The present invention relates to a method of operating a membrane filtration unit including plural hollow fiber membrane modules connected to each other in parallel, the method including: a filtration step; a collection step; and a recovery step, in which a relation of n.sub.1n.sub.2>n.sub.3 is satisfied, where n.sub.1 is the number of the hollow fiber membrane modules simultaneously used in executing the filtration step, n.sub.2 is the number of the hollow fiber membrane modules simultaneously used in executing the collection step, and n.sub.3 is the number of the hollow fiber membrane modules simultaneously used in executing the recovery step.

A method (100) of filtering solids (41) from a solution (44) derived from blood plasma is disclosed. The method (100) comprises feeding (102) the solution (44) into a hollow fibre filter (12) at a feed rate, the hollow fibre filter (12) comprising a plurality of hollow fibres (38), each hollow fibre (38) comprising a membrane (36) defining an elongate hollow fibre channel (32). The method (100) further comprises filtering (104) the solution (44) using the hollow fibre filter (12) to produce a permeate (46) and a retentate (45), the permeate (46) passing through pores (37) of the membrane (36) at a trans-membrane pressure and the retentate (45) flowing from respective outlets of the elongate hollow fibre channels (32), wherein the permeate (46) has a reduced solids content with respect to the solution (44) fed into the hollow fibre filter (12).

A control method for an RO system, which is a control method for an RO system that includes a plurality of RO devices 41 to 44 arranged in parallel, a control unit that controls a start/stop process including an operation process and a stop process of the RO devices 41 to 44, and a chemical injection unit that injects a chemical that mitigates fouling during the stop process. The control method performs control such that a number of times of start/stop increases for RO devices that are more likely to recover treatability through start/stop operations, and a stop-time is controlled according to a recovery rate.

A method of removing chemical contaminants from a composition comprising an active, a solvent, and a contaminant can include providing an initial feed supply, wherein the initial feed supply comprises the active, the solvent, and the contaminant, wherein the contaminant can include 1,4 dioxane, dimethyl dioxane, or a combination thereof; including filtering the initial feed stock through a nanofilter.

A method includes inducing a first quantity of a feed fluid (28) to flow along a first direction (72) from a bioreactor (12) to a tangential flow filter (16) to separate the first quantity of the feed fluid (28) into a permeate fluid (42) and a retentate fluid (48). Further, the control unit (66) is operated to control at least one feed flow control device (24, 26) to inhibit the flow of first quantity of the feed fluid (28). Furthermore, the control unit (66) is operated to control the at least one feed flow control device (24, 26) to direct at least one of further flow of a second quantity of the feed fluid (28) from the bioreactor (12), a portion of the permeate fluid (42), and a portion of a nutrient fluid, along a second direction (74) opposite to the first direction (72) via the tangential flow filter (16).

A water treatment system includes a source of inlet water, a prefiltration unit, a feeder, a pump, and a membrane element. The prefiltration unit is in fluid communication with the source and provides a prefiltered water to a prefiltered water line. The feeder is in fluid communication with the prefiltered water line and is positioned downstream of the prefiltration unit. The feeder is designed to deliver a chemical additive to the prefiltered water. The pump is in fluid communication with the prefiltered water line and a permeate flush line, and the pump is designed to increase a flow rate of water in a membrane feed line. The membrane element includes an inlet that is in fluid communication with the pump via the membrane feed line. The membrane element produces a permeate imparted with a first concentration of solutes and a retentate imparted with a second concentration of solutes.

Provided is a water purifier which prevents an increase in the total dissolved solids (TDS) concentration of fluid located in a purified water zone of a reverse osmosis (RO) filter. Specifically, the water purifier may include a reverse osmosis (RO) filter including a raw water zone into which raw water flows from an outside, a purified water zone for accommodating purified water generated by filtering at least a portion of the raw water located in the raw water zone, and a reverse osmosis membrane partitioning the raw water zone and the purified water zone; a pretreatment filter configured to pretreat the raw water flowing into the RO filter and having a hollow through which the pretreated raw water passes; a flow channel connected to the pretreatment filter and the RO filter and providing a passage on which the raw water and the purified water flow; an inner guide including a cylindrical inner guide partition wall inserted into the hollow of the pretreatment filter and a passage hole formed through the inner guide partition wall and communicating with the hollow; a plurality of valves connected to the pretreatment filter and the RO filter and selectively opened/closed to regulate flow of the raw water and the purified water; and a controller configured to control opening/closing of the plurality of valves based on a plurality of flow modes.

The present disclosure provides a direct water purification system with an automatic backwash function. The direct water purification system includes a raw water inlet unit, a first pressure valve, a filtration device, a second pressure valve, a purified water outlet unit, a waste water outlet unit, and an energy recovery waterway which is in liquid communication with the filtration device, the second pressure valve and the first pressure valve. The energy recovery waterway is configured to collect purified water and accumulate pressure when the purified water outlet unit is closed, and to back flow the purified water by the accumulated pressure to a filtered water outlet so as to clean a filtration component. The direct water purification system with an automatic backwash function is adapted to automatic clean the direct water purification system each time purified water output is used.