Apparatus and method for semi-permeable membrane cleaning in particular, applying series of pulsed water stroke, made simultaneously with osmosis backward flow causing superposed membrane directional shaking and fouling detachment. Pulsed water stroke provided by water stroke generator as several momentum sharp changes in gauge pressure and induce velocity pulse of residual brine flow. The pulsed water strokes ideally induce resonance in the membrane. Osmosis backward wash may be provided either by injection for predetermined injection time, additional solution selected in such way that net driving pressure be-comes opposite to normal osmotic operation thereby providing a backward flow of permeate towards to the side opposite to normal operation mode, so as to lift said foulant, or by throttling permeate exiting from the permeate enclosure, until the net driving pressure value become equal to zero, during application of precise synchronized and opposing brine and permeate pressure strokes thereby providing a plurality of quick RO-FO-RO process changes. These procedures allow a membrane to be kept continuously clean and operate at higher recovery.

Apparatus and method for semi-permeable membrane cleaning in particular, applying series of pulsed water stroke, made simultaneously with osmosis backward flow causing superposed membrane directional shaking and fouling detachment. Pulsed water stroke provided by water stroke generator as several momentum sharp changes in gauge pressure and induce velocity pulse of residual brine flow. The pulsed water strokes ideally induce resonance in the membrane. Osmosis backward wash may be provided either by injection for predetermined injection time, additional solution selected in such way that net driving pressure becomes opposite to normal osmotic operation thereby providing a backward flow of permeate towards to the side opposite to normal operation mode, so as to lift said foulant, or by throttling permeate exiting from the permeate enclosure, until the net driving pressure value become equal to zero, during application of precise synchronized and opposing brine and permeate pressure strokes thereby providing a plurality of quick RO-FO-RO process changes. These procedures allow a membrane to be kept continuously clean and operate at higher recovery.

There is provided a system for the removal of scaling precipitants obtained due to dewatering a solution including i. at least one membrane, such as FO membrane adapted to be at least partially surrounded by a feed solution and to receive a flow through of a draw solution; and ii. a device adapted to control the flow of said draw solution through said at least one membrane; wherein said system is configured to operate in at least three predetermined different modes of operation including; filtration mode, osmotic relaxation mode and pulsation mode, according to some demonstrative embodiments.

Separation processes using osmotically driven membrane systems are disclosed generally involving the extraction of solvent from a first solution to concentrate solute by using a second concentrated solution to draw the solvent from the first solution across a semi-permeable membrane.

Disclosed herein are apparatuses and methods for semi-permeable membrane cleaning. In particular, a pressure retarded osmosis (PRO) process redirects raw solution and fluid streams in such a way as to cause periodic changes of the process from PRO to reverse osmosis (RO) for lifting and detaching fouling. Further disclosed is applying, at least periodically, a pulsed-flow regime in the fluid stream, thereby causing increased shearing force for enhanced evacuation of the foulant. Additionally, a backward wash may be provided by injection, for a predetermined injection time, of additional solution selected in such way that net driving pressure becomes RO opposite to normal PRO operation, thereby providing a backward flow from a first side of the membrane to a second side of the membrane, so as to lift and evacuate foulant.

Disclosed herein are apparatuses and methods for semi-permeable membrane cleaning. Specifically, a pressure retarded osmosis (PRO) process redirects raw solution and fluid streams in such a way as to cause periodic changes of the process from PRO to reverse osmosis (RO) for removing fouling. Further disclosed is applying a pulsed-flow regime in the fluid stream, thereby causing increased shearing force for enhanced foulant evacuation. Additionally, a backward wash may be provided by injection of additional solution such that net driving pressure becomes RO as opposed to PRO, thereby providing a backward flow from a first side of the membrane to a second side. Further disclosed are phased operations that resolve the issue of self-extinguishing PRO, thereby providing energy savings and/or PRO process optimization by, for instance, (1) utilizing osmotic pressure for circulation, (2) variation in POp gauge pressure, and/or (3) variation of the ratio of Additional Solution to Draw Solution.

Periodically operating a forward osmosis (FO) semi-permeable membrane element in reverse osmosis (RO), to yield product extraction on a feed side of the membrane, to flush out a concentration polarization (salt concentration of the feed side and dilution of draw solution on the draw side) across the membrane. Utilizing treated waste water to generate the flushing solution of low osmotic pressure, and gauge pressurizing the flushing solution to the gauge pressure of the draw solution to keep a constant gauge pressure of the solutions. FO process is interrupted every 5-20 minutes for a 10-60 seconds long flushing RO process, thereby increasing the FO throughput five fold and recovering power from the increased throughput, i.e. from the osmotic pressure of the brine.