Alkalinity Addition: Theory and Best Practice

Alkalinity is an often overlooked water quality parameter in water treatment. An imbalance in the alkalinity of the water can cause problems during the treatment process and in the reticulation. Increasing alkalinity is usually achieved through the addition of alkalis such as lime and soda ash. However, these methods can cause a rapid increase in pH with no significant increase in alkalinity. Using carbon dioxide in combination with limestone allows for greater flexibility in controlling alkalinity, pH, and hardness. This article briefly discusses the theory of carbonate chemistry and how to improve water stability using the remineralisation process. It will also discuss the challenges of designing this system for the Wheatstone LNG plant to be constructed by Xylem Water Solutions (Australia).