Dr Jamal Anwar
 

ARSENIC contamination of the groundwater was detected in 1993. A lot of money has been invested to arrange seminars and develop expensive and largely ineffective filters; however, the rural poor, the worst affected in the crisis, has not yet got the support they really need. Interestingly, while much attention has been paid to treatment of arsenic-contaminated tube-well water, simpler and less expensive alternatives have been ignored. I have gone to numerous villages in Bangladesh and found that the water of kua (dug well), although not in use, is not arsenic contaminated.

Dug well is an indigenous technology, is socially accepted and can be constructed with easily available resources. In the United States, Section 265.91 of the Code Federal Registration (CFR) requires special design, criteria casing, clay packing, etc while sinking wells in a contaminated region. A dug well requires double casing made of terra cotta clay rings where inside is filled with clay to inhibit water percolation from the surrounding geological formation.

Pathogen, bacteria, viruses can be removed through solar radiation (at no cost) and other methods at site which is acceptable to all. It is easy to remove bacteria. But present experiences in Bangladesh and India show that household methods of arsenic removal have totally failed but the donors and the NGOs are continuing to support the ineffective methods.

The construction of dug wells that existed even 30 years ago have almost vanished from the country due to non-use and popularisation of tube-wells.

Advantages of dug wells are:

• Dug wells are indigenous technology.

• The wells are cheaper and easier to construct and less susceptible to bacteriological contamination (BRAC, August 2000).

• Natural biological filtration occur, when water percolates through sand bodies (develop microbial flora whose metabolism contributed to the effectiveness of removing effluents)

• In dug wells within the standing water simple sedimentation take place and has been found frequently a substantial reduction in BOD (Biological Oxygen Demand).

• Natural iron coagulation and settlement occur within standing water (decrease in arsenic, suspended solids, ammonia, nitrate and phosphate content).

Protected dug wells provide acceptable bacteriological quality but usual investigation and monitoring methods are inadequate in Bangladesh.

Surface water irrigation

Agriculture through contaminated groundwater is now contaminating our food chain. There is no programme to go back to traditional method of agriculture. The government has no programme on "floodwater" irrigation. Wilcock, an irrigation expert, who visited Bengal in early 19th Century, was overwhelmed to see irrigation system in Bengal. He had said, "River water in the early months of the flood is gold. 2.5 billion tonnes of fertile soil carried by the rivers Ganges-Brahmaputra goes directly to the Bay of Bengal." Flood irrigation system is the only alternative. It will not only stop contaminating food chain and surface water but also reduce use of fertiliser. As we notice after each severe flood, a bumper crop in Bangladesh is recorded.

Conclusion

Arsenic problem in Bangladesh should be solved within our traditional wisdom. Herb Klein, a former US congressman (July 1998) expressed, "Much is already clear and it is deeply embarrassing for western scientists and engineers for this crisis is entirely due to their failures."

We do not want the same mistake repeating in the name of mitigation. We were united during our independence, severe cyclones, floods and severe tidal storms. Now there is a greater need to be united and fight together for arsenic free water.

Previous Page

Top