Preferably, the pH during the reverse osmosis separation membrane treatment is 7 or greater.

Concentrated water produced by the semi-permeable membrane separation treatment (2) is biologically treated and is further subjected to solid-liquid separation to purify the concentrated water.

A process for treatment of water via membrane separation equipment (Fig.2).

The process of membrane separation is based on the use of semi-permeable membranes.

Methods and systems for monitoring and/or controlling membrane separation systems or processes are provided.

The selective removal is effected by a membrane separation process for example a pervaporation or a vapour permeation process.

The membrane separation process is based on the presence of semi permeable membranes.

As an additional advantage, the membrane separation step (305) generates a hydrogen - rich stream (307) which can be sent for other uses.

The membrane separation process is based on the presence of semi-permeable membranes.

The electrocatalysis composite membrane (3) has automatic cleaning function and can achieve non-contaminating operation during membrane separation.

A feedwater (10) is maintained or adjusted to a pH of 4.3 or lower, and fed to a membrane separation system.

By utilizing low pressure separation, highly selective membranes can be used and recycling becomes practical.

Separation is by membrane separation at low pressures.

The primary treated water is then subjected to cross flow-type semi-permeable membrane separation treatment (2) to obtain a purified water.

A membrane separation process (1) for treating a gas stream (3) containing methane and nitrogen, for example, natural gas.