Factorial experiments in sequence: The attainment of optimum conditions for a decontamination process

The advantages of factorial design are first illustrated by a simple experiment devoted to the effect of two pH factors and an iron‐concentration factor on the efficiency of a decontamination process employing iron sulfide as a scavenging agent. The broadening of the base of an investigation by the expansion of a factorial is illustrated by addition of the sulfide concentration as a factor. Finally the principle of expanded factorials is further utilized in the later phases of the study, in which additional levels are assigned to the pH factors in order to arrive at a closer estimate of the optimum conditions for the process.