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

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Chapter 4 4. The power supply In most cases, the transformers and rectifiers are replaced, either because they have reached the end of their life (approximately 30 years) or because their technical characteristics are incompatible with the requirements of new membrane cell electrolysers. Existing mercury electrolysers are, with a few exceptions, monopolar (high current, low voltage), while new membrane electrolysers are bipolar (low current, high voltage) [ 211, Dibble and White 1988 ], [ 232, Euro Chlor 2010 ]. Reuse of the rectifiers depends on the type of membrane cell configuration and power requirements. The decision to renew the power supply or not will depend, among other things, on the balance between investment and operating costs. A monopolar conversion should be possible using existing rectifiers and transformers, as, with few exceptions, existing plants are monopolar. Bipolar conversions can also be carried out keeping the existing power supply, one example being the conversion of Donau Chemie in Brückl (Austria) in 1999 [Schindler]. A careful review of voltage is required to ensure that adequate control is achievable for the membrane system. 5. Gas treatment facilities Chlorine and hydrogen collection and treatment are not essentially different in membrane and mercury cell plants compared to the mercury process. Process steps to remove mercury are no longer needed. The main concern for the new cell room is the method of pressure control of the gases. The membrane cell technique technology requires a steady differential pressure of hydrogen over chlorine. This means that a differential pressure controller must be added to the existing control system [ 211, Dibble and White 1988 ]. The chlorine and hydrogen gases leave the cell at higher temperatures than with the mercury cell technique technology. The gases will be are saturated with water vapour and so therefore the loading on gas coolers will be higher, as will the volume of resulting condensate. In addition, the primary cooling system for hydrogen is usually part of the mercury cells. New cooling equipment may be needed is therefore needed in most cases [ 232, Euro Chlor 2010 ]. Chlorine from membrane cells contains more oxygen, which for some applications needs to be removed prior to downstream use of the chlorine. For this purpose, total liquefaction followed by subsequent evaporation of liquid chlorine is necessary. Larger liquefaction units than those normally in operation are therefore required for these applications. 6. Caustic treatment The mercury cell technique technology produces 50 wt-% caustic soda. Membrane cells require a recirculating system with associated heat exchange and dilution and to produce 33 wt-% caustic soda. If more concentrated caustic soda is needed, an evaporator system is also necessary [ 211, Dibble and White 1988 ]. These changes usually require an extension of the cooling water circuit and steam production [ 232, Euro Chlor 2010 ]. WORKING DRAFT IN PROGRESS 7. Process piping The reuse of existing process piping is not appropriate when converting to the a membrane cell technique process, as the physical location is often very different from that required by membrane electrolysers. The existing piping may also be made of material unsuitable for use with membrane electrolysers [ 211, Dibble and White 1988 ]. An example of a conversion is the Borregaard chlor-alkali plant in Sarpsborg (Norway). Data are summarised in Table 4.2. 150 December 2011 TB/EIPPCB/CAK_Draft_1
Chapter 4 Table 4.2: Data from the conversion of the Borregaard chlor-alkali plant to the membrane cell technique technology Context of the old production units: cell room built in 1949: 3 floors, 122 cells; mercury air emissions to air: 1.4 g/tonne chlorine capacity; mercury water emissions to water (water ion exchange process): 0.25 g/tonne chlorine capacity. Driving forces for conversion: demand from the Norwegian authorities to switch to a mercury-free technique process; demand for higher production of sodium hydroxide and wish to lower operating costs. The conversion: decision made to convert: autumn 1995; conversion carried out: autumn 1997; shutdown time: 7 weeks. Characteristics of new plant: chlorine capacity 40 kt/yr 40000 tonnes Cl2 capacity/year at 4.35 kA/m 2 ; supplier: Asahi Glass Co. Ltd. Japan engineering: Krebs-Swiss electrolyser: AZEC-B1 bipolar, 4 electrolysers, each 75 cells, 4.35 kA/m 2 ; membrane area: 2.88 m 2 per cell. membrane: Flemion 893 Reused equipment: rectifiers; hydrogen treatment and HCl production units; chlorine compression and liquefaction section and compression. New equipment: cell room for electrolysers: the existing building was considered old and mercury-contaminated; electrolysis section; brine circuit: brine filtration unit, ion exchange unit, brine dechlorination unit; sodium hydroxide recirculation concentration unit and evaporation system; chlorine gas drying unit and chlorine gas absorption unit; power supply and wiring (excluding rectifiers); pumps, instruments and piping. Cost of conversion: Total cost of conversion was about NOK 210 million NOK (EUR 26.6 million euros in October 1997) corresponding to about EUR 665 euros/tonne chlorine capacity. This figure includes EUR 2.4 million euros for the clean-up of the old plant and the storage of mercury-contaminated waste but excludes the clean-up of soil pollution. Economic benefits: electricity: 30 % reduced per tonne 100 % NaOH produced; personnel: 25 % reduced; some mercury sold for batteries, instruments and to mercury cell chlor-alkali plants; return on investment: five 5 years (depending on the caustic market). WORKING DRAFT IN PROGRESS Decommissioning: no clean-up of mercury-contaminated soil; monitoring of mercury emissions to air from old cell room; construction of a sealed disposal facility for mercury-contaminated wastes: building volume 1800 m 3 , 3 special membranes with sand filter seals in between. The bunker is ventilated and the vented air led through a carbon filter. The majority of the wastes (about 55 %) was mercurycontaminated process equipment (steel and rubberlined steel); 95 tonnes of mercury drained from the cells. Source: [ 227, de Flon 1998 ][de Flon, 1998] TB/EIPPCB/CAK_Draft_1 December 2011 151
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EUROPEAN COMMISSION JOINT RESEARCH
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PREFACE 1. Status of this document
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Reference Document on Best Availabl
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3.4.7 Emissions of noise ..........
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4.3.6.3.3 Chemical reduction ......
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List of Tables Table 2.1: Main char
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List of Figures Figure 1.1: Share p
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SCOPE WORKING DRAFT IN PROGRESS Sco
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1 GENERAL INFORMATION 1.1 Industria
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Chlorine production in Mt/yr 12 11
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Chapter 1 Figure 1.4 shows the annu
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Share of total capacity in % 70 70%
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1.4 Chlor-alkali products and their
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Total consumption: 9 801 kt Miscell
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1.4.5 Consumption of hydrogen Chapt
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Chapter 1 and hazardous waste incin
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2 APPLIED PROCESSES AND TECHNIQUES
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Chapter 2 WORKING DRAFT IN PROGRESS
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Chapter 2 The main characteristics
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2.2 The mercury cell technique proc
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Chapter 2 Characteristics of the ca
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2.3 The diaphragm cell technique pr
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Source: [ 2, Le Chlore 2002 ] [USEP
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2.4 The membrane cell technique pro
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Chapter 2 (carcinogenic) [ 76, Regu
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Chapter 2 The membranes used in the
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Table 2.2: Typical configurations o
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2.5 Brine supply 2.5.1 Sources, qua
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Chapter 2 centrifuges before dispos
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Source: [ 29, Asahi Glass 1998 ] (p
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Impurity Source Upper limit of brin
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Chapter 2 No such dechlorination tr
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Chapter 2 The cooling water is gene
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Chapter 2 composition of the chlori
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2.6.11 Dealing with impurities 2.6.
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Chapter 2 amount of chlorine, and t
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2.6.12.2 Chemical reactions Chapter
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2.7 Caustic processing production,
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Chapter 2 2.8 Hydrogen processing p
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3 CURRENT PRESENT EMISSION AND CONS
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Chapter 3 Table 3.1: Overview of em
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3.3 Consumption levels of all cell
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3.3.3 Ancillary materials Ancillary
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Further materials and/or further us
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Chapter 3 current) and the efficien
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Chapter 3 distance means a higher f
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3.3.4.3.6 Production of caustic pot
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Chapter 3 hydrogen at low pressure
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28 kg of hydrogen is produced {Thes
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Chapter 3 depleted brine is recircu
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Chapter 3 Table 3.10: Emissions of
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Chapter 3 When measuring chlorine i
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Chapter 3 concentrations of organic
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Chapter 3 3.4.3 Emissions and waste
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Chapter 3 {Please TWG provide infor
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Page 117 and 118: Chapter 3 produced per year has bee
Page 119 and 120: Chapter 3 Table 3.21: Emissions of
Page 121 and 122: Chapter 3 of chlorine capacity. The
Page 123 and 124: Table 3.23: Mercury emissions from
Page 125 and 126: Mercury emissions in g Hg/t Cl capa
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Page 129 and 130: Chapter 3 Table 3.25: Emissions of
Page 131 and 132: Chapter 3 KCl are higher than from
Page 133 and 134: Chapter 3 When concentrated solid c
Page 135 and 136: Chapter 3 Generally, storage of con
Page 137 and 138: Chapter 3 recycled brine systems si
Page 139 and 140: Process Maintenance To solid treatm
Page 141 and 142: 3.5.9.5 Graphite and activated Acti
Page 143 and 144: Chapter 3 Table 3.31: Yearly waste
Page 145 and 146: Chapter 3 The fact that the differe
Page 147 and 148: Chapter 3 3.6 Emissions Emission an
Page 149 and 150: Reported asbestos concentrations ar
Page 151 and 152: Chapter 3 3.7 Emissions Emission an
Page 153 and 154: {A list of techniques used on full
Page 155 and 156: 3.8.3 PCDDs/PCDFs, PCBs, PCNs and P
Page 157 and 158: Chapter 3 The ‘dioxin’ pattern
Page 159 and 160: Chapter 4 4 TECHNIQUES TO CONSIDER
Page 161 and 162: Heading within the sections Cross-m
Page 163 and 164: 4.1 Mercury cell plants 4.1.1 Overv
Page 165: Chapter 4 plants at comparable capa
Page 169 and 170: Chapter 4 environment can be expect
Page 171 and 172: 4. Plant size Chapter 4 An increase
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Page 175 and 176: Chapter 4 Generally, conversion cos
Page 177 and 178: 4.1.3 Decommissioning 4.1.3.1 Decom
Page 179 and 180: 3. Emptying of the cells and handli
Page 181 and 182: Chapter 4 Table 4.7: Overview of co
Page 183 and 184: Table 4.8: Techniques for monitorin
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Page 187 and 188: 4.2 Diaphragm cell plants 4.2.1 Aba
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Page 191 and 192: Chapter 4 diaphragms [ 31, Euro Chl
Page 193 and 194: Driving force for implementation Th
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Page 197 and 198: Chapter 4 directly from the cells.
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Page 203 and 204: Chapter 4 removal of conductive com
Page 205 and 206: Chapter 4 Cross-media effects Plant
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Page 209 and 210: Example plants Dow, Stade (Germany)
Page 211 and 212: Chapter 4 current density resulting
Page 213 and 214: Chapter 4 modifications to auxiliar
Page 215 and 216: Table 4.14: Cost calculation for th
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Chapter 4 membrane lifetimes range
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Chapter 4 Cross-media effects Some
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Chapter 4 The drawback of using fer
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Chapter 4 evaporation unit integrat
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Chapter 4 Environmental performance
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Chapter 4 Technical description The
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Chapter 4 Table 4.17: Monitoring te
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Chapter 4 Environmental performance
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Environmental performance and opera
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Chapter 4 Prevention of chlorine re
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Chapter 4 Good pipework design to m
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Chapter 4 was the solution at that
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differential pressure at inlet and
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Chapter 4 chlorine scrubber, immedi
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Chapter 4 Achieved environmental be
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{Please TWG provide more informatio
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environmental legislation; generati
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Chapter 4 Table 4.21: Examples of o
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Chapter 4 Driving force for impleme
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4.3.6.3.4 Catalytic decomposition r
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Chapter 4 In both cases, the spent
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Chapter 4 Example plants Thermal de
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Chapter 4 migration of hydroxide io
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eduction of chlorate emissions; red
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Example plants Solvin in Antwerp-Li
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eduction of costs related to equipm
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Chapter 4 Off-site reconcentration
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Chapter 4 b) closing of doors and w
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4.4 Membrane cell plants 4.4.1 High
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4.5.3 Containment Chapter 4 Descrip
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Chapter 4 Sections 4.5.4.2 and 4.5.
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Chapter 4 At this site, mercury con
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Chapter 4 However, the soil washing
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5 BEST AVAILABLE TECHNIQUES Scope
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General considerations In these BAT
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5.2 Decommissioning of mercury cell
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5.3 Environmental management system
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Chapter 5 The BAT-associated enviro
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Chapter 5 6. In order to reduce ene
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5.6 Monitoring of emissions Chapter
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[This BAT conclusion is based on in
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5.9 Generation of waste Chapter 5 1
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5.11 Site remediation Chapter 5 20.
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Chapter 5 inorganic chloramines, di
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6 EMERGING TECHNIQUES 6.1 Introduct
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Chapter 6 cooperation with the Japa
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Chapter 6 In December 1998 a test w
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6.3 Use of fuel cells in chlor-alka
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Chapter 6 hydrogen that is burnt to
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Chapter 7 7 CONCLUDING REMARKS AND
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REFERENCES References [1] Ullmann's
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References [63] Euro Chlor, Euro Ch
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References [112] Santorelli et al.,
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References [161] Germany, 'Verordnu
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[212] Florkiewicz, Long life diaphr
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References [259] Rappe et al., 'Lev
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GLOSSARY OF TERMS AND ABBREVIATIONS
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V. Units · VI. Chemical elements T
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VIII. Acronyms and definitions AC A
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EOX Extractable Organically-bound H
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Glossary Technique Ensemble of both
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ANNEX Annex {The CAK plant capaciti
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Euro Chlor No. Country code Company
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