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　mm　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.　(C)　2015　Published　by　Elsevier　B.V.