How should wastewater meeting Level 3 emission standards be further treated?
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One of our plant’s biochemical wastewater treatment systems requires the addition of tap water before treating the wastewater, in order to dilute the wastewater with high COD levels, and then proceed with the biochemical treatment. We now intend to treat the qualified wastewater after biochemical treatment (meeting Level 3 discharge standards) and reuse it as dilution water, in order to reduce the consumption of tap water and wastewater discharge. Do any of you have any good suggestions? Thank you!
Let’s see if sodium hypochlorite can be used for oxidation
Is the ammonia nitrogen level high? It is difficult to develop activated sludge using tertiary effluent. Chlorine can be added first (since biochemical treatment has been carried out earlier, there are fewer biodegradable substances in the water; chemical oxidation can remove some of them, and breaking down large molecules into smaller ones facilitates further biodegradation). Alternatively, biological contact oxidation can be used (for COD removal, with lower costs), or coagulation–inclined tube sedimentation (also with lower costs), or coagulation–air flotation (with higher costs). Even coarse sand filtration (SS removal)
It is completely fine to dilute it directly with the tertiary effluent; no further treatment is required. Wastewater with high concentrations is diluted using the effluent from three-stage treatment, resulting in a significant reduction in concentration. Subsequently, physical and biological methods are employed for further treatment, such as air flotation, coagulation, anaerobic biological treatment, aerobic biological treatment, and strong oxidation; several of these methods can also be combined for treatment.
Sure, reusing treated water is very popular these days; you can consult a professional design firm or an environmental protection company.
I didn’t expect so many enthusiastic people to reply; thank you! Currently, the initial idea within the company is to use a membrane treatment method. I was wondering if anyone is familiar with similar technologies or has practical experience using them? It is said that this method is quite expensive
The initial investment for this membrane separation process can be higher than that of conventional methods! ! ! But the operating cost per unit is relatively low! ! The cost of recycled water per unit should be much lower than the cost of purchasing tap water! ! The payback period for equipment investment is about 1.5 years! ! Doing this can help build a great image for the company! !
Using membrane treatment is like using a cannon to kill mosquitoes. Furthermore, the water after tertiary treatment still has a high level of pollution; it also causes significant contamination of the membranes, resulting in increased treatment costs. It is very important to choose the appropriate treatment methods for wastewater of different levels.
Using the membrane method is quite inappropriate; it is recommended that you opt for the contact oxidation method or the aerated biological filter method, as these will yield excellent results!