High sludge index and recirculation problem

asked 9 August 2018 asked by Amphinitrate (1080 points)

I am operating a 1500-PE treatment plant; I performed my tests, namely V30 with 1/4 dilution and sludge weight. For sludge concentration in the aeration tank, I have 2.88 g of SS. For the return activated sludge, the concentration is 1.36 g of SS. For the V30, I get 150 ml. I usually recirculate at 150%; but, is it normal to have a lower concentration in the RAS compared to the aeration tank? I also have an SVI with these values that is at 194, which is a sign of poor settling. What can I do to fix these issues?

2 Answer(s) 0 votes

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Your sludge index is just above 200 mL/g, which indicates settling problems (and maybe a bulking issue). You are also seeing this poor settling in your recirculation rate.

I have a few questions:

- Has your SVI varied by more than 40 ml/g since your last analysis?

- What is the separation of sludge/water in your V30 test and sedimentation tank like?

- Do you see any gas bubbles in your sludge?

- Are you loosing SS?

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