An electrostatic precipitator, particularly a WESP, comprising an array of collector tubes and a like array of separately powered discharge electrodes provided in the form of pairs of rods extending within each of the collector tubes. The pairs of rods are provided in the form of a first length rod having a terminal end, the first length rod powered by a first power source, and an axially opposed, second length rod having a terminal end, the second length rod powered by a second power source, wherein each first length discharge electrode rod, of a pair of rods, extends from an inlet of the electrostatic precipitator into a respect e collector tube and each second length discharge electrode rod, of the same pair of rods, extends from an outlet of the electrostatic precipitator into the same, respect e collector tube such that the respective terminal ends of the pairs of discharge electrode rods are spaced apart, thereby defining a gap therebetween. This arrangement enables different energy levels to be applied to each of the first and second length discharge electrode rods of the pairs of discharge electrode rods, by the first and second power supplies, respectively, thereby inducing different levels of ionization within a gas stream flowing through the collector tube array of the electrostatic precipitator, at different locations within the electrostatic precipitator.