Important considerations for implementing ZLD for industrial wastewater treatment

Zero liquid discharge (ZLD) wastewater treatment can improve water recycling, reclaim valuable resources and eliminate contaminated wastewater discharge. But before implementing a ZLD system, you must consider several important factors.

The rapid depletion of water resources in water stressed countries like India has forced many industries to reevaluate their approach to water management. In addition, widespread pollution issues have prompted Indian authorities to introduced regulation designed to improve water recycling and reduce the discharge of contaminated industrial wastewater.

To address these increased demands, zero liquid discharge (ZLD) systems are getting greater attention as useful wastewater treatment and water management solutions for complex industrial production. ZLD is an ambitious strategy for wastewater management, which enable the factory or plant to recover most of its wastewater for recycling.

With ZLD, the wastewater is treated, purified and cycled back for reuse. You can then safely dispose the remaining solid waste, often after reclaiming valuable resources like Glauber’s salt. The ZLD process ensures that no effluent is discharged from the facility thus eliminating the risk of contaminating the local water supply or environment.

Despite all these benefits, ZLD systems are expensive to implement, have high operating costs and can be challenging to maintain. It is important to consult an experienced partner or specialist, who can assist you in designing a customized solution which fits your specific production setup, challenges, and goals.

For system integrators or water technology consultants responsible for designing and implementing wastewater treatment systems at factory level, comprehensive knowledge of related technologies is essential.   You should examine how membrane technology, ultrafiltration and high-recovery reverse or forward osmosis can be incorporated in you ZLD design.

Usually, an initial lab-scale test followed by a pilot project ensures the best outcome.

Before embarking on the process of building or selecting and implementing a ZLD solution, take time to make these important considerations:

  1. What are your primary business drivers for implementing ZLD? While the need to comply with stricter regulation is the primary driver for most ZLD implementations in India, there may be other business drivers that are relevant to consider. Do you want to reduce your dependency on scarce water resources, reduce your use of chemicals, minimize your waste or simplify your effluent treatment? This information is vital for your ability to steer the ZLD implementation project in the right direction. The optimal solution depends on your plant and treatment goals.
  2. What are the characteristics of the incoming effluent? When selecting the ZLD solution, it is vital to take the exact characteristics of the wastewater effluent. You need to consider the total volume, pH, temperature, biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) and salinity, to name a few.
  3. How can you reuse the treated water in your production? One of the main benefits of a ZLD wastewater treatment system is the ability to reuse the majority of the processed effluent – often as much as 75 percent or more, depending on the specific site and design. A forward osmosis membrane solution can improve the quality of the recycled water, by extracting clean water while rejecting difficult contaminants even with high BOD/COD/TOC levels, thereby making more available for reuse.
  4. Do you want to reclaim valuable solids, salts, and chemicals? A ZLD can improve your ability to recover and reuse valuable compounds like salts . This can offset some of the total operating cost of the ZLD system.
  5. What can you do to reduce your energy costs? One of the major expenses of running a ZLD treatment system is the cost of the energy needed to power the evaporators which remove the remaining liquid from the effluent.  By integrating an forward osmosis (FO) process that uses Aquaporin Inside® FO membranes in your effluent treatment system, you can minimize waste by effluent volume and sludge reduction to save costs related to disposal or evaporation/crystallization in Zero or Minimal Liquid Discharge systems.

To learn more about the benefits of zero liquid discharge and forward osmosis, visit our industrial water hub here.

Published on October 20 in