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 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.

A circulating water preparation system for cooling plants, a cooling system, in particular a recooling system, and a method for operating such a cooling system. In such a cooling system a surface of a heat exchanger is cooled by wetting with water, the water is collected in a collecting tank and returned by means of a water circuit for the renewed wetting of the surface of the heat exchanger. The method is characterised in that the water is purified by means of a filter, in particular a membrane filter. As a result considerably less biocide is needed to keep the water free of germs, in particular legionella, compared to conventional cooling systems or methods for operating such cooling systems.

A filter device includes one or more filter membranes, and a filter housing enclosing the one or more filter membranes. Each of the filter membranes includes a base membrane made of a ceramic material, and a plurality of through holes. The base membrane is coated with a coating material.

A method of filtration includes a filtration step in which a liquid to be filtered is filtered through a porous membrane module consisted of a resin having a three-dimensional network structure by external pressure filtration; a cleaning step of cleaning an outer surface of the porous membrane by carrying out backwash of passing a cleaning solution through the porous membrane from an inner surface of the membrane, and air bubbling after the filtration step; and a discharging step of discharging the cleaning solution remaining on the outer surface and inside of the porous membrane after the cleaning step; and in SEM images of a membrane cross section in a membrane thickness direction orthogonal to the inner surface of the porous membrane, a total area of a resin portion having an area of 1 μm.sup.2 or less is 70% or more relative to a total area of the resin portion.

A composition for cleaning membranes used in food processing comprising an amine oxide and an alkyl sulfate, the composition maintaining good cleaning performance whilst leaving a low residue of surfactant on the membrane that is cleaned using the composition. A method of use of the composition is also presented.

A composition for cleaning membranes used in food processing comprising an amine oxide and an alkyl sulfate, the composition maintaining good cleaning performance whilst leaving a low residue of surfactant on the membrane that is cleaned using the composition. A method of use of the composition is also presented.

Embodiments of the present disclosure generally relate to methods for treating porous membranes. In an embodiment, a method of treating a porous membrane is provided. The method includes flushing the membrane with a first fluid comprising a hydroxide ion and hypochlorite ion, flushing the membrane with water, flushing the membrane with a second fluid comprising an organic peroxide, organic peroxide ion, or both, and flushing the membrane with water.

A greywater treatment system includes a first modular greywater processing apparatus having a raw greywater inlet, a mechanical (MTF) filter connected to the raw greywater inlet, a first ultrafine (UF) filter connected in series downstream of the mechanical filter. The UF filter includes a UF filter inlet, a filtrate outlet, and a cross-flow outlet. The filtrate outlet is connected to a processed water outlet. A modular base supports the mechanical filter and the UF filter.

A solution-type water treatment chemical, includes, as one, gluconic acid (salt) and a surfactant having an HLB determined by the following equation (1) satisfying the following equation (2), wherein in a relationship between concentrations of the gluconic acid (salt) and the surfactant and a molecular weight and HLB of the surfactant, the gluconic acid (salt) and the surfactant are contained such that the water treatment chemical does not form a gel or precipitate.
HLB=(Σinorganic value/Σorganic value)×10  (1)
Molecular weight>−34.4×HLB+1005  (2)