Zero Liquid Discharge technology aims to reuse wastewater in a system. This technology has a bright future especially in regions around the globe where water reuse is mandatory.
A closed loop water cycle: this is the principle of Zero Liquid Discharge – or ZLD – technology.A simple principle, but a complex technology. Water remains in a closed loop in the factory, where it is gradually rid of all of its contaminants and is of high enough quality to be reused in the industrial facility’s process. There are four decontamination processes required to achieve this: physicochemical, pretreatment, biological treatment, filtration and, finally, evapoconcentration (see opposite). Certain pollutants are purified and reused in the process.
“ZLD technology has applications across multiple industries including oil and gas, automotive, food and beverage, pharmaceutical, and others,” states Dionisio Visintin, Marketing Manager of Veolia Water Technologies Italia’s Solutions division. “At the outset, this technology was geared toward large manufacturing and industrial complexes, but this is now no longer the case.”
So why utilize this sophisticated technology when it would be simpler to treat and discharge water using traditional wastewater treatment technology?
“ZLD technology is critical when the surrounding environment is fragile and cannot withstand even the discharge of treated wastewater effluent,” points out Visintin. “ZLD also offers another major advantage: since no effluent is discharged, water legislation need not be taken into account. Last but not least, it sometimes allows you to avoid post-treatment.”
Another scenario in which ZLD is a must: in regions where water is scarce, its reuse may be required by law. This is the case, for example, in California, which has been struck by drought for over a year and where all businesses are required to “close the loop.” Ever mindful of sustainability, most industries are now looking to reduce their environmental impact, especially their water consumption.