Water Resources Research Act Program

Details for Project ID 2011ND238B

Arsenic Contaminated Groundwater Remediation by Entrapped Nanoscale Zero-Valent Iron

Institute: North Dakota
Year Established: 2011 Start Date: 2011-03-01 End Date: 2012-02-29
Total Federal Funds: $6,000 Total Non-Federal Funds: $12,001

Principal Investigators: Achintya Bezbaruah

Project Summary: In response to the significant threat arsenic presents, the United States Environmental Protection Agency (USEPA) drastically modified the maximum contaminant level (MCL) for arsenic in drinking water from 50 g/L to 10 g/L in 2006. Even at 10 g/L the world health organization (WHO) estimates a 0.2% chance of developing cancer in humans. Millions are presently at risk due to high arsenic levels in drinking water. Acute and chronic arsenic exposure from drinking water has been reported in many countries, most of which have large proportions of drinking water contaminated with high concentrations of arsenic (total As ≥ 50 g/L). The United States Geological Survey (USGS) analysis of 30,000 random groundwater samples across the United States found that approximately 10% of sites had arsenic concentrations in excess of 10 g/L. Moreover, arsenic is second only to lead (Pb) as the most commonly found hazardous contaminant at Superfund Sites. In Southeastern North Dakota more than 25% of groundwater samples contain arsenic at levels in excess of 10 g/L. The U.S. EPA conducted a five year review (2004-2008) to analyze the remedial action implemented in Southeastern North Dakota. Approximately 375 wells in the 26 townships (about 568 square miles) were sampled and it was found that more than 84% samples have the arsenic concentration above the MCL. This presents an unacceptable risk of cancer and adverse health effects to the residents who depend upon water from the aquifer. By entrapping NZVI within a biopolymer (Ca-alginate) the overall contact time with contaminants will be prolonged, allowing individual particles to react more efficiently. By optimizing critical parameters such as NZVI dosage and pH, the waters can be effectively remediated below the USEPA arsenic MCL (10 g/L). The objective of this research is to determine the treatability of arsenic by entrapped NZVI. The specific objectives of the study are: 1) Conduct entrapped NZVI treatability batch studies with various As5+ and As3+ concentrations. 2) Examine the effects of individual ions (which are present in groundwater) on the arsenic removal (by entrapped NZVI) reaction kinetics. 3) Characterize entrapped NZVI within Ca-alginate beads using X-ray diffraction (XRD) and scanning electron microscopy (SEM) to understand the arsenic treatment mechanisms. 4) Perform entrapped NZVI treatability batch studies with actual arsenic contaminated groundwater.