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Wednesday, Jun 02, 2004

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Low-cost remedies to remove arsenic

M. Somasekhar

The stainless steel filter that removes arsenic from polluted water. The device, developed by NMRL scientists, is cost-effective and easily made.

A STAINLESS steel filter device has been found effective in the removal of arsenic from contaminated drinking water and in making it safe for human consumption.

Interestingly, the filter medium itself is a processed waste material from the steel industry. The device is easy to operate and affordable, even for use in households, according to researchers at the Naval Materials Research Laboratory (NMRL), Ambernath, Maharastra.

Six prototypes of the arsenic removal filter have been put through field trials in the arsenic-affected villages of West Bengal for more than six months.

NMRL, a laboratory under the Defence Research and Development Organisation (DRDO), has filed for a national patent for the process and an international patent (US) for the product (filter).

The main investment (one-time) in the novel device is around Rs 500 for the stainless steel filter and Rs 150for the plastic parts.

The cost of removing arsenic from the contaminated waters works out to Rs 27-30 per 1,000 litres of water.

The life of the filter is five years and it requires little maintenance — just the normal washing and replacement of active ingredients. It does not require power (electricity or battery) and is easy to operate and maintain.

The wastes generated can be converted into cement bricks that can be used for construction, say the NMRL scientists.

Explaining the use of the device, Dr Narayan Das, Director, and Ms Kshipra Misra, Scientist, NMRL, said the filter works on the principle of co-precipitation and adsorption, which is followed by filtration through treated sand. The medium used in the filter is a processed waste of the steel industry and is easily available.

The device has three containers. The reactant material is placed in the first, and the sand-bag in the second.

The water contaminated with arsenic is allowed to flow into the first container, through the second and through the cloth filters. The water thus filtered is collected in the bottom-most container.

The reactant material and sand are periodically replaced, according to the usage.

There are several waste-water treatment technologies and kits for removal of arsenic available in the market.

Their high cost, problems of waste disposal and effect on the environment have been major limitations to their acceptability, said the scientists from the Marine Biology and Environmental Sciences Division of NMRL.

Interestingly, the device was judged one of the most innovative technologies and, recently, NMRL has successfully transferred the technology to the Indian Institute of Management, Ahmedabad (IIMA). The technology has been given on a non-exclusive basis, Ms Misra said.

The next phase of the development involves the fabrication of community type filter devices that can be used in hospitals and schools, and to meet the safe drinking water demands of larger communities.

For this, NMRL has entrusted the job to the Indian Institute of Technology, Mumbai (IIT). A one-year project for the development of prototypes has been finalised, Ms Misra said.

An alarming 66 million people in the Indo-Gangetic belt and around 55 million people in neighbouring Bangladesh are exposed to the threat of arsenic poisoning as the water sources are contaminated.

The levels of arsenic found in drinking water range from 50 ppb (parts per billion) to 20 ppm (parts per million) in parts of Bihar, West Bengal and Chattisgarh States, as against 10 ppb stipulated by the WHO.

The problem of arsenic in groundwater is not unique to India. Reports of arsenic poisoning have emerged from China, Taiwan, Mongolia, Argentina, Chile, Mexico, Vietnam and even the UK, though the levels are far lower.

What happens if people drink arsenic contaminated water for long periods? The known health effects are skin cancer, bronchitis, conjunctivitis and cirrhosis.

NMRL scientists have installed arsenic removal filters in Kamdevkati and Chatra villages of 24 Paraganas District, one of the worst affected in West Bengal, and have run trials in association with `Save the Environment', an NGO and the AIIHPH (All-India Institute of Hygiene and Public Health) in September 2003.

The arsenic and iron concentration fell well below the WHO/EPA drinking water standards of less than 10 ppb and less than 300 ppb respectively.

The filtered water quality is being monitored by the NMRL team and the AIIHPH.

The Jadhavpur University has done an extensive study of the prevalence of arsenic pollution in groundwater in West Bengal and the State Government has also initiated steps to control this growing menace.

The Hyderabad-based National Geophysical Research Institute (NGRI), has also done studies to get to the source of the problem.

Four foreign funding agencies have also joined hands with the environmental engineering cell of Bengal Engineering College to install 85 arsenic-removing units in three districts of West Bengal.

They are: Water For People (a non-governmental organisation based in North America), Rotary Club of Puerto Rico, US-based Conrad N. Hilton Foundation and Das Foundation.

Bengal Engineering College, a deemed university, has installed 10 such units in 24 North Parganas.

The university has an arsenic removal unit, a device that uses activated alumina and is attached to the hand-pumped tubewells.

The alumina absorbs the arsenic and raw iron present in the water. One unit can treat 6,000 litres of water per day.

There is an ongoing Indo-Australian initiative to examine the steps being taken to eliminate arsenic and recommend cost-effective and ecologically sustainable approaches.

The Murdoch University of Australia and the Regional Research Laboratory (RRL), Bhubaneshwar are the lead organisations in this project.

The Australian Agency for International Development (AusAID) has extended support of Rs 2.7 crore. The AusAID also supports a major project in Bangladesh, where arsenic pollution is severe.

While in the short term there is an urgent need to provide immediate relief to those suffering from the ill-effects of drinking water contaminated by arsenic, the long-term solution has to be based on an scientific assessment of the reasons, sources and geographical spread of the problem and in choosing technologies that are effective and affordable, suggest the NMRL scientists.

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