Enhanced recovery of polyhydroxyalkanoates from secondary wastewater sludge of sewage treatment plant: Analysis and process parameters optimization

The present study was aimed to recover and characterize the polyhydroxyalkanoates (PHA) from secondary sludge biomass of sewage treatment plant (STP) extracted by organic solvent under optimized conditions. The maximum recovery yield and purity of PHA were 8.3% and 96%, respectively under optimized conditions of incubation time 72 h, reaction temperature incubation at 75 °C, and sludge solid to chloroform ratio 1:20 (w/v). The maximum PHA concentration was 9.58 g/L, under optimized conditions. Spectroscopic analyses of recovered polymer were revealed the presence of 3-hydroxybutyrate (90%) and 3-hydroxyvalerate (10%) monomers content. PHA was thermally stable at below 260 °C, as confirmed by TGA and DSC analyses. This study concluded that sewage sludge can be a sustainable substitute to recover PHA due to enormously maximum PHA yield, inexpensive feedstock, and subsequently decrease the excess sludge burden generated from STP. © 2021 Elsevier Ltd