Ballast　flocculation　by　recycling　drinking　water　treatment　sludge　(DWTS)　is　an　alternative　to　traditional　coagulation　and　pretreatment　of　the　membrane-based　process.　However,　the　enhancement　of　organics　removal　is　limited　due　to　the　release　of　organics　derived　from　sludge.　This　study　mainly　focused　on　the　characteristics　of　solubilized　organics　derived　from　DWTS　exposed　to　different　ultrasound　conditions　(ultrasound　dose　of　2.53,　5.10,　7.73,　10.42,　and　15.79Wh/L,　frequency　of　25/40kHz).　The　effect　of　solubilized　matter　in　the　coagulation　process　of　recycling　pre-sonicated　DWTS　on　organics　removal　was　also　assessed.　The　results　indicated　that　protein-like　substances　(Peaks　T-1　and　T-2)　and　humic-like　substance　(Peak　A)　occurred　in　raw　DWTS　samples.　The　kinetic　model　of　soluble　chemical　oxygen　demand　(SCOD)　solubilization　was　pseudo-linear,　and　the　rate　of　SCOD　released　at　40kHz　was　higher　than　that　at　25kHz,　which　could　be　confirmed　by　the　increase　in　fluorescence　intensities　of　Peaks　A,　T-1,　and　T-2　in　the　supernatant　of　sonicated　DWTS.　Additionally,　the　release　velocity　of　protein-like　substances　at　40kHz　was　more　rapid　than　that　at　25kHz.　The　results　of　recycling　trials　indicated　that　solubilized　organics　could　deteriorate　the　settled　water　quality,　independent　of　the　ultrasound　conditions　used.