Treatment of arsenic-contaminated water using a simple, inexpensive and sustainable technology
Arsenic contamination affects more than 20 nations throughout the world, including the United States, India, Bangladesh, Pakistan, Argentina, Chile, Mexico and Taiwan...
By Jeremiah D. Jackson, Ph.D., PE, Senior Principal Engineer, Kleinfelder (San Diego, CA)
Arsenic contamination affects more than 20 nations throughout the world, including the United States, India, Bangladesh, Pakistan, Argentina, Chile, Mexico and Taiwan. World Health Organization (WHO) estimates suggest that more than 35 million people in Asia alone are consuming arsenic-contaminated waters with concentrations great enough to cause chronic illness and premature death. Typical small-scale treatment processes include reverse osmosis, ion exchange and activated alumina adsorption. Unfortunately, these approaches are technically sophisticated, requiring trained operators, and are relatively expensive at approximately $53 to $300 (USD) per 1,000 gallons of treated water. These requirements have limited their widespread use in rural and poor areas.
The need for a cheaper and easier technology prompted a senior engineer at Kleinfelder to develop an innovative arsenic removal approach that uses inexpensive and sustainable natural processes to remove poisonous arsenic from drinking waters. Initial research proved promising enough to construct a prototype system sized to treat a rural family's drinking water. The prototype was operated during a summer and winter season to demonstrate its effectiveness in treating contaminated drinking water with an arsenic concentration of 300 micrograms per liter (ug/L).
The prototype system is composed of simple household materials -- such as plastic sheeting, sand and milk jugs -- and uses indigenous aquatic weeds (namely, common cattails: Typha spp.) in its removal of arsenic from the water. (See photograph.)
Operation of the prototype system over an extended period resulted in an average arsenic removal rate of 89 percent, with an effluent arsenic concentration of 34 ug/L. This quality water is considered acceptable by the WHO for long-term consumption by humans. Advantages of this system include that it can be constructed and operated by untrained individuals, and occupies a small 12-square-foot space. The system is extremely inexpensive, with an estimated annual cost of only $0.21 (USD) per 1,000 gallons of treated water. The system is designed for single-family use, although it is easily scalable, and thus can also be used in large-scale domestic and agricultural applications.