Techno-economic and environmental assessment of glycerol valorization to polyhydroxybutyrate using chemical digestion methods

Abstract

Polyhydroxybutyrate (PHB) is a biodegradable polymer that can be produced from glycerol, a major by-product of biodiesel plants. However, the high production costs associated with the inefficient downstream process have impeded the commercialization of PHB. Previously, several methods have been demonstrated capable of recovering PHB^__ among them, chemical digestion appeared to be the most effective. There are various classes of chemical digestion. This study examined the processes of PHB production from glycerol using three different classes of chemical digestion including alkaline digestion, surfactant digestion, and alkaline−surfactant digestion for PHB recovery. The processes are evaluated based on performance indexes, such as techno-economic, energy utilization, and greenhouse gas (GHG) emissions. According to the simulated results, the use of alkaline digestion for PHB recovery is economically attractive. Based on PHB production capacity of 5,000 tonnes/y, the best production provides a net present value of 442 million USD, an internal rate of return of 76.6 %, and a payout period of 2.48 years. Furthermore, important findings from this investigation also reveal that heat integration not only reduces energy consumption but also minimizes operating costs and GHG emissions. Therefore, the production of PHB from glycerol using alkaline digestion for PHB recovery may find commercial application in the bioplastic industry.