Search Results (213)

Olive mill wastewater (OMWW) is a highly polluting agro-industrial effluent characterized by elevated organic load, low pH, and high concentrations of phenolic compounds responsible for its phytotoxicity and dark coloration. In this study, 41 non-conventional yeast strains belonging to the University of Basilicata Yeast Collection (UBYC), were tested for both the oleaginous potential traits and OMWW detoxification capacity in comparison to two commercial oleaginous controls, Yarrowia lipolytica ATCC 46483 and Lipomyces tetrasporus Li-0407. Primary screening in synthetic medium under nitrogen-limited conditions revealed widespread intracellular lipid accumulation. Quantitative analysis showed lipid contents above 20% (w/w) in some strains, with Candida tropicalis AII122 (33.3%) and Pichia manshurica ML-3 (29.4%) exhibiting the highest values in synthetic medium. The cultivation of eight selected strains in synthetic medium supplemented with 15% (v/v) of OMWW reduced intracellular lipid accumulation, with the highest value of 6.48% for the 2R1 strain. Levels of phenol reduction and color removal were highly different among all the analyzed strains, and C. tropicalis AII122 achieved the highest phenolic reduction and decolorization ability. These findings demonstrate that indigenous non-conventional yeasts represent a source of natural biodiversity, supporting sustainable waste valorization strategies based on the use of selected microorganisms within a circular bioeconomy framework. Full article

Weed management is crucial for the sustainable production of rice (Oryza sativa L.), although herbicides such as Imazamox (IZX) can persist in soils, posing risks to soils and water resources. This two-year study evaluated the effects of soil physicochemical properties under different irrigation and tillage practices, with and without compost derived from olive mill waste, on IZX behavior. The treatments implemented were as follows: no-tillage and sprinkler (NT-S), conventional tillage and sprinkler (T-S), conventional tillage and flooding (T-F), and the corresponding regimes with compost amendment (NT-SC, T-SC, and T-FC). Sorption–desorption, dissipation, and leaching of the herbicide were assessed. The IZX adsorption was lower under soil collected from sprinkler irrigation, especially in NT-S, while compost reduced the adsorption under T-SC and T-FC. Dissipation was faster in NT-S and T-S soils, in which the half-life of IZX declined up to 30% relative to T-F. Furthermore, compost further accelerated herbicide dissipation, correlating with higher organic carbon content and microbial activity. The IZX losses via leaching were significantly reduced in soils irrigated by sprinkler in combination with compost, with values ≤ 48.5% of the IZX applied. These results indicate that the irrigation regime and organic amendment strongly influence soil physicochemical properties, then influencing the environmental fate of IZX. Integrated management using sprinkler irrigation and compost can mitigate IZX persistence and leaching, improve soil health, and reduce the risk of water contamination, representing a sustainable strategy for rice cultivation. Full article

The olive oil extraction industry produces large amounts of olive pomace and wastewater, both of which contain high levels of pollutants. In Albania, olive oil production has increased, while by-product challenges persist. Uncontrolled wastewater discharge and pomace burning have caused environmental issues and inefficient resource use. This study combines published data with field information to examine country pomace utilization and wastewater management. The regional distribution of extraction units and production volumes was analyzed to identify mismatches between processing capacity and output. The findings reveal discrepancies between official statistics and field data. Regional analysis highlights notable imbalances between the number of olive mills and their production volumes, especially in Elbasan, Fier, Vlora, and Berat. Projections, assuming three-phase technology, indicate increased generation of olive pomace and wastewater, thereby raising environmental risks associated with wastewater disposal. The potential for olive pomace oil production was estimated to reach up to 1600 tons. While progress has been made in establishing a pomace oil extraction plant, infrastructure gaps, weak regulation, and limited producer awareness need to be addressed to convert by-products into valuable resources and help Albania’s olive oil sector achieve sustainability goals. Full article

Lignocellulosic biomass is an abundant renewable resource, yet its effective utilization remains limited due to its structural recalcitrance, primarily attributed to lignin. While aerobic lignin-degrading microorganisms, particularly fungi, have been extensively studied, much less is known about bacteria capable of lignin depolymerization under low-oxygen conditions. This study focused on the isolation and evaluation of native anaerobic bacterial cultures capable of degrading lignin-derived compounds to enhance biogas production. Soil samples from decaying vegetation and olive mill wastewater were used as microbial sources. Enriched cultures were developed anaerobically using kraft lignin and p-coumaric acid as sole carbon sources. Twelve pure bacterial strains were isolated and screened for their ligninolytic activity. All strains were able to degrade p-coumaric, with the highest biomass concentration reaching 387 mg L⁻¹ and maximum substrate consumption rate at 438 mg L⁻¹ d⁻¹. When kraft lignin was used as sole carbon source, 9 out of 12 strains showed growth, with a maximum of 55 mg L⁻¹ over 11 days. Enzyme activity assays confirmed the production of lignin peroxidase and laccase, with highest values at 2.10 and 0.15 U mL⁻¹, respectively, even under conditions of limited oxygen. The enriched cultures were applied in biomethane potential (BMP) batch tests, resulting in increased methane production. The best performing culture resulted in a bioaugmentation percentage of 174% compared with control. These findings suggest that native ligninolytic bacteria can serve as promising bioaugmentation agents in anaerobic digestion of lignocellulosic waste. Full article

The purpose of this study was to examine how hydraulic retention time (HRT) influences biohydrogen generation and the formation of end-products during the co-digestion of olive mill wastewater (OMW), cheese whey (CW), and sewage sludge (SS) mixed in a 40:40:20 (v/v/v) ratio. The relationship between the substrates, resulting metabolites, and microbial communities was also explored. Continuous fermentation trials were carried out under both mesophilic (37 °C) and thermophilic conditions using HRTs of 12, 24 and 48 h. Acetic, propionic, and butyric acids were identified as the main end-products. The highest hydrogen production rate (4.4 ± 0.5 L H₂/L_reactor/day) occurred under thermophilic conditions at an HRT of 24 h, whereas under mesophilic operation at the same HRT the hydrogen production reached 3.0 ± 0.3 L H₂/L_reactor/day. In contrast, the greatest accumulation of volatile fatty acids (VFAs) was observed under mesophilic conditions (10.02 g/L), while thermophilic operation at 24 h HRT resulted in 5.54 g/L of total VFAs. The improved performance under thermophilic fermentation is likely linked to the suppression of hydrogen-consuming bacteria at elevated temperatures, which favors rapid hydrogen producers. Microbial community analysis indicated dominance of Firmicutes and persistent Lactobacillus prevalence across conditions. Shorter HRT at 37 °C promoted community diversification with genera such as Olsenella, Dialister, and Prevotella increasing in relative contribution. Under thermophilic operation, consortia remained Lactobacillus-dominant but showed significant temporal restructuring. The predominance of acetic acid (~2.80 g/L) and butyric acid (~2.60 g/L) indicates that hydrogen generation mainly followed the acetic and butyric pathways. This study reveals how targeted control of HRT and temperature can steer microbial communities toward highly hydrogen-productive consortia in the continuous dark fermentation of mixed agro-industrial wastes. Full article

Significant volumes of wastewater and solid by-products are produced by olive oil industries worldwide, posing serious environmental challenges. This study presents an innovative circular economy and environmental sustainability approach that simultaneously valorizes liquid (olive mill wastewater, OMW) and solid by-products (crushed olive pits) rom olive oil production through hydroponic lettuce cultivation. The OMW was pretreated and supplemented with nutrients (OMW-N) to create a hydroponic solution for lettuce (Lactuca sativa) cultivation using crushed olive pits as growing substrate. A hydroponic system fed with a nutritive solution was used as a control. Lettuces grown in the OMW-N system achieved a 100% survival rate with no signs of phytotoxicity, although they exhibited a significant reduction in fresh mass (approx. 66%) and size, compared to the control. The sensory analysis revealed no significant differences in consumer acceptance, except for slightly lower color intensity, with 40% of participants explicitly indicating a purchase preference for the OMW-N lettuce, validating its commercial feasibility. Results demonstrated that OMW-N system functioned as a tertiary treatment, achieving additional removal of nutrients. Overall, integrating treated OMW and olive pits into hydroponics is a feasible strategy to convert agro-industrial waste into value-added food products, reducing the environmental footprint of the olive sector. Full article

The agri-food sector is among the most environmentally impactful industries globally, making its shift toward sustainability a pressing priority. In response, governments—including the EU—are promoting circular economy (CE) principles across all sectors, with CE implementation serving as a key measure of policy effectiveness. The olive oil sector, while economically and culturally vital, poses significant environmental risks due to intensive resource use and problematic waste disposal. Considering resource scarcity and climate change, CE adoption—grounded in industrial ecology—is increasingly relevant. This study investigates the implementation of CE practices in Greek olive oil mills (OOMs) by evaluating the degree of circularity through tailored indicators and conducting a techno-economic analysis (TEA) of selected practices. Together, these methods offer a robust, quantitative assessment of the environmental and financial sustainability of CE initiatives within the olive oil industry. Full article

There is an urgent need to develop sustainable approaches for the remediation of contaminated soil as well as to promote sustainable practices for waste management. Here, we provide the first evaluation of the performance of two types of iron nanoparticles (NA and NH) obtained from olive mill wastewater for the remediation of an acidic multi-contaminated soil, including metal(loid)s, PCBs, and a flame retardant (TCPP). Their efficiency was then compared against that of a commercial nanoscale zero-valent iron (NS) through a one-month microcosm experiment employing two doses of each nanomaterial. The impact of the treatments on key soil physicochemical properties, metal(loid) availability, PCB and TCPP concentrations, and soil phytotoxicity was assessed. All treatments reduced soil acidity. Regarding organic contaminants, bioremediation of TCPP was enhanced by all nanomaterials, particularly NH, whereas NA was the only treatment that significantly reduced PCB concentration under the tested conditions. NS achieved the highest rates of metal(loid) immobilization (63–100%); NH was most beneficial for soil fertility and immobilized As, Ni, and Pb (100, 38, and 53%, respectively), whereas NA was only effective for Pb (21–49%). The low dose of both NA and NH improved the germination index (66 and 61%, respectively), reducing soil phytotoxicity. These results highlight the potential of valorizing olive mill wastewater for soil remediation, thereby contributing to the principles of the Circular Economy. Full article

Waste valorisation has become a key strategy for applying circular economy principles in the agro-industrial field. This study investigated the territorial implementation of the waste composting on a territorial scale. The wastes considered were the post-processing orange waste, spent olive oil pomace, and spent wine grape pomace. Their potential use as soil amendments across the provinces of Sicily was assessed through a GIS-based analysis, taking into account nitrogen (N) application constraints. Moreover, a cascade valorisation scheme was also evaluated: post-processing orange waste was first used as animal feed, and the remaining fraction was directed to composting; olive pomace was first sent to pomace oil extraction mills, and the residual material was subsequently used for composting. Results indicate that N inputs derived from composted residues remain below legal thresholds in all provinces, with relative contributions ranging from 38% to 92% of the regulatory limits. Spatial variability in nitrogen availability reflects the territorial distribution of agro-industrial activities, highlighting the importance of localised management strategies. These findings demonstrate that composting, combined with cascade valorisation, is an effective pathway to close nutrient cycles, reduce waste generation, and support sustainable biomass management in regional agri-food systems. 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

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

The excessive use of synthetic fertilizers in agriculture has raised environmental concerns, prompting the search for sustainable alternatives, such as organic amendments. This study evaluated the agronomic performance, nutrient use efficiency and metabolomic profiles of lettuce (Lactuca sativa L. var. baby leaf) cultivated using synthetic and organic (olive mill waste-based compost pellets and sewage sludge) in a controlled pot experiment. The treatments included three doses of inorganic fertilizer and two organic fertilizers applied at equivalent nitrogen (N) rates, alongside an unfertilized control. Soil physicochemical properties, plant biomass, nutrient uptake and metabolite profiles, including amino acids, sugars and organic acids, were analyzed. Inorganic fertilization rapidly increased soil mineral N and phosphorus (P), enhancing leaf chlorophyll, canopy development and fresh biomass, and promoting the accumulation of reducing sugars (p < 0.05). However, it reduced amino acid and phenolic levels, indicating a metabolic shift towards growth at the expense of stress and antioxidant compounds. Sewage sludge increased soil organic matter and amino acid and sucrose accumulation, but also induced stress-related metabolites. Pelletized compost maintained an intermediate level of nutrient availability, preserved phenolic compounds and improved phosphorus use efficiency. This surpassed the results achieved with sewage sludge in terms of dry matter yield, despite limited short-term growth stimulation. These findings highlight the potential of integrating moderate mineral fertilization with pelletized compost to balance immediate productivity, nutrient efficiency and long-term soil and metabolic quality in lettuce cultivation. Full article

Mesophilic anaerobic co-digestion of eight distinct substrate mixtures of agroindustrial and food wastes was assessed to determine the most efficient waste mixture for maximizing hydrogen production. To evaluate the impact of adding various mixtures on dark fermentation (DF), batch tests were conducted for 250 h at 37 °C and a pH range between 5.0 and 5.9. Ethanol, butyric, propionic, acetic, and isobutyric acids were identified as the principal fermentation end products. The hydrogen production rate reached in a decreasing order from a mixture comprising 55% Olive Mill Wastewater (OMW), 40% Cheese Whey (CW), and 5% Sewage Sludge (SS) or Liquid Pig Manure (LPM) (38 NmL/gVS) to 55% OMW, 40% CW and 5% diluted Food Waste (FW_dil) (30 NmL/gVS), 60% CW and 40% Grape Residues (GR) (27 NmL/gVS), 80% CW and 20% LPM (13 NmL/gVS), 60% OMW and 40% FW_dil. (10 NmL/gVS), 60% CW and 40% FW_dil, (8 NmL/gVS) and 70% OMW and 30% SS (5 NmL/gVS). These results indicated that H₂ was generated through mixed fermentation pathways, while the addition of OMW > 55% inhibited microbial activity and reduced hydrogen production. The highest hydrogen yield (38 NmL/gVS), accompanied by 27.6%, Volatile Solids (VS) reduction and the highest Volatile Fatty Acids (VFAs) concentration (6.1 g/L). The same substrate mixture resulted in the highest accumulation of acetic and butyric acid in the acidified effluent, indicating the dominance of hydrogen-producing metabolic routes. The data suggest that co-fermentation of the selected residues not only enhances hydrogen production but also creates more stable operational conditions -including improved pH regulation, increased carbohydrate conversion, and greater VFAs accumulation- making the process more robust and viable for practical application. Full article

Ethanol stress profoundly affects yeast metabolism, yet its integrated impact on lipase activity and lipid remodeling in Yarrowia lipolytica remains unexplored. Here, we investigated, for the first time, the combined effects of ethanol-induced stress on lipase production and fatty acid profiles in Y. lipolytica cultivated on two hydrophobic substrates: olive mill wastewater (OMW) and Waste Frying Oil (WFO). Ethanol was applied at increasing concentrations (3%, 5%, and 7% v/v), and the physiological responses were monitored over time (48, 72, and 96 h). Our results reveal a substrate-dependent and dose-dependent response to ethanol. Lipase activity was significantly enhanced at 5% ethanol, reaching 0.55 ± 0.11 U/mL in the OMW medium after 48 h. In comparison, mild stress (3%) induced the de novo synthesis of C20:1 (eicosenoic acid) and C20:2 (eicosadienoic acid), indicating reprogramming of lipid biosynthetic pathways. Oxidative stability, assessed by pressurized differential scanning calorimetry (PDSC), markedly improved in OMW-derived lipids, with τ_on increasing from 30.48 ± 0.80 to 47.07 ± 3.92 min and τ_max from 35.73 ± 0.62 to 54.04 ± 1.99 min under 3% ethanol. Conversely, WFO-derived samples exhibited lower oxidative stability and less pronounced changes in lipid composition. These findings demonstrate that Y. lipolytica adapts its lipid metabolism differently depending on the substrate, and that controlled ethanol exposure can enhance both lipase secretion and lipid oxidative resistance, underscoring its potential as a robust biocatalyst for sustainable biorefineries and the valorization of agro-food oil wastes. Full article

The growing accumulation of non-biodegradable petrochemical plastics and increasing food waste present urgent environmental and public health challenges. This study addresses both issues by developing biodegradable food packaging films from agar and starch, enhanced with antimicrobial properties by incorporating silver nanoparticles. The innovation of this work is the synthesis of novel agar–starch–silver nanoparticle coatings, where the contained nanoparticles were produced via green methods using two agro-industrial by-products of Greek olive oil production—olive stone extract and olive mill wastewater—as reducing agents. The morphology of the novel coatings was confirmed using transmission electron microscopy combined with energy-dispersive X-ray spectroscopy, revealing nanoscale particles with variable sizes. Additional film characterization was performed through Fourier-transform infrared spectroscopy, scanning electron microscopy coupled with energy-dispersive spectroscopy, and surface profilometry. Infrared spectroscopy analysis suggested the presence of functional groups responsible for nanoparticle stabilization, while energy-dispersive X-ray spectroscopy revealed silver aggregation in both olive stone extract and olive mill wastewater-derived films. Profilometry showed that films with olive mill wastewater-based nanoparticles had a rougher surface than those synthesized from olive stone extract. Antibacterial efficacy was tested against Escherichia coli (Gram-negative) and Staphylococcus epidermidis (Gram-positive) using a spot-on-film assay with high (10⁶ CFU/film) and low (10³ CFU/film) bacterial loads. After 72 h of incubation at 4 °C, both film types showed strong antibacterial activity at high bacterial concentrations, demonstrating their potential for active food packaging. These findings highlight a promising approach to sustainable food packaging within the circular economy, utilizing agricultural waste to create biodegradable materials with effective antimicrobial functionality. Full article