Lime is the cheapest and most commonly used alkali applied in water and waste water treatment for neutralisation. Lime is available in the form of quick lime or hydrated lime. If quick lime is used it must be slaked on site into a slurry.

Lime slakers are available as  rotary slakers or open batch tanks which mix lime and water to make slaked lime by either of the following methods:

1. Automatic feeding of lime and water into a rotary slaker to obtain continuous production of slaked lime.
    

2. After weighing the  lime and dumping it into a tank water is added and then agitators start to dissolve the lime. Tests with hydrometers help to obtain desired concentrations. The mixture can finally be transferred into storage tanks. Additionally the slakers can crush or grind limestone in crushing machines or ball mills and collect samples of lime for further test, e.g. titration.