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[NEW DELHI] A new chemical-free method to remove arsenic from water is working well in pilot plants in India, scientists report.

The method, developed by a team of European and Indian scientists, was tested in six plants set up to supply safe arsenic-free water to Kasimpore village in India's West Bengal state, one of the most arsenic-contaminated sites in the world.

An estimated 140 million people in Asia are affected by arsenic contamination of groundwater. Chronic exposure can cause cancers of the skin, lungs, heart and kidneys.

The six plants produce 2,000 litres of safe drinking water, with arsenic levels of about two micrograms per litre. In Kasimpore, 70 per cent of tube wells have arsenic levels of 50 micrograms per litre of water, much higher than WHO guidelines of ten micrograms per litre.

The plants contain a spray nozzle or water jet air pump that sprays oxygen into aquifers, freeing the arsenic.
Treated water is pumped up from the aquifer into a storage tank, and distributed to nearby households through pipelines.

Bhaskar Sengupta, senior lecturer at the department of civil engineering at Queens University, United Kingdom, told SciDev.Net, that an added benefit is that the treatment kills most diarrhoea-causing bacteria in water so that less than one per 100 millilitres remain. "It is automatic disinfection," he says.

Sengupta says setting up a treatment plant could cost about US$2,200 and most of the parts can be purchased from local shops and installed by local plumbers and electricians. The operation cost is US$1 per day to produce 2,000 litres of clean water.

Mohammad Yunus, a senior scientist at the public health sciences division at the International Centre for Diarrhoeal Disease Research, Bangladesh, says that, "overall, the technology seems to be simple and innovative and has potential for supplying arsenic safe water to mass people in affected areas".

But an objective evaluation of the plants for performance, operation and maintenance — as well as community participation — is essential before wider application of the technology, he adds.

The scientists published their findings online in Environmental Pollution last week (9 October). The project is funded by the European Commission.