# Commission Implementing Decision of 9 December 2013 establishing the best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council on industrial emissions, for the production of chlor-alkali (notified under document C(2013) 8589) (Text with EEA relevance) (2013/732/EU), Division 2: Decommissioning or conversion of mercury cell plants

Extent: E+W+S+N.I.

BAT 2: In order to reduce emissions of mercury and to reduce the generation of waste contaminated with mercury during the decommissioning or conversion of mercury cell plants, BAT is to elaborate and implement a decommissioning plan that incorporates all of the following features:
(i) inclusion of some of the staff experienced in running the former plant at all stages of elaboration and implementation;
(ii) provision of procedures and instructions for all stages of implementation;
(iii) provision of a detailed training and supervision programme for personnel with no experience in mercury handling;
(iv) determination of the quantity of metallic mercury to be recovered and estimation of the quantity of waste to be disposed of and of the mercury contamination contained therein;
(v) provision of working areas which are:
(a) covered with a roof;
(b) equipped with a smooth, sloped, impervious floor to direct mercury spills to a collection sump;
(c) well lit;
(d) free of obstructions and debris that may absorb mercury;
(e) equipped with a water supply for washing;
(f) connected to a waste water treatment system.
(vi) emptying of the cells and transfer of metallic mercury to containers by:
(a) keeping the system closed, if possible;
(b) washing of mercury;
(c) using gravity transfer, if possible;
(d) removing solid impurities from mercury, if necessary;
(e) filling the containers to ≤ 80 % of their volumetric capacity;
(f) hermetically sealing the containers after filling;
(g) washing of the empty cells, followed by filling with water.
(vii) carrying out of all dismantling and demolition operations by:
(a) replacing hot cutting of equipment by cold cutting, if possible;
(b) storing contaminated equipment in suitable areas;
(c) frequent washing of the floor of the working area;
(d) rapid clean-up of mercury spills by using aspiration equipment with activated carbon filters;
(e) accounting of waste streams;
(f) separating mercury-contaminated waste from non-contaminated waste;
(g) decontaminating waste contaminated with mercury by using mechanical and physical treatment techniques (e.g. washing, ultrasonic vibration, vacuum cleaners), chemical treatment techniques (e.g. washing with hypochlorite, chlorinated brine or hydrogen peroxide) and/or thermal treatment techniques (e.g. distillation/retorting);
(h) reusing or recycling decontaminated equipment, if possible;
(i) decontaminating the cell room building by cleaning the walls and the floor, followed by coating or painting to give them an impermeable surface if the building is to be reused;
(j) decontaminating or renewing the waste water collection systems in or around the plant;
(k) confining the working area and treating ventilation air when high concentrations of mercury are expected (e.g. for high-pressure washing); treatment techniques for ventilation air include adsorption on iodised or sulphurised activated carbon, scrubbing with hypochlorite or chlorinated brine or adding chlorine to form solid dimercury dichloride;
(l) treating mercury-containing waste water, including laundry wash water arising from the cleaning of protective equipment;
(m) monitoring of mercury in air, water and waste, including for an appropriate time after the finalisation of the decommissioning or conversion;
(viii) if needed, interim storage of metallic mercury on site in storage facilities that are:
(a) well lit and weatherproof;
(b) equipped with a suitable secondary containment capable of retaining 110 % of the liquid volume of any single container;
(c) free of obstructions and debris that may absorb mercury;
(d) equipped with aspiration equipment with activated carbon filters;
(e) periodically inspected, both visually and with mercury-monitoring equipment.
(ix) if needed, transport, potential further treatment and disposal of waste.
BAT 3: In order to reduce emissions of mercury to water during the decommissioning or conversion of mercury cell plants, BAT is to use one or a combination of the techniques given below.
Technique
Description
a
Oxidation and ion exchange
Oxidising agents such as hypochlorite, chlorine or hydrogen peroxide are used to fully convert mercury into its oxidised form, which is subsequently removed by ion-exchange resins.
b
Oxidation and precipitation
Oxidising agents such as hypochlorite, chlorine or hydrogen peroxide are used to fully convert mercury into its oxidised form, which is subsequently removed by precipitation as mercury sulphide, followed by filtration.
c
Reduction and adsorption on activated carbon
Reducing agents such as hydroxylamine are used to fully convert mercury into its elemental form, which is subsequently removed by coalescence and recovery of metallic mercury, followed by adsorption on activated carbon.
The BAT-associated environmental performance level for mercury emissions to water, expressed as Hg, at the outlet of the mercury treatment unit during decommissioning or conversion is 3 – 15 μg/l in 24-hour flow-proportional composite samples taken daily. The associated monitoring is in BAT 7.

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Source: https://www.legislation.gov.uk/eudn/2013/732/annex/division/4/division/2 (the official version)
Page: https://openlegislation.uk/eu-decision-2013-732/annex/division-4/division-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.