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
Facts of Caustic Soda Industry
1.
95% of world chlorine production is by this industry
2.
The caustic soda industry has attracted particular
attention of pollution control authorities world over.
3.
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.
4.
Caustic soda is mainly produced by two electrolytic
processes – Mercury Cell and Membrane Cell
Technology.
5.
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.
Caustic Soda Demand in India(%)
5. 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 .
6. Chlorine is used in 98% of the water treatment plants in the
world.
Operational Status of Caustic Soda Plant in
India
No. of Caustic Soda Plants in Operation :
 Mercury + Membrane Cell Plants
:
(i) Atul Ltd, Gujarat
(ii) Hindustan Paper Corporation, Cacher, Assam
(iii) Hindustan Paper Corporation, Nagaon, Assam
 Mercury Cell Plants closed
:
(i) Hindustan Heavy Chemical Ltd, West Bengal
(ii) Solaris Chemtech, Karnataka
 Membrane Cell Plants (Exclusively)
:
03
02
32
Total : 37 plants
Process
Total
Installed Capacity
(Lakh MTA)
27.94
Production
in 2012-13
(Lakh MTA )
21.61
No of Mercury & Membrane cell
35
30
25
20
15
No. of Mercury Cell
10
Units
5
No. of Membrane
0
Cell Units
Year
Trend of Technology Shift in Chlor-Alkali Sector
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
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
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.
Brine Sludge Area Before Earth Capping
Brine Sludge Area After Earth Capping
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
ENVIRONMENTAL REGULATIONS
Wastewater Discharge Standards
Parameter
Concentration not to exceed

Total concentration of
mercury in final effluent
:
0.01 mg/l
·
Mercury bearing wastewater
generation (Flow)
:
10 Kl/ton of NaOH production
·
pH
:
5.5 to 9.0
Air Emission Standards
Pollutants
Emission limits (mg/Nm3)
Mercury process
Mercury (H2 gas holder)
0.2
All process
Chlorine (Hypo tower)
15
All process
Hydrochloric vapor/mist
(Hydrochloric acid plant)
35
Process
Permissible Limit for Mercury/Chlorine in Work Environment
as per the Factories Acts, 1948
Substance
Permissible limits for Mercury &
Chlorine
Work zone conc. in mg/m3 (8 hrs. timeweighted avg.)
• Mercury
• Chlorine
• HCl mist
0.05
3.00
7.00
Hazardous Waste Generation from Chlor-alkali
Industry
as per HW(M ,H,T)Rules , 2008


Processes (Schedule-I)
o
Cat:16.1: Mercury bearing sludge
o
Cat:16.2:Residue sludge and filter cakes
o
Cat:16.3:Brine sludge containing Mercury
SPCB to issue authorisation for collection, storage, treatment &
disposal of HW.
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
International Regulations Contd. ….
Stream
Limit for mercury
SWEDEN

Liquid effluent

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)
:
0.05 mg/m3
:
0.1 gm/t of Cl2 (~ 0.09 gm/t NaOH)
WHO

Conc. in Cell Room
China
Wastewater
:
Air
:
0.01 mg/l
0.012 mg/m3
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).
Realising problem associated with mercury based
caustic soda plant, Govt. of India :
i.
Issued notification under EPA 1986 for liquid
effluent and gaseous emission standards for
controlling mercury from stationary sources;
and
ii.
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.
Name of Industry
Production Date of Complying/
capacity
Inspect Non complying
ion
Remarks
Rayalaseema
Alkaliies and
Allied
Chemicals,
Kurnool,
Andhra Pradesh
Caustic
soda 520 TPD
24.11. Partially
2009
complying –PM126 > 115
mg/Nm3
HCl-7.5<35
Cl2-9.5<15.0
Letter to APPCB
to direct
industry to take
necessary action
SIEL chemical
complex
,Patiala,
Punjab
Caustic
soda 250 TPD
25.06. complying
2013
Hindustan
Heavy
Chemicals Ltd,
West Bengal
Caustic
soda-42
TPD
19.11. Not complying.
2009
Mercury
released to
environment is
5 gm/ton >2
gm/ton
CPCB issued
direction u/s 18
(1) b to WBPCB
and
Closure notice
issued by
WBPCB
Name of
Industry
Productio Date of
n capacity Inspection
Complying/
Non
complying
Remarks
Aditya Birla
Chemical Ltd,
Renukoot ,UP
Caustic
soda 220 TPD
21.04.2010 complying
Travancor
Cochin
Chemicals
,Cochin,
Kerala
Caustic
soda 175 TPD
21.09.2009 Non
complying
Cl2- 124>15
mg/Nm3
HCl-339 >35
mg/Nm3
RIL
,Dahej,Gujarat
Caustic
17.11.2009 Complying
soda-450
TPD
-
Shriram
Chemical and
Fertiliser ,Kota,
Rajasthan
Caustic
17.09.2012 complying
soda-325
TPD
-
CPCB issued
direction u/s
18 (1) b to
Kerala Board
Name of
Industry
Producti
on
capacity
Date of
Inspection
Complying/
Non complying
Remarks
Grasim
Industries
Ltd,Nagda,
MP
Caustic
soda 750
TPD
22.02.20
12
Partially
complying
Letter to the unit
to install
continuous
monitoring
system
Gujarat
Alkali and
Chemical
Ltd,
Vadodara,
Gujarat
Caustic
soda 500
TPD
18.02.20
11
Non complying
Chloride 1873
mg/l>600
mg/l and
incinerator is
operating
without APCD
CPCB issued
direction u/s 18
(1) b to Gujarat
PCB and GPCB
issued direction
u/s 31 A and 33
A
Lords Chlor
Alkali, Alwar
,Rajasthan
Caustic
soda30 TPD
17.12.20
10
Complying
-
Name of
Industry
Producti Date
Complying/
on
of
Non complying
capacity Inspec
tion
Remarks
Tamilnadu
Petroproducts
,Manali,
Chennai,Tamil
Nadu
Caustic
soda 225
TPD
16.12. Non complying
2013 Ph-11.4>9.0
SS-302>30 mg/l
Oil and Grease
121 >10 mg/l
Cl2-41>15
mg/Nm3
Direction u/s 5
issued to the unit
by CPCB
DCW
,Thoothkudi,
Tamil Nadu
Caustic
Soda280
TPD
22.04. Non complying
2008 Ph-2.4<5.5
Hg-0.02>0.01
mg/l
CPCB issued
direction u/s 18
(1) b to
Tamilnadu PCB
and TNPCB issued
direction u/s and
33 A
Status of Caustic soda Plant
Name of
Product Date of
Industry10.04 ion
Inspection
.2013
capacity
Complying
/
Non
complying
Remarks
Durgapur
Chemicals
Ltd,
Durgapur,
West Bengal
Caustic
soda100
TPD
18.01.2011 complying
-
Aitya Birla
Chemicals
Ltd, Palamau,
Jharkhand
Caustic
soda 550
TPD
25.09.2013 complying
Letter to the unit
to connect CPCB
server
Jayshree
chemicals
Ltd, Ganjam,
Odisha
Caustic
soda 150
TPD
10.04.2013 complying
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.
•
•
•
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
emission monitoring system
effluent
and
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