Provided is a method for operating an RO-membrane treatment system that includes an energy recovery device that recovers energy from the concentrate of an RO-membrane device and the RO-membrane treatment system that reduce the occurrence of biofouling in not only the RO-membrane device but also the energy recovery device in order to increase the energy efficiency of the entire system and operate the RO-membrane treatment system with consistency. The method includes adding at least one slime-control agent selected from a combined-chlorine slime-control agent and a stabilized-bromine slime-control agent to water that is to be treated with the reverse-osmosis-membrane device such that a residual halogen concentration in the concentrate that is to be introduced into the energy recovery device is 0.1 to 10000 mg/L as total chlorine.

Provided is a filtration method that includes a cleaning step and involves the use of a porous membrane, wherein the filtration method offers exceptional resistance to cleaning solutions (chemicals) (chemical liquid resistance) and exceptional filtration performance, and has a long service life. A filtration method includes the following steps: a filtration step in which a liquid to be processed that contains a material to be filtered is passed through a porous membrane configured from a resin having a three-dimensional mesh structure, and a filtrate is separated from the material to be filtered; and a cleaning step in which the porous membrane has a cleaning solution passed therethrough or is immersed in the cleaning solution so that the interior of the porous membrane is cleaned.

A conventional media filter such as a gravity sand filter is converted into a membrane filter. The media is removed and replaced by immersed membrane modules. Transmembrane pressure is created by a static head pressure differential, without a suction pump, thereby creating a membrane gravity filter (MGF). Preferred operating parameters include transmembrane pressure of 5-20 kPa, 1-3 backwashes per day, and a flux of 10-20 L/m.sup.2/h. The membranes are dosed with chlorine or another oxidant, preferably at 700 minutes*mg/L as Cl.sub.2 equivalent per week or less. The small oxidant does is believed to provide a porous biofilm or fouling layer without substantially removing the layer. The media filter may be modified so that backwash wastewater is removed from near the bottom of the tank rather than through backwash troughs above the membrane modules. Membrane integrity testing may be done while the tank is emptied after a backwash.

A method ensuring excellent chemical resistance to a chemical cleaning solution, excellent filtration performance and an enhanced life in a saccharified solution production method including a cleaning step and filtration using a porous filtration membrane. A method for producing a saccharified solution, including the following steps: a liquefaction step of adding an enzyme to liquid starch to obtain a sugar-containing liquefied product; a saccharification step of adding a saccharifying enzyme to further degrade the sugar and obtain a saccharified solution composition containing a saccharified solution and an insoluble component; a filtration step of passing the saccharified solution composition through a porous membrane composed of a resin having a three-dimensional network structure to separate the saccharified solution from the insoluble component; and a cleaning step of passing or soaking the porous membrane into a cleaning solution to clean/remove the insoluble matter attached to the surface or inside of the porous membrane.

A water treatment membrane washing apparatus includes two ozone dissolving tanks for storing filtrate generated by filtering raw water through a water treatment membrane and gas aspirators provided for the respective ozone dissolving tanks, for mixing the filtrate with ozone gas supplied from an ozone supply unit to generate ozone gas containing filtrate, and is configured such that waste ozone gas generated in one of the ozone dissolving tanks is aspirated by the gas aspirator provided for the other ozone dissolving tank. After the filtrate from the raw water is pretreated by being mixed with the waste ozone gas in the aspirator, the pretreated filtrate is mixed with the ozone gas in the other ozone dissolving tank until it reaches a predetermined concentration. The ozone gas containing filtrate is supplied from the secondary side of the water treatment membrane to the primary side thereof to wash the eater treatment membrane.

A cleaning solution for accelerated cleaning of a membrane having an enzyme and an agent having a pH that is compatible with the enzyme. The cleaning solution may additionally include one or both of a binding agent and a surfactant. Once the cleaning solution has been included in a solution that is used to contact the membrane for a defined period of time, one or both of a binding agent and a reducing agent may be added to the solution that has contacted the membrane. Optionally, one or both of increasing a pH of the solution and increasing a temperature of the solution may be used to reduce an activity of the enzyme.

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 water treatment chemical for a membrane, being is a water treatment chemical for preventing membrane contamination caused by an organic compound having a phenolic hydroxy group and including an organic amine having two or more nitrogen atoms and having five or more carboxyl groups or four or more phosphate groups. A membrane treatment method including adding the water treatment chemical for a membrane to water to be treated which contains an organic compound having a phenolic hydroxy group and then subjecting the water to be treated to membrane separation treatment.

A conventional media filter such as a gravity sand filter is converted into a membrane filter. The media is removed and replaced by immersed membrane modules. Transmembrane pressure is created by a static head pressure differential, without a suction pump, thereby creating a membrane gravity filter (MGF). Preferred operating parameters include transmembrane pressure of 5-20 kPa, 1-3 backwashes per day, and a flux of 10-20 L/m.sup.2/h. The membranes are dosed with chlorine or another oxidant, preferably at 700 minutes*mg/L as Cl.sub.2 equivalent per week or less. The small oxidant does is believed to provide a porous biofilm or fouling layer without substantially removing the layer. The media filter may be modified so that backwash wastewater is removed from near the bottom of the tank rather than through backwash troughs above the membrane modules. Membrane integrity testing may be done while the tank is emptied after a backwash.

Disclosed are nanocomposite membranes and methods for making and using same. In one aspect, the nanocomposite membrane comprises a film comprising a polymer matrix and nanoparticles disposed within the polymer matrix, wherein the film is substantially permeable to water and substantially impermeable to impurities. In a further aspect, the membrane can further comprise a hydrophilic layer. In a further aspect, the nanocomposite membrane comprises a film having a face, the film comprising a polymer matrix, a hydrophilic layer proximate to the face, and nanoparticles disposed within the hydrophilic layer, wherein the film is substantially permeable to water and substantially impermeable to impurities. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present invention.