Water Reuse and ZLD

Why is water reuse important?

Rising water prices, stricter environmental regulations and increasing water stress make the efficient use of water a crucial competition factor. Companies have two approaches at their disposal, water reuse and zero liquid discharge (ZLD), to use water resources sustainably, significantly reduce fresh water demand and make the industrial water cycle more efficient.

What does ‘water reuse’ mean?

Water reuse, also known as water recycling or water recovery, refers to the treatment of process, rinse or cooling water in order to enable it to be reused in the production process, amongst other things. The aim is to provide valuable recycled water and to permanently reduce the consumption of fresh water.

Various treatment processes are used, depending on the water quality and the specific application. Membrane processes such as ultrafiltration, nanofiltration or reverse osmosis remove particles, dissolved substances and microorganisms, and enable the water quality to be adjusted to suit the respective process. In addition, processes such as softening, ion exchange, activated carbon filtration or UV disinfection can be employed. This ensures that the treated water can be reliably returned to the industrial water cycle.

What is Zero Liquid Discharge (ZLD)?

Zero Liquid Discharge (ZLD) takes things a step further. The aim is to recover almost all of the water so that no liquid waste water leaves the production site. To achieve this, membrane processes are combined with other technologies such as evaporators and crystallisers. The water is returned entirely to the process, whilst dissolved salts and other residues are separated out as solids.

What are the benefits of water reuse and ZLD?

The key benefits are:

• Reduced fresh water consumption
• Reduced wastewater volumes and disposal costs
• Greater security of supply during water shortages
• More sustainable and resource-efficient production
• Optimisation of the water cycle in industry
• Support in complying with legal requirements

Whether water reuse or ZLD is the right solution depends on the process requirements, water quality and economic conditions. Both concepts make an important contribution to sustainable water management whilst also enhancing the long-term security of industrial production sites.