Dr. Eddy Dean Smith, Ph.D., P.E., DEE, Senior Researcher
Edgar.d.smith@erdc.usace.army.mil
Fax: 217-373-3430
Telephone: 217-373-3488
Dr. Veera M. Boddu, Ph.D., P.E., Researcher
veera.boddu@erdc.usace.army.mil
Fax: 217-373-3430
Telephone: 217-373-5511
Ms. Joyce C. Baird, MS, Researcher
Joyce.C.Baird@erdc.usace.army.mil
Fax: 217-373-3430
Telephone: 217-373-4469
United States Army Engineer Research and Development Center
Construction Engineering Research Laboratory
Abstract: Arsenic is a common groundwater contaminant. Chromium (Cr) is widely used for critical metal plating, corrosion control and surface finishing requirements. Industrial chrome plating facilities generate chrome contaminated waste streams from its plating operations. The hexavalent Cr (VI) anion is toxic and must be removed from wastewaters prior to discharge. The U.S. Army Engineer Research and Development Center, Construction Engineering Research Laboratory (ERDC-CERL) has recently disclosed a composite adsorption material based on chitosan-coated alumina and perlite with enhanced adsorption capacity for Cr (VI) salts found in effluents. As part of an overall investigation on the economic feasibility of applying the new adsorbent for toxic metals removal from aqueous streams, a semi-pilot scale study was conducted at one plating facility. The plating rinsewater has a Cr (VI) concentration in the inlet in the range of 20 to 150 ppm (mg/L). The very first cycle showed that all of the chromium present in the stream could be removed even after 210 minutes of continuous operation. Samples were collected at 30-minute intervals both from the inlet and the outlet streams. After the adsorption cycle the bed was regenerated using 0.1N NaOH solution for 1 hour. Following regeneration with NaOH, the bed was again rinsed thoroughly with water for 1 hour to remove residual NaOH from the bed. The adsorbent was regenerated and used for up to 10 cycles. The adsorbent did not show any sign of deterioration in strength or adsorption capacity during these 10 cycles. The operating cost for the removal of chromium ranged from $0.15 to $0.41 per gallon depending on the life cycle of the adsorbent. Data will also be presented regarding the treatments of arsenic contaminated groundwater.
Keywords: water treatment, groundwater, arsenic, heavy metals, water contaminants