Preliminary optimization of the environmental performance of PHA downstream processing

Abstract

As downstream processing has been identified as a bottleneck for the sustainable development of the polyhydroxyalkanoates (PHAs) value chains, this work aims to provide new insights for the optimization of its environmental performance. After identifying the most promising methods for PHA recovery and purification, four processes with two different system functions,high- and low-grade PHA, were defined and scaled up. The environmental performance of these processes was evaluated by life cycle assessment (LCA). Processes based on solvent extraction showed a worse environmental performance due to the high energy requirements of solvents recovery. Processes relying on chemical digestion showed a better environmental performance when combined with other technologies such as high pressure homogenization, which allows a reduction of the amount of chemicals employed. Therefore, two main improvement actions were proposed to overcome these hotspots and estimate the environmental burdens reduction: heat integration in larger facilities would reduce the heat duty, while introducing a chemical recovery unit or combining chemical digestion with other technologies would reduce those impacts related to chemicals consumption. Through this work, it is demonstrated that the environmental performance of PHA downstream processing can be improved if the process design include life cycle assessment from its conception