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

4.1.3 Decommissioning .........................................................................................................161
4.1.3.1 Decommissioning plan .........................................................................................161
4.1.3.2 Mercury-containing wastes...................................................................................170
4.2 Diaphragm cell plants .............................................................................................................171
4.2.1 Abatement of asbestos emissions and discharges.........................................................171
4.2.2 Asbestos-free diaphragms Application of non-asbestos diaphragm material ...............171
4.2.3 Conversion of asbestos diaphragm cell plants to membrane cell plants technology or
to asbestos-free diaphragms..........................................................................................179
4.3 All Diaphragm and membrane cell plants ..............................................................................183
4.3.1 Environmental management systems ...........................................................................183
4.3.2 Techniques to reduce consumption of raw materials....................................................185
4.3.2.1 Salt........................................................................................................................185
4.3.2.1.1 Choice of salt type ........................................................................................185
4.3.2.1.2 Techniques to reduce consumption of salt....................................................186
4.3.2.1.3 Recycling of waste water from other production processes..........................186
4.3.2.2 Water ....................................................................................................................188
4.3.2.2.1 Overview.......................................................................................................188
4.3.2.2.2 Brine recirculation ........................................................................................188
4.3.2.2.3 Recycling of other process streams...............................................................189
4.3.2.2.4 Closed-circuit direct cooling of chlorine and hydrogen with water..............190
4.3.2.2.5 Concentration of brine filtration sludges ......................................................191
4.3.2.2.6 Use of waste water for solution mining ........................................................192
4.3.2.2.7 Miscellaneous techniques .............................................................................193
4.3.2.2.8 Combination of techniques to reduce the generation of waste water............193
4.3.2.3 Energy...................................................................................................................194
4.3.2.3.1 Overview.......................................................................................................194
4.3.2.3.2 High-performance bipolar membrane cells...................................................194
4.3.2.3.3 High-performance membranes......................................................................200
4.3.2.3.4 High-performance electrodes and coatings...................................................202
4.3.2.3.5 High-purity brine ..........................................................................................203
4.3.2.3.6 Iron(III) meso-tartrate as anti-caking agent...................................................204
4.3.2.3.7 Once-through brine system...........................................................................206
4.3.2.3.8 Plate evaporators...........................................................................................208
4.3.2.3.9 Use of hydrogen as chemical reagent or fuel ................................................210
4.3.3 Metal anodes.................................................................................................................212
4.3.4 Techniques for monitoring of emissions ......................................................................212
4.3.4.1 Overview ..............................................................................................................212
4.3.4.2 Common issues of all monitoring techniques.......................................................212
4.3.4.3 Monitoring techniques and frequency ..................................................................212
4.3.4.4 Monitoring of chlorine and chlorine dioxide in air...............................................213
4.3.4.5 Monitoring of free oxidants in water ....................................................................215
4.3.4.6 Monitoring of halogenated organic compounds in water .....................................216
4.3.5 Techniques to reduce emissions to air ..........................................................................217
4.3.5.1 Techniques to reduce emissions of chlorine .........................................................217
4.3.5.1.1 Techniques to prevent accidents and incidents or to limit their
environmental consequences Safety measures..............................................217
4.3.5.1.2 The chlorine absorption unit .........................................................................223
4.3.5.2 Scrubbing with hydrogen peroxide to reduce emissions of chlorine dioxide .......226
4.3.5.3 Carbon tetrachloride-free chlorine purification and recovery liquefaction and
purification............................................................................................................228
4.3.5.4 Use of refrigerants without ozone depletion potential and with low global
warming potential .................................................................................................230
4.3.6 Techniques to reduce emissions to water .....................................................................231
4.3.6.1 Techniques to reduce emissions of sulphate.........................................................231
4.3.6.1.1 Overview.......................................................................................................231
4.3.6.1.2 Precipitation of sodium sulphate...................................................................232
4.3.6.2 Techniques to reduce emissions of chloride .........................................................233
4.3.6.2.1 Overview.......................................................................................................233
4.3.6.2.2 Nanofiltration................................................................................................233
4.3.6.3 Techniques to reduce emissions of free oxidants Treatment of waste water
containing free oxidants, including bleach destruction.........................................236
4.3.6.3.1 Overview.......................................................................................................236
4.3.6.3.2 Common issues of all techniques to reduce emissions of free oxidants........236
WORKING DRAFT IN PROGRESS
vi December 2011 TB/EIPPCB/CAK_Draft_1