Opportunities for the development of cassava waste biorefineries for the production of polyhydroxyalkanoates in Sub-Saharan Africa

The use of plastic materials is forecasted to double by 2030 in Africa. The increase in plastic demand presents an opportunity to develop biopolymers such as polyhydroxyalkanoates (PHA) instead of petroleum-based plastics. However, the high cost of PHA production is closely linked to feedstock price, which will hinder their deployment. On the other hand, the Sub-Saharan Africa (SSA) economy is heavily reliant on agriculture, with cassava being one of the most important crops. Cassava industries in SSA produce 146 Mtpa cassava, generating an estimated 40 Mtpa waste, of which 55% goes to landfill or is incinerated. The use of cassava waste as a carbon source for PHA production, therefore, represents an opportunity to decrease production costs of bioplastics while contributing to waste management solutions. This review critically analyses the potential for developing cassava waste biorefineries for the production of PHA in SSA, a region where the bioplastics industry is in a nascent stage. We conclude that cassava waste is an adequate resource for the production of bioplastics in the SSA region that can also contribute toward the reduction of GHG emissions whilst decreasing the dependence on fossil fuels. We identify cost reduction potential with PHA-overproducing strains or strains capable of utilizing substrates more efficiently and show the economic attractiveness of using waste biomass resources in a circular economy framing. Finally, we make recommendations on the next steps needed to pave the way for sustainable economic development, job creation and industrial activity in the SSA region using circular economy principles.