Passing a coagulant dose to a chemical feed pump isn't enough. The difference between a plant that runs clean, predictable filter cycles and one that fights turbidity spikes and colloidal breakthrough almost every week usually comes down to how well the operator controls pH, alkalinity, and mixing energy around the coagulation step — and how quickly they recognize the early symptoms of a dose that has drifted off target. This guide moves beyond what coagulation is into the process-control skills a Class C operator is expected to apply on shift: reading jar test results correctly, recognizing over- and under-dosing before they become a filtration problem, and keeping coagulant feed equipment calibrated and reliable.
pH and Alkalinity: The Chemistry Behind the Dose
When a metal-salt coagulant such as alum or ferric chloride is added to water, it undergoes a chemical reaction with wa