Effect of Thermal Pretreatment on the Yield of Biogas from Microcoleous Vaginatus

Abstract

Biomass is being looked upon as one of the promising renewable energy sources for the future, with growing interest in microalgae conversion into biogas through anaerobic digestion. Recently, the ability of microalgae to treat waste water has doubled its potentials material today. However, in spite of the progress made in that regards, there are still challenges of algae conversion to biofuel, due to the presence of complex cell wall in some algae. Cell wall inhibits bacteria growth during degradation. In this research work 10 grams of Microcoleous vaginatus was treated in an oven at varying temperatures of 70, 75 and 80 oC for an hour, out of which 4 g was measured into 250 ml serum bottle for digestion at mesophilic temperature of 37 oC. Based on the results of proximate analysis, 69% increase in carbohydrate was attained with 72.7 – 148% reduction in moisture content. The biogas yield of untreated sample was 4.36 mLg−1 VS, while, pretreated samples at 70, 75 and 80 ℃ produced 8.39, 9.07 and 9.38 mLg−1VS (volatile solid) of biogas. This corresponds to 92, 108 and 115% higher than that of untreated samples. However, thermal treatment of M. vaginatus prior to digestion show positive effect on carbohydrate extraction and enhanced biogas and methane yield as well. Therefore, this makes the substrate a good feedstock for biogas production.

Keywords

• biomass
• biogas
• pretreatment
• anaerobic digestion
• degradation
• microcoleous vaginatus