In chemical engineering, a cascade is a plant consisting of several similar stages with each processing the output from the previous stage. Cascades are most commonly used in isotope separation, distillation and other separation or purification processes.
Examples
If a still removes 99% of impurities from water (leaving .01 the original amount of impurities), a cascade of three stills will leave (1-0.99)3 = 0.000001 = 0.0001% the amount of impurities (99.9999% removed).
