Characteristics of extracellular polymeric substances and bacterial communities in an anaerobic membrane bioreactor coupled with online ultrasound equipment

► Cake layer has a relatively high content of extracellular polymeric substances. ► Some bacterial strains are found in high relative abundance in cake sludge samples. ► Cake layer provided a more stable environment for bacteria than mixed liquor. ► Ultrasound irradiation leads to bacterial transformation in bulk sludge.