ModiBioPol
Process-integrated modification of the biopolymer polyhydroxybutyrate (PHB)
Project duration
From: 01.07.2022 To: 31.12.2024Description
The primary objective of the research project was the further development and application of the continuous process developed at the Technische Hochschule Nürnberg (THN) for the production of polyhydroxybutyrate (PHB) with defined and narrowly distributed average molar masses. To date, neither literature nor patents, nor the polyhydroxyalkanoate (PHA) community, report any process or ongoing work in which fermentation can be so precisely controlled that a “target molar mass” can be reproducibly achieved.The project focused on investigating the relationship between residence time under steady-state conditions in a continuously operated reactor cascade and the resulting average molar masses and molar mass distribution, in order to enable molar mass control. This correlation has not been previously described in the literature. Continuous processes are still rarely used in the fermentative production of biopolymers, and the targeted production of PHB with desired material properties has not yet been reported. Gaining knowledge in these areas will accelerate the broader application of PHAs. In addition, the modification of the material properties of commercially available PHB was carried out by blending it with polyvinyl acetate (PVAc) using a direct extrusion process. To achieve the defined research objectives, the individual tasks were divided into a total of eight work packages. Initially, the required raw materials and equipment were procured, and all project steps were coordinated in consultation with the project advisory board. In the subsequent work packages, a continuous biosynthesis process was established and evaluated over a period of at least 1000 hours. In parallel, a continuous downstream processing method for the produced polymers was developed, considering both ecological and economic aspects. These steps formed the basis for the investigations in the following work packages on the targeted control of molecular weight—particularly through variation of the nutrient medium composition and adjustment of the residence time in the reactor. To characterize the polymers, the material properties of the synthesized polymers were comprehensively quantified. To holistically evaluate the continuous biosynthesis process, a techno-economic analysis (TEA) and a life cycle assessment (LCA) were finally conducted. Both analyses were based on the process data obtained during the project and enabled a well-founded assessment of the ecological and economic impact.
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