State-of-the-Art Irradiation Technologies for the Waste Biomass Pretreatment: Potential and Challenges

Increasing fossil energy dependency on fuels and chemicals leads to escalated environmental impacts, including global climate changes. The search for renewable alternatives for petroleum feedstock is gaining much attention from the scientific community worldwide. On the other side, a huge amount of waste biomass generated from agricultural, forestry, municipal, and industrial activities raises serious issues of pollution due to lack of proper management. This waste biomass could be considered as a cost-effective feedstock for generating cleaner and sustainable energy. However, the complex biomass structure must be degraded with efficient pretreatment techniques for its conversion into high-value products. Various physical, chemical, and biological pretreatment methods have been widely studied for industrially relevant product generation. Irradiation technologies are one of the major physical pretreatment methods for degrading complex recalcitrant biomass. Irradiation methods including microwave, ultrasonication, electron-beam, and gamma irradiation are applied in transforming the chemical structure of biomass, making the further steps of the bioprocess more effective. This chapter reviews the state-of-the-art of various irradiation techniques for the valorization of waste biomass into biofuels and chemicals. It explains specific irradiation methods as a stand-alone as well as a co-pretreatment technique with special emphasis on lignocellulosic biomass. It also dives into various biomass, products, the structural changes occurring to biomass during radiation reaction, potentialities, and challenges in upscaling the techniques to industrial application.