A wide range of technologies, some new and some more traditional, is being marketed and applied for arsenic treatment. Each of these technologies has specific properties impacting its suitability for any particular scale of application. While rare, the ability of a single water treatment technology to perform effectively across many treatment platforms is not unique.
Cross-platform viability of treatment technologies
In February, NSF International arranged for many experts to cover the issues and facets of point-of-use and point-of-entry (POU/POE), how they can be used for PWS compliance and other opportunities for the manufacturers and users. This article is intended to provide opinions and a broad conference overview.
Some really important research going on right now, which is critical for the point-of-use/point-of-entry (POU/POE) industry in order for POU/POE treatment to become an accepted practice for small public water system compliance. It seems as though we are closer than ever to finding acceptance in this arena.
A combination of increasing arsenic levels from the new well and the lowering of the MCL to 10 ppb has the water company concerned about meeting the new arsenic standards.
At Work on Arsenic Removal
Manganese greensand is a specially processed medium for iron, manganese, and hydrogen sulphide removal. This premium non-proprietary filter medium is processed from glauconitic greensand on which a shiny, hard finite thickness manganese oxide coating is formed and is firmly attached on every grain by a controlled process.
While high concentrations of arsenic are found mostly in the Western region of the United States, parts of the Midwest and New England show levels of arsenic
that exceed the newly approved U.S. Environmental Protection Agency (EPA) standard of 10 parts per billion (ppb). Individuals not willing to wait for their water system's compliance with the arsenic standard currently are looking for treatment systems to use in their homes. POU and even point-of-entry (POE) treatment systems are an attractive solution for these individuals. The process should begin with a basic understanding of arsenic contamination and the element's chemistry, a complete water quality analysis of the application-specific water and the knowledge of available technologies.
Editor’s Note: Part 1 of this series provided a timeline for the development of a drinking water standard for arsenic. It also summarized the political and public reactions to the U.S. EPA decision to delay and withdraw the arsenic rule.
Part 2 dealt with human exposure and advances in knowledge concerning human health effects of exposure to arsenic.
Part 3 summarized early data on the occurrence of arsenic in U.S. waters.
Arsenic Removal Methods
Only recently has a substantial amount of data become available on the concentrations of arsenic in United States drinking water supplies. Most of these data have been accumulated by the state regulatory agencies responsible for monitoring drinking waters. Since the arsenic standard has been 50 µg/L, some state agencies have recorded arsenic concentrations only in excess of that concentration. Others have been limited by the sensitivity of the analytical techniques and equipment used for the arsenic analysis. As a result, much of the available arsenic data are “below the limits of detection.
Occurrence of Arsenic in U.S. Waters
On November 26, 2001, the new arsenic standard was signed into law—lowering the acceptable level for the contaminant from 50 parts per billion (ppb) to 10 ppb. Approximately 4,100 municipal water systems serving nearly 13 million people nationwide are affected by the law and are required to meet compliance by January 2006. According to the U.S. Environmental Protection Agency (EPA), 97 percent of these systems are small systems serving fewer than 10,000 people each. The economic impact on these small systems is likely to be large. However, there currently are options available to small municipalities that may be more affordable than central treatment.
New POU Technologies May Be the Answer for Small Municipalities Facing High Costs
On-going health effects studies and research reports (2001) appear to support the argument for lowering the current EPA drinking water standard for arsenic. Studies conducted by EPA, the University of North Carolina and the University of British Columbia have indicated that methylated metabolites of trivalent arsenic are genotoxic. In other words, they damage DNA in human cells.
Human Exposure and Health Effects