Polyhydroxyalkanoates (PHAs) Production from the Liquid Fraction of dried/shredded Food Waste

An enriched culture of Polyhydroxyalkanoates (PHAs)-forming bacteria was developed using the liquid fraction (condensate) which is generated during drying and shredding of food waste. A mixed enriched culture was used for the production of PHAs, in two Draw-Fill Reactors (DFRs). The culture was developed using cyclic limitation by carbon and nitrogen. Urea was used as nitrogen source and a mixture of volatile fatty acids (VFAs), lactic acid, ethanol and glucose, simulating the composition of the condensate as carbon source. Two cycles of experiments were performed aiming to investigate the effect of the organic loading on the yields and composition of the produced PHAs. The results showed that the organic loading did not significantly affect the accumulation capacity of PHAs, with the average yield for DFR-1 being 16±5% g PHAs/g DCW (dry cell weight) and for DFR-2 19±3% g PHAs/g DCW. The HV:HB ratio in DFR-1 was estimated to be (19±4):(81±4), whereas in DFR-2 (26±2):(74±2) indicating that the availability of more odd-VFAs may lead to the production of copolymers with higher HV content i.e. a bioplastic with improved properties.