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Fine particulate matter (PM 2.5 ) harms human health and hinders normal human life. Considering the serious complexity and obvious regional characteristics of PM 2.5 pollution, it is urgent to fill in the comprehensive overview of regional characteristics and interannual evolution of PM 2.5 . This review studied the PM 2.5 pollution in six typical areas between 2014 and 2022 based on the data published by the Chinese government and nearly 120 relevant literature. We analyzed and compared the characteristics of interannual and quarterly changes of PM 2.5 concentration. The Beijing-Tianjin-Hebei region (BTH), Yangtze River Delta (YRD) and Pearl River Delta (PRD) made remarkable progress in improving PM 2.5 pollution, while Fenwei Plain (FWP), Sichuan Basin (SCB) and Northeast Plain (NEP) were slightly inferior mainly due to the relatively lower level of economic development. It was found that the annual average PM 2.5 concentration change versus year curves in the three areas with better pollution control conditions can be merged into a smooth curve. Importantly, this can be fitted for the accurate evaluation of each area and provide reliable prediction of its future evolution. In addition, we analyzed the factors affecting the PM 2.5 in each area and summarize the causes of air pollution in China. They included primary emission, secondary generation, regional transmission, as well as unfavorable air dispersion conditions. We also suggested that the PM 2.5 pollution control should target specific industries and periods, and further research need to be carried out on the process of secondary production. The results provided useful assistance such as effect prediction and strategy guidance for PM 2.5 pollution control in Chinese backward areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

An important way to promote the environmental industry's goal of carbon reduction is to promote the recycling of resources. Membrane separation technology has unique advantages in resource recovery and advanced treatment of industrial wastewater. However, the great promise of traditional organic membrane is hampered by challenges associated with organic solvent tolerance, lack of oxidation resistance, and serious membrane fouling control. Moreover, the high concentrations of organic matter and inorganic salts in the membrane filtration concentrate also hinder the wider application of the membrane separation technology. The emerging cost-effective graphene oxide (GO)-based membrane with excellent resistance to organic solvents and oxidants, more hydrophilicity, lower membrane fouling, better separation performance has been expected to contribute more in industrial wastewater treatment. Herein, we provide comprehensive insights into the preparation and characteristic of GO membranes, as well as current research status and problems related to its future application in industrial wastewater treatment. Finally, concluding remarks and future perspectives have been deduced and recommended for the GO membrane separation technology application for industrial wastewater treatment, which leads to realizing sustainable wastewater recycling and a nearly "zero discharge" water treatment process., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Mechanism of microbiome assembly and function driven by cathode potential in electro-stimulated microbial reductive dechlorination system remain poorly understood. Here, core microbiome structure, interaction, function and assembly regulating by cathode potential were investigated in a 2,4,6-trichlorophenol bio-dechlorination system. The highest dechlorination rate (24.30 μM/d) was observed under - 0.36 V with phenol as a major end metabolite, while, lower (-0.56 V) or higher (0.04 V or -0.16 V) potentials resulted in 1.3-3.8 times decreased of dechlorination kinetic constant. The lower the cathode potential, the higher the generated CH 4 , revealing cathode participated in hydrogenotrophic methanogenesis. Taxonomic and functional structure of core microbiome significantly shifted within groups of - 0.36 V and - 0.56 V, with dechlorinators (Desulfitobacterium, Dehalobacter), fermenters (norank_f_Propionibacteriaceae, Dysgonomonas) and methanogen (Methanosarcina) highly enriched, and the more positive interactions between functional genera were found. The lowest number of nodes and links and the highest positive correlations were observed among constructed sub-networks classified by function, revealing simplified and strengthened cooperation of functional genera driven by group of - 0.36 V. Cathode potential plays one important driver controlling core microbiome assembly, and the low potentials drove the assembly of major dechlorinating, methanogenic and electro-active genera to be more deterministic, while, the major fermenting genera were mostly governed by stochastic processes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

In groundwater environments, the interaction between microbial communities and the hydrogeochemical parameters have been investigated extensively in the past years. However, little is known whether the maximum contamination level (MCL) is a threshold value that dictates the microbial composition. In this study, we analyzed 10 groundwater samples for their nitrate, nitrite, COD and sulfate concentrations, and characterized their microbial compositions using 16 S rRNA based high-throughput sequencing methods. All the 10 samples had oxygen demands higher than the corresponding MCL of China (10 mg L -1 ); moreover, 4 out of 10 samples also had nitrate concentrations higher than the corresponding MCL, which indicated that the groundwater quality was negatively impacted by anthropogenic activities. Comparing the microbial composition of groundwater that had higher-than-MCL nitrate concentrations to those that had lower-than-MCL nitrate concentrations, no significant differences were detected in communities' richness and diversity. However, the non-metric multi-dimensional analysis suggested that the 4 groundwater samples whose nitrate concentration exceed MCL are distinctly different from those of the rest 6 samples, indicating that MCL does have a significant impact on microbial structures. Pearson's correlation analysis suggested that none of the four analyzed hydrochemical parameters had significant impact on microbial communities' richness and diversity; however, at the genus level, the correlation results suggested that JG30-KM-CM45, Sphingomonas and Rhodococcus are closely correlated with nitrate concentration. The findings of this study deepened our understanding with respect to the relationships between the environmental quality indices and the microbial compositions of groundwater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Although the contamination of microplastics (MPs) in groundwater has been anticipated, their occurrence, distribution, and composition require further understanding. In this study, the occurrence and distributions of MPs were investigated in shallow groundwater from an important water source district in Tianjin city of northern China. The abundance, the physical morphology, the chemical composition, and the potential correlations of the determined MPs with human activities were thoroughly characterized. MPs were determined from all ten sampling sites with the abundance ranged between 17.0 ± 2.16 to 44.0 ± 1.63 n/L, revealing the ubiquitous existed MPs contamination. Based on the physical categorization, fiber (44.74%) was the most abundant shape, while blue (31.02%) and transparent (26.09%) were the most prevalent colors. The dominant size of MPs was smaller than 200 μm which accounted for 73.10%. A total of seven types of MPs were determined with polyethylene, polyethylene terephthalate, and polystyrene as the main types, of which, polypropylene showed strong positive correlations with polystyrene, indicating the possible similar sources of them. Besides, the determined MPs in groundwater were greater in areas with the high population density and strong population activity, indicating their high correlation with human activity. The study highlighted the presence of MPs in groundwater of drinking water source in northern China and provided useful information for evaluating the potential ecological effects on water quality safety and human health brought by MPs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Tetrabromobisphenol A (TBBPA), a hazardous and persistent flame retardant, has been widely detected in the natural aquatic system. The acceleration of reductive debromination (rate-limiting process) is vital during the decomposition and detoxification of TBBPA. This study achieved superior TBBPA electrochemical reductive debromination performance by nano Pd doped Ni foam electrode (4.8 times higher than Ni foam electrode). The optimal TBBPA reductive debromination performance was obtained under -1.2 V of cathode potential, 1.2 wt% of Pd loading, 10 mg L -1 of TBBPA and 100 mM of Na 2 SO 4 as the electrolyte solution. UPLC-QTOF-MS verified that Br atoms in TBBPA were removed sequentially to form bisphenol A as the major product. Most TBBPA was reductively debrominated by atomic H* through indirect hydrodebromination, evidenced by the atomic H* quenching test. The higher solution conductivity and appropriate TBBPA concentration would contribute to the debromination efficiency. Excessive H 2 generation whether by over negative potential or H atom richness electrolyte largely disturbed the reaction process and restricted the debromination. The improved generation of reductant (H*) ads Pd was the most significant, while excessive Pd loading would make aggregation and limit the debromination efficiency. The study confirmed the optimization strategies of conditions for Pd/Ni foam electrode and revealed the related function mechanism for stimulating TBBPA electrochemical reduction, giving suggestions for the efficient removal of TBBPA in the aquatic environment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The response of the denitrification community to long-term antibiotic exposure requires further investigation. Here, the significantly altered denitrifying community structure and function were observed by continuous exposure to 1 mg/L sulfamethoxazole (SMZ) or chlortetracycline (CTC) for 180 d in the expanded granular sludge bed reactors. Thaurea, positively correlated with SMZ and NO 3 - removal efficiency (NrE), was highly enriched in the SMZ-added reactor, while, Comamons and Acinetobacter were largely inhibited. The acute inhibited and then gradual-recovered NrE (87.17-90.38 %) was observed with highly expressed narG, indicating the adaptability of Thaurea to SMZ. However, the abundance of Thaurea and Comamonas greatly decreased, while Melioribacter and Acinetobacter were largely enriched in the CTC-added reactor. CTC created more serious and continuous inhibition of NO 3 - reduction (NrE of 64.53-66.95 %), with lowly expressed narG. Improved NO 2 - reduction capacity was observed in both reactors (70.16-95.42 %) with highly expressed nirS and nosZ, revealing the adaptability of NO 2 - reduction populations to antibiotics., (Copyright © 2021. Published by Elsevier Inc.)

Tetrabromobisphenol A (TBBPA) has aroused widespread pollution in industrial wastewater. Microbial fuel cell (MFC) was proved powerful in organics degradation and simultaneous resource recovery during wastewater treatment. However, the TBBPA biotransformation potential, pathway and the related molecular mechanism remain poorly understood. In this study, the enhanced degradation and detoxification performance of TBBPA in MFC anode was confirmed, evidenced by the shorter degradation period (2.3 times shorter) and less generation of bisphenol A. UPLC-QTOF-MS analysis verified TBBPA metabolism went through reductive debromination, hydrolytic debromination, oxidative ring cleavage and o-methylation. Accompanied with those biochemical processes, the metabolites underwent dynamic changes. The distinctly decreased abundance and fewer interactions with other functional genera for the potential reductive dehalogenators (Pseudomonas, etc.) possibly led to the suppressed reductive debromination (5.1%) in the closed bioanode. Otherwise, the more abundant potential function bacteria with more collaborated interrelations, including hydrolytic dehalogenators (Acinetobacter, etc.), aromatics degrading bacteria (Geobacter, Holophaga, etc.) and electroactive bacteria (Geobacter, Desulfovibrio, etc.) made great sense to the enhanced hydrolytic debromination and detoxification of TBBPA. This study revealed that MFC anode was beneficial to TBBPA degradation and provided theoretical support for the decomposition and transformation of micro-pollutants in the municipal sewage treatment coupled with MFC process., (Copyright © 2021. Published by Elsevier B.V.)

The excess organic carbon is often added to meet denitrification requirements during municipal wastewater treatment, resulting in the carbon waste and increased risk of secondary pollution. In this study, microbial fuel cell (MFC) was coupled with an up-flow denitrification biofilter (BF), and the long-term performances of denitrification and power output were investigated under the different carbon source concentration. With sodium acetate (NaAc) of 600 mg/L and 300 mg/L, the favorable denitrification efficiencies were obtained (98.60%) and the stable current output was maintained (0.44 mÃ0.48 mA). By supplying NaAc of 150 mg/L, the high denitrification efficiency remained in a high range (89.31%) and the current output maintained at 0.12 mA, while, the denitrification efficiency dropped to 71.34% without coupling MFC. Electron balance analysis indicated that both nitrate removal and electron recovery efficiencies were higher in MFC-BF than that in BF, verifying the improved denitrification and carbon utilization performance. Coupling MFC significantly altered the bacterial community structure and composition, and while, the diversified abundance and distribution of bacterial genera were observed at the different locations. Compared with BF, the more exoelectrogenic genera (Desulfobacterium, Trichococcus) and genera holding both denitrifying and electrogenic functions (Dechloromonas, Geobacter) were found dominated in MFC-BF. Instead, the dominating genera in BF were Dechloromonas, Desulfomicrobium, Acidovorax and etc. By coupling MFC, the more complex and diversified network and the closer interaction relationships between the dominant potential functional genera were found. The study provides a feasible approach to effectively improve the denitrification efficiency and organic carbon recovery for deep denitrification process., (Copyright © 2020. Published by Elsevier Inc.)

Reducing the use of liquid organic carbon electron donors during biostimulation of heterotrophic denitrification is critical for sustainable groundwater remediation. Solid-phase humin isolated from natural sources can provide a cost-effective alternative to classical electron donors. In this study, the low-temperature denitrification capacity of an acetate-fed microbial community was enhanced using humin at 20 °C and 10 °C. These enhancements were not caused by faster acetate consumption and greater bacterial growth with the addition of humin. Estimation of the electron balance and first-order kinetics suggested that the enhancement in denitrification occurred mainly after acetate exhaustion. Humin may therefore have acted as an additional electron donor for the denitrifying microbial community, with the reduced quinone group in humin potentially responsible for electron donation. The addition of humin increased the richness and diversity of the denitrifying microbial community, in which Dechloromonas spp. played a critical role. Given the prevalence of humin and denitrifiers using humic substances, our results have important implications in the bioremediation of nitrate-contaminated groundwater using less liquid organic carbon electron donors., (Copyright © 2020 Elsevier Inc. All rights reserved.)

To characterize the impact of reactor configuration and influent loading on elemental sulphur (S 0 ) recovery during denitrification desulfurization, a laboratory-scale expanded granular sludge bed (EGSB) reactor was established under two influent acetate/nitrate/sulphide loadings; the water flow velocity, microbial community, and functional genes at different heights were investigated. There was no S 0 generated when acetate/nitrate/sulphide loadings were set to 0.95/0.60/1.05 kg/m 3 .d (low-loading). Furthermore, there were no typical denitrifying sulphide oxidizing bacteria under this condition, and Syntrophobacter, Anaerolineaceae genera were predominant in the reactor. As the influent loading was doubled (high-loading), S 0 recovery increased to 87%; the bacterial distribution was relatively homogeneous with sulphide oxidation genera (Thauera) being predominant. Neither nirK nor sqr genes were detected in the low-loading sample at a height of 50 cm. The sqr/sox ratios of low-loading stage were 2.50 (10 cm), 0.94 (30 cm), and 0 (50 cm), and the ratios of the high-loading stage were 1.38 (10 cm), 1.33 (30 cm), and 1.08 (50 cm). A hydrodynamics analysis indicated that the water flow velocity was homogenous throughout the reactor. Appropriate reactor configuration and operation parameters play an important role in the efficient regulation of S 0 recovery during denitrification desulfurization., (Copyright © 2020. Published by Elsevier Inc.)

Antibiotics commonly exist in municipal, livestock and industrial wastewaters. However, the response of key microbiota performance in wastewater treatment plants to antibiotic exposure lacks systematic research. In this study, the short-term acute stress of four commonly used antibiotics (sulfamethoxazole, chlortetracycline, ciprofloxacin, and amoxicillin) on microbial denitrification performance was systematically investigated. All tested antibiotics exhibited the inhibitory effects in varying degrees by repeated addition for six cycles. The nitrate removal efficiencies (NrE) decreased to 7.98-26.80%, accompanied by the significant decrease of the expressed narG gene, by exposure to sulfamethoxazole, chlortetracycline or amoxicillin. Nitrite reduction was inhibited more severely than nitrate reduction, which was further verified by the low- or non-expressed nirS and nosZ genes. Furthermore, a higher antibiotic concentration made stronger inhibitory effect. Except for chlortetracycline, 2.09-6.80 times decrease of k value was commonly observed as concentration increased from 10 to 50 or 100 mg L -1 . Even in a short period (24 h), antibiotics largely decreased the abundance of the dominant denitrifying bacterial genera (Thauera, Comamonas, etc.), while, some unclassified populations (Labrenzia, Longilinea, etc.) were enriched. This study provides theoretical researches on the microbial denitrification behaviors influenced by exposure to different antibiotics., (Copyright © 2020. Published by Elsevier B.V.)

An electrostimulated anaerobic-oxic integrated system was constructed for treating alizarin yellow R (AYR) containing wastewater. In electro-stimulated anaerobic unit, AYR decolorization efficiency improved from 51.2% to 96.6%. Two amination metabolites, p-phenylenediamine and 5-aminosalicylic acid, went through oxidation, ammonification and mineralization in oxic unit. Electro-stimulation promoted denitrification and COD removal efficiencies by 15.5% and 8.6%, respectively. A 20% improved nitrification efficiency was observed in oxic unit, due to elimination of AYR toxicity inhibition. No corrosion of heat-treated stainless steel occurred during the 60 days of continuous operation. Electrons sunk in denitrification and decolorization accounted for 34.4-36.8% of those released from COD removal, and 7.3% increase of removed nitrogen in nitrogenous compounds (AYR, nitrate and ammonia) was found. Electro-stimulated anaerobic unit predominated with fermentation and denitrification genera (Propionispira, Rhodocyclus, etc.) and aboundance of electro-active decolorization genus (Desulfovibrio, etc.) increased. Ammonia-oxidizing genus, Comamonas, was the most abundant in aerobic unit. Compared to the suspension, the electrostimulation could increased the abundance of electro-active genera in cathodic biofilm. This study revealed the feasibility of applying electro-stimulation and the conversion laws of nitrogenous organics in secondary bio-treatment system for treating toxic nitrogenous organics-contained wastewater., Competing Interests: Declaration of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Expanded granular sludge blanket (EGSB) is regarded as a promising reactor to carry out denitrifying sulfide removal (DSR) and elemental sulfur (S 0 ) recovery. Although the recirculation ratio is an essential parameter for EGSB reactors, how it impacts the DSR process remains poorly understood. Here, three lab-scale DSR-EGSB reactors were established with the different recirculation ratios (3:1, 6:1 and 9:1) to evaluate the corresponding variations in pollutant removal, S 0 recovery, anaerobic granular sludge (AGS) characteristics and microbial community composition. It was found that an intermediate recirculation ratio (6:1) could facilitate long-term reactor stability. Adequate recirculation ratio could enhance S 0 recovery, but an excessive recirculation ratio (9:1) was likely to cause AGS fragmentation and biomass loss. The S 0 desorbed more from sludge at higher recirculation ratios, probably due to the enhanced hydraulic disturbance caused by the increased recirculation ratios. At the low recirculation ratio (3:1), S 0 accumulation as inorganic suspended solids in AGS led to a decrease in VSS/TSS ratio and mass transfer efficiency. Although typical denitrifying and sulfide-oxidizing bacteria (e.g., Azoarcus, Thauera and Arcobacter) were predominant in all conditions, facultative and heterotrophic functional bacteria (e.g., Azoarcus and Thauera) were more adaptable to higher recirculation ratios than autotrophs (e.g., Arcobacter, Thiobacillus and Vulcanibacillus), which was conducive to the formation of bacterial aggregates to response to the increased recirculation ratio. The study revealed recirculation ratio regulation significantly impacted the DSR-EGSB reactor performance by altering AGS characteristics and microbial community composition, which provides a novel strategy to improve DSR performance and S 0 recovery., (Copyright © 2019. Published by Elsevier Inc.)

The enrichment of specific pollutant-reducing consortium is usually required prior to the startup of biocathode bioelectrochemical system (BES) and the whole process is time consuming. To rapidly establish a non-specific functional biocathode, direct polar inversion from bioanode to biocathode is proposed in this study. Based on the diverse reductases and electron transfer related proteins of anode-respiring bacteria (ARB), the acclimated electrochemically active biofilm (EAB) may catalyze reduction of different aromatic pollutants. Within approximately 12 d, the acclimated bioanodes were directly employed as biocathodes for nitroaromatic nitrobenzene (NB) and azo dye acid orange 7 (AO7) reduction. Our results indicated that the established biocathode significantly accelerated the reduction of NB to aniline (AN) and AO7 to discolored products compared with the abiotic cathode and open circuit controls. Several microbes possessing capabilities of nitroaromatic/azo dye reduction and bidirectional electron transfer were maintained or enriched in the biocathode communities. Cyclic voltammetry highlighted the decreased over-potentials and enhanced electron transfer of biocathode as well as demonstrated the ARB Geobacter containing cytochrome c involved in the backward electron transfer from electrode to NB. This study offers new insights into the rapid establishment and modularization of functional biocathodes for the potential treatment of complicated electron acceptors-coexisting wastewaters., (Copyright © 2017 Elsevier B.V. All rights reserved.)

To characterize the impact of influent loading on elemental sulfur (S 0 ) recovery during the denitrifying and sulfide oxidation process, three identical, lab-scale UASB reactors (30cm in length) were established in parallel under different influent acetate/nitrate/sulfide loadings, and the reactor performance and functional community structure were investigated. The highest S 0 recovery was achieved at 77.9% when the acetate/nitrate/sulfide loading was set to 1.9/1.6/0.7kgd -1 m -3 . Under this condition, the genera Thauera, Sulfurimonas, and Azoarcus were predominant at 0-30, 0-10 and 20-30cm, respectively; meanwhile, the sqr gene was highly expressed at 0-30cm. However, as the influent loading was halved and doubled, S 0 recovery was decreased to 27.9% and 45.1%, respectively. As the loading was halved, the bacterial distribution became heterogeneous, and certain autotrophic sulfide oxidation genera, such as Thiobacillus, dominated, especially at 20-30cm. As the loading doubled, the bacterial distribution was relatively homogeneous with Thauera and Azoarcus being predominant, and the nirK and sox genes were highly expressed. The study verified the importance of influent loading to regulate S 0 recovery, which could be achieved as Thauera and Sulfurimonas dominated. An influent loading that was too low or too high gave rise to insufficient oxidation or over-oxidation of the sulfide and low S 0 recovery performance., (Copyright © 2016 Elsevier B.V. All rights reserved.)