Reverse Osmosis Desalination for Softening Hard Water

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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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 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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