Search Results (490)

The dairy industry generates significant amounts of wastewater, including microfiltration (MF) retentate, a byproduct thickened with organic and inorganic pollutants. This study focuses on the treatment of two times concentrated MF retentate using a hybrid system based on biological treatment in a sequential batch reactor (SBR) and adsorption on activated carbon. The first stage involved cross-flow microfiltration using a 0.2 µm PVDF membrane at 0.5 bar, resulting in reductions of 99% in turbidity and 79% in chemical oxygen demand (COD), as well as a partial reduction in conductivity. The second stage involved 24-h biological treatment in a sequential batch reactor (SBR) with activated sludge (activated sludge index: 80 cm³/g, MLSS 2500 mg/dm³), resulting in further reductions in COD (62%) and TOC (30%), as well as the removal of 46% of total phosphorus (TP) and 35% of total nitrogen (TN). In the third stage, the decantate underwent adsorption in a column containing powdered activated carbon (PAC; 1 g; S_(BET) = 969 m² g⁻¹), reducing the concentrations of key indicators to the following levels: COD 84%, TOC 70%, TN 77%, TP 87% and suspended solids 97%. Total pollutant retention ranged from 24.6% to 97.0%. These results confirm that the MF–SBR–PAC system is an effective, compact solution that significantly reduces the load of organic and biogenic pollutants in MF retentates, paving the way for their reuse or safe discharge into the environment. Full article

Per- and polyfluoroalkyl substances (PFAS) are synthetically produced chemicals that are causing a major One Health crisis. These “forever chemicals” are widely distributed globally in air, water, and soil, and because they are highly mobile and extremely difficult to degrade in the environment. They cause additional health concerns in a circular bioeconomy and food system that recycles and reuses by-products and numerous types of waste materials. Uptake of PFAS by plants and food-producing animals ultimately leads to the consumption of PFAS-contaminated food that is associated with numerous adverse health and developmental effects in humans. Contaminated meat, milk, and eggs are some of the main sources of human PFAS exposure. Although there is no safe level of PFAS exposure, maximum tolerable PFAS consumption guidelines have been established for some countries. However, there is no international PFAS monitoring system, and there are no standardized international guidelines and mechanisms to prevent the consumption of PFAS-contaminated foods. Urgent action is needed to stop PFAS production except for critical uses, implementing effective water-purification treatments, preventing spreading sewage sludge on land and pastures used to produce food, and requiring marketers and manufacturers to use packaging that is free of PFAS. Full article

Alperujo, a solid by-product from the two-phase olive oil extraction process, poses significant environmental challenges due to its high organic load, phytotoxicity, and phenolic content. At the same time, it represents a promising feedstock for recovering value-added compounds such as phenols and volatile fatty acids (VFAs). When used as a substrate for white rot fungi (WRF), it also produces ligninolytic enzymes. This study explores the use of two native WRF, Anthracophyllum discolor and Stereum hirsutum, for the biotransformation of alperujo under solid-state fermentation conditions, with and without supplementation of copper and manganese, two cofactors known to enhance fungal enzymatic activity. S. hirsutum stood out for its ability to release high concentrations of phenolic compounds (up to 6001 ± 236 mg gallic acid eq L⁻¹) and VFAs (up to 1627 ± 325 mg L⁻¹) into the aqueous extract, particularly with metal supplementation. In contrast, A. discolor was more effective in degrading phenolic compounds within the solid matrix, achieving a 41% reduction over a 30-day period. However, its ability to accumulate phenolics and VFAs in the extract was limited. Both WRF exhibited increased enzymatic activities (particularly Laccase and Manganese Peroxidase) with the addition of Cu-Mn, highlighting the potential of the aqueous extract as a natural source of biocatalysts. Phytotoxicity assays using Solanum lycopersicum seeds confirmed a partial detoxification of the treated alperujo. However, none of the fungi could entirely eliminate inhibitory effects on their own, suggesting the need for complementary stabilization steps before agricultural reuse. Overall, the results indicate that S. hirsutum, especially when combined with metal supplementation, is better suited for valorizing alperujo through the recovery of bioactive compounds. Meanwhile, A. discolor may be more suitable for detoxifying the solid phase strategies. These findings support the integration of fungal pretreatment into biorefinery schemes that valorize agroindustrial residues while mitigating environmental issues. Full article

Gasification of municipal solid waste and other biogenic residues (e.g., biomass and biowaste) is increasingly recognized as a promising thermochemical pathway for converting non-recyclable fractions into valuable energy carriers, with applications in electricity generation, district heating, hydrogen production, and synthetic fuels. This paper provides a comprehensive analysis of major gasification technologies, including fixed bed, fluidized bed, entrained flow, plasma, supercritical water, microwave-assisted, high-temperature steam, and rotary kiln systems. Key aspects such as feedstock compatibility, operating parameters, technology readiness level, and integration within circular economy frameworks are critically evaluated. A comparative assessment of incineration and pyrolysis highlights the environmental and energetic advantages of gasification. The valorization pathways for main product (syngas) and by-products (syngas, ash, tar, and biochar) are also explored, emphasizing their reuse in environmental, agricultural, and industrial applications. Despite progress, large-scale adoption in Europe is constrained by economic, legislative, and technical barriers. Future research should prioritize scaling emerging systems, optimizing by-product recovery, and improving integration with carbon capture and circular energy infrastructures. Supported by recent European policy frameworks, gasification is positioned to play a key role in sustainable waste-to-energy strategies, biomass valorization, and the transition to a low-emission economy. Full article

Origanum majorana L. (O. majorana) (Lamiaceae) is an aromatic Mediterranean plant widely used in food, cosmetics, and traditional medicine due to its aroma and rich content of bioactive compounds. While its leaves and flowers are commonly utilized, lignified stems are often discarded. This study compared hydroalcoholic extracts from the leaves and flowers (valuable fraction, VF) and stems (by-product, BP). Phytochemical analysis revealed qualitatively similar profiles, identifying 20 phenolic compounds, with Rosmarinic acid and Salvianolic acid B as the most and second most abundant, respectively. Antioxidant activity was evaluated in vitro using DPPH (IC₅₀ [µg/mL]: VF 30.11 ± 3.46; BP 31.72 ± 1.46), H₂O₂ (IC₅₀ [µg/mL]: VF 103.09 ± 4.97; BP 119.55 ± 10.58), and O₂^•− (IC₅₀ [µg/mL]: VF 0.71 ± 0.062; BP 0.79 ± 0.070). Both extracts (20 µg/mL) fully restored oxidative balance in hemin-stressed AC16 cardiomyocytes, without altering the expression of catalase, heme-oxygenase 1, superoxide dismutase 2, or ferritin. Anti-inflammatory activity in LPS-stimulated RAW 264.7 macrophages showed that VF (IC₅₀ 400 µg/mL) reduced ^•NO release to control levels, while BP achieved a ~60% reduction. Cytotoxicity was assessed on cancer cell lines: CaCo-2 (IC₅₀ [µg/mL]: VF 154.1 ± 6.22; BP 305.2 ± 15.94), MCF-7 (IC₅₀ [µg/mL]: VF 624.6 ± 10.27; BP 917.9 ± 9.87), and A549 (IC₅₀ [µg/mL]: VF 720.8 ± 13.66; BP 920.2 ± 16.79), with no cytotoxicity on normal fibroblasts HFF-1 (IC₅₀ > 1000 µg/mL for both extracts). Finally, both extracts slightly inhibited only CYP1A2 (IC₅₀ [µg/mL]: VF 497.45 ± 9.64; BP 719.72 ± 11.37) and CYP2D6 (IC₅₀ [µg/mL]: VF 637.15 ± 14.78, BP 588.70 ± 11.01). These results support the potential reuse of O. majorana stems as a sustainable source of bioactive compounds for nutraceutical and health-related applications. Full article

White-light-emitting diodes (wLEDs) are central to next-generation lighting technologies, yet their reliance on critical raw materials (CRMs), such as rare-earth elements, raises concerns regarding sustainability and supply security. In this work, we present a simple, low-cost method to produce photoluminescent carbon-based nanostructures—known as oxidative debris (OD)—via alkaline treatment of graphene oxide (GO) using KOH solutions ranging from 0.04 M to 1.78 M. The resulting OD, isolated from the supernatant after acid precipitation, exhibits strong and tunable photoluminescence (PL) across the visible spectrum. Emission peaks shift from blue (~440 nm) to green (~500 nm) and yellow (~565 nm) as a function of treatment conditions, with excitation wavelengths between 300 and 390 nm. Optical, morphological. and compositional analyses were performed using UV-Vis, AFM, FTIR, and Raman spectroscopy, confirming the presence of highly oxidized aromatic domains. The blue-emitting (S2) and green/yellow-emitting (R2) fractions were successfully separated and characterized, demonstrating potential color tuning by adjusting KOH concentration and treatment time. This study highlights the feasibility of reusing GO-derived byproducts as sustainable phosphor alternatives in wLEDs, reducing reliance on CRMs and aligning with green chemistry principles. Full article

The transition toward a circular water economy addresses accelerating water scarcity and pollution. A PRISMA-2020 systematic review of 50 peer-reviewed articles (January 2018–April 2024) mapped current technologies and management strategies, seeking patterns, barriers, and critical bottlenecks. Bibliometric analysis revealed the following three dominant patterns: (i) rapid diffusion of membrane bioreactors, constructed wetlands, and advanced oxidation processes; (ii) research geographically concentrated in Asia and the European Union; (iii) industry’s marked preference for by-product valorization. Key barriers—high energy costs, fragmented regulatory frameworks, and low social acceptance—converge as critical constraints during scale-up. The following three practical action lines emerge: (1) adopt progressive tariffs and targeted tax credits that internalize environmental externalities; (2) harmonize water-reuse regulations with comparable circularity metrics; (3) create multi-actor platforms that co-design projects, boosting local legitimacy. These findings provide policymakers and water-sector practitioners with a clear roadmap for accelerating Sustainable Development Goals 6, 9, and 12 through circular, inclusive, low-carbon water systems. Full article

Mining by-products present both an environmental challenge and a resource opportunity. This review investigates their potential application in road pavement construction, focusing on materials such as fly ash, slag, sulphur, red mud, tailings, and silica fume. Drawing from laboratory and field studies, the review examines their roles across pavement layers—subgrade, base, subbase, asphalt mixtures, and rigid pavements—emphasising mechanical properties, durability, moisture resistance, and ageing performance. When properly processed or stabilised, many of these wastes meet or exceed conventional performance standards, contributing to reduced use of virgin materials and greenhouse gas emissions. However, issues such as variability in composition, leaching risks, and a lack of standardised design protocols remain barriers to adoption. This review aims to consolidate current research, evaluate practical feasibility, and identify directions for future studies that would enable the responsible and effective reuse of mining waste in transportation infrastructure. Full article

Establishing a sustainable production system requires a more efficient utilization of resources and the adoption of cleaner production methodologies. Specifically, industrial symbiosis promotes collaboration among interconnected industries by exchanging waste, byproducts, and utilities, thereby providing innovative ways to enhance the efficiency of production processes. However, the sustainability of agricultural products and agro-based industries is essential for human survival. This study proposed an integrated symbiotic production system that targets agro-based industries. The system includes seven plants: a sugar production plant, a corn-integrated industrial plant, an alcohol production plant, a feed production plant, a fertilizer plant, a bioethanol production plant, and a wastewater treatment plant. The study aimed to design a sustainable industrial system that shares byproducts, waste, and water reuse. Symbiotic relations between production plants are designed in a provided multi-objective optimization model that considers both the mitigation of CO₂ emissions and the maximization of system profit. The multi-objective model with the epsilon-constraint method results in Pareto-efficient solutions that address the tradeoff between the objectives. This allows decision makers to select a suitable one among the solution set that prioritizes conflicting objectives. We developed ten scenarios to assess costs, revenue, profit, and CO₂ emissions, offering significant insights into how model parameters affect managerial knowledge. This study also addresses environmental and economic concerns, thereby making the development of agro-based industries more sustainable. Full article

Spice by-products, often discarded as waste, represent an untapped resource for sustainable packaging solutions due to their unique, multifunctional, and bioactive profiles. Unlike typical plant residues, these materials retain diverse phytochemicals—including phenolics, polysaccharides, and other compounds, such as essential oils and vitamins—that exhibit controlled release antimicrobial and antioxidant effects with environmental responsiveness to pH, humidity, and temperature changes. Their distinctive advantage is in preserving volatile bioactives, demonstrating enzyme-inhibiting properties, and maintaining thermal stability during processing. This review encompasses a comprehensive characterization of phytochemicals, an assessment of the re-utilization pathway from waste to active materials, and an investigation of processing methods for transforming by-products into films, coatings, and nanoemulsions through green extraction and packaging film development technologies. It also involves the evaluation of their mechanical strength, barrier performance, controlled release mechanism behavior, and effectiveness of food preservation. Key findings demonstrate that ginger and onion residues significantly enhance antioxidant and antimicrobial properties due to high phenolic acid and sulfur-containing compound concentrations, while cinnamon and garlic waste effectively improve mechanical strength and barrier attributes owing to their dense fiber matrix and bioactive aldehyde content. However, re-using these residues faces challenges, including the long-term storage stability of certain bioactive compounds, mechanical durability during scale-up, natural variability that affects standardization, and cost competitiveness with conventional packaging. Innovative solutions, including encapsulation, nano-reinforcement strategies, intelligent polymeric systems, and agro-biorefinery approaches, show promise for overcoming these barriers. By utilizing these spice by-products, the packaging industry can advance toward a circular bio-economy, depending less on traditional plastics and promoting environmental sustainability in light of growing global population and urbanization trends. Full article

Reprocessing lignocellulosic waste to obtain new products for industrial purposes is a vital part of circular economy. This paper reports the cellulase production by newly isolated Bacillus methylotrophicus cultured on lignocellulosic agro-industrial by-products, out of which brewer’s spent grain (BSG) was selected as most beneficial. Plackett–Burman design was used for screening medium components, while Box–Behnken design was further applied to model the impact of the three most influential variables. The maximum approximated cellulase activity was 0.469 U/mL (1 U = 1 µmol of reducing sugars/1 min), at 48.6 g/L substrate, 5.3 g/L ammonium sulfate, pH 6.1. The partially purified cellulase was characterized, which demonstrated broad range of optimal pH (6.5–9.4), temperature (50–60 °C), and sensitivity to metals. Changes in lignin and pentosans content was demonstrated as a result of BSG hydrolysis with a cell-free cellulase preparation. The produced enzyme was used for hydrolysis of various chemically pretreated (NaOH and H₂SO₄) cellulosic substrates, where for reused alkali-pretreated BSG (after microbial enzyme production) the saccharification efficiency was at a level of 25%. The cellulolytic potential of the bacterial strain, along with its resistance to ethanol, present a beneficial combination, potentially applicable to aid saccharification of lignocellulosic by-products for biofuel production. Full article

Multifunctional water-treatment materials urgently need to be developed to avoid normal organic matter, inorganic anions, resistant bacteria, and hazardous disinfection by-products in conventional drinking water treatment strategies. While quaternary ammonium pyridine resins (QAPRs) possess porous adsorption structures and incorporate antibacterial groups, enabling simultaneous water disinfection and purification, their limited bactericidal efficacy hinders broader utilization. Therefore, a deeper understanding of the structure-dependent antimicrobial mechanism in QAPRs is crucial for improving their antibacterial performance. Hexyl (C₆) was proved to be the optimal antibacterial alkyl in the QAPRs. A new antibacterial quaternary ammonium pyridine resin Py-61 was prepared by more surficial bactericidal N⁺ groups and higher efficient antibacterial hexyl, performing with the excellent antibacterial efficiency of 99.995%, far higher than the traditional resin Py-6C (89.53%). The antibacterial resin Py-61 completed the disinfection of sand-filtered water independently to produce safe drinking water, removing the viable bacteria from 3600 to 17 CFU/mL, which meets the drinking water standard of China in GB5749-2022 (<100 CFU/mL). Meanwhile, the contaminants in sand-filtered water were obviously removed by the resin Py-61, including anions and dissolved organic matter (DOM). The resin Py-61 can be regenerated by 15% NaCl solution, and keeps the reused antibacterial efficiency of >99.97%. As an integrated disinfection–purification solution, the novel antibacterial resin presents a promising alternative for enhancing safety in drinking water treatment. Full article

Wine production generates by-products that require proper management and reuse to minimize their environmental impact. Grape pomace, a by-product of winemaking, holds significant nutritional and bioactive potential. This study evaluated the nutritional and antioxidant profiles of pomace from Isabella grapes (La Plata, Argentina) and Cabernet grapes (Veneto, Italy). Both varieties contain high levels of dietary fiber, especially Cabernet. However, Cabernet showed lower protein and lipid levels than Isabella. Calcium, potassium, and phosphorus were the major minerals in both by-products. Isabella exhibited a higher content of essential polyunsaturated fatty acids, particularly α-linoleic acid, while Cabernet shows a greater proportion of saturated and monounsaturated fatty acids. Additionally, Isabella exhibited significantly higher levels of caffeic acid derivatives (506.4 vs. 38.2 mg/kg dry weight), catechin (1613.2 vs. 294.8 mg/kg dry weight), epicatechin (1229.2 vs. 230.3 mg/kg dry weight), and total anthocyanins (2649 vs. 607.5 mg kuromanin/kg dry weight), as well as a greater total polyphenol content and antioxidant activity compared to Cabernet. These results highlight grape pomace’s potential as a valuable functional ingredient. Full article

This study focuses on the design and optimization of a monopolar electrode configuration for the hybrid electrochemical treatment of real washing machine wastewater. A combined electrocoagulation (EC) and electro-oxidation (EO) system was optimized to maximize pollutant removal efficiency while minimizing energy consumption. The monopolar setup employed mixed metal oxide (MMO) and aluminum anodes, along with a stainless steel cathode, operating under controlled conditions with sodium chloride as the supporting electrolyte. An applied current density of 15 mA cm⁻² achieved 90% chemical oxygen demand (COD) removal, 98% surfactant degradation, complete turbidity reduction within 120 min, and pH stabilization near 8. Additionally, electrochemical disinfection achieved <2 MPN/100 mL, with no detectable phenols and the presence of organic anions such as oxalate and acetate. These results demonstrate the effectiveness of an optimized monopolar EC–EO system as a cost-efficient and sustainable strategy for wastewater treatment and potential water reuse. Further studies should focus on refining energy consumption and monitoring reaction by-products to enhance large-scale applicability. Full article

The storage of highly alkaline red mud (RM) consumes land and threatens the environment, making its reuse crucial. The study used calcium carbide slag to dealkalize it, and analyzed the changes in mineral particles in RM using a CT scan. It then evaluated the stabilization effects of different materials and explored the mechanism of RM solidification through analysis of micro-mechanisms. The results showed that after dealkalization with CCS, RM particles form more agglomerates and the overall structure becomes more compact, and the Na⁺ content in RM decreased from 10.44 wt% to 0.86 wt%. After treatment with stabilization materials, the mechanical strength of low-alkalinity RM was greatly improved, and the stabilization effect of composite slag was the best. When the partial replacement ratio was 12%, the 28 d compressive strength was 4.51 MPa. After soaking in water for one day and night, the strength decreased by 24.3%, which had good stability. This study found that the strength gains were mainly due to crystal substances like Ca₃Al₂O₆ and non-crystalline substances such as C-S-H filling pores and wrapping particles. This study provides a new method for RM stabilization and promotes the utilization of industrial by-products. Full article