Nitrate contamination of potable water sources is a critical water quality concern for many small water systems. The federal maximum contaminant level (MCL) for nitrate, set by the United States Environmental Protection Agency (U.S. EPA), is 10 mg/L as nitrogen (N); the California MCL, set by the State Water Resources Control Board (SWRCB) Division of Drinking Water (DDW) is consistent with the federal MCL. The major health concern of nitrate exposure through drinking water is the risk of methemoglobinemia, or “blue baby syndrome,” especially in infants and pregnant women. Due to the nature of the infant digestive system, nitrate is reduced to nitrite which can render hemoglobin unable to carry oxygen (SWRCB 2010).
Strong base anion exchange (SBA-IX) treatment is the most common form of active nitrate treatment in California. SBA-IX is also used as a treatment method for other contaminants including perchlorate, arsenic, uranium, and hexavalent chromium. The process uses a strong base anion exchange resin to remove nitrate from the treatment stream. The resin is regenerated using a concentrated salt solution to remove nitrate from the resin. Regeneration of SBA-IX resin produces a concentrated waste brine solution that requires disposal. The most significant drawback of this nitrate treatment option, especially for inland communities, is the cost for disposal of waste brine, which represents a significant lifetime financial burden. Operations & maintenance costs can be a barrier to implementation of SBA-IX as a solution for nitrate-impacted small stand-alone water systems. Recent research focusing on brine waste management for small water systems in the SJV highlighted the need for regional solutions to address the Valley’s nitrate problem, particularly with respect to brine disposal (Jensen & Darby 2016). Consolidated management of nitrate treatment for multiple small water systems is one such solution. Although there are many potential challenges associated with the implementation, management, and successful operation of such options, regional solutions are necessary to sustainably address the chronic non-compliance of small water systems in the San Joaquin Valley.
This Proposition 50 project aims to provide proof of concept in the implementation of consolidated management of SBA-IX for nitrate removal for a cluster of small water systems in the San Joaquin Valley. Focusing on nitrate removal with SBA-IX for small water systems in the SJV, the objectives of the project are to:
- Identify key considerations for the implementation of a consolidated management approach;
- Demonstrate application of consolidated management;
- Perform an affordability assessment comparing the costs of stand-alone treatment with those of clustered treatment with consolidated management; and
- Evaluate statewide application of consolidated management of small water systems for sustainable potable water treatment.
Demonstration locations have been selected from nitrate-impacted candidate sites; participating water systems include Rio Bravo Greeley School Water System, Lindsay Strathmore Irrigation District (LSID) – Tonyville, and Woodville Public Utility District.