Agent and Process for Increasing Rejection of Nanofiltration Membrane or Reverse Osmosis Membrane, Nanofiltration Membrane or Reverse Osmosis Membrane, Process for Water Treatment and Apparatus for Water Treatment

摘要

An agent for increasing the rejection of a nanofiltration membrane or a reverse osmosis membrane which comprises a compound having a polyalkylene glycol chain having a weight-average molecular weight of 2,000 to 6,000; a process for increasing the rejection of a nanofiltration membrane or a reverse osmosis membrane which comprises bringing the nanofiltration membrane or the reverse osmosis membrane into contact with an aqueous solution of a compound having a polyalkylene glycol chain which is obtained by diluting the agent for increasing the rejection of a nanofiltration membrane or a reverse osmosis membrane described above with water; a nanofiltration membrane or a reverse osmosis membrane exhibiting a rejection increased in accordance with the process; and a process and an apparatus for water treatment using the nanofiltration membrane or the reverse osmosis membrane. The rejection and, in particular, the rejection to nonionic solutes, of a nanofiltration membrane or a reverse osmosis membrane can be increased while the flux is kept at a great value.