Optimization of polyhydroxyalkanoates (PHA) synthesis with heat pretreated waste sludge

To reduce the cost of polyhydroxyalkanoates (PHA) production and disposal amount of waste sludge simultaneously, the feasibility of using different heat pretreated sludge (60 degrees C, 80 degrees C, 100 degrees C, 120 degrees C) as external carbon source to synthesize PHA was examined in this study. The maximal PHA accumulation (24.1% of the dry cell weight) was achieved with 60 degrees C pretreated waste sludge, with the utilization efficiency of COD, proteins, carbohydrate and VFAs were 74.3%, 82.3%,47.2%,81.4%, respectively. Both of VFAs and non VFAs organics could be used as carbon source for PHA synthesis. The results of kinetic parameter analysis showed that the highest PHA production rate (0.23 mg COD/mg X. h) and the PHA conversion rate (0.46 mg COD/mg COD) all occurred when using 60 degrees C pretreated waste sludge. In order to further investigate the utilization of sludge carbon source for PHA synthesis, the three-dimensional fluorescence excitation-emission matrix (EEM) spectroscopy with fluorescence regional integration (FRI) analysis were introduced. (C) 2018 Elsevier Ltd. All rights reserved.