The diagram below shows how salt is removed from sea water to make it drinkable. Summarize the information by selecting and reporting the main features and comparisons where relevant.

The flow chart gives information about the process of producing clean

water

from saltwater so that it can be used for drinking.

Overall

, seawater has to follow four main steps to be drinkable, beginning with the pretreatment filter stage and ending with the storage stage. At

first,

water

that is

taken from the sea must go through the pretreatment step before filtration. Under high pressure, the treated

water

then

is forced through the membrane. The membrane only allows

water

molecules to pass,

thus

impurities and salt are eliminated. The waste of the first two steps, filter backwash, and seawater concentrate, are all given back to the sea

while

the main product is continued in

further

steps.

Subsequently

, the filtered

water

is post-treated with lime, chlorine, and fluoride in the third processing stage. The product of

this

final main step is drinkable

water

. Before being transferred into an integrated

water

supply system, clean

water

is stored in storage conditions.