Zero Liquid Discharge – Key To Water Conservation

Zero Liquid Discharge – Key To Water Conservation

Almost every industry produces wastewater, but not all industries have zero liquid discharge plant (ZLD) facilities because they are complex and expensive.

In wastewater treatment, zero liquid discharge means every advanced technology has a limit to producing zero waste at the end of the process.

Components of the ZLD Treatment System

It is important to note that the exact components of a ZLD treatment system are heavily influenced by the volume of waste and the flow rate of waste and contaminants. ZLD treatment system typically includes:

  • Clarifier: Metals, hardness, and silica are precipitated out.
  • Chemical feed: To make it easier for any metals and suspended particles to precipitate, flocculate, or coagulate.
  • Filter press: After pretreatment, concentrate secondary solid waste.
  • Evaporator: In the final stages of trash concentration, access water is vaporized.

The global distribution of water resources is not uniform, and this coupled with climate change and a lack of effective water conservation strategies has led to widespread water scarcity. Physical scarcity occurs when there is simply not enough water available to meet demand, while economic scarcity happens even if enough water is available but without the necessary infrastructure in place to produce good-quality water. It has therefore become essential for industries to achieve and maintain wastewater recycling as much as possible, with a long-term ambition for Zero Liquid Discharge (ZLD) from all liquid streams. However, several elements can affect the effluent treatment process – including varying effluent quality and quantity changes due to manufacturing processes, as well as questions about the effectiveness of conventional treatments.

As technology continues to evolve and manufacturing processes become more advanced, the composition of wastewater is changing. It is essential then to have effective industrial wastewater treatment to manage water quality appropriately. Combining conventional treatments with new technologies opens possibilities to treat a range of discharges successfully. For instance, traditional methods can reduce organic matter and insoluble solids from coke oven wastewater whereas new adsorbents can be used to eliminate source-specific elements. This hybrid approach has proven successful in managing even the toughest types of wastewater, enabling them to be recycled.

ZLD is an increasingly popular solution to cut the water consumption of industries. Essentially referring to ‘Zero Liquid Discharge’, this system expunges all liquid waste from the plants. Wastewater can be cleansed, recycled, and residues concentrated and disposed off as solids. Membrane filtration-based techniques and bioprocesses are put into practice for treating industrial wastewater. Additionally, thermal technologies like multi-effect evaporators (MEE) and mechanical vapor recompression (MVR) are used to concentrate inorganic components in the wastewater stream, thus helping companies optimize their water recovery.

How Does the ZLD Treatment System Work?

This step in wastewater treatment involves removing unwanted substances with filtration or precipitation. Coagulation often necessitates adding chemicals like caustic soda and lime, which are combined in a reactor or reaction tank. This helps to decrease the amount of suspended solids, as well as other contaminants. The most popular coagulants used for this purpose are based on aluminum, such as alum and poly aluminum chloride.

After the coagulation process, flocculation follows. This involves the stirring together of the coagulated particles and long-chain polymers, resulting in visible, settleable particles. Several other processes can then take place, such as Reverse Osmosis, Electro dialysis, Evaporation and Condensation, Filtration, and several other processes depending on industrial needs. Once treated, water is pumped into a holding tank for later use within facilities thereby leading to Zero Liquid Discharge (ZLD).



We are a Zero Liquid Discharge Plant, ZLD Turnkey Projects Manufacturer, Supplier, Exporter, and Consultants (and Installation, Commissioning, and Consultancy Services Provider) based in Pune, Maharashtra, India. KWTPL has over 15 years of expertise in custom-designing and manufacturing wastewater treatment systems, so please contact us if you have any queries.

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