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.

Membrane filtration systems can be used to purify liquid streams for downstream use. In practice, foulant can build-up on the surface of a membrane within a filtration system over time. The effectiveness of the filtration system will deteriorate if the fouling is not properly controlled. In some examples, a method of controlling membrane fouling in a pressurized membrane system involves supplying a feed stream that is predominately air mixed with water to the membrane. In other words, the feed stream a greater volume of air than water, even though it is the water being processed by the membrane. Supplying the pressurized membrane system with a feed stream that contains a greater volume of air than water can yield significantly better performance than supplying the membrane with a feed stream that contains a greater volume of water than air.

A control method for a water purifier includes establishing a first cleaning passage which communicates a scale inhibiting mechanism with an RO membrane element of the water purifier and through which the scale inhibiting mechanism cleans the RO membrane element for a first preset time. The method additionally includes establishing a draining passage which is connected to the scale inhibiting mechanism and through which liquid in the scale inhibiting mechanism is drained out, and establishing a second cleaning passage which is in communication with raw water and through which the RO membrane element is cleaned with the raw water for a second preset time.

A method of filtering contaminants from a fluid is disclosed. A feedstream of fluid containing contaminants is directed into a filter chamber containing a filter element. Part of the feedstream fluid flows in one of: a forward flow direction where it passes in a first direction through a wall of the filter element; and a reverse flow direction where it passes in a second, opposite direction through the wall. The filtrate is directed into a flowline for collection. The feedstream fluid is then arranged to flow through the filter element in the other direction, to remove contaminant material from a surface of the element wall. Following removal of contaminant material, the feedstream fluid is continued to be directed through the wall of the filter element in said other direction, to filter out contaminants from the fluid during flow in said other direction.

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.

A system and process for removing divalent ions from a MEG feed stream is presented. Embodiments of the system include a chemical treatment tank where chemicals are mixed with the feed stream to form insoluble carbonate and hydroxide salts. The system also includes a solid-liquid separation unit that receives the feed stream from the chemical treatment tank and separates it into a liquids portion containing MEG and a insoluble salts portion. The system may also include washing the insoluble salts portion to remove additional MEG, which is then recycled to a MEG regeneration or reclamation process. The system may also include a dryer that receives waste slurry from the solid-liquid separation unit and dries it to form a solid waste, thereby facilitating its handling, storage, and disposal.

A combined chlorine agent having a low concentration of free chlorine and a high concentration of combined chlorine whereby the combined chlorine concentration of water can be increased when added to water systems at a low concentration of free chlorine. The combined chlorine agent is an aqueous agent which contains an alkali metal hydroxide, sulfamic acid, and an oxidizing agent based on chlorine, wherein the compositional ratio of the oxidizing agent based on chlorine to the sulfamic acid is in the range from 0.45 to 0.6 by Cl/N (mole ratio), the compositional ratio of the oxidizing agent based on chlorine to alkali is in the range from 0.3 to 0.4 by Cl/alkali metal (mole ratio), and the free chlorine concentration in the aqueous agent is 2% by weight or lower of the total chlorine concentration.

A system and process for removing divalent ions from a MEG feed stream is presented. The system includes a chemical treatment tank where chemicals are mixed with the feed stream to form insoluble carbonate and hydroxide salts. The system also includes a solid-liquid separation unit that receives the feed stream from the chemical treatment tank and separates it into a liquids portion containing MEG and a insoluble salts portion. The system may also include washing the insoluble salts portion to remove additional MEG, which is then recycled to a MEG regeneration or reclamation process. The system may also include a dryer that receives waste slurry from the solid-liquid separation unit and dries it to form a solid waste, thereby facilitating its handling, storage, and disposal.

A cleaning-in-place method for cleaning a membrane filter module, the membrane filter module including a membrane having a feed side and a permeate side and being configured to filter a fluid passing through the membrane from the feed side to the permeate side; wherein the method comprises performing a sequence of process cycles, the sequence comprising at least one monitored process cycle, the monitored process cycle comprising: providing a flow of a liquid through the membrane and/or across the feed side of the membrane; monitoring at least one hydraulic parameter associated with the provided flow of the liquid; and terminating the flow of the liquid, when the at least one monitored hydraulic parameter meets a predetermined cycle completion criterion.