main membrane applications

Even if we only consider the membrane applications exclusive to the water treatment industry, the number of such applications is rising regularly and rapidly. In effect, if we refer to figure 50 of the section membrane separation, it is clear that, whatever the problem, pure water can always be extracted from any water-based effluent except, however, when it contains highly polarised and low molecular weight organic molecules (e.g. simple alcohols, ketones …). On the other hand, the energy costs, the danger of the membrane becoming fouled or of precipitation (scaling) and the cost of the membranes themselves continue to form major stumbling blocks ... that are gradually being overcome.

In effect, if we look at desalination membranes :

• during the 90’s, these membranes saw their price per m² almost halve;
• their permeability improved;
• for the same pressure levels, their salt passage decreased;
• the emergence of so-called "low pressure" membranes meant that the energy used to desalinate brackish water could be halved;
• the development of ever more efficient inhibitors meant that the scope of these membranes could be increased even further;
• …

And the very rapid development seen by the clarification membranes market since 1995 has been accompanied by the same improved efficiency and cost reduction.

Consequently, the following paragraph only quotes the major uses. Additional reference should be made to the chapters drinking water treatment and industrial processes and effluent treatment for further examples of the use of membranes in treatment lines applied to all types of water.