WO2020104728A1 - A method and apparatus for treatment of saline water - Google Patents

A method and apparatus for treatment of saline water

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Publication number
WO2020104728A1
WO2020104728A1 PCT/FI2019/050832 FI2019050832W WO2020104728A1 WO 2020104728 A1 WO2020104728 A1 WO 2020104728A1 FI 2019050832 W FI2019050832 W FI 2019050832W WO 2020104728 A1 WO2020104728 A1 WO 2020104728A1
Authority
WO
WIPO (PCT)
Prior art keywords
membrane
water
frame structure
blade
module
Prior art date
Application number
PCT/FI2019/050832
Other languages
French (fr)
Inventor
Mika MÄNTTÄRI
Kimmo AROLA
Mari KALLIOINEN
Original Assignee
Lappeenrannan-Lahden Teknillinen Yliopisto Lut
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lappeenrannan-Lahden Teknillinen Yliopisto Lut filed Critical Lappeenrannan-Lahden Teknillinen Yliopisto Lut
Publication of WO2020104728A1 publication Critical patent/WO2020104728A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
    • B01D63/08—Flat membrane modules
    • B01D63/082—Flat membrane modules comprising a stack of flat membranes
    • B01D63/0822—Plate-and-frame devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
    • B01D63/08—Flat membrane modules
    • B01D63/082—Flat membrane modules comprising a stack of flat membranes
    • 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
    • C02F1/004—Processes for the treatment of water whereby the filtration technique is of importance using large scale industrial sized filters
    • 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
    • B01D29/64—Regenerating the filter material in the filter by scrapers, brushes, nozzles, or the like, acting on the cake side of the filtering element
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/15—Filters with filtering elements which move during the filtering operation with rotary plane filtering surfaces
    • B01D33/21—Filters with filtering elements which move during the filtering operation with rotary plane filtering surfaces with hollow filtering discs transversely mounted on a hollow rotary shaft
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/35—Filters with filtering elements which move during the filtering operation with multiple filtering elements characterised by their mutual disposition
    • B01D33/37—Filters with filtering elements which move during the filtering operation with multiple filtering elements characterised by their mutual disposition in parallel connection
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/58—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element
    • B01D33/68—Retarding cake deposition on the filter during the filtration period, e.g. using stirrers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
    • B01D63/16—Rotary, reciprocated or vibrated modules
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
    • B01D65/08—Prevention of membrane fouling or of concentration polarisation
    • 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
    • C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • 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
    • C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2311/00—Details relating to membrane separation process operations and control
    • B01D2311/04—Specific process operations in the feed stream; Feed pretreatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2311/00—Details relating to membrane separation process operations and control
    • B01D2311/25—Recirculation, recycling or bypass, e.g. recirculation of concentrate into the feed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2311/00—Details relating to membrane separation process operations and control
    • B01D2311/25—Recirculation, recycling or bypass, e.g. recirculation of concentrate into the feed
    • B01D2311/252—Recirculation of concentrate
    • B01D2311/2523—Recirculation of concentrate to feed side
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2313/00—Details relating to membrane modules or apparatus
    • B01D2313/12—Specific discharge elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2315/00—Details relating to the membrane module operation
    • B01D2315/02—Rotation or turning
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2321/00—Details relating to membrane cleaning, regeneration, sterilization or to the prevention of fouling
    • B01D2321/20—By influencing the flow
    • B01D2321/2008—By influencing the flow statically
    • B01D2321/2016—Static mixers; Turbulence generators
    • 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
    • C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
    • C02F1/385—Treatment of water, waste water, or sewage by centrifugal separation by centrifuging suspensions
    • 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
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F2001/5218—Crystallization
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/105—Phosphorus compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00—General aspects of water treatment
    • C02F2301/02—Fluid flow conditions
    • C02F2301/024—Turbulent
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00—General aspects of water treatment
    • C02F2301/04—Flow arrangements
    • C02F2301/046—Recirculation with an external loop
    • 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
    • C02F2303/22—Eliminating or preventing deposits, scale removal, scale prevention

Definitions

  • the present invention relates to the field of treatment of water, pro cess water, wastewater, sewage or sludge, and more particularly to a method and apparatus for treatment of saline water.
  • Membrane technologies are used to purify these waters.
  • Traditional membrane modules include tubular membrane modules and plate and frame membrane modules, hollow fibre membrane modules as well as spiral wound membrane modules.
  • the most commonly used membrane modules i.e. spiral wound membrane modules used today enable rather low water recovery level i.e. 50-75%.
  • the crystallization in the bulk solution or on the membrane surface will lead to plugging of the feed channel and fouling of the membrane or plugging of the whole filter.
  • An object of the present invention is thus to provide a method and an apparatus for implementing the method so as to overcome the above problems and to alleviate the above disadvantages.
  • the objects of the invention are achieved by a method for treatment of saline water, which method comprises the steps of:
  • said method also comprises the step of:
  • said at least one blade or disk is posi tioned in relation to said at least one membrane so as to create turbulent forces for lifting crystallized particles from the surface of said at least one membrane and to create centrifugal forces for removing said crystallized particles from the surface of said at least one membrane to the outer periphery of said frame struc ture.
  • the method further comprises the step of:
  • the method further comprises the step of:
  • the method further comprises the step of:
  • the method further comprises the step of:
  • the first stage water purification process is a nanofil tration process or a reverse osmosis process.
  • an apparatus for treatment of saline water which apparatus comprises a membrane module, said membrane module comprising:
  • said membrane module of said apparatus comprises an at least one blade or disk arranged close to a surface of said at least one membrane, wherein said apparatus further comprises a motor arranged to rotate one of said at least one blade or disk or said at least one membrane,
  • said frame structure comprises an output for recovering con centrated stream containing crystallized particles from outer periphery of said frame structure
  • said output for purified water is arranged in the direction of the tangent of the outer periphery of said frame structure or at an acute angle a in relation to the tangent of the outer periphery of said frame structure.
  • said at least one blade or disk is positioned in relation to said at least one membrane so as to create turbulent forces for lifting crystallized particles from the surface of said at least one membrane and to create centrifu gal forces for removing said crystallized particles from the surface of said at least one membrane to the outer periphery of said frame structure.
  • said apparatus further comprises an arrangement for reduc ing the concentrated stream flow velocity outside said membrane module.
  • said apparatus further comprises an arrangement for removing crystallized particles from said concentrated stream.
  • a wastewater output from a first stage water purification pro cess is provided as said input for incoming water.
  • said first stage water purification process is a nanofiltration process or a reverse osmosis process.
  • said at least one blade comprises one blade or two blades.
  • said at least one membrane comprises one membrane or two membranes.
  • said at least one membrane comprises one or more stacks of 2-200 membranes, preferably one or more stacks of 20-50 mem branes.
  • said output for purified water is arranged in the direction of the tangent of the outer periphery of said frame structure.
  • said acute angle a is less than 90 degrees and more than 0 degrees, preferably less than 45 degrees and more than 0 degrees, more pref erably less than 15 degrees and more than 0 degrees.
  • said apparatus is used for saline wastewater treatment or saline process water treatment.
  • Figure 1 shows a block diagram of one embodiment of an arrange ment for treatment of saline water according to the present invention.
  • Figure 2 shows an exploded view of one embodiment of a membrane module according to the present invention.
  • Figure 3 shows a flow diagram of one embodiment of a method for treatment of saline water according to the present invention.
  • Figure 4 shows an exploded view of another embodiment of a mem brane module according to the present invention.
  • Figure 5 shows a partial perspective view of a third embodiment of a membrane module arrangement according to the present invention.
  • Figure 6 shows a block diagram of another embodiment of an ar rangement for treatment of saline water according to the present invention.
  • Figure 7 shows a flow diagram of another embodiment of a method for treatment of saline water according to the present invention.
  • Figure 8 shows a cross-sectional view of a fourth embodiment of a membrane module arrangement according to the present invention.
  • FIG. 1 shows a block diagram of one embodiment of an arrange ment for treatment of saline water according to the present invention.
  • the saline water treatment arrangement according to the present embodiment comprises a high shear rate water purification block 10, said high shear rate water purifica tion block 10 comprising an input for incoming water 1 1 , a membrane module 12 for filtering the incoming water 1 1 , an output for purified water 13, and an output for a concentrated stream 14. From said high shear rate water purification block 10 said concentrated stream 14 is lead to a precipitate removal block 16 for removal of precipitate residue 17. From said precipitate removal block 16 precipitate residue 17 is removed, i.e.
  • the saline water treatment arrangement according to the pre sent embodiment also comprises a motor 15 connected to the membrane mod ule 12 of said high shear rate water purification block 10.
  • the flow velocity of the concentrated stream 14 reduces as concentrated stream 14 exits the membrane module 12. This facilitates the precipitate formation.
  • the apparatus may further comprise an ar rangement for reducing the concentrated stream 14 flow velocity outside said membrane module 12, such as an open chamber design with unlimited stream mass flow in the concentrated stream 14 exiting area at the membrane module 12.
  • FIG. 2 shows an exploded view of one embodiment of a membrane module according to the present invention.
  • the membrane module 20 according to the present embodiment comprises a frame structure 21 , 22, 23.
  • the frame structure 21 , 22, 23 of the membrane module 20 has a lower cover frame 21 , an upper cover frame 22 and a central frame part 23.
  • the membrane module 20 also comprises an input for incoming water, which input is not shown in Figure 2.
  • the membrane module 20 also comprises a membrane 24 for filtering the incoming water. Furthermore, the membrane module 20 comprises an output for purified water 235. In the present embodiment, the output for purified water 235 is arranged to the central frame part 23 of the membrane module 20. In the present embodiment, the output for purified water 235 is arranged at an acute angle a in relation to the outer periph ery frame of the membrane module 20.
  • the membrane module 20 according to the present embodiment also comprises a blade 25 or a disk arranged close to a surface of the membrane 24. Said blade 25 or said disk is positioned in relation to said membrane 24 so as to create turbulent forces for lifting crystallized particles from the surface of said membrane 24.
  • Said blade 25 or said disk is also positioned so as to create cen trifugal forces for removing said crystallized particles from the surface of said membrane 24 to outer periphery of said frame structure 21 , 22.
  • Said blade 25 may be a rectangular blade 25, curved blade, s-shaped blade, perforated blade or any other blade with a suitable shape for creating turbulent and centrifugal forces.
  • the membrane module 20 according to the present invention may also comprise an output for recovering a concentrated stream containing crystallized particles and concentrated dissolved compounds from the outer periphery of said frame structure 21 , 22, which output is not shown in Figure 2.
  • the membrane module 20 of the saline water treatment arrangement also comprises a motor 15 connected to the membrane module 20, said motor 15 being arranged to rotate one of said blade 25, said disk or said membrane 24.
  • the motor 15 is not shown in Figure 2.
  • FIG. 3 shows a flow diagram of one embodiment of a method for treatment of saline water according to the present invention.
  • incoming water 1 1 is first lead 32 to a frame structure 21 , 22, 23 of a membrane module 20 of a saline water treatment apparatus through an incoming water input 1 1 .
  • the incoming water 1 1 is then filtered 33 through a membrane 24 of said membrane module 20.
  • the membrane module 20 according to the present embodiment also com prises a blade 25 or a disk arranged close to a surface of the membrane 24.
  • said blade 25 or said disk is rotated 34.
  • said membrane 24 is rotated 34.
  • said blade 25 or said disk is positioned in re lation to said membrane 24 so as to create turbulent forces for lifting crystallized particles from the surface of said membrane 24 and to create centrifugal forces for removing said crystallized particles from the surface of said membrane 24 to outer periphery of said frame structure 21 , 22.
  • the purified water is outputted 35 from said frame struc ture 21 , 22, 23 of said membrane module 20 through a purified water output 235.
  • a concentrated stream containing crystallized particles is recovered 36 from the outer periphery of said frame structure 21 , 22.
  • the precipitate residue 17 is removed, i.e. crystallized particles are then removed and thereby recovered 36.
  • the centrifugal forces lead the crystallized particles to the outer periphery of said frame struc ture 21 , 22 and they do not precipitate or form scale on the membrane surface.
  • FIG 4 shows an exploded view of another embodiment of a mem brane module according to the present invention.
  • the membrane module 40 according to the present another embodiment comprises a frame structure 21 , 22, 23.
  • the frame structure 21 , 22, 23 of the membrane module 40 has a lower cover frame 21 , an upper cover frame 22 and a central frame part 23.
  • the membrane module 40 also comprises an input for incoming water, which input is not shown in Figure 4.
  • the membrane module 40 also comprises membranes 24, 26 for filtering the incoming water. Further more, the membrane module 40 comprises an output for purified water 235. In the present another embodiment, the output for purified water 235 is arranged to the central frame part 23 of the membrane module 40. In the present embod iment, the output for purified water 235 is arranged at an acute angle a in relation to the outer periphery frame of the membrane module 40.
  • the membrane module 40 according to the present another embodi ment also comprises blades 25, 27 or disks arranged close to a surface of the membranes 24, 26. Said blades 25, 27 or said disks are positioned in relation to said membranes 24, 26 so as to create turbulent forces for lifting crystallized particles from the surface of said membranes 24, 26. Said blades 25, 27 or said disks are also positioned so as to create centrifugal forces for removing said crystallized particles from the surface of said membranes 24, 26 to outer periph ery of said frame structure 21 , 22. Said blades 25, 27 may be rectangular blades 25, 27, curved blades, s-shaped blades, perforated blades or any other blades with a suitable shape for creating turbulent and centrifugal forces.
  • the mem brane module 40 according to the present invention may also comprise an out put for recovering a concentrated stream containing crystallized particles from the outer periphery of said frame structure 21 , 22, which output is not shown in Figure 4.
  • the membrane module 40 of the saline water treatment arrangement also comprises a motor 15 connected to the membrane module 40, said motor 15 being arranged to rotate one of said blades 25, 27 said disks or said membranes 24, 26.
  • the motor 15 is not shown in Figure 4.
  • FIG. 5 shows a partial perspective view of a third embodiment of a membrane module arrangement according to the present invention.
  • the mem brane module arrangement 50 according to the present third embodiment com prises several membrane stacks 51 -58.
  • the membranes of said membrane stacks 51 -58 are arranged as partially overlap ping each other so as to create turbulent forces for lifting crystallized particles from the surface of said membranes of said membrane stacks 51 -58.
  • the mem brane module arrangement 50 according to the present third embodiment may also comprise an at least one blade or disk arranged close to a surface of an at least one membrane. Flowever, said at least one blade or disk of the membrane module arrangement is not shown in Figure 5.
  • the membrane module arrangement 50 of the saline water treatment arrangement also comprises a motor 15 con nected to the membrane module arrangement 50, said motor 15 being arranged to rotate said several membrane stacks 51 -58. Said several membrane stacks 51 -58 are rotated so as to create centrifugal forces for removing said crystallized particles from the surface of said membranes 24, 26 to outer periphery of said frame structure 21 , 22.
  • the motor 15 is not shown in Figure 5.
  • FIG. 6 shows a block diagram of another embodiment of an ar rangement for treatment of saline water according to the present invention.
  • the saline water treatment arrangement according to the present another embodi ment comprises a first stage water purification block 101 and a high shear rate water purification block 10.
  • the first stage water purification block 101 comprises an input for incoming water 102, a first stage output for purified water 1 03, and a first stage output for wastewater 104.
  • the first stage water purification process 101 carried out in said first stage water purification block 101 may e.g. be a nanofiltration process 101 or a reverse osmosis process 101 using e.g. spiral wound modules or other type modules.
  • the high shear rate water purification block 10 comprises an input for incoming water 1 04, a membrane module 12 for filtering the incoming water 1 04, an output for purified water 13, and an output for a concentrated stream 14. From said high shear rate water purification block 10 said concentrated stream 14 is lead to a precipitate removal block 16 for removal of precipitate residue 17. From said precipitate removal block 16 precipitate residue 17 is removed and the clarified solution 18 is recirculated back to the feed of said high shear rate water purification block.
  • the wastewater 104 from the first stage water purification block 101 is forwarded as an incoming water 104 input to the high shear rate water purification block 10.
  • the saline water treatment arrangement also comprises a motor 15 con nected to the membrane module 12 of said high shear rate water purification block 10.
  • the flow velocity of the concentrated stream 14 reduces as concentrated stream 14 exits the membrane module 12. This facilitates the precipitate formation.
  • the apparatus may further comprise an arrangement for reducing the concentrated stream 14 flow velocity outside said membrane module 12, such as an open chamber de sign with unlimited stream mass flow in the concentrated stream 14 exiting area at the membrane module 12.
  • FIG. 7 shows a flow diagram of another embodiment of a method for treatment of saline water according to the present invention.
  • incoming water 1 02 is first lead to first stage water purification 31 in the first stage water purification block 101 .
  • the out putted wastewater 104 is forwarded 32 as an incoming water 104 input to the high shear rate water purification block 10.
  • the first stage water purification pro cess 101 carried out in said first stage water purification block 101 may e.g. be a nanofiltration process 101 or a reverse osmosis process 101 , using e.g. spiral wound modules or other type modules.
  • the incoming water 104 is lead 32 to a frame structure 21 , 22, 23 of a membrane module 20, 40, 50 of a saline water treatment apparatus through an incoming water input 1 04.
  • the incoming water 1 04 is then filtered 33 through an at least one membrane 24, 26 of said membrane module 20.
  • the membrane module 20 according to the pre sent another embodiment also comprises an at least one blade 25, 27 or disk arranged close to a surface of said at least one membrane 24, 26.
  • said at least one blade 25, 27 or disk is ro tated 34.
  • said at least one membrane 24, 26 is rotated 34.
  • said at least one blade 25, 27 or disk is posi tioned in relation to said at least one membrane 24, 26 so as to create turbulent forces for lifting crystallized particles from the surface of said at least one mem brane 24, 26 and to create centrifugal forces for removing said crystallized par ticles from the surface of said at least one membrane 24, 26 to outer periphery of said frame structure 21 , 22.
  • the purified water is outputted 35 from said frame struc ture 21 , 22, 23 of said membrane module 20, 40, 50 through a purified water output 235.
  • a concentrated stream containing crystallized particles is re covered 36 from the outer periphery of said frame structure 21 , 22. From said precipitate concentrated stream the precipitate residue 17 i.e. crystallized parti cles is then removed and thereby recovered 36.
  • the centrifugal forces lead the crystallized particles to the outer periphery of said frame structure 21 , 22 and they do not precipitate or form scale on the mem brane surface.
  • Figure 8 shows a cross-sectional view of a fourth embodiment of a membrane module arrangement according to the present invention.
  • the mem brane module arrangement 60 according to the present fourth embodiment com prises a frame structure, an input for incoming water and an at least one mem brane for filtering the incoming water, which are not shown in Figure 8.
  • the membrane module 60 also comprises an at least one blade 65 an at least one blade arranged close to a surface of an at least one membrane for filtering the incoming water. Furthermore, the membrane module 60 comprises an output for purified water 236.
  • the output for purified water 236 is arranged in the direction of the tangent of the outer periphery frame or at an acute angle a in relation to the tangent of the outer periphery frame of the membrane module 60.
  • the tangent of the outer periphery frame of the membrane module 60 is drawn and indicated as TAN.
  • Said acute angle a of said output for purified water 236 in relation to the tangent of the outer periphery frame of the membrane module 60 is indicated as a.
  • Said acute angle a is less than 90 degrees and more than 0 degrees, 90° > a > 0°.
  • said acute angle a is less than 45 degrees and more than 0 degrees, 45° > a > 0°.
  • said acute angle a is less than 15 degrees and more than 0 degrees, 15° > a > 0°.
  • Said output for purified water 236 may for example have a round shape, a rectangular shape, oval shape or elliptical shape. Said output for puri fied water 236 may also be closable and openable, e.g. for intermittent opera tion. Said output for purified water 236 provides enhanced removal of precipi tates from the filtration module 60.
  • the rotation speed or the at least one blade 65 may also be variable.
  • the membrane module 12, 20, 40, 50 comprises an at least one mem brane 24, 26 for filtering the incoming water 1 1 , 104.
  • At least one membrane 24, 26 may comprise one membrane 24 or two membranes 24, 26. Said at least one membrane 24, 26 may also comprise one or more stacks of 2-200 mem branes 24, 26. Alternatively, said at least one membrane 24, 26 may also com prise one or more stacks of 20-50 membranes 24, 26.
  • the membrane module 12, 20, 40, 50 comprises an at least one blade
  • the saline water treatment apparatus may e.g. be used for saline wastewater treatment or saline process water treatment.
  • the solution according to the present invention presents a process to treat saline water with a special membrane module, which enables concentra tion of the feed solution above saturation point without fear of plugging of the filtration channel or scaling of the membrane.
  • the formation of crystallized particles on the membrane surface is substantially de creased due to the shear forces created by rotating a blade or a disk on the membrane surface or by rotating the membrane.
  • the removal of the salt solu tions and the crystallized particles can be done efficiently in the filter in which turbulence is created by centrifugal forces e.g. rotating a rotor blade or a disk close to membrane surface. In this way an extremely high turbulence can be generated, scaling on the membrane surface can be reduced, and bulk precipi tation is facilitated.
  • the turbulence produced by the rotating blade/disk/mem brane cause solids and foulants to be lifted off the membrane surface.
  • centrifugal forces are created, which throw precip itates out from the membrane surface to the outer periphery of said frame struc ture 21 , 22 and to the concentrate stream containing precipitate residue 17 i.e. crystallized particles.
  • the filter construction according to the present invention preferen tially removes precipitates due to centrifugal forces.
  • the principle is the same as in the centrifuge where more dense solid particles are removed by centrifugal forces.
  • the removal of precipitates from the module can be achieved with very low concentrate flow rate and efficient concentration can be achieved in one stage inside the module.
  • the concentrate having high flow velocity may also be recirculated back to the module in order to en hance water recovery.
  • spiral wound modules only 10-15% of the feed perme ated the membrane in one cycle.
  • the formed precipitates are recirculated back to the module they can cause plugging of the channel in the module. There fore, the water recovery is commonly around 50-75%.
  • High shear rate prevents the formation of crystallized particles on the membrane surface and enables concentration of salts above saturation point, i.e. filtration can be operated at bulk crystallisation conditions. This means that significantly higher water recovery and salt concentration can be achieved than e.g. when spiral wound filtration modules are used.
  • centrifugal forces are not only used to create turbulence and to prevent scaling formation on the membrane surface but also to remove the formed crystals out from the module. Because the turbulence and centrifugal forces are created by rotating a rotor, the pumping velocity can be very low. Therefore, flow velocity outside the module can be almost zero and these conditions favours the precipitation process.
  • the formed precipitates can then be removed e.g. by filtering or sed imentation.
  • the clarified solution can be circulated back to the membrane filtra tion stage. By circulating the clarified concentrate back to the filtration stage wa ter recovery and also recovery of salts can be increased further.
  • the solution according to the present invention produces pure water, which can be recircu lated, and by-products (e.g. phosphorous or metal salts) without addition of chemicals.
  • the created centrifugal forces cause both high turbulence on the mem brane surface as well as efficient removal of precipitates from the perimeter of the filter module is achieved.
  • turbulence is cre ated by rotor and therefore the concentrate flow rate can be kept very low. Therefore, when the solution where some bulk crystallization has occurred has discharged from the module with the help of centrifugal forces its flow velocity decreased dramatically close to zero. These conditions favor crystallization and growth of crystals. After removal of formed precipitates, the clarified solution can be lead back to membrane filtration stage.
  • the described process concept enable achievement of a very high water recovery. With municipal wastewater it was shown that even a water re covery of 99.7% was achieved. During the filtration over 50% of phosphorous was recovered as a calcium phosphate precipitate.
  • the high shear rate technology solution according to the present in vention can also be used in combination with traditional spiral wound modules.
  • the spiral wound modules are first used to recover most of water and the high shear rate modules are used to increase further the water recovery and to recover salts.
  • the presented process concept can be used to treat saline waters consisting of sparingly soluble ions (typically multivalent ions such as Ca, Mg, Ba, sulphate, phosphate). These kind of water exist in mining industry, energy, pulp and paper or chemical and food industry and in future biorefineries. In the future, the limitation requirements concerning discharge of salts will be stricter and this increases the need for the solution according to the present invention.
  • sparingly soluble ions typically multivalent ions such as Ca, Mg, Ba, sulphate, phosphate
  • the solution according to the present invention enables achievement of significantly higher water recovery i.e. 90% or even 99.7% without plugging of the filters. Simultaneously, with the increased water recovery, the recovery of ionic compounds e.g. phosphorous or metals can he achieved due to their spon taneous precipitation.
  • the solution according to the present invention enables purification of waters containing sparingly soluble salts which is already today a challenge in mining industry and will be challenge in future also in other industrial sectors. The purification can be done at extremely high water recovery and sim ultaneously recovery of salts as solid product can be achieved.
  • the solution according to the present invention can be utilized also in many industrial sectors where saline wastewaters or process waters need to be purified.
  • the process of the invention can be also used for recovery of salts from waters.
  • the process of the invention can be utilized to recover phosphorous from industrial or municipal wastewaters or to treat nutrient rich waters from production of biomethane or composting plants.

Abstract

The present invention relates to the field of treatment of water, process water, wastewater, sewage or sludge, and more particularly to a method and apparatus for treatment of saline water. An apparatus for treatment of saline water according to the present invention comprises a membrane module (12), (20), (40), (50), (60), said membrane module (12), (20), (40), (50), (60) comprising: a frame structure (21), (22), (23), an input for incoming water (11), (104), an at least one membrane (24), (26) for filtering the incoming water (11), (104), and an output for purified water (13), (235), (236), in which said membrane module (12), (20), (40), (50), (60) of said apparatus comprises an at least one blade (25), (27) or disk arranged close to a surface of said at least one membrane (24), (26), wherein said apparatus further comprises a motor (15) arranged to rotate one of said at least one blade (25), (27) or disk or said at least one membrane (24), (26), wherein said frame structure (21), (22), (23) comprises an output for recovering (36) concentrated stream (14) containing crystallized particles (17) from outer periphery of said frame structure (21), (22), (23), and wherein said output for purified water (13), (235), (236) is arranged in the direction of the tangent of the outer periphery of said frame structure (23) or at an acute angle α in relation to the tangent of the outer periphery of said frame structure (23).

Description

A METHOD AND APPARATUS FOR TREATMENT OF SALINE WATER
FIELD OF THE INVENTION
The present invention relates to the field of treatment of water, pro cess water, wastewater, sewage or sludge, and more particularly to a method and apparatus for treatment of saline water.
BACKGROUND OF THE INVENTION
Saline wastewaters have caused significant environmental problems e.g. in mining industry. Membrane technologies are used to purify these waters. Traditional membrane modules include tubular membrane modules and plate and frame membrane modules, hollow fibre membrane modules as well as spiral wound membrane modules. The most commonly used membrane modules i.e. spiral wound membrane modules used today enable rather low water recovery level i.e. 50-75%. The crystallization in the bulk solution or on the membrane surface will lead to plugging of the feed channel and fouling of the membrane or plugging of the whole filter.
In commonly used spiral wound modules and tubular modules the flow velocity created by pumping the feed solution over the membrane surface is critical parameter concerning fouling and removal of precipitates. In these modules the concentrate having high flow velocity is typically recirculated back to the module in order to enhance water recovery. In spiral wound modules only 10-15% of the feed permeated the membrane in one cycle. When the formed precipitates are recirculated back to the module they can cause plugging of the channel in the module or scaling on the membrane surface. Therefore, the water recovery is commonly only around 50-75%.
Consequently, there is a need for a more efficient solution for treat ment of saline water that would provide better water recovery level. There is a demand in the market for a method for treatment of saline waters as well as for an apparatus for treatment of saline waters that would be more efficient than the current prior art solutions.
BRIEF DESCRIPTION OF THE INVENTION
An object of the present invention is thus to provide a method and an apparatus for implementing the method so as to overcome the above problems and to alleviate the above disadvantages. The objects of the invention are achieved by a method for treatment of saline water, which method comprises the steps of:
- leading incoming water to a frame structure of a membrane module of a saline water treatment apparatus through an incoming water input,
- filtering the incoming water through said membrane module,
- outputting purified water out from said frame structure of said mem brane module through a purified water output,
wherein said method also comprises the step of:
- rotating one of an at least one membrane of said membrane module or an at least one blade or disk arranged close to a surface of said at least one membrane, and
- recovering concentrated stream containing crystallized particles from outer periphery of said frame structure.
Preferably, in the step of rotating said at least one blade or disk is posi tioned in relation to said at least one membrane so as to create turbulent forces for lifting crystallized particles from the surface of said at least one membrane and to create centrifugal forces for removing said crystallized particles from the surface of said at least one membrane to the outer periphery of said frame struc ture.
Preferably, the method further comprises the step of:
- reducing the concentrated stream flow velocity outside said membrane module.
Preferably, the method further comprises the step of:
- removing crystallized particles from said concentrated stream.
Preferably, the method further comprises the step of:
- recirculating back to said frame structure of a membrane module the clarified solution of said concentrated stream from which crystallized particles are removed.
Preferably, the method further comprises the step of:
- purifying feed water in a first stage water purification process and providing a wastewater output from said first stage water purification process as an input incoming water for said step of leading.
Further preferably, the first stage water purification process is a nanofil tration process or a reverse osmosis process. Furthermore, the objects of the invention are achieved by an apparatus for treatment of saline water, which apparatus comprises a membrane module, said membrane module comprising:
- a frame structure,
- an input for incoming water,
- an at least one membrane for filtering the incoming water, and
- an output for purified water,
wherein said membrane module of said apparatus comprises an at least one blade or disk arranged close to a surface of said at least one membrane, wherein said apparatus further comprises a motor arranged to rotate one of said at least one blade or disk or said at least one membrane,
wherein said frame structure comprises an output for recovering con centrated stream containing crystallized particles from outer periphery of said frame structure, and
wherein said output for purified water is arranged in the direction of the tangent of the outer periphery of said frame structure or at an acute angle a in relation to the tangent of the outer periphery of said frame structure.
Preferably, said at least one blade or disk is positioned in relation to said at least one membrane so as to create turbulent forces for lifting crystallized particles from the surface of said at least one membrane and to create centrifu gal forces for removing said crystallized particles from the surface of said at least one membrane to the outer periphery of said frame structure.
Preferably, said apparatus further comprises an arrangement for reduc ing the concentrated stream flow velocity outside said membrane module.
Preferably, said apparatus further comprises an arrangement for remov ing crystallized particles from said concentrated stream.
Preferably, a wastewater output from a first stage water purification pro cess is provided as said input for incoming water. Further preferably, said first stage water purification process is a nanofiltration process or a reverse osmosis process.
Preferably, said at least one blade comprises one blade or two blades.
Preferably, said at least one membrane comprises one membrane or two membranes. Alternatively, said at least one membrane comprises one or more stacks of 2-200 membranes, preferably one or more stacks of 20-50 mem branes. Preferably, said output for purified water is arranged in the direction of the tangent of the outer periphery of said frame structure.
Preferably, said acute angle a is less than 90 degrees and more than 0 degrees, preferably less than 45 degrees and more than 0 degrees, more pref erably less than 15 degrees and more than 0 degrees.
Preferably, said apparatus is used for saline wastewater treatment or saline process water treatment.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a block diagram of one embodiment of an arrange ment for treatment of saline water according to the present invention.
Figure 2 shows an exploded view of one embodiment of a membrane module according to the present invention.
Figure 3 shows a flow diagram of one embodiment of a method for treatment of saline water according to the present invention.
Figure 4 shows an exploded view of another embodiment of a mem brane module according to the present invention.
Figure 5 shows a partial perspective view of a third embodiment of a membrane module arrangement according to the present invention.
Figure 6 shows a block diagram of another embodiment of an ar rangement for treatment of saline water according to the present invention.
Figure 7 shows a flow diagram of another embodiment of a method for treatment of saline water according to the present invention.
Figure 8 shows a cross-sectional view of a fourth embodiment of a membrane module arrangement according to the present invention.
In the following, the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings of Figures 1 to 8.
DETAILED DESCRIPTION OF THE INVENTION
Figure 1 shows a block diagram of one embodiment of an arrange ment for treatment of saline water according to the present invention. The saline water treatment arrangement according to the present embodiment comprises a high shear rate water purification block 10, said high shear rate water purifica tion block 10 comprising an input for incoming water 1 1 , a membrane module 12 for filtering the incoming water 1 1 , an output for purified water 13, and an output for a concentrated stream 14. From said high shear rate water purification block 10 said concentrated stream 14 is lead to a precipitate removal block 16 for removal of precipitate residue 17. From said precipitate removal block 16 precipitate residue 17 is removed, i.e. crystallized particles are removed and the clarified solution 18 is recirculated back to the feed of said high shear rate water purification block. The saline water treatment arrangement according to the pre sent embodiment also comprises a motor 15 connected to the membrane mod ule 12 of said high shear rate water purification block 10. In the embodiment of the present invention, the flow velocity of the concentrated stream 14 reduces as concentrated stream 14 exits the membrane module 12. This facilitates the precipitate formation. Furthermore, the apparatus may further comprise an ar rangement for reducing the concentrated stream 14 flow velocity outside said membrane module 12, such as an open chamber design with unlimited stream mass flow in the concentrated stream 14 exiting area at the membrane module 12.
In an alternative embodiment, there can be several high shear rate water purification blocks 10 arranged in series so that the clarified solution out put 18 of one high shear rate water purification block 10, from which clarified solution 18 the precipitate residue 17 has been removed, can function as the incoming water feed 1 1 of the following high shear rate water purification block 10. This facilitates the achievement of higher water recovery in said arrange ment for treatment of saline water.
Figure 2 shows an exploded view of one embodiment of a membrane module according to the present invention. The membrane module 20 according to the present embodiment comprises a frame structure 21 , 22, 23. In the pre sent embodiment, the frame structure 21 , 22, 23 of the membrane module 20 has a lower cover frame 21 , an upper cover frame 22 and a central frame part 23. The membrane module 20 also comprises an input for incoming water, which input is not shown in Figure 2.
The membrane module 20 according to the present embodiment also comprises a membrane 24 for filtering the incoming water. Furthermore, the membrane module 20 comprises an output for purified water 235. In the present embodiment, the output for purified water 235 is arranged to the central frame part 23 of the membrane module 20. In the present embodiment, the output for purified water 235 is arranged at an acute angle a in relation to the outer periph ery frame of the membrane module 20. The membrane module 20 according to the present embodiment also comprises a blade 25 or a disk arranged close to a surface of the membrane 24. Said blade 25 or said disk is positioned in relation to said membrane 24 so as to create turbulent forces for lifting crystallized particles from the surface of said membrane 24. Said blade 25 or said disk is also positioned so as to create cen trifugal forces for removing said crystallized particles from the surface of said membrane 24 to outer periphery of said frame structure 21 , 22. Said blade 25 may be a rectangular blade 25, curved blade, s-shaped blade, perforated blade or any other blade with a suitable shape for creating turbulent and centrifugal forces. The membrane module 20 according to the present invention may also comprise an output for recovering a concentrated stream containing crystallized particles and concentrated dissolved compounds from the outer periphery of said frame structure 21 , 22, which output is not shown in Figure 2.
The membrane module 20 of the saline water treatment arrangement according to the present invention also comprises a motor 15 connected to the membrane module 20, said motor 15 being arranged to rotate one of said blade 25, said disk or said membrane 24. The motor 15 is not shown in Figure 2.
Figure 3 shows a flow diagram of one embodiment of a method for treatment of saline water according to the present invention. In the saline water treatment method according to the present embodiment incoming water 1 1 is first lead 32 to a frame structure 21 , 22, 23 of a membrane module 20 of a saline water treatment apparatus through an incoming water input 1 1 . The incoming water 1 1 is then filtered 33 through a membrane 24 of said membrane module 20. The membrane module 20 according to the present embodiment also com prises a blade 25 or a disk arranged close to a surface of the membrane 24. As the incoming water 1 1 is being filtered 33 through said membrane 24 of said membrane module 20, said blade 25 or said disk is rotated 34. Alternatively, said membrane 24 is rotated 34.
During said rotating 34 said blade 25 or said disk is positioned in re lation to said membrane 24 so as to create turbulent forces for lifting crystallized particles from the surface of said membrane 24 and to create centrifugal forces for removing said crystallized particles from the surface of said membrane 24 to outer periphery of said frame structure 21 , 22.
Thereafter, the purified water is outputted 35 from said frame struc ture 21 , 22, 23 of said membrane module 20 through a purified water output 235. In the saline water treatment method according to the present embodiment, a concentrated stream containing crystallized particles is recovered 36 from the outer periphery of said frame structure 21 , 22. From said precipitate concen trated stream the precipitate residue 17 is removed, i.e. crystallized particles are then removed and thereby recovered 36. In the present invention, the centrifugal forces lead the crystallized particles to the outer periphery of said frame struc ture 21 , 22 and they do not precipitate or form scale on the membrane surface.
Figure 4 shows an exploded view of another embodiment of a mem brane module according to the present invention. The membrane module 40 according to the present another embodiment comprises a frame structure 21 , 22, 23. In the present another embodiment, the frame structure 21 , 22, 23 of the membrane module 40 has a lower cover frame 21 , an upper cover frame 22 and a central frame part 23. The membrane module 40 also comprises an input for incoming water, which input is not shown in Figure 4.
The membrane module 40 according to the present another embodi ment also comprises membranes 24, 26 for filtering the incoming water. Further more, the membrane module 40 comprises an output for purified water 235. In the present another embodiment, the output for purified water 235 is arranged to the central frame part 23 of the membrane module 40. In the present embod iment, the output for purified water 235 is arranged at an acute angle a in relation to the outer periphery frame of the membrane module 40.
The membrane module 40 according to the present another embodi ment also comprises blades 25, 27 or disks arranged close to a surface of the membranes 24, 26. Said blades 25, 27 or said disks are positioned in relation to said membranes 24, 26 so as to create turbulent forces for lifting crystallized particles from the surface of said membranes 24, 26. Said blades 25, 27 or said disks are also positioned so as to create centrifugal forces for removing said crystallized particles from the surface of said membranes 24, 26 to outer periph ery of said frame structure 21 , 22. Said blades 25, 27 may be rectangular blades 25, 27, curved blades, s-shaped blades, perforated blades or any other blades with a suitable shape for creating turbulent and centrifugal forces. The mem brane module 40 according to the present invention may also comprise an out put for recovering a concentrated stream containing crystallized particles from the outer periphery of said frame structure 21 , 22, which output is not shown in Figure 4.
The membrane module 40 of the saline water treatment arrangement according to the present invention also comprises a motor 15 connected to the membrane module 40, said motor 15 being arranged to rotate one of said blades 25, 27 said disks or said membranes 24, 26. The motor 15 is not shown in Figure 4.
Figure 5 shows a partial perspective view of a third embodiment of a membrane module arrangement according to the present invention. The mem brane module arrangement 50 according to the present third embodiment com prises several membrane stacks 51 -58. In the present another embodiment, the membranes of said membrane stacks 51 -58 are arranged as partially overlap ping each other so as to create turbulent forces for lifting crystallized particles from the surface of said membranes of said membrane stacks 51 -58. The mem brane module arrangement 50 according to the present third embodiment may also comprise an at least one blade or disk arranged close to a surface of an at least one membrane. Flowever, said at least one blade or disk of the membrane module arrangement is not shown in Figure 5.
The membrane module arrangement 50 of the saline water treatment arrangement according to the present invention also comprises a motor 15 con nected to the membrane module arrangement 50, said motor 15 being arranged to rotate said several membrane stacks 51 -58. Said several membrane stacks 51 -58 are rotated so as to create centrifugal forces for removing said crystallized particles from the surface of said membranes 24, 26 to outer periphery of said frame structure 21 , 22. The motor 15 is not shown in Figure 5.
Figure 6 shows a block diagram of another embodiment of an ar rangement for treatment of saline water according to the present invention. The saline water treatment arrangement according to the present another embodi ment comprises a first stage water purification block 101 and a high shear rate water purification block 10. The first stage water purification block 101 comprises an input for incoming water 102, a first stage output for purified water 1 03, and a first stage output for wastewater 104. The first stage water purification process 101 carried out in said first stage water purification block 101 may e.g. be a nanofiltration process 101 or a reverse osmosis process 101 using e.g. spiral wound modules or other type modules.
The high shear rate water purification block 10 comprises an input for incoming water 1 04, a membrane module 12 for filtering the incoming water 1 04, an output for purified water 13, and an output for a concentrated stream 14. From said high shear rate water purification block 10 said concentrated stream 14 is lead to a precipitate removal block 16 for removal of precipitate residue 17. From said precipitate removal block 16 precipitate residue 17 is removed and the clarified solution 18 is recirculated back to the feed of said high shear rate water purification block. In the saline water treatment arrangement according to the present another embodiment, the wastewater 104 from the first stage water purification block 101 is forwarded as an incoming water 104 input to the high shear rate water purification block 10. The saline water treatment arrangement according to the present another embodiment also comprises a motor 15 con nected to the membrane module 12 of said high shear rate water purification block 10. In the embodiment of the present invention, the flow velocity of the concentrated stream 14 reduces as concentrated stream 14 exits the membrane module 12. This facilitates the precipitate formation. Furthermore, the apparatus may further comprise an arrangement for reducing the concentrated stream 14 flow velocity outside said membrane module 12, such as an open chamber de sign with unlimited stream mass flow in the concentrated stream 14 exiting area at the membrane module 12.
In an alternative embodiment, there can be several high shear rate water purification blocks 10 arranged in series so that the clarified solution out put 18 of one high shear rate water purification block 10, from which clarified solution 18 the precipitate residue 17 has been removed, can function as the incoming water feed 1 1 of the following high shear rate water purification block 10. This facilitates the achievement of higher water recovery in said arrange ment for treatment of saline water.
Figure 7 shows a flow diagram of another embodiment of a method for treatment of saline water according to the present invention. In the saline water treatment method according to the present another embodiment, incoming water 1 02 is first lead to first stage water purification 31 in the first stage water purification block 101 . From the first stage water purification block 101 the out putted wastewater 104 is forwarded 32 as an incoming water 104 input to the high shear rate water purification block 10. The first stage water purification pro cess 101 carried out in said first stage water purification block 101 may e.g. be a nanofiltration process 101 or a reverse osmosis process 101 , using e.g. spiral wound modules or other type modules.
In the high shear rate water purification block 10, the incoming water 104 is lead 32 to a frame structure 21 , 22, 23 of a membrane module 20, 40, 50 of a saline water treatment apparatus through an incoming water input 1 04. The incoming water 1 04 is then filtered 33 through an at least one membrane 24, 26 of said membrane module 20. The membrane module 20 according to the pre sent another embodiment also comprises an at least one blade 25, 27 or disk arranged close to a surface of said at least one membrane 24, 26. As the incom ing water 1 1 is being filtered 33 through said at least one membrane 24, 26 of said membrane module 20 40, 50, said at least one blade 25, 27 or disk is ro tated 34. Alternatively, said at least one membrane 24, 26 is rotated 34.
During said rotating 34 said at least one blade 25, 27 or disk is posi tioned in relation to said at least one membrane 24, 26 so as to create turbulent forces for lifting crystallized particles from the surface of said at least one mem brane 24, 26 and to create centrifugal forces for removing said crystallized par ticles from the surface of said at least one membrane 24, 26 to outer periphery of said frame structure 21 , 22.
Thereafter, the purified water is outputted 35 from said frame struc ture 21 , 22, 23 of said membrane module 20, 40, 50 through a purified water output 235. In the saline water treatment method according to the present an other embodiment, a concentrated stream containing crystallized particles is re covered 36 from the outer periphery of said frame structure 21 , 22. From said precipitate concentrated stream the precipitate residue 17 i.e. crystallized parti cles is then removed and thereby recovered 36. In the present invention, the centrifugal forces lead the crystallized particles to the outer periphery of said frame structure 21 , 22 and they do not precipitate or form scale on the mem brane surface.
Figure 8 shows a cross-sectional view of a fourth embodiment of a membrane module arrangement according to the present invention. The mem brane module arrangement 60 according to the present fourth embodiment com prises a frame structure, an input for incoming water and an at least one mem brane for filtering the incoming water, which are not shown in Figure 8.
The membrane module 60 according to the present fourth embodi ment also comprises an at least one blade 65 an at least one blade arranged close to a surface of an at least one membrane for filtering the incoming water. Furthermore, the membrane module 60 comprises an output for purified water 236. In the present embodiment, the output for purified water 236 is arranged in the direction of the tangent of the outer periphery frame or at an acute angle a in relation to the tangent of the outer periphery frame of the membrane module 60. In Figure 8 the tangent of the outer periphery frame of the membrane module 60 is drawn and indicated as TAN. Said acute angle a of said output for purified water 236 in relation to the tangent of the outer periphery frame of the membrane module 60 is indicated as a.
Said acute angle a is less than 90 degrees and more than 0 degrees, 90° > a > 0°. Preferably, said acute angle a is less than 45 degrees and more than 0 degrees, 45° > a > 0°. Further preferably, said acute angle a is less than 15 degrees and more than 0 degrees, 15° > a > 0°. Further preferably, the output for purified water 236 is arranged in the direction of the tangent of the outer periphery frame of the membrane module 60, i.e. a = 0°.
Said output for purified water 236 may for example have a round shape, a rectangular shape, oval shape or elliptical shape. Said output for puri fied water 236 may also be closable and openable, e.g. for intermittent opera tion. Said output for purified water 236 provides enhanced removal of precipi tates from the filtration module 60. The rotation speed or the at least one blade 65 may also be variable.
In the saline water treatment apparatus according to the present in vention, the membrane module 12, 20, 40, 50 comprises an at least one mem brane 24, 26 for filtering the incoming water 1 1 , 104. Said at least one membrane
24, 26 may comprise one membrane 24 or two membranes 24, 26. Said at least one membrane 24, 26 may also comprise one or more stacks of 2-200 mem branes 24, 26. Alternatively, said at least one membrane 24, 26 may also com prise one or more stacks of 20-50 membranes 24, 26.
In the saline water treatment apparatus according to the present in vention, the membrane module 12, 20, 40, 50 comprises an at least one blade
25, 27 or disk arranged close to a surface of said at least one membrane 24, 26. Said at least one blade 25, 27 may comprise one blade 25 or two blades 25, 27. The saline water treatment apparatus according to the present invention may e.g. be used for saline wastewater treatment or saline process water treatment.
The solution according to the present invention presents a process to treat saline water with a special membrane module, which enables concentra tion of the feed solution above saturation point without fear of plugging of the filtration channel or scaling of the membrane.
With the help of the solution according to the present invention the formation of crystallized particles on the membrane surface is substantially de creased due to the shear forces created by rotating a blade or a disk on the membrane surface or by rotating the membrane. The removal of the salt solu tions and the crystallized particles can be done efficiently in the filter in which turbulence is created by centrifugal forces e.g. rotating a rotor blade or a disk close to membrane surface. In this way an extremely high turbulence can be generated, scaling on the membrane surface can be reduced, and bulk precipi tation is facilitated. The turbulence produced by the rotating blade/disk/mem brane cause solids and foulants to be lifted off the membrane surface. In addi tion, in the present invention centrifugal forces are created, which throw precip itates out from the membrane surface to the outer periphery of said frame struc ture 21 , 22 and to the concentrate stream containing precipitate residue 17 i.e. crystallized particles.
The filter construction according to the present invention preferen tially removes precipitates due to centrifugal forces. The principle is the same as in the centrifuge where more dense solid particles are removed by centrifugal forces. The removal of precipitates from the module can be achieved with very low concentrate flow rate and efficient concentration can be achieved in one stage inside the module.
In the traditional prior art membrane modules the concentrate having high flow velocity may also be recirculated back to the module in order to en hance water recovery. In spiral wound modules only 10-15% of the feed perme ated the membrane in one cycle. When the formed precipitates are recirculated back to the module they can cause plugging of the channel in the module. There fore, the water recovery is commonly around 50-75%.
High shear rate prevents the formation of crystallized particles on the membrane surface and enables concentration of salts above saturation point, i.e. filtration can be operated at bulk crystallisation conditions. This means that significantly higher water recovery and salt concentration can be achieved than e.g. when spiral wound filtration modules are used.
Furthermore, in the present invention centrifugal forces are not only used to create turbulence and to prevent scaling formation on the membrane surface but also to remove the formed crystals out from the module. Because the turbulence and centrifugal forces are created by rotating a rotor, the pumping velocity can be very low. Therefore, flow velocity outside the module can be almost zero and these conditions favours the precipitation process.
The formed precipitates can then be removed e.g. by filtering or sed imentation. The clarified solution can be circulated back to the membrane filtra tion stage. By circulating the clarified concentrate back to the filtration stage wa ter recovery and also recovery of salts can be increased further. The solution according to the present invention produces pure water, which can be recircu lated, and by-products (e.g. phosphorous or metal salts) without addition of chemicals.
In the membrane module construction according to the present in vention the created centrifugal forces cause both high turbulence on the mem brane surface as well as efficient removal of precipitates from the perimeter of the filter module is achieved. In the solution of the invention, turbulence is cre ated by rotor and therefore the concentrate flow rate can be kept very low. Therefore, when the solution where some bulk crystallization has occurred has discharged from the module with the help of centrifugal forces its flow velocity decreased dramatically close to zero. These conditions favor crystallization and growth of crystals. After removal of formed precipitates, the clarified solution can be lead back to membrane filtration stage.
The described process concept enable achievement of a very high water recovery. With municipal wastewater it was shown that even a water re covery of 99.7% was achieved. During the filtration over 50% of phosphorous was recovered as a calcium phosphate precipitate.
The high shear rate technology solution according to the present in vention can also be used in combination with traditional spiral wound modules. In this two-stage process the spiral wound modules are first used to recover most of water and the high shear rate modules are used to increase further the water recovery and to recover salts.
The presented process concept can be used to treat saline waters consisting of sparingly soluble ions (typically multivalent ions such as Ca, Mg, Ba, sulphate, phosphate). These kind of water exist in mining industry, energy, pulp and paper or chemical and food industry and in future biorefineries. In the future, the limitation requirements concerning discharge of salts will be stricter and this increases the need for the solution according to the present invention.
With the help of the present invention municipal wastewater was con centrated to water recovery of 99.7% without plugging of the filters. Calcium phosphate precipitated outside module and did not foul the membrane. There fore, a significantly higher water recovery and higher concentration of salts was achieved when a membrane filtration using presented solution was applied.
The solution according to the present invention enables achievement of significantly higher water recovery i.e. 90% or even 99.7% without plugging of the filters. Simultaneously, with the increased water recovery, the recovery of ionic compounds e.g. phosphorous or metals can he achieved due to their spon taneous precipitation. The solution according to the present invention enables purification of waters containing sparingly soluble salts which is already today a challenge in mining industry and will be challenge in future also in other industrial sectors. The purification can be done at extremely high water recovery and sim ultaneously recovery of salts as solid product can be achieved.
The solution according to the present invention can be utilized also in many industrial sectors where saline wastewaters or process waters need to be purified. The process of the invention can be also used for recovery of salts from waters. For instance, the process of the invention can be utilized to recover phosphorous from industrial or municipal wastewaters or to treat nutrient rich waters from production of biomethane or composting plants.

Claims

1. A method for treatment of saline water, said method comprising the steps of:
- leading (32) incoming water (11 ), (104) to a frame structure (21 ), (22), (23) of a membrane module (12), (20), (40), (50), (60) of a saline water treatment apparatus through an incoming water input (11), (104),
- filtering (33) the incoming water (11), (104) through said membrane module (12), (20), (40), (50), (60),
- outputting (35) purified water out from said frame structure (21), (22), (23) of said membrane module (12), (20), (40), (50), (60) through a purified water output (13), (235), (236),
said method being characterized in that it comprises the steps of:
- rotating (34) one of an at least one membrane (24), (26) of said mem- brane module (12), (20), (40), (50), (60) or an at least one blade (25), (27) or disk arranged close to a surface of said at least one membrane (24), (26), and
- recovering (36) concentrated stream (14) containing crystallized parti cles (17) from outer periphery of said frame structure (21), (22), (23).
2. A method according to claim 1, characterized in that in the step of rotating (34) said at least one blade (25), (27) or disk is positioned in relation to said at least one membrane (24), (26) so as to create turbulent forces for lifting crystallized particles from the surface of said at least one membrane (24), (26) and to create centrifugal forces for removing said crystallized particles from the surface of said at least one membrane (24), (26) to the outer periphery of said frame structure (21 ), (22), (23).
3. A method according to claim 1 or to claim 2, characterized in that the method further comprises the step of:
- reducing the concentrated stream (14) flow velocity outside said mem brane module (12), (20), (40), (50), (60).
4. A method according to any one of claims 1 to 3, characterized in that the method further comprises the step of:
- removing crystallized particles (17) from said concentrated stream
(14).
5. A method according to claim 4, characterized in that the method further comprises the step of: - recirculating back to said frame structure (21), (22), (23) of a mem brane module (12), (20), (40), (50), (60) the clarified solution (18) of said con centrated stream (14) from which crystallized particles (17) are removed.
6. A method according to any one of claims 1 to 5, characterized in that the method further comprises the step of:
- purifying (31 ) feed water (102) in a first stage water purification process (101) and providing a wastewater (104) output from said first stage water purifi cation process (101 ) as an input incoming water (11 ), (104) for said step of lead ing (32).
7. A method according to claim 6, characterized in that said first stage water purification process (101) is a nanofiltration process (101) or a re verse osmosis process (101).
8. An apparatus for treatment of saline water, wherein said apparatus comprises a membrane module (12), (20), (40), (50), (60), said membrane mod- ule (12), (20), (40), (50), (60) comprising:
- a frame structure (21), (22), (23),
- an input for incoming water (11 ), (104),
- an at least one membrane (24), (26) for filtering the incoming water (11), (104), and
- an output for purified water (13), (235), (236),
said apparatus being characterized in that
said membrane module (12), (20), (40), (50), (60) comprises an at least one blade (25), (27) or disk arranged close to a surface of said at least one membrane (24), (26),
wherein said apparatus further comprises a motor (15) arranged to ro tate one of said at least one blade (25), (27) or disk or said at least one mem brane (24), (26),
wherein said frame structure (21), (22), (23) comprises an output for recovering (36) concentrated stream (14) containing crystallized particles (17) from outer periphery of said frame structure (21), (22), (23), and
wherein said output for purified water (13), (235), (236) is arranged in the direction of the tangent of the outer periphery of said frame structure (23) or at an acute angle a in relation to the tangent of the outer periphery of said frame structure (23).
9. An apparatus according to claim 8, characterized in that said at least one blade (25), (27), (28), (29) or disk is positioned in relation to said at least one membrane (24), (26) so as to create turbulent forces for lifting crystal lized particles from the surface of said at least one membrane (24), (26) and to create centrifugal forces for removing said crystallized particles from the surface of said at least one membrane (24), (26) to the outer periphery of said frame structure (21), (22), (23).
10. An apparatus according to claim 8 or to claim 9, characterized in that said apparatus further comprises an arrangement for reducing the concentrated stream (14) flow velocity outside said membrane module (12), (20), (40), (50), (60).
11. An apparatus according to any one of claims 8 to 10, characterized in that said apparatus further comprises an arrangement for remov ing crystallized particles (17) from said concentrated stream (14).
12. An apparatus according to any one of claims 8 to 11, characterized in that a wastewater (104) output from a first stage water purification process (101) is provided as said input for incoming water (104).
13. An apparatus according to claim 12, characterized in that said first stage water purification process (101) is a nanofiltration process (101) or a reverse osmosis process (101).
14. An apparatus according to any one of claims 8 to 13, characterized in that said at least one blade (25), (27), (28), (29) comprises one blade (25) or two blades (25), (27), (28), (29).
15. An apparatus according to any one of claims 8 to 14, characterized in that said at least one membrane (24), (26) comprises one mem brane (24) or two membranes (24), (26).
16. An apparatus according to any one of claims 8 to 14, characterized in that said at least one membrane (24), (26) comprises one or more stacks of 2-200 membranes (24), (26), preferably one or more stacks of 20-50 membranes (24), (26).
17. An apparatus according to any one of claims 8 to 16, characterized in that said output for purified water (13), (235), (236) is arranged in the direction of the tangent of the outer periphery of said frame structure (23).
18. An apparatus according to any one of claims 8 to 16, characterized in that said acute angle a is less than 90 degrees and more than 0 degrees, preferably less than 45 degrees and more than 0 degrees, more pref erably less than 15 degrees and more than 0 degrees.
19. An apparatus according to any one of claims 8 to 18 used for saline wastewater treatment or saline process water treatment.
PCT/FI2019/050832 2018-11-22 2019-11-21 A method and apparatus for treatment of saline water WO2020104728A1 (en)

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CN113173623A (en) * 2021-03-19 2021-07-27 福建兴恒机械科技有限公司 Cycle reuse information full-automatic water filter
CN113173623B (en) * 2021-03-19 2022-08-09 福建兴恒机械科技有限公司 Cycle reuse information full-automatic water filter

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