Cover illustration
Front Cover Story (See: Yuhang Liu, Wenxuan Deng, Xiaojun Wu, Chun Hu, Lai Lyu, 2024, 18(4): 44)
The effective removal of emerging contaminants (ECs) to avoid negative impacts on human health and the natural environment is a global challenge. Herein, a seaweed spherical microsphere catalyst with cation-π structures was fabricated via a hydrothermal method to remove ECs in water. The results show that bisphenol A is substantially degraded within 5 min under natural cond
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● “Electrons surplus” is the underlying cause of the anaerobic digestion collapse. ● Electronic regulation is proposed to improve the efficiency of anaerobic digestion. ● Electrons shunt enhances syntrophic oxidation of volatile fatty acids. ● Direct interspecies electron transfer improves electron transfer efficiency. ● Methanogenic metabolism pathway regulation alters electron utilization patterns.
Anaerobic digestion (AD) of organic fraction of municipal solid waste (OFMSW) is prone to system breakdown under high organic loading rates (OLRs) condition, which subsequently reduces the efficiency of digestion process and results in substantial economic losses. In this perspective paper, the substances metabolisms, electrons flow, as well as microbial interaction mechanisms within AD process are comprehensively discussed, and the underlying bottleneck that causes inefficient methane production is identified, which is “electrons surplus”. Systems encountering severe electron surplus are at risk of process failure, making it crucial to proactively prevent this phenomenon through appropriate approaches. On this basis, the present perspective proposes three potential electronic regulation strategies to prevent electrons surplus, namely, electron shunt, accelerating electron transfer and regulating methanogenic metabolism pathway, and presents specific methodologies for each strategy. Furthermore, the potential solutions to challenges that may occur during the electronic regulation process are also presented in this paper. This perspective aims to provide innovative approaches to achieve the efficient and stable operation of OFMSW anaerobic digestion, especially under high OLRs condition.
● A novel hydrogel (2%-SKP-Ca2+) was developed by macro-micro dual biomimetic strategy. ● Mechanical properties of 2%-SKP-Ca2+ were enhanced by triple crosslinking method. ● Unique micro umbrella structure of 2%-SKP-Ca2+ can improve its pore structure. ● 2%-SKP-Ca2+ can be effectively used as multi-substrate anti-fouling coatings. ● 2%-SKP-Ca2+ can efficiently purify both emulsified oil and methylene blue solution.
Recently, research on hydrogel materials with a porous structure and superior water absorption capabilities significantly grown. However, the hydrogel under gravity-driven separation conditions often exhibit an unstable pore structure, poor mechanical properties, and limited functionality. To this end, this work presents a novel approach that combines a macro-micro double bionic strategy with a triple crosslinking method to develop a multifunctional alginate composite hydrogel filter (2%-SA-κ-CG-PVA-Ca2+, 2%-SKP-Ca2+ for short) with a stable pore structure and superior mechanical properties, which possessed an umbrella-shaped structure resembling that of jellyfish. The 2%-SKP-Ca2+ filter was synthesized using polyvinyl alcohol (PVA) as a stable structure-directing agent, and sodium alginate (SA) and κ-carrageenan (κ-CG) as polymer hydrogels. The distinctive umbrella-shaped hydrogel of 2%-SKP-Ca2+ filter, formed through the triple crosslinking method, overcomes the limitations of unstable pore structure and poor durability seen in hydrogels prepared by traditional crosslinking methods. Furthermore, the utilization of the 2%-SKP-Ca2+ filter in water treatment demonstrates its good selective permeability, excellent resistance to fouling, and extended longevity, which enables it to simultaneously achieve the multifunctional water purification and the coating of multi-substrate anti-fouling coatings. Therefore, not only does this research provide an efficient, multi-functional, highly pollution-resistant preparation method for designing a new filter, but it also confirms the application prospect of the macro-micro dual bionic strategy developed in this study in complex water treatment.
● Simplified ADM1 can predict biogas production from a full-scale biogas plant. ● Default parameters allowed for an accurate process simulation. ● Measurement variability did not affect simulated biogas and methane flow. ● Degradability of carbohydrates had a remarkable effect on gas yields.
Mathematical modeling of anaerobic digestion is a powerful tool to predict gas yields and optimize the process. The Anaerobic Digestion Model No. 1 (ADM1) is a widely implemented model for this purpose. However, modeling full-scale biogas plants is challenging due to the extensive substrate and parameter characterization required. This study describes the modification of the ADM1 through a simplification of individual process phases, characteristic components and required parameters. Consequently, the ability of the simplified model to simulate the co-digestion of grass silage and cattle slurry was evaluated using data from a full-scale biogas plant. The impacts of substrate composition (crude carbohydrate, protein and lipid concentration) and variability of carbohydrate degradability on simulation results were assessed to identify the most influential parameters. Results indicated that the simplified version was able to depict biogas and biomethane production with average model efficiencies, according to the Nash-Sutcliffe efficiency (NSE) coefficient, of 0.70 and 0.67, respectively, and was comparable to the original ADM1 (average model efficiencies of 0.71 and 0.63, respectively). The variability of crude carbohydrate, protein and lipid concentration did not significantly impact biogas and biomethane output for the data sets explored. In contrast, carbohydrate degradability seemed to explain much more of the variability in the biogas and methane production. Thus, the application of simplified models provides a reliable basis for the process simulation and optimization of full-scale agricultural biogas plants.
● Photodegraded polyvinyl chloride nanoplastics (PVC-NPs) inhibited pea seedlings’ growth. ● Photodegraded PVC-NPs resulted in damage of leaf stomata and roots. ● Photodegraded PVC-NPs influenced protein processing in endoplasmic reticulum. ● Photodegraded PVC-NPs influenced phenylpropanoid biosynthesis.
Nanoplasctics (NPs), which are very small in particle size, exert toxic effect to organisms. Additionally, compared to original NPs, photodegraded NPs would pose higher toxicity. This is because their relatively higher specific surface areas and the presence of additives which can more easily leach. How original NPs and aged NPs affect plant growth has not been widely investigated. This work chose polyvinyl chloride NPs (PVC-NPs) that were subjected to up to 1000 h UV light radiation to explore the impact of PVC-NPs on the growth of pea seedlings (Pisum Sativum L.). The results indicated the existence of PVC-NPs with longer UV light radiation time and higher concentrations had more negative influences on pea seedlings’ growth such as germination rate (decreased by 10.6%–22.5%), stem length (decreased by 2.8%–8.1%), dry weight (decreased by 6.3%–7.1%) and fresh weight (decreased by 6.7%–14.8%). It was also noted that photodegraded PVC-NPs resulted in damage to leaf stomata and roots, hindering photosynthesis and absorption of nutrients and hence the decrease in chlorophyll and soluble sugar contents. According to transcriptomic investigation results, the presence of aged PVC-NPs primarily influenced protein processing in endoplasmic reticulum (upregulated metabolic pathway) and phenylpropanoid biosynthesis (downregulated metabolic pathway) of pea seedlings. These results provide an in-depth understanding of how NPs influence the growth of plants.
● The first study of electrochemically active magnetotactic bacteria. ● Two magnetotactic species are able to generate current in microbial fuel cells. ● Electron shuttle resazurin enables both species to reduce the crystalline Fe2O3. ● M. magneticum can reduce poorly crystalline iron oxide (FeOOH). ● Electroactivity might be common for magnetotactic bacteria.
Magnetotactic bacteria reside in sediments and stratified water columns. They are named after their ability to synthesize internal magnetic particles that allow them to align and swim along the Earth’s magnetic field lines. Here, we show that two magnetotactic species, Magnetospirillum magneticum strain AMB-1 and Magnetospirillum gryphiswaldense strain MSR-1, are electroactive. Both M. magneticum and M. gryphiswaldense were able to generate current in microbial fuel cells with maximum power densities of 27 and 11 µW/m2, respectively. In the presence of the electron shuttle resazurin both species were able to reduce the crystalline iron oxide hematite (Fe2O3). In addition, M. magneticum could reduce poorly crystalline iron oxide (FeOOH). Our study adds M. magneticum and M. gryphiswaldense to the growing list of known electroactive bacteria, and implies that electroactivity might be common for bacteria within the Magnetospirillum genus.
● MnO2/PCL composite material (MPCM) enhances ammonia and nitrate removal in CWs. ● The reduction and re-oxidation of MnO2 both facilitate the removal of ammonia. ● Mnammox accounts for 17.16%–27.24% of ammonia removal at the height of 0–20 cm. ● MPCM promotes the richness of ammonia oxidizers and denitrifiers in CWs. ● MPCM significantly decreases N2O emission in CWs.
Constructed wetlands (CWs) are widely used to treat secondary effluent. However, simultaneously removing ammonia (NH4+-N) and nitrate (NO3––N) is challenging because of insufficient oxygen and carbon sources. In this study, a novel composite material (MPCM) comprising MnO2 and polycaprolactone was developed as a substrate for CWs to enhance the synchronous removal of NH4+–N and NO3––N. The CWs with a higher MPCM content (H-CW), lower MPCM content (L-CW), and controlled CW (C-CW) exhibited average NH4+–N removal efficiencies of 75.69%, 70.49%, and 52.40%, respectively. The 15N isotope tracking technique showed that NH4+–N removal was attributed to anaerobic ammonia oxidation mediated by MnO2 reduction (Mnammox), which accounted for 17.16%–27.24% of the NH4+–N removal in the composite material layers (0–20 cm) of the H-CW and L-CW. The richness of ammonia oxidizers in the upper layers (40–50 cm) of the H-CW and L-CW further facilitated NH4+–N removal. Moreover, the average total nitrogen (TN) removal efficiencies of the H-CW and L-CW were 1.99 and 1.59 times that of C-CW, respectively, owing to enhanced denitrification by MPCM. Furthermore, N2O emissions were reduced by 81.31% and 70.83% in the H-CW and L-CW, respectively. This study provides an effective approach for improving nitrogen removal and reducing N2O emissions during the treatment of secondary effluent by CWs.
● Wastewater reuse for groundwater replenishment and agricultural irrigation. ● Assessment of (in)organic pollutants in WWTP effluent and adjacent water systems. ● Measurement of bioavailable inorganic pollutants using DGT technique. ● Calculation of lability of inorganic pollutants based on the DGT results.
Under the pressure of global droughts and water shortage, it is essential to evolve toward a sustainable and robust water system. One possible avenue is the maximum reuse of treated wastewater, but the quality of which determines its reuse. Therefore, inorganic (Cd, Pb, Cr, Ni, Cu, and As) and organic (xenoestrogens and polycyclic aromatic contaminants, PACs) contaminants were monthly monitored in an effluent of the wastewater treatment plant (WWTP), the surrounding surface waters and the local groundwater in Belgium. Dissolved and particulate concentrations of inorganic contaminants in these water bodies were analyzed. In addition, Diffusive Gradients in Thin-films (DGT) was used in situ to obtain bioavailable metal fractions. In the WWTP effluent and surface waters, only Ni exceeds the Annual Average-Environmental Quality Standard (AA-EQS), while in the groundwater, dissolved As was the predominant element. Moreover, in the surface and effluent waters the highest lability degrees were observed for Cd and Ni. The concentrations of these metal species in the effluent water were lower than in the other water bodies. Micro-organic pollutants, xenoestrogens and PACs were analyzed by dual Estrogen and Aryl hydrocarbon Receptor - Chemical Activated LUciferase gene eXpression (ER & AhR-CALUX) assays. Since the annual averaged (AA) bioequivalent concentration of E2 (0.18 ng/L) is below the AA-EQS standard (0.4 ng/L), and the bioequivalent concentration of benzo[a]pyrene never exceeded the maximum admissible concentration (MAC), the reclamation and reuse of treated wastewater for groundwater replenishment and agricultural irrigation should pose no environmental problems, at least in a short-term.
● Urethane functionalities created on PES membranes via electron beam irradiation. ● Water contact angle decreased from 58° to 52°, higher hydrophilicity. ● 13% increase in water permeability via functionalization. ● 17β-estradiol adsorption enhanced by five times. ● Functionalized membranes reused for three cycles without a loss of adsorption capacity.
Polyethersulphone (PES) membranes modified with urethane functional groups were prepared through an interfacial reaction using electron beam irradiation. The removal of eight endocrine disrupting chemicals (EDCs) was studied using both pristine and functionalized PES membranes. The prepared membranes underwent characterization using several techniques, including attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy, contact angle analysis, and measurements of pure water flux. Furthermore, dynamic adsorption experiments were conducted to evaluate the adsorption mechanism of the prepared membrane toward the eight EDCs. The urethane functionalized membranes were hydrophilic (52° contact angle) and maintained a high permeate flux (26000 L/h m2 bar) throughout the filtration process. Dynamic adsorption results demonstrated that the introduction of urethane functional groups on the membranes significantly enhanced the removal efficiency of 17β-estradiol, estriol, bisphenol A, estrone, ethinylestradiol, and equilin. The adsorption loading of 17β-estradiol on the functionalized PES membrane was 6.7 ± 0.7 mg/m2, exhibiting a 5-fold increase compared to the unmodified PES membrane. The membranes were successfully regenerated and reused for three adsorption cycles without experiencing any loss of adsorption capacity.
● Cu-C-MSNs are developed via a co-doping step of Cu with L(+)-ascorbic acid. ● Cu-C-MSNs show superb performance in removing contaminants and purifying wastewater. ● The performance is owing to the polarization electric field and cation-π structures. ● The biological toxicity of bisphenol A is considerably weakened after the reaction.
Effective removal of emerging contaminants (ECs) to minimize their impacts on human health and the natural environment is a global priority. For the removal of ECs in water, we fabricated a seaweed spherical microsphere catalyst with Cu cation-π structures by in situ doping of Cu species and ascorbic acid in mesoporous silica (Cu-C-MSNs) via a hydrothermal method. The results indicate that bisphenol A (BPA) is substantially degraded within 5 min under natural conditions, with its biological toxicity considerably weakened. Moreover, industrial wastewater could also be effectively purified by Cu-C-MSNs/H2O2 system. The presence of metal sites and the complexation of ECs via cation-π interaction and π-π stacking on the catalyst surface were directly responsible for the polarization distribution of electrons, thus activating H2O2 and dissolved oxygen (DO). The removal of contaminants could be attributed primarily to 1) the activation of H2O2 into •OH to attack the contaminants and 2) self-cleavage because of the transfer of electrons from the contaminants to the catalysts. This study provides an innovative solution for the effective treatment of ECs and has positive implications for easing global environmental crises.
● The situation of endosulfan residues in cotton fields were assessed. ● A KAP survey was carried out for cotton farmers. ● Endosulfan sulfate was the main endosulfan residue in the soil. ● Cotton farmers scored low on knowledge about the phase-out of endosulfan.
We assessed the situation of endosulfan residues in cotton fields after the endosulfan ban came into effect and the current knowledge, attitude, and practice (KAP) of cotton farmers on the phase-out of endosulfan and the application of alternative technologies. Topsoil samples (n = 91) of cotton fields were collected from the major cotton-producing areas in China, namely the north-west inland cotton region, and the endosulfan residues were analyzed. A KAP survey was carried out for cotton farmers, and 291 questionnaires were distributed. The influences of gender, age, education background, cotton planting years, publicity and training, income sources, and other factors on cotton farmers’ KAP were analyzed. The results showed that endosulfan sulfate was the main endosulfan residue in the soil, followed by β-endosulfan and α-endosulfan, the average residual contents were 0.569, 0.139, and 0.060 µg/kg, respectively. The results of the KAP study showed that cotton farmers scored low on knowledge about the phase-out of endosulfan and the application of alternative technologies but high on attitude and practice. The number of family members, years of cotton planting, age, and the cotton-planting area had different degrees of influence on KAP scores. The training could significantly improve the KAP scores of cotton farmers; training should be more targeted and designed reasonably for key groups, such as men and the population under 30, followed by training them to use pesticides safely. For large-scale cotton growers, training should focus on green prevention and control technologies.
● Bioretention systems showed > 92% load reduction rates of PAHs. ● PAHs were accumulated in the upper layer of media 10–40 cm. ● The fate of PAHs in bioretention systems by different design scenarios were revealed. ● NAP was degraded within 40 d while FLT and PYR were not completely degraded. ● PAHs didn’t show accumulation trends under continuous rainfall events.
Polycyclic aromatic hydrocarbons (PAHs) present significant risks to human health owing to their carcinogenic, teratogenic, and mutagenic properties. The contamination of surface water with PAHs via runoff has become a prominent source of water pollution. While the capacity of bioretention systems to remove PAHs from runoff is recognized, the dynamics of PAH migration and degradation in these systems are not well-understood. This study aims to explain the migration and fate of PAHs in bioretention systems through a series of experiments and model simulations. This study constructed bioretention systems with three different media types and found that these systems achieved PAH load reductions exceeding 92%. Notably, naphthalene (NAP), fluoranthene (FLT), and pyrene (PYR) tended to accumulate in the media’s upper layer, at depths of 10 to 40 cm. To further analyze the migration and fate of PAHs during multi-site rainfall events and across prolonged operation, we applied the HYDRUS-1D model under three distinct scenarios. The findings of this study indicated that NAP degraded in 40 d, whereas FLT and PYR showed incomplete degradation after 120 d. During continuous rainfall events, there was no clear pattern of PAH accumulation; however, FLT and PYR persisted in the bioretention systems. The combination of experimental and simulation findings highlights the inevitable accumulation of PAHs during extended use of bioretention systems. This research provides a theoretical basis for improving operational efficiency, advancing PAH degradation in bioretention systems, and reducing their toxicity.
● We find air pollution distracts attention and reveal the neurocognitive mechanisms. ● Clean air captures more attention and evokes larger N300 amplitudes in all trials. ● Pollution causes lower accuracy and larger P300 wave in attention-holding trials. ● Pollution causes higher accuracy and lower P300 wave in attention-shifting trials.
Awareness of the adverse impact of air pollution on attention-related performance such as learning and driving is rapidly growing. However, there is still little known about the underlying neurocognitive mechanisms. Using an adapted dot-probe task paradigm and event-related potential (ERP) technique, we investigated how visual stimuli of air pollution influence the attentional allocation process. Participants were required to make responses to the onset of a target presented at the left or right visual field. The probable location of the target was forewarned by a cue (pollution or clean air images), appearing at either the target location (attention-holding trials) or the opposite location (attention-shifting trials). Behavioral measures showed that when cued by pollution images, subjects had higher response accuracy in attention-shifting trials. ERP analysis results revealed that after the cue onset, pollution images evoked lower N300 amplitudes, indicating less attention-capturing effects of dirty air. After the target onset, pollution cues were correlated with the higher P300 amplitudes in attention-holding trials but lower amplitudes in attention-shifting trials. It indicates that after visual exposure to air pollution, people need more neurocognitive resources to maintain attention but less effort to shift attention away. The findings provide the first neuroscientific evidence for the distracting effect of air pollution. We conclude with several practical implications and suggest the ERP technique as a promising tool to understand human responses to environmental stressors.
● A spindle-shaped influent chamber was designed and equipped in FCDI system. ● CFD is used to analyze the hydrodynamics of raw water in the intermediate chamber. ● The spindle-shaped chamber avoided the stagnation zone in the intermediate chamber.
Flow-electrode capacitive deionization (FCDI) is an innovative technology in which an intermediate chamber plays an important role in the desalination process. However, relatively few studies have been conducted on the structures of these intermediate chambers. In this study, we propose a novel flow-electrode capacitive deionization device with a spindle-shaped inlet chamber (S-FCDI). The desalination rate of the S-FCDI under optimal operating conditions was 36% higher than that of the FCDI device with a conventional rectangular chamber (R-FCDI). The spindle-shaped chamber transferred 1.2 μmol more ions than the rectangular chamber, based on energy per joule. Additionally, we performed a detailed analysis of different inlet chamber shapes using computational fluid dynamics software. We concluded that S-FCDI has a relatively low flow resistance and almost no stagnation zone. This provides unique insights into the development of intermediate chambers. This study may contribute to the improvement of the desalination performance in industrial applications of FCDI.
