Thermogravimetric analysis of activated sludge flocculated with polyelectrolyte

This work examines the thermal pyrolysis characteristics of polyelectrolyte-flocculated activated sludge at a heating rate up to 873 K by means of thermogravimetric analysis (TGA). Although the polyelectrolyte does not affect the pyrolysis rate of the sludge at a temperature of 8 or 14 K/min, using polyelectrolyte flocculation to charge neutralization appears to accelerate the pyrolysis process at 20 K/min. TGA/mass spectrometer tests were performed to identify the species released during pyrolysis of the sludges. A parallel-reaction kinetic model (Reactions 1 and 2) was applied to interpret the experimental data, with Reaction 1 corresponding to the release of C7H14 equivalents or lighter, and Reaction 2 corresponding to the heavier compounds. Using polyelectrolyte flocculation to change the neutralization point enhances Reaction 1 by transforming the heavier organics that are originally released at elevated temperature (Reaction 2) to the lighter compounds in the low-temperature regime (Reaction 1).