US20220145596A1 - Residential grey water recycling system - Google Patents
Residential grey water recycling system Download PDFInfo
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- US20220145596A1 US20220145596A1 US17/585,127 US202217585127A US2022145596A1 US 20220145596 A1 US20220145596 A1 US 20220145596A1 US 202217585127 A US202217585127 A US 202217585127A US 2022145596 A1 US2022145596 A1 US 2022145596A1
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- water
- permeate
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- membrane
- collection tank
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- 239000010797 grey water Substances 0.000 title claims abstract description 51
- 238000004064 recycling Methods 0.000 title claims description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 110
- 239000012528 membrane Substances 0.000 claims abstract description 95
- 239000012466 permeate Substances 0.000 claims abstract description 72
- 238000000034 method Methods 0.000 claims abstract description 34
- 238000003287 bathing Methods 0.000 claims abstract description 18
- 238000011045 prefiltration Methods 0.000 claims abstract description 11
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 34
- 239000000460 chlorine Substances 0.000 claims description 34
- 229910052801 chlorine Inorganic materials 0.000 claims description 34
- 238000001179 sorption measurement Methods 0.000 claims description 22
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 15
- 238000010926 purge Methods 0.000 claims description 13
- 238000011001 backwashing Methods 0.000 claims description 8
- 238000004140 cleaning Methods 0.000 claims description 8
- 238000004891 communication Methods 0.000 claims description 4
- 238000011068 loading method Methods 0.000 claims description 2
- 238000001914 filtration Methods 0.000 claims 3
- 238000005086 pumping Methods 0.000 claims 1
- 230000002040 relaxant effect Effects 0.000 claims 1
- 238000002791 soaking Methods 0.000 claims 1
- 238000011144 upstream manufacturing Methods 0.000 claims 1
- 238000011010 flushing procedure Methods 0.000 abstract description 8
- 239000007787 solid Substances 0.000 abstract description 5
- 239000002594 sorbent Substances 0.000 abstract description 3
- 239000000463 material Substances 0.000 abstract description 2
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- 239000002699 waste material Substances 0.000 description 11
- 238000005660 chlorination reaction Methods 0.000 description 10
- 238000012546 transfer Methods 0.000 description 7
- 230000004941 influx Effects 0.000 description 6
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- 239000013505 freshwater Substances 0.000 description 2
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- 239000007788 liquid Substances 0.000 description 2
- 238000005374 membrane filtration Methods 0.000 description 2
- 238000001471 micro-filtration Methods 0.000 description 2
- 230000002572 peristaltic effect Effects 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000002453 shampoo Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000004909 Moisturizer Substances 0.000 description 1
- 230000032770 biofilm formation Effects 0.000 description 1
- 239000007844 bleaching agent Substances 0.000 description 1
- DGLFSNZWRYADFC-UHFFFAOYSA-N chembl2334586 Chemical compound C1CCC2=CN=C(N)N=C2C2=C1NC1=CC=C(C#CC(C)(O)C)C=C12 DGLFSNZWRYADFC-UHFFFAOYSA-N 0.000 description 1
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Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03B—INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
- E03B1/00—Methods or layout of installations for water supply
- E03B1/04—Methods or layout of installations for water supply for domestic or like local supply
- E03B1/041—Greywater supply systems
- E03B1/042—Details thereof, e.g. valves or pumps
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
- B01D29/62—Regenerating the filter material in the filter
- B01D29/66—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps
- B01D29/668—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps with valves, e.g. rotating valves for coaxially placed filtering elements
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
- B01D35/14—Safety devices specially adapted for filtration; Devices for indicating clogging
- B01D35/143—Filter condition indicators
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
- B01D35/14—Safety devices specially adapted for filtration; Devices for indicating clogging
- B01D35/147—Bypass or safety valves
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/008—Control or steering systems not provided for elsewhere in subclass C02F
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/28—Treatment of water, waste water, or sewage by sorption
- C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/68—Treatment of water, waste water, or sewage by addition of specified substances, e.g. trace elements, for ameliorating potable water
- C02F1/685—Devices for dosing the additives
- C02F1/686—Devices for dosing liquid additives
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/76—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
-
- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03B—INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
- E03B1/00—Methods or layout of installations for water supply
- E03B1/04—Methods or layout of installations for water supply for domestic or like local supply
- E03B1/041—Greywater supply systems
-
- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03D—WATER-CLOSETS OR URINALS WITH FLUSHING DEVICES; FLUSHING VALVES THEREFOR
- E03D5/00—Special constructions of flushing devices, e.g. closed flushing system
- E03D5/003—Grey water flushing systems
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/002—Grey water, e.g. from clothes washers, showers or dishwashers
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/03—Pressure
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/40—Liquid flow rate
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/42—Liquid level
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/16—Regeneration of sorbents, filters
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- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03B—INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
- E03B1/00—Methods or layout of installations for water supply
- E03B1/04—Methods or layout of installations for water supply for domestic or like local supply
- E03B1/041—Greywater supply systems
- E03B2001/045—Greywater supply systems using household water
-
- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03C—DOMESTIC PLUMBING INSTALLATIONS FOR FRESH WATER OR WASTE WATER; SINKS
- E03C1/00—Domestic plumbing installations for fresh water or waste water; Sinks
- E03C1/12—Plumbing installations for waste water; Basins or fountains connected thereto; Sinks
- E03C1/26—Object-catching inserts or similar devices for waste pipes or outlets
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/146—Water conservation; Efficient water supply; Efficient water use using grey water
- Y02A20/148—Water conservation; Efficient water supply; Efficient water use using grey water using household water from wash basins or showers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/30—Relating to industrial water supply, e.g. used for cooling
Definitions
- This specification relates to grey water recycling.
- U.S. Pat. No. 8,377,291 describes a water recycling system that can be used for reclaiming and recycling grey water to provide water for landscaping or sanitary facilities such as a toilet.
- the water recycling system includes a tank, an influx pipe with a filter screen, and a pump.
- the filter screen covers an opening in the bottom of the influx pipe.
- the part of the influx pipe containing the filter screen is sloped.
- At least some influent water passing through the influx pipe falls through the filter screen to be collected in the tank. Any excess influent water continues past the filter screen and flows through the influx pipe to an external sanitary drain.
- filtered water is drawn from the tank for use, a portion of it is sprayed against the bottom of the screen to force material off the filter screen and into the influx pipe.
- NSF/ANSI Standard 350 establishes effluent quality criteria for, among other things, onsite residential (single residence, up to 1,500 gallons (5700 L) per day) grey water treatment systems used to provide non-potable (i.e. toilet flushing) water.
- the influent test water has a TSS of 80-160 mg/L and CBOD 5 of 130-180 mg/L, among other parameters.
- the effluent requirements include TSS of 10 mg/L or less and CBOD 5 of 10 mg/L or less.
- the required BOD reduction is a difficult challenge, in part because the synthetic challenge water used for the test includes organics from shampoo, hair conditioner and soap as well as suspended solids and a small amount of residential wastewater.
- This specification describes a grey water collection and recycling system and process.
- the system and process are useful, for example, in collecting grey water from baths or showers or both (bathing water) for re-use in toilet flushing in a single-family residence.
- the following paragraphs describe various features of the system and process.
- a claimed invention may involve only a subset of the features in this summary, or a subset of features in this summary combined with one or more features in the detailed description to follow.
- a household In a typical day, a household generates an excess of bathing water in the morning but uses a similar volume of water for toilet flushing throughout the day.
- the system described herein has two holding tanks to, at least in part, separate in time the collection of bathing water from the provision of toilet flushing water.
- This allows a relatively small membrane filtration unit to operate at low flux while still operating in a cycle of about 24 hours (i.e. up to 27 hours) or less.
- the membrane unit may process grey water at a rate of 10-80 L/hr.
- the total volume of both tanks may be 500 L or less, preferably 400 L or less.
- the entire system can be provided in an integrated appliance sized package, preferably a packaged unit that is no more than two feet (610 mm) wide and no more than six feet (1830 mm) high.
- an integrated appliance sized package preferably a packaged unit that is no more than two feet (610 mm) wide and no more than six feet (1830 mm) high.
- One exemplary system tested met NSF 350 standards for suspended solids and BOD removal.
- influent bathing water is collected, optionally pre-filtered, and stored in a collection tank. Collected influent water is filtered through a membrane unit.
- the membrane filtration is not instantaneous, but the typical daily volume of bathing water generated in a single-family residence (for example 240 L or more, optionally 325 L, or more) is filtered through the membrane unit in about 24 hours (i.e. up to 27 hours) or less.
- the membrane permeate is stored in a permeate tank for delivery on demand for toilet flushing.
- permeate is also treated with a sorbent and disinfected, i.e. oxidized.
- a system described in this specification has an optional prefilter, a greywater collection tank, a microfiltration or ultrafiltration membrane, a sorbent media column, a permeate tank, a chemical dosing system and a control system.
- the prefilter has an automated backwash cycle.
- the membrane is located in the bottom of the collection tank, which may have a reduced cross section in an area surrounding the membrane unit.
- the chemical dosing system may communicate with the permeate tank or the collection tank or both.
- FIG. 1 is a schematic overview of a grey water recycling system in a house.
- FIG. 2 is a schematic drawing showing an example of a grey water recycling system.
- FIGS. 3A, 3B and 3C are front, side and isometric views of a membrane unit of the grey water recycling system of FIG. 2 .
- FIG. 1 shows a house 10 with a grey water recycling system 12 .
- Grey water collected from a bathtub or shower 20 flows down grey water drain 22 to the grey water recycling system 12 .
- the grey water recycling system 12 delivers treated water under pressure to a toilet 24 through a pressurized supply line 28 .
- a waste drain line 30 connects the grey water system to a sanitary drain stack 32 .
- Sanitary drain stack 32 is connected to a sewer, septic system or other wastewater treatment system in or outside of the house 10 .
- FIG. 2 shows an example of a grey water recycling system 12 .
- grey water inlet 40 is connected to the grey water drain 22 of the house 10 .
- Treated water outlet 42 is connected to pressurized supply line 28 .
- Waste outlet 44 is connected to waste drain line 30 .
- reclaimed bathing water from showers and baths enters the grey water recycling system 12 through a grey water inlet 40 .
- Influent grey water passes through a pre-filter unit 46 .
- the pre-filter unit 46 has a filter screen 48 , which separates solids such as hair, soap pieces and other debris from the grey water.
- An integrated bypass tank 50 is connected to the grey water inlet and provides a volume in communication with and above the filter screen 48 . If the filter screen 48 begins to clog, the bypass tank 50 will temporarily retain a volume of grey water. The bypass tank 50 thereby acts as a buffer to allow more time for the incoming grey water to pass through the filter screen 48 .
- a water proximity sensor 50 sends a signal indicating that influent grey water is near the top of the bypass tank 50 .
- the controller implements a filter screen 48 cleaning process.
- the controller is not shown in FIG. 2 to simplify the figure. However, the controller is connected to all of the sensors and controlled devices (i.e. pumps and valves) of the grey water recycling system 12 as well as to an operator interface.
- a flapper valve 54 is open. This allows incoming grey water to flow through the filter screen 48 and flow out of a pre-filtered outlet 56 of the pre-filter unit 46 to a grey water collection tank 60 .
- the controller waits for a predetermined period of time, for example 5 or 10 minutes, and then opens a backwash valve 58 , (i.e. a solenoid valve).
- Backwash valve 58 is connected to the outlet of a main pump 62 .
- Main pump 62 draws treated water from a permeate tank 64 .
- Main pump 62 has an integrated pressure sensor on its outlet.
- Main pump 62 turns on whenever the outlet pressure drops below a preselected minimum, for example 30 psi, and turns off whenever outlet pressure exceeds a preselected maximum, for example 50 psi. Opening backwash valve 58 thereby causes a flow of pressurized water in backwash line 66 . The pressurized water impinges against flapper valve 54 and causes flapper valve 54 to cover the pre-filtered outlet 56 . Water then flows in a reverse direction through the filter screen 48 and overflows through the by-pass tank 50 to the waste outlet 44 . Solids attached to the filter screen 48 are thereby removed from the pre-filter unit 46 . After a predetermined time, the controller closes the backwash valve 58 to end the cleaning process.
- a preselected minimum for example 30 psi
- a preselected maximum for example 50 psi.
- Opening backwash valve 58 thereby causes a flow of pressurized water in backwash line 66 .
- the pressurized water impinges against flapper valve 54
- a backwash waste connector 66 can be opened during the cleaning process to allow backwash water to flow to the waste outlet 44 without passing through the by-pass tank 50 .
- an air pump for example air pump 82 described below
- the pre-filter unit 46 may be as described in U.S. provisional application 62/302,988 filed on Mar. 3, 2016, entitled Intake Filter for Water Collection System with Pressure Activated Backwash Valve, or a PCT application claiming priority to that application filed on the same date as the present application, both of which are incorporated herein by reference.
- the pre-filtered water is stored temporarily in the collection tank 60 .
- the grey water recycling system 12 may be designed for a typical single-family residence, for example with up to five inhabitants. Although water use varies, one frequent pattern is for bathing to peak in the morning, sometimes with a minor amount of bathing in the evening. Toilet flushing also has a morning peak, but is typically more evenly dispersed throughout the day compared to bathing.
- the permeate tank 64 is sized to hold at least enough treated water for a morning toilet flushing peak.
- the collection tank 60 is sized to hold the water generated during a morning bathing peak.
- This holding volume of the collection tank 60 is provided to reduce stress on a membrane unit 70 by allowing the membrane unit 70 at least a few hours, for example 3-8 hours or more, to process enough water to re-fill the permeate tank 64 . In this way, the membrane unit 70 operates at a lower flux, which reduces fouling.
- the membrane unit 70 may have, for example, ultrafiltration or microfiltration membranes.
- the membrane unit may be located in its own tank or immersed in the collection tank 60 , preferably on or near the bottom of the collection tank 60 .
- the collection tank 60 shown is shaped with a reduced horizontal cross sectional area around the membrane unit 70 . This reduces a minimum holding volume required to ensure that the membranes are submerged in water at most times, or at least while permeating an otherwise frequently enough to avoid drying the membranes out.
- FIGS. 3A, 3B and 3C show an example of a membrane unit 70 .
- a membrane unit 70 In this example, several flat sheet membranes 72 are oriented vertically in a membrane housing 74 .
- Permeate collectors 76 separate the individual membranes 72 , connect them to the membrane housing 74 , and provide ports in communication with the inside of the membranes 72 for permeate removal.
- Aerators 78 are attached to the membrane housing 74 below the membranes 72 for use in cleaning the membranes 72 .
- the membranes may be made of PVDF for chlorine resistance.
- filtered water (permeate) is drawn through the membrane unit 70 by suction from a membrane pump 80 , for example a peristaltic pump. Flux through the membranes may be in the range of 1-5 gfd (1.7-8.5 L/m 2 /hour).
- the membrane unit 70 can be cleaned physically cleaned periodically by one or more of relaxation, backwashing and bubble scouring. Preferably, relaxation or backwashing and bubble scouring are conducted simultaneously or at least overlapping in time, or with the bubble scouring directly follows backwashing. To provide relaxation, the membrane pump 80 is stopped. To provide backwashing, the membrane pump 80 can be reversed.
- backwashing can be provided by opening a valve, for example a solenoid valve, in a conduit connecting the outlet of the main pump 62 to the outlet of the membrane unit 70 , which backwashes membrane unit 70 with fully treated water.
- Backwashing may be provided, for example, for 5-120 seconds every 15 to 240 minutes.
- the air pump 82 is turned on to deliver air to the aerators 78 . Bubbles from the aerators 78 circulate grey water through the membrane unit 70 and scour the membranes 72 . The bubbles may also break up a concentration polarization layer on the membranes 72 .
- a pressure sensor 84 at the bottom of collection tank 60 allows the controller to calculate the volume of water in the collection tank 60 .
- the pressure sensor 84 also detects the addition of any new incoming water.
- a typical shower produces about 65 L of water. In a typical single-family residence, there are often three or more showers in a morning.
- the collection tank 60 is sized to hold at least a significant portion of morning shower water for processing later. For example, the collection tank 60 may have a volume of 150 L or more.
- a purge pump 86 is installed at the bottom of the collection tank 60 . As permeate is removed from the collection tank 60 , water in the collection tank becomes concentrated. The collection tank 60 is purged from time to time to avoid over-concentrating the waster in the collection tank 60 . The controller may determine that over-concentration has occurred, or is likely to occur, based on the cumulative amount of grey water collected since the last purge. When a new purge is indicated, the controller waits for a new input of grey water to be detected entering the collection tank 60 , as indicated by an increase in pressure (and therefore the tank water level) detected by the pressure sensor 84 . The controller then causes the purge pump 86 to pump water from the collection tank 60 to the waste outlet 44 .
- the purge pump 86 may remove a predetermined volume of water or reduce the pressure (water level) in the collection tank to a predetermined amount. Purging water from the collection tank 60 prevents operation of the membrane unit 70 in overly concentrated greywater and thereby reduces fouling.
- the controller turns on the purge pump 60 and empties the collection tank 60 . Then, the transfer solenoid 90 opens to add the minimum volume of water required to submerge the membrane unit 70 within the collection tank 60 , for example 20 L.
- the controller opens a collection tank chlorination valve 90 (i.e. a solenoid valve). Pressurized water delivered from the main pump 62 flows through a collection tank venturi 92 . Reduced pressure in the collection tank venturi 92 draws chlorine (i.e. liquid laundry bleach) from a chlorine tank 94 . The chlorine tank 94 is located below the collection tank venturi 92 . The chlorine mixes with the flowing water and chlorine is transferred from the chlorine tank 94 to the collection tank 60 . Alternatively, a dedicated chlorine pump can transfer chlorine from chlorine tank 94 to the collection tank 60 directly or indirectly.
- a collection tank chlorination valve 90 i.e. a solenoid valve
- chlorine can first be pumped from chlorine tank 94 and through a T-connection that is located in a line downstream of main pump 62 , optionally replacing collection tank venturi 92 . Following that step, the chlorination valve 90 is opened, which causes pressurized water from the main pump 62 to carry chlorine that was pumped through the T-connection to the collection tank 60 . Adding chlorine to the collection tank 60 reduces the risk of biofilm formation in the collection tank 60 and on the surfaces of the membranes 72 .
- the collection tank 60 is hyper-chlorinated to clean the membrane unit 70 .
- a hyper-chlorination cycle is preferably started when the water level in the collection tank 60 is low, for example than 40 L or less.
- the controller stops the permeate pump 80 and turns on the purge pump 86 to reduce the volume of water in the collection tank 60 to the minimum required to submerge the membrane unit 70 , for example 20 L.
- the controller then transfers sufficient chlorine to the collection tank 60 (using any method described above) to bring the chlorine concentration in the collection tank to 200 ppm or more, for example 300 ppm.
- the membrane unit 70 is soaked in the concentrated chlorine solution.
- the membrane pump 80 is then activated to draw chlorinated water through the membrane unit 70 .
- Permeate produced during this time is directed to the waste outlet 44 by opening a waste permeate valve 96 (i.e. a solenoid valve).
- a waste permeate valve 96 i.e. a solenoid valve.
- chlorine is transferred to the collection tank 60 and backwashed through the membrane unit 70 simultaneously, or partially simultaneously or sequentially.
- chlorine is injected into a line or manifold downstream of the main pump 62 .
- opening a valve in a conduit connecting the outlet of the main pump 62 downstream of the chlorine injection to the outlet of the membrane unit 70 backwashes membrane unit 70 .
- Opening chlorination valve 90 provides an indirect transfer of chlorine to collection tank 60 as described above.
- the purge pump 86 is turned on to empty the collection tank 60 .
- a transfer solenoid 90 is then opened to add enough water to the collection tank 60 to keep the membrane unit 70 submerged.
- Membrane pump 80 is then activated, optionally with the permeate valve 96 open, to flush water through the membrane unit 70 and permeate tubing.
- the permeate valve 96 is then closed if it was open and the grey water system 12 resumes the normal processing of incoming water.
- the permeate valve 96 may be deleted.
- the membrane pump 80 can be re-activated. A small amount of chlorinated water will be pumped into the next stage (adsorption unit 100 discussed below).
- the permeate flows from the permeate pump 80 to an adsorption unit 100 .
- the adsorption unit 100 may have multiple adsorption columns in series.
- the adsorption columns may be U-shaped or otherwise configured to provide more contact time in a compact area.
- the surface loading in an adsorption column is 0.66 m/hr, and the total empty bed contact time is 156 min.
- Dissolved surfactants and other organics are adsorbed into the adsorbing media of the adsorption unit 100 , for example activated carbon.
- a vent with a valve such as a solenoid valve operable by the controller can be used to vent air from the adsorption unit. Air can be vented on a predetermined schedule, for example once every 15 to 120 minutes.
- Treated water is collected in the permeate tank 64 after passing through the adsorption unit 100 .
- the main pump 62 senses reduced pressure at its outlet and turns on to send water from permeate tank 64 to the toilet 24 .
- a second pressure sensor 102 reads the water level in the permeate tank 64 .
- the permeate pump 80 turns on to deliver more water to the permeate tank 64 whenever the permeate tank 64 is below full capacity the water level in the collection tank 60 is above the membrane unit 70 .
- a permeation tank chlorination valve 106 (i.e. a solenoid valve) is opened periodically, for example once every 1-4 hours. This causes main pump 62 to circulate water from permeate tank 64 , through a permeate tank venturi 104 , and back to permeate tank 64 . Water flowing in permeate tank venturi 104 draws chlorine from chlorine tank 94 . Alternatively, a chlorine pump can be used to pump chorine from chlorine tank 94 into permeate tank 64 directly, or indirectly through a T-fitting replacing permeate tank 104 followed by opening permeation tank chlorination valve 106 . Chlorine is thereby transferred from chlorine tank 94 to permeate tank 64 to disinfect the water in the permeate tank 64 . The amount of chlorine added to the permeate tank 64 is determined by the controller considering, for example, the volume of new and stagnant water in the permeate tank 64 .
- a typical toilet uses 6-13 L per flush.
- the permeate tank 64 is preferably sized to hold enough water for a morning peak, for example 4 or more flushes.
- the permeate tank 64 may have a volume of 25 L.
- a larger volume for example 50 L or more, is preferable to reduce the chance of emptying the permeate tank 64 .
- permeate tank volume in excess of that required for a morning peak for example 80 L or more, allows the membrane unit 70 to operate for a longer period of time overnight, which in turn reduces the required flux or membrane area.
- a make up water valve 110 (i.e. a solenoid valve) opens.
- the make up water valve 110 is connected to a fresh water supply (not shown) for example a supply of municipal drinking water to the house 10 .
- the make up water valve 110 is kept open until enough fresh water is added to bring the water level in the permeate tank back to a predetermined amount, for example 25% of the permeate tank 64 volume or 15 L.
- the transfer valve 90 may open from time to time, for example to add water to submerge the membrane unit 70 after the collection tank 60 is purged after a membrane cleaning (hyper-chlorination) cycle. In some cases, this may cause the make up valve 110 to open and some make up water may flow into the collection tank 60 .
- a control system includes a controller (not shown), pressure sensors 84 , 102 in the permeate and collection tanks, optionally one or more leak detection sensors, a plurality of solenoid valves such as 106 , 58 , 90 , 110 , and optionally 96 that can be opened/closed by the controller and pumps (main pump 62 , membrane pump 80 , purge pump 86 , air pump 82 and optionally a chlorine pump) that can be turned on and off by the controller.
- the controller is programmed to perform various calculations. For example, the controller can calculate the volume of water in each tank 60 , 64 .
- the controller activates and ends chlorination, purging, and hyperchlorination (membrane cleaning) processes, optionally considering the volume of water in a tank 60 , 64 and time passed from the previous cycle.
- the controller can detect clogging of the pre-filter and activate and end a process to clean the pre-filter.
- the controller can also detect failures in the system (for example failures of a valve or a pump) and inform the homeowner to seek service.
- the effectiveness of a prototype grey water recycling system 12 as shown in FIG. 2 in meeting NSF 350 requirements was evaluated.
- the prototype included a submerged ultrafiltration membrane and a carbon adsorption column.
- the results suggested that NSF 350 requirements for CBOD5, TSS and turbidity were met using a combination of ultrafiltration and activated carbon adsorption.
- Synthetic NSF350 challenge water was prepared as per the requirements of NSF 350 (ANSI/NSF 2014). Table 1 shows the ingredients of the challenge water. This challenge water is suitable for testing systems treating bathing water only.
- the challenge water was added to the collection tank.
- the treatment process included two steps: (1) membrane ultra-filtration and (2) carbon adsorption.
- the membrane unit included 10 flat sheet membranes with a combined surface area of 13 ft 2 (1.2 m 2 ).
- the sheets were made of PVDF membrane coated on a non-woven substrate.
- the membranes had a molecular weight cut-off (MWCO) of 75 kDa.
- the membrane unit was operated at a flux of 3 gfd (5 L/m 2 /hour) and was immersed in the collection tank.
- a peristaltic pump (MasterFlex L/S, Cole Parmer) draws permeate through the membrane unit.
- the membrane permeate was passed through a 2-inch (51 mm) adsorption (activated carbon) column with an empty bed contact time of 13.5 min.
- the granular activated carbon was HydroDarco 3000 (Cabot Carbon) with a mesh size of 8 ⁇ 30 (falls through as screen with openings of US screen size 8 (2.4 mm) but remains on a screen with openings of US screen size 30 (0.6 mm)).
- Raw water samples were collected immediately after mixing the NSF350 challenge water and kept refrigerated before transporting to an analytical lab.
- Membrane permeate and adsorption column effluent was collected in pre-labeled sampling bottles, and instantly refrigerated. Triplicate samples were taken from the membrane permeate and the adsorption column effluent.
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Abstract
Description
- This application is a continuation of U.S. application Ser. No. 16/078,246, filed Aug. 21, 2018, which is a National Stage Entry of International Application No. PCT/CA2017/050282, filed Mar. 2, 2017, which claims priority from U.S.
provisional patent application 62/302,988 filed on Mar. 3, 2016 and U.S.provisional patent application 62/305,625 filed on Mar. 9, 2016. U.S. application Ser. No. 16/078,246, International Application No. PCT/CA2017/050282, U.S.provisional patent application 62/302,988 and U.S.provisional patent application 62/305,625 are incorporated herein by reference. - This specification relates to grey water recycling.
- U.S. Pat. No. 8,377,291 describes a water recycling system that can be used for reclaiming and recycling grey water to provide water for landscaping or sanitary facilities such as a toilet. The water recycling system includes a tank, an influx pipe with a filter screen, and a pump. The filter screen covers an opening in the bottom of the influx pipe. The part of the influx pipe containing the filter screen is sloped. At least some influent water passing through the influx pipe falls through the filter screen to be collected in the tank. Any excess influent water continues past the filter screen and flows through the influx pipe to an external sanitary drain. When filtered water is drawn from the tank for use, a portion of it is sprayed against the bottom of the screen to force material off the filter screen and into the influx pipe.
- NSF/ANSI Standard 350 establishes effluent quality criteria for, among other things, onsite residential (single residence, up to 1,500 gallons (5700 L) per day) grey water treatment systems used to provide non-potable (i.e. toilet flushing) water. The influent test water has a TSS of 80-160 mg/L and CBOD5 of 130-180 mg/L, among other parameters. The effluent requirements include TSS of 10 mg/L or less and CBOD5 of 10 mg/L or less. The required BOD reduction is a difficult challenge, in part because the synthetic challenge water used for the test includes organics from shampoo, hair conditioner and soap as well as suspended solids and a small amount of residential wastewater.
- This specification describes a grey water collection and recycling system and process. The system and process are useful, for example, in collecting grey water from baths or showers or both (bathing water) for re-use in toilet flushing in a single-family residence. The following paragraphs describe various features of the system and process. However, a claimed invention may involve only a subset of the features in this summary, or a subset of features in this summary combined with one or more features in the detailed description to follow.
- In a typical day, a household generates an excess of bathing water in the morning but uses a similar volume of water for toilet flushing throughout the day. The system described herein has two holding tanks to, at least in part, separate in time the collection of bathing water from the provision of toilet flushing water. This allows a relatively small membrane filtration unit to operate at low flux while still operating in a cycle of about 24 hours (i.e. up to 27 hours) or less. For example, the membrane unit may process grey water at a rate of 10-80 L/hr. However, the total volume of both tanks may be 500 L or less, preferably 400 L or less. The entire system can be provided in an integrated appliance sized package, preferably a packaged unit that is no more than two feet (610 mm) wide and no more than six feet (1830 mm) high. One exemplary system tested met NSF 350 standards for suspended solids and BOD removal.
- In a process, influent bathing water is collected, optionally pre-filtered, and stored in a collection tank. Collected influent water is filtered through a membrane unit. The membrane filtration is not instantaneous, but the typical daily volume of bathing water generated in a single-family residence (for example 240 L or more, optionally 325 L, or more) is filtered through the membrane unit in about 24 hours (i.e. up to 27 hours) or less. The membrane permeate is stored in a permeate tank for delivery on demand for toilet flushing. Optionally, permeate is also treated with a sorbent and disinfected, i.e. oxidized.
- A system described in this specification has an optional prefilter, a greywater collection tank, a microfiltration or ultrafiltration membrane, a sorbent media column, a permeate tank, a chemical dosing system and a control system. Optionally, the prefilter has an automated backwash cycle. Optionally, the membrane is located in the bottom of the collection tank, which may have a reduced cross section in an area surrounding the membrane unit. Optionally, the chemical dosing system may communicate with the permeate tank or the collection tank or both.
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FIG. 1 is a schematic overview of a grey water recycling system in a house. -
FIG. 2 is a schematic drawing showing an example of a grey water recycling system. -
FIGS. 3A, 3B and 3C are front, side and isometric views of a membrane unit of the grey water recycling system ofFIG. 2 . -
FIG. 1 shows ahouse 10 with a greywater recycling system 12. Grey water collected from a bathtub orshower 20 flows downgrey water drain 22 to the greywater recycling system 12. The greywater recycling system 12 delivers treated water under pressure to atoilet 24 through a pressurizedsupply line 28. Awaste drain line 30 connects the grey water system to asanitary drain stack 32.Sanitary drain stack 32 is connected to a sewer, septic system or other wastewater treatment system in or outside of thehouse 10. -
FIG. 2 shows an example of a greywater recycling system 12. When installed, grey water inlet 40 is connected to thegrey water drain 22 of thehouse 10. Treatedwater outlet 42 is connected to pressurizedsupply line 28. Waste outlet 44 is connected towaste drain line 30. - As mentioned above, reclaimed bathing water from showers and baths enters the grey
water recycling system 12 through a grey water inlet 40. Influent grey water passes through apre-filter unit 46. Thepre-filter unit 46 has afilter screen 48, which separates solids such as hair, soap pieces and other debris from the grey water. An integratedbypass tank 50 is connected to the grey water inlet and provides a volume in communication with and above thefilter screen 48. If thefilter screen 48 begins to clog, thebypass tank 50 will temporarily retain a volume of grey water. Thebypass tank 50 thereby acts as a buffer to allow more time for the incoming grey water to pass through thefilter screen 48. If thefilter screen 48 becomes significantly clogged, grey water rises up to the top of thebypass tank 50 and may overflow to the waste outlet 44. As, or shortly before, the grey water overflows to the waste outlet 44, awater proximity sensor 50 sends a signal indicating that influent grey water is near the top of thebypass tank 50. After receiving the signal, the controller implements afilter screen 48 cleaning process. The controller is not shown inFIG. 2 to simplify the figure. However, the controller is connected to all of the sensors and controlled devices (i.e. pumps and valves) of the greywater recycling system 12 as well as to an operator interface. - Under normal operation, a flapper valve 54 is open. This allows incoming grey water to flow through the
filter screen 48 and flow out of apre-filtered outlet 56 of thepre-filter unit 46 to a greywater collection tank 60. When water is detected at thewater proximity sensor 50, the controller waits for a predetermined period of time, for example 5 or 10 minutes, and then opens abackwash valve 58, (i.e. a solenoid valve).Backwash valve 58 is connected to the outlet of amain pump 62.Main pump 62 draws treated water from apermeate tank 64.Main pump 62 has an integrated pressure sensor on its outlet.Main pump 62 turns on whenever the outlet pressure drops below a preselected minimum, for example 30 psi, and turns off whenever outlet pressure exceeds a preselected maximum, for example 50 psi. Openingbackwash valve 58 thereby causes a flow of pressurized water inbackwash line 66. The pressurized water impinges against flapper valve 54 and causes flapper valve 54 to cover thepre-filtered outlet 56. Water then flows in a reverse direction through thefilter screen 48 and overflows through the by-pass tank 50 to the waste outlet 44. Solids attached to thefilter screen 48 are thereby removed from thepre-filter unit 46. After a predetermined time, the controller closes thebackwash valve 58 to end the cleaning process. Optionally, abackwash waste connector 66 can be opened during the cleaning process to allow backwash water to flow to the waste outlet 44 without passing through the by-pass tank 50. Optionally, an air pump (forexample air pump 82 described below) can be turned on and used to add air to the flow of pressurized water inbackwash line 66. Optionally, thepre-filter unit 46 may be as described in U.S.provisional application 62/302,988 filed on Mar. 3, 2016, entitled Intake Filter for Water Collection System with Pressure Activated Backwash Valve, or a PCT application claiming priority to that application filed on the same date as the present application, both of which are incorporated herein by reference. - The pre-filtered water is stored temporarily in the
collection tank 60. The greywater recycling system 12 may be designed for a typical single-family residence, for example with up to five inhabitants. Although water use varies, one frequent pattern is for bathing to peak in the morning, sometimes with a minor amount of bathing in the evening. Toilet flushing also has a morning peak, but is typically more evenly dispersed throughout the day compared to bathing. Thepermeate tank 64 is sized to hold at least enough treated water for a morning toilet flushing peak. Thecollection tank 60 is sized to hold the water generated during a morning bathing peak. This holding volume of thecollection tank 60 is provided to reduce stress on amembrane unit 70 by allowing themembrane unit 70 at least a few hours, for example 3-8 hours or more, to process enough water to re-fill thepermeate tank 64. In this way, themembrane unit 70 operates at a lower flux, which reduces fouling. - The
membrane unit 70 may have, for example, ultrafiltration or microfiltration membranes. The membrane unit may be located in its own tank or immersed in thecollection tank 60, preferably on or near the bottom of thecollection tank 60. Thecollection tank 60 shown is shaped with a reduced horizontal cross sectional area around themembrane unit 70. This reduces a minimum holding volume required to ensure that the membranes are submerged in water at most times, or at least while permeating an otherwise frequently enough to avoid drying the membranes out. -
FIGS. 3A, 3B and 3C show an example of amembrane unit 70. In this example, severalflat sheet membranes 72 are oriented vertically in amembrane housing 74.Permeate collectors 76 separate theindividual membranes 72, connect them to themembrane housing 74, and provide ports in communication with the inside of themembranes 72 for permeate removal. Aerators 78 are attached to themembrane housing 74 below themembranes 72 for use in cleaning themembranes 72. Optionally, the membranes may be made of PVDF for chlorine resistance. - Referring back to
FIG. 2 , filtered water (permeate) is drawn through themembrane unit 70 by suction from amembrane pump 80, for example a peristaltic pump. Flux through the membranes may be in the range of 1-5 gfd (1.7-8.5 L/m2/hour). Themembrane unit 70 can be cleaned physically cleaned periodically by one or more of relaxation, backwashing and bubble scouring. Preferably, relaxation or backwashing and bubble scouring are conducted simultaneously or at least overlapping in time, or with the bubble scouring directly follows backwashing. To provide relaxation, themembrane pump 80 is stopped. To provide backwashing, themembrane pump 80 can be reversed. Alternatively, backwashing can be provided by opening a valve, for example a solenoid valve, in a conduit connecting the outlet of themain pump 62 to the outlet of themembrane unit 70, which backwashesmembrane unit 70 with fully treated water. Backwashing may be provided, for example, for 5-120 seconds every 15 to 240 minutes. To provide bubble scouring, theair pump 82 is turned on to deliver air to theaerators 78. Bubbles from theaerators 78 circulate grey water through themembrane unit 70 and scour themembranes 72. The bubbles may also break up a concentration polarization layer on themembranes 72. - A
pressure sensor 84 at the bottom ofcollection tank 60 allows the controller to calculate the volume of water in thecollection tank 60. Thepressure sensor 84 also detects the addition of any new incoming water. A typical shower produces about 65 L of water. In a typical single-family residence, there are often three or more showers in a morning. Thecollection tank 60 is sized to hold at least a significant portion of morning shower water for processing later. For example, thecollection tank 60 may have a volume of 150 L or more. - A
purge pump 86 is installed at the bottom of thecollection tank 60. As permeate is removed from thecollection tank 60, water in the collection tank becomes concentrated. Thecollection tank 60 is purged from time to time to avoid over-concentrating the waster in thecollection tank 60. The controller may determine that over-concentration has occurred, or is likely to occur, based on the cumulative amount of grey water collected since the last purge. When a new purge is indicated, the controller waits for a new input of grey water to be detected entering thecollection tank 60, as indicated by an increase in pressure (and therefore the tank water level) detected by thepressure sensor 84. The controller then causes thepurge pump 86 to pump water from thecollection tank 60 to the waste outlet 44. Thepurge pump 86 may remove a predetermined volume of water or reduce the pressure (water level) in the collection tank to a predetermined amount. Purging water from thecollection tank 60 prevents operation of themembrane unit 70 in overly concentrated greywater and thereby reduces fouling. - If no new grey water has entered the
collection tank 60 for more than 48 hours, the controller turns on thepurge pump 60 and empties thecollection tank 60. Then, thetransfer solenoid 90 opens to add the minimum volume of water required to submerge themembrane unit 70 within thecollection tank 60, for example 20 L. - When new water is entering the
collection tank 60, or water has remained stagnant in thecollection tank 60 for more than 6 hours, the controller opens a collection tank chlorination valve 90 (i.e. a solenoid valve). Pressurized water delivered from themain pump 62 flows through acollection tank venturi 92. Reduced pressure in thecollection tank venturi 92 draws chlorine (i.e. liquid laundry bleach) from achlorine tank 94. Thechlorine tank 94 is located below thecollection tank venturi 92. The chlorine mixes with the flowing water and chlorine is transferred from thechlorine tank 94 to thecollection tank 60. Alternatively, a dedicated chlorine pump can transfer chlorine fromchlorine tank 94 to thecollection tank 60 directly or indirectly. To provide an indirect transfer, chlorine can first be pumped fromchlorine tank 94 and through a T-connection that is located in a line downstream ofmain pump 62, optionally replacingcollection tank venturi 92. Following that step, thechlorination valve 90 is opened, which causes pressurized water from themain pump 62 to carry chlorine that was pumped through the T-connection to thecollection tank 60. Adding chlorine to thecollection tank 60 reduces the risk of biofilm formation in thecollection tank 60 and on the surfaces of themembranes 72. - Periodically, for example once every 4 to 8 days, the
collection tank 60 is hyper-chlorinated to clean themembrane unit 70. A hyper-chlorination cycle is preferably started when the water level in thecollection tank 60 is low, for example than 40 L or less. The controller stops thepermeate pump 80 and turns on thepurge pump 86 to reduce the volume of water in thecollection tank 60 to the minimum required to submerge themembrane unit 70, for example 20 L. The controller then transfers sufficient chlorine to the collection tank 60 (using any method described above) to bring the chlorine concentration in the collection tank to 200 ppm or more, for example 300 ppm. Themembrane unit 70 is soaked in the concentrated chlorine solution. Themembrane pump 80 is then activated to draw chlorinated water through themembrane unit 70. Permeate produced during this time is directed to the waste outlet 44 by opening a waste permeate valve 96 (i.e. a solenoid valve). In an alternative method of hyper-chlorination, chlorine is transferred to thecollection tank 60 and backwashed through themembrane unit 70 simultaneously, or partially simultaneously or sequentially. First, chlorine is injected into a line or manifold downstream of themain pump 62. Thereafter, opening a valve in a conduit connecting the outlet of themain pump 62 downstream of the chlorine injection to the outlet of themembrane unit 70backwashes membrane unit 70. Openingchlorination valve 90 provides an indirect transfer of chlorine tocollection tank 60 as described above. After cleaning themembrane unit 70 with the concentrated chlorine solution, thepurge pump 86 is turned on to empty thecollection tank 60. Atransfer solenoid 90 is then opened to add enough water to thecollection tank 60 to keep themembrane unit 70 submerged.Membrane pump 80 is then activated, optionally with thepermeate valve 96 open, to flush water through themembrane unit 70 and permeate tubing. Thepermeate valve 96 is then closed if it was open and thegrey water system 12 resumes the normal processing of incoming water. Particularly in the hyper-chlorination method in which themembrane unit 70 is backwashed rather than permeating, thepermeate valve 96 may be deleted. In this case, after themembrane unit 70 is soaked in chlorine solution for the required period of time and thecollection tank 60 is purged, themembrane pump 80 can be re-activated. A small amount of chlorinated water will be pumped into the next stage (adsorption unit 100 discussed below). - The permeate flows from the
permeate pump 80 to anadsorption unit 100. Optionally, theadsorption unit 100 may have multiple adsorption columns in series. The adsorption columns may be U-shaped or otherwise configured to provide more contact time in a compact area. In an example, the surface loading in an adsorption column is 0.66 m/hr, and the total empty bed contact time is 156 min. Dissolved surfactants and other organics are adsorbed into the adsorbing media of theadsorption unit 100, for example activated carbon. Optionally, or if necessary, a vent with a valve such as a solenoid valve operable by the controller can be used to vent air from the adsorption unit. Air can be vented on a predetermined schedule, for example once every 15 to 120 minutes. - Treated water is collected in the
permeate tank 64 after passing through theadsorption unit 100. When there is demand for water after atoilet 24 flushes, themain pump 62 senses reduced pressure at its outlet and turns on to send water frompermeate tank 64 to thetoilet 24. Asecond pressure sensor 102 reads the water level in thepermeate tank 64. Thepermeate pump 80 turns on to deliver more water to thepermeate tank 64 whenever thepermeate tank 64 is below full capacity the water level in thecollection tank 60 is above themembrane unit 70. - A permeation tank chlorination valve 106 (i.e. a solenoid valve) is opened periodically, for example once every 1-4 hours. This causes
main pump 62 to circulate water frompermeate tank 64, through a permeate tank venturi 104, and back to permeatetank 64. Water flowing in permeate tank venturi 104 draws chlorine fromchlorine tank 94. Alternatively, a chlorine pump can be used to pump chorine fromchlorine tank 94 intopermeate tank 64 directly, or indirectly through a T-fitting replacing permeate tank 104 followed by opening permeationtank chlorination valve 106. Chlorine is thereby transferred fromchlorine tank 94 to permeatetank 64 to disinfect the water in thepermeate tank 64. The amount of chlorine added to thepermeate tank 64 is determined by the controller considering, for example, the volume of new and stagnant water in thepermeate tank 64. - A typical toilet uses 6-13 L per flush. The
permeate tank 64 is preferably sized to hold enough water for a morning peak, for example 4 or more flushes. For example, thepermeate tank 64 may have a volume of 25 L. However, a larger volume, for example 50 L or more, is preferable to reduce the chance of emptying thepermeate tank 64. Further, permeate tank volume in excess of that required for a morning peak, for example 80 L or more, allows themembrane unit 70 to operate for a longer period of time overnight, which in turn reduces the required flux or membrane area. - If the water level in the
permeate tank 64 is less than a predetermined minimum, for example 10% of thepermeate tank 64 volume or 8 L, a make up water valve 110 (i.e. a solenoid valve) opens. The make up water valve 110 is connected to a fresh water supply (not shown) for example a supply of municipal drinking water to thehouse 10. The make up water valve 110 is kept open until enough fresh water is added to bring the water level in the permeate tank back to a predetermined amount, for example 25% of thepermeate tank 64 volume or 15 L. As discussed previously, thetransfer valve 90 may open from time to time, for example to add water to submerge themembrane unit 70 after thecollection tank 60 is purged after a membrane cleaning (hyper-chlorination) cycle. In some cases, this may cause the make up valve 110 to open and some make up water may flow into thecollection tank 60. - In the example shown in
FIG. 2 , a control system includes a controller (not shown),pressure sensors main pump 62,membrane pump 80,purge pump 86,air pump 82 and optionally a chlorine pump) that can be turned on and off by the controller. The controller is programmed to perform various calculations. For example, the controller can calculate the volume of water in eachtank tank - The effectiveness of a prototype grey
water recycling system 12 as shown inFIG. 2 in meeting NSF 350 requirements was evaluated. The prototype included a submerged ultrafiltration membrane and a carbon adsorption column. The results suggested that NSF 350 requirements for CBOD5, TSS and turbidity were met using a combination of ultrafiltration and activated carbon adsorption. - Synthetic NSF350 challenge water was prepared as per the requirements of NSF 350 (ANSI/NSF 2014). Table 1 shows the ingredients of the challenge water. This challenge water is suitable for testing systems treating bathing water only.
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TABLE 1 Ingredients Amount/100 L Body wash with moisturizer 30 g Toothpaste 3 g Deodorant 2 g Shampoo 19 g Conditioner 21 g Lactic acid 3 g Secondary effluent 2 L Bath cleaner 10 g Liquid hand soap 23 g Test dust 10 g - The challenge water was added to the collection tank. The treatment process included two steps: (1) membrane ultra-filtration and (2) carbon adsorption. The membrane unit included 10 flat sheet membranes with a combined surface area of 13 ft2 (1.2 m2). The sheets were made of PVDF membrane coated on a non-woven substrate. The membranes had a molecular weight cut-off (MWCO) of 75 kDa. The membrane unit was operated at a flux of 3 gfd (5 L/m2/hour) and was immersed in the collection tank. A peristaltic pump (MasterFlex L/S, Cole Parmer) draws permeate through the membrane unit. The membrane permeate was passed through a 2-inch (51 mm) adsorption (activated carbon) column with an empty bed contact time of 13.5 min. The granular activated carbon was HydroDarco 3000 (Cabot Carbon) with a mesh size of 8×30 (falls through as screen with openings of US screen size 8 (2.4 mm) but remains on a screen with openings of US screen size 30 (0.6 mm)).
- Raw water samples were collected immediately after mixing the NSF350 challenge water and kept refrigerated before transporting to an analytical lab. Membrane permeate and adsorption column effluent was collected in pre-labeled sampling bottles, and instantly refrigerated. Triplicate samples were taken from the membrane permeate and the adsorption column effluent.
- The water quality results in Table 2 show that combination of ultra-filter (UF) membrane and carbon adsorption can meet NSF 350 requirements. The membrane alone can reduce turbidity and TSS to the required values for NSF 350. In addition, the membrane removes 53% of CBOD5, but this is not enough to reach the standard requirements. The addition of an adsorption column reduces CBOD5 to less than 5 mg/L as well as providing further reduction in turbidity.
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TABLE 2 NSF NSF Chal- De- effluent influent lenge Per- Sorption tection Parameter goal range water meate effluent limit Turbidity (NTU) 5 30-70 71.45 1.65 ≤0.5 0.5 pH 6 to 9 — 7.56 7.68 7.94 NA BOD — 100-180 117 — — 5 CBOD5 (mg/L) 10 — 96 51 ≤5 5 TSS (mg/L) 10 50-100 105 ≤10 ≤10 10
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US17/585,127 US20220145596A1 (en) | 2016-03-03 | 2022-01-26 | Residential grey water recycling system |
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US201816078246A | 2018-08-21 | 2018-08-21 | |
US17/585,127 US20220145596A1 (en) | 2016-03-03 | 2022-01-26 | Residential grey water recycling system |
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US16/078,246 Continuation US20190047878A1 (en) | 2016-03-03 | 2017-03-02 | Residential grey water recycling system |
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US16/078,250 Active US10934691B2 (en) | 2016-03-03 | 2017-03-02 | Intake filter for water collection system with pressure activated backwash valve |
US16/078,246 Pending US20190047878A1 (en) | 2016-03-03 | 2017-03-02 | Residential grey water recycling system |
US17/162,684 Active 2037-09-29 US11879236B2 (en) | 2016-03-03 | 2021-01-29 | Intake filter for water collection system with pressure activated backwash valve |
US17/585,127 Pending US20220145596A1 (en) | 2016-03-03 | 2022-01-26 | Residential grey water recycling system |
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US17/162,684 Active 2037-09-29 US11879236B2 (en) | 2016-03-03 | 2021-01-29 | Intake filter for water collection system with pressure activated backwash valve |
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US10717027B2 (en) * | 2018-08-24 | 2020-07-21 | Zhen-Fa Guan | Modified apparatus for wastewater recycling |
CN111018168A (en) * | 2019-11-21 | 2020-04-17 | 新乡中新化工有限责任公司 | Ash water treatment equipment and process |
CN111519719B (en) * | 2020-04-29 | 2021-06-11 | 杭州震弘环境科技有限公司 | Domestic sewage recycling system for recycling water resources |
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EP3423413B1 (en) | 2023-06-07 |
US11879236B2 (en) | 2024-01-23 |
US20190047878A1 (en) | 2019-02-14 |
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CA3015264A1 (en) | 2017-09-08 |
US20210148095A1 (en) | 2021-05-20 |
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ES2954253T3 (en) | 2023-11-21 |
ES2961889T3 (en) | 2024-03-14 |
CA3015230A1 (en) | 2017-09-08 |
EP3423413A1 (en) | 2019-01-09 |
EP3423418B1 (en) | 2023-08-09 |
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