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 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 flat ceramic membrane 1 has a plate-shaped porous support 21 made of ceramics and a filtration membrane 22 formed on an outer surface of the porous support 21. A plurality of water collection channels 2 where filtrate water obtained by permeation of water-to-be-treated through the filtration membrane 22 flows are formed inside the porous support 21. Further, a region where a thickness between a membrane surface 20 of the filtration membrane 22 and the water collection passage 2 is different is ensured inside the porous support 21.

Provided is a method for washing a hollow fiber membrane module which comprises a hollow fiber membrane for filtering raw water containing a suspended component, said method comprising, in the following order, a first washing step for removing a suspended component that is accumulated on the hollow fiber membrane and a second washing step for carrying out an air scrubbing process in which gas is caused to pass through at least to the raw water side of the hollow fiber membrane, wherein, out of water that existed in the hollow fiber membrane module before washing, water in an amount corresponding to not less than 50 vol % of the capacity of the hollow fiber membrane module is removed in the first washing step.

The invention provides a dynamic membrane reactor with function of nitrogen and phosphorus removal and an operation method thereof, and comprises a biological treatment system, a dynamic membrane loading system and an automatic system. The operation method comprises the following steps. (1) Before the formation of dynamic membrane, a porous filter for phosphorus removal is used as a cathode, a conductive precision filter screen is used as an anode, and aerobic denitrifying bacteria are inoculated into the dynamic membrane reactor under certain constant current density, hydraulic retention time and flux. (2) After the dynamic membrane is formed, the porous filter for phosphorus removal is used as the anode, the conductive precision filter screen is used as the cathode. And intermittent aeration is started at the anode under certain constant current density. (3) When the transmembrane pressure difference exceeds a certain range, hydraulic backwashing is performed under certain constant current density.

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).

Disclosed herein are apparatuses and methods for semi-permeable membrane cleaning. In particular, a pressure retarded osmosis (PRO) process redirects raw solution and fluid streams in such a way as to cause periodic changes of the process from PRO to reverse osmosis (RO) for lifting and detaching fouling. Further disclosed is applying, at least periodically, a pulsed-flow regime in the fluid stream, thereby causing increased shearing force for enhanced evacuation of the foulant. Additionally, a backward wash may be provided by injection, for a predetermined injection time, of additional solution selected in such way that net driving pressure becomes RO opposite to normal PRO operation, thereby providing a backward flow from a first side of the membrane to a second side of the membrane, so as to lift and evacuate foulant.

This membrane filtration method includes: a membrane filtration process for adding a coagulant to water to be treated which contains viruses, and filtering the water to be treated by using a filtration membrane; and a cleaning process for, after the membrane filtration process, cleaning the filtration membrane, the membrane filtration process and the cleaning process being repeatedly performed, wherein, in the membrane filtration process, in the initial period of filtration, at least either an operation of filtering the water to be treated that includes the coagulant added by an amount larger than the amount of a coagulant added in a normal case, or an operation of filtering the water to be treated that has a pH lower than the pH of water to be treated in a normal case, is performed.

An isolation device includes an isolation chip assembly, a vacuum system, a frequency converting module, and a controller. The isolation chip assembly includes an isolation chip having a first chamber and a second chamber, a first oscillator mounted on the first chamber, and a second oscillator mounted on the second chamber. The frequency converting module causes the vacuum system to generate negative pressure in the first and the second chambers alternately. The controller controls the first and the second oscillators to operate when the vacuum system stops generating the negative pressure in the first chamber and in the second chamber. The first and the second oscillators respectively generate a first and a second oscillation wave when operating, a frequency of the first oscillation wave is greater than a frequency of the oscillation wave, an amplitude of the first oscillation wave is less than an amplitude of the second oscillation wave.

A desalination brine dispersal apparatus and method employ airlift to remove, oxygenate and disperse brine from a desalination apparatus. The apparatus includes a brine removal conduit having a brine inlet that receives brine from the desalination apparatus, a plurality of brine outlets submerged in seawater and one or more air introduction points located at depths below the brine outlets. The supplied air oxygenates and moves brine through the brine removal conduit and outlets via airlift and disperses the brine into seawater away from the brine removal conduit. The apparatus avoids the formation of concentrated, high shear brine plumes and can disperse brine into seawater over a wide area well away from the brine removal conduit.