TM 10-4610-241-10
TO 40W4-13-41
Section III. TECHNICAL PRINCIPLES OF OPERATION
Page
System Technical Principles of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-19
Component Technical Principles of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1-12. SYSTEM TECHNICAL PRINCIPLES OF OPERATION.
a.
General. The ROWPU removes suspended solids (called turbidity), chemicals, and solids held in solution
(called dissolved solids), found in most fresh water and seawater sources to a level fit for human
consumption. This is done by filtering, reverse osmosis, and treating the water with selected chemicals.
b.
Reverse Osmosis. Reverse osmosis is the process by which purified water is separated from the available
fresh, seawater, or brackish water sources. High pressure is applied to the raw water side of a
semipermeable membrane and desalinated product 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. elements. The R.O. elements separate this water stream into a
product water stream and a brine concentrate stream, both of which continuously flow away from the
membranes through the R.O. pressure tubes. About 10 gallon of product water is produced for every 30
gallon of raw water processed.
C.
Water Processing. Water flowing through the ROWPU is processed as follows:
CAUTION
Petroleum contaminated raw water will damage R.O. elements, multimedia filter and
cartridge filter.
(1)
First Stage of Filtration - Multimedia Filter. The multimedia filter is the first stage of filtration.
Large particles of suspended solids are removed by the various layers of filter material in the tank.
Polymer, added to the raw water by the chemical feed pump, collects suspended solids into groups
large enough to be removed by the multimedia filter in a process called coagulation.
(2)
Second Stage of Filtration - Cartridge Filter. The cartridge filter removes finer suspended solids
that pass through the multimedia filter.
(3)
Reverse Osmosis (R.O.). The R.O. elements remove dissolved solids from the water and any
suspended solids that may have passed through the multimedia and cartridge filters.
(4)
Chemical Injection - Chemical Feed Pump). The chemical feed pump is comprised of four liquid
heads which inject chemicals into the water system. Polymer is injected into the raw water before
entry into the multimedia filter. Polymer aids in the removal of suspended solids by the
multimedia filter through a process called coagulation. Sodium hex is injected into the raw water
to reduce scaling and corrosion of pipes, pumps and filters caused by hard water deposits.
Chlorine is added to the product water to reduce bacteria and make the water safe for
consumption. Citric acid is injected downstream of the multimedia filter to remove scale deposits
that build up on the R.O. elements and maintain pH.
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