How to reduce COD levels in demulsified wastewater
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During the production process, the company generates some demulsified wastewater whose COD value is as high as nearly 100,000. I would like to ask experts how to handle this situation (without adding water) so that the COD value can be brought within acceptable levels for discharge
The common treatment processes for demulsified wastewater include physical separation and chemical separation. The basic process for physical separation is: high-speed rotational mixing – sedimentation in a sedimentation tank – solid-liquid separation using a vacuum filter or a pressure filter； Chemical separation involves adding aluminum or iron salts as coagulants, or the polymer flocculant PAM, to cause the suspended particles to coagulate, followed by solid-liquid separation. Relatively speaking, physical separation takes a longer time, while chemical separation yields results quickly, but the choice of demulsifier is quite important. The salt concentration of this wastewater is quite high. In my opinion, the best approach is to combine physical and chemical methods – that is, during the precipitation step using physical methods, additives such as polyacrylamide are added to the sedimentation tank to create a flocculation sedimentation chamber. This will yield better treatment results. As for the selection of these additives, you can refer to the websites www.gydacheng.com, www.dcjscl.com, and www.dcscl.com. I hope this will be helpful to the original poster
Even by adding demulsifiers, flocculants, and carrying out sedimentation and filtration, it is not possible to ensure that COD levels are within the allowable limits for discharge. For 100,000 units of COD, it would be quite good if it can be reduced to 1,000 using the above methods. Consider adding a wastewater treatment unit.
Our current treatment process involves oil separation, air flotation, flocculation, and filtration; the COD level can only be reduced to a little over 1000. As mentioned on the third floor, it seems that we will have to add additional equipment.
The key is to determine what type of wastewater it is. I’m not sure if the original poster can provide more details. At present, I am dealing with wastewater containing butyric acid; I’m able to reduce the COD level from tens of thousands to below 1000, while also recovering butyric acid.
Reply to 5#: Completely soaked. The wastewater in question is generated during the treatment of waste alkali; it consists of some oily wastewater that results from demulsification processes.
The common treatment processes for demulsified wastewater include physical separation and chemical separation. The basic process for physical separation is: high-speed rotational mixing – sedimentation in a sedimentation tank – solid-liquid separation using a vacuum filter or a pressure filter； Chemical separation involves adding aluminum or iron salts as coagulants, or the polymer flocculant PAM, to cause the suspended particles to coagulate, followed by solid-liquid separation. Relatively speaking, physical separation takes a longer time, while chemical separation yields results quickly, but the choice of demulsifier is quite important.