SRT upper limit in ASM1

Hi,
I'm simulating an aerobic digestion with ASM1; I'm using a tradional ASU block; I read that the upper limit on SRT for validity of the model to single sludge systems is about 30 days; so, since my SRT is superior (40 days), what problems can I find?

thanks
iacopo

Hi Iacopo,
I am not sure I understand your question .. you mean literature suggests that the sludge age should not be more than 30 days?
If you calculate 40 days for your set up, you need to lower it by wasting more sludge, increasing the flow, reducing the volume, ... it depends on how your system is set up.