Sustainable Biopolymers Production Using a Bioethanol Residue as Raw Material

Vinasse, a by-product of bioethanol production, can be transformed by biotechnological processes into valuable compounds. In this work, the feasibility of incorporate a poly(hydroxyalcanoate)s (PHA)s production process to a bioethanol plant was evaluated. A superstructure whose objective function is maximization of the net present value (NPV) was run employing data reported in the literature about PHAs productivities by using different bacteria strains and vinasse as carbon source. Integration of a PHA production process to a bioethanol plant can produce economic benefits along with a reduction in the environmental impact caused by the disposal of vinasse residue. Positive NPV were reached for some analyzed scenarios, indicating that economic benefits are being obtained or meet the expectations of the investment project. The maximum obtained NPV was 35.09 million dollars using Haloferax mediterranei and a medium with 25% vinasse, pretreated with activated carbon. PHA production cost was calculated and resulted economically competitive compared to PHA production at industrial level. To estimate the economic outcome, the investment viability was evaluated using the project’s internal rate of return (IRR) and calculating the payback period (PBP) and the return on investment (ROI). Finally, a sensitivity analysis was performed to study the influence of different parameters (price, accumulation, and yield of PHA, as well as the cost of thermal and electrical energy) over the NPV and it can be concluded that polymer accumulated by the microorganism and PHA selling price are the most significant factors. Graphical Abstract