Search Results (512)

Phenolic compounds are widespread environmental contaminants whose removal from water and wastewater is essential for ecosystem protection. Among the several purification technologies, the use of zero-valent metals has gained increasing interest in recent years. The identification of effective and environmentally friendly materials is a key issue for the development of this technology. In this study, zero-valent magnesium (ZVMg), a highly reactive non-toxic material, was used for the first time for the degradation of gallic acid (GA), chosen as a model phenolic compound, in an aqueous system. Several tests were conducted in order to identify the effect of pH, ZVMg amount, and temperature on the process performance. Moreover, the reusability of the reactive material in subsequent treatment cycles was assessed. Optimal operational conditions were achieved with a ZVMg amount of 0.3 g, corresponding to a ratio of 0.33 g_GA/g_Mg, reaching a removal efficiency of almost 90% in about 180 min. The performance was clearly favored by an alkaline environment, and yields close to the maximum values were reached under uncontrolled pH conditions. The increase in temperature significantly accelerated the reaction rate, which followed pseudo-first-order kinetic law, achieving high abatement percentages with a reduced quantity of ZVMg. Finally, Mg⁰ demonstrated good reusability, maintaining high efficiency, close to 78%, for up to four cycles, with the possibility of restoring the material’s activity through acid washing. The detected results confirm that ZVMg is a promising and sustainable reactive material for environmental remediation processes, offering an effective alternative for the treatment of water contaminated by phenolic compounds. Full article

Olive mill wastewater (OMW) contains high organic loads and phytotoxic polyphenols. In Tunisia, OMW is often stored in unlined evaporation ponds. This practice creates a risk of soil and groundwater contamination. This study evaluates the environmental impact of a long-term OMW evaporation pond in the Ben Aoun area, Sidi Bouzid region. The investigation combines wastewater, soil and groundwater sampling with laboratory physicochemical analyses. Three OMW samples (E1 surface, E2 mixed, E3 recent spill) were collected. Three shallow boreholes (0–5 m) were sampled at 20 cm intervals. In addition, three nearby pumping wells were sampled. All samples were analyzed for pH, electrical conductivity (EC), chemical oxygen demand (COD), total and volatile solids, major cations/anions, total nitrogen, total phosphorus and total polyphenols. Results obtained using the Folin–Ciocalteu method are expressed as mg Eq AG L⁻¹ for liquids and mg Eq AG gMS⁻¹ for soils. OMW samples showed high COD (E1 = 48, E2 = 70, E3 = 80 g/L) and polyphenols (E1 = 5, E2 = 9.7, E3 = 14 g/L). Soil profiles inside the pond exhibited increased EC with peak of 15.48 mS cm⁻¹ at 0.4 m depth. Near-surface layers showed low pH and increased organic matter and polyphenols to depths of ~5 m. Groundwater samples collected near the pond contained measurable polyphenols (up to 41 mg/L in the closest well), indicating subsurface migration. Evidence indicates lateral migration of about 20 m and vertical infiltration to a depth of approximately 5 m beneath the pond. The findings demonstrate that unlined OMW evaporation ponds act as a persistent source of organic and phenolic contamination. This poses a potential risk to shallow groundwater. Full article

Pecan (Carya illinoinensis) cultivation generates a substantial number of byproducts, particularly nutshells, which are often discarded despite being rich in bioactive and structural compounds. These agro-industrial residues, comprising nearly 50% of the total nut mass, contain high levels of phenolics, flavonoids, dietary fiber, and lignocellulosic matter, making them suitable for circular economy applications. This review critically evaluates the potential of pecan shell waste for value-added applications in environmental remediation, food and pharmaceutical formulations, and green materials production. It explores innovative green extraction techniques, such as ultrasound-assisted, microwave-assisted, and subcritical water extraction, to recover valuable compounds like ellagic acid and tannins with high efficiency and minimal environmental impact. Moreover, the review highlights the conversion of pecan shells into activated carbon for wastewater treatment and soil remediation. Pecan byproducts have been used as sustainable feedstocks for catalyst support, contributing to energy conversion and biomass catalysis. The bioactive compounds also offer therapeutic properties, including antioxidant, anti-inflammatory, and antimicrobial effects, supporting their inclusion in nutraceutical and cosmetic applications. Through a comprehensive synthesis of recent studies, this work highlights the role of pecan shell valorization in reducing waste, improving public health, and increasing economic resilience within agro-industrial systems. By aligning with sustainable development and circular economies, the utilization of pecan byproducts provides a low-cost, eco-innovative pathway to mitigate environmental pollution and promote sustainable development. Full article

This study explores the application of a cobalt–manganese oxide catalyst supported on coal gangue (CoMnOx@CG) for peroxymonosulfate (PMS) activation to degrade phenol in coal chemical wastewater (CCW). The synthesized CoMnOx@CG catalyst demonstrated remarkable catalytic activity, achieving above 90% phenol removal within 10 min at pH 9 and 11. More importantly, the catalyst exhibited excellent stability and reusability, maintaining over 85% phenol removal efficiency after four consecutive cycles and cobalt leaching below 100 μg/L. Quenching experiments and electron paramagnetic resonance (EPR) analyses revealed that singlet oxygen (¹O₂), sulfate radicals (SO₄·⁻), and hydroxyl radicals (·OH) contributed to the degradation process. When treating actual CCW, the system significantly reduced both phenol and fluorescent dissolved organic matter, demonstrating its effectiveness for complex wastewater matrices. CoMnOx@CG provides a sustainable and practical solution for alkaline refractory wastewater remediation. Full article

Water contamination by antibiotics has become a critical environmental and public health issue. Among emerging technologies for their removal, heterogeneous photocatalysis has shown remarkable potential. This review provides a systematic analysis of 40 recent studies (2019–2025) that employed green synthesis routes—including sol–gel, hydrothermal, combustion, pyrolysis and co-precipitation methods—for the photocatalytic degradation of antibiotics. The comparison of these techniques revealed that biogenic metal oxides and ferrites synthesized with plant extracts achieved outstanding photocatalytic performance, with degradation efficiencies often exceeding 90–100% for antibiotics such as ciprofloxacin and tetracycline. These results are attributed to the phytochemical composition of the extracts, which are rich in flavonoids, phenols, saponins, tannins, and alkaloids, which act as natural reducing, capping, and stabilizing agents, promoting uniform nucleation, smaller particle sizes, and enhanced crystallinity. The review also highlights the synergistic relationship between biomolecule-mediated reduction and controlled synthesis conditions, which enables the design of sustainable, reusable, and high-efficiency photocatalysts for wastewater treatment and environmental remediation. Full article

Large quantities of wastewater (OMW) are generated by the olive oil industry, requiring sustainable management to mitigate environmental impacts. The main goal of this work is to evaluate the possibility of using the homogeneous Fenton process as a pretreatment of OMW, as well as the iron (Fe (II) and Fe (III)) addition to improve the methane production through AD. The Fenton process achieved chemical oxygen demand (COD) and total phenolic compound (TPh) removals of 17–47% and 75–94%, respectively. However, methane production did not improve compared with untreated OMW, which yielded about 82 NmL CH₄/ g COD_i. The increase in H₂S production from about 2 mL in raw OMW to more than 8 mL in treated OMW may justify the inhibition of AD. Supplementing AD with 2 mg/L of Fe (III) increased methane production by 65% and significantly reduced H₂S due to FeS precipitation. The addition of 1 and 2 mg/L of Fe (II) also increased methane production by 82 and 59%, respectively, but no reduction in H₂S was observed. Therefore, although the Fenton pretreatment effectively reduces recalcitrant organic matter, it does not necessarily enhance methane production. A balance must be achieved between improving OMW characteristics and minimizing adverse impacts on AD performance. Full article

Background: Olive cultivation and olive oil production are key agricultural sectors in the Dalmatia region, where numerous oil mills operate. Analyses have shown that extra virgin olive oils (EVOO) produced in this area contain respectable amounts of polyphenols, which contribute to superior oil quality due to their antioxidant properties. During processing, hydrophilic phenolic compounds predominantly transfer into olive mill wastewater (OMW), making it a concentrated source of valuable bioactive molecules. The antioxidant, anti-inflammatory, and photoprotective effects of these polyphenols are highly relevant for cosmetic and pharmaceutical use. Methods: A total of 186 OMW samples were collected from oil mills in the Split-Dalmatia County across three production seasons (2023–2025). Total polyphenol content (TPC) was measured spectrophotometrically, while polyphenol composition was determined by High Performance Liquid Chromatography (HPLC). Antioxidant activity was evaluated using hydrogen atom transfer (HAT; 2,2-diphenyl-1-picrylhydrazyl) (DPPH), electron transfer (ET; ferric reducing antioxidant power) (FRAP), and oxygen radical absorbance capacity assay (ORAC). Results: The obtained results indicated high total polyphenols concentrations, with values ranging from 111.8 to 6717.2 mg of gallic acid equivalents per L of OMW (mg GAe L⁻¹). In the vast majority of analyzed samples, hydroxytyrosol was the predominant phenol compound. The antioxidant activity of the samples was high. Full article

Wastewater-derived microplastics (WW-MPs) are increasingly recognised as reactive vectors for aromatic organic contaminants (AOCs), yet their role in contaminant fate remains insufficiently constrained. This review synthesises current knowledge on the transformation of microplastics in wastewater treatment plants, including fragmentation, oxidative ageing, additive leaching, and biofilm formation, and links these processes to changes in sorption capacity toward phenols, PAHs and their derivatives, and organochlorine pesticides (OCPs). We summarise the dominant adsorption mechanisms-hydrophobic partitioning, π-π interactions, hydrogen bonding, and electrostatic and, in some cases, halogen bonding-and critically evaluate how wastewater-relevant parameters (pH, ionic strength, dissolved organic matter, temperature, and biofilms) can modulate these interactions. Evidence in the literature consistently shows that ageing and biofouling enhance WW-MP affinity for many AOCs, reinforcing their function as mobile carriers. However, major gaps persist, including limited data on real wastewater-aged MPs, lack of methodological standardisation, and incomplete representation of ageing, competitive sorption, and non-equilibrium diffusion in existing isotherm and kinetic models. We propose key descriptors that should be incorporated into future sorption and fate frameworks and discuss how WW-MP-AOC interactions may influence ecological exposure, bioavailability, and risk assessment. This critical analysis supports more realistic predictions of AOC behaviour in wastewater environments. Full article

With the advent of new analytical technologies and the urgent environmental problem, reopening investigations into polluting waste matrices becomes a priority. Olive mill wastewater is a pollutant and phytotoxic by-product of olive oil production. An untargeted UHPLC-QTOF analysis of three olive mill wastewaters from three different olive cultivars was performed, and modern informatic platforms were involved to characterize the chemical components in-depth. Data elaboration and statistical analysis confirmed the differences between samples and revealed a total of 364 annotated compounds, including iridoids, phenolic compounds, flavonoids, lignans, cinnamic acid derivatives, and pyrrolidine derivatives. Many of these metabolites, including compounds with known antioxidant and bioactive potential, are scarcely reported in olive products and by-products. The outcomes of this work could be useful for rethinking olive mill wastewater as a source of bioactive compounds to develop and optimize new detoxification strategies. Full article

Phenol, an essential feedstock widely used in manufacturing and chemical industries, inevitably results in the discharge of phenol-laden wastewater. To enhance the phenol-degradation efficiency of Fe-based amorphous alloys, a novel atomic-scale fabrication approach for Fe-Cu galvanic couples is proposed, enabling the rapid and uniform formation of micro/nano Fe-Cu structures on the surface of Fe-based alloys with significant improvement in the catalytic activity towards phenol. Micron/nano Fe-Cu couples can be fabricated within 15 s at 45 °C. Phenol degradation experiments reveal that the pristine amorphous alloy exhibits a 40 min hatching period before the phenol removal process, and it exhibits a kinetic constant (k_obs) of 0.1596 min⁻¹ after the hatching period, under conditions of 50 °C, 0.5 g/L catalytic loading, 10 mmol/L H₂O₂, and pH = 3 towards a 50 mg/L phenol solution. With the micro/nano Fe-Cu galvanic couples, the k_obs value markedly increased to 2.23~2.36 min⁻¹ under identical conditions except for 3 mmol/L H₂O₂, corresponding to approximately a 14-fold improvement. This cost-effective and time-efficient atomic-scale fabrication strategy offers a promising platform for the development of next-generation catalytic alloys and functional materials. Full article

This study looked at a fungal–cyanobacterial co-pellet system for cleaning up coffee waste and producing high-value polymers. Optimization focused on the pelletization process, waste removal efficiency, and biomass yield. Optimal conditions, including pH (6.5), glucose concentration (6 g/L), and shaking speed (130 rpm), achieved a maximum cyanobacterial immobilization efficiency of up to 97% on the fungal mycelium. Scanning electron microscopy (SEM) confirmed the formation of an integrated co-pellet structure, with fungal hyphae acting as a physical scaffold and extracellular polymeric substances (EPSs) enhancing cell–cell adhesion. The co-culture system exhibited superior performance compared to fungal (20.56 g/L) and algal (1.09 g/L) monocultures. It effectively removed major coffee effluent pollutants, achieving a significant reduction in total phenolic compounds (74.5%). Furthermore, the co-pellets displayed a remarkable final biomass yield (24.33 g/L) and high production of extracellular polymeric substances (EPSs) (5.28 g/L) and intracellular polymeric substances (IPSs) (3.84 g/L). The synergistic relationship was further confirmed by high nitrogen contents in the co-pellets (15.24%), which significantly surpassed that of the individual fungal biomass, suggesting interspecies nutrient transfer. Valuable glycerol-lipids were detected and identified in the fermentative broth of the co-culture confirming a highly efficient bioconversion process. Analyses revealed a targeted metabolic flow toward the accumulation of monoglycerides, notably monooleoylglycerol and monopalmitin, highlighting a powerful cooperative compatibility for producing high-value emulsifiers. Overall, these findings firmly establish the cyano-fungal co-pellet system as a robust and sustainable biorefinery approach for treating complex industrial wastewater while producing a high-quality, value-added biomass suitable for utilization as a biofertilizer or animal feed. Full article

Olive mill wastewater (OMW), a by-product of olive oil extraction, poses significant environmental challenges due to its toxicity and heterogeneity. This study evaluates the phenolic and mineral composition of OMW and alpechin sludges from abandoned ponds in Spain, and establishes a standardized conventional method to recover phenolic fractions and promote their safe valorization as bioactive ingredients. Phenolic compounds were identified by triple-TOF-LC-MS/MS, and minerals and heavy metals were quantified by ICP-MS. Across thirteen ponds analyzed, samples from Cordoba, Tarragona, Alicante and Toledo showed higher phenolic levels, ranging from 7.2 g GAE/kg to 18.9 g GAE/kg, with methanolic extracts reaching 10.98–15.67 mg GAE/mL. Thirty-one phenolic compounds were identified, predominantly luteolin, apigenin, quercetin, and secoiridoid derivatives, notably hydroxytyrosol and tyrosol, supporting their functional potential as natural antioxidants. The mineral profile was dominated by K and Ca and showed negligible carryover to the phenolic organic fraction (<1%). Heavy metal concentrations in fresh OMW were 0.32–1.06 µg/kg for Cd and Hg and 9–43.9 µg/kg for As and Pb. In OMW sludge, they ranged between 0.033 and 0.19 mg/kg for Cd, 0.01 and 0.12 mg/kg for Hg, 5.45 and 8.06 mg/kg for As, and 4.45 and 23.70 mg/kg for Pb, whereas phenolic extracts contained only 0.15–21.50 µg/kg, remaining below EU food safety limits. This work presents one of the first integrated approaches to risk-benefit mapping of abandoned ponds in Spanish soils and advances extraction standardization by jointly considering functional potential, contaminant profiles, and matrix location. Full article

Within the framework of sustainability, the parallel valorization of two challenging industrial (crude glycerol) and agricultural (olive mill wastewaters—OMWs) residues by the yeast Yarrowia lipolytica was examined. The rationale of this study was to evaluate the potential of the Y. lipolytica strain ACA-YC 5031 to produce valuable metabolites under a wide range of pH values and increasing NaCl concentrations in agro-industrial blends. OMWs were used as both microbial substrate and process water, and despite high levels of phenolic compounds in the medium and the simultaneously high initial concentrations of NaCl, appreciable quantities of dry cell weight (DCW) and metabolites were synthesized. Moreover, the growth of the strain under non-aseptic conditions was examined. The simultaneous effect of low pH (3.0) and the presence of OMWs (~2.0 g/L) notably increased the extracellular production of erythritol and the accumulation of cellular lipids (reaching Ery_max = 18.3 g/L and DCW = 38.6% w/w, respectively). In media with low pH (3.0) and high NaCl concentration (5.0% w/v), a metabolic shift towards erythritol secretion was observed (Ery_max = 27.2 g/L, with Y_Ery/Glol = 0.46 g/g). Oleic acid accumulation was enhanced by OMW presence in the medium. Full article

The treatment of olive mill wastewater (OMW) remains a major environmental challenge due to its high organic load and phenolic content. This study investigates a combined approach using lime pretreatment and limestone (LS)-based adsorption for cost-effective and sustainable OMW remediation. Locally sourced limestone was used in both micro- and nanoscale forms, while lime (CaO) was produced by calcination. The materials were characterized using X-ray Diffraction pattern (XRD), Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET), and Point of Zero Charge (pH_PZC) analyses to evaluate surface properties relevant to adsorption. Lime pretreatment achieved notable reductions in total suspended solids (TSS, 99%), chemical oxygen demand (COD, 43%), and total phenolic content (TPC, 48%). Subsequent adsorption with nano-limestone (particles obtained through high-energy ball milling, followed by sieving, with a size distribution 400–500 nm) further enhanced pollutant removal, achieving up to 72% COD and 89% TPC reduction in batch experiments. Column studies confirmed the synergistic effect of mixed particle sizes, yielding 65% COD and 76% TPC removal. The combined process demonstrates the potential of lime–limestone composites as locally available and eco-friendly materials for OMW treatment. While promising, the results represent laboratory-scale findings; further optimization and long-term assessments are recommended for field applications. Full article

Phytoremediation is considered as a green alternative for remediating metal-contaminated soil and water, yet further efforts are needed to minimise secondary pollution after phytoremediation. This study investigates a cost-effective and sustainable method to synthesise carbon quantum dot supported on zinc oxide (CQD-ZnO) composites using extracted zinc (Zn) from post-phytoremediated plants, plant extracts, and CQDs derived from water hyacinth (Eichhornia crassipes) for the sonocatalytic degradation of malachite green. The CQD-ZnO materials were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) surface analysis, and ultraviolet–visible (UV–Vis) spectroscopy to confirm their crystalline structure, morphology, functional groups, surface area, and optical properties. The composites exhibited disaggregation of agglomerates, high crystallinity, and increased carbon content due to the addition of CQDs containing phenolic functional groups (e.g., polyphenols, flavonoids) from the plant extract. The highest sonocatalytic degradation efficiency (84.52%) was achieved after 90 min of treating 10 ppm malachite green using 1 g/L of the CQD-ZnO composite at a natural pH, with 300 W ultrasonic power at 25 kHz. This study paves the way for the development of environmentally friendly, high-performance sonocatalysts from post-phytoremediated plants for wastewater treatment applications. Full article