Lime Softening Process
Spiractors

In the early 1960's through the late 1970's, the City constructed and expanded its water treatment facility with a lime softening system. Currently the City of Hollywood has twelve Spiractors manufactured by the Permutit/US Filter Corporation. Spiractors are sand filled conical shaped tanks that soften water by a process technically known as Fluidized Bed Crystallization. This process removes minerals that cause hard water by precipitating them onto sand particles, known as "seed," which are suspended in the water. The term spiractor comes from the Czechoslovakian "SPItzenReACTOR" which was the name first used by the Zentner Company in 1938. The Permutit design installed on the Hollywood plant is basically a modification of the original Zentner design. "Raw" well water enters the bottom of the Spiractor along a tangent on the side, thus causing a helical swirling flow which produces the fluidized bed. At the same time, a lime slurry is also added, which acts as a catalyst, helping the precipitation. The lime slurry converts the dissolved calcium bicarbonate into solid calcium carbonate that "plates" onto the sand particles. The result is hard spheres of calcite (CaCO₃) , which later can be disposed. The softened water then flows out the top of the Spiractors.

Due to high turbidity and suspended solids levels in the discharge from the Spiractors, the next stage is a mandatory filtering.