All silicones plants have permits, which limit effluent discharge and define daily limits for discharge volume, flow rate and concentration of pollutants. The parameter used is chemical oxygen demand (COD), expressed as metric tonnes of oxygen. COD emissions are measured at all plants and analysed and managed daily. An monthly environmental review is organised at plant and board level for the French plants as they represent around 99 per cent of Elkem Silicones’ effluents.
In addition to compliance with local environmental permits, continuous improvement in both water use and COD reduction is the goal. Several improvement projects have been initiated during the last 3 – 4 years. Some examples are:
• Several contaminated water discharges stopped and are now incinerated
• Installation of dry vacuum pumps instead of water vacuum pumps
• Optimisation of pH treatment to remove soluble copper before discharge
• New distillation column to reduce volatiles.