If you consider the figure below,

a$)$ What type of reactor is that?

b$)$ What type of contaminant input is this?

c$)$ What does lower Kd of Sulfate compared to Boron

indicate? How is it related with affinity to column?

d$)$ What does lower Kd of Boron in $Ca/$Mg loaded resin

column $($figure on the right side$)$ indicate?