Lime Saturators

Lime slurry (calcium hydroxide) is fed into the centre of the saturator tank from an inlet pipe, which also carries treated feed water into the tank. The lime-dosed feed water mixes with recirculated flow from the saturator inside a baffle, flowing down through diffuser plates and underneath the baffle to equalise flow into the remainder of the clarifier.

The lime water then slowly rises to the top of the clarifier and flows over V-notch weirs into a collection trough, leading to storage in a limewater tank. The lime-treated water has a higher pH and alkalinity compared to the treated water feed.

This allows for its use in controlling the quality of water for other treatment processes that affect pH and alkalinity, such as coagulation. Excess lime remaining (after the treated water is saturated in the baffle) settles to the bottom of the clarifier to form a slurry, which is kept slowly moving and disposed of through a sludge line at the bottom of the hopper. The saturator also features a recirculation line at the bottom of the hopper, which returns unused lime to the feed well for re-mixing.