Hành tinh của chúng tôi, trái đất hoặc gaia, là một nơi nước. nước chiếm 70% tổng số Eartha ™ diện tích, khoảng 360 10 12 m 2, và tổng lượng nước bao gồm các Eartha bề mặt là khoảng 1,40 10 18 m 3. Điều này làm cho trái đất một hành tinh hồ chứa nước rất lớn, tuy nhiên thực tế, những một lượng lớn nước không trực tiếp có thể sử dụng, như 97% nước này là nước biển của các vùng biển và đại dương mở và chỉ có 3% bao gồm nước ngọt và nước lợ, tức là 0,042 10 18 m 3 | D DESALINATION INTRODUCTION Our planet the earth or gaia is a water place. Water occupies 70 of the total earth s area about 360 X 1012 m2 and the total water volume that covers the earth s surface is about X 1018 m3. This makes the planet earth a very large water reservoir nevertheless practically these huge amounts of water are not directly usable as 97 of this water is the seawater of the open seas and oceans and only 3 consist of fresh and brackish water . X 1018 m3. From these fresh water reserves only a portion is in liquid form in rivers lakes and wells directly available to us for immediate use the rest can be found as glacier icebergs and very deep water of geological reservoirs. Fresh water for all of historical times has been an uncontrollable happening of nature wherever and however found. In the Bible good land is described as one of brooks of water of fountains and depths that spring out of valleys and hills for water is a precious source of development and civilization because water and civilization are two inseparable conceptions. From antiquity up to our times rivers seas oases and oceans have attracted man to their shores. As a rule towns and countries have grown along rivers. Egypt for example was considered as the gift of the river. Egypt is a typical historical example of the influence of water to the birth and development of a civilization. As a largely developed agricultural country Egypt was able to master the river and had most of the time such an abundant harvest that it became the main wheat-exporting country in the whole Mediterranean. The Egyptians learned to determine the seasons of the year by the behaviour of the river. Inundation Emergence of the fields and Drought were their seasons. The first calendar was created in this way and out of this was derived the modern calendar. Unfortunately fresh water and even seawater has not had our proper attention respect and treatment. Due to the increase of population .
