Energy Valorization and Resource Recovery from Municipal Sewage Sludge: Evolution, Recent Advances, and Future Prospects
Municipal sewage sludge, a by-product of urban wastewater treatment, is increasingly recognized to be a strategic resource rather than a disposal burden. Traditional management practices, such as landfilling, incineration, and land application, are facing growing limitations due to environmental ris...
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2025-06-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/18/13/3442 |
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| author | Pietro Romano Adriana Zuffranieri Gabriele Di Giacomo |
| author_facet | Pietro Romano Adriana Zuffranieri Gabriele Di Giacomo |
| author_sort | Pietro Romano |
| collection | DOAJ |
| description | Municipal sewage sludge, a by-product of urban wastewater treatment, is increasingly recognized to be a strategic resource rather than a disposal burden. Traditional management practices, such as landfilling, incineration, and land application, are facing growing limitations due to environmental risks, regulatory pressures, and the underuse of the sludge’s energy and nutrient potential. This review examines the evolution of sludge management, focusing on technologies that enable energy recovery and resource valorization. The transition from linear treatment systems toward integrated biorefineries is underway, combining biological, thermal, and chemical processes. Anaerobic digestion remains the most widely used energy-positive method, but it is significantly improved by processes such as thermal hydrolysis, hydrothermal carbonization, and wet oxidation. Among these, hydrothermal carbonization stands out for its scalability, energy efficiency, and phosphorus-rich hydrochar production, although implementation barriers remain. Economic feasibility is highly context-dependent, being shaped by capital costs, energy prices, product markets, and policy incentives. This review identifies key gaps, including the need for standardized treatment models, decentralized processing hubs, and safe residual management. Supportive regulation and economic instruments will be essential to facilitate widespread adoption. In conclusion, sustainable sludge management depends on modular, integrated systems that recover energy and nutrients while meeting environmental standards. A coordinated approach across technology, policy, and economics is vital to unlock the full value of this critical waste stream. |
| format | Article |
| id | doaj-art-ff35b18513df4d4bbfa16bd58d62c70b |
| institution | Kabale University |
| issn | 1996-1073 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj-art-ff35b18513df4d4bbfa16bd58d62c70b2025-08-20T03:28:37ZengMDPI AGEnergies1996-10732025-06-011813344210.3390/en18133442Energy Valorization and Resource Recovery from Municipal Sewage Sludge: Evolution, Recent Advances, and Future ProspectsPietro Romano0Adriana Zuffranieri1Gabriele Di Giacomo2Department of Industrial and Information Engineering and of Economics (DIIIE), Engineering Headquarters of Roio, University of L’Aquila, 67100 L’Aquila, ItalyDepartment of Industrial and Information Engineering and of Economics (DIIIE), Engineering Headquarters of Roio, University of L’Aquila, 67100 L’Aquila, ItalyIndependent Researcher, 64025 Pineto, ItalyMunicipal sewage sludge, a by-product of urban wastewater treatment, is increasingly recognized to be a strategic resource rather than a disposal burden. Traditional management practices, such as landfilling, incineration, and land application, are facing growing limitations due to environmental risks, regulatory pressures, and the underuse of the sludge’s energy and nutrient potential. This review examines the evolution of sludge management, focusing on technologies that enable energy recovery and resource valorization. The transition from linear treatment systems toward integrated biorefineries is underway, combining biological, thermal, and chemical processes. Anaerobic digestion remains the most widely used energy-positive method, but it is significantly improved by processes such as thermal hydrolysis, hydrothermal carbonization, and wet oxidation. Among these, hydrothermal carbonization stands out for its scalability, energy efficiency, and phosphorus-rich hydrochar production, although implementation barriers remain. Economic feasibility is highly context-dependent, being shaped by capital costs, energy prices, product markets, and policy incentives. This review identifies key gaps, including the need for standardized treatment models, decentralized processing hubs, and safe residual management. Supportive regulation and economic instruments will be essential to facilitate widespread adoption. In conclusion, sustainable sludge management depends on modular, integrated systems that recover energy and nutrients while meeting environmental standards. A coordinated approach across technology, policy, and economics is vital to unlock the full value of this critical waste stream.https://www.mdpi.com/1996-1073/18/13/3442sewage sludgemunicipal wastewaterwaste-to-energybiorefineryhydro-thermal carbonizationhydrochar |
| spellingShingle | Pietro Romano Adriana Zuffranieri Gabriele Di Giacomo Energy Valorization and Resource Recovery from Municipal Sewage Sludge: Evolution, Recent Advances, and Future Prospects Energies sewage sludge municipal wastewater waste-to-energy biorefinery hydro-thermal carbonization hydrochar |
| title | Energy Valorization and Resource Recovery from Municipal Sewage Sludge: Evolution, Recent Advances, and Future Prospects |
| title_full | Energy Valorization and Resource Recovery from Municipal Sewage Sludge: Evolution, Recent Advances, and Future Prospects |
| title_fullStr | Energy Valorization and Resource Recovery from Municipal Sewage Sludge: Evolution, Recent Advances, and Future Prospects |
| title_full_unstemmed | Energy Valorization and Resource Recovery from Municipal Sewage Sludge: Evolution, Recent Advances, and Future Prospects |
| title_short | Energy Valorization and Resource Recovery from Municipal Sewage Sludge: Evolution, Recent Advances, and Future Prospects |
| title_sort | energy valorization and resource recovery from municipal sewage sludge evolution recent advances and future prospects |
| topic | sewage sludge municipal wastewater waste-to-energy biorefinery hydro-thermal carbonization hydrochar |
| url | https://www.mdpi.com/1996-1073/18/13/3442 |
| work_keys_str_mv | AT pietroromano energyvalorizationandresourcerecoveryfrommunicipalsewagesludgeevolutionrecentadvancesandfutureprospects AT adrianazuffranieri energyvalorizationandresourcerecoveryfrommunicipalsewagesludgeevolutionrecentadvancesandfutureprospects AT gabrieledigiacomo energyvalorizationandresourcerecoveryfrommunicipalsewagesludgeevolutionrecentadvancesandfutureprospects |