In-situ arsenic removal from groundwater for application in developing countries

researcher: Doris van Halem

Project outline

Arsenic contamination in groundwater is found in many countries worldwide, including Argentina, Bangladesh, Hungary, India, the United States, and Vietnam. The main reason for concern is de gradual, chronic poisoning by this invisible, toxic metal. The first symptoms of arsenic poisoning are (de)pigmentation of the skin and toughening of palms and soles (black-foot disease). Chronic exposure may cause cancer of the skin, lungs, urinary bladder and kidneys.
Even though many techniques have been developed over the years to remove arsenic from groundwater, a solution is not yet at hand for many people living in rural areas. The use of subsurface arsenic removal could proof a reliable alternative, especially in regions where shallow tube wells are already used for drinking water supply. Arsenic and iron are retained in the aquifer and thus no waste stream is produced. In short, the periodic injection of aerated water oxidizes adsorbed iron (II) to iron (III) and therefore forming new adsorption sites for iron (II) and trace elements such as arsenic.

 

      
Principle of subsurface arsenic removal. Left: injection of water. Right: abstraction of water.

Scientific relevance

Even though subsurface iron removal is operated worldwide for many decades now, the use for arsenic retention is a new approach. Before subsurface arsenic removal can be safely implemented it is vital to identify the parameters influencing the retardation of arsenic to the well, e.g. pH, competing anions, Fe:As ratio.

Social relevance

One only has to hear about the ‘mass poisoning’ of people living in the Bengal Delta to understand the social relevance of arsenic-related research topics. The use of subsurface arsenic removal to treat groundwater is not only interesting from a scientific point-of-view; it may also provide safe drinking water to millions worldwide. Therefore this research study should extend beyond acquiring theoretical answers and also translate the technology to the practicality of the users’ real world. In Bangladesh the study is executed in collaboration with local partners UNICEF and DPHE (Department of Public Health Engineering).

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