# Sludge Reactor Plant Homework

• 03-14-2014, 03:46 AM
javacola
Sludge Reactor Plant Homework
So I'm completely lost on how to approach this problem, but I'm not familiar with the terms and variables so I'm unable to figure out how everything is related. Any help to set me in the right direction would be appreciated.

A complete mix activated sludge plant operates at design Q, with the reactor tank volume set by a nominal [COLOR=#000000][FONT=Helvetica Neue]Θ[/FONT][/COLOR]= 6 hours.
a) It was anticipated that it would operate at 25% RAS for an expected X[SUB]r[/SUB]= 2,000 mg/l. What would the actual [COLOR=#000000][FONT=Helvetica Neue]Θ[/FONT][/COLOR] be?
b) The secondary clarifier only produces X[SUB]r[/SUB]= 1,000 mg/l, so RAS is increased to 50% Q. What is the actual [COLOR=#000000][FONT=Helvetica Neue]Θ [/FONT][/COLOR]then? Does the F/M, the MLVSS concentration and SRT change?
c) The secondary clarifier actually produces 3,000 mg/l X[SUB]r[/SUB], but RAS stays at 25% as originally planned. Do F/M, MLVSS and SRT change from what was planned??

Obviously [COLOR=#000000][FONT=Helvetica Neue]Θ is residence time, and Q is flowrate. RAS stands for return activated sludge. What in the world is Xr? I'm guessing it's some type of fraction by the X. Does anyone know how these terms are related in terms of equations? [/FONT][/COLOR]
• 03-14-2014, 07:37 AM
Kelly Bramble
First, convince me that this is not school homework...
• 03-14-2014, 07:46 AM
javacola
[QUOTE=Kelly Bramble;8650]First, convince me that this is not school homework...[/QUOTE]

It is. What's wrong with that? There are other topics on here that I see that are asking for calculation help as well. I'm not asking anyone to do it for me.
• 03-14-2014, 09:07 AM