Question

A water treatment plant has 6 settling tanks
that operate in parallel (the flow gets split into
six equal flow streams), and each tank has a
volume of 600m3. If the flow to the plant is
10 mgd, what is the retention time in each
of the settling tanks? If, instead, the tanks
operated in series (the entire flow goes first
through one tank, then the second, and so
on), what would be the retention time in each
tank?

Answer 1

23

Answer 2

1.) parallel
Q1=Q2=Q3=Q4=Q5=Q6= (440L/s)/(6)
t=V/Q=((600m^3)/(440/g L/s))x (1000 L)/ (1m^3L = 8181.82 s

2.) series
Q1=Q2=Q3=Q4=Q5=Q6= 440L/s
t= (600 m^3)/(440 L/s) x (1000L/m^3) = 1363.64 s