Converting Wastewater Treatment Plants into Polyhydroxyalkanoate Production Factories

Fossils derived plastics offer a wide range of services in applications, frompackaging to building and construction, to electronics and water distribution networks. The use of fossils to produce plastics releases the stored CO2 and contributes to climate change. Due to durability and resistance to degradation, discarded plastics accumulate in the environment and affect the ecosystems. Polyhydroxyalkanoates (PHA) are considered as an alternative for bio-based and biodegradable plastics. PHA is a family of polyesters that is naturally synthesised by microorganisms. After extraction and purification, PHA shows thermoplastic properties similar to polypropylene and polyethylene. However, the current market share of all bioplastics in the overall plastic industry is small (3%) (Plastics Europe, 2020). Efforts are urgently needed to expand the global potential for greater capacity in bioplastics production. PHA may be accumulated directly using the waste activated sludge from wastewater treatment plants. Currently, methods and experiences for PHA accumulation directly using waste activated sludge are still at the pilot scale. This thesis critically evaluated the current status of the technology, identified knowledge gaps and then focused on deepening insight and fundamental understanding to help facilitate a scaling up to industrial scale.