Objective :- Remove/Reduce the Total Dissolved Solids (TDS) from water/treated effluent under high pressure (at about 10-15 kg/cm2) through membrane.

Permeate recovery with RO / Recovery of Pure Water :

Varies from 30% to 70% of the total feed water quantity which greatly depends on

• Constituents of water (Organic, Inorganic), • Expected years of Operation, • Type of membrane (Low Fouling, Sea water, High/Low Pressure etc.), • Combination of R.O. process (Stages, passes, recycling, Blending) • Number of R.O. modules & size.

Therefore complete analysis of water/ effluent after tertiary units is necessary.

Pre Treatment : Most necessary before allowed to pass through the membrane to prevent Bio-fouling of membrane & Scaling of membrane which is the cause of failure of R.O. membrane.

Fouling of membrane : is due to Organic Content & Suspended Solids, could be prevented with proper filtration i.e. micro filtration and ultra filtration.

Scaling of membrane : is due to the carbonate and sulphates of calcium, magnesium (i.e. Hardness).

Therefore it is necessary to soften the water prior to passing through the R.O. membrane.