Monday, December 6, 2010

Are Residential RO Drinking Water Systems Effective for Arsenic Removal? Not Really.

by Beth Thomas CWS VI, Business Development Manager, AdEdge Technologies Inc.

While continuing to be sold as a good method for removing arsenic from potable water in homes, Reverse Osmosis (RO) technology is not effective in treating arsenic in residential applications. In fact, The Water Quality Association and the American Water Works Association changed their recommendation for this application as not acceptable several years ago when it was determined that reverse osmosis membranes do not remove both forms of arsenic. While arsenic V is removed, arsenic III is not effectively removed. Most groundwater supplies are higher in arsenic III than in arsenic V.

Another concern with the use of RO for arsenic removal is that the arsenic rejected by the membrane is concentrated in the waste stream. This reject stream is then discharged back to the environment through the sewer, septic system, or leach field. Consequently, residential RO systems waste water. Most systems use about 8-9 gallons of water for every gallon of treated water produced. Larger commercial and municipal systems have a much better efficiency rating.

The good news is that residential systems are available to the public that are efficient, environmentally friendly and effectively remove arsenic. AdVantEdge™ residential drinking water systems by AdEdge Technologies, use arsenic filtration cartridges. These systems do not have a reject stream. They remove both arsenic III and arsenic V. In fact, these cartridges can be also be used as pretreatment to an RO membrane to remove arsenic so there is none in the waste stream, or as in-line cartridges used after the RO to remove the arsenic III not removed by the membrane.

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