In the paper industry, nanofiltration membranes are primarily used for the efficient treatment and resource reuse of process wastewater. Through their precise sieving characteristics, they effectively remove lignin, pigments, salts, and harmful chemicals from wastewater, enabling water recycling and significantly reducing clean water consumption and wastewater discharge. Simultaneously, membrane technology can also be used to recover valuable byproducts (such as lignin) and improve the quality of production water, helping paper companies achieve green, energy-saving, and sustainable production.