Pressure-reduced saline water treatment system

A pressure-reduced saline water treatment system, comprising:

• a first forward osmosis desalination unit having a feed side and a draw side;
• a second forward osmosis desalination unit having a feed side and a draw side;
• and
• a reverse osmosis desalination unit having a feed side and a permeate side,
• wherein the feed side of the reverse osmosis desalination unit is in fluid communication with the feed side of the second forward osmosis desalination unit, such that seawater drawn through the feed side of the second forward osmosis desalination unit is fed into the feed side of the reverse osmosis desalination unit,
• wherein the permeate side of the reverse osmosis desalination unit outputs product water extracted from the seawater, and the feed side of the reverse osmosis desalination unit outputs a reject stream,
• wherein the draw side of the second forward osmosis desalination unit is in fluid communication with the feed side of the reverse osmosis desalination unit, such that the draw side of the second forward osmosis desalination unit receives the reject stream and outputs a concentrated reject stream,
• wherein the draw side of the first forward osmosis desalination unit is in fluid communication with the draw side of the second forward osmosis desalination unit, such that the draw side of the first forward osmosis desalination unit receives the concentrated reject stream and outputs concentrated brine,
• wherein the feed side of the first forward osmosis desalination unit is in fluid communication with the feed side of the second forward osmosis desalination unit, such that the seawater flows through the feed side of the first forward osmosis desalination unit to and through the feed side of the second forward osmosis desalination unit,
• wherein the reject stream passes through the draw side of the second forward osmosis desalination unit at a higher osmotic and hydraulic pressure than an osmotic pressure of the diluted seawater fed through the feed side of the second forward osmosis desalination unit, and
• wherein the concentrated reject stream passes through the draw side of the first forward osmosis desalination unit at a higher osmotic and hydraulic pressure than an osmotic pressure of the seawater fed through the feed side of the first forward osmosis desalination unit.

A pressure-reduced saline water treatment system, comprising:

• a first forward osmosis desalination unit having a feed side and a draw side;
• a second forward osmosis desalination unit having a feed side and a draw side;
• a third forward osmosis desalination unit having a feed side and a draw side;
• and
• a reverse osmosis desalination unit having a feed side and a permeate side,
• wherein the feed side of the reverse osmosis desalination unit is in fluid communication with the feed side of the third forward osmosis desalination unit, such that seawater drawn through the feed side of the third forward osmosis desalination unit is fed into the feed side of the reverse osmosis desalination unit,
• wherein the permeate side of the reverse osmosis desalination unit outputs product water extracted from the seawater, and the feed side of the reverse osmosis desalination unit outputs a reject stream,
• wherein the draw side of the third forward osmosis desalination unit is in fluid communication with the feed side of the reverse osmosis desalination unit, such that the draw side of the third forward osmosis desalination unit receives the reject stream and outputs a first concentrated reject stream,
• wherein the draw side of the second forward osmosis desalination unit is in fluid communication with the draw side of the third forward osmosis desalination unit, such that the draw side of the second forward osmosis desalination unit receives the first concentrated reject stream and outputs a second concentrated reject stream,
• wherein the draw side of the first forward osmosis desalination unit is in fluid communication with the draw side of the second forward desalination unit, such that the draw side of the first forward osmosis desalination unit receives the second concentrated reject stream and outputs concentrated brine,
• wherein the feed side of the first forward osmosis desalination unit is in fluid communication with the feed side of the second forward osmosis desalination unit, such that the seawater flows through the feed side of the first forward osmosis desalination unit to and through the feed side of the second forward osmosis desalination unit,
• wherein the feed side of the second forward osmosis desalination unit is in fluid communication with the feed side of the third forward osmosis desalination unit, such that the seawater flows through the feed side of the second forward osmosis desalination unit to and through the feed side of the third forward osmosis desalination unit,
• wherein the reject stream passes through the draw side of the third forward osmosis desalination unit at a higher osmotic and hydraulic pressure than an osmotic pressure of the diluted seawater fed through the feed side of the third forward osmosis desalination unit,
• wherein the first concentrated reject stream passes through the draw side of the second forward osmosis desalination unit at a higher osmotic and hydraulic pressure than an osmotic pressure of the diluted seawater fed through the feed side of the second forward osmosis desalination unit, and
• wherein the second concentrated reject stream passes through the draw side of the first forward osmosis desalination unit at a higher osmotic and hydraulic pressure than an osmotic pressure of the seawater fed through the feed side of the first forward osmosis desalination unit.