Can THM monitoring and removal be improved in high-purity water applications?
Authors: John DeGenova, PhD, Philippe Rychen, Ignacy Kieler, M. Sc., Malek Salamor
In water treatment history, the problem of increased con- centrations of disinfection byproducts (DBPs) started to emerge in the early 1900s. This is when chlorine (and ozone) started to be applied as primary disinfection agents for drinking water. A reaction of the disinfectant agent with organic compounds present in water often leads to the formation of various types of DBPs. Throughout the years, with a growth in awareness around the negative impacts of DBPs on hu- man health, previously underutilized DBP removal technologies gained importance while new ones have also been developed.
Today, water disinfection through chlorination still remains the most common approach throughout the world. Consequently, DBPs are be- ing formed in many municipal water supplies. Trihalomethanes (THMs) and haloacetic acids (HAAs), make up the two main classes of DBPs. Considering the properties and concentrations of THMs in chlo- rinated water, which vary strongly throughout the seasons, their effi- cient removal requires a particular focus. THMs are deleterious to hu- man health and are also undesired contaminants in high-purity water plants. Because of their chemical nature, the removal of THMs from water is considered difficult, and if not handled properly their contribu- tion to the reactive halogen level at the point of use (POU) might be substantial. THMs impact may be also observed in measured total organic carbon (TOC) concentration.
This article discusses a method to overcome the challenge of the increasing importance of controlling THMs in UPW plants and presents innovative methods for both the removal of THMs and their continuous monitoring.