How to achieve zero discharge in chemical process circulating water systems
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With **increasingly strict environmental regulations, the issue of wastewater discharge is becoming more and more problematic. Do anyone out there have any good solutions?
A reclaimed water reuse system can be added to reduce wastewater discharge
The so-called zero emissions cannot be achieved in a complete manner; at best, what can be done is to reduce emissions, or to reuse treated water and compress concentrated wastewater in order to eliminate wastewater discharge；
For closed-loop water systems, it is possible to consider using softened water as make-up water, which can help avoid problems related to chloride ions and total salt content, thereby achieving zero emissions. As for the reuse of treated water and concentration recovery, issues such as the disposal of concentrated wastewater and even the treatment of solid salts must be taken into account, as each of these approaches has its own drawbacks. It is recommended to consider using closed-loop cooling towers, as they require less make-up water and enable zero emissions; however, their initial investment is higher and their heat exchange efficiency is slightly lower than that of open-type cooling towers
The most reliable approach is probably reusing treated water. But I don’t understand how reusing treated water can reduce chloride ions. If reverse osmosis is used, then what happens to the concentrated water? How is it handled?
Zero discharge of industrial circulating water means that if soft water is used for make-up water, the discharge volume will be very low; however, it is unlikely to reach zero, and the costs will be much higher. The soft water production process also is not zero-emission.
Electroadsorption can remove salts and reduce wastewater discharge; electrodialysis, on the other hand, is costly but enables zero emissions
Firstly, soft water should be used for water replenishment; secondly, a bypass system should be installed to remove the sludge and microorganisms from the circulating water, which is then treated centrally after concentration, with the remaining water being reused.