BIOGROUP

Permanent URI for this collectionhttps://hdl.handle.net/10347/34309

A misión do BIOGROUP é xerar coñecemento científico e tecnolóxico útil para o desenvolvemento sustentable da sociedade e capacitar persoal investigador emprendendor, promovendo sinerxías nunha contorna humana e estimulante.

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Iron oxide-mediated photo-Fenton catalysis in the inactivation of enteric bacteria present in wastewater effluents at neutral pH
(Elsevier, 2020-11) Fernández Fernández, Lucía; González-Rodríguez, Jorge; Gamallo Mirón, María; Vargas Osorio, Zulema; Vázquez Vázquez, Carlos; Piñeiro Redondo, Yolanda; Rivas Rey, José; Feijoo Costa, Gumersindo; Moreira Vilar, María Teresa; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Instituto de Materiais (iMATUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química; Universidade de Santiago de Compostela. Departamento de Química Física
The pressure on natural water resources associated with increasing water scarcity highlights the value of using reclaimed water through the development of efficient and environmentally friendly treatment technologies. In this work, the use of magnetic nanoparticles in photo-Fenton catalysis for water disinfection was considered to inactivate natural enteric bacteria present in municipal wastewater effluents under white light and neutral pH. The most recommended ranges were evaluated in key variables such as the loading and composition of nanoparticles (NPs), hydrogen peroxide (H₂O₂) concentration, the light source (UV and visible) and treatment time were evaluated in wastewater disinfection expressed in terms of total coliforms and Escherichia coli colony forming units (CFU). The magnetic separation of NPs allowed the disinfection process to be carried out in different cycles, facilitating the recovery of the nanocatalyst and avoiding its discharge with the treated effluent.
Design of biorefineries aligned with stakeholders’ preferences: How to select optimal valorization pathways?
(Elsevier, 2026-05-05) Koptelov, Maksim; Linck, Jan; Fereidani, Bahar M.; Leis Garrote, Isaac; Van der Hauwaert, Lucas; Dedieu, Isabelle; Sommer Schjønberg, Mias; Hospido Quintana, Almudena; Mauricio Iglesias, Miguel; Universidade de Santiago de Compostela. Departamento de Enxeñaría Química; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS)
Addressing agri-food waste accumulation via development of sustainable biorefineries is essential for advancing the circular bioeconomy. However, conflicting priorities of stakeholders, from feedstock producers to consumers and policymakers, are significant barriers that disrupt the selection of optimal valorization pathways. This study proposes a methodology to support early-stage biorefinery design by systematically integrating stakeholder preferences. Stakeholder insights are collected through qualitative data analysis (QDA) and translated into explicit design criteria, which are incorporated into the decision-making process. The approach combines multi-criteria decision analysis (MCDA) to identify optimal valorization pathways with life cycle assessment (LCA) to evaluate environmental performance. This enables the simultaneous consideration of economic and environmental objectives while ensuring alignment with stakeholder expectations. The proposed framework serves as a practical roadmap for decision-making in biorefinery design, providing specific recommendations for selecting sustainable and stakeholder-aligned valorization strategies.
Lactic acid unchained: enabling the LA platform with lactic acid production with high selectivity and titer
(2025) Regueira López, Alberte; Delmoitié, Brecht; Rabaey, Korneel; De Wever, Heleen; Sakarika, Myrsini; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
The LA (lactic acid) platform is an attractive biorefinery concept whereby organic wastes are converted into high-added value products. The first step is an open-culture fermentation to selectively convert sugar-rich wastes into concentrated LA streams (>40 g/L), followed by its transformation into different industrially relevant products such as bioplastics (i.e. PLA), biochemicals (e.g. medium chain carboxylic acids) or marketable green solvents (e.g. ethyl lactate). As nowadays LA is produced in pure-culture fermentations, we cannot apply the current know-how to develop the LA platform. Thus, our research focused on optimising LA production in mixed-culture fermentations using cheese whey permeate as model waste stream. We evaluated the effect of different operational parameters (temperature, pH and hydraulic retention time) to optimise jointly productivity, yield, concentration and community. Our findings revealed that operating at mildly thermophilic conditions (45°C) resulted in highly selective LA production, and significantly augmented the LA yield and productivity, compared to more typical higher temperatures (50-55°C). Also, circumneutral pH conditions (6.0-6.5) led to an improved performance compared to the conventional acid pH conditions (≤5.5), leading to an unprecedented LA productivity of 27.4 g/L/h (70.0% yield), which is over 2.5 times the previous maximum reported value in a CSTR (Sakarika et al., 2021). The process was composed at all conditions by a very lean microbial community, which underlies its stability. Overall, we showed that LA production with the requirements of a biorefinery scheme is feasible, setting the first stone of the LA platform path.
Pathway development for brewer’s spent grain valorization using multi-objective optimization
(Elsevier, 2026-04-29) Penedo Campos, Andrea; Yndgaard, Yeppe; Van der Hauwaert, Lucas; Mauricio Iglesias, Miguel; Hospido Quintana, Almudena; Errico, Massimiliano; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
Brewer’s spent grain (BSG) is a major biowaste stream in the European beer industry used for animal feed, biogas and landfilling. Its composition offers potential for producing a variety of value-added products, making it crucial to benchmark valorization technologies for better management. In response to this sectorial need, the study applies a methodological framework previously developed open-source OUTDOOR software to the brewing industry context. A multi-objective optimization was performed for a superstructure that includes all possible BSG valorization pathways, guiding decision-making in biorefinery design, and assessing the economic and environmental sustainability of the process. Beyond traditional valorization options, a comprehensive review of potential products and conversion pathways–including biological, thermochemical and extraction routes–was conducted based on biomass characterization. A Pareto efficiency analysis was applied to integrate the two optimization objectives, using earnings before interest and taxes (EBIT) and minimum selling price (MSP) to evaluate economic performance, and the carbon footprint analysis compliant with ISO 14067 to assess environmental impact. Results indicate animal feed as the most profitable route, with an EBIT approximately 10 % higher than the best second alternative (compost). Environmentally, compost exhibits the smallest carbon footprint, around 91 % lower than the next best option (biogas). Ethanol and hydrochar stood out for their environmental value and proximity to market competitiveness, based on MSP. An evaluation of cascade conversion strategies suggested that the combination of multiple valorization routes is only viable through synergies between pathways, i.e. if obtaining one product facilitates the remaining routes through increased yields or resource efficiencies.
Environmental Assessment of Olive Stone Valorisation: From Cultivation to Biorefinery
(2025-09-10) Agraso Otero, Adrián; Cortiñas, Sara; Rebolledo Leiva, Ricardo; González García, Sara; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
Life Cycle Assessment of Red Grape Production in La Rioja Designation of Origin
(2024-10-30) Agraso Otero, Adrián; Cancela Barrio, Javier José; Vilanova de la Torre, Mar; Ugarte Andreva, Javier; Rebolledo Leiva, Ricardo; González García, Sara; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química; Universidade de Santiago de Compostela. Departamento de Enxeñaría Agroforestal
Closing the loop in agriculture: life cycle assessment from manure to hydrogen and biofertilizer
(Elsevier, 2026-01-10) Tehseen, Arsal; Regueiro, Leticia; Feijoo Costa, Gumersindo; González García, Sara; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
Dairy sector accounts for 14–20 % of global greenhouse gas (GHG) emissions where the major emissions come from manure-management and fertilizers consumption. To address these hotspots, a closed-loop system is developed to valorise livestock manure for simultaneous hydrogen and fertilizer production, thereby fulfilling on-farm energy and nutrient needs. The system, modelled using SuperPro Designer®, consists of anaerobic digestion (AD) for biogas generation, followed by steam methane reforming and a water-gas shift reaction for hydrogen production. The digestate, enriched in nitrogen, phosphorus, and potassium, serves as a biofertilizer, reducing reliance on synthetic alternatives. Simulation results demonstrate that the system can meet the farm's energy demands and supply up to 32 % of its fertilizer requirements. Life Cycle Impact Assessment (LCA) was conducted using primary data from both the farm and the simulation model, employing an economic allocation approach within a cradle-to-gate boundary. The functional unit was defined as 1 kg of fat and protein corrected milk (FPCM). Two scenarios were evaluated: a conventional intensive dairy farm (Scenario-1) and the same farm with the proposed system (Scenario-2). Scenario-2 resulted in a significant shift in economic value towards hydrogen (63.01 %) and achieved a 66 % reduction in global warming potential per kg of FPCM without compromising milk yield. These results highlight the potential of integrated manure valorisation systems to promote circularity and reduce the environmental footprint of dairy farming. However, there is a need to study the feasibility and scalability of this approach for different farms, climatic-regions and geographical constraints.
Raw used cooking oil valorization into polyhydroxyalkanoates by mixed microbial cultures: evaluation of one- and two-unit configuration
(Elsevier, 2026-02-24) Ucha Muñoz, Carlota; Martínez Rey, Sara; Correa Galeote, David; Pedrouso Fuentes, Alba; Mosquera Corral, Anuska; Val del Río, Ángeles; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
The production of polyhydroxyalkanoates with untreated used cooking oil (UCO) as substrate represents an interesting strategy to valorize this residue into a value-added product. Three sequencing batch reactors (R1, R2, and RA) were operated, using mixed microbial cultures (MMCs) fed with raw UCO. R1 and R2 operated as enrichment units, with withdrawal at the end of the feast and famine phases, respectively. Enrichment was achieved in both within 30 days, reaching similar accumulations of the copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) (17.76 wt. % in R1 and 12.47 wt. % in R2). To improve process stability and reduce chemical consumption for pH control, urea was evaluated as nitrogen source, resulting in a reactor less dependent on pH control and increasing PHBV content from 16.7 to 25.7 wt. %. Then, the accumulation unit (RA) was operated in series with R1 to evaluate the maximum PHBV production of the biomass and compare the one-unit (R1) and two-unit (R1 + RA) configurations. Different hydraulic retention times (HRTs) were studied for the one-unit (24 and 48 h) and the two-unit (48 and 96 h) configurations. The best overall performance was observed at an HRT of 48 h in both cases, with similar accumulations (44.8–49.1 wt. % PHBV), yields (230–250 g PHBV/kg UCO) and productivities (0.010–0.013 g PHBV/(L·h)), showing that the one-unit was the best strategy for its operational simplicity. These results demonstrate the feasibility of enriching MMCs to produce PHBV using raw UCO, highlighting the potential of one-unit configuration to perform enrichment and accumulation steps in the same reactor.
Comparative assessment of two bioproducts using quantitative image analysis
(Elsevier, 2026-02-03) Ucha Muñoz, Carlota; Val del Río, Ángeles; Pedrouso Fuentes, Alba; Mosquera Corral, Anuska; Mesquita, Daniela P.; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
Polyhydroxyalkanoates (PHA) and triacylglycerides (TAG) could be used as bioplastic and precursors of biodiesel, respectively. To ensure a more controlled and efficient operation of the reactor, rapid monitoring of bioproducts accumulation is essential for enabling precise process adjustments and efficiency. Usually, gas chromatography (GC) or high-performance liquid chromatography (HPLC) are the methods used for bioproduct quantification, but these are hazardous and labor-intensive techniques. In this context, quantitative image analysis (QIA) emerges as a rapid and non-hazardous alternative for bioproducts quantification. The present work investigates the application of QIA for the simultaneous quantification of PHA and TAG in a mixed microbial culture fed with used cooking oil (UCO). Three stains were evaluated: Sudan Black B (SBB), Nile Blue A (NBA), and BODIPY. The data obtained from the images acquired were processed using multivariate statistical methods, specifically Partial Least Squares (PLS) and Multilinear Regression (MLR). Overall, SBB tended to show comparatively better predictive performance, particularly for PHA, while PLS models generally demonstrated more favourable performance than MLR. However, none of the tested stains were effective in quantifying TAG, likely due to the concentration of data around a limited range, which hindered the model´s ability to predict this bioproduct. Simultaneous quantification of both products (PHA+TAG) resulted in moderate model performance (R2 ≈ 0.57–0.89), without improving the predictive accuracy of PHA quantification alone. These findings support the potential of image-based techniques for intracellular bioproduct quantification, while also highlighting the need for a larger and more diverse dataset to enhance model prediction accuracy and robustness.
Assessing environmental impacts and ecosystem services of Hops crop in Galicia, NW Spain: critical contributors for sustainable cultivation strategies
(Springer, 2026-03-17) Agraso Otero, Adrián; Cancela Barrio, Javier José; Fandiño Beiro, María; Rebolledo Leiva, Ricardo; González García, Sara; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Agroforestal; Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
Hops (Humulus lupulus) is a crop of great interest due to its use in the brewing industry; however, the environmental impacts associated with its cultivation remain largely unexplored. Therefore, this study provides the first evaluation of the environmental performance of hops cultivation using the Life Cycle Assessment methodology, with a case study of Galicia, NW Spain. The system boundaries, following a cradle-to-farm-gate approach, included all field operations throughout its entire lifespan (20 years), with primary data obtained directly from farmers. Impact categories such as Global Warming, Eutrophication, Ecotoxicity and Water Scarcity were considered. The main environmental hotspots identified were irrigation, due to the high crop water requirements, followed by agrochemical production and the associated on-field emissions. The results showed impacts of 3.05 kg CO₂ eq in global warming, 35.35 g SO₂ eq in terrestrial acidification or 70.3 m3 in water scarcity per kilogram of dry hop cones. Agricultural activities exert pressure on our natural ecosystems in different ways, for example, globally through the propagation of emissions or locally through the degradation of species-rich landscapes, with plants being the most affected taxon in this case. Moreover, two ecosystem services were assessed: pollination and soil erosion. Pollinator presence was found to be constant throughout spring and summer, with a ratio close to 50% of the regional maximum, while the effects of soil erosion control were estimated at €838 over the 20-year lifespan of the crop. With these results, the environmental performance of hop cultivation can be significantly improved, paving the way for more sustainable products within the brewing industry.
Comparison of vibrational spectroscopy methods for real-time monitoring of anaerobic fermentation
(2024) Fuente Mariño, Manuel de la; Bouzas Fernández, Miguel; Cubero Cardoso, Juan; Mauricio Iglesias, Miguel; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
A central idea in the transition to a circular economy is to recover resources from wastes. An emerging biorefinery for carbon recovery from waste streams focuses on the production of carboxylates or volatile fatty acids (VFA) by anaerobic fermentation. VFA have value on their own but also as precursors to other chemicals, biofuels and biopolymers constituting the so-called carboxylate platform. A challenge in the development of the carboxylate platform is the poor selectivity in a given VFA (e.g. acetic, propionic, butyric acid…) and the lack of thorough understanding of how changes in operational conditions (pH, retention time, substrate nature and concentration) have an impact on the VFA produced. Currently, the analysis of products, often present in aqueous solutions at moderate/low concentrations, tends to be done by gas chromatography (GC) or high-performance liquid chromatography (HPLC) which prevents real-time or near real-time monitoring. Spectroscopic methods can enable faster monitoring rates if configured at-, in- or online. The interest on vibrational spectroscopy (Raman, infrared) has steadily grown in the last 15 years thanks to the decreasing cost of the monitoring equipment. The potential of vibrational spectroscopy in anaerobic fermentation monitoring lies in the possibility of quantifying the main metabolites and substrates (e.g. glucose, ethanol, starch, amino acids). However, there are important challenges too: a major obstacle for infrared spectroscopy in bioprocess monitoring lies in its high sensitivity to water with high bands that overlap other analytes. In contrast, Raman spectroscopy is particularly interesting for bioprocesses, precisely, because water is mostly Raman inactive. However, a large number of molecules present in mixed-cultures lead to fluorescence in Raman. In this work, we compare the capability of Fourier-Transform Infrared (FTIR) and Raman spectroscopies to effectively monitor the main metabolites of anaerobic fermentation. Aqueous mixtures containing acetic, propionic and butyric acid (n = 30; range 0,1 g/L to 20 g/L) were prepared with concentrations designed by latin hypercube sampling as described by Cabaneros-Lopez et al. (2020) to ensure high coverage of the sampling space while keeping at minimum in-sample correlation. The mixtures were measured by Attenuated-Total Reflectance (ATR) FTIR in the medium infrared range and by Raman spectroscopy between 95 and 3500 cm-1 Raman shift wavenumber using a 785 nm excitation laser. Spectra were preprocessed (baseline correction, Savitzky-Golay noise filtering) and used as input for several chemometric models. Spectra were split in calibration (20 samples) and validation (10 samples) sets. Partial least square (PLS) models for each of the analytes were finally selected based on the goodness of fit for the calibration and validation models (Figure 1) for the three analytes. Acetic and propionic acid were satisfactorily estimated while butyric acid estimation is being improved. Despite the influence of water in the obtained spectra, FTIR results were superior to Raman spectroscopy results for the three analytes at all range. When tested in the fermentation media using glucose as a substrate, Raman spectroscopy led to severe fluorescence phenomena, hence preventing an accurate estimation of the VFA in the solution. (data not shown). Infrared spectroscopy was hence selected for VFA monitoring. Upcoming work will deal with the combined use of mathematical models, in particular observers (e.g. nonlinear versions of Kalman filters) to integrate the information obtained by spectroscopy with models of anaerobic fermentation (Regueira et al. 2021) in order to integrate all the available information
Real time monitoring of anaerobic fermentation by Raman and FTIR spectroscopy
(2025) Bouzas Fernández, Miguel; Fuente Mariño, Manuel de la; Cubero Cardoso, Juan; Mauricio Iglesias, Miguel; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
A major challenge in carbon recovery through the carboxylate platform is the poor selectivity of anaerobic fermentation in a given carboxylate (e.g. acetate, propionate, butyrate…). Furthermore, our understanding of how changes in fermentation (pH, retention time, substrate concentration…) may be used to steer the fermentation to a targeted product is limited. Vibrational spectroscopy methods (i.e. Raman and FTIR) can be used for real-time process monitoring by estimation of fermentation metabolites and, in some cases, substrate uptake. Combined with process mathematical models, it is possible to obtain real-time evaluation of the fermentation state and propose corrective actions
Monitorización de procesos de fermentación anaerobia mediante espectroscopía infrarroja y Raman
(2024) Fuente, Manuel de la; Cubero Cardoso, Juan; Mauricio Iglesias, Miguel; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
La recuperación de carbono orgánico de las aguas residuales y residuos orgánicos en ácidos grasos volátiles (AGV) es una estrategia prometedora ya que permite su valorización posterior como productos químicos, biopolímeros y biocombustibles. Un obstáculo importante en el desarrollo de la fermentación anaerobia es la dificultad para monitorizar cambios dinámicos y detectar problemas de inhibición o contaminación. En el proyecto WATCHER (CNS2022-135594, Agencia Estatal de Investigación) se aborda la monitorización de la fermentación anaerobia mediante espectroscopía infrarroja (IR) y Raman en línea, siendo ambas espectroscopías vibracionales, adecuadas para seguir en tiempo real los AGV y otros metabolitos. Al poder identificar la “huella dactilar” de los compuestos, las espectroscopías vibracionales son altamente específicas aunque tienen una sensibilidad limitada. En el marco del desarrollo de las técnicas de monitorización, se realizaron tests de calibración, primero en agua y posteriormente en medio de fermentación que fueron analizados tanto en IR como en Raman. Para ello, se realizaron mezclas simultáneas de ácidos acético, propiónico y butírico (rango 0,1 g/L – 20 g/L) diseñadas mediante muestreo de hipercubos latino para asegurar una alta cobertura del espacio muestral manteniendo una mínima correlación entre los analitos. Se compararon diversos modelos quimiométricos para cada analito, optando por modelos PLS (Projection on Latent Structures) con un número bajo de variables latentes. El trabajo en curso actual se basa en incluir la determinación de diversos sustratos de fermentación de forma simultánea. A pesar de la influencia del agua en el espectro obtenido, la espectroscopía IR demostró ser superior a la espectroscopía Raman para los tres analitos en todo rango de concentración, en particular para la estimación de ácido butírico. Para los análisis en medio de fermentación (sustrato glucosa), la espectroscopía Raman dio lugar a fenómenos de fluorescencia, resultando en un obstáculo importante para el uso de esta técnica en cultivos mixtos. La espectroscopía IR fue seleccionada para su combinación con modelos matemáticos de fermentación anaerobia con el objetivo de proporcionar un sistema de monitorización avanzada en tiempo real.
Eco-efficiency analysis of a continuous two-phase partitioning bioreactor treating 2,4-dichlorophenol synthetic wastewater
(Elsevier, 2026-02-06) Estévez Rivadulla, Sofía; Mosca Angelucci, Domenica; Moreira Vilar, María Teresa; Tomei, Maria Concetta; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
Continuous two-phase partitioning bioreactors are a promising solution for removing poorly biodegradable pollutants, such as phenolic compounds, from wastewater. However, their combined economic and environmental feasibility has not yet been jointly evaluated, and it is crucial to ensure a minimum incorporation of sustainability aspects during design. For this purpose, four methodologies were employed. Standalone analyses were first conducted using Life Cycle Assessment and Life Cycle Costing, followed by an integrated environmental–economic sustainability assessment. The latter consisted of an eco-efficiency approach and a qualitative evaluation based on the principles of the EU Taxonomy, which functions as a key instrument within the European sustainable legal framework. The methodologies were applied to four scenarios in which the concentrations of 2,4-dichlorophenol, as targeted model phenolic compound, in the influent and the recycling ratio of the treated effluent were varied. The findings revealed that integrating recycling within the reactor resulted in a significant environmental burden across categories, with exception of ecotoxicity (with 98.2% decrease). Although the technology successfully achieved its removal objectives, the higher consumption of utilities required for proper reactor operation reduced the expected benefits. As for operating expenses, differences between scenarios were minimal due to the dominance of fixed costs, which remain constant in all cases. Comparatively, the technology aligned with performance metrics found in existing literature (around 13.7 kg CO2eq./m3 of treated wastewater and costs above 7.62 €/m3). To enhance the competitiveness of the technology, it is essential to manage energy demands for heating and aeration and to increase process automation, thereby reducing associated labor costs
Potato peel integrated biorefinery design for succinic acid and bioethanol production: technoeconomic and environmental analysis
(Elsevier, 2026-01-23) Rodríguez Martínez, Beatriz; Agraso Otero, Adrián; Rebolledo Leiva, Ricardo; Yáñez Díaz, María Remedios; Gullón Estévez, Beatriz; González García, Sara; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
The increasing demand for energy and chemical products, coupled with the depletion of fossil resources, underscores the need for sustainable biorefinery alternatives. Potato peel (PP), an abundant agro-industrial residue, represents a promising feedstock due to its valuable biochemical composition. This study evaluates two PP valorization strategies: (i) Scenario 1, involving the microbial fermentation for the production of succinic acid (SA), and (ii) Scenario 2, a coupled system integrating bioethanol production where CO2 emitted during bioethanol fermentation is reutilized as a substrate for SA synthesis. A techno-economic analysis (TEA) and life-cycle assessment (LCA) were conducted using SuperPRO designer process simulation, experimentally validated yields, literature-derived kinetic data, and cost estimations based on a 30-year plant lifetime. Scenario 1 yielded a minimum selling price (MSP) of $3.77 per kg of SA, along with a net present value (NPV) of $81.35 million and an internal rate of return (IRR) of 11.21 %, confirming its economic feasibility. In contrast, Scenario 2 resulted in negative NPV values and significantly higher MSPs for both SA and bioethanol, indicating that economic feasibility was not achieved under the current assumptions. However, Scenario 2 exhibited superior environmental performance, achieving more than a 20 % reduction in global warming potential (GWP) and fossil resource use per metric ton of PP processed. Sensitivity analysis showed that SA market price and fixed capital investment were the dominant parameters influencing profitability in both scenarios. Overall, while Scenario 1 is the economically preferable option, Scenario 2 highlights the environmental benefits of incorporating carbon-reuse strategies into emerging biorefineries
Uncovering the environmental and economic feasibility of an integral tomato-based biorefinery for obtaining pectin and seed oil
(Elsevier, 2025-12-11) Agraso Otero, Adrián; Rebolledo Leiva, Ricardo; González García, Sara; Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
The combination of life cycle assessment and techno-economic analysis enables the evaluation of a biorefinery’s viability from both environmental and economic perspectives. This is particularly relevant for valorising food industry by-products within the framework of a circular economy. This study focuses on the integral valorisation of tomato pomace by separating seeds and skins to obtain oil and pectin, respectively. For each valorisation route, two technologies were assessed: cold pressing and supercritical CO₂ extraction for seeds, and acid extraction and ultrasound-assisted extraction for peels. Of these, cold pressing and acid extraction were identified as the best options in terms of environmental performance and yield for seeds and for peels, respectively. The corresponding emissions were 33.6 kg CO₂ eq and 0.08 kg SO₂ eq per kg of oil, and 44.8 kg CO₂ eq and 0.12 kg SO₂ eq per kg of pectin, for global warming and terrestrial acidification respectively. These impacts could be significantly reduced by modifying the heat source, identified as the system’s main hotspot. Economically, the biorefinery with the best environmental performance was not profitable under current conditions. However, sensitivity analysis showed that improving oil yield by a factor of 2.6 through technological adjustments could lead to economic viability. These findings provide valuable insights for stakeholders and policymakers seeking sustainable solutions for food waste management, supporting both environmental responsibility and techno-economic feasibility.
Assessing the economic viability, environmental sustainability, and scalability of microbial protein from cheese whey permeate in Europe
(Elsevier, 2026-01-08) Delmoitié, Brecht; Regueira López, Alberte; De Wever, Heleen; Ganigué, Ramon; Sakarika, Myrsini; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
Cheese whey permeate (CWP), a nutrient-rich by-product of the dairy industry, holds untapped potential for conversion into microbial protein (MP). This study presents a comprehensive techno-economic analysis and life cycle assessment (LCA) of two distinct MP production routes from CWP: a one-step conversion of lactose to MP, and a two-step route involving lactic acid fermentation prior to MP production. Furthermore, centralised and decentralised MP production systems were compared based on CWP spatial distribution, valorisation scale, and logistical constraints. The two-step MP production, despite higher capital and raw material inputs, achieved the lowest minimum selling price (MSP) of 3.9–5.0 €/kgprotein. This MSP makes the two-step MP production route competitive with other food-grade protein sources, including plant-based (2.5–9.2 €/kgprotein) and animal-based sources (5.9–13.5 €/kgprotein). According to the LCA, the two-step configuration demonstrated a 95.7–99.3% lower overall environmental burden than animal-derived proteins (beef, pork, chicken) and outperformed plant-based alternatives such as pea protein. Decentralised MP production at 100 ton CWP/h emerged as the most viable scale due to reduced MSP and compatibility with mid-sized cheese producers. Centralised production was restricted in scale due to the heterogeneous distribution of CWP across Europe. Valorisation of 80% of Europe's CWP into food-grade MP through decentralised facilities could replace up to 7.2% of the European animal protein needs and substantially reduce the environmental impact. This work provides key insights into economic feasibility, environmental sustainability, and deployment strategies for MP production from CWP, highlighting its potential as an alternative protein source.
Thermophilic caproic acid production from grass juice by sugar-based chain elongation
(Elsevier, 2022) Sakarika, Myrsini; Regueira López, Alberte; Rabaey, Korneel; Ganigué, Ramon; Universidade de Santiago de Compostela. Departamento de Enxeñaría Química; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS)
Medium chain carboxylic acids (MCCA) such as caproic acid have a plethora of applications, ranging from food additives to bioplastics. MCCA can be produced via microbial chain elongation using waste and side-streams as substrates, a process that can be more sustainable than conventional production routes. Most chain elongation studies have focused on mesophilic conditions, with only two recent studies hinting at the possibility of thermophilic chain elongation, but a systematic study of its mechanisms is lacking. Here, we investigated thermophilic chain elongation from grass juice, to understand the effect of key operational parameters (pH, temperature, substrate) on the process performance and to establish the key microbial genera and their role in the system. The genus Caproiciproducens was identified as responsible for thermophilic chain elongation, and caproic acid production was most favorable at pH 6.0 and 50 °C among the conditions tested, reaching an average concentration of 3.4 g/L. Batch experiments showed that the substrate for caproic acid production were glucose and xylose, while lactic acid led to the production of only butyric acid. Fed-batch experiments showed that substrate availability and the presence of caproic acid in the system play a major role in shaping the profile of thermophilic chain elongation. The increase of the total sugar concentration by glucose addition (without changing the organic load) during continuous operation led to a microbial community dominated (75 %) by Caproiciproducens and increased by 76 % the final average caproic acid concentration to 6.0 g/L (13 gCOD/L) which represented 32 % (g/g) of the total carboxylic acids. The highest concentration achieved was 7.2 g/L (day 197) which is the highest concentration reported under thermophilic conditions thus far. The results of this work pave the way to the potential development of thermophilic systems for upgrading various underexplored abundant and cheap sugar-rich side-streams to caproic acid.
Enhancing carbon capture and utilization: mixotrophic growth of Clostridium luticellarii using methanol and hydrogen for efficient CO2 reduction
(Elsevier, 2025-12-25) Quinten, Mariën; Regueira López, Alberte; Petrognani, Camille; Scarborough, Matthew; Ganigué, Ramon; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS)
Carbon capture and utilization remains a major challenge in mitigating climate change. Carbon dioxide (CO2) fixing microorganisms offer promising routes to convert CO2 emissions into valuable products. Clostridium luti-cellarii is a recently discovered acetogen capable of converting CO2 to acetic, butyric and isobutyric acids using H2 or methanol as electron donors. Both routes can use renewable electricity as primary energy input, but each has its limitations: While H2-based processes suffer from poor gas-to-liquid mass transfer and low product selectivity beyond acetic acid, methanol requires a preliminary energy-intensive catalytic reduction of CO2. This study investigated the growth of C. luticellarii on both substrates to compensate their respective drawbacks. Combining methanol and H2 resulted in mixotrophic growth and enhanced CO2 assimilation up to four-fold compared to conversion of methanol alone, while producing similar product spectra. Thermodynamic pathway analysis suggested that high H2 pressures inhibit the H2-producing formate oxidation, while pathways with alternative electron carriers remain favorable. Subsequently, a metabolic model of the one-carbon catabolism was constructed and used to perform flux balance analysis. This revealed that H2 oxidation during mixotrophic growth augments the intracellular pool of reducing equivalents, reducing the need for methanol oxidation and increasing net CO2 assimilation into products. These findings highlight the potential of combining methanol and H2 as electron donors to improve CO2 conversion efficiency for the sustainable production of butyric and isobutyric acids.
Inclusive by design? Rethinking sustainability standards and certification schemes for smallholders
(Elsevier, 2025-10-24) Carballido Nogueira, Aroa; Arias Calvo, Ana; Ares Sainz, Jose Luis; Feijoo Costa, Gumersindo; Moreira Vilar, María Teresa; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Enxeñaría Química
The transition to more sustainable models requires the active participation of all stakeholders in value chains. Although large producers tend to bear the majority of environmental, economic and social burdens, small producers also play a vital role in promoting sustainability and circularity. However, their ability to adapt and adopt technological innovations is often limited by narrower profit margins. Therefore, sustainability requirements must be applied flexibly and proportionately to small producers, without underestimating any criteria, while encouraging compliance wherever possible. Currently, most standards and certification schemes do not differentiate between actors in the value chain, focusing mainly on large producers. In this context, this manuscript aims to identify and propose a set of requirements tailored to small producers, using an integrated approach encompassing environmental, economic, social and circular sustainability. Various key certification schemes were used as the basis for defining evaluation indicators. The manuscript also introduces a scoring methodology that combines three complementary evaluation methods: (i) evaluation of the quality of certification schemes, (ii) evaluation of the minimum requirements applicable to small producers and (iii) evaluation of the suitability and practical applicability of the indicators. Thus, this manuscript aims to facilitate the meaningful integration of small producers into sustainable and circular development trajectories.

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