Grantee Research Project Results

Final Report: Removal of Arsenic from Drinking Water (SEER 1)

EPA Grant Number: R827683E02
Title: Removal of Arsenic from Drinking Water (SEER 1)
Investigators: Moller, Gregory , Crawford, Donald L. , Crawford, Ronald L.
Institution: University of Idaho
EPA Project Officer: Chung, Serena
Project Period: August 15, 1999 through August 14, 2002
Project Amount: $261,443
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (1998) RFA Text |  Recipients Lists
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)

Objective:

The objective of this research project was to compare new alternatives to older methods of arsenic removal from drinking water. One of most serious problems related to chemical contamination of drinking water is the occurrence of arsenic. Present drinking water standards are difficult and exceedingly expensive to meet using currently available technologies. The problem particularly is acute for small communities that have arsenic-affected water supplies.

Summary/Accomplishments (Outputs/Outcomes):

Project researchers investigated a large variety of media that might be used in column filtration reactors to adsorb arsenic species from water. In addition, several types of interfering constituents (e.g., sulphate and phosphate) were used in combination with both arsenate and arsenite to mimic real-world scenarios. Additions were made at likely drinking water concentrations. Adsorbent materials examined included alumina, manganese green sand, granular ferric hydroxide, and several proprietary commercial materials. To date, 66 experimental combinations have been compared and results are being summarized for publication. Project investigators also designed and tested reactors to remove arsenic species through co-precipitation reactions with iron in combination with sand filtration. Iron reagents were added to the influent of a specially designed reactor to be used in the high surface area of the sand bed as a non-diffusion, non-equilibrium limited reaction surface. In a pilot-scale test, well water in northern Idaho containing 50 µg/L naturally occurring arsenic was combined with iron reagents, then fed at 10-30 gallons per minute into the reactor. After co-precipitation of the arsenic with oxyhydroxide particles, approximately 90 percent of the flow left the reactor as clean effluent. The remainder was directed into a clarification basin for settling. Varying numerous process parameters allowed optimization for high arsenic removal efficiencies.

Conclusions:

Several of the filtration media examined show promise as affordable arsenic removal agents; however, the iron co-precipitation process tested performed exceptionally at the pilot scale at a real-world site. Iron co-precipitation was demonstrated to be a viable arsenic removal technology for a small public drinking water supply system. It appears that this technology should be particularly useful for small communities having limited financial resources. This arsenic removal technology presently is proceeding toward commercialization for implementation in the Western United States at the small community level.

Supplemental Keywords:

drinking water, arsenic, environmental science, Idaho, ID, EPA Region 10., RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Geographic Area, Water, POLLUTANTS/TOXICS, Chemical Engineering, State, Environmental Chemistry, Analytical Chemistry, Arsenic, Drinking Water, Environmental Monitoring, Water Pollutants, drinking water treatment facilities, Idaho (ID), iron reagents, drinking water system, drinking water contaminants, drinking water treatment, co-precipitation, sand filtration, arsenic removal

Relevant Websites:

http://www.agls.uidaho.edu/envirosci/ Exit

Progress and Final Reports:

Original Abstract

2000

2001