A method of purifying impure water contaminated with a filterable impurity and a dissolved impurity, such as seawater, comprising the steps of: providing impure water to a primary microfiltration or ultrafiltration unit to remove the filterable impurity and produce impure filtered water contaminated with a dissolved impurity; providing the impure filtered water contaminated with a dissolved impurity to a reverse osmosis unit to produce a potable water stream and a residual reverse osmosis stream; and treating the residual reverse osmosis stream prior to reuse. The treatment may be in the form of passing through a secondary filter (such as another microfiltration or ultrafiltration membrane or a cartridge filter, and the subsequently treated reverse osmosis reject may be used to backwash the microfiltration or ultrafiltration unit.

Process and apparatus for purifying impure water using microfiltration or ultrafiltration in combination with reverse osmosis

A method of cleaning a membrane surface immersed in a liquid medium with a fluid flow, including the steps of providing a randomly generated intermittent or pulsed fluid flow along the membrane surface to dislodge fouling materials therefrom. A membrane module is also disclosed comprising a plurality of porous membranes (6) or a set of membrane modules (5) and a device (11) for providing a generally randomly generated, pulsed fluid flow such that, in use, said fluid flow moves past the surfaces of said membranes (6) to dislodge fouling materials therefrom.

Membrane cleaning with pulsed airlift pump

A method of filtering solids from a liquid suspension comprising providing a pressure differential across the walls of permeable, hollow membranes (5) immersed in the liquid suspension contained in a vessel (8), the liquid suspension being applied to the outer surface of the porous hollow membrane (5) to induce and sustain filtration through the membrane walls. Some of the liquid suspension passes through the walls of the membranes (5) to be drawn off as permeate from the hollow membrane lumens, and at least some of the solids are retained on or in the hollow membranes or otherwise as suspended solids within the liquid surrounding the membranes (5). The method includes the steps of suspending the flow of the liquid suspension to the vessel (8); reducing the volume of liquid suspension within the vessel (8); suspending the filtration process; cleaning the membranes (5) by dislodging at least some of th solids retained on or in the membranes (5); and removing the liquid containing dislodged solids from the vessel (8).

Reduction of backwash liquid waste

A method of cleaning a porous polymeric membrane having a feed side and a permeate side including the steps of introducing a fluid containing a cleaning agent to the permeate side of a membrane allowing the cleaning agent to contact the permeate side of the membrane for a predetermined time, and contact the pores of the membrane, or introducing a fluid containing a cleaning agent to the feed side of a membrane; applying a transmembrane pressure to force the fluid containing the cleaning agent from the feed side to the permeate side of the membrane; allowing the cleaning agent to contact the permeate side of the membrane for a predetermined time, and contact the pores of the membrane. Preferably a concentration gradient between the feed side fluid and the lumen side fluid containing the cleaning agent causes cleaning agent to diffuse into the feed side fluid. Pressure may be applied to the fluid containing a cleaning agent to dislodge, where present, dissolved and undissolved solid from the membrane pores. The pressure may be applied in a pulsed fashion, and can be by way of compressed air at a pressure not more than the membrane's bubble point. The methods of the present invention may be preceded by, or followed with a backwash.

Chemical Clean For Membrane Filter

An aeration/backwash device ( 16 ) for use with a porous membrane filtration module ( 5 ) including one or more membranes ( 6 ) extending longitudinally between vertically spaced upper ( 7 ) and lower headers ( 8 ) into which the ends of the membranes are potted The membranes ( 6 ) having a permeable wall which, in use, is subjected to a filtration operation wherein feed containing contaminant matter is applied to one side of the membrane wall and filtrate is withdrawn from the other side of the membrane wall The aeration/backwash device ( 16 ) adapted to at least partially surround a portion of said membrane module ( 5 ) and including a communication chamber ( 17 ) having spaced through-openings ( 18, 19 ) in fluid communication with the chamber ( 17 ) and the membrane module ( 5 ) In use, gas is supplied to the chamber ( 17 ) and communicated to the membrane module ( 5 ) through the through-openings ( 18, 19 ) to aerate the membranes within the membrane module and liquid backwash is withdrawn from and/or fed into the membrane module ( 5 ) through the throughopenings into the chamber ( 17 )

Module cleaning method

PROBLEM TO BE SOLVED: To supply sufficient oxygen without damaging the membrane surface washing effect due to coarse air bubbles and accompanied by the diffusion of an excessive amount of air. SOLUTION: A predetermined amount of air is divided to be supplied to first and second air diffusers 8, 9 and a first aeration zone L3 is formed by fine air bubbles A diffused from the first air diffuser 8 arranged under an immersion type membrane separation apparatus 3 and a second aeration zone L2 is formed by coarse air bubbles B diffused from the second air diffuser 9 arranged above the first air diffuser 8 and finer air bubbles A diffused from the first air diffuser 8 and oxygen is supplied to the activated sludge mixed liquid in a tank with high dissolving efficiency by the independent aeration due to fine air bubbles A in the first aeration zone L3 and oxygen is supplied by the mixing aeration of coarse air bubbles B and fine air bubbles A in the second aeration zone L3 and the ascending streams of a gas-liquid mixed phase generated by the air lift action of coarse bubbles B and fine air bubbles A are allowed to act on the membrane surface of the immersion type membrane separation apparatus 3 as sweeping streams.

Method and apparatus for diffusing air of membrane separation activated sludge method

PROBLEM TO BE SOLVED: To provide a cleaning method of diffuser, which can easily remove dry and deposited foreign matter by making a water to be flow backward into an air diffusion pipe. SOLUTION: In this diffuser, a gas for diffusion is jetted into the water to be treated by diffusion in a reaction tank 1 from a plurality of jet ports 3 at the bottom of the air diffusion pipe 2 immersed in the tank 1. After stopping diffusion, the water to be treated is made to flow backward into the air diffusion pipe 2 from a tip opening 4 of the air diffusion pipe 2 bent downward and each jet port 3. The influent water humidifies the foreign matter dry and deposited in the vicinity of each jet port 3. Then, diffusion is restarted, and the water to be treated in the air diffusion pipe 2 is discharged from the tip opening 4, and the humidified foreign matter is removed by the sweeping stream of the water to be treated.

Cleaning method of diffuser

PROBLEM TO BE SOLVED: To provide a separating and dewatering apparatus for screenings having a compact tank capacity to separate and treat a screenings-and-water mixture collectively flowing in a short time. SOLUTION: This apparatus comprises a casing 39, a spiral transport wing body 40 arranged inside the casing 39, and a drive device 41 driving the transport wing body 40 to rotate. The one end of the casing 39 is separated and submerged in a holding tank 30 for screenings. The casing 39 comprises a draining part 42, a transport part 43 and a compressing/dewatering part 44. An inflow port 45 is formed so as to open in opposite to a screen 31 on the upperside of the draining part 42. A discharge port 47 is formed to communicate with a discharge duct 46 on the underside of the compressing part 44. The underside section of the draining part 42 is formed of a porous member 48. The transport wing body 40 comprises a spiral wing 49 with a wing spirally arranged in a section corresponding to the draining part 42, a screw wing 51 with wings spirally arranged around the rotating axis 50 in a section corresponding to the transport part 43, and a cutting-down wing 52 with the wing body spirally arranged in an opposite direction to the screw wing 51 in a section corresponding to the compressing/dewatering part 44. COPYRIGHT: (C)2003,JPO

Separating and dewatering apparatus for screenings

PROBLEM TO BE SOLVED: To provide a reaction vessel structure which maintains activated sludge concentration uniformly in an existing and long rectangular, and does not filter untreated feed water by performing homogeneous biological treatment in the whole vessel. SOLUTION: An immersing type film separating device 4 is placed along the long side of a long rectangular reaction vessel 1. In the vessel, an inflow system 8 which introduces the feed water and an outflow system 9 which takes out a mixed solution in the vessel are placed oppositely in the direction of the short side of the immersing type film separating device 4. The inflow system 8 and the outflow system 9 are provided along the long side, and the feed water is uniformly introduced into the reaction vessel 1 from various places of the inflow system 8 along the long side of the reaction vessel 1. The mixed solution in the vessel is uniformly discharged from the reaction vessel 1 in various places of the outflow system 9 along the long side of the reaction vessel 1. COPYRIGHT: (C)2002,JPO

真一福原

Papers

Method and apparatus for diffusing air of membrane separation activated sludge method

Cleaning method of diffuser

Separating and dewatering apparatus for screenings

Reaction vessel structure

真一 福原

Papers

Method and apparatus for diffusing air of membrane separation activated sludge method

Cleaning method of diffuser

Separating and dewatering apparatus for screenings

Reaction vessel structure

真一福原