Facts of Caustic Soda Industry 95% of world chlorine production is by this industry

1. Standards and Regulations for discharge of liquid effluents and Gaseous Emissions related to chlor alkali industry Shri Paritosh Kumar ,AD & Shri Dinabandhu Gouda, SEE CENTRAL POLLUTION CONTROL BOARD DELHI – 110 032

2. Facts of Caustic Soda Industry 95% of world chlorine production is by this industry The caustic soda industry has attracted particular attention of pollution control authorities world over. The concern is due to the release of mercury into the environment from industrial unit using mercury cell process (a polluting process) for the manufacture of caustic soda. Caustic soda is mainly produced by two electrolytic processes – Mercury Cell and Membrane Cell Technology. Stoichiometrically 1.46 MT salt (100% NaCl) and 0.45 MT water is converted to produce 1 MT of caustic soda, 0.89 MT of Chlorine and 25 kg of Hydrogen.

3. Caustic Soda Demand in India(%)

4. Chlorine is largely used in the synthesis of chlorinated organic compounds. Vinyl chloride monomer (VCM) for the synthesis of polyvinyl chloride (PVC) still remains the driver of chlor-alkali production in the world . • Chlorine is used in 98% of the water treatment plants in the world.

5. Operational Status of Caustic Soda Plant in India • No. of Caustic Soda Plants in Operation : • Mercury + Membrane Cell Plants : 03 • Atul Ltd, Gujarat • Hindustan Paper Corporation, Cacher, Assam • Hindustan Paper Corporation, Nagaon, Assam • Mercury Cell Plants closed : 02 • Hindustan Heavy Chemical Ltd, West Bengal • Solaris Chemtech, Karnataka • Membrane Cell Plants (Exclusively) : 32 • Total : 37 plants

6. Trend of Technology Shift in Chlor-Alkali Sector

7. Energy Consumption in 5 th Generation Membrane cell • The energy consumption in a Membrane cell is of the order of 2,000–2,200 kilowatt-hours per metric tonne of caustic . • Electrode gap plays an important role in cell voltage, as the electrode gap reduces there will be an reduction in electrolyte internal resistance which lowers the cell voltage. This gap cannot be reduced to zero because of the following reasons. Risk of friction between membrane and electrodes • • Special cathode coating required • • Corrosion attack of fine mesh by chlorine gas penetration and stagnation • • Complex and expensive manufacturing

8. Wastewater is generated from • Cell house, • Brine purification section, chlorine • Hhydrogen handling section • HCl manufacturing unit. • Brine sludges are one of the largest waste streams of the chlor-alkali industry. • EFFLUENT TREATMENT SYSTEM ADOPTED IN • CAUSTIC SODA INDUSTRIES IN INDIA • Combination of Treatment Procedures Adopted by Caustic Soda Plants: • ·     Sodium sulphide treatment • · Activated carbon bed filtration • ·        Sand filtration • ·        Ion exchange resin columns

9. SOLID WASTE DISPOSAL • · Brine sludge generation range : 0.03 to 0.05 t/t of NaOH • Hg conc. in brine sludge : 25-235 mg/kg • Observations: • ·Need for vacuum dewatering system/washing of brine mud. • · Need for proper storage of brine mud to avoid entry of rainwater and its spillage. • ·  Need for proper collection and containment of brine mud. • ·  Need for periodic monitoring around the storage/disposal areas for any spillage/percolation of mercury bearing waste.

10. Brine Sludge Area Before Earth Capping

11. Brine Sludge Area After Earth Capping

12. CREP : Chlor-Alkali Industry • All the industries has been complied 12 action points out of 13 action points suggested by CREP. • Mercury emission to environment has been decreased to 0.64 gram/Ton against CREP recommendation 2 gram/ton. • Mercury consumption has been reduced to 14.91 gram/ton against CREP recommendation 50 gram/ton . • All the mercury cell plant has been planned to switch over membrane cell technology by 2012 much ahead of EU target of 2020. 12

13. ENVIRONMENTAL REGULATIONS Wastewater Discharge Standards ParameterConcentration not to exceed ·Total concentration of : 0.01 mg/l mercury in final effluent  ·    Mercury bearing wastewater : 10 Kl/ton of NaOH production generation (Flow)  ·   pH : 5.5 to 9.0 Air Emission Standards

14. Permissible Limit for Mercury/Chlorine in Work Environment as per the Factories Acts, 1948

15. Hazardous Waste Generation from Chlor-alkali Industry as per HW(M ,H,T)Rules , 2008 • Processes (Schedule-I) • Cat:16.1: Mercury bearing sludge • Cat:16.2:Residue sludge and filter cakes • Cat:16.3:Brine sludge containing Mercury • ·SPCB to issue authorisation for collection, storage, treatment & disposal of HW.

16. INTERNATIONAL REGULATIONS (Standards for Hg bearing streams) Stream Limit for mercury EUROCHLOR · Liquid effluent : 0.1 gm/t of Cl2 (~ 0.09 gm/t NaOH) ·    Emission from cell room : 1.7 gm/t of Cl2 (~ 1.55 gm/t NaOH) ·    Products : 0.1 gm/t of Cl2 (~ 0.09 gm/t NaOH) ·    Total Hg release : 2.0 gm/t of Cl2 (~ 1.82 gm/t NaOH) USEPA ·  Liquid effluent : 0.23 gm/t of Cl2 (~ 0.21 gm/t NaOH) – max. for one day : 0.1 gm/t of Cl2 (~ 0.09 gm/t NaOH) – max. avg. for 30 days ·  Sludge : 17 mg/kg ·    Leachate for solid waste : 0.2 mg/l

17. International Regulations Contd. …. • Stream Limit for mercury • SWEDEN • ·  Liquid effluent : 0.1 gm/t of Cl2 (~ 0.09 gm/t NaOH) • · Ventilation air from cell room : 1.0 gm/t of Cl2 (~ 0.909 gm/t NaOH) • · H2 gas : 0.5 gm/t of Cl2 (~ 0.45 gm/t NaOH) • WHO • Conc. in Cell Room : 0.05 mg/m3 • China • Wastewater : 0.01 mg/l • Air : 0.012 mg/m3

18. JAPAN Two types of requirements for effluent control in Japan: ·  Regulations or standards issued by the environmental agencies; and · Guidelines issued by the Ministry of Interior, Trade and Industry (MITI). Standards for industrial discharges of mercury: · WW discharge standards for mercury : 5.0 ppb (0.005 mg/l) · Standards for water quality : 0.5 ppb (0.0005 mg/l) Guidelines issued by MITI to all Chlor alkali plants: · All process water contaminated with mercury must receive full recycling. · Mercury cell must be phased out (5 yrs. from recycling date).

19. Realising problem associated with mercury based caustic soda plant, Govt. of India : • Issued notification under EPA 1986 for liquid effluent and gaseous emission standards for controlling mercury from stationary sources; and • Recommended commissioning of new plants and expansion of Hg cell based plants not to be allowed with effect from 1986 and adopt the cleaner production process (i.e. membrane cell process). The production of caustic soda by Hg cell plant since then gradually declined.

20. Status of Caustic soda Plant

21. Status of Caustic soda Plant

22. Status of Caustic soda Plant

23. Status of Caustic soda Plant

24. Status of Caustic soda Plant

25. All the Caustic Soda Plant should : • Not by-pass any control system. • Maintain operational parameter during start-up & shut down, like Redox meter in Hypo tower . • Maintain desired strength of caustic concentration in HT. • Use of good quality salt • Provide continuous Cl2 and HCl monitoring system at all strategic location, stacks, work-zone areas and its recording on strip chart in control room.

26. Issues of caustic soda industry Issue of Brine Sludge generated from Membrane cell plants in the light of Hazardous Waste(M,H,T) Rules,2008 Review of effluent and emission standards Applicability of continuous effluent and emission monitoring system

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