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 p H 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 p H factors in order to arrive at a closer estimate of the optimum conditions for the process.