Microbial Poly-β-hydroxyalkanoate Accumulation for Biodegradable Plastic Production: Oral presentation by Lei Liu

The raw material for biodegradable plastics, poly-β-hydroxyalkanoates (PHAs), can be produced microbially by converting sludge volatile solids (VS) to volatile fatty acids (VFAs), which are then fed to PHA-accumulating bacteria. The method helps to reduce environmental pollutions by replacing the traditional plastic from petroleum industry. Researchers have succeeded in producing PHAs in this transform process. Morgan-Sagastume et al. (2015) achieved a PHAs yield of 0.4 g/g VSS in wastewater using a feast and famine process. Additionally, Bengtsson et al. (2017) gained a PHAs yield of 49 % of VS during wastewater treatment by removing carbon and nitrogen in anaerobic feast and aerobic famine system (Bengtsson et al., 2017). However, in this study, the feast-and-famine process could not be used to convert VFAs to PHAs in a wastewater treatment process with chemical phosphorus precipitation, but PHA-accumulating bacteria could be cultivated using continuous aeration. Sludge containing PHA-accumulating microorganisms was added to the hydrolyzed activated sludge bioreactor five times in a semi-continuous process simultaneously with acetic acid. After 64 days, the final PHA concentration was 80% of volatile solids.

Keywords
Polydroxyalkanoates, Volatile fatty acids, Wastewater sludge, pH

References
Bengtsson, S., Karlsson, A., Alexandersson, T., Quadri, L., Hjort, M., Johansson, P., Morgan-Sagastume F., Anterrieu S., Arcos-Hernandez M., Karabegovic, L., Magnusson, P., Karabegovic, L. (2017). A process for polyhydroxyalkanoate (PHA) production from municipal wastewater treatment with biological carbon and nitrogen removal demonstrated at pilot-scale. New biotechnology, 35, 42-53.

Morgan-Sagastume, F., Hjort, M., Cirne, D., Gérardin, F., Lacroix, S., Gaval, G., Karabegovic, L., Alexandersson, T., Johansson, P., Karlsson, A., Bengtsson, S., Arcos-Hernández, M.V., Magnusson, P., Werker, A. (2015). Integrated production of polyhydroxyalkanoates (PHAs) with municipal wastewater and sludge treatment at pilot scale. Bioresource Technology, 181, 78-89.