Impact of corn stover particle size and C/N ratio on reactor performance in solid-state anaerobic co-digestion with dairy manure

Abstract

Green energy generation from agricultural waste has the potential to minimize dependency on fossil and reduce the resultant environmental impact of this fuel provided anaerobic reactor performance is optimized. Hence, the interactive impact of carbon to nitrogen (C/N) ratio, particle size, and codigestion of dairy manure (DM) and corn stover (CS) on solid-state anaerobic digester (SSAD) performance was investigated with four treatments (DMCS24S, DMCS24L, DMCS28L, and DMCS32L) in this solid-state study. Novel scanning electron microscope (SEM) image analysis utilized to describe the corn stover using ImageJ indicated that corn stover of particle size 0.18-0.42 mm had lower rough surface texture relative to the 0.42-0.84 mm size. This observation not only influenced the ingestate degradation, the bioconversion rate was negatively affected by 0.18-0.42 mm particle size of corn stover. Notably, increase in C/N ratio led to decrease in total ammonia nitrogen (TAN) and alkalinity concentration (Alk), hence, treatments with the lowest C/N ratio had better reactor performance in terms of suitable process parameters such as Alk, pH, ORP, and TAN. Furthermore, DMCS24L treatment had the highest methane yield (106 mL/g VS) and net methane energy (2.92 MJ/kg). Interestingly, modified Gompertz model gave the best kinetic description of the methane production. This SSAD mesophilic study suggests that corn stover, with particle size of 0.42-0.84 mm, co-digested with dairy manure under a C/N ratio of 24 has the potential to enhance methane yield and optimize reactor performance.Implications: The utilization of agricultural waste for bioenergy generation through solid-state anaerobic digestion could be enhanced through the interactive impact of substrate particle size, carbon-to-nitrogen (C/N) ratio and co-digestion, which has not been previously studied. These ternary factors significantly improved reactor performance and enhanced methane yield when corn stover of 0.42-0.84 mm particle size was co-digested with dairy manure to achieve a C/N ratio of 24.

Modelling the effects of particle size pretreatment method on biogas yield of groundnut shells

“…For oDMBY and oDMMY, their optimum yields were recorded at the same temperature and hydraulic retention time but with different particle sizes. Optimum oDMBY was recorded at a particle size of 4 mm, and this result agrees with what was recorded by earlier researchers when compared with 6 mm particle size (Ajayi-Banji et al, 2020; Kirby et al, 2020; Kulichkova et al, 2020; Prade et al, 2019). Compared with 2 mm particle size, it is contrary to what was earlier reported (Naegele et al, 2014; Nalinga and Legonda, 2016).…”

High-Solid Anaerobic Digestion: Reviewing Strategies for Increasing Reactor Performance

“…A similar result was obtained by Ajayi-Banji et al [45] when evaluating SS-AD using corn stover and dairy manure. These authors also reported the better performance of high-solid digestion systems when reducing the C/N ratio of the mixture, with these systems favoring the alkalinity and pH values of the reactor leachate.…”

“…Solid-state fermentation has been successfully studied for producing enzymes, biosurfactants, proteins, and biofuels [39,40] and a great variety of valuable products [41][42][43][44]. Anaerobic digestion has also been evaluated under this configuration and the co-digestion of different residues, such as manure, food wastes, and agricultural wastes, has also been studied under SS-AD conditions [45][46][47].…”

Anaerobic co-digestion of agricultural wastes toward circular bioeconomy

“…They suggested that the low CH 4 yield (in the case of a 1-mm chopped crop) may be attributed to the less lactic acid generation during ensiling. A similar result was observed in the case of corn stover; when the particle size was reduced from 0.42-0.84 to 0.18-0.42 mm, significantly lower methane and biogas yields could be observed (Ajayi-Banji et al, 2020). In addition, a digester can be easily clogged in the case where fine particles are fed, which should be carefully considered in the design.…”