An apparatus includes 1) a filtration device including a filtration module to generate a filtrate from an input stream; 2) a desalination device fluidly connected to the filtration device; and 3) a controller configured to direct operation of the filtration device and the desalination device. In a first mode of operation, the filtration module is configured to perform filtration as part of generating the filtrate. In a second mode of operation, the filtration module is configured to receive an output from the desalination device such that the output backwashes the filtration module. The controller is configured to monitor a change in membrane resistance of the filtration module during the first mode of operation, and is configured to trigger the filtration module to enter the second mode of operation based on the change in membrane resistance.

This specification describes membrane based filtration and softening systems and methods. A system has a microfiltration or ultrafiltration (MF/UF) membrane unit upstream of a nanofiltration or reverse osmosis (NF/RO) membrane unit, optionally with no intermediate tank. In some cases, the system and method may be used with feed water provided at municipal line pressure to the membranes. NF/RO permeate is collected in a tank and then pumped to a header. Treated water may be drawn from the header for use or recycled to the system, for example to backwash or flush one or both of the membrane units. In a combined process, NF/RO permeate flushes the feed side of the NF/RO unit and then backwashes the MF/UF unit. In another process, the MF/UF unit and NF/RO unit are filled with NF/RO permeate before being placed in a standby mode.

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.

A water desalination system includes a first set of ultrafiltration membranes, a second set of ultrafiltration membranes, a first backwashing system configured to treat at least one of the first set of ultrafiltration membranes or the second set of ultrafiltration membranes with brine generated by a reverse osmosis process, and a second backwashing system configured to treat at least one of the first set of ultrafiltration membranes or the second set of ultrafiltration membranes with one or more chemicals and reverse osmosis permeate water.

An apparatus includes 1) a filtration device including a filtration module to generate a filtrate from an input stream; 2) a desalination device fluidly connected to the filtration device; and 3) a controller configured to direct operation of the filtration device and the desalination device. In a first mode of operation, the filtration module is configured to perform filtration as part of generating the filtrate. In a second mode of operation, the filtration module is configured to receive an output from the desalination device such that the output backwashes the filtration module. The controller is configured to monitor a change in membrane resistance of the filtration module during the first mode of operation, and is configured to trigger the filtration module to enter the second mode of operation based on the change in membrane resistance.