Semi-closed-loop microbial electrochemical device and method for purifying water body and bottom mud

Abstract

The invention discloses a semi-closed-loop microbial electrochemical device and method for purifying water and sediment, the semi-closed-loop microbial electrochemical device comprises a bacteria-algae coexistence SBR reactor, a direct current power supply, an anode and a cathode, the anode is arranged on the surface layer of the sediment and is connected with the anode of the direct current power supply through a wire, the cathode is placed in the bacteria-algae coexistence SBR reactor, and the direct current power supply is connected with the anode of the direct current power supply through a wire. A water inlet of the bacteria-algae coexistence SBR reactor is communicated with river leakage sewage through a pipeline, so that the sewage can enter the bacteria-algae coexistence SBR reactor, and a water outlet of the bacteria-algae coexistence SBR reactor extends to the vicinity of the anode through a pipeline, so that water treated by the bacteria-algae coexistence SBR reactor is discharged to the vicinity of the anode. According to the semi-closed-loop microbial electrochemical device and method, pollutants in low-concentration sewage can be effectively degraded, in-situ treatment can be synchronously carried out on bottom mud, and an effective solution is provided for river sewage leakage.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, specifically to a semi-closed-loop microbial electrochemical device and method for purifying water bodies and sediments. Background Technology

[0002] River sewage leakage is a significant problem currently facing environmental protection projects. On the one hand, it is difficult to continuously collect river sewage; on the other hand, sewage diffuses around the leakage point, affecting the water quality of the local river and causing rapid growth of bottom sediment around the leakage point.

[0003] Currently, the main methods for treating sewage leakage in rivers are integrated equipment based on MBR or MBBR processes, or preliminary treatment using constructed wetlands.

[0004] However, integrated equipment is only used in different scenarios for integrated wastewater treatment. For river seepage, the concentration of the water after seepage is lower than that of the wastewater. Especially after the large-scale treatment of urban black and odorous water bodies, the water concentration near the seepage point in urban rivers is usually COD < 80 mg / L and ammonia nitrogen < 20 mg / L. The COD and ammonia nitrogen concentrations of this water are significantly lower than the wastewater concentrations that integrated equipment is most suitable for, which are COD = 200-400 mg / L and ammonia nitrogen = 20-40 mg / L. In this low-concentration water, the microorganisms in the integrated equipment have difficulty surviving well. Therefore, the integrated equipment is not ideal for treating low-concentration water after river seepage.

[0005] The application of constructed wetlands in river wastewater treatment is limited by factors such as topography, temperature, and volume, resulting in limited practical use. Furthermore, constructed wetlands often fail to provide substantial purification due to their limited oxygen supply capacity. Therefore, there is an urgent need to develop in-situ treatment equipment and methods for low-concentration wastewater and sediment. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a semi-closed-loop microbial electrochemical device and method for purifying water bodies and bottom sediments. This device can effectively degrade conventional pollutants in low-concentration wastewater and simultaneously treat bottom sediments in situ.

[0007] To achieve the above objectives, the present invention provides a semi-closed-loop microbial electrochemical device for purifying water and sediment, comprising: a microbial-algae coexisting SBR reactor; a DC power supply; an anode disposed on the surface of the sediment and connected to the positive terminal of the DC power supply via a wire; and a cathode placed in the microbial-algae coexisting SBR reactor and connected to the negative terminal of the DC power supply via a wire. The microbial-algae coexisting SBR reactor has an inlet and an outlet. The inlet is connected to the seepage sewage from the river via a pipe, allowing the sewage to enter the microbial-algae coexisting SBR reactor. The outlet extends to the vicinity of the anode via a pipe, allowing the water treated by the microbial-algae coexisting SBR reactor to be discharged to the vicinity of the anode. A weak electric field is formed between the microbial-algae coexisting SBR reactor and the sediment to accelerate the process of organic matter in the sediment at the anode losing electrons and being degraded by microorganisms.

[0008] In one embodiment, the algae-bacteria coexisting SBR reactor includes an influent system, an effluent system, an aeration device, and a control system.

[0009] In one embodiment, the pH value in the algae-bacteria coexisting SBR reactor is maintained at 8–8.5 by periodically replenishing sodium carbonate.

[0010] In one embodiment, the anode includes a stainless steel support and a carbon fiber cloth layer covering the stainless steel support.

[0011] In one implementation, the DC power supply voltage is 24V.

[0012] This invention also proposes a method for purifying water and sediment using the aforementioned semi-closed-loop microbial electrochemical device, wherein the water concentration is COD < 80 mg / L and ammonia nitrogen < 20 mg / L, comprising:

[0013] The anode is buried in the bottom sediment by its own weight and connected to the positive terminal of a DC power supply via a wire.

[0014] The cathode is placed in the algae-bacteria coexistence SBR reactor and connected to the negative terminal of a DC power supply via a wire;

[0015] A weak electric field is formed between the bacteria-algae coexisting SBR reactor and the bottom sediment;

[0016] Wastewater is fed into a bacterial-algae coexisting SBR reactor, which is operated with parameters of HRT = 5-10h and aeration time = 0.25-0.5h. Sodium carbonate is added regularly during operation to maintain the pH value at 8-8.5.

[0017] The water treated by the SBR reactor with coexisting bacteria and algae is discharged to the vicinity of the anode, so that the organic matter in the sediment and the nitrate contained in the treated water can undergo denitrification under the metabolism of microorganisms on the riverbed, thereby decomposing the sediment.

[0018] In one embodiment, the packing material of the bacteria-algae coexisting SBR reactor accounts for 15%, the sludge concentration is 2-3 g / L, and the algae concentration is 0.3-0.35 g / L.

[0019] In one embodiment, the bacteria-algae coexisting SBR reactor is operated with parameters of HRT = 10h and aeration time = 0.25h.

[0020] In one embodiment, the light intensity of the algae in the algae coexistence SBR reactor is 60,000 to 100,000 LUX of natural light during the day and 10,000 to 20,000 LUX of fluorescent light at night.

[0021] Beneficial effects:

[0022] (1) This invention provides a microbial electrochemical device and method for treating low-concentration sewage and bottom sediment, which solves the problem that the current integrated equipment is not ideal for treating low-concentration water bodies after river seepage.

[0023] (2) The microbial electrochemical purification device and method of the present invention can simultaneously treat sewage and bottom sediment in situ. Moreover, the microbial electrochemical purification device is a semi-closed loop, so it is not limited by factors such as space and terrain, and provides an effective solution for the treatment of sewage leakage in rivers and bottom sediment near the leakage point.

[0024] (3) The microbial electrochemical purification device and method of the present invention uses algae as an important component for degrading pollutants, making full use of the characteristics of algae to generate oxygen from carbon dioxide under light conditions and absorb and transform nitrogen and phosphorus. Under the synergistic effect of bacterial-algae symbiosis, pollutants in sewage are efficiently treated.

[0025] (4) The microbial electrochemical purification device and method of the present invention utilizes a bacterial-algae coexisting SBR reactor to oxidize ammonia nitrogen in sewage into nitrate, and then discharges the water containing nitrate to the bottom sediment near the anode, allowing the organic matter and nitrate in the bottom sediment to undergo denitrification under the metabolism of microorganisms in the riverbed, thereby decomposing the bottom sediment and effectively reducing the bottom sediment.

[0026] (5) The semi-closed-loop microbial electrochemical device and method of the present invention forms a weak electric field between the sediment and the SBR reactor in which bacteria and algae coexist. It utilizes electron capabilities to promote the reaction, which can accelerate the process of organic matter in the sediment at the anode losing electrons and being degraded by microorganisms, and further improve the efficiency of sediment treatment. Attached Figure Description

[0027] The invention will now be further described and explained with reference to the accompanying drawings.

[0028] Figure 1 This is a schematic diagram of a semi-closed-loop microbial electrochemical device for purifying water and sediment according to the preferred embodiment of the present invention.

[0029] Figure 2 yes Figure 1 A schematic diagram of a microbial-algae coexisting SBR reactor.

[0030] Figure 3 This is a data graph showing the effects of experiments on low-concentration wastewater treatment using a bacterial-algae coexisting SBR reactor and a sludge reactor.

[0031] Figure label:

[0032] 1. Algae and bacteria coexisting SBR reactor; 2. DC power supply; 3. Anode; 4. Cathode; 5. Bottom sediment; 6. River channel; 11. Inlet; 12. Outlet; 13. Aeration device; 14. Solenoid valve; 15. Level gauge. Detailed Implementation

[0033] The technical solution of the present invention will be more clearly and completely explained below with reference to the accompanying drawings and through the description of preferred embodiments of the present invention.

[0034] like Figure 1 As shown, the semi-closed-loop microbial electrochemical device for purifying water and sediment disclosed in this invention includes: a microbial-algae coexistence SBR reactor 1, a DC power supply 2, an anode 3, and a cathode 4. The anode 3 is located on the surface of the sediment 5 and connected to the positive terminal of the DC power supply 2 via a wire. The cathode 4 is placed in the microbial-algae coexistence SBR reactor 1 and connected to the negative terminal of the DC power supply 2 via a wire. The microbial-algae coexistence SBR reactor 1 has an inlet 11 and an outlet 12. The inlet 11 is connected to the seepage sewage from the river 6 via a pipe, allowing sewage to enter the microbial-algae coexistence SBR reactor 1. The outlet 12 extends via a pipe to the vicinity of the anode 3, allowing the water treated by the microbial-algae coexistence SBR reactor 1 to be discharged to the vicinity of the anode 3. A weak electric field is formed between the microbial-algae coexistence SBR reactor 1 and the sediment 5 to accelerate the process of organic matter in the sediment at the anode 3 losing electrons and being degraded by microorganisms.

[0035] The semi-closed-loop microbial electrochemical device of the present invention can effectively purify low-concentration river sewage and simultaneously treat bottom sediment. Under the synergistic effect of bacterial and algal symbiosis, ammonia nitrogen in sewage is oxidized into nitrate, which is then sent to the vicinity of the anode. Organic matter and nitrate in the bottom sediment undergo denitrification under the metabolism of microorganisms on the riverbed, thereby decomposing the bottom sediment and achieving the effect of bottom sediment reduction.

[0036] like Figure 2 As shown, the algae-bacterial coexistence SBR reactor 1 includes an influent system, an effluent system, an aeration device, and a control system. The aeration device 13 includes an air pump. The influent system includes an influent pump. The effluent system includes a solenoid valve 14. The control system includes a timer switch. The algae-bacterial coexistence SBR reactor 1 is also equipped with a level gauge 15.

[0037] Preferably, the anode 3 includes a stainless steel support and a carbon fiber cloth layer covering the stainless steel support. This design gives the anode 3 a certain weight, allowing it to be buried in the surface of the bottom mud 5 by its own weight. The cathode 4 is made of carbon felt material.

[0038] Preferably, the pH value in the SBR reactor 1 with coexisting bacteria and algae is maintained at 8-8.5 by periodically supplementing sodium carbonate to promote the growth of nitrifying bacteria, algae and photosynthetic bacteria in the reactor.

[0039] Preferably, the voltage of the DC power supply 2 is 24V, and the low-voltage DC power is used to promote the reaction between sewage and bottom sludge.

[0040] Based on the above embodiments, a semi-closed-loop microbial electrochemical device of the present invention is formed. Compared with a closed-loop electrochemical device, the semi-closed-loop microbial electrochemical device of the present invention is not limited by space size. It only needs to treat the wastewater at the cathode, while the bottom sediment near the anode is in a relatively open state, providing more substrate for reaction. The wastewater at the cathode is treated through a coexisting bacteria-algae SBR reactor. Under light conditions, the algae in the reactor utilize carbon dioxide to generate oxygen, achieving denitrification and phosphorus removal. It oxidizes ammonia nitrogen in the wastewater into nitrate, which is then discharged to the vicinity of the anode. The organic matter and nitrate in the bottom sediment undergo denitrification under the metabolism of microorganisms on the riverbed, decomposing the bottom sediment and thus achieving sediment reduction. Furthermore, the semi-closed-loop microbial electrochemical device of the present invention forms a weak electric field between the bottom sediment and the coexisting bacteria-algae SBR reactor, thereby accelerating the process of organic matter in the bottom sediment at the anode losing electrons and being degraded by microorganisms, improving the efficiency of bottom sediment treatment.

[0041] This invention also proposes a method for purifying water and sediment using the aforementioned semi-closed-loop microbial electrochemical device, particularly for low-concentration wastewater with COD < 80 mg / L and ammonia nitrogen < 20 mg / L, comprising:

[0042] The anode 3 is buried in the surface of the bottom mud 5 by its own weight and connected to the positive terminal of the DC power supply 2 through a wire.

[0043] The cathode 4 is placed in the SBR reactor 1 with bacteria and algae coexistence and connected to the negative terminal of the DC power supply 2 through a wire;

[0044] A weak electric field is formed between the bacteria-algae coexisting SBR reactor 1 and the bottom sediment 5;

[0045] Wastewater is fed into the bacteria-algae coexistence SBR reactor 1, which is operated with parameters of HRT = 5-10h and aeration time = 0.25-0.5h. Sodium carbonate is added regularly during operation to keep the pH value at 8-8.5.

[0046] The water treated by the SBR reactor 1 with coexisting bacteria and algae is discharged to the vicinity of the anode 3, so that the organic matter in the sediment 5 and the nitrate contained in the treated water undergo denitrification under the metabolism of microorganisms on the riverbed, thereby decomposing the sediment.

[0047] Preferably, the packing material ratio of the bacteria-algae coexisting SBR reactor is 15%, the sludge concentration is 2-3 g / L, and the algae concentration is 0.3-0.35 g / L. The light intensity for the algae in the bacteria-algae coexisting SBR reactor is 60,000-100,000 LUX of natural light during the day and 10,000-20,000 LUX of fluorescent light at night.

[0048] Preferably, the optimal operating parameters for the algae-bacterial coexistence SBR reactor 1 are HRT = 10h and aeration time = 0.25h. Experiments have verified that excessively long HRT reduces the nutrients required for algal growth, while excessively short HRT leads to significant loss of suspended algae and delayed algal growth. However, with the optimal HRT of 10h, algal growth and pollutant absorption in the algae-bacterial coexistence SBR reactor 1 begin to function effectively. Experiments have also verified that excessive aeration negatively impacts algal growth and reduces pollutant absorption and degradation. Research indicates that algal growth under light conditions produces oxygen, which is more beneficial for the algae-bacterial coexistence SBR reactor under low aeration conditions. Therefore, under these optimal operating parameters, the removal efficiency of conventional pollutants (COD, NH3-N, TN, TP) from wastewater by the algae-bacterial coexistence SBR reactor is significantly improved.

[0049] Based on the above semi-closed-loop microbial electrochemical method, the following examples investigate the differences in wastewater treatment effects between a bacterial-algae coexisting SBR reactor and a sludge reactor under low-concentration influent conditions.

[0050] Experimental conditions: The volume of the bacteria-algae coexisting SBR reactor was 10L, the packing material ratio was 15%, and the SBR operation mode was adopted; the sludge age of the sludge reactor was controlled at 18d.

[0051] The influent for the experiment was prepared using domestic sewage, with the following concentrations: COD 50-80 mg / L, NH3-N 15-20 mg / L, TN 20-25 mg / L, and TP 2-4 mg / L.

[0052] like Figure 3As shown in the figure, the effluent parameters of the SBR reactor and the sludge reactor with coexisting bacteria and algae were as follows when the aeration time was 0.5h to 0.25h: Taking NH3-N as an example, as the aeration time was adjusted in the sequence of 0.5h-0.25h-0.5h-0.25h, it can be seen that at an aeration time of 0.5h, the effluent NH3-N of both was relatively low; at an aeration time of 0.25h, the effluent from bacteria and algae was lower than that from sludge. Based on the data measured on September 4th, the NH3-N in the effluent from bacteria and algae was 0.9 mg / L, while that in the effluent from sludge was 1.6 mg / L. This indicates that under the aeration conditions at this point, the treatment capacity of the bacteria and algae reactor is superior to that of the sludge reactor. At this time, the sludge concentration was approximately 2.2 g / L, the algae concentration was approximately 0.6 g / L, and the DO concentration was approximately 2-3 mg / L.

[0053] It is worth noting that when the aeration time is above 0.5 hours, the effluent NH3-N can reach a low level (around 0.5 mg / L); when the aeration time is 0.25 hours, a difference emerges, with the effluent NH3-N reaching 1-2 mg / L. Considering that the bacteria-algae coexistence SBR reactor is used for treating river seepage wastewater, and its effluent will undergo further treatment after entering the river water body, the bacteria-algae coexistence SBR reactor has advantages under low aeration conditions.

[0054] Through experimental verification, it can be concluded that:

[0055] (1) If the HRT is too high (15h, 20h) or too low (8h, 6h), algae growth in the SBR reactor with bacteria and algae coexistence will be inhibited or severely lost. When HRT = 10h, there are differences in the effluent indicators of the SBR reactor with bacteria and algae coexistence and the sludge reactor, and the effluent indicators of the SBR reactor with bacteria and algae coexistence are low.

[0056] (2) Excessive aeration (aeration time > 0.5h) will result in low effluent indicators for both the bacteria-algae coexisting SBR reactor and the sludge reactor, with no significant difference; however, at low aeration (aeration time = 0.25h), there is a difference in effluent indicators between the two, and the effluent indicators of the bacteria-algae coexisting SBR reactor are lower.

[0057] (3) Under the same operating parameters, the bacteria and algae coexistence SBR system has a higher removal efficiency for conventional pollutants (COD, NH3-N, TN, TP) in wastewater compared to the sludge system.

[0058] The above-described specific embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Various modifications, substitutions, and improvements made by those skilled in the art to the technical solutions of the present invention based on the provided textual description and drawings, without departing from the design concept and spirit of the present invention, should all fall within the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

Claims

1. A semi-closed loop microbial electrochemical device for purifying water bodies and sediments, characterized in that, The application relates to a bacteria-algae coexisting SBR reactor. The application relates to a direct current power supply. An anode is arranged on the surface of the bottom mud and is connected with the positive pole of the direct current power supply through a wire. A cathode is arranged in the bacteria-algae coexisting SBR reactor and is connected with the negative pole of the direct current power supply through a wire. The bacteria-algae coexisting SBR reactor has a water inlet and a water outlet, the water inlet is communicated with the seepage sewage of a river channel through a pipeline, so that the sewage can enter the bacteria-algae coexisting SBR reactor, and the water outlet extends to the vicinity of the anode through a pipeline, so that the water treated by the bacteria-algae coexisting SBR reactor is discharged to the vicinity of the anode. A weak electric field is formed between the bacteria-algae coexisting SBR reactor and the bottom mud, so as to accelerate the process of losing electrons and being degraded by microorganisms of the organic matters of the bottom mud at the anode. The bacteria-algae coexisting SBR reactor comprises a water inlet system, a water outlet system, an aeration device and a control system.

2. The semi-closed loop microbial electrochemical device of claim 1, wherein, The PH value of the bacteria-algae coexisting SBR reactor is kept at 8-8.5 by supplementing sodium carbonate in time.

3. The semi-closed loop microbial electrochemical device of claim 2, wherein, The anode comprises a stainless steel support and a carbon fiber cloth layer wrapping the stainless steel support.

4. The semi-closed loop microbial electrochemical device of claim 1, wherein, The voltage of the direct current power supply is 24V.

5. The semi-closed loop microbial electrochemical device of claim 1, wherein, The application relates to a bacteria-algae coexisting SBR reactor.

6. A method for purifying water and sediment by using the semi-closed loop microbial electrochemical device according to any one of claims 1-5, wherein the concentration of the water is COD < 80 mg / L and ammonia nitrogen < 20 mg / L. A cathode is arranged in the bacteria-algae coexisting SBR reactor and is connected with the negative pole of the direct current power supply through a wire. A weak electric field is formed between the bacteria-algae coexisting SBR reactor and the bottom mud. The sewage is sent into the bacteria-algae coexisting SBR reactor, the bacteria-algae coexisting SBR reactor is operated with the parameters of HRT=5-10h and aeration time=0.25-0.5h, and sodium carbonate is supplemented in time during the operation, so that the PH value is kept at 8-8.

5. The water treated by the bacteria-algae coexisting SBR reactor is discharged to the vicinity of the anode, so that the organic matters in the bottom mud and the nitrate contained in the treated water are subjected to denitrification under the metabolism of the microorganisms on the riverbed, thereby decomposing the bottom mud. The filling ratio of the bacteria-algae coexisting SBR reactor is 15%, the sludge concentration is 2-3g / L, and the algae concentration is 0.3-0.35g / L. The bacteria-algae coexisting SBR reactor is operated with the parameters of HRT=10h and aeration time=0.25h.

7. The semi-closed loop microbial electrochemical process of claim 6, wherein, The illumination intensity of the algae of the bacteria-algae coexisting SBR reactor is 60-100 thousand LUX of natural light in the daytime and 1-2 thousand LUX of sunlight lamp in the night.

8. The semi-closed loop microbial electrochemical process of claim 7, wherein, ​ 9. The semi-closed loop microbial electrochemical process of claim 7, wherein, ​

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