Consumers unwilling to drink arsenic contaminated water are demanding a more rapid implementation. Publicly owned utilities, however, will be held hostage from implementing a more rapid solution due to government approval cycles, annual budgets, required biding processes and slow implementation schedules. As a result, in-home treatment systems, which immediately can be installed, are a very popular treatment option for individual homeowners. Other advantages such as low implementation/operating costs and improved flexibility make the POU/POE approach option appealing.
Current Solutions and Practices
Arsenic is a naturally occurring metal found in rocks and soil, which can be released into the environment through geological events such as volcanic activity and erosion. Other releases of arsenic into the environment occur through industrial processes such as production of paints, metals, soaps, dyes, drugs, semi-conductors and wood preservatives, as well as in mining and smelting.
General Information and Background
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