Wastewater Treatment Strategies Research Articles

Electrochemical activity of self-supporting nitrogen-doped graphene for the degradation and in-situ determination of methylene blue

Environmentally friendly wastewater treatment and online pollution monitoring systems, important for water quality control, are yet to be developed. Electrochemical strategies combining the electrocatalytic degradation and electroanalysis of organic pollutants are expected to achieve this key technology. This study employed a chemical vapor deposition method using N₂ gas as the nitrogen source and applying an alternating electric field to prepare self-supporting nitrogen-doped graphene (NG) tubes with a wall thickness of up to 480 μm comprising few-layer NG nanosheets. The correlation between the properties of these materials and the electrocatalytic activity for methylene blue (MB) was investigated. The feasibility of the electrochemical strategy for online wastewater treatment and detection was validated using a combination of UV–visible spectroscopy and differential pulse voltammetry. The NG tube with the N-C bond distribution regulated by adjusting the methane flow rate and growth time exhibited high electrocatalytic activity, rapidly degrading 50 mg L⁻¹ of MB within 36 min and tracking changes in MB concentration. The NG tubes were assembled in an electrocatalytic meter pen for water treatment, achieving a degradation efficiency of 99.4 % and a detection limit of 0.3 mg L−1 for the MB solution, quite satisfactory for emerging simultaneous degradation and monitoring processes. The developed self-supporting NG tubes are promising materials for electrocatalytic degradation anodes and sensing electrodes in water treatment. Dual-functional electrocatalytic systems have potential applications in water quality monitoring and improvement.

Performance Assessment of Rural Decentralized Domestic Wastewater Treatment Facilities in Foshan, China

Rural decentralized domestic wastewater treatment (DDWT) facilities, as an alternative to centralized sewage treatment plants, have been rapidly developed in rural areas worldwide. However, the lack of performance evaluations and operational status assessments of these facilities poses a significant obstacle to advancements in rural domestic wastewater treatment strategies. In the present study, 30 rural DDWT facilities with AO (anoxic/oxic) and AAO (anaerobic/anoxic/oxic) processes were investigated. The results revealed that only two facilities reached the first A-grade discharge standards of China, and twelve facilities met the first B-grade discharge standards for all ten wastewater quality indicators. Low standard-achieving ratios for biochemical oxygen demand (BOD5) (63.3%), total nitrogen (TN) (60.0%), ammonia nitrogen (NH3-N) (63.3%), total phosphorus (TP) (30.0%), suspended solids (SS) (46.7%), and fecal coliforms (FC) (26.7%) were calculated. Thus, it is essential to improve the treatment efficiency for BOD5, TN, NH3-N, TP, SS, and FC for rural wastewater treatment facilities. In addition, the AAO process had a median weighted average removal efficiency of 82.02%, which was better than that of the AO process (72.48%). Minor equipment failure rates, i.e., less than 20%, did not affect the operation of the rural DDWT facilities, since most equipment in the DDWT facilities was backed up. Notably, problems in several areas, e.g., process design, equipment selection, construction, and especially operations, influencing treatment performance should be investigated and proactively addressed. These findings provide specific suggestions for improvements that could benefit the long-term operation and management of rural DDWT facilities.

Comprehensive study on the selection and performance of the best electrode pair for electrocoagulation of textile wastewater using multi-criteria decision-making methods (TOPSIS, VIKOR and PROMETHEE II)

The accelerating environmental impact of the textile industry, especially in water management, requires efficient wastewater treatment strategies. This study examines the effectiveness of various electrode pairs in the Electrocoagulation (EC) process for treating textile wastewater, focusing on removing of Total Suspended Solids (TSS), turbidity, Chemical Oxygen Demand (COD), and Total Organic Carbon (TOC). A comprehensive analysis was conducted using thirty-six electrode pair combinations, consisting of six materials: Aluminium (Al), Zinc (Zn), Carbon (C), Copper (Cu), Mild Steel (MS), and Stainless Steel (SS). The results demonstrated that different electrode pairs yielded varying removal efficiencies for various pollutants, with the highest efficiencies being 92.09% for COD (Al–C pair), 99.66% for TSS (Al–Cu pair), 99.17% for turbidity (Al-MS pair), and 70.99% for TOC (SS-SS pair). However, no single electrode pair excelled in removing all pollutant categories. To address this, three Multi-Criteria Decision Making (MCDM) methods such as TOPSIS, VIKOR, and PROMETHEE II were used to assess the most effective electrode pair. The results indicated that the Al–Zn combination was the most efficient, exhibiting high removal efficiencies for various pollutants (99.32% for TSS, 98.88% for turbidity, 68.62% for COD, and 57.96% for TOC). This study demonstrates that the EC process can effectively treat textile effluent and emphasizes the importance of selecting suitable electrode materials. Furthermore, pollutant removal was optimal with the Al–Zn electrode pair, offering a balanced and efficient approach to textile wastewater treatment. Thus, MCDM methods offer a robust framework for assessing and optimizing electrode selection, providing valuable insights for sustainable environmental management practices.

Removal of metals and emergent contaminants from liquid digestates in constructed wetlands for agricultural reuse.

Given the increasing pressure on water bodies, it is imperative to explore sustainable methodologies for wastewater treatment and reuse. The simultaneous presence of multiples contaminants in complex wastewater, such as the liquid effluents from biogas plants, can compromise biological treatment effectiveness for reclaiming water. Vertical subsurface flow constructed wetlands were established as low-cost decentralized wastewater treatment technologies to treat the liquid fraction of digestate from municipal organic waste with metals, antibiotics, and antibiotic resistance genes, to allow its reuse in irrigation. Twelve lab-scale planted constructed wetlands were assembled with gravel, light expanded clay aggregate and sand, testing four different treating conditions (liquid digestate spiked with oxytetracycline, sulfadiazine, or ofloxacin, at 100 μg/ L, or without dosing) during 3 months. Physicochemical parameters (pH, chemical oxygen demand (COD), nutrients, metals, and antibiotics), the microbial communities dynamics (through 16S high-throughput sequencing) and antibiotic resistance genes removal (qPCR) were monitored in influents and effluents. Systems removed 85.8%-96.9% of organic matter (as COD), over 98.1% of ammonium and phosphate ions, and 69.3%-99.4% of nitrate and nitrite ions, with no significant differences between the presence or absence of antibiotics. Removal of Fe, Mn, Zn, Cu, Pb and Cr exceeded 82% in all treatment cycles. The treatment also removed oxytetracycline, sulfadiazine and ofloxacin over 99%, and decreased intl1, tetA, tetW, sul1 and qnrS gene copies. Nonetheless, after 3 months of ofloxacin dosing, qnrS gene started being detected. Removal processes relied on high HRT (14 days) and various mechanisms including sorption, biodegradation, and precipitation. Microbial community diversity in liquid digestate changed significantly after treatment in constructed wetlands with a decrease in the initial Firmicutes dominance, but with no clear effect of antibiotics on the microbial community structure. Removals above 85% and 94% were observed for Streptococcus and Clostridium, respectively. Results suggest that vertical subsurface flow constructed wetlands were a suitable technology for treating the liquid digestate to reuse it in irrigation agricultural systems, contributing to the circular bioeconomy concept. However, a more profound understanding of effective wastewater treatment strategies is needed to avoid antibiotic resistance genes dissemination.

Zeolites and their composites as novel remediation agent for antibiotics: A review

Antibiotic residues in aquatic environments pose significant challenges when exceeding permissible limits. Zeolites, particularly aluminosilicate zeolites, have emerged as effective adsorption materials and solid substrates for semiconductor photocatalysts, facilitating the removal of antibiotics from wastewater. This review highlights the versatility of zeolites and their composites in antibiotic remediation, showcasing recent advancements in adsorption and photocatalytic degradation. Noteworthy examples include Fe (III)-modified synthetic zeolite 13X, exhibiting a maximum tetracycline adsorption capacity of approximately 200 mg/g, and MoS2@Zeolite achieving a remarkable efficiency of 396.70 mg/g for tetracycline removal. Additionally, zeolite-based photocatalysts like Fe-TiO2/BEA zeolite and exceptional CdS/CaFe2O4-clinoptilolite demonstrate high removal percentages, reaching 100% for tetracycline and 86% for cefazolin, respectively. The discussion encompasses an introduction to zeolites, including synthetic and natural zeolites, as well as techniques for modifying natural zeolites. It further delves into the production of synthetic zeolites as well as the fabrication of zeolite-based composite materials. These findings underscore the potential of zeolites and their composites as novel remediation agents for tackling antibiotic contamination in aquatic ecosystems, paving the way for sustainable wastewater treatment strategies. It highlights key elements, distinct qualities, and areas needing further research, paving the way for future studies.

Utilization of tofu wastewater and Nannochloropsis oceanica for eutrophication mitigation and eicosapentaenoic acid valorization: Advancing carbon neutrality and resource recycling

Seeking environmentally-friendly and resource-recycling strategies for tofu wastewater (TFW) treatment could effectively mitigate harsh ecological impacts and resource wastage caused by direct discharge. This study investigated the feasibility on the utilization of Nannochloropsis oceanica (N. oceanica) for TFW eutrophication mitigation and eicosapentaenoic acid valorization. The findings demonstrated that employing N. oceanica resulted in significant removal rates for total phosphorus, total nitrogen, ammonia nitrogen, and chemical oxygen demand by 88.60 %, 97.02 %, 94.22 %, and 98.02 % under fed-batch treatment mode. Such nutrients removal efficiency met discharge permit standards while accomplished a superior biomass at 26.37 g/L and EPA yield at 43.5 mg/g by N. oceanica, representing 2.61- and 2.52-fold more than that of batch treatment mode. Furthermore, TFW feeding enhanced the cytomembrane fluidity of N. oceanica and promoted TFW nutrients uptake into cells consequently boosted the nutrients removal efficiency. Simultaneously, TFW feeding upregulated enzymes such as antioxidases, desaturases and elongases responsible for EPA biosynthesis in N. oceanica to collectively protect EPA from oxidation stress and stimulate proactive accumulation. EPA derived from TFW-fed N. oceanica exhibited promising in vitro antihyperlipidaemia efficacy in constructed hyperlipopyte HepG-2 cells. Further, the molecular docking indicated that the hypolipidemic activity partly contributed to that EPA inhibited PPARα signaling to trigger fatty acids β-oxidation and cholesterol transport suppression. The outcomes present a viable route that utilization of microalgae for TFW eutrophication mitigation and EPA valorization to advance carbon neutrality and resource recycling.

Mechanistic study of novel ordered BiVO4/C/TiO2 S-heterojunctions with C layers as the electron transport pathways

Assembling the composition synergism and structure adjustment to efficiently accelerate the electron transfer and separation, is emerging as a promising strategy for advanced photocatalytic wastewater treatment. Henein, a novel ordered BiVO4/C/TiO2(BVCT) S-scheme heterojunction were successfully synthesized. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) show the composite of BiVO4 and C/TiO2, with the C layer as the contact surface. UV–vis diffuse reflectance spectra (UV–vis DRS) and X-ray photoelectron spectra (XPS) indicate that BVNT could follow S-scheme electron transfer. Electron paramagnetic resonance (EPR) shows that ·OH, ·OH, and h+ can all participate in photocatalytic reactions. Moreover, BVNT can degrade 91.2 % methylene blue (MB) within 40 min. This study provides new insights for the design of high-performance photocatalysts.

Sequential high-recovery nanofiltration and electrochemical degradation for the treatment of pharmaceutical wastewater

The presence of antibiotics in aquatic ecosystems poses a significant concern for public health and aquatic life, owing to their contribution to the proliferation of antibiotic-resistant bacteria. Effective wastewater treatment strategies are needed to ensure that discharges from pharmaceutical manufacturing facilities are adequately controlled. Here we propose the sequential use of nanofiltration (NF) for concentrating a real pharmaceutical effluent derived from azithromycin production, followed by electrochemical oxidation for thorough removal of pharmaceutical compounds. The NF membrane demonstrated its capability to concentrate wastewater at a high recovery value of 95 % and 99.7 ± 0.2 % rejection to azithromycin. The subsequent electrochemical oxidation process completely degraded azithromycin in the concentrate within 30 min and reduced total organic carbon by 95 % in 180 min. Such integrated treatment approach minimized the electrochemically-treated volume through a low-energy membrane approach and enhanced mass transfer towards the electrodes, therefore driving the process toward zero-liquid-discharge objectives. Overall, our integrated approach holds promises for cost-effective and sustainable removal of trace pharmaceutical compounds and other organics in pharmaceutical wastewater.

Efficient incorporation of highly migratory thallium into struvite structure: Unraveling the stabilization mechanisms from a mineralogical perspective

The remediation of high-concentration thallium (Tl+) contaminated wastewater is a critical environmental concern. Current research emphasizes the effectiveness of adsorption and oxidation methods for Tl+ treatment, yet challenges persist in enhancing their performance. This study explores the feasibility of emergency Tl+ wastewater treatment and elucidates the mechanisms of Tl+ incorporation into mineral structures, with a focus on the struvite mineral as a framework for Tl+ integration via NH4+ ion exchange. To assess the efficacy and mechanisms of Tl+ immobilization, we utilized comprehensive analytical techniques, including X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS), Thermogravimetric Analysis (TG), and Density Functional Theory (DFT) calculations. The findings reveal that struvite adsorbs Tl+ onto its surface, followed by an ion exchange process between monovalent cations (NH4+/K+) within the structure and Tl+. Ultimately, Tl+ is incorporated in the form of a (NH4,Tl)MgPO4 solid solution within the structure, achieving a remarkable maximum incorporation capacity of 320.56 mg/g, which significantly surpasses the capacity of typical adsorbents. The findings demonstrate significant Tl+ incorporation, validating the approach for emergency wastewater treatment and suggesting the potential of mineralogy in environmental remediation. This research contributes to advancing heavy metal wastewater treatment strategies, offering a foundation for further investigation.

Biopolymer Hydrogel-Based Salt-Resistant Evaporator for Solar-Energy-Driven Desalination and Water Purification.

Interfacial solar steam generation (ISSG) has recently received much attention as a low-carbon-footprint and high-energy-efficient strategy for seawater desalination and wastewater treatment. However, achieving the goals of a high evaporation rate, ecofriendliness, and high tolerance to salt ions in brine remains a bottleneck. Herein, a novel hydrogel-based evaporator for effective solar desalination was synthesized on the basis of sodium alginate (SA) and carboxymethyl chitosan (CMCS) incorporating a carbon nanotube (CNT)-wrapped melamine sponge (MS) through a simple dipping-drying-cross-linking process. The hydrogel-based evaporator reaches a high evaporation rate of 2.18 kg m-2 h-1 in 3.5 wt % brine under 1 sun irradiation. Furthermore, it demonstrated excellent salt ion rejection in high-concentration salt water. Simultaneously, it exhibits excellent purification functionality toward heavy metals and organic dyes. This study provides a simple and efficient strategy for seawater desalination and wastewater treatment.

A bio-based strategy for efficient industrial wastewater treatment using TiO2 photocatalysis

A bio-based strategy for efficient industrial wastewater treatment using TiO2 photocatalysis

Environmental stewardship in the oil and gas sector: Current practices and future directions

This paper provides an overview of the current practices and future directions in environmental stewardship within the oil and gas industry, focusing on key areas of concern and strategies for improvement. The oil and gas industry has made significant strides in environmental stewardship in recent years, driven by a combination of regulatory requirements, corporate initiatives, and stakeholder pressure. One of the primary areas of focus has been the reduction of greenhouse gas emissions associated with extraction, refining, and transportation processes. Companies have implemented technologies such as carbon capture and storage to minimize their carbon footprint, alongside investments in renewable energy sources and energy efficiency measures to transition towards cleaner energy alternatives. Furthermore, the industry has placed increasing emphasis on the responsible management of water resources, recognizing the potential environmental impacts of water extraction and usage in oil and gas operations. Strategies for water recycling, reuse, and wastewater treatment have been adopted to mitigate pollution and minimize strain on local ecosystems. Biodiversity conservation has also emerged as a critical aspect of environmental stewardship in the oil and gas sector, with companies undertaking environmental impact assessments and collaborating with conservation organizations to minimize habitat disruption and restore ecosystems affected by their operations. Community engagement and social responsibility are integral components of environmental stewardship, with companies seeking to address the social impacts of their operations through employment opportunities, infrastructure development, and social programs benefiting local communities. However, the industry continues to face challenges and limitations in its efforts to minimize environmental impact. Accidental spills, leaks, and other incidents pose significant ecological risks, highlighting the importance of stringent safety regulations and emergency response protocols. Moreover, the transition to renewable energy presents challenges for traditional oil and gas companies, requiring substantial capital investment and strategic planning. To address these challenges and advance environmental stewardship, several future directions are proposed. These include accelerating the transition to renewable energy, enhancing transparency and accountability in reporting environmental performance, strengthening environmental regulations and enforcement, investing in research and development of innovative technologies, and fostering collaboration among industry stakeholders, governments, NGOs, and local communities. Keywords: Stewardship, Oil, Gas, Sustainability, Climate, Mitigation

Promoted adsorption-photocatalysis synergistic removal of contaminants via surface regulation by a tree-like nanofiber membrane substrate

Photocatalysis represents a promising strategy for wastewater treatment, but the widely used powder photocatalysts are still limited by sluggish interfacial mass transfer and chemical processes. In this study, a tree-like PVDF nanofiber membrane (T-PVDF) was explored to enhance the photocatalytic activity of TiO2 and TiO2/BiOI heterojunction through different pathways. TiO2 was first integrated into the T-PVDF substrate via a one-step electrospinning method. The dendritic architecture greatly favored the contaminant adsorption on the catalytic surface and thus boosted the photodegradation of RhB under UV or visible light irradiation. Especially for the visible light driven dye-sensitive photocatalysis, the integrated TiO2@T-PVDF outperformed the powder TiO2 and pristine PVDF membrane anchored TiO2 by 17.9 and 2.4 times, respectively. In addition, the construction of TiO2/BiOI heterojunction on the T-PVDF substrate was realized by further growing BiOI nanosheets via a solvothermal method. The irregular growth of BiOI on the multiscale nanofiber substrate formed a rough surface with unexpected high hydrophobicity, which allowed the accumulation of high-concentrated O2 at the catalytic interfaces. This greatly boosted the O2 reduction and inhibited the competitive H2 evolution under visible light irradiation, resulting in 3.8-fold higher reaction kinetics than that obtained for hydrophilic powder TiO2/BiOI heterojunction.

Impact of CeO2 modified cathode and PANI modified anode on tannery wastewater fed microbial fuel cell performance

Microbial fuel cell (MFC) technology is getting acceptance as an emphatic, sustainable and energy efficient alternative of conventional wastewater treatment strategies. MFCs utilize exoelectrogens as biocatalysts to degrade the complex organic substances present in wastewater with simultaneous power generation. The present study was aimed at investigating the impact of MFC electrode’s modification with CeO2 nanoparticles and polyaniline (PANI) on its performance characteristics. The hydrothermal approach was employed for the synthesis of CeO2 nanoparticles followed by their deposition on carbon cloth (CC) as MFC cathode, whereas MFC’s anode i.e., CF/NF was modified by in-situe deposition of PANI. The synthesized material was characterized with FTIR, XRD, SEM, EDX and BET analysis. The experiments were performed using dual chambered MFC fed with leather tannery wastewater using modified and unmodified electrodes. The highest outcomes of power density and corresponding current density were observed with PANI@NF composite anode and CeO2@CC as cathode i.e., 279.3 mW/m2 corresponding to the current density of 581.8 mA/m2. The same MFC electrode configuration resulted in highest COD reduction, i.e., 80 % and coulombic efficiency of 19.86 %. On the other hand, MFC equipped with PANI@CF anode and CeO2@CC cathode also displayed comparable results. It was ascertained that modification of NF/CF anode with PANI (conductive polymer) and CC cathode with CeO2 nanoparticles have significantly improved the overall MFC operational performance regarding tannery wastewater treatment and bioelectricity generation.

Nonradical-dominated peroxymonosulfate activation by perylenetetracarboxylic acid nanosheet photocatalyst for efficient degradation of bisphenol a under visible-light irradiation

As a green, highly efficient, and sustainable technology, photocatalytic peroxymonosulfate (PMS) activation is a promising strategy for wastewater treatment. Moreover, the development of photocatalysts with excellent PMS activation performance is highly desirable for removing refractory organic contaminants from wastewater. Herein, perylenetetracarboxylic acid (PTA) nanosheets obtained using a facile method were explored as a highly efficient photocatalyst with a high PMS activation ability for bisphenol A (BPA) removal. Experimental results indicated that BPA can be removed within 16 min using PTA under optimal conditions. As confirmed through radical quenching, electron paramagnetic resonance spectroscopy, galvanic-oxidation-process experiments, and density functional theory calculations, photoinduced electrons and holes from PTA trigger PMS activation and thereby convert the reaction routes of BPA degradation from radical- to nonradical-dominated. The BPA degradation pathway was also studied using intermediate analysis and Fukui functions. Overall, the findings of this study shed light on organic semiconductor photocatalysts for nonradical-dominated PMS activation with regard to recalcitrant-organic-pollutant removal.

Molecular Simulation Studies of Pharmaceutical Pollutant Removal (Rosuvastatin and Simvastatin) Using Novel Modified-MOF Nanostructures (UIO-66, UIO-66/Chitosan, and UIO-66/Oxidized Chitosan).

The ubiquitous presence of pharmaceutical pollutants in the environment significantly threatens human health and aquatic ecosystems. Conventional wastewater treatment processes often fall short of effectively removing these emerging contaminants. Therefore, the development of high-performance adsorbents is crucial for environmental remediation. This research utilizes molecular simulation to explore the potential of novel modified metal-organic frameworks (MOFs) in pharmaceutical pollutant removal, paving the way for the design of efficient wastewater treatment strategies. Utilizing UIO-66, a robust MOF, as the base material, we developed UIO-66 functionalized with chitosan (CHI) and oxidized chitosan (OCHI). These modified MOFs' physical and chemical properties were first investigated through various characterization techniques. Subsequently, molecular dynamics simulation (MDS) and Monte Carlo simulation (MCS) were employed to elucidate the adsorption mechanisms of rosuvastatin (ROSU) and simvastatin (SIMV), two prevalent pharmaceutical pollutants, onto these nanostructures. MCS calculations demonstrated a significant enhancement in the adsorption energy by incorporating CHI and OCHI into UIO-66. This increased ROSU from -14,522 to -16,459 kcal/mol and SIMV from -17,652 to -21,207 kcal/mol. Moreover, MDS reveals ROSU rejection rates in neat UIO-66 to be at 40%, rising to 60 and 70% with CHI and OCHI. Accumulation rates increase from 4 Å in UIO-66 to 6 and 9 Å in UIO-CHI and UIO-OCHI. Concentration analysis shows SIMV rejection surges from 50 to 90%, with accumulation rates increasing from 6 to 11 Å with CHI and OCHI in UIO-66. Functionalizing UIO-66 with CHI and OCHI significantly enhanced the adsorption capacity and selectivity for ROSU and SIMV. Abundant hydroxyl and amino groups facilitated strong interactions, improving performance over that of unmodified UIO-66. Surface functionalization plays a vital role in customizing the MOFs for pharmaceutical pollutant removal. These insights guide next-gen adsorbent development, offering high efficiency and selectivity for wastewater treatment.

An attempt to augment performance of machine learning models in a pilot-scale urban wastewater treatment system

The challenge we face is striking a balance between ensuring the standards for wastewater treatment processes and minimizing energy consumption. As such, accurate predictive models become critical. With machine learning algorithms having the ability to discern relationships between inputs and outputs, broad interest has been shown in their applications in wastewater treatment. A key research focus is on effectively adjusting these generic machine learning algorithms to adapt to frequent fluctuations of water quality, inflow volume, and environmental variations. This study developed a Nonlinear Autoregressive neural network (NARX) model having an adaptive real-time updating module to predict the ammonium concentration in the treated effluent. The model has exhibited high predictive accuracy on the testing data, achieving an R2 value of 0.997. By incorporating an adaptive real-time updating module, the model's capability to predict effluent ammonium concentration on novel data sets has been significantly improved, with the R2 value for these predictions increasing from an initial 0.918 to a more refined range of 0.966 to 0.984. Our findings confirm that integrating real-time updating capabilities with machine learning algorithms substantially improves the stability and predictive performance of the models. These outcomes will prompt a broader integration of artificial intelligence in the domain of environmental engineering, which shall foster the implementation of more accurate and eco-friendly wastewater treatment strategies.

Intensify Mass Transfer and Molecular Oxygen Activation by Defect‐Bridged Asymmetric Catalytic Sites Toward Efficient Membrane‐Based Nanoconfined Catalysis

AbstractEfficient spontaneous molecular oxygen (O2) activation is expected in advanced oxidation processes. However, it remains a great challenge to promote the reactants adsorption and accelerate the interfacial electron transfer to boost the activation kinetic of O2. Herein, defect‐rich N‐doped reduced graphene oxide/CoFe2O4 (NGCF‐OV) membrane containing asymmetric Co‐OV‐Fe sites is prepared for O2 activation. The intrinsic catalytic activity is that the asymmetric Co‐OV‐Fe sites regulate the O─O bond length, promoting more and faster electron transfer to O2 for selectively producing 1O2. Meanwhile, the adjacent graphitic N sites help confine organics to the surface and thus greatly shorten the reaction distance of 1O2 and improve its utilization efficiency. The NGCF‐OV membrane demonstrates complete degradation of bisphenol A within a retention time of 86 ms, achieving a k‐value of 0.047 ms−1, which exceeds the performance of most Fenton‐like systems. This work provides new horizons for designing an efficient and stable catalytic membrane, enriching the domain of advanced wastewater treatment strategies.

Neodymium-doped nickel cobaltite reinforced with 2D MXene nanocomposite (Nd-NiCo2O4/MXene) for enhanced photocatalytic degradation of the organic pollutants

In the quest for sustainable strategies for environmental remediation and wastewater treatment, composite material-based visible light-responsive photocatalysis has emerged as a highly efficient method that is not only facile but also economical. Herein, we have synthesized pure (NiCo2O4) and Nd-doped (Nd-NiCo2O4) nickel cobaltite nanoparticles and incorporated doped material on 2D MXene to fabricate nanocomposite (Nd-NiCo2O4/MXene). The prepared samples were characterized to exploit the effect of Nd-doping and composite formation on structural, electrical, and optical properties. The photocatalytic potential of composite material was investigated by targeting malachite green and pendimethalin. In comparison to pure and doped materials, the nanocomposite demonstrated superior photocatalytic efficiency for the degradation of targeted pollutants. This enhanced catalytic activity is attributed to the synergism of rare earth metal doping and composite formation which result in enhanced absorption in visible light and lower coupling of charge carriers. Systematic studies revealed the promising potential of the Nd-NiCo2O4/MXene nanocomposite for solar light harvesting in wastewater remediation applications.

Enhanced biodegradation of phenol under Cr(VI) stress by microbial collaboration and potential application of machine learning for phenol biodegradation.

Cr(VI) and phenol commonly coexist in wastewater, posing a great threat to the environment and human health. However, it is still a challenge for microorganisms to degrade phenol under high Cr(VI) stress. In this study, the phenol-degrading strain Bacillus cereus ZWB3 was co-cultured with the Cr(VI)-reducing strain Bacillus licheniformis MZ-1 to enhance phenol biodegradation under Cr(Ⅵ) stress. Compared with phenol-degrading strain ZWB3, which has weak tolerance to Cr(Ⅵ), and Cr(Ⅵ)-reducing strain MZ-1, which has no phenol-degrading ability, the co-culture of two strains could significantly increase the degraded rate and capacity of phenol. In addition, the co-cultured strains exhibited phenol degradation ability over a wide pH range (7-10). The reduced content of intracellular proteins and polysaccharides produced by the co-cultured strains contributed to the enhancement of phenol degradation and Cr(Ⅵ) tolerance. The determination coefficients R2, RMSE, and MAPE showed that the BP-ANN model could predict the degradation of phenol under various conditions, which saved time and economic cost. The metabolic pathway of microbial degradation of phenol was deduced by metabolic analysis. This study provides a valuable strategy for wastewater treatment containing Cr(Ⅵ) and phenol.