(BAT) Reference Document for the Production of Chlor-alkali ...

Example plants
Dow, Stade (Germany), chlorine capacity 1585 kt/yr.
Reference literature
[ 57, EIPPCB 2011 ]
4.3.2.2.7 Miscellaneous techniques
Chapter 4
Other techniques to reduce water consumption include [ 124, COM 2011 ], [ 130, Austria
1996 ], [ 131, Germany 2003 ], [ 132, Germany 2000 ]:
waste water-free processes for vacuum generation;
waste water-free processes for exhaust air cleaning;
reduction of brine purge volume by using vacuum salt;
reduction of brine purge volume by using nanofiltration (see Section 4.3.6.2.2);
reduction of brine purge volume by using techniques to reduce chlorate emissions (see
Section 4.3.6.4.
Although residual levels of chlorine in process exhaust are removed by wet scrubbing with
caustic, usually no waste water is generated because the produced bleach is often a saleable
product or because it can be recycled to the brine system (see Section 4.3.6.3.6).
The brine purge volume can be reduced by using vacuum salt, the production of which,
however, requires significant amounts of energy during purification (see Section 4.3.2.1.1).
{Please TWG provide more information.}
4.3.2.2.8 Combination of techniques to reduce the generation of waste water
Description
Chlor-alkali plants generally use a combination of techniques to reduce the generation of waste
water.
Technical description
Individual techniques are described in the Sections 4.3.2.2.2 to 4.3.2.2.7.
Achieved environmental benefits
The achieved environmental benefits of this technique include the following:
reduction of water consumption/waste water generation;
reduction of salt consumption;
reduction of chloride emissions.
WORKING DRAFT IN PROGRESS
Environmental performance and operational data
During the period of 2002 to 2010, the average waste water volume of chlor-alkali plants in
EU-27 and EFTA countries oscillated between 1.87 and 2.04 tonnes per tonne of chlorine
produced [ 73, Debelle 2011 ].
A suitable combination of techniques results in generation of waste water volumes of
0.5 – 1 m 3 /t chlorine produced [ 131, Germany 2003 ].
{Please TWG provide more information. It would be good to have concrete examples of plants
which use a combination of techniques and the resulting water consumption levels.}
TB/EIPPCB/CAK_Draft_1 December 2011 193