Pilot-scale integrated membrane system for the treatment of acrylonitrile wastewater

• Acrylonitrile wastewater with high concentration was treated by a novel integrated membrane system (IMS).
• UF, NF and RO were included in IMS; pilot-scale plants of IMS were built and tested for 1600 h.
• Technical and economic analyses of pilot scale-plants were studied and compared with present four-effect evaporation system.
• IMS has a good application in acrylonitrile wastewater treatment instead of four-effect evaporation.

The production of acrylonitrile exceeds 5 million tons every year throughout the world, which leads to the huge emission of acrylonitrile wastewater. Hence, treating the acrylonitrile wastewater remains challenging. In this study, a pilot scale integrated membrane system (IMS) consisting of ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) was proposed to treat the highly concentrated acrylonitrile wastewater from petrochemical plants. A preliminary techno-economic study for a 24 m3/day wastewater treatment pilot plant was conducted. The system runs smoothly in 1600 h operation. In treating acrylonitrile wastewater with COD 22,000–30,000 mg/L, NH3-N 14–40 mg/L, CN− 20–55 mg/L, the effluent water quality of IMS was COD < 3000 mg/L, NH3-N < 10 mg/L, CN− < 5 mg/L. The results show that the developed IMS is effective for the treatment of acrylonitrile wastewater and industrialization of IMS is prospective.