Zero Liquid Discharge or ZLD is one of the industrial water treatment systems where all the contaminants are converted into solid waste while separating the water. This process helps to decrease the waste quantity & recover fresh water which can be reutilized. Although ZLD is a noble approach, it is not at all an easy process and requires a high investment of money & machinery. Extraction of water from waste means dealing with a higher concentration of salinity, scaling compounds, and organics, which means increased cost. But there are various benefits of ZLD which makes it an optimum choice for an industrial facility.
Several methods of waste management are classified as zero liquid discharge, despite using different boundaries to define the point where the discharge occurs. Usually, a facility or site property line that houses the industrial process is considered the border or ‘boundary condition’ where wastewater must be treated, recycled, and converted to solids for disposal to achieve zero liquid discharge.
Certain facilities which send their liquid waste for off-site treatment, deep well disposal or incineration, consider this to be akin to zero liquid discharge. While this approach actually avoids discharge of liquids into surface water or sewers, it can significantly increase the cost.
Some designs describe themselves as near zero liquid discharge or minimal liquid discharge systems which do not completely eliminate complete waste but may be more economical than ZLD.
An optimum ZLD treatment system should be able to:
● manage fluctuations in waste contamination and flow
● support required chemical volumes adjustments
● recover about 95% of the liquid
● treat and retrieve valuable byproducts from your waste
● produce a dry, solid cake for disposal
What makes ZLD important
Undeniably, freshwater is a scarce yet important resource in the industrial processes. Reusing the water becomes highly beneficial and economical too. Not to mention additional benefits like less damage to the environment. On a broader scale, heavy contamination of rivers and water bodies have forced the government to make regulatory reforms in wastewater treatment. The severe consequences of water pollution have led to the rise in consideration of methods like zero liquid discharge system to tackle the issue on a large scale. For example, The Gainesville Renewable Bioenergy plant which is expected to power 70,000 homes in Gainesville, required setup of a complete zero liquid discharge system before granting the permit. One more notable perk of considering zero liquid discharge is the scope to recover the lost resources from wastewater.
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