Anaerobic Co-Digestion of Cattle Manure and Sewage Sludge Using Different Inoculum Proportions

Anaerobic digestion (AD) is a sustainable strategy for converting hazardous wastes into renewable energy while supporting Sustainable Development Goals (SDGs). This study aimed to evaluate the effect of inoculum on optimizing biogas production from sewage sludge (SS) and cattle manure (CM). Bench-sc...

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Main Authors: Caroline Carvalho Pinto, Juliana Lobo Paes, Alexia de Sousa Gomes, Daiane Cecchin, Igor Ferreira Oliva, Romulo Cardoso Valadão, Vânia Reis de Souza Sant’Anna
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Fermentation
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Online Access:https://www.mdpi.com/2311-5637/11/7/373
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author Caroline Carvalho Pinto
Juliana Lobo Paes
Alexia de Sousa Gomes
Daiane Cecchin
Igor Ferreira Oliva
Romulo Cardoso Valadão
Vânia Reis de Souza Sant’Anna
author_facet Caroline Carvalho Pinto
Juliana Lobo Paes
Alexia de Sousa Gomes
Daiane Cecchin
Igor Ferreira Oliva
Romulo Cardoso Valadão
Vânia Reis de Souza Sant’Anna
author_sort Caroline Carvalho Pinto
collection DOAJ
description Anaerobic digestion (AD) is a sustainable strategy for converting hazardous wastes into renewable energy while supporting Sustainable Development Goals (SDGs). This study aimed to evaluate the effect of inoculum on optimizing biogas production from sewage sludge (SS) and cattle manure (CM). Bench-scale digesters were fed with 0, 20, and 40% inoculum prepared at a 1:3 SS:CM ratio. Substrate and digestate were analyzed for physicochemical properties, and biogas production data were fitted using nonlinear models. Kinetic parameters ranged from 0.0770 to 0.4691 L·kg<sup>−1</sup> for Y<sub>max</sub>, from 1.0263 to 2.1343 L·kg<sup>−1</sup>·week<sup>−1</sup> for μ<sub>max</sub>, and from 0.8168 to 8.0114 weeks for λ, depending on the ratio. The 1:3 SS:CM with 40% inoculum significantly improved biogas production by reducing the lag phase and increasing weekly yield, with the Gompertz model showing the best fit to the digestion kinetics. This was particularly evident due to the favorable conditions for microbial adaptation and efficient substrate degradation. The results reinforce the concept of optimization as defined in this study, wherein the application of inoculum enhances the performance of AD by improving the physicochemical conditions of the substrate and accelerating microbial activity, thereby resulting in increased methane (CH<sub>4</sub>) generation and overall biogas yield.
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spelling doaj-art-5e5fbed6e01e4132b0e404b4c06972582025-08-20T03:07:54ZengMDPI AGFermentation2311-56372025-06-0111737310.3390/fermentation11070373Anaerobic Co-Digestion of Cattle Manure and Sewage Sludge Using Different Inoculum ProportionsCaroline Carvalho Pinto0Juliana Lobo Paes1Alexia de Sousa Gomes2Daiane Cecchin3Igor Ferreira Oliva4Romulo Cardoso Valadão5Vânia Reis de Souza Sant’Anna6Department of Engineering, Federal Rural University of Rio de Janeiro (UFRRJ), Seropédica 23890-000, BrazilDepartment of Engineering, Federal Rural University of Rio de Janeiro (UFRRJ), Seropédica 23890-000, BrazilDepartment of Veterinary Medicine and Surgery, Federal Rural University of Rio de Janeiro (UFRRJ), Seropédica 23890-000, BrazilGraduate Program in Digital Agroenergy, Federal University of Tocantins (UFT), Palmas Campus, Palmas 77001-090, BrazilDepartment of Engineering, Federal Rural University of Rio de Janeiro (UFRRJ), Seropédica 23890-000, BrazilDepartment of Engineering, Federal Rural University of Rio de Janeiro (UFRRJ), Seropédica 23890-000, BrazilIndependent Researcher, Viçosa 36570-240, BrazilAnaerobic digestion (AD) is a sustainable strategy for converting hazardous wastes into renewable energy while supporting Sustainable Development Goals (SDGs). This study aimed to evaluate the effect of inoculum on optimizing biogas production from sewage sludge (SS) and cattle manure (CM). Bench-scale digesters were fed with 0, 20, and 40% inoculum prepared at a 1:3 SS:CM ratio. Substrate and digestate were analyzed for physicochemical properties, and biogas production data were fitted using nonlinear models. Kinetic parameters ranged from 0.0770 to 0.4691 L·kg<sup>−1</sup> for Y<sub>max</sub>, from 1.0263 to 2.1343 L·kg<sup>−1</sup>·week<sup>−1</sup> for μ<sub>max</sub>, and from 0.8168 to 8.0114 weeks for λ, depending on the ratio. The 1:3 SS:CM with 40% inoculum significantly improved biogas production by reducing the lag phase and increasing weekly yield, with the Gompertz model showing the best fit to the digestion kinetics. This was particularly evident due to the favorable conditions for microbial adaptation and efficient substrate degradation. The results reinforce the concept of optimization as defined in this study, wherein the application of inoculum enhances the performance of AD by improving the physicochemical conditions of the substrate and accelerating microbial activity, thereby resulting in increased methane (CH<sub>4</sub>) generation and overall biogas yield.https://www.mdpi.com/2311-5637/11/7/373anaerobic monodigestionanaerobic digestionphysicochemical characterizationbiogasmethanekinetics modeling
spellingShingle Caroline Carvalho Pinto
Juliana Lobo Paes
Alexia de Sousa Gomes
Daiane Cecchin
Igor Ferreira Oliva
Romulo Cardoso Valadão
Vânia Reis de Souza Sant’Anna
Anaerobic Co-Digestion of Cattle Manure and Sewage Sludge Using Different Inoculum Proportions
Fermentation
anaerobic monodigestion
anaerobic digestion
physicochemical characterization
biogas
methane
kinetics modeling
title Anaerobic Co-Digestion of Cattle Manure and Sewage Sludge Using Different Inoculum Proportions
title_full Anaerobic Co-Digestion of Cattle Manure and Sewage Sludge Using Different Inoculum Proportions
title_fullStr Anaerobic Co-Digestion of Cattle Manure and Sewage Sludge Using Different Inoculum Proportions
title_full_unstemmed Anaerobic Co-Digestion of Cattle Manure and Sewage Sludge Using Different Inoculum Proportions
title_short Anaerobic Co-Digestion of Cattle Manure and Sewage Sludge Using Different Inoculum Proportions
title_sort anaerobic co digestion of cattle manure and sewage sludge using different inoculum proportions
topic anaerobic monodigestion
anaerobic digestion
physicochemical characterization
biogas
methane
kinetics modeling
url https://www.mdpi.com/2311-5637/11/7/373
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