Reverse osmosis filtration system

Abstract

A reverse osmosis filtration system includes an automatic flushing filtration membrane to prevent total dissolved solids (TDS) ramping.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 356,614 filed on June 29, 2022, the disclosure of which is expressly incorporated herein by reference.

[0003] Background and Summary of the Invention

[0004] The present invention generally relates to a reverse osmosis filtration system, and more particularly to a reverse osmosis filtration system including automatic flushing of the filtration membrane to prevent total dissolved solids (TDS) ramping.

[0005] It is known to provide tankless reverse osmosis (RO) systems to provide point-of-use (POU) (e.g., tap) filtered water for drinking and / or cooking. However, such conventional systems are typically affected by total dissolved solids (TDS) ramp. TDS ramp is referred to in the art as the rate at which dissolved solids migrate through the filtration membrane of an RO system when the system is stagnant.

[0006] In response to the TDS ramp, the user may flush the RO system before each use. However, this approach may be inefficient, particularly in the case of a tankless RO system. More particularly, due to the amount of contaminants in a typical tankless RO system, it takes a relatively long time to clear the water, thereby negating the convenience and efficiency advantages of such a tankless RO system. Existing tankless RO systems may include various forms of automatic flushing in an attempt to mitigate the TDS ramp, but with limited success.

[0007] The present invention relates to a reverse osmosis (RO) filtration system which is configured to flush the dirty or concentrating side of a filtration membrane with filtered water after use so that both sides of the large surface area filtration membrane are in equilibrium and no (or minimal) contaminants pass through the membrane (i.e., TDS ramp-up).

[0008] According to an illustrative embodiment of the present disclosure, a reverse osmosis filtration system includes a filter membrane including a concentration side and a permeation side. The concentration side of the filter membrane is in fluid communication with a tap water inlet. The permeation side of the filter membrane is configured to be in fluid communication with a faucet. A flushing reservoir is in fluid communication with the permeation side of the filter membrane. A flushing outlet valve is fluidly coupled between the flushing reservoir and the concentration side of the filter membrane.

[0009] According to another illustrative embodiment of the present disclosure, a reverse osmosis filtration system includes a filter membrane including a concentrate side and a permeate side. The concentrate side of the filter membrane is in fluid communication with a tap water inlet and a waste pipe. The permeate side of the filter membrane is configured to be in fluid communication with a faucet. A reservoir is in fluid communication with the permeate side of the filter membrane. An electrically operable control valve provides selective fluid communication from the permeate side of the filter membrane to the waste pipe or to the reservoir. A pump is fluidly coupled between the tap water inlet and the concentrate side of the filter membrane. A controller is operably coupled to the control valve and the pump.

[0010] According to another illustrative embodiment of the present disclosure, a reverse osmosis filtration system includes a filter membrane including a concentration side and a permeation side. A tap water inlet is fluidically connected to the concentration side of the filter membrane. A tap water inlet valve is fluidly connected between the tap water inlet and the concentration side of the filter membrane. A waste pipe is fluidically connected to the concentration side of the filter membrane. A non-pressurized reservoir is fluidically connected to the permeation side of the filter membrane. A flushing valve is fluidly connected between the permeation side of the filter membrane and the non-pressurized reservoir. A pressure sensor is operably connected to the permeation side of the filter membrane. A controller is operably connected to the tap water inlet valve, the flushing valve, and the pressure sensor.

[0011] According to another illustrative embodiment, a reverse osmosis filtration system includes a tap water inlet, a first water inlet valve fluidly connected downstream of the tap water inlet, and a pump fluidly connected downstream of the tap water inlet valve. The filter membrane includes a concentration side and a permeate side. The second water inlet valve includes an inlet fluidly connected to the permeate side of the filter membrane, and an outlet fluidly connected to the pump, the outlet being used to supply water from the second water inlet valve between the first water inlet valve and the pump. The pump, the filter membrane, and the second water inlet valve define a circulation loop. The waste pipe is fluidly connected downstream of the concentration side of the filter membrane. The controller is operably connected to the first water inlet valve, the pump, and the second water inlet valve. Illustratively, the dilution reservoir can be arranged in series in the circulation loop.

[0012] According to another illustrative embodiment of the present disclosure, a reverse osmosis filtration system includes a tap water inlet, a first water inlet valve fluidly connected to the tap water inlet, and a pump fluidly connected downstream of the first water inlet valve. The filter membrane includes a concentration side and a permeate side. The second water inlet valve includes an inlet fluidly connected to the permeate side of the filter membrane, and an outlet fluidly connected to the pump, the outlet being used to supply water from the second water inlet valve between the first water inlet valve and the pump. The first water inlet valve and the second water inlet valve each include an electrically operable valve. A waste pipe is fluidly connected downstream of the concentration side of the filter membrane. The controller is operably connected to the first water inlet valve, the pump, and the second water inlet valve. A dilution reservoir is fluidly connected downstream of the permeate side of the filter membrane. The dilution reservoir illustratively includes a volatile organic compound filter.

[0013] Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of illustrative embodiments which illustrate the best mode presently believed to be carrying out the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The detailed description of the drawings is directed in particular to the accompanying drawings, in which:

[0015] Figure 1 is a schematic diagram of an illustrative reverse osmosis filtration system in the form of a flush-only zero-pressure reservoir system;

[0016] Figure 2 is a schematic diagram of an illustrative reverse osmosis filtration system in the form of a flush-only low-pressure reservoir system;

[0017] Figure 3 is a schematic diagram of an illustrative reverse osmosis filtration system in the form of a true hybrid system with a transfer pump; and

[0018] Figure 4 is a schematic diagram of an illustrative reverse osmosis filtration system in the form of a true hybrid system having a water-to-water tank;

[0019] Figure 5 is a schematic diagram of an illustrative reverse osmosis filtration system in the form of a true hybrid system without pre-flush;

[0020] Figure 6 is a schematic diagram of an illustrative reverse osmosis filtration system in the form of a hybrid osmosis backwash (OBW) flushing system; and

[0021] Figure 7 is a schematic diagram of an illustrative reverse osmosis filtration system in the form of a tankless pure system with flushing. DETAILED DESCRIPTION

[0022] The embodiments of the invention described herein are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Rather, the embodiments selected for description are selected to enable one skilled in the art to practice the invention. In the following illustrative drawings, solid lines represent fluid lines or conduits, and dashed lines represent wires or conductors.

[0023] Figure 1An illustrative reverse osmosis (RO) filtration system 100 is shown, which is defined as a pump-flushed, flush-only zero-pressure reservoir system. More particularly, the system 100 is fluidly coupled to a conventional tap water source 102 via a tap water inlet valve 104 (illustratively an electrically operable valve, such as a solenoid valve). A reverse osmosis (RO) filter membrane 106 is fluidly coupled to the tap water inlet valve 104 upstream via a pump 108. As is known, the illustrative filter membrane 106 includes a dirty side or concentrate side 110 and a permeate side or purification side 112. The filter membrane 106 can be a conventional reverse osmosis filter membrane available from a variety of sources, such as Flowtech, Inc., Kalamazoo, Michigan. The pump 108 can include a conventional electric water pump available from a variety of different sources.

[0024] The concentrate side 110 of the filter membrane 106 is fluidly coupled upstream to the pump 108 and the tap water inlet valve 104. The concentrate side 110 of the filter membrane 106 is fluidly coupled downstream to a waste pipe 114 through a waste valve 116 (illustratively an electrically operable valve, such as a solenoid valve). The permeate side 112 of the filter membrane 106 is fluidly coupled downstream to an outlet fluid line 118. The outlet fluid line 118 illustratively includes a T-fitting or connector 119 that allows fluid communication between the permeate side 112 of the filter membrane 106 and a fluid delivery device (such as a faucet 120) and a rinse-only reservoir 122.

[0025] The faucet 120 can be of conventional design, including a valve 121 that controls the flow of water to the outlet 123. The valve 121 can be a manual valve or an electrically operable valve (e.g., a solenoid valve) in electrical communication with the controller 130. Illustratively, a sensor can be operably coupled to the faucet 120 to provide an indication of the flow of water through the water outlet 123 to the controller 130. Such a sensor can include, for example, a flow sensor or a position sensor coupled to the faucet valve 121.

[0026] Reservoir 122 is illustratively a zero pressure (ie, unpressurized) tank or container. Further, reservoir 122 is illustratively only large enough to hold the volume of water required to provide a membrane flushing cycle.

[0027] The flushing inlet valve 124 is fluidly connected between the permeate side 112 of the filter membrane 106 and the reservoir 122. Illustratively, the flushing inlet valve 124 is an electrically operable valve, such as a solenoid valve. An optional check valve 126 may be fluidly connected upstream of the flushing inlet valve 124. The flushing outlet valve 128 is fluidly connected between the reservoir 122 and the pump 108. Likewise, the flushing outlet valve 128 may be an electrically operable valve, such as a solenoid valve. The flushing outlet valve 128 is configured to supply water from the reservoir 122 to the pump 108. In other illustrative embodiments, the flushing outlet valve 128 may be a check valve, which is typically a cheaper option than an electrically operable valve. The pressure of the tap water from the water source 102 is higher than the water pressure from the reservoir 122, thereby keeping the check valve closed during normal use.

[0028] Illustratively, controller 130 is operably coupled to electrically operable valves 104, 116, 124, 128 and pump 108 to control operation thereof. More particularly, controller 130 may include a processor or central processing unit (CPU) and a memory storing machine-readable instructions executed by the processor.

[0029] During normal water dispensing operation (i.e., normal dispensing mode) of the illustrative filtration system 100, the tap water inlet valve 104 is open, and the pump 108 pushes water through the filter membrane 106 and the open faucet valve 121, so that water is dispensed from the outlet 123 of the faucet 120. At this time, the rinse inlet valve 124, the rinse outlet valve 128, and the waste valve 116 are illustratively closed. After dispensing water from the faucet 120, the rinse inlet valve 124 is opened, and the pump 108 continues to push water through the filter membrane 106 to fill the reservoir 122.

[0030] After the faucet 120 has not been used for a predetermined period of time (e.g., five minutes), the illustrative filtration system 100 enters a flushing operation (i.e., a flushing mode). In this mode, the flush outlet valve 128 and the waste valve 116 are opened, and the pump 108 is reactivated and draws filtered water from the reservoir 122 to flush the concentrating side 110 of the filter membrane 106. As described above, the controller 130 illustratively controls the operation of the various electrical components of the filtration system 100 (e.g., the electrically operable valves 104, 116, 124, 128 and the pump 108).

[0031] Figure 2 An illustrative reverse osmosis (RO) filtration system 200 is shown that is defined as a flush-only low-pressure reservoir system that provides a silent flush. Figure 2 The illustrative filtering system 200 includes a number of Figure 1 The filter system 100 has similar features. Therefore, in the following description, the same reference numerals identify similar components.

[0032] The illustrative filtration system 200 includes a flush-only reservoir 222 with low pressure water. The water pressure in the reservoir 222 is illustratively less than 20 psi, and preferably 10 psi or less. The reservoir water pressure is illustratively sufficient to gradually flush the filter membrane 106 without being large enough to deliver water through the faucet 120. Illustratively, the reservoir 222 is only large enough to hold the volume of water required to provide a membrane flush cycle. Illustratively, the flush outlet valve 128 is in direct fluid communication upstream with the concentrate side 110 of the filter membrane 106 ( Figure 2 ), rather than being in direct fluid communication with the pump 108 of the filtration system 100 ( Figure 1 ).

[0033] During operation of the illustrative filtration system 200, after dispensing water from the faucet 120 in the normal dispensing mode, the user closes the valve 121. Next, the controller 130 causes the rinse inlet valve 124 to open, and the pump 108 continues to push water through the filter membrane 106 to fill the reservoir 222. At this point, the tap water inlet valve 104 is open, while the rinse outlet valve 128 and the waste valve 116 are closed.

[0034] After faucet 120 has not been used for a predetermined period of time (e.g., five minutes), controller 130 enters a flush mode in which flush outlet valve 128 and waste valve 116 are opened and the low pressure in reservoir 222 slowly pushes water to flush concentrating side 110 of filter membrane 106. Likewise, controller 130 illustratively controls the operation of various electrical components of filtration system 200 (e.g., electrically operable valves 104, 116, 124, 128 and pump 108).

[0035] Figure 3 An illustrative reverse osmosis (RO) filtration system 300 is shown, which is defined as a true hybrid system with a transfer pump system. Figure 3 The illustrative filtration system 300 includes a number of Figure 1 The filter system 100 has similar features. Therefore, in the following description, the same reference numerals identify similar components.

[0036] Further references Figure 3 , the illustrative reservoir 122 is twice as large as the volume required for flushing. A transfer pump 332 is fluidly coupled between the reservoir 122 and the faucet 120 .

[0037] During operation of the illustrative filtration system 300, after dispensing water from the faucet 120 in the normal dispensing mode, the user closes the faucet valve 121. Next, the controller 130 causes the rinse inlet valve 124 to open, and the pump 108 continues to push water through the filter membrane 106 to fill the reservoir 122. At this time, the tap water inlet valve 104 is open, while the rinse outlet valve 128 and the waste valve 116 are closed. After the faucet 120 is not used for a predetermined time (e.g., five minutes), the controller 130 enters a rinse mode in which the rinse outlet valve 128 and the waste valve 116 are opened and the supply pump 108 pumps water to rinse the concentrating side 110 of the filter membrane 106.

[0038] The transfer pump 332 can be activated by the controller 130 to supply water from the reservoir 122 to the faucet 120. More specifically, when the user again draws water through the faucet valve 121, water is initially supplied from the reservoir 122 to the faucet 120 through the transfer pump 332, so that flushing is not then required. For dispensing a volume less than a flush, this reduces the flushing by at least two times. Similarly, the controller 130 illustratively controls the operation of the various electrical components of the filtration system 300 (e.g., the electrically operable valves 104, 116, 124, 128 and the pumps 108, 332).

[0039] Figure 4 An illustrative reverse osmosis (RO) filtration system 400 is shown, which is defined as a true hybrid system with a water-to-water tank. Figure 4 The illustrative filtration system 400 includes a number of Figure 3 The filter system 300 has similar features. Therefore, in the following description, the same reference numerals identify similar components.

[0040] Illustratively, the reservoir 422 is twice as large as the volume required for flushing and includes a filtered (or purified) water portion 423 and a tap water portion 425. A flexible diaphragm 428 illustratively separates the filtered water portion 423 from the tap water portion 425. The filtered water portion 423 of the reservoir 422 is in fluid communication with the permeate side 112 of the filter membrane 106 through the flush inlet valve 124. The tap water portion 425 of the reservoir 422 is in fluid communication with the tap water inlet 102 through the tap water inlet valve 104. Check valves 430a and 430b may be provided that prevent backflow toward the flush outlet valve 128 and the reservoir 422, respectively.

[0041] After dispensing water from the faucet 120 in the normal dispensing mode, the user closes the faucet valve 121. Next, the controller 130 causes the rinse inlet valve 124 to open, and the pump 108 continues to push water through the filter membrane 106 to fill the reservoir 422. At this time, the tap water inlet valve 104 is open, while the rinse outlet valve 128 and the waste valve 116 are closed. Filtered water is pushed into the reservoir 422 from one side of the membrane 428 (i.e., the filtered water portion 423), and tap water is drawn out of the reservoir 422 from the other side of the membrane 428 (i.e., the tap water portion 425) until the reservoir is full.

[0042] After the faucet 120 has not been used for a predetermined time (e.g., five minutes), the controller 130 enters a flush mode in which the flush outlet valve 128, the waste valve 116, and the tap water inlet valve 104 are opened to allow tap water to be pushed into the reservoir 422, thereby pushing the filtered water out to flush the concentrating side 110 of the filter membrane 106 and flow to the waste pipe 114. More specifically, the flush outlet valve 128 provides water to the concentrating side 110 of the membrane 106.

[0043] When the user again draws water through the faucet valve 121, water is initially supplied from the reservoir 422 by the pump 332, so that flushing is not required. For dispensing a volume less than a flush, the system 400 reduces the flushing by at least two times. Likewise, the controller 130 illustratively controls the operation of the various electrical components of the filtration system 400 (e.g., the electrically operable valves 104, 116, 124, 128 and the pumps 108, 332).

[0044] Figure 5 An illustrative reverse osmosis (RO) filtration system 500 is shown, which is defined as a true hybrid system without a pre-flush. Figure 5 The illustrative filtration system 500 includes a number of Figure 4 The filter system 400 has similar features. Therefore, in the following description, the same reference numerals identify similar components.

[0045] like Figure 5 As shown, a control valve 521 (e.g., a three-way valve) is fluidly coupled to the filter membrane 106. The control valve 521 is illustratively an electrically operable valve that is in electrical communication with the controller 130. More specifically, the illustrative three-way valve 521 includes an inlet fluidly coupled to the permeate side 112 of the filter membrane 106 upstream; a first outlet fluidly coupled to the waste pipe 114 downstream through a T-shaped fitting or connector 522; and a second outlet fluidly coupled to a T-shaped fitting or connector 523 downstream, which in turn is fluidly coupled to the faucet 120 and the reservoir 122 (through a reservoir valve 524). The reservoir valve 524 can be an electrically operable valve, such as a solenoid valve, that is operably coupled to the controller 130.

[0046] Illustratively, reservoir 122 is of a size required to provide sufficient water until the contaminated water is drained (e.g., about 1 quart). Illustratively, reservoir 122 is pressurized. Instead of a pressurized reservoir 122, a zero pressure reservoir and transfer pump may be used.

[0047] After the user stops dispensing water in the normal dispensing mode and closes the valve 121 of the faucet 120, the controller 130 opens the reservoir valve 524 and instructs the pump 108 to keep running until the reservoir 122 is full. Illustratively, a water level sensor (e.g., a float sensor or an electrical contact) can be operably connected to the reservoir 122 to provide a signal indicating the volume of water in the reservoir 122 to the controller 130. At this time, the tap water inlet valve 104 is open and the waste valve 116 is closed. If there is no water flowing through the faucet 120 for a sufficient time, the water in the filter membrane 106 may be contaminated by the slow rise of total dissolved solids (TDS) before the user dispenses water again. In response, the controller 130 enters a flushing mode in which water is supplied to the user from the reservoir 122 through the open reservoir valve 524, and the three-way valve 521 directs water from the filter membrane 106 to the waste pipe 114 until the water is clean enough for use.

[0048] An optional TDS sensor 525 can be used to adjust the amount of water diverted to the drain pipe 114. The TDS sensor 525 can have a conventional design for measuring the amount of total dissolved solids (TDS) in the water. The TDS sensor 525 is fluidly connected between the permeate side 112 of the filter membrane 106 and the 3-way valve 521, and is electrically connected to the controller 130. Similarly, if the system 500 is not deactivated for a long time, the water from the reservoir 122 can be used to enhance the initial water flow rate (characteristics for the user). The controller 130 illustratively controls the operation of each electrical component of the filtration system 500 (e.g., electrically operable valves 104, 116, 521, 524, pump 108, and TDS sensor 525) and / or receives input from it.

[0049] Figure 6 An illustrative reverse osmosis (RO) filtration system 600 is shown, which is defined as a hybrid osmosis backwash (OBW) flushing system. Figure 6 The illustrative filtration system 600 includes a number of Figure 1 The filter system 100 has similar features. Therefore, in the following description, the same reference numerals identify similar components.

[0050] like Figure 6As shown, a flushing valve 524 (illustratively an electrically operable valve, such as a solenoid valve) is fluidly coupled between the permeate side 112 of the filter membrane 106 and the reservoir 122. The reservoir 122 is illustratively unpressurized (i.e., zero pressure) and is only the size required for flushing the filter membrane 106. Illustratively, a pressure sensor 625 is fluidly coupled between the permeate side 112 of the filter membrane 106 and the faucet 120 and is in electrical communication with the controller 130. The pressure sensor 625 has a conventional design for measuring water pressure. Illustratively, a check valve 526 is positioned upstream of the pressure sensor 625.

[0051] After dispensing water from the faucet 120 during normal mode, the user closes the faucet valve 121. Next, the controller 130 causes the water inlet valve 104 to open, and the pump 108 continues to push water through the filter membrane 106 until the reservoir 122 is full. At this point, the waste valve 116 is closed, and the flush valve 524 is opened. Since the reservoir 122 does not capture air pressure, the pressure remains stable and then builds up immediately when the reservoir 122 is full, thereby triggering the pressure sensor 625.

[0052] In response to the sensor 625 detecting the pressure increase, the controller 130 enters the flush mode by shutting down the pump 108 and closing the tap water inlet valve 104. The waste valve 116 is open, and due to the dynamic pressure on the concentrate side 110 of the filter membrane 106 and the lack of a pressurized reservoir on the permeate side 112 of the filter membrane 106, no significant back pressure is generated on the filter membrane 106 when the system 600 is depressurized. It should be understood that other methods can be used to protect the membrane 106 from the effects of back pressure.

[0053] As the mechanical pressure drops, osmotic pressure takes over and draws water from the permeate side 112 of the filter membrane 106 to the concentrate side 110 of the filter membrane 106. Because this flow is concentration driven, it efficiently flushes the concentrate side 110 over the entire membrane area. The check valve 526 illustratively maintains the pressure at the pressure sensor 625 and the faucet 120. When the faucet valve 121 is opened, the pressure at the faucet 120 drops, and the controller 130 starts the pump 108 again. The cycle is then repeated. Similarly, the controller 130 illustratively controls the operation of and / or receives input from the various electrical components of the filtration system 600 (e.g., the electrically operable valves 104, 116, 524, the pump 108, and the pressure sensor 625).

[0054] Figure 7 is an illustrative reverse osmosis (RO) filtration system 700, which is defined as a tankless clean system with flushing. Figure 7 The system 700 includes many Figure 5 Filtration system 500 and Figure 6The filter system 600 has similar features. Therefore, the same reference numerals identify similar components.

[0055] like Figure 7 As shown, the illustrative system 700 can include an optional three-way valve 719 in fluid communication with a conventional tap water source 102. For example, during maintenance, the valve 719 can be closed so that water cannot be provided from the tap water source 102. A first or tap water inlet valve 104 is fluidly connected downstream of the three-way valve 719. Illustratively, a dilution reservoir 724 is fluidly connected downstream of the filter membrane 106. As further detailed herein, the dilution reservoir 724 is configured to receive and store water that passes through the filter membrane 106. The dilution reservoir 724 illustratively includes a volatile organic compound (VOC) filter. The VOC filter 724 is illustratively a conventional carbon filter configured to remove or reduce volatile organic compounds (VOCs) from water. A check valve 526 can be fluidly connected between the optional VOC filter 724 and the faucet 120.

[0056] Fluidically coupled downstream of the filter membrane 106 and optional VOC filter 724 is a flush valve 721. The flush valve 721 illustratively comprises an electrically operable valve, such as a solenoid valve. A check or non-return valve 723 may be fluidly coupled downstream of the flush valve 721.

[0057] Illustratively, pump 108, filter membrane 106, VOC filter 724, flush valve 721, and check valve 723 define a circulation loop 722. Thus, water from the outlet of pump 108 is supplied to filter membrane 106, where filtered water passes through VOC filter 724, reaches branch or T-junction 725, reaches flush valve 721, passes through check valve 723, and returns to the inlet of pump 108 (e.g., see arrow 728 representing circulating water flow). VOC filter 724 downstream of membrane 106 illustratively acts as a buffer for filtered water. By placing VOC filter 724 within circulation loop 722, the filter is flushed and refilled with water during each flush cycle.

[0058] An optional TDS sensor 525 is fluidly coupled between the permeate side 112 of the filter membrane 106 and the VOC filter 724 and upstream of the flush valve 721. The TDS sensor 525 is in electrical communication with the controller 130. The TDS sensor 525 can be used to monitor water quality and provide feedback to a user through the controller 130. In other illustrative embodiments, the controller 130 can control the operation of the system 700 (e.g., provide a flush cycle) in response to input from the TDS sensor 525.

[0059] Illustratively, a pressure sensor 625 (e.g., a high pressure switch) may be fluidly coupled between the permeate side 112 of the filter membrane 106 and the faucet 120 and in electrical communication with the controller 130. The controller 130 may determine whether water is flowing through the faucet 120 in response to the water pressure detected by the pressure sensor 625. More specifically, when the valve 121 is open and water is flowing through the outlet 123, the pressure sensor 625 detects little or no water pressure. However, when the valve 121 is closed and water is not flowing through the faucet 120, the valve 121 defines a restriction such that the water pressure detected by the pressure sensor 625 increases.

[0060] In normal water dispensing operation (i.e., normal dispensing mode) of the illustrative filtration system 700, the tap water inlet valve 104 is open, and the pump 108 pushes water through the filter membrane 106, the VOC filter 724, and the open faucet valve 121, so that water is dispensed from the outlet 123 of the faucet 120. At this time, the flush valve 121 and the waste valve 116 are illustratively closed.

[0061] After the faucet 120 has not been used for a predetermined time (e.g., five minutes), the water filtration system 700 enters a flushing operation (i.e., flushing mode) in which the controller 130 of the illustrative filtration system 700 opens both the tap water inlet valve 104 and the water inlet valve 721 and enables the pump 108 for a predetermined time to mitigate the TDS ramp. This draws in tap water from the inlet 102, pushes the water through the RO filter membrane 106, through the VOC filter 724, and dilutes the incoming tap water with the volume of purified water that has passed through the filter membrane 106, thereby diluting the TDS of the concentrate side 110 of the RO filter membrane 106 to the level of tap water within a predetermined time (e.g., about 1 minute of flushing (consuming less than about 1 quart)). Illustratively, this reduces the TDS ramp by more than half. Although TDS ramp may still occur, it is reduced to the small volume of water in the filter membrane 106 itself.

[0062] When the user turns on the faucet 120 to dispense water again, his / her first glass of water is relatively pure because the first glass of water comes from the water in the VOC filter 724. The second glass of water is also relatively pure, still mainly coming from the relatively pure water in the VOC filter 724. If the user draws a larger volume of water, it is diluted by this water from the VOC filter 724, thereby also significantly reducing the effect of the TDS ramp. Without this water from the VOC filter 724, the effect of the TDS ramp on the water quality may still be too high. If the user only draws one glass of water (e.g., about 8 ounces), the concentrate water is drawn into the VOC filter 724, but after the controller 130 operates in the rinse mode for a predetermined time (e.g., 5 minutes), the water is recycled back to the concentrate (dirty) side 110 of the filter membrane 106. Likewise, controller 130 illustratively controls the operation of and / or receives input from various electrical components of filtration system 700 , such as electrically operable valves 104 , 116 , 721 , pump 108 , TDS sensor 726 , and high pressure switch 727 .

[0063] The following description further details the advantages of the illustrative flushing system of the present disclosure over the prior art. If the VOC (e.g., carbon) filter 724 is positioned after the RO filter membrane 106 and is not in the flushing loop, the TDS ramping water enters the carbon filter 724 when the user takes a small amount of water (1 cup) and is not flushed out after use. In this way, as small amounts of water are used multiple times, TDS will accumulate in the downstream filter 724. In addition, the large VOC filter 724 easily absorbs any lead that does migrate through in the TDS (and some other dangerous contaminants that are easily absorbed by VOC-grade activated carbon), but because the filter 724 only contacts a very small volume of contaminants that ramp up in stagnation, it can be used for a long time and provide excellent lead removal performance (even after being left overnight, it can still remove lead almost completely).

[0064] The recirculation of system 700 also mitigates bacterial accumulation in the VOC filter 724 and RO membrane 106, since flushing also occurs every 12 hours. This helps because carbon filters have a large surface area, while RO systems can have problems when not used for long periods of time (days or weeks). All of this can also be accomplished without the large captured air storage tanks of canister-based systems, which can reduce efficiency due to back pressure and create stagnant water that can breed bacteria and give the water an off-flavor when it sits in a cup.

[0065] This is also true for VOCs that are partially removed by RO but not well removed by RO membrane 106. Placing filter 724 after RO membrane 106 avoids wasting VOC filter 724 on water flowing from RO membrane 106 to waste pipe 114. In addition, RO membrane 106 does partially reject VOCs, further extending the life of VOC filter 724.

[0066] Although the invention has been described in detail with reference to certain preferred embodiments, changes and modifications exist within the spirit and scope of the invention as described and defined in the following claims.

Claims

1. A reverse osmosis filtration system, comprising: A filtration membrane, the filtration membrane comprising a concentration side and a permeation side; wherein the concentration side of the filter membrane is in fluid communication with the tap water inlet; wherein the permeate side of the filter membrane is configured to be in fluid communication with a faucet; a flush reservoir in fluid communication with the permeate side of the filtration membrane; and A flush outlet valve is fluidly coupled between the flush reservoir and a concentrating side of the filter membrane.

2. The reverse osmosis filtration system of claim 1, further comprising a flush inlet valve fluidly coupled between the permeate side of the filtration membrane and the flush reservoir.

3. The reverse osmosis filtration system according to claim 2, wherein: The flush outlet valve and the flush inlet valve each comprise an electrically operable valve.

4. The reverse osmosis filtration system according to claim 3, wherein: The flush outlet valve and the flush inlet valve each include a solenoid valve.

5. The reverse osmosis filtration system of claim 2, further comprising a controller operably coupled to the flush outlet valve and the flush inlet valve.

6. The reverse osmosis filtration system of claim 1, further comprising a pump fluidly coupled between the tap water inlet, the flush outlet valve, and a concentrate side of the filtration membrane.

7. The reverse osmosis filtration system of claim 6, further comprising a tap water inlet valve fluidly coupled upstream of the pump.

8. The reverse osmosis filtration system according to claim 1, wherein: The flushing reservoir is a zero pressure reservoir.

9. The reverse osmosis filtration system of claim 1, wherein: The flushing reservoir includes a filtered water portion, a tap water portion, and a diaphragm separating the filtered water portion from the tap water portion; The filtered water portion of the flush reservoir is in fluid communication with the permeate side of the filter membrane; and The tap water portion of the flushing reservoir is in fluid communication with the tap water inlet.

10. The reverse osmosis filtration system of claim 1, further comprising a waste pipe in fluid communication with the concentrate side of the filtration membrane.

11. The reverse osmosis filtration system of claim 10, further comprising a waste valve in fluid communication between the concentrate side of the filtration membrane and the waste pipe.

12. The reverse osmosis filtration system according to claim 1, wherein: The flush outlet valve includes a check valve.

13. A reverse osmosis filtration system, comprising: A filtration membrane, the filtration membrane comprising a concentration side and a permeation side; The concentration side of the filter membrane is in fluid communication with a tap water inlet and a waste pipe; The permeate side of the filtration membrane is configured to be in fluid communication with a faucet; a reservoir in fluid communication with the permeate side of the filtration membrane; an electrically operable control valve providing selective fluid communication from the permeate side of the filtration membrane to the waste or to the reservoir; a pump fluidly coupled between the tap water inlet and a concentrate side of the filter membrane; as well as A controller is operably coupled to the control valve and the pump.

14. The reverse osmosis filtration system of claim 13, further comprising a tap water inlet valve fluidly coupled upstream of the pump.

15. The reverse osmosis filtration system of claim 13, further comprising a waste valve in fluid communication between the concentrate side of the filtration membrane and the waste pipe.

16. The reverse osmosis filtration system according to claim 15, wherein: The waste valve is an electrically operable valve in electrical communication with the controller.

17. The reverse osmosis filtration system of claim 13, further comprising a total dissolved solids sensor operably coupled to a permeate side of the filtration membrane and in electrical communication with the controller.

18. The reverse osmosis filtration system of claim 13, further comprising an electrically operable reservoir valve positioned between the control valve and the controller and in electrical communication with the controller.

19. The reverse osmosis filtration system according to claim 13, wherein: The control valve is a three-way valve.

20. A reverse osmosis filtration system, comprising: A filtration membrane, the filtration membrane comprising a concentration side and a permeation side; a tap water inlet, the tap water inlet being in fluid communication with the concentration side of the filter membrane; a tap water inlet valve fluidly coupled between the tap water inlet and a concentrating side of the filtration membrane; a waste pipe in fluid communication with the concentrate side of the filter membrane; a non-pressurized reservoir in fluid communication with the permeate side of the filtration membrane; a flush valve fluidly coupled between the permeate side of the filtration membrane and the non-pressurized reservoir; a pressure sensor operably coupled to the permeate side of the filtration membrane; as well as A controller is operably coupled to the tap water inlet valve, the flush valve, and the pressure sensor.

21. The reverse osmosis filtration system according to claim 20, wherein: The flush outlet valve and the flush inlet valve each comprise an electrically operable valve.

22. The reverse osmosis filtration system of claim 20, further comprising a pump fluidly coupled between the tap water inlet, the flush outlet valve, and a concentrate side of the filtration membrane, the pump operably coupled to the controller.

23. The reverse osmosis filtration system of claim 20, wherein: The flush reservoir is unpressurized.

24. The reverse osmosis filtration system of claim 20, further comprising a waste valve in fluid communication between the concentrate side of the filtration membrane and the waste pipe, the waste valve being operably coupled to the controller.

25. The reverse osmosis filtration system of claim 20, further comprising a faucet in fluid communication with the permeate side of the filtration membrane.

26. A reverse osmosis filtration system comprising: Water inlet; a water inlet valve fluidly coupled downstream of the tap water inlet; a pump fluidly coupled downstream of the first inlet valve; A filtration membrane, the filtration membrane comprising a concentration side and a permeation side; a flush valve including an inlet fluidly coupled to the permeate side of the filter membrane and an outlet fluidly coupled to the pump, the outlet for supplying water from the flush valve between the first water inlet valve and the pump; a circulation loop, the circulation loop being defined by the pump, the filter membrane and a second water inlet valve; a drain pipe fluidly coupled downstream of the concentrating side of the filtration membrane; as well as A controller is operably coupled to the first water inlet valve, the pump, and the second water inlet valve.

27. The reverse osmosis filtration system of claim 26, wherein: The first water inlet valve and the second water inlet valve each include an electrically operable valve.

28. The reverse osmosis filtration system of claim 26, further comprising a waste valve in fluid communication between the concentrate side of the filtration membrane and the waste pipe, the waste valve being operably coupled to the controller.

29. The reverse osmosis filtration system of claim 26, further comprising a faucet fluidly coupled downstream of the permeate side of the filtration membrane.

30. The reverse osmosis filtration system of claim 26, further comprising a dilution reservoir fluidly coupled downstream of the permeate side of the filtration membrane.

31. The reverse osmosis filtration system of claim 30, wherein: The dilution reservoir includes a volatile organic compound filter.

32. The reverse osmosis filtration system of claim 30, wherein: The dilution reservoir is positioned in the circulation loop.

33. The reverse osmosis filtration system of claim 30, further comprising a total dissolved solids sensor fluidly coupled downstream of the permeate side of the filtration membrane and operably coupled to the controller.

34. A reverse osmosis filtration system comprising: Water inlet; a first water inlet valve fluidly coupled downstream of the tap water inlet; a pump fluidly coupled downstream of the first inlet valve; A filtration membrane, the filtration membrane comprising a concentration side and a permeation side; a second water inlet valve, the second water inlet valve comprising an inlet fluidly coupled to the permeate side of the filtration membrane and an outlet fluidly coupled to the pump, the outlet being used to supply water from the second water inlet valve between the first water inlet valve and the pump; wherein the first water inlet valve and the second water inlet valve each comprise an electrically operable valve; a drain pipe fluidly coupled downstream of the concentrating side of the filtration membrane; a controller operably coupled to the first water inlet valve, the pump, and the second water inlet valve; and A dilution reservoir is fluidly coupled downstream of the permeate side of the filtration membrane.

35. The reverse osmosis filtration system of claim 34, further comprising a total dissolved solids sensor fluidly coupled downstream of the permeate side of the filtration membrane and in electrical communication with the controller.

36. The reverse osmosis filtration system of claim 34, further comprising a faucet fluidly coupled downstream of the permeate side of the filtration membrane.

37. The reverse osmosis filtration system of claim 34, further comprising a circulation loop defined by the pump, the filtration membrane, and the second water inlet valve.

38. The reverse osmosis filtration system of claim 37, wherein: The dilution reservoir is positioned in the circulation loop.

39. The reverse osmosis filtration system of claim 34, further comprising a waste valve in fluid communication between the concentrate side of the filtration membrane and the waste pipe, the waste valve being operably coupled to the controller.

40. The reverse osmosis filtration system of claim 34, wherein: The dilution reservoir includes a volatile organic compound filter.

Images