Search Results (811)

The intensifying rate of global water stress is motivating the exploration of alternative water sources. This research aims to unlock conventionally unusable wastewater effluent for reuse with the aid of slow sand filtration (SSF). In this study, a traditional SSF reactor was constructed and later modified by replacing a section with sawdust, a sustainable material. The two filter configurations were asynchronously investigated to evaluate their potential capacity for the removal of antibiotics and common surface-water nutrients, i.e., nitrates and phosphates. Each filtration system was operated in a recirculating mode over four weeks to develop the biological component referred to as the “schmutzdecke”. Standard water-quality testing indicated that the SSF with an incorporated sawdust layer buffered shock events (e.g., turbidity spikes) while still cultivating a healthy schmutzdecke. Furthermore, the sawdust facilitated greater microbial activity, which is associated with the biodegradation of various contaminants and pathogens. Following filtration of a simulated wastewater effluent containing sulfamethoxazole (SMX) and trimethoprim (TMP) antibiotics (ca. 1 mg∙L⁻¹), it was found that the TMP removal exceeded 93% in both configurations. The SMX removal rate was much lower and varied significantly, ranging from 1.2 to 38.6% and from 1.4 to 3.4% for the traditional and modified filters, respectively. These findings suggest that the proposed configuration has the potential to address some emerging contaminants but that refinements are needed to address other contaminants such as SMX. Full article

With the widespread application of new chemicals, the concentration of emerging contaminants (ECs), such as antibiotics, per- and polyfluoroalkyl substances (PFAS), microplastics, and new pesticides, in aquatic environments is on the rise. ECs such as those examined in the studies exhibit high toxicity, persistence, and a propensity for bioaccumulation, which can lead to significant risks for ecosystems and human health. Traditional water treatment technologies exhibit limited removal capabilities for ECs, whereas micro-nano bubbles (MNBs) exhibit great potential in the field of ECs treatment, due to their unique physicochemical properties. This article systematically reviews the research progress on the treatment of ECs using MNBs combined with other technologies, including physical methods (adsorption enhancement), chemical methods (ozonation, persulfate oxidation, photocatalysis, and material catalysis) and biological methods (microbial synergy). This review summarizes the research progress and mechanisms of MNBs combination technologies, outlining the critical knowledge gaps and future research perspectives to advance the rational design and engineering application of MNBs for ECs’ elimination in water treatment. Full article

Microbiological contamination of surface water represents a critical public health concern, while conventional disinfectants face limitations such as the generation of toxic by-products and the emergence of microbial resistance. In this study, the application of an ethanolic peel extract of Citrus paradisi (grapefruit), obtained by sonication at 40 kHz for 90 min at 55 °C using a 1:4 (w/v) solvent-to-solid ratio, was evaluated as a natural alternative for bacterial reduction in contaminated waters. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the extract were first determined against Staphylococcus aureus and Escherichia coli. The extract was then applied to samples of slightly contaminated surface water with bacterial loads between 10³–10⁴ CFU/mL and turbidity of 150 NTU, as well as to highly contaminated surface water with bacterial loads ≥10⁵ CFU/mL and turbidity of 250 NTU. Bacterial removal was assessed at 6, 12, and 24 h. FTIR and UV-Vis characterization of the extract confirmed the presence of flavonoids (naringin), terpenes (limonene), and phenolic compounds. Results showed MIC/MBC values of 2.5/5.0 mg/mL for S. aureus and 5.0/10.0 mg/mL for E. coli. In slightly contaminated water, the extract at 5.0 mg/mL achieved complete (100%) removal of both microorganisms after 12 h, whereas in highly contaminated water, removals ranged from 80–90% for Staphylococcus spp. and E. coli. Statistical analysis (ANOVA, Bonferroni) demonstrated significant differences (p < 0.05) between the extract and ethanol. These findings indicate that Citrus paradisi extract constitutes an effective, sustainable, and low-cost natural alternative for bacterial reduction in surface waters, contributing to the valorization of agro-industrial residues and to the achievement of Sustainable Development Goal (SDG) 6. Full article

The growing demand for safe and minimally processed fresh fruits and vegetables has highlighted the need for effective and environmentally friendly decontamination methods. Conventional washing techniques often fail to remove pesticide residues and microbial contaminants efficiently, while chemical disinfectants raise concerns related to toxicity and sustainability. In this context, natural surfactants and fermentation-derived solutions have emerged as promising alternatives. This critical review presents aspects regarding recent advances in the use of plant-based and microbial surfactants, for the decontamination of fresh products, with highlights on their mechanisms of action, ranging from enhanced removal of hydrophobic residues to disruption of microbial bio-films. Also, particular attention is given to the potential of combining surfactants with bioactive compounds obtained through fermentation processes, as well as to the valorization of agro-industrial waste as sustainable raw materials. The impact of these treatments will contribute to the improvement of product quality, safety, and environmental compatibility. Finally, current challenges related to scalability, standardization, and regulatory aspects are outlined, highlighting the need for further research to support the transition from laboratory studies to real-world applications. Full article

The removal of recalcitrant industrial dyes from wastewater has emerged as a critical environmental challenge, particularly in the context of the accelerating decline of global freshwater reserves. Given that these contaminants originate predominantly from the effluents of textile, chemical, and related manufacturing sectors, the deployment of advanced treatment technologies prior to discharge is imperative to mitigate their ecological impact. This study investigates the photocatalytic degradation of indigo carmine using a synthesized MgAl–LDH material. LDH is shown to act as an active photocatalytic component rather than a support, with its remarkably simple synthesis offering a practical alternative to the complex catalysts dominating the current literature. The catalyst’s structural, morphological, and surface characteristics were comprehensively validated through XRD, SEM, EDX, and BET analyses. The catalyst was evaluated under varying hydrogen peroxide doses and across an initial dye concentration range of 5 × 10⁻⁵ to 5 × 10⁻⁴ M. Increasing the H₂O₂ volume (3.5–20 mL, corresponding to H₂O₂ excess ratios of 17.5–100) significantly enhanced the oxidation rate, whereas higher dye concentrations reduced efficiency due to photon competition and partial saturation of catalytic sites. These experiments provided the basis for extracting kinetic parameters and assessing the mechanistic pathways governing the photocatalytic process. The kinetic behavior of indigo carmine degradation was evaluated by fitting the experimental data to zero-order, first-order, and second-order empirical models to identify the rate law that best describes the reaction. Reusability tests showed that MgAl–LDH maintains high activity over multiple cycles, with only a moderate decline, demonstrating its stability and suitability for practical wastewater treatment applications. Full article

The extensive use of plastics in everyday life has exerted a significant influence on the environment, with the release of micro- and nanoplastics posing even greater ecological threats. Plastic contamination, particularly in these smaller forms, has emerged as a pressing environmental concern due to its persistence, bioaccumulation, and potential hazards. Traditional treatment systems are generally ineffective at removing such micro- and nano-scale complex pollutants. Recently, micro- and nanofiber-based materials have emerged as promising candidates due to their large surface area, porous structure, and adjustable functionality, enabling efficient adsorption, filtration, and photocatalytic degradation. The term micro/nanofibers in this study encompasses both electrospun nanofibrous membranes and nanofiber-based functional layers or additives incorporated into pre-existing membrane structures for performance enhancement. The incorporation of photocatalysts enables these materials to promote photocatalytic oxidation, degrading plastics into smaller, less toxic compounds. This paper outlines recent progress in developing micro- and nanofiber systems for environmental remediation, highlighting their design approaches, removal mechanisms, and multifunctional capabilities. Ultimately, the discussion explores emerging directions, existing limitations, and future opportunities, highlighting how these advanced materials can contribute to sustainable and efficient pollution control strategies. Full article

Optimizing industrial wastewater treatment systems requires efficient, cost-effective, and easily adaptable technologies. In this context, adsorption emerges as a promising alternative through the use of advanced nanostructured materials that optimize contaminant removal and facilitate their separation from the treated medium. This work evaluates the use of nanoporous anodic aluminum oxide (AAO) as a nanoadsorbent for the removal of Eriochrome Black T (EBT) dye, analyzing the effect of thermal and chemical modifications on its performance. The results demonstrated that calcination and chemical etching with NaOH, applied individually, increased removal efficiency by 10% compared to untreated AAO. Notably, the combined treatment (calcination + alkaline etching) boosted removal efficiency by 38% after 1 h of contact. Furthermore, this synergistic modification extended the viability of the process to alkaline media (up to pH 10) and allowed the material to be reused for four consecutive cycles, maintaining an 85% removal rate. Finally, the kinetic analysis elucidated the influence of the structural and chemical modifications on the adsorption rate, obtaining satisfactory correlations with various theoretical models. Full article

Perfluorobutane sulfonamide (FBSA), an emerging short-chain perfluorooctanesulfonate (PFOS) alternative used in semiconductor manufacturing and fire suppression, has been detected in environmental matrices and poses environmental risks via industrial emissions and product leaching. However, the microbial degradation characteristics of FBSA are still unclear. In this study, two FBSA-transforming bacterial strains (designated LH-1 and BO-1) were isolated from the contaminated sediments of the Liaohe Estuary and the Bohai Sea, northeastern China. Based on 16S rDNA gene sequence analysis, strain LH-1 showed 99.66% sequence similarity with Neobacillus cucumis C7-N-8-8, while strain BO-1 showed 100% similarity with Glutamicibacter nicotianae OTC-16. Genomic analysis identified key degradation-related genes, including oxidoreductases, hydrolases, and genes involved in chloroalkane (LH-1) or fluorobenzoate (BO-1) degradation pathways, providing genetic evidence that supported their FBSA biotransformation potential. After 5 days of incubation with 133.8 nmol/mL FBSA, LH-1 and BO-1 removed 8.78% and 11.37% of FBSA, respectively. Perfluorobutanesulfonic acid (PFBS), perfluorobutanoic acid (PFBA), and perfluoropropionic acid (PFPrA) were detected as biodegradation products, with PFBS and PFPrA as the main products in strains LH-1 and BO-1, respectively. Genome annotation revealed candidate genes associated with deamination, oxidation, desulfonation, decarboxylation, and defluorination, as well as strain-specific enrichment of chloroalkane degradation genes in LH-1 and fluorobenzoate degradation genes in BO-1. Neither strain showed detectable degradation of perfluorooctanoic acid (PFOA) or PFOS, suggesting an apparent preference for the sulfonamide precursor FBSA over terminal perfluoroalkyl acids (PFAAs). This study provides the first genomic and metabolic insights into FBSA biotransformation by coastal sediment bacteria and improves our understanding of the environmental fate of sulfonamide-based PFAS precursors. Full article

Chlorinated benzoquinones such as 2,6-dichlorobenzoquinone (DCBQ) are toxic disinfection by-products that may persist in treated waters, requiring post-treatment strategies. In this study, the photo-Fenton process was evaluated for DCBQ degradation, with a focus on the influence of pH on kinetics, oxidation behavior, and water quality evolution. Experiments were conducted using 50.0 mg/L DCBQ, 1.0 mg/L Fe²⁺, and 2.0 mM H₂O₂ under UV irradiation (150 W) within a pH range of 3.0–12.0. Degradation followed apparent second-order kinetics, with maximum rates at acidic pH. At initial pH 3.0–5.0, rapid pollutant removal was accompanied by efficient aromaticity (UV₂₅₄) and color elimination, intense dissolved oxygen consumption, transient turbidity peaks due to intermediate formation, and increases in total dissolved solids, indicating extensive oxidation and a high degree of organic matter transformation, as inferred from indirect physicochemical indicators. At near-neutral pH, oxidation was slower, with delayed aromatic and chromophoric decay and moderate accumulation of intermediates. Mildly alkaline conditions exhibited limited radical activity, stable turbidity, and reduced mineralization. Under strongly alkaline conditions, oxidation was largely inhibited, with persistent aromaticity and negligible oxygen consumption. These findings highlight the importance of integrating advanced oxidation processes with adsorption-based systems for efficient and sustainable water treatment of emerging contaminants. Full article

Microbial fuel cells (MFCs) are emerging as biomimetic bioelectrochemical systems that emulate naturally occurring microbial electron-transfer pathways for stimulus bioenergy generation and wastewater remediation. In this study, food–vegetable leachate (FVL) and sugarcane bagasse-derived biol were evaluated in combination with carbon fiber (CF) and biochar-modified carbon fiber (BCF) electrodes used as membrane components in MFCs. Four configurations, in duplicate, were constructed by coupling two substrates (biol or FVL) with two membrane types (CF and BCF). All systems exhibited progressive anodic acidification and up to a 55% increase in electrical conductivity. The highest voltage output was achieved in MFC-BL-2 (404.59 mV), followed by MFC-FL-1, driven by synergistic interactions between the substrate and biochar-enhanced conductive networks. MFC-FL-1 also demonstrated superior contaminant removal performance, achieving 60% COD reduction, 36% BOD reduction, and 50% NH₄⁺–N removal. SEM–EDS analysis confirmed that biochar-modified electrodes developed a porous structure and substantially enhanced microbial adhesion. FVL-fed systems formed dispersed electroactive biofilms that facilitated electron transfer, whereas biol-fed systems developed compact biofilms that constrained electron flux. By integrating waste-derived lignocellulosic materials with electroactive microbial consortia, this work advances a biomimetic circular bioengineering platform for sustainable bioelectrochemical recovery and wastewater remediation. Full article

Advanced oxidation processes using titanium dioxide (TiO₂) have emerged as a promising approach for the photocatalytic degradation of contaminants in water and have drawn extensive research attention despite limited translation of this technology to large-scale applications. The limitations of this technology include immobilization of the photocatalyst, scalability, and compatibility with available light sources. Using 3D printing to immobilize TiO₂-based photocatalysts, we systematically evaluated the rates of photocatalytic degradation of methylene blue (MB) with different light-emitting diode (LED) ultraviolet (UV) light sources and modified TiO₂-based photocatalytic materials. The UV LED lights successfully decreased the MB concentrations with half-lives ranging from 0.9 to 2.4 h, with relative photocatalytic performance of UVA-365 > UVA-395 > UVC-280. The photocatalytic degradation rates under UV LEDs were slower (0.9–2.4 h) than those achieved using a low-pressure mercury UV-C lamp (0.5 h) and were also lower than those observed under solar simulated lights (0.6 h). The TiO₂ modified by an alkyl silane entity and embedded in a polylactic acid polymeric system with 3D printing exhibited the fastest methylene blue (MB) removal among the three TiO₂-based structures evaluated, with a half-life of 0.6 h compared to the 1.6–17.7 h for the other materials. This research demonstrated that 3D printing enables the integration of functionalized photocatalysts, and, when paired with low-cost, low-energy UV LED lights, can achieve environmentally relevant rates of performance. Ultimately, these findings represent an incremental step toward improving the performance of 3D-printed photocatalytic materials. Full article

Aquatic ecosystems are under severe stress from a diverse combination of contaminants, including heavy metals, pesticides, pharmaceuticals, and microplastics, driven by rapid industrialization, intensive agriculture, and urbanization. Globally, 80% of wastewater remains untreated, and conventional systems often fail to address emerging contaminants. Consequently, toxic heavy metals like lead and mercury can persist in water sources for decades. In response, phytoremediation has emerged as a scalable, eco-friendly, nature-based alternative. Among phytoremediation agents, duckweeds are increasingly recognized for their rapid growth, simple morphology, and continuous water-column contact. This review outlines the landscape of duckweed-based remediation, detailing molecular detoxification pathways and the synergistic role of associated microbiomes in enhancing environmental cleanup. Evidence indicates that contaminant removal is often supported by plant-microbe interactions. Despite extensive laboratory validation, field-scale implementation remains constrained by environmental complexity, pollutant mixtures, and variable climatic conditions. Furthermore, while duckweed systems hold promise within circular bioeconomy frameworks, converting wastewater into nutrient-rich biomass, contaminant accumulation in plant tissues raises concerns about biomass utilization and contaminant carryover. Addressing these challenges requires an integrative approach that links molecular detoxification, ecological interactions, and engineered system design to realize the full potential of duckweeds for sustainable aquatic pollution management. Full article

The transition to a circular economy requires the safe management of sewage sludge through nutrient and energy recovery. However, pharmaceuticals and personal care products (PPCPs) present a significant challenge. These compounds tend to accumulate in sludge via sorption, shifting the environmental burden from the aqueous phase to the sludge. This manuscript provides a comprehensive review of the scientific literature on technical alternatives for valorizing sewage sludge and removing emerging contaminants. The study evaluates the limitations of conventional biological methods, such as anaerobic digestion and composting, which exhibit variable efficacy and are often insufficient to degrade some commonly used pharmaceuticals. On the contrary, thermal treatments (pyrolysis, gasification, and hydrothermal processes) are considered robust alternatives capable of achieving the high removal of chemical compounds. Furthermore, the article emphasizes the innovative potential of utilizing carbon-based byproducts (biochar and hydrochar) as adsorbents, catalysts, or soil amendment to enhance the removal of PPCPs within the treatment infrastructure itself. The integration of advanced thermal technologies is essential to mitigate the risks of contaminant transfer to the food chain and ensure a safe and sustainable nutrient cycle. Full article

Per- and polyfluoroalkyl substances (PFASs) are persistent emerging contaminants characterized by high environmental stability and biotoxicity. Ubiquitous detection of these contaminants across aquatic environments poses severe threats to ecosystem stability and human health, while constructed wetlands (CWs) serve as a sustainable low-carbon alternative for the remediation of PFAS-laden wastewater. However, traditional mechanisms such as matrix adsorption, phytoaccumulation, and microbial transformation often suffer from low efficiency, rapid saturation, and incomplete degradation. To overcome the above drawbacks, the arbuscular mycorrhizal fungi (AMF)–plant–microbe synergistic consortium has become a promising remediation candidate, which facilitates PFAS immobilization and biodegradation via symbiotic crosstalk among three components. This paper reviews recent advancements in PFAS remediation within AMF-facilitated systems, examining fundamental synergistic mechanisms, treatment efficiencies, and key influencing factors. We propose several optimization strategies, including substrate modification, operational parameter refinement, and the integration of advanced technologies. Furthermore, we emphasize the necessity of elucidating the molecular pathways governing long-chain PFAS degradation and addressing current bottlenecks in engineering applications. Future research should prioritize molecular interaction level interaction mechanisms, the development of anti-interference systems, and field-scale validation. This review provides a theoretical foundation and technical framework for leveraging AMF–plant–microbe synergism to enhance PFAS removal in CWs. Full article

The management of livestock manure is associated with substantial ammonia (NH₃) emissions and the accumulation of emerging contaminants, including antibiotics, antibiotic resistance genes (ARGs), and microplastics, posing risks to environmental quality and public health. Biochar has emerged as a promising strategy for mitigating gaseous emissions and reducing contaminant mobility during manure storage and composting processes. This review synthesizes recent research on the application of biochar in livestock manure management systems, focusing on NH₃ emissions, antibiotic degradation, ARG reduction, and microplastic removal. Particular attention is given to the effectiveness of biochar in mitigating pollutants during manure storage, housing operations, and composting processes. Across the literature, reported NH₃ mitigation efficiencies vary widely, from negligible effects to reductions exceeding 90–97%, depending on feedstock type, pyrolysis conditions, particle size, and application strategy. Biochar also promotes antibiotic degradation and ARG mitigation, with reductions of up to 98% reported in composting systems. Emerging evidence further suggests that biochar can reduce microplastics by approximately 15–64% in sludge composting. Plant-derived and chemically modified biochars generally outperform manure-derived biochars due to higher surface area, cation exchange capacity, and greater abundance of functional groups. The review highlights that activation treatments, co-composting strategies, and microbial interactions are key factors controlling pollutant mitigation efficiency. Despite promising outcomes, large-scale application remains limited by economic constraints, variability in biochar properties, and the lack of long-term field-scale validation. Future research should prioritize standardized production protocols, field implementation studies, and integrated environmental and economic assessments to support the practical adoption of biochar in sustainable livestock waste management systems. Full article