Perchlorate Removal, Destruction and Field Monitoring Demonstration

Site Name:

Redstone Arsenal

Location:

Huntsville, Alabama

Period of
Operation:

June 2005 to October 2005 (15 weeks)

Cleanup
Type:

Pilot Scale

Technology:
Ion exchange using perchlorate-selective weak base anion (WBA) resin

  • The ion exchange process used WBA resins consists of three unit operations: pretreatment, ion exchange, and posttreatment. The system was installed in an 8 by 20-ft enclosed trailer.
  • Pretreatment consisted of reducing the pH of the contaminated water to below the ionization constant (pKa) of the resin.
  • Ion exchange consisted of two conventional ion exchange columns in series. The pretreated water passed through these columns in a lead-lag configuration.
  • Posttreatment is used to restore pH and alkalinity of effluent before discharge.
  • The regeneration of WBA resin is accomplished by increasing the pH to neutralize the functional groups. This was accomplished by increasing the pH of two to three bed volumes of water and passing the solution over the resin. The target pH of the regeneration solutions was 12.
  • The residuals were treated using the following two processes for destroying/removing perchlorate from the regenerating solutions.
    • Biodegradation using two continuously stirred tank reactors (CSTR) in series.
    • A strong base anion resin to scavenge the concentrated spent regenerant solution as a super-loading approach.

Cleanup Authority:
Environmental Security Technology Certification Program (ESTCP)

Contacts:

Andrea Lesson
Technical Program Manager
ESTCP
901 N. Stuart Street,
Suite 303
Arlington, VA 22203
Telephone: 703-696-2118
Fax: 703-696-2114
andrea.leeson@osd.mil

Bryan Harre
U.S. Navy
1100 23rd Avenue
Port Hueneme, CA 93043
Telephone: 805-982-1795
Fax: 805-982-4304
bryan.harre@navy.mil

Edward Coppola
ARA
430 W. 5th St, Ste 700
Panama City, FL 32401
Telephone: 850-914-3188
Fax: 850-914-3189
ecoppola@ara.com

Andrea Davis
ARA
430 W. 5th St, Ste 700
Panama City, FL 32401
Telephone: 850-914-3188
Fax: 850-914-3189
adavis@ara.com

Steve Baxley
ARA
430 W. 5th St, Ste 700
Panama City, FL 32401
Telephone: 850-914-3188
Fax: 850-914-3189
sbaxley@ara.com

Robert Girvin
ARA
430 W. 5th St, Ste 700
Panama City, FL 32401
Telephone: 850-914-3188
Fax: 850-914-3189
rgirvin@ara.com

Phil Thorne
ARA
415 Waterman Road
South Royalton, VT 05068
Telephone: 802-763-8348
Fax: 802-763-8283
pthorne@ara.com

Terry de la Paz
U.S. Army Corps of
Engineers,
Redstone Arsenal, AL 36602
terry.delapaz@us.army.mil

Wes Smith
U.S. Army Corps of
Engineers,
Redstone Arsenal, AL 36602
Telephone: 256-876-9479
Fax: 256-876-0887
carl.smith@redstone.army.mil

Larry Galloway
RSA Support Contractor
500 Wynn Drive, Suite 314
Huntsville, AL 35816-3429
Telephone: 256-842-2850
Fax: 256-722-7212
lgalloway@amtec-corp.com

Contaminants:
Perchlorate

Waste Source:
Ordnance production

Type/Quantity of Media Treated:
Groundwater (Treatment rates of 1.5, 2.25, and 3.0 gallons per minute {gpm}/cubic feet {ft3}of resin were evaluated)

Purpose/Significance of Application:
The purpose of this project was to evaluate and demonstrate a perchlorate ion exchange treatment process for groundwater. Data collection focused on the performance and economics of the proposed treatment system compared to current perchlorate treatment methods.

Regulatory Requirements/Cleanup Goals:
The maximum concentration limit (MCL) for perchlorate is 5 parts per billion (ppb). The primary performance criteria for this demonstration include:

  1. Reduce concentration of perchlorate in groundwater from >50 ppb to ≤ 5 ppb.
  2. Reduce concentration of perchlorate in the regenerant stream to ≤ 5 ppb enabling discharge or reuse of the regenerant stream.
  3. Demonstrate an efficient regeneration technique of the perchlorate-selective ion exchange resin. Generate ≤ 0.1% spent regenerant volume of total volume treated.
  4. Demonstrate the performance of a perchlorate field monitor capable of real-time perchlorate analysis with a minimum detection limit of 1 ppb.

Results:
Data from the demonstration site indicated the following:

  1. Perchlorate concentration in the column effluent was below the criteria (5 ppb) in the lead columns until breakthrough. In the lag columns, effluent perchlorate concentration was below 4 ppb.
  2. The volume of spent regenerant never exceeded 0.06% of the volume treated.
  3. Biodegradation of spent regenerant solution was conducted for over 33 days. The perchlorate in the regenerant stream was reduced to below the detection limit for all but 3 days of this period. The excursion was due to insufficient nutrient addition (desugared molasses). After adjusting the nutrient level, perchlorate was again reduced to below the detection limit.
  4. The scavenging process removed the perchlorate from the spent regenerant solution to below the detection limit.
  5. The minimum detection limit of the field monitor could not be determined due to software and mechanical failures

Cost Factors:
The cost of the water treatment was $90 to $95 per acre-ft (AF).

Description:
A field demonstration using the ion exchange system was set-up at Redstone Arsenal in Huntsville, Alabama to treat groundwater contaminated with perchlorate. The purpose of this project was to evaluate and demonstrate a perchlorate ion exchange process for groundwater treatment. The ion exchange process used WBA resins and consisted of three unit operations: pretreatment, ion exchange, and posttreatment. Ion exchange consisted of two conventional ion exchange columns in series. The pretreated water passed through these columns in a lead-lag configuration. The pretreatment and posttreatment were used to control the pH and alkalinity of the groundwater. The ion exchange system was installed in an 8 by 20-ft enclosed trailer which was configured to provide power, climate control, and protection from the elements while in the field. The pilot system was operated in a continuous flow manner and was designed with a data acquisition unit that was remotely accessed via the Internet. Through this system, key operating parameters such as pH and flow rate were monitored. The first test period of the demonstration was initiated on June 23, 2005 and ended on October 3, 2005.

During the demonstration, samples were collected from the pretreatment and posttreatment units and lead and lag column effluents at least three times per week. Data collection focused on the performance and economics of the proposed treatment system compared to current perchlorate treatment methods. The results indicated that perchlorate concentration in the column effluent was successfully reduced to below the MCL criteria of 5 ppb. Biodegradation of spent regenerant solution was conducted for over 33 days. The perchlorate in the regenerant stream was reduced to below the detection limit for all but 3 days of this period. The excursion was due to insufficient nutrient addition (desugared molasses). After adjusting the nutrient level, perchlorate was again reduced to below the detection limit. The scavenging process also removed the perchlorate from the spent regenerant solution to below the detection limit.