Zero-liquid discharge (ZLD) is a water treatment process in which all wastewater is purified and recycled; therefore, leaving zero discharge at the end of the treatment cycle. Zero liquid discharge is an advanced wastewater treatment method that includes ultrafiltration, reverse osmosis, evaporation/crystallization, and fractional electrodeionization.


Water Technology BD Ltd (WTB) offers complete thermal and non-thermal ZLD solutions to manage tough-to-treat wastewaters. WTBL’s proprietary evaporators, brine concentrators, and crystallizers can help recover more than 95% of your plant’s wastewater while reducing the remaining brine as a product or solid.

Zero Liquid Discharge Process:

Pretreatment and conditioning:

Pretreatment is used to remove simple things from the wastewater stream that can be filtered or precipitated out, conditioning the water and reducing the suspended solids and materials that would otherwise scale and/or foul following treatment steps.

Ultrafiltration (UF) can also be used after the clarifiers instead of the gravity sand filter, or it can replace entire clarification process altogether. Membranes have become the newest technology for treatment, pumping water directly from the wastewater source through the UF (post-chlorination) and eliminating the entire clarifier/filtration train.


Phase-one concentration

Concentrating in the earlier stages of ZLD is usually done with membranes like reverse osmosis (RO), brine concentrators, or electro dialysis.



After the concentration step is complete, the next step is generating a solid, which is done through thermal processes or evaporation, where you evaporate all the water off, collect it, and reuse it.

Recycled water distribution/solid waste treatment

If the treated water is being reused in an industrial process, it’s typically pumped into a holding tank where it can be used based on the demands of the facility. The ZLD treatment system should have purified the water enough to be reused safely in your process.



Carbon Sand Filtration

The most common filters are filled with granular media such as sand/anthracite.
Filters are completely enclosed to use the line water pressure to push the influent through the media.

WTB offers a wide range of filters of different types and dimensions. Some of them are made entirely of Stainless Steel and can be operated either manually or automatically.

Membrane Bio-Reactor (MBR)

The term ‘membrane bioreactor’ (MBR) is generally used to define wastewater treatment processes where a perm-selective membrane eg; microfiltration or ultrafiltration is integrated with a biological process – a suspended growth bioreactor. Water Technology BD Ltd (WTB) is a renewed Company that working with Membrane Bio-Reactor (MBR).


MBRs differ from ‘polishing’ processes where the membrane is employed as a discrete tertiary treatment step with no return of the active biomass to the biological process.


Ultrafiltration (UF)

Water Technology BD Ltd (WTB) successfully working withUltrafiltration (UF) that is a separation process using membranes with pore sizes in the range of 0.1 to 0.001 micron. Typically, UF membranes will remove high molecular-weight substances, colloidal materials, and organic and inorganic polymeric molecules. Low molecular-weight organics and ions such as sodium, calcium, magnesium chloride, and sulfate are not removed by UF Membranes. Because only high-molecular weight species are removed, the osmotic pressure differential across the UF Membrane surface is negligible. Low applied pressures are therefore sufficient to achieve high flux rates from an Ultrafiltration membrane. Flux of a membrane is defined as the amount of permeate produced per unit area of membrane surface per unit time. Generally flux is expressed as gallons per square foot per day (GFD) or as cubic meters per square meters per day.