Zero liquid discharge (ZLD) - production without wastewater

It often pays off to close the water cycle in dry regions.

ZERO LIQUID DISCHARGE – POSSIBLE, YET NOT ALWAYS VIABLE

The future topic of zero liquid discharge is increasingly becoming an important issue for companies in many regions. For example, because there is a shortage of water at their production sites or resources have to be preserved.

Wastewater-free production is possible thanks to a combination of different wastewater treatment processes offered by EnviroChemie, however it is economically viable only under specific basic conditions. Water is required in many places in production. But regardless whether it is used, for example, for plant cleaning, cooling or dissolving substances, it usually has to be treated afterwards. The question is: To what extent? “Technically it is possible, of course, that no wastewater is left over,” says Elmar Billenkamp, expert on zero liquid discharge at EnviroChemie. For example, wastewater can be pre-treated with a combination of different EnviroChemie processes to the extent that it completely evaporates and leftover solids can be recycled or disposed of. Or it is treated so that instead of wastewater only sludge or brine is left over as residual material.

Disposal limitations

At some production sites, it is urgent to find alternative wastewater solutions: For example, the local sewage systems cannot be used or because there simply are none available. At other production sites, discharging is restricted by official regulations.

Water shortage

Another important motivating force for companies to deal with the topic of zero liquid discharge is water shortage. “Zero liquid discharge is usually not an issue wherever water is cheap and readily available. It often pays off to close the water cycle in regions where water is scarce,” says Billenkamp. For example, saline wastewater in a solar factory in Qatar is treated until it can be reused for cooling systems, irrigation or cleaning purposes. The remainder can safely be discharged into the ocean.

Freedom from regulations

In other cases, companies want to free themselves from dependence on official decisions by implementing wastewater-free production. For example, an automobile manufacturer chose a zero liquid discharge solution for its oily wastewater in its engine plant in Kazakhstan because it wanted to control its wastewater treatment costs.

Environmental protection

Environmental protection is also an issue. “In these cases, the reasons are internal corporate regulations regarding environmental objectives, or because companies want to obtain specific certificates for their production sites,” says Billenkamp. A cosmetics manufacturer wanted to achieve platinum, the highest level of LEED certification, with its factory in Mexico. LEED (Leadership in Energy and Environmental Design) is an internationally recognised building rating system. Bonus points are granted for an innovative wastewater treatment system which can be earned with the aid of EnviroChemie technologies.

These listed examples show how diverse the basic conditions for wastewater-free production can be. And they also show that “zero” does not necessarily mean nil. Sometimes liquids, sometimes solids are left over. “After all, wastewater does not simply disintegrate. That’s why you always have to consider what will happen with the separated substances,” says Billenkamp. For example, the solids could be incinerated to produce energy. That makes “zero” even a plus.