an impure solution). Osmosis occurs in humans and is the means for nutrients to reach
and nourish cell tissue. Plants absorb food and moisture from the soiI in the same way
(see figure 1-16). Reverse osmosis is the process used to purify water. Separating
suspended and dissolved solids from fiItered water (or high concentrated solution) is the
process. This is done by forcing raw water under very high pressure against a thin fi1m
called a membrane. The membrane allows purified water to pass through leaving the
suspended, dissolved solids and salts stay on the other side. At the same time,
essentially all particles, including microorganisms and suspended colloids, are removed
(see figure 1-17). The Army has this equipment. The equipment is called the reverse
osmosis water purification unit.
Figure 1-16. Osmosis.
Figure 1-17. Reverse osmosis.
(1) Principles of operation. All of the reverse osmosis water purification
units or ROWPU incorporate the following technical principles of operation: The
ROWPU reduces the number of small particles, chemicals, and solids in solution (called
dissolved solids), found in most fresh water systems, dirty streams, and seawater, to a
level fit for drinking by humans (figure 1-18).