What are the main differences between Batch reactor, Complete Mixed Flow Reactor and Plug Flow Reactor?

$2.$ A CMFR reactor is filled with clean water prior to being started. After startup, a waste stream containing $50m\frac{g}{L}$ of a conservative pollutant is added to the reactor at a flow rate of $25\frac{m^3}{?}$ day. The volume of the reactor is $400m^3.$

a$.$ What is the concentration exiting the reactor as a function of time after it is started?

b$.$ Draw the figure of outlet concentration versus time $($tip: you can use Excel$)$

c$.$ Calculate the concentration exiting the reactor after $60$ days of operation.