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

Abstract

Optimising biogas yields from anaerobic digestion of organic wastes is significant to maximum energy recovery in the biodigestion process and has become an important topic of interest. Substrate particle size is an important process parameter in biogas production, and it precedes other pretreatments methods for the majority of the lignocellulose materials. Optimisation of biogas yield using Response Surface Methodology (RSM) was done, and temperature, hydraulic retention time and particle size were considered variables to develop the predictive models. Pretreatment of groundnut shells was investigated using particle size reduction of mechanical pretreatment methods. After pretreatment, 30 samples were digested in a batch digester at mesophilic temperature. The experimental results showed that the temperature, hydraulic retention time and particle size had significant effects of interaction ( p < 0.05). The optimum experimental and predicted yields are: 44.70 and 42.92 (lNkgoDM) organic dry matter biogas yield, 20.80 and 19.09 (lN/kgFM) fresh mass biogas yield, 24.00 and 22.68 (lNCH4oDM) organic dry methane yield and 12.30 and 15.59 (lNCH4FM) fresh mass methane yield, respectively. The R2 recorded for the four yield components were 0.6268, 0.5875, 0.6109 and 0.5547. These values seem to be lower and a sign of the average fit of the model. Biogas production from groundnut shells was significantly improved with statistical optimisation and the pretreatment method.

Experimental evaluation of the influence of combined particle size pretreatment and Fe3O4additive on fuel yields ofArachis Hypogeashells

“… Jekayinfa et al (2020) reported 6 mm particle size as the optimum value for fresh biogas and methane yields of lignocellulose material. This result also supports what was reported by an earlier researcher when particle size was considered ( Olatunji et al, 2022b ). But this result contradicts what was recorded by Menardo et al (2012) that a particle size of 0.5 cm produced the optimum biogas and methane yields.…”

“…Economically, the technique requires further investigation at a commercial scale before it can be recommended. The detailed parameters related to particle sizes and Fe 3 O 4 additives show the influence of these operating parameters on the yield, as reported earlier ( Abdelsalam et al, 2016 ; Menardo et al, 2012 ; Olatunji et al, 2022b ). The results showed that combined particle size reduction with Fe 3 O 4 influences the biogas and methane yields more than the single pretreatment of Fe 3 O 4 nanoparticle additive.…”

“…Arachis Hpogea shell is one of the abundant feedstocks that have been investigated to have an excellent potential for biogas and methane generation ( Jekayinfa et al, 2020 ). The study shows that different particle sizes of Arachis hypogea significantly influence the biogas yield, and the expected yield determines the choice of particle size ( Olatunji et al, 2022b ). Compared with the conventional single pretreatment method, a combination of two or more pretreatment methods is advantageous in minimizing operational process stages apart from reducing the retention period and release of undesirable inhibitors ( Kumar and Sharma, 2017 ).…”

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

“…The general low digestion efficiency of the lignocellulose feedstock, along with the longer retention time (30-40 days), results in limited efficiency [14]. The efficiency and proportion of the hydrolysis and morphological characteristics of lignocellulosic feedstocks can be adapted by biological, chemical, thermal, and mechanical pretreatment methods [15][16][17]. Combining two or more pretreatment techniques has been investigated, and different researchers have recommended its application [18][19][20].…”

“…The engineering use of the Arachis hypogea shells is limited due to their high lignocellulosic content [37]. The shells have been reported to consist of 37% cellulose, 18% hemicellulose, and 27% lignin [17]. Arachis hypogea shells' surface morphological examination is shown in Figure 1.…”