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Water emissions
| Water emissions : meet the standards of the most restrictive community in which we operate, at all sites, for waste water discharge. |
Several waste water treatment plans were upgraded during 1999 and a new one was installed at Rousset in France in order to face significant increase in production and to maintain the waste water parameters within the stringent corporate limits.
In addition, buffer tanks were installed at several sites to cater both for: storage of untreated water in case of plant shutdown or parameters out of compliance; storage of water in case of emergencies such as chemical warehouse fires or other spills.
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At Rousset, in cooperation with the French authorities and local associations, ST participated in the construction of an advanced waste water treatment within the industrial park where the plant is situated to minimize emissions to the nearby river Arc. |
ST's new 8-inch plant started operation in 1999 but even with the increase of productivity from both the 6-inch and 8-inch fabs, significant achievements in water emissions were accomplished:
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Fluoride |
decreased from 13 mg per liter to less than 2 |
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Phosphates |
decreased from 6 mg per liter to less than 1 |
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Suspended solids |
decreased from 30 mg per liter to less than 4 |
Because of the introduction of new processes in the fabs, the waste water treatment plant was extended during the second half of 1999 in order to treat new effluents such as ammonia and nitrates. When the biological treatment is complete, the ammonia content of water will be less than 0.5 mg per liter, compared to the present 15 mg per litre.
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For further protection of the river, the site installed an oil separator designed for the treatment of 460 litres per second which is the equivalent of the emissions from a car park capacity of 25,000m2. |
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A storm water storage tank of 7,000m3 was also dug for use during heavy rainfall. Part of this storage can also collect potentially contaminated water from major fires. |
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