Grantee Research Project Results

2013 Progress Report: Fluoride, DBP Precursors, and Particles: Simultaneous Removal with Aluminum Salts a Solution for Small Drinking Water Systems

EPA Grant Number: R835176
Title: 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, 2012 through November 30,2013
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 also will 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: Mechanistic studies, Laboratory-scale demonstration, and Pilot-Scale demonstration. We have completed Phase I, which includes the mechanistic studies of the precipitation process, the effects of ligand adsorption (of fluoride, synthetic organics as surrogates of NOM, and actual NOM), and the stability or dissolution of the precipitant(s) in the presence of the ligands. Many of the Phase II experiments have been completed. Public records (consumer confidence reports and annual water quality reports from the past 3 years) were used to develop a database of water systems that contain high fluoride levels. The database containing source water locations and characteristics was used to select water utilities that utilize surface water and have high fluoride levels. Natural waters from three public water systems in the states of Colorado and Texas have been evaluated to date. Two of the selected water systems use surface water containing naturally high fluoride concentrations (above 3.2 mg/L). The third water system blends ground water and treated surface water to lower the fluoride concentration in its finished water. Phase III, which involves onsite testing, has not yet begun, but one water system in west Texas has been identified as a probable site because it already employs alum coagulation for treating its water.

Future Activities:

Several more natural waters are needed to establish statistical correlations between NOM content, fluoride, and their removals using alum coagulation. Our primary focus is directed at finding water systems using surface water as their water source because these water systems are likely to have significant NOM content and fluoride concentrations greater than 2 mg/L. However, it may be necessary to select waters that provide a range of NOM concentrations to which we add fluoride to ensure a sufficient range of concentrations. Correlations between fluoride removals and NOM properties such as specific ultraviolet absorbance (SUVA) are expected to improve the interpretation of current and future results, allowing for a more robust treatment model to be developed. These correlations, in conjunction with our findings from Phase I, will be used to assist in the development of a draft set of guidelines for alum treatment for fluoride removal in the next several months.

All three water systems that have contributed natural water to this project have indicated a future willingness for onsite work to be done with their water. One of the water systems, located in west Texas, already employs alum coagulation to remove particles and NOM. We anticipate beginning pilot-scale and perhaps full-scale testing at this site during the coming year and will soon contact the water system. Full-scale testing would allow us to evaluate the guidelines and understandings developed from the Phase I and Phase II results of the project while also allowing us to refine our treatment model so that optimal fluoride removal by alum coagulation can be achieved at the specific water system.

References:

Sharma JR. Development of a preliminary cost estimation method for water treatment plants. M.S. Thesis, The University of Texas—Arlington, 2010.

Journal Articles:

No journal articles submitted with this report: View all 14 publications for this project

Supplemental Keywords:

fluoride removal, alum coagulation, NOM removal

Progress and Final Reports:

Original Abstract

The 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.