Comparative assessment of dewatered sewage sludge combustion and biogas production: Environmental, economic and energy considerations

Yıl 2026, Cilt: 11 Sayı: 1, 161 - 186, 17.03.2026

Süleyman Sapmaz

https://doi.org/10.58559/ijes.1807712

https://izlik.org/JA85BP69LE

Öz

The escalating production of sewage sludge necessitates sustainable management strategies that balance energy recovery, environmental impact, and economic viability. This study presents a comprehensive techno-economic and environmental comparison of two sewage sludge-to-energy pathways: direct combustion and biogas production through anaerobic digestion. A computational model was developed to evaluate the complete sludge management chain, from wastewater treatment plant discharge to final disposal, accounting for auxiliary fuel requirements in combustion and digestate disposal costs in biogas production. Six sewage sludge (9.57-16.51 MJ/kg) were analyzed using data from Turkish wastewater treatment plants. Results demonstrated that high-calorific sludges required 23.8% less supplementary fuel than low-calorific samples, with installed capacities ranging from 0.84 to 1.58 MW for combustion systems and 0.66 to 0.79 MW for biogas systems. Only the highest calorific sludge achieved an emission factor (439.88 kg CO₂/MWh) lower than Turkey's electricity grid (442 kg CO₂/MWh), while biogas systems exhibited consistent emission factors (780-800 kg CO₂/MWh) across all scenarios. Economic analysis revealed that neither pathway is viable without government incentives at current market prices (67.81 USD/MWh). Total annual emissions from incineration (8,300 tons CO₂/year for low-calorific sludge) substantially exceeded those from biogas production (4,000-4,500 tons CO₂/year). 

Anahtar Kelimeler

Sewage sludge , Combustion , Anaerobic digestion , Net energy production , Environmental impact

Kaynakça

• [1] Carsky M, Solcova O, Soukup K, Kralik T, Vavrova K, Janota L, et al. Techno-Economic Analysis of Fluidized Bed Combustion of a Mixed Fuel from Sewage and Paper Mill Sludge. Energies (Basel) 2022;15. https://doi.org/10.3390/en15238964.
• [2] Pop E, Mihăescu L, Safta CA, Pop HL, Negreanu GP, Pîșă I. Solutions for Energy and Raw Material Recovery from Sewage Sludge Within the Concept of Circular Economy. Sustainability (Switzerland) 2025;17. https://doi.org/10.3390/su17073181.
• [3] Arias A, Behera CR, Feijoo G, Sin G, Moreira MT. Unravelling the environmental and economic impacts of innovative technologies for the enhancement of biogas production and sludge management in wastewater systems. J Environ Manage 2020;270. https://doi.org/10.1016/j.jenvman.2020.110965.
• [4] Liu Y, Ren J, Man Y, Lin R, Lee CKM, Ji P. Prioritization of sludge-to-energy technologies under multi-data condition based on multi-criteria decision-making analysis. J Clean Prod 2020;273. https://doi.org/10.1016/j.jclepro.2020.123082.
• [5] Grobelak A, Całus-Makowska K, Jasińska A, Klimasz M, Wypart-Pawul A, Augustajtys D, et al. Environmental Impacts and Contaminants Management in Sewage Sludge-to-Energy and Fertilizer Technologies: Current Trends and Future Directions. Energies (Basel) 2024;17. https://doi.org/10.3390/en17194983.
• [6] Yu S, Deng S, Zhou A, Wang X, Tan H. Life cycle assessment of energy consumption and GHG emission for sewage sludge treatment and disposal: a review. Front Energy Res 2023;11:1123972. https://doi.org/10.3389/FENRG.2023.1123972.
• [7] Nkuna SG, Olwal TO, Chowdhury SD, Ndambuki JM. A review of wastewater sludge-to-energy generation focused on thermochemical technologies: An improved technological, economical and socio-environmental aspect. Cleaner Waste Systems 2024;7. https://doi.org/10.1016/j.clwas.2024.100130.
• [8] Frišták V, Pipíška M, Soja G. Pyrolysis treatment of sewage sludge: A promising way to produce phosphorus fertilizer. J Clean Prod 2018;172:1772–8. https://doi.org/10.1016/j.jclepro.2017.12.015.
• [9] Arazo R, de Luna MD, Capareda S, Ido A, Mabayo VI. Superior sewage sludge disposal with minimal greenhouse gas emission via fast pyrolysis in a fluidized bed reactor. IOP Conf Ser Earth Environ Sci 2021;765:012094. https://doi.org/10.1088/1755-1315/765/1/012094.
• [10] Pawlak-Kruczek H, Wnukowski M, Niedzwiecki L, Czerep M, Kowal M, Krochmalny K, et al. Torrefaction as a valorization method used prior to the gasification of sewage sludge. Energies (Basel) 2019;12:1–18. https://doi.org/10.3390/en12010175.
• [11] Quan LM, Kamyab H, Yuzir A, Ashokkumar V, Hosseini SE, Balasubramanian B, et al. Review of the application of gasification and combustion technology and waste-to-energy technologies in sewage sludge treatment. Fuel 2022;316:123199. https://doi.org/10.1016/j.fuel.2022.123199.
• [12] Xiao H, Li K, Zhang D, Tang Z, Niu X, Yi L, et al. Environmental, energy, and economic impact assessment of sludge management alternatives based on incineration. J Environ Manage 2022;321. https://doi.org/10.1016/j.jenvman.2022.115848.
• [13] Chen L, Liao Y, Ma X. Economic analysis on sewage sludge drying and its co-combustion in municipal solid waste power plant. Waste Management 2021;121:11–22. https://doi.org/10.1016/j.wasman.2020.11.038.
• [14] Nordin A, Strandberg A, Elbashir S, Åmand LE, Skoglund N, Pettersson A. Co-combustion of municipal sewage sludge and biomass in a grate fired boiler for phosphorus recovery in bottom ash. Energies (Basel) 2020;13. https://doi.org/10.3390/en13071708.
• [15] Rijo B, Nobre C, Brito P, Ferreira P. An Overview of the Thermochemical Valorization of Sewage Sludge: Principles and Current Challenges. Energies 2024;17. https://doi.org/10.3390/en17102417.
• [16] Carotenuto A, Di Fraia S, Massarotti N, Uddin MR, Vanoli L. Combined Heat and Power Generation from Mechanically Dewatered Sewage Sludge: Numerical Modelling. Chem Eng Trans 2022;92:283–8. https://doi.org/10.3303/cet2292048.
• [17] Siriwardhana KACG, Mahanama KRR, Atthanayake IU, Somasundara DHGSR. Optimizing Sludge Incineration for Thermal Energy Recovery: A Sustainable Approach to Industrial Waste Management. Engineer: Journal of the Institution of Engineers, Sri Lanka 2025;58:83–91. https://doi.org/10.4038/engineer.v58i3.7706.
• [18] Appels L, Baeyens J, Degrève J, Dewil R. Principles and potential of the anaerobic digestion of waste-activated sludge. Prog Energy Combust Sci 2008;34:755–81. https://doi.org/10.1016/j.pecs.2008.06.002.
• [19] Cao Y, Pawłowski A. Sewage sludge-to-energy approaches based on anaerobic digestion and pyrolysis: Brief overview and energy efficiency assessment. Renewable and Sustainable Energy Reviews 2012;16:1657–65. https://doi.org/10.1016/j.rser.2011.12.014.
• [20] Varsha SS V., Soomro AF, Baig ZT, Vuppaladadiyam AK, Murugavelh S, Antunes E. Methane production from anaerobic mono- and co-digestion of kitchen waste and sewage sludge: synergy study on cumulative methane production and biodegradability. Biomass Convers Biorefin 2022;12:3911–9. https://doi.org/10.1007/s13399-020-00884-x.
• [21] Mudzanani K, Iyuke SE, Daramola MO. Co-digestion of wastewater treatment sewage sludge with various biowastes: A comparative study for the enhancement of biogas production. Mater Today Proc 2022;65:2172–83. https://doi.org/10.1016/j.matpr.2022.05.539.
• [22] Li H, Lindmark J, Nordlander E, Thorin E, Dahlquist E, Zhao L. Using the Solid Digestate from a Wet Anaerobic Digestion Process as an Energy Resource. Energy Technology 2013;1:94–101. https://doi.org/10.1002/ENTE.201200021.
• [23] URL TÜBİTAK KAMAG 1007 – 108G167 Evsel/Kentsel Arıtma Çamurlarının Yönetimi Projesi n.d. https://cygm.csb.gov.tr/evsel-kentsel-aritma-camurlarinin-yonetimi-projesi-duyuru-33959 (accessed October 28, 2021).
• [24] URL Evsel/Kentsel Arıtma Çamurlarının Yönetimi Projesi - TÜBİTAK KAMAG 1007 Çalıştay Sunumları n.d. https://www.camur.itu.edu.tr/dokuman.php (accessed October 28, 2021).
• [25] Sapmaz S, Kılıçaslan İ. Conceptual design and feasibility study of industrial sludge-based biosolid fuel production facility. Energy & Environment 2023;34:2093–109. https://doi.org/10.1177/0958305X221108496.
• [26] Novak JT. Dewatering of Sewage Sludge. Drying Technology 2006;24:1257–62. https://doi.org/10.1080/07373930600840419.
• [27] Chen G, Lock Yue P, Mujumdar AS. Sludge Dewatering and Drying. Drying Technology 2002;20:883–916. https://doi.org/10.1081/DRT-120003768.
• [28] Sapmaz S, Kılıçaslan İ. Energy analysis of sewage sludge energy conversion processes for Turkey—investigation of existing drying and combustion plants. Biomass Convers Biorefin 2023;13:2449–58. https://doi.org/10.1007/s13399-022-02773-x.
• [29] Sapmaz S. Decarbonization of Sewage Sludge Processing Through Solar Thermal Energy Integration. Int J Environ Res 2025;19:161. https://doi.org/10.1007/s41742-025-00829-0.
• [30] Sapmaz S, Kılıçaslan İ. Study on increasing the energy efficiency of a dryer used for the conversion of sewage sludge to biofuel. Biomass Convers Biorefin 2023;13:2459–68. https://doi.org/10.1007/s13399-022-02990-4.
• [31] Tchobanoglous G, Stensel HD, Tsuchihashi R, Burton F. Metcalf & Eddy Inc. Wastewater Engineering: Treatment and Resource Recovery. 4th ed. New York: McGraw-Hill; 2003.
• [32] Sapmaz S, Kılıçaslan İ. Biogas production from sewage sludge as a distributed energy generation element: A nationwide case study for Turkey. Environmental Research & Technology 2019;2:19–25.
• [33] Carlos Augusto de Lemos Chernicharo. Anaerobic Reactors. Water Intelligence Online 2015;6:9781780402116–9781780402116. https://doi.org/10.2166/9781780402116.
• [34] Paraschiv LS, Serban A, Paraschiv S. Calculation of combustion air required for burning solid fuels (coal / biomass / solid waste) and analysis of flue gas composition. Energy Reports 2020;6:36–45. https://doi.org/10.1016/J.EGYR.2019.10.016.
• [35] Çalbay E. Evaluation Of Dewatered And Partially Dried Sewage Sludge Combustion Based On Energy Balance And Carbon Footprint. Middle East Technical University, 2018.
• [36] Luostarinen S, Luste S, Sillanpää M. Increased biogas production at wastewater treatment plants through co-digestion of sewage sludge with grease trap sludge from a meat processing plant. Bioresour Technol 2009;100:79–85. https://doi.org/10.1016/j.biortech.2008.06.029.
• [37] Grosser A, Neczaj E. Sewage sludge and fat rich materials co-digestion - Performance and energy potential. J Clean Prod 2018;198:1076–89. https://doi.org/10.1016/j.jclepro.2018.07.124.
• [38] Davidsson Å, Lövstedt C, la Cour Jansen J, Gruvberger C, Aspegren H. Co-digestion of grease trap sludge and sewage sludge. Waste Management 2008;28:986–92. https://doi.org/10.1016/j.wasman.2007.03.024.
• [39] Commitee (MoENR). Türkiye Elektrik Üretimi ve Elektrik Tüketim Noktası Emisyon Faktörleri Bilgi Formu. https://enerji.gov.tr/evced-cevre-ve-iklim-elektrik-uretim-tuketim-emisyon-faktorleri 2024. https://enerji.gov.tr//Media/Dizin/EVCED/tr/%C3%87evreVe%C4%B0klim/%C4%B0klimDe%C4%9Fi%C5%9Fikli%C4%9Fi/EmisyonFaktorleri/2022_Uretim_Tuketim_EF.pdf (accessed September 11, 2025).