Batch and Continuous Removal of Arsenic Using Hyacinth Roots

Abstract

Arsenic is considered a primary pollutant in drinking water because of its high toxicity. The unique property of water hyacinth roots (Eichhornia crassipes) to remove heavy metals is of great significance for the development of a cost-effective phytoremediation technology. An experimental test program was conducted at the United States Environmental Protection (USEPA) Test and Evaluation (T&E) Facility in Cincinnati, Ohio, to investigate the potential of water hyacinth roots to remove arsenic from spiked drinking water samples. Water hyacinth roots were washed, dried, and powdered to provide dried hyacinth roots (DHR) for batch and continuous column experiments. Various quantities of DHR were added to water spiked with 300 micrograms per liter (μg/L) arsenic. A concentration of 20 g/L DHR was found adequate for greater than 90% arsenic removal in the batch tests. Based on the batch test results, continuous column experiments were performed using a 2-L column. In a continuous system, 15 L of water containing 300 μg/L arsenic were treated to below 20 μg/L using 50 g DHR, and 44 L of water containing 600 μg/L arsenic were treated to below 20 μg/L using 100 g DHR, giving a specific accumulation rate of approximately 260 μg As/g DHR.

KEYWORDS:

• phytoremediation
• dried hyacinth roots
• arsenic
• Eichhornia crassipes
• water
• metal

ACKNOWLEDGMENTS

The authors wish to thank Larry Wetzel of USEPA for help with column fabrication, plumbing, and spectrophotometric analyses. The authors also wish to thank Dr. Maqsud Rahman, Chemist, Shaw Environmental, Inc. for his inputs on preparation of stock solutions and valuable tips on arsenic chemistry.