Rialto, California

Drinking Water Treatment: Ion Exchange 1000-gpm Prototype

Problem Statement

Multiple drinking water wells in the Rialto-Colton Basin are adversely impacted by perchlorate
contamination.  If perchlorate concentration in a well exceeds or is projected to exceed the maximum contaminant level (MCL) established by the California Department of Public Health (6 ppb), the well must
be shut down or perchlorate treatment must be implemented.  Treatment using single-use, ion exchange resins are costly, especially as perchlorate concentration in the groundwater increases, which results in more frequent replacement of the single-use resin.   A perchlorate-selective, regenerable ion exchange process that minimizes or eliminates spent regenerating solutions will significantly reduce treatment cost.

Objectives:

Demonstrate ARA’s large-scale (1000 gpm) ion exchange process for perchlorate treatment using weak base anion resin.  Specific guidelines include:
  • Demonstrate at a wellsite in Rialto, CA
  • Demonstrate at a wellsite with high perchlorate concentration (preferably >50 ppb)
  • Meet guidance specified by CDPH Policy Memorandum 97-005  for “Extremely Impaired” source water
  • Evaluate and validate performance and operating and maintenance cost of the demonstration system

Results and Benefits

Construction of the 1000 gpm WBA demonstration system, managed by Carollo Engineers, is underway at wellsite Rialto No. 3.   ARA designed the demonstration system to reduce the perchlorate concentration in the treated groundwater to less than 1 ppb and produce a neutral (i.e. non-scaling and non-corrosive) drinking water that meets all regulatory limits.  Less than 0.05% of perchlorate-free spent regenerating will be produced.  Demonstration of the 1000 gpm WBA treatment system is anticipated to start by July 2011.

Project sponsored by the Environmental Security Technology Certification Program (ESTCP)