Search Results (53)

This study presents a four-year evaluation (2020–2024) of an integrated climate mitigation project on a pig farm in Ávila, Spain, at an elevation of over 1100 m above sea level with continental climate conditions. The project aimed to reduce greenhouse gas emissions (GHG) and nitrogen pollution by implementing solid–liquid filtration followed by biological treatment in a 625 m³ Sequencing Batch Reactor (SBR) operating under a nitrification–denitrification (N-DN) regime. The SBR carried out four daily cycles, alternating aerobic and anoxic phases, with 5 and 8 m³ inlets. Aeration intensity and redox potential were continuously monitored to optimize bacterial activity. Analytical parameters (pH, electrical conductivity, solids content, nitrogen, phosphorus, and potassium) were measured using ISO methods and tracked frequently. Annual emission reductions were 75% for N₂O, up to 97% for NH₃, and 80% for N₂. In the summer months, we observed higher efficiency reduction for N₂, NH₃, and NO₂. Additionally, there was a 75% average reduction for COD and up to 92% for total GHG emissions. This real-world case study highlights the effectiveness of SBR-based N-DN systems for nutrient removal and emission reduction in high-altitude, climate-sensitive regions, contributing to EU nitrate directive compliance and circular economy practices. Full article

Nejayote (Nej), an effluent from nixtamalization process, has an alkaline pH and contains a high load of organic matter in suspension and dissolution, which makes it a highly polluting waste when discharged directly into the environment. However, the sustainable reuse of this effluent is relevant since it contains high-value compounds (ferulic acid (FA)) with appropriate activity for the ecological synthesis of silver nanoparticles (AgNPs). This study explores the synthesis of AgNPs using Nej as a reducing and stabilizing agent and evaluates the antibacterial effectiveness of AgNPs against Escherichia coli (E. coli). The AgNPs under study possess excellent optical (UV-Vis) and structural properties (XRD). HR-TEM images show predominantly spherical particles, with an average size of 20 nm. FTIR spectroscopy identified functional groups, including phenols and flavonoids, on the nanoparticle surface, acting as stabilizing agents. HPLC supports the existence of FA in the AgNPs. Biogenic AgNPs exhibit enhanced antibacterial activity due to the adsorption of these functional groups onto their surface, which contributes to bacterial membrane disruption. Finally, no hemolytic or cytotoxic activity was observed, suggesting that the AgNPs exert antimicrobial activity without potentially harmful doses (biocompatibility). The study highlights the potential of Nej as a sustainable source for use in nanoparticle synthesis, promoting the recycling of agro-industrial waste and the production of materials with technological applications. Full article

Aquaculture effluents are a growing source of water pollution, releasing suspended solids, organic matter, nitrogen, and phosphorus into aquatic environments. Recirculating aquaculture systems (RASs) have emerged as a more sustainable solution, allowing water to be continuously treated and reused. Within RASs, coagulation–flocculation is a key treatment step due to its simplicity and effectiveness. Tannin-based coagulants have gained attention as natural alternatives to traditional chemical agents. Although natural coagulants have been studied in aquaculture, only a few works explore their use in continuous-flow systems. This study evaluates a chestnut shell-based (CS) coagulant applied in continuous mode for the post-treatment of aquaculture effluent. The performance of CS was compared with Tanfloc, aluminum sulfate, and ferric chloride in removing color and dissolved organic carbon (DOC). At natural pH (6.5) and 50 mg·L⁻¹, CS and Tanfloc achieved color removal of 61.0% and 65.5%, respectively, outperforming chemical coagulants. For DOC, Tanfloc and chemical coagulants removed 45–50%, while CS removed 32%. All coagulants removed over 90% of phosphorus, but nitrogen removal was limited (30–40%). These results highlight the potential of tannin-derived coagulants, particularly from agro-industrial residues, as sustainable solutions for aquaculture wastewater treatment in continuous systems. Full article

This study explores the feasibility of producing biohydrogen from winery wastewater using a dual-chamber microbial electrolysis cell (MEC). A mixed microbial consortium pre-adapted to heavy-metal environments and enriched with Geobacter sulfurreducens was anaerobically cultivated from diverse waste streams. Over 5000 h of development, the MEC system was progressively adapted to winery wastewater, enabling long-term electrochemical stability and high organic matter degradation. Upon winery wastewater addition (5% v/v), the system achieved a sustained hydrogen production rate of (0.7 ± 0.3) L H₂ L⁻¹ d⁻¹, with an average current density of (60 ± 4) A m⁻³, and COD removal efficiency exceeding 55%, highlighting the system’s resilience despite the presence of inhibitory compounds. Coulombic efficiency and cathodic hydrogen recovery reached (75 ± 4)% and (87 ± 5)%, respectively. Electrochemical impedance spectroscopy provided mechanistic insight into charge transfer and biofilm development, correlating resistive parameters with biological adaptation. These findings demonstrate the potential of MECs to simultaneously treat agro-industrial wastewaters and recover energy in the form of hydrogen, supporting circular resource management strategies. Full article

Climate change and socio-economic challenges require greater production efficiency in the agricultural sector. Using microbial additives and biodiesel byproducts in silage production improves quality, reduces losses, and adds value to agro-industrial byproducts, thereby reducing environmental impacts. This study aimed to evaluate the potential of including cottonseed cake (CSC) and microbial inoculant isolated from forage cactus on the fermentation profile and quality of forage sorghum silage. The experimental design used was a completely randomized design, with four treatments: Control: sorghum (SS); sorghum + 10% CSC (% natural matter) (SSCSC); sorghum + Weissella cibaria (SSWC); and sorghum + 10% CSC + W. cibaria (SSCSCWC). There were increases of 15.1% in lactic acid bacteria, 11.4% in dry matter, and 62.9% in crude protein for SSCSC than SS (p = 0.001). There was a decrease of 96.4% in effluent losses (p = 0.002) and 21.6% in acid detergent fiber content (p = 0.005) in SSCSCWC compared to SS. Including 10% CSC and Weissella cibaria in sorghum silage was effective in improving nutritional composition with increased protein content and reduced fermentation losses. The cottonseed cake inclusion promotes greater efficiency in sorghum silage production, which can result in higher profitability and sustainability. Full article

The growing challenges of freshwater scarcity and the high generation of agro-industrial waste, particularly from fruit and vegetable (F&V) processing, pose significant threats to the sustainability of global food systems. F&V waste, which represents a major portion of the 1.3 billion tons of annual food waste, is characterized by a high moisture content (80–95%), making it a largely overlooked but promising source of water recovery. This review critically assesses the techno-economic and environmental feasibility of extracting water from moisture-rich agro-industrial waste streams. Potential technologies such as solar distillation and membrane separation are evaluated to determine their capacity to treat complex organic effluents and recover high-quality water. The potential end uses of reclaimed water in all sectors are explored, focusing on agricultural irrigation, fertigation, industrial reuse and environmental restoration. This study addresses a key research gap and proposes the reclassification of agro-industrial waste as a viable water resource aligned with circular bioeconomy principles and Sustainable Development Goals (SDGs) 6 and 12. Full article

Agro-industrial activities generate significant amounts of organic waste and a variety of effluents thus posing environmental challenges. Viticulture in Argentina, which covered 204,847 ha in 2023, faces water scarcity as a limiting factor conditioning its production. This industry produces large volumes of grape marc, sediments, and stalks, which can be valorised into products like alcohol, tartaric acid, and compost. However, these valorisation processes generate effluents with high organic load and salinity, further stressing water resources. This study explores the potential of utilising these effluents to cultivate plant biomass in arid regions (sorghum or perennial pasture), which could serve as bioenergy, animal feed, or composting co-substrates, contributing to circular bioeconomy principles. The combined use of effluent as a water resource and the sowing of sorghum and pasture increased soil organic matter content and led to a slight reduction in pH (depth: 0.30–0.60 m) compared to the control treatment. The sorghum plots showed better establishment and higher dry biomass yield (32.6 Tn/ha) compared to the pasture plots (6.5 Tn/ha). Sorghum demonstrated better tolerance to saline soils and high salinity effluents, aligning with previous studies. Although pasture had a lower biomass yield, it was more efficient in nutrient uptake, concentrating more NPK, ash, and soluble salts. Sorghum’s higher yield compensated for its lower nutrient concentration. For biomass production, sorghum is preferable, but if nutrient capture from effluents is prioritised, summer polyphytic pastures are more suitable. These results suggest that the final selection between plant biomass alternatives highly depends on whether the goal is biomass generation or nutrient capture. Full article

Lignocellulosic fungi are highly versatile organisms with valuable applications in bioremediation processes, including the biodegradation of agro-industrial effluents. In this work, the use of a native strain of the white-rot fungus, Pycnoporus aff. sanguineus, in the bioremediation of the sugar industry waste called vinasse was studied, originating from the San Martín del Tabacal Sugar Mill, located in the north of the Salta province, Argentina. We studied, under controlled laboratory conditions, the bioremediation process of three concentrations of vinasse (5, 10, and 25% in distilled water) with a native isolated strain. The results showed biomass growth at all three tested concentrations, with a maximum at the highest vinasse concentration (25%), while the percentages of color and Chemical Oxygen Demand (COD) removal indicated that the most efficient treatment was with 10% vinasse. The results obtained are promising for the treatment of effluents from the sugar industry using white-rot fungi, considering the valuable subproducts of Pycnoporus spp. biomass. Full article

This study aimed to develop and implement a nanotechnology-based alternative to traditional tracers used in the oil and gas industry for assessing interwell connectivity. A simple and rapid hydrothermal protocol for synthesizing carbon quantum dots (CQDs) using agroindustry waste was implemented. Three commercial CQDs were employed (CQDblue, CQDgreen, and CQDred); the fourth was synthesized from orange peel (CQDop). The CQDs from waste and other commercials with spherical morphology, nanometric sizes less than 11 nm in diameter, and surface roughness less than 3.1 nm were used. These tracers demonstrated high colloidal stability with a negative zeta potential, containing carbonyl-type chemical groups and unsaturations in aromatic structures that influenced their optical behavior. All materials presented high colloidal stability with negative values of charge z potential between −17.8 and −49.1. Additionally, individual quantification of these tracers is feasible even in scenarios where multiple CQDs are present in the effluent with a maximum percentage of interference of 15.5% for CQDop in the presence of the other three nanotracers. The CQDs were injected into the field once the technology was insured under laboratory conditions. Monitoring the effluents allowed the determination of connectivity for five first-line producer wells. This study enables the application of CQDs in the industry, particularly in fields where the arrangement of injector and producer wells is intricate, requiring the use of multiple tracers for a comprehensive description of the system. Full article

Brewery (BW) and dairy (DW) wastewater are two types of agro-industrial wastewater that are generated in large amounts and, therefore, should be treated effectively and in an environmentally beneficial manner. Both these wastewater types are characterized by a high COD, BOD₅, and nutrient content, and conventional wastewater treatment methods such as an activated sludge process may prove to be inefficient due to the possibility of foaming, large biomass production, low activity at low temperatures, and risk of overloading the reactor with a load of organic pollutants. In the context of the described difficulties, anaerobic processes seem to be the best alternative. An interesting research area is the co-digestion of these wastewaters. However, this research direction, so far, has not been frequently reported. Given the gap in the current knowledge, this literature review aims to assess the possibility of BW and DW digestion in anaerobic reactors and provide up-to-date data on the post-treatment methods of effluent generated after the anaerobic digestion process. Despite numerous advantages, anaerobic treatment often requires post-effluent treatment to complete the treatment cycle. Full article

Olive mill wastes are some of the most important waste streams in Mediterranean countries, such as Greece, and their uncontrolled disposal without treatment imposes serious environmental impacts. In the last few decades, the European Union has defined the framework for a sustainable circular economy, aiming for viable waste treatment solutions. Under this scope, anaerobic digestion could be a remarkable solution for efficiently reducing waste organic matter and producing green energy, at the same time. In this study, the economic sustainability of an anaerobic digestion unit for olive mill effluents was assessed. It was found that a centralized treatment plant that can process liquid olive mill effluents during the olive harvesting season and other agro-industrial by-products (such as fruit and vegetable waste) for the rest of the year could be a viable solution, with waste capacities of 780 m³_OMW d⁻¹ and 245 kg_FVW d⁻¹. The internal rate of return was estimated at 6%, the net present value was estimated to be EUR 2 million, while the payback period was calculated to be 12 years. Furthermore, through the sensitivity analysis, the selling price of the electricity produced and the productivity of the waste processed in the plant alongside the olive mill wastewater were identified as the main factors affecting the viability of the process. The findings of this study can be applied in the development of a biomass-processing facility, taking into consideration the economic feasibility and the processing of challenging-to-treat wastes to generate green energy. Full article

In a zero-waste approach for the agro-industrial sector, this study aimed to evaluate the reuse of cheese whey wastewater (chemical oxygen demand = 2.1 g L⁻¹) pretreated by immediate one-step lime precipitation followed by natural carbonation as a nutritive solution for tomato production in hydroponic systems. Pretreated effluent, diluted with groundwater (1:6) and supplemented with nutrients, was utilized to irrigate different hydroponic systems designed to assess the influence of tomato rooting type (free/confined−setup_A) and the feed’s solution level (with/without water deep−setup_B). Plants and fruit development, fruit physicochemical characteristics and sensory analysis, and effluent quality after reuse were analyzed. Good quality tomato production with high crop yield was obtained. The highest marketable tomato weight per plant (682 g) was observed in setup_B with a deep-bed system, but setup_A, with free or confined rooting, presented similar values. The type of rooting, within setup_A or water deep within setup_B, did not significantly influence plant and fruit characteristics. The highest maturity and flavor indexes were observed for setup_A with free rooting. Regarding sensory analysis, setup_A often scored the highest in terms of overall appreciation with free or confined rooting. The reuse of cheese whey wastewater in hydroponics reduced freshwater consumption for crop production, allowed for a treated final effluent and prevented soil degradation in a sustainable circular economy methodology. Full article

This study, through the use of company data, offers an in-depth analysis of the current situation and future prospects of biogas plants and how they can promote economic advantages and environmental benefits. The geographical context of the Piana del Sele (Salerno, Italy) was chosen on the basis of objective criteria, including its relevance in the agro-industrial sector and the availability of accurate and reliable company data that was collected through IT systems, including software business performance monitoring and digital data analysis. This choice was fundamental to guaranteeing the validity and representativeness of our analyses and results. From a methodological point of view, mathematical formulas and algorithms were used, which allowed the calculation of the biogas producibility indices by type of biomass as well as the quantification of the effluents produced to then estimate the quantification of the biogas and the interconnected economic savings. Furthermore, this study uses the SWOT (strengths, weaknesses, opportunities, and threats) approach in an innovative way by integrating renewable energy communities into it. The aim is to demonstrate the potential of biogas plants and how energy communities can transform weaknesses and threats into opportunities. The results show that the integration of biogas plants into the farm environment offers considerable potential, and although it is a challenge for small and medium-sized farms, it could bring energy self-sufficiency and economic surplus. Furthermore, the integration of renewable energy communities would be able to promote the diversification of energy supply and transform weaknesses and threats into opportunities. Full article

Wine production generates a high volume of wastewater with a significant fraction of biodegradable organic matter that must be removed before safe release into surface waters. Aerobic sequencing batch reactors (SBRs) have been successfully applied in the treatment of a wide range of wastewaters. However, only a few studies have described the use of the SBR process for the treatment of winery wastewater (WW). The effectiveness of using an aerobic SBR process was investigated for the treatment of WW using two activated sludge concentrations (i.e., 2 and 4 g_VSS L⁻¹) and nutrient-supplemented conditions. In nutrient-deficient conditions, COD removal efficiencies varied between 70% and 97% depending on the organic loading rate (OLR). In nutrient-supplemented assays, COD removal efficiencies remained above 91% in all conditions tested. However, the effluent quality decreased due to the increase in the total suspended solids concentration. Furthermore, the COD concentration of the treated effluent was unable to meet legal requirements (<0.150 g L⁻¹) for safe wastewater discharge. Therefore, longer aeration periods and settling phases may be required in order to improve effluent quality under high organic loadings. Overall, these findings demonstrate the potential of SBR as a biological WW treatment process. Full article

The release of boron (B) into the environment as a result of anthropogenic activity modifies sustainable natural conditions, thus affecting ecosystems. To meet water quality regulations, commercial and natural boron adsorbents are available to reduce its concentrations in industrial effluents, with the former being not only more expensive but also less sustainable. In the publication, the biosorption parameters of carob kibbles (Ceratonia siliqua L.) were optimized in order to remove boron from aqueous solutions using batch experiments. The biosorbent used in the present research was agro-waste biomass provided by the local locust-beam gum industry. Boron removal by carob kibbles was favored at high initial pH values, and this capacity was found to be a function of boron initial concentration, biosorbent content in the solution, and particle size. The change in temperature did not affect the potential of biomass to remove boron. The highest boron removal efficiency (55.1%) was achieved under the following optimal conditions: 50 g/L biosorbent dose (Cs), with particle size range 0.025–0.106 mm, for the initial concentration (C₀) of boron in the solution of 100 mg/L, at an initial pH of 11.5, for 5 h at 25 °C. This investigation suggests that carob kibble agro-waste can be valorized as a biosorbent to remove boron from wastewater, and the boron-loaded residue may eventually be explored as a new boron-fertilizer. Full article