DIRECT EXTRUSION OF PHA-RICH BIOMASS

It is known that several bacteria in sewage treatment plants can produce attractive quantities of- biodegradable polymers within their cell walls (up to 80% of the cell weight). These polymers may consist of polyhydroxyalkanoates (PHA), a bioplastic which exhibits interesting characteristics like excellent biodegradation, low melting point and good environmental footprint. PHA bioplastics or PHBV are still quite expensive because cumbersome downstream processing steps of the PHA containing bacteria are needed before PHA can be applied in products. In this project, the consortium (Paques Biomaterials, MAAN Group, Ecoras and Avans CoEBBE) investigated the possibilities for eliminating these expensive and environmentally intensive purification steps. The objective of the project was to investigate the possibilities of direct extrusion of PHA-containing bacteria and the application opportunities of the extruded PHA. The results showed that is possible to directly hot press PHA rich biomass, to extrude PHA rich biomass into filaments. The quality of the filaments highly depends on the PHA content of the PHA rich biomass. This quality can be improved by blending the PHA rich biomass with other commercial polymers. The study also looked into the most promising markets for direct extruded PHA rich biomass, the possible financial savings and the sustainability of this new processing route compared to extraction of PHA

It is known that several bacteria in sewage treatment plants can produce attractive quantities of
biodegradable polymers within their cell walls (up to 80% of the cell weight). These polymers may
consist of polyhydroxyalkanoates (PHA), a bioplastic which exhibits interesting characteristics like
excellent biodegradation, low melting point and good environmental footprint. PHA bioplastics or
PHBV are still quite expensive because cumbersome downstream processing steps of the PHAcontaining bacteria are needed before PHA can be applied in products. In this proposal, the
consortium investigates the possibilities for eliminating these expensive and environmentally
intensive purification steps, and as a result contribute to speeding up the up-take of PHA
production of residual streams by the market.
The objective of the project is to investigate the possibilities of direct extrusion of PHAcontaining bacteria and the application opportunities of the extruded PHA. The consortium of
experienced partners (Paques Biomaterials, MAAN Group, Ecoras and CoEBBE) will investigate and
test the extrusion of different types of PHA-containing biomass, and analyse the products on
composition, appearance and mechanical properties. Moreover, the direct extrusion process will
be evaluated and compared with conventional PHA extraction and subsequent extrusion.
The expected result will be a proof of principle and provide an operational window for the
application of direct extrusion with PHA-containing biomass produced using waste streams, either
used as such or in blends with purified PHA. Both the opportunities of the direct extrusion process
itself as well as the application opportunities of the extruded PHA will be mapped. If the new
process leads to a cheaper, more environmentally friendly produced and applicable PHA, the
proof of principle developed by the consortium could be the first step in a larger scale
development that could help speeding up the implementation of the technology for PHA
production from residual streams in the market.