Device for membrane purification of a liquid

A membrane liquid purification device comprising:

• a liquid tank filled with a source liquid having a top layer and a bottom layer, said liquid tank having a top portion, a bottom portion, a source liquid outlet located within said top portion of said liquid tank, and a drainage liquid inlet located within said bottom portion of said liquid tank;
• a membrane liquid purification unit configured to purify said source liquid producing a purified liquid and a drainage liquid, said liquid purification unit having a source liquid inlet, a purified liquid line and a drainage liquid line connected to said drainage liquid inlet of said liquid tank;
• a liquid withdrawal means having a flexible tube with a first end and a second end, said second end of said flexible tube being connected to said source liquid outlet of said tank, said liquid withdrawal means further comprising a floating element connected to the first end of said flexible tube and positioned at a surface of said top layer of said source liquid within said liquid tank;
• a source liquid line connecting said source liquid outlet of said liquid tank to said source liquid inlet of said liquid purification unit;
• and
• a pressure increasing means disposed within said source liquid line between said source liquid outlet of said liquid tank and said source liquid inlet of said liquid purification unit, said pressure increasing means being configured to facilitate supply of said source liquid from said liquid tank to said liquid purification unit,
• wherein, when said pressure increasing means is activated, said source liquid flows from said surface of said top layer of the source liquid, through said flexible tube and said source liquid outlet of said liquid tank into the source liquid inlet of said liquid purification unit;
• wherein said liquid purification unit is configured to discharge said purified liquid through said purified liquid line and to discharge said drainage liquid through said drainage liquid line and through said drainage liquid inlet into said bottom portion of said liquid tank to be mixed with said bottom layer of said source liquid;
• wherein said floating element is configured to move vertically between said top portion of said liquid tank and said bottom portion of said liquid tank with said top layer of said source liquid while remaining at said surface of said top layer of said source liquid;
• and
• wherein said liquid purification unit is configured to automatically stop a liquid purification process said purification unit when said floating element at the surface of the top layer reaches a predetermined level.