Perchlorate and Arsenic Treatment Alternatives Study

Magna Water Company, 

Perchlorate and Arsenic Treatment Alternatives Study

Project Highlights: 
  • Desktop and pilot study evaluation of C/F, EDR, and IX processes.
  • Treatment alternative evaluation examining blending, wellhead treatment, centralized treatment, and combinations thereof.
  • Pilot testing, cost estimate, and preliminary design for EDR and C/F process for a 4.5-mgd centralized facility.
EDR stack
In 1999, Carollo evaluated EDR for arsenic and TDS removal

Early before the Arsenic Rule was promulgated, Carollo worked with Magna Water Company to address inorganic removal at several area wells. Initial evaluation focused on total dissolved solids (TDS), arsenic, and perchlorate removal. Several treatment scenarios were evaluated, including blending split-stream treatment and complete treatment of all wells.

Final recommendations included a long-term solution, wellhead treatment, and a short-term solution blending various water supplies. Treatment by the electrodialysis reversal (EDR) process was pilot tested to validate the performance capabilities of the system for this particular water source.

In 2001, with the promulgation of the Arsenic Rule and several Best Available Technologies (BATs), Carollo conducted a follow-up investigation examining coagulation/filtration. Two high rate C/F systems were piloted and it was shown that less than 5 mg/L FeCl3 would drop raw water arsenic from 13 ppb to 5 ppb in the filtered water. Filtration rates ranged from 5 to 10 gpm/ft2.

With various performance and cost data generated from testing and modeling different treatment alternatives (e.g., centralized vs. wellhead), Carollo recommended an EDR process with centralized treatment. This would allow the following benefits:

  • Simultaneous removal of three contaminants (arsenic, perchlorate, TDS).
  • Environmentally friendly, bio-destruct process as the final perchlorate treatment step.
  • Meet future demands by utilization of available water supplies.

In 2003, Carollo evaluated C/F as an alternative treatment process for arsenic removal.