Ordering Information:
ORDER NUMBER:  3100
DATE AVAILABLE: Spring 2008

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PRINCIPAL INVESTIGATORS:
Zaid Chowdhury, Sunil Kommineni, Marc Edwards, Jeffrey Parks, Michelle De Haan, Steve Acquafredda, and Jerry Lowry

OBJECTIVES:
The purpose of this project was to evaluate the issue of unintended consequences resulting from changes in water chemistry due to arsenic treatment.

BACKGROUND:
In 2006, USEPA lowered the maximum contaminant level (MCL) for arsenic from 50 micrograms per liter (ug/L) to 10 ug/L. It was estimated that approximately 3,000 community water systems will need to take action to lower arsenic in drinking water. In order to meet the new arsenic regulation, the water purveyors are implementing a wide array of new treatment technologies for removing arsenic from groundwater and surface water. When evaluating options to remove arsenic from a potable water source, consideration is given to factors such as life-cycle costs, operational complexity, system reliability, and acceptability to neighbors. The Awwa Research Foundation has funded several projects that identified and evaluated the decision criteria for the arsenic treatment process selection based on water-quality and site-specific factors. However, it is acknowledged that each treatment process can have impacts on the longevity of infrastructure assets, microbial re-growth, and lead leaching to water. Current knowledge about these effects is inadequate, and thus they do not receive proper consideration during selection of the optimal treatment technique.

 APPROACH:
The researchers performed the following tasks for this project:

• Conducted a literature review and identified data gaps with respect to secondary impacts of arsenic treatment
• Performed bench-scale tests to evaluate the secondary impacts of arsenic treatment on iron corrosion and release, non-uniform copper corrosion, and potential for leaching of lead
• Evaluated the chemical and biological stability of water treated for arsenic by ion exchange (IX), adsorption using activated alumina (AA), or adsorption using granular ferric hydroxide/oxide (GFH/GFO)
• Prepared water systems to evaluate the secondary impacts of arsenic treatment technologies during process selection and implementation

RESULTS/FINDINGS:
This study demonstrated that IX treatment had the most adverse water quality impacts, followed by AA and GFH/GFO treatment. Among the arsenic technologies studied, the GFH/GFO treatment has more beneficial effects than detrimental effects. The secondary impacts of coagulation/filtration treatment will be somewhere in between IX (detrimental) and GFH/GFO (beneficial) treatment impacts.

RESEARCH PARTNERS:
This study was jointly funded by the Awwa Research Foundation and the U.S. Department of Energy through the Arsenic Water Technology Partnership. The report was published by WERC (a Consortium for Environmental Education and Technology Development at New Mexico State University).