liquid-mixing (S-ZVIlm) of ZVI with elemental sulfur(S0) to investigate the performance and mechanisms of As(III) sequestration in air-saturated water. Sulfidation was found to significantly enhance the As(III) removal rate constant, which was 2.8 âˆ¼ 6.7 times (S-ZVIbm) and 3.1 âˆ¼ 17.1 times (S-ZVIlm) higher than that without sulfidation. FeS was identified as the predominant sulfur species in the S-ZVI samples using S K-edge XANES spectra. The enhanced electron transfer and ZVI corrosion after sulfidation were verified via electrochemical tests. XANES and Mössbauer spectra suggested that lepidocrocite(γ-FeOOH) was the predominant corrosion product generated on the ZVI surface with the presence of oxygen, and DFT calculations further confirmed the improved performance of γ-FeOOH for As(III) sequestration. Besides, As(III) oxidation occurred dominantly on the heterogeneous surface rather than in solution, and the As(III) sequestration pathway of adsorption followed by oxidation was proposed. This study provides new insight into the enhanced As(III) sequestration by S-ZVI in aerobic conditions.