CN104724862A - Desalination system and method - Google Patents

Abstract

The disclosure provides a desalination system, the system comprises a desalination unit, and the desalination unit receives a first flow for desalination and a second flow to take away ion removed by the first flow. A precipitation unit is in flow connection with the desalination unit and circulates the second flow to the desalination unit. The system also (a) comprises a pretreatment unit at an upstream of the desalination unit, wherein the pretreatment unit receives a feed flow and at least one pretreatment chemical agent and generates the ion-reduced first flow for the desalination unit; (b) adds calcium in the second flow in the precipitation unit or passing through the precipitation unit; and/or (c) comprises a film based purification device receiving a desalination output flow from the desalination unit.

Description

Desalination system and method

Invention field

The disclosure relates to desalination system and uses the method for desalting plant (such as electrodialysis reversal (EDR) unit, preferably combines with settler), reclaims for product water.

Background of invention

In industrial processes, produce a large amount of waste water, such as aqueous salt solution.Usually, such salt brine solution is unsuitable for directly consuming in family or industrial application.In view of limited qualified water source, current (such as waste water, seawater or have brackish water) deionization (being commonly referred to desalination) is made to become the option produced for the qualified water directly consumed in family or industrial application.

By the waste water that mining (such as acid mine drainage), mineral are processed and Metal Production industry produces usually containing the calcium of elevated levels and vitriol and metal ion (such as Fe, Mn, Al, Mg, Cu and/or Zn).Many places also find high-caliber vitriol in underground water in the world.The deionization with the solution (especially having the solution of the difficulty soluble salt (such as: the vitriol of calcium, barium and strontium) of high density) of the vitriol of elevated levels is subject to the precipitation of these salt and the restriction of fouling.

Due to relatively high efficiency and the higher rate of recovery of product water, electrodialysis reversal unit is for making these stream desalinations.During operation, such stream is incorporated into EDR unit, for desalination, reclaims for product water.

The metal ion existed in the waste water produced by mining, mineral processing and Metal Production causes fouling in EDR film.This causes the process cost of Water Sproading rate and low membrane lifetime and the raising reduced.Usually, during the desalination of stream, precipitation unit is used for liquid circulation to corresponding EDR unit.The liquid of this circulation makes the electrically charged thing class removed from the stream through EDR process concentrate.But, in a liquid salt or other impurity concentration along with between EDR unit and corresponding precipitation unit liquid circulation and improve.This causes, in precipitation unit, solids precipitation occurs.The particle obtained is taken in EDR unit by the liquid of recirculation, and the fouling obtained or stainedly destroy EDR equipment.

Attempt to avoid introducing solids precipitation in EDR equipment.Such as, post strainer can be arranged between precipitation unit and corresponding EDR unit, with filtering particle precipitation, insert the liquid into EDR equipment subsequently.But post strainer suffers inefficient and high replacement frequency, this causes the running cost improved.

Or precipitation unit can be made enough large, and to provide other settling zone for solid-liquid separation, this cycle period being reduced in liquid introduces the possibility of particle in EDR unit.But large-sized precipitation unit can cause the installing space, fund cost and the assembling difficulty that improve, and this can suppress them extensively to implement.

As compared to other desalination system (such as reverse osmosis and distillation), the product water from EDR unit can have the solid of higher dissolving.Therefore, in many places, the product water from EDR unit may not meet discharge or recycling regulation.

Need the new desalination system based on EDR with improving and method.

Summary of the invention

From mining, mineral process and the waste water of Metal Production industry can be included in EDR film the level causing stained calcium, vitriol and metal ion (such as Fe, Mn, Al, Mg, Cu and/or Zn).The amount of iron, magnesium and aluminium can up to several thousand ppm.Total dissolved solidss can more than 3000 ppm.

In addition, if the concentration of sulfate radical and calcium ion not substantially the same and they do not remove from desalination system, then any one ion may be combined with the salt becoming into dirt.The salt that there is into dirt limits recovery in demineralising process.If pending waste water sulfate radical is high and calcium is low (such as by the waste water of digging up mine, mineral are processed or Metal Production produces, its can have such as be greater than about 500 ppm calcium and be greater than about 2000 ppm sulfate radicals), then expect removing sulfate radical, to reduce fouling in electrodialysis reversal (EDR) unit.

The removal of insoluble salt in precipitation unit is depended in recovery based on the system of EDR, and then depends on the ionic equilibrium of incoming flow.Such as, the stream with high-sulfate and low calcium can not produce enough calcium sulfate salts that will remove, particularly in pre-treatment step.This causes the product water rate of recovery reducing whole system.Expect the level reducing calcium, sulfate radical and/or metal ion, to protect desalter, such as electrodialysis reversal unit.

Process EDR incoming flow is to remove calcium, sulfate radical and/or metal ion, combine with the nanofiltration of the EDR output stream of recirculation, to remove sulfate radical and other polyvalent ion, be decreased through the amount of the sulfate ion of EDR cell processing, thus reduce fouling and improve recovery rate.

Present specification describes a kind of desalination system, described system comprises desalination unit, described desalination unit accept first-class for desalination and second to take away the ion from first-class removing.Precipitation unit is communicated with desalination unit fluid and second is circulated to desalination unit.Described system also (a) comprises pretreatment unit in the upstream of desalination unit, and described pretreatment unit accepts incoming flow and the agent of at least one pretreatment chemical, and produces the first-class for desalination unit of ion-reduction; B () adds lime in precipitation unit or in the second through precipitation unit; And/or (c) comprises the purification devices based on film, described purification devices accepts the desalination output stream from desalination unit.

Described desalination unit is preferably electrodialysis reversal unit.

Described desalination system preferably makes waste water desalination, and described waste water comprises acid mine drainage, or be rich in sulfate ion but based on volumetric molar concentration, calcium concn lower than sulfate concentration, such as, lower than the half of sulfate concentration.

Optionally, can by from desalination unit more than 90% enriched material be recycled to preatreating reactors.Particularly, the liquid produced after making settling vessel dewatering sludge can be back to preatreating reactors.

This specification sheets also describes a kind of method, and described method comprises by using second from first-class deionizing, makes first-class desalination in desalination unit.Second is circulated to desalination unit from precipitation unit.Described method also comprises: (a), before making treated incoming flow desalination, uses at least one pretreatment chemical agent process incoming flow; B () adds lime in precipitation unit or in the second through precipitation unit; And/or (c) uses purification devices purifying based on film from the desalination output stream of desalination unit.

This specification sheets also describes a kind of method, wherein in desalination unit, processes feed water, and wherein enriched material is recirculated through precipitation unit, and wherein feed intake lime in precipitation unit.Described method can such as the treatment of acid mine drainage, but or is rich in the another kind of feed water that sulfate ion calcium concn is less than the half of sulfate concentration.Lime feeds intake and contributes to removing metal and the sulfate radical of magnesium and other remnants.

This specification sheets also describes a kind of method, wherein in desalination unit, processes feed water, and enriched material is recirculated through precipitation unit, and wherein desalination product water processes further in reverse osmosis (RO) or nanofiltration (NF) film unit.Film unit contributes to satisfied strict emission regulation.Optionally, film unit enriched material can be recycled to preatreating reactors.Film unit is preferably NF unit, particularly when feed water is acid mine drainage, but or is rich in sulfate ion calcium concn when being less than the another kind of feed water of the half of sulfate concentration.

This specification sheets also describes a kind of desalination system, and described system comprises pretreatment unit, and described pretreatment unit accepts incoming flow and the agent of at least one pretreatment chemical, and produces the discharge stream of the first-class of ion-reduction and ion-concentrated.This desalination system comprises desalination unit, and it is first-class for desalination that described desalination unit accepts from pretreatment unit.The agent of at least one pretreatment chemical comprises alkali and oxygenant.

This specification sheets also describes a kind of desalting method, and described method comprises and uses at least alkali and oxygenant pre-treatment incoming flow, makes subsequently treated to flow through desalination unit for desalination.

This specification sheets also describes a kind of composition for the treatment of waste water, and described waste water has concentration more than the iron ion of 100 ppb, concentration more than the aluminum ion of 100 ppb and the concentration magnesium ion more than 50 ppb.Described composition comprises: alkali; Oxygenant; With water-soluble, branching, polymeric dithiocarbamates.

The present invention includes following items:

Project 1. 1 kinds of desalination systems, described system comprises:

Desalination unit, its arrange for accept first-class for desalination and second to take away the ion from described first-class removing;

Precipitation unit, it is communicated with described desalination unit fluid and arranges and is used for described second is circulated between which;

With following one of at least:

A () pretreatment unit in the upstream of described desalination unit and arranging is used for:

Accept incoming flow and the agent of at least one pretreatment chemical, and

Produce ion-reduction first-class for desalination in described desalination unit, the discharge stream of and ion-concentrated;

B () described desalination system arranges and is used for adding lime in described precipitation unit or in the second through described precipitation unit; With

C (), based on the purification devices of film, it is arranged for accepting the desalination output stream from described desalination unit.

The desalination system of project 2. project 1, wherein said desalination unit is electrodialysis reversal unit.

The desalination system of project 3. project 1 or 2, wherein said precipitation unit comprises the settler with precipitation zone and solid-liquid separation region.

The desalination system of project 4. project 3, wherein said precipitation unit provides described second from the top in described solid-liquid separation region.

Desalination system any one of project 5. project 1-4, wherein said desalination system makes waste water desalination, and described waste water comprises acid mine drainage, but or is rich in the half that sulfate ion calcium concn is less than sulfate concentration.

Desalination system any one of project 6. project 1-5, wherein said desalination system comprises pretreatment unit in the upstream of described desalination unit.

The desalination system of project 7. project 6, the agent of wherein said at least one pretreatment chemical comprises alkali.

The desalination system of project 8. project 7, wherein said alkali is unslaked lime, white lime, Wingdale or rhombspar, and it adds and obtains about 50-about 1000 ppm alkali.

The desalination system of project 9. project 7 or 8, the agent of wherein said at least one pretreatment chemical comprises oxygenant.

The desalination system of project 10. project 9, wherein said oxygenant is clorox, and it adds and obtains about 50-about 200 ppm clorox.

The desalination system of project 11. project 9 or 10, the agent of wherein said at least one pretreatment chemical comprises water-soluble, branching, polymeric dithiocarbamates.

The desalination system of project 12. project 11, wherein said polymeric dithiocarbamates is Metclear ^tM2405, it adds and obtains about 1-about 5 ppm Metclear ^tM2405.

The desalination system of project 13. project 11 or 12, the agent of wherein said at least one pretreatment chemical comprises chitosan, and it adds and obtains about 20-about 200 ppm chitosan.

The desalination system of project 14. project 11 or 12, the agent of wherein said at least one pretreatment chemical comprises FeCl ₃, it adds and obtains about 25-about 75 ppm FeCl ₃.

Desalination system any one of project 15. project 6-14, wherein said pretreatment unit comprises:

Settler, it arranges the discharge stream for generation of clarification stream and clarification; With

Filter unit, it is communicated with described settler fluid, and to accept the discharge stream of described clarification, described filter unit arranges and is used for filtrate flow being circulated to described settler and producing filtering emission stream.

The desalination system of project 16. project 15, is wherein back to described settler by the filtrate flow recirculation from described filter unit of at least 90%.

The desalination system of project 17. project 15 or 16, wherein said pretreatment unit comprises ultra filtration unit, and it is communicated with described settler fluid, to accept the discharge stream of described clarification, and arranges for generation of pretreated liquid filtrate for described desalination unit.

The desalination system of project 18. project 17, is wherein accepted as a part for described second at least partially by the pretreated liquid filtrate that described desalination unit accepts.

The desalination system of project 19. project 17 or 18, wherein said Operation system setting is used for acid being received described ultra filtration unit or in the discharge stream of the clarification through described ultra filtration unit.

Desalination system any one of project 20. project 1-19, wherein said Operation system setting is used for adding lime in described precipitation unit or in the second through described precipitation unit.

The desalination system of project 21. project 20, wherein said Operation system setting is used for adding lime in the precipitation element arranged in the container of described settling vessel.

The desalination system of project 22. project 20 or 21, the amount that wherein said lime adds is enough to be reduced in the amount being circulated to the sulfate ion the second of described desalination unit from described precipitation unit.

Desalination system any one of project 23. project 20-22, wherein said system comprises filter unit, to filter the precipitation discharge stream from described precipitation unit.

The desalination system of project 24. project 23, is wherein back to described desalination system by the recirculation of filtrate at least partially from described filtering unit.

Desalination system any one of project 25. project 20-24, wherein said system comprises ultra filtration unit, with filtration cycle to the second of described desalination unit.

The desalination system of project 26. project 25, wherein said Operation system setting is used for acid to receive in described ultra filtration unit or in the second of described ultra filtration unit.

Desalination system any one of project 27. project 20-26, wherein described second recirculation will be back to described desalination system at least partially.

Desalination system any one of project 28. project 1-27, wherein said system comprises the purification devices based on film, and it is arranged for accepting the desalination output stream from described desalination unit.

The desalination system of project 29. project 29, the wherein said purification devices based on film is nanofiltration device.

The desalination system of project 30. project 28 or 29, the wherein said purification devices based on film produces concentration logistics and permeate discharge stream, described concentration logistics recirculation will be back to described desalination system at least partially, and described permeate stream will at least partially be discharged from desalination system as purified discharge stream.

Desalination system any one of project 31. project 28-30, is wherein back to described desalination system by the desalination output stream recirculation at least partially from described desalination unit, and without the described purification devices based on film.

Desalination system any one of project 32. project 28-31, the wherein said purification devices based on film produces permeate stream, and the desalination output stream at least partially from described desalination unit is discharged together with permeate stream from described desalination system, as purified discharge stream.

Project 33. 1 kinds of desalination systems, described system comprises:

Pretreatment unit, its setting is used for:

Accept incoming flow and the agent of at least one pretreatment chemical, and

Produce the discharge stream of the first-class and ion-concentrated of ion-reduction; With

Desalination unit, it arranges first-class for desalination for what accept from described pretreatment unit;

The agent of wherein said at least one pretreatment chemical comprises alkali and oxygenant.

The desalination system of project 34. project 33, wherein said alkali is unslaked lime, white lime, Wingdale or rhombspar.

The desalination system of project 35. project 34, wherein adds described alkali to obtain about 50-about 1000 ppm alkali.

Desalination system any one of project 36. project 33-35, wherein said oxygenant is clorox.

The desalination system of project 37. project 36, wherein adds clorox to obtain about 50-about 200 ppm clorox.

Desalination system any one of project 38. project 33-37, the agent of wherein said at least one pretreatment chemical comprises water-soluble, branching, polymeric dithiocarbamates.

The desalination system of project 39. project 38, wherein said polymeric dithiocarbamates is Metclear ^tM2405.

The desalination system of project 40. project 39, wherein adds Metclear ^tM2405 to obtain about 1-about 5 ppm Metclear ^tM2405.

Desalination system any one of project 41. project 33-40, the agent of wherein said at least one pretreatment chemical comprises chitosan.

The desalination system of project 42. project 41, wherein adds chitosan to obtain about 20-about 200 ppm chitosan.

Desalination system any one of project 43. project 33-42, the agent of wherein said at least one pretreatment chemical comprises FeCl ₃.

The desalination system of project 44. project 43, wherein adds FeCl ₃to cause about 25-about 75 ppm FeCl ₃.

Desalination system any one of project 45. project 33-44, wherein said pretreatment unit comprises:

Settler, it arranges the discharge stream for generation of clarification stream and clarification; With

Filter unit, it is communicated with described settler fluid, and to accept the discharge stream of described clarification, described filter unit arranges and is used for filtrate flow being circulated to described settler and producing filtering emission stream.

The desalination system of project 46. project 45, wherein said pretreatment unit also comprises:

Ultra filtration unit, it is communicated with described settler fluid, to accept described clarification stream, and arranges for generation of pretreated liquid filtrate.

Desalination system any one of project 47. project 33-46, wherein said desalination unit is electrodialysis reversal unit, reverse osmosis units, nano-filtration unit, electrodialysis cell or supercapacitor desalination cell unit.

Desalination system any one of project 48. project 33-47, wherein said desalination system makes waste water desalination: described waste water comprises acid mine drainage; But be rich in the half that sulfate ion calcium concn is less than sulfate concentration; Or comprise concentration and exceed the iron ion of the acceptable level of described desalination unit, aluminum ion and magnesium ion.

The desalination system of project 49. project 48, wherein said waste water comprises concentration more than the iron ion of 100 ppb, concentration more than the aluminum ion of 100 ppb and the concentration magnesium ion more than 50 ppb.

Desalination system any one of project 50. project 33-49, it is first-class that wherein said desalination unit accepts from described pretreatment unit, and without to first process in addition.

Project 51. 1 kinds of desalting method, described method comprises:

Make first-class by desalination unit, for desalination;

Make second via precipitation unit by desalination unit, to take away the ion from described first-class removing;

With following one of at least:

A () makes incoming flow and the agent of at least one pretreatment chemical by pretreatment unit, described first-class for desalination in described desalination unit to produce, and produces the discharge stream of ion-concentrated;

B () adds lime in described precipitation unit or in the second through described precipitation unit; With

C () makes desalination output stream from described desalination unit by based on the purification devices of film, to produce purified discharge stream.

The desalting method of project 52. project 51, wherein makes described first-class and second by electrodialysis reversal unit.

The desalting method of project 53. project 51 or 52, wherein said method is included in precipitation unit and precipitates, and described precipitation unit comprises the settler with precipitation zone and solid-liquid separation region.

The desalting method of project 54. project 53, wherein said method comprises makes described second lead to described desalination unit from the top in described solid-liquid separation region.

Desalting method any one of project 55. project 51-54, wherein said desalting method makes waste water desalination, and described waste water comprises acid mine drainage, but or is rich in the half that sulfate ion calcium concn is less than sulfate concentration.

Desalting method any one of project 56. project 51-55, in described precipitation unit, wherein add lime cartridge mix with the desalination output stream from described desalination unit containing making at least lime, with make described mixture by the reactor in described precipitation unit and settler, to produce described second.

Project 57. 1 kinds is for the treatment of useless water desalting method, and described method comprises:

Make incoming flow and the agent of at least one pretreatment chemical by pretreatment unit, to produce the discharge stream of the first-class of ion-reduction and ion-concentrated;

Make described first-class by desalination unit, for desalination;

The agent of wherein said at least one pretreatment chemical comprises alkali and oxygenant.

The desalting method of project 58. project 57, wherein said alkali is unslaked lime, white lime, Wingdale or rhombspar.

The desalting method of project 59. project 58, wherein adds alkali to obtain about 50-about 1000 ppm alkali.

Desalting method any one of project 60. project 57-59, wherein said oxygenant is clorox.

The desalting method of project 61. project 60, wherein adds clorox to obtain about 50-about 200 ppm clorox.

Desalting method any one of project 62. project 57-61, wherein said waste water comprises concentration more than the iron ion of 100 ppb, concentration more than the aluminum ion of 100 ppb and the concentration magnesium ion more than 50 ppb.

Project 63. 1 kinds of compositions for the treatment of waste water, described waste water has concentration more than the iron ion of 100 ppb, concentration more than the aluminum ion of 100 ppb and the concentration magnesium ion more than 50 ppb, and described composition comprises:

Alkali;

Oxygenant;

Water-soluble, branching, polymeric dithiocarbamates; With

Flocculation agent.

The composition of project 64. project 63, wherein

Described alkali is: lime, magnesium calcium carbonate, caustic soda, or their any combination;

Described oxygenant is: clorox, chlorine, ClO ₂, KMnO ₄, hydrogen peroxide, or their any combination;

Described water-soluble, branching, polymeric dithiocarbamates: MetClear ^tM2405; With

Described flocculation agent comprises: polymeric flocculant.

The composition of project 65. project 64, wherein:

Described alkali is: Wingdale;

Described oxygenant is: clorox;

Described water-soluble, branching, polymeric dithiocarbamates is: MetClear ^tM2405; With

Described flocculation agent is: polymeric flocculant and FeCl ₃combination.

The composition of project 66. project 65, wherein:

Wingdale is joined in described waste water, to obtain at least about 400 ppm;

Clorox is joined in described waste water, to obtain at least about 50 ppm;

By MetClear ^tM2405 join in described waste water, to obtain at least about 2 ppm;

Polymeric flocculant is joined in described waste water, to obtain at least about 1 ppm; With

By FeCl ₃join in described waste water, to obtain about 50 ppm.

By reference to the accompanying drawings, when after the description of checking following specific embodiments, other side of the present disclosure and feature will become apparent for those of ordinary skill in the art.

Accompanying drawing is sketched

With reference now to accompanying drawing, only as an example, embodiment of the present disclosure is described.

Fig. 1 is the schematic diagram of a part for desalination system of the present disclosure.

Fig. 2 is the schematic diagram of another part of desalination system.

Fig. 3 is the schematic diagram of the settler that can be used for desalination system of the present disclosure.

Fig. 4 is the figure of the concentration that Fe, Mn and Al ion in the effluent of the sample of the acid mine drainage using Wingdale and clorox process is described.

Fig. 5 A is the figure of the concentration that Fe, Mn and Al ion in the effluent of the sample of the acid mine drainage using different pretreatment compositions process is described.

Fig. 5 B is the figure of the concentration that Fe, Mn and Al ion in the effluent of the sample of the acid mine drainage using different pretreatment compositions process is described.

Fig. 5 C is the figure of the concentration that Fe, Mn and Al ion in the effluent of the sample of the acid mine drainage using different pretreatment compositions process is described.

Fig. 6 is the schematic diagram of a kind of exemplary desalination system of the present disclosure.

Fig. 7 is the explanation of disclosure method.

Fig. 8 is the explanation of the optional part of described method.

Describe in detail

Generally, the disclosure provides a kind of desalination system, and described system comprises desalination unit, preferred electrodialysis reversal (EDR) unit.Electrodialysis reversal unit is Electrochemical separation device, and it uses anion-exchange membrane and cationic exchange membrane, with under the DC electric current that periodic polarity is reverse, from water and other fluid deionizing or charged thing class.Although the disclosure relates to electrodialysis reversal unit, other Electrochemical separation device can be used, such as electrodialysis (ED) unit or supercapacitor desalination cell (SCD) device.But EDR is proved to be as the less technology being subject to scale effect, be therefore preferred compared with other Electrochemical separation device.In another is alternative, desalination unit can be the purification devices based on film, such as reverse osmosis (RO) or nanofiltration (NF) device.But in example system, the purification devices based on film may produce the rate of recovery less a little, therefore, compared with the purification devices based on film, EDR device is also preferred.

Under situation of the present disclosure, in charging or inlet flow, add charging or inlet flow that chemical agent or composition cause having the chemical agent of illustrated concentration or the treated of composition.Such as, state " using the compounds X process of 50 ppm " and " adding the compounds X of 50 ppm " refer to add q.s compounds X to cause the compounds X of 50 ppm in treated inlet flow.Similarly, state " the compound Y of 100 ppm that feed intake " and " dosage of the compound Y of 100 ppm " and refer to that the compound Y adding q.s is to obtain the compound Y of 100 ppm in treated inlet flow.

In FIG desalination system is described.The precipitation unit 11 that this desalination system comprises electrodialysis reversal (EDR) unit 10 and is communicated with EDR unit 10 fluid.EDR unit 10 is also communicated with pretreatment unit 12 fluid.An example of pretreatment unit is discussed below in more detail about Fig. 2.Pretreatment unit 12 accepts brine feed stream and the agent of at least one pretreatment chemical, produces first-class 13 of ion-reduction.

As discussed above, when process from mining, mineral processing and the waste water of Metal Production industry time, expect the amount being reduced in vitriol and calcium in brine feed stream, such as, to about equal concentration, make to reduce formation dirt.Also expect the amount of the metal ion (such as at least iron, magnesium and aluminium) reduced from brine feed stream, to reduce the stained of EDR unit.

Pretreatment unit 12 removes metal ion, to reduce fouling in EDR unit from brine feed stream.By forming the insoluble precipitate of ion, metal ion can be removed in pretreatment unit 12.By supplying hydroxyl ion (OH to brine feed stream ^-), thus form the insoluble petal oxyhydroxide be settled out from water, can this point be realized.Therefore, the agent of at least one pretreatment chemical can comprise alkali, such as lime, such as unslaked lime, white lime or Wingdale.Use lime can produce the sludge undesirably measured, it needs to dispose.Can expect to add one or more other pretreatment chemical agent, to remove the metal of dissolving, reduce the amount of the solid of generation simultaneously.Below discuss the specific examples of spendable pretreatment chemical agent in more detail.

EDR unit 10 arrange for accept from pretreatment unit 12 first-class 13, and to accept from the second 14 of precipitation unit 11.EDR unit produces the second output stream 16 of the first output stream 15 of ion-reduction and ion-concentrated, as discussed in detail below.

Precipitation unit 11 makes salt precipitate in the second output stream 16, produces precipitation discharge stream 17.Supernatant liquor recirculation is back to EDR unit 10 as second 14 by precipitation unit 11.The supernatant liquor of recirculation is used, to accept the ion from EDR incoming flow removing, as discussed in detail below in EDR unit.Can join in second 14 by first-class for a part 13, to replenish the solution of removing in precipitation discharge stream 17.

During the incoming flow desalination that calcium is low when making sulfate radical high, expect to be further purified the first output stream 15 or its part by the following method: (a) will be recycled to pre-treatment 12 by the first output stream 15 at least partially, b () makes the first output stream 15 or its part lead to one or more electricity or Electrochemical separation unit for further desalination, or (c) the two.Concentrated discharge recirculation can be back to pretreatment unit 12 by one or more electricity or Electrochemical separation unit.As mentioned above, in pretreatment unit 12, process output stream 15 to remove sulfate ion and nanofiltration output stream 15 combines, be decreased through the amount of the sulfate ion of EDR cell processing, thus reduce fouling and improve recovery rate.

Electricity or Electrochemical separation unit can comprise nano-filtration unit 19, as discussed in detail below.Nano-filtration unit 19 makes monovalent ion lead to nanofiltration permeate 20, and discharges penetrant 20, such as, together with the first output stream 15, prevents them from accumulating in systems in which.Nanofiltration enriched material 21 recirculation can be back to desalination system, such as, be back to pretreatment unit 12, to improve the overall rate of recovery.First output stream 15 and/or penetrant 20 form purified discharge stream 22.Nano-filtration unit 19 can replace with reverse osmosis units.Purified discharge stream 22 can be used as final effluent and discharges from desalination system, or, if needed, can process further, to meet any concrete discharge or recycling requirement.

electrodialysis reversal unit.In some limiting examples, EDR unit 10 comprises pair of electrodes, and its setting is used for being used separately as anode and negative electrode.Electrode can comprise electro-conductive material, and it can be heat conducting or for heat conducting, and can not can have the particle of reduced size and high surface area.In some instances, electrode can be stainless steel plate, titanium plate or is coated with the titanium plate of platinum.In other example, electro-conductive material can comprise one or more carbon materials.The limiting examples of carbon material comprises carbosphere in activated carbon granule, porous carbon particle, carbon fiber, carbon aerogels, porous, or their combination.In other example, electro-conductive material can comprise conductive composites, such as magnesium or iron or the oxide compound of the two, or titanium, zirconium, vanadium, tungsten carbide, or their combination.

EDR unit comprises multiple anion-exchange membrane replaced of arranging between the anode and cathode and cationic exchange membrane, to form multiple dilution of replacing and enriched material passage between which.Anion-exchange membrane only negatively charged ion by.Cationic exchange membrane only positively charged ion by.Anion-exchange membrane can comprise the polymeric material of quaternary amines.Cationic exchange membrane can comprise the polymeric material of sulfonic acid group and/or hydroxy-acid group.

EDR unit can comprise multiple between every a pair film and the spacer arranged between electrode and adjacent film.Spacer can comprise any ion-permeable non-conducting material, comprises film and porous and non-porous materials.

During operation, when EDR unit is in normal polarization state, when electric current being put on EDR unit, liquid (such as first-class 13 and second 14) is by the first valve and enter corresponding alternately dilution and enriched material passage respectively along the first input channel.

In dilution passage, the positively charged ion in first-class 13 by cationic exchange membrane towards cathodic migration to enter adjacent passage.Negatively charged ion is moved to enter other adjacent passage towards anode by anion-exchange membrane.Adjacent passage (enriched material passage) on the every side being arranged in dilution passage, positively charged ion does not move by anion-exchange membrane, and negatively charged ion does not move by cationic exchange membrane, even if electric field applies towards the power (such as, negatively charged ion is attracted to positively charged anode) of corresponding electrode ion.Therefore, negatively charged ion and positively charged ion retain wherein and concentrate in corresponding enriched material passage.As a result, second 14 is by enriched material passage, so that the concentrated negatively charged ion gone out from dilution channel migration and positively charged ion are carried EDR unit.

During operation, first-class 13 and second 14 can enter EDR unit along corresponding first input channel and the second input channel, the first output stream 15 and the second output stream 16 can from corresponding first output channel and the discharges of the second output channel.Compared with first-class 13, first output streams 15, there is comparatively low ion concns, and compared with second 14, the second output stream 16 has higher ion.

The polarity of the electrode of EDR unit 10 can be reverse, to be reduced in fouling in EDR equipment and stained tendency.In reverse polarization state, the dilution passage deriving from normal polarization state can be used as enriched material passage, and to accept second 14, and the enriched material passage deriving from normal polarization state can be used as dilution passage, to accept first-class 13.

For the layout of disclosed system, it should be noted that EDR unit is not limited to any specific electrodialysis reversal (EDR) unit for the treatment of liquid.

precipitation unit.Solid sediment is separated with supernatant liquor by precipitation unit 11.Can in precipitation unit 11, or in the second output stream 16 through precipitation unit 11, add pretreatment chemical agent in addition, such as lime, to improve in discharge stream 17 amount of the solid of removing, and is reduced in the amount of ion (such as sulfate radical) of recirculation in enriched material second 14.The lime of about 100-1000 ppm dosage can be used, such as white lime.In the example be described further below, use the white lime dosage of 445 ppm.

Precipitation unit 11 can comprise precipitation zone (or being called reactor) and solid-liquid separation region (such as settler).Solid precipitates in the reactor, and in solid-liquid separation region with liquid separation.Suitable precipitation unit 11 is the settler shown in U.S. Patent Application Publication No. US 2011/0114567 A1, and it is incorporated herein by reference.Another kind of suitable precipitation unit 11 is the AquaSel that can derive from GE Water & Process Technologies ^tMthe brine concentration unit of system.As discussed in detail below, the pretreatment chemical agent joining pretreatment unit 12 can join in precipitation unit 11, or can join in addition in the second output stream 16 of precipitation unit 11.

The settler described in Fig. 1 of US 2011/0114567 is identical with the settler illustrated in figure 3.Settler 38 is included in the precipitation element 40 arranged in container 42, and arranges for limiting precipitation zone 44 between precipitation element 40 and container 42 and solid-liquid separation region 46.Precipitation zone 46 is arranged for accepting the first-class of saline fluid 48 and the throw out solid (not shown) from saline fluid.Solid-liquid separation region 46 arranges and is used for by gravity settling solid.Outlet 50 is positioned at the top 52 of container, and arranges the second 54 being used for drawing liquid from solid-liquid separation region 46, and compared with first-class, this second 54 has lower salinity.

The salinity of the second 54 of liquid is subject to multifactorial impact perhaps, such as, and the structure of settler 38.The top 52 of precipitation element 40 and container 42 has hollow-cylindrical shape.Precipitation element 40 comprises the lower opening 56 be communicated with container 42.In addition, the upper shed 58 be communicated with the lower opening 56 of precipitation element 40 can arrange or can not be set to be communicated with container 42.In some exemplary precipitation unit, in solid-liquid separation region, the flow velocity of per unit cross-sectional area is about 0.12-about 0.48 gallon per minute/square feet cross-sectional area (gpm/ft ²), or about 8.2 × 10 ^-5-Yue 3.3 × 10 ^-4cube meter per second/square metre cross-sectional area (m/s).The diameter D on the top 52 of container 42 is about 1.5-about 2.8 with the ratio of the diameter D1 of precipitation element 40, or preferred about 1.6-about 2.2.In a concrete exemplary settler, the bottom of container 42 is conical, and cone angle is about 60-about 120 degree.The height H of container 42 and the ratio of diameter D are not less than 0.2.

In some limiting examples, container 42 can have other shape, such as overall cylinder form.Similarly, precipitate element 40 and also can comprise other shape, such as cone shape.

For settler 38 illustrated in fig. 3, provide limiting element 60, to limit restricted areas 62, it is arranged in precipitation zone 44 at least partially, and is communicated with solid-liquid separation region 46 with precipitation zone 44.As an example, limiting element 60 can comprise two unlimited ends and the hollow-cylindrical shape had with homogeneous diameter.

Precipitation unit 11 arranges and is used for supernatant liquor to be recycled in EDR unit 10 as second 14.Preferably second 14 is filtered, such as, by ultra filtration unit, subsequently by EDR unit 10.Acid (such as sulfuric acid) can join in second.Add acid reduce pH and be reduced in fouling in the filtering membrane of EDR unit 10.As discussed above, the concentrated charged thing class from first-class 13 removings of second 14, to produce the second output stream 16.When the circulation of liquid 14 continues, the concentration of salt or other impurity improves continuously, until liquid 14 is saturated or supersaturation.As a result, saturated or oversaturated degree can reach the point when there is solids precipitation in liquid 14 along with the time.

Salt or other contamination precipitation may not occur, until degree of saturation is relatively high.Therefore, seed particles (not shown) can be added in precipitation unit 11, precipitate under lower degree of saturation to induce.In some applications, seed particles can comprise solid particulate, includes but not limited to CaSO ₄particle and their hydrate.

Precipitation unit can have the top of hollow-cylindrical shape and conical bottom.Or precipitation unit can have other shape, such as cylindrical or rectangular shape.In limiting examples, the part on the top of precipitation unit 11 can be used as solid-liquid separation space for promoting that solids precipitation is separated with second (liquid) 14.During operation, second 14 can be provided or extract second 14 from the top in the solid-liquid separation space of precipitation unit 11.In other example, can limit or solid-liquid separation space can not be limited.

Therefore, the second output stream 16 being introduced from its upper end in precipitation unit 11 period, in precipitation unit 11, solids precipitation can be separated with liquid 14 (or with the second output stream 16) at least partially.In some instances, the solids precipitation that diameter is greater than designated diameter can remain in the region (not shown) of the restriction of precipitation unit 11 or in the bottom of precipitation unit 11 and settle down.Other solids precipitation that diameter is less than designated diameter can disperse in liquid 14.

In some applications, the second output stream 16 does not directly reboot in precipitation unit 11, and provides fluid supply (not shown) to introduce liquid 16 in precipitation unit 11.

In some applications, when by liquid 14 from precipitation unit 11 be incorporated into do not filter the solids precipitation wherein disperseed EDR unit 10 time, the solids precipitation of dispersion can enter EDR unit 10, to cause stained or scale problems.In order to avoid during desalination to the destruction of EDR unit 10, can arrange between EDR unit 10 and precipitation unit 11 can the strainer of back scrubbing, remove solids precipitation at least partially with filter liquide 14 with from liquid 14, subsequently liquid 14 is incorporated into EDR unit 10 from precipitation unit 11.

The term used herein strainer of back scrubbing " can " refers to reproducible strainer, and it can recycle after being rinsed by wash fluid, such as, with proper flow side's flush filter in the opposite direction, for filtering liquid to be filtered.In an example, can the strainer of back scrubbing can by Pall Corporation, Port Washington, New York, U.S.A sell.Compared with adopting the conventional desalination system of single pass filtration device (such as post strainer), the strainer of back scrubbing can have higher tolerance limit for the load of solids precipitation.Due to the replacement frequency that the desalination system center pillar strainer in routine is relatively high, use can the strainer of back scrubbing can improved system efficiency and reducing costs.

The operation of precipitation unit produces settling vessel discharge stream 17.In some instances, a certain amount of stream 18 can be removed, as " blowdown " from liquid 14 in precipitation unit 11, to keep constant volume and/or to reduce the saturated or oversaturated degree of some thing classes in precipitation unit 11.The stream that stream 18 can remove with the bottom from precipitation unit 11 mixes, to form settling vessel discharge stream 17.Discharge stream can be filtered further, to form the filtering emission stream of the thing class comprising precipitation.Depend on the chemical constitution of raw material salt solution incoming flow, settling vessel discharge stream 17 and filtering emission stream can comprise Ca, Mg and/or SO of solid or dissolving ₄salt.

pretreatment unit.Pretreatment unit 12 removes metal ion, to reduce fouling in EDR unit from brine feed stream.Pretreatment unit 12 can comprise: settler, and it arranges the discharge stream for generation of clarification stream and clarification; And filter unit, it is communicated with described settler fluid, and to accept the discharge stream clarified, described filter unit arranges and is used for filtrate flow being circulated to settler and producing filtering emission stream.Pretreatment unit also can comprise: ultra filtration unit, and it is communicated with described settler fluid, to accept clarification stream, and arranges for generation of pretreated liquid filtrate.Acid (as sulfuric acid) can join clarification stream.Add acid to reduce pH and be reduced in fouling in the filtering membrane of EDR unit.

An example of pretreatment unit 12 illustrates in fig. 2.As described, pretreatment unit comprises settler 23, and it accepts input brine feed stream 24.As discussed above, in some brine feed solution, such as by the waste water that mining, mineral are processed and Metal Production industry produces, expect the amount reducing sulfate radical and other metal ion (such as Fe, Mn, Al, Ca and/or Mg) from input brine feed stream 24, to reduce the burden of EDR unit 10, thus improve the rate of recovery.

Pretreatment unit 12 uses lime 25 (such as unslaked lime, white lime or Wingdale) or another kind of alkali (such as: magnesium calcium carbonate or " rhombspar "; Or caustic soda) process inlet flow 24, to reduce the amount of heavy metal (such as aluminium, iron and magnesium) and sulfate radical.Such as, inlet flow can use 100 ppm lime treatments.Inlet flow preferably also uses oxygenant (such as clorox) to process.The pretreatment chemical agent 26 that inlet flow 24 can use one or more other in addition processes, to reduce the level of sulfate radical and/or other metal ion further.Such as, inlet flow 24 can use and process further for improvement of the polymkeric substance of heavy metals removal, flocculation agent, flocculation agent or their any combination.The pretreatment chemical agent added can have multiple function.Such as, FeCl ₃can be used as flocculation agent, pH control agent, for the metal that dissolves and metalloid precipitated catalyst, or their any combination.FeCl ₃contribute to the precipitation of metal and the metalloid (such as arsenic) dissolved.The combination of the process chemical agent used and dosage depend on the composition of pending inlet flow, and determine by test input stream.Such as, in the inlet flow with silicon-dioxide and iron, magnesium, aluminium, calcium and magnesium ion, can expect together with Metclear ^tM2405 and rhombspar combination use.Metclear ^tM2405 effectively except de-iron, magnesium and aluminum ion, but not too effective in removing calcium and magnesium.Rhombspar effectively removes silicon-dioxide and calcium and magnesium ion, but not significantly except de-iron, magnesium or aluminum ion.

When inlet flow is acid mine drainage, alkali and oxygenant pre-treatment inlet flow is used to remove enough sulfate radicals, calcium, Mn, Al and Fe ion, make discharge can accept for being fed to desalination unit, such as, be fed to reverse osmosis units, nano-filtration unit or electrodialysis reversal unit.For reverse osmosis or nanofiltration feed water, the acceptable level of Fe, Al and Mn can be respectively such as: be less than about 100 ppb, be less than about 100 ppb and be less than about 50 ppb.For EDR unit, the acceptable level for feed water can be the Al of the Fe of such as 300 ppb, the Mn of 100 ppb and 100 ppb.

Test pretreatment compositions reduces acid mine drainage sample, and (it comprises 540 ppm Ca ions; 2400 ppm SO ₄ion; 74 ppm Na ions; 250 ppm Mg ions; 7 ppm Mn ions; 16 ppm Al ions; 21 ppm Fe ions; 3500 ppm total dissolved solidss; And pH is 3.5) in metal ion amount ability illustrate, under the dosage of 400 ppm or higher, Wingdale effectively removes Fe and Al.When the concentration of Wingdale is increased to up to 1000 ppm Wingdale, see the removal of the raising of Fe and Al ion, but even if under the dosage up to 5000 ppm, Wingdale effectively can not remove Mn.The clorox (hypo) adding 50-100 ppm in 800 or 100 ppm Wingdales provides almost Mn completely to remove, but the Al being above 150 ppm clorox display reductions removes.The unitized dose of about 400-1000 ppm Wingdale and 50-150 ppm clorox provides preferred composition for removing Fe, Al and Mn from acid mine drainage.There is the white lime (Ca (OH) of 200-400 ppm rhombspar or 100 ppm ₂) composition produce the result similar with having the composition of 400 ppm Wingdales.Also can use unslaked lime (CaO), because when being added to the water, it forms white lime.These compositions-treated acid mine drainages are used to cause the effluent that can accept for being fed to desalination unit.

Such as, the compositions-treated with 800 ppm Wingdales and 100 ppm clorox is used to cause having the effluent of about 100 ppb Fe, about 90 ppb Al and about 20 ppb Mn.This shows in the diagram.

Although test clorox, the present inventor's expection can use other oxygenant.Oxygenant can be such as, clorox, chlorine, ClO ₂, KMnO ₄, hydrogen peroxide, or their any combination.

The ability of the metal ion of test pretreatment compositions removing acid mine drainage sample illustrates, adds the Metclear of 2 ppm ^tM2405 allow the amount of Wingdale to reduce about 25%, to meet the aimed concn of 100 ppb Fe, 100 ppb Al and 50 ppb Mn.These results illustrate in fig. 5.

A kind of dual stage process, wherein all Metclear ^tM2405, be less than the clorox of the Wingdale of 25% and about half for the first stage, surplus is used for subordinate phase, allows to reduce amount of lime (to 400 ppm) further, meets the aimed concn of Mn and Fe, but do not meet Al.These results illustrate in figure 5b, and wherein sample I-VI tests in two benches.Within the first stage, after lime, add Metclear ^tM2405, in the first phase, preferred addition sequence is lime or another kind of alkali, oxygenant, Metclear ^tM2405 or another kind of alkali, subsequently other flocculation agent any or flocculation agent.Metclear ^tM2405 can optionally add in subordinate phase, but in the experiment being shown in Fig. 5 B, are not add in subordinate phase.

Sample I is corresponding to following dosage: in the first phase, 75 ppm Wingdales, 0 ppm clorox and 2 ppm Metclear ^tM2405; With in subordinate phase, 325 ppm Wingdales, 100 ppm clorox and 0 ppm Metclear ^tM2405.PH is 7.89.

Sample II is corresponding to following dosage: in the first phase, 75 ppm Wingdales, 50 ppm clorox and 2 ppm Metclear ^tM2405; With in subordinate phase, 325 ppm Wingdales, 50 ppm clorox and 0 ppm Metclear ^tM2405.PH is 7.98.

Sample III is corresponding to following dosage: in the first phase, 75 ppm Wingdales, 100 ppm clorox and 2 ppm Metclear ^tM2405; With in subordinate phase, 325 ppm Wingdales, 0 ppm clorox and 0 ppm Metclear ^tM2405.PH is 8.01.

Sample IV is corresponding to following dosage: in the first phase, 50 ppm Wingdales, 0 ppm clorox and 2 ppm Metclear ^tM2405; With in subordinate phase, 350 ppm Wingdales, 100 ppm clorox and 0 ppm Metclear ^tM2405.PH is 7.78.

Sample V is corresponding to following dosage: in the first phase, 50 ppm Wingdales, 50 ppm clorox and 2 ppm Metclear ^tM2405; With in subordinate phase, 350 ppm Wingdales, 50 ppm clorox and 0 ppm Metclear ^tM2405.PH is 7.85.

Sample VI is corresponding to following dosage: in the first phase, 50 ppm Wingdales, 100 ppm clorox and 2 ppm Metclear ^tM2405; With in subordinate phase, 350 ppm Wingdales, 0 ppm clorox and 0 ppm Metclear ^tM2405.PH is 7.98.

Except 400 ppm Wingdales, 100 ppm clorox and 2 ppm Metclear ^tMbeyond 2405, add with about 20-200 ppm the concentration that chitosan reduces all three metal ion species further.These results illustrate in the following table 1.

Table 1

Except 400 ppm Wingdales, 100 ppm clorox and 2 ppm Metclear ^tMbeyond 2405, add the FeCl of 50 ppm ₃reduce Al ionic concn, wherein improve Fe concentration acceptably.These results illustrate in figure 5 c, and wherein sample I is corresponding to the 400 ppm Wingdales that feed intake, 100 ppm clorox and 2 ppm Metclear ^tMthe acid mine drainage of 2405; Sample II is corresponding to the 400 ppm Wingdales that feed intake, 100 ppm clorox, 2 ppm Metclear ^tM2405 and 50 ppm FeCl ₃acid mine drainage; With sample III corresponding to the 400 ppm Wingdales that feed intake, 100 ppm clorox, 2 ppm Metclear ^tM2405 and 100 ppm FeCl ₃acid mine drainage.Obtain that there are 400 ppm Wingdales, 100 ppm clorox, 2 ppm Metclear ^tM2405 and 50 ppm FeCl ₃inlet flow process reduce Fe, Al and Mn to lower than reverse osmosis feed water expect level.

In view of the above results, and consider that different acid mine drainages can have the metal ion of different levels, add preferred pretreatment compositions to cause having following treated inlet flow: alkali, such as lime, Wingdale or rhombspar, its amount is about 100-1000 ppm; Oxygenant, such as clorox, its amount is about 50-200 ppm; And Metclear ^tM2405, its amount is about 1-5 ppm.Its amount is the chitosan of about 20-200 ppm is also useful, but non-essential, if expect the concentration reducing Al, Mn and Fe in addition.Also FeCl can be added ₃to obtain having about 25-75 ppm FeCl ₃inlet flow.

Metclear ^tM2405 is at U.S. Patent number 5,658, and water-soluble, branching, the polymeric dithiocarbamates (DTC) that describe in 487, it is incorporated herein by reference.Be described in U.S. Patent number 5,658, water-soluble, branching, the Polydithiocarbamate salt of 487 have following formula:

Wherein R ¹be independently organic group or

Wherein R ⁴be organic group independently, and x=1-5; R ²be-H or-CS independently ₂r ⁵, R ⁵be H or positively charged ion independently; R ³for N or the organic group that is substituted; Z is N-R independently ², O or S; The summation of n be greater than 10 integer; With m be greater than 2 integer.

In a preferred example of such Polydithiocarbamate salt, R ¹for vinyl, the summation of n is greater than 10, m=3, R ³the R of=N, >50% ²for-CS ₂r ⁵, R ⁵for basic metal, Z is N-R ².

In a particularly preferred example of such Polydithiocarbamate salt, R ¹for vinyl, the summation of n is greater than 25, m=3, R ³the R of=N, >50% ²for-CS ₂r ⁵, R ⁵for basic metal, Z is N-R ².

In another particularly preferred example of such Polydithiocarbamate salt, R ¹for vinyl, the summation of n is greater than 25, m=3, R ³the R of=N, >79% ²for-CS ₂r ⁵, R ⁵for basic metal, Z is N-R ².

Metclear ^tM2405 is by making to gather [ethyleneimine] (PEI) and dithiocarbonic anhydride (CS ₂) react in the presence of a base and the DTC polymkeric substance prepared, wherein 80% CS ₂functionalized and molecular weight is about 170,000.

Polymkeric substance for improvement of heavy metals removal can be the anionic polymer using sulfur-bearing functional group, with precipitation of heavy metals.The example of such polymkeric substance comprises MetClear ^tM2405 and MetClear ^tM2410, developed by BetzDearborn Research and Development.The U.S. Patent number 5,658 that other exemplary polymer was submitted in November 1 nineteen ninety-five, discusses in 487.MetClear ^tM2405 preferential precipitation heavy metals, such as cadmium, chromium, copper, lead, mercury, nickel and zinc.It is effective precipitation of aluminium, cobalt, iron, magnesium, silver, tin and vanadium also.

Flocculation agent can be such as: anionic polymer, such as AP 1120 (deriving from GE Water & Process Technologies, the product of Trevose, PA); Cationic flocculants, such as CE2666; Based on the flocculation agent of Weibull; Based on the flocculation agent of chitosan; Or non-polymeric flocculation agent, such as FeCl ₃.Anionic polymer (such as AP 1120) can about 3 ppm concentration use.Cationic flocculants (such as CE2666) can about 3 ppm concentration use.

In order to make inlet flow 24 clarify, in concrete example, preferably use Wingdale (400 ppm), clorox (100 ppm), MetClear ^tMthe combination of 2405 (2 ppm) and polymeric coagulant (3 ppm).This preferably combines and can comprise FeCl in addition ₃(50 ppm).In this example, the pH of inlet flow is about 3.5.Use the preferably combination of this chemical agent to be favourable, because its permission removes at least iron, magnesium and aluminium in one step, otherwise it is difficult to remove, because these metals precipitate under different pH scopes.Such as, iron is about 3.5 times precipitations, and magnesium precipitates more than 10, and aluminium precipitates under about 6-9.Use one step, use preferred combination to reduce the level of the metal dissolved.

In other example, preferably use the combination of Wingdale (800 ppm) and hypochlorite (100 ppm).In other example, preferably use Wingdale (600 ppm), hypochlorite (100 ppm) and Metclear ^tM2405 (2 ppm).In other example, preferably use Wingdale (400 ppm), hypochlorite (100 ppm), Metclear ^tM2405 (2 ppm) and FeCl ₃(50 ppm).In other example, preferably use rhombspar (400 ppm), hypochlorite (100 ppm) and Metclear ^tM2405 (2 ppm).In other example, preferably use Wingdale (400 ppm), hypochlorite (100 ppm), Metclear ^tM2405 (2 ppm) and chitosan (100 ppm).In other example, preferably use white lime (also referred to as calcium hydroxide) (100 ppm), hypochlorite (100 ppm) and Metclear ^tM2405 (2 ppm).Use has about 20 ppm iron ions, 7 ppm magnesium ions and the aluminum ions coal mine drainage of 16 ppm, successfully tests these combinations.

After adding alkali and optional oxygenant, can preferably add flocculation agent, flocculation agent or the two.

Nanofiltration enriched material 21 from nano-filtration unit 19 can accept by pretreated unit 12, as the charging of settler 23, causes using lime 25 and other pretreatment chemical agent 26 to process nanofiltration enriched material 21.

Inlet flow 24 is clarified in settler 23, and to produce clarification stream 27, it can filter in ultra filtration unit 28.The pretreated liquid filtrate 29 obtained is accepted as first-class 13 by EDR unit 10.

Settler 23 also produces settler discharge stream 30, it comprise precipitation, flocculation and/or cohesion product.Settler discharge stream 30 is filtered by filter unit 31, to form the filtering emission stream 32 and filtrate flow 33 that comprise solids class.Filtrate flow 33 can be recycled to settler 23, cause using lime 25 and other pretreatment chemical agent 26 to process filtrate flow 33.Depend on the chemical constitution of raw material, solids class can comprise Fe, Mn, Al, Ca, Mg and/or their SO of solid or dissolving ₄or CO ₃salt.

Pre-treatment can be used as dual stage process operation.In dual stage process, add process chemical agent with the dosage expected in two steps.Such as, the Metclear of the Wingdale of 50 ppm, the clorox of 50 ppm and 2 ppm is added in the first phase ^tM2405, in subordinate phase, add 350 ppm Wingdales and 50 ppm clorox.With add in the single stage contrary, add in two stages process chemical agent cause more alkaline preprocessing process, it can contribute to precipitating such as Al, Mn and Fe salt.Dual stage process allows to use less lime, to produce identical process water quality.

nanofiltration.Nano-filtration unit 19 comprises nanofiltration membrane element, and it can repel multivalent anions, and depends on that shape and size repel positively charged ion.The nanofiltration membrane that can be used for filtering system of the present disclosure can repel the divalent ion of nearly 90% (such as repelling the sulfate radical of 99%, calcium and magnesium), allow the monovalent ion of at least 50% (such as to reach the sodium of 50-80% simultaneously, potassium and muriate) by film, thus the dirt reducing nanofiltration membrane downstream is formed.

In concrete example, compared with reverse osmosis membrane, preferred nanofiltration membrane, can repel polyvalent ion due to nanofiltration membrane and in permeate stream, pass through monovalent ion simultaneously.This causes improving a little and reducing and recirculation can being back to the salinity of the nanofiltration concentration logistics 21 for the treatment of system, to improve Water Sproading rate of product water salinity.

Nanofiltration membrane known in the art can be used.In concrete example, preferably have at least 90% polyvalent ion rate of rejection and at the most 50% the film of monovalent ion rate of rejection.

For uncharged organic molecule, exemplary film element can have the daltonian molecular weight of about 150-about 300 and retain.Input concentration and composition will be depended on by such membrane element repulsion divalence and polyvalent ion.Exemplary nanofiltration membrane element at about 70-about 300 psi, or even can operate up under about 600 psi.Nanofiltration membrane element can the throughput of about 10-about 20 gallons of/square feet of film/skies (GFD).Exemplary nanofiltration membrane element can operate under the pH of about 3.0-about 9.0.The specific examples of such nanofiltration membrane element comprises those that produced by model HL8040F-400 by GE Water & Process Technologies, and its useful area is about 37.2 m ², average permeate logistics capacity is about 43.5 m ³/ sky is (as use 2000 ppm MgSO ₄when testing under 100 psig); With press Seasoft ^tM8040 sell those.

The salt be present in brine feed stream can comprise charged ion, such as magnesium (Mg ²⁺), calcium (Ca ²⁺), sodium (Na ⁺), potassium (K ⁺), barium (Ba ²⁺), strontium (Sr ²⁺), chlorine (Cl ^-), sulfate radical (SO ₄ ^2-), and/or other ion.In some applications, first-class 13 and second 14 can comprise or identical salt or impurity can not be comprised, and can have or can not have salt or the impurity of same concentrations.In second 14, the concentration of salt or impurity can be saturated or oversaturated or can not be saturated or oversaturated.

example system.By a kind of exemplary system models of the present disclosure.Incoming flow in model represent total dissolved solidss (TDS) be about 3000 ppm and pH be about 3.5 acid mine drainage.Calcium and sulfate ion are rich in incoming flow, but sulfate radical is not substantially the same with the concentration of calcium ion.Sulfate concentration reaches more than the twice of calcium concn and even more than four times (respectively relative about 500 ppm of about 2400 ppm).Significant metal ion comprises iron, magnesium, aluminum and zinc.Incoming flow uses the lime of 100 ppm, the clorox of 100 ppm, the MetClear of 5 ppm ^tM2405 and the flocculation agent of q.s and the mixture pre-treatment of flocculation agent.Second output stream 16 also uses pretreatment chemical agent process.

The explanation of the system of display model in figure 6, display fluid and efflux of solids.The parts of this exemplary desalination system interact as discussed above.This system comprises pretreatment unit 12, EDR unit 10, precipitation unit 11 and nano-filtration unit 19.First output stream 15 uses nano-filtration unit 19 to process, and nanofiltration enriched material 21 is recycled to pretreatment unit 12.Feed intake lime in the reactor of precipitation unit 11.Dotted line around in product stream project through desalination system produce product.Modeled system comprises ultra filtration unit 34, to filter second 14; With filter unit 35, with filtering-depositing discharge stream 17.Filter unit 35 is by from the solid of system discharge and the liquid separation mixed with a part for second 14 in mixing tank 36.The liquid of mixing is back to settler 23 via settler recirculation flow 37 recirculation.The liquid that a part mixes is flowed 18 from system discharge as " blowdown ".The second 14 acid (such as sulfuric acid) being joined clarification stream 27 and discharge from ultra filtration unit 34.Add the fouling that acid reduces pH and is reduced in the filtering membrane of EDR unit 10.

Precipitation unit 11 in modeling system is the settler of display in U.S. Patent Application Publication No. US 2011/0114567 and illustrates in figure 3.

Mathematical model causes following fluidity matter:

	Input charging 24	Purified discharge stream 22	Repel stream 18
				Flow (m 3/hr)	1250	1246.25	3.75
Calcium (ppm)	512	31	434
				Magnesium (ppm)	239	14.2	88.1
Sodium (ppm)	65.9	73.4	4459
				Potassium (ppm)	14.6	13.2	494.5
Sulfate radical (ppm)	2403	231	10201
				Muriate (ppm)	22	51.6	842.2
Total dissolved solidss (ppm)	3289	420	16838

By the mathematical model of example system with there is no pre-treatment brine feed stream, compared with the mathematical model that do not have pretreating raw material, do not have chemical agent to join settling vessel and do not have a system of nanofiltration.This model uses identical initial parameters, and the process calculating raw material causes following fluidity matter:

Relatively obvious by between two kinds of mathematical models, example system provides the rate of recovery improved for this poor calcium feed water and the sulfate concentration reduced in product water.The present inventor believes, it is beneficial that uses desalination system, and described system comprises following one or more: (a) such as uses lime, the clorox of about 100 ppm, the MetClear of about 5 ppm of about 100 ppm ^tM2405 and the flocculation agent of q.s and/or the mixture pre-treatment of flocculation agent, (b) feeds intake lime and (c) nano-filtration unit 19 in settling vessel, when desalination system for the treatment of sulfate radical with the incoming flow that calcium ion is substantially not identical time.Other mixture of pretreatment chemical agent as discussed in this article also can provide the removal of the expectation of sulfate radical, calcium and metal ion.Although use example system lime consumption to improve, for total operation expense, the raising of the rate of recovery incessantly compensates these lime consumptions and improves.In addition, lime consumption and solids yield are less than the three stage RO methods arranged for obtaining the similar rate of recovery.

for the treatment of the composition of waste water.According to another aspect of the present disclosure, provide a kind of composition for the treatment of waste water, the waste water such as produced by mining (such as acid mine drainage), mineral processing and Metal Production.These waste water contain calcium and the sulfate radical of elevated levels, and the level of metal ion (such as Fe, Mn, Al, Mg, Cu and/or Zn), make waste water undesirably be directly used in desalination unit.These waste water are usually containing the sulfate concentration more than calcium concn twice.

Expect, by process under existing without other treatment step, there is the waste water of certain chemical constitution, reduce the concentration of Fe, Al and Mn to desalination unit (such as reverse osmosis units, nano-filtration unit or electrodialysis reversal unit) acceptable level.Adopt process waste water in such a way waste water is separated into by permission: the effluent with Fe, Al and Mn level below for the aimed concn of desalination unit, and sludge.Effluent can process in desalination unit without further treatment step.

Composition of the present disclosure can be used for being reduced in the concentration of Fe, Al and Mn in inlet flow.Preferred composition can be used for the concentration of reduction acid mine drainage extremely lower than the aimed concn (100 ppb Fe, 100 ppb Al and 50 ppb Mn) for reverse osmosis feed water.

Composition comprises: alkali and oxygenant.Alkali preferably adds with the dosage of about 50-about 1000 ppm.Oxygenant preferably adds with the dosage of about 50-about 200 ppm.Composition also can comprise the anionic polymer containing the sulfur-bearing functional group for making heavy metal precipitation.Composition also can comprise flocculation agent.

Composition can comprise the chemical agent that one or more have several functions.Such as, FeCl ₃can be used as flocculation agent, pH control agent, for the metal that dissolves and metalloid precipitated catalyst, or their any combination.

Alkali can be: lime, magnesium calcium carbonate (rhombspar), caustic soda (sodium hydroxide), or their any combination.Oxygenant can be: clorox, chlorine, ClO ₂, KMnO ₄, hydrogen peroxide, or their any combination.The anionic polymer comprising the sulfur-bearing functional group for making heavy metal precipitation can be: MetClear ^tM2405.Flocculation agent can comprise: polymeric coagulant.Lime can be: unslaked lime (calcium oxide), white lime (calcium hydroxide) or Wingdale (calcium carbonate).

In concrete example, described alkali is: Wingdale; Described oxygenant is: clorox; Comprise for making the anionic polymer of the sulfur-bearing functional group of heavy metal precipitation be: MetClear ^tM2405; Flocculation agent is: polymeric coagulant and FeCl ₃combination.

In the preferred composition of one, in waste water, add Wingdale with the amount at least about 800 ppm.In waste water, clorox is added with the amount at least about 100 ppm.

In another preferred composition, in waste water, add Wingdale with the amount at least about 600 ppm.In waste water, clorox is added with the amount at least about 100 ppm.In waste water, MetClear is added with the amount at least about 2 ppm ^tM2405.

In the preferred composition of one, in waste water, add Wingdale with the amount at least about 400 ppm.In waste water, clorox is added with the amount at least about 50 ppm.In waste water, MetClear is added with the amount at least about 2 ppm ^tM2405.In waste water, FeCl is added with the amount of about 50 ppm ₃.In preferred composition, polymeric coagulant can be added at least about the amount of 1 ppm in waste water.

In other example, preferably use rhombspar (400 ppm), hypochlorite (100 ppm) and Metclear ^tM2405 (2 ppm).In other example, preferably use Wingdale (400 ppm), hypochlorite (100 ppm), Metclear ^tM2405 (2 ppm) and chitosan (100 ppm).In other example, preferably use white lime (also referred to as calcium hydroxide) (100 ppm), hypochlorite (100 ppm) and Metclear ^tM2405 (2 ppm).

Discuss about Fig. 4,5A, 5B and 5C as above, use has about 20 ppm iron ions, 7 ppm magnesium ions and the aluminum ions coal mine drainage of 16 ppm and successfully tests these combinations.

This preferred composition is particularly advantageous for processing the waste water comprising iron, magnesium and aluminium, because its permission removes at least iron, magnesium and aluminium in one step, otherwise it is difficult to remove, because these metals precipitate under different pH scopes.Such as, iron is about 3.5 times precipitations, and magnesium precipitates more than 10, and aluminium precipitates under about 6-9.Use one step, use preferred combination to reduce the level of the metal dissolved.As previously mentioned, concentration can be comprised up to the iron of several thousand ppm, magnesium and aluminium from mining, mineral processing and the waste water of Metal Production industry.

desalting method.On the other hand, the disclosure provides a kind of desalting method.Desalting method of the present disclosure illustrates in the figure 7.Described method comprises: make incoming flow and the agent of at least one pretreatment chemical by pretreatment unit 64, for generation of the discharge stream of the first-class of ion-reduction and ion-concentrated; Make first-class by electrodialysis reversal unit 65, for desalination; With make second via precipitation unit 66 by electrodialysis reversal unit, to take away the ion from first-class removing.

The agent of at least one pretreatment chemical can comprise lime, such as unslaked lime, white lime or Wingdale.The agent of at least one pretreatment chemical can comprise Wingdale, clorox, MetClear ^tM2405, FeCl ₃and polymeric coagulant.

Described method also can comprise makes the first output stream lead to nano-filtration unit or reverse osmosis units 67 from electrodialysis reversal unit.Described method also can comprise makes concentration logistics lead to pretreatment unit 68 from nano-filtration unit,

Incoming flow and the agent of at least one pretreatment chemical can be comprised (as illustrated in fig. 8): make incoming flow by settler 69 by pretreatment unit, to produce the discharge stream of clarification stream and clarification; Settler 70 is circulated to by filter unit with by filtrate flow with making the discharge stream of clarification.Incoming flow and the agent of at least one pretreatment chemical also can be comprised: clarification is circulated to ultra filtration unit 71, to produce pretreated liquid filtrate by pretreatment unit.

In the foregoing written description, for illustrative purposes, many details are stated, to provide fully understanding example.But, it will be apparent to one skilled in the art that and do not need these concrete details.Above-mentioned example is intended to be only exemplary.When not departing from the scope be only defined by the following claims, those skilled in the art can modify to concrete example, change and change.

Claims (10)

1. a desalination system, described system comprises:

Desalination unit, its arrange for accept first-class for desalination and second to take away the ion from described first-class removing;

Precipitation unit, it is communicated with described desalination unit fluid and arranges and is used for described second is circulated between which;

With following one of at least:

A () pretreatment unit in the upstream of described desalination unit and arranging is used for:

Accept incoming flow and the agent of at least one pretreatment chemical, and

Produce ion-reduction first-class for desalination in described desalination unit, the discharge stream of and ion-concentrated;

B () described desalination system arranges and is used for adding lime in described precipitation unit or in the second through described precipitation unit; With

C (), based on the purification devices of film, it is arranged for accepting the desalination output stream from described desalination unit.

2. the desalination system of claim 1, wherein said desalination unit is electrodialysis reversal unit.

3. the desalination system of claim 1 or 2, wherein said precipitation unit comprises the settler with precipitation zone and solid-liquid separation region.

4. the desalination system of claim 3, wherein said precipitation unit provides described second from the top in described solid-liquid separation region.

5. the desalination system any one of claim 1-4, wherein said desalination system makes waste water desalination, and described waste water comprises acid mine drainage, but or is rich in the half that sulfate ion calcium concn is less than sulfate concentration.

6. the desalination system any one of claim 1-5, wherein said desalination system comprises pretreatment unit in the upstream of described desalination unit.

7. the desalination system of claim 6, the agent of wherein said at least one pretreatment chemical comprises alkali.

8. the desalination system of claim 7, wherein said alkali is unslaked lime, white lime, Wingdale or rhombspar, and it adds and obtains about 50-about 1000 ppm alkali.

9. the desalination system of claim 7 or 8, the agent of wherein said at least one pretreatment chemical comprises oxygenant.

10. the desalination system of claim 9, wherein said oxygenant is clorox, and it adds and obtains about 50-about 200 ppm clorox.