Removing Arsenic from Contaminated Drinking Water in Rural Bangladesh: Recent Fieldwork Results & Policy Implications

ARUBA (Arsenic Removal Using Bottom Ash) has proven effective at removing high concentrations of arsenic from drinking water in Bangladesh. During fieldwork in four sub-districts of the country, ARUBA reduced arsenic levels ranging from 200 to 900 ppb to below the Bangladesh standard of 50 ppb. The technology is cost-effective because the substrate—bottom ash from coal fired power plants—is a waste material readily available in South Asia. In comparison to similar technologies, ARUBA uses less media for arsenic removal due to its high surface area to volume ratio. Hence, less waste is produced. A number of experiments were conducted in Bangladesh to determine the effectiveness of various water treatment protocols. It was found that (1) ARUBA removes more than half of the arsenic from water within five minutes of treatment, (2) ARUBA, that has settled at the bottom of a treatment vessel, continues to remove arsenic for 2-3 days, (3) ARUBA’s arsenic removal efficiency can be improved through sequential partial dosing (adding a given amount of ARUBA in fractions versus all at once), and (4) allowing water to first stand for two to three days followed by treatment with ARUBA produced final arsenic levels ten times lower than treating water directly out of the well. Our findings imply a number of tradeoffs between ARUBA’s effective arsenic removal capacity, treatment system costs, and waste output. These tradeoffs, some a function of arsenic-related policies in Bangladesh (e.g., waste disposal regulations), must be considered when designing an arsenic removal system. We propose that the most attractive option is to use ARUBA in communityscale water treatment centers, installed as public-private partnerships, in Bangladeshi villages. Introduction Naturally-occurring arsenic in drinking water is a major public health problem threatening the wellbeing (and in many cases, lives) of more than a hundred million people worldwide. According to World Health Organization estimates, in Bangladesh alone, 28-77 million people drink arsenic-laden water from shallow tubewells (Ahmad et al. 2003). The vast majority of these wells were installed by the Bangladeshi government organizations, international agencies, various NGOs, and private citizens within the past 40 years as an alternative to drinking biologically contaminated surface water. High levels of arsenic were first noted in the shallow tubewells in the early 1990s. The country is currently experiencing the largest case of mass poisoning in human history. Arsenic-laden water is also known to exist in Argentina, Australia, Chile, China, Hungary, India, Mexico, Nepal, Peru, Thailand, and the United States.