Activated Sludge

[elarocque]

Situation 1 involves Activated Sludge for Industrial WW

his solution seems to assume point of wastage exists on the return line - how did he arrive at this assumption?-or given this is a complete mix AS situation, are we to automatically infer the point of sludge wastage occurs on the return line?

bottom line - problem is straighforward to solve only IF this point of wastage is assumed; if wastage before secondary clarification or directly from Reactor - entirely different VSS/MLVSS mass balance (obviously)

thx

-eric

 

[Dleg]

Waste activated sludge always takes place from the secondary clarifiers, same as the return activated sludge - usually accomplished with simply a different pipe and pump from the clarifier, but could also be accomplished with a valve off the return line.

So, yes, it is an assumption, but an assumption based on the fact that you pretty much have to waste from that point - it wouldn't make any sense to waste directly from the reactor (or any point between the reactor and the secondary clarifier), since the sludge isn't settled yet (very inefficient, in other words)