Ultrasonic technology alone or the combination of ultrasound with alkaline or thermal hydrolysis as pretreatment
for anaerobic digestion of activated sludge has been extensively documented. However, there
are few reports on ultrasound as pretreatment of drinking water treatment sludge (DWTS), and thereby
the characteristic variability of sonicated DWTS has not been fully examined. This research presents a
lab-scale study on physical, chemical and biological characteristics of a DWTS sample collected from a
water plant after ultrasonic treatment via a bath/probe sonoreactor. By doing this work, we provide
implications for using ultrasound as pretreatment of enhanced coagulation of recycling sludge, and for
the conditioning of water and wastewater mixed sludge by ultrasound combined with polymers. Our
results indicate that the most vigorous DWTS disintegration quantified by particles’ size reduction and
organic solubilization is achieved with 5 W/ml for 30 min ultra-sonication (specific energy of
1590 kWh/kg TS). The Brunauer, Emmett and Teller (BET) specific surface area of sonicated DWTS flocs
increase as ultra-sonication prolongs at lower energy densities (0.03 and 1 W/ml), while decrease as
ultra-sonication prolongs at higher energy densities (3 and 5 W/ml). Additionally, the pH and zeta potential
of sonicated DWTS slightly varies under all conditions observed. A shorter sonication with higher
energy density plays a more effective role in restraining microbial activity than longer sonication with
lower energy density