Emulsion-containing oily wastewater mainly comes from industries such as metal processing, petroleum, and docks. Its treatment difficulty is quite high because it has characteristics such as high oil content, high wastewater concentration, and difficulty in biodegradation. The problem of treating oily emulsion-containing wastewater urgently needs to be solved and has become a top priority in wastewater treatment. Nanofiltration membrane technology has a significant application effect in the treatment of oily emulsion-containing wastewater. So, what is a nanofiltration membrane? What are the advantages of nanofiltration membrane technology in the treatment of oily emulsion-containing wastewater?
Nanofiltration membrane is a functional semi-permeable membrane that allows solvent molecules or certain low molecular weight solutes or low-priced ions to pass through. It is a special and promising variety of separation membrane because it is named after the size of substances that can be intercepted, which is around the nanometer scale. It is used to remove organic matter and color from surface water, remove hardness from groundwater, partially remove dissolved salts, concentrate juice, and separate useful substances in drugs. Most nanofiltration membranes are composite membranes, and their surface separation layers are composed of polyelectrolytes, so they have a certain retention rate for inorganic salts. Many commercial nanofiltration membranes are now mostly composite with an ultra-thin separation layer with a nanometer-sized aperture on a microporous base membrane through interfacial polymerization and co-polymerization.
During the treatment process using a membrane, there is no need to add any other chemical reagents for chemical reactions. Physical separation can be carried out through the membrane only.
After treatment with nanofiltration membrane, no oily sludge is produced in the treatment of oily emulsion-containing wastewater, and the oil separated and concentrated by the membrane can be recovered, or it can be incinerated.
Even if the concentration of oil in wastewater is unstable and changes greatly, nanofiltration membrane technology will not have a significant impact on the permeate flow and water quality.
The cost of using nanofiltration membrane technology to treat oily emulsion-containing wastewater is low, and there is no need for high operating and equipment costs. It is only necessary to circulate wastewater through pressure. Difficult wastewater that is difficult to biodegrade can be treated with this method, especially wastewater with high oil content.
Generally, oily emulsion-containing wastewater contains some easily coagulated oil particles, and it is necessary to strictly pretreat this type of wastewater.