CN111704259A

CN111704259A - Method and system for filtering and combined weight removal treatment of wastewater

Info

Publication number: CN111704259A
Application number: CN202010268851.XA
Authority: CN
Inventors: 何志; 许锦鹏; 何劲松; 谭博文; 杨光耀; 赵聪
Original assignee: Chengdu Stareng Environmental Protection Equipment Co ltd; Sichuan Scsdn Technology Co ltd
Current assignee: Chengdu Stareng Environmental Protection Equipment Co ltd; Sichuan Scsdn Technology Co ltd
Priority date: 2020-04-08
Filing date: 2020-04-08
Publication date: 2020-09-25

Abstract

The invention relates to sewage treatment, in particular to a method and a system for filtering and combining weight removal treatment of wastewater, wherein the method comprises the following steps: a first filtration treatment, wherein the wastewater is subjected to filtration treatment by using microfiltration equipment, so that first wastewater and first concentrated water are obtained; performing second filtration treatment, namely performing filtration treatment on the first wastewater by using ultrafiltration equipment to obtain second wastewater and second concentrated water; performing third filtration treatment, namely performing filtration treatment on the second wastewater by using nanofiltration equipment to obtain third wastewater and third concentrated water; performing fourth filtration treatment, namely performing filtration treatment on the third wastewater by using reverse osmosis equipment to obtain fourth wastewater and fourth concentrated water; and at least performing weight removal treatment on the third concentrated water and the fourth concentrated water respectively aiming at the first concentrated water/slurry, the second concentrated water, the third concentrated water and the fourth concentrated water. Through the multi-stage treatment and the combination of at least the third concentrated water and the fourth concentrated water, the weight removal treatment is respectively carried out, so that the overall recovery rate of the wastewater can reach more than 30-70%.

Description

Method and system for filtering and combined weight removal treatment of wastewater

Technical Field

The invention relates to sewage treatment, in particular to a method and a system for filtering and combining weight removal treatment on wastewater.

Background

In nickel smelting, the laterite-nickel ore is smelted by a pyrogenic process or a wet process, taking the wet process as an example, the ore is sequentially leached, deironing, neutralized and precipitated, ammonia leaching, extraction, back extraction and nickel sulfate solution is obtained in the wet process, and the emission reduction of high-salinity wastewater such as the nickel sulfate solution is an important step in environmental protection. After the impurities of the nickel solution are removed, the nickel in the nickel solution needs to be precipitated, sodium carbonate is added into the precipitated nickel solution to generate nickel carbonate, and the generated nickel precipitation wastewater needs to be treated. At present, MVR evaporation and electrodialysis are generally adopted to treat the nickel precipitation wastewater, but the equipment used by an MVR evaporation system is high in height, high in temperature during operation and high in operation energy consumption, and the electrodialysis mode is low in desalination rate and cannot treat water with salt content more than 3000 mg/L.

Disclosure of Invention

The invention aims to provide a method for filtering and combining the weight removal treatment of wastewater with higher water reuse rate.

In order to achieve the purpose, the technical scheme adopted by the application is a method for filtering and combining weight removal treatment on wastewater, which comprises the following steps:

a first filtration treatment, wherein the wastewater is subjected to filtration treatment by using a microfiltration device, so that first wastewater and first concentrated water/slurry are obtained;

performing second filtration treatment, namely performing filtration treatment on the first wastewater by using ultrafiltration equipment to obtain second wastewater and second concentrated water;

performing third filtration treatment, namely performing filtration treatment on the second wastewater by using nanofiltration equipment to obtain third wastewater and third concentrated water;

performing fourth filtration treatment, namely performing filtration treatment on the third wastewater by using reverse osmosis equipment to obtain fourth wastewater and fourth concentrated water;

wherein the content of the first and second substances,

at least respectively carrying out weight removal treatment on the third concentrated water and the fourth concentrated water aiming at the first concentrated water/slurry, the second concentrated water, the third concentrated water and the fourth concentrated water; and filtering the concentrated water after weight removal by microfiltration equipment.

Through the multi-stage filtration treatment of microfiltration, ultrafiltration, nanofiltration and reverse osmosis and the combination of at least the weight removal treatment of the third concentrated water and the fourth concentrated water, the overall recovery rate of the wastewater can reach more than 30-70 percent. The recovery rate here is water before treatment/water after treatment × 100%.

And further returning the obtained second concentrated water to microfiltration equipment for filtration treatment.

Further, after the weight removal, any one or more of nickel, copper and cobalt in the combination continuously and stably reaches within 1mg/L after the weight removal of the discharged concentrated water by complexation, and the pH value is 6-9.

Further, when the second wastewater is subjected to a filtration treatment using a nanofiltration device, the wastewater is subjected to a filtration treatment at an operating pressure of 40-120 bar.

Further, the fourth filtering process includes employing:

the first-stage reverse osmosis equipment is used for filtering the third waste water to obtain first-stage fourth waste water and first-stage fourth concentrated water;

and the second-stage reverse osmosis equipment is used for filtering the first-stage fourth wastewater to obtain second-stage fourth wastewater and second-stage fourth concentrated water.

Further, the stable recovery rate of the first-stage reverse osmosis equipment system is more than or equal to 62 percent;

the stable recovery rate of the second-stage reverse osmosis equipment system is more than or equal to 30 percent.

And further, the fourth concentrated water of the second stage is returned to the reverse osmosis equipment of the first stage for treatment.

The invention also provides a system for filtering and combined de-weighting of wastewater with high desalination rate, high water reuse rate and low energy consumption, comprising:

the first microfiltration device is used for filtering the entering wastewater to obtain first wastewater and first concentrated water/slurry;

the ultrafiltration equipment is used for filtering the first wastewater to obtain second wastewater and second concentrated water;

the nanofiltration equipment is used for filtering the second wastewater to obtain third wastewater and third concentrated water;

the reverse osmosis equipment is used for treating the third wastewater to obtain fourth wastewater and fourth concentrated water;

the system for filtering and jointly removing the weight of the wastewater also comprises a weight removing device for removing the weight of at least the third concentrated water and the fourth concentrated water and adding a weight removing agent to carry out complex reaction on heavy metals such as nickel, cobalt and copper in the concentrated water; the output end of the weight removing device is connected with a second microfiltration device for filtering the concentrated water after weight removal.

Furthermore, the filter elements of the first microfiltration device and the second microfiltration device are both porous metal filter elements, and can be stainless steel filter elements. Thus, the solid-liquid two phases are separated by adopting a physical method, no chemical agent is required to be added, and no impurity is introduced; the porous material metal filter element is a rigid structure, and the pores of the porous material metal filter element are more uniform and more stable than those of a cloth bag filter and a sand filter tank, so that the filtering precision is high.

Furthermore, the sludge discharge channels of the first microfiltration device and the second microfiltration device are both connected with a recovery device.

Furthermore, the reverse osmosis equipment comprises a first-stage reverse osmosis equipment and a second-stage reverse osmosis equipment which are sequentially connected, wherein a channel for outputting the concentrated water of the second-stage reverse osmosis equipment is connected with an inlet of the first-stage reverse osmosis equipment, and a channel for outputting the concentrated water of the first-stage reverse osmosis equipment is connected with the weight removing equipment. .

And (4) after nanofiltration separation, the obtained product enters reverse osmosis equipment for cyclic concentration, and meanwhile, the produced water is purified through the next stage of reverse osmosis.

The first-stage reverse osmosis equipment is reverse osmosis equipment with a system stable recovery rate of more than or equal to 62%;

the second-stage reverse osmosis equipment is reverse osmosis equipment with a system stable recovery rate of more than or equal to 30%.

Further, a heat exchanger is arranged between the output end of the microfiltration device and the input end of the ultrafiltration device. The heat exchanger can adopt a heat exchange water pipe to exchange heat with a pipeline at the output end of the microfiltration equipment.

Further, the input end of the microfiltration device is connected with a supernatant liquid storage tank.

Furthermore, the input end of the supernatant liquid storage tank is connected with a concentrator for concentrating the wastewater.

Furthermore, the microfiltration equipment is connected with a back flushing equipment.

Furthermore, any one or any more output ends of the ultrafiltration equipment, the nanofiltration equipment and the reverse osmosis equipment are connected with a buffer water tank, and the buffer water tank is connected with any one or any more output ends of the ultrafiltration equipment, the nanofiltration equipment and the reverse osmosis equipment through a back-flushing water inlet pipeline.

The invention is further described with reference to the following figures and detailed description. Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description. Or may be learned by practice of the invention. .

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to assist in understanding the invention, and are included to explain the invention and their equivalents and not limit it unduly. In the drawings:

FIG. 1 is a schematic diagram illustrating one embodiment of the present system for filtering and combining wastewater for de-weighting;

FIG. 2 is a schematic diagram illustrating another embodiment of the present system for filtering and combining wastewater for de-weighting;

the labels in the figure are: the device comprises a supernatant liquid storage tank 1, a first precision filter 2, a heat exchanger 3, an ultrafiltration membrane filter 4, a nanofiltration membrane filter 5, a reverse osmosis membrane separation treatment device 6, a first reverse osmosis treatment system 6a, a second reverse osmosis treatment system 6b, a first heavy removal tank 7, a second heavy removal tank 8, a second precision filter 9, a third precision filter 10, a third heavy removal tank 11 and a pit 12.

Detailed Description

The invention will be described more fully hereinafter with reference to the accompanying drawings. Those skilled in the art will be able to implement the invention based on these teachings. Before the present invention is described in detail with reference to the accompanying drawings, it is to be noted that:

the technical solutions and features provided in the present invention in the respective sections including the following description may be combined with each other without conflict.

Moreover, the embodiments of the present invention described in the following description are generally only examples of a part of the present invention, and not all examples. Therefore, all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort shall fall within the protection scope of the present invention.

With respect to terms and units in the present invention. The term "comprises" and any variations thereof in the description and claims of this invention and the related sections are intended to cover non-exclusive inclusions.

A method for filtering and combining the heavy treatment of wastewater, the method has an overall recovery rate of the wastewater of more than 30-70%, and the method treats high-salinity wastewater such as nickel sulfate solution, and the method comprises the following operation steps:

wherein the content of the first and second substances,

and at least performing weight removal treatment on the third concentrated water and the fourth concentrated water respectively aiming at the first concentrated water/slurry, the second concentrated water, the third concentrated water and the fourth concentrated water.

The wastewater collected is subjected to complexing and weight removal treatment, the complexing and weight removal treatment comprises the steps of sequentially adopting complexing agent weight removal equipment and microfiltration equipment for filtration, and the microfiltration equipment is used for filtering the wastewater and removing fine suspended matters or colloidal particles, so that the turbidity after filtration is less than 5 NTU.

An ultrafiltration device is used to filter out particles, colloids or suspended substances with a molecular weight of > 500 and a particle diameter of > 10 nm.

Specifically, the micro-filtration equipment filters the wastewater to remove fine suspended matters or colloidal particles, so that the turbidity after filtration is less than 5NTU, and the micro-filtration equipment is used for removing the fine suspended matters or the colloidal particles. The microfiltration equipment adopts a porous metal filter element, for example, a stainless steel porous metal filter element and the like can be adopted.

And adding a heavy metal trapping agent into the concentrated water obtained by the treatment of the nanofiltration equipment for removing the weight, filtering the liquid after the weight removal by using microfiltration equipment, outputting, and recovering the obtained complex precipitate to be used as a raw material for recycling the front-end production process resources.

The nanofiltration equipment is used for processing, particles with the molecular weight of 150-500 and the particle size of 0.0005-0.005 mu m are filtered, the stable recovery rate of the nanofiltration membrane system is enabled to be more than or equal to 40%, heavy metal capture agents are added into concentrated water obtained through the nanofiltration equipment for removing the weight, liquid after the weight removal is filtered by the microfiltration equipment and then output, and the obtained complex precipitate is recovered and used as a raw material for recycling front-end production process resources. .

Specifically, the reverse osmosis equipment adopts a filtering system with the filtering molecular weight of 50-150 and the particle size of 0.0001-0.001 mu m, the reverse osmosis equipment is subjected to one-stage or multi-stage separation treatment, the stable recovery rate of the whole reverse osmosis system is more than or equal to 45%, concentrated water obtained by the reverse osmosis equipment is added with a heavy metal trapping agent for complexing and removing the heavy metal, and the liquid after the heavy metal removal is filtered by a microfiltration equipment and then output, so that the discharged wastewater reaches the discharge standard of relevant requirements, and the produced water of the system can be directly recycled as reclaimed water or reaches the pure water standard.

Univalent ions and multivalent ions in the raw water are separated, and the subsequent sections are respectively treated, so that the treatment efficiency is improved.

Thus, the solid-liquid two phases are separated by adopting a physical method, no chemical agent is required to be added, and no impurity is introduced; the porous material metal filter element is a rigid structure, and the pores of the porous material metal filter element are more uniform and more stable than those of a cloth bag filter and a sand filter tank, so that the filtering precision is high.

Referring to fig. 1, the specific operation employs a system for filtration treatment and combined de-weighting treatment of wastewater comprising:

the microfiltration equipment 2 is used for filtering the entering wastewater and enabling the turbidity of the filtered wastewater to be less than 5 NTU;

the post-filtration separation group is connected with the microfiltration equipment and mainly comprises a plurality of filtration equipment which are connected in series;

the weight removing equipment is used for collecting concentrated water generated by filtering of the post-positioned filtering separation group, and adding a weight removing agent to carry out complex reaction with the concentrated water;

and the second micro-filtration equipment is used for filtering the wastewater after weight removal and outputting the filtered wastewater.

The post-filtration separation group comprises an ultrafiltration device 4, a nanofiltration device 5 and a reverse osmosis device 6 which are connected in series;

and one or more concentrated water discharge channels of the ultrafiltration equipment 4, the nanofiltration equipment 5 and the reverse osmosis equipment 6 are connected with the weight removal equipment.

Firstly, filtering the wastewater, enabling the turbidity after filtering to be less than 1NTU by adopting modes such as an ultrafiltration membrane and the like, then carrying out treatment by a 40-120bar pressure nanofiltration device, then carrying out reverse osmosis device, removing the weight of the wastewater, namely, reducing the content of nickel, cobalt and copper in the wastewater by adding a heavy metal trapping agent, enabling the combination of any one or more of nickel, copper and cobalt to be continuously and stably within 1mg/l, enabling the pH to be 6-9, and finally filtering again by adopting a microfiltration device and outputting, so that the overall recovery rate of the wastewater can be more than 30-70%.

Ultrafiltration (UF) employed by the ultrafiltration unit 4 is a technique for removing impurities from a liquid by mechanical sieving principles, which has a highly efficient and stable retention of suspended matter, colloids, bacteria and microorganisms, and is a fluid tangential flow and pressure driven filtration process and separates particles by molecular weight. The pore diameter of the ultrafiltration membrane is approximately in the range of 0.002-0.1 μm. Dissolved substances and substances with a pore size smaller than that of the membrane permeate the membrane as permeate, and substances which do not permeate the membrane are slowly concentrated in the effluent. The produced water (permeate) will therefore contain water, ions and small molecular weight substances, while colloidal substances, particles, bacteria, viruses and protozoa will remove the envelope. The rejection rate of the ultrafiltration membrane treatment equipment to escherichia coli is 99.99%, the rejection rate of SS is 55-99.99%, and the rejection rate of COD is 20-60% (considering the molecular weight). Ensure that the SDI of the effluent is less than 3(100 percent of time) and the turbidity of the effluent is less than 0.1 NTU.

UF is a membrane process that utilizes the "sieving" action of the membrane for separation. Under the action of static pressure difference, particles smaller than the membrane pores pass through the membrane, particles larger than the membrane pores are blocked on the surface of the membrane, particles with different sizes are separated, the filtration precision is higher than that of MF, the membrane pores are smaller, and the actual operating pressure is slightly higher than that of MF and is generally 0.1-0.5 MPa.

UF separates mainly macromolecular substances (proteins, nucleic acid polymers, starches, natural gums, enzymes, etc.), colloidal dispersions (clays, pigments, minerals, emulsion particles, microorganisms) and emulsions (greases, detergents, oil-water emulsions) from liquid-phase substances. The method of combining with proper macromolecule can separate metal ion, soluble solute and macromolecule from the water solution to reach the aim of purification and concentration.

The nanofiltration membrane is between reverse osmosis and ultrafiltration. The reverse osmosis membrane has pores smaller than 1nm, and other inorganic salts except water are difficult to permeate; the pore diameter of the ultrafiltration membrane is 10-100nm, and inorganic salt can permeate the ultrafiltration membrane. The aperture of the nanofiltration membrane applied to denitration is close to that of a reverse osmosis membrane, and the membrane has higher rejection rate on 2-valent compounds such as sodium sulfate and the like after special treatment.

The nanofiltration membrane has selective interception performance on ions, such as high interception rate of 90-99% on multivalent ions or negative ions and low interception rate of 0-55% on monovalent ions. The pretreated brine enters membrane equipment after being subjected to pressure increase by a high-pressure pump. Under high pressure, most sulfate ions are intercepted, chloride ions and sodium ions smoothly pass through the membrane, monovalent sodium ions and chloride ions with a valence of-1 are separated from sulfate radicals with a valence of-2, and a penetrating fluid containing a small amount of sulfate radicals and a concentrated solution containing more sulfate ions are obtained.

The membrane aperture of the nanofiltration membrane in the embodiment is 0.5-1.0nm, 1-valent ions (sodium ions and chloride ions) are allowed to pass through, and the nanofiltration membrane has a good interception effect on-2-valent sulfate radicals. The material is chosen from amides with aromatic structure, which allows higher operating pressures. The excellent structure of the nanofiltration membrane ensures that the repulsive force to sulfate radicals is very stable, and the stability of operation is ensured.

And sludge discharge channels of the microfiltration equipment 2 and the second microfiltration equipment 9 are both connected with recovery equipment. The recovery apparatus here may be an excavated pit 12.

The reverse osmosis equipment 6 comprises a first-stage reverse osmosis equipment and a second-stage reverse osmosis equipment which are sequentially connected, wherein the second-stage reverse osmosis equipment is used for outputting a channel of concentrated water and is connected with an inlet of the first-stage reverse osmosis equipment, and the first-stage reverse osmosis equipment is used for outputting a channel of the concentrated water and is connected with the weight removing equipment. The solution after nanofiltration separation enters reverse osmosis equipment for cyclic concentration, and simultaneously, the produced water is purified by the next stage of reverse osmosis.

A heat exchanger 3 between the output of the microfiltration device 2 and the input of the ultrafiltration device 4. The heat exchanger 3 can adopt a heat exchange water pipe to exchange heat with a pipeline at the output end of the microfiltration device 2. The input end of the microfiltration device 2 is connected with a supernatant liquid storage tank 1.

The input end of the supernatant liquid storage tank 1 is connected with a concentrator for concentrating the wastewater.

The microfiltration equipment 2 is connected with a back flushing equipment. The output end of any one or more of the ultrafiltration device 4, the nanofiltration device 5 and the reverse osmosis device 6 is connected with a buffer water tank, and the buffer water tank is connected with the output end of any one or more of the ultrafiltration device 4, the nanofiltration device 5 and the reverse osmosis device 6 through a back flush water inlet pipeline.

One specific process comprises the following steps (the following adopted UF system is ultrafiltration equipment, SNF system is nanofiltration equipment, SRO system is first-stage reverse osmosis equipment, and RO is second-stage reverse osmosis equipment):

the wastewater output by the concentrator is conveyed to a supernatant liquid storage tank 1, the supernatant liquid storage tank 1 conveys the wastewater to a microfiltration device 2 for filtration, the liquid filtered by the microfiltration device 2 is conveyed to a UF system, namely an ultrafiltration device 4 for filtration after heat exchange by a heat exchanger 3, the generated concentrated water is conveyed to the supernatant liquid storage tank 1 again, and the steps are carried out again.

Conveying the water produced after filtering by the UF system to an SNF system, namely a nanofiltration membrane system, filtering, conveying the concentrated water produced by the SNF system to a first weight removal device 7, adding a weight removal agent to remove weight, and conveying the liquid after weight removal to a second microfiltration device 9 for filtering; the produced water of the SNF system is conveyed to an SRO system, namely a first-stage reverse osmosis device 6a (a first-stage reverse osmosis device) for treatment, concentrated water generated by the SRO system (which can be a roll reverse osmosis membrane) is conveyed to a second weight removing device 8, a weight removing agent is added for weight removal, and the liquid after weight removal is conveyed to a second microfiltration device 9 (a separate third microfiltration device 10 can be additionally arranged) for filtration; the produced water of the SRO system is conveyed to an RO system (which can be a roll type reverse osmosis membrane), namely a second-stage reverse osmosis device 6b for treatment, the concentrated water generated by the RO system is conveyed to the SRO system for treatment, and the RO system outputs the produced water. The second microfiltration device 9 or the third filter can convey the filtered liquid to a waste water plant or other treatment facilities for treatment. The microfiltration device 2, the second microfiltration device 9 or the third filter described above are provided with a sludge discharge channel leading to the pit 12. The one piece of the weight removing equipment is a buffer water tank, the buffer water tanks are arranged at the conveying ends of the ultrafiltration equipment 4, the nanofiltration equipment 5 and the reverse osmosis equipment 6, and the buffer water tanks at the conveying ends of the nanofiltration equipment 5 and the reverse osmosis equipment 6 can be used as the weight removing equipment.

Referring to fig. 2, in addition to the above-mentioned process steps, there is another embodiment, different from the above-mentioned embodiment, a third weight-removing device 11 is also provided between the supernatant fluid storage tank 1 and the microfiltration device 2, and the concentrated water generated by the UF system is delivered to the third weight-removing device 11, so that the concentrated water enters the weight-removing link, and the weight removal through two processes is more reliable.

The micro-filtration equipment filters the wastewater by adopting the micro-filtration equipment, is used for removing fine suspended matters or colloidal particles, ensures that the turbidity after filtration is less than 5NTU, and is used for removing the fine suspended matters or the colloidal particles. The microfiltration equipment is a porous material metal filter element. The porous material metal filter element is a rigid structure, and the pores of the porous material metal filter element are more uniform and more stable than those of a cloth bag filter and a sand filter tank, so that the filtering precision is high.

And (3) carrying out nanofiltration equipment treatment to ensure that the stable recovery rate of a nanofiltration membrane system is more than or equal to 40%, adding a heavy metal trapping agent into the concentrated water obtained by the nanofiltration equipment treatment to remove the weight, and outputting the liquid after the weight removal after the microfiltration equipment is adopted for filtration.

And (3) performing reverse osmosis equipment to ensure that the stable recovery rate of the system is more than or equal to 45%, adding a heavy metal trapping agent into the concentrated water obtained by the treatment of the nanofiltration equipment to remove the weight, and filtering the liquid after the weight removal by using microfiltration equipment and then outputting the liquid.

In this embodiment, the water quality of each process stage is estimated as follows:

the first, second and third microfiltration devices can stably produce water with turbidity less than 5NTU, and during cleaning, after the dosage cleaning, the flux of the filter element can recover more than 98%, so that the surface cleaning effect is good, and the flux attenuation of the filter element is low. During the test time, the continuously operated apparatus body did not show severe corrosion.

The above UF system, i.e. ultrafiltration unit, produced water turbidity < 1 NTU. After the dosage is cleaned, the flux of the membrane element can be recovered by more than 98 percent, which shows that the cleaning effect is good. During the test time, the continuously operated apparatus body did not show severe corrosion.

The stable recovery rate of the SNF system nanofiltration equipment processor is more than or equal to 72 percent. In the continuous operation test process, the cleaning period is more than or equal to 1 month. After the dosage is cleaned, the flux of the membrane element can be recovered to 98% of the new membrane under the same water quality, which indicates that the cleaning effect is good. In the attenuation rate test of the membrane element, a raw water test is carried out after pilot plant test continuous operation, and the interception rate of the system to various ions under the same operation pressure and the same water inlet quality is tested. The change of the interception rate of ions in water is in a reasonable range (the interception rate of each ion is attenuated by less than 5 percent before and after the experiment), and the membrane element is polluted by sewage. In the test time, the main pumps, valves, instruments and the like of the continuous operation equipment are not seriously corroded.

The stable recovery rate of the SRO system, namely the first-stage reverse osmosis equipment is more than or equal to 45 percent. In the continuous operation test process, the cleaning period is more than or equal to 1 month. After the dosage is cleaned, the flux of the membrane element can be recovered to 98% of the new membrane under the same water quality, which shows that the cleaning effect is good. The decay rate of the membrane element was tested. And (3) carrying out a raw water test after pilot plant test continuous operation, and testing the interception rate of the system on various ions under the same operation pressure and the same water inlet quality. The change of the interception rate of ions in water is in a reasonable range (the interception rate of each ion is attenuated by less than 5 percent before and after the experiment), and the membrane element is polluted by sewage. In the test time, the main pumps, valves, instruments and the like of the continuous operation equipment are not seriously corroded.

The contents of the present invention have been explained above. Those skilled in the art will be able to implement the invention based on these teachings. All other embodiments, which can be derived by a person skilled in the art from the above description without inventive step, shall fall within the scope of protection of the present invention.

Claims

1. A method for filtering and combined de-weighting of wastewater, comprising:

wherein the content of the first and second substances,

2. The method for filtering and combining wastewater with de-weighting according to claim 1, wherein the second concentrated water obtained is returned to a microfiltration device for filtering.

3. The method of claim 1 for filtering and combined removal of weight from wastewater wherein the removal of weight is followed by the continuous stabilization of any one or more of nickel, copper, and cobalt in the combination of the discharged concentrate after complex removal of weight to within 1mg/L at a pH of 6-9.

4. The method for the filtration treatment and combined de-weighting treatment of wastewater as claimed in claim 1, wherein the second wastewater is subjected to a filtration treatment using a nanofiltration device, the wastewater being subjected to a filtration treatment at an operating pressure of 40-120 bar.

5. A method for the filtration treatment and combined de-weighting treatment of wastewater according to claim 1, characterized in that said fourth filtration treatment comprises the use of:

6. The method for the filtration treatment and combined de-weighting treatment of wastewater as claimed in claim 5,

the stable recovery rate of the first-stage reverse osmosis equipment system is more than or equal to 62 percent;

7. The method for the filtration treatment and combined de-weighting treatment of wastewater as claimed in claim 5,

and returning the fourth concentrated water of the second stage to the reverse osmosis equipment of the first stage for treatment.

8. A system for filtering and combining wastewater for de-weighting, comprising:

the system for filtering and jointly removing the weight of the wastewater also comprises a weight removing device for removing the weight of at least the third concentrated water and the fourth concentrated water and adding a weight removing agent to carry out complex reaction on heavy metals such as nickel, cobalt and copper in the concentrated water;

the output end of the weight removing device is connected with a second microfiltration device for filtering the concentrated water after weight removal.

9. The system for filtering and combining wastewater with a de-weighting treatment according to claim 8, wherein the filter elements of the first and second microfiltration apparatuses are metal porous material filter elements.

10. The system for filter treatment and combined de-weighting of wastewater as claimed in claim 8, wherein the reverse osmosis unit includes a first reverse osmosis unit and a second reverse osmosis unit connected in series, the second reverse osmosis unit having a passage for delivery of concentrate connected to an inlet of the first reverse osmosis unit, the first reverse osmosis unit having a passage for delivery of concentrate connected to the de-weighting unit.