CN104071925A - A zero-discharge treatment system and method for nickel-plating wastewater in a steel workshop - Google Patents

Abstract

The invention belongs to the technical field of sewage treatment systems, and particularly relates to a zero-emission treatment system for nickel plating wastewater in a steel workshop. Compared with the prior art, the method can ensure that the wastewater discharged from the steel workshop reaches the zero discharge standard so as to avoid the harm to the environment and the human health and ensure that the nickel plating wastewater in the steel workshop can be effectively recycled. The invention also discloses a method for carrying out zero discharge treatment on the nickel plating wastewater in the steel workshop by using the system.

Description

A zero-discharge treatment system and method for nickel-plating wastewater in a steel workshop

technical field

The invention belongs to the technical field of sewage treatment systems, and in particular relates to a zero-discharge treatment system and method for nickel-plating wastewater in iron and steel workshops.

Background technique

The process of nickel plating on the steel surface mainly includes three steps. One is the pretreatment process, which is mainly used to clean and activate the metal surface. It is commonly used in brighteners, complexing agents and corrosion inhibitors, etc.; The electroplating solution in the electroplating solution is mainly composed of main salt, complexing agent, conductive salt, buffer, anode activator and additives, among which the main salt is generally nickel sulfate; the third is the post-treatment process, which mainly includes cleaning and drying. In the whole production process, the workpieces in the pretreatment stage and after nickel plating need to be rinsed with water, thus forming nickel plating wastewater.

Nickel in nickel-plating wastewater is a carcinogen. If the nickel-plating wastewater is discharged without treatment, it will not only cause waste of resources, but also cause serious harm to the environment and human health.

In addition, water is an increasingly scarce resource. If the nickel-plating wastewater in steel workshops can be treated with zero discharge so that it can be recycled and reused, it will undoubtedly make a certain contribution to the cause of environmental protection.

In view of this, it is necessary to provide a zero-discharge treatment system and method for nickel-plating waste water in steel workshops, so that the nickel-plating wastewater discharged from steel workshops can reach zero discharge standards, so as to avoid harm to the environment and human health, and The nickel-plating waste water in the iron and steel workshop can be effectively recycled. the

Contents of the invention

One of the purposes of the present invention is to provide a zero-discharge treatment system for nickel-plating waste water in iron and steel workshops, so that the nickel-plating waste water discharged from iron and steel workshops can reach the zero-discharge standard to avoid environmental pollution. and human health, and enables the nickel-plating wastewater in steel workshops to be effectively recycled. the

In order to achieve the above object, the present invention adopts the following technical solutions:

A zero-discharge treatment system for nickel-plating wastewater in a steel workshop, including a collection aeration water tank, a reaction aeration water tank, a concentrated water tank, a tubular membrane filtration system, an activated carbon filter, a callback aeration water tank, a security filter, and a first-stage RO system, concentrated water tank, secondary RO system, fresh water tank, outlet pump and plate-and-frame filter press, the outlet of the collection aeration water tank is connected to the inlet of the reaction aeration water tank, and the outlet of the reaction aeration water tank is connected to the The waste water inlet of the concentrated water tank is connected, the liquid outlet of the concentrated water tank is connected with the inlet of the tubular membrane filtration system, the solid outlet of the concentrated water tank is connected with the inlet of the plate and frame filter press, and the plate The filtrate outlet of the frame filter press is connected to the inlet of the collecting aeration water tank, the produced water outlet of the tubular membrane filtration system is connected to the activated carbon filter, and the concentrated water outlet of the tubular membrane filtration system is connected to the The concentrated water inlet of the concentrated water tank is connected, the outlet of the activated carbon filter is connected with the inlet of the callback aeration water tank, the outlet of the callback aeration water tank is connected with the inlet of the security filter, and the security filter The outlet of the first-stage RO system is connected to the inlet of the first-stage RO system through a primary high-pressure pump, the concentrated water outlet of the primary RO system is connected to the inlet of the concentrated water tank, and the outlet of the concentrated water tank is connected to the secondary high-pressure pump. The inlet of the secondary RO system is connected, the concentrated water outlet of the secondary RO system is connected to the inlet of the collection aeration water tank, the reaction aeration water tank is also connected with an alkali addition device, and the callback aeration water tank is also connected There is an acid adding device connected.

As an improvement of the zero-discharge treatment system for nickel-plating wastewater in iron and steel workshops in the present invention, the treatment system also includes a fresh water tank, and the water production outlet of the first-level RO system and the water production outlet of the second-level RO system are both Connect with the inlet of the fresh water tank.

As an improvement of the zero discharge treatment system for nickel-plating wastewater in iron and steel workshops of the present invention, a first lift pump is arranged between the collection aeration water tank and the reaction aeration water tank.

As an improvement of the zero-discharge treatment system for nickel-plating wastewater in iron and steel workshops of the present invention, a second lift pump is arranged between the wastewater inlet of the reaction aeration water tank and the concentrated water tank.

As an improvement of the zero-discharge treatment system for nickel-plating wastewater in iron and steel workshops of the present invention, a circulating pump is arranged between the liquid outlet of the concentrated water tank and the tubular membrane filtration system.

As an improvement of the zero-discharge treatment system for nickel-plating wastewater in iron and steel workshops of the present invention, a sludge filter press pump is arranged between the solid outlet of the concentrated water tank and the inlet of the plate and frame filter press.

As an improvement of the zero-discharge treatment system for nickel-plating wastewater in iron and steel workshops of the present invention, the tubular membrane filtration system includes a box body, a microporous membrane, a water washing device and a medicine washing device, the microporous membrane, the The water washing device and the medicine washing device are both arranged in the box.

As an improvement of the zero-discharge treatment system for nickel-plating wastewater in iron and steel workshops of the present invention, both the primary RO system and the secondary RO system are provided with cleaning devices.

As an improvement of the zero-discharge treatment system for nickel-plating wastewater in iron and steel workshops of the present invention, the treatment system further includes a PLC control system and a touch screen connected to the PLC control system.

Another object of the present invention is to provide a method utilizing the system of the present invention to carry out zero-discharge treatment of nickel-plating waste water in iron and steel workshops, comprising the following steps:

In the first step, the waste water is first collected in the collection aeration water tank for buffering, and then poured into the reaction aeration water tank, and then the alkali solution is added to the reaction aeration water tank from the alkali adding device to make the pollutants in the waste water react with the alkali generate solid precipitates;

In the second step, the waste water containing the solid precipitation is pumped into the concentrated water tank, and the solid particles are precipitated in the concentrated water tank, so that the waste water in it is divided into a supernatant liquid and a lower layer sediment, and the upper clear liquid is pumped into a tubular membrane filter In the system, the sediment in the lower layer is pressed to the plate and frame filter press for pressure filtration, the filtered sludge is transported out, and the formed filtrate enters the collection aeration water tank;

In the third step, the supernatant is continuously concentrated in the tubular membrane filtration system, so that the concentrated water containing solid precipitation is separated from the product water. , and then add acid solution from the acid adding device to the callback aeration water tank, adjust the pH to neutral and then enter the security filter;

In the fourth step, the water flowing out of the security filter is pumped into the first-level RO system through the first-level high-pressure pump, and the produced water from the first-level RO system can be directly used, while the concentrated water enters the concentrated water tank;

In the fifth step, the second high-pressure pump pumps the water in the concentrated water tank into the secondary RO system. The produced water from the secondary RO system can be used directly, while the concentrated water is returned to the collection aeration water tank.

Compared with the prior art, the present invention firstly carries out chemical pretreatment by adding alkali to wastewater, so that metal ions such as nickel, copper, zinc become precipitates, and then filters the chemically pretreated wastewater by using a tubular membrane filtration system , so that the precipitated sludge is transported out after passing through the plate and frame filter press, so that metal ions such as nickel, copper, and zinc in the nickel-plating wastewater in the iron and steel workshop can be well removed, and no additional sedimentation is required during the entire filtration process pool, and there is no need to use coagulant (PAM), the water after filtration is clear and rarely contains fine suspended matter, and the SDI in wastewater can be reduced to between 1-3 without sand carbon and ultrafiltration, so it can be done Reach the standard discharge. In addition, the microporous membrane in the tubular membrane filtration system can withstand the cleaning of acidic, alkaline, bleaching and oxidizing agents. Therefore, the tubular membrane filtration system has a long service life, usually 3 to 5 years.

Moreover, the activated carbon filter in the present invention can reduce COD, adsorb colloids and particulate impurities in the water, thereby further removing substances that are not suitable for discharge in the waste water, so that the nickel plating waste water discharged from the iron and steel workshop becomes standard water.

Set up a security filter, a primary RO system, a concentrated water tank and a secondary RO system after calling back the aeration water tank to achieve zero discharge of nickel-plating wastewater in the iron and steel workshop, because the security filter can remove particulate impurities left in the water , to ensure the normal operation of the first-level RO system and the second-level RO system. The first-level RO system and the second-level RO system use reverse osmosis to separate the solute (ions, molecules) from water through the reverse osmosis membrane. The two-level RO system The combined use can remove nickel, copper and other metal ions left in the wastewater treated by the tubular membrane filtration system, so as to achieve zero discharge.

Compared with the traditional ion exchange resin, the RO system has the following advantages: no acid and alkali regeneration is required, which can save a lot of acid, alkali and cleaning water, greatly reduce labor intensity, and there is no waste acid and waste alkali discharge, so it can be compared It guarantees clean production; it can supply water continuously for a long time; it occupies a very small area (less than 1/4 of the traditional process), and it is easy to operate.

Description of drawings

Fig. 1 is the structural representation of the present invention.

Fig. 2 is the structural representation of tubular membrane filtration system in the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the specific embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

As shown in Figure 1, a zero-discharge treatment system for nickel-plating wastewater in a steel workshop provided by the present invention includes a collection aeration water tank 1, a reaction aeration water tank 2, a concentrated water tank 3, a tubular membrane filtration system 4, and activated carbon filtration Device 5, callback aeration water tank 6, security filter 7, primary RO system 8, concentrated water tank 9, secondary RO system 10 and plate and frame filter press 11, collecting the outlet of aeration water tank 1 and reaction aeration water tank 2 The inlet of the reaction aeration water tank 2 is connected to the waste water inlet of the concentrated water tank 3, the water outlet of the concentrated water tank 3 is connected to the inlet of the tubular membrane filtration system 4, and the solid outlet of the concentrated water tank 3 is connected to the plate and frame filter press 11 The inlet of the plate and frame filter press 11 is connected to the inlet of the collection aeration water tank 1, the water outlet of the tubular membrane filtration system 4 is connected to the activated carbon filter 5, and the concentrated water outlet of the tubular membrane filtration system 4 It is connected with the concentrated water inlet of the concentrated water tank 3, the outlet of the activated carbon filter 5 is connected with the inlet of the callback aeration water tank 6, the outlet of the callback aeration water tank 6 is connected with the inlet of the security filter 7, and the outlet of the security filter 7 passes through a The first-stage high-pressure pump 12 is connected to the inlet of the first-stage RO system 8, the concentrated water outlet of the first-stage RO system 8 is connected to the inlet of the concentrated water tank 9, and the outlet of the concentrated water tank 9 passes through the second-stage high-pressure pump 13 and the inlet of the second-stage RO system 10 Connection, the concentrated water outlet of the secondary RO system 10 is connected to the inlet 1 of the collection aeration water tank, the reaction aeration water tank 2 is also connected to the alkali adding device 21, and the callback aeration water tank 6 is also connected to the acid adding device 14.

Among them, the security filter 7 is also called a precision filter device, which is filled with PP cotton. The pore size of the PP cotton is about 5 μm, which can remove tiny suspended solids, bacteria and other impurities in the water, so that the water quality can meet the requirements of the reverse osmosis membrane.

Wherein, the treatment system further includes a fresh water tank 15 , and the water production outlet of the primary RO system 8 and the produced water outlet of the secondary RO system 10 are both connected to the inlet of the fresh water tank 15 . The fresh water tank 15 is used to store the treated clean water. When it needs to be reused in the workshop, it only needs to use the water outlet pump 20 to pump it out to the place where water is needed in the workshop.

A first lift pump 16 is arranged between the collection aeration water tank 1 and the reaction aeration water tank 2 for pumping wastewater from the collection aeration water tank 1 into the reaction aeration water tank 2 .

A second lift pump 17 is arranged between the waste water inlet of the reaction aeration water tank 2 and the concentration water tank 3, and is used to pump the waste water reacted with the alkali into the concentration water tank 3 from the reaction aeration water tank 2 for static stratification, The solid precipitate was allowed to separate from the supernatant.

A circulating pump 18 is arranged between the liquid outlet of the concentrated water tank 3 and the tubular membrane filtration system 4 for pumping the supernatant in the concentrated water tank 3 into the tubular membrane filtration system 4 for microfiltration. The concentrated water tank 3 can also precipitate the solid precipitation in the wastewater returned by the tubular membrane filtration system 4 .

A sludge filter press pump 19 is arranged between the solid outlet of the concentrated water tank 3 and the inlet of the plate and frame filter press 11 to pump the solid sediment in the concentrated water tank 3 into the plate and frame filter press 11 for plate pressure, thereby Separate the filter mud from the filtrate.

As shown in Figure 2, the tubular membrane filtration system 4 includes a box body 41, a tubular membrane 42, a water washing device 43 and a medicine washing device 44, and the microporous filter membrane 42, the water washing device 43 and the medicine washing device 44 are all arranged in the box body within 41.

Tubular membrane 42 is a porous membrane made of ultrahigh molecular polymer, and its aperture range is 0.1 micron. What select for use in the present invention is PVDF membrane or PVDF/HDPE composite membrane, and its support is very firm, wear-resistant, High temperature resistance, pH between 0-14 will not reduce its ability to retain solids. The working principle of the tubular membrane 42 is to use the static pressure difference as the driving force, and use the "screening" effect of the membrane to separate. It has a relatively neat, Uniform porous structure, under the action of static pressure difference, the particles smaller than the membrane pores pass through the membrane, and the particles larger than the membrane pores are blocked on the membrane surface, so that the components of different sizes can be separated to achieve a more thorough solidification. liquid separation. Tubular membrane 42 combined with micro-flocculation technology can separate suspended particles, colloids, organic macromolecules, bacteria, microorganisms, etc. in wastewater to purify water. As the filtration time increases, particles are trapped on the membrane surface or in the membrane pores to form a layer of filter cake. In order to maintain a certain flow rate, it is necessary to increase the driving pressure. When the pressure increases to a certain value, the device must be washed with water. The intercepted layer on the membrane is backwashed to wash off the filter cake on the membrane and restore the ability of the filter membrane. Generally, every 30-60 minutes, automatic backwash once, and each backwash time is 60-90 seconds.

After a long period of operation, some pollutants or particles in the water are firmly adsorbed by the filter membrane, and cannot be completely washed away during backwashing and accumulate. React with the chemical cleaning solution, the solution is separated from the membrane, and then removed by backwashing to restore the filtration performance of the membrane. The time interval for chemical cleaning is generally 10 to 20 days.

Both the primary RO system 8 and the secondary RO system 10 are provided with cleaning devices. It will automatically flush the membrane surface for 60 seconds when starting and stopping, but when certain pollutants are accumulated on the reverse osmosis membrane in the primary RO system 8 and secondary RO system 10, it will automatically start the chemical washing membrane device, which can The pollutants on the surface of the membrane are washed away to prolong the life of the reverse osmosis membrane.

The reverse osmosis separation temperature of the primary RO system is 10-50°C, the pressure of the primary high-pressure pump 12 is 1.0-1.8MPa, the reverse osmosis separation temperature of the secondary RO system is 10-50°C, and the pressure of the secondary high-pressure pump 12 is 1.0-1.8MPa, when the pressure is too high, it will automatically shut down for protection through the high pressure protection device.

The treatment system also includes a PLC control system and a touch screen connected to the PLC control system. The PLC control system is connected to the collection aeration water tank 1, the reaction aeration water tank 2, the concentrated water tank 3, the tubular membrane filtration system 4, the activated carbon filter 5, and the callback Aeration water tank 6, security filter 7, primary RO system 8, concentrated water tank 9, secondary RO system 10, plate and frame filter press 11, primary high pressure pump 12, secondary high pressure pump 13, alkali adding device 21, Acid adding device 14, fresh water tank 15, first lift pump 16, second lift pump 17, circulation pump 18 and sludge filter press pump 19 are connected to control the action and running time of each component, so that the whole system can run automatically , Automatic cleaning.

Utilize the system of the present invention to carry out the method for zero-discharge treatment of the nickel-plating waste water of iron and steel workshop, comprise the following steps:

In the first step, the waste water is first collected to be buffered in the collection aeration water tank 1, then pumped into the reaction aeration water tank 2 through the first lift pump 16, and then an alkali solution is added to the reaction aeration water tank 2 from the alkali adding device 21 ( Such as NaOH), to make the pollutants in the wastewater react with the alkali to form solid precipitation (such as the reaction of nickel ions and NaOH to form nickel hydroxide);

In the second step, the waste water containing the solid precipitation is pumped into the concentrated water tank 3 by the second lift pump 17. In the concentrated water tank 3, the solid particles are precipitated, so that the waste water in it is divided into a supernatant liquid and a lower layer of precipitation, wherein the upper layer The clear liquid is pumped into the tubular membrane filtration system 4 by the circulation pump 18, and the concentration of the solid precipitate in the tubular membrane filtration system 4 is kept between 3-5%, while the lower sediment is pressed to the plate by the sludge filter press pump 19. Frame filter press 11 performs pressure filtration, and the sludge after pressure filtration is transported out, and the formed filtrate enters the collection aeration water tank 1;

In the third step, the supernatant is continuously concentrated in the tubular membrane filtration system 4, so that the concentrated water containing solid precipitation is separated from the product water, and the concentrated water is returned to the concentrated water tank 3 to concentrate and precipitate again, and the product water passes through the activated carbon filter 5 Entering the callback aeration water tank 6, the activated carbon filter 5 can reduce the COD, adsorbed colloid and particulate impurities in the liquid, and then add acid solution from the acid adding device 14 to the callback aeration water tank 6, adjust the pH to neutral and then enter the security filter7;

In the fourth step, the water flowing out from the security filter 7 is pumped into the first-level RO system 8 through the first-level high-pressure pump 12, and the produced water from the first-level RO system 8 is stored in the fresh water tank 15. When it needs to be used, It can be pumped out by the outlet pump 20, and the concentrated water enters the concentrated water tank 9;

In the fifth step, the second high-pressure pump 13 pumps the water in the concentrated water tank 9 into the secondary RO system 10, and the produced water from the secondary RO system 10 is stored in the fresh water tank 15. It just needs to be pumped out, and the concentrated water is returned to the collecting aeration water tank 1 .

The present invention firstly carries out chemical pretreatment by adding alkali to wastewater, so that metal ions such as nickel, copper, and zinc become precipitates, and then filters the chemically pretreated wastewater by using a tubular membrane filtration system Frame filter press 11 is then transported out, so that metal ions such as nickel, copper, and zinc in the nickel-plating wastewater in the iron and steel workshop can be removed well, and there is no need to set up another settling tank in the whole filtration process, and there is no need to use a polymer filter. Coagulant (PAM), the water quality after filtration is clear and does not carry fine suspended solids. Without sand carbon and ultrafiltration, the SDI in wastewater can be reduced to between 1-3, so it can achieve standard discharge. In addition, the microporous membrane in the tubular membrane filtration system can completely remove particulate matter in the water, and the amount of sludge produced is less than that of the traditional process. The tubular high-flow cross-flow filtration is adopted, and the water flow tangentially flows through the membrane surface at high speed. , while filtering, it also has the function of scouring and cleaning the membrane surface, the pollutants are not easy to accumulate, the membrane surface is not easy to be polluted, and can well withstand the cleaning of acid, alkali, bleaching and oxidizing agents. Therefore, the tubular membrane filtration system has a relatively Long service life.

Moreover, the activated carbon filter 5 in the present invention can reduce COD, adsorb colloids and particulate impurities in the water, thereby further removing unsuitable substances in the waste water, so that the nickel-plating waste water discharged from the iron and steel workshop becomes standard water.

Set security filter 7, primary RO system 8, concentrated water tank 9 and secondary RO system 10 after callback aeration water tank, can realize zero discharge of nickel-plating waste water in iron and steel workshop, this is because security filter 7 can clear The particulate impurities left in the water are used to ensure the normal operation of the primary RO system 8 and the secondary RO system 10 . The first-level RO system 8 and the second-level RO system 10 use reverse osmosis to separate solutes (ions, molecules) from water through reverse osmosis membranes. The semi-permeable membrane in the first-level RO system 8 can remove most of the ions and mass The fraction of 90%-95% of dissolved solids, more than 95% of dissolved organic matter and colloids has a rejection rate of more than 98% for nickel ions, and the semi-permeable membrane in the secondary RO system 10 has a rejection rate of 99% for nickel ions. % or more; the combination of the two-stage RO system can remove nickel, copper, zinc and other metal ions left in the wastewater after the tubular membrane filtration system 4, so as to achieve zero discharge, and the concentrated water of the first-stage RO system 8 enters the concentrated After the water tank 9 enters the secondary RO system 10 and stores the produced water for use, the efficiency of water treatment can be improved.

According to the disclosure and teaching of the above-mentioned specification, those skilled in the art to which the present invention belongs can also make changes and modifications to the above-mentioned embodiment. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims (10)

1. A zero-discharge treatment system for nickel-plating waste water in a steel workshop, characterized in that: it includes a collection aeration water tank, a reaction aeration water tank, a concentrated water tank, a tubular membrane filtration system, an active carbon filter, a callback aeration water tank, a security guard filter, primary RO system, concentrated water tank, secondary RO system, fresh water tank, outlet pump and plate-and-frame filter press, the outlet of the collection aeration water tank is connected to the inlet of the reaction aeration water tank, and the reaction The outlet of the aeration water tank is connected to the wastewater inlet of the concentrated water tank, the liquid outlet of the concentrated water tank is connected to the inlet of the tubular membrane filtration system, and the solid outlet of the concentrated water tank is connected to the plate and frame filter press. The inlet is connected, the filtrate outlet of the plate and frame filter press is connected to the inlet of the collecting aeration water tank, the water production outlet of the tubular membrane filtration system is connected to the activated carbon filter, and the tubular membrane filtration system The concentrated water outlet is connected to the concentrated water inlet of the concentrated water tank, the outlet of the activated carbon filter is connected to the inlet of the callback aeration water tank, and the outlet of the callback aeration water tank is connected to the inlet of the security filter , the outlet of the security filter is connected to the inlet of the first-stage RO system through a first-stage high-pressure pump, the concentrated water outlet of the first-stage RO system is connected to the inlet of the concentrated water tank, and the outlet of the concentrated water tank is passed through The secondary high-pressure pump is connected to the inlet of the secondary RO system, the concentrated water outlet of the secondary RO system is connected to the inlet of the collection aeration water tank, and the fresh water outlet of the secondary RO system is connected to the reaction aeration tank. The gas water tank is also connected with an alkali adding device, and the callback aeration water tank is also connected with an acid adding device. 2. The zero-discharge treatment system of nickel-plating wastewater in a steel workshop according to claim 1, characterized in that: the treatment system also includes a fresh water tank, the water output outlet of the first-level RO system and the second-level RO system The produced water outlets of the system are all connected with the inlets of the fresh water tanks. 3. The zero-discharge treatment system for nickel-plating wastewater in iron and steel workshops according to claim 1, characterized in that: a first lift pump is arranged between the collection aeration water tank and the reaction aeration water tank. 4. The zero-discharge treatment system for nickel-plating wastewater in a steel workshop according to claim 1, characterized in that: a second lift pump is arranged between the reaction aeration water tank and the wastewater inlet of the concentrated water tank. 5. The zero-discharge treatment system for nickel-plating wastewater in iron and steel workshops according to claim 1, characterized in that: a circulating pump is arranged between the liquid outlet of the concentrated water tank and the tubular membrane filtration system. 6. The zero-discharge treatment system of nickel-plating waste water in a steel workshop according to claim 1, characterized in that: a sludge filter press is arranged between the solid outlet of the concentrated water tank and the inlet of the plate-and-frame filter press Pump. 7. The zero-discharge treatment system of nickel-plating waste water in iron and steel workshop according to claim 1, characterized in that: the tubular membrane filtration system comprises a box body, a microporous membrane, a water washing device and a medicine washing device, the The microporous filter membrane, the water washing device and the medicine washing device are all arranged in the box. 8. The zero-discharge treatment system for nickel-plating wastewater in iron and steel workshops according to claim 1, characterized in that: both the primary RO system and the secondary RO system are provided with cleaning devices. 9. The zero-discharge treatment system for nickel-plating wastewater in iron and steel workshops according to claim 1, characterized in that: the treatment system further comprises a PLC control system and a touch screen connected with the PLC control system. 10. A method utilizing the system according to claim 1 to carry out zero-discharge treatment of nickel-plating waste water in iron and steel workshop, it is characterized in that, comprising the following steps: In the first step, the waste water is first collected in the collection aeration water tank for buffering, and then poured into the reaction aeration water tank, and then the alkali solution is added to the reaction aeration water tank from the alkali adding device to make the pollutants in the waste water react with the alkali Generate small particles of solid precipitates; In the second step, the wastewater containing the small particle solid precipitation is pumped into the concentrated water tank. In the concentrated water tank, the solid particles are precipitated, so that the wastewater in it is divided into a supernatant liquid and a lower layer sediment, and the supernatant liquid is poured into the pipe In the membrane filtration system, the lower layer of sediment is pressed to the plate and frame filter press for pressure filtration, the sludge after pressure filtration is transported out, and the formed filtrate enters the collection aeration water tank; In the third step, the supernatant is continuously concentrated in the tubular membrane filtration system, so that the concentrated water containing solid precipitation is separated from the product water. , and then add acid solution from the acid adding device to the callback aeration water tank, adjust the pH to neutral and then enter the security filter; In the fourth step, the water flowing out of the security filter is pumped into the first-level RO system through the first-level high-pressure pump, and the produced water from the first-level RO system can be directly used, while the concentrated water enters the concentrated water tank; In the fifth step, the second high-pressure pump pumps the water in the concentrated water tank into the secondary RO system. The produced water from the secondary RO system can be used directly, while the concentrated water is returned to the collection aeration water tank.