Methods for controlling a spinning membrane separator so as to limit fouling of the membrane by changing the rotation rate of the spinning membrane in response to the fouling rate, while maintaining a constant outlet cellular concentration. Increasing the spinner rotation rate will increase the strength of the Taylor vortices generated within the separator by the spinning of the membrane, which should reduce fouling of the membrane. The goal of the method is to rotate the spinning membrane at the slowest rate possible without unacceptable fouling. Two specific methods to control fouling are disclosed. In a first, unidirectional method, the spin rate of the membrane is only increased in response to undesirable fouling in order to prevent the fouling from continuing. In a second, bidirectional method, the spin rate of the membrane may be either increased or decreased in response to the measured fouling rate in order to maintain the fouling rate within a desired range.

Filtration systems and methods for removing a filter residue from a filter employed in filtering a liquid (for example, grey water). The filtration system may include a vessel having an inlet through which a liquid can be introduced during use and an outlet through which filtered clean liquid can exit. A filter configured to filter the liquid is disposed within the vessel between the inlet and the outlet. The filtration system may further include at least one transducer disposed on or adjacent to the filter. The at least one transducer may be configured to generate one or more pressure waves effective to dislodge at least some residue materials collected on an upstream side of the filter.

A method of operating a high velocity cross flow dynamic membrane filtration includes feeding a fluid stream into a pressure vessel, in which the vessel defines a treatment chamber containing a disc membrane assembly having a first support shaft and a second support shaft, each support shaft defining a longitudinal axis about which is positioned a plurality of axially spaced membrane discs. The method further includes distributing the fluid stream over at least a portion of the disc membrane assembly. The method also includes discharging a first portion of the fluid stream from the vessel and discharging a second portion of the fluid stream from the vessel. The method additionally includes rotating the first support shaft and the second support shaft in a first direction. The rotating includes modulating a rotation rate in response to the flow rate of the second portion of the fluid stream.

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.

An osmotic process comprising for a first period, passing a draw stream and a feed stream through an osmotic unit having a semi-permeable membrane, permitting the passage of water but not salts. The feed stream is an aqueous stream with a lower salinity than the draw stream. The feed stream has a scalant with a concentration above saturation in a region on a feed side of the semi-permeable membrane. The draw stream passes over a draw side of the membrane and the feed stream passes over the feed side so water passes across the membrane from the feed stream to the draw stream. For a second time period, the flow rate of the draw stream is lower than the flow rate in the first time period, and the feed stream passes over the feed side such that the concentration of the scalant in said region is reduced.

A high velocity cross flow dynamic membrane filtration system includes a disc membrane assembly having a frame and at least two support shafts. Each support shaft defines a longitudinal axis about which is positioned a plurality of axially spaced membrane discs, with each shaft further coupled to the frame. A permeate tube is coupled to each support shaft and in fluid communication with the membrane discs associated with that support shaft. A vessel defines a treatment chamber and is configured to removably support the disc membrane assembly within the treatment chamber. The vessel further includes a wall. The filtration system also includes a drive system. The permeate tubes are configured to extend through a portion of the vessel wall when the disc membrane assembly is positioned within the treatment chamber. The permeate tubes are further configured for rotation by the drive system.

The invention relates to a method for fouling reduction and/or fouling removal and/or prevention of fouling in membrane based fluid-flow processes, such as ED, RED, EDR, CDI, fuel cells, filtration, flow batteries, and a device capable of performing such methods. The method comprises the steps of: providing a dynamic membrane stack with a number of membranes, the stack capable of changing the average inter-membrane distance between two adjacent membranes with the inter-membrane distance being the distance between the membrane surfaces of two adjacent membranes; performing the membrane based fluid-flow process in a first state with the stack having a first set of average inter-membrane distances; switching the membrane based fluid-flow process between the first state and a second state wherein the stack having a second set of average inter-membrane distances different from the first set; and performing the membrane based fluid-flow process in the second state, wherein, at least in an initiating phase, fouling is removed and/or reduced and/or prevented.

A desalination system (100) having an intake unit (110) providing seawater to a pre-treatment unit (120) connected to a reverse osmosis (RO) desalination unit (130) and a post treatment unit (150). The desalination system (100) is configured to operate without any external addition of chemicals to simplify logistics and regulation concerns. The units of the system are configured to prevent biofouling, scaling and corrosion by mechanical and biological means including high flow speeds, biological flocculation of colloids, and making the water entering the RO units inhospitable to bacteria and other organisms that cause biofouling, hence preventing their settlement and removing them with the brine. Recovery rate is lowered and energy is recovered to increase the energetic efficiency and minerals that are added to the product water are taken from the brine.

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.

A system and method are provided for controlling fouling and complement protein activation during separation of plasma from whole blood using a spinning membrane separator. The separator includes a pair of relatively rotating surfaces spaced apart to define a gap therebetween, with at least one of the surfaces comprising a membrane that allows plasma to pass therethrough but substantially prevents the passage of red cells. In accordance with the method, the membrane material and membrane fabrication technique are selected so as that the resulting membrane both resists fouling and complement protein activation. In a specific embodiment, the membrane is has a smooth surface and substantially linear pores. The pores have a nominal diameter of less than 2 microns (so as to exclude platelets) and preferably a diameter of from 0.6 microns to 0.8 microns, as may be obtained by use of track-etching. In addition, the membrane material preferably is polycarbonate, as it has been determined that polycarbonate does not activate complement proteins.