Cleaning Arsenic from Bangladesh's Water
In the largest case of mass poisoning in the world, arsenic contaminates the drinking water of about a hundred million people worldwide. In Bangladesh alone, forty million people are exposed to arsenic levels as high as 1,200 ppb, 240 times the level deemed acceptable by the Bangladeshi government. Chronic exposure to arsenic leads to a series of health problems including disfigurement, gangrene, heart disease and lung and kidney cancers. Since 1999, Ashok Gadgil and his Berkeley Lab colleagues have been working on the enormous challenge of finding an effective, affordable and practical way to remove the arsenic from water in Bangladesh. They have filed patents for two promising technologies.
One method Berkeley Lab scientists have developed involves coating particles of coal ash with ferric hydroxide. In water, the arsenic binds to the resulting dark red powder and can be filtered out with the coated ash. Sold for around $2 per person for a year's supply, this low cost powder (Arsenic Removal Using Bottom Ash — ARUBA) is affordable to low-income villagers while allowing the factory and local distributors to make a small profit. The process is now available for licensing from Berkeley Lab and a number of companies have applied for exclusive rights.
The second technology, developed in 2005, is a device based on electrochemistry. The scientists envisage that one D cell battery will be adequate power to treat enough drinking water for one person each year. The major benefit of the device is that all it will need to function is the battery, so villagers will not be dependent on a central factory for replenishing an arsenic-depleting medium.