Zero Liquid Discharge – An infinite loop to create wealth from refining waste
Zero Liquid Discharge (ZLD) is an advanced wastewater treatment process that aims to eliminate liquid discharge from industrial facilities, ensuring that no wastewater is released into the environment. ZLD systems are a vital tool for industries aiming to achieve sustainability goals by minimising their environmental impact through responsible water management. ZLD facilitates the recovery of valuable resources, such as salts and other chemicals, from the wastewater, promoting circular economy practices. Integrating ZLD can often lead to energy savings by utilising waste heat for the evaporation process, enhancing overall plant efficiency. Implementing ZLD ensures compliance with stringent wastewater discharge regulations, reducing potential penalties and legal liabilities. ZLD has gained popularity worldwide, especially in regions facing severe water scarcity or strict environmental regulations.
Some industries are already subject to ZLD regulations in certain jurisdictions. For example, the US Environmental Protection Agency (EPA) and EU Industrial Emissions Directive (IED) have ZLD regulations for the Power, Coal, and Oil and gas industries. These agencies are considering implementing ZLD regulations for additional industries in the future. Many more governments across countries are considering or implementing ZLD regulations at the local, provincial, or national level, as part of their efforts to protect water resources. Additionally, industries located in water-stressed areas or those operating in environmentally sensitive regions may face stricter requirements to manage and treat their wastewater effectively, often requiring the use of ZLD or similar discharge approaches.
Some steps to be kept in mind while implementing a ZLD system include:
- 1. Conducting a thorough water audit to understand water usage patterns and identify the opportunities for water reuse/recycling considering the specific needs of the wastewater stream and the desired level of treatment before designing and implementing a ZLD system;
- 2. Choosing the right ZLD technology from the variety available guided by the specific characteristics of the wastewater and the desired level of treatment;
- 3. Designing the ZLD system to make it modular and scalable, allowing for easy expansion or adjustments based on the facility's changing needs and production capacity;
- 4. Making sure there is an effective pre-treatment solution to remove contaminants and impurities before the ZLD process to enhance the efficiency and longevity of the ZLD system; 5) Strategies for optimising chemical recovery and ensuring that valuable chemicals are efficiently extracted and reused within the industrial process;
- 5. Putting in place a regular system to monitor performance, conduct preventive maintenance, and incorporate data-driven insights to ensure the ZLD system operates at peak efficiency and complies with regulatory requirements; and
- 6. Involving stakeholders and providing adequate training to operators to enhance their understanding of ZLD systems, promoting efficient operation and sustainable management.