PROGRAMME

Progress in the implementation of polyhydroxyalkanoates (PHAs) as a viable option, for single-use packaging has been attained recently. Mixed Microbial Cultures (MMCs) have been tested extensively to produce PHAs due to their potential in reducing costs both by utilizing organic wastes as feedstock and by minimizing aseptic conditions. Replacing single-use petrochemical plastics with materials manufactured using organic wastes could be a significant step in the advancement of circular economy. Optimization of MMC enrichment in PHA producing microorganisms is crucial for the maximization of PHA production. Feast and Famine conditions are usually selected for PHA producing organisms. Draw-fill reactors were used using 3.5 days cycles and Sludge Retention Time (SRT) of 7 days to simplify the enrichment procedure. The biomass was enriched with PHA producing microorganisms with Organic Loading Rates of 50 and 83 Cmmol/day. Growth conditions with and without aeration were tested. Accumulation of PHA bioplastics was also carried out using Draw and fill reactors with the enriched biomass to obtain product above 40% by weight of cell mass. The production was validated gravimetrically and qualitatively with Nile Red microscopy. Extraction with chloroform was performed to obtain films. COD, VFA and ammonia measurements were performed to elucidate the process. Biomass growth of 0.43 g/(LxD) was achieved using 83 Cmmol/day, while growth using 50 Cmmol/day was insignificant. Aeration was found to be imperative for growth. Strategies for process optimization are discussed.