A water purification system includes: a composite filter cartridge including a pretreatment filter cartridge and a filter membrane assembly; a raw water inlet pipe; a pure water outlet pipe; a pretreated water pipe; a booster pump; a water quality detecting device disposed to the raw water inlet pipe and/or the pure water outlet pipe and configured to detect water quality in the raw water inlet pipe and the pure water outlet pipe; and a control device connected to the water quality detecting device and configured to determine service life of the composite filter cartridge and/or judge whether the composite filter cartridge has lost efficacy according to information detected by the water quality detecting device.

A reverse osmosis treatment device includes: a first pressure vessel for treating an untreated water to produce a primarily treated water and a first permeated water; a second pressure vessel for treating the primarily treated water to produce a secondarily treated water and a second permeated water; a first cleaning solution tank for storing a first cleaning solution for cleaning the first pressure vessel; and a second cleaning solution tank for storing a second cleaning solution for cleaning the second pressure vessel. Each of the first pressure vessel and the second pressure vessel has therein a reverse osmosis membrane element having a reverse osmosis membrane. The first cleaning solution tank is connected to the first concentrate outlet pipe of the first pressure vessel, and the second cleaning solution tank is connected to the inlet pipe for the primarily treated water of the second pressure vessel.

A reverse osmosis treatment device includes: a first pressure vessel for treating an untreated water to produce a primarily treated water and a first permeated water; a second pressure vessel for treating the primarily treated water to produce a secondarily treated water and a second permeated water; a first cleaning solution tank for storing a first cleaning solution for cleaning the first pressure vessel; and a second cleaning solution tank for storing a second cleaning solution for cleaning the second pressure vessel. Each of the first pressure vessel and the second pressure vessel has therein a reverse osmosis membrane element having a reverse osmosis membrane. The first cleaning solution tank is connected to the first concentrate outlet pipe of the first pressure vessel, and the second cleaning solution tank is connected to the inlet pipe for the primarily treated water of the second pressure vessel.

The present invention relates to a system and process for treating a feedwater wherein the system includes at least one RO or nanofiltration unit that receives a feed under high pressure and produces a concentrate that is directed to and held at low pressure in a concentrate accumulator. Generally the permeate or the inlet feedwater is maintained at a constant flow rate. Periodically the system is switched from a mode 1 or normal operating process to a mode 2 where the concentrate is drained from the concentrate accumulator. However, in mode 2, the feedwater is still directed into the system and through the RO or nanofiltration unit which produces the permeate and the concentrate.

The present invention relates to a system and process for treating a feedwater wherein the system includes at least one RO or nanofiltration unit that receives a feed under high pressure and produces a concentrate that is directed to and held at low pressure in a concentrate accumulator. Generally the permeate or the inlet feedwater is maintained at a constant flow rate. Periodically the system is switched from a mode 1 or normal operating process to a mode 2 where the concentrate is drained from the concentrate accumulator. However, in mode 2, the feedwater is still directed into the system and through the RO or nanofiltration unit which produces the permeate and the concentrate.

A control valve for a reverse osmosis water purifying system provides a feed water port, a squeeze water port, a drain port, and a product water connection, each of which open into a bore. A first, second, and third O-rings are located in the bore successively between the feed water port, the squeeze water port, the drain port, and the product water connection. A control piston is moveably located in the bore of the housing. The control piston includes a vent/drain well in which a side is chamfered and at least one recess disposed around an end of the control piston. The vent/drain well provides a fluid passage between the squeeze water port and the drain port when the vent/drain well passes over the second O-ring. The fluid passage includes an opening formed between the second O-ring and the chamfered side of the vent/drain well, where the size of the opening is responsive to the position of the control piston.

A control valve for a reverse osmosis water purifying system provides a feed water port, a squeeze water port, a drain port, and a product water connection, each of which open into a bore. A first, second, and third O-rings are located in the bore successively between the feed water port, the squeeze water port, the drain port, and the product water connection. A control piston is moveably located in the bore of the housing. The control piston includes a vent/drain well in which a side is chamfered and at least one recess disposed around an end of the control piston. The vent/drain well provides a fluid passage between the squeeze water port and the drain port when the vent/drain well passes over the second O-ring. The fluid passage includes an opening formed between the second O-ring and the chamfered side of the vent/drain well, where the size of the opening is responsive to the position of the control piston.

The present invention relates to a method of controlling a fresh-water production apparatus for treating a raw water in stages by N-stage (N is a natural number of 2 or larger) water treatment methods, the method including: a filtration-characteristic prediction step; a filtration-characteristic deviation assessment step; a filtration-characteristic deviation assessment step; a cyclic prediction calculation step; a control condition recording step; a cyclic prediction calculation step; and a control condition recording step, in which the fresh-water production apparatus is controlled on the basis of the control condition recording step for the (n−1)-th stage water treatment method and the control condition recording step for the n-th stage water treatment method.

Citric acid is purified to remove metal ions through a two-step filtration process. A first filter is used to perform a first filtration, then a second filter is used to perform a second filtration on citric acid solution that has been subject to the first filtration. The first and second filters can include the same filter membrane material. The filter used as the first filter can be a relatively dirtier, more loaded filter compared to the filter used as the second filter. The first filtration can be performed over four hours of recirculating the citric acid solution through the first filter, and the second filtration can be performed over approximately two and one half hours of recirculating the citric acid solution through the second filter. Such a purification process can remove calcium and magnesium ions to render citric acid suitable as a cleaning solution in semiconductor processing.

Some embodiments of the invention provide a reverse osmosis water filtration system including a housing, a pre-filter cartridge, a reverse osmosis cartridge, and a post treatment cartridge. A medial water line transports a first portion of pretreated water from the pre-filter cartridge to the reverse osmosis cartridge. An unfiltered water line includes a flow restrictor and blend valve. The unfiltered water line is fluidly coupled between the medial water line and a blend water line. The blend water line receives filtered water at a first flowrate from the reverse osmosis cartridge and unfiltered water at a second flowrate from the blend valve. The first flowrate and the second flowrate are substantially equal to produce a consistent total dissolved solids value.