Effect of Combined Particle Size Reduction and Fe3O4 Additives on Biogas and Methane Yields of Arachis hypogea Shells at Mesophilic Temperature

Abstract

Enzymatic hydrolysis of lignocellulose materials has been identified as the rate-limiting step during anaerobic digestion. The application of pretreatment techniques can influence the biodegradability of lignocellulose substrate. This study combined Fe3O4 nanoparticles, which serve as a heterogeneous catalyst during anaerobic digestion, with different particle sizes of Arachis hypogea shells. Batch anaerobic digestion was set up at mesophilic temperature for 35 days. The results showed that 20 mg/L Fe3O4 additives, as a single pretreatment, significantly influence biogas and methane yields with an 80.59 and 106.66% increase, respectively. The combination of 20 mg/L Fe3O4 with a 6 mm particle size of Arachis hypogea shells produced the highest cumulative biogas yield of 130.85 mL/gVSadded and a cumulative methane yield of 100.86 mL/gVSadded. This study shows that 20 mg/L of Fe3O4 additive, combined with the particle size pretreatment, improved the biogas and methane yields of Arachis hypogea shells. This result can be replicated on the industrial scale to improve the energy recovery from Arachis hypogea shells.

Enhancing the biomethane yield of groundnut shells using deep eutectic solvents for sustainable energy production

“…A 178% increase in methane yield released was reported when acidic pretreatment of groundnut shells was considered . It can be observed that among some of the pretreatment techniques experimented with on groundnut shells, DES pretreatment produced the most significant improvement except when combined pretreatment (particle size reduction and Fe 3 O 4 additive) was investigated (Olatunji et al, 2022b). However, it has been reported that combined pretreatment increases the cost of production compared to single pretreatment, which could present DES pretreatment as the most efficient method.…”

Algae biogas production focusing on operating conditions and conversion mechanisms – A review

“…Lignocellulosic materials' size reduction during milling pretreatment increased the anaerobic digestion's capacity to buffer, which helps to reduce the acidity of AD. The substrate's particle sizes have an immediate impact on digestion since they immediately correlate with the amount of hydrolysing enzyme surface area that is accessible [ 85 , 86 ].…”

Sustainable enhancement of biogas and methane yield of macroalgae biomass using different pretreatment techniques: A mini-review

“…45 The recent development in multidisciplinary research has reported the application of nanoparticles, natural deep eutectic solvents (NADES), deep eutectic solvents (DES), and ionic liquids for feedstock pretreatments as a new novel means of pretreating biogas feedstocks. [55][56][57] Despite the successes recorded in the feedstock pretreatment, some demerits were observed. This includes the high energy inputs, particularly for thermal and mechanical methods, the release of inhibitory materials and corrosion/environmental challenges associated with a chemical pretreatment, the release of inhibitory compounds that lower the digestion rate, and the exorbitant cost of enzymes for biological pretreatments.…”

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