The Use of Low Frequency Ultrasound to Disintegrate Filamentous Bacteria

Abstract

The increase in the number of filamentous bacteria in activated sludge causes complications in the functioning of the sewage treatment plant. The paper presents the results of investigation of activated sludge coming from two sewage treatment plants -municipal and industrial. In both treatment plants the increase in the number of filamentous bacteria in winter has been noticed. In order to reduce the number of filamentous bacteria in activated sludge, the sludge samples were subjected to ultrasonic disintegration at a frequency of 40 kHz at 1, 2, 3, 5, 10 and 20 minutes. The use of low frequency ultrasounds has contributed to the defragmentation and destruction of most filamentous bacteria in activated sludge after 10 minutes of their operation. Necessary time to almost complete defragmentation of filamentous bacteria is more than 20 minutes.