Dislodged　sludge,　a　kind　of　industrial　waste,　was　used　as　raw　material　to　prepare　silica　aerogels　via　ambient　pressure　drying.　The　effect　of　solvent　exchange　and　surface　silylation　on　the　pore　structure　and　property　of　the　obtained　materials　was　investigated　in　detail.　If　the　ethanol　and　n-hexane　exchange　decreases　to　8　h　(two　times,　each　time　for　4　h)　and　4　h　(one　time),　respectively,　and　the　volume　ratio　of　ethanol/wet　gel　and　n-hexane/wet　gel　reduces　to　2　and　1,　respectively,　the　obtained　materials　exhibit　a　desirable　pore　volume　of　3.17　cm(3)/g,　a　water　contact　angle　of　152.9A　degrees　and　a　low　thermal　conductivity　of　0.030　W/　(m　center　dot　K).　Further　decreasing　the　mole　ratio　of　silylation　agent/SiO2　to　0.5　and　the　silylation　time　to　6　h　results　to　silica　aerogels　with　a　pore　volume　of　3.44　cm(3)/g,　a　water　contact　angle　of　144.5A　degrees　and　a　low　thermal　conductivity　of　0.032　W/　(m　center　dot　K).　A　rapid　synthesis　(a　total　time　of　50　h,　from　wet　gel　aging　to　ambient　pressure　drying)　of　silica　aerogels　has　been　realized　and　the　consumption　of　solvent/silylation　agents　has　been　pronouncedly　reduced　without　sacrificing　the　thermal　insulation　property　of　the　obtained　materials.