The concept of a characteristic reaction time is applied to the flocculation reaction and proposed
for use as a new guideline for the design of continuous flow flocculators. The proposed
guideline suggests designing flocculators on the basis of the characteristic reaction time for the
loss of one micrometer of particles in the suspension. Based on the current understanding of
flocculation processes and classical chemical engineering design principles, this new guideline
has several advantages over the currently accepted design guidelines. These advantages are
discussed in the paper and the new approach illustrated by comparison with the design of an operating water
treatment facility. Includes 9 references, tables, figures.