Investigating subsurface iron and arsenic removal: Anoxic column experiments to explore efficiency parameters

Investigating subsurface iron and arsenic removal: Anoxic column experiments to explore efficiency parameters

Van der Laan, H.

Van Dijk, J.C. (mentor)
Van Halem, D. (mentor)
Petrusevski, B. (mentor)
Olsthoorn, T.N. (mentor)

Civil Engineering and Geosciences

Watermanagement

Sanitary Engineering

2009-09-01

High concentrations of arsenic in drinking water form a major threat for public health in more than 70 countries worldwide. The situation is Bangladesh is seen as the worst incidence of arsenic poisoning: it is believed that 30 million people in Bangladesh are exposed to an arsenic concentration exceeding 50 ?g/L. Recently subsurface treatment as a possibility for arsenic removal for drinking water supply on community scale in rural Bangladesh has been recognized. The application of this subsurface treatment technique for arsenic removal is seen as very promising, since it has many advantages: it is a residue free, low-cost technology and no hazardous chemicals or expensive filter media are required. The technique, already applied for decades in Europe for subsurface iron removal, involves the injection of aerated water into an anoxic aquifer, where consequently ferrous iron is oxidized by the injected oxygen. Subsequently, the flow is reversed and a multiple of the injected volume can be extracted with lowered iron concentrations, which makes the technology successful. Efficiency ratios (V/Vi) of extracted water (V) over injected water (Vi) are typically increasing over the successive cycles and may range from 3 to 30. The freshly formed ferric oxides are potentially effective adsorbents for trace elements like arsenic. Yet, there is a lack of insight in both (i) the fundamental knowledge of the responsible mechanisms causing the (increasing) sorption of iron and arsenic, and (ii) the operational factors through which the removal efficiency can be optimized. The primary goal of this study is to gain a better understanding of these dominant mechanisms and the observed increasing efficiency, in order to optimize the operation of this technology in the field.

arsenic
drinking water
Bangladesh

http://resolver.tudelft.nl/uuid:d9713dec-437a-4066-ae9e-bc75b7f3e80d

Student theses

master thesis

(c) 2009 Van der Laan, H.