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

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 ℃) 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.

Performance Monitoring of Anaerobic Digestion at Various Organic Loading Rates of Commercial Malaysian Food Waste

“…Furthermore, the model demonstrated that the CMFW substrates had a higher biogas potential than a recent study ( Khadka et al, 2022 ). The authors obtained the value of R m as 0.0252 L/day.…”

Application of Magnetite‐nanoparticles and Static Magnetic Field on a Microbial Fuel Cell in Anaerobic Digestion

“…The cumulative biogas yield obtained from this study was fitted to the modified Gompertz model described by Equation [42] $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr {\rm M}={{\rm B}}_{{\rm p}}\times {\rm e}{\rm x}{\rm p}\left\{-{\rm e}{\rm x}{\rm p}\left[{{{{\rm B}}_{{\rm m}}.$$…”

Ensiling water hyacinth for enhanced biomethane production: effect of co‐ensiling with maize straw and eggshell powder as additive

“…The effective methane production time, T eff , calculated by subtracting the lag phase from the time required to obtain 90% of the cumulative BMP, was 17 days for all silages. Neither an increase in TS nor the presence of additive had an effect on T eff , probably because all experiments were conducted at the same initial pH and inoculum‐to‐substrate ratio 51 . Mao et al 52 .…”

“…Neither an increase in TS nor the presence of additive had an effect on T eff , probably because all experiments were conducted at the same initial pH and inoculum-to-substrate ratio. 51 Mao et al 52 reported that longer T eff (19.2 days) was obtained at higher initial pH (7.5) compared to lower initial pH (6.0 and 6.5) during the co-digestion of swine manure and corn straw. In the present study, T eff obtained from the dual-pool model was the same as T eff obtained from the measured data, another indication that the model was most appropriate in predicting the BMP of the silages compared to the other two models.…”