NSF/EPA Project Offers Cost-Effective Solution to Meet New Arsenic MCL
Time is up for public drinking water utilities to meet the new standard for arsenic. In reality, however, it is time for many small systems to apply for exemptions. EPA’s new arsenic rule, which was issued Jan. 22, 2001, requires public drinking water utilities to meet a new standard for arsenic of 10 ppb.
According to the U.S. Environmental Protection Agency, nearly 3,000 public water systems have yet to implement some type of solution to meet the new MCL. Many of these are small systems that can’t afford to install new centralized water treatment. While exemptions will offer a temporary solution to regulatory compliance, they may leave some communities with water that poses significant health concerns.
Among other options, POU treatment offers an alternative, cost-effective solution to these communities.
A recent joint NSF/EPA study analyzed the feasibility of an economically sustainable POU/POE decentralized public water system. The goal of the project was to identify the important issues for successfully implementing a centrally managed POU treatment system in a small community for the purpose of complying with the new MCL.
The project management group (PMG), organized by NSF International, consisted of representatives from the U.S. EPA, Association of State Drinking Water Administrators, American Water Works Association, National Rural Water Association and the Water Quality Association. The group selected Grimes, Calif., a small, predominantly bilingual, low-income, farming community, as the study site. The drinking water in Grimes has an arsenic concentration of approximately 25 ppb.
Water Quality Products provided an overview of the project in the January 2006 issue. This month’s Part II of the article will focus on the commercial installations in Grimes.
After choosing Grimes as the community for the project, the PMG selected an activated-alumina treatment system provided by Kinetico, Inc. The California Department of Health Services requested the units meet a criterion of <2 µg/L, instead of the MCL, as a precaution.
Mark Brotman, research scientist for Kinetico, said, “The best choice ended up being point-of-use filters that monitor water volume and automatically shut off at 500 gal. The units bear cartridges with an adsorptive media and another with granular activated carbon.”
Kinetico was selected as the vendor for the project due to its ability to donate time and equipment and the availability of an authorized Kinetico dealer in the area. The Sacramento-based dealer, Blue Fountain Water, scheduled and made all the installations for the townspeople.
Prior to installation, the selected system was tested both at the NSF testing laboratory and in Grimes. At NSF, the system was tested against the new arsenic reduction protocol in NSF/ANSI Standard 53, using an arsenic challenge of 50 µg/L. In Grimes, two systems were operated eight hours per day with an operation pattern of five minutes on, five minutes off. During both tests, the system was able to produce treated water with <2 µg/L of arsenic for more than 500 gal. According to Mike Blumenstein, NSF Grimes project coordinator, “The NSF [test] and accelerated field test represent a conservative demonstration of the system’s arsenic removal capability, since the units treated about 100 gallons per day, whereas in practice, most units treated less than 1 gallon per day.”
Approximately 140 systems were installed in the community. A few locations (a daycare center and elementary school) required multiple systems to accommodate water fountains and food prep needs.
Installations began in July 2002. The project staff encountered various challenges during the installations. While standard installations usually take about 15 minutes, installations in Grimes took anywhere from 15 minutes to three hours.
Grimes’ Grand Island Elementary School only required drinking fountain treatment because the school’s cafeteria serves prepackaged breakfast and lunch. Nevertheless, the school’s indoor and outdoor fountains presented a number of installation difficulties.
For example, in order to reach the plumbing of one indoor fountain, the installer had to get behind a wall to perform an unusual connection that took much longer than the typical 15-minute installation (see figures 1, 2 & 3).
Other issues were encountered with the school’s outdoor fountains. A POU device could not be installed on one of the outdoor drinking fountains, located near the school’s ball field. Although treatment could have been provided further upstream in the supply line, the community decided to turn off the water to this fountain, as there were other fountains nearby (see Figure 4).
The other outdoor fountain on the school grounds included three simultaneously operating fountains. Due to the low flow rates associated with POU devices (In Grimes, the POU device’s average flow rate was 0.4 gpm), the fountain had to be converted into a new one-fountain installation. In addition, the plumbing on this outside fountain was exposed. This was also the case in several other community installations. Despite the fact that freezing would not be an issue in Grimes, all outdoor POU units were protected and insulated (see figures 5 and 6).
Other business and commercial installations in Grimes included two restaurants, a small store, two daycare centers, a library, post office and church.
Installers faced some additional challenges at one of the restaurants. The installation took about three hours to complete because it required a special POE-sized unit to handle a commercial ice machine.
The NSF/EPA study confirmed overall unit performance of <2 µg/L of arsenic by sampling the units quarterly for one year. A few units showed arsenic levels >2 µg/L, but most of these were in high-use locations such as schools, businesses or large-family homes.
The Grimes case study also included a detailed cost analysis of the project in order to determine the advantages of POU/POE treatment as an alternative to central treatment for arsenic reduction. Costs were tracked for installation, operation and maintenance, and Kinetico provided estimates for installing central treatment equipment.
According to this data, central treatment would be $24.31 per month per household. On the other hand, using POU and POE units that are allowed to operate until the shut off devices activate, with one half of the units sampled per year, the estimated cost would be $11.46 per month per household.
After the study was completed, the units were left with the community for them to maintain. To date, Grimes residents are satisfied with the taste and quality of the water.
Overall, the cost savings achieved through non-centralized treatment may enable some systems to provide more protection to their customers than they might otherwise be able to afford. Ultimately, POU treatment devices may be an option for public water systems where central treatment or even POE treatment is not affordable.
Perialwar (Regu) Regunathan, president of Regunathan and Associates, Inc., who helped manage the project, said, “All small communities facing a chronic contaminant in their water should seriously consider POU to save a great deal of money and in the process, improve their drinking water to a much better level than otherwise.”