It should be noted that many of these technologies are engineered with reference to empirical design rules rather than being designed using formulae derived from rigorous theory.

To compare pollutant removal systems we need to look at the concept of efficiency.

After a pollutant enters a (generic) collection device there are two options:

Collection or Escape

Mass Balance

M_a=M_b + M_c..............................(1)

M_a = amount of pollutant entering device
M_b =amount of pollutant not collected
M_c =amount of pollutant collected

Efficiency F =100 M_c / M_a..............................(2)

But since M_a=M_b + M_c

We can write

F=100 M_c /( M_b + M_c)..............................(3)