ABSTRACT
Microalgae biomass can be used directly for biogas production via anaerobic digestion or the disrupted biomass after microwave treatment or the lipid extracted biomass can be fed to the anaerobic digestion system. Anaerobic digestion proceeds through a series of decomposition phases: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. The rate-limiting step in anaerobic digestion of solid feedstock such as lignocellulosic crops is the hydrolysis of complex polymeric substances and in particular, the cross-linking of lignin which is non-biodegradable with cellulose and hemicellulose. Agricultural wastes such as rice straw and switchgrass and other lignocellulosic waste can be used as feedstock for biogas production. Pretreatment of the feedstock improves hydrolysis yield and the total methane yield. The chapter describes various types of pretreatment techniques, namely acid pretreatment, alkaline pretreatment, mechanical pretreatment, steam pretreatment, thermal pretreatmen and microwave pretreatment. The impact of microwave irradiation on the microalgae cell wall structure can be analyzed using microscopic imaging.
