Mud-water separation method for high-salt-content and high-organic-content wastewater in coal-electricity coal chemical industry

Abstract

The invention provides a mud-water separation method for high-salt-content and high-organic-content wastewater in coal-electricity-coal chemical industry, which comprises the following steps: precipitating the wastewater through pre-precipitation, and then adding a flocculating agent and a coagulant aid for flocculation treatment; and then sequentially carrying out electric flocculation and precipitation on the mixed solution subjected to flocculation treatment. According to the mud-water separation method disclosed by the invention, a treatment mode of adding electric flocculation is combined with a plurality of wastewater treatment means, so that suspended matters are effectively removed, and reasonable treatment of coal-electricity coal chemical industry wastewater is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of organic wastewater treatment, and in particular to a method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries. Background Art

[0002] Generally, coal-fired power and coal chemical wastewater is mainly divided into the following categories: ① Coking wastewater, which is wastewater produced in the process of coal decomposition under heat without air, contains phenol, ammonia nitrogen, cyanide, heterocyclic compounds and polycyclic aromatic compounds, etc., which are difficult to biodegrade; ② Coal gasification wastewater, which is wastewater produced in the process of generating coal gas in the gasifier, mainly produced in the washing, condensation and fractionation stages of the coal gas or natural gas manufacturing process. This type of wastewater has a high concentration of pollutants, including phenols, oil and ammonia nitrogen; ③ Coal liquefaction wastewater, which is mainly composed of high-concentration phenol-containing wastewater and low-concentration oil-containing wastewater, and contains high concentrations of toxic substances and difficult-to-biodegrade organic matter.

[0003] Generally speaking, the main characteristics of coal-fired power and coal chemical wastewater include complex composition, high pollutant concentration, great harm, poor biodegradability, and difficulty in treatment.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The first purpose of the present invention is to provide a method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries. This treatment method effectively removes suspended matter by adding an electro-flocculation treatment method and combining a variety of wastewater treatment methods, thereby ensuring that the coal-fired power and coal chemical industry wastewater is properly disposed of.

[0006] The second purpose of the present invention is to provide a mud-water separation system corresponding to the above-mentioned mud-water separation method. By adopting this system, it is ensured that the treated wastewater is pollution-free, no three wastes are discharged, and it is safe and environmentally friendly.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: The present invention provides a method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries, comprising the following steps: The wastewater is first subjected to pre-sedimentation for sedimentation, and then flocculants and coagulants are added for flocculation treatment; Then, the mixed solution after the flocculation treatment is subjected to electro-flocculation and precipitation in sequence.

[0008] Preferably, as a further feasible solution, the pre-sedimentation method is to achieve preliminary sedimentation and discharge of sludge in wastewater by natural sedimentation.

[0009] Preferably, as a further feasible solution, the wastewater is subjected to secondary treatment before pre-sedimentation, and the secondary treatment method includes any of physical precipitation, chemical precipitation, aeration, and microbial filtration.

[0010] Preferably, as a further feasible solution, the secondary treatment includes sequentially performing physical sedimentation and aeration.

[0011] The mud-water separation method of the present invention achieves a good removal effect of organic pollutants and suspended matter in wastewater by integrating various separation means, especially by adopting the method of electric flocculation and utilizing the dissociation effect to better achieve the separation of colloidal impurities and suspended impurities in wastewater by coagulation and precipitation.

[0012] Wastewater can also be further treated in depth, and the means of deep treatment can be selected from reverse osmosis units or forward osmosis units.

[0013] The reverse osmosis unit includes an RO water inlet tank, an RO feed pump, an RO membrane, and a membrane shell mounted on the outside of the RO membrane. The forward osmosis unit includes an FO concentrated brine tank, an FO feed pump, an extraction liquid feed pump, a diluted extraction liquid storage tank, an extraction liquid recovery system, a concentrated brine gas stripping system, an FO membrane, and a membrane shell mounted on the outside of the FO membrane.

[0014] The reverse osmosis unit can be designed as a multi-stage treatment, where the first stage of reverse osmosis concentration obtains the first concentrated liquid, the last stage of reverse osmosis concentration obtains the first separated liquid, the separated liquids of the remaining levels continue to enter the next stage for reverse osmosis concentration, and the concentrated liquid returns to the previous stage for reverse osmosis concentration again; preferably, a two-stage treatment.

[0015] Forward osmosis is the process in which water molecules spontaneously penetrate from high-salt water to the draw liquid under the driving force of the osmotic pressure difference generated on both sides of the semipermeable membrane, and the main substance that generates the power source is the draw liquid. The advantage of this concentration treatment method is that it can be operated without a high-pressure pump, and it can selectively remove dissolved substances in the water while consuming less energy than the thermal method. These characteristics ensure that the forward osmosis unit has higher anti-pollution performance. Similarly, forward osmosis concentration can also be designed as single-stage or multi-stage treatment, but considering the cost and concentration effect, single-stage treatment can meet the requirements.

[0016] The present invention also provides a separation system corresponding to the above-mentioned method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries, comprising: The pre-sedimentation tank, mixing tank, electric flocculation tank and sedimentation tank are connected in sequence.

[0017] Preferably, as a further feasible solution, a plurality of agitators are provided in the mixing tank to achieve sufficient contact and reaction between the flocculant, the coagulant aid and the wastewater.

[0018] Preferably, as a further implementable solution, the cathode and anode in the electro-flocculation cell form an electro-flocculation device.

[0019] Preferably, as a further implementable solution, an inclined tube device is provided in the sedimentation tank, and the rising flow rate of the inclined tube is controlled between 0.4 and 0.6 mm / s.

[0020] Preferably, as a further feasible solution, the hydraulic surface load in the sedimentation tank is controlled at 0.8-1.2 m 3 / (m 2 •h).

[0021] The present invention removes suspended matter in water by using the cathode and anode electro-flocculation devices in the electro-flocculation tank. This step can utilize the dissociation effect of electricity to condense and precipitate colloidal impurities and suspended impurities in the wastewater for separation. When the wastewater is subjected to electro-flocculation treatment, not only the colloidal impurities and suspended impurities are condensed and precipitated, but also the residual organic pollutants and suspended matter in the coal chemical wastewater are removed due to the oxidation effect of the anode and the reduction effect of the cathode. DETAILED DESCRIPTION

[0022] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. If specific conditions are not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0023] Example 1 The method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries includes the following steps: S1: The sludge in the biochemical system is initially separated in the pre-sedimentation tank, and the supernatant in the pre-sedimentation tank enters the mixing tank. S2: In the mixing tank, the flocculant, coagulant aid and wastewater are stirred by an agitator to react and generate flocs.

[0024] S3: The wastewater in the mixing tank then enters the electric flocculation tank, where the colloidal impurities and suspended impurities in the wastewater are condensed using the dissociation effect of electricity.

[0025] S4: The condensed pollutants enter the sedimentation tank, where an inclined pipe device is installed. The rising flow rate of the inclined pipe is controlled at 0.4 mm / s, and the hydraulic surface load is controlled at 0.8 m 3 / (m 2 h), the coagulated flocs are separated by sedimentation.

[0026] S5: After sedimentation and separation, colloidal impurities and suspended impurities in the wastewater are removed, and due to the oxidation of the anode and the reduction of the cathode, the remaining organic pollutants in the wastewater are also removed. The supernatant in the sedimentation tank is discharged into the next process link of the wastewater treatment system.

[0027] Example 2 The method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries includes the following steps: S1: The sludge in the biochemical system is initially separated in the pre-sedimentation tank, and the supernatant in the pre-sedimentation tank enters the mixing tank. S2: In the mixing tank, the flocculant, coagulant aid and wastewater are stirred by an agitator to react and generate flocs.

[0028] S3: The wastewater in the mixing tank then enters the electric flocculation tank, where the colloidal impurities and suspended impurities in the wastewater are condensed using the dissociation effect of electricity.

[0029] S4: The condensed pollutants enter the sedimentation tank, where an inclined pipe device is installed. The rising flow rate of the inclined pipe is controlled at 0.6 mm / s, and the hydraulic surface load is controlled at 1.2 m 3 / (m 2 h), the coagulated flocs are separated by sedimentation.

[0030] S5: After sedimentation and separation, colloidal impurities and suspended impurities in the wastewater are removed, and due to the oxidation of the anode and the reduction of the cathode, the remaining organic pollutants in the wastewater are also removed. The supernatant in the sedimentation tank is discharged into the next process link of the wastewater treatment system.

[0031] Example 3 The method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries includes the following steps: S1: The sludge in the biochemical system is initially separated in the pre-sedimentation tank, and the supernatant in the pre-sedimentation tank enters the mixing tank. S2: In the mixing tank, the flocculant, coagulant aid and wastewater are stirred by an agitator to react and generate flocs.

[0032] S3: The wastewater in the mixing tank then enters the electric flocculation tank, where the colloidal impurities and suspended impurities in the wastewater are condensed using the dissociation effect of electricity.

[0033] S4: The condensed pollutants enter the sedimentation tank, where an inclined pipe device is installed. The rising flow rate of the inclined pipe is controlled at 0.5 mm / s, and the hydraulic surface load is controlled at 1.0 m 3 / (m 2 h), the coagulated flocs are separated by sedimentation.

[0034] S5: After sedimentation and separation, colloidal impurities and suspended impurities in the wastewater are removed, and due to the oxidation of the anode and the reduction of the cathode, the remaining organic pollutants in the wastewater are also removed. The supernatant in the sedimentation tank is discharged into the next process link of the wastewater treatment system.

[0035] Example 4 The method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries includes the following steps: S1: After the organic wastewater undergoes secondary treatment - activated sludge method to remove organic pollutants, the sludge in the biochemical system is initially separated in the pre-sedimentation tank, and the supernatant in the pre-sedimentation tank enters the mixing tank. S2: In the mixing tank, the flocculant, coagulant aid and wastewater are stirred by an agitator to react and generate flocs.

[0036] S3: The wastewater in the mixing tank then enters the electric flocculation tank, where the colloidal impurities and suspended impurities in the wastewater are condensed using the dissociation effect of electricity.

[0037] S4: The condensed pollutants enter the sedimentation tank, where an inclined pipe device is installed. The rising flow rate of the inclined pipe is controlled at 0.5 mm / s, and the hydraulic surface load is controlled at 1.0 m 3 / (m 2 h), the coagulated flocs are separated by sedimentation.

[0038] S5: After sedimentation and separation, colloidal impurities and suspended impurities in the wastewater are removed, and due to the oxidation of the anode and the reduction of the cathode, the remaining organic pollutants in the wastewater are also removed. The supernatant in the sedimentation tank is discharged into the next process link of the wastewater treatment system.

[0039] Example 5 The method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries includes the following steps: S1: After the organic wastewater undergoes secondary treatment of physical sedimentation and aeration-activated sludge method to remove organic pollutants, the sludge in the biochemical system is initially separated in the pre-sedimentation tank, and the supernatant in the pre-sedimentation tank enters the mixing tank. S2: In the mixing tank, the flocculant, coagulant aid and wastewater are stirred by an agitator to react and generate flocs.

[0040] S3: The wastewater in the mixing tank then enters the electric flocculation tank, where the colloidal impurities and suspended impurities in the wastewater are condensed using the dissociation effect of electricity.

[0041] S4: The condensed pollutants enter the sedimentation tank, where an inclined pipe device is installed. The rising flow rate of the inclined pipe is controlled at 0.5 mm / s, and the hydraulic surface load is controlled at 1.0 m 3 / (m 2 h), the coagulated flocs are separated by sedimentation.

[0042] S5: After sedimentation and separation, colloidal impurities and suspended impurities in the wastewater are removed, and due to the oxidation of the anode and the reduction of the cathode, the remaining organic pollutants in the wastewater are also removed. The supernatant in the sedimentation tank is discharged into the next process link of the wastewater treatment system.

[0043] In summary, the present invention provides a highly efficient mud-water separation method for high-salt and high-organic wastewater from coal-fired power and coal chemical industries. After the organic wastewater undergoes secondary treatment—activated sludge method to remove organic pollutants, it enters the mud-water separation process, which is divided into four links, namely, pre-sedimentation tank, mixing tank, electric flocculation tank and sedimentation tank. The sludge in the biochemical system is initially separated in the pre-sedimentation tank, and the supernatant of the pre-sedimentation tank enters the mixing tank, where flocculants, coagulants and wastewater are added to react to generate flocs, which then enter the electric flocculation tank, and the colloidal impurities and suspended impurities in the wastewater are condensed and precipitated by the dissociation effect of electricity to be separated. When the wastewater is subjected to electrolytic flocculation treatment, it not only has a condensation and precipitation effect on the colloidal impurities and suspended impurities, but also removes the remaining organic pollutants and suspended matter in the coal chemical wastewater due to the oxidation effect of the anode and the reduction effect of the cathode. The method of the present invention has a good application value.

[0044] Although the present invention has been illustrated and described with specific embodiments, it will be appreciated that many other changes and modifications may be made without departing from the spirit and scope of the present invention. Therefore, it is intended to include all such changes and modifications within the scope of the present invention in the appended claims.

Claims

1. A method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries, characterized in that: The steps include: The wastewater is first subjected to pre-sedimentation for sedimentation, and then flocculants and coagulants are added for flocculation treatment; Then, the mixed solution after the flocculation treatment is subjected to electro-flocculation and precipitation in sequence.

2. The method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries according to claim 1, characterized in that: The pre-sedimentation method is to achieve the initial sedimentation and discharge of the sludge in the wastewater by natural sedimentation.

3. The method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries according to claim 1, characterized in that: The wastewater is first subjected to secondary treatment before pre-sedimentation. The secondary treatment methods include any of physical sedimentation, chemical sedimentation, aeration, and microbial filtration.

4. The method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries according to claim 3, characterized in that: The secondary treatment includes physical sedimentation and aeration in sequence.

5. The separation system of the method for separating mud and water from high-salt and high-organic wastewater from coal-fired power and coal chemical industries according to any one of claims 1 to 4, characterized in that: include: The pre-sedimentation tank, mixing tank, electric flocculation tank and sedimentation tank are connected in sequence.

6. The separation system according to claim 5, characterized in that A plurality of stirrers are arranged in the mixing tank to achieve full contact and reaction between the flocculant, the coagulant aid and the wastewater.

7. The separation system according to claim 5, characterized in that The cathode and anode in the electro-flocculation cell form an electro-flocculation device.

8. The separation system according to claim 5, characterized in that: An inclined tube device is arranged in the sedimentation tank, and the rising flow rate of the inclined tube is controlled between 0.4 and 0.6 mm / s.

9. The separation system according to claim 5, characterized in that: The hydraulic surface load in the sedimentation tank is controlled at 0.8~1.2m 3 / (m 2 •h).