Improving biomethane potential by pretreatment methods/utilization of energy crops

In this study, the positive effect of steam explosion and alkali pretreatments on biomethane yields and the conditions for optimization for the anaerobic digestion process in the energy crops of switchgrass (Panicum virgatum L) and sweet sorghum (Sorghum bicolar var. saccharatum) were investigated. When determining the pretreatment parameters, the criteria of being economical and sustainable were taken into consideration. As a result of the anaerobic digestion process of the alkali-pretreated feedstocks of switchgrass and sweet sorghum, the maximum biogas yield and biomethane potential were obtained as 614 and 615 as well as 378 and 367 IN kg-1 VS, respectively. In the feedstock of sweet sorghum, the maximum biogas yield was measured in the pretreatment parameter of 70°C, 6 hours, and 2.5% NaOH. When compared with the untreated feedstock, twofold biogas yield was obtained from this pretreatment parameter. Similarly, the maximum methane yield from the feedstock of switchgrass was measured in the pretreatment parameter of 55°C, 12 hours, and 2.5% NaOH. Accordingly, twofold biogas yield is seen when compared with the untreated feedstock. The maximum specific biogas yield rate (458 IN kg-1 VS) was obtained from the switchgrass pretreated with steam explosion at 220°C for 5 minutes. The maximum specific methane yield (250 IN kg-1 VS) was measured in the pretreatment parameter of 200°C and 10 minutes. In addition, when compared with the untreated feedstock of switchgrass, 42% more specific biogas and 40% more methane yield were obtained.