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.1≥n.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.

Apparatus and method for semi-permeable membrane cleaning in particular, applying series of pulsed water stroke, made simultaneously with osmosis backward flow causing superposed membrane directional shaking and fouling detachment. Pulsed water stroke provided by water stroke generator as several momentum sharp changes in gauge pressure and induce velocity pulse of residual brine flow. The pulsed water strokes ideally induce resonance in the membrane. Osmosis backward wash may be provided either by injection for predetermined injection time, additional solution selected in such way that net driving pressure becomes opposite to normal osmotic operation thereby providing a backward flow of permeate towards to the side opposite to normal operation mode, so as to lift said foulant, or by throttling permeate exiting from the permeate enclosure, until the net driving pressure value become equal to zero, during application of precise synchronized and opposing brine and permeate pressure strokes thereby providing a plurality of quick RO-FO-RO process changes. These procedures allow a membrane to be kept continuously clean and operate at higher recovery.

A method for cleaning a filter membrane in which at least 2 types of cleaning water containing oxidizing agents are prepared, and the filter membrane is cleaned using the cleaning water in an ascending order of the oxidizabilities of the oxidizing agents. Moreover, an apparatus for cleaning a filter membrane of the present invention comprises a means for cleaning the filter membrane using at least 2 types of cleaning water containing oxidizing agents, and the filter membrane is cleaned using the cleaning water in an ascending order of the oxidizabilities of the oxidizing agents. The method and the apparatus for cleaning a filter membrane can efficiently remove polluting substances adhered to a filter membrane while reducing the amounts of oxidizing agents and water to be used, and can maintain the filtration performance for a long period of time.

A membrane separation pretreatment apparatus including a membrane separation unit and a first underwater plasma discharge unit disposed in front of the membrane separation unit is provided. The membrane separation pretreatment apparatus includes a membrane separation unit configured to remove particulate matter contained in raw water, and a first underwater plasma discharge unit disposed in front of the membrane separation unit and configured to cause a portion of the raw water to be introduced into the membrane separation unit to perform underwater plasma discharging.

A system for treating a tetraalkylammonium hydroxide-containing liquid having a high-pressure type reverse osmosis membrane device concentrating a liquid to be treated containing tetraalkylammonium hydroxide at a concentration side, and a line for supplying the concentrated liquid to be treated by the reverse osmosis membrane device to an evaporator further concentrating the concentrated liquid to be treated.

An apparatus and a method use permeate to flush a reverse osmosis filter membrane in the same flow direction as when fluid is being filtered through the membrane. The apparatus includes a housing having a membrane positioned therein. The membrane has an interior surface and an exterior surface. The housing has an inlet port located outward of the exterior surface of the membrane and first and second outlet ports. The first outlet port is located outward of the exterior surface of the membrane and the second outlet port is located inward of the interior surface of the membrane. A first pump is used to route pressurized, untreated fluid from a fluid source through the membrane to produce permeate. A second pump is used to route permeate to a desired function while also routing some permeate at low pressure to the housing to flush the membrane.

The invention relates to a method for filtering water comprising the use of a pump (14) to supply a filtering means (17), said supply being performed by simultaneous suction, for example by the same pump (14), through an ultrafiltration module (12).

Methods for monitoring patient parameters and blood fluid removal system parameters include identifying those system parameters that result in improved patient parameters or in worsened patient parameters. By comparing the patient's past responses to system parameters or changes in system parameters, a blood fluid removal system may be able to avoid future use of parameters that may harm the patient and may be able to learn which parameters are likely to be most effective in treating the patient in a blood fluid removal session.

A method for treating produced water in a system for treating wastewater is disclosed. The system includes a reverse osmosis unit for removing dissolved solids. The reverse osmosis unit produces a permeate and concentrate. To reduce the fouling potential of the membranes associated with the reverse osmosis unit and/or to increase membrane lifetime and/or to increase system recovery, at least a portion of the concentrate is recycled and mixed with the wastewater stream at a point upstream of the reverse osmosis unit.

An apparatus and a method for using permeate to flush a reverse osmosis filter membrane in the same flow direction as when fluid is being filtered through the membrane is disclosed. The apparatus includes a housing having a membrane positioned therein. The housing has an inlet side and an outlet side. The membrane has an interior surface and an exterior surface. The housing has an inlet port located outward of the exterior surface of the membrane, at the inlet side of the housing, and a first outlet port and a second outlet port both located at the outlet side of the housing. The first outlet port is located outward of the exterior surface of the membrane and the second outlet port is located inward of the interior surface of the membrane. A first pump is used to route pressurized, untreated fluid from a fluid source through the membrane to produce permeate. A storage tank holds permeate until needed. A second pump is used to route permeate to a desired function while also routing some permeate at low pressure to the housing to flush the membrane. The flushing occurs when the first pump is turned off. A method of flushing the membrane is also taught.