Journal home Browse Most Down Articles

Most Down Articles

  • Select all
  • REVIEW ARTICLE
    Jiuhui Qu, Hongchen Wang, Kaijun Wang, Gang Yu, Bing Ke, Han-Qing Yu, Hongqiang Ren, Xingcan Zheng, Ji Li, Wen-Wei Li, Song Gao, Hui Gong
    Frontiers of Environmental Science & Engineering, 2019, 13(6): 88. https://doi.org/10.1007/s11783-019-1172-x

    The history of China’s municipal wastewater management is revisited.

    The remaining challenges in wastewater sector in China are identified.

    New concept municipal wastewater treatment plants are highlighted.

    An integrated plant of energy, water and fertilizer recovery is envisaged.

    China has the world’s largest and still growing wastewater sector and water market, thus its future development will have profound influence on the world. The high-speed development of China’s wastewater sector over the past 40 years has forged its global leading treatment capacity and innovation ability. However, many problems were left behind, including underdeveloped sewers and sludge disposal facilities, low sustainability of the treatment processes, questionable wastewater treatment plant (WWTP) effluent discharge standards, and lacking global thinking on harmonious development between wastewater management, human society and the nature. Addressing these challenges calls for fundamental changes in target design, policy and technologies. In this mini-review, we revisit the development history of China’s municipal wastewater management and identify the remaining challenges. Also, we highlight the future needs of sustainable development and exploring China’s own wastewater management path, and outlook the future from several aspects including targets of wastewater management, policies and technologies, especially the new concept WWTP. Furthermore, we envisage the establishment of new-generation WWTPs with the vision of turning WWTP from a site of pollutant removal into a plant of energy, water and fertilizer recovery and an integrated part urban ecology in China.

  • RESEARCH ARTICLE
    Joana C. Prata, Ana L. Patrício Silva, Armando C. Duarte, Teresa Rocha-Santos
    Frontiers of Environmental Science & Engineering, 2022, 16(1): 5. https://doi.org/10.1007/s11783-021-1439-x

    • Portugal recycles 34% of the 40 kg/hab year of plastic packaging waste.

    • Recycling of plastics in Portugal produces a final revenue of 167 €/t.

    • Recycling and recovery must be the priority for imported wastes.

    • Beach litter must be reduced from 330 to 20 items/100 m (94%) under EU goals.

    • Consumption, use, and waste management of plastics need to improve.

    As a European Union (EU) member, Portugal must comply with reductions in plastic waste. In Portugal, the 330 items/100 m of beach litter, comprising up to 3.9 million pieces and of which 88% is plastic, is higher than the EU median (149 items/100 m) and must be reduced to 20 items/100 m (94%). Integrative measures are needed to reduce littering and improve plastics’ use and disposal under the circular economy. Of this 414 kt of plastic packaging waste, 163 kt were declared plastic packaging, 140 kt subjected to recycling, and 94 kt to energy recovery. The current recycling rate of plastic packaging (34%) should be improved to reach EU recycling averages (42%) and goals and to provide widespread benefits, considering revenues of 167 €/t. As a net importer of waste, Portugal could benefit from the valorization of imported waste. Besides increased recycling, pyrolysis and gasification could provide short-term alternatives for producing value-added substances from plastic waste, such as hydrogen, consistent with the National Plan of Hydrogen and improving ongoing regulations on single-use plastics. This manuscript provides an integrative view of plastics in Portugal, from use to disposal, providing specific recommendations under the circular economy.

  • RESEARCH ARTICLE
    Haiyan Mou, Wenchao Liu, Lili Zhao, Wenqing Chen, Tianqi Ao
    Frontiers of Environmental Science & Engineering, 2021, 15(4): 61. https://doi.org/10.1007/s11783-020-1353-7

    • Separate reduction and sintering cannot be effective for Cr stabilization.

    • Combined treatment of reduction and sintering is effective for Cr stabilization.

    • Almost all the Cr in the reduced soil is residual form after sintering at 1000°C.

    This study explored the effectiveness and mechanisms of high temperature sintering following pre-reduction with ferric sulfate (FeSO4), sodium sulfide (Na2S), or citric acid (C6H8O7) in stabilizing hexavalent chromium (Cr(VI)) in highly contaminated soil. The soil samples had an initial total Cr leaching of 1768.83 mg/L, and Cr(VI) leaching of 1745.13 mg/L. When FeSO4 or C6H8O7 reduction was followed by sintering at 1000°C, the Cr leaching was reduced enough to meet the Safety Landfill Standards regarding general industrial solid waste. This combined treatment greatly improved the stabilization efficiency of chromium because the reduction of Cr(VI) into Cr(III) decreased the mobility of chromium and made it more easily encapsulated in minerals during sintering. SEM, XRD, TG-DSC, and speciation analysis indicated that when the sintering temperature reached 1000°C, almost all the chromium in soils that had the pre-reduction treatment was transformed into the residual form. At 1000°C, the soil melted and promoted the mineralization of Cr and the formation of new Cr-containing compounds, which significantly decreased subsequent leaching of chromium from the soil. However, without reduction treatment, chromium continued to leach from the soil even after being sintered at 1000°C, possibly because the soil did not fully fuse and because Cr(VI) does not bind with soil as easily as Cr(III).

  • REVIEW ARTICLE
    Zhengqing Cai, Xiao Zhao, Jun Duan, Dongye Zhao, Zhi Dang, Zhang Lin
    Frontiers of Environmental Science & Engineering, 2020, 14(5): 84. https://doi.org/10.1007/s11783-020-1263-8

    ▪ Overviewed evolution and environmental applications of stabilized nanoparticles.

    ▪ Reviewed theories on particle stabilization for enhanced reactivity/deliverability.

    ▪ Examined various in situ remediation technologies based on stabilized nanoparticles.

    ▪ Summarized knowledge on transport of stabilized nanoparticles in porous media.

    ▪ Identified key knowledge gaps and future research needs on stabilized nanoparticles.

    Due to improved soil deliverability and high reactivity, stabilized nanoparticles have been studied for nearly two decades for in situ remediation of soil and groundwater contaminated with organic pollutants. While large amounts of bench- and field-scale experimental data have demonstrated the potential of the innovative technology, extensive research results have also unveiled various merits and constraints associated different soil characteristics, types of nanoparticles and particle stabilization techniques. Overall, this work aims to critically overview the fundamental principles on particle stabilization, and the evolution and some recent developments of stabilized nanoparticles for degradation of organic contaminants in soil and groundwater. The specific objectives are to: 1) overview fundamental mechanisms in nanoparticle stabilization; 2) summarize key applications of stabilized nanoparticles for in situ remediation of soil and groundwater contaminated by legacy and emerging organic chemicals; 3) update the latest knowledge on the transport and fate of stabilized nanoparticles; 4) examine the merits and constraints of stabilized nanoparticles in environmental remediation applications; and 5) identify the knowledge gaps and future research needs pertaining to stabilized nanoparticles for remediation of contaminated soil and groundwater. Per instructions of this invited special issue, this review is focused on contributions from our group (one of the pioneers in the subject field), which, however, is supplemented by important relevant works by others. The knowledge gained is expected to further advance the science and technology in the environmental applications of stabilized nanoparticles.

  • REVIEW ARTICLE
    Elham Abaie, Limeimei Xu, Yue-xiao Shen
    Frontiers of Environmental Science & Engineering, 2021, 15(6): 124. https://doi.org/10.1007/s11783-021-1412-8

    •The history of biological and artificial water channels is reviewed.

    •A comprehensive channel characterization platform is introduced.

    •Rationale designs and fabrications of biomimetic membranes are summarized.

    •The advantages, limitations, and challenges of biomimetic membranes are discussed.

    •The prospect and scalable solutions of biomimetic membranes are discussed.

    Bioinspired and biomimetic membranes that contain biological transport channels or attain their structural designs from biological systems have been through a remarkable development over the last two decades. They take advantage of the exceptional transport properties of those channels, thus possess both high permeability and selectivity, and have emerged as a promising solution to existing membranes. Since the discovery of biological water channel proteins aquaporins (AQPs), extensive efforts have been made to utilize them to make separation membranes–AQP-based membranes, which have been commercialized. The exploration of AQPs’ unique structures and transport properties has resulted in the evolution of biomimetic separation materials from protein-based to artificial channel-based membranes. However, large-scale, defect-free biomimetic membranes are not available yet. This paper reviews the state-of-the-art biomimetic membranes and summarizes the latest research progress, platform, and methodology. Then it critically discusses the potential routes of this emerging area toward scalable applications. We conclude that an appropriate combination of bioinspired concepts and molecular engineering with mature polymer industry may lead to scalable polymeric membranes with intrinsic selective channels, which will gain the merit of both desired selectivity and scalability.

  • RESEARCH ARTICLE
    Fei LI,Suocheng DONG,Fujia LI,Libiao YANG
    Frontiers of Environmental Science & Engineering, 2016, 10(2): 276-287. https://doi.org/10.1007/s11783-014-0700-y

    As the largest contributor to water impairment, agriculture-related pollution has attracted the attention of scientists as well as policy makers, and quantitative information is being sought to focus and advance the policy debate. This study applies the panel unit root, heterogeneous panel cointegration, and panel-based dynamic ordinary least squares to investigate the Environmental Kuznets Curve on environmental issues resulting from use of agricultural synthetic fertilizer, pesticide, and film for 31 provincial economies in mainland China from 1989 to 2009. The empirical results indicate a positive long-run co-integrated relationship between the environmental index and real GDP per capita. This relationship takes on the inverted U-shaped Environmental Kuznets Curve, and the value of the turning point is approximately 10,000–13,000, 85,000–89,000 and over 160,000 CNY, for synthetic fertilizer nitrogen indicator, fertilizer phosphorus indicator and pesticide indicator, respectively. At present, China is subject to tremendous environmental pressure and should assign more importance to special agriculture-related environmental issues.

  • REVIEW ARTICLE
    Yunping Han, Lin Li, Ying Wang, Jiawei Ma, Pengyu Li, Chao Han, Junxin Liu
    Frontiers of Environmental Science & Engineering, 2021, 15(3): 38. https://doi.org/10.1007/s11783-020-1330-1

    • Bioaerosols are produced in the process of wastewater biological treatment.

    • The concentration of bioaerosol indoor is higher than outdoor.

    • Bioaerosols contain large amounts of potentially pathogenic biomass and chemicals.

    • Inhalation is the main route of exposure of bioaerosol.

    • Both the workers and the surrounding residents will be affected by the bioaerosol.

    Bioaerosols are defined as airborne particles (0.05–100 mm in size) of biological origin. They are considered potentially harmful to human health as they can contain pathogens such as bacteria, fungi, and viruses. This review summarizes the most recent research on the health risks of bioaerosols emitted from wastewater treatment plants (WWTPs) in order to improve the control of such bioaerosols. The concentration and size distribution of WWTP bioaerosols; their major emission sources, composition, and health risks; and considerations for future research are discussed. The major themes and findings in the literature are as follows: the major emission sources of WWTP bioaerosols include screen rooms, sludge-dewatering rooms, and aeration tanks; the bioaerosol concentrations in screen and sludge-dewatering rooms are higher than those outdoors. WWTP bioaerosols contain a variety of potentially pathogenic bacteria, fungi, antibiotic resistance genes, viruses, endotoxins, and toxic metal(loid)s. These potentially pathogenic substances spread with the bioaerosols, thereby posing health risks to workers and residents in and around the WWTP. Inhalation has been identified as the main exposure route, and children are at a higher risk of this than adults. Future studies should identify emerging contaminants, establish health risk assessments, and develop prevention and control systems.

  • RESEARCH ARTICLE
    Gustaf OLSSON
    Frontiers of Environmental Science & Engineering, 0: 787-793. https://doi.org/10.1007/s11783-013-0526-z

    Water and energy are inextricably linked, and as a consequence both have to be addressed together. This is called the water-energy nexus. When access to either is limited, it becomes obvious that it is necessary to consider their interdependence. Population growth, climate change, urbanization, increasing living standards and food consumption will require an integrated approach where food, water and energy security are considered together. In this paper we examine water, energy and food security and their couplings. The nexus also creates conflicts between water use, energy extraction and generation as well as food production. Some of these conflicts are illustrated. It is argued that there is an urgent need for integrated planning and operation. Not only will better technology be needed, but also better integration of policies, organizations and political decisions.

  • REVIEW ARTICLE
    Shuai Li, Zhiyao Yang, Da Hu, Liu Cao, Qiang He
    Frontiers of Environmental Science & Engineering, 2021, 15(4): 65. https://doi.org/10.1007/s11783-020-1357-3

    • The built environment, occupants, and microbiomes constitute an integrated ecosystem.

    • This review summarizes research progress which has focused primarily on microbiomes.

    • Critical research needs include studying impacts of occupant behaviors on microbiomes.

    Built environments, occupants, and microbiomes constitute a system of ecosystems with extensive interactions that impact one another. Understanding the interactions between these systems is essential to develop strategies for effective management of the built environment and its inhabitants to enhance public health and well-being. Numerous studies have been conducted to characterize the microbiomes of the built environment. This review summarizes current progress in understanding the interactions between attributes of built environments and occupant behaviors that shape the structure and dynamics of indoor microbial communities. In addition, this review also discusses the challenges and future research needs in the field of microbiomes of the built environment that necessitate research beyond the basic characterization of microbiomes in order to gain an understanding of the causal mechanisms between the built environment, occupants, and microbiomes, which will provide a knowledge base for the development of transformative intervention strategies toward healthy built environments. The pressing need to control the transmission of SARS-CoV-2 in indoor environments highlights the urgency and significance of understanding the complex interactions between the built environment, occupants, and microbiomes, which is the focus of this review.

  • VIEWS & COMMENTS
    Elvis Genbo Xu, Zhiyong Jason Ren
    Frontiers of Environmental Science & Engineering, 2021, 15(6): 125. https://doi.org/10.1007/s11783-021-1413-7
  • REVIEW ARTICLE
    Haiyan Yang, Shangping Xu, Derek E. Chitwood, Yin Wang
    Frontiers of Environmental Science & Engineering, 2020, 14(5): 79. https://doi.org/10.1007/s11783-020-1254-9

    • CWF is a sustainable POU water treatment method for developing areas.

    • CWF manufacturing process is critical for its filtration performance.

    • Simultaneous increase of flow rate and pathogen removal is a challenge.

    • Control of pore size distribution holds promises to improve CWF efficiency.

    • Novel coatings of CWFs are a promising method to improve contaminant removal.

    Drinking water source contamination poses a great threat to human health in developing countries. Point-of-use (POU) water treatment techniques, which improve drinking water quality at the household level, offer an affordable and convenient way to obtain safe drinking water and thus can reduce the outbreaks of waterborne diseases. Ceramic water filters (CWFs), fabricated from locally sourced materials and manufactured by local labor, are one of the most socially acceptable POU water treatment technologies because of their effectiveness, low-cost and ease of use. This review concisely summarizes the critical factors that influence the performance of CWFs, including (1) CWF manufacturing process (raw material selection, firing process, silver impregnation), and (2) source water quality. Then, an in-depth discussion is presented with emphasis on key research efforts to address two major challenges of conventional CWFs, including (1) simultaneous increase of filter flow rate and bacterial removal efficiency, and (2) removal of various concerning pollutants, such as viruses and metal(loid)s. To promote the application of CWFs, future research directions can focus on: (1) investigation of pore size distribution and pore structure to achieve higher flow rates and effective pathogen removal by elucidating pathogen transport in porous ceramic and adjusting manufacture parameters; and (2) exploration of new surface modification approaches with enhanced interaction between a variety of contaminants and ceramic surfaces.

  • REVIEW ARTICLE
    Qinghui Sun, Juan Li, Chen Wang, Anqi Chen, Yanli You, Shupeng Yang, Huihui Liu, Guibin Jiang, Yongning Wu, Yanshen Li
    Frontiers of Environmental Science & Engineering, 2022, 16(1): 1. https://doi.org/10.1007/s11783-021-1429-z

    • Microplastics are widely found in both aquatic and terrestrial environments.

    • Cleaning products and discarded plastic waste are primary sources of microplastics.

    • Microplastics have apparent toxic effects on the growth of fish and soil plants.

    • Multiple strains of biodegradable microplastics have been isolated.

    Microplastics (MPs) are distributed in the oceans, freshwater, and soil environment and have become major pollutants. MPs are generally referred to as plastic particles less than 5 mm in diameter. They consist of primary microplastics synthesized in microscopic size manufactured production and secondary microplastics generated by physical and environmental degradation. Plastic particles are long-lived pollutants that are highly resistant to environmental degradation. In this review, the distribution and possible sources of MPs in aquatic and terrestrial environments are described. Moreover, the adverse effects of MPs on natural creatures due to ingestion have been discussed. We also have summarized identification methods based on MPs particle size and chemical bond. To control the pollution of MPs, the biodegradation of MPs under the action of different microbes has also been reviewed in this work. This review will contribute to a better understanding of MPs pollution in the environment, as well as their identification, toxicity, and biodegradation in the ocean, freshwater, and soil, and the assessment and control of microplastics exposure.

  • REVIEW ARTICLE
    Shaoyi Xu, Xiaolong Wu, Huijie Lu
    Frontiers of Environmental Science & Engineering, 2021, 15(6): 133. https://doi.org/10.1007/s11783-021-1426-2

    • AOA and comammox bacteria can be more abundant and active than AOB/NOB at WWTPs.

    • Coupled DNRA/anammox and NOx-DAMO/anammox/comammox processes are demonstrated.

    • Substrate level, SRT and stressors determine the niches of overlooked microbes.

    • Applications of overlooked microbes in enhancing nitrogen removal are promising.

    Nitrogen-cycling microorganisms play key roles at the intersection of microbiology and wastewater engineering. In addition to the well-studied ammonia oxidizing bacteria, nitrite oxidizing bacteria, heterotrophic denitrifiers, and anammox bacteria, there are some other N-cycling microorganisms that are less abundant but functionally important in wastewater nitrogen removal. These microbes include, but not limited to ammonia oxidizing archaea (AOA), complete ammonia oxidation (comammox) bacteria, dissimilatory nitrate reduction to ammonia (DNRA) bacteria, and nitrate/nitrite-dependent anaerobic methane oxidizing (NOx-DAMO) microorganisms. In the past decade, the development of high-throughput molecular technologies has enabled the detection, quantification, and characterization of these minor populations. The aim of this review is therefore to synthesize the current knowledge on the distribution, ecological niche, and kinetic properties of these “overlooked” N-cycling microbes at wastewater treatment plants. Their potential applications in novel wastewater nitrogen removal processes are also discussed. A comprehensive understanding of these overlooked N-cycling microbes from microbiology, ecology, and engineering perspectives will facilitate the design and operation of more efficient and sustainable biological nitrogen removal processes.

  • REVIEW ARTICLE
    Chao Lu, Kanglan Deng, Chun Hu, Lai Lyu
    Frontiers of Environmental Science & Engineering, 2020, 14(5): 82. https://doi.org/10.1007/s11783-020-1261-x

    • Dual-reaction-center (DRC) system breaks through bottleneck of Fenton reaction.

    • Utilization of intrinsic electrons of pollutants is realized in DRC system.

    • DRC catalytic process well continues Fenton’s story.

    Triggered by global water quality safety issues, the research on wastewater treatment and water purification technology has been greatly developed in recent years. The Fenton technology is particularly powerful due to the rapid attack on pollutants by the generated hydroxyl radicals (•OH). However, both heterogeneous and homogeneous Fenton/Fenton-like technologies follow the classical reaction mechanism, which depends on the oxidation and reduction of the transition metal ions at single sites. So even after a century of development, this reaction still suffers from its inherent bottlenecks in practical application. In recent years, our group has been focusing on studying a novel heterogeneous Fenton catalytic process, and we developed the dual-reaction-center (DRC) system for the first time. In the DRC system, H2O2 and O2 can be efficiently reduced to reactive oxygen species (ROS) in electron-rich centers, while pollutants are captured and oxidized by the electron-deficient centers. The obtained electrons from pollutants are diverted to the electron-rich centers through bonding bridges. This process breaks through the classic Fenton mechanism, and improves the performance and efficiency of pollutant removal in a wide pH range. Here, we provide a brief overview of Fenton’s story and focus on combing the discovery and development of the DRC technology and mechanism in recent years. The construction of the DRC and its performance in the pollutant degradation and interfacial reaction process are described in detail. We look forward to bringing a new perspective to continue Fenton’s story through research and development of DRC technology.

  • REVIEW ARTICLE
    Xiaoming Wan, Mei Lei, Tongbin Chen
    Frontiers of Environmental Science & Engineering, 2020, 14(2): 24. https://doi.org/10.1007/s11783-019-1203-7

    • Recent progress of As-contaminated soil remediation technologies is presented.

    • Phytoextraction and chemical immobilization are the most widely used methods.

    • Novel remediation technologies for As-contaminated soil are still urgently needed.

    • Methods for evaluating soil remediation efficiency are lacking.

    • Future research directions for As-contaminated soil remediation are proposed.

    Arsenic (As) is a top human carcinogen widely distributed in the environment. As-contaminated soil exists worldwide and poses a threat on human health through water/food consumption, inhalation, or skin contact. More than 200 million people are exposed to excessive As concentration through direct or indirect exposure to contaminated soil. Therefore, affordable and efficient technologies that control risks caused by excess As in soil must be developed. The presently available methods can be classified as chemical, physical, and biological. Combined utilization of multiple technologies is also common to improve remediation efficiency. This review presents the research progress on different remediation technologies for As-contaminated soil. For chemical methods, common soil washing or immobilization agents were summarized. Physical technologies were mainly discussed from the field scale. Phytoextraction, the most widely used technology for As-contaminated soil in China, was the main focus for bioremediation. Method development for evaluating soil remediation efficiency was also summarized. Further research directions were proposed based on literature analysis.

  • RESEARCH ARTICLE
    Shuyi Wang, Xiang Qi, Yong Jiang, Panpan Liu, Wen Hao, Jinbin Han, Peng Liang
    Frontiers of Environmental Science & Engineering, 2022, 16(8): 97. https://doi.org/10.1007/s11783-022-1518-7

    • Antibiotic azithromycin employed in graphite electrode for EAB biosensor.

    • Azithromycin at 0.5% dosage increased the sensitivity for toxic formaldehyde.

    • Azithromycin increased the relative abundance of Geobacter.

    • Azithromycin regulated thickness of electroactive biofilm.

    Extensive research has been carried out for improved sensitivity of electroactive biofilm-based sensor (EAB-sensor), which is recognized as a useful tool in water quality early-warning. Antibiotic that is employed widely to treat infection has been proved feasible in this study to regulate the EAB and to increase the EAB-biosensor’s sensitivity. A novel composite electrode was prepared using azithromycin (AZM) and graphite powder (GP), namely AZM@GP electrode, and was employed as the anode in EAB-biosensor. Different dosages of AZM, i.e., 2 mg, 4 mg, and 8 mg, referred to as 0.25%, 0.5% and 1% AZM@GP were under examination. Results showed that EAB-biosensor was greatly benefited from appropriate dosage of AZM (0.5% AZM@GP) with reduced start-up time period, comparatively higher voltage output, more readable electrical signal and increased inhibition rate (30%-65% higher than control sensor with GP electrode) when exposing to toxic formaldehyde. This may be attributed to the fact that AZM inhibited the growth of non-EAM without much influence on the physiologic or metabolism activities of EAM under proper dosage. Further investigation of the biofilm morphology and microbial community analysis suggested that the biofilm formation was optimized with reduced thickness and enriched Geobacter with 0.5% AZM@GP dosage. This novel electrode is easily fabricated and equipped, and therefore would be a promising way to facilitate the practical application of EAB-sensors.

  • REVIEW ARTICLE
    Jinlan Yu, Kang Xiao, Wenchao Xue, Yue-xiao Shen, Jihua Tan, Shuai Liang, Yanfen Wang, Xia Huang
    Frontiers of Environmental Science & Engineering, 2020, 14(2): 31. https://doi.org/10.1007/s11783-019-1210-8

    • Principles and methods for fluorescence EEM are systematically outlined.

    • Fluorophore peak/region/component and energy information can be extracted from EEM.

    • EEM can fingerprint the physical/chemical/biological properties of DOM in MBRs.

    • EEM is useful for tracking pollutant transformation and membrane retention/fouling.

    • Improvements are still needed to overcome limitations for further studies.

    The membrane bioreactor (MBR) technology is a rising star for wastewater treatment. The pollutant elimination and membrane fouling performances of MBRs are essentially related to the dissolved organic matter (DOM) in the system. Three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy, a powerful tool for the rapid and sensitive characterization of DOM, has been extensively applied in MBR studies; however, only a limited portion of the EEM fingerprinting information was utilized. This paper revisits the principles and methods of fluorescence EEM, and reviews the recent progress in applying EEM to characterize DOM in MBR studies. We systematically introduced the information extracted from EEM by considering the fluorescence peak location/intensity, wavelength regional distribution, and spectral deconvolution (giving fluorescent component loadings/scores), and discussed how to use the information to interpret the chemical compositions, physiochemical properties, biological activities, membrane retention/fouling behaviors, and migration/transformation fates of DOM in MBR systems. In addition to conventional EEM indicators, novel fluorescent parameters are summarized for potential use, including quantum yield, Stokes shift, excited energy state, and fluorescence lifetime. The current limitations of EEM-based DOM characterization are also discussed, with possible measures proposed to improve applications in MBR monitoring.

  • RESEARCH ARTICLE
    Shaswati Saha, Rohan Gupta, Shradhanjali Sethi, Rima Biswas
    Frontiers of Environmental Science & Engineering, 2022, 16(8): 101. https://doi.org/10.1007/s11783-022-1522-y

    • Simultaneous C & N removal in Methammox occurs at wide C:N ratio.

    • Biological Nitrogen Removal at wide C:N ratio of 1.5:1 to 14:1 is not reported.

    • Ammonia removal shifted from mixotrophy to heterotrophy at high C:N ratio.

    • Acetogenic population compensated for ammonia oxidizers at high C:N ratio.

    • Methanogens increase the plasticity of nitrogen removers at high C:N ratio.

    High C:N ratio in the wastewater limits biological nitrogen removal (BNR), especially in anammox based technologies. The present study attempts to improve the COD tolerance of the BNR process by associating methanogens with nitrogen removing bacterial (NRB) populations. The new microbial system coined as ‘Methammox’, was investigated for simultaneous removal of COD (C) and ammonia (N) at C:N ratio 1.5:1 to 14:1. The ammonia removal rate (11.5 mg N/g VSS/d) and the COD removal rates (70.6 mg O/g VSS/d) of Methammox was close to that of the NRB (11.1 mg N/g VSS/d) and the methanogenic populations (77.9 mg O/g VSS/d), respectively. The activities established that these two populations existed simultaneously and independently in ‘Methammox’. Further studies in biofilm reactor fetched a balanced COD and ammonia removal (55%–60%) at a low C:N ratio (≤2:1) and high C:N ratio (≥9:1). The population abundance of methanogens was reasonably constant, but the nitrogen removal shifted from mixotrophy to heterotrophy as the C:N ratio shifted from low (C:N≤2:1) to high (C:N≥9:1). The reduced autotrophic NRB (ammonia- and nitrite-oxidizing bacteria and Anammox) population at a high C:N ratio was compensated by the fermentative group that could carry out denitrification heterotrophically. The functional plasticity of the Methammox system to adjust to a broad C:N ratio opens new frontiers in biological nitrogen removal of high COD containing wastewaters.

  • SHORT COMMUNICATION
    Minxiang Wang, Lili Yang, Xiaoyun Liu, Zheng Wang, Guorui Liu, Minghui Zheng
    Frontiers of Environmental Science & Engineering, 2021, 15(4): 60. https://doi.org/10.1007/s11783-020-1352-8

    • Unintentional HCBD production in typical chemical plants was investigated.

    • The highest HCBD concentrations were found in the bottom residue.

    • Tri/tetrachloroethylene production processes were important HCBD sources.

    Hexachlorobutadiene (HCBD) was classed as a persistent organic pollutant under the Stockholm Convention in 2015. HCBD is mainly an unintentionally produced by-product of chlorinated hydrocarbon (e.g., trichloroethylene and tetrachloroethylene) synthesis. Few studies of HCBD formation during chemical production processes have been performed, so HCBD emissions from these potentially important sources are not understood. In this study, HCBD concentrations in raw materials, intermediate products, products, and bottom residues from chemical plants producing chlorobenzene, trichloroethylene, and tetrachloroethylene were determined. The results indicated that HCBD is unintentionally produced at much higher concentrations in trichloroethylene and tetrachloroethylene plants than chlorobenzene plants. The sum of the HCBD concentrations in the samples from all of the trichloroethylene and tetrachloroethylene production stages in plant PC was 247000 mg/mL, about three orders of magnitude higher than the concentrations in the tetrachloroethylene production samples (plant PB) and about six orders of magnitude higher than the concentrations in the chlorobenzene production samples (plant PA). The HCBD concentrations were highest in bottom residues from all of the plants. The concentrations in the bottom residue samples contributed 24%–99% of the total HCBD formed in the chemical production plants. The bottom residue, being hazardous waste, could be disposed of by incineration. The HCBD concentrations were much higher in intermediate products than raw materials, indicating that HCBD formed during production of the intended chemicals. The results indicate the concentrations of HCBD unintentionally produced in typical chemical plants and will be useful in developing protocols for controlling HCBD emissions to meet the Stockholm Convention requirements.

  • Research article
    Xiaowen ZHANG, Weili DAI, Shuangfeng YIN, Shenglian LUO, Chak-Tong AU
    Frontiers of Environmental Science & Engineering, 2009, 3(1): 32-37. https://doi.org/10.1007/s11783-008-0068-y

    In order to achieve high-efficiency conversion of CO2 into valuable chemicals, and to exploit new applications of organobismuth compounds, cationic organobismuth complex with 5,6,7,12-tetrahydrodibenz[c,f]1,5 azabismocine framework was examined for the first time for the coupling of CO2 into cyclic carbonates, using terminal epoxides as substrates and tetrabutylammonium halide as co-catalyst in a solvent-free environment under mild conditions. It is shown that the catalyst exhibited high activity and selectivity for the coupling reaction of CO2 with a wide range of terminal epoxide. The selectivity of propylene carbonates could reach 100%, and the maximum turnover frequency was up to 10740 h-1 at 120°C and 3 MPa CO2 pressure when tetrabutylammonium iodide was used as co-catalyst. Moreover, the catalyst is environment friendly, resistant to air and water, and can be readily reused and recycled without any loss of activity, demonstrating a potential in industrial application.

  • REVIEW ARTICLE
    Jianzhi Huang, Huichun Zhang
    Frontiers of Environmental Science & Engineering, 2020, 14(5): 76. https://doi.org/10.1007/s11783-020-1255-8

    • Mechanisms of redox reactions of Fe- and Mn-oxides were discussed.

    • Oxidative reactions of Mn- and Fe-oxides in complex systems were reviewed.

    • Reductive reaction of Fe(II)/iron oxides in complex systems was examined.

    • Future research on examining the redox reactivity in complex systems was suggested.

    Conspectus Redox reactions of Fe- and Mn-oxides play important roles in the fate and transformation of many contaminants in natural environments. Due to experimental and analytical challenges associated with complex environments, there has been a limited understanding of the reaction kinetics and mechanisms in actual environmental systems, and most of the studies so far have only focused on simple model systems. To bridge the gap between simple model systems and complex environmental systems, it is necessary to increase the complexity of model systems and examine both the involved interaction mechanisms and how the interactions affected contaminant transformation. In this Account, we primarily focused on (1) the oxidative reactivity of Mn- and Fe-oxides and (2) the reductive reactivity of Fe(II)/iron oxides in complex model systems toward contaminant degradation. The effects of common metal ions such as Mn2+ , Ca2+, Ni2+, Cr3+ and Cu2+, ligands such as small anionic ligands and natural organic matter (NOM), and second metal oxides such as Al, Si and Ti oxides on the redox reactivity of the systems are briefly summarized.

  • REVIEW ARTICLE
    Dongjie Shang, Jianfei Peng, Song Guo, Zhijun Wu, Min Hu
    Frontiers of Environmental Science & Engineering, 2021, 15(2): 34. https://doi.org/10.1007/s11783-020-1326-x

    • Characteristics and interannual variation of aerosol pollution are illustrated.

    • Mechanisms of secondary aerosol formation in winter haze of North China are reviewed.

    • Directions in future studies of secondary aerosol formation are provided.

    Severe haze pollution occurs frequently in the winter over the Beijing-Tianjin-Hebei (BTH) region (China), exerting profound impacts on air quality, visibility, and human health. The Chinese Government has taken strict mitigation actions since 2013 and has achieved a significant reduction in the annual mean PM2.5 concentration over this region. However, the level of secondary aerosols during heavy haze episodes showed little decrease during this period. During heavy haze episodes, the concentrations of secondary aerosol components, including sulfate, nitrate and secondary organics, in aerosol particles increase sharply, acting as the main contributors to aerosol pollution. To achieve effective control of particle pollution in the BTH region, the precise and complete secondary aerosol formation mechanisms have been investigated, and advances have been made about the mechanisms of gas phase reaction, nucleation and heterogeneous reactions in forming secondary aerosols. This paper reviews the research progress in aerosol chemistry during haze pollution episodes in the BTH region, lays out the challenges in haze formation studies, and provides implications and directions for future research.

  • RESEARCH ARTICLE
    Nan Wu, Weiyu Zhang, Shiyu Xie, Ming Zeng, Haixue Liu, Jinghui Yang, Xinyuan Liu, Fan Yang
    Frontiers of Environmental Science & Engineering, 2020, 14(1): 1. https://doi.org/10.1007/s11783-019-1180-x

    • Manure application increased the abundances of ARGs and MGEs in agricultural soils.

    • Five classes of ARGs and two MGEs were prevalent in manured and unfertilized soils.

    • Genera Pseudomonas and Bacteroidetes might be the dominant hosts of intI1 and ermF.

    • The abundances of ARGs positively correlated with TC, TN, OM, Cu, Zn, Pb and MGEs.

    Land application of manure tends to result in the dissemination of antibiotic resistance in the environment. In this study, the influence of long-term manure application on the enrichment of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in agricultural soils was investigated. All the analyzed eight ARGs (tetA, tetW, tetX, sulI, sulII, ermF, aac(6’)-Ib-cr and blaTEM) and two MGEs (intI1 and Tn916/1545) were detected in both the manured and control soils, with relative abundances ranging from 10-6 to 10-2. Compared with the control soil, the relative abundances of ARGs and MGEs in manured soils were enriched 1.0–18.1 fold and 0.6–69.1 fold, respectively. High-throughput sequencing analysis suggested that at the phylum level, the bacteria carrying intI1 and ermF might be mainly affiliated with Proteobacteria and Bacteroides, respectively. The dominant genera carrying intI1 and ermF could be Pseudomonas and Bacteroides, independent of manure application. Correlation analysis revealed that ARGs had strong links with soil physicochemical properties (TC, TN, and OM), heavy metals (Cu, Zn and Pb) and MGEs, indicating that the profile and spread of ARGs might be driven by the combined impacts of multiple factors. In contrast, soil pH and C/N exhibited no significant relationships with ARGs. Our findings provide evidence that long-term manure application could enhance the prevalence and stimulate the propagation of antibiotic resistance in agricultural soils.

  • RESEARCH ARTICLE
    Xiaoge Huang, Lihao Chen, Ziqi Ma, Kenneth C. Carroll, Xiao Zhao, Zailin Huo
    Frontiers of Environmental Science & Engineering, 2022, 16(12): 151. https://doi.org/10.1007/s11783-022-1586-8

    ● nZVI, S-nZVI, and nFeS were systematically compared for Cd(II) removal.

    ● Cd(II) removal by nZVI involved coprecipitation, complexation, and reduction.

    ● The predominant reaction for Cd(II) removal by S-nZVI and nFeS was replacement.

    ● A simple pseudo-second-order kinetic can adequately fit Fe(II) dissolution.

    Cadmium (Cd) is a common toxic heavy metal in the environment. Taking Cd(II) as a target contaminant, we systematically compared the performances of three Fe-based nanomaterials (nano zero valent iron, nZVI; sulfidated nZVI, S-nZVI; and nano FeS, nFeS) for Cd immobilization under anaerobic conditions. Effects of nanomaterials doses, initial pH, co-existing ions, and humic acid (HA) were examined. Under identical conditions, at varied doses or initial pH, Cd(II) removal by three materials followed the order of S-nZVI > nFeS > nZVI. At pH 6, the Cd(II) removal within 24 hours for S-nZVI, nFeS, and nZVI (dose of 20 mg/L) were 93.50%, 89.12% and 4.10%, respectively. The fast initial reaction rate of nZVI did not lead to a high removal capacity. The Cd removal was slightly impacted or even improved with co-existing ions (at 50 mg/L or 200 mg/L) or HA (at 2 mg/L or 20 mg/L). Characterization results revealed that nZVI immobilized Cd through coprecipitation, surface complexation, and reduction, whereas the mechanisms for sulfidated materials involved replacement, coprecipitation, and surface complexation, with replacement as the predominant reaction. A strong linear correlation between Cd(II) removal and Fe(II) dissolution was observed, and we proposed a novel pseudo-second-order kinetic model to simulate Fe(II) dissolution.

  • RESEARCH ARTICLE
    Sen Dong, Peng Gao, Benhang Li, Li Feng, Yongze Liu, Ziwen Du, Liqiu Zhang
    Frontiers of Environmental Science & Engineering, 2022, 16(11): 142. https://doi.org/10.1007/s11783-022-1577-9

    ● Reduce the quantifying MPs time by using Nile red staining.

    ● The removal rate of MPs and PAEs in wastewater and sludge were investigated.

    ● MPs and PAEs were firstly analyzed during thermal hydrolysis treatment.

    ● The removal of PAEs from wastewater and sludge was mainly biodegradation.

    Microplastics (MPs) and plasticizers, such as phthalate esters (PAEs), were frequently detected in municipal wastewater treatment plants (MWTP). Previous research mainly studied the removal of MPs and PAEs in wastewater. However, the occurrence of MPs and PAEs in the sludge was generally ignored. To comprehensively investigate the occurrence and the migration behaviors of MPs and PAEs in MWTP, a series of representative parameters including the number, size, color, shape of MPs, and the concentrations of PAEs in wastewater and sludge were systematically investigated. In this study, the concentrations of MPs in the influent and effluent were 15.46±0.37 and 0.30±0.14 particles/L. The MP removal efficiency of 98.1% was achieved and about 73.8% of MPs were accumulated in the sludge in the MWTP. The numbers of MPs in the sludge before and after digestion were 4.40±0.14 and 0.31±0.01 particles/g (dry sludge), respectively. Fourier Transform Infrared Spectroscopy (ATR FT-IR) analysis showed that the main types of MPs were polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), and polystyrene (PS). Six PAEs, including phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), ortho dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), and bis(2-ethyl) hexyl phthalate (DEHP), were detected in the MWTP. The concentrations of total PAEs (ΣPAEs) in the influent and effluent were 76.66 and 6.28 µg/L, respectively. The concentrations of ΣPAEs in the sludge before and after digestion were 152.64 and 31.70 µg/g, respectively. In the process of thermal hydrolysis, the number and size of MPs decreased accompanied by the increase of the plasticizer concentration.

  • RESEARCH ARTICLE
    Chao Yang, Wenjun Sun, Xiuwei Ao
    Frontiers of Environmental Science & Engineering, 2020, 14(1): 13. https://doi.org/10.1007/s11783-019-1192-6

    • Long amplicon is more effective to test DNA damage induced by UV.

    • ATP in bacteria does not degrade instantly but does eventually after UV exposure.

    • After medium pressure UV exposure, ATP degraded faster.

    The efficacy of ultraviolet (UV) disinfection has been validated in numerous studies by using culture-based methods. However, the discovery of viable but non-culturable bacteria has necessitated the investigation of UV disinfection based on bacterial viability parameters. We used quantitative polymerase chain reaction (qPCR) to investigate DNA damage and evaluated adenosine triphosphate (ATP) to indicate bacterial viability. The results of qPCR effectively showed the DNA damage induced by UV when using longer gene amplicons, in that sufficiently long amplicons of both 16S and gadA indicated that the UV induced DNA damages. The copy concentrations of the long amplicons of 16S and gadA decreased by 2.38 log/mL and 1.88 log/mL, respectively, after exposure to 40 mJ/cm2 low-pressure UV. After UV exposure, the ATP level in the bacteria did not decrease instantly. Instead it decreased gradually at a rate that was positively related to the UV fluence. For low-pressure UV, this rate of decrease was slow, but for medium pressure UV, this rate of decrease was relatively high when the UV fluence reached 40 mJ/cm2. At the same UV fluence, the ATP level in the bacteria decreased at a faster rate after exposure to medium-pressure UV.

  • REVIEW ARTICLE
    Zhuqiu Sun, Jinying Xi, Chunping Yang, Wenjie Cong
    Frontiers of Environmental Science & Engineering, 2022, 16(7): 87. https://doi.org/10.1007/s11783-021-1495-2

    • Quorum sensing enhancement and inhibition methods are summarized.

    • Effects of quorum sensing regulation on biofilm are reviewed.

    • Current knowledge gaps and research challenges are proposed.

    Quorum sensing (QS) plays an important role in microbial aggregation control. Recently, the optimization of biological waste treatment systems by QS regulation gained an increasing attention. The effects of QS regulation on treatment performances and biofilm were frequently investigated. To understand the state of art of QS regulation, this review summarizes the methods of QS enhancement and QS inhibition in biological waste treatment systems. Typical QS enhancement methods include adding exogenous QS molecules, adding QS accelerants and cultivating QS bacteria, while typical QS inhibition methods include additions of quorum quenching (QQ) bacteria, QS-degrading enzymes, QS-degrading oxidants, and QS inhibitors. The specific improvements after applying these QS regulation methods in different treatment systems are concluded. In addition, the effects of QS regulation methods on biofilm in biological waste treatment systems are reviewed in terms of biofilm formation, extracellular polymeric substances production, microbial viability, and microbial community. In the end, the knowledge gaps in current researches are analyzed, and the requirements for future study are suggested.

  • RESEARCH ARTICLE
    Shansi Wang, Siwei Li, Jia Xing, Jie Yang, Jiaxin Dong, Yu Qin, Shovan Kumar Sahu
    Frontiers of Environmental Science & Engineering, 2022, 16(2): 26. https://doi.org/10.1007/s11783-021-1460-0

    •Strong ENSO influence on AOD is found in southern China region.

    •Low AOD occurs in El Niño but high AOD occurs in La Niña events in southern China.

    •Angstrom exponent anomalies reveals the circulation pattern during each ENSO phase.

    •ENSO exerts large influence (70.5%) on annual variations of AOD during 2002–2020.

    •Change of anthropogenic emissions is the dominant driver for AOD trend (2002–2020).

    Previous studies demonstrated that the El Niño–Southern Oscillation (ENSO) could modulate regional climate thus influencing air quality in the low-middle latitude regions like southern China. However, such influence has not been well evaluated at a long-term historical scale. To filling the gap, this study investigated two-decade (2002 to 2020) aerosol concentration and particle size in southern China during the whole dynamic development of ENSO phases. Results suggest strong positive correlations between aerosol optical depth (AOD) and ENSO phases, as low AOD occurred during El Niño while high AOD occurred during La Niña event. Such correlations are mainly attributed to the variation of atmospheric circulation and precipitation during corresponding ENSO phase. Analysis of the angstrom exponent (AE) anomalies further confirmed the circulation pattern, as negative AE anomalies is pronounced in El Niño indicating the enhanced transport of sea salt aerosols from the South China Sea, while the La Niña event exhibits positive AE anomalies which can be attributed to the enhanced import of northern fine anthropogenic aerosols. This study further quantified the AOD variation attributed to changes in ENSO phases and anthropogenic emissions. Results suggest that the long-term AOD variation from 2002 to 2020 in southern China is mostly driven (by 64.2%) by the change of anthropogenic emissions from 2002 to 2020. However, the ENSO presents dominant influence (70.5%) on year-to-year variations of AOD during 2002–2020, implying the importance of ENSO on varying aerosol concentration in a short-term period.

  • RESEARCH ARTICLE
    Kun Zhang, Jialuo Xu, Qing Huang, Lei Zhou, Qingyan Fu, Yusen Duan, Guangli Xiu
    Frontiers of Environmental Science & Engineering, 2020, 14(6): 92. https://doi.org/10.1007/s11783-020-1271-8

    • Air masses from Zhejiang Province is the major source of O3 in suburban Shanghai.

    • O3 formation was in VOC-sensitive regime in rural Shanghai.

    • O3 formation was most sensitive to propylene in rural Shanghai.

    A high level of ozone (O3) is frequently observed in the suburbs of Shanghai, the reason for this high level remains unclear. To obtain a detailed insight on the high level of O3 during summer in Shanghai, O3 and its precursors were measured at a suburban site in Shanghai from July 1, 2016 to July 31, 2016. Using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model and concentration weighted trajectories (CWT), we found that Zhejiang province was the main potential source of O3 in suburban Shanghai. When the sampling site was controlled by south-western winds exceeding 2 m/s, the O3-rich air masses from upwind regions (such as Zhejiang province) could be transported to the suburban Shanghai. The propylene-equivalent concentration (PEC) and ozone formation potential (OFP) were further calculated for each VOC species, and the results suggested that propylene, (m+p)-xylene, and toluene played dominant roles in O3 formation. The Ozone Isopleth Plotting Research (OZIPR) model was used to reveal the impact of O3 precursors on O3 formation, and 4 base-cases were selected to adjust the model simulation. An average disparity of 18.20% was achieved between the simulated and observed O3 concentrations. The O3 isopleth diagram illustrated that O3 formation in July 2016 was in VOC-sensitive regime, although the VOC/NOx ratio was greater than 20. By introducing sensitivity (S), a sensitivity analysis was performed for O3 formation. We found that O3 formation was sensitive to propylene, (m+p)-xylene, o-xylene and toluene. The results provide theoretical support for O3 pollution treatment in Shanghai.

  • REVIEW ARTICLE
    Hongqi Wang, Ruhan Jiang, Dekang Kong, Zili Liu, Xiaoxiong Wu, Jie Xu, Yi Li
    Frontiers of Environmental Science & Engineering, 2020, 14(1): 9. https://doi.org/10.1007/s11783-019-1188-2

    • Explaintheadsorption, uptake and transmembrane transport of PAHs by bacteria.

    • Analyze functional regulation of membrane proteins inthe transmembrane transport.

    • Proteomics technology such as iTRAQ labeling was used to access expressed proteins.

    • Single cell analysis technology wereused to study the morphological structure.

    In recent years, increasing research has been conducted on transmembrane transport processes and the mechanisms behind the microbial breakdown of polycyclic aromatic hydrocarbons (PAHs), including the role of membrane proteins in transmembrane transport and the mode of transmission. This article explains the adsorption, uptake and transmembrane transport of PAHs by bacteria, the regulation of membrane protein function during the transmembrane transport. There are three different regulation mechanisms for uptake, depending on the state and size of the oil droplets relative to the size of the microbial cells, which are (i) direct adhesion, (ii) emulsification and pseudosolubilization, and (iii) interfacial uptake. Furthermore, two main transmembrane transport modes are introduced, which are (i) active transport and (ii) passive uptake and active efflux mechanism. Meanwhile, introduce the proteomics and single cell analysis technology used to address these areas of research, such as Isobaric tags for relative and absolute quantitation (iTRAQ) technology and Nano Secondary ion mass spectrometry (Nano-SIMS). Additionally, analyze the changes in morphology and structure and the characteristics of microbial cell membranes in the process of transmembrane transport. Finally, recognize the microscopic mechanism of PAHs biodegradation in terms of cell and membrane proteins are of great theoretical and practical significance for understanding the factors that influence the efficient degradation of PAHs contaminants in soil and for remediating the PAHs contamination in this area with biotechnology.