Exploration of a novel biorefinery based on sequential hydropyrolysis and anaerobic digestion of algal biofilm: a comprehensive characterization of products for energy and chemical production

Abstract

This study presents an extensive and detailed characterization of products from hydropyrolysis and anaerobic digestion and proposes a multi-pathway assessment of algal biomass conversion. An algal biorefinery based on sequential hydropyrolysis (HyPy) and anaerobic digestion (AD) of algal biofilm has been comprehensively studied for the first time. Wet and untreated biomass from algal biofilm was directly employed as feedstock for the HyPy–AD coupled process and the products obtained were characterized by GC-MS, LC-MS, HPLC, CHNS, SEM and TEM. Based on different morphological and structural characterizations, different biorefinery routes were assessed in terms of net energy recovery and ecological impact. Upto 42% biocrude yield and 200 mL g_VS⁻¹ biomethane yield with a net energy ratio (NER) of 1.5 were observed for the coupled process of HyPy and AD, giving it a cutting edge over other conversion routes. A biorefinery based on these results has been presented considering a sustainable approach to valorize whole algal biomass towards multiple product recovery.