Water treatment system and method

A method of treatment of liquid comprising:

• supplying at least one water treatment module including at least one membrane and having a feed water inlet at a feed side of said at least one membrane, a permeate outlet at a permeate side of said at least one membrane and a brine outlet at a brine side of at least one membrane;
• pressurizing feed water supplied to said feed water inlet by employing a pump which normally maintains a fixed output feed water volume notwithstanding variations in water pressure at an outlet thereof, the energy consumption of said pump being a function of the variations in water pressure at said outlet;
• monitoring the water pressure at said outlet of said pump;
• and
• when a predetermined high pressure threshold is reached at said outlet of said pump, immediately making changes in the water supply to said module, thereby to cause immediate lowering of the water pressure at said outlet of said pump, to a pressure below the osmotic pressure at the feed side of part but not all of said module, thereby immediately reducing the energy consumption of said pump, thereby providing an overall energy cost savings per unit of water treated.

A method for treatment of liquid in at least one liquid treatment module including at least a high pressure pump and a circulation pump, the method comprising:

• upon occurrence of an operational threshold representing exceedence of a salinity threshold in said at least one liquid treatment module, effecting the following:
• removing brine from the at least one liquid treatment module;
• and
• reducing, at an enhanced speed, pressure of said liquid in said at least one liquid treatment module by at least one of the following:
• opening a pressure reducing valve downstream of said high pressure pump;
• increasing the volume output of said circulation pump from its volume output when functioning as a concentrate circulation pump to a higher volume output when functioning as a feed water pump;
• and
• passing liquid from downstream of said high pressure feed pump to upstream of said high pressure feed pump.

A water treatment system comprising:

• at least one liquid treatment module operative to receive feed water at a water inlet thereof and to separate said feed water into permeate and concentrate, said permeate constituting treated water, said at least one liquid treatment module having a brine outlet for release of concentrate whose salinity is such that an operational threshold of said system is exceeded;
• a liquid pressure reducing valve at said brine outlet;
• a high pressure pump, operative to pressurize liquid to be treated received at a liquid feed inlet and to provide a pressurized feed water output to said at least one liquid treatment module;
• a feed water flow rate sensor located upstream of said high pressure pump and providing a feed water flow rate output;
• a pump controller receiving said feed water flow rate output and controlling the operation of said high pressure pump;
• a liquid pressure sensor for providing an output indication of liquid pressure at at least one of an inlet to said at least one liquid treatment module, an outlet from said at least one liquid treatment module and within said at least one liquid treatment module;
• a circulation pump which removes brine from said at least one liquid treatment module and supplies liquid to said water inlet;
• a liquid feed tank;
• a system controller receiving at least said output indication of liquid pressure within said at least one liquid treatment module, said system controller being operative, upon exceedance of a liquid pressure threshold in said at least one liquid treatment module, representing exceedence of a salinity threshold in the liquid therein, to reduce said liquid pressure in said at least one liquid treatment module by performing at least one of the following functions:
• opening said liquid pressure reducing valve at said brine outlet, thereby reducing said liquid pressure at said brine outlet to a level above atmospheric pressure which exceeds osmotic pressure of said liquid in said at least one liquid treatment module;
• increasing a liquid volume output of said circulation pump, which removes brine from said at least one liquid treatment module and supplies liquid to said water inlet from a liquid volume output at times other than upon and immediately following said exceedance;
• equilibrating liquid pressures between a liquid pressure inside said at least one liquid treatment module and inside said liquid feed tank;
• and
• opening a liquid pressure reducing valve at said liquid inlet, thereby providing a pressure reducing backflow liquid path from said liquid inlet of said at least one liquid treatment module which bypasses said high pressure pump upstream of said liquid inlet.

A water treatment system comprising:

• at least one water treatment module including at least one membrane and having a feed water inlet at a feed side of said at least one membrane, a permeate outlet at a permeate side of said at least one membrane and a brine outlet at a brine side of at least one membrane;
• a high pressure pump, which normally maintains a fixed output feed water volume notwithstanding variations in water pressure at an outlet thereof;
• a system controller receiving at least said output indication of liquid pressure within said at least one liquid treatment module, said system controller being operative, upon exceedance of a liquid pressure threshold in said at least one liquid treatment module, representing exceedence of a salinity threshold in the liquid therein, to reduce said liquid pressure in said at least one liquid treatment module by performing at least one of the following functions:
• pressurizing feed water supplied to said feed water inlet by employing said high pressure pump, the energy consumption of said high pressure pump being a function of the variations in water pressure at said outlet;
• monitoring the water pressure at said outlet of said high pressure pump;
• and
• when a predetermined high pressure threshold is reached at said outlet of said high pressure pump, immediately making changes in the water supply to said at least one liquid treatment module, thereby to cause immediate lowering of the water pressure at said outlet of said high pressure pump, to a pressure below the osmotic pressure at the feed side of part but not all of said at least one liquid treatment module, thereby immediately reducing the energy consumption of said high pressure pump, thereby provide an overall energy cost savings per unit of water treated.

A water treatment system comprising:

• at least one water treatment module including at least one membrane and having a feed water inlet at a feed side of said at least one membrane, a permeate outlet at a permeate side of said at least one membrane and a brine outlet at a brine side of at least one membrane;
• a high pressure pump, which normally maintains a fixed output feed water volume notwithstanding variations in water pressure at an outlet thereof;
• a pressure reducing valve downstream of said high pressure feed pump;
• a circulation pump;
• a system controller receiving at least said output indication of liquid pressure within said at least one liquid treatment module, said system controller being operative, upon exceedance of a liquid pressure threshold in said at least one liquid treatment module, representing exceedence of a salinity threshold in the liquid therein, to reduce said liquid pressure in said at least one liquid treatment module by performing at least one of the following functions:
• upon occurrence of an operational threshold representing exceedence of a salinity threshold in said at least one liquid treatment module, effecting the following:
• removing brine from the at least one liquid treatment module;
• and
• reducing, at an enhanced speed, pressure of said liquid in said at least one liquid treatment module by at least one of the following:
• opening said pressure reducing valve downstream of said high pressure feed pump;
• increasing the volume output of said circulation pump from its volume output when functioning as a concentrate circulation pump to a higher volume output when functioning as a feed water pump;
• and
• passing liquid from downstream of said high pressure feed pump to upstream of said high pressure feed pump.