Long-Term Disinfection By-Product Reduction Using Clearitas®

Problem

In conjunction with Water Solution Unlimited, Blue Earth Labs was brought into the city of Winslow, Indiana to determine if the addition of Clearitas to the water distribution system could improve disinfection by-product (DBP) levels and eliminate stage 2 compliance issues. Used to remove scale and reduce chlorine demand, Clearitas is a proprietary formulation of oxidized chlorine that is added to drinking water distribution systems. Used in conjunction with existing disinfectants, Clearitas has been shown to effectively lower chlorine demand and improve DBP levels in many municipal settings.

Solution

Clearitas 101 dosing started on August 27, 2008, at a concentration of 20 ppm (of product). After two months, the dosing rate was cut in half (to 10 ppm of product). Additionally, in conjunction with the Clearitas dosing, Winslow lowered their total chlorine dosing from an average of 2.1 ppm to 0.9 ppm. As can be seen from the data in Figures 1 & 2 (view full case study) significant reductions in both DBPs occurred immediately after the addition of Clearitas and stayed low throughout the course of the study of Winslow’s water distribution system, which lasted through 2009. A 55% reduction in TTHMs occurred as well as an 84% reduction in HAA5 values.

Results

In this particular system, a very low dosing of Clearitas was very effective at decreasing the DBPs in problem portions of the water distribution system. In fact, this particular customer had no stage 2 compliance issues related to DBPs after the addition of Clearitas as part of his water treatment program and reported no adverse side effects throughout this study. Moreover, with supplemental Clearitas added, the customer was able to maintain sufficient chlorine residuals in the system even with the lower chlorine dosing, demonstrating Clearitas is effective for long-term DBP reduction.