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    Zhengyang Huo, Young Jun Kim, Yuying Chen, Tianyang Song, Yang Yang, Qingbin Yuan, Sang Woo Kim
    Frontiers of Environmental Science & Engineering, 2023, 17(10): 118.

    ● Energy harvesters harness multiple energies for self-powered water purification.

    ● Hybrid energy harvesters enable continuous output under fluctuating conditions.

    ● Mechanical, thermal, and solar energies enable synergic harvesting.

    ● Perspectives of hybrid energy harvester-driven water treatment are proposed.

    The development of self-powered water purification technologies for decentralized applications is crucial for ensuring the provision of drinking water in resource-limited regions. The elimination of the dependence on external energy inputs and the attainment of self-powered status significantly expands the applicability of the treatment system in real-world scenarios. Hybrid energy harvesters, which convert multiple ambient energies simultaneously, show the potential to drive self-powered water purification facilities under fluctuating actual conditions. Here, we propose recent advancements in hybrid energy systems that simultaneously harvest various ambient energies (e.g., photo irradiation, flow kinetic, thermal, and vibration) to drive water purification processes. The mechanisms of various energy harvesters and point-of-use water purification treatments are first outlined. Then we summarize the hybrid energy harvesters that can drive water purification treatment. These hybrid energy harvesters are based on the mechanisms of mechanical and photovoltaic, mechanical and thermal, and thermal and photovoltaic effects. This review provides a comprehensive understanding of the potential for advancing beyond the current state-of-the-art of hybrid energy harvester-driven water treatment processes. Future endeavors should focus on improving catalyst efficiency and developing sustainable hybrid energy harvesters to drive self-powered treatments under unstable conditions (e.g., fluctuating temperatures and humidity).

    Hao Zheng, Jian Cheng, Hung Chak Ho, Baoli Zhu, Zhen Ding, Wencong Du, Xin Wang, Yang Yu, Juan Fei, Zhiwei Xu, Jinyi Zhou, Jie Yang
    Frontiers of Environmental Science & Engineering, 2023, 17(9): 105.

    ● A study assessing the temperature-injury relationship was conducted among students.

    ● The maximum risks of injury appeared at moderate temperatures.

    ● The temperature effect on outdoor falls was greater in older students.

    Although studies have suggested that non-optimal temperatures may increase the risk of injury, epidemiological studies focusing on the association between temperature and non-fatal injury among children and adolescents are limited. Therefore, we investigated the short-term effect of ambient temperature on non-fatal falls and road traffic injuries (RTIs) among students across Jiangsu Province, China. Meteorological data and records of non-fatal outdoor injuries due to falls and RTIs among students aged 6–17 were collected during 2018–2020. We performed a time-stratified case-crossover analysis with a distributed lag nonlinear model to examine the effect of ambient temperature on the risk of injury. Individual meteorological exposure was estimated based on the address of the selected school. We also performed stratified analyses by sex, age, and area. A total of 57322 and 5455 cases of falls and RTIs were collected, respectively. We observed inverted U-shaped curves for temperature-injury associations, with maximum risk temperatures at 18 °C (48th of daily mean temperature distribution) for falls and 22 °C (67th of daily mean temperature distribution) for RTIs. The corresponding odds ratios (95% confidence intervals) were 2.193 (2.011, 2.391) and 3.038 (1.988, 4.644) for falls and RTIs, respectively. Notably, there was a significant age-dependent trend in which the temperature effect on falls was greater in older students (P-trend < 0.05). This study suggests a significant association between ambient temperature and students’ outdoor falls and RTIs. Our findings may help advance tailored strategies to reduce the incidence of outdoor falls and RTIs in children and adolescents.

    Ling Qi, Zhige Tian, Nan Jiang, Fangyuan Zheng, Yuchen Zhao, Yishuo Geng, Xiaoli Duan
    Frontiers of Environmental Science & Engineering, 2023, 17(8): 92.

    ● Increased DAAO offsets 3/4 of the decrease of DAAP in 2013–2020.

    ● DAAO increases are mainly due to O3 concentration increase and population aging.

    ● Health benefit from PM2.5 reduction after 2017 is larger than that before 2017.

    ● Reducing PM2.5 concentration by 1% results in 0.6% reduction of DAAP.

    ● Reducing O3 concentration by 1% results in 2% reduction of DAAO.

    PM2.5 concentration declined significantly nationwide, while O3 concentration increased in most regions in China in 2013–2020. Recent evidences proved that peak season O3 is related to increased death risk from non-accidental and respiratory diseases. Based on these new evidences, we estimate excess deaths associated with long-term exposure to ambient PM2.5 and O3 in China following the counterfactual analytic framework from Global Burden Disease. Excess deaths from non-accidental diseases associated with long-term exposure to ambient O3 in China reaches to 579 (95% confidential interval (CI): 93, 990) thousand in 2020, which has been significantly underestimated in previous studies. In addition, the increased excess deaths associated with long-term O3 exposure (234 (95% CI: 177, 282) thousand) in 2013–2020 offset three quarters of the avoided excess deaths (302 (95% CI: 244, 366) thousand) mainly due to PM2.5 exposure reduction. In key regions (the North China Plain, the Yangtze River Delta and the Fen-Wei Plain), the former is even larger than the latter, particularly in 2017–2020. Health benefit of PM2.5 concentration reduction offsets the adverse effects of population growth and aging on excess deaths attributed to PM2.5 exposure. Increase of excess deaths associated with O3 exposure is mainly due to the strong increase of O3 concentration, followed by population aging. Considering the faster population aging process in the future, collaborative control, and faster reduction of PM2.5 and O3 are needed to reduce the associated excess deaths.

    Md. Raihanul Islam, Sumaiya Akter Ruponti, Md. Abdur Rakib, Huy Quoc Nguyen, Monjur Mourshed
    Frontiers of Environmental Science & Engineering, 2023, 17(6): 66.

    ● A global snapshot of plastic waste generation and disposal is analysed.

    ● Effect of plastic pollution on environment and terrestrial ecosystem is reviewed.

    ● Ecotoxicity and food security from plastic pollution is discussed.

    Plastic is considered one of the most indispensable commodities in our daily life. At the end of life, the huge ever-growing pile of plastic waste (PW) causes serious concerns for our environment, including agricultural farmlands, groundwater quality, marine and land ecosystems, food toxicity and human health hazards. Lack of proper infrastructure, financial backup, and technological advancement turn this hazardous waste plastic management into a serious threat to developing countries, especially for Bangladesh. A comprehensive review of PW generation and its consequences on environment in both global and Bangladesh contexts is presented. The dispersion routes of PW from different sources in different forms (microplastic, macroplastic, nanoplastic) and its adverse effect on agriculture, marine life and terrestrial ecosystems are illustrated in this work. The key challenges to mitigate PW pollution and tackle down the climate change issue is discussed in this work. Moreover, way forward toward the design and implementation of proper PW management strategies are highlighted in this study.

    Xi Lu, Dan Tong, Kebin He
    Frontiers of Environmental Science & Engineering, 2023, 17(2): 14.

    ● China has pledged ambitious carbon peak and neutrality goals for mitigating global climate change.

    ● Major challenges to achieve carbon neutrality in China are summarized.

    ● The new opportunities along the pathway of China’s carbon neutrality are discussed from four aspects.

    ● Five policy suggestions for China are provided.

    China is the largest developing economy and carbon dioxide emitter in the world, the carbon neutrality goal of which will have a profound influence on the mitigation pathway of global climate change. The transition towards a carbon-neutral society is integrated into the construction of ecological civilization in China, and brings profound implications for China’s socioeconomic development. Here, we not only summarize the major challenges in achieving carbon neutrality in China, but also identify the four potential new opportunities: namely, the acceleration of technology innovations, narrowing regional disparity by reshaping the value of resources, transforming the industrial structure, and co-benefits of pollution and carbon mitigation. Finally, we provide five policy suggestions and highlight the importance of balancing economic growth and carbon mitigation, and the joint efforts among the government, the enterprises, and the residents.

    Xiaoying Wang, Haiguang Zhang, Xu Wang, Shuo Chen, Hongtao Yu, Xie Quan
    Frontiers of Environmental Science & Engineering, 2023, 17(1): 1.

    ● Electroconductive RGO-MXene membranes were fabricated.

    ● Wettable membrane channels were established between RGO and MXene nanosheets.

    ● Hydrophilic MXene reduces the resistance of water entering the membrane channels.

    ● Water permeance of RGO-MXene membrane is 16.8 times higher than that of RGO membrane.

    ● Electro-assistance can enhance the dye rejection performance of RGO-MXene membrane.

    Reduced graphene oxide (RGO) membranes are theoretically more conducive to the rapid transport of water molecules in their channels compared with graphene oxide (GO) membranes, as they have fewer oxygen-containing functional groups and more non-oxidized regions. However, the weak hydrophilicity of RGO membranes inhibits water entry into their channels, resulting in their low water permeability. In this work, we constructed wettable RGO-MXene channels by intercalating hydrophilic MXene nanosheets into the RGO membrane for improving the water permeance. The RGO-MXene composite membrane exhibits high pure water permeance of 62.1 L/(m2·h·bar), approximately 16.8 times that of the RGO membrane (3.7 L/(m2·h·bar)). Wettability test results and molecular dynamics simulations suggest that the improved water permeance results from the enhanced wettability of RGO-MXene membrane and increased rate of water molecules entering the RGO-MXene channels. Benefiting from good conductivity, the RGO-MXene membrane with electro-assistance exhibits significantly increased rejection rates for negatively charged dyes (from 56.0% at 0 V to 91.4% at 2.0 V for Orange G) without decreasing the permeate flux, which could be attributed to enhanced electrostatic repulsion under electro-assistance.

    Yang Yang, Xiuzhen Zheng, Wei Ren, Jiafang Liu, Xianliang Fu, Sugang Meng, Shifu Chen, Chun Cai
    Frontiers of Environmental Science & Engineering, 2022, 16(11): 137.

    ● Systematic information of recent progress in photocatalytic NO x removal is provided.

    ● The photocatalysts with special morphologies are reviewed and discussed.

    ● The morphology and photocatalytic NO x removal performance is related.

    The significant increase of NOx concentration causes severe damages to environment and human health. Light-driven photocatalytic technique affords an ideal solution for the removal of NOx at ambient conditions. To enhance the performance of NOx removal, 1D, 2D and 3D photocatalysts have been constructed as the light absorption and the separation of charge carriers can be manipulated through controlling the morphology of the photocatalyst. Related works mainly focused on the construction and modification of special morphologic photocatalyst, including element doping, heterostructure constructing, crystal facet exposing, defect sites introducing and so on. Moreover, the excellent performance of the photocatalytic NOx removal creates great awareness of the application, which has promising practical applications in NOx removal by paint (removing NOx indoor and outdoor) and pavement (degrading vehicle exhausts). For these considerations, recent advances in special morphologic photocatalysts for NOx removal was summarized and commented in this review. The purpose is to provide insights into understanding the relationship between morphology and photocatalytic performance, meanwhile, to promote the application of photocatalytic technology in NOx degradation.

    Xin Xing, Na Li, Dandan Liu, Jie Cheng, Zhengping Hao
    Frontiers of Environmental Science & Engineering, 2022, 16(10): 125.

    ● A series of Cu-ZSM-5 catalysts were tested for DMF selective catalytic oxidation.

    ● Cu-6 nm samples showed the best catalytic activity and N2 selectivity.

    ● Redox properties and chemisorbed oxygen impact on DMF catalytic oxidation.

    ● Isolated Cu2+ species and weak acidity have effects on the generation of N2.

    N, N-Dimethylformamide (DMF), a nitrogen-containing volatile organic compound (NVOC) with high emissions from the spray industry, has attracted increasing attention. In this study, Cu-ZSM-5 catalysts with different CuO particle sizes of 3, 6, 9 and 12 nm were synthesized and tested for DMF selective catalytic oxidation. The crystal structure and physicochemical properties of the catalyst were studied by various characterization methods. The catalytic activity increases with increasing CuO particle size, and complete conversion can be achieved at 300–350 °C. The Cu-12 nm catalyst has the highest catalytic activity and can achieve complete conversion at 300 °C. The Cu-6 nm sample has the highest N2 selectivity at lower temperatures, reaching 95% at 300 °C. The activity of the catalysts is determined by the surface CuO cluster species, the bulk CuO species and the chemisorbed surface oxygen species. The high N2 selectivity of the catalyst is attributed to the ratio of isolated Cu2+ and bulk CuO species, and weak acidity is beneficial to the formation of N2. The results in this work will provide a new design of NVOC catalytic oxidation catalysts.

    Dan Xiao, Zhaofeng Lyu, Shiheng Chen, Yang Huo, Wei Fan, Mingxin Huo
    Frontiers of Environmental Science & Engineering, 2022, 16(9): 112.

    Cryptosporidium in WWTPs in a cold region was investigated in different seasons.

    • The overall removal efficiency of Cryptosporidium in WWTPs was over 84%.

    • The infectivity rate declined below 53% in effluents mainly due to disinfection.

    • The infectivity of Cryptosporidium increased with a seasonal drop in temperature.

    • Low temperature promotes binding protein retention and virulence genes expression.

    This study investigated the occurrence, species, infectivity and removal efficiency of Cryptosporidium spp. across typical wastewater treatment train. Samples from different process units were collected seasonally and synchronously from four wastewater treatment plants (WWTPs) in Northeastern China. Live Cryptosporidium oocysts were identified in most samples from both influent (97.50%) and effluent (90.00%) wastewaters of the four WWTPs, at an average density of 26.34 and 4.15 oocysts/L, respectively. The overall removal efficiency was 84.25%, and oocysts were mainly removed (62.01%) by the modified secondary sedimentation process. Ten Cryptosporidium species were identified in the effluent samples. C. andersoni, C. bovis, and C. ryanae were the three most prevalent species. Oocyst viability assays indicated no reduction of excystation rate during the primary and secondary wastewater treatments (varied in the range of 63.08%–68.50%), but the excystation rate declined to 52.21% in the effluent after disinfection. Notably, the Cryptosporidium oocysts showed higher infection intensity in the cold season (winter and spring) than that in summer and autumn. The influences of environmental temperature on virulence factors of Cryptosporidium were further examined. It was observed that more extracellular secretory proteins were bound on the oocyst surface and several virulence genes were expressed relatively strongly at low temperatures, both of which could facilitate oocyst adhesion, invasion, and host immune evasion. This research is of considerable interest since it serves as an important step towards more accurate panoramic recognition of Cryptosporidium risk reduction in WWTPs, and especially highlights the potential health risk associated with Cryptosporidium in cold regions/seasons.

    Shuyi Wang, Xiang Qi, Yong Jiang, Panpan Liu, Wen Hao, Jinbin Han, Peng Liang
    Frontiers of Environmental Science & Engineering, 2022, 16(8): 97.

    • 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.