Zero Liquid Discharge in Gujarat: Industrial Wastewater Infrastructure, ZLD Systems and EPC Planning

Industrial growth and water management are increasingly interconnected.

As manufacturing expands, industries need reliable water for production, utilities and processing. At the same time, the wastewater generated by these activities needs to be collected, treated, reused or disposed of in accordance with applicable environmental requirements.

This is particularly important in Gujarat, where large industrial clusters support chemical, pharmaceutical, textile, petrochemical, engineering and other manufacturing activities.

One technology that has become increasingly relevant in water-intensive industrial applications is Zero Liquid Discharge, commonly known as ZLD.

ZLD is an industrial wastewater management approach designed to minimise or eliminate liquid discharge from a facility by treating wastewater, recovering usable water and concentrating the remaining dissolved contaminants into a manageable solid or concentrated stream.

It is not simply a piece of equipment.

A successful ZLD system can involve an interconnected infrastructure comprising:

• Effluent collection
• Equalisation
• Primary and secondary treatment
• Membrane treatment
• Reverse osmosis
• Concentrate management
• Evaporation
• Crystallisation or drying
• Water recovery
• Sludge and salt handling
• Pumps and pipelines
• Electrical systems
• Instrumentation
• Automation
• Monitoring

For Gujarat industries, therefore, ZLD should be considered as part of the broader industrial wastewater and EPC infrastructure strategy.

What Is Zero Liquid Discharge?

Zero Liquid Discharge is a wastewater treatment approach in which the objective is to recover water from industrial effluent while avoiding the routine discharge of liquid wastewater outside the system.

The process typically separates wastewater into two broad outcomes:

Recovered water that can potentially be reused for suitable industrial applications.

Concentrated residual material that requires further management.

The exact process depends heavily on the characteristics of the industrial effluent.

Factors such as:

• Total dissolved solids
• COD
• BOD
• pH
• Chlorides
• Sulphates
• Heavy metals
• Oil and grease
• Organic compounds
• Temperature
• Flow variation

can influence the treatment train.

This is why a ZLD system should not be selected solely by looking at the plant's daily flow rate.

The quality and composition of the wastewater are equally important.

Why ZLD Is Important for Gujarat Industries

Gujarat has one of India's most diverse industrial ecosystems.

GIDC currently identifies 239 industrial estates across the state and continues to develop industrial areas, Special Investment Regions, PCPIRs and sector-specific industrial estates.

GIDC's industrial infrastructure framework includes water and drainage systems as well as environmental infrastructure such as CETPs, depending on the requirements of individual estates.

The state's industrial clusters include areas such as:

• Ahmedabad
• Vadodara
• Bharuch
• Ankleshwar
• Vapi
• Surat
• Sanand
• Dahej
• Hazira
• Jamnagar
• Kutch

These clusters have different industrial wastewater profiles.

Chemical manufacturing can generate high-TDS or chemically complex effluent.

Textile processing can generate wastewater containing dyes, salts and other process contaminants.

Pharmaceutical manufacturing can generate variable organic and chemical loads.

Petrochemical and industrial facilities can generate complex process wastewater requiring specialised treatment.

Consequently, ZLD is not one universal process.

It is an engineered wastewater management strategy.

ZLD vs Conventional ETP

A common misunderstanding is that ZLD simply means installing a larger ETP.

It does not.

An ETP is designed to treat industrial effluent to the required quality for its intended discharge or reuse pathway.

A ZLD system goes further by attempting to recover water and minimise or eliminate liquid discharge.

A conventional treatment system may include:

Collection → Primary Treatment → Biological/Chemical Treatment → Clarification → Filtration → Discharge or Reuse

A ZLD-oriented system may include:

Collection → Pretreatment → Biological/Chemical Treatment → Filtration → RO → Concentrate Management → Evaporation → Crystallisation/Drying → Water Recovery

The exact configuration varies according to the wastewater characteristics and the required recovery rate.

Therefore, an industrial facility should not automatically choose ZLD simply because it is technologically advanced.

The right solution depends on:

• Regulatory requirements
• Site conditions
• Water availability
• Effluent characteristics
• Reuse objectives
• Energy availability
• Capital cost
• Operating cost
• Waste-residue management

How a Typical ZLD System Works

1. Effluent Collection

Wastewater first needs to be collected from different process areas.

This may require:

• Collection drains
• Sumps
• Pumping stations
• Underground pipelines
• Above-ground pipelines
• Flow meters
• Transfer pumps

Industrial facilities often generate different wastewater streams.

Separating incompatible streams at source can make downstream treatment more effective.

2. Equalisation

Industrial wastewater flow and composition can vary during the day.

An equalisation tank helps balance these variations before wastewater enters downstream treatment processes.

It can help stabilise:

• Flow
• pH
• Pollutant concentration
• Temperature

This provides a more consistent feed to the treatment system.

3. Primary and Chemical Treatment

Depending on the effluent, primary treatment can include:

• Screening
• Oil separation
• Coagulation
• Flocculation
• Chemical precipitation
• Clarification

The objective is to remove contaminants that could interfere with subsequent treatment stages.

4. Biological Treatment

Where biodegradable organic matter is present, biological treatment may be incorporated.

The technology selected depends on the characteristics of the wastewater.

Potential processes include:

• Activated sludge
• MBBR
• MBR
• Other biological systems

Not every ZLD project requires the same biological treatment.

5. Filtration

Filtration can remove remaining suspended particles and protect downstream membrane systems.

Depending on the application, systems can include:

• Sand filtration
• Activated carbon
• Micron filtration
• Other polishing systems

6. Reverse Osmosis

Reverse osmosis can recover a significant proportion of treated water while concentrating dissolved salts and contaminants into an RO reject stream.

The recovered permeate can potentially be reused for appropriate applications.

However, RO does not by itself achieve ZLD.

The concentrated reject still requires management.

7. Concentrate Management

The RO reject or other concentrated stream is where ZLD becomes more technically demanding.

Depending on the project, concentrate treatment can involve:

• Evaporation
• Mechanical Vapour Recompression
• Multi-Effect Evaporation
• Crystallisation
• Agitated Thin Film Drying
• Other specialised technologies

Technology selection depends on wastewater chemistry, recovery targets and economics.

8. Final Residue Management

The final concentrated material may require:

• Salt recovery
• Crystallisation
• Drying
• Solid-waste handling
• Approved disposal
• Potential beneficial reuse where technically feasible

A ZLD project therefore needs to consider the entire material balance, not just the recovered water.

The Role of RO in ZLD

Reverse osmosis is frequently an important stage in industrial water-recovery systems.

However, RO has practical limitations.

As dissolved solids become concentrated, osmotic pressure increases and recovery becomes more difficult.

This means that simply increasing RO recovery indefinitely is not practical.

The remaining concentrate therefore needs another treatment pathway.

This is where thermal processes or other concentrate-management technologies can become relevant.

The final configuration should be established through:

• Laboratory testing
• Pilot testing where required
• Water analysis
• Mass balance
• Energy balance
• Technology evaluation
• Lifecycle cost assessment

MEE, MVR and ATFD in ZLD Systems

Three technologies frequently associated with industrial ZLD systems are MEE, MVR and ATFD.

Multi-Effect Evaporator

A Multi-Effect Evaporator uses multiple evaporation stages to improve thermal efficiency.

It can be used to concentrate wastewater or RO reject.

Mechanical Vapour Recompression

MVR uses mechanical compression of vapour to reduce the requirement for external steam or thermal energy under suitable operating conditions.

It can be attractive where energy efficiency is an important consideration.

Agitated Thin Film Dryer

ATFD systems can be used for further concentration and drying of highly concentrated streams.

The objective can be to produce a more manageable solid residue.

The choice between these technologies should be based on actual wastewater characteristics rather than simply selecting the newest or most sophisticated equipment.

Gujarat's Textile Industry and ZLD

Textile processing is one of the clearest examples of where advanced industrial wastewater management can become important.

Dyeing, washing, bleaching and finishing processes can generate significant wastewater containing salts, colour, organic compounds and other contaminants.

Gujarat's textile ecosystem makes this particularly relevant.

The Ministry of Textiles reported in 2026 that the Gujarat Eco Textile Park project at Palsana had a project cost of ₹146.39 crore and was nearing completion under the Integrated Processing Development Scheme. The ministry also stated that the supported parks were implementing ZLD technology, with Multi-Effect Evaporation being another technology used for treated-water recovery. (PIB)

This is a useful indication of how wastewater infrastructure is being integrated into newer industrial development.

PM MITRA Park and Integrated Wastewater Infrastructure

The PM MITRA Park at Vansi in Navsari provides another important Gujarat example.

GIDC's official project information lists the park's infrastructure facilities as including:

• 65 MLD water supply
• CETP + ZLD
• Sewage Treatment Plant
• Integrated TSDF
• Power substations
• Boiler steam facility
• Common facilities
• Plug-and-play units

The park covers a planned area of approximately 1,142 acres.

This demonstrates an important principle in modern industrial development:

Environmental infrastructure is increasingly being planned alongside production infrastructure.

A manufacturing cluster cannot simply focus on land, roads and power.

Water supply, wastewater treatment, waste management and resource recovery must also be considered.

ZLD in Chemical and Pharmaceutical Industries

Chemical and pharmaceutical facilities can generate highly variable wastewater.

Depending on the manufacturing process, effluent may contain:

• High TDS
• Solvents
• Organic compounds
• Salts
• Acids
• Alkalis
• Specific process chemicals

This makes treatment design more complicated than a standard municipal wastewater application.

The wastewater treatment system needs to be based on actual process chemistry.

Competitors operating in Gujarat's ZLD market are specifically targeting pharmaceutical, chemical, textile, petrochemical and other industrial applications, reflecting the diversity of wastewater challenges across the state's manufacturing clusters. (Evops ZLD)

ZLD and Industrial Water Reuse

The strongest reason for implementing ZLD is not simply eliminating discharge.

Water recovery can reduce dependence on fresh-water sources.

Recovered water can potentially be reused for applications such as:

• Cooling towers
• Process utilities
• Boiler-related applications after appropriate polishing
• Washing
• Gardening
• Other non-potable uses

The actual reuse application depends on water quality.

A good ZLD project should therefore begin with the question:

Where will the recovered water be used?

This helps determine the required treatment quality and can prevent unnecessary over-treatment.

ZLD Is an Infrastructure Project, Not Just a Treatment Plant

This distinction is important for project owners.

A ZLD system may require significant infrastructure beyond the treatment equipment itself.

The complete project can include:

Civil Infrastructure

• Treatment foundations
• Tanks
• Buildings
• Equipment foundations
• Drainage
• Chemical storage areas
• Access infrastructure

Mechanical Infrastructure

• Pumps
• Piping
• Valves
• Treatment equipment
• Evaporators
• Dryers
• Crystallisation systems

Electrical Infrastructure

• Power distribution
• MCCs
• Control panels
• Cabling
• Backup systems

Instrumentation

• Flow measurement
• Pressure measurement
• Level measurement
• pH monitoring
• Conductivity
• TDS
• Other process parameters

Automation

• PLC
• SCADA
• Alarms
• Data logging
• Remote monitoring

This makes ZLD particularly relevant to EPC contractors capable of coordinating multiple engineering disciplines.

Why EPC Matters in ZLD Projects

A ZLD project has multiple interfaces.

For example, the evaporation system depends on the quality and quantity of the stream received from the preceding treatment stages.

The RO system depends on adequate pretreatment.

Pumps and pipelines must be sized according to process flow.

Electrical infrastructure must accommodate the treatment equipment.

Instrumentation must provide operators with reliable information.

If these systems are designed independently, interface problems can appear during commissioning.

An integrated EPC approach can coordinate:

Process + Civil + Mechanical + Electrical + Instrumentation + Automation

within one project framework.

Energy Consumption: A Critical ZLD Consideration

One of the most important challenges associated with ZLD is energy consumption.

Thermal concentration processes can require substantial energy depending on the wastewater characteristics and technology selected.

Therefore, energy should be considered during the earliest design stage.

Potential strategies include:

• Maximising upstream water recovery
• Optimising RO recovery
• Reducing unnecessary thermal load
• Heat recovery
• Efficient evaporation systems
• MVR where technically and economically suitable
• Better insulation
• Optimised operating conditions

A system with slightly higher capital expenditure may sometimes deliver better lifecycle economics through lower operating costs.

This is why ZLD should be evaluated on a lifecycle-cost basis, not simply on initial equipment price.

How to Evaluate a ZLD Project

Before selecting technology, an industrial facility should establish a detailed baseline.

Step 1: Analyse the Wastewater

Test parameters such as:

• pH
• TDS
• COD
• BOD
• Chlorides
• Sulphates
• Hardness
• Suspended solids
• Specific contaminants

Step 2: Determine Flow

Understand:

• Average flow
• Peak flow
• Seasonal variation
• Production-linked variation

Step 3: Identify Water-Reuse Requirements

Determine where recovered water can be used.

Step 4: Develop a Mass Balance

Track:

Freshwater → Process → Effluent → Treatment → Recovered Water → Concentrate → Final Residue

Step 5: Compare Technologies

Evaluate:

• Capital cost
• Energy consumption
• Chemical consumption
• Recovery
• Footprint
• Maintenance
• Reliability

Step 6: Plan Residue Management

A ZLD system is incomplete unless the final concentrated residue has a defined management route.

ZLD and Regulatory Planning in Gujarat

Industrial wastewater projects must be developed with applicable environmental requirements in mind.

CPCB maintains a dedicated SOP for issuance of ZLD certificates, published in July 2024. (CPCB)

Gujarat's industrial regulatory environment also places importance on continuous monitoring for relevant industrial categories.

A Gujarat Pollution Control Board affidavit submitted in environmental proceedings states that certain large and medium red-category industries are required to install systems for continuous monitoring of effluent quality and quantity for relevant parameters, with connection to the GPCB server; it also states that industries with water consumption above specified thresholds must submit water-harvesting plans and that techno-economic feasibility of ZLD should be explored where applicable. (GPCB document)

Because regulatory applicability varies by industry and project, project owners should confirm the requirements applicable to their specific facility with the relevant authorities and environmental consultants.

ZLD for Existing Plants vs Greenfield Projects

ZLD planning differs significantly between an existing facility and a new industrial project.

Greenfield Industrial Project

A new facility has the advantage of planning:

• Treatment location
• Pipeline corridors
• Utility requirements
• Electrical capacity
• Water storage
• Reuse network
• Expansion space

from the beginning.

Existing Industrial Facility

An existing plant may face:

• Limited space
• Existing pipeline constraints
• Existing ETP configuration
• Limited electrical capacity
• Difficult construction access
• Production shutdown requirements

In such cases, the ZLD system may need to be integrated into an operating facility without disrupting production.

This makes brownfield EPC execution considerably more complex.

Common Mistakes in ZLD Projects

Selecting Technology Before Testing the Effluent

A technology that works for one industry may not work for another.

Focusing Only on Water Recovery

A high recovery number is not enough.

The energy, chemicals, maintenance and residue management requirements also matter.

Ignoring the RO Reject

RO reject is one of the central challenges in a ZLD system.

The downstream concentrate-management process must be considered from the beginning.

Not Planning for Residue Disposal

Recovering water does not mean the remaining solids disappear.

The final residue needs an appropriate management strategy.

Underestimating Energy Demand

Thermal systems can significantly affect operating costs.

Energy availability and cost should be considered during feasibility analysis.

Treating ZLD as an Isolated Equipment Purchase

A ZLD plant must integrate with the site's existing ETP, water network, electrical system, drainage and production processes.

How to Select a ZLD or Industrial Wastewater EPC Partner

Industrial companies should evaluate EPC partners on more than equipment supply.

Consider:

Process Engineering Capability

Can the contractor understand the actual wastewater chemistry?

Multidisciplinary Engineering

Can it coordinate civil, mechanical, electrical and instrumentation works?

Integration Experience

Can the new system integrate with an existing ETP or industrial water network?

Commissioning Capability

Can the contractor demonstrate performance after installation?

O&M Support

Can the contractor support the plant after commissioning?

Industrial Experience

Does the contractor understand the operating environment of chemical, textile, pharmaceutical, petrochemical or other manufacturing facilities?

The Gujarat market already contains specialist ZLD companies targeting equipment and treatment-system supply. Competitors such as Rototech and EVOPS position themselves around turnkey ZLD, ETP, evaporation and related systems. (Rototech) (EVOPS ZLD)

For larger infrastructure packages, however, project owners may also require broader EPC coordination covering pipelines, civil infrastructure, pumping, utilities and associated systems.

OmYash Projects and Industrial Water Infrastructure

OmYash Projects' service portfolio includes water infrastructure projects, drinking water and wastewater treatment, effluent treatment projects, pumping machinery and other infrastructure services.

This wider EPC capability is relevant when industrial wastewater treatment needs to be integrated with larger infrastructure systems.

A major industrial wastewater project may require much more than the treatment equipment itself.

It may require:

• Effluent collection pipelines
• Pumping stations
• Civil structures
• Treatment infrastructure
• Electrical systems
• Instrumentation
• Automation
• Treated-water pipelines
• Storage
• Testing
• Commissioning

OmYash's project portfolio includes large-scale pipeline, pumping, water infrastructure and industrial-related projects.

The Future of Industrial Wastewater Infrastructure in Gujarat

The direction of Gujarat's industrial development points toward greater integration of production and environmental infrastructure.

GIDC's current industrial-development model includes water, drainage and environmental infrastructure within industrial estates.

Newer industrial developments are also incorporating advanced environmental systems from the planning stage.

The PM MITRA Park at Vansi is a clear example, with CETP + ZLD, STP and integrated TSDF included alongside water, power and common industrial facilities.

This suggests that future industrial infrastructure will increasingly focus on:

• Water efficiency
• Wastewater reuse
• Resource recovery
• ZLD where appropriate
• Digital monitoring
• Integrated utilities
• Energy efficiency
• Circular water management

The objective is gradually shifting from simply treating wastewater toward managing water as a recoverable industrial resource.

Conclusion

Zero Liquid Discharge is becoming an increasingly important part of industrial water management, particularly for water-intensive manufacturing sectors.

But ZLD should not be viewed simply as an evaporator, RO plant or specialised treatment machine.

A successful ZLD project requires an integrated system covering wastewater collection, treatment, water recovery, concentrate management, residue handling, pumping, pipelines, electrical infrastructure, instrumentation and long-term operation.

Gujarat's industrial ecosystem provides a strong example of this broader approach.

From textile clusters in South Gujarat to chemical and pharmaceutical manufacturing in central Gujarat and large industrial developments across the state, water and environmental infrastructure are becoming integral components of industrial planning.

For companies considering ZLD, the right approach begins with wastewater characterisation, process design, water-reuse planning and lifecycle economics.

The final technology should then be selected around the actual requirements of the facility.

For larger industrial wastewater and infrastructure projects, an EPC partner capable of coordinating treatment systems with pipelines, pumping, civil, mechanical and electrical infrastructure can provide a more integrated project-delivery approach.

Frequently Asked Questions

What is Zero Liquid Discharge?

Zero Liquid Discharge is an industrial wastewater management approach designed to recover usable water from wastewater while minimising or eliminating liquid discharge from the facility. Concentrated residual material is managed separately.

Is ZLD the same as an ETP?

No. An ETP treats industrial wastewater to meet the required quality for its intended discharge or reuse. ZLD generally adds advanced recovery and concentrate-management stages to minimise or eliminate liquid discharge.

Which industries use ZLD systems?

ZLD can be relevant to industries generating complex or water-intensive wastewater, including textiles, chemicals, pharmaceuticals, petrochemicals, food processing, metals and other manufacturing sectors. The suitability depends on wastewater characteristics and project requirements.

What technologies are used in ZLD?

A ZLD system can include pretreatment, biological or chemical treatment, filtration, reverse osmosis, evaporation, MEE, MVR, crystallisation and drying. The appropriate combination depends on the wastewater chemistry and recovery requirements.

Why is ZLD important for Gujarat industries?

Gujarat has a large network of industrial estates and manufacturing clusters with significant water and wastewater requirements. New industrial developments are increasingly incorporating advanced environmental infrastructure, including CETP and ZLD systems.

Is ZLD expensive to operate?

ZLD can have significant operating costs, particularly when thermal concentration is required. Energy, chemicals, maintenance and residue management should therefore be evaluated during project feasibility and lifecycle-cost analysis.

Does OmYash Projects provide industrial wastewater infrastructure services?

OmYash Projects provides water infrastructure, wastewater treatment and effluent treatment services as part of its broader EPC and infrastructure portfolio. Its capabilities can also cover associated pipelines, pumping and infrastructure required for large-scale projects. (OmYash Projects Services)

‍