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EXPERIENCES WITH ZLD AND
WAY FORWARD
I. Sajid Hussain, Chief Operating Officer
Tamilnadu Water Investment Company Limited.
www.twic.co.in
German Water Partnership -Day 2017
German Solutions to Indian Challenges20th Sept 2017
1
CONTENTS
Section A : Concept of ZLD
Section B : Brief Experience with ZLD in Textile
Dyeing and tannery CETPs
Section C: Recent advances in ZLD technologies
Section D : Approach to ZLD
Section E : Conclusions
2
SECTION A: CONCEPT OF ZLD
3
Concept of ZLD
ZLD – meaning zero discharge of wastewater from Industries.
A ZLD system involves a range of advanced wastewater
treatment technologies to recycle, recovery and re-use of the
‘treated’ wastewater and thereby ensure there is no discharge
of wastewater to the environment.
A typical ZLD is an hybrid system comprising of the following
components:
Pre-treatment (Primary Secondary and Tertiary treatment)
Reverse Osmosis
Evaporator & Crystallizer
Land application & Deep well disposal of treated effluent is not
permitted (Tamilnadu).
ZLD based on directions from SPCB.
No national level standards formulated for ZLD as yet.4
Need for ZLD…1
MAIN MOTIVATORS- Water Scarcity, water economics, regulatory pressure.
Water Scarcity
Several states in India including Tamilnadu are waterstressed.54% of India faces High to extremely high waterstress and 54% of ground water wells are decreasing– WRI.
No ground water for irrigation by 2025 in Delhi, Rajasthanand Haryana. UNESCO Report says India holds the number 1spot for the annual Ground water extraction at 251 cu.Km asagainst 112 cu.km in China and USA, a distant second.
Competing demands for water from agriculture and domesticuse has limited industrial growth.
5
Need for ZLD…2
TN has taken a lead on ZLD due to absence of fully flowing Perennial River. Most rivers originate from neighboring states and water sharing is enmeshed in disputes.
With ZLD the industry can be located in barren and low water potential or quality areas.
Industrial Production is not affected even during drought years.
6
Need for ZLD …3Pollution issues & Regulatory pressure..1
Industrial Effluents with high salinity/TDS- pollutingindustries such as Pharma, Pulp& Paper, Tanneries, TextileDyeing, Chemicals , Power Plants etc.
The TDS content is well above the statutory limit of 2100mg/l.
Draft ZLD notification dropped by MoEF but the revisednotification speaks of exhausting recycling and reuseoptions.
Conventional ‘Physico-chemical-biological’ treatment doesnot remove salinity in the treated effluent.
Discharge of saline but treated wastewater pollutes groundand surface waters.
7
Need for ZLD …4Pollution issues & Regulatory pressure..2
189 CETPs in the country and non-compliance is a major issue. Samewith STPs. Individual ETPs ?. No incentives for treatment for CETP/STP/ETP. Recovery and reuse of water is seen to be major incentive.
Several landmark pollution cases and court battles -Vellore andTirupur court cases.
Most rivers in the country are polluted.
ZLD is easy to monitor for compliance, any discharge from thefactory 24 x7 means non-compliant. No need for lay man tocomplain, inspect, collect samples or test in lab and check withstandards.
NGT actively perusing pollution cases and prohibiting discharge torivers.
Poor experience with marine discharge and effluent channelspolluting enroute and the sea, affecting coastal communities are alsoknown. 8
Need for ZLD …5Water Economics
Indiscriminate withdrawal of ground water ‘free of cost’ inmost parts of the country. Water priced low in many parts.
However, cost of fresh water for Industry is rising due toscarcity, Tirupur it is Rs.78/m3, Vellore –Rs.50/m3, Pali- Rs.100/m3.
Location of industries in ‘Inland areas’ therefore marinedischarge may not feasible. Cost of marine dischargeincreases with distance from shore and if the cost of freshwater is high (say Rs. 50/m3) then beyond 20 KM, ZLDbecomes competitive.
Other states such as Andhra, Telangana, Rajasthan, andKarnataka are also now enforcing ZLD in many cases.
Internationally ZLD is gaining prominence – China,Bangladesh, USA, Germany etc. 9
ZLD results in generation of hazardous solid wastes creating
disposal challenges- need to think of Zero Waste Disposal (ZWD)
Plants. Generate products/ by-products out of the waste.
Economic viability- cost and availability of water, regulatory pressure
are the real driving force.
High Carbon foot print- is this environmentally sustainable?
High Operating cost and financial impact on the industry and its
Regional/ National/Global competitiveness.
Technology shortcomings.
Barriers / Challenges in ZLD
10
Benefits of ZLD
Installing ZLD technology is beneficial for the plant’s water
management; encouraging close monitoring of water
usage, avoiding wastage and promotes recycling by
conventional and far less expensive solutions.
High operating costs can be justified by high recovery of
water (>90-95%) and recovering of several by products
from the salt.
A more sustainable growth of the industry while meeting
most stringent regulatory norms.
Reduction in water demand from the Industry, frees up
water for Agriculture and Domestic demands.
No loss in production even during drought years.
11
Section B- Brief experience with ZLD in
Textile Tannery CETPs and Pulp & Paper
12
Textile Dyeing CETPs in Tirupur 18 CETPs established based on ZLD.
Most CETPs are based in treated brine reuse technology and Sodium Sulfate salt crystallization and reuse.
Design Capacities range from 1.5 MLD to 12 MLD.
Currently operating at 30 -90% capacity (average 50%).
95-98% recovery of water and 80% recovery of salt.
Operating costs at Rs. 200-250 Rs/m3. Expected to go down to Rs. 180/m3 with further project modifications.
Net operating cost after salt and water recovery at ~ Rs. 100-150 per m3.
Financial Impact: 5 to 6% on production cost. Rs. 4 to Rs. 5 per Kg of dyed fabric.
Independent O&M agency for all CETPs, PMA agency is operator in most cases. 13
*90-95%
110-120% Recovered water for
reuse
Well water / River
water for Top up
Chemical sludge (Lime sludge) for Brick
Manufacturing /Co-Processing in Cement
Industry
Textile Dyeing Units ZLD CETP
Raw effluent
Treated Brine for resue (Mixed salt )
Bio sludge for manufacturing briquettes after
blending with Agro waste and usage as fuel in
Recovered sodium sulphate salt for top-up /
sale
Tirupur Dyeing ZLD CETP Project Concept
14
Storage and Homogenization tank
Biological Oxidation Tank
Secondary
Clarifier
Chlorine contact Tank
Quartz Filter
Ultrafiltration system
Decolourant Resin Filter
Softener Filter
Reverse Osmosis
Raw effluent from member dyeing
units
Resin RegenerateLiquor
Reactor Clarifier
Sludge Thicken
er
Filter Press Lime Sludge to
Cement Industries
Sludge Thicken
er
Filter Press
Bio sludge cake for disposal
Excess sludge
MVR
MEE
Adiabatic Chiller
Pusher Centrifuge
Recovered Glauber’s salt
(Na2SO4.10 H2O) for reuse
Recovered water for reuse (RO Permeate
& Evaporator condensate)
Process Schematic for a typical ZLD based Textile CETP
Brine Treatment system
Brine for reuse at member units 100-150gpl
Major quantity
Solar Evaporation Pan
Waste salt for disposal
ML
Bio
ma
ss
Re
cir
cu
lati
on
Ba
ck
wa
sh
/C
IP t
o
SH
T
Raw effluent lineReject line
Pretreatment UnitsTertiary Treatment units
Reject Management systemResin regenerate treatment
system
Legend
15
Pretreatment Biological Treatment Reverse Osmosis
Untreated & Treated
Effluent
Lab trails using
RO brine
R.O reject
– before
treatment
R.O reject
– after
treatment
Tirupur Textile Effluent Management
Project, Tirupur.. 3
16
O & M of Tirupur Textile CETP at Tirupur
17
2. Tannery CETPs in Vellore
12 CETPs established, 10 based on ZLD,1 partial ZLD and 1 very small CETP (500 m3- SF-F) based on irrigation on trial basis.
Most CETPs are based Evaporator crystallization and storage of waste salt.
Design Capacities range from 0.5 MLD to 4.5 MLD.
Currently operating at 30 -75% capacity.
Operating costs at Rs. 460 to 480 per m3.
Net operating cost after water recovery at ~ Rs. 390-410 per m3.
Financial Impact: 8 to 10% on production cost. Rs. 5 to Rs. 6 per sq.ft of finished
leather. Rs. 15-18 per pair of shoes.
Membrane Bioreactor (MBR) Vaniyambadi
RO plant at Ambur 18
3. Technical and Commercial Feasibility for
Development, Financing, Implementation and
Operation of Zero Liquid Discharge Effluent
Project for Pulp & Paper Major
Aeration Tank Ultra Filtration
Nano Filtration Reverse Osmosis
>95% recovery of water. Recovery of Sodium Sulphate and Sodium Choride Salts.
19
SECTION C: RECENT ADVANCES IN
ZLD TECHNOLOGY
20
RECENT ADVANCES IN ZLD TECHNOLOGIES
Electro-oxidation for colour & recalcitrant COD removal as alternative to Decolourant Resin Filters or chemical precipitation.
High Pressure RO (both SWRO and HPPTRO) upto 200 bar feed pressures to reduce volume of rejects for thermal evaporation.
Need for Captive Power with cogen
Membrane Distillation as alternative to MEE. Possibility of use of hot water (solar) instead of steam. Thereby reducing carbon foot print.
Forward Osmosis for brine management at very concentrations at reduced energy requirements.
TWIC has developed a near Zero Waste Salt Technology.
O&M costs will substantially reduce with these technologies and is expected to go down further in the near future.
21
Project Concept with Captive Power with cogen-Jajmau Tannery CETP, Kanpur
22
Web based on-line monitoring system
23
Project Concept with Solar thermal Heating with Membrane Distillation- Sree Bhavani, Textile CETP, Erode
24
Ho
t W
ater
@ 8
4OC
*90-95%
110-120%
* Net recovery after internal consumption in cooling tower and for solar thermal system
Recovered Sodium Sulphate for top-up or sale/
Textile Dyeing Units ZLD CETP
Raw effluent
Treated Brine for resue (Sodium chloride )
Chemical sludge for brick manufacturing or
co-processing in cement industry
Biolsudge for making briquettes and
blending with agro-waste as boiler fuelR
eco
ver
ed w
ater
for
top u
p
Recovered water for
reuse
Solar Thermal Heating
System
Well water / River
water for Top up
Low Carbon footprint of ZLD-ZWS technology as compared with Conventional treatment & discharge plants and
existing ZLD technologies
Note: For Southern Grid power, weighted average emission factor has been taken as 1 MWH = 0.81 Ton of CO2 as per CEA report for FY 2013 -14
0%
95% 95% 95%
0%
70% 70%
100%CO2 Emission (tons/
annum), 17000
CO2 Emission (tons/ annum), 32000
CO2 Emission (tons/ annum), 39000
CO2 Emission (tons/ annum), 13500
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
0%
20%
40%
60%
80%
100%
120%
ConventionalTreatment for
discharge to River/ Sea(Primary + SecondaryTeatment Only + grid
power)
Existing ZLD(MEE + Bolier+ grid
power)
Existing ZLD technology(MEE+ CPP cogen)
ZLD-ZWS Technology(Membrane Distillation+ Solar Thermal + grid
power)
CO
2 e
mis
sio
n in
to
ns/
an
nu
m
Re
sou
rce
(W
ate
r &
Sal
t) R
eco
very
Water Recovery Salt Recovery CO2 Emission (tons/ annum)
25
SECTION D: APPROACH TO ZLD
26
Approach to ZLD.. 1
• Technology Need for extensive piloting before implementation to demonstrated Techno-
commercial feasibility.
One Size does not fit all:Need to remember “not all Textile dyeing effluent aresame” or “not all Tannery effluent are same” or “not all paper industries aresame” or “not all ZLD are same”.
Since almost no EPC company provides ‘in-house’ all components of ZLD,there is an extensive need for integrating the complete process components toavoid problems. Therefore the Consultant should assure process performanceguarantees.
Not just water balance but material balance for several critical parameters (notjust TDS) a must for correct process design.
Internal recirculation:Quality and quantity of backwash/ regeneration/ CIP/cleaning on the entire treatment process to be carefully accounted for inprocess design.
System design should be based on high ‘Reliability Index’.
High Process Flexibility to be built in for various components to handlevariations in effluent quality/ individual component performance. Design shouldbe based on multiple process streams including standby and downtime.
27
Approach to ZLD…2
Must focus on reduction of brine concentrate to reduce the need for
evaporation and crystallization.
Higher recovery in R.O possible subject to osmotic pressure limitations,
but with elimination of Hardness, silica, foulants. High Pressure R.O
systems available and are cost effective such as DTRO (90 – 160 bar).
Think “Zero Waste Discharge” to achieve Zero Liquid Discharge”.
Focus on salt recovery and reuse, salt separation and reduced sludge
generation.
28
Approach to ZLD…3
• O&M
Need for independent (for CETPs) and Professional O&M.
Most CETPs /ETPs are poorly managed and there is
complete lack of certified ETP operator courses and dearth
of well trained manpower.
Expenditure on O&M is an issue.
EPC contractors fail to deliver on performance.
The consultant/ designer can be held responsible for
process performance through O&M.
29
NEED FOR POLICY FRAMEWORK…1
There is a need for a comprehensive policy and standards
for ZLD.
Need for a higher grant towards capex as most such
polluting industries fall under the Tiny and SME category.
Issues with Regional/ National competitiveness due higher
operating expenses due to ZLD.
Polluting industries such as Tannery and Textiles are
essentially based on “Job Work”. Therefore there is an
issue with transfer of higher costs to the “buyer”.
The ultimate customer may be able to bear the additional
cost due to ZLD. E.g. Rs. 20 on a pair of shoes. 30
NEED FOR POLICY FRAMEWORK…2
A Environmental cess on the finished product out of a cluster can be used to reimburse ZLD costs of a CETP/ IETP.
or an additional duty drawback on exports can be some policy decisions.
A green labelling scheme can be initiated, which could be leveraged for better export prices for the goods, thereby offsetting the higher input costs.
e.g. Gold rating given to a ZLD Tannery CETPs in TN by
LWG, UK, leading to a higher market price.
However, all these are only suggestions and needs to be finalized in consultation with all the stakeholders. 31
Section E: Conclusions
ZLD is a Technological Challenge, and the focus must
be on Zero Waste Disposal (ZWD).
Extensive research and piloting necessary for every
single case for Technology selection and financial
viability.
Brine Concentration, Evaporation and Crystallization and
disposal still a major issue. Focus must be on recovery
and reuse of salts.
Water Scarcity, Water economics and regulatory
pressure are the main drivers of ZLD and will determine
financial viability.32
Tirupur Video-https://www.youtube.com/watch?v=42jbPRb7xvg
33
34