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< prev - next > Water and sanitation Water quality and treatment KnO 100401_Arsenic and iron removal plant (Printable PDF)
Groundwater is the main source of water
supply in Bangladesh. Groundwater
abstracted from tubewells was
considered to be the best option for
water supply in rural and peri-urban
areas. Unfortunately, arsenic in excess
of the acceptable limit has been found
in tubewell water in many parts of the
world and particularly in Bangladesh.
Alternative options for arsenic-safe
water are urgently needed to mitigate
arsenic toxicity and protect public
health and there has been considerable
research into a range of technologies.
Some of the common arsenic mitigation
technologies include:
Co-precipitation of arsenic and iron
Adsorption of arsenic onto coagulated
Lime treatment
Adsorption onto sorptive media
Ion exchange
Filtering by special membrane
Microbial process
One low-cost option based on the co-
precipitation principle that is showing
promises is the arsenic and iron removal
plant (AIRP) that has been tested in
Bangladesh. This approach to arsenic
mitigation is described in this Technical
How does the AIRP system work?
Figure 1: AIRP Design.
The basic structure of the 4 chamber plant is shown in Figure 1. Water contaminated with
arsenic and iron from the source tubewell is introduced to chamber C1. The water spreads
through the perforations of the inlet pipe. This action aerates the water. In the aeration
process, oxygen from the air reacts with iron and arsenic in the water. This transforms the
soluble arsenic and iron into insoluble compounds. The insoluble arsenic and iron
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