The effects of alkalinity, hardness, and pH on the formation potential of disinfection by-products

Abstract

Chlorine is the most common disinfectant used; its use has dramatically decreased a number of waterborne diseases. However, the use of disinfectants creates another potential problem in the creation of disinfection by-products (DBPs). The United States Environmental Protection Agency has determined DBPs may be a carcinogen and may pose a risk to human risk. Research was conducted on whether alkalinity and hardness contribute to DBP formation. The waters were tested under low and high hardness, low and high alkalinity, and a global mean value. Not until pH 10 was there a significant decrease in DBPs formed for the high hardness compared to low hardness concentrations. The high alkalinity concentrations suppressed the DBP formation potential. Under the global mean value the formation potential was approximately the addition of the individual tests. These tests may aid in potential strategy in limiting DBP formation, by keeping the alkalinity value high there would be a suppression of DBP formation. Additionally, if the treatment plant was treating water a pH of 10.0, then a high hardness concentration may aid in DBP formation reduction as well.