EXPERIENCES WITH ZLD AND

WAY FORWARD

I. Sajid Hussain, Chief Operating Officer

Tamilnadu Water Investment Company Limited.

www.twic.co.in

sajidhussain1@twic.co.in

German Water Partnership -Day 2017

German Solutions to Indian Challenges20th Sept 2017

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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

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SECTION A: CONCEPT OF ZLD

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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.

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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.

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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.

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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

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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.

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Section B- Brief experience with ZLD in

Textile Tannery CETPs and Pulp & Paper

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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

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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

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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

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O & M of Tirupur Textile CETP at Tirupur

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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.

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SECTION C: RECENT ADVANCES IN

ZLD TECHNOLOGY

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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.

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Project Concept with Captive Power with cogen-Jajmau Tannery CETP, Kanpur

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Web based on-line monitoring system

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Project Concept with Solar thermal Heating with Membrane Distillation- Sree Bhavani, Textile CETP, Erode

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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)

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SECTION D: APPROACH TO ZLD

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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.

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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.

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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.

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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

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