Town of Springs, NM – Disinfectant By-Product Study
Phelps Engineering Services, Inc. is helping to bring the Town into compliance with DBP standards. Phelps Engineering Services, Inc. prepared a study focusing on four different areas of treatment.
1. Chlorine Contact Analysis
Disinfectants, such as chlorine, are added to drinking water to kill disease-causing microbes. It may be possible to precisely balance the chlorine dosing in order to provide the required inactivation of microbes and required residual level (to kill microbes in the distribution system) without leaving an excess to form DBPs. Phelps Engineering Services, Inc. analysis found that the Town is limited in its ability to make adjustments to the chlorination practices at the WTP that would have any measurable effect on the finished water DBP levels.
2. Enhanced Coagulation Analysis
Coagulants are chemicals added to water that gather particulate matter together, causing them to settle or be filtered out, clarifying the water and removing organic matter. This study included extensive analysis to evaluate whether changes in the coagulants, doses, and/or coagulant aids can bring finished water DBP levels into compliance. Phelps Engineering Services, Inc. coordinated testing with a University lab.
Preliminary results, based on reductions in turbidity, DOC and UV254 absorbance, all indicators of disinfectant byproduct formation potential, were promising.
However, further testing of the actual formation of DBPs demonstrated that while enhanced coagulation could significantly reduce DBPs, the resulting DBP concentrations were still above the Maximum Contaminant Levels (MCLs). Phelps Engineering Services, Inc. analysis concluded that changes in coagulation alone are insufficient to achieve compliance with DBP standards.
3. Alternative Disinfectant Analysis
A qualitative analysis was performed to consider alternative disinfectants, including chloramines, ozone, chlorine dioxide, and UV. These disinfectants are not known to create DBPs. Industry practice suggests the UV may be effective in reducing DBPs. However, the water chemistry in Springer, as shown in lab results, is not conducive to this treatment.
4. Alternative Treatment Processes
A qualitative analysis was performed to consider alternative treatment processes. The alternatives considered were Granular Activated Carbon, Powdered Activated Carbon, Ion Exchange, Ozone Preoxidation, and Membranes. The analysis concluded that Ozone Preoxidation was the most promising alternate treatment process. Conceptual cost estimates were developed for this option.
The study concluded that Ozone Preoxidation was the most promising technology. Phelps Engineering Services, Inc. is currently working with the Town to test the effectiveness of this technology in the lab, and to deter-mine the optimum ozone dose. In the future, Phelps Engineering Services, Inc. can also provide preliminary design, bidding assistance and construction oversight to this project.