Systems and processes for purifying and concentrating a liquid feed stream are disclosed. In the systems, the concentrated liquid output from the high pressure side of a reverse osmosis stage is used as the draw solution in the low pressure side of the reverse osmosis stage in a configuration called osmotically assisted reverse osmosis. This reduces the osmotic pressure differential across the membrane, permitting high solute concentrations to be obtained, hastening the purification of the liquid. Reduced system pressures are also obtained by arranging multiple osmotically assisted reverse osmosis stages in a cross-current arrangement. Overall system energy consumption is reduced compared to conventional thermal processes for high concentration streams.

A wave-actuated system for desalination of water by reverse osmosis (RO) having a wave energy converter (WEC) subsystem and a RO desalination subsystem is disclosed. The WEC subsystem has a float, a reaction member, and a hydraulic cylinder connected between the float and the reaction member and defining first and second variable volume chambers The RO desalination subsystem has a RO cell containing a RO membrane and a flow smoothing device (FSD). During a first stroke of the WEC subsystem: the float moves in a first direction; and seawater is supplied from the first variable volume chamber to the RO cell and to the FSD. During a second stroke of the WEC subsystem: the float moves in a second direction; seawater is supplied from a seawater intake to the first variable volume chamber; and seawater is supplied from the FSD to the RO cell.

A reverse osmosis system and method of operating the same includes a membrane housing comprising a reverse osmosis membrane therein. The membrane housing has a feed fluid input, a brine outlet and a permeate outlet; The system further includes a charge pump, a plurality of valves and a tank having a volume comprising a movable partition dividing the volume into a first volume and a second volume. The plurality of valves selectively couples the charge pump to the first volume or the second volume and the brine outlet to the second volume or the first volume respectively.

An energy-saving water purifying system has a tube, two pistons, a movable component, a pump, and a filter. The two pistons are mounted in the tube. The movable component is moveably mounted between two block portions of the tube. Two magnetic elements are mounted on the movable component and repulse magnetic elements of the two pistons. The movable component selectively blocks one of two wastewater entrances of the tube. An outlet of the pump is connected to two check valves of the two inlets in parallel. An inlet of the filter is connected to two check valves of the two outlets in parallel. A wastewater exit of the filter is connected to the two wastewater entrances of the tube in parallel. The water purifying system is switched by magnetic force so that the structure is simplified, energy is saved, and cost and fault rate are decreased.

An apparatus for treating water or liquids in general, including a reverse osmosis filtration device provided with at least one inlet associated with a line for supplying the liquid to be treated, at least one outlet of the permeate associated with a line for dispensing the treated liquid and at least one concentrate outlet associated with a line for discharging the waste. The particularity of the present invention resides in that it includes, downstream of the filtration device, at least one tank that forms inside it two adjacent chambers with a mutually variable volume, in which one chamber is connected to the delivery line while the other chamber is connected to the discharge line.

A reverse osmosis system and method includes a pump pressurizing a feed stream, a first and second membrane array that generates permeate and brine streams. A first energy recovery device uses first energy from the second brine stream to pressurize the first brine stream. A first and second auxiliary and bypass valves are associated with the first and second energy recovery device. A second energy recovery device uses second energy from the second brine stream to increase a second pressure of the feed stream. A first flowmeter generates a first flow signal for the first permeate stream. A second flowmeter generates a second flow signal for of the second permeate stream. A third flowmeter generates a third flow signal for the second brine stream. A motor drives the first energy recovery device. A controller controls the in response to the flow signals.

Systems for water desalination are disclosed. The systems include a source of non-potable water, a low pressure nanofiltration device, a first electrodialysis unit, a second electrodialysis unit, and recycle conduits. Methods of water desalination including directing non-potable water to a low pressure nanofiltration device, a first electrodialysis unit, and a second electrodialysis unit are also disclosed. Methods of facilitating water desalination by providing a water desalination system are also disclosed.

The present application pertains to systems and methods for desalination. In one embodiment the system employs a first storage reservoir configured to be near the surface of a body of water and configured to store a low density fluid. A second storage reservoir is configured to be located below the surface of the body of water. A desalination system is operably connected to the second reservoir. Desalinated water is produced by allowing desalination permeate to displace low density fluid in the second reservoir and transfer the low density fluid from the second reservoir to the first reservoir. Desalinated water is exported by transferring low density fluid from the first reservoir into the second reservoir to displace desalinated water from the second reservoir into a water export pipeline.

A reverse osmosis desalination system has a combined displacement pump and displacement pressure recovery motor that propagate feed water with a structurally fixed recovery rate and structurally stabilized volume flow through continuously alternating discharging and recirculation intervals. Thereby enabled is an instantaneous discharge of the entire feed water concentrate and unmixed replacement with low salinity source water that intermittingly and effectively flushes the reverse osmosis membranes. This in turn provides for high recirculation peak salinity and recovery rate that are simple and reliably controlled without impairing membrane longevity.

A process for treating waste water, including the steps of extracting by forward osmosis treated water from a wastewater feed stream and transferring it to a saline draw stream, and extracting from the saline draw stream treated water by a reverse osmosis process.