Search Results (66)

Palm oil mill effluent (POME), a byproduct of palm oil processing, has substantial resource recovery potential. Its rich biodegradable content supports methane (CH₄) production via anaerobic digestion, enabling renewable energy generation. Additionally, the significant water content of POME can be reclaimed for use in boiler feed, irrigation, and drinking water. However, selecting appropriate technologies to recover valuable resources from POME is challenging, particularly for the purification and upgrading of biogas. Membrane technologies offer an effective approach for transforming POME treatment from an energy-intensive process into a resource recovery system, supporting the decarbonization of palm oil production and advancing global sustainability objectives. This technique is cost-effective and ecofriendly for biogas purification and water reclamation. For biogas purification and upgrading, membrane systems offer the lowest capital and operational costs at 5.654 USD/m³, compared to other technologies, such as 6.249 USD/m³ for water scrubbers and 6.999 USD/m³ for chemical absorbers. This review primarily explores the potential of membranes for gas purification from POME and examines their integration with other processes to develop advanced systems, such as ultrasonicated membrane anaerobic systems and membrane anaerobic systems, to enhance biogas production. In addition, water reclamation from POME is discussed, with ultrafiltration membranes emerging as the most promising candidates. Proton exchange membranes, such as Nafion, are used extensively in microbial fuel cells to improve electricity generation, and this is also summarized. Finally, challenges and future perspectives are highlighted, emphasizing the broader potential of membrane technology in POME wastewater resource recovery. Full article

The selective chlorination of ethane to 1,2-dichloroethane offers a promising route for upgrading ethane, yet its efficiency remains constrained by limited mechanistic insights into gas-phase chlorine-radical-mediated pathways, which govern target product selectivity and competing dehydrochlorination side reactions. This work systematically decouples the kinetics of ethane chlorination and chloroethane functionalization under varying Cl₂ concentrations, revealing that chlorine radicals govern product distribution through thermodynamically favored pathways. This results in an interesting phenomenon whereby the product ratio between 1,1-C₂H₄Cl₂ and 1,2-C₂H₄Cl₂ maintains a constant 2:1 stoichiometry regardless of Cl₂ concentration variation. A critical observation is that the rate of all chlorination steps remains independent of alkane concentrations, highlighting the dominant role of chlorine radicals in rate-determining steps. Furthermore, ethylene byproducts are demonstrated to originate from the dechlorination of chlorine-radical-induced 2-chloroethyl radicals derived from chloroethane, rather than the direct dehydrochlorination of chloroethane itself. These insights into the dual role of chlorine radicals—mediating both the chlorination and dehydrochlorination pathways—establish a foundational framework for integrating gas-phase radical chemistry with catalytic engineering strategies to suppress undesired side reactions and enable scalable, selective ethane chlorination. Full article

In the face of acute water scarcity and sanitation challenges emblematic of arid and semi-arid regions (ASARs), this study investigated the transformative upgrade of the Aqaba Conventional Activated Sludge Wastewater Treatment Plant (CAS-AWWTP) in Jordan. The project, expanding capacity to 40,000 m³/day, integrated sustainable features including renewable energy and repurposed natural treatment ponds functioning as artificial wetlands. The plant’s treatment performance, byproduct valorization, and alignment with sustainable development goals (SDGs) were assessed. Comparative analysis revealed that the upgraded CAS-AWWTP consistently outperforms the previous natural and extended activated sludge systems. CAS-AWWTP average removal efficiencies of BOD₅, COD, TSS, and T-N were 99.1%, 96.6%, 98.7%, and 95.1%, respectively, achieving stringent reuse standards and supplying approximately 30% of Aqaba Governorate’s annual water budget, thus conserving freshwater for domestic use. Furthermore, the plant achieved 44% electrical self-sufficiency through renewable energy integration, significantly reducing its carbon footprint. The creation of artificial wetlands transformed the site into a vital ecological habitat, attracting over 270 bird species and becoming a popular destination for birdwatching enthusiasts, drawing over 10,000 visitors annually. This transformation underscores the plant’s dual role in wastewater treatment and environmental conservation. The AWWTP upgrade exemplifies a holistic approach to sustainable development, impacting multiple SDGs. Beyond improving sanitation (SDG 6), it enhances water reuse for agriculture and industry (SDG 6.4, 9.4), promotes renewable energy (SDG 7), stimulates economic growth (SDG 8), strengthens urban sustainability (SDG 11), fosters resource efficiency (SDG 12), and supports biodiversity (SDG 14/15). The project’s success, facilitated by multi-stakeholder partnerships (SDG 17), provides a replicable model for water-scarce regions seeking sustainable wastewater management solutions. Full article

The valorization of agricultural and industrial solid by-products as secondary resources in the development of value-added materials can contribute to environmental health protection, particularly in the climate change era. Current advances in environmental legislation also encourage manufacturers to optimize waste management, upgrading and utilization towards resource conservation, energy efficiency and cost reduction in the context of a circular economy. In the present research, the elaboration of novel sustainable ceramics is investigated by sintering (at 800 °C for 2 or 6 h) of compacted mixtures composed of lignite fly ashes along with biomass ash (olive kernel ash) at different proportions. It appears that the chemical, mineralogical and morphological characteristics of these by-products promote their use as starting materials in ceramic engineering. Characterization and evaluation of the ceramics obtained via XRD and SEM-EDX analysis, as well as Vickers microhardness measurements, confirm the effectiveness of the consolidation process. In fact, the material derived from an 85% Class-C fly ash and 15% biomass ash compact, after 6 h sintering, exhibited greater results in terms of ceramic microstructure and microhardness (380 Hv), while a sintering time of 2 h was barely acceptable. The materials developed can be considered for use in various applications. Full article

Spent coffee ground (SCG) is a main byproduct of the coffee industry and has been revalorized as a source of value-added products. The direct application of SCG as a soil amendment has drawn much attention in recent years as a more environmentally sustainable option. In this work, a comprehensive review of studies on the agricultural application of SCG is presented. The aims of this review were (1) to summarize the impacts of raw SCG on soil health and to identify the factors limiting its direct soil use, (2) to outline methods that are often used to upgrade SCG for soil application, and (3) to highlight the potential of SCG and its derivatives as a biocontrol agent and biofertilizer. The results indicate that raw SCG could improve certain soil health attributes, but plant growth is often limited owing to its phytotoxicity and induced N immobilization. To eliminate phytotoxicity, composting, vermicomposting, and thermochemical treatments have been employed but to a limited extent. SCG and its derivatives may be used as biocontrol agents for weeds, soil-borne pathogens, and pests. Novel bio-organic fertilizers based on SCG have also been developed. Future research should focus on the long-term effects of SCG and its derivatives as soil amendments under real scenarios and the underlying mechanisms, particularly the soil–plant–microorganism interactions. Full article

The growing concern over water pollution and waste management requires innovative solutions that promote resource efficiency within a circular economy. This study aims to utilize rice husk (RH) as a sustainable feedstock to develop highly porous silica particles and generate valuable by-products, addressing the dual challenges of waste reduction and water contamination. We hypothesize that optimizing the production of amorphous silica from acid-washed RH will enhance its adsorptive properties and facilitate the concurrent generation of bio-oil and syngas. Amorphous silica particles were extracted from acid-washed RH with a yield of 15 wt% using a combination of acid washing at 100 °C, pyrolysis at 500 °C, and calcination at 700 °C with controlled heating at 2 °C/min. The optimized material (RH2-SiO₂), composed of small (60–200 nm) and large (50–200 µm) particles, had a specific surface area of 320 m²/g, with funnel-shaped pores with diameters from 17 nm to 4 nm and showed a maximum cadmium adsorption capacity of 407 mg Cd/g SiO₂. Additionally, the pyrolysis process yielded CO-rich syngas and bio-oil with an elevated phenolic content, demonstrating a higher bio-oil yield and reduced gas production compared to untreated RH. Some limitations were identified, including the need for bio-oil upgrading, further research into the application of RH2-SiO₂ for wastewater treatment, and the scaling-up of adsorbent production. Despite the challenges, these results contribute to the development of a promising adsorbent for water pollution control while enhancing the value of agricultural waste and moving closer to a circular economy model. Full article

The depletion of conventional light petroleum reserves has intensified the search for alternative sources, notably, low-quality heavy oils and byproducts from heavy crude processing, to meet the global demand for fuels, energy, and petrochemicals. Heavy crude oil (HO) and extra heavy crude oil (EHO) represent nearly 70% of the world’s reserves but require extensive upgrading to satisfy refining and petrochemical specifications. Their high asphaltene content results in elevated viscosity and reduced API gravity, posing significant challenges in extraction, transportation, and refining. Advanced catalytic approaches are crucial for efficient asphaltene removal and the conversion of heavy feedstocks into valuable light fractions. Kaolin, an aluminosilicate mineral, has emerged as a key precursor for zeolite synthesis and a promising catalyst in upgrading processes. This article provides a comprehensive exploration of kaolin’s geological origins, chemical properties, and structural characteristics, as well as the various modification techniques designed to improve its catalytic performance. Special focus is given to its application in the transformation of heavy crudes, particularly in facilitating asphaltene breakdown and enhancing light distillate yields. Finally, future research avenues and potential developments in kaolin-based catalysis are discussed, emphasizing its vital role in addressing the technological challenges linked to the growing reliance on heavier crude resources. Full article

Lignin, the earth’s second-most abundant biopolymer after cellulose, has long been relegated to low-value byproducts in the pulp and paper industry. However, recent advancements in valorization are transforming lignin into a sustainable and versatile feedstock for producing high-value biofuels, bioplastics, and specialty chemicals. This review explores the conversion of lignin’s complex structure, composed of syringyl (S), guaiacyl (G), and p-hydroxyphenyl (H) units, into value-added products. We critically assess various biochemical and analytical techniques employed for comprehensive lignin characterization. Additionally, we explore strategies for lignin upgrading and functionalization to enhance its suitability for advanced biomaterials. The review emphasizes key areas of lignin valorization, including catalytic depolymerization methods, along with the associated challenges and advancements. We discuss its potential as a feedstock for diverse products such as biofuels, bioplastics, carbon fibers, adhesives, and phenolic compounds. Furthermore, the review briefly explores lignin’s inherent properties as a UV protectant and antioxidant, alongside its potential for incorporation into polymer blends and composites. By presenting recent advancements and case studies from the literature, this review highlights the significant economic and environmental benefits of lignin valorization, including waste reduction, lower greenhouse gas emissions, and decreased reliance on non-renewable resources. Finally, we address future perspectives and challenges associated with achieving large-scale, techno-economically feasible, and environmentally sustainable lignin valorization. Full article

The fruit processing industry is responsible for disposing of huge amounts of byproducts, especially fruit peels (FPs), which are often discarded in landfills. Using FPs in biotechnological processes contributes to a circular economy, reducing the environmental burden of FPs and increasing the revenue of the fruit processing industry. This study was focused on upgrading the nutritional value of orange (OPs) and banana (BPs) peels by solid-state fermentation (SSF) with filamentous fungi. SSF factors (moisture, fermentation time, inoculum size, ammonium sulfate (AS), and corn steep liquor (CSL)) and fungi species (Aspergillus ibericus and Rhizopus oryzae) were studied by a variable screening Plackett–Burman design. Both fungi grew on untreated FPs, increasing their protein content and antioxidant activity. Moisture, AS, and CSL were further studied by a Box–Behnken design with A. ibericus. Fermented OPs at 70% moisture and 0.005 g/g AS increased their protein content by 200%, whereas BPs at 70% moisture and 0.005 g/g CSL increased by 123%. Fermented peels were enriched in protein, fiber, and minerals, with a low content of carbohydrates and soluble sugars. Fermented OPs and BPs showed higher antioxidant activity than unfermented peels. The SSF of these FPs is an innovative approach that contributes to obtaining rich nutrient-fermented peels for food. Full article

Solid-State fermentation (SSF) is a valuable process used for the enhancement of the nutritional profile of agro-industrial by-products. The main objective of the present study concerns the exploitation of a mixture consisting of Cottonseed Cake (CSC) and Lathyrus clymenum pericarp (LCP) at a ratio of 80–20% w/w, which was utilized as substrate for the initiated by Pleurotus ostreatus SSF process. The final goal is the improvement of their nutritional value and the parallel reduction in their gossypol content. The obtained results revealed a statistically significant increase (p < 0.05) in protein content by 34.91%, while 1,3-1,6 β-glucans exceeded a 5-fold statistically significant increment (p < 0.05) at Day 11. Furthermore, lignin was reduced significantly (−26.71%) at Day 11. Free gossypol’s presence was lowered by 12.45%, while SSF presented a profound effect concerning the total gossypol level since the latter underwent a statistically significant reduction (p < 0.05) that exceeded 9-fold at Day 11. The study herein highlights SSF’s efficiency as a potential means to reduce free and total gossypol content with a parallel upgrade of its nutritional value. The fermentation outcome reveals its potential as a feed supplement and contributes to the reduction in the environmental footprint within the framework of a circular economy. Full article

Direct upgrading of methane into value-added products is one of the most significant technologies for the effective transformation of hydrocarbon feedstocks in the chemical industry. Both oxidative and non-oxidative methane conversion are broadly useful approaches, though the two reaction pathways are quite distinguished. Oxidative coupling of methane (OCM) has been widely studied, but suffers from the low selectivity to C₂ hydrocarbons because of the overoxidation leading to undesired byproducts. Therefore, non-oxidative coupling of methane is a worthy alternative approach to be developed for the efficient, direct utilization of methane. Recently, heterogeneous catalysts comprising singly dispersed metal sites, such as single-atom catalysts (SAC) and surface organometallic catalysts (SOMCat), have been proven to be effectively active for direct coupling of methane to product hydrogen and C₂ products. In this context, this review summarizes recent discoveries of these novel catalysts and provides a perspective on promising catalytic processes for methane transformation via non-oxidative coupling. Full article

The use of whole-cell biocatalysts in microbial cell factories is of great interest to produce added-value compounds. Through large-scale fermentative processes, which use secondary raw materials as substrates, it is possible to recycle and upgrade agro-industrial by-products. This review addresses the main fermentative processes and bioreactors currently used for the valorization of orange peel, a by-product of the Citrus processing industry. Among the main added-value products, bioethanol, organic acids, enzymes, single cell proteins (SCPs), dyes and aromatic compounds have been industrially produced using orange peel via solid state fermentation and submerged fermentation. This approach fits within the circular economy goals in terms of clean technology and renewable energy, valorization and recycling, upgrade of industrial by-products and sustainability. Full article

The industrial processing of Argentine shortfin squid to obtain rings generates a significant amount of protein-rich waste, including the skin, which is rich in collagen and attached myofibrillar proteins. This waste is generally discarded. In this study, skin was used as a source of proteins that were hydrolysed using Trypsin, Esperase® or Alcalase®, which released peptides with antioxidant potential and, in particular, antihypertensive (ACE inhibition), hypoglycemic (DPP-IV inhibition) and/or nootropic (PEP inhibition) potential. Among the three enzymes tested, Esperase® and Alcalase produced hydrolysates with potent ACE-, DPP-IV- and PEP-inhibiting properties. These hydrolysates underwent chromatography fractionation, and the composition of the most bioactive fractions was analysed using HPLC-MS-MS. The fractions with the highest bioactivity exhibited very low IC50 values (16 and 66 µg/mL for ACE inhibition, 97 µg/mL for DPP-IV inhibition and 55 µg/mL for PEP inhibition) and were mainly derived from the hydrolysate obtained using Esperase®. The presence of Leu at the C-terminal appeared to be crucial for the ACE inhibitory activity of these fractions. The DPP-IV inhibitory activity of peptides seemed to be determined by the presence of Pro or Ala in the second position from the N-terminus, and Gly and/or Pro in the last C-terminal positions. Similarly, the presence of Pro in the peptides present in the best PEP inhibitory fraction seemed to be important in the inhibitory effect. These results demonstrate that the skin of the Argentine shortfin squid is a valuable source of bioactive peptides, suitable for incorporation into human nutrition as nutraceuticals and food supplements. Full article

Low levels of docosahexaenoic acid (DHA) in the brain have been related to neurological disorders, like Alzheimer’s disease (AD). After ingestion, dietary DHA must cross the blood–brain barrier, where it is absorbed as lysophosphatidylcholine (LPC), due to its role as a preferential DHA carrier in the brain. This work aimed at the production of LPC-DHA extracts to be used in supplementation/food fortification intended neural enrichment in DHA. As it is rich in DHA, especially its phospholipids (PL), Atlantic mackerel (Scomber scombrus, caught in Spring/2022) was used as a raw material. The polar lipids fraction was separated and hydrolysed with Rhizomucor miehei lipase, to enzymatically convert phosphatidylcholine (PC) into LPC. The fish (muscle and by-products) lipids fraction was used for total lipids (TL) content, lipid classes (LC) and fatty acid (FA) profile evaluation, whilst polar lipids extracts were studied for LC production and FA analysis. Muscle TL ranged between 1.45 and 4.64 g/100 g (WW), while by-products accounted for 7.56-8.96 g/100 g, with the highest contents being found in March. However, PL were more abundant in muscle (22.46–32.20% of TL). For polar lipids extracts, PL represented 50.79% of TL, among which PC corresponded to 57.76% and phosphatidylethanolamine to 42.24%. After hydrolysis, nearly half of this PC was converted into LPC. When compared to the initial PC, DHA relative content (33.6% of total FA) was significantly higher after hydrolysis: 55.6% in PC and 73.6% in LPC. Such extract, obtained from this undervalued species, may represent a promising strategy to increase DHA uptake into brain cells while allowing this species to upgrade. Full article

The gasification performance of lignite/barley straw mixtures for syngas production was investigated. The experiments were carried out under a steam or carbon dioxide atmosphere, in fixed-bed and thermogravimetric–mass spectrometry systems. The thermal behavior, reactivity, conversion, product gas composition, liquid and gaseous by-products and interactions between fuels were determined and correlated with the structural characteristics and inherent minerals in ashes, which were analyzed via mineralogical, chemical and fusibility tests. Devolatilization of the materials up to 600 °C resulted in the carbon enrichment of chars and a 30–90-fold increase in the specific surface area. Gaseous and liquid by-products with higher heating values of 5–7 MJ/m³ and 20–28 MJ/kg could offer valuable energy. Upon steam gasification up to 1000 °C, product gas was enriched in hydrogen and carbon monoxide. The syngas yield and heating value of the gas mixture were higher for barley straw fuel (0.77 m³/kg, 11.4 MJ/m³), which, when blended with the lignite, produced upgraded products. Upon carbon dioxide gasification up to 1000 °C, barley straw char exhibited a 3-times higher rate than the lignite, as well as higher conversion (94.5% vs. 62.9%) and a higher syngas yield (0.84 m³/kg vs. 0.55 m³/kg). Lignite/barley straw blends showed synergistic effects and presented higher gasification reactivity and conversion in comparison to lignite. The overall performance of lignite was improved with the steam reagent, while that of barley straw was improved with the carbon dioxide reagent. Full article