Effect of the Substrate to Inoculum Ratios on the Kinetics of Biogas Production during the Mesophilic Anaerobic Digestion of Food Waste

Aakash Khadka, Anmol Parajuli, Sheila Dangol, Bijay Thapa, Lokesh Sapkota, Alessandro A. Carmona-Martínez and Anish Ghimire
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Aakash Khadka: Resource Recovery Research Group (Re3G), Department of Environmental Science and Engineering, Kathmandu University, Dhulikhel 45200, Nepal
Anmol Parajuli: Resource Recovery Research Group (Re3G), Department of Environmental Science and Engineering, Kathmandu University, Dhulikhel 45200, Nepal
Sheila Dangol: Nawa Paila, Sisir-Marg-11, Babarmahal, Kathmandu 44600, Nepal
Bijay Thapa: Nawa Paila, Sisir-Marg-11, Babarmahal, Kathmandu 44600, Nepal
Lokesh Sapkota: Soil Water and Air Testing Laboratories Pvt. Ltd., GPO 25752, Babarmahal, Kathmandu 44600, Nepal
Alessandro A. Carmona-Martínez: CIRCE-Research Centre for Energy Resources and Consumption (CIRCE Foundation—University of Zaragoza), Parque Empresarial Dinamiza, Avenida Ranillas 3D, 1a Planta, 50018 Zaragoza, Spain
Anish Ghimire: Resource Recovery Research Group (Re3G), Department of Environmental Science and Engineering, Kathmandu University, Dhulikhel 45200, Nepal

Energies, 2022, vol. 15, issue 3, 1-16

Abstract: This study evaluates the effects of the varying substrate to inoculum ratios (S:I) of 0.5, 1, 2, 3, 4, 5, and 6 (volatile solids/VS basis) on the kinetics of biogas production during batch mesophilic (35 ± 1 °C) anaerobic digestion (AD) of simulated food waste (FW), using anaerobic digestate as the inoculum. Kinetic parameters during biogas production (scrubbed with NaOH solution) are predicted by the first-order and the modified Gompertz model. The observed average specific biogas yields are in descending order corresponding to the S:I ratios 1, 2, 4, 6, 3, 5, and 0.5, respectively, and the significant effect of the S:I ratio was observed. The tests with the S:I of 1 have the maximum average biogas production rates of 88.56 NmL/gVS.d, whereas tests with the S:I of 6 exhibited the lowest production rates (24.61 NmL/gVS.d). The maximum biogas yields, predicted by the first order and the modified Gompertz model, are 668.65 NmL/gVS (experimental 674.40 ± 29.10 NmL/gVS) and 653.17 NmL/gVS, respectively. The modified Gompertz model has been proven to be suitable in predicting biogas production from FW. VS removal efficiency is greater in higher S:I ratios, with a maximum of 78.80 % at the S:I ratio of 6, supported by the longer incubation time. Moreover, a significant effect of the S:I ratio is seen on kinetics and energy recovery from the AD of FW.

Keywords: food waste; biogas; substrate to inoculum ratio; kinetic modeling; Gompertz model; volatile solids; energy recovery; first-order kinetics (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (12)

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