Zero liquid discharge (ZLD) technology

Zero liquid discharge - ZLD

ZLD applications in various types of industry by MEGA electrodialysis

Did you know?

Compared to RO, ED and EDR ZLD systems are able to concentrate feedwaters to higher salinity up to 200 g/l

What is zero liquid discharge

What is zero liquid discharge

Zero Liquid Discharge (ZLD) is a water treatment process with a goal of recirculation of all of the possible water back to the process with zero liquid waste. The ultimate treatment process has zero or nearly zero impact on the environment.

Pre-treatment - reducing TSS, COD, Turbidity to filter out particle impurities or precipitation of sparingly soluble compounds to allow additional treatment.

Concentration of dissolved solids - by membrane technologies, either by a combination of reverse osmosis (RO) with electrodialysis (EDR). The way of concentrating RO brine by EDR. Or single step electrodialysis. Using these technologies to concentrate the stream we can achieve more than 98 % of recovery.

Thermal treatment - the last step is usually consisting of Evaporator/Crystallizer to generate solids. Final evaporation of remaining water for re-use together with precipitation of solid waste for disposal in a controlled landfill or to be sold as a valuable product (pure NaCl Na2SO4 etc.)

MEGA Electrodialysis zero liquid discharge plant

Benefits of ZLD plant

Zero liquid discharge plant technology is growing globally as an important wastewater management strategy to reduce water pollution and extend water supply. The main benefits of ZLD are:

  • Minimizes wastewater discharge
  • Maximizes water recovery
  • Create a valuable product for sale
  • Removing environmental issues
  • Reduction of dependence on local water sources and local legislation

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ZLD system by MEGA

Electrodialysis in ZLD

RALEX® ED(R)-IF/250 – The world's most capable electrodialyser

MEGA is focused mainly on the concentration of dissolved solids with its EDR products. We are offering a reduction of the waste stream before thermal treatment to decrease the complete cost of the water treatment plant.

We are also capable to offer technology for non-thermal ZLD plant. Using a special type of Electrodialysis with Bipolar Membranes (EDBM, BPED) we are capable to use salts to produce acid and caustic to be locally used in production. Such technology then has three products acid, caustic and desalinated water not requiring additional treatment.

Being a manufacturer of electrodialysis technology for decades, we have used our first-hand experience from the field to develop a new generation of electrodialysers. The ED(R)-IF stack is the world's most effective membrane concentrator used in ZLD plants.

RALEX membranes for different industries and processes

MEGA ZLD technology industries

MEGA offers electrodialysers for various zero liquid discharge plants all over the world. The MEGA´s Electrodialyzers are original products developed for wastewater ZLD plants used since the '80s. Nowadays MEGA apply its technology mainly for:

  • Textile
  • Power
  • Tanneries
  • Breweries
  • Chemical
  • Petrochemical
  • Paper industry
...And many other industries all over the world.

Benefits of electrodialysis ZLD solution

Advantages of electrodialysis ZLD solution by MEGA

  • Reduction of pre-treatment
  • High concentration of salts (up to 200 g/l)
  • Avoid evaporator, direct use of crystallizer
  • Silica does not influence water recovery/concentration capabilities
  • High reduction of capital and operating expenditure
  • Low chemical demand
  • Operation under low pressure
  • Standard frequency of replacement of parts

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RO brine treatment by ZLD system

RO brine treatment

Enhancement of existing RO plants can be achieved with a combination of RO and EDR technology. Even that the working principles of these two technologies are far from each other, we are proud to own the know-how of coupling these together in industrial scale and to provide this solution to the customer.

Advantages of RO brine treatment by MEGA ZLD system

  • Increase water recovery of existing RO
  • Increase capacity of your plant without the need for additional wastewater treatment
  • Increase capacity of SWRO without the need for marine works
  • Implement correct combination for your ZLD by combination of technologies

Our ZLD projects

Zero Liquid Discharge Water Treatment EDR

ZSNP at Žiar nad Hronom, Slovakia

Desalination of tailing ponds after production of aluminium oxide

Slovak leading producer of aluminium, ZSNP headed to the negative impact of its production activities. The feed water for the sludge bed has very high alkalinity (pH 13–14) and contains free NaOH, anions of OH-, CO3 2-, cations of Na+, K+, metals as Al (1 g/l), heavy metals Cr, As, Mo, V and some organic matters.

The typical electrodialysis mode Feed & Bleed has been chosen for this case. Design of membrane process was done with emphasis to reaching the quality of desalinated water (6 g/l) and maximal concentration of brine (180 g/l). The fundamental advantages are in the flexibility of process control allowing to obtain wanted product quality and quantity.

ZSNP highlights

High quality of output water Process efficiency Using waste as a product
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Tomas Dornik

Tomas Dornik

Sales Manager

+420 601 342 268
Oleksandr Bornosus

Oleksandr Bornosus

Area Sales Manager, CEE and CIS

+420 722 459 239
Zdenek Divisek

Zdenek Divisek

Area Sales Manager, Americas

+420 725 090 944