A swirling jet-induced cavitation to increase activated sludge solubilisation and aerobic sludge biodegradability

At the optimum operating conditions, the specific supplied energy has been varied from 3276 to 12,780 kJ kg TS−1 in the HC treatment, by increasing the treatment time from 2 to 8 h, respectively. Low endogenous decay rates (bH) were measured on the excess sludge at low specific supplied energy, revealing that only an alteration in floc structure was responsible for the sludge solubilisation. On the contrary, higher bH values were measured at higher specific supplied energy, indicating that the sludge solubilisation was related to a decreasing biomass viability, as consequence of dead cells and/or disrupted cells (cell lysis).