Ashok Gadgil of Berkeley Lab has developed a low-cost and highly efficient method to remove arsenic from water to less than 10 parts per billion (ppb) – the World Health Organization and U.S. EPA standard for drinking water. The technology has been tested in Bangladesh and Cambodia and proven effective. The cost of the treatment is projected to be substantially less than current technologies because it uses a material that is already a waste product to remove the arsenic.
This invention “Arsenic Removal Using Bottom Ash” or ARUBA is based on coating the surfaces of particles of bottom ash (a finely powdered and sterile waste material from coal-fired power plants) with ferric (hydr)oxide . The manufacturing process is conducted at room-temperature and atmospheric pressure. Thus, the material can be produced with relatively simple equipment at low cost.
Removing arsenic from contaminated drinking water is simple. ARUBA is mixed into the water, where it reacts with and immobilizes arsenic by adsorption and/or co-precipitation. The resulting complex can be filtered or settled out of the water, and is safe enough for disposal in municipal landfills, per EPA standards.
Bottom ash is much less expensive than solid ferric oxide particles, which are often used as a filter media to bond arsenic species. Moreover, it has a high surface to volume ratio meaning that less material is required for water treatment, and hence less waste is produced.
The cost of raw materials needed for ARUBA production is expected to be low- less than 0.5 cents ($0.005) per kg ARUBA. Based on field results over three trips to Bangladesh in 2007 and 2008, treating 1 liter of Bangladesh groundwater at an initial arsenic concentration of 400 ppb requires approximately 4-5 grams of ARUBA
