Agent for increasing rejection with a permeable membrane, process for increasing the rejection, permeable membrane and process for water treatment

A process for increasing rejection with a permeable membrane which is a nano filtration membrane or a reverse osmosis membrane and comprising a polyamide based material, said process comprising treating the permeable membrane a plurality of times with agents for increasing rejection with a permeable membrane, wherein said agents comprise a first agent for increasing rejection with a permeable membrane which comprises an aqueous solution of a cationic macromolecule having a weight average molecular weight of 100,000 or greater and a second agent for increasing rejection with a permeable membrane which comprises an aqueous solution of an anionic macromolecule having a weight average molecular weight of 100,000 or greater, and the permeable membrane is treated alternately with said first agent and then with said second agent or with said second agent and then with said first agent, wherein said treating is conducted by passing the first agent and then the second agent alternately through a module in which the permeable membrane is disposed or by passing the second agent and then the first agent alternately through a module in which the permeable membrane is disposed, or by dipping the permeable membrane into the first agent and then into the second agent alternately or by dipping the permeable membrane into the second agent and then into the first agent alternately, thereby the cationic macromolecule and the anionic macromolecule are adsorbed in the permeable membrane, wherein each of the first and second agents comprises a tracer for confirming the rejection comprising an inorganic electrolyte or an organic compound soluble in water.

A process for increasing rejection with a permeable membrane which is a nano filtration membrane or a reverse osmosis membrane and comprising a polyamide based material, said process comprising treating the permeable membrane a plurality of times with agents for increasing rejection with a permeable membrane, wherein said agents comprise a first agent for increasing rejection with a permeable membrane which comprises an aqueous solution of a cationic macromolecule having a weight average molecular weight of 100,000 or greater, wherein said cationic macromolecule is a polyvinylamidine, represented by the following formula [1]

• or a derivative thereof, wherein R1 to R4 represent a hydrogen atom or an alkyl grout, and a second agent for increasing rejection with a permeable membrane which comprises an aqueous solution of an anionic macromolecule having a weight average molecular weight of 100,000 or greater, and the permeable membrane is treated alternately with said first agent and then with said second agent or with said second agent and then with said first agent, wherein said treating is conducted by passing the first agent and then the second agent alternately through a module in which the permeable membrane is disposed or by passing the second agent and then the first agent alternately through a module in which the permeable membrane is disposed, or by dipping the permeable membrane into the first agent and then into the second agent alternately or by dipping the permeable membrane into the second agent and then into the first agent alternately, thereby the cationic macromolecule and the anionic macromolecule are adsorbed in the permeable membrane.