Top 5 Technologies Used in Zero Liquid Discharge Plants

Zero Liquid Discharge Plants

Zero Liquid Discharge (ZLD) solution is a comprehensive Industrial wastewater system that eliminates liquid waste discharge from industrial processes, ensuring that all the water used in the process is treated, recycled and reused. A Typical ZLD system involves multiple stages of treatment, including pre-treatment, ultrafiltration, reverse osmosis, and evaporation and crystallisation. The pre-treatment stage removes suspended solids, oil, and grease from the wastewater, while ultrafiltration removes colloidal particles and microorganisms. The reverse osmosis stage removes dissolved salts, impurities, and organic compounds, and the resulting concentrate is then treated through evaporation and crystallization to produce clean water and solids that can be reused or safely disposed of. Zero liquid discharge wastewater treatment solution helps industries to achieve compliance with environmental regulations, reduce freshwater intake, minimize wastewater discharge, and conserve water resources.

Importance of ZLD in modern industrial processes

Zero Liquid Discharge (ZLD) being an advanced engineering approach to water treatment where all water is recovered and contaminants are reduced to solid waste reduces environmental impact, improves sustainability and ensures compliance with local discharge and water reuse regulations.

For an industrial process or facility, aiming for zero liquid discharge has a variety of advantages such as :

1. Compliance with environmental protection regulations

Zero liquid discharge treatment system is a wastewater treatment process that enables industries to comply with strict environmental regulations. A ZLD plant minimizes or even eliminates the need for wastewater discharge, thus preventing water pollution and protecting the environment. 

2. Water Conservation

The Zero Liquid Discharge process makes effective use of wastewater treatment, recycling, and reuse, thereby contributing to water conservation through reduced intake of fresh water. This helps reduce the strain on local water sources, especially in water-stressed regions.

3. Cost Savings

Zero Liquid Discharge (ZLD) can save costs for industries in several ways. By decreasing the volume of wastewater, ZLD lowers the costs of waste management. It also allows for recycling water on-site, reducing the need for water intake and meeting treatment needs. This can reduce truck transportation costs for off-site disposal and related environmental risks. In Europe and North America, Zero liquid discharge process is in vogue due to the high costs of wastewater disposal at inland facilities. 

4. Corporate Social Responsibility (CSR)

Adopting Zero Liquid Discharge (ZLD) reflects a company’s dedication to sustainable and responsible business practices. It can improve the company’s reputation and support its corporate social responsibility efforts.

Top 5 Technologies Used in Zero Liquid Discharge Plants

Several technologies are used in Zero Liquid Discharge (ZLD) plants. The top 5 are listed below:

1. Membrane Filtration Technology

Membrane filtration technology plays a crucial role in Zero Liquid Discharge (ZLD) treatment systems, which are an effective solution for industries that produce large amounts of wastewater. In this technology, wastewater is filtered through specialized membranes that remove impurities. These membranes have tiny pores that allow water molecules to pass through while trapping larger particles and contaminants. ZLD systems can use various types of membrane filtration technologies, such as microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF), each with different pore sizes to remove different contaminants. Membrane filtration is often combined with other treatment processes like chemical pretreatment and evaporation to achieve ZLD. Membrane-based processes consume less energy and have lower membrane fouling problems compared to thermal processes.

2. Evaporation Technology

Evaporation technology plays a crucial role in Zero Liquid Discharge (ZLD) systems by effectively separating and concentrating contaminants in wastewater. This results in a reduced volume of solid waste and an increased volume of water that can be reused. In this, industrial effluent is pre-treated and evaporated until the dissolved solids precipitate as crystals. These crystals are removed and dewatered with a filter press or a centrifuge. The water vapor from evaporation is condensed and returned to the process. Evaporation technology can handle a wider range of waste streams compared to membranes and traditional physical/chemical treatment methodologies. Evaporation technology needs less intervention than other wastewater treatment methodologies, resulting in substantially lower labour requirements.

3. Crystallization Technology

In ZLD technology, industrial effluent is pre-treated and evaporated until the dissolved solids precipitate as crystals. These crystals are removed and dewatered with a filter press or a centrifuge. The water vapour from evaporation is condensed and returned to the process. Crystallization technology is a critical component of ZLD systems as it enables for the recovery of valuable minerals and salts from concentrated brine streams while minimizing environmental impact. Several crystallization technologies are used in ZLD systems, including forced circulation crystallization, vacuum crystallization, cooling crystallization, and anti-solvent crystallization. The choice of technology depends on the properties of the brine stream and the specific application.

4. Reverse Osmosis Technology

Reverse Osmosis (RO) technology is widely used in Zero Liquid Discharge (ZLD) systems. In the membrane-based reverse osmosis process, wastewater is pumped through fine-meshed semi-permeable membranes at high pressures. The introduction of membrane-based reverse osmosis systems has significantly reduced the operational costs of ZLD plants.

5. Brine concentration technology

A brine concentrator is a key component of a Zero Liquid Discharge (ZLD) water treatment plant which plays a crucial role by recovering valuable minerals or salts and reducing the amount of waste discharged into the environment. Brine concentrators evaporate water from the brine stream to create a more concentrated solution of salts and minerals. Different types of brine concentrators include forced circulation evaporators, falling film evaporators, mechanical vapour recompression evaporators, and multiple effect evaporators.

Wipro Water Approach

Wipro Water’s zero liquid discharge treatment system eliminates liquid waste with advanced water treatment processes, recovering over 95% of liquid waste for reuse and producing a dry, solid cake for disposal. The plants are designed to handle waste contamination and flow variations, allow chemical volume adjustments, and retrieve valuable by-products. Wipro uses the above-discussed technologies and with a strong focus on research and development has stayed at the forefront of the water treatment industry to deliver cutting-edge solutions.

Wipro Water is a division of Wipro Enterprises Pvt Limited, which has a number of businesses including fast-moving consumer goods, lighting, hydraulic cylinders, industrial automation, 3D printing and aerospace component manufacturing business headquartered in India. As an experienced global industrial wastewater treatment solution provider, Wipro Water has been serving the industry since 15 years+, providing a wide range of services and solutions to help industries effectively treat and recycle their wastewater. Wipro Water provides Zero Liquid Discharge (ZLD) solutions, which help customers to achieve zero liquid discharge from their water treatment facilities. As a trusted global industrial wastewater treatment solution provider, Wipro Water is committed to providing industries with the best possible solutions to help them effectively treat and recycle their wastewater in a sustainable and cost-effective way.