Industrial wastewater treatment, reuse processes, comparison of reverse osmosis concentration treatment methods
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At present, industrial wastewater is mostly reused in treatment processes, but desalination methods always generate concentrated wastewater. Let’s discuss the current methods for treating this concentrated wastewater, comparing the initial investment, operating costs, and performance levels. What will happen if this concentrated wastewater is not treated?
We have come across cases where RO concentrate was treated using electrodialysis; however, due to the relatively high COD level of this concentrate, around 300–400, the macromolecular anionic substances present in it can clog the cathode membrane of the electrodialysis system, resulting in a decrease in efficiency. Currently, there are projects that use a combination of resin methods and electrodialysis. This achieves the purpose of protecting the cathode membrane. Improves the processing effect.
Or another option is to use MVR for evaporation treatment
1. At the previous reclaimed water point, 2. or as direct water for rinsing
What happens if concentrated water is not treated? It’s fine as long as other parameters are within the acceptable range
This post was last edited by Gorou’s Eight Trigrams Staff on 2015-7-29 09:15. If the quality of the concentrated water is good, it can be directly discharged into the raw water collection tank. However, if this concentrated water has a significant impact on the quality of the water in the tank, it is recommended to treat it separately; this can reduce the load on the membranes and extend their service life.
Using only electrodialysis can reduce operating costs; when combined with resins, resin regeneration and flushing increase labor costs and expenses
For industrial wastewater and concentrated wastewater, it is basically impossible for other parameters to meet the required standards
Using electrodialysis alone is not feasible because the COD level of the concentrated water is very high; in actual applications, using electrodialysis solely on the concentrated water causes severe clogging of the cathode membrane, which affects the treatment efficiency. That’s why resin was added.
Thank you all for your active participation. I hope we can continue to discuss this topic. For treating concentrated wastewater, methods such as evaporation and electrodialysis are available; however, evaporation comes with high operating costs, while electrodialysis requires a significant initial investment, and it still results in the generation of concentrated wastewater
If the concentrated water is still to be reused, we have carried out a project in the past to remove hardness from it. If there is a sufficient amount of water, depending on its quality, lime or soda ash can be added to high-density tanks, or both of these substances together with PAC can be used to remove hardness. After that, a V-filter is used to reduce part of the COD, and finally the water proceeds to ultrafiltration and reverse osmosis systems for water recovery; as for the concentrated water, it is sent to evaporation and crystallization units.