High-pressure reverse osmosis and nanofiltration, a ''zero discharge'' process combination for the treatment of waste water with severe fouling/scaling potential

Contrary to seawater desalination where water recovery rates of about 50% are optimal, waste water treatment processes must achieve very high water recovery rates since all disposal methods for the concentrate are very cost intensive. An established solution for waste water treatment is the combination of RO and evaporation. This paper discusses a simpler and more energy-efficient process - the combination of RO, operating at 60, 120 and 200 bar, with nanofiltration and crystallizer/filtration. For the treatment of dumpsite leachate, the process has been in operation since September 1994, achieving water recovery rates of >97%. The process details and oeprating performances are discussed, and consumption data are given.