Analysis of the fermentation strategy and its impact on the economics of the production process of PHB (polyhydroxybutyrate)

Abstract

PHB (polyhydroxybutyrate) is a biodegradable polymer that can replace petrochemical polymers due to its properties and applications. However, its commercial use remains limited because of its high production cost. In this work, factors affecting the PHB fermentation reactor and its impact on the production cost are studied. The production process considers the sucrose fermentation with Azohydromonas australica, followed by the PHB purification and drying. The proposed methodology is divided into two stages: firstly, the analysis of the reactor where it is necessary to define the operation mode and the operating conditions to achieve high product yield and productivity; and secondly, the analysis of production process using technical, economic and environmental criteria to evaluate the process conceptual design. The proposed methodology can reduce complex efforts to achieve an efficient fermentation and validate the design of PHB production process, thereby enabling a biopolymer production with a competitive cost and low environmental impact. The best operation mode for the fermentation reactor was fed-batch, whose feeding strategy allowed to achieve satisfactory technical-economic-environmental results for the PHB production plant: product yield of 0.36g PHB/g sucrose, productivity of 1.6g/L/h, production cost of 2.6USD/kg PHB, return on investment of 34.2%, payback period of 2.9yr, emissions of 1.7kg CO2/kg PHB, energy consumption of 10.1MJ/kg PHB and process requirement of 16.9kg water/kg PHB.