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Programme","award":["UIDB\/04129\/2020"],"award-info":[{"award-number":["UIDB\/04129\/2020"]}]},{"name":"FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia, I.P.","award":["731101"],"award-info":[{"award-number":["731101"]}]},{"name":"FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia, I.P.","award":["BBRI-LISBOA-01-0145-FEDER-022059"],"award-info":[{"award-number":["BBRI-LISBOA-01-0145-FEDER-022059"]}]},{"name":"FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia, I.P.","award":["PORTUGAL2020"],"award-info":[{"award-number":["PORTUGAL2020"]}]},{"name":"FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia, I.P.","award":["Norte2020"],"award-info":[{"award-number":["Norte2020"]}]},{"name":"FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia, I.P.","award":["UIDB\/04129\/2020"],"award-info":[{"award-number":["UIDB\/04129\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Energies"],"abstract":"<jats:p>This work proposes a valorization route for spent coffee grounds (SCG), a widespread lignocellulosic residue, encompassing the production of: biomethane, lignin, and oligosaccharides as value-added products obtained simultaneously during a mild alkaline (NaOH) pretreatment. The studied operational variables were the reaction time (60\u2013240 min), temperature (25\u201375 \u00b0C), and the NaOH concentration (0\u20132.5 M). The severity factor suitably describes the global process kinetics, with higher severities (log Mo = 5.5) yielding high product yields, 18.02% and 13.25% (on dry SCG basis) for lignin and oligosaccharides (XGMOS), respectively. Solid yield is negatively impacted by all studied variables (at the 95% confidence level). Conversely, XGMOS yield is positively influenced both by time and catalyst concentration, whereas lignin yield is only (positively) influenced by catalyst concentration. Optimal balance between product formation and potential operational costs is putatively achieved when using 0.625 M NaOH, at 50 \u00b0C for 60 min. The mild alkaline pretreated biomass (MAP-SCG) was compared to untreated SCG for biomethane production by anaerobic co-digestion with pig slurry (PS), using a ratio of biomass\/PS = 1\/3 (volatile solids (VS) basis). The proposed valorization route enabled the sequential production of 6.25 kg lignin, 6.36 kg oligosaccharides, and 138.05 kg biomethane per 100 kg of non-extracted SCG (and 287.60 kg pig slurry), in an integrated process that is technically feasible and promotes the circular bioeconomy.<\/jats:p>","DOI":"10.3390\/en16093907","type":"journal-article","created":{"date-parts":[[2023,5,5]],"date-time":"2023-05-05T08:12:11Z","timestamp":1683274331000},"page":"3907","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["The Role of Mild Alkaline Pretreatment in the Biorefinery Upgrade of Spent Coffee Grounds"],"prefix":"10.3390","volume":"16","author":[{"given":"Gabriel Mota","family":"Ribeiro","sequence":"first","affiliation":[{"name":"Unidade de Bioenergia e Biorrefinarias, LNEG\u2014Laborat\u00f3rio Nacional de Energia e Geologia, Estrada do Pa\u00e7o do Lumiar, 22, 1649-038 Lisboa, Portugal"},{"name":"LEAF\u2014Linking Landscape, Environment, Agriculture and Food Research Center, Associated Laboratory TERRA, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal"}]},{"given":"Pedro L.","family":"Martins","sequence":"additional","affiliation":[{"name":"Unidade de Bioenergia e Biorrefinarias, LNEG\u2014Laborat\u00f3rio Nacional de Energia e Geologia, Estrada do Pa\u00e7o do Lumiar, 22, 1649-038 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5641-8965","authenticated-orcid":false,"given":"Ana Cristina","family":"Oliveira","sequence":"additional","affiliation":[{"name":"Unidade de Bioenergia e Biorrefinarias, LNEG\u2014Laborat\u00f3rio Nacional de Energia e Geologia, Estrada do Pa\u00e7o do Lumiar, 22, 1649-038 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0270-4832","authenticated-orcid":false,"given":"Florbela","family":"Carvalheiro","sequence":"additional","affiliation":[{"name":"Unidade de Bioenergia e Biorrefinarias, LNEG\u2014Laborat\u00f3rio Nacional de Energia e Geologia, Estrada do Pa\u00e7o do Lumiar, 22, 1649-038 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2957-7340","authenticated-orcid":false,"given":"Rita","family":"Fragoso","sequence":"additional","affiliation":[{"name":"LEAF\u2014Linking Landscape, Environment, Agriculture and Food Research Center, Associated Laboratory TERRA, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5820-3669","authenticated-orcid":false,"given":"Lu\u00eds C.","family":"Duarte","sequence":"additional","affiliation":[{"name":"Unidade de Bioenergia e Biorrefinarias, LNEG\u2014Laborat\u00f3rio Nacional de Energia e Geologia, Estrada do Pa\u00e7o do Lumiar, 22, 1649-038 Lisboa, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2023,5,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"125952","DOI":"10.1016\/j.biortech.2021.125952","article-title":"Biodiesel, biogas and fermentable sugars production from spent coffee grounds: A cascade biorefinery approach","volume":"342","author":"Battista","year":"2021","journal-title":"Bioresour. Technol."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Teixeira, R.A., Bueno, B.A., Borges, R.M., and Bringhenti, J.R. (2021). Biochemical methane potential of spent coffee grounds via co-digestion with food waste. Bioenerg. Res., 1\u201312.","DOI":"10.1007\/s12155-021-10351-8"},{"key":"ref_3","first-page":"100029","article-title":"The circular bioeconomy: Its elements and role in European bioeconomy clusters","volume":"6","author":"Stegmann","year":"2020","journal-title":"Resour Conserv Recycl X"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"155113","DOI":"10.1016\/j.scitotenv.2022.155113","article-title":"Towards the sustainable and circular bioeconomy: Insights on spent coffee grounds valorization","volume":"833","author":"Gebreeyessus","year":"2022","journal-title":"Sci. Total Environ."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"569","DOI":"10.1016\/j.nbt.2015.02.008","article-title":"Biotechnological conversion of spent coffee grounds into polyhydroxyalkanoates and carotenoids","volume":"32","author":"Obruca","year":"2015","journal-title":"New Biotechnol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"100592","DOI":"10.1016\/j.scp.2021.100592","article-title":"Recovery of phenolic compounds from spent coffee grounds through optimized extraction processes","volume":"25","author":"Solomakou","year":"2022","journal-title":"Sustain. Chem. Pharm."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.jfoodeng.2016.11.014","article-title":"Optimization of autohydrolysis conditions to extract antioxidant phenolic compounds from spent coffee grounds","volume":"199","author":"Ballesteros","year":"2017","journal-title":"J. Food Eng."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"258","DOI":"10.1016\/j.carbpol.2016.09.054","article-title":"Extraction of polysaccharides by autohydrolysis of spent coffee grounds and evaluation of their antioxidant activity","volume":"157","author":"Ballesteros","year":"2017","journal-title":"Carbohydr. Polym."},{"key":"ref_9","unstructured":"Stahl, H., and Turek, E. (1991, January 14\u201319). Acid-hydrolysis of spent coffee grounds to produce D-mannose and D-mannitol. Proceedings of the Fourteenth International Conference on Coffee Science, San Francisco, CA, USA."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"449","DOI":"10.1002\/jctb.4313","article-title":"Spent coffee ground mass solubilisation by steam explosion and enzymatic hydrolysis","volume":"90","author":"Chiyanzy","year":"2015","journal-title":"J. Chem. Technol. Biot."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"2565","DOI":"10.1007\/s12649-017-0033-8","article-title":"Spent coffee grounds alkaline pre-treatment as biorefinery option to enhance their anaerobic digestion yield","volume":"9","author":"Girotto","year":"2018","journal-title":"Waste Biomass Valor."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1000","DOI":"10.1016\/j.renene.2020.12.095","article-title":"Effect of methanol-organosolv pretreatment on anaerobic digestion of lignocellulosic materials","volume":"169","author":"Oliva","year":"2021","journal-title":"Renew Energ."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"405","DOI":"10.1016\/j.biortech.2015.09.115","article-title":"Methane enhancement through oxidative cleavage and alkali solubilization pre-treatments for corn stover with anaerobic activated sludge","volume":"200","author":"Hassan","year":"2016","journal-title":"Bioresour. Technol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"115157","DOI":"10.1016\/j.indcrop.2022.115157","article-title":"An integrated olive stone biorefinery based on a two-step fractionation strategy","volume":"187","author":"Carvalheiro","year":"2022","journal-title":"Ind. Crops Prod."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"62","DOI":"10.1016\/j.apenergy.2012.10.060","article-title":"A comparison of different pre-treatments to increase methane production from two agricultural substrates","volume":"104","author":"Sambusiti","year":"2013","journal-title":"Appl. Energ."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1194","DOI":"10.1016\/j.biortech.2017.08.182","article-title":"Pretreatment of agricultural biomass for anaerobic digestion: Current state and challenges","volume":"245","author":"Paudel","year":"2017","journal-title":"Bioresour. Technol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"104","DOI":"10.1016\/j.indcrop.2016.10.017","article-title":"Selective single-stage xylan-to-xylose hydrolysis and its effect on enzymatic digestibility of energy crops giant reed and cardoon for bioethanol production","volume":"95","author":"Shatalov","year":"2017","journal-title":"Ind. Crops Prod."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1007\/s12649-016-9813-9","article-title":"Direct dilute acid hydrolysis of spent coffee grounds: A new approach in sugar and lipid recovery","volume":"9","author":"Pabiloa","year":"2018","journal-title":"Waste Biomass Valor."},{"key":"ref_19","first-page":"181","article-title":"Optimization of coffee oil extraction from spent coffee grounds using four solvents and prototype-scale extraction using circulation process","volume":"51","author":"Somnuk","year":"2017","journal-title":"Agric. Nat. Resour."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"131730","DOI":"10.1016\/j.chemosphere.2021.131730","article-title":"A state-of-the-art review on spent coffee ground (SCG) pyrolysis for future biorefinery","volume":"286","author":"Atabani","year":"2022","journal-title":"Chemosphere"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2401","DOI":"10.30638\/eemj.2018.238","article-title":"Spent coffee grounds from coffee vending machines as feedstock for biogas production","volume":"17","author":"Vasmara","year":"2018","journal-title":"Environ. Eng. Manag. J."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1016\/j.fuel.2012.10.019","article-title":"Gaseous products and particulate matter emissions of biomass residential boiler fired with spent coffee grounds pellets","volume":"107","author":"Limousy","year":"2013","journal-title":"Fuel"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"695","DOI":"10.1007\/s10163-017-0621-5","article-title":"The broad spectrum of possibilities for spent coffee grounds valorisation","volume":"20","author":"Girotto","year":"2018","journal-title":"J. Mater. Cycles Waste"},{"key":"ref_24","unstructured":"van Dam, J.E., and Harmsen, P. (2010). Coffee Residues Utilization."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1462","DOI":"10.1016\/j.rser.2011.11.035","article-title":"Methane production from lignocellulosic agricultural crop wastes: A review in context to second generation of biofuel production","volume":"16","author":"Chandra","year":"2012","journal-title":"Renew Sust. Energ. Rev."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"125296","DOI":"10.1016\/j.fuel.2022.125296","article-title":"Valorization of spent coffee grounds for biogas production: A circular bioeconomy approach for a biorefinery","volume":"328","author":"Mahmoud","year":"2022","journal-title":"Fuel"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"121594","DOI":"10.1016\/j.biortech.2019.121594","article-title":"Co-feeding spent coffee grounds in anaerobic food waste digesters: Effects of co-substrate and stabilization strategy","volume":"288","author":"Kim","year":"2019","journal-title":"Bioresour. Technol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"4613","DOI":"10.1007\/s12649-019-00796-6","article-title":"Anaerobic co-digestion of pig manure and spent coffee grounds for enhanced biogas production","volume":"11","author":"Orfanoudaki","year":"2020","journal-title":"Waste Biomass Valor."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"164","DOI":"10.1186\/1754-6834-6-164","article-title":"Total solids content: A key parameter of metabolic pathways in dry anaerobic digestion","volume":"6","author":"Motte","year":"2013","journal-title":"Biotechnol. Biofuels"},{"key":"ref_30","unstructured":"Sluiter, A., Hames, B., Ruiz, R., Scarlata, C.J., Sluiter, J., and Templeton, D. (2008). Determination of Sugars, Byproducts, and Degradation Products in Liquid Fraction Process Samples, National Renewable Energy Laboratory. NREL\/TP-510-42623."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"739","DOI":"10.1016\/j.nbt.2010.05.003","article-title":"Lignocellulose pretreatment severity\u2014Relating pH to biomatrix opening","volume":"27","author":"Pedersen","year":"2010","journal-title":"New Biotechnol."},{"key":"ref_32","unstructured":"Sluiter, A., Hames, B., Ruiz, R., Scarlata, C.J., Sluiter, J., and Templeton, D. (2008). Determination of Ash in Biomass, NREL\/TP-510-42622."},{"key":"ref_33","unstructured":"Sluiter, A., Hames, B., Ruiz, R., Scarlata, C., Sluiter, J., Templeton, D., and Crocker, D. (2012). Determination of Structural Carbohydrates and Lignin in Biomass, NREL\/TP-510-42618."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"136","DOI":"10.1016\/j.procbio.2017.11.012","article-title":"Membrane separation and characterisation of lignin and its derived products obtained by a mild ethanol organosolv treatment of rice straw","volume":"65","author":"Moniz","year":"2018","journal-title":"Process Biochem."},{"key":"ref_35","unstructured":"Standard Methods Committee of the American Public Health Association, American Water Works Association, and Water Environment Federation (2017). Standard Methods for the Examination of Water and Wastewater, American Public Health Association."},{"key":"ref_36","first-page":"49","article-title":"A comparison of two simple titration procedures to determine volatile fatty acids in influents to waste-water and sludge treatment processes","volume":"24","author":"Buchauer","year":"1998","journal-title":"Water SA"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"661","DOI":"10.1007\/s11947-011-0565-z","article-title":"Production, composition, and application of coffee and its industrial residues","volume":"4","author":"Mussatto","year":"2011","journal-title":"Food Bioprocess Technol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"3493","DOI":"10.1007\/s11947-014-1349-z","article-title":"Chemical, functional, and structural properties of spent coffee grounds and coffee silverskin","volume":"7","author":"Ballesteros","year":"2014","journal-title":"Food Bioprocess Technol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1016\/j.bej.2015.06.006","article-title":"Autohydrolysis of Annona cherimola mill. seeds: Optimization, modeling and products characterization","volume":"104","author":"Branco","year":"2015","journal-title":"Biochem. Eng. J."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"242","DOI":"10.1016\/j.biortech.2017.09.080","article-title":"Ethanol production from bamboo using mild alkaline pre-extraction followed by alkaline hydrogen peroxide pretreatment","volume":"247","author":"Yuan","year":"2018","journal-title":"Bioresour. Technol."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"3000","DOI":"10.1016\/j.biortech.2006.10.022","article-title":"A comparison of chemical pretreatment methods for improving saccharification of cotton stalks","volume":"98","author":"Silverstein","year":"2007","journal-title":"Bioresour. Technol."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"254","DOI":"10.1016\/j.ijbiomac.2021.01.185","article-title":"Tuning structure of spent coffee ground lignin by temperature fractionation to improve lignin-based carbon nanofibers mechanical performance","volume":"174","author":"Du","year":"2021","journal-title":"Int. J. Biol. Macromol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"531","DOI":"10.1016\/j.ijbiomac.2022.03.049","article-title":"Green solvents-based molecular weight controllable fractionation process for industrial alkali lignin at room temperature","volume":"207","author":"Jin","year":"2022","journal-title":"Int. J. Biol. Macromol."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1016\/j.indcrop.2013.06.037","article-title":"Characterisation and hydrothermal processing of corn straw towards the selective fractionation of hemicelluloses","volume":"50","author":"Moniz","year":"2013","journal-title":"Ind. Crops Prod."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"413","DOI":"10.1385\/ABAB:121:1-3:0413","article-title":"Effects of aliphatic acids, furfural, and phenolic compounds on Debaryomyces hansenii CCMI 941","volume":"121","author":"Duarte","year":"2005","journal-title":"Appl. Biochem. Biotechnol."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"461","DOI":"10.1385\/ABAB:130:1:461","article-title":"The combined effects of acetic acid, formic acid, and hydroquinone on Debaryomyces hansenii physiology","volume":"130","author":"Duarte","year":"2006","journal-title":"Appl. Biochem. Biotechnol."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"281","DOI":"10.1016\/S0144-8617(02)00183-2","article-title":"Degradation of cellulose under alkaline conditions","volume":"51","author":"Knill","year":"2003","journal-title":"Carbohydr. Polym."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"1278","DOI":"10.1177\/0734242X20914731","article-title":"In search of the optimal inoculum to substrate ratio during anaerobic co-digestion of spent coffee grounds and cow manure","volume":"38","author":"Akyol","year":"2020","journal-title":"Waste Manag. Res."},{"key":"ref_49","unstructured":"Bernhard, D. (2013). Process Monitoring in Biogas Plants, IEA Bioenergy."}],"container-title":["Energies"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1073\/16\/9\/3907\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:29:49Z","timestamp":1760124589000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1073\/16\/9\/3907"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,5,5]]},"references-count":49,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2023,5]]}},"alternative-id":["en16093907"],"URL":"https:\/\/doi.org\/10.3390\/en16093907","relation":{},"ISSN":["1996-1073"],"issn-type":[{"value":"1996-1073","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,5,5]]}}}