Search Results (196)

Caffeine has been recognized as an emerging pollutant in aquatic ecosystems due to its persistence. This study evaluated the techno-economic viability of caffeine removal using thermally modified bentonite (Na–Bent–400) as an adsorbent. Caffeine removal was simulated under two operational schemes: Scenario 1 (S1: Adsorption–Disposal), where Na–Bent–400 is discarded following saturation, and Scenario 2 (S2: Regeneration–Reuse–Disposal), which integrates adsorbent regeneration to enable the reuse of Na–Bent–400 in a second adsorption before final disposal. Using the optimized model for caffeine removal (95.97% removal efficiency in batch operation: 2.26 g/L Na–Bent–400, 30 mg/L caffeine, and pH 8), the process was scaled up through process simulation in Aspen Plus (V14) for a treatment flow rate of 8 L/s (252,288 m³/year). Capital expenditure (CapEx) was estimated at USD 331,004 without adsorbent regeneration (S1) and USD 486,725 with regeneration (S2), showing a 47% increase due to auxiliary equipment and operational complexity; however, integrating adsorbent regeneration minimizes long-term operational expenditures by reducing raw material requirements and wastewater treatment costs. Estimated water treatment costs based on operational expenditures (OpEx) are USD 1.38/m³ for S1 and USD 0.74/m³ for S2. A sensitivity study found that caffeine concentrations above 30 mg/L have little effect on treatment costs. By evaluating these scenarios, this study demonstrates the preliminary techno-economic viability of thermally modified bentonite for treating caffeine-contaminated agroindustry effluents. Full article

Olive oil production is an economically and culturally important agro-industrial activity, particularly in Mediterranean regions, but conventional extraction processes generate significant quantities of by-products and may lead to the loss of valuable bioactive compounds. In this context, improving extraction efficiency while preserving oil quality and promoting sustainable processing has become a major research focus. This review examines the composition of virgin olive oil with particular attention to minor bioactive compounds and discusses how conventional processing technologies influence their distribution and retention. The environmental implications of traditional extraction systems, especially the generation of olive mill wastewater and solid residues, are also addressed. Furthermore, emerging and alternative extraction technologies are analyzed, including screw press (expeller) and supercritical CO₂ extraction, highlighting their potential to enhance the recovery of bioactive compounds and reduce environmental impacts. Particular emphasis is placed on water-free or reduced-water extraction approaches and on the valorization of olive mill by-products as part of a circular economy strategy. Overall, innovative extraction technologies can reconcile efficiency, sustainability and quality by minimizing polyphenol losses and wastewater generation, requiring further industrial optimization. Full article

The textile industry generates dye-containing wastewater characterized by intense coloration, high salinity, elevated oxygen demand, and recalcitrant pollutants. Although conventional treatment technologies can remove color and reduce organic load, decolorization alone does not guarantee detoxification because toxic transformation products may persist or be generated during incomplete degradation. This review emphasizes the synergistic interaction between oxidative and reductive enzymes and microorganisms as a promising strategy for promoting extensive pollutant transformation and potentially enhancing mineralization. Particular attention is given to the complementary roles of laccases (LAC), azoreductases (AZOR), ligninolytic peroxidases, bacteria, fungi, and microbial consortia in sequential degradation pathways that can improve detoxification efficiency. Mechanisms including azo bond cleavage, aromatic amine transformation, and subsequent microbial degradation are discussed to demonstrate how integrated systems can overcome the limitations of enzyme- or microorganism-based treatments alone and may facilitate complete pollutant removal under appropriate conditions. The review also explores biomass-derived biocatalysts produced through solid-state fermentation of agro-industrial residues, demonstrating opportunities to integrate wastewater remediation with biomass valorization and circular bioeconomy principles. Finally, operational challenges, toxicity assessment, reactor design, enzyme immobilization, scale-up, and techno-economic considerations are discussed, and future research priorities are identified to support the development of sustainable and industrially applicable enzymatic–microbial detoxification technologies. Full article

Dairy wastewater is an agro-industrial effluent characterized by elevated concentrations of organic matter, nutrients and suspended solids, posing environmental risks when inadequately treated. This study assessed the feasibility of a simultaneous Scenedesmus obliquus–Lemna minor co-cultivation system within a single, shared bioreactor for the treatment of modified dairy wastewater, comparing its performance against the two individual monocultures. Raw dairy wastewater was subjected to sequential heat treatment, ultrasound and filtration, which significantly altered its physicochemical composition (p < 0.05) prior to cultivation. Experiments were conducted in parallel laboratory-scale open reactors over 14 days with periodic sampling. The mixed system achieved the highest removal efficiencies (95.3% COD, 91.3% TOC, 97.1% NO₃-N and 94.6% PO₄-P), with rapid pollutant reduction during the first 3–6 days followed by a slower stabilization phase. Despite these high removal efficiencies, the final COD concentration remained relatively high in absolute terms, indicating that the system is best suited as an on-site pretreatment step at the dairy facility, reducing the organic and nutrient load prior to discharge into the municipal sewerage network for further treatment at a municipal WWTP. The recovered microalgal biomass was nutrient-rich and exhibited preliminary biofertilizer potential, as reflected in the positive growth trends observed in two of the three tested Lactuca sativa L. cultivars, although these did not reach statistical significance relative to controls. Overall, the integrated system represents an effective, low-impact approach combining pollutant removal, biomass valorization and circular bioeconomy principles. Full article

Cr(VI) is considered one of the most dangerous pollutants due to its bioaccumulation and toxicity, which has driven the search for sustainable and effective solutions for its removal from wastewater. In this regard, the aim of this research was to develop a material based on cellulose acetate (CA) extracted from Cocos nucifera L. fibres and polyhydroxybutyrate (PHB) for the removal of Cr(VI). The biocomposite (PHB/CA) was synthesised using the casting method; its adsorption capacity was evaluated in batch systems and its efficiency measured at different contaminant concentrations. The characterisation results indicated interactions between the fibres and the PHB, resulting in a porous material containing hydroxyl, amino, ether/alcohol, carbonyl and alkane/alkyl functional groups. Cr(VI) removal tests indicated that the optimal operating conditions were achieved at a pH of 3 and a concentration of 15 mg/L, yielding an adsorption efficiency of 44.5%, and showing a trend consistent with the Elovich kinetic model and the Langmuir isotherm. In conclusion, this research proposes the exploration of new bioadsorbents derived from coconut agro-industrial waste combined with biopolymers for the remediation of contaminated water, thereby expanding our understanding of the relationship between the structure of bio-composites of renewable origin and their performance in heavy metal adsorption processes. Full article

Water scarcity and increasing pressure on freshwater resources have intensified interest in the reuse of agro-industrial effluents in semi-arid Mediterranean regions. This study examines the volume, temporal variability, and physicochemical characteristics of wastewater generated by a tomato-processing plant in central Tunisia during the 2022 production campaign. Wastewater discharge was continuously monitored throughout the season, combined with physicochemical analyses to assess effluent quality and reuse potential. Results show strong variability in wastewater generation, closely related to production cycles and operational activities, particularly cleaning operations. Specific wastewater production ranged from 1.5 to 1.7 m³ per ton of processed tomatoes. The effluents were characterized by variable salinity conditions and dominant Na-Cl facies, with electrical conductivity values ranging from 2.09 to 8.01 dS/m and an average value of 4.06 dS/m. While pH and BOD₅ remained within Tunisian standards, COD occasionally exceeded regulatory limits, indicating residual organic pollution. Over the 84-day campaign, approximately 490,000 m³ of wastewater was generated, representing a significant non-conventional water resource. This volume could potentially irrigate 98–163 ha depending on crop water requirements. However, salinity and temporal variability remain key constraints for large-scale reuse. Unlike previous studies based on short-term or laboratory-scale assessments, this work provides a field-scale, season-long evaluation under real operating conditions. Full article

Hexavalent chromium (Cr(VI)) is a highly toxic, non-biodegradable, and carcinogenic heavy metal. Its continuous release into aquatic ecosystems demands efficient, low-cost adsorbents. In this study, orange peel and peanut shell residues were thermally modified at 250 °C to enhance Cr(VI) remediation. Structural characterization confirmed that low-temperature calcination transforms raw agroindustrial wastes into functional biochars with a chemical architecture primed for cooperative Cr(VI) removal. N₂ physisorption revealed a hierarchical mesoporous network with average pore diameters of 30.6 nm (calcined orange peel) and 15.4 nm (calcined peanut shell), despite low specific surface areas. Batch adsorption experiments demonstrated that removal kinetics reached equilibrium within 5 min for the modified biochars. Isotherm modeling showed that the adsorption process was best described by the Freundlich and Sips models. The calculated Sips heterogeneity factors (β_S > 1) provided evidence of a cooperative multi-layer adsorption mechanism, attributed to the induced mesoporosity: initial chemisorption at high-energy sites facilitates the continuous anchoring of additional Cr(VI) ions without premature saturation. Ultimately, this study demonstrates that low-temperature calcination is a viable strategy to transform agricultural waste into kinetically efficient, cooperative adsorbents for wastewater treatment. Full article

Salicornia is a genus of salt-tolerant plants capable of growing and producing biomass under conditions that severely constrain conventional agriculture. Beyond its ecological niche as a halophyte, Salicornia has emerged as a multifunctional crop for sustainable food, feed, and bio-based production in saline landscapes. The increasing generation of saline wastewaters and brines from aquaculture, municipal treatment, agro-industrial activities, and greenhouse systems intensifies the need for natural solutions that can recover resources while protecting soils and receiving ecosystems. This review synthesizes current understanding of how Salicornia species perform when irrigated with saline wastewaters, with particular attention to their dual role as productive crops and phytoremediation agents. It further examines the biological mechanisms underlying salt tolerance and the influence of wastewater characteristics on biomass production and phytoremediation performance. Overall, the evidence indicates that Salicornia performs particularly well in nutrient-rich, controlled saline effluents, whereas more complex wastewater matrices require careful contaminant management to ensure biomass quality and safe reuse. This synthesis positions Salicornia as a fundamental species for circular and climate-resilient strategies linking saline wastewater reuse with crop production, while emphasizing that standardized reporting, long-term field validation, and contaminant-aware biomass management remain essential to support wider adoption. Full article

This paper reported the grey water footprint (GWF) mitigation resulting from a brewery industry wastewater treatment using malt dust-derived biochar. The GWF was assessed based on chemical oxygen demand (COD) and total suspended solids (TSS) removal. A new data-driven parametric index (GWFI_BP) was reported that uses the GWF tool. A data-driven model was designed in order to define the impact of the dual advantages of biochar application relative to the Conventional Activated Sludge (CAS) process. A GWF reduction of approximately 21.59% was found for the biochar application. Full article

The growing volume of agro-industrial and food-processing residues has intensified interest in their use as low-cost substrates for microbial bioprocessing. Coffee-derived waste streams, including spent coffee grounds (SCGs), wastewater, pulp, husk, and silverskin, represent abundant but still underutilized biomass resources. This narrative review evaluates their potential as liquid or solid substrates or as components of cultivation media for selected microbial systems, including microalgae, bioremediation- and bioprocess-related bacteria, edible fungi such as Pleurotus spp., and yeasts in the genera Pichia, Kluyveromyces, Saccharomyces, and Yarrowia. The review compares the suitability of individual coffee residues based on substrate composition, pretreatment requirements, inhibitory compounds, process limitations, and reported outputs. Coffee-derived residues can reduce substrate costs, support waste valorization, and partially replace conventional nutrients in microbial processes. However, their broader application is limited by compositional variability, conditioning or hydrolysis requirements, difficulties in process standardization, and downstream processing costs. Current evidence most strongly supports fungal cultivation on SCG-containing substrates, bacterial treatment of caffeine-rich wastewaters, yeast fermentation of hydrolyzed residues, and microalgal use of conditioned liquid streams. The review identifies key research gaps and outlines realistic directions for developing coffee-based microbial bioprocesses within a circular bioeconomy framework. Full article

Admiralty brass, commonly used in heat exchangers, is particularly susceptible to corrosion in acidic media such as those used in industrial cleaning. To mitigate this problem, the present study evaluated Musa acuminata (banana) peel and Lupinus mutabilis Sweet (Andean lupine) extracts as sustainable, low-toxicity corrosion inhibitors for admiralty brass in 0.5 M HCl. Six extracts were prepared using different solvents and characterized by qualitative and semi-quantitative phytochemical analyses (phenols, flavonoids, alkaloids). M. acuminata extracts were rich in phenolic compounds, while L. mutabilis extracts contained high levels of quinolizidine alkaloids. A comparative electrochemical screening of the agro-industrial waste-derived extracts revealed that the inhibition efficiency of M. acuminata extracts reached up to 43.6%, whereas the debittering wastewater extract of L. mutabilis (E6) achieved a maximum efficiency of 85.5% at 2000 ppm. A preliminary techno-economic analysis indicated the feasibility of industrial-scale production of the L. mutabilis-based inhibitor, yielding a net present value (NPV) of USD 9.48 million, an internal rate of return (IRR) of 27.3%, and a payback period of 6.7 years. These results demonstrate that agro-industrial residues can be valorized into effective and profitable green corrosion inhibitors, aligning with circular economy and sustainable chemistry principles. Full article

The growing demand for sustainable energy carriers has intensified interest in hydrogen production from renewable resources and waste-derived substrates. In this context, microbial electrolysis cells (MECs) have emerged as a promising technology for the simultaneous treatment of organic waste and biohydrogen generation. This review provides an overview of recent advances in MEC systems, focusing on reactor configurations, performance indicators such as hydrogen production rate, coulombic efficiency, and chemical oxygen demand removal. Attention is given to the valorization of real waste streams, including municipal and agro-industrial effluents, highlighting the differences between laboratory- and pilot-scale applications. While numerous studies have demonstrated the technical feasibility of MECs, several bottlenecks still limit their large-scale implementation, including challenges associated with the use of complex substrates. In particular, untreated wastewater often leads to reduced process efficiency due to its variable composition and the occurrence of competing microbial pathways. To overcome these limitations, integrated approaches are also discussed, with emphasis on the coupling of dark fermentation, capable of enhancing substrate biodegradability through the production of volatile fatty acids, with MEC systems. Overall, MEC technology represents a promising pathway for sustainable hydrogen production within circular waste management frameworks, although further advancements are required to enable its practical application. Full article

The increasing generation of agro-industrial residues like nejayote (maize lime-cooking wastewater from the maize nixtamalization process) poses significant environmental challenges in Mexico due to its elevated chemical oxygen demand (COD) and organic load. This study evaluates the physical separation of nejayote via membranes and its use as a low-cost substrate for producing lipids and carotenoids using Rhodotorula glutinis. A batch culture followed by pulse-feeding achieved a COD removal efficiency of 53.6% (0.22 g COD/(L h)) and a biomass concentration of 3.72 ± 0.45 g COD/L within 48 h. The yeast demonstrated a high specific metabolic efficiency, yielding 0.457 g of lipids and 0.0049 g of carotenoids per gram of biomass, with an oleaginous fraction of 46.21% in dry weight. Experimental data calibrated a process model in SuperPro Designer, simulating full-scale processes treating 100, 1000, and 10,000 m³ of nejayote per batch, producing up to 2137.11 MT of lipids and 22.90 MT of carotenoids annually. A techno-economic analysis estimated the investment, operating costs, and financial indicators for all scenarios. Strategies like evaporation and reverse osmosis to concentrate nejayote significantly improved profitability by reducing equipment size. Additionally, a circular economy approach was modeled, recovering process water and nutrient-rich side streams. These findings confirm that integrated physical and biological treatment, coupled with resource recovery, transforms this particularly agro-industrial residue into a technically robust and economically viable biorefinery feedstock, aligning industrial production with sustainable waste management. Full article

The increasing demand for sustainable energy and efficient wastewater treatment has driven interest in single-chamber microbial fuel cells (SCMFCs) as integrated systems for bioelectricity generation and waste remediation. This study evaluates untreated agro-industrial byproduct olive mill wastewater (OMW) as a substrate in SCMFCs. It investigates the performance of activated biochar derived from olive pomace coated on stainless-steel mesh (ACB/SSM) as a low-cost cathode material. A synthetic media was used as a control. Electrochemical performance was assessed using voltage profiles, polarization analysis, power density, chemical oxygen demand (COD%) removal, and coulombic efficiency (CE%). The synthetic media achieved higher peak voltage (0.647 ± 0.026 V) and power density (46.05 mW m⁻²), whereas OMW showed more stable voltage output and lower internal resistance. OMW exhibited superior initial COD removal (74%) and a gradual increase in CE% up to 63% over successive cycles. In contrast, synthetic media exhibited a consistent COD% of 64%; its CE% removal improved to 61%. These results demonstrate that, despite lower peak power, OMW provides a more stable and sustainable substrate for long-term SCMFC operation. The use of waste-derived biochar cathodes further enhances system feasibility by reducing cost and supporting circular economy principles. This study highlights the potential of OMW-based SCMFCs as a practical approach for simultaneous wastewater treatment and renewable energy recovery. Full article

Northern Colombian Creole-Antillean avocado constitutes a promising agroindustrial resource because of its lipid-rich composition and regional availability. Despite this potential, the industrial exploitation of this biomass remains limited, particularly regarding the technical assessment of large-scale oil production systems. In this study, an avocado oil production process was evaluated through computer-aided simulation combined with the Water–Energy–Product (WEP) methodology to assess operational behavior, resource utilization, and process efficiency from an integrated technical perspective. The evaluated system achieved an overall production yield of 9.43%, mainly affected by the elevated raw material requirements associated with oil generation. Nevertheless, the extraction stage exhibited favorable technical performance, reaching an oil recovery efficiency of 81.42%. Concerning water management, the process required 26.85 m³/t of freshwater and generated wastewater equivalent to 96.05% of the total water consumed, revealing important limitations related to water integration and recirculation within the process configuration. From an energy perspective, the system presented a specific energy intensity of 19,929 MJ/t, with natural gas representing the predominant energy source throughout the operation. Overall, the obtained results demonstrate that the proposed process is technically viable for avocado oil production while also identifying critical opportunities for improving resource utilization, decreasing water demand, and enhancing the operational sustainability of the system. Full article