Biotechnology in Circular Economy: Converting Waste to Valuable Products

Abstract

A circular economy shifts production systems from linear “take-make-waste” flows to closed-loop cycles that preserve

materials, energy, and value. Biotechnology is a central enabler of this shift: microbes, enzymes, and cell factories transform

biogenic and mixed waste streams into fuels, chemicals, materials, nutrients, and proteins while reducing greenhouse-gas

(GHG) emissions and pollution. This paper synthesizes pathways that operationalize the circular bioeconomy—anaerobic

digestion to biogas and volatile fatty acids (VFAs), syngas fermentation, lignocellulose biorefineries, polyhydroxyalkanoate

(PHA) and polylactic acid (PLA) bioplastics, black soldier fly (BSF) bioconversion, algal valorization, nutrient recovery

(struvite), biosurfactants and enzymes from side streams, and bioleaching for metals. We present a decision framework

that maps feedstocks to technologies, discuss techno-economics and life-cycle assessment (LCA) evidence, outline policy

instruments that accelerate scale-up, and identify R&D gaps in feedstock heterogeneity, inhibitors, process integration,

and end-of-life circularity for bio-products.