Search Results (33)

Diclofenac (DCF), a widely consumed non-steroidal anti-inflammatory drug, presents significant environmental challenges due to its persistence and toxicity in aquatic ecosystems. This study investigates the pH-dependent ozonation of DCF in aqueous media, focusing on degradation kinetics, transformation pathways, and effects on key water quality indicators. Ozonation experiments were conducted across a broad pH range (2.0–13.0), using a multi-scale analytical approach combining UV/Vis spectroscopy, colorimetry, turbidity, and aromaticity measurements. The results show that pH strongly influences DCF degradation efficiency: acidic conditions favor selective reactions with molecular ozone, while an alkaline pH enhances non-selective oxidation via hydroxyl radicals. Spectroscopic analyses revealed the progressive breakdown of aromatic structures, the transient formation of quinonoid and phenolic intermediates, and eventual mineralization to inorganic by-products such as nitrate. Low-pH conditions also induced turbidity due to precipitation of neutral DCF species. These findings underline the importance of pH control in optimizing ozonation performance and minimizing toxic by-products. Furthermore, this study proposes ozonation as a viable pre-treatment step within Nature-Based Solutions (NBSs), potentially improving the performance of downstream biological systems such as constructed wetlands. The results contribute to the development of integrated and sustainable water treatment strategies for pharmaceutical contaminant removal and water reuse. Full article

Shrimp are highly favored by consumers for their delicious taste and rich nutritional value. However, reports of allergic reactions caused by shrimp and its derivatives have been increasing, significantly impacting consumer health and posing a growing global food safety concern. This article introduces the structure and biochemical characteristics of major allergenic proteins in shrimp, including tropomyosin (TM), arginine kinase, sarcoplasmic calcium-binding protein, myosin light chain, troponin C, and hemocyanin. Currently, there is no effective treatment for shrimp allergies, and prevention is mainly achieved by avoiding consumption. The study of shrimp allergen sensitization reduction technology is of great significance to the development of hypoallergenic or desensitized products. The article provides a detailed overview of the effects of common processing techniques, including physical, chemical, biological, and combined methods, on the allergenicity of shrimp allergens; for instance, the binding rate to immunoglobulin E (IgE) was reduced by 73.59% after treating TM with high pressure (500 MPa) at 55 °C for 10 min and the recognition rate of TM to IgE decreased by 89.4% on average after treating TM with pepsin (30 μg/mL, pH 2) for 2 h. These techniques provide references for the development of hypoallergenic aquatic products or desensitized foods. Full article

Real winery wastewater (WW), with a high concentration of organic matter (OM), was treated using Fenton (FP), photo-Fenton (PFP), sono-Fenton (SFP), and sono-photo-Fenton processes (SPFP), with the primary objective of removing phenolic compounds (PhCs). Although beneficial to human health, these compounds are considered recalcitrant and toxic to aquatic organisms, posing significant environmental risks if discharged into water bodies. They can also reduce the efficiency of biological treatment processes. After physicochemical characterization and two hours of treatment, the removal efficiencies achieved by the FP, PFP, SFP, and SPFP processes were 29.35%, 41.30%, 28.82%, and 33.95% for PhCs; 27.88%, 31.51%, 23.19%, and 29.29% for chemical oxygen demand (COD); and 12.53%, 13.92%, 9.28%, and 10.62% for dissolved organic carbon (DOC), respectively. The degradations achieved by SFP and SPFP were lower than those of FP and PFP, respectively, due to reactions that scavenge hydroxyl radicals. Treatment of a gallic acid (GA) solution, used as a model compound for PhCs, exhibited similar trends, indicating that the lower efficiency in processes involving ultrasound is not due to the OM in the effluent, but rather the interaction between ultrasound (US) and H₂O₂, which reduces hydroxyl radical concentration. However, under the conditions of the wastewater used, the technologies applied did not completely reduce the parameters analyzed, being recommended as pre- or post-treatment, and combined with other processes. Full article

Ethylene glycol (EG) is a contaminant in the wastewater of airports because it is commonly used in aircraft deicing fluids during the cold season in northern regions. Ethylene glycol by itself has relatively low toxicity to mammals and aquatic organisms, but it can lead to a substantial increase in chemical and biological oxygen demands. The contamination of water with EG facilitates the rapid growth of microbial biofilms, which decreases the concentration of dissolved oxygen in water and negatively affects overall biodiversity. The development of a simple method to decompose EG with high efficiency and low operating costs is important. This study revealed that ethylene glycol can be completely oxidized using UV-C activated hydrogen peroxide (H₂O₂/UV-C) at a high rate (up to 56 mg L⁻¹ h⁻¹) at an optimum EG:H₂O₂ molar ratio of 1:10–1:15. Air purging the reaction mixture at 1000 cm³ min⁻¹ increases the EG mineralization rate up to two times because the simultaneous action of UV-activated H₂O₂ and O₂ (H₂O₂ + O₂/UV-C) leads to a synergistic effect, especially at low EG:H₂O₂ ratios. The kinetics and mechanism of EG degradation are discussed on the basis of the concentration profiles of ethylene glycol and intermediate products. Full article

Onsite wastewater treatment systems (OWTSs), although essential for managing domestic sewage in areas without centralized sewerage treatment plants, often release phosphorus (P) into the environment due to inadequate treatment. This unregulated P discharge exacerbates water quality degradation and jeopardizes aquatic habitats and human health. Among different treatment technologies, electrocoagulation (EC) demonstrates considerable potential for addressing this challenge by efficiently removing P from OWTSs and thus protecting water resources and ecological integrity. Through electrochemical reactions, EC destabilizes and aggregates P-bearing particles, facilitating their removal through precipitation. Compared to conventional treatment approaches, i.e., chemical and biological methods, EC offers several advantages, including high efficiency, minimal chemical usage, and adaptability to varying wastewater compositions. This review underscores the urgent need for mitigating P discharge from OWTSs and the efficacy of EC as a sustainable solution for P removal, offering insights into its mechanisms, reactor design considerations, important operational factors, performance, and potential applications in OWTSs as well as providing future research directions. Full article

The issue of the qualitative and quantitative analysis of the concentration of oxidising species in aquatic environments is crucial for a wide range of biological and environmental tasks. In particular, reactive chlorine species, specifically hypochlorite (ClO⁻), play a significant biochemical role in the operation of the immune system. There is also the challenge of determining the presence of ClO⁻ in purified drinking water that is supplied by water treatment systems. Traditional chemical analytical methods often lack the required selectivity and sensitivity to detect oxidising compounds, and chemiluminescence-based techniques offer an alternative solution. In this study, we propose a simple and selective approach for the chemiluminescent detection of hypochlorite in aqueous media under neutral conditions. The technique is based on measuring a chemiluminescent signal generated in the presence of hypochlorite by a combined probe comprising commercially available WS₂ quantum dots and luminol. The oxidation of WS₂ with hypochlorite followed by a reaction with luminol results in an intense luminescent signal that enables the selective determination of hypochlorite under neutral conditions. The greatest sensitivity with this method was achieved when combining WS₂ quantum dots with L-012, a highly sensitive analogue of luminol. Additionally, the use of L-012 improved the detection limit for hypochlorite to 2 × 10⁻⁶ M. Due to its selectivity in determining hypochlorite in the presence of reactive oxygen species (hydrogen peroxide) under neutral conditions with high sensitivity and with a wide linear range, the proposed approach provides an attractive analytical tool for the analysis of water samples and biological liquids. Full article

Phosphorus (P) discharge from anthropogenic sources, notably sewage effluent and agricultural runoff, significantly contributes to eutrophication in aquatic environments. Stringent regulations have heightened the need for effective P removal technologies in wastewater treatment processes. This paper provides a comprehensive review of current P removal methods, focusing on both biological and chemical approaches. Biological treatments discussed include enhanced biological P removal in activated sludge systems, biological trickling filters, biofilm reactors, and constructed wetlands. The efficiency of microbial absorption and novel biotechnological integrations, such as the use of microalgae and fungi, are also examined. Chemical treatments reviewed encompass the application of metal salts, advanced oxidation processes such as chlorination, ozonation, and the Fenton reaction, as well as emerging techniques including the Electro-Fenton process and photocatalysis. Analytical methods for P, including spectrophotometric techniques and fractionation analyses, are evaluated to understand the dynamics of P in wastewater. This review critically assesses the strengths and limitations of each method, aiming to identify the most effective and sustainable solutions for P management in wastewater treatment. The integration of innovative strategies and advanced technologies is emphasized as crucial for optimizing P removal and ensuring compliance with environmental regulations. Full article

Sulfonamides can be effectively removed from wastewater through a photocatalytic process. However, the mineralization achieved by this method is a long-term and expensive process. The effect of shortening the photocatalytic process is the partial degradation and formation of intermediates. The purpose of this study was to evaluate the sensitivity and transformation of photocatalytic reaction intermediates in aerobic biological processes. Sulfadiazine and sulfamethoxazole solutions were used in the study, which were irradiated in the presence of a TiO₂-P25 catalyst. The resulting solutions were then aerated after the addition of river water or activated sludge suspension from a commercial wastewater treatment plant. The reaction kinetics were determined and fifteen products of photocatalytic degradation of sulfonamides were identified. Most of these products were further transformed in the presence of activated sludge suspension or in water taken from the river. They may have been decomposed into other organic and inorganic compounds. The formation of biologically inactive acyl derivatives was observed in the biological process. However, compounds that are more toxic to aquatic organisms than the initial drugs can also be formed. After 28 days, the sulfamethoxazole concentration in the presence of activated sludge was reduced by 66 ± 7%. Sulfadiazine was practically non-biodegradable under the conditions used. The presented results confirm the advisability of using photocatalysis as a process preceding biodegradation. Full article

Lipoxygenases make several biological functions in cells, based on the products of the catalyzed reactions. In diatoms, microalgae ubiquitous in aquatic ecosystems, lipoxygenases have been noted for the oxygenation of fatty acids with the production of oxylipins, which are involved in many physiological and pathological processes in marine organisms. The interest in diatoms’ lipoxygenases and oxylipins has increased due to their possible biotechnological applications, ranging from ecology to medicine. We investigated using bioinformatics and molecular docking tools the lipoxygenases of diatoms and the possible interaction with substrates. A large-scale analysis of sequence resources allowed us to retrieve 45 sequences of lipoxygenases from diatoms. We compared and analyzed the sequences by multiple alignments and phylogenetic trees, suggesting the possible clustering in phylogenetic groups. Then, we modelled the 3D structure of representative enzymes from the different groups and investigated in detail the structural and functional properties by docking simulations with possible substrates. The results allowed us to propose a classification of the lipoxygenases from diatoms based on their sequence features, which may be reflected in specific structural differences and possible substrate specificity. Full article

The selective serotonin reuptake inhibitor fluoxetine is one of the most commonly administered psychotropic medications; however, it has been recognized as toxic to aquatic life. In this study, we showed that stress responses and feeding motivation in Nile tilapia were affected by acute exposure to fluoxetine. To reach that conclusion, we exposed Nile tilapia to 0, 1 or 10 µg/L (environmentally/biologically relevant doses) of fluoxetine over a 24 h period and then exposed them to a handling stressor. We found that the 10 µg/L dose enhanced cortisol response to stress but caused an earlier decrease in the ventilation boost induced by that stressor. An immediate ventilation boost after stressful stimuli indicates sympathetic activation. Thus, this suggests that fluoxetine decreased sympathetic nervous system activity but augmented hypothalamus–pituitary–interrenal axis activity in the fish. Both feeding latency and ingestion were similar among the tested conditions; however, a multiple logistic regression model revealed that in the presence of a stressor or fluoxetine, the Nile tilapia tended to ingest less food but there was a higher probability of this decrease to be associated with fluoxetine. We concluded that acute exposure to environmentally/biologically relevant fluoxetine concentrations over 24 h acted as a modifying factor for Nile tilapia stress physiology and tended to interfere with feeding motivation. An acute stress response is an emergency reaction that contributes to the recovery of homeostasis. In the presence of fluoxetine, modifications of acute stress responses and the tendency to reduce food intake, which restricts the ability to replace the energy spent on stress responses, could compromise the resumption of homeostasis and an animal’s adjustment to different environmental contexts, such as those associated with aquaculture, in which anthropogenic stressors inevitably occur. Full article

Phenolic chemicals are poisonous and have long-term impacts on humans and animals. Even in low quantities, as carcinogens, they destroy red blood cells and the liver. These biological waste products pollute groundwater. Thus, removing these organic chemicals to meet discharge limits is difficult. Electrochemical oxidation, redox reactions, membrane separation, and photocatalytic degradation help remove phenolic chemicals from water. Recently, phenolic chemicals have been shown to be removed via adsorption and photocatalysis employing carbon materials and clays. Due to their unique chemical and physical properties, nanometric materials are crucial to these processes. These substances’ structures, classification, entry points, and reactivity or interaction with other aquatic components have been extensively studied. Phenolic substances can be removed from the water before usage. This has led to the development of water treatment technologies and methods like activated carbon adsorption, solvent extraction, the electro-Fenton method, membrane-based separation method, photocatalysis, and others that have been shown to successfully remove phenolic compounds from water. Activated carbon is the most promising adsorbent for numerous contaminants (dyes, metals, etc.). However, low-cost agricultural materials are typically used to switch to more environmentally friendly ones. This study uses low-cost, eco-friendly adsorbents to remediate biomedical effluents. Pyrolysis of potato peels (waste) from a restaurant produced carbon samples. Absorption–desorption experiments examined pH, temperature, starting drug concentration, contact time, and regeneration ability. Full article

Amongst per- and polyfluoroalkyl substances (PFAS) compounds, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have a high persistence in physicochemical and biological degradation; therefore, the accumulation of PFOS and PFOA can negatively affect aquatic organisms and human health. In this study, two microalgae species (Chlorella vulgaris and Scenedesmus obliquus) were exposed to different concentrations of a PFOS and PFOA mixture (0 to 10 mg L⁻¹). With increases in the contact time (days) and the PFAS concentration (mg L⁻¹) from 1 to 7, and 0.5 to 10, respectively, the cell viability, total chlorophyll content, and protein content decreased, and the decrease in these parameters was significantly greater in Scenedesmus obliquus. As another step in the study, the response surface methodology (RSM) was used to optimize the toxicity effects of PFAS on microalgae in a logical way, as demonstrated by the high R² (>0.9). In another stage, a molecular docking study was performed to monitor the interaction of PFOS and PFOA with the microalgae, considering hydrolysis and the enzymes involved in oxidation-reduction reactions using individual enzymes. The analysis was conducted on carboxypeptidase in Chlorella vulgaris and on c-terminal processing protease and oxidized cytochrome c6 in Scenedesmus obliquus. For the enzyme activity, the affinity and dimensions of ligands-binding sites and ligand-binding energy were estimated in each case. Full article

Coumarins represent a broad class of compounds with pronounced pharmacological properties and therapeutic potential. The pursuit of the commercialization of these compounds requires the establishment of controlled and highly efficient degradation processes, such as advanced oxidation processes (AOPs). Application of this methodology necessitates a comprehensive understanding of the degradation mechanisms of these compounds. For this reason, possible reaction routes between HO^• and recently synthesized aminophenol 4,7-dihydroxycoumarin derivatives, as model systems, were examined using electron paramagnetic resonance (EPR) spectroscopy and a quantum mechanical approach (a QM-ORSA methodology) based on density functional theory (DFT). The EPR results indicated that all compounds had significantly reduced amounts of HO^• radicals present in the reaction system under physiological conditions. The kinetic DFT study showed that all investigated compounds reacted with HO^• via HAT/PCET and SPLET mechanisms. The estimated overall rate constants (k_overall) correlated with the EPR results satisfactorily. Unlike HO^• radicals, the newly formed radicals did not show (or showed negligible) activity towards biomolecule models representing biological targets. Inactivation of the formed radical species through the synergistic action of O₂/NO_x or the subsequent reaction with HO^• was thermodynamically favored. The ecotoxicity assessment of the starting compounds and oxidation products, formed in multistage reactions with O₂/NO_x and HO^•, indicated that the formed products showed lower acute and chronic toxicity effects on aquatic organisms than the starting compounds, which is a prerequisite for the application of AOPs procedures in the degradation of compounds. Full article

Due to its unique biological composition, aquatic products, especially fish, are extremely perishable compared to other muscle products. Herein, we proposed an artificial nanozyme-based colorimetric detection of hypoxanthine (Hx), the indicator of fish freshness, in a minute–time scale without the assistance of a natural enzyme (hypoxanthine oxidase). The principle is based on the interaction between Hx and polyvinylpyrrolidone-modified platinum cubic nanomaterials (PVP-PtNC), in which the catalytic active sites of PVP-PtNC’s surface were blocked by Hx. This causes the downregulation of PVP-PtNC’s catalytic ability and weakened its ability to catalyze the oxidization of 3,3′,5,5′-Tetramethylbenzidine (TMB) by H₂O₂. Accordingly, the decrease in the UV–vis absorption and the weakening of the colorimetric reaction color is proportional to the Hx concentration. On this basis, a target-triggered colorimetric method for detecting Hx is developed for fish freshness monitoring with a fast detection speed, low cost, high accuracy, and simplified operation. Experiments reveal that the correlation response of Hx is from 0.5 μM to 10 mM with a limit of detection of 0.16 μM. In particular, the Hx detected from real fish indicates that the method possesses a promising potential for practical application. All of these features are expected to promote the development of online detection tools for food safety monitoring. Full article

Owing to the toxicity and adverse effects of arsenic on human health, its levels in aquatic environments are among the most serious threats to humans globally. To improve our understanding of its occurrence and cycling in aquatic environments, herein we review the concentration, speciation, and distribution of arsenic in freshwater, seawater, and sediments. Many natural processes, such as rock weathering and geothermal activities, contribute to the background arsenic concentrations in the natural environment, whereas metal mining and smelting are anthropogenic sources of arsenic in the water. The high solubility and mobility of arsenic in aquatic environments affects its global cycling. Furthermore, the biological processes in the aquatic environment are discussed, especially the possible microbe-mediated reactions of arsenic in sediments. In addition, various environmental factors, such as redox conditions, pH, and salinity, which influence the transformation of arsenic species, are summarized. Finally, the differences between freshwater and seawater with reference to the concentration as well as speciation and distribution patterns of arsenic are addressed. This review provides deep insights into arsenic occurrence and cycling between freshwater and seawater aquatic environments, which can more accurately distinguish the risks of arsenic in different water environments, and provides theoretical guidance for the prevention and control of arsenic risks. Full article