Wastage: From RS pump Vs aeration tank

[mohtogh]

Hi there,
we have two optios for wastage from activated sludge WWTP,one of them is from discharge of return sludge pump and the other one directly from aeration tank.
What are the advantages and disadvanages of each method?
Could you introduce me some online sources about that?

Thanks

 

[Rich240674]

The basic difference is that RAS (Return Activated Sludge) is thicker than the Mixed Liquor in the activated sludge lanes. (RAS is drawn from the bottom of the final tanks and as such has thickened up. Often approx. 2x as concentrated).

The lanes could be controlled either way but the benefits of removing the sludge from the RAS line are that your not pumping/ transporting as much water and so you can use smaller pumps, sludge equipment etc.

Possibly would remove direct if the plant was small and the MLSS is removed directly from the lanes by a tanker etc. You should ask yourself - what is the least cost option for the works as a whole?

Hope this helps.