CASE STUDY: ZLD SYSTEM FOR VARDHMAN TEXTILES

THE NEED

Vardhman Textiles, one of the most reputable textile groups worldwide, required state-of-the-art technology for the treatment and recovery of wastewater for its new ZDL plant.

Objective: to select the technology with the lowest operating cost, and therefore the most sustainable solution in the long term.

THE SOLUTION

WaterNext Group addressed this new challenge by applying the full extent of its know-how and experience, designing a completely innovative plant consisting of an initial fully biological stage for the removal of dissolved substances such as COD and BOD, solid separation using MBR technology, and a reverse osmosis system never designed or built before, with six stages in series, capable of recovering up to 97.5% of the wastewater and sending only 2.5% of the treated water to a vacuum evaporator.

In practical terms, the plant treats 2,500 m³/day, directly recovers 2,437.5 m³/day after the membrane process, and sends 62.5 m³/day to the evaporator, where it is subsequently recovered through vapor condensation, thereby closing the recovery cycle.

GOAL

The entire plant, including the evaporator, operates at a total operating cost – including electricity and chemicals – of €0.90/m³.

This is the lowest operating cost ever achieved worldwide for a ZLD plant in the industrial textile sector.

The project context

Vardhman Textiles is one of India’s leading vertically integrated textile groups, with a strong presence in yarns, fabrics, sewing threads, and acrylic fibers. The company is internationally recognized for its technological standards, operational excellence, and commitment to increasingly sustainable industrial production.

In the textile sector, wastewater management represents a particularly complex challenge. Dyeing, washing, finishing, and chemical treatment processes generate effluents characterized by quality variability, organic load, salinity, and the presence of substances that can affect both discharge quality and the possibility of reusing water within production processes.

For an industrial company such as Vardhman, wastewater treatment could not be considered merely an environmental requirement. The objective was to adopt a more advanced circular water management strategy, transforming treated water into a reusable resource and minimizing the amount of residual wastewater to be managed in the final stage of the process.

In this context, Vardhman Textiles selected WaterNext Group in 2025 to upgrade the wastewater treatment facilities at its plant in Ludhiana, Punjab, India. The project involved the development of a new-generation ZLD plant based on the integration of advanced biological treatment, MBR technology, multi-stage reverse osmosis, and Concentrated RO.

The technical challenge

In Zero Liquid Discharge plants, the evaporator is often the final stage of treatment. It is an effective technology, but also one of the most demanding in terms of energy consumption and operating costs. For this reason, a truly efficient ZLD plant should not simply rely on evaporation, but should reduce as much as possible the volume reaching the thermal section.

Vardhman’s challenge was therefore to develop a system capable of maximizing water recovery through membrane technologies while maintaining operational stability, permeate quality, and economic sustainability. In less optimized configurations, the evaporator may treat much higher percentages of the total flow rate, for example around 10%. This leads to higher energy consumption, higher operating costs, and more complex plant management.

WaterNext approached the project with an integrated strategy: rather than sizing the evaporator as the main solution, the aim was to reduce the residual flow upstream through a high-performance treatment line. The result is a plant in which the evaporation stage operates only on the final fraction that cannot be recovered through membranes.

The WaterNext Solution

The plant developed by WaterNext for Vardhman has a treatment capacity of 2,500 m³/day and was designed to ensure very high water recovery, stable operation, and reduced operational management requirements.

The treatment line integrates several technologies, each with a specific function. The advanced biological treatment reduces the organic load and stabilizes the incoming wastewater. MBR technology, Membrane Bioreactor, makes it possible to obtain high-quality treated water, with virtually no suspended solids and characteristics suitable for feeding the RO membranes.

Downstream of the MBR, the multi-stage reverse osmosis system recovers water that can be reused in industrial processes, progressively reducing the concentration of dissolved salts. The Concentrated RO section completes the process, further increasing recovery and minimizing the final volume sent to the evaporator.

This configuration allows evaporation to be used only where truly necessary. Instead of thermally treating a significant portion of the flow, the WaterNext system reduces the final residual stream to 2.5%, with a direct impact on energy consumption, operating costs, and overall sustainability.

Results achieved

The new ZLD plant developed for Vardhman achieves approximately 97.5% water recovery. This means that almost the entire treated flow is transformed into reusable water, while only a minimal fraction is sent to final management.

This result is particularly significant because it allows the evaporator to operate on only 2.5% of the flow, instead of much higher values. In a 2,500 m³/day plant, this difference has a major impact: less volume to evaporate means lower energy demand, lower thermal load, and reduced operating costs.

The plant’s operating cost is below €1/m³, an extremely competitive value for an advanced textile wastewater recovery system based on membrane technologies and integrated into a ZLD strategy.

In addition to its high water recovery rate, the plant ensures smooth operation thanks to automation, continuous monitoring, and control of the main process parameters. This reduces labor requirements and helps maintain stable recovered water quality over time.