(465a) Process Design and Scale-up Study for the Production of Polyol-Based Biopolymers from Sawdust

Polymers are materials with exceptional properties that contributed to the development of modern societies (Thompson et al., 2009; Yarsley and Couzens, 1945). However, multiple environmental threats associated with their extensive use have been revealed. The difficult and slow degradability of these materials, which leads the generation of micro-plastics polluting soils and fresh and marine waterbodies, is an environmental issue of major concern. This requires the development of new environmentally and economically sustainable materials with adequate properties capable to replace traditional petroleum-based polymers. Different wastes are emerging as interesting raw materials for this purpose, which use to produce new polymers also contribute to reduce the environmental footprint of modern societies. Particularly, sawdust is a by-product of the forestry industry which can be used as raw material for the production of added-value bio-based chemicals, leading to the development of a circular economy based on this organic resource. One of the most promising paths for the reuse of sawdust is the production of polyols, which in turn can be used as raw material for obtaining biopolymers capable of replacing crude derived polymers, changing the paradigm of the polymer industry towards a more sustainable model.

A conceptual design and techno-economic evaluation of a process for the production of polyol-based biopolymers from sawdust at full-scale have been performed in this work. The process has been designed following the premise of being as environmentally sustainable as possible, but using simple equipment feasible to be deployed and operated by the timber facilities. It consists of preparing the raw material, the catalysis and glycerol for the solvolysis reaction followed by the purification of the polyol and finally the production of the bio polymer adding starch. A fraction of the sawdust processed is combusted to cover the thermal energy requirements of the process rather than using external fossil fuel supplies. The performance of the process stages is assessed based on experimental data (CIPA, 2017).

The results show that, as a result of the low capital expenses required, the deployment of the process proposed has a low economic entry barrier. However, the intensive use of raw materials results in most of the production costs are due to raw materials cost. In order to evaluate the effect of the scale in the economy of the process, a scale-up study has been performed. It is revealed that production costs are largely affected by the economies of scale, allowing a significant reduction of the investment per unit of waste processed as the facilities increase their size. For the typical range of market prices of glycerol and starch, the production cost ranges from 0.10 to 0.66 USD per kilogram of biopolymer produced.

References

CIPA, 2017. Biodegradable polymer based materials using Wood residues of SME from wood industry in Chile's Biobío region. R15F10009. Technical Report. Centro de Investigación de Polímeros Avanzados.
Thompson, R.C., Moore, C.J., Vom Saal, F.S., Swan, S.H., 2009. Plastics, the environment and human health: current consensus and future trends. Philosophical Transactions of the Royal Society B: Biological Sciences 364, 2153-2166.
Yarsley, V., Couzens, E., 1945. Plastics Middlesex. Penguin Books Limited.