A process for treating wastewater based on electrochemical combined with biological method

Abstract

The present invention discloses a process for treating wastewater based on electrochemical combined biological method, which relates to the technical field of wastewater treatment, including: S1, pretreatment: filtering the wastewater with a grid, and adjusting the pH value of the wastewater to acidic; S2, adding 40-60 g / L of electrolytic material containing iron, carbon and copper to the pretreated wastewater, putting in anaerobic activated sludge, continuously aerating with nitrogen, stirring, and reacting at room temperature for 30-40 minutes; S3, adding aerobic activated sludge to the wastewater treated in S2, and adjusting the pH value of the wastewater to 6.8-7.0, aerating with air, and after 30-45 minutes, discharging after the action of a filter membrane, and obtaining the treated wastewater. The process for treating wastewater provided by the present invention combines micro-electrolysis with aerobic or anaerobic treatment, and designs a reasonable wastewater treatment process, which not only has a high removal rate for COD in wastewater, but also can effectively degrade other organic matter in wastewater, greatly improving the water quality of wastewater.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a process for treating wastewater based on an electrochemical combined biological method. Background Art

[0002] Recently, high-salt organic wastewater from the chemical industry (electroplating, plastic production, printing and dyeing, etc.) has a relatively complex composition. It not only contains toxic substances such as nitro compounds and epoxide compounds, but also contains elements such as nitrogen and phosphorus, and may also contain heavy metals. If it is directly discharged into the nature, the toxic substances will have a relatively bad impact on microorganisms, animals and plants, and may even affect people's health. Therefore, these chemical wastewaters need to be treated before being discharged.

[0003] At present, the commonly used methods for treating wastewater are: physical method, chemical method and biological method. Physical method usually uses sedimentation, flotation, centrifugation, filtration, etc. to treat sewage, and the removal effect of soluble pollutants is not good; chemical method will produce a large amount of sludge, and the operating cost is high, and harmful by-products may be produced; biological method has a long treatment cycle. At present, multiple treatment methods are often combined to treat high-salt organic wastewater, but due to the complex composition of wastewater, high COD content, and strong toxicity, the treatment effect is not good and the COD removal rate is not ideal. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a process for treating wastewater based on electrochemical combined with biological methods. By combining biological methods with electrochemistry, pollutants in organic wastewater can be effectively removed and pollution to the environment can be reduced.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A process for treating wastewater based on electrochemical combined biological method, comprising:

[0007] S1, pretreatment: filtering the wastewater with a screen and adjusting the pH value of the wastewater to acidic;

[0008] S2, adding 40-60 g / L of electrolytic material containing iron, carbon and copper to the pretreated wastewater, adding anaerobic activated sludge, continuously aerating with nitrogen, stirring, and reacting at room temperature for 30-40 minutes;

[0009] S3, add aerobic activated sludge to the wastewater treated in S2, and adjust the pH value of the wastewater to 6.8~7.0, use air for aeration treatment, and after 30~45 minutes, discharge it through the filter membrane to obtain the treated wastewater.

[0010] Furthermore, the preparation method of the electrolytic material containing iron, carbon and copper in step S2 is:

[0011] S21, cleaning the surface of the carbon plate with an acid solution and deionized water, and drying to a constant weight;

[0012] S22, placing the carbon plate in an electroplating device and connecting it to a cathode for electroplating, wherein the anode is a phosphor copper ball; the electroplating temperature is 20-30° C., and the time is 4-6 minutes, to obtain a copper-containing carbon plate;

[0013] S23, vacuum drying the copper-containing carbon plate at 85-90° C. for 3-4 hours, and then crushing the plate under the protection of an inert gas to obtain copper-containing carbon powder;

[0014] S24, mixing copper-containing carbon powder, iron filings, and bentonite in a mass ratio of 1-1.5:1-1.5:1.5-2, and adding deionized water to prepare a ball with a diameter of 0.5-1.5 mm, drying the ball, and sintering it in an inert gas protection environment for 1.5-2 hours at a sintering temperature of 800-850° C.;

[0015] S25, after sintering is completed, the electrolytic material containing iron, carbon and copper is obtained by natural drying.

[0016] Furthermore, in step S21, drying is performed in an oven at a temperature of 100-110°C.

[0017] Furthermore, the composition of the electroplating solution in step S22 includes: 150-180 g / L of CuSO 4 , 40~60 g / L H 2 SO 4 , 15~20 g / L NaCl; the electroplating is carried out with an interval current density, and the current density changes with N1 and N2 as a cycle, where N1 is 1.5~2.0A / dm 2 , N2 is 0.5~0.8A / dm 2 ; Each interval lasts 1 minute.

[0018] Furthermore, in step S23, the copper-containing carbon powder is crushed to 100 mesh; and in step S24, the particle size of the iron filings is 0.1-0.5 mm.

[0019] Furthermore, in step S1, the pH value of the wastewater is adjusted to 4.5-5.0 using hydrochloric acid or ammonia water.

[0020] Furthermore, the stirring speed in step S2 is 60-80 r / min.

[0021] Furthermore, the filter membrane in step S3 is a hollow fiber membrane.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The wastewater treatment process provided by the present invention combines micro-electrolysis with aerobic or anaerobic treatment and designs a reasonable wastewater treatment process. It not only has a high removal rate for COD in the wastewater, but also can effectively degrade other organic matter in the wastewater, thereby greatly improving the water quality of the wastewater.

[0024] (2) The present invention also provides a micro-electrolysis material, which solves the problem that the existing iron-carbon micro-electrolysis material is easy to passivate and harden during use, and is easy to form an isolation layer and lose its function. The present invention also adds copper to the micro-electrolysis material, and nitrobenzene is reduced at the copper electrode, so that nitrobenzene can be degraded in a short time. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with embodiments, and the embodiments of the present invention include but are not limited to the following embodiments.

[0026] This embodiment provides a process for treating wastewater based on electrochemical combined with biological method, and the specific steps are as follows:

[0027] (1) Pretreatment: The collected wastewater is filtered through a screen to remove large particles and floating objects in the wastewater, and the pH value of the filtered wastewater is adjusted to acidic (4.5~5.0), where hydrochloric acid or ammonia water is used for adjustment.

[0028] (2) Preparation of electrolytic materials for micro-electrolysis:

[0029] 1) Wash the grease on the surface of the carbon plate with acid solution and deionized water, and dry the cleaned carbon plate in an oven at 100~110℃ to constant weight;

[0030] 2) Place the carbon plate in an electroplating device and connect it to the cathode for electroplating. The anode is a phosphor copper ball. The composition of the electroplating solution includes: 150~180 g / L CuSO 4 , 40~60 g / L H 2 SO 4 , 15~20 g / L NaCl. The electroplating temperature is 20~30℃, the time is 4~6min, and the copper-containing carbon plate is obtained. The electroplating is carried out using an interval current density, and the current density changes with N1 and N2 as one cycle, where N1 is 1.5~2.0A / dm 2 ; N2 is 0.5~0.8A / dm 2 ; The electroplating time of each interval is 1 minute. By using the interval current density for electroplating, the grain structure of the copper plating layer can be refined, so that the copper can be plated on the surface of the carbon plate more evenly and smoothly, and the corrosion resistance of the plating layer can be improved;

[0031] 3) After vacuum drying the copper-containing carbon plate at 85-90°C for 3-4 hours, crush it to 100 mesh under the protection of inert gas (nitrogen) and seal it to obtain copper-containing carbon powder;

[0032] 4) Mix copper-containing carbon powder, iron filings (particle size 0.1-0.5 mm), and bentonite in a mass ratio of 1-1.5:1-1.5:1.5-2, and add deionized water to prepare balls with a diameter of 0.5-1.5 mm. After drying the balls, place them in an inert gas (nitrogen) protection environment and sinter them for 1.5-2 hours at a sintering temperature of 800-850°C;

[0033] 5) After sintering, dry naturally to obtain the electrolytic material containing iron, carbon and copper, which should be sealed and stored.

[0034] (3) Add 40-60 g / L of electrolytic material and anaerobic activated sludge to the pretreated wastewater, stir continuously at a speed of 60-80 r / min, and react at room temperature for 30-40 min. During this process, nitrogen aeration is continuously used to remove oxygen from the wastewater.

[0035] (4) Add aerobic activated sludge to the wastewater treated in step S3, and adjust the pH value of the wastewater to 6.8-7.0. Aerate the wastewater with air. After 30-45 minutes, discharge the wastewater treated with aerobic activated sludge through a filter membrane to obtain treated wastewater. The filter membrane used here is a hollow fiber membrane.

[0036] The electrolytic materials used in the general micro-electrolysis process are iron filings and carbon particles (such as charcoal, activated carbon, coke, etc.). Due to the potential difference between iron and carbon, countless tiny primary cells are formed. Iron acts as the anode (-0.44V potential) and undergoes oxidation reaction under acidic conditions, dissolving into Fe 2+ ; Carbon particles as cathode, H + It receives electrons at the cathode and is reduced to hydrogen. 2+ and hydrogen have high electrochemical activity and can undergo redox reactions with many organic pollutants in wastewater, destroying the molecular structure of organic pollutants, such as chain breaking and ring opening reactions, thereby degrading organic matter; at the same time, Fe 2+Ions have a coagulation effect, and attract each other with negatively charged particles to form stable flocs, which are helpful to remove pollutants in water, provide a nutrient-rich environment for anaerobic microorganisms, promote their growth activities, and accelerate the decomposition process of organic matter by anaerobic microorganisms. Therefore, under the dual effects of micro-electrolysis + anaerobic activated sludge, organic matter in water can be effectively degraded, and high-load BOD and COD have an effective removal rate. However, after anaerobic treatment, there are still certain BOD and COD remaining in the wastewater, and there are also products of anaerobic degradation (a small amount of ammonia and hydrogen sulfide). Therefore, this embodiment also performs aerobic treatment on the wastewater after anaerobic treatment, and further degrades the untreated organic matter in the wastewater, while removing the remaining ammonia and hydrogen sulfide. And during aerobic treatment, due to the presence of oxygen, the cathode of the micro-electrolysis may also undergo an oxygen reduction reaction to generate water and hydroxide ions (OH-), which can further increase the pH value of the wastewater, and some Fe 2+ Oxidized to Fe 3+ , Fe 3+ Hydrolysis generates Fe(OH) with high adsorption performance 3 By adjusting the pH value of the wastewater to 6.8~7.0 and adding the effect of the micro-electrolysis cathode, the pH value of the wastewater can be made neutral or weakly alkaline, which can further promote the Fe(OH) 3 The generation of flocculation effect is enhanced, thereby improving the wastewater treatment effect.

[0037] In addition, when only iron-carbon is used as the electrolytic material, the iron-carbon is easily passivated and hardened. Since the iron and carbon are in physical contact, an isolation layer is easily formed between them, which makes the micro-electrolysis unable to continue and lose its function. Therefore, the present embodiment introduces copper into the electrolytic material, which can effectively solve the problem of easy passivation and hardening of the traditional iron-carbon electrolytic material. The wastewater generated by chemical plants and printing and dyeing plants often contains nitrobenzene. The traditional iron-carbon electrolytic material cannot effectively remove nitrobenzene in the wastewater. After the introduction of copper, the nitrobenzene in the wastewater can be effectively removed.

[0038] Example 1

[0039] This embodiment provides a process for treating wastewater based on electrochemical combined with biological method, and the specific steps are as follows:

[0040] (1) Pretreatment: The collected wastewater is filtered through a screen to remove large particles and floating objects in the wastewater, and the pH value of the filtered wastewater is adjusted to 4.5, where hydrochloric acid and ammonia are used for adjustment.

[0041] (2) Preparation of electrolytic materials for micro-electrolysis:

[0042] 1) Wash the grease on the surface of the carbon plate with 5% dilute hydrochloric acid and deionized water, and dry the cleaned carbon plate in an oven at 100°C to constant weight;

[0043] 2) Place the carbon plate in the electroplating device and connect it to the cathode, then electroplate it. The anode is a phosphor copper ball. The composition of the electroplating solution includes: 150g / L CuSO 4 , 40g / L H 2 SO 4 , 15g / L NaCl. The electroplating temperature is 20℃, the time is 6min, and a copper-containing carbon plate is obtained. The electroplating is carried out using an interval current density, and the current density changes with N1 and N2 as one cycle, where N1 is 1.5A / dm 2 ; N2 is 0.8A / dm 2 ; The electroplating time for each interval is 1 minute.

[0044] 3) After vacuum drying the copper-containing carbon plate at 85°C for 3 hours, crush it to 100 mesh under the protection of nitrogen and seal it to obtain copper-containing carbon powder;

[0045] 4) Copper-containing carbon powder, iron filings (0.1 mm), and bentonite were mixed in a mass ratio of 1:1:1.5, and deionized water was added to prepare a ball with a diameter of 0.8 mm. After the ball was dried, it was placed in a nitrogen protection environment and sintered for 1.5 hours at a sintering temperature of 800°C;

[0046] 5) After sintering, dry naturally to obtain the electrolytic material containing iron, carbon and copper, which should be sealed and stored.

[0047] (3) Add 40 g / L of electrolytic material and anaerobic activated sludge to the pretreated wastewater, and continue stirring at a speed of 60 r / min. React at room temperature for 30 min. During this process, nitrogen aeration is continuously used to remove oxygen from the wastewater.

[0048] (4) Add aerobic activated sludge to the wastewater treated in step S3, adjust the pH value of the wastewater to 6.8, and aerate it with oxygen or air. After 30 minutes, discharge the wastewater treated with aerobic activated sludge through a filter membrane to obtain treated wastewater. The filter membrane used here is a hollow fiber membrane.

[0049] The wastewater used for treatment in this embodiment comes from an industrial park in Hohhot, Inner Mongolia. The industrial park includes a food factory, an electronics factory, a printing and dyeing factory, etc. The collected wastewater is treated using the above method. The water quality before and after treatment is as shown in the following table:

[0050] Table 1 Comparison of water quality indicators before and after wastewater treatment in Example 1

[0051]

[0052] Example 2

[0053] This embodiment provides a process for treating wastewater based on electrochemical combined with biological method, and the specific steps are as follows:

[0054] (1) Pretreatment: The collected wastewater is filtered through a screen to remove large particles and floating objects in the wastewater, and the pH value of the filtered wastewater is adjusted to 4.8, where hydrochloric acid is used for adjustment.

[0055] (2) Preparation of electrolytic materials for micro-electrolysis:

[0056] 1) Wash the grease on the surface of the carbon plate with 5% dilute hydrochloric acid and deionized water, and dry the cleaned carbon plate in an oven at 105°C to constant weight;

[0057] 2) Place the carbon plate in the electroplating device and connect it to the cathode, then electroplate it. The anode is a phosphor copper ball. The composition of the electroplating solution includes: 160g / L CuSO 4 , 50g / L H 2 SO 4 , 18g / L NaCl. The electroplating temperature is 25℃, the time is 5min, and a copper-containing carbon plate is obtained. The electroplating is carried out using an interval current density, and the current density changes with N1 and N2 as one cycle, where N1 is 1.8A / dm 2 ; N2 is 0.6A / dm 2 ; The electroplating time for each interval is 1 minute.

[0058] 3) The copper-containing carbon plate is vacuum dried at 90°C for 3.5 hours, crushed to 100 mesh under the protection of nitrogen, and sealed for storage to obtain copper-containing carbon powder;

[0059] 4) Copper-containing carbon powder, iron filings (0.4 mm), and bentonite were mixed in a mass ratio of 1.2:1.2:1.8, and deionized water was added to prepare balls with a diameter of 1.2 mm. After the balls were dried, they were placed in a nitrogen protection environment and sintered for 1.8 hours at a sintering temperature of 820°C;

[0060] 5) After sintering, dry naturally to obtain the electrolytic material containing iron, carbon and copper, which should be sealed and stored.

[0061] (3) Add 50 g / L of electrolytic material and anaerobic activated sludge to the pretreated wastewater, stir continuously at a speed of 70 r / min, and react at room temperature for 35 min. During this process, nitrogen aeration is continuously used to remove oxygen from the wastewater.

[0062] (4) Add aerobic activated sludge to the wastewater treated in step S3, adjust the pH value of the wastewater to 7.0, and aerate it with oxygen. After 45 minutes, discharge the wastewater treated with aerobic activated sludge through a filter membrane to obtain treated wastewater. The filter membrane used here is a hollow fiber membrane.

[0063] The wastewater used for treatment in this embodiment comes from an industrial park in Hohhot, Inner Mongolia, which includes a food factory, an electronics factory, a printing and dyeing factory, etc. Although the source of the wastewater in this embodiment is the same as that in Example 1, the collection period is different. The collected wastewater is treated by the above method. The water quality before and after treatment is as follows:

[0064] Table 2 Comparison of water quality indicators before and after wastewater treatment in Example 2

[0065]

[0066] Example 3

[0067] This embodiment provides a process for treating wastewater based on electrochemical combined with biological method, and the specific steps are as follows:

[0068] (1) Pretreatment: The collected wastewater is filtered through a screen to remove large particles and floating objects in the wastewater, and the pH value of the filtered wastewater is adjusted to 5.0, where hydrochloric acid and ammonia are used for adjustment.

[0069] (2) Preparation of electrolytic materials for micro-electrolysis:

[0070] 1) Wash the grease on the surface of the carbon plate with 5% dilute hydrochloric acid and deionized water, and dry the cleaned carbon plate in an oven at 110°C to constant weight;

[0071] 2) Place the carbon plate in the electroplating device and connect it to the cathode, then electroplate it. The anode is a phosphor copper ball. The composition of the electroplating solution includes: 180g / L CuSO 4 , 60g / L H 2 SO 4 , 20g / L NaCl. The electroplating temperature is 30℃, the time is 4min, and a copper-containing carbon plate is obtained. The electroplating is carried out using an interval current density, and the current density changes with N1 and N2 as one cycle, where N1 is 2.0A / dm 2 ; N2 is 0.8A / dm 2 ; The electroplating time for each interval is 1 minute.

[0072] 3) The copper-containing carbon plate is vacuum dried at 85°C for 3 hours, crushed to 100 mesh under the protection of nitrogen, and sealed for storage to obtain copper-containing carbon powder;

[0073] 4) Copper-containing carbon powder, iron filings (0.5 mm), and bentonite were mixed in a mass ratio of 1.5:1.5:2, and deionized water was added to prepare balls with a diameter of 1.5 mm. After the balls were dried, they were placed in a nitrogen protection environment and sintered for 2 hours at a sintering temperature of 850°C;

[0074] 5) After sintering, dry naturally to obtain the electrolytic material containing iron, carbon and copper, which should be sealed and stored.

[0075] (3) Add 60 g / L of electrolytic material and anaerobic activated sludge to the pretreated wastewater, and continue stirring at a speed of 80 r / min. React at room temperature for 40 min. During this process, nitrogen aeration is continuously used to remove oxygen from the wastewater.

[0076] (4) Add aerobic activated sludge to the wastewater treated in step S3, adjust the pH value of the wastewater to 7.0, and aerate it with oxygen. After 45 minutes, discharge the wastewater treated with aerobic activated sludge through a filter membrane to obtain treated wastewater. The filter membrane used here is a hollow fiber membrane.

[0077] The wastewater used for treatment in this embodiment comes from an industrial park in Hohhot, Inner Mongolia, which includes a food factory, an electronics factory, a printing and dyeing factory, etc. Although the source of the wastewater in this embodiment is the same as that in Example 1, the collection period is different. The collected wastewater is treated by the above method. The water quality before and after treatment is as follows:

[0078] Table 3 Comparison of water quality indicators before and after wastewater treatment in Example 3

[0079]

[0080] It can be seen from Examples 1, 2 and 3 that the method provided by the present invention can be used to treat wastewater, thereby removing organic matter in the wastewater in a relatively short period of time, and the removal rates of nitrobenzene, COD and the like are relatively high.

[0081] The above embodiment is only one of the preferred implementation modes of the present invention and should not be used to limit the protection scope of the present invention. Any changes or modifications that are made to the main design concept and spirit of the present invention and have no substantive significance, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention.

Claims

1. A process for treating wastewater based on electrochemical combined with biological method, characterized in that: include: S1， Pretreatment: Filter the wastewater with a screen and adjust the pH value of the wastewater to acidic; S2, adding 40-60 g / L of electrolytic material containing iron, carbon and copper to the pretreated wastewater, adding anaerobic activated sludge, continuously aerating with nitrogen, stirring, and reacting at room temperature for 30-40 minutes; S3, adding aerobic activated sludge to the wastewater treated in S2, and adjusting the pH value of the wastewater to 6.8-7.0, using air for aeration treatment, and after 30-45 minutes, the wastewater is discharged after being filtered through a membrane to obtain the treated wastewater; The preparation method of the electrolytic material containing iron, carbon and copper in step S2 is: S21, cleaning the surface of the carbon plate with an acid solution and deionized water, and drying to a constant weight; S22, placing the carbon plate in an electroplating device and connecting it to a cathode for electroplating, wherein the anode is a phosphor copper ball; the electroplating temperature is 20-30° C., and the time is 4-6 minutes, to obtain a copper-containing carbon plate; S23, vacuum drying the copper-containing carbon plate at 85-90° C. for 3-4 hours, and then crushing the plate under the protection of an inert gas to obtain copper-containing carbon powder; S24, mixing copper-containing carbon powder, iron filings, and bentonite in a mass ratio of 1-1.5:1-1.5:1.5-2, and adding deionized water to prepare a ball with a diameter of 0.5-1.5 mm, drying the ball, and sintering it in an inert gas protection environment for 1.5-2 hours at a sintering temperature of 800-850° C.; S25, after sintering is completed, the electrolytic material containing iron, carbon and copper is obtained by natural drying.

2. A process for treating wastewater based on electrochemical combined biological method according to claim 1, characterized in that: In step S21, drying is performed in an oven at a temperature of 100-110°C.

3. A process for treating wastewater based on electrochemical combined biological method according to claim 2, characterized in that: The composition of the electroplating solution in step S22 includes: 150-180 g / L CuSO4, 40-60 g / L H2SO4, and 15-20 g / L NaCl; the electroplating is performed using an interval current density, and the current density changes with N1 and N2 as one cycle, wherein N1 is 1.5-2.0 A / dm 2 , N2 is 0.5~0.8A / dm 2 ; Each interval lasts 1 minute.

4. A process for treating wastewater based on electrochemical combined biological method according to claim 3, characterized in that: In step S23, the copper-containing carbon powder is crushed to 100 mesh; in step S24, the particle size of the iron filings is 0.1-0.5 mm.

5. A process for treating wastewater based on electrochemical combined biological method according to claim 1 or 4, characterized in that: In step S1, the pH value of the wastewater is adjusted to 4.5-5.0 with hydrochloric acid or ammonia water.

6. A process for treating wastewater based on electrochemical combined biological method according to claim 5, characterized in that: The stirring speed in step S2 is 60-80 r / min.

7. A process for treating wastewater based on electrochemical combined biological method according to claim 6, characterized in that: The filtration membrane in step S3 is a hollow fiber membrane.

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