ACOUSTIC SONICATION EFFECTS ON SEWAGE SLUDGE DISINTEGRATION

Abstract

This work aimed at investigating the effect of audible frequency (F_S = 12 kHz) on sludge pretreatment by sonication (US) under pressure for the first time. The main US parameters (power -P_US, intensity -I_US) were also looked into. The higher P_US, the higher sludge disintegration (DD_COD) was achieved due to the increase in cavitation intensity, e.g. at 7000 kJ/kg_TS, DD_COD improvement was about 74% when increasing P_USfrom 50 to 360 W (I_US of 5.2-37.4 W/cm²). In addition, about 16% of DD_COD improvement was achieved when switching from 50W-SP to 360W-BP at same I_US (about 37.5 W/cm²). Besides, sludge disintegration was significantly improved by low frequency US (12 vs. 20 kHz) due to more violent cavitation: by 64% at ES of 7000 kJ/kg_TS.  Positive effect of pressure associated with high P_US and low F_S was also found. This work provided general information and trends related to sonication process to be used or checked in other potential applications of physical effects of acoustic cavitation.