REVERSE OSMOSIS

MAJOR MMWD REPORTS

The MMWD has published two major documents relative to their proposed reverse osmosis sea water desalination.

Click here to view their detailed Engineering Report. (This is a very large report. Do not go here unless you are really interested in detail that is not presented below - and are prepared to wait some time for this large report to download to your computer.)

The following simplified flow diagram of their proposed reverse osmosis desalination plant, taken from that report, is shown here for the readers convenience.

Click here to view their Environmental Impact Report, including links to its several detailed chapters.

FEED WATER SALINITY

The electric power required by the reverse osmosis process is related to the salinity of the feed water. MMWD proposes using pump pressures of 625 pounds per square inch (psi) when the water feed salinity is lowered to about 22,000 ppm by fresh water inlet from the Delta vs. pump pressures of 970 psi during draught years when the feed water is not diluted with fresh water and the salinity is near the salinity of ocean water.

FEED WATER TEMPERATURE

One option that MMWD apparently did not consider is that an increase of the feed water temperature decreases the viscosity of the water, allowing an increased flow rate through the semi-permeable membranes, thereby decreasing the pumping power. Such heating could rather easily be done by solar panels and an heat storage facility to allow heating use of heated saltwater 24 hours per day. Whether or not this would be valuable is not known since the economic trade-offs are unknown.