In　order　to　find　the　optimal　SRT　and　temperature　for　TAD,　Aerobic　thermophilic　stabilization　and　degradation　of　waste　activated　sludge　from　wastewater　treatment　plant　was　studied.　The　experimental　was　divided　into　two　parts.　In　first,　Batch　experiments　were　performed　at　temperatures　of　40,　45,　50　and　55　degrees　C.　The　most　beneficial　temperature　for　aerobic　digestion　of　waste　activated　sludge　was　found　to　be　55　degrees　C.　Semi-continuous　feed　reactor　was　used　to　study　the　effect　of　SRT　in　the　second　part　of　experiments.　Temperature　was　maintained　at　55　degrees　C,　and　SRT　were　set　to　4,8,12　days　in　turn.　The　average　VSS　destruction　efficiency　was　36.8%,　46.7%　and　47.1%,　respectively.　VSS　destruction　rate　increases　as　the　SRT　was　increased,　but　No　significant　difference　between　8　days　and　12　days.　Higher　pH,　alkalinity　and　ammonia　concentration　was　found　in　TAD　reactor　mainly　because　of　the　nitrification　inhibition　at　high　temperature.　Alkalinity　and　ammonia　concentration　generally　increased　at　longer　SRTs.