TM 10-4610-240-10
TM 08580C-10/1
T.O. 40W4-13-21
1.10. REVERSE OSMOSIS (R.O.) PROCESS.
Reverse osmosis is the process by which purified water is separated from the available seawater or brackish water
source. Pressure is applied to the raw water side of a semipermeable membrane, and desalinated water diffuses through
the membrane to the freshwater side. The 600 GPH ROWPU is arranged so that prefiltered water is pumped under
pressure across the semi-permeable membranes, called R.O. membranes. The R.O. membranes separate this water
stream into a product water stream and a brine concentrate stream, both of which continuously flow away from the
membranes.
CAUTION
Source water must be free of chlorine. Chlorine will instantly destroy beyond repair the R.O.
elements. Destruction of the R.O. elements will make the ROWPU unable to meet its mission.
RAW WATER SOURCE (1). Any place you can get water.
STRAINER (2). A screen on the end of a suction hose to keep large particles that may clog or damage out of the pumps
and filters of the ROWPU.
RAW WATER PUMPS (3) (4). Two each 30 GPM electric motor driven, centrifugal, portable pumps which draw source
water through the strainer into the ROWPU under pressure. These pumps are normally connected in series.
POLYMER FEED PUMP (5). Adds polymer solution to raw water before it reaches multimedia filter to collect
suspended solids into groups large enough to be removed by the multimedia filter. (This process is called coagulation).
SODIUM HEX FEED PUMP (6). Feeds diluted sodium hex to raw water to prevent scaling of filters, housings and
pipes.
MULTIMEDIA FILTER (7). First stage of filtration. The multimedia filter contains six types of media: gravel, coarse
garnet, fine garnet, silica sand, anthracite, and plastic. The water flowing into the filter discharges into a baffle to
dissipate the velocity that could disturb the surface of the filter media. The water then flows through the filter and
underdrains leaving larger suspended solids behind. The media bed is backwashed when: the loss of head pressure
through the filter bed increases above a certain level; or the quality of the water flowing out fails to meet standards.
BOOSTER PUMP (8) Stabilized, centrifugal-type pump draws water from multimedia filter through the cartridge filter.
The booster pump increases the water pressure for the second stage of filtration.
CARTRIDGE FILTER (9). Second stage of filtration. This filter removes finer suspended solids that pass through the
multimedia filter by entrapment of the particles on the fibrous cylindrical material. The cartridge filter contains eight 40"
spiral type filter tube elements. Cartridge filter elements should be replaced when cartridge filter gage differential
pressure rises above 40 psid.
R.O. PUMP (10). High pressure (500 to 1000 psi), positive displacement pump supplies pressure to the R.O. vessels
so that R.O. process can occur.
PULSE DAMPENER (11). A cylindrical shaped metal tank used to reduce pulses in water flow caused by pistons of
R.O. pump.
R.O. ELEMENTS (12). Semi-permeable type membrane utilized under pressure to separate dissolved solids (the
product water is forced through a membrane leaving dissolved solids on the membrane which are flushed out of the R.O.
elements as brine). There are 4 vessels which house a total of 8 R.O. elements.
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