Physical-biological combined electroplating wastewater treatment method and device

Abstract

The invention relates to a biological-biological combined electroplating wastewater treatment method. The method comprises the following steps: S1, classifying and collecting electroplating wastewater according to different types of metals; s2, performing complex breaking treatment on the electroplating wastewater; s3, adjusting the pH value of the electroplating wastewater subjected to complex breaking treatment to be neutral, and precipitating to remove heavy metals to obtain precipitated wastewater; s4, the precipitated wastewater flows into a sulfate reducing bacteria biochemical reaction tank, and heavy metal in the precipitated wastewater is removed; and S5, carrying out nitrogen and phosphorus removal on the precipitated wastewater in the step S4 by using an A / A / O process. The invention also relates to a biological-biological combined electroplating wastewater treatment device. According to the biological-biological combined electroplating wastewater treatment method, the electroplating wastewater can be efficiently treated, the addition of acidic (100%) and alkaline (50%) pH regulators in the traditional electroplating wastewater treatment process is reduced, the activity of bacteria in an A / O / O process is favorably improved, so that the nitrogen and phosphorus removal efficiency is improved, and the biological-biological combined electroplating wastewater treatment method belongs to the technical field of wastewater treatment.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method and device for treating electroplating wastewater by combining physico-biology. Background Art

[0002] Electroplating wastewater is a common polluted water produced in industrial production processes. There are many pollutants in the electroplating production process. In addition to various heavy metals, cyanide and various strong acids such as sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid are also added. In addition, in the electroplating production process, in order to enhance the stability of ions, a large amount of ammonia water is usually added to complex with metal ions such as nickel ions. The use of a large amount of ammonia water can easily cause the ammonia nitrogen content in the wastewater to exceed the standard. Therefore, the pH value of general electroplating wastewater is low and the water contains a large amount of heavy metal elements, organic matter, sulfate, nitrate, ammonia nitrogen and other substances.

[0003] Traditional methods for removing electroplating wastewater include chemical precipitation, adsorption, ion exchange, membrane separation and other treatment methods. Among them, chemical precipitation has become the mainstream removal process for heavy metal wastewater because of its relatively low price and easy implementation.

[0004] In the traditional process, the amount of chemical reagents added is large and the cost is high. The cost of normal sewage treatment is less than 1 yuan per ton, while the cost of electroplating wastewater treatment is as high as more than 20 yuan or even higher. At the same time, although the large amount of reagents invested achieves acid-base neutralization, there are a large number of various ionic substances in the water body, which affects the subsequent treatment efficiency of nitrogen and phosphorus removal and increases the output of sludge during the treatment process.

[0005] Therefore, the existing electroplating wastewater treatment process has the problems of high cost and low efficiency. Summary of the invention

[0006] In view of the technical problems existing in the prior art, the purpose of the present invention is to provide a physical-biological combined electroplating wastewater treatment method and device to solve the problems of high cost and low efficiency of existing processes for treating electroplating wastewater.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A biological-biocombined electroplating wastewater treatment method comprises the following steps:

[0009] S1: Electroplating wastewater is collected according to the types of metals it contains;

[0010] S2: Conduct chelation treatment on electroplating wastewater;

[0011] S3: adjusting the pH of the electroplating wastewater after the decomposition treatment to neutral, and removing heavy metals by precipitation to obtain precipitated wastewater;

[0012] S4: The precipitated wastewater flows into the sulfate-reducing bacteria biochemical reaction tank to remove heavy metals in the precipitated wastewater;

[0013] S5: Denitrification and phosphorus removal of the precipitated wastewater in step S4 using the A / A / O process.

[0014] As a preferred embodiment, in step S2, the method for breaking the complex of the electroplating wastewater is: adding a strong oxidant to the electroplating wastewater to break the complex of the electroplating wastewater; wherein the strong oxidant is hydrogen peroxide or ozone.

[0015] As a preferred embodiment, in step S3, the method for adjusting the pH value of the electroplating wastewater after the chelation breaking treatment to neutral is: adding slaked lime into the electroplating wastewater after the chelation breaking treatment until the pH value of the electroplating wastewater reaches neutral.

[0016] As a preferred embodiment, in step S4, a sulfate-reducing bacteria biochemical reaction tank is used to remove heavy metals from the precipitated wastewater, and the method is as follows:

[0017] Sulfate-reducing bacteria and precipitated wastewater are added to the sulfate-reducing bacteria biochemical reaction pool, and the sulfate-reducing bacteria and precipitated wastewater undergo the following reactions:

[0018] SO4 2- (aq) +2C (aq) +2H2O (aq) →H2S (aq)+ 2HCO3 - (aq) ,

[0019] M 2+ (aq)+ H2S→MS (s)+ 2H + (aq) .

[0020] As a preferred embodiment, in step S4, during the process of removing heavy metals from the precipitated wastewater, it is necessary to ensure that the sulfate-reducing bacteria are in an anaerobic environment. The method for ensuring that the sulfate-reducing bacteria are in an anaerobic environment is as follows: the sulfate-reducing bacteria biochemical reaction pool is sealed, and only one water inlet and water outlet are retained in the sulfate-reducing bacteria biochemical reaction pool, the water inlet is located at the bottom of the side wall of the sulfate-reducing bacteria biochemical reaction pool, and the water outlet is located at the top of the side wall of the sulfate-reducing bacteria biochemical reaction pool, so that the liquid flows from the water inlet to the water outlet in a bottom-to-top flow direction.

[0021] As a preferred embodiment, in step S4, plastic balls are used to float above the liquid surface in the sulfate-reducing bacteria biochemical reaction pool.

[0022] As a preferred embodiment, in step S4, the sulfate-reducing bacteria biochemical reaction pool is started and runs normally, and then the precipitated wastewater is added. The H2S generated during the reaction between the electroplating wastewater and the sulfate-reducing bacteria combines with the oxygen in the air or liquid to generate S 0 , elemental sulfur floats on the surface of the liquid in the sulfate-reducing bacteria biochemical reaction pool to prevent the liquid from contacting with oxygen in the air, while the oxygen in the liquid is consumed by the H2S produced by the reaction.

[0023] As a preferred embodiment, in step S4, the COD in the liquid in the sulfate-reducing bacteria biochemical reaction pool is observed. If the COD content in the liquid decreases, industrial glucose or industrial sodium lactate is added to maintain the operation of the sulfate-reducing bacteria biochemical reaction pool.

[0024] A physical-biological combined electroplating wastewater treatment device is applied to a physical-biological combined electroplating wastewater treatment method, comprising an inlet pool, a flocculation sedimentation pool, a sulfate-reducing bacteria biochemical reaction pool and an A / A / O process treatment pool; the inlet pool is used to store electroplating wastewater, the inlet pool is connected to the flocculation sedimentation pool, the flocculation sedimentation pool is connected to the sulfate-reducing bacteria biochemical reaction pool, and the sulfate-reducing bacteria biochemical reaction pool is connected to the A / A / O process treatment pool.

[0025] In general, the present invention has the following advantages:

[0026] The present invention discloses a method and device for treating electroplating wastewater by combining physico-biology, which reduces the dosage of chemical agents and the amount of waste sludge, thereby reducing the cost of treating electroplating wastewater; adopts biological treatment to solve the problem of heavy metal emission reaching the standard in the traditional electroplating wastewater treatment process; simultaneously removes COD and sulfate ions in the electroplating wastewater, reduces the ion content of the water body, and thereby reduces secondary water pollution problems such as black and smelly water bodies; and the entire process flow improves the efficiency of the A / A / O process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of a physical-biological combined electroplating wastewater treatment device.

[0028] Figure 2 The figure is a process flow chart of a physical-biological combined electroplating wastewater treatment method.

[0029] Figure 3 Schematic diagram of the sulfate-reducing bacteria biochemical reaction pool in a bio-biological combined electroplating wastewater treatment method.

[0030] Among them, 1 is the water inlet tank, 2 is the flocculation sedimentation tank, 3 is the sulfate-reducing bacteria biochemical reaction tank, 4 is the A / A / O process treatment tank, 5 is the plastic ball, 6 is the water outlet, 7 is the water inlet, and 8 is the sludge discharge outlet. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below in conjunction with specific implementation methods.

[0032] Embodiment 1

[0033] like Figure 2 As shown, this embodiment provides a bio-bio combined electroplating wastewater treatment method, comprising the following steps:

[0034] S1: Collect electroplating wastewater according to the types of metals it contains; specifically, before treating electroplating wastewater, it is necessary to collect electroplating wastewater according to the types of metals it contains, including testing the data of heavy metals and various ions related to the wastewater, so as to determine the standards for subsequent treatment and perform necessary pretreatment operations;

[0035] S2: Performing chelation treatment on the electroplating wastewater; specifically, adding a strong oxidant to the electroplating wastewater that needs to be chelated after classification treatment to perform chelation treatment on the complex electroplating wastewater, and after the treatment is completed and the electroplating wastewater that does not need to be chelated is centrally treated;

[0036] S3: Adjust the pH of the electroplating wastewater after the decomposition treatment to neutral, and select a suitable HRT (hydraulic retention time: the average residence time of the treated wastewater in the reactor) for precipitation to remove most of the heavy metals in the electroplating wastewater to obtain precipitated wastewater;

[0037] S4: The precipitated wastewater flows into the sulfate-reducing bacteria biochemical reaction pool to remove the remaining heavy metals in the electroplating wastewater through biochemical reactions to achieve standard treatment;

[0038] S5: Denitrification and phosphorus removal of the precipitated wastewater in step S4 is carried out using the traditional and mature A / A / O process (anaerobic-anoxic-aerobic method).

[0039] Through the above method, electroplating wastewater can be treated biologically to achieve efficient and low-cost removal of heavy metals, improve water quality and reduce the discharge of chemical ions and waste sludge.

[0040] In step S2, the method for breaking the complex of the electroplating wastewater is: adding a strong oxidant to the electroplating wastewater to break the complex of the electroplating wastewater; wherein the strong oxidant is hydrogen peroxide or ozone. It should be noted that complex electroplating wastewater refers to the wastewater that contains various complexing agents (such as EDTA-Na, citrate, etc.) and heavy metal ions (such as Ni) during the electroplating process. 2 + , Cu 2+ The wastewater is produced by forming a stable complex with heavy metal ions (such as ions of chlorinated carbon, etc.). This wastewater has a high degree of processing difficulty because it is difficult to effectively remove these complexed heavy metal ions by traditional chemical precipitation methods. The strong oxidant of this embodiment uses hydrogen peroxide, which can achieve comprehensive removal of heavy metals and reduce the toxic effect of the complex on fungi in the subsequent A / A / O process, and it is low in cost and easy to use.

[0041] In step S3, the method for adjusting the pH of the electroplating wastewater after the chelation breaking treatment to neutral is: adding slaked lime to the electroplating wastewater after the chelation breaking treatment until the pH of the electroplating wastewater reaches neutral. In this embodiment, the wastewater pH is adjusted by slaked lime, which has low cost and high safety factor and is widely used as a strong alkaline substance in pH adjustment. Moreover, since the method of this embodiment only needs to adjust the pH of the electroplating wastewater to 7, compared with the traditional process, a large amount of slaked lime needs to be added to pH>12 to achieve the standard treatment of electroplating wastewater, the method of this embodiment only adjusts the pH to neutral during the treatment process to remove more than 90% of heavy metals in the electroplating wastewater, and reduces the input of a large amount of slaked lime and the generation of sludge. It should be noted that there is no need to adjust the pH in step S3, and this process will not require the input of strong acid, while reducing the concentration of sulfate ions and chloride ions after the input of strong acid.

[0042] Among them, the pH of electroplating wastewater to neutral refers to the pH of electroplating wastewater to 7. Quicklime is added to the electroplating wastewater after chelating treatment until the pH of the electroplating wastewater reaches 7, and then flocculation and sedimentation treatment are performed to remove heavy metals (all metals that can form precipitates with sulfate ions) to obtain precipitated wastewater.

[0043] In step S4, compared with traditional chemical treatment, the method of this embodiment uses biological treatment to remove heavy metals remaining after the chemical process, which can not only achieve the treatment of electroplating wastewater up to standard, but also reduce the treatment cost of electroplating wastewater. The sulfate-reducing bacteria biochemical reaction tank 3 is used to remove heavy metals from the precipitated wastewater, and the method is as follows:

[0044] Sulfate-reducing bacteria and precipitated wastewater are added to the sulfate-reducing bacteria biochemical reaction tank 3, and the sulfate-reducing bacteria and precipitated wastewater undergo the following reactions:

[0045] SO4 2- (aq) +2C (aq) +2H2O (aq) →H2S (aq)+ 2HCO3 - (aq) ,

[0046] M 2+ (aq)+ H2S→MS (s)+ 2H + (aq) .

[0047] M—Heavy Metal,

[0048] aq—liquid,

[0049] S—Solid state.

[0050] In step S4, during the process of removing heavy metals from the sediment wastewater, it is necessary to ensure that the sulfate-reducing bacteria are in an anaerobic environment. The method for ensuring that the sulfate-reducing bacteria are in an anaerobic environment is as follows: the sulfate-reducing bacteria biochemical reaction pool 3 is sealed, and only one water inlet 7 and a water outlet 6 are left in the sulfate-reducing bacteria biochemical reaction pool 3. The water inlet 7 is located at the bottom of the side wall of the sulfate-reducing bacteria biochemical reaction pool 3, and the water outlet 6 is located at the top of the side wall of the sulfate-reducing bacteria biochemical reaction pool 3, so that the liquid flows from the water inlet 7 to the water outlet 6 in a bottom-to-top flow direction. By setting this up, the loss of the lower bacterial liquid is prevented, and the direct entry of oxygen is reduced.

[0051] In step S4, plastic balls 5 are used to float above the liquid surface in the sulfate-reducing bacteria biochemical reaction pool 3. After the plastic balls 5 cover the liquid surface, the amount of oxygen exchange between the liquid and the air can be ensured to be small, which is conducive to maintaining an anaerobic environment.

[0052] In step S4, the sulfate-reducing bacteria biochemical reaction pool 3 is started and runs normally, and then the precipitated wastewater is added. The H2S generated during the reaction between the electroplating wastewater and the sulfate-reducing bacteria combines with the oxygen in the air or liquid to generate S 0 , elemental sulfur floats on the surface of the liquid in the sulfate-reducing bacteria biochemical reaction pool 3 to prevent the liquid from contacting oxygen in the air, while the oxygen in the liquid is consumed by the H2S produced by the reaction.

[0053] In step S4, the COD in the liquid in the sulfate-reducing bacteria biochemical reaction pool 3 is observed. If the COD content in the liquid decreases, industrial glucose or industrial sodium lactate is added to maintain the operation of the sulfate-reducing bacteria biochemical reaction pool 3. The use of industrial glucose or industrial sodium lactate to maintain the operation of the sulfate-reducing bacteria biochemical reaction pool 3 has a lower cost.

[0054] During the A / A / O process in step S5, due to excessive addition of chemical substances during the heavy metal treatment process, the activity of the reactor bacteria is affected. In order to improve the treatment efficiency, it is necessary to increase the carbon source input. At the same time, the high content of various ions is likely to increase the waste sludge. This process reduces the impact on the A / A / O process by reducing the chemical substance input, thereby reducing the carbon source input and waste sludge treatment (usually the sludge treatment cost is high).

[0055] There are a large number of ions in traditional electroplating wastewater after treatment. The presence of a large number of ions in the water body has an adverse effect on the ecological environment. For example, the presence of black and smelly water bodies is directly related to the presence of organic matter and sulfate ions in the water body. The method of this embodiment can reduce the concentration of sulfate ions in the water body and reduce the concentration of various ions by reducing the input of chemical substances, thereby reducing the probability of secondary pollution of the water body.

[0056] Embodiment 2

[0057] like Figure 1-Figure 3As shown, a physical-biological combined electroplating wastewater treatment device provided in this embodiment is applied to a physical-biological combined electroplating wastewater treatment method, including an inlet pool 1, a flocculation sedimentation pool 2, a sulfate-reducing bacteria biochemical reaction pool 3 and an A / A / O process treatment pool 4; the inlet pool 1 is used to store electroplating wastewater, the inlet pool 1 is connected to the flocculation sedimentation pool 2, the flocculation sedimentation pool 2 performs chelation treatment on the electroplating wastewater, adjusts the pH of the electroplating wastewater after chelation treatment to neutral, and precipitates to remove heavy metals to obtain precipitated wastewater; the flocculation sedimentation pool 2 is connected to the sulfate-reducing bacteria biochemical reaction pool 3, and the precipitated wastewater flows into the sulfate-reducing bacteria biochemical reaction pool to further remove heavy metals in the precipitated wastewater; the sulfate-reducing bacteria biochemical reaction pool 3 is connected to the A / A / O process treatment pool 4, and the precipitated wastewater is denitrified and dephosphorized by the A / A / O process. It should be noted that a sludge discharge port 8 is provided at the bottom of the side wall of the sulfate-reducing bacteria biochemical reaction pool 3, and the sludge formed by precipitation is discharged through the sludge discharge port 8.

[0058] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A biological-biointegrated electroplating wastewater treatment method, characterized in that: The following steps are involved: S1: Electroplating wastewater is collected according to the types of metals it contains; S2: Conduct chelation treatment on electroplating wastewater; S3: adjusting the pH of the electroplating wastewater after the decomposition treatment to neutral, and removing heavy metals by precipitation to obtain precipitated wastewater; S4: The precipitated wastewater flows into the sulfate-reducing bacteria biochemical reaction tank to remove heavy metals in the precipitated wastewater; S5: Denitrification and phosphorus removal of the precipitated wastewater in step S4 using the A / A / O process.

2. A bio-bio combined electroplating wastewater treatment method according to claim 1, characterized in that: In step S2, the method for breaking the complex of the electroplating wastewater is: adding a strong oxidant to the electroplating wastewater to break the complex of the electroplating wastewater; wherein the strong oxidant is hydrogen peroxide or ozone.

3. A bio-bio combined electroplating wastewater treatment method according to claim 1, characterized in that: In step S3, the method for adjusting the pH value of the electroplating wastewater after the chelation breaking treatment to neutral is: adding slaked lime into the electroplating wastewater after the chelation breaking treatment until the pH value of the electroplating wastewater reaches neutral.

4. A bio-bio combined electroplating wastewater treatment method according to claim 1, characterized in that: In step S4, a sulfate-reducing bacteria biochemical reaction tank is used to remove heavy metals from the precipitated wastewater, and the method is as follows: Sulfate-reducing bacteria and precipitated wastewater are added to the sulfate-reducing bacteria biochemical reaction pool, and the sulfate-reducing bacteria and precipitated wastewater undergo the following reactions: M 2+ (aq)+ H2S→MS (s)+ 2H + (aq) 。 5. A bio-bio combined electroplating wastewater treatment method according to claim 4, characterized in that: In step S4, during the process of removing heavy metals from the precipitated wastewater, it is necessary to ensure that the sulfate-reducing bacteria are in an anaerobic environment. The method for ensuring that the sulfate-reducing bacteria are in an anaerobic environment is as follows: the sulfate-reducing bacteria biochemical reaction pool is sealed, and only one water inlet and water outlet are retained in the sulfate-reducing bacteria biochemical reaction pool, the water inlet is located at the bottom of the side wall of the sulfate-reducing bacteria biochemical reaction pool, and the water outlet is located at the top of the side wall of the sulfate-reducing bacteria biochemical reaction pool, so that the liquid flows from the water inlet to the water outlet in a bottom-to-top flow direction.

6. A bio-bio-combined electroplating wastewater treatment method according to claim 5, characterized in that: In step S4, plastic balls are used to float above the liquid surface in the sulfate-reducing bacteria biochemical reaction pool.

7. A bio-bio-combined electroplating wastewater treatment method according to claim 1, characterized in that: In step S4, the sulfate-reducing bacteria biochemical reaction pool is started and runs normally, and then the precipitated wastewater is added. The H2S generated during the reaction between the electroplating wastewater and the sulfate-reducing bacteria combines with the oxygen in the air or liquid to generate S 0 , elemental sulfur floats on the surface of the liquid in the sulfate-reducing bacteria biochemical reaction pool to prevent the liquid from contacting with oxygen in the air, while the oxygen in the liquid is consumed by the H2S produced by the reaction.

8. A bio-bio combined electroplating wastewater treatment method according to claim 1, characterized in that: In step S4, the COD in the liquid in the sulfate-reducing bacteria biochemical reaction pool is observed. If the COD content in the liquid decreases, industrial glucose or industrial sodium lactate is added to maintain the operation of the sulfate-reducing bacteria biochemical reaction pool.

9. A biological-biointegrated electroplating wastewater treatment device, applied to a biological-biointegrated electroplating wastewater treatment method according to any one of claims 1 to 8, characterized in that: It includes an inlet pool, a flocculation sedimentation pool, a sulfate-reducing bacteria biochemical reaction pool and an A / A / O process treatment pool; the inlet pool is used to store electroplating wastewater, the inlet pool is connected to the flocculation sedimentation pool, the flocculation sedimentation pool is connected to the sulfate-reducing bacteria biochemical reaction pool, and the sulfate-reducing bacteria biochemical reaction pool is connected to the A / A / O process treatment pool.

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