{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,6]],"date-time":"2026-02-06T23:06:44Z","timestamp":1770419204947,"version":"3.49.0"},"reference-count":52,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,2,6]],"date-time":"2026-02-06T00:00:00Z","timestamp":1770336000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Processes"],"abstract":"<jats:p>Intensive swine production contributes significantly to the global protein supply but generates considerable environmental pressure, particularly through greenhouse gas emissions and surplus slurry management. Anaerobic digestion (AD), especially (co-AD), has been widely investigated as a mitigation strategy to enhance renewable energy generation and nutrient recovery. This systematic review synthesizes life cycle assessment (LCA) studies published between 2019 and 2025 that evaluated AD systems treating swine slurry, following the PRISMA 2020 guidelines. Across diverse methodological approaches and regional contexts, the literature consistently shows that AD can reduce global warming potential compared with conventional slurry management, with stronger environmental benefits when biogas is efficiently valorized and when swine slurry is co-digested with complementary organic substrat. Co-AD emerges as a key mitigation option by improving biogas yields, process stability, and overall environmental performance while also enabling better utilization of external organic waste. However, the results remain highly sensitive to operational factors such as methane leakage, digestate management, energy efficiency, and substrate selection. This review highlights the methodological inconsistencies among LCA studies and underscores the need for harmonized assessment frameworks and improved emission data. Overall, co-AD represents a promising pathway for enhancing the environmental sustainability of swine production systems when integrated into optimized, context-specific management strategies.<\/jats:p>","DOI":"10.3390\/pr14030573","type":"journal-article","created":{"date-parts":[[2026,2,6]],"date-time":"2026-02-06T11:10:38Z","timestamp":1770376238000},"page":"573","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Comparative Systematic Review of Life-Cycle Assessments of Treatment Strategies for Swine Slurry with a Focus on Anaerobic Co-Digestion"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-1523-6960","authenticated-orcid":false,"given":"Pedro","family":"Esperan\u00e7o","sequence":"first","affiliation":[{"name":"Agriculture School, Polytechnic University of Coimbra, Rua da Miseric\u00f3rdia, Lagar dos Corti\u00e7os, S. Martinho do Bispo, 3045-093 Coimbra, Portugal"},{"name":"Agriculture School, Polytechnic University of Castelo Branco, 6001-909 Castelo Branco, Portugal"},{"name":"Research Center for Natural Resources, Environment and Society, Polytechnic University of Coimbra, Bencanta, 3045-601 Coimbra, Portugal"},{"name":"Research Center for Natural Resources, Environment and Society, Polytechnic University of Castelo Branco, Quinta Sra. de M\u00e9rcules, 6001-909 Castelo Branco, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5686-9192","authenticated-orcid":false,"given":"Ant\u00f3nio","family":"Ferreira","sequence":"additional","affiliation":[{"name":"Agriculture School, Polytechnic University of Coimbra, Rua da Miseric\u00f3rdia, Lagar dos Corti\u00e7os, S. Martinho do Bispo, 3045-093 Coimbra, Portugal"},{"name":"Research Center for Natural Resources, Environment and Society, Polytechnic University of Coimbra, Bencanta, 3045-601 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7596-8065","authenticated-orcid":false,"given":"Jos\u00e9","family":"Ferreira","sequence":"additional","affiliation":[{"name":"Centre for Natural Resources, Environment and Society-CERNAS-IPV, Technology and Management School, Polytechnic University of Viseu, Av. Cor. Jos\u00e9 Maria Vale de Andrade, 3504-510 Viseu, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1007\/s40726-018-0082-z","article-title":"Nutrient Recovery from Digestate of Anaerobic Digestion of Livestock Manure: A Review","volume":"4","author":"Shi","year":"2018","journal-title":"Curr. Pollut. Rep."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"163223","DOI":"10.1016\/j.scitotenv.2023.163223","article-title":"Treatment and utilization of swine wastewater\u2014A review on technologies in full-scale application","volume":"880","author":"Deng","year":"2023","journal-title":"Sci. Total Environ."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"110476","DOI":"10.1016\/j.rser.2020.110476","article-title":"Environmental sustainability assessment of pig manure mono- and co-digestion and dynamic land application of the digestate","volume":"137","author":"Zhang","year":"2021","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Beily, M., Young, B.J., Bres, P.A., Riera, N.I., Wang, W., Crespo, D.E., and Komilis, D. (2023). Relationships among physicochemical, microbiological, and parasitological parameters of pig slurry. Sustainability, 15.","DOI":"10.3390\/su15043172"},{"key":"ref_5","unstructured":"Food and Agriculture Organization of the United Nations (FAO) (2025). Pig Meat Production Dataset, FAO. Our World in Data."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"145408","DOI":"10.1016\/j.jclepro.2025.145408","article-title":"Evaluating environmental impacts of pork production: A life cycle assessment","volume":"503","author":"Treml","year":"2025","journal-title":"J. Clean. Prod."},{"key":"ref_7","unstructured":"Gerber, P.J., Steinfeld, H., Henderson, B., Mottet, A., Opio, C., Dijkman, J., Falcucci, A., and Tempio, G. (2013). Tackling Climate Change Through Livestock: A Global Assessment of Emissions and Mitigation Opportunities, Food and Agriculture Organization of the United Nations."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Sejian, V., Hyder, I., Ezeji, T., Lakritz, J., Bhatta, R., Ravindra, J.P., Prasad, C.S., and Lal, R. (2015). Global Warming: Role of Livestock. Climate Change Impact on Livestock: Adaptation and Mitigation, Springer.","DOI":"10.1007\/978-81-322-2265-1_10"},{"key":"ref_9","unstructured":"Food and Agriculture Organization of the United Nations (2017). Livestock Solutions for Climate Change, FAO. Available online: https:\/\/www.fao.org\/family-farming\/detail\/en\/c\/1634679\/."},{"key":"ref_10","unstructured":"Sutton, M., Howard, C., Erisman, J., Billen, G., Bleeker, A., Grennfelt, P., Van Grinsven, H., and Grizzetti, B. (2025, December 13). The European Nitrogen Assessment Assessing Our Nitrogen Inheritance. Available online: https:\/\/publications.tno.nl\/publication\/34627918\/45o9AS\/b11011.pdf."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Jim\u00e9nez-de-Santiago, D.E., Ovejero, J., Ant\u00fanez, M., and Bosch-Serra, A.D. (2024). Ammonia Volatilization from Pig Slurries in a Semiarid Agricultural Rainfed Area. Sustainability, 16.","DOI":"10.3390\/su16010238"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"101315","DOI":"10.1016\/j.biteb.2022.101315","article-title":"Anaerobic digestion biorefinery for circular bioeconomy development","volume":"21","author":"Millati","year":"2023","journal-title":"Bioresour. Technol. Rep."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"115638","DOI":"10.1016\/j.rser.2025.115638","article-title":"Upcycling anaerobic digestion streams into feed-grade protein for increased environmental sustainability","volume":"216","author":"Marami","year":"2025","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"5478","DOI":"10.1016\/j.biortech.2008.12.046","article-title":"The future of anaerobic digestion and biogas utilization","volume":"100","year":"2009","journal-title":"Bioresour. Technol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1007\/s11250-022-03045-6","article-title":"The environmental performance of different pork production scenarios: A life cycle assessment study","volume":"54","year":"2022","journal-title":"Trop. Anim. Health Prod."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"7472","DOI":"10.1039\/D5GC01053E","article-title":"Anaerobic Digestion-derived Digestate Valorization: Green Chemistry Innovations for Resource Recovery and Reutilization","volume":"27","author":"Jacob","year":"2025","journal-title":"Green Chem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"541","DOI":"10.1016\/j.scitotenv.2013.06.058","article-title":"Anaerobic digestion of different feedstocks: Impact on energetic and environmental balances of biogas process","volume":"463\u2013464","author":"Bacenetti","year":"2013","journal-title":"Sci. Total Environ."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"3204","DOI":"10.1016\/j.biortech.2006.07.007","article-title":"Methane production through anaerobic digestion of various energy crops grown in sustainable crop rotations","volume":"98","author":"Amon","year":"2006","journal-title":"Bioresour. Technol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"126805","DOI":"10.1016\/j.chemosphere.2020.126805","article-title":"Enhancing the production of biogas through anaerobic co-digestion of agricultural waste and chemical pre-treatments","volume":"255","author":"Almomani","year":"2020","journal-title":"Chemosphere"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"125340","DOI":"10.1016\/j.energy.2022.125340","article-title":"Holistic Life Cycle Assessment of a biogas-based electricity generation plant in a pig farm considering co-digestion and an additive","volume":"261","author":"Freitas","year":"2022","journal-title":"Energy"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"130441","DOI":"10.1016\/j.jclepro.2022.130441","article-title":"Climate mitigation efficacy of anaerobic digestion in a decarbonising economy","volume":"338","author":"Styles","year":"2022","journal-title":"J. Clean. Prod."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1291","DOI":"10.1016\/j.rser.2015.10.013","article-title":"Review of life cycle assessment for biogas production in Europe","volume":"54","author":"Hijazi","year":"2016","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Sossidou, E.N., Banias, G.F., Batsioula, M., Termatzidou, S.-A., Simitzis, P., Patsios, S.I., and Broom, D.M. (2025). Modern Pig Production: Aspects of Animal Welfare, Sustainability and Circular Bioeconomy. Sustainability, 17.","DOI":"10.3390\/su17115184"},{"key":"ref_24","unstructured":"(2006). Environmental Management\u2014Life Cycle Assessment\u2014Principles and Framework (Standard No. ISO 14040:2006a)."},{"key":"ref_25","unstructured":"(2006). Environmental Management\u2014Life Cycle Assessment\u2014Requirements and Guidelines (Standard No. ISO 14040:2006b)."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"115187","DOI":"10.1016\/j.rser.2024.115187","article-title":"Mitigating biomethane losses in European biogas plants: A techno-economic assessment","volume":"210","author":"Hurtig","year":"2024","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"n71","DOI":"10.1136\/bmj.n71","article-title":"The PRISMA 2020 statement: An updated guideline for reporting systematic reviews","volume":"372","author":"Page","year":"2021","journal-title":"BMJ"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"210","DOI":"10.1186\/s13643-016-0384-4","article-title":"Rayyan\u2014a web and mobile app for systematic reviews","volume":"5","author":"Ouzzani","year":"2016","journal-title":"Syst. Rev."},{"key":"ref_29","first-page":"e1230","article-title":"PRISMA2020: An R package and Shiny app for producing PRISMA 2020-compliant flow diagrams, with interactivity for optimised digital transparency and Open Synthesis Campbell","volume":"18","author":"Haddaway","year":"2022","journal-title":"Syst. Rev."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"105522","DOI":"10.1016\/j.envint.2020.105522","article-title":"Life cycle assessment of anaerobic digestion of pig manure coupled with different digestate treatment technologies","volume":"137","author":"Duan","year":"2020","journal-title":"Environ. Int."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Gir\u00f3n-Rojas, C., Alcobendas, A.I.P., Cort\u00e9s, J.G., Ribal, J., and Sanjuan, N. (2025). Enhancing Energy Self-Sufficiency in Rural Regions: Environmental and Financial Assessment of Anaerobic Digestion of Pig Slurry. Waste Biomass Valorization, 1\u201317.","DOI":"10.1007\/s12649-025-03366-1"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1016\/j.wasman.2022.12.011","article-title":"A comparative life cycle assessment of anaerobic mono- and co-digestion of livestock manure in Bangladesh","volume":"157","author":"Hossain","year":"2023","journal-title":"Waste Manag."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"125034","DOI":"10.1016\/j.jclepro.2020.125034","article-title":"Improved environmental sustainability and bioenergy recovery through pig manure and food waste on-farm co-digestion in Ireland","volume":"280","author":"Jiang","year":"2021","journal-title":"J. Clean. Prod."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"120005","DOI":"10.1016\/j.jclepro.2020.120005","article-title":"Environmental impacts of housing conditions and manure management in European pig production systems through a life cycle perspective: A case study in Denmark","volume":"253","author":"Pexas","year":"2020","journal-title":"J. Clean. Prod."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Venslauskas, K., Navickas, K., Rube\u017eius, M., Tilvikien\u0117, V., Supronien\u0117, S., Doyeni, M.O., Bar\u010dauskait\u0117, K., Bak\u0161inskait\u0117, A., and Bunevi\u010dien\u0117, K. (2022). Environmental Impact Assessment of Sustainable Pig Farm via Management of Nutrient and Co-Product Flows in the Farm. Agronomy, 12.","DOI":"10.3390\/agronomy12040760"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"110512","DOI":"10.1016\/j.jenvman.2020.110512","article-title":"Environmental life cycle comparisons of pig farming integrated with anaerobic digestion and algae-based wastewater treatment","volume":"264","author":"Wu","year":"2020","journal-title":"J. Environ. Manag."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1567","DOI":"10.1016\/j.jclepro.2019.06.085","article-title":"LCA of anaerobic digestion: Emission allocation for energy and digestate","volume":"235","author":"Timonen","year":"2019","journal-title":"J. Clean. Prod."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"924","DOI":"10.1016\/j.spc.2022.06.011","article-title":"Evaluating the environmental and economic sustainability of energy from anaerobic digestion of different feedstocks in Turkey","volume":"32","author":"Balcioglu","year":"2022","journal-title":"Sustain. Prod. Consum."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"171","DOI":"10.1007\/s10661-022-10675-8","article-title":"Environmental impacts of corn silage production: Influence of wheat residues under contrasting tillage management types","volume":"195","author":"Mirzaei","year":"2022","journal-title":"Environ. Monit. Assess."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Ferreira, J., Santos, L., Ferreira, M., Ferreira, A., and Domingos, I. (2024). Environmental Assessment of Pig Manure Treatment Systems through Life Cycle Assessment: A Mini-Review. Sustainability, 16.","DOI":"10.3390\/su16093521"},{"key":"ref_41","first-page":"907","article-title":"Life Cycle Assessment and Techno-Economic Assessment of Anaerobic Co-Digestion: A Short Review","volume":"88","author":"Tan","year":"2021","journal-title":"Chem. Eng. Trans."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"100339","DOI":"10.1016\/j.cesys.2025.100339","article-title":"Financial feasibility and optimization of anaerobic digestion systems for sustainable waste management: A comprehensive global analysis","volume":"19","author":"Marefat","year":"2025","journal-title":"Clean. Environ. Syst."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"148","DOI":"10.1016\/j.resconrec.2017.08.014","article-title":"Life cycle assessment of orange peel waste management","volume":"127","author":"Negro","year":"2017","journal-title":"Resour. Conserv. Recycl."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"28","DOI":"10.1016\/j.apenergy.2017.11.032","article-title":"An evaluation of anaerobic co-digestion implementation on New York State dairy farms using an environmental and economic life-cycle framework","volume":"211","author":"Usack","year":"2018","journal-title":"Appl. Energy"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"111343","DOI":"10.1016\/j.rser.2021.111343","article-title":"Current status of biogas upgrading for direct biomethane use: A review","volume":"149","author":"Khan","year":"2021","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"111472","DOI":"10.1016\/j.rser.2021.111472","article-title":"Effects of swine manure storage time on solid-liquid separation and biogas production: A life-cycle assessment approach","volume":"150","author":"Hollas","year":"2021","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1016\/j.jclepro.2017.10.095","article-title":"Selection of pig manure management strategies: Case study of Polish farms","volume":"172","author":"Makara","year":"2018","journal-title":"J. Clean. Prod."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"303","DOI":"10.1007\/s12649-020-00959-w","article-title":"Performance of Anaerobic Co-digestion of Pig Slurry with Pineapple (Ananas comosus) Bio-waste Residues","volume":"12","author":"Azevedo","year":"2020","journal-title":"Waste Biomass Valori."},{"key":"ref_49","doi-asserted-by":"crossref","unstructured":"Santos, L., Ferreira, M., Domingos, I., Oliveira, V., Rodrigues, C., Ferreira, A., and Ferreira, J. (2025). Life Cycle Assessment of Pig Production in Central Portugal: Environmental Impacts and Sustainability Challenges. Sustainability, 17.","DOI":"10.3390\/su17020426"},{"key":"ref_50","doi-asserted-by":"crossref","unstructured":"Mart\u00edn-Sanz-Garrido, C., Revuelta-Aramburu, M., Santos-Montes, A.M., and Morales-Polo, C. (2025). A Review on Anaerobic Digestate as a Biofertilizer: Characteristics, Production, and Environmental Impacts from a Life Cycle Assessment Perspective. Appl. Sci., 15.","DOI":"10.3390\/app15158635"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"133072","DOI":"10.1016\/j.jclepro.2022.133072","article-title":"Effect of natural and regulatory conditions on the environmental impacts of pig slurry acidification across different regions in Europe: A life cycle assessment","volume":"368","author":"Beyers","year":"2022","journal-title":"J. Clean. Prod."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"127653","DOI":"10.1016\/j.jclepro.2021.127653","article-title":"Life cycle analysis of renewable natural gas and lactic acid production from waste feedstocks","volume":"311","author":"Lee","year":"2021","journal-title":"J. Clean. 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