A laboratory procedure that simulates a water treatment plant's coagulation/flocculation units with differing chemical doses and also energy of rapid mix, energy of slow mix, and settling time.
The purpose of this procedure is to estimate the minimum or ideal coagulant dose required to achieve certain water quality goals.
Samples of water to be treated are commonly placed in six jars.
Various amounts of chemicals are added to each jar, stirred, and the settling of solids is observed. The dose of chemicals that provides satisfactory settling removal of turbidity and/or color is the dose used to treat the water being taken into the plant at that time.
When evaluating the results of a jar test, the operator should also consider the floc quality in the flocculation area and the floc loading on the filter.