Arsenic level in ground water in 47 dists crosses WHO limit, says study
A group of scientists in Jadavpur University in Kolkata have observed that arsenic level in groundwater in 47 districts in Bangladesh and nine district s in Indian West Bengal states have already crossed the World Health Organisation (WHO) maximum permissible limit of 50 micro-gram per litre, reports BSS.
The group, led by head of the School of Environmental Studies (SOES) of Jadavpur University, Dipankar Chakraborti, said the world's four biggest sites of groundwater contamination are Bangladesh, West Bengal of India, Inner Mongolia of the People's Republic of China and Taiwan. They said huge withdrawal of groundwater is taking place because of agricultural irrigation.
"We have made a green revolution at the cost of underground water," a study of the SOES observed.
Exploring the state of the diffusion of available techniques for removal of arsenic from groundwater, the SOES scientists noted that in the villages of India and Bangladesh even a highly successful technology may not succeed unless it fits in the rural context and is accepted by the rural people.
"Development of such technology is only possible when a combination is made between technocrats and villagers with proper village level participation," the scientists said.
They said appropriate arsenic removal technologies should be economically viable and socially acceptable.
The researchers said the processes used in the arsenic-affected areas of Chile and Taiwan at full scale treatment plant is coagulation. But the University of Connecticut (patent pending) has claimed a novel and cost effective Arsenic Remedy Technology (AsRT) for the immobilisation of inorganic arsenic such as arsenates and arsenites.
Quoting field survey reports, they said, in some arsenic-affected villages many families due to high iron content in their tubewell water cannot drink the water directly. To make it drinkable, they just keep the water after withdrawal from tubewell for some time, when a brown precipitate settles at the bottom and the users decant the upper clear water or use a common filter to arrest the flock.
"It is a burning question how and where to dispose of arsenic rich flock. Many thinks that arsenic rich flock if disposed of on soil, may contaminate the aquifer," the scientists said adding that in the laboratory (of SOES) we found that cow-dung can eliminate arsenic in volatile form.
Referring to some tests, the SOES scientists said arsenic removal system of Jadavpur University was proved to be 93 per cent to 98.5 per cent effective according to official test results of Government Industrial Toxicological Research, Lucknow, India, National Test House, India, CSIR institute at Nagpur India as well as independent research conducted by Asia Arsenic Network (AAN), Japan and Thailand bureau of the Asia Arsenic Network.
The AAN (Japan) has purchased 300 units of arsenic removal system from CSIR (Council of Scientific and industrial Research) New Delhi, India and installed them in the arsenic-affected areas across Bangladesh, experts in the SOES said.
The SOES researchers opined that the actual solution of groundwater arsenic contamination in Bangladesh and India would be achieved through proper watershed management utilising the available surface water.
Source: The Independent, 06 May ,2001