to pass through it and not the others. In osmosis, there is a tendency for a liquid to go from an area of less
concentration to an area of more concentration through a semi-permeable membrane. Figure 1 shows the osmotic
process.
If pressure is applied to the concentrated solution, reverse osmosis will take place. The pressure causes a flow
through the semi-permeable membrane into the dilute solution. The semi-permeable membrane acts as a barrier to
ions and does not allow them to pass through into the dilute solution. When applied to water, this means that the
product water has a reduced total dissolved solids (TDS) content as a result of the passage of water molecules
through the membrane while the mineral ions are rejected. (Figure 2)
Note: Numbers used in these examples may not reflect those of your unit.
INTRODUCTION
3
REJECTION AND RECOVERY
Feed water entering the system is split into two streams, a product stream and a concentrate stream (Figure 3).
During the process of reverse osmosis, some of the water has its dissolved solids content reduced by approximately
96%. This high quality product water is sent to service.
FIG. 1
FIG. 2
The rest of the feed water contains the total dissolved solids removed from the product water, in addition to the
total dissolved solids already present in the feed water. This concentrate water is sent to drain.
The amount of total dissolved solids rejected by the system is expressed as a percentage. A 90% rejection means
that 90% of the total dissolved solids have been removed from the feed water by the system. To calculate the
percent rejection, use the following equation:
(Feed TDS - Product TDS)
Feed TDS
where Feed TDS is the total dissolved solids content of the water going into the system, and Product TDS is the
total dissolved solids content of the high quality product water.
Example - If the Feed TDS is 600 ppm and the Product TDS is 24 ppm.
(600 - 24)
600
The amount of high quality water recovered for use as a percentage of the water fed into the reverse osmosis system
is called percent recovery. Use the following equation to calculate percent recovery:
Product Water Flow Rate
Feed Water Flow Rate
FIG. 3
x 100 = % Rejection
x 100 = 96% Rejection
x 100 = % Recovery
MG10 R/O WATER FILTRATION SYSTEM
