Grantee Research Project Results
2015 Progress Report: Fluoride, DBP Precursors, and Particles: Simultaneous Removal with Aluminum Salts a Solution for Small Drinking Water Systems
EPA Grant Number: R835176Title: Fluoride, DBP Precursors, and Particles: Simultaneous Removal with Aluminum Salts a Solution for Small Drinking Water Systems
Investigators: Lawler, Desmond , Katz, Lynn
Institution: The University of Texas at Austin
EPA Project Officer: Page, Angela
Project Period: December 1, 2011 through November 30, 2014 (Extended to June 19, 2016)
Project Period Covered by this Report: December 1, 2014 through November 30,2015
Project Amount: $499,357
RFA: Research and Demonstration of Innovative Drinking Water Treatment Technologies in Small Systems (2011) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
Objective:
The goals of this project are to (1) develop a treatment system for the simultaneous removal of fluoride, natural organic matter (NOM), and particles from natural waters that are used as drinking water sources, and (2) demonstrate the efficacy of the system through small-scale pilot testing of a continuous flow system using a real drinking water source. Because NOM is the precursor of many disinfection by-products (DBPs), this treatment system will also reduce DBP formation. The system will be specifically designed for small water systems (SWS) with limited capital and personnel resources available. The treatment system will exploit the favorable interactions of all three contaminants with aluminum (oxy)hydroxides.
Progress Summary:
We proposed a three-phase study that was subsequently extended to 4 years: Mechanistic studies, Laboratory-scale demonstration, and Pilot-Scale demonstration. Research during this year focused the second pilot-scale demonstration for Phase III and an analysis of the particle size distributions formed under various ligand circumstances relevant to this project.
The second pilot-scale study was performed at the water treatment facility in Manitou Springs, CO. Manitou Springs' influent water had an average fluoride concentration of 2.7 mg/L. Fluoride reduction ranged from 14% to 80%. Steady-state fluoride concentrations below 1.5 mg/L were achieved with alum doses 100 mg/L and above. Fluoride residuals below 2.0 mg/L, the fluoride secondary maximum contaminant level (SMCL), were achieved with alum doses of 50 mg/L and above. The results were quite similar to those found from jar tests on this water and also were similar to those found in the first pilot study. At the effluent of the flocculation unit, doses of 100 mg/L of alum and above were able to achieve a fluoride concentration that was below the SMCL of 2.0 mg/L
The effect of ligand substitution on the particle size distributions of aluminum precipitates was investigated through jar tests in synthetic water. Results indicated that a noticeable effect on the particle distributions is seen when fluoride and NOM are present. In the presence of fluoride alone, the particle diameter associated with the peak of the volume distribution is shifted toward smaller particles relative to that when alum alone is precipitated, indicating that particle formation and aggregation is inhibited by the presence of fluoride. When NOM is present in the system, however, a noticeable increase in the total volume of particles occurs. This increased volume indicates the formation of aluminum organic precipitates that contribute to the total volume of suspended particles. When both fluoride and NOM are present in the system, a combination of the two effects occurs: a shift in the volume distribution toward smaller particles and an increase in the total volume of particles. This observation indicates that while fluoride is inhibiting the formation or aggregation of particles resulting in a larger number of smaller particles, the NOM also is complexing with the aluminum to create aluminum organic precipitates, resulting in a larger volume concentration of particles.
Journal Articles:
No journal articles submitted with this report: View all 14 publications for this projectSupplemental Keywords:
fluoride removal, alum coagulation, NOM removalProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.