Arsenic mitigation dilemma

Experts caught between treatment of surface and contaminated water
After years of research on mitigation and debates, experts are still divided over whether to opt for surface water or chemical methods in the face of groundwater arsenic contamination.

One camp voices its views against treating the contaminated tubewell water by chemical methods, while the other demands that chemical options can be considered only when surface water options are not available.

According to sources in the Bangladesh Arsenic Mitigation Water Supply Project (BAMWSP), both the surface water and chemical options have been approved for mitigation purpose. And some of the affected villages have already gone for surface water options.

Experts in favour of the surface water said the surface water in most of the places has no risk of chemical contamination. Here they argue that if the people need to use chemicals to remove arsenic, they have to consider the fact that how much they can deal with the sludge, which may be highly toxic, and villagers may not be in a position to dispose of them.

"If you consider the rural area of Bangladesh, you will find ponds, rivers, dug wells and the gift of God -- rainwater, of course. These are all potential sources of natural water. But we have completely ignored such sources, and gone for the underground water, which is an injustice to nature," said Prof. Quazi Quamruzzaman, chairman of the Dhaka Community Hospital Trust.

Prof. Quamruzzaman said, "Before the advent of tubewells, people used to use surface water and live with micro-organisms. But as time passed, we learned to kill the germs in water and reduced the incidences of water-borne diseases like diarrhoea."

He also said there is no reason why the people should not opt for the surface water. "Yes, it is true that the people may find it difficult to shift back to the past habit that has been altered over 30 years, but it is still worth recommending that a shift in habit would cost us virtually nothing," goes the argument.

People have to boil water before taking it, which is still a traditional practice in many parts of the country where no tubewell is available as in the Barendra region.

At the other extreme, the propo nents of chemical options said they do not oppose the use of surface water, but in the face of such a serious crisis, there is no alternative to chemical methods.

A researcher of Dhaka University said, "Surface water option means that the people eventually have to return to the traditional habit of drinking from ponds and rivers. How far it is feasible and safe is a big question. But from my experience, the tubewell has become a symbol of safe-drinking water. People trust it and want to stick to it."

Dr Firoz Ahmed, a leading researcher in this field and professor of Bangladesh University of Engineering and Technology (BUET), said, "Surface water options have many demerits like the risks of micro-organisms and man-made contamination as in the case of the Buriganga. If you use surface water, you have to consider some of the treatment processes like the removal of micro-organisms and toxic substances."

Dr Firoz also suggested that whenever possible, the people opt for chemical methods, since it is the safest way of removing toxic chemicals from water.

In the western countries, no matter what the source is, chemical reaction is a must to ensure safety, some researchers of chemical options pointed out. And it is not possible to make sure that the surface water does not contain the harmful level of hard metal, they cautioned.

Source: The Daily Star: July 6, 2001