Demonstration of Regenerable, Large-Scale Ion Exchange System Using WBA Resin in Rialto, CA
ER-201168
Objectives of the Demonstration
The current approach to achieve compliance with federal and state drinking water regulations for perchlorate is treatment by either ion exchange or biodegradation, with ion exchange favored for drinking water applications. An alternative regenerable ion exchange process that uses weak base anion (WBA) resin was developed and patented by Applied Research Associates, Inc. and the Purolite Company under ESTCP project ER-200312, which demonstrated on a pilot scale the treatment of groundwater at Redstone Arsenal, Alabama. The objective of this project is to demonstrate at the pilot scale and full scale (~1,000 gpm) the use of the WBA resin, ion exchange system for treatment of drinking water. The pilot scale system was demonstrated at Fontana, California and was completed in 2008 (see documents below). The full scale system is being demonstrated at the Rialto, California, wellhead #3 in the Inland Empire. A data package will be prepared for inclusion in the Drinking Water Supply Permit Application. After the WBA resin process is permitted in the state of California, this technology can then be deployed at other contaminated sites.
Technology Description
The ion exchange process takes advantage of the pH dependent nature of WBA resins. At low pH, functional groups on these resins are ionized (R-NH3+) and capable of performing anion exchange. However, at high pH, the resin functional groups lose a proton and are uncharged (R-NH2) – no longer attracting the counter anion and enabling efficient and complete regeneration. The pH dependent nature of WBA resins enables efficient regeneration, minimizing the amount of regeneration chemicals and resulting in an economical process. The WBA ion exchange process has two primary modes: operation and regeneration. During operation, perchlorate is removed from the contaminated water. Once the resin has reached its exchange capacity for perchlorate treatment and is considered "spent," the resin must be regenerated before it can be returned to the operational mode.
Demonstration Results
Pilot Scale System
Six test periods were conducted during this demonstration. The minimum treatment rate was 24 bed volumes (BV) per hour or 3 gpm/ft3 (a surface loading rate of 9.7 gpm/ft2). Four test periods were breakthrough tests (1, 2, 5, and 6). During regeneration of the spent column, the lag column remained online and treated water in a single column. The remaining two test periods (3 and 4) were short-cycle tests. In short-cycle tests, columns were regenerated after approximately one week on-line and before breakthrough. These short-cycle tests were conducted to maximize the number of regenerations per column and minimize the duration of the demonstration. The short-cycle tests were also used to evaluate perchlorate removal efficiency at a higher specific flow rate of 4 gpm/ft3 (a surface loading rate of 12.9 gpm/ft2). Regeneration of spent resin and treatment of the spent regenerating solution using the zero-discharge scavenger process were conducted on-site.
The treatment capacity determined from this demonstration was 9,700 bed volumes. The treated water was below the method report limit for perchlorate (<0.10 ppb) using IC/MS/MS. Nitrosamines were analyzed using EPA Method 521. NDMA was 2.6 ppt with a detection limit of 2 ppt. All other nitrosamines analyzed (including NDEA, NDBA, NDPA, NMEA, NMOR, NPIP, and NPYR) were below the detection limit. A “dial in” capability for controlling residual alkalinity of the treated water in the post treatment process was demonstrated by varying the pH and using a combination of air/membrane stripping and calcite contacting. Treated water had a Langelier Saturation Index (LSI) near zero, which indicated that it had neither corrosive nor scaling tendencies. Five resin regenerations were accomplished using 3 bed volumes of regenerant solution, or approximately 0.03% of the treated water. The spent regenerating solution was successfully treated using the zero-discharge scavenger resin approach to remove perchlorate to below method reports limits.
Implementation Issues
As perchlorate concentration in groundwater increases, regenerable resins offer significant cost savings and longer service life over single-use resins. The regeneration approach using WBA resin is up to 50 times more efficient than regeneration of strong base anion resins, which typically require a large excess of salt brine. In addition, for many applications, the treated spent regenerating solutions generated contain no perchlorate. (Full-Scale Anticipated Project Completion – 2012; Pilot-Scale Completed – 2008)
Project Documents
Points of Contact
Principal Investigator
Mr. Jeffrey Rine
Applied Research Associates, Inc.
Phone: 850-914-3188 x205
Fax: 850-914-3189
Project Documents
Document Types
- Fact Sheet - Brief project summary with links to related documents and points of contact.
- Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
- Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
- Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
- Guidance - Instructional information on technical topics such as protocols and user’s guides.
- Workshop Report - Summary of workshop discussion and findings.
- Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
- Model/Software - Computer programs and applications available for download.
- Database - Digitally organized collection of data available to search and access.