Nitrate Removal For Small Public Water Systems PDF Download

Nitrate contamination of potable water sources has become one of the most important water quality concerns across the United States. Nitrate presents unique water treatment challenges and small water systems are particularly affected by the high costs of addressing nitrate impacted supplies. The incidence of nitrate impacted drinking water systems, with respect to contamination, violations, and treatment, was assessed nationally, with particular emphasis on the state of California. Findings indicate that public water systems serving less than 3,300 people (very small and small water systems) are disproportionately affected by nitrate in potable water supplies, accounting for an average of 97.5% of systems in violation of the nitrate maximum contaminant level from 1998 - 2013. Of the 744,304 people served by national community water systems (CWS) that were non-compliant at least once from 2010 - 2013, 37.4% were served by systems in California. There were more systems in California in violation of the nitrate MCL between 2010 and 2013 than in any other state. Treatment measures have been proven effective and are in use at public water systems across the United States; anion exchange is the most common treatment technology implemented in the United States for nitrate removal. The disposal of waste residuals from drinking water treatment processes like anion exchange can be costly, particularly for small inland communities lacking the resources needed to identify the most affordable and sustainable waste management approach. Brine waste management options for small nitrate treatment systems in the Central Valley of California were examined with consideration of the feasibility, sustainability, and affordability of the available alternatives. Onsite evaporation, landfill evaporation, landfill solidification, and coastal wastewater treatment plant disposal were considered in detail with a base case scenario. Onsite evaporation ponds and transport of waste to a coastal wastewater treatment facility were identified as the least-costly, currently-available management options. In nearly all cases, the estimated minimum disposal costs associated with the base case scenario exceeded the average cost of tap water in the United States, $2.00/1,000 gallons. The minimization of brine waste through improved water recovery has the potential to significantly decrease disposal costs, by as much as 95%. Given the high costs of brine disposal options for individual small water systems in the San Joaquin Valley, the development of sustainable and affordable regional solutions is warranted to address the problem in a manner that can benefit multiple small water systems, as well as other brine producers in the region.