Pathways and contributions of sulfate reducing-bacteria to arsenic cycling in landfills.

Sulfate-reducing bacteria (SRB) are generally found in sanitary landfills and play a role in sulfur (S) and metal/metalloid geochemical cycling. In this study, we investigated the influence of SRB on arsenic (As) metabolic pathways in refuse-derived cultures. The results indicated that SRB promote As(III) methylation and are beneficial for controlling As levels. Heterotrophic and autotrophic SRB showed significant differences during As cycling. In heterotrophic SRB cultures, the As methylation rate increased with As(III) concentration in the medium and reached a peak (85.1%) in cultures containing 25 mg L-1 As(III). Moreover, 4.0-12.6% of SO42- was reduced to S2-, which then reacted with As(III) to form realgar (AsS). In contrast, autotrophic SRB oxidized As(III) to less toxic As(V) under anaerobic conditions. Heterotrophic arsM-harboring SRB, such as Desulfosporosinus, Desulfocurvibacter, and Desulfotomaculum, express As-related genes and are considered key genera for As methylation in landfills. Thiobacillus are the main autotrophic SRB in landfills and can derive energy by oxidizing sulfur compounds and metal(loid)s. These results suggest that different types of SRB drive As methylation, redox reaction, and mineral formation in landfills. These study findings have implications for the management of As pollutants in landfills and other contaminated environments.

Green synthesis of Fe3O4@ceramsite from sludge improving anaerobic digestion performance of waste activated sludge.

Anaerobic digestion (AD) is a promising technique for waste management, which can achieve sludge stabilization and energy recovery. This study successfully prepared Fe3O4@ceramsite from WAS and applied it as an additive in sludge digestion, aiming to improve the conversion of organics to biomethane efficiency. Results showed that after adding the Fe3O4@ceramsite, the methane production was enhanced by 34.7% compared with the control group (88.0 ± 0.1 mL/g VS). Further mechanisms investigation revealed that Fe3O4@ceramsite enhanced digesta stability by strong buffering capacity, improved sludge conductivity, and promoted Fe (III) reduction. Moreover, Fe3O4@ceramsite has a larger surface area and better porous structure, which also facilitated AD performance. Microbial community analysis showed that some functional anaerobes related to AD such as Spirochaeta and Smithella were enriched with Fe3O4@ceramsite treatment. Potential syntrophic metabolisms between syntrophic bacteria (Syntrophomonas, associated with DIET) and methanogens were also detected in the Fe3O4@ceramsite treatment AD system.

Distribution and survival of pathogens from different waste components and bioaerosol traceability analysis in household garbage room.

Household garbage rooms release abundant bioaerosols and are an important source of pathogens; however, information on the distribution and survival patterns of pathogens in different waste components is limited. In this study, a culture method and 16S rRNA high-throughput sequencing were used to determine bacterial communities, culturable pathogens, and human bacterial pathogens (HBPs). The results showed that abundant culturable bacteria were detected in all waste types, and a large number of S. aureus was detected on the surface of recyclable wastes, whereas S. aureus, total coliforms, Salmonella, Enterococcus, and hemolytic bacteria were detected in food waste and other waste. The activities of these detected pathogenic bacteria decreased after 24 h of storage but re-activated within one week. Factors affecting the emergence of pathogens varied with different waste components. Sequencing results showed that Pseudomonas, Acinetobacter, and Burkholderia were abundant in the waste samples, whereas Achromobacter, Exiguobacteriums, Bordetella, and Corynebacterium were the primary pathogens in the bioaerosol and wall attachment. The results of traceability analysis showed that bioaerosol microbes were mainly derived from raw kitchen waste (5.98%) and plastic and paper contaminated with food waste (19.93%) in garbage rooms. In addition, bioaerosols were the main source of microflora in the wall attachment, which possessed high HBP diversity and required more attention. These findings will help in understanding the microbial hazards in different waste components and provide guidance for the control and risk reduction of bioaerosols during waste management and recycling.

Evaluation of pathogen spread risk from excavated landfill.

Landfill is a huge pathogen reservoir and needs special attention. Herein, the distribution and spread risk of pathogen were assessed in excavated landfill scenario. The results show that landfill excavation will greatly increase the risk of environmental microbial contamination. The highest total concentration of culturable bacteria among landfill refuse, topsoil and plant leaves was found to be as high as 1010 CFU g-1. Total coliforms, Hemolytic bacteria, Staphylococcus aureus, Salmonella, Enterococci, and Fecal coliforms were detected in the landfill surrounding environment. Notably, pathogens were more likely to adhere to plant leaves, making it an important source of secondary pathogens. The culturable bacteria concentration in the air samples differed with the landfill zone with different operation status, and the highest culturable bacteria concentration was found in the excavated area of the landfill (3.3 × 104 CFU m-3), which was the main source of bioaerosol release. The distribution of bioaerosols in the downwind outside of the landfill showed a tendency of increasing and then decreasing, and the highest concentration of bioaerosols outside of the landfill (6.56 × 104 CFU m-3) was significantly higher than that in the excavated area of the landfill. The risk of respiratory inhalation was the main pathway leading to infection, whereas the HQin (population inhalation hazardous quotient) at 500 m downwind the excavation landfill was still higher than 1, indicating that the neighboring residents were exposed to airborne microbial pollutants. The results of the study provide evidence for bioaerosols control protective measures taken to reduce health risk from the excavated landfill.

Source analysis of chlorine in municipal solid waste under waste classification: a case study of Hangzhou, China.

Inorganic chlorine is susceptible to water and soil salinization due to its non-degradability and high mobility. To clarify the environmental risks associated with the active inorganic chlorine in municipal solid waste (MSW), the specific characteristics and contributions of inorganic chlorine in different MSW categories were investigated in this study. MSW samples were collected from eight representative waste classification residential areas in Hangzhou, China. It was found that the inorganic chlorine content in different MSW categories varied significantly (0-113 mg/g). Perishable waste, paper, and plastic were found to be the main sources of inorganic chlorine in MSW. A four-category classification system was used to quantify the contribution of inorganic chlorine from each waste category. It was found that the misclassification of inorganic chlorine contributions from perishable waste and other waste accounted for 51.96% and 48.04%, respectively. However, when correctly classified into the four-category system, their contributions were reduced to 67.14% and 30.65%, respectively. Therefore, MSW classification showed a significant reduction in the overall contribution of inorganic chlorine. The misclassification reduces the contribution of inorganic chlorine to 48.04%, while correct classification increases the reduction to 69.35%.

Enhanced removal of toluene in heterogeneous aquifers through injecting encapsulated ozone micro-nano bubble water.

Organic contaminants have a tendency to accumulate in low-permeability aquifers, making their removal challenging and creating a bottleneck in groundwater remediation efforts. The use of ozone micro-nano bubbles, due to their smaller size compared to traditional macrobubbles, shows potential for efficient penetration into the low-permeability aquifer and effective oxidization of contaminants. This study conducted batch experiments, column studies, and 2D tank experiments to systematically investigate the remediation efficiency of toluene in a heterogeneous aquifer using ozonated water (OW), ozone micro-bubble water (OMBW), and encapsulated ozone micro-nano bubble water (EOMBW) with rhamnolipid. Experimental results showed that rhamnolipid effectively increased the densities and reduced the sizes of micro-nano bubbles, leading to improved ozone preservation and enhanced toluene degradation. Nanobubbles exhibited higher mobility compared to microbubbles in porous media, while rhamnolipid increased the density of penetrated nanobubbles by 9.6 times. EOMBW demonstrated superior efficiency in oxidizing toluene in low-permeability aquifers, and a numerical model was developed to successfully simulate the ozone and toluene concentration. The model revealed that the increased oxidation rate by EOMBW was attributed to the preservation of ozone in micro-nano bubbles and the enhanced toluene oxidation rate. These findings contribute significantly to the application of EOMBW in heterogeneous aquifer remediation.

Transformation behavior of heavy metal during Co-thermal treatment of hazardous waste incineration fly ash and slag/electroplating sludge.

In this study, the behavior of heavy metal transformation during the co-thermal treatment of hazardous waste incineration fly ash (HWIFA) and Fe-containing hazardous waste (including hazardous waste incineration bottom slag (HWIBS) and electroplating sludge (ES)) was investigated. The findings demonstrated that such a treatment effectively reduced the static leaching toxicity of Cr and Pb. Moreover, when the treatment temperature exceeded 1000 °C, the co-thermal treated sample exhibited low concentrations of dynamically leached Cr, Pb, and Zn, indicating that these heavy metals were successful detoxified. Thermodynamic analyses and phase transformation results suggested that the formation of spinel and the gradual disappearance of chromium dioxide in the presence of Fe-containing hazardous wastes contributed to the solidification of chromium. Additionally, the efficient detoxification of Pb and Zn was attributed to their volatilization and entry into the liquid phase during the co-thermal treatment process. Therefore, this study sets an excellent example of the co-thermal treatment of hazardous wastes and the control of heavy metal pollution during the treatment process.

Sulfate reduction behavior in response to landfill dynamic pressure changes.

During the long-term stabilization process of landfills, the pressure field undergoes constant changes. This study constructed dynamic pressure changes scenarios of high-pressure differentials (0.6 MPa) and low-pressure differentials (0.2 MPa) in the landfill pressure field at 25 °C and 50 °C, and investigated the sulfate reduction behavior in response to landfill dynamic pressure changes. The results showed that the pressurization or depressurization of high-pressure differentials caused more significant differences in sulfate reduction behavior than that of low-pressure differentials. The lowest hydrogen sulfide (H2S) release peak concentration under pressurization was only 29.67% of that under initial pressure condition; under depressurization, the highest peak concentration of H2S was up to 21,828 mg m-3, posing a serious risk of H2S pollution. Microbial community and correlation analysis showed that pressure had a negative impact on the sulfate-reducing bacteria (SRB) community, and the SRB community adjusted its structure to adapt to pressure changes. Specific SRBs were further enriched with pressure changes. Differential H2S release behavior under pressure changes in the 25 °C pressure environments were mediated by Desulfofarcimen (ASV343) and Desulfosporosinus (ASV1336), while Candidatus Desulforudis (ASV24) and Desulfohalotomaculum (ASV94) played a key role at 50 °C. This study is helpful in the formulation of control strategies for the source of odor pollution in landfills.

Enhanced biomethane production from waste activated sludge anaerobic digestion by ceramsite and amended Fe2O3 ceramsite.

Wastes recycling and reutilization technique could simultaneously fulfill waste control and energy recovery sustainably, which has attracted increasing attention. This work proposed a novel waste reuse technology utilizing ceramsite and amended Fe2O3-ceramsite made from waste activated sludge (WAS) as additives to promote the yield of methane from WAS anaerobic digestion (AD). Experimental results demonstrated that compared to the control (85.05 ± 0.2 mL CH4/g-VS), the cumulative methane yield was effectively enhanced by 14% and 40% when ceramsite and Fe2O3-ceramsite were added. Further investigation revealed that ceramsite, especially the Fe2O3-ceramsite, enriched the populations of key anaerobes involved in hydrolysis, acidification, and methanogenesis. Meanwhile, potential syntrophic metabolisms between syntrophic bacteria and methanogens were confirmed in the Fe2O3-ceramsite AD system. Mechanisms studies exhibited that ceramsite and Fe2O3-ceramsite reinforced intermediate processes for methane production. The favorable pore structure, enhanced Fe (III) reduction capacity and conductivity also contributed a lot to the AD process.

Microplastic release and sulfate reduction response in the early stage of a simulated landfill.

Landfills are essential facilities for treating and disposing municipal solid waste. They emit sulfur-containing odors and serve as an important sink for a new type of pollutant called microplastics (MPs). This study focused on the initial stage of anaerobic degradation to establish the relationship between the release of MPs and odor generation. Our findings show the rapid release of MPs into the leachate in the early stage of landfill and their predominant accumulation in the leachate sediment. The circulating leachate contained 1.45 times higher concentrations of MPs than the noncirculating leachate, with a peak concentration of 39 items·L-1. In addition, fragmentation of MPs occurred. The percentage of MPs with particle sizes of 2.5-5 mm decreased from 66.70 % to 22.32 %, while those measuring 0.1-0.5 mm increased by 33.12 %. A positive correlation was observed between MP release and sulfate reduction. Although leachate circulation increased the release of MPs, it also reduced the overall release time and total amount of MPs exported from the landfill. Compared with the initial landfill waste, the leachate operation mode, regardless of circulation, resulted in a 6.15-8.93-fold increase in MP release. These findings provide a valuable foundation for the simultaneous regulation of traditional pollutant odor and new pollutants (MPs) in landfills.

Simultaneous Sensing of Velocity and Position of a Moving Light Source Using Metal-Insulator-Semiconductor Structures.

Photodetectors based on semiconductor devices have been widely used to sense light position, intensity, and wavelength. However, monitoring the motion velocity of a light beam generally requires complex integration of device arrays. Here, we report a single device of a simple metal-insulator-semiconductor structure for self-powered sensing not only position but also velocity of a light beam or shadow. A velocity-dependent voltage output between two terminals of the metal is observed. It is attributed to light illumination-induced local surface potential change in semiconductors and the following movement of local charges accumulated in the metal due to capacitive coupling. The amplitude of the velocity-dependent voltage can be facilely modulated by applying a gate voltage. These results shed light on compact devices with multiple sensing functions.

Sulfate reduction behavior in response to changing of pressure coupling with temperature inside landfill.

The behavior of sulfate reduction, which was the source of hydrogen sulfide (H2S) odor, was investigated under changing pressure and temperature conditions inside landfills. The results showed that the release of H2S and methyl mercaptan (MM) was significantly inhibited at 25 °C and 50 °C under pressure, and the highest H2S and MM concentrations released were only 0.82 %-1.30 % and 1.87 %-4.32 % of atmospheric pressure, respectively. Analysis of the microbial community structure and identification of sulfate-reducing bacteria (SRB) revealed that temperature significantly altered the microbial community in the landfill environment, while pressure inhibited some bacteria and induced the growth and reproduction of specific bacteria. Key SRB (Desulfosporosinus-ASV212, Desulfitibacter-ASV1744) mediated differentiated sulfate reduction behavior in the pressure-bearing environment at 25 °C, while key SRB (Dethiobacter-ASV177, Desulfitibacter-ASV2355 and ASV316) were involved at 50 °C. This study provides a theoretical basis for the formulation of landfill gas management and control strategies.

Insight into the impact of industrial waste co-disposal with MSW on groundwater contamination at the open solid waste dumping sites.

Due to the lack of normalized management, industrial waste is often co-disposed at open solid waste dumping sites, which could aggravate the groundwater pollution. In this study, 5 practical open solid waste dumping sites dealing with municipal solid wastes (MSW) (2 of 5) and industrial wastes mixed with MSW (3 of 5) were chosen to investigate the effect of waste co-disposal on the groundwater contamination. The industrial waste was mainly from rubber production, leather production, machinery industry, pharmaceutical industry and plastic production. 3 to 6 groundwater wells were excavated from each dumping site and 148 indices were analyzed, including regular chemicals, heavy metals, biological pollutants, volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs) and pesticide residues. Nemerow index analysis showed that 5 indices were severely polluted in the groundwater from every industrial waste co-disposal landfill, while only 0 and 1 severely polluted index was found for the two MSW landfill, respectively. The principal component analysis (PCA) analysis indicated that 2 biological pollutant (plate-counting bacteria (TPB) and total coliforms (TCs)), 4 chemical pollutants (permanganate index, ammonia, S2- and petroleum) were closely connected with the disposal of industrial waste. Besides, co-disposal of industrial waste also brought in series of PAHs and dichloromethane, with di(2-ethylhexyl)phthalate exceeding the standard limit (10.5 mg L-1). Attention should be paid to TPB and TCs, whose maximal concentrations exceeded the standard limit by extraordinary 3200 and 1600 times, respectively. The distribution pattern of the pollutants showed that the biological pollutants at the downstream area, and chemical pollutants at the leakage points exhibited the highest concentration, which indicated the downstream area and seepage points should be specially concerned for the industry waste co-disposed dumping sites.

Microbial contamination risk of landfilled waste with different ages.

Landfills are reservoirs of antibiotic resistance genes (ARGs) and pathogens, and humans are exposed to these pollutants during extensive excavation of old landfills. However, the microbial contamination risk of landfilled waste with different ages has not been assessed. In this study, human bacterial pathogens (HBPs), ARGs, and virulence factors (VFs) were systematically determined using metagenomic analysis. Results showed that the abundance of HBPs, ARGs, and VFs increased with landfill age, the percentage of HBPs in refuse with deposit age of 10-12 years (Y10) was 23.75 ± 0.49%, which was higher than that in fresh refuse (Y0, 17.99 ± 0.14%) and refuse with deposit age of 5-6 years (Y5, 19.14 ± 0.15%), indicating that old refuse had higher microbial contamination risk than fresh refuse. Multidrug, macrolide, lincosamide, streptogramine, and tetracycline resistance genes were the primary ARGs, whereas lipooligosaccharides, type IV pili, and polar flagella were the dominant VFs in refuse. The HBPs showed a significant positive correlation with ARGs and VFs. Listeria monocytogenes, Salmonella enterica, Streptococcus pneumoniae, Acinetobacter baumannii, and Escherichia coli possibly possess both multiple ARGs and VFs and could be listed as high-risk HBPs in refuse. Mobile genetic elements, especially transposons, showed positive correlations with most ARGs and VFs, and they were identified as the primary factors accounting for the variations in ARGs and VFs. These findings will help understand the spread of ARGs and VFs in landfills and evaluate the potential risk of microbiological contamination in refuse of different landfill ages, thus providing guidance for preventing disease infection during landfill excavations.

Promising valorisation method of chitin biomass by producing 5-hydroxymethylfurfural using microwave hydrothermal treatment.

Chitin biomass is the second largest biomass resource on Earth but under-utilized. In this study, pretreated shrimp shells were converted into value-added platform chemical 5-hydroxymethylfurfural (HMF) using microwave hydrothermal treatment. Under the combined pretreatment of acid decalcification at room temperature and microwave-assisted alkali deacetylation, the HMF yield could reach 1.8 wt%. The key process parameters, including the holding temperature, holding time, and pH value, were evaluated and optimised. The highest HMF yield of 6.5 wt% was obtained at 202.6°C at a holding time of 5.8 min and a pH value of 1.5. This result demonstrates the potential of synchronously treating waste and recycling it, thereby offering a highly promising valorisation strategy for chitin-biomass utilisation.

Metagenomics insights into the effect of co-landfill of incineration fly ash and refuse for bacterial community succession and metabolism pathway of VFAs production.

With the development of incineration technologies, incineration has become the most common treatment method of municipal solid waste in China. However, stabilized fly ash may enter landfills during the transition from landfill to incineration, which caused uncertain impact on landfill waste stabilization. Two simulated co-landfill columns were constructed based on different co-landfill methods (layer co-landfill and mixed co-landfill) to investigate the effect of stabilized fly ash co-landfilled municipal solid waste for bacterial community succession and change in metabolic pathways during hydrolysis-acidogenesis stage. The mixed co-landfill method resulted in higher degree of organic matter degradation, and the concentrations of volatile fatty acids (VFA) and chemical oxygen demand (COD) in leachate were higher. The dominant phyla were Firmicutes in the layered co-landfill column and Bacteroidetes in mixed co-landfill column. The dominant genera for the total bacterial composition and VFA production were different, Pseudomonas and Propionibacterium, Proteiniphilum and unclassified Bacteroides were the dominant genera responsible for VFA generation in the layered and mixed co-landfill columns. The genes for butyrate production were enriched in the layered co-landfill column, whereas those related to acetate production were enriched in mixed co-landfill column. However, the layered co-landfill inhibited the microbial metabolic activity at the end of the co-landfill process.

Co-electron donors driven medium-chain fatty acids production: Roles of electron donors, reaction kinetics and metabolic pathways.

Energy conversion of waste activated sludge alkaline fermentation liquor (WASAFL) to medium-chain fatty acids (MCFAs) is promising for sludge treatment and carbon recovery. However, the single electron donor (ED) fermentation for MCFAs production has irreparable defects. To resolve the respective shortcomings of single electron donor (ED) and improve the MCFAs production efficiency from WASAFL, a novel biotechnical process utilizing ethanol and lactate as co-EDs within different combination ratios were investigated. The results verified that MCFAs production was highest with ethanol to lactate ratio of 1:3 (6988.54 ± 208.18 mg COD/L), being 1.46 and 1.87 times of that with ethanol and lactate as single ED. The kinetic analysis results confirmed that ethanol to lactate ratio of 1:3 resulted in the highest MCFAs yield and formation rate. The microbial taxa results uncovered that the relative abundance of Sphaerochaeta and Haloimpatiens showed positive correlation with MCFAs production. The metabolic pathway analysis indicated that the ethanol oxidization, lactate oxidization, acrylate pathway, reverse ß oxidization and fatty acid biosynthesis pathway might take place in the WASAFL fermentation system, contributing to the WASAFL-to-MCFAs conversion.

Mechanism of antibiotic resistance development in an activated sludge system under tetracycline pressure.

The mechanism of antibiotic resistance (AR) development in an activated sludge system under tetracycline (TC) pressure was discussed and analyzed. According to the variation of macro-factors, including TC, COD, TN, TP, NH3-N, pH, heavy metals, and reactor settings, the tet genes respond accordingly. Consequently, the enrichment sites of tet genes form an invisible AR selection zone, where AR microorganisms thrive, gather, reproduce, and spread. The efflux pump genes tetA and tetB prefer anaerobic environment, while ribosome protective protein genes tetM, tetO, tetQ, tetT, and tetW were more concentrated in aerobic situations. As a corresponding micro-effect, different types of tet genes selected the corresponding dominant bacteria such as Thauera and Arthrobacter, suggesting the intrinsic relationship between tet genes and potential hosts. In summary, the macro-response and micro-effect of tet genes constitute an interactive mechanism with tet genes as the core, which is the crucial cause for the continuous development of AR. This study provides an executable strategy to control the development of AR in actual wastewater treatment plants from the perspective of macro-factors and micro-effects.

Alteration of the migration trajectory of antibiotic resistance genes by microplastics in a leachate activated sludge system.

The environmental behavior of emerging contaminants of microplastics (MPs), antibiotics and antibiotic resistance genes (ARGs) in the leachate activated sludge system has been monitored and analyzed comprehensively. The results suggested that MPs could effectively alter the migration trajectory of tetracycline resistance genes (tet genes) in the leachate activated sludge system under intermittent and continuous influent conditions. After adding MPs, the total average abundance of tet genes in leachate increased from 0.74 ± 0.07 to 0.78 ± 0.07 (log10tet genes/log10 16S rRNA) and that in sludge increased from 0.65 ± 0.08 to 0.70 ± 0.06 (log10tet genes/log10 16S rRNA). Except for tetA, the abundance of tetB, tetO, tetM and tetQ on MPs increased with increasing TC concentration under both aerobic and anaerobic conditions. MPs not only significantly affect the abundance level and migration trajectory of ARGs in the leachate activated sludge system, but also remarkably improve the level of heavy metals in the ambient environment, indirectly promoting the selective effect of antibiotic-resistant bacteria (ARB) and promoting the development of antibiotic resistance (AR). In addition, MPs changed their physicochemical properties and released hazardous substances with aging to force tet genes to migrate from the leachate activated sludge system to the MPs, making AR more difficult to eliminate and persisted in wastewater treatment plants. Meanwhile, microorganisms played a driving role, making MPs serve as a niche for ARGs and ARB colonization. The co-occurrence network analysis indicated the specific distribution pattern of tet genes and microorganisms in different media, and the potential host was speculated. This study improves the understanding of the environmental behavior of emerging contaminants in leachate activated sludge system and lays a theoretical for protecting the ecological environment.

Arsenate microbial reducing behavior regulated by the temperature fields in landfills.

Attention should be paid to the As(V) reducing behavior in landfills under different temperature fields. In this study, microcosm tests were conducted using enrichment culture from a landfill. The results revealed that the reduction rate of As(V) was significantly affected by the temperature field, with the highest reduction rate observed at 50 °C, followed by 35 °C, 25 °C, and 10 °C. Different As cycling pathways were observed under various temperature fields. At room and medium temperatures, As4S4 was detected, indicating that both biomineralization and methylation processes occurred after As(V) reduction. However, only biogenic methylation was observed under high or low temperatures, indicating that the viability and adaptability of microorganisms varied depending on the temperature field and As contents. Pseudomonas was found to be the primary genus and dominant As(V) reduction bacteria (ARB) in all reactors. The study revealed that Pseudomonas accounted for a significant proportion of arsC genes, ranging from 87.29% to 97.59%, while arsCs genes were predominantly found in Bacillales and Closestridiales, with a contribution ranging from 89.17% to 96.59%. Interestingly, Bacillus and Clostridium were found to possess arsA genes in their metagenome-ssembled genome, resulting in a higher As(V) reducing rate under medium and high temperatures. These findings underscore the importance of temperature in modulating As(V) reducing behavior and As cycling, and could have implications for managing As pollution in landfill sites.