REMOVAL OF ARSENIC AND CHROMIUM FROM WATER USING FE-EXCHANGED ZEOLITE

Arsenic and chromium are two of the most harmful environmental contaminants. In this research, a natural clinoptilolite zeolite was exchanged with iron (III) to enhance its arsenic and chromium removal. Batch test results showed that the zeolite could sorb as much as 100 mmol/kg of Fe(III). The arsenic (As) sorption on the Fe-exchanged zeolite (Fe-eZ) could reach up to 100 mg/kg while that of chromate could be as high as 200 mg/kg of Cr, or 3.5 mmol/kg. Columns packed with Fe-eZ were tested for As removal from water collected from acid mine drainage (AMD) and groundwater containing high natural organic matter and high As(III). With an initial As concentration of 147 µg/L in the AMD water, a complete As removal was achieved up to 40 pore volumes. However, the Fe-eZ was not effective to remove As from Chia-Nan Plain groundwater due to its high initial As concentration (511 µg/L) and high natural organic matter, as well as its low oxidation-reduction potential, under which the As was in reduced As(III) form.