Wastewater is treated though primary treatment of the water by way of a micro-sieve to produce a primary effluent and primary sludge. There is secondary treatment of the primary effluent by way of a membrane bioreactor (MBR) or an integrated fixed film activated sludge (IFAS) reactor to produce a secondary effluent and a waste activated sludge. The micro-sieve may have openings of 250 microns or less, for example about 150 microns. In a process, a gas transfer membrane is immersed in water. Pressurized air flows into the gas transfer membrane. An exhaust gas is withdrawn from the gas transfer membrane and used to produce bubbles from an aerator immersed in the water.

A method of operating a filtration unit of a filtration system includes feeding, during filtration, feed water containing suspended particulate material to an inside of each of a plurality of hollow fibres through a first inlet and a second inlet of each hollow fibre while simultaneously removing a filtrate from an outside of each of the hollow fibres through an outlet of a filtration elements. In addition, the method includes feeding, during back-washing, back-wash water to the outside of the hollow fibres through the outlet of the filtration element. Further the method includes discharging, in a first back-wash cycle, back-wash water containing entrained particulate material from the inside of the hollow fibres from one end thereof. Still further, the method includes discharging, in a second back-wash cycle, back-wash water containing entrained particulate material from the inside of the hollow fibres from the other end thereof.

A reverse osmosis desalination system has a combined displacement pump and displacement pressure recovery motor that propagate feed water with a structurally fixed recovery rate and structurally stabilized volume flow through continuously alternating discharging and recirculation intervals. Thereby enabled is an instantaneous discharge of the entire feed water concentrate and unmixed replacement with low salinity source water that intermittingly and effectively flushes the reverse osmosis membranes. This in turn provides for high recirculation peak salinity and recovery rate that are simple and reliably controlled without impairing membrane longevity.

A membrane separation process is described. The process comprises pumping of a fluid stream through a membrane module to produce a permeate during a plurality of membrane operating cycles. Each membrane operating cycle comprises a filtration cycle and a relaxation cycle. Concentration polarisation is controlled during the process by controlling duration of filtration cycles and relaxation cycles to relatively short duration to maintain the degree of concentration polarisation below a target.

Embodiments herein relate to a membrane bioreactor for strengthening membrane fouling control and method thereof. The embodiments may solve problems associated with existing techniques in the field of water treatment. The membrane bioreactor may include a reactor wall, a membrane element, a collecting pipe, a water collecting pipe, a vacuum table, a suction pump, a cleaning unit, an air compressor, an aeration pipe, an aeration head, an inlet pipe, and a drain pipe. The existing techniques related to membrane fouling control has problems such as complexity to operate, difficulties to clean online, and uses of chemicals, which may cause secondary pollution. The embodiments relate to a device that includes a set of automatic mechanical transmission units. With cleaning parts installed at terminals of the device, the surface of the pollution layer of the flat membrane may be cleaned periodically to achieve in situ membrane fouling control, an increase of water production capacity and backwash cycle, and improvement of the efficiency of the membrane bioreactor.

Wastewater is treated though primary treatment of the water by way of a micro-sieve to produce a primary effluent and primary sludge. There is secondary treatment of the primary effluent by way of a membrane bioreactor (MBR) or an integrated fixed film activated sludge (IFAS) reactor to produce a secondary effluent and a waste activated sludge. The micro-sieve may have openings of 250 microns or less, for example about 150 microns. In a process, a gas transfer membrane is immersed in water. Pressurized air flows into the gas transfer membrane. An exhaust gas is withdrawn from the gas transfer membrane and used to produce bubbles from an aerator immersed in the water.

The present invention provides a submerged type membrane separation device and a membrane separation method which allow long-term stable filtration. In the submerged type membrane separation device including a membrane module having membrane units stacked on top of each other in stages, in each of which flat sheet membrane element each having a separation membrane are arranged, the membrane module is constructed of various membrane units differing in sludge-filtration resistance or pure-water permeation resistance, whereby it becomes possible to extend a device operation period of time lapsing before transmembrane plugging occurs, or equivalently, the necessity to clean membranes arises. Further, it also becomes possible to design to synchronize timings with which a plurality of membrane units require cleaning.

A method of operating a pressure-retarded osmosis plant, the plant comprising at least one osmosis element having a semi-permeable membrane, the semi-permeable membrane defining a feed side and a permeate side of the osmosis element, the method comprising, in a first mode of operation, supplying a feed stream having a relatively high concentration of solute to the feed side, supplying a permeate stream having a relatively low concentration of solute to an inlet of the permeate side, and receiving a feed outlet stream from the feed side wherein permeate has passed through the semi-permeable membrane from the permeate side to the feed side, in a second mode of operation, supplying a backwash stream having a relatively low concentration to the feed side of the osmosis element such that water passes through the semi-permeable membrane, and receiving a permeate outlet stream from an outlet of the permeate side, the method further comprising alternately performing the first mode of operation, to perform a production step, and performing the second mode of operation, to reduce fouling of the semi-permeable membrane.

The invention relates to the purification and/or desalination of a liquid. The present method includes purifying a liquid and flushing a liquid purification means. Raw liquid is fed, via a means for increasing pressure, along a raw liquid and drain liquid mixing line to a liquid purification means. Drain liquid is fed along a recirculation line in order to be mixed with raw liquid. After a set period of time, the liquid purification process is interrupted in order for the liquid purification means to be flushed by a liquid medium for the removal of contaminants which have built up on the inside surface of the liquid purification means. Downstream of the liquid purification means, the liquid medium is discharged at high speed into a drain. Prior to flushing of the liquid purification means, the purification process is interrupted at least once for a short period of time sufficient to enable disruption of a polarized layer of contaminants. A mixture of raw liquid and drain liquid is used as the liquid medium for flushing. Technical result: a reduction in the amount of raw liquid used for flushing and an increase in the service life of the water purification means.

The invention relates to systems for purifying and/or desalinating a liquid. The present system comprises a valved raw liquid supply line, which is connected to a filtration unit comprising a liquid purification means with an inlet and with outlets for purified liquid and drain liquid, a mixing device, a means for maintaining pressure, a means for maintaining a recirculating flow of liquid, which is located on a line supplying a mixture of raw liquid and concentrate upstream of the liquid purification means, a recirculating line, a purified liquid line, a drain liquid line, and a control unit, which is connected to all of the following: the means for maintaining pressure, a means for monitoring changes in pressure, the raw liquid supply valve and a drain liquid discharge valve. The means for maintaining pressure is located on a raw liquid supply line upstream of the liquid mixing device, which is in the form of a head tank connected to a raw liquid and concentrate mixing line. The technical result is a longer system working life, more efficient use of raw liquid, and reduced energy expenditure.