ENVE 331, Winter 2009
Homework #2
Due on February 4
th
2009
Mass Balance Problems:
Problem 1:
Alcohol
containing 15% salt is fed at a rate of 10 kg/min in a mixer (CSTR) that initially holds 100 L
of
5% salt in alcohol.
The exit solution leaves the mixer at a rate of 10 kg/min.
Determine the exit
concentration after 30 minutes in
ppm
and assume complete mixing.
The density of alcohol is 0.8 g/mL
and can be assumed constant due to low salt concentration.
Problem 2:
A CSTR is running at steady state with a flowrate of 50 mL/min.
At any instant of time you started
injecting a dye (2 mL/min with a dye concentration of 100 g/L) in the inlet line and continued to do so.
The inlet flow rate
turned to (50+2) 52ml/min and the volume of the CSTR is 2500 ml.
No reaction occurs
in the reactor.
Find the concentration of the dye after 15 and 30
minutes.
Problem 3:
A lake with a surface area of 1.13 mi
2
, is fed by a river with a flow rate of 5000 cfs.
The flow
rate in the river exiting the lake is 6000 cfs.
A wastewater treatment plant discharges into the lake at the
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Winter '08
 VIGIL
 Environmental Engineering, Sewage treatment, Rate equation, koi pond

Click to edit the document details