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Nov 2022, Volume 16 Issue 11
    
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  • VIEWS
    Yindong Tong, Xuejun Wang, James J. Elser

    Eutrophication is the most widespread water quality issue globally. To date, most efforts to control eutrophication have focused on reductions of external nutrient inputs, yet importance of nutrient stoichiometry and subsequent shift in plankton composition in aquatic ecosystem has been largely neglected. To address eutrophication, improved sanitation is one of the United Nations Sustainable Development Goals, spurring the constructions of wastewater treatment facilities that have improved water quality in many lakes and rivers. However, control measures are often targeted at and effective in removing a single nutrient from sewage and thus are less effective in removing the others, resulting in the changes of nutrient stoichiometry. In general, more effective phosphorus removal relative to nitrogen has occurred in wastewater treatment leading to substantial increases in N/P ratios in effluent relative to the influent. Unfortunately, high N/P ratios in receiving waters can impose negative influences on ecosystems. Thus, long-term strategies for domestic wastewater management should not merely focus on the total reduction of nutrient discharge but also consider their stoichiometric balances in receiving waters.

  • RESEARCH ARTICLE
    Olga S. Arvaniti, Marilena E. Dasenaki, Alexandros G. Asimakopoulos, Niki C. Maragou, Vasilios G. Samaras, Korina Antoniou, Georgia Gatidou, Daniel Mamais, Constantinos Noutsopoulos, Zacharias Frontistis, Nikolaos S. Thomaidis, Athanasios S. Stasinakis

    ● Different advanced treatment processes were tested for ECs removal from wastewater.

    ● UV radiation showed low to moderate removal for 5 of the 38 micropollutants.

    ● Among tested membrane processes, nanofiltration showed the better performance.

    ● The use of PAC achieved high or partially removal for 31 out of the 38 compounds.

    ● The environmental and economical evaluation of a pilot-scale PAC unit is suggested.

    In this work, 38 different organic emerging contaminants (ECs), belonging to various chemical classes such as pharmaceuticals (PhCs), endocrine-disrupting chemicals (EDCs), benzotriazoles (BTRs), benzothiazoles (BTHs), and perfluorinated compounds (PFCs), were initially identified and quantified in the biologically treated wastewater collected from Athens’ (Greece) Sewage Treatment Plant (STP). Processes already used in existing STPs such as microfiltration (MF), nanofiltration (NF), ultrafiltration (UF), UV radiation, and powdered activated carbon (PAC) were assessed for ECs’ removal, under the conditions that represent their actual application for disinfection or advanced wastewater treatment. The results indicated that MF removed only one out of the 38 ECs and hence it was selected as pretreatment step for the other processes. UV radiation in the studied conditions showed low to moderate removal for 5 out of the 38 ECs. NF showed better results than UF due to the smaller pore sizes of the filtration system. However, this enhancement was observed mainly for 8 compounds originating from the classes of PhCs and PFCs, while the removal of EDCs was not statistically significant. Among the various studied technologies, PAC stands out due to its capability to sufficiently remove most ECs. In particular, removal rates higher than 70% were observed for 9 compounds, 22 were partially removed, while 7 demonstrated low removal rates. Based on our screening experiments, future research should focus on scaling-up PAC in actual conditions, combining PAC with other processes, and conduct a complete economic and environmental assessment of the treatment.

  • RESEARCH ARTICLE
    Rui Yue, Zhikang Chen, Liujun Liu, Lipu Yin, Yicheng Qiu, Xianhui Wang, Zhicheng Wang, Xuhui Mao

    ● Coupling merits of SEE and ERH were explored by a laboratory-scale device.

    ● SEE promotes the soil electrical conductivity and ERH process.

    ● Preheating soil by ERH improves the soil permeability and SEE.

    ● Combined method is more energy-efficient for perchloroethylene extraction.

    In situ thermal desorption (ISTD) technology effectively remediates soil contaminated by dense nonaqueous phase liquids (DNAPLs). However, more efforts are required to minimize the energy consumption of ISTD technology. This study developed a laboratory-scale experimental device to explore the coupling merits of two traditional desorption technologies: steam-enhanced extraction (SEE) and electrical resistance heating (ERH). The results showed that injecting high-density steam (> 1 g/min) into loam or clay with relatively high moisture content (> 13.3%) could fracture the soil matrix and lead to the occurrence of the preferential flow of steam. For ERH alone, the electrical resistance and soil moisture loss were critical factors influencing heating power. When ERH and SEE were combined, preheating soil by ERH could increase soil permeability, effectively alleviating the problem of preferential flow of SEE. Meanwhile, steam injection heated the soil and provided moisture for maintaining soil electrical conductivity, thereby ensuring power stability in the ERH process. Compared with ERH alone (8 V/cm) and SEE alone (1 g/min steam), the energy consumption of combined method in remediating perchloroethylene-contaminated soil was reduced by 39.3% and 52.9%, respectively. These findings indicate that the combined method is more favorable than ERH or SEE alone for remediating DNAPL-contaminated subsurfaces when considering ISTD technology.

  • SHORT COMMUNICATION
    Shuyu Chen, Run Li, Yaqi Shen, Lu Zhan, Zhenming Xu

    ● The co-existing metals in WPCBs has positive catalytic influence in pyrolysis.

    ● Cu, Fe, Ni can promote reaction progress and reduce the apparent activation energy.

    ● Ni play better role in promoting WPCB pyrolysis reaction.

    Waste printed circuit boards (WPCBs) are generated increasingly recent years with the rapid replacement of electric and electronic products. Pyrolysis is considered to be a potential environmentally-friendly technology for recovering organic and metal resources from WPCBs. Thermogravimetric analysis and kinetic analysis of WPCBs were carried out in this study. It showed that the co-existing metals (Cu, Fe, Ni) in WPCBs have positive self-catalytic influence during the pyrolysis process. To illustrate their catalytic effects, the apparent activation energy was calculated by differential model. Contributions of different reactions during catalytic pyrolysis process was studied and the mechanism function was obtained by Šesták-Berggren model. The results showed that Cu, Fe, Ni can promote the reaction progress and reduce the apparent activation energy. Among the three metals, Ni plays better catalytic role than Cu, then Fe. This work provides theoretical base for understanding the three metals’ catalytic influence during the pyrolysis of non-metal powders in WPCBs.

  • RESEARCH ARTICLE
    Yu Xia, Xuyang Zhang, Miao Zhang, Liming Chen, Xiaotong Tang, Yuhong Sun, Xiang Li

    ● Wastewater MPs exhibited resistomes and therefore health threats.

    ● High density of alkB gene indicates both HDPE and PET can be utilized by microbes.

    ● Plastics and waters actively selected and shaped the plastispheres over time.

    ● A broader phylogenetic spectrum of MHET-degrading microorganisms was annotated.

    The daily use of plastics presents a serious pollution issue due to their extremely slow degradation. Microplastics and the biofilm that grows on plastics (i.e., the plastisphere) are important subsets of plastic wastes. Many studies have been conducted to reveal the structures of the plastispheres, the driving factors for the formation of the plastisphere, and the ability of the plastispheres to degrade plastics in a variety of water bodies. However, the plastispheres related to wastewater are understudied. In this study, we used a microcosmic strategy to study the evolution of the plastispheres associated with microplastics (MPs) over time in wastewater. We found that plastic materials and water sources did not actively select and shape the plastispheres at an early stage, but the active selection for a unique niche of the plastisphere occurred after 14 d of growth. In addition, we confirmed that the alkB gene was densely present, and metagenomics showed some additional chemical reactions, which suggests that MPs are consumed by the microbes in the plastispheres. Additionally, metagenomics identified some metagenome-assembled genomes (MAGs) associated with high-density polyethylene (HDPE) and polyethylene terephthalate (PET). The identification of HDPE-associated MAGs and PET-associated MAGs further supports the notion that the selection for a unique niche of the plastisphere is driven by plastic materials and water sources (in this study, after 14 d of growth). Our discoveries bring new views on the behavior of the wastewater-associated plastisphere, especially how long it takes a wastewater plastisphere to form.

  • RESEARCH ARTICLE
    Mingyi Yang, Lin Shi, Di Zhang, Zhaohui He, Aiping Liang, Xiao Sun

    ● Adsorption of environmental deoxyribonucleic acid on biochar was studied.

    ● π−π interaction and electrostatic repulsion worked in the adsorption.

    ● Thermodynamics indicated the adsorption was spontaneous and endothermic.

    Environmental deoxyribonucleic acid (eDNA), which includes antibiotic resistance genes, is ubiquitous in the environment. The interactions between eDNA and biochar, a promising material widely used in soil amendment and water treatment, greatly affect the environmental behavior of eDNA. Hitherto few experimental evidences are available yet, especially on the information of thermodynamics and energy distribution to explains the interactions between biochar and eDNA. This study investigated the adsorption of herring sperm DNA (hsDNA) on pine sawdust biochar, with a specific emphasis on the adsorption thermodynamics and site energy distribution. The adsorption of hsDNA on biochar was enhanced by an increase in the pyrolysis and adsorption temperatures. The higher surface area, stronger π−π interaction, and weaker electrostatic repulsion between hsDNA and biochars prepared at high pyrolysis temperatures facilitated the adsorption of hsDNA. The thermodynamics indicated that the adsorption of hsDNA on biochar was spontaneous and endothermic. Therefore, higher temperature was beneficial for the adsorption of hsDNA on biochar; this was well explained by the increase in E* and F(E*) with the adsorption temperature. These results are useful for evaluating the migration and transformation of eDNA in the presence of biochar.

  • RESEARCH ARTICLE
    Juan Liu, Guanjun Xu, Xuejun Ruan, Kejian Li, Liwu Zhang

    ● V-shaped substrate was obtained for SERS analysis of microplastics (diameter ≈ 1 μm).

    ● Enhancement factor of V-shaped substrate can reach 20 in microplastics detection.

    ● V-shaped nanopore array can bring additional volume enhancement.

    ● V-shaped substrate was more economic in application compared to Klarite substrate.

    Research on the microplastics (MPs) is developing towards smaller size, but corresponding methods for the rapid and accurate detection of microplastics, especially nanoplastics still present challenge. In this work, a novel surface and volume enhanced Raman spectroscopy substrate was developed for the rapid detection of microplastic particles below 5 μm. The gold nanoparticles (NPs) were deposited onto the surface and into the V-shaped nanopores of anodized aluminum oxide (AAO) through magnetron sputtering or ion sputtering, and then AuNPs@V-shaped AAO SERS substrate was obtained and studied for microplastic detection. SERS performance of AuNPs@V-shaped AAO SERS substrate was evaluated through the detection of polystyrene and polymethyl methacrylate microspheres. Results indicated that individual polystyrene sphere with a diameter of 1 μm can be well detected on AuNPs@V-shaped AAO SERS substrate, and the maximum enhancement factor (EF) can reach 20. In addition, microplastics in ambient atmospheric samples were collected and tested to verify the effectiveness of the AuNPs@V-shaped AAO SERS substrate in the real environment. This study provides a rapid, economic and simple method for detecting and identifying microplastics with small size.

  • RESEARCH ARTICLE
    Sen Dong, Peng Gao, Benhang Li, Li Feng, Yongze Liu, Ziwen Du, Liqiu Zhang

    ● 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
    Yifan Liu, Qiongfang Zhang, Ainiwaer Sidike, Nuerla Ailijiang, Anwar Mamat, Guangxiao Zhang, Miao Pu, Wenhu Cheng, Zhengtao Pang

    ● Presented coupled system enhanced biodegradation of antibiotic chloramphenicol.

    ● HRT and electrical stimulation modes were key influencing factors.

    ● Electrical stimulation had little effect on the chloramphenicol metabolic pathway.

    ● Microbial community structure varied with the voltage application mode.

    Exoelectrogenic biofilms have received considerable attention for their ability to enhance electron transfer between contaminants and electrodes in bioelectrochemical systems. In this study, we constructed anaerobic-aerobic-coupled upflow bioelectrochemical reactors (AO-UBERs) with different voltage application modes, voltages and hydraulic retention times (HRTs). In addition, we evaluated their capacity to remove chloramphenicol (CAP). AO-UBER can effectively mineralize CAP and its metabolites through electrical stimulation when an appropriate voltage is applied. The CAP removal efficiencies were ~81.1%±6.1% (intermittent voltage application mode) and 75.2%±4.6% (continuous voltage application mode) under 0.5 V supply voltage, which were ~21.5% and 15.6% greater than those in the control system without voltage applied, respectively. The removal efficiency is mainly attributed to the anaerobic chamber. High-throughput sequencing combined with catabolic pathway analysis indicated that electrical stimulation selectively enriched Megasphaera, Janthinobacterium, Pseudomonas, Emticicia, Zoogloea, Cloacibacterium and Cetobacterium, which are capable of denitrification, dechlorination and benzene ring cleavage, respectively. This study shows that under the intermittent voltage application mode, AO-UBERs are highly promising for treating antibiotic-contaminated wastewater.

  • RESEARCH ARTICLE
    Jie Wu, Jian Lu, Jun Wu

    ● Organic matter content significantly affected adsorption of E2/EE2 on saline soil.

    ● EE2 possessed higher competition intensity for adsorption sites than E2.

    ● The adsorption of E2/EE2 on saline soil was a spontaneous exothermic process.

    ● Desorption capacity of EE2/E2 accounted for 40%/78% of the total adsorption capacity.

    Soil organic matter content was the main driving factor affecting adsorption and desorption process of 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) on saline soil. The adsorption and desorption of E2 and EE2 on three saline soils showed the similar behavior that soil with the highest organic content possessed the highest adsorption capacity and the lowest desorption capacity for E2 and EE2. The adsorption capacity of untreated soil samples (with organic matter) was larger than that of soil samples without organic matter. For soil with the largest adsorption capacity, adsorption capacity of E2/EE2 on the untreated soil and soil colloid (with organic matter) respectively reached 0.15/0.30 μg/g and 0.16/0.33 μg/g while the soil and soil colloid without organic matter hardly adsorbed pollutants. The adsorption capacity of E2/EE2 at the initial concentration of 100 μg/L was 25/15 times higher than that at the initial concentration of 5 μg/L. E2 and EE2 had the same adsorption sites on saline soil while EE2 possessed higher competition intensity for adsorption sites than E2. Pseudo-first-order model (R2 = 0.995–0.986) and Langmuir model (R2 = 0.989–0.999) could better fit the adsorption process of E2 or EE2. The thermodynamic study further showed that the adsorption of E2/EE2 on saline soil was a spontaneous exothermic process. The desorption capacity of EE2/E2 accounted for 40%/78% of the total adsorption capacity to possibly exert potential risk to the groundwater. The variation of the salinity led to the variation of soil organic carbon which subsequently changed the adsorption and desorption behaviors of endocrine disrupting chemicals in coastal saline soil. This study provides a new insight on the interfacial behavior of endocrine disrupting chemicals on saline soil.

  • RESEARCH ARTICLE
    Yangyan Cheng, Ye Shan, Yuhuan Xue, Yujiao Zhu, Xinfeng Wang, Likun Xue, Yanguang Liu, Fangli Qiao, Min Zhang

    ● Diurnal patterns of CH4 and CO2 are clearly extracted using EEMD.

    ● CH4 and CO2 show mid-morning high and evening low patterns during sea breezes.

    ● Wind direction significantly modulates the diurnal variations in CH4 and CO2.

    Methane (CH4) and carbon dioxide (CO2) are the two most important greenhouse gases (GHGs). To examine the variation characteristics of CH4 and CO2 in the coastal South China Sea, atmospheric CH4 and CO2 measurements were performed in Bohe (BH), Guangdong, China, in summer 2021. By using an adaptive data analysis method, the diurnal patterns of CH4 and CO2 were clearly extracted and analysed in relation to the sea breeze (SB) and land breeze (LB), respectively. The average concentrations of CH4 and CO2 were 1876.91 ± 31.13 ppb and 407.99 ± 4.24 ppm during SB, and 1988.12 ± 109.92 ppb and 421.54 ± 14.89 ppm during LB, respectively. The values of CH4 and CO2 during SB basically coincided with the values and trends of marine background sites, showing that the BH station could serve as an ideal site for background GHG monitoring and dynamic analysis. The extracted diurnal variations in CH4 and CO2 showed sunrise high and sunset low patterns (with peaks at 5:00–7:00) during LB but mid-morning high and evening low patterns (with peaks at 9:00) during SB. The diurnal amplitude changes in both CH4 and CO2 during LB were almost two to three times those during SB. Wind direction significantly modulated the diurnal variations in CH4 and CO2. The results in this study provide a new way to examine the variations in GHGs on different timescales and can also help us gain a better understanding of GHG sources and distributions in the South China Sea.

  • RESEARCH ARTICLE
    Qingqing Li, Chao Lv, Xiangwei Xia, Chao Peng, Yan Yang, Feng Guo, Jianfeng Zhang

    ● PDA-Fe3O4-Ag was made by hydrothermal and oxidation self-polymerization method.

    ● PDA-Fe3O4-Ag had great magnetic separation performance.

    ● PDA-Fe3O4-Ag had good adsorption and degradation performance for ionic dyes.

    ● PDA-Fe3O4-Ag showed NR and MO degradation potential of 91.2% and 87.5%, respectively.

    High-performance adsorbents have been well-studied for the removal of organic dye pollutants to promote environment remediation. In this study, an Ag nanoparticle-functionalized Fe3O4-PDA nanocomposite adsorbent (PDA-Fe3O4-Ag) was synthesized, and the adsorption/separation performance of commonly used cationic and anionic organic dyes by the PDA-Fe3O4-Ag adsorbent were assessed. Overall, PDA-Fe3O4-Ag exhibited a significantly higher adsorption capacity for cationic dyes compared to anionic dyes, the highest of which was more than 110.0 mg/g (methylene blue (MB)), which was much higher than not only the adsorption capacities of the anionic dyes in this study but also other dye adsorption capacities reported in the literature. The dye adsorption kinetics data fitted well to both the pseudo second-order kinetics model and the Langmuir isotherm model, suggesting a monolayer-chemisorption-dominated adsorption mode. Thermodynamics analysis indicated that the adsorption process was both endothermic and spontaneous. Furthermore, the PDA-Fe3O4-Ag adsorbent achieved high photodegradation removal rates of the dyes, especially neutral red (NR) and methyl orange (MO), which were 91.2% and 87.5%, respectively. With the addition of PDA-Fe3O4-Ag, the degradation rate constants of NR and MO increased from 0.08 × 10−2 and 0 min−1 to 2.11 × 10−2 and 1.73 × 10−2 min−1, respectively. The high adsorption and photocatalytic degradation performance of the PDA-Fe3O4-Ag adsorbent make it an excellent candidate for removing cationic and anionic dyes from the industrial effluents.

  • REVIEW ARTICLE
    Yang Yang, Xiuzhen Zheng, Wei Ren, Jiafang Liu, Xianliang Fu, Sugang Meng, Shifu Chen, Chun Cai

    ● 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.