The best method of selecting chemicals and determining doses is:

The jar test is a widely recognized laboratory method used in water treatment to evaluate the effectiveness of various chemicals for coagulation, flocculation, and sedimentation processes. By simulating the full-scale treatment process on a smaller scale, the jar test allows operators to assess how different chemicals perform with respect to water quality parameters.

During the jar test, small samples of water are treated with different chemicals in jars, and various doses can be tested simultaneously. This enables operators to observe the reactions, optimize dosages, and select the most effective chemical treatment for the specific water quality conditions. The results from the jar test provide valuable data that can guide decisions on chemical selection and dosing strategies before full-scale implementation.

Given these advantages, the jar test is often preferred over methods such as full-scale batch treatment or trial and error, as it provides a controlled environment and precise data to inform the decision-making process. Intense research can also yield information about chemical effectiveness, but the jar test directly correlates laboratory findings with practical application in treatment processes.