The mechanical and cavitation effects of low intensity ultrasonic irradiation on the biological activity of sludge
低强度超声波辐射对污泥生物活性的影响机制

he mechanism of biological activity enhancement of sludge by low intensity ultrasound was investigated based on the sludge characteristics before and after ultrasonic treatment, the impact of different ultrasonic treatment patterns, as well as the effect of addition of the radical scavenger NaHCO3. Test results indicate that due to the mechanical and cavitation effects of the low intensity ultrasound irradiation, the sludge flocs disintegrated; the liquid-solid mass transfer of the system improved; the activity of microbial enzymes was enhanced; and the concentration of biodegradable substances in the mixture increased. On the other hand, a large number of free radicals were generated during ultrasonic cavitation, which could inhibit or even damage the biological activity of the cells. Therefore, the effect of low intensity ultrasound irradiation on the sludge activity is a complex combination of enhancement and inhibition.