Wastewater is treated though primary treatment of the water by way of a micro-sieve to produce a primary effluent and primary sludge. There is secondary treatment of the primary effluent by way of a membrane bioreactor (MBR) or an integrated fixed film activated sludge (IFAS) reactor to produce a secondary effluent and a waste activated sludge. The micro-sieve may have openings of 250 microns or less, for example about 150 microns. In a process, a gas transfer membrane is immersed in water. Pressurized air flows into the gas transfer membrane. An exhaust gas is withdrawn from the gas transfer membrane and used to produce bubbles from an aerator immersed in the water.

The disclosure pertains to sanitizing the permeate flow path of a reverse osmosis system. A method of sanitizing a filtration system is disclosed that can include injecting a biocide into a permeate compartment of an operating reverse osmosis system. The method can also include maintaining pressure in a concentrate compartment of the reverse osmosis system simultaneously while injecting the biocide.

A water filtration module includes filtration elements, each formed from a bundle of hollow fibers. In each element, the end portions of the fibers are included in the coating blocks that do not close them, and a longitudinal hollow tube is arranged at the center of the bundle, so as to open on either side of the coating blocks. Each element includes a cap attached around the lower coating block providing a chamber in hydraulic communication with the hollow fibers and with the central tube. The set of elements are assembled removably in a housing of the module, such that an upper permeate collection chamber of the module is in hydraulic communication with the hollow fibers and the central tubes of each of the elements.

A resistivity adjustment device includes: a hollow fiber membrane module that is divided by a hollow fiber membrane into a liquid phase side area; a liquid supply pipe that communicates with the liquid phase side area; a liquid discharge pipe that communicates with the liquid phase side area; a gas supply pipe that communicates with the gas phase side area; a gas discharge pipe that communicates with the gas phase side area; a bypass pipe that communicates with the liquid supply pipe and the liquid discharge pipe to bypass the hollow fiber membrane module; and a first on-off valve that is connected to the gas discharge pipe and opens or closes a first passage inside the gas discharge pipe, wherein the first on-off valve opens the first passage to discharge water accumulated in the gas phase side area.

Provided is a method for cleaning a filtration membrane provided in a membrane filtration device that is immersed in a liquid to be treated and performs solid-liquid separation on the liquid to be treated. When a transmembrane pressure difference exceeds a first predetermined pressure difference P1, a first cleaning step W1 for cleaning a filtration membrane is performed using a first chemical solution; when the transmembrane pressure difference immediately after performing the first cleaning step W1 exceeds a second predetermined pressure difference P2 that is lower than the first predetermined pressure difference, a second cleaning step W2 for cleaning the filtration membrane is performed using a second chemical solution having a concentration higher than the first chemical solution; and when the second cleaning step W2 is performed, the concentration of the second chemical solution and/or the cleaning time is changed according to the temperature of the liquid to be treated.

A method of air scouring an immersed membrane is described in this specification. The method comprising a step of adjusting one or more aeration parameters: between successive permeation, back pulse or relaxation cycles; during a permeation cycle; or, between a permeation cycle and a backpulse or relaxation cycle.

A filtration filter is suitable for performing cross-flow filtration by using a metallic porous membrane. A metallic porous membrane has a membrane portion for filtering filtration objects contained in a fluid and a held portion provided at its outer periphery. A first frame member and a second frame member hold the held portion of the metallic porous membrane there between. The held portion has a bent portion bent to a second principal surface side opposing a first principal surface of the membrane portion. The first frame member is in contact with the held portion at the first principal surface side of the metallic porous membrane. The second frame member is disposed at an inner side portion of the first frame member and is in contact with the held portion at the second principal surface side of the metallic porous membrane.

A method of air scouring an immersed membrane is described in this specification. The method comprises a step of adjusting one or more aeration parameters during a permeation cycle, or between a permeation cycle and a back pulse or relaxation cycle, or between successive cycles. The method may be used with a gas delivery device described in this specification in which a supply of gas is provided to a manifold with multiple ports connected to multiple conduits. The method may further comprise bringing a flow of pressurized gas into a tank to near or below the bottom of a membrane module. At about this elevation, the flow of pressurized gas is split into multiple flows of pressurized gas. Each of the multiple flows of pressurized gas is directed to a different lateral position and then released as bubbles.

A process and system for cleaning semipermeable membranes is described that is particularly well suited for cleaning membranes contained in a water purification system, such as a reverse osmosis process. In order to clean the filter membranes, the membranes are placed in a cleaning chamber capable of allowing a reduction in pressure. In one embodiment, for instance, the membranes are contained in a filter housing and the filter housing is converted into a cleaning chamber by sealing off at least one end. The membranes are then submerged in a cleaning fluid and the pressure within the cleaning chamber is reduced causing the cleaning fluid to form bubbles. The process and system of the present disclosure is well suited to cleaning filter membranes, particularly ceramic membranes, in-line without having to remove the membranes from the water purification system.

A filtration system can comprise a pressure pump configured to apply a pressure on fluid flowing between a first chamber and a second chamber. The filtration system can also comprise a flow sensor configured to determine at least one parameter associated with fluid flowing across a membrane deposited between the first chamber and a second chamber. The filtration system can comprise a pressure sensor configured to determine pressure readings of the fluid flowing from the first chamber to the second chamber. The filtration system can comprise a filtration management system configured to cause the pressure pump to apply a constant pressure on fluid flowing across the membrane for a first predetermined time based on the pressure reading. The filtration management system can be configured to cause the pressure pump to reverse the fluid flow across the membrane.