In which water treatment processes is alkalinity determination essential for calculating chemical doses?

Alkalinity determination is crucial in the coagulation and softening processes of water treatment for a couple of key reasons.

In coagulation, understanding alkalinity helps in determining the appropriate type and dosage of coagulants needed to effectively neutralize the charges on suspended particles, allowing them to agglomerate and settle out of the water. Different coagulants react differently depending on the alkalinity of the water. For instance, if the alkalinity is too low, the added coagulant may overly lower the pH, potentially causing incomplete coagulation and increasing particle stability.

In softening, alkalinity helps in assessing how much lime or other agents are needed to precipitate calcium and magnesium hardness from the water. The relationship between alkalinity and hardness must be maintained, as it's necessary to ensure that the water doesn't become too acidic during the softening process. Accurate alkalinity measurements ensure proper chemical dosing, thus preventing issues like increased corrosion in the distribution system or re-dissolution of softened minerals.

Thus, the determination of alkalinity is integral to both the coagulation and softening processes to optimize chemical addition and ensure effective treatment.