Abstract:NF-HF and NF-HS nanofiltration membranes were employed to separate SO42- from Cl-in secondary reverse osmosis concentrate discharged from coal-chemical wastewater treatment plant. The separation of SO42- from Cl-, rejection of scaling ions and anti-fouling performance of the two types membrane were investigated. Spiral Tube Reverse Osmosis (STRO) was used to concentrate permeate of NF-HF. The results showed that NF-HF membrane had better separation Cl- from SO42- and rejection of scaling ions than NF-HS membrane, whose rejection were 3.38%-16.03% for Cl-, 91.18%-97.16% for SO42-, 90% for Ca2+, 80% for Mg2+ and 40% for SiO2, respectively. Moreover, NF-HF showed excellent antifouling property. The operating pressure rose slowly from 3.2 MPa to 4.5 MPa after continuously running 336 h and the membrane flux reduced by 11%, which was recovered completely after alkaline washing. STRO could effectively concentrate the NF-HF permeate and reject organic matter, but the anti-fouling performance was poor. Therefore, separating and concentrating coal chemical wastewater with NF-DTRO (Disc Tube Reverse Osmosis) combination process is practicable.