Technical Challenges of Zero Discharge systems in Tirupur

   What is Zero Liquid 

Discharge Systems

Why Recycle Water? 

•  To cater to increased water demand due to 

• Urbanization, industrialization 

• Reduced rainfalls and depletion of natural resources

•  Prevention of water pollution 

•  Social obligation 

• Disposal of waste water spoil natural water bodies and offer health 

hazards 

•  It saves 

•  Fresh water consumption 

• Water Treatment costs 

• Boiler and Cooling Tower blow-down losses 

• Loss of production & revenue due to forced closures by pollution control board 

•  Reduces public liability costs 

•  Promotes public goodwill, brand image & recognition in society 

•  Employee Motivation 

•  Business growth 

•  Improves productivity

Limitations of Conventional Water Recycling Plants 

•  Inferior, unproven, unreliable technologies 

•  Poor revenue to capital ratios 

•  Weaknesses in economic viability 

•  Energy Intensive 

•  High running cost

The following Industries are needed in Zero Liquid Discharge Systems 

•  Pharmaceuticals Industry 

•  Polymer Industry 

•  Automobile Industry 

•  Distilleries & Breweries. 

•  Pesticides & Insecticides. 

•  Dyestuff Industry. 

•  Textile & Dyeing Plants. 

•  Paper & Pulp Industry. 

•  Food Processing Industry. 

•  Meat Processing Plants. 

•  Fisheries & Fish Processing Units. 

•  Beverage Bottling Plants. 

•  Dairy Industry. 

•  Chemical Industries. 

•  Paints & Pigments Industry. 

•  Agrochemicals & Fertilizer Plants. 

•  Solvent Extraction and Edible Oil Refining Industry.

•  Ink & Varnish Industry. 

•  Hotels, Laundries and Hospitals. 

•  Sugar Industry 

•  Any other Industry generating wastewater.

Why need zero discharge system need in TIRUPUR

Ground water quality in Tirupur has been significantly affected due to the discharge of largequantities of textile dye effluent into the Noyyal river - a tributary of Cauvery. This has alsoresulted in contamination of Orathupalayam Dam and caused serious environmental degradationin the downstream areas of Erode and Karur.

At present, around 800 individual dying units and, eight Common Effluent Treatment Plants(CETP) are existing in Tirupur which processes textile dye effluent. At one of the CETPs, theManickapurampudur Common Effluent Treatment Plant (MPCETP), our organisation is engagedin the research & development work for the treatment of textile dye effluent for the past 3 years.

The treated effluent at this CETP was regularly collected and analysed for pH, total suspendedsolids, TDS, COD, BOD, sodium, chloride, sulphate, sulphide, and trace metals (Cu, Zn, Pb, Ni,Cd). The results showed that the treated effluent obeyed the effluent discharge norms of the TamilNadu Pollution Control Board, except TDS.In order to reduce effluent load to the Noyyal river, attempts were made at this CETP toevaporate the effluent using solar energy. 

Though significant progress has been achieved in thisdirection, due to the concerns on air pollution, this method was abandoned in continuation of these efforts to achieve zero-discharge, trials were conducted for implementingreverse osmosis system. Following these trials, this CETP is in the process of implementingreverse osmosis for water reuse, nano-filtration for salt recovery and, Multiple Effect Evaporatorand solar bed for reject management, and wind mill for power generation.

Though Multiple Effect Evaporator can be successfully utilised for reject management, itconsumes large quantity of wood as a fuel. This will enhance wood demand and CO2 emissioninto the atmosphere. 

In order to reduce wood requirement and CO2 emission, it is planned toexpand the already existing plantations grown by this CETP using the treated effluent.We conclude our paper with a note on emerging technologies for textile dyeing, which couldtotally eliminate the need of water for dying textile fabrics, thereby totally eliminatingenvironmental degradation

The following zero discharge water systems methods followed in Tirupur dyeing units

Technical Challenges of Zero Discharge systems in Tirupur CETPs Technical Challenges of Zero Discharge systems in Tirupur CETPs

1. The final RO rejects are normally in the range of 15% - 20%. But to be on the safer side we have to consider 20% rejection for deciding the Capacity of Multiple Evaporators.
2. From Multiple Evaporators we have to achieve a TDS concentration of 2,40,000 ppm             ( 240 gpl) for sending it to Glauber’s Salt Crystalliser (for Glauber’s Salt recovery)
3. For Mixed salt recovery also we need still a higher concentration to send it to Salt Settler.
4. The present MVR Evaporators installed in most of the  CETPs can not achieve this much concentration due to its design limitation. Polymeric heat exchangers in MVR may get blocked due to scaling because of very narrow gaps. With this MVR, crossing more than a TDS concentration of 60,000 ppm itself may be difficult.
5. If the feed (RO reject) to MVR is taken as 30,000 ppm and the out put as 60,000 ppm then only 50% of the reject can be evaporated. That too we are not sure of the performance.
6. The biggest problem in the CETPs is the installation of MVR Evaporator which will not do the work of normal Multiple Evaporators.
7. We need separate Multiple Evaporators to concentrate 60,000 ppm MVR output to the required 2,40,000 ppm.
8. Some CETPs have installed 100% Biological Treatment scheme which does not fully remove colour. If coloured reject is sent to Multiple Evaporator, then the recovered Salt also be coloured which can not be reused. Hence they use a Resin Filter to remove colour. But the Resin Filter needs back-wash and regeneration with basic chemicals, generating s huge volume of back-wash. If this back-wash (PT effluent) is sent to Effluent collection sump, then the colour and pollutants get concentration and puts more load on Resin Filters. Therefore the Resin Filter back-wash (PT effluent) has to be separately handled in Multiple Evaporators.
9. In order to prevent RO scaling, some CETP have installed Softening plants before RO to remove hardness. The regenerated solution has to be separately handled in Multiple Evaporators.
10. All CETPs have to definitely recover reusable Sodium Sulphate or Sodium Chloride. If the recovered salt is not reusable then hundreds of tons non-usable salt will have to be disposed off as solid waste in Secured Land Fill. This is practically not possible. Otherwise some other Industry has to buy this to be used in their process if possible. 
11. Many CETPs do not have adequate land for Solar Evaporation Ponds. Sending all the final Liquid Reject (after salt recovery) to Solar Evaporation Ponds is not possible. Hence the installed Multiple Evaporator or a separate one has to be used for handling the Final Liquid Reject from salt Recovery.
12. Glauber’s Salt ( Sodium Sulphate decahydrate) has a melting point of  32.4 degree C. In our climate this will easily melt and hence CETPs can not easily distribute it to its members. Therefore we have to convert the Glauber’s salt (Sodium Sulphate decahydrate) into Anhydrous Sodium Sulphate and to be sent to its members for reuse.
13. If the CETPs recover Sodium Chloride as Mixed Salt, it should have reusable purity.
14. Any ZLD design without Salt reuse will generate huge volumes of Solid Waste whose disposal will be a very tough task.
15. The capacity of Multiple Evaporators has to meet the requirements of Concentration for Salt recovery and also for Final Liquid Reject management.
16. One CETP is installed only for bleaching effluent. Some use Calcium Bleaching powder and this will give a lot of Calcium hardness in the effluent. Ultimately this will create scaling problem in the Multiple Evaporators.
17. Scaling problem in Multiple Evaporator is universal and hence suitable Multiple Evaporators have to be designed and selected which will have less scaling tendency.
18. There is no single perfect treatment method for Effluent Treatment before R.O..  Every method has got its own merits and demerits. Only a combination of treatment methods has to be selected.
1. Physico-chemical primary treatment is very efficient. But it produces lot of Sludge.
2. Only 100% Biological method is not efficient in colour removal. Physico-chemical treatment is needed before or after this.
3. Chlorination is very efficient is colour removal. But this is very dangerous to handle and it also produces undesirable Chloramines.
4. Ozonation partly removes colour. But Ozone generators very costly, power hungry and requires lot of maintenance.
5. Electro-oxidation and Electro-coagulation is also efficient but the maintenance is very difficult.

10 MLD Zero Discharge System by Ion Exchange for ACETP, Tirupur
Tirupur is a hosiery and export centre located about 450 km from Chennai in Tamil Nadu. Around 80 bleaching and dyeing units form part of the Angeripalayam common effluent treatment plant (ACETP) project; These dyeing units consume large volumes of water which they were purchasing at around Rs 50 to 60 per cu m through tankers. During the dyeing process, 10 MLD (million litres per day) of waste water with high TDS, organics and colour is generated by the individual units of the ACETP. This ACETP and other CETPs had been set up to treat the effluent discharged from these units. The partially treated effluent, without reduction of total dissolved solids (TDS), was being discharged by the various Tirupur dyeing units into the Noyyal River, polluting the water and making it unfit for agriculture and domestic use. Discharge of the high TDS effluent into the river and its subsequent percolation into the ground water system had also affected the ground water quality. In view of this, all textile units were directed by the Chennai High Court to implement zero liquid discharge. Ion Exchange carried out extensive piloting to identify the right solution to overcome the problem faced by the units in Tirupur. Various combinations of technologies including biological, chemical, resin and membrane based systems were tried out. Based on this, a 0.5 MLD plant was built to gather further operating data after which the scheme for the 10 MLD zero discharge system was developed and constructed. The main treatment scheme comprises the flat sheet membrane bio-reactor and two stage reverse osmosis for effluent recycle followed by, for the RO reject stream, silica removal, sand filtration and nano filtration for zero discharge. The RO permeate has TDS of <6200 ppm, COD of <5, with nil BOD, suspended solids and colour. Benefits of the Zero Discharge System Apart from satisfying the High Court mandate of zero liquid discharge, the ACETP/individual units derive a host of benefits: [] More than 82% of the feed water (10 MLD capacity) is obtained as RO permeate of much better quality than available raw water. This improves the quality of the dyeing. [] 11% of the feed water, obtained as pure brine solution from nano filtration, will be used effectively for dyeing. This means around 93% of effluent is recycled and reused by the dyeing industries. [] The operating cost of the project is around Rs 40 - 45/m3, much less than the fresh water cost of about Rs 50 - 60/m3, - a huge saving of costs on purchasing water. [] A much smaller footprint, as it uses the membrane bio-reactor instead of a conventional biological system. [] Sludge production is vastly minimised as the physico-chemical process is avoided. Zero Liquid Discharge Eliminate Liquid Discharge,  Recover Valuable Process Water by GE Water & Process Technologies

Complying with stringent wastewater treatment regulations 
and reducing water usage are critical considerations in industry
today. Numerous environmental regulations, rigorous permitting
processes, and lack of water availability, among other factors, 
are driving many industrial facilities to implement zero liquid
discharge (ZLD) systems as a solution.

GE’s ZLD systems eliminate liquid waste streams from your plant
and produce high purity water for reuse. In many cases, your
plant’s water consumption can be reduced by up to 90 percent—
saving money and helping to protect the environment. You may
even be able to capture valuable by-products and sell them to
offset your costs.
With more than 35 years of experience in the design, delivery,
commissioning and service of ZLD systems, GE provides a
comprehensive portfolio of technologies for ZLD applications,
including brine concentrators, evaporators, and crystallizers.
Proven performers and
highly reliable, GE ZLD
systems offer 95%
availability and are up to 
30 percent more energy
efficient than conventional
designs. These technologies
can often be combined 
with other GE equipment,
such as ultrafiltration (UF),
reverse osmosis (RO),
electrodeionization (EDI)
and ion exchange to provide the optimal solution. Our specialists
can tailor a system to fit your wastewater characteristics, flow
rates, and end-product requirements.
As the pioneer of thermal ZLD systems, GE is continually developing
new thermal solutions that respond to changing market needs. Our
extensive global experience can help you tackle the challenges of
stringent discharge regulations, process optimization and effective
water and wastewater management. GE ZLD systems can help
simplify the permitting process, thereby accelerating your plant
development schedule and alleviating environmental concerns.
Our strong vendor relationships enable strategic sourcing
agreements and, in turn, offer you the most competitive pricing
available. With multiple contracting methods, a variety of system
options, and highly experienced design and delivery teams, GE 
can custom-design a system for your maximum benefit.
Robust Solutions 
for Demanding Applications
GE’s large installed base of robust systems is proven to perform
across a broad range of applications, including: 
• Power 
• Synthetic fuels
• Primary metals processing 
• Microelectronics
• Chemical
• Pulp and paper
• Coal mining
• Battery manufacturing
• PVC manufacturing
• Uranium mining
• Petroleum and petrochemical
• Oil refining
• SAGD heavy oil recovery
• Cogeneration
• Fertilizer
• Solid waste (leachate and secondary sewage effluent)
• Coal liquefaction
• Ethanol production


Brine Concentrator
GE brine concentrators recover up to 95% of industrial wastewater
as high purity distillate. This can be used for boiler makeup, NOx
control, cooling tower makeup and process use. The remaining 
five percent is a slurry concentrate that may be sent to a small
solar pond, reduced to dry solids in a crystallizer or spray dryer, 
or used for ash wetting.
Brine Concentrators Can Recycle:
• Cooling tower blowdown
• Oil and gas field
produced water
• Demineralizer waste
• Reverse osmosis reject
• Electrodialysis reject
• FGD wastewaters
• Boiler blowdown
• Softener waste
• Plant drains
• Salty effluents
• Mine drainage
• Landfill leachate
Benefits: 
• Corrosion resistant titanium—High grade construction
materials mean GE brine concentrators will last for decades
and provide reliable operation. 
• Scale control—Proprietary seeded slurry technology controls
scale, often limiting cleanings to only once per year. 
• Patented brine distributors—Individual tube distributors 
ensure a smooth flow of brine, avoiding scale formation.
• Variable waste flows—GE’s largest single brine concentrator
treats 1,200 gpm, while small units treat as little as 10 gpm.
• Energy-efficient operation—In the vapor compression
configuration, the brine concentrator uses 21 to 37 BTU 
per pound of waste feed. This converts to 50 to 90 kWh per
1,000 gallons of feed, which is 25 to 50 times more efficient
than conventional single-effect, steam-driven evaporators
• Ability to run on electricity or steam—Typical operation 
is by mechanical vapor compression, but brine concentrators
may also run on steam in a multiple-effect configuration.
• Fully automated operation—Maintain precise system control
while minimizing operator interaction
Crystallizer
Meeting stringent zero-liquid-discharge requirements also 
requires a crystallizer, to reduce brine concentrate to a dry solid.
Recovered water can be recycled back to plant processes, while 
an easy-to-handle dry solid can be safely disposed of in an
approved landfill.
• Ease of use—With simple color graphic controls and an
automatic wash system, GE’s crystallizers are easy to operate.
• Ease of installation—Skid-mounted, fully packaged systems
with all auxiliary equipment and controls.
• Valuable product recovery—Systems can be designed to
recover specific salts from a waste stream.
• Expertise in zero liquid discharge—GE has more than 
35 years of experience developing and implementing thermal
technologies to solve zero liquid discharge challenges for customers worldwide.