Sustainable Remediation Research Articles

UiO-67 metal-organic framework loaded on hardwood biochar for sustainable management of environmental boron contaminations

Boron contamination in water poses significant potential risks to human health and the environment, necessitating the development of efficient, cost-effective, and sustainable remediation technologies. This study introduces a novel composite material combining a zirconium-based metal-organic framework (UiO-67) and a low-cost carbonaceous material (hardwood biochar, BC) with synergetic efficiency to address boron-polluted waters. The UiO-67-biochar (UBC) composite exhibits effective surface chemistry and a remarkably high specific surface area of approximately 881.9m²/g, substantially increasing from the 19.7m²/g of biochar. Our experimental results demonstrate that UBC removed up to 88.5% of boron from 20 ppm polluted water, achieving levels compliant with the WHO standards. The composite also showed excellent reusability, maintaining 95% efficiency over multiple cycles without loss of crystallinity. Life cycle assessment and cost analysis indicate that an optimal MOF to biochar ratio of approximately 60wt% minimises CO2 emissions and costs while maximising the boron removal efficiency. The UiO-67-biochar composites proposed here offers a promising scalable solution for boron contamination and potentially other environmental pollutants, combining the high functionality of UiO-67 with the practical and economic advantages of biochar.

A Comprehensive Study of the Degradation of Veterinary Antibiotics by Non-Thermal Plasma: Computational, Experimental, and Biotoxicity Assessments

Water quality is threatened by numerous pollutants, among which antibiotics are of great concern due to their widespread use and unaltered excretion, leading to water contamination and fostering antibiotic resistance. To comprehensively address sustainable water remediation, herein, the susceptibility to non-thermal plasma degradation of two veterinary antibiotics (Oxytetracycline (OTC) and Lincomycin (LNC)) are compared in an integral approach, including computational analyses, plasma irradiation assays, and a byproduct toxicity assessment. The computational assessment was performed by evaluating the ionization potential (IP) obtained from Density Functional Theory calculations and determining the antibiotics’ susceptible sites for radical attack. Plasma irradiation achieved nearly complete degradation (~100%) of both compounds with the initial concentration of 1 mg L−1, while 60% degradation was observed when the starting concentration was 10 mg L−1. The mineralization rates were 21% and 31% for OTC and LNC, respectively. The degradation profiles followed similar trends, as expected from their comparable IP values. After treatment, the solution exhibited lower biotoxicity compared to the original antibiotics. Therefore, this work represents a step forward in addressing one of the key environmental challenges of our time and encourages further extending the analysis towards the remediation of water polluted with many other organic compounds.

Exploring Sustainable Remediation Options: The Mycodegradation of Halogenated Nitroaromatic Compounds by Caldariomyces fumago

Chlorinated and fluorinated nitrophenols (HNCs) are widely used in agriculture and industry, with a global market valued at USD $25 billion, one which is expected to grow by 5% by 2030. However, these compounds pose significant environmental risks; they are classified as toxic by the International Agency for Research on Cancer (IARC). Existing treatment methods include advanced oxidation, adsorption, and bioremediation, though to date, there has been only limited research on fungal remediation of these halogenated pollutants. This study aims to explore a sustainable approach by using fungi’s potential to degrade HNCs in minimal media. Ten fungi were selected through literature screening; Caldariomyces fumago and Curvularia sp. were highly effective, degrading over 50% of 2-chloro-4-nitrophenol (2C4NP) and 80% of 5-fluoro-2-nitrophenol (5F2NP) within 24 and 48 h, respectively. Additionally, five strains showed degradation potential for fluorinated compounds. Further studies revealed C. fumago could degrade up to 1 mM of chlorinated compounds and 12 mM of fluorinated compounds, far exceeding any known environmental concentrations of HNCs; importantly, ecotoxicology tests demonstrated reductions in toxicity of 77% and 85%, respectively. This work highlights fungi’s underexplored ability to degrade toxic HNCs, offering a sustainable mycoremediation strategy and positioning mycology as a critical tool for future environmental remediation efforts.

Genome streamlining of Pseudomonas putida B6-2 for bioremediation.

Microbial transformation is a favored approach for environmental remediation. However, the effectiveness of microbial remediation has been limited by the lack of chassis cells with satisfactory contaminant degradation performance. Pseudomonas putida B6-2, with a wide substrate spectrum and high solvent tolerance, is a chassis strain with great potential for application in environmental remediation. Here, guided by bioinformatic analyses and genome-scale metabolic model (GEM) predictions, we successfully optimized P. putida B6-2 by rationally reducing its nonessential genetic components and generating a more robust genome-streamlined strain, P. putida BGR4. Several improvements were observed compared with the original P. putida B6-2 strain, including a 1.4 × 105-fold increase in electroporation efficiency, an 8.3-fold increase in conjugation efficiency, improved glycerol utilization capability, and increased phenol utilization after heterologous expression of the phenol monooxygenase encoded by dmpKLMNOP. Additionally, P. putida BGR4 exhibited enhanced tolerance to several stressors, including starvation, oxidative stress, and DNA damage. Transcriptomic analysis revealed that genome streamlining led to the upregulation of genes involved in the "carbon metabolism" and "tricarboxylic acid cycle" pathways in P. putida BGR4, which likely contributed to the superior phenotype of P. putida BGR4 in terms of carbon source utilization and contaminant degradation capabilities. Furthermore, the absence of four prophages was identified as a potential cause of the enhanced stress resistance observed in P. putida BGR4. Overall, we developed a combined genome-streamlining strategy involving bioinformatic analyses and GEM predictions and generated a more robust chassis strain, P. putida BGR4, which expands the repertoire of chassis cells for environmental remediation.IMPORTANCEDespite the development of many chassis cells, there is still a lack of robust chassis cells with satisfactory contaminant degradation performance. Targeted genome streamlining is an effective way to provide powerful chassis cells. However, genome streamlining does not always lead to the improved phenotypes of genome-streamlined chassis cells. In this research, a novel procedure that combined bioinformatic analyses and GEM predictions was proposed to guide genome streamlining and predict the effects of genome streamlining. This genome streamlining procedure was successfully applied to Pseudomonas putida B6-2, which was a chassis cell with great potential for application in environmental remediation and resulted in the generation of a more robust chassis cell, P. putida BGR4, thereby providing a superior chassis cell for efficient and sustainable environmental remediation and a valuable framework for guiding the genome streamlining of strains for other applications.

Green-Fueled synthesis of rGO/CuO for catalytic degradation of methyl violet dye

This study presents the green synthesis of copper oxide (CuO) through an eco-friendly solution combustion method, utilizing lemongrass as a natural fuel source. The rGO/CuO composite was prepared via a simple reflux process, emphasizing environmental sustainability. Comprehensive characterization of the synthesized CuO and rGO/CuO composites was conducted using techniques such as XRD, SEM, FTIR, PL, HR-TEM, EDX, and UV–Vis's spectroscopy. The photocatalytic efficiency of the rGO/CuO composite was tested for the degradation of Methyl Violet (MV) dye, achieving an impressive degradation rate of 98.87 ​% and following first-order kinetic behavior. The half-life (t₁/₂) of the reaction was calculated to be 18.17 ​min, with a rate constant (k) of 0.0398 ​min⁻1. Various parameters affecting photocatalytic performance, including pH, dye concentration, light source, and catalyst dosage, were systematically investigated. Scavenger experiments were conducted to determine the active species involved in the degradation process, and total organic carbon (TOC) removal was measured to assess mineralization efficiency. The catalyst's reusability was also evaluated, confirming its potential for long-term use in sustainable environmental remediation applications.

Sustainable remediation of piggery wastewater using a novel mixotrophic Chlorella sorokiniana Cbeo for high value biomass production

Piggery wastewater (PW) contains high density of organic carbon (COD), nitrogen (NH4+-N and TN) and phosphorous (TP), which are essential nutrients for microalgae growth. This work was attempted to use a newly isolate Chlorella sorokiniana Cbeo for recovery these compounds into its biomass via mixotrophic cultivation. Critical factors including level of ammonia, C/N ratio, pH, light intensity, sterilized/unsterilized media, and indoor/outdoor cultivations affecting biomass production and nutrients removal efficiencies were investigated. Data revealed that C. sorokiniana Cbeo achieved the optimal growth in the unsterilized medium at NH4+-N concentration, C/N ratio, initial pH, and light intensity of 250 mg/L, 10/1, 7, and 150 μmol/m2/s, respectively. Under the optimal conditions, dry cell weight (DCW) reached the maximal level of 4.30 g/L, which was slightly higher than 4.14 g/L determined for the sterilized medium. In 30 L-scale photobioreactor, C. sorokiniana Cbeo grown under indoor and outdoor achieved DCW of 3.61 and 3.19 g/L, respectively. COD, NH4+-N, TN, TP removal efficiencies for both conditions were determined as 91.9–96.7, 96.6–99.7, 96.2–96.4, and 98.2–100 %, respectively. The C. sorokiniana Cbeo biomass contained 14–27 % lipid, 25–32 % carbohydrate, 44–48 % protein, and 0.25–0.97 % lutein. Interestingly, α-Linolenic acid (C18:3n3) was 19.84 –27.0 % of the total fatty acids. C. sorokiniana Cbeo is the promising algal strain for development of a sustainable biorefinery of PW.

Scalable and sustainable remediation of OPD-contaminated aquifer via amphipathic multi-component covalent organic polymers

Scalable and sustainable remediation of OPD-contaminated aquifer via amphipathic multi-component covalent organic polymers

Advancing Sustainable Water Quality Monitoring and Remediation in Malaysia: Innovative Analytical Solutions for Detecting and Removing Emerging Contaminants

Advancing Sustainable Water Quality Monitoring and Remediation in Malaysia: Innovative Analytical Solutions for Detecting and Removing Emerging Contaminants

Sustainable Abiotic-Biotic Dechlorination of Perchloroethene with Sulfidated Nanoscale Zero-Valent Iron as Electron Donor Source.

Combining organohalide-respiring bacteria with nanoscale zero-valent iron (nZVI) represents a promising approach for remediating chloroethene-contaminated aquifers. However, limited information is available regarding their synergistic dechlorinating ability for chloroethenes when nZVI is sulfidated (S-nZVI) under the organic electron donor-limited conditions typically found in deep aquifers. Herein, we developed a combined system utilizing a mixed culture containing Dehalococcoides (Dhc) and S-nZVI particles, which achieved sustainable dechlorination with repeated rounds of spiking with 110 μM perchloroethene (PCE). The relative abundance of Dhc considerably increased from 5.2 to 91.5% after five rounds of spiking with PCE, as evidenced by 16S rRNA gene amplicon sequencing. S-nZVI corrosion generated hydrogen as an electron donor for Dhc and other volatile fatty acid (VFA)-producing bacteria. Electron balance analysis indicated that 68.1% of electrons from Fe0 consumed in S-nZVI were involved in dechlorination, and 6.2, 1.1, and 3.2% were stored in formate, acetate, and other VFAs, respectively. The produced acetate possibly served as a carbon source for Dhc. Metagenomic analysis revealed that Desulfovibrio, Syntrophomonas, Clostridium, and Mesotoga were likely involved in VFA production. These findings provide valuable insights into the synergistic mechanisms of biotic and abiotic dechlorination, with important implications for sustainable remediation of electron donor-limited aquifers contaminated by chloroethenes.

Mechanisms of roasting for improving rare earth element leaching from coal gangue

ABSTRACT Coal resources represent an important potential source for the future extraction of rare earth elements (REEs). This study, combining microscopic characterization techniques and experimental analysis, investigates the occurrence characteristics of REEs in coal gangue and the roasting activation mechanisms. The study reveals that phosphate minerals are the primary carriers of REEs, and sequential chemical extraction results further confirm the close association between REEs and phosphate minerals. Roasting at around 600°C facilitates the release of REEs from organic matter and clay minerals like kaolinite, significantly improving leaching efficiency. Under leaching conditions of 20 g/L, 50°C, 0.5 M HCl, and 1000 RPM, the leaching of REEs can reach approximately 80%. However, when the roasting temperature exceeds 1000°C, the formation of mullite leads to mineral surface sintering, reducing the recovery of REEs. This study emphasizes the importance of optimizing roasting conditions and understanding mineral phase changes to maximize REEs recovery, which is crucial for sustainable resource management and environmental remediation.

Multifunctional aluminum 12-hydroxystearate/lignin polyurethane foam for selective gelation and efficient separation of oil and organic solvents

During frequent transportation, the marine environment is continuously exposed to significant threats from crude oil and organic solvent leakage. Non-covalent self-assembly of organogelator on the adsorbent matrix to fix non-polar solvents is an efficient and sustainable remediation method. This contribution proposes an organogelator-adsorbent composite by blending aluminum 12-hydroxystearate (Al HSA) and expanded graphite (EG) during lignin-based polyurethane foaming. Al HSA molecule synergizes with EG to modulate the shape (hexagonal), oil retention, mechanical property, and hydrophobicity (water contact angle = 151.3°) of the lignin-based polyurethane foam (LPUF) skeleton. Al HSA-LPUF (OTS-LPUF/EAH) superhydrophobic foam exhibits sorption capacity up to 13.2–53.0 g g−1 in various oils and organic solvents. From the microscopic morphology, the Al HSA on the skeleton self-assembles into spherical nanoclusters driven by hydrogen bonding, realizing the capturing of oils and organic solvents. Even after 20 cycles, the foam still has a high oil/water separation capacity and mechanical performance. OTS-LPUF/EAH also shows improved flame retardancy and a 61 % reduction in total smoke release (TSR) compared to pristine LPUF.

Bismuth-based nanocomposites as potential materials for indoor air treatment

Air pollution is a worldwide health hazard; thus, improving air quality is a demanding need. Photocatalysis is a robust strategy for air treatment. The boosted activity of the photocatalytic system depends on tuning their properties for the particular application. BiOX (X: Cl, I) compounds are emergent photocatalytic systems with numerous advantages for air treatment. However, their optical properties (Eg) and fast recombination of active species (e−/h+) limit their practical applications. In this study, we remark on the properties of BiOX-GO systems for indoor air purification. We use a microwave-activated solvothermal technique to synthesize the nanomaterials (NMs). BiOX NMs exhibit hierarchical 3D structures, crystallinity, and tunable optical absorption properties. BiOX-GO composites present an enhanced visible-light photocatalytic activity due to the electron acceptor capacity of GO and modification of Eg. The indoor air disinfection capacity of the NMs ranked as follows: BiOCl-GO (96.7%) > BiOI-GO (96.2%) > BiOI (89.2%) > BiOCl (79%). The higher efficiency under visible light of BiOCl-GO can be related to the presence of oxygen vacancies, strong oxidation potential, and single crystalline phase of the materials. Due to the abundance and biocompatibility of bismuth-containing compounds, together with their enhanced visible light activity, BiOX become potent candidates for environmentally sustainable remediation technologies.

Adsorption Performance of Fe-Mn Polymer Nanocomposites for Arsenic Removal: Insights from Kinetic and Isotherm Models.

Global concern over arsenic contamination in drinking water necessitates innovative and sustainable remediation technologies. This study evaluates the adsorption performance of Fe-Mn binary oxide (FMBO) nanocomposites developed by coating polyethylene (PE) and polyethylene terephthalate (PET) with FMBO for the removal of As(III) and As(V) from water. Adsorption kinetics were rapid, with equilibrium achieved within 1-4 h depending on the material and pH. PET-FMBO and FMBO exhibited faster rates and higher arsenic removal (up to 96%) than PE-FMBO. Maximum As(III) adsorption capacities ranged from 4.76 to 5.75 mg/g for PE-FMBO, 7.2 to 12.0 mg/g for PET-FMBO, and up to 20.8 mg/g for FMBO, while capacities for As(V) ranged from 5.20 to 5.60 mg/g, 7.63 to 18.4 mg/g, and up to 46.2 mg/g, respectively. The results of the Dubinin-Radushkevich isotherm model, with free energy (Ea) values exceeding 16 kJ/mol, suggest chemisorption is the dominant mechanism, which is supported by the kinetics data. Given the effective removal of As(III), chemisorption likely proceeds through ligand exchange during the Mn oxide-mediated oxidation of As(III) and complexation with hydroxyl groups on the nanocomposite. These findings highlight the strong potential of Fe-Mn polymer nanocomposites, particularly PET-FMBO, for efficient arsenic removal during practical water treatment applications.

Unraveling the synergistic interplay of sulfur and wheat straw in heterotrophic-autotrophic denitrification for sustainable groundwater nitrate remediation

Nitrate pollution in groundwater is a global environmental issue that poses significant threats to human health and ecological security. This study focuses on elucidating the mechanisms of heterotrophic-autotrophic cooperative denitrification (HAD) by employing wheat straw and elemental sulfur as electron donors in varying proportions. The research initially underscores that heterotrophic denitrification (HD) accelerates the denitrification process due to its high-energy metabolism. However, as readily degradable organic matter diminished, reliance on more complex substrates such as lignocellulose posed a challenge to HD. This marks a pivotal transition towards autotrophic denitrification (AD), which, despite a slower initial rate, exhibits a more sustained denitrification performance. A low proportion of heterotrophic denitrification layer (e.g., 3:1) at the bottom facilitating efficient and sustainable denitrification. HD is capable of simultaneous removal of nitrates and nitrites, whereas AD demonstrates a higher affinity for nitrates, with nitrite accumulation reaching 100% at high influent nitrate concentrations (100 mg/L). HD not only provides the necessary alkaline environment for AD but also reduces sulfate production, whereas AD utilizes the residual organic carbon and ammonia produced by HD. The heterotrophic layer is characterized by a diverse community, whereas the autotrophic layer is predominantly composed of Thiobacillus. By delineating the interactive mechanisms and characteristics of HAD, this study highlights the importance of balancing heterotrophic and autotrophic activities for the effective remediation of groundwater nitrates.

Effects of simulated low-temperature thermal remediation on the microbial community of a tropical creosote contaminated soil.

In the search for more sustainable remediation strategies for PAH-contaminated soils, an integrated application of thermal remediation and bioremediation (TEB) may allow the use of less impacting temperatures by associating heating to biological degradation. However, the influence of heating on soil microbiota remains poorly understood, especially in soils from tropical regions. This work investigated the effects of low-temperature heating on creosote-contaminated soil bacteria. We used culture-dependent and 16S rRNA sequencing methods to compare the microbial community of soil samples heated to 60 and 100 oC for 1h in microcosms. Heating to 60°C reduced the density of cultivable heterotrophic bacteria compared to control soil (p < 0.05), and exposure to 100°C inactivated the viable heterotrophic community. Burkholderia-Caballeronia-Paraburkholderia (BCP) group and Sphingobium were the predominant genera. Temperature and incubation time affected the Bray-Curtis dissimilarity index (p < 0.05). At 60°C and 30 days incubation, the relative abundance of Sphingobium decreased and BCP increased dominance. The network of heated soil after 30 days of incubation showed fewer nodes and edges but maintained its density and complexity. Both main genera are associated with PAH degradation, suggesting functional redundancy and a likely potential of soil microbiota to maintain biodegradation ability after exposure to higher temperatures. We concluded that TEB can be considered as a potential strategy to bioremediate creosote-contaminated soils, allowing biodegradation in temperature ranges where thermal remediation does not completely remove contaminants. However, we recommend further research to determine degradation rates with this technology.

Mitigation of microplastic toxicity in soybean by synthetic bacterial community and arbuscular mycorrhizal fungi interaction: Altering carbohydrate metabolism, hormonal transduction, and genes associated with lipid and protein metabolism

Microplastics (MPs) have become ubiquitous environmental pollutants, eliciting concerns about their negative impacts on terrestrial and agroecosystems. However, employing sustainable remediation approaches holds the potential to mitigate these negative impacts and bolster MPs tolerance in both the seeds and vegetative structures of plants. The current investigation explores the impact of arbuscular mycorrhizal fungi (AMF) and synthetic bacterial community (SynCom) as potential alleviators of MP-induced stress. Results exhibited that co-applied SynCom and AMF, resulted in the highest plant biomass, leaf area, pod per plant, and 100-seed weight under control (no MPs) and MPs stress. The combined application of SynCom and AMF enhanced colonization, association, and arbuscule abundance in the non-stressed plants (no MPs) as compared to stressed plants. The sole or co-application of SynCom and AMF enhanced the primary metabolites content and mitigated the MPs-induced reduction in soluble sugars, lipids, protein, and oil contents. Soybean inoculation stimulated the genes expression involved in lipid and protein biosynthesis, while a contradictory drift was noted for genes associated with lipid and protein degradation, underpinning the observed increment in protein and lipid content. Soybean inoculated with AMF exhibited the utmost α-amylase and β-amylase activities, demonstrating enhanced osmolyte (soluble sugar) production, mainly under MPs stress. Remarkably, sole or co-application further reinforces the positive effect of MPs stress on the osmoprotectants and antioxidant levels, for instance, phenol, flavonoid, glycine betaine contents, and glutathione-S-transferase (GST) activities. Subsequent to the stress release, a stress hormones known as abscisic acid (ABA) reduced in the seeds of inoculated soybean while gibberellin (GA), trans-zeatin riboside (ZR), and indole acetic acid (IAA) were increased. Therefore, it is concluded that the combined application of SynCom and AMF protected the soybean plants from MPs-induced oxidative damage by upregulating osmoprotectants and antioxidant levels. This study provides insights into the potential of sustainable remediation approaches in alleviating the complex impact of MPs on soybean, contributing to future strategies for environmental sustainability. Future studies could explore the optimization of SynCom and AMF formulations for different crops and environmental conditions, potentially leading to practical applications in sustainable agriculture and pollution management.

Sustainable remediation of nickel (II) in aqueous solutions using waste orange peel biomass as a bioadsorbent

Sustainable remediation of nickel (II) in aqueous solutions using waste orange peel biomass as a bioadsorbent

Iron-modified biochars and their aging reduce soil cadmium mobility and inhibit rice cadmium uptake by promoting soil iron redox cycling

Iron (Fe) modified biochar has been widely used for cadmium (Cd) contaminated soil remediation. However, the accompanying anions introduced during the modification process potentially affect the behavior of Cd in soil. In this study, we investigated the distinct Cd immobilization mechanisms by Fe2(SO4)3 modified biochar (FSBC) and Fe(NO3)3 modified biochar (FNBC) in a two-year pot experiment. Results showed that both FSBC and FNBC significantly reduced Cd concentrations in rice grains by 23%–42% and 30%–37% compared to pristine biochar (BC). Specifically, NFBC promoted the formation of amorphous Fe oxides by enhancing the NO3−-reducing Fe(II) oxidation process, which significantly increased Fe/Mn oxide-bound Cd and decreased soil CaCl2-extractable Cd. For FSBC, the introduction of SO42− significantly promoted the formation of Fe plaques by enhancing the Fe(III) reduction process, which blocked the Cd transfer from the soil to the rice roots. More importantly, after two years of biochar application, an organo-mineral complex layer is formed on the biochar surface, which immobilized a large amount of Cd. The Cd immobilization on the surface of aged biochar could be due to the fixation by the secondary Fe oxides within the organo-mineral layer and the complexation by the surface functional groups. The result of laser ablation inductively coupled plasma mass spectrometry showed that the Cd content on aged FNBC and FSBC was 5.9 and 2.6 times higher than on aged BC. This might be attributed to the Fe-modified biochar's higher electron exchange capability (EEC), which promoted the development of organo-mineral complexes. Notably, the EEC of biochar was maintained during its aging process, which may keep the biochar surface active and facilitate continual Cd immobilization. This study revealed the complex mechanisms of soil Cd immobilization with Fe-modified biochar, providing new insights into sustainable biochar environmental remediation.

Simplified efficiency calibration methods for scintillation detectors used in nuclear remediation

Our study introduces innovative methods to address waste reduction and enhance resource efficiency in nuclear cleanup processes. We focus on sustainable nuclear technology, aligning with goals for cleaner production and environmental protection. We developed two novel methods, termed “oversimplified” and “simplified,” for easily determining the photopeak efficiency of NaI(Tl) scintillation detectors. These methods, along with a “general” solution method, were validated with calibrated radioactive sources such as 241Am, 57Co, 133Ba, 137Cs, and 60Co, and were used to commission a NaI(Tl) scintillation detector system at Chalk River Laboratories (CRL) for nuclear remediation. The system demonstrated high accuracy, making it suitable for screening unstable isotopes at contaminated sites. This screening tool significantly reduces the number of soil samples requiring detailed characterization, thereby lowering operational costs. The NaI(Tl) detector system was calibrated for near-contact geometry, which is commonly used at CRLs. Detection limits were established for this configuration. By improving the efficiency calibration of scintillation detectors, our study advances sustainable nuclear remediation practices, promoting environmental sustainability and cleaner production processes.

Self-Reconstruction Induced Electronic Metal-Support Interaction for Modulated Cu+ Sites on TiO2 Nanofibers in Electrocatalytic Nitrate Conversion.

The Cu+ active sites have gained great attention in electrochemical nitrate reduction, offering a highly promising method for nitrate removal from water bodies. However, challenges arise from the instability of the Cu+ state and microscopic structure over prolonged operation, limiting the selectivity and durability of Cu+-based electrodes. Herein, a self-reconstructed Cu2O/TiO2 nanofibers (Cu2O/TiO2 NFs) catalyst, demonstrating exceptional stability over 50 cycles (12 h per cycle), a high NO3 --N removal rate of 90.2%, and N2 selectivity of 98.7% is reported. The in situ electrochemical reduction contributes to the self-reconstruction of Cu2O/TiO2 nanofibers with stabilized Cu+ sites via the electronic metal-support interaction between TiO2 substrates, as evidenced by in situ characterizations and theoretical simulations. Additionally, density functional theory (DFT) calculations also indicate that the well-retained Cu+ sites enhance catalytic capability by inhibiting the hydrogen evolution reaction and optimizing the binding energy of *NO on the Cu2O/TiO2 NFs heterostructure surface. This work proposes an effective strategy for preserving low-valence-state Cu-based catalysts with high intrinsic activity for nitrate reduction reaction (NO3RR), thereby advancing the prospects for sustainable nitrate remediation technologies.