Production, downstream processing, and characterization of polyhydroxyalkanoates (PHAs) boosted by pyruvate supplement using mixed microbial culture (MMC) and organic wastewater

The synthesis of polyhydroxyalkanoates (PHA) using mixed microbial cultures (MMC) has been studied in three stages: a sequencing batch reactor, a PHA accumulation reactor, and a pyruvate effect. Tainan pig farm, Chiayi pig farm, and Feng Chia University’s sludge were the three seed sludges tested. Two distinct substrates are used, such as effluent from sucrose acidified fermenter and molasses waste acidified fermenter. Both substrates showed significant COD and VFA, but the effluent from molasses waste acidified fermenter had more significant acetic acid and butyric acid levels, with 4,087 ± 128 and 8,151 ± 152 mL/L, respectively. The propionic acid content in effluent from sucrose acidified fermenter is more significant (4,789 ± 36 mg/L). The highest PHA production yield in the three seed sludges was 26.88%, 22.88%, and 21.90%. Tainan pig farm sludge had the highest PHA accumulation of 26.88%. This study validated MMC’s ability to produce PHA in 8 h using VFA efficiency. The present work employed the addition of pyruvate to enhance the MMC. The 1 g addition of pyruvate in a sequencing batch reactor (SBR) can increase the productivity of PHAs yielded 53.58 g PHAs/g VSS (%), respectively. Therefore, MMC boosted with pyruvate used in high organic wastewater to produce PHA could potentially further commercial activities. Graphical abstract