Search Results (336)

This review summarizes recent applications of carbon-based materials as catalysts in the ozonation of wastewater contaminated with persistent organic pollutants. Methods available for production of commonly used inexpensive carbonaceous materials such as biochar and hydrochar are presented. Differences between production methods of active carbon and biochar or hydrochar are discussed. Interestingly, biochar, in a role of rather simple and cheap charcoal, is catalytically active and increases the rate of oxidative degradation of nonbiodegradable aqueous contaminants such as drugs or textile dyestuffs. This review documents that even the addition of biochar to the ozonized wastewater increases the rate of removal of persistent organic pollutants. Cheap bio-based carbonaceous materials such as biochar work as adsorbent of dissolved pollutants and catalysts for ozone-based degradation of organic compounds via the formation of reactive oxygen species (ROS). Low-molecular-weight degradation products produced by ozonation of pharmaceuticals and textile dyes are presented. The combination of air-based ozone generation, together with application of biochar, represents a sustainable AOP-based wastewater treatment method. Full article

This study investigates the impact of tire wear particles (TWPs) and their dissolved organic matter (DOM) on soil DOM dynamics and heavy metal behavior. Through short-term incubation experiments under simulated natural conditions with TWPs of varying particle sizes, we analyzed ecological changes in soil. Using three-dimensional excitation–emission matrix (3D-EEM) spectroscopy coupled with parallel factor analysis, we monitored the photochemical properties and compositional evolution of soil dissolved organic matter. Results demonstrate that TWP amendment substantially alters soil DOM molecular characteristics, inducing a sharp decrease in protein-, carbohydrate-, and lipid-like components, the degradation of low-aromaticity unstable dissolved organic matter, and an overall increase in aromaticity. Furthermore, TWP input directly modified soil properties, triggering the transformation of soil aggregates: the proportion of large aggregates significantly decreased while that of small aggregates increased, thereby reducing overall aggregate stability. The bioaccessibility of heavy metals (HMs) (Cd, Cu, and Zn) extracted by CaCl₂ increased, primarily due to the release of endogenous metals from TWPs, compounded by the disruption of soil aggregates. In contrast, Pb tended to transform into more stable fractions under TWP stress, reducing its bioaccessibility. Further correlation analysis indicated that TWPs indirectly affected HM (Cd, Cu, and Zn) fractionation by influencing the soil dissolved organic matter properties and soil properties. This study provides a new perspective for elucidating the interplay between dissolved organic matter and HMs in urban soils, as mediated by tire wear particles (TWPs). Full article

Cyanobacterial blooms pose significant threats to aquatic ecosystems and drinking water safety, primarily through the release of diverse secondary metabolites. This study systematically explored the dynamics of secondary metabolites in Microcystis aeruginosa and Anabaena sp. under controlled conditions, focusing on the effects of temperature (10 °C, 25 °C, 35 °C) and growth phases (exponential, stationary, decline). Key parameters measured included cell density, dissolved organic carbon (DOC), microcystins (MC-LR, MC-RR), taste and odor compounds (β-cyclocitral, β-ionone), and disinfection by-product formation potentials (trihalomethanes (THMs) and haloacetic acids (HAAs)). Results revealed striking interspecific differences: M. aeruginosa exhibited significantly higher metabolite production, with peak DOC, extracellular MC-LR, and particulate β-cyclocitral observed in the decline phase at 25–35 °C. In contrast, Anabaena sp. showed an “early accumulation advantage” for THM precursors and “residual release” in the decline phase. Temperature played a critical regulatory role, with 25 °C as the optimal for most metabolites, while 35 °C enhanced extracellular release of dissolved β-cyclocitral in M. aeruginosa. Growth phase dynamics were consistent across species, with stationary and decline phases marked by elevated metabolite concentrations due to intensified synthesis and cell lysis, particularly for HAAs. These findings highlight species-specific metabolic strategies and their environmental drivers, providing critical insights for assessing and managing cyanobacterial bloom risks in aquatic ecosystems. Full article

Silicone is widely used in medical devices due to its mechanical properties and biocompatibility; however, microbial contamination of silicone surfaces, which can lead to nosocomial infections, remains a significant concern. This can be countered by surface modification using techniques commonly involving oxidative plasma activation or ozone treatments, followed by treatment with silanization agents. Here, we report an alternative surface modification procedure involving treatment with non-toxic organic hydroxyl amines or diamine dissolved in eco-friendly solvents, thus avoiding using reactive and potentially harmful compounds and not requiring specialized equipment. Our findings demonstrate that ethanolamine in isopropanol effectively activates silicone without compromising its tensile strength, making it ideal for further modification. The activated surfaces showed stable amino group areal concentrations over a 10-day period, confirmed by fluorescence imaging and ninhydrin assays. Subsequent treatments with glutaraldehyde and chitosan enhanced the antibacterial properties of the silicone. Chitosan-coated silicone significantly reduced Gram-positive and Gram-negative bacteria colony-forming units (CFUs), with Enterococcus faecalis CFUs decreasing from 7.1 to 3.7 Log₁₀ CFU/mL. This study introduces a sustainable activation technique for silicone surfaces, resulting in medical devices with improved resistance to microbial colonization while maintaining their mechanical integrity. Full article

Nowadays, spent batteries are considered a secondary and potential resource to meet the growing demand for lithium, a critical element widely used in the manufacturing of electric vehicles. Therefore, this work presents a hydrometallurgical method for extracting lithium from Nickel–Manganese–Cobalt (NMC) batteries. Citric (${\mathrm{C}}_6{\mathrm{H}}_8{\mathrm{O}}_7$) and oxalic (${\mathrm{C}}_2{\mathrm{H}}_2{\mathrm{O}}_4$) acids were used as leaching agents, both of which are cataloged as environmentally friendly organic compounds. To comprehend the chemical interactions between citrate ($\mathrm{c}\mathrm{i}\mathrm{t}$), oxalate ($\mathrm{o}\mathrm{x}$) and metallic ions, a thermodynamic analysis is presented. According to this analysis, both ions were effective in dissolving lithium; however, the experimental studies demonstrated that oxalate ensured a selective process and achieved complete lithium dissolution under the experimental conditions 1 M C₂H₂O₄, 50 g/L, 60 °C, and 60 min, with a mechanically treated sample (milling time 8 min at 1000 rpm). In this process, the other metals present in the sample, such as cobalt, nickel, and manganese, formed insoluble species with oxalate, allowing their recovery in subsequent stages. Therefore, this investigation provides a proficient methodology for battery recycling, emphasizing sustainable practices. Full article

The increasing emphasis on green chemistry and environmentally responsible organic synthesis highlights the need to evaluate not only the biological activity but also the ecological safety of bioactive molecules. Xanthone, cinnamic acid, and chalcone scaffolds are widely explored in pharmaceutical and cosmetic research, yet their environmental profiles remain insufficiently characterized. This study assessed the ecotoxicity of simple derivatives from these three structural classes using the Microtox assay with the bioluminescent bacteria Aliivibrio fischeri. Test compounds were synthesized or obtained commercially, dissolved in dimethyl sulfoxide (DMSO), and evaluated at two exposure times (5 and 15 min), with half maximal effective concentration (EC₅₀) values calculated based on luminescence inhibition. The results revealed substantial differences between the investigated groups: chalcone derivatives exhibited uniformly high ecotoxicity, whereas cinnamic acid derivatives showed the most favorable environmental profile with low variability in EC₅₀ values. Xanthone derivatives displayed the widest ecotoxicity range, with toxicity strongly dependent on substituent type and substitution position. Notably, chloro-substitution in cinnamic acid derivatives correlated with lower toxicity, while positional effects were critical in the xanthone series. A comparison with in silico predictions generated using the ADMETlab platform showed poor correlation with the experimental outcomes. The predictive model did not distinguish the differing ecotoxicological behavior of α,β-unsaturated systems in chalcones versus cinnamic acids and systematically flagged halogenation as a toxicity-driving feature, contrary to several of our in vitro observations. Together, these findings provide new insights into structure–ecotoxicity relationships and underscore the need to complement computational predictions with validated experimental assays when designing bioactive compounds with improved environmental safety. Full article

The rapid growth in manufacturing and use of electrical and electronic equipment has led to unprecedented volumes of poorly managed e-waste, posing serious ecological risks. Although data on individual chemical substances in e-waste are available, evidence of ecotoxicity from actual e-waste materials remains scattered. This review consolidates organism-level ecotoxicity data on real e-waste samples (mixed fractions, fragments, leachates) and samples collected near e-waste facilities (soil, sediments, dust, water) across aquatic and terrestrial environments. It critically examines how methodological approaches influence reported outcomes and outlines research priorities. In aquatic environments, toxic responses vary with increased amounts of toxicants (dissolved metals, particles from dismantling operations) that mobilise to surface waters, while hydrophobic organic compounds cause sublethal behavioural and genotoxic effects. The few studies on terrestrial environments show impaired invertebrate growth and reproduction, along with changes in soil and “plastisphere” microbiota. However, tested concentrations, material complexity, and incomplete reporting of exposure chemistry, among other factors, limit the environmental relevance and comparability of the data. Uniformised procedures, combined with thorough chemical characterisation, environmentally realistic conditions, and cross-system bioassays (including different exposure routes and cumulative assessments), may provide mechanistic insights into e-waste toxicity, supporting evidence-based risk management strategies while contributing towards the development and validation of robust new approach methodologies (NAMs). Full article

Landfill leachate is highly concentrated wastewater containing non-biodegradable organic compounds and toxic substances. For this reason, advanced treatment methods are necessary for its treatment. The article discusses the possibility of treating leachate in a hybrid system combining ultrasonic pretreatment and anaerobic co-digestion with dairy wastewater in an anaerobic membrane bioreactor. Two laboratory-scale submerged anaerobic membrane reactors with a capillary module with membranes with a pore size of 0.1 μm and an effective filtration area of 0.35 m² were used in this study. An ultrasound disintegrator at 22 kHz (amplitude 14 µm) was used for leachate pretreatment. It was found that, as a result of leachate sonification (time > 10 min), the BOD₅/COD ratio in the wastewater increased from 0.1 to 0.4, and the content of dissolved organic compounds accounted for more than 40% of the total COD. Preliminary sonication of the leachate resulted in improved co-digestion efficiency in a reactor fed with conditioned leachate. A 92% reduction in organic pollutants was achieved, as well as a biogas production rate of 0.5 L biogas/g COD removed. Full article

Dissolved organic matter (DOM) is a crucial carbon source for soil microorganisms and plays a vital role in nutrient cycling and carbon (C) sequestration in soils. However, the extent to which soil microbes mediate DOM transformation at the molecular level, and whether this is regulated by different organic fertilization, remains unclear. Here, we designed a field experiment to investigate the transformations of DOM under three types of organic fertilization (straw, biochar, and manure) using Fourier transform ion cyclotron resonance mass spectrometry and metagenomic analysis. Compared to the control, manure fertilization increased the molecular chemodiversity of DOM by 33.2%, with recalcitrant compounds (e.g., highly unsaturated phenolic compounds and lignins) increasing by 47.2%. In contrast, labile compounds (e.g., aliphatics) decreased by 73.5%. Compared to straw treatment, manure application significantly increased the average conversion rate of dissolved organic matter (DOM). This process was accompanied by a significant increase in the Shannon index of the soil microbial community (p < 0.05) and upregulation of ABC transporter-encoding genes (e.g., livK, livM). DOM composition directly governed transformation potential (p < 0.01), whereas functional genes enhanced transformation indirectly by modulating DOM composition. This study elucidates microbial-mediated DOM transformation mechanisms under varying organic fertilization practices, providing a scientific basis for optimizing soil organic matter management in paddy ecosystems. Full article

Biocides, including fungicides and paraben preservatives, are widely used in medicine, agriculture and food industries, and are ubiquitous in aquatic environments, which will have adverse impacts on aquatic organisms. This study investigated the occurrence, distribution, ecological risks, and human health risks of 7 target biocides in Chao Lake, a large eutrophic urban lake, and its tributaries. Four biocides were detected, with total concentrations ranging from 186 ng/L to 853 ng/L. Carbendazim (CBD), fluconazole (FCZ), and methylparaben (MP) had detection frequencies of 100%, with mean concentrations of 234 ng/L, 35.3 ng/L, and 26.8 ng/L, respectively. Significant spatial heterogeneity was observed, with obviously elevated levels in the western region compared with the central and eastern regions. Strong correlations (p ≤ 0.01) were found between these three biocides, CBD, FCZ, and climbazole (CLI), and the following two environmental factors: total nitrogen and dissolved total nitrogen. Based on the risk quotient (RQ) evaluation, CBD was identified as a high-risk compound for aquatic organisms, particularly Daphnia magna, with RQ values exceeding 1 and reaching up to 7.42. CLI showed moderate risks at some sampling sites, while FCZ and MP posed no risk. Human health risk quotient (RQ_h) analysis revealed no significant health risks to different age groups, with the RQ_h values of biocides at all sampling sites in Chao Lake below 0.1. The ecological risks of CBD warrant even greater attention. Full article

Nutrient cycling has barely been studied in acidic environments and may have an important influence on the evolution of the microbial communities. In this research, we studied nutrient sources and fluxes in acidic metal-mine pit lakes to evaluate their relationship with the lakes’ microbial ecology. Nutrient concentrations (including phosphorus, nitrogen, and dissolved inorganic carbon) increase with depth in all the studied pit lakes. Phosphorus comes mainly from the leaching of the host rock and is rapidly scavenged from the aqueous phase in the oxygenic and Fe(III)-rich mixolimnion due to adsorption on ferric precipitates (schwertmannite, jarosite), which leads to an important P-limitation in the photic zone. Below the chemocline, however, the sum of phosphorus inputs (e.g., settling of algal biomass, desorption from the ferric compounds, microbial reduction of Fe(III)-sediments) sharply increases the concentration of this element in the anoxic monimolimnion. Nitrogen is very scarce in the host rocks, and only a limited input occurs via atmospheric deposition followed by N-uptake by algae, N-fixation by acidophilic microorganisms, sedimentation, and organic matter degradation in the sediments. The latter process releases ammonium to the anoxic monimolimnion and allows some nitrogen cycling in the chemocline. Soluble SiO₂ in the mixolimnion is abundant and does not represent a limiting nutrient for diatom growth. Differences in phytoplankton biomass and extent of bacterial sulfate reduction between relatively unproductive lakes (San Telmo) and the more fertile lakes (Cueva de la Mora) are likely caused by a P-limitation in the former due to the abundance of ferric iron colloids in the water column. Our results suggest that phosphorus amendment in the photic zone could be an efficient method to indirectly increase acidity-consuming and metal-sequestering bacterial metabolisms in these lakes. Full article

Background: Although hydrolysis and photolysis are important pathways for penicillin antibiotics degradation in aquatic ecosystems, the degradation mechanism of penicillin antibiotics in real natural waters is rarely reported. Furthermore, the dominant factors influencing this process are poorly understood. Methods: Therefore, five natural waters were selected to simulate both the hydrolysis and photolysis processes of penicillin G (PG) in aqueous environments. Results: Our results demonstrated that the half-life of PG hydrolysis ranged from 44 h to 141 h in natural water, and aqueous Ca²⁺ ion was the most important factor controlling the hydrolytic degradation of PG. Moreover, several biological dissolved organic matter (DOM, microbial by-product compounds) could also promote the PG hydrolysis reaction. Direct photolysis of PG is dominated in natural water, for which half-life photodegradation rates were 6 h in both blank and natural water, suggesting that salinity and DOM have little influence on penicillin photolysis. The hydrolysis reaction mainly involved the cleavage of the ester bond in the β-lactam ring and a decarboxylation process, while photolysis degradation principally included the hydroxylation of the benzene ring and destruction of the thiazole ring. Conclusions: This study demonstrates the significant factors influencing hydrolysis and photolysis of penicillin antibiotics in an aquatic ecosystem, which can improve the estimates of ecological risk of antibiotic pharmaceuticals in a realistic environment. Full article

The separation of oil-in-water emulsions from industrial wastewater remains a significant challenge, particularly under saline conditions. This study evaluated bacterial cellulose (BC) membranes from Komagataeibacter hansenii for filtering synthetic effluents with high oil content (ES1) and saline oil-in-water emulsions (ES2). FTIR confirmed the incorporation of lipophilic compounds into the BC matrix. Crystallinity decreased from 78.8% to 40% following ES1 filtration, while a new peak at 2θ ≈ 31.8° appeared in ES2, indicating salt deposition. TGA revealed increased mass loss in the oil-saturated membrane (BCO), whereas the saline-exposed membrane (BCOS) exhibited higher thermal stability. SEM showed fiber compaction and localized deposition of oil and salt, corroborated by EDS, which identified Na, Cl, Ca, and elevated oxygen levels. Mechanical testing indicated that oil acted as a plasticizer, increasing the elongation at break of BCO, while salt crystallization enhanced BCOS stiffness. The membranes removed up to 98% of organic load (BOD and COD), 69% of oils and greases, and reduced turbidity and apparent color by 92%. Partial salt retention (~23%) and a significant decrease in dissolved oxygen were also observed. These results demonstrate the potential of BC membranes as an effective and sustainable solution for the treatment of complex oily and saline wastewater. Full article

Cyanobacteria can pose a threat to aquatic organisms by their ability to produce toxins such as neurotoxic anatoxins. Although cyanobacteria and their effects on aquatic fauna have been a research focus for a long time, the interactions between benthic cyanobacteria and benthic invertebrates are still largely unknown, especially with regard to how invertebrates cope with cyanotoxins which they are exposed to in their habitat. This study characterizes the effects of anatoxins on the benthic macroinvertebrate Hyalella azteca. In a first test, organisms were exposed to synthetically produced anatoxins dissolved in the ambient aqueous phase. In a second test, organisms were exposed to natural anatoxins within intact Tychonema cells as their sole food source. Over 10 days of aqueous exposure to anatoxins, survival of H. azteca was not affected, even at the highest nominal concentrations of 587.37 µg/L ATX and 590.31 µg/L dhATX. Over 42 days of dietary exposure to natural anatoxins, H. azteca readily accepted Tychonema as a food source. Survival, growth, reproductive success and storage compound concentrations (glucose, glycogen, lipid and protein) in the organisms’ tissue, all assessed in the same individuals, were reduced. These findings suggest that the ecotoxicological effects of anatoxins on aquatic invertebrates not only depend on their concentration, but even more so on the type and duration of exposure. Furthermore, cyanobacteria like Tychonema seem to be insufficient as source of energy if they represent the only available food source. Full article

The aim of this study was to evaluate the effect of low-temperature disintegration of Chlorella vulgaris using solidified carbon dioxide (SCO₂) on the efficiency of anaerobic digestion of microalgae biomass. The novelty of this study resides in the pioneering application of SCO₂ for the pretreatment of C. vulgaris biomass to enhance methane fermentation. This approach integrates mechanical disruption of cell walls with improved solubilization of organic fractions at low temperatures, providing an innovative and energy-efficient strategy to boost biomethanogenesis performance. This study was carried out in four stages, including characterisation of substrate properties, evaluation of organic compound solubilization following SCO₂ pretreatment, and fermentation under both batch and continuous conditions. Analysis of dissolved COD and TOC fractions revealed a significant increase in the bioavailability of organic matter as a result of SCO₂ application, with the highest degree of solubilization observed at a SCO₂/C. vulgaris biomass volume ratio of 1:3. In batch reactors, CH₄ yield increased significantly to 369 ± 16 mL CH₄/g VS, methane content in biogas reached 65.9 ± 1.0%, and kinetic process parameters were improved. Comparable enhancements were observed in continuous fermentation, with the best scenario yielding 243.4 ± 9.5 mL CH₄/g VS. Digestate analysis confirmed more efficient degradation of organic fractions, and the stability of methanogenic consortia was maintained, with only moderate changes in the relative abundance of the main groups (Methanosarcinaceae, Methanosaeta). Energy balance calculations indicated a positive net effect of the process. This study represents a pioneering application of SCO₂ pretreatment in the context of microalgal biomass and highlights its high potential for intensifying anaerobic digestion. Full article