Reverse Osmosis for Water Softening

A reverse osmosis system for seawater desalination with improved efficiency, reduced maintenance and easier membrane replacement. The system uses a two-stage reverse osmosis arrangement with interstage pressure exchange. The first stage has reverse osmosis membranes in a vessel. Seawater is pumped in, filtered, and moves to a second stage with more membranes. Between stages, a transport space guides water. Pressure exchangers connect to feed, outlet, and transport. They exchange pressure between feed water and transport water, diluting it for the second stage. This recovers pressure energy. The two-stage design reduces front-end membrane load, extends membrane life, and enables easy replacement.

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Desalination system that uses nanofiltration (NF), reverse osmosis (RO) and forward osmosis (FO) techniques to produce pure water from seawater or other sources of a solute solution or salt-contaminated water. The system includes a feed side, a permeate side, and a reverse osmosis desalination unit.

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Seawater desalination system that reduces maintenance costs by easily replacing reverse osmosis membrane units or vessels. The system includes a barrel in which a plurality of vessels receiving reverse osmosis membrane units may be arranged; a feed tank provided in an intermediate portion of the barrel and connected to a seawater inlet; a first water tank provided inside a first end portion of the barrel and connected to a plurality of first vessels connected to a first side of the feed tank; and a second water tank provided inside a second end portion of the barrel and connected to a plurality of second vessels connected to a second side of the feed tank.

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A simplified and compact reverse osmosis pretreatment system for high hardness water that reduces hardness levels to meet reverse osmosis requirements. The system consists of four main components: chemical crystallization granulation, solid-liquid separation, filtration, and polyceramic ultrafiltration. This allows effective removal of hardness, particularly carbonate, without the complexities and issues of traditional lime treatment or double-alkali softening. It provides a simpler, more automated, space-saving, and environmentally friendly option for high hardness water reverse osmosis pretreatment.

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A method to improve efficiency and reliability of reverse osmosis desalination of saline water by reducing concentrate consumption and utilizing it. The method involves softening the saline water before desalination using a small amount of caustic soda. This reduces the amount of calcium and magnesium ions in the water that can foul the reverse osmosis membranes. This allows using a lower operating pressure, reducing the concentrate flow and making it easier to utilize. The softened water is then desalinated by reverse osmosis.

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Composite RO membranes with improved properties for reverse osmosis desalination and purification of water. The membranes are made by interfacial polymerization using acacia gum as an additive. The acacia gum increases pore size, hydrophilicity, and surface charge and reduces roughness compared to pure polyamide membranes. This leads to higher membrane flux and reduced fouling while maintaining salt rejection. The composite membranes show improved performance and stability in filtration tests with seawater compared to commercial membranes.

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Efficient and economical desalination system with zero liquid discharge that reduces product cost, brine volume, and energy consumption compared to conventional desalination. The system uses a two-stage process with a nano-filtration (NF) membrane followed by reverse osmosis (RO). The NF removes divalent ions from the feed water before RO, preventing scaling and allowing higher recovery. This reduces brine volume compared to direct RO. The concentrated NF brine can also have commercial applications. The overall process has lower energy requirements than direct RO due to the lower TDS levels from NF.

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A reverse osmosis water filtration system to efficiently remove hardness from water. The system uses three tanks: a boiling tank, a condensation tank, and a reverse osmosis filtration tank. Boiling the water in the first tank to evaporate hardness-causing minerals, then condensing the vapor in the second tank to separate the purified water. The condensed water is fed to the reverse osmosis filter in the third tank to remove any remaining impurities. This multi-stage process provides a more effective hardness removal compared to directly filtering hard water with a reverse osmosis membrane.

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Direct drinking water system with multi-stage filtration and purification to produce high-quality, healthy drinking water. The system includes stages of compressed carbon filter, media filter, water softening, reverse osmosis (RO) membrane, and UV sterilization. This multi-stage filtration removes impurities, softens water, removes contaminants, and further purifies through RO and UV to provide direct drinking water that meets World Health Organization standards for healthy water.

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A high-hardness brackish water desalination system that can effectively treat water with high hardness levels without blocking reverse osmosis membranes. The system uses a staged chemical dosing and mixing process to soften the water before reverse osmosis. The process involves pumping high-hardness brackish water into a regulating tank, then pumping it to a reaction tank where NaOH and Na2CO3 are dosed. A flocculant is also dosed. The reaction tank overflow goes to a circulating tank. This softened water is then fed to reverse osmosis for desalination. The stages of chemical dosing and mixing help remove the hardness components before reverse osmosis, preventing membrane fouling.

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A water purifier with improved water purification rate and reduced scaling risk, particularly for areas with hard water. The purifier has multiple stages of filtration. Before reverse osmosis, the natural water is pretreated with a high molecular polymer composite filter to remove sediment, chlorine, and calcium/magnesium ions. This reduces scaling on the RO membrane by preventing calcium/magnesium crystallization. An ultrafiltration stage further traps non-directional agglomerated ions. This pre-filtration extends the life of the RO membrane in high hardness water with high recovery rates.

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Reverse osmosis concentrated water treatment device that reduces hardness without lime or soda ash. The device uses nanofiltration followed by multiple stages of Dow membranes to remove calcium and magnesium from reverse osmosis concentrate. The nanofiltration removes some impurities before the Dow membranes. The Dow membranes have multiple stages with intermediate pumps and recirculation to incrementally reduce impurities. This avoids using lime or soda ash for precipitation and has lower cost, smaller footprint, and higher recycling rate compared to traditional lime softening.

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A softened water treatment and recovery system for high hardness water sources that reduces scale buildup and prolongs membrane life. The system uses a multi-stage filter configuration with sand, activated carbon, softening, precision filtration, and reverse osmosis. A booster pump provides pressure for the filters. The softening tank has multiple stages and inclined bottoms to prevent scaling. The system also has sludge discharge valves, recovery tank, and a feed port for chemicals.

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A water treatment system that replaces traditional ion exchange water softeners using a combination of ultrafiltration (UF) and nanofiltration (NF) membranes. The system filters and softens water without adding salt or discharging chloride-rich waste. The UF unit removes particles, and the NF unit removes hardness ions like calcium and magnesium. The system has the UF unit upstream of the NF unit, with permeate from the UF fed to the NF. NF permeate is used to flush and backwash the UF and NF membranes. This allows continuous treatment without salt, unlike ion exchange.

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A water treatment device and method to reduce fouling and scaling in reverse osmosis membranes, enabling longer operation and reduced maintenance. The method involves using a sub-reverse osmosis membrane device with a lower operating pressure to filter the feed water before it enters the main reverse osmosis membranes. This traps foreign materials that can deposit in the main membranes. The sub-membrane device only filters, not desalinates, to limit fouling. Backwashing can be done by reversing feed flow through the sub-membrane. The method involves switching between normal operation and backwashing.

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Submerged forward osmosis desalination system for offshore applications that reduces the space requirements compared to traditional desalination systems on offshore platforms. The system uses submerged forward osmosis elements to desalinate seawater. The diluted draw solution from the forward osmosis elements is then further concentrated using reverse osmosis elements on the platform. This allows the bulkier forward osmosis elements to be submerged, saving space compared to having both forward osmosis and reverse osmosis elements on the platform.

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A symbiotic osmosis process using flat sheet membranes to improve seawater desalination recovery and power generation efficiency. The process involves cascading closed loop cells with differing salt concentrations connected by semipermeable membranes. Water is extracted from seawater in one cell and transferred through the membranes to a cell with lower salt concentration. This allows higher desalination recovery compared to traditional reverse osmosis. The concentration gradient between cells drives osmotic power generation. The closed loops prevent salt accumulation. The process can also be applied to hypersaline waters, brines, and wastewater recovery.

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Utilizing municipal water supply pressure to desalinate water without external energy sources using a venturi effect. The method involves connecting a pipe to a municipal water supply, adding a venturi arrangement with two nozzles and a branch, and using the vacuum created by the venturi effect to draw in contaminated water from one side. The vacuum suction is used to force the contaminated water through a reverse osmosis membrane on the other side to desalinate it. This allows desalination using only the municipal water supply pressure without any external energy sources.

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An integrated desalination system using a novel process flow configuration to improve efficiency and reduce costs compared to traditional desalination systems. The system uses a combination of microfiltration (MF), ultrafiltration (UF), and reverse osmosis (RO) membranes. The MF and UF stages are operated in parallel, followed by the RO stage, to provide pre-treatment for the RO. The MF and UF stages are optimized using techniques like backflush with brine and high salinity to reduce fouling. The system also uses a common pump for all stages and a programmable logic controller to switch configurations based on user selection. This allows flexibility in membrane choice and reduces costs compared to fixed systems.

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Seawater desalination system that efficiently heats seawater for reverse osmosis desalination in marine environments with low temperatures. The system uses multiple heat sources like engine waste heat, steam, exhaust gas, and recovered seawater heat to warm the feed water. This allows desalinating at temperatures as low as 5°C without freezing or performance degradation. The system also has temperature control valves to switch between heated and unheated feed streams based on seawater temperature.

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