Sequencing batch reactors let sludge settle before drawing off the supernatant. For this, decanter arms are often used. An example is here.
The challenge is to draw off the supernatant without creating turbulence, which would disturb the sedimented sludge and lead to sludge in the supernatant.
I'm willing to compromise on the amount of supernatant I draw off, say only 20% of fill level. Can I use a simple standing pipe for this, or will I get excessive sludge?
