AlfaFlash ZLD

What is Zero Liquid Discharge (ZLD) and why is it important? 

ZLD technology addresses the growing water challenges that industries are facing, including waste and pollution minimization, water scarcity, compliance with legislation and circularity. The ZLD market is significant and expanding, driven by those megatrends. Most industrial processes rely on fresh water, which often results in a wastewater stream. This polluted and contaminated water represents a cost for treatment, discharge or offsite disposal, and environmental concerns. ZLD systems are designed to treat this wastewater, letting you recover and reuse both water and valuable chemicals directly at the production site. This is crucial for achieving profitable circular solutions. By reusing water and recovering value with ZLD technology, industries make their operations more sustainable and efficient. A ZLD system enhances resiliency, aligns profit and sustainability goals, leading to a more robust business, less vulnerable to external changes.

ZLD is a combination of technologies

The goal of a ZLD system is to minimize liquid waste and convert it into reusable clean water and solids that can be used, sold, or safely disposed of. A ZLD system combines technologies to reduce wastewater as much as possible, while producing concentrated solids and high-quality water at the end. The most common process steps follow this sequence:

• Chemical and/or physical pre-treatment of the raw wastewater. The aim is to prepare the stream for the requirements of the downstream steps. Typical examples of pre-treatment can be chemical reaction, precipitation, flotation or filtration.
• Membrane treatment and pre-concentration. Reverse osmosis is a common option to decrease the wastewater volume as much as possible at minimal cost.
• Thermal evaporation of the brine (reject) from the membrane step. Thermal evaporation further reduces the brine volume.
• Crystallization of the concentrated brine. It is during this step that the solids (crystals) are produced for disposal or reuse, achieving Zero Liquid Discharge.

Learn more about our ZLD systems! 

Alfa Laval ZLD systems are robust compact solutions for absolute minimization of liquid discharge in. Highly adaptable, they can be used across a range of demanding duties in various industries for wastewater reduction as well as recovery of product, and of water suitable for reuse. Our proven track record and extensive experience in both thermal solutions and separation technology ensure a cost-efficient solution.

Modular systems in standard configuration or customized to your needs

Mechanical vapor recompression (MVR) 

• Requiring electricity as utility
• Significantly less energy consumption compared with steam driven systems 
• Available in 1,5-6 ton/hour evaporative capacity or to your specific capacity needs in a customized configuration 
• Available as pre-assembled module
• Available in ZLD configuration equipped with crystal dewatering decanter centrifuge to produce a dry solids phase, and as stand-alone evaporator.

Multiple effect systems 

• Available  Multi-effect using steam, hot water or waste heat to drive the evaporation. Also available with thermal vapour recompression (TVR) enabling less steam consumption. 
• Available as pre-assembled module
• Available in ZLD configuration equipped with crystal dewatering decanter centrifuge to produce a dry solids phase, and as stand-alone evaporator.

Heat sources for evaporation system

Configuration Options

Alfa Laval evaporation systems can use heat from different sources such as mechanical and thermal compression as well as waste vapours from dryers.

Mechanical vapour recompression, MVR 

Multiple-effect system 

Thermal vapour  recompression, TVR 

Waste heat from your process

Working principle

Water is fed into the AlfaFlash heat exchanger. After heating fluid is then pushed through the flash orifice. The mixture is now essentially split in two phases – concentrate and vapour, which enters the cyclone separator where centrifugal forces boost vapour liquid separation. Vapour rises into space where mists and fine droplets are removed and the remaining concentrate flows into the recirculation pump. A side stream of concentrated liquid is then pushed through to the decanter where water is separated from solids. 

Decanter centrifuge working principle

AlfaFlash working principle