초록
<P><B>Abstract</B></P> <P>As the circular bioeconomy is gaining momentum around the globe, biorefinery will play a key role in the framework of sustainability as integral component. A self-sustainable biorefinery model using azolla cultivation was designed at the focal point of a circular loop. This model is aimed to enable a cascading valorization of bio-based products through a series of sequentially integrated biological/thermal unit operations. <I>Azolla pinnata</I> with an inherent ability to sequester CO<SUB>2</SUB> along with simultaneous nitrogen fixation capability will serves as a potential and renewable carbon resource (feedstock) for the integrated unit operations viz., acidogenesis, photosynthesis, hydrolysis, and pyrolysis. The cascading loop is initiated by acidogenesis of spent wash (distillery wastewater-DSW) in a semi pilot scale bioreactor for the production of biohydrogen and volatile fatty acids (VFA). Treated spent wash after acidogenesis (TSW) was used as feed for <I>Azolla pinnata</I> cultivation, which eventually depicted good COD and nitrates removal efficiency. Harvested <I>A. pinnata</I> biomass (AB) showed presence of good amount of carbohydrates (237 mg/g) and proteins (160 mg/g) along with 11% of lipids (composed of 22% omega fatty acids) thus making it a good nutritional feed for livestock. AB after lipid extraction was subjected to mild acid-hydrolysis and the hydrolysate was used as substrate for acidogenesis to facilitate circular/closed loop operation. The techno-economics of biorefinery process evaluated using SuperPro Designer software depicted the feasibility of the integrated strategy. This study extends the scope of biobased platform with self-sustainability as core objective.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Self-sustained azolla-biorefinery for valorization of multi-biobased products. </LI> <LI> Sequentially integrated bioprocesses a design strategy to enhance product benefit. </LI> <LI> Biorefineries benefit resource conversion efficiency. </LI> <LI> Circular-loop design yields economical and environmental sustainability. </LI> <LI> Azolla hydrolysate as a substrate for acidogenesis for production of biohydrogen. </LI> </UL> </P>