Clarifiers

CWLP has a total of five clarifiers, representing three different technologies. The oldest technology is the Spaulding Upflow Clarifer, which was designed by the utility's first Water Plant Superintendent, Charles Spaulding, and placed into operation when the lakeside Water Purification Plant was built in 1935. For many years, this type of clarifier was considered state-of-the-art. It is still used by purification plants around the world. In Spaulding Upflow Clarifiers, water flows downward, through a large inverted cone in the center of the clarifier. At the bottom of this cone, a series of revolving paddles mix the water and chemicals used in the treatment process—including ferrous sulfate and polymer, which help dirt and other suspended particles coagulate (stick together). Then, flowing outward and upward into the main body of the clarifier, the water passes through a "blanket" of lime sludge formed from an accumulation of coagulated particles. Most of the suspended particles in the upflowing water are trapped there. The cleaned water then flows over the top of the clarifier and heads to the filter gallery.

The second type of clarifier currently being used by CWLP is a Permutit unit, which is simply a modified version of the Spaulding clarifier.

The third and newest model, is the Helical Flow Clarifier, designed by another former CWLP Water Plant Superintendent, Dave Wyness. In this type of clarifier, the water is introduced into the base of the clarifier where it moves upward in an ever expanding and slowing spiral motion, passing through the lime sludge blanket on its way. The Helical Flow Clarifier is superior to the Spaulding unit in two ways. First, it has no moving parts and requires no power to operate. Second, it is better at removing suspended particles, producing a better overall water quality. As in the Spaulding Clarifiers, water that has passed through the sludge blanket then overflows the top of the clarifier and heads to the filter gallery for the final stage of purification.