41 results about "Reverse osmosis desalination" patented technology

The invention discloses a method and a system for co-processing rain sewage wastewater in the non-ferrous metal resource recycling industry, the rain sewage wastewater comprises rainwater, general production wastewater, acidic wastewater and acidic wastewater, and the method comprises the following steps: carrying out coagulating sedimentation, filtration and low-pressure reverse osmosis desalination treatment on the rainwater and the general production wastewater; concentrated water of reverse osmosis is used as a liquid preparation of lime milk of waste acid wastewater and acidic wastewater; the method comprises the following steps: carrying out vulcanization reaction on waste acid wastewater and acid wastewater, carrying out neutralization treatment with lime milk, softening, filtering, resin softening, reverse osmosis and evaporative crystallization treatment, taking evaporated steam condensate as reuse water, and carrying out resource utilization on salt obtained by evaporative crystallization. According to the invention, zero discharge of wastewater generated in the non-ferrous metal recovery process can be realized, no wastewater is discharged to the outside, and natural water and soil are ensured not to be polluted.

Systems for manufacturing reverse osmotic desalination membranes are described. The system is for the industrial scale manufacturing of carbon nanotubes supported reverse osmotic desalination membranes. The system overcomes several technological challenges and develops new membranes, improving aspects of membrane manufacturing and performance.

The invention belongs to the technical field of saline-alkali soil comprehensive treatment and circular agriculture, and particularly relates to a saline-alkali soil multi-stage circular agriculture system and method based on saline-alkali water multi-stage resource utilization. And efficient cyclic utilization of natural resources in saline-alkali areas is realized. The method mainly comprises the following steps: detecting saline-alkali water in a saline-alkali area, extracting the saline-alkali water for seawater-like regulation to obtain regulated saline-alkali water, desalting the regulated saline-alkali water through a reverse osmosis system to obtain fresh water and seawater-like water which are respectively used for crop planting and aquatic product culture, and recycling culture tail water after solid-liquid separation. By the adoption of the system and method, fresh water does not need to be supplied externally, the system is formed by itself, the win-win effect of ecological benefits, social benefits and economic benefits is achieved, green and sustainable development is achieved, and the system and method have universal popularization value for comprehensive development and utilization of saline-alkali soil.

The application belongs to the technical field of comprehensive management of saline-alkali land and circular agriculture, and particularly relates to a multi-stage circular agriculture system and method for saline-alkali land based on multi-stage resource utilization of saline-alkali water, which comprises the following steps: through the technical chain of terrace land reclamation, seawater-like regulation, reverse osmosis desalination, planting and breeding coupling and tail water circulation, efficient cyclic utilization of natural resources in the saline-alkali area is realized. The method mainly comprises the following steps: after the saline-alkali water in the saline-alkali area is detected, the saline-alkali water is extracted for seawater-like regulation, the regulated saline-alkali water is obtained, and then the saline-alkali water is desalinated through a reverse osmosis system, and fresh water and seawater-like water are obtained, which are used for crop planting and aquatic product breeding, respectively, and the breeding tail water is recycled after solid-liquid separation. The system and method have the advantages that the system does not need external supply of fresh water, is self-contained, achieves win-win of ecological benefit, social benefit and economic benefit, realizes green and sustainable development, and has universal popularization value for comprehensive development and utilization of saline-alkali land.

The application discloses a kind of high-salinity wastewater reverse osmosis desalination recovery processing equipment and recovery processing method, equipment includes shell, is arranged in the reverse osmosis component of shell interior and is arranged in the backwashing component of shell interior;Reverse osmosis component includes the water inlet head and end cap of joint in shell, is arranged between the cylinder of water inlet head and end cap, is set in the reverse osmosis membrane of cylinder and is set in the water outlet pipe of reverse osmosis membrane interior;Backwashing component includes the conversion pipe of joint in each water outlet pipe, with the backflush water inlet pipe of cylinder connection and is arranged in the electric push rod of shell interior and provides power for conversion pipe;The equipment of the application is pretreated to high-salinity wastewater, then carries out reverse osmosis treatment, realizes the depth desalination treatment of high-salinity wastewater, by evaporation crystallization treatment to reverse osmosis concentrated water, realizes the recycling of salt in high-salinity wastewater.

The invention discloses a shale gas produced water desalination system regulated and controlled by a dynamic electric field, which comprises an electrochemical hardness removal unit (11), a microfiltration interception unit (13), a reverse osmosis desalination unit (12) and a controller (10), the electrochemical hardness removal unit (11), the microfiltration interception unit (13) and the reverse osmosis desalination unit (12) are sequentially arranged along the inflow direction, the electrochemical hardness removal unit (11) is used for removing hardness components in water through a dynamic electric field, the microfiltration interception unit (13) is used for intercepting precipitates and suspended particles, and the reverse osmosis desalination unit (12) is used for reducing salt; and the controller (10) is respectively connected with the electrochemical hardness removal unit (11) and the reverse osmosis desalination unit (12) and is used for dynamically adjusting the polarity of an electrode so as to relieve membrane pollution in an electric field transformation mode. The invention solves the problems of low efficiency and serious membrane pollution caused by hardness removal and desalination separation in the traditional shale gas produced water treatment process.

The application provides a membrane seawater desalination system for large temperature difference and a control method, the membrane seawater desalination system for large temperature difference comprises a water supply module, a high-pressure module, a reverse osmosis desalination module, an energy recovery module and a PLC controller, the high-pressure module comprises M sets of high-pressure pump groups arranged in parallel, the high-pressure pump group comprises a booster high-pressure pump and a high-pressure pump arranged in series along the water flow direction; the energy recovery device has N sets of energy recovery devices corresponding to the reverse osmosis devices in the reverse osmosis desalination module one by one, wherein M < N; each set of energy recovery device is matched with one energy recovery booster pump and one second water supply pump simultaneously. The first water supply pump, the second water supply pump, the high-pressure pump, the booster high-pressure pump, the energy recovery booster pump and the low-pressure circuit and the high-pressure circuit are optimally combined, so that the number of high-pressure pumps and the use of high-power frequency converters are reduced, the investment cost is reduced, and the system operation efficiency and the safety redundancy are improved.

The present invention discloses a reverse osmosis desalination plant scheduling method that takes into account the pressure-delayed osmosis process, comprising the following steps: 1) obtaining basic parameters of the desalination plant; 2) modeling the desalination process based on the basic parameters to obtain a desalination plant equipment unit model; 3) establishing desalination plant operation constraints based on the basic desalination plant equipment unit model; 4) constructing an overall desalination plant scheduling model based on the desalination plant equipment unit model and the desalination plant operation constraints; and 5) solving the overall desalination plant scheduling model to obtain an optimized desalination plant scheduling plan. The present invention provides a reverse osmosis desalination plant scheduling method that takes into account the pressure-delayed osmosis process, enabling a more efficient and environmentally friendly desalination process.

The application discloses a ZIF-8-NH2 doped bridge organic silicon reverse osmosis membrane and a preparation method thereof. The membrane is prepared by doping ZIF-8-NH2 metal organic framework material into polymeric organic silicon sol, and forming a ZIF-8-NH2 / organic silicon hybrid membrane on the surface of a prefabricated ceramic support by a rubbing coating method. The ZIF-8-NH2 / bridge organic silicon membrane prepared by the application has high water permeability and high salt retention rate (NaCl retention rate is greater than 99.2%) in reverse osmosis desalination application, and the membrane structure is stable in the process of treating high-salt wastewater with TDS greater than 7 wt%.

The present invention relates to an underwater pumping device and method capable of moving over the seabed and of converting wave energy into high-pressure seawater pumping action for reverse osmosis desalination. The invention makes it possible to transform wave motion into linear motion by means of surface floats and an underwater float oscillating with the waves. The floats drive pistons that draw in, filter, and compress seawater. The movable pumping device is capable of positioning itself in synchronisation with the period and celerity of the waves by sliding by means of an anchoring system rolling on a conveying pipeline that carries the pumped water directly to a reverse osmosis station. The pipeline is anchored to the seabed by means of a series of deadman anchors. The sliding mechanism makes it possible to retrieve and remove the pumping device from the water for weather-risk prevention and for cleaning and maintenance.

The application discloses a deep degradation TOC-based integrated ultrapure water preparation device, which comprises a pretreatment unit, a reverse osmosis desalination unit, a high-level oxidation TOC deep degradation unit, a terminal refining unit and an intelligent monitoring and control unit integrated in the same pry cabinet; the pretreatment unit removes suspended solids, colloids and large-particle impurities in the water and adjusts the pH value of the water; the reverse osmosis desalination unit is connected with the pretreatment unit and removes salt, organic matter and microorganisms in the water; the high-level oxidation TOC deep degradation unit is connected with the reverse osmosis desalination unit; and the terminal refining unit is connected with the high-level oxidation TOC deep degradation unit. Compared with the prior art, the application has the advantages that the deep degradation TOC-based integrated ultrapure water preparation device and method are provided, which realizes efficient and deep removal of TOC through the coupling of high-level oxidation, membrane separation, ion exchange and real-time monitoring technology, and realizes the high integration and intelligent operation of the device.

The present application relates to the technical field of renewable energy development and seawater desalination, and discloses a deep-geological-ocean energy coupling utilization system and a running method. The system comprises a seawater taking unit, a horizontal full-pipe pressure flow transmission pipeline, a hydraulic power generation unit, a seawater desalination unit and a deep well group unit, and is sequentially connected to form a closed loop through the deep well-pipeline combination constructed by a deep-geological engineering. The present application forms a stable triangular hydraulic distribution along the whole pipeline by artificially setting a water head difference, thereby ensuring that multiple water turbines independently work and power is stably superimposed. The present application can realize long-distance water transmission through the deep well-pipeline, utilize natural energy to assist seawater desalination, and drive reverse osmosis desalination by using the high water head pressure energy of the deep well to generate power. Surplus power can be sent out.

A method of desalinating water, including the steps of when electricity costs between a first predetermined price and a second predetermined price, fill water is pumped into a reverse osmosis desalination unit to yield desalinated permeate and saltwater having a first salinity, when electricity costs less than the first predetermined price, fill water is pumped into a reverse osmosis desalination unit to yield desalinated permeate and saltwater having a second salinity, and when electricity costs greater than the second predetermined price, pure water is flowed into a reverse osmosis unit to yield pressurized saltwater which is run through a turbine to generate electricity. The first salinity is lower than the second salinity.

The invention discloses a preparation method and application of an in-situ cross-linked graphene oxide-hybrid silicon reverse osmosis membrane. The preparation method comprises the following steps: adding a graphene oxide nanosheet into an alcohol solution, carrying out centrifugal treatment to replace the graphene oxide nanosheet into an alcohol phase, adding a hybrid silicon precursor, carrying out primary cross-linking, and carrying out water bath stirring to obtain composite sol; adding a hybrid silicon precursor into the composite sol, mixing, adding an acidic catalyst and water, and carrying out an in-situ cross-linking reaction to prepare a polymerized sol; and coating a ceramic support body with the polymerized sol by a hot wiping method, and calcining to obtain the in-situ cross-linked graphene oxide-hybrid silicon reverse osmosis membrane. The graphene oxide / organic silicon composite matrix reverse osmosis membrane prepared by the invention shows excellent structural stability when being applied to 120h continuous reverse osmosis desalination, and the water permeation flux (greater than or equal to 5.03 * 10 <-8 > mol / m < 2 > h Pa) and the salt rejection rate (NaCl: greater than or equal to 97.59%) are achieved.

This invention is applicable to the field of oilfield wastewater treatment and provides a method for efficient reuse of oilfield wastewater in boilers based on high-temperature resistant membranes and reverse osmosis. The method includes the following steps: pretreatment conditioning: controlling the wastewater temperature at 50-80℃ and adjusting the pH to 10.5-11.5; using a high-temperature resistant special filter membrane for oil removal, suspended solids removal, hardening removal, and silica removal; two-stage anti-fouling reverse osmosis desalination; in this invention, by reducing the amount of chemicals added, the cost of chemicals is reduced by 40% compared to traditional processes, reducing dependence on chemicals and thus effectively lowering treatment costs and improving the economic benefits of oilfield wastewater treatment; by optimizing the treatment process, the amount of sludge generated is reduced, lowering the difficulty and cost of sludge treatment, and also reducing the potential environmental hazards of sludge.

The invention discloses a method for inhibiting a liquid spore microbial fertilizer from expanding a barrel, and belongs to the technical field of microbial fertilizers. According to the method, kitchen waste and agricultural and forestry waste are used as raw materials, the kitchen waste is treated through buffer solution soaking, physical adsorption oil removal and reverse osmosis desalination, and agricultural and forestry waste smashing and high-temperature disinfection pretreatment are combined; soil bacillus, bacillus licheniformis, bifidobacterium and lactic acid bacteria are added according to the proportion of 1%-10% of the total mass, are stirred and mixed by stages, are subjected to composting fermentation for 3-5 days at the temperature of 40-90 DEG C and the humidity of 30%-98%, and are finally mixed and air-dried with wood dust and plant ash to form a blocky fertilizer, so that the problems of barrel expansion, low resource utilization rate and poor soil improvement effect of a traditional bacterial fertilizer are solved, and the fertilizer is suitable for large-scale production. The method is suitable for saline-alkali soil improvement, arid regions and continuous cropping obstacle soil, and efficient resource utilization of waste is achieved.

The invention provides an ozone oxidation treatment system and treatment method for wastewater containing organic matters, and the treatment system comprises a nanofiltration unit which carries out nanofiltration on the wastewater to intercept divalent salt and part of the organic matters; the reverse osmosis unit is used for carrying out reverse osmosis desalination on the nanofiltration permeate; the nanofiltration trapped fluid ozone oxidation unit is used for performing ozone oxidation on the nanofiltration trapped fluid; the tail gas pressurizing unit is used for pressurizing the exhausted gas of the nanofiltration trapped fluid ozone oxidation unit; the reverse osmosis concentrated water ozone oxidation unit is used for performing ozone oxidation on reverse osmosis concentrated water of the reverse osmosis unit and a circulating concentrated solution of the concentration unit by adopting tail gas of the tail gas pressurization unit; the concentration unit is used for concentrating the effluent of the reverse osmosis concentrated water ozonation unit and returning part of concentrated solution to the reverse osmosis concentrated water ozonation unit while recovering fresh water; the tail gas washing unit is used for washing exhausted gas of the reverse osmosis concentrated water ozone oxidation unit; and the tail breaking unit is used for treating the exhaust gas of the tail gas washing unit, so that the exhaust gas reaches the standard and is discharged.

The invention discloses a saline-alkali soil remediation system, and belongs to the technical field of saline-alkali soil remediation. The water taking module pumps underground water and conveys the underground water to the desalting module, and the desalting module performs desalting treatment on the underground water and then separates out fresh water and concentrated water; fresh water is conveyed to the irrigation and planting module for planting and cultivation in the saline-alkali soil; concentrated water is conveyed to a salt separation module for concentration treatment, concentrated salt is conveyed to a salt recovery module, and an industrial-grade salt product is obtained after purification and drying. According to the method, a desalination-micro-irrigation-airing-salt separation system is established, namely, a reverse osmosis desalination device or an electro-adsorption desalination device is installed at an underground water pump opening, a desalination module is combined with a local micro-irrigation system, micro-irrigation is conducted through fresh water produced by the desalination device, and after the saline-alkali soil is irrigated with the fresh water for 3-5 years, the physical and chemical properties of the soil can be remarkably improved; the agricultural utilization is preliminarily realized.

The application discloses a kind of high salinity mine water zero discharge system and method thereof, system includes: first pressure exchange unit, reverse osmosis desalination concentration unit, first heat energy exchange unit, second pressure exchange unit, second heat energy exchange unit, pressure delayed osmosis unit and bipolar membrane electrodialysis unit, the renewable energy driving is used in the application, by introducing pressure delayed osmosis and double cycle geothermal power generation into conventional high salinity mine water zero discharge system, renewable energy energy supply is realized;In addition, by introducing bipolar membrane electrodialysis unit, the efficient use of inorganic salt and water resources is realized.

The present application belongs to the technical field of boiler make-up water treatment in thermal power plant, and discloses an intelligent control system and method for reverse osmosis device of boiler make-up water system in thermal power plant, which comprises the following steps: ultrafiltration water is sent into an ultrafiltration water tank for buffering, and is pressurized and transported by two parallel reverse osmosis water pumps; after being mixed, scale inhibitors, reducing agents and non-oxidizing bactericides are added by three mixers respectively; after being detected by a water quality sensing device, the water is sent into a security filter for filtration; after being filtered, the water is pressurized by a reverse osmosis high-pressure pump, and after being detected, the water is sent into two-stage reverse osmosis devices for desalination in turn, and the concentrated water is discharged after being converged; the produced water is converged to a produced water mother pipe, and after being detected, the unqualified produced water is discharged by a control valve, and the qualified produced water is sent into a reverse osmosis water tank for collection, so that the reverse osmosis desalination treatment of make-up water is completed, and efficient and stable control is realized.

The application discloses a non-ferrous metal resource recycling industry rain and sewage wastewater collaborative treatment method and system, the rain and sewage wastewater includes rainwater, general production wastewater, waste acid wastewater and acid wastewater, and the method comprises the following steps: coagulating and depositing, filtering, low-pressure reverse osmosis desalination treatment on the rainwater and the general production wastewater, and the concentrated water of the reverse osmosis is used as the dosing water of lime milk of the waste acid wastewater and the acid wastewater; the waste acid wastewater and the acid wastewater are subjected to sulfuration reaction, neutralization treatment with the lime milk, softening, filtering, resin softening, reverse osmosis and evaporation crystallization treatment, the steam condensate of the evaporation is used as the reused water, and the salt crystallized by the evaporation is used for resource utilization. The application can realize zero discharge of the wastewater generated in the non-ferrous metal recycling process, does not discharge any wastewater to the outside world, and guarantees that the natural water body and the soil are not polluted.

The invention relates to the technical field of reverse osmosis seawater desalination monitoring, and discloses a reverse osmosis membrane module conductivity value automatic cycle detection method and system, the reverse osmosis membrane module conductivity value automatic cycle detection method specifically comprises the following steps: receiving a high pressure pump operation signal, and only starting a detection program in a high pressure pump operation state; enabling the detected media at the plurality of membrane shell sampling points and the energy recovery device sampling points to sequentially enter a conductivity meter according to a preset sequence; performing data reading on the sampling points, comparing the measured conductance values of the sampling points with an alarm threshold value, and triggering alarm when the measured conductance values exceed the threshold value; and after detection of all sampling points is completed, automatic cyclic detection is carried out again. According to the invention, multi-point automatic monitoring can be realized, and performance abnormity of the membrane module can be found in time.

An assembly for reverse osmotically desalinating water, including a source containing feed water to be desalinated, a high-pressure tank having a first portion and a second portion and a movable piston wall operationally connected therebetween, a first portion inlet operationally connected to the first portion and a second portion inlet operationally connected to the second portion, a first portion outlet operationally connected to the first portion and a second portion outlet operationally connected to the second portion, a first valve having a first first valve inlet, a second first valve inlet, a first first valve outlet in fluidic communication with the first portion inlet and a second first valve outlet in fluidic communication with the second portion inlet, a high-pressure pump operationally connected to the source and to the first first valve inlet, a second valve having a first second valve inlet in fluidic communication with the first portion outlet and a second second valve inlet in fluidic communication with the second portion outlet and a second valve outlet, at least one reverse osmosis module having at least one reverse osmosis module inlet connected in fluidic communication with the second valve outlet, at least one brine outlet and at least one desalinated water outlet, a circulation pump having a circulation pump inlet port connected in fluidic communication with the brine outlet and a circulation pump outlet connected in fluidic communication with the second first valve inlet, and an electronic controller operationally connected to the first valve, to the second valve, to the high-pressure pump and to the circulation pump.

The present invention relates to a sequential circulation reverse osmosis desalination apparatus, and more particularly to a sequential circulation reverse osmosis desalination apparatus that employs closed-circuit reverse osmosis technology to ensure a fundamentally high recovery rate, and sequentially applies reverse reverse osmosis technology to reduce fouling, while performing highly efficient water treatment without a separate energy recovery device.

The utility model discloses a water quality improvement device for a silt dam, which comprises a sedimentation tank, a raw water tank, a pretreatment system, a reverse osmosis desalination system and a pure water tank, and the sedimentation tank is connected with the silt dam through a submersible pump; the raw water tank is connected with the sedimentation tank; the pretreatment system is connected with the raw water tank; the reverse osmosis desalination system is connected with the pretreatment system; the pure water tank is connected with the reverse osmosis desalination system. According to the device, the restriction problem that the silt dam water is high in salt content and poor in water quality and cannot be directly used for rural production and domestic water is solved, the desalting rate of the device is larger than or equal to 90%, the conductivity of the effluent water quality is smaller than or equal to 483us / CM, barium, magnesium, calcium and manganese are basically removed, and the requirement of the water quality basic control project limit value of the rural production and domestic water can be completely met; the sedimentation tank is provided with a deep tank and a shallow tank, so that the raw water pumped from the silt dam can be subjected to multi-stage sufficient sedimentation, and the service lives of the subsequent pretreatment system and the reverse osmosis desalination system can be prolonged.

The utility model discloses a reclaimed water recycling device suitable for hard and silicon-containing wastewater, which is used for reducing hardness, silicon, organic matter content and salt content in mixed sewage and comprises a softening silicon removal unit, a COD (Chemical Oxygen Demand) removal unit and a desalting unit, the softening and silicon removal unit is used for performing efficient precipitation or high-density precipitation on the mixed sewage; the COD removal unit is used for filtering and adsorbing the mixed sewage; the desalting unit is used for performing ultrafiltration and reverse osmosis desalting on the mixed sewage; the mixed sewage is connected to the softening and silicon removal unit, an outlet of the softening and silicon removal unit is connected to the COD removal unit through a neutralization water pump, an outlet of the COD removal unit is connected to the desalting unit through an intermediate water pump, a fresh water outlet of the desalting unit is used for producing reuse water reaching the standard for reuse, and a concentrated water outlet of the desalting unit is used for discharging high-salt-content concentrated water. The hardness, the silicon content, the organic matter content and the salt content in raw water are reduced through the softening silicon removal unit, the COD removal unit and the desalting unit as well as the auxiliary configuration of the dosing unit and the chemical cleaning unit.

The invention discloses a polar region seawater desalination treatment system, which relates to the technical field of seawater desalination, and comprises a pre-treatment unit, a primary filter, a secondary filter, an RO (reverse osmosis), a desalination water storage tank, a living water supply pipeline, a shell activated carbon filter and an ultraviolet disinfection water tank, a main industrial online water quality sensor for monitoring a water quality health value in real time is arranged in the desalination water storage tank; according to the method, a whole-distance closed loop of monitoring, decision making, execution, guarantee and pre-judgment is constructed by taking a water quality health value as a core, so that the core problem that the water quality of seawater desalination reaches the standard in a special environment is solved, and meanwhile, the energy limitation of a remote region is adapted through energy consumption optimization; through fault guarantee and remote operation and maintenance, the system is adapted to unattended scenes or scenes with inconvenient operation and maintenance; and through active pre-judgment and targeted treatment, continuous, stable and high-quality water supply in an extreme environment is ensured, and a safe, efficient, intelligent and reliable comprehensive water supply target is finally achieved.

The present application relates to the technical field of mine water treatment, and particularly relates to a method and system for step-by-step softening and silicon removal of coal mine water by a membrane method, comprising the following steps: A) coagulating and clarifying the coal mine water; B) removing calcium and softening and preliminarily removing silicon from the effluent obtained in step A); C) adjusting the pH value of the effluent obtained in step B) to 7.8-8.3 and then performing sterilization treatment; D) performing ultrafiltration and reverse osmosis desalination treatment on the effluent obtained in step C); E) removing magnesium and softening and deeply removing silicon from the reverse osmosis concentrated water obtained in step D); and F) performing filtration treatment on the effluent obtained in step E). The process adopted by the present application is short and efficient, calcium and magnesium ions can be recovered and utilized in steps, the softening and silicon removal effects are good, the membrane method treatment makes the system effluent reach the industrial and agricultural recycled water standards, and the subsequent combination with a deep treatment process can realize zero discharge of the coal mine water.

A method of desalinating water, including the steps of when electricity costs between a first predetermined price and a second predetermined price, fill water is pumped into a reverse osmosis desalination unit to yield desalinated permeate and saltwater having a first salinity, when electricity costs less than the first predetermined price, fill water is pumped into a reverse osmosis desalination unit to yield desalinated permeate and saltwater having a second salinity, and when electricity costs greater than the second predetermined price, pure water is flowed into a reverse osmosis unit to yield pressurized saltwater which is run through a turbine to generate electricity. The first salinity is lower than the second salinity.

The system comprises a wave energy converter comprising a moveable body 2 exposed to wave motion coupled to a seawater pump 6 adapted to pump seawater through a reverse osmosis desalination system. An