OBSERVATION: Mercury rising

  • 14/09/2002

OBSERVATION: Mercury rising Although there has been a belated shift from the polluting mercury cell technology to the membrane cells, mercury pollution in India is still very high. India does not produce mercury and relies completely on imports. Between 1998-2001, the annual mercury imports stood at 170-190 tonnes, which is 10 per cent of the global mercury consumption. Mercury consumption by Indian caustic-chlorine companies is at least 50 times higher than the average European consumption. Though mercury is not supposed to be consumed in the process, it gets lost during operation as soon as it is used. This has led to 70 tonnes of mercury entering the environment every year by existing mercury cell plants. And this trend is only increasing.

Mercury also finds its use in clinical thermometers, fluorescence lamps, metal switches, batteries, pesticides and certain pharmaceutical drugs and agricultural products. All these products too have a short life and they find their way into the environment shortly after they are disposed. Assuming that only 50 per cent of the mercury is released by these industries, the total mercury pollution load generated every year (including the caustic-chlorine industry) will be about 125 tonnes of elemental mercury. This is about five times more than the total mercury compounds dumped into the Minamata Bay in Japan in 36 years (see box: Mercurial deaths). This means that the mercury pollution being generated in India every year is equivalent to five Minamata disasters.

The mercury cell companies alone release at least 75 times more mercury than what was disposed every year in Minamata.

Unaccounted threat
Ideally, mercury lost in the process should get loaded into the environment through wastes and products. So there should be no difference between the input mercury and mercury released from various outputs. But data collected by grp reveals that there is a large difference in the mercury balance between the input mercury and mercury released into the environment through various sources. grp has found that as much as 44 per cent of mercury loss goes unaccounted and even companies have no clue about this huge alarming loss. Earlier estimates (1982) by the Central Pollution Control Board (cpcb) of mercury loss underplay the magnitude of the problem. Worse still, the character of mercury is such that it is a globetrotter. Studies have revealed how mercury pollution caused in Europe can be found in Antarctica and Africa. This makes the unaccounted disappearance of 44 per cent mercury in India a major health hazard. It is an unknown enemy. And regulations in India are such that they are unable to check and control mercury pollution.

Lax regulations
The focus of regulations for mercury pollution from mercury cell plants in India is on placing checks on mercury concentration from various point sources rather than putting a check on total mercury pollution load entering the environment. This is in contrast with regulations being implemented in Europe where along with the concentration, regulation on total mercury being released from the plant exists.

The existing regulatory standards of India on mercury pollution from caustic-chlorine industry measures emissions of mercury from following point sources: mercury in wastewater and mercury from hydrogen gas holder.

The average mercury loss through wastewater in Indian mercury cells is 0.38 gm per tonne caustic soda and average mercury loss through hydrogen gas holder is 0.01gm per tonne caustic soda. Therefore, only 0.39 gm mercury loss can be accounted as per the existing regulation.

However, the average mercury consumption in Indian mercury cells is 146.6 gm per tonne caustic soda. This means that the regulatory standards are only regulating 0.3 per cent of the total pollution. This alone sums up the effectiveness of regulations in controlling mercury pollution.

Even though the regulations on concentration of mercury from various point sources in India and Europe are very much similar, the absence of total mercury input regulation in India has resulted in the average mercury emissions being as high as 146 grammes per metric tonnes (gm/mt) caustic soda from mercury cell plants. Whereas, by implementing this standard European companies have achieved mercury emissions of 1.5 gm/mt caustic soda.

The future of mercury
In most developed countries, construction of new mercury plants has been banned. The government of India too has followed suit and has banned new mercury cell plants from 1986. But unlike the developed countries where the mercury cells have been given a time frame to close down, no such time frame has been stipulated by the Indian government.

Europe, for example will only have membrane cell plants from year 2010 onwards and all mercury cell plants, which currently produce six million tonnes of caustic soda every year, will be shut down. If Europe can take such decisions to protect the public health even though huge amount of money is involved, it is indeed unfortunate that Indian government has not taken any decision regarding mercury cell companies, whose size is just seven per cent of the European mercury cell sector but is releasing seven times more mercury into environment with disastrous consequences to the public health.

Similar to Europe, in India too, mercury cells should be asked to close down once their economic life ends. However, the question is whether to allow the existing mercury cell plants that have not completed their economic life, considering that their mercury emission is more than 50 times that of a European unit.

One thing that comes out very clearly from grp analysis is that, under no circumstances can the existing mercury cell companies of India meet the mercury emission standards being currently met by the European companies. It would be almost impossible for the existing mercury cell companies of India to reduce their mercury emissions even below 50 grammes per tonne caustic soda, unless they decide to upgrade the technology substantially. The investment for this upgradation would be very high and according to some Indian experts, it would be much more viable to shift to membrane cell technology rather than asking mercury cell companies to upgrade their technology to meet European standards.

Even if we assume that on an average the mercury emissions have been reduced to 50 gm per tonne caustic soda, the total mercury emissions from Indian mercury cells will still be about 20 tonnes per annum, which is about 32 times more than the existing mercury emissions from Europe to produce equivalent caustic soda. Therefore, even for the companies whose economic life has not yet expired, it is a big public health risk to allow them to operate.

One interesting finding of grp is that partial shifting of mercury cell to membrane cell is causing more environmental pollution than good. In these production plants, mercury cells release more mercury and their membrane cell too consume more energy and raw materials. Pollution control boards that claim that mercury pollution has been solved by partial shifting better watch out. grp has found that instead of a decrease, there is an increase in the specific mercury pollution from these plants.

grp has recommended that all existing mercury cell plants should be shut down by 2005. Under its various schemes to promote cleaner technologies, financial institutions should be instructed to provide loans at reduced interest rates for facilitating the changeover from mercury cell technology to membrane cell technology.

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