The present invention relates to a desalination apparatus and a desalination method using the same. In one specific embodiment, the desalination apparatus comprises: a forward osmosis unit having a draw-solution part into which seawater flows, and a raw water part into which raw water flows, and having an osmosis membrane, formed between the draw solution part and the raw water part, so as to respectively generate first treated water and first concentrated water; a capacitive deionization unit, which is connected to the draw solution part through a first inflow passage, and into which the first treated water of the draw solution part flows so as to generate second treated water; and an electrodialysis unit, which is connected to the raw water part through a second inflow passage, and into which the first concentrated water of the raw water part flows so as to generate third treated water.

Methods and system for real-time monitoring and control of an ultrafiltration/diafiltration (UF/DF) conditioned pool in a UF/DF recovery tank are disclosed. In various embodiments, a UF/DF pool is received at a recovery tank for conditioning or dilution by a buffer. Inline Raman measurements of the conditioned UF/DF pool may be performed and provided to a trained machine learning model as input. The machine learning model can then predict product quality attributes of the UF/DF conditioned pool, examples of said product quality attributes including protein concentration and osmolality of the conditioned UF/DF pool.

The water treatment device according to the present disclosure includes: an electrochemical cell having electrodes including a positive electrode and a negative electrode, and a bipolar membrane; a tank; a power supply configured to apply power to the electrodes; a water circulation flow path having at least the tank and the electrochemical cell and through which water circulates; a circulation device configured to circulate water in the water circulation flow path; a raw water supply path configured to supply raw water to the water circulation flow path; and a control device. In performing water softening treatment in the electrochemical cell where power is applied to the electrodes so as to remove ions from raw water and soft water is produced, the control device drives the circulation device so as to circulate water in the water circulation flow path.

A method for treating an etching solution in order to circulate and reuse an etching solution used in etching treatment of silicon includes (1) selectively removing multivalent ions having a valence of two or more, or (2) removing multivalent ions having a valence of two or more, 20-50% of alkali metal ions having a valence of one relative to a total amount of the alkali metal ions, and hydroxide ions, through a membrane separation unit comprising a nanofiltration membrane. A permeated solution of the membrane separation unit is circulated to the etching bath.

A method for treating an etching solution in order to circulate and reuse an etching solution used in etching treatment of silicon includes (1) selectively removing multivalent ions having a valence of two or more, or (2) removing multivalent ions having a valence of two or more, 20-50% of alkali metal ions having a valence of one relative to a total amount of the alkali metal ions, and hydroxide ions, through a membrane separation unit comprising a nanofiltration membrane. A permeated solution of the membrane separation unit is circulated to the etching bath.

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.

An object is to provide a pretreatment device of seawater capable of growing and maintaining a biofilm in a good state on each of a plurality of filters connected in series, by supplying nutrients appropriately to the filters. A pretreatment device of seawater is used in removing salt from the seawater to obtain freshwater, and includes: a supply duct (21) through which the seawater is to be supplied; a plurality of filters (16) including a particulate filtering material and a biofilm; connecting tubes (23) which connect the plurality of filters in series; a plurality of bypass tubes (24) each of which connects corresponding one of the plurality of filters to the supply duct; and a plurality of regulating valves (26) each of which is disposed in corresponding one of the plurality of bypass tubes to regulate a flow rate.

An object is to provide a pretreatment device of seawater capable of growing and maintaining a biofilm in a good state on each of a plurality of filters connected in series, by supplying nutrients appropriately to the filters. A pretreatment device of seawater is used in removing salt from the seawater to obtain freshwater, and includes: a supply duct (21) through which the seawater is to be supplied; a plurality of filters (16) including a particulate filtering material and a biofilm; connecting tubes (23) which connect the plurality of filters in series; a plurality of bypass tubes (24) each of which connects corresponding one of the plurality of filters to the supply duct; and a plurality of regulating valves (26) each of which is disposed in corresponding one of the plurality of bypass tubes to regulate a flow rate.

A multi-stage polymeric membrane module system separates a gas, such as air, into components of high purity. In at least two of the stages, a portion of the retentate gas is directed into the low-pressure side of the module, to act as a sweep gas. The use of the sweep gas reduces the partial pressure of permeate gas on the low-pressure side of the membrane, and therefore improves the flow of permeate through the membrane. In a preferred embodiment, there are three modules. The output streams are taken from the retentate outlet of one module, and from the permeate outlet of another module. The output streams have very high purity, relative to the number of modules required, as compared with systems of the prior art.

The formation of scale in a reverse osmosis membrane apparatus is reduced at low water temperatures without the necessity of pH adjustment or addition of a scale dispersant to continue a consistent operation for a long period of time. The operation of a reverse osmosis membrane apparatus is controlled on the basis of the concentration of aluminum ions and/or iron ions in the feed to the reverse osmosis membrane apparatus and/or the concentrate from the reverse osmosis membrane apparatus. Not only silica but also aluminum ions and iron ions that are also present in the water significantly affect the reduction in the flux of a reverse osmosis membrane which is caused by silica scale. It is necessary to appropriately control the concentration of aluminum ions and/or iron ions in the feed and/or the concentrate to consistently operate a reverse osmosis membrane apparatus for a long period of time.