Optimizing Biogas Production and Digestive Stability through Waste Co-Digestion

Rao Muhammad Ahmad, Sabiha Javied (), Ambreen Aslam, Saud Alamri, Qamar uz Zaman, Ayesha Hassan and Nabeela Noor
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Rao Muhammad Ahmad: Department of Environmental Sciences, The University of Lahore, Lahore 54000, Pakistan
Sabiha Javied: Department of Environmental Sciences, The University of Lahore, Lahore 54000, Pakistan
Ambreen Aslam: Department of Environmental Sciences, The University of Lahore, Lahore 54000, Pakistan
Saud Alamri: Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
Qamar uz Zaman: Department of Environmental Sciences, The University of Lahore, Lahore 54000, Pakistan
Ayesha Hassan: Energy, Environment and Society, School of Humanities, Social Science and Law, University of Dundee, Dundee DD1 5HW, UK
Nabeela Noor: Department of Pharmacy, University of management and Technology, Lahore 54770, Pakistan

Sustainability, 2024, vol. 16, issue 7, 1-15

Abstract: This study aimed to enhance the nutrient balance of municipal solid waste (MSW), characterized by a high carbon-to-nitrogen (C/N) ratio, which is a critical factor in the anaerobic digestion process. The investigation involved the addition of MSW, which is rich in carbon content, to food waste (FW) with high nitrogen content. The goal was to determine an optimal co-substrate mixing ratio of MSW and FW for anaerobic co-digestion at mesophilic temperatures, aiming to improve process stability and performance to achieve higher biogas yield. The co-digestion experiments encompassed five mixing ratios of MSW and FW with C/N ratios of 20, 25, 30, 35, and 40 under mesophilic conditions in a laboratory. The results indicated that the highest specific biogas yield, reaching 827 L/kg VS, was attained when the co-substrate feedstock had a balanced C/N ratio of 20, surpassing the 520 L/kg vs. obtained from MSW digestion alone. As the proportion of MSW increased in the co-substrate mixing feedstock, the biogas production rate decreased. Additionally, the study explored the optimal substrate-to-inoculum (S/I) ratio, focusing on the co-substrate feedstock with a C/N ratio of 20. Four S/I ratios (0.5, 1.0, 1.5, and 2.0) were examined, revealing that the highest specific biogas yield, at 642 L/kg VS, occurred at an S/I ratio of 0.5. An accumulation in volatile fatty acids (VFAs) was observed at higher S/I ratios, attributed to the lower abundance of inoculum microorganisms in the anaerobic digestion process. Overall, the findings suggested that the optimum C/N ratio for co-digestion of MSW and FW falls within the range of 20–25/1, while the preferred S/I ratio is 0.5.

Keywords: anaerobic co-digestion; C/N ratio; substrate to inoculum ratio; food waste; municipal solid waste; biogas (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2024
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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