An agent for cleaning an RO membrane, which includes an aldonic acid and/or a salt of an aldonic acid, removes effectively foulants that cannot be sufficiently removed with conventional cleaning agents when an RO membrane used for water treatment. In a method for cleaning an RO membrane with the cleaning agent or the cleaning liquid, while the detachment and hydrolysis effects are achieved by performing cleaning under alkaline conditions, chelation of heavy metals is caused by the aldonic acid and/or the salt of an aldonic acid. When an anionic surfactant is used in combination with the aldonic acid and/or the salt of an aldonic acid, the anionic surfactant causes the detachment of foulants. When a polyol having a molecular weight of 1000 or less is used in combination with the aldonic acid and/or the salt of an aldonic acid, the polyol causes wetting and swelling of foulants.

Apparatus for purifying a liquid, which comprises a container housing multiple closed cells, each delimited by an anionic membrane and by a cationic membrane, and multiple open cells, susceptible of being traversed by a liquid to be treated and each interposed between two adjacent closed cells. The apparatus also comprises two electrodes which are supplied with supply voltages with reversed polarities in order to push the ionized particles of the liquid into the closed cells during an operating phase, and in order to bring the ionized particles back into the open cells during a regeneration phase. The apparatus also comprises a polymer substance having functional groups with non-zero electric charge, which is contained inside the closed cells in order to create chemical bonds with the ionized particles of the liquid that enter therein.

An example water purification system includes a forward osmosis module, a reverse osmosis module, a pump powered by an electric motor, and a pressure sensor. The forward osmosis module may receive a feed stream and a draw stream, and may produce an intermediate product stream. The intermediate product stream may be pressurized by a pump and provided to the reverse osmosis module. The reverse osmosis module may generate a product stream and return the draw stream to the forward osmosis module. The pressure sensor may monitor the pressure of the intermediate product stream, and the pressure may be used to determine the speed of the electric motor.

A method for inhibiting silica scale formation in an aqueous system by adding a hydrophobically-modified alkylene oxide urethane copolymer anti-scalant to the water used in the aqueous system.

A process for inhibiting formation of calcium scale in a reverse osmosis desalination membrane during desalination involving desalinating an aqueous salt solution comprising water, sodium chloride, calcium chloride, and sodium bicarbonate with the reverse osmosis desalination membrane, while concurrently irradiating the aqueous salt solution with a UV light source that emits UV light with a wavelength of 250-400 nm. Scale formation is inhibited by treating a salt solution with the UV light in a continuous or a non-continuous process.

The present invention provides methods and apparatus for cleaning and sanitizing potable water devices/appliances by recirculating and pulsing a rejuvenation solution through the device/appliance using a portable apparatus comprising a mechanical pump fluidly connected to the device/appliance.

An object of the present invention is to provide a dispersant for treatment of water. The dispersant is used in a membrane separation process of water containing an organic compound having a phenolic hydroxy group and prevents a reduction in amount of the water permeating a separation membrane, which is caused by deposition of the organic compound onto the surface of the separation membrane. Provided are a dispersant for treatment of water containing an organic compound having a phenolic hydroxy group wherein the dispersant contains a polymer compound having a carbonyl group and a structure including a nitrogen atom bonded to a carbonyl carbon atom; and a method for treatment of water containing an organic compound having a phenolic hydroxy group, wherein the method includes adding the dispersant to the water.

A zwitterionic monomer and corresponding cyclopolymerized polyzwitterion () (PZ) (i.e. poly(Z-alt-SO.sub.2). Phosophonate ester hydroloysis in PZ gave a pH-responsive polyzwitterionic acid () (PZA). The PZA under pH-induced transformation was converted into polyzwitterion/anion () (PZAN) and polyzwitterion/dianion (=) (PZDAN).

There is provided a process for treating well water to produce drinking water. The process combines a vacuum tank process, an adsorption-desorption process, a heat-exchanger process, a membrane distillation-crystallization process. The process allows for some level of efficiency with regard to energy consumption and operational and maintenance costs.

A silica fouling inhibition method for a reverse osmosis membrane system is provided, in which an acrylic acid-based polymer and/or a maleic acid-based polymer; and a combined chlorine-based oxidizing agent and/or a combined bromine-based oxidizing agent are allowed to be present in water to be treated. A silica fouling inhibitor for a reverse osmosis membrane system is provided, the silica fouling inhibitor includes: a copolymer of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid and/or a terpolymer of acrylic acid, acrylamide methylpropanesulfonic acid, and N-substituted acrylamide; and a combined chlorine-based oxidizing agent and/or a combined bromine-based oxidizing agent.