A method for simultaneously repairing water body and sediment by using a microbial electrochemical repairing device

Abstract

This invention belongs to the field of water environment treatment and restoration technology, specifically involving a method for simultaneous restoration of water bodies and sediments using a microbial electrochemical restoration device. The restoration method provided in this invention differs from traditional methods that enhance the transport of electron acceptors such as oxygen or nitrates into the sediment. Instead, it can sequentially form two reaction zones, aerobic and anaerobic, in the longitudinal section of a device. In the anaerobic zone (sediment), electrons from pollutants are directionally pumped out to the water body driven by the redox potential difference between the sediment and water phases. Therefore, pollutants in the sediment and water body can undergo oxidative degradation and reductive degradation, respectively, thereby achieving simultaneous restoration of water bodies and sediments.

Description

Technical Field

[0001] This invention belongs to the field of water environment treatment and restoration, specifically relating to a method for simultaneous restoration of water bodies and bottom sediments using a microbial electrochemical remediation device. Background Technology

[0002] Water pollution sources are categorized into external and internal sources. External pollution is caused by wastewater discharge into water bodies and can be controlled through methods such as pollution control and interception. Internal pollution occurs when pollutants enter the overlying water body from the bottom sediment. The silt, humus, and other components in the bottom sediment adsorb pollutants from the water, giving it a certain capacity to accumulate pollutants. Organic matter in wastewater and organic matter produced by the decomposition of dead aquatic plants and animals can enter the bottom sediment through adsorption and sedimentation, causing a large accumulation of pollutants. Anaerobic decomposition of organic matter in the bottom sediment creates an anaerobic or even extremely anaerobic environment, producing reducing odorous substances such as biogas, NH3, H2S, thiols, organic amines, and organic acids, as well as blackening substances such as ferrous sulfide and manganese sulfide. Therefore, in the process of water environment management, it is necessary to treat the black and odorous bottom sediment simultaneously to prevent it from becoming an internal source of water pollution.

[0003] Artificial aquatic plant restoration technology is a biological ecological restoration technology for aquatic environments. It can be seen as a variation of biofilm carrier technology, using corrosion-resistant and highly flexible materials to create artificial aquatic plant fillers. These fillers provide a large surface area as a carrier for microorganisms, mimicking the microbial purification process in wastewater treatment to improve the water environment treatment effect of ecological wetlands. However, accidental ingestion of artificial aquatic plants by aquatic animals is a significant cause of material loss, potentially impacting the integrity of the aquatic ecosystem. In practical engineering applications, the plants are directly subjected to the hydraulic scouring effect of water flow, often resulting in severe damage and significantly reduced control effectiveness. Furthermore, since the portion of the artificial aquatic plants buried in the sediment cannot affect the sediment, and material breakage or damage to this buried portion can introduce new pollution into the sediment, this technology cannot achieve in-situ simultaneous restoration of both sediment and water. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for the simultaneous remediation of water bodies and sediments using a microbial electrochemical remediation device. The method provided by this invention can achieve simultaneous remediation of sediments and water bodies.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for simultaneous remediation of water bodies and sediments using a microbial electrochemical remediation device, comprising the following steps:

[0007] The microbial electrochemical remediation device is vertically deployed in the sediment and water body to remediate the sediment and water body;

[0008] The remediation process involves the following: pollutants in the sediment undergo an oxidation reaction under the conditions of electroactive microorganisms in the sediment, releasing electrons. These electrons are then transferred to the water body by a microbial electrochemical remediation device. Oxidizing substances in the water body accept these electrons and undergo a reduction reaction in the presence of electroactive microorganisms.

[0009] The microbial electrochemical remediation device includes a conductive body and a conductive microbial carrier disposed on the outside of the conductive body;

[0010] The number of the microbial electrochemical remediation devices is ≥1.

[0011] Preferably, the microbial electrochemical remediation device further includes a load resistor.

[0012] Preferably, the repair process also includes using an online monitoring device to indicate the repair process.

[0013] Preferably, when the number of microbial electrochemical repair devices is greater than 1, the method further includes applying a voltage to the microbial electrochemical repair devices.

[0014] Preferably, the voltage applied between the microbial electrochemical repair devices ranges from 0.01 to 10 V / cm.

[0015] Preferably, the repair process also includes coupling with aquatic plants.

[0016] Preferably, during deployment, the bottom of the microbial electrochemical remediation device is positioned 0.1 to 2.0 m below the sediment / water interface formed by the sediment and water body; the top of the microbial electrochemical remediation device is located above the light-oxygen compensation depth, or, under sunlight irradiation, the dissolved oxygen in the water body area where the top of the microbial electrochemical remediation device is located is ≥0.5 mg / L.

[0017] Preferably, the deployment density is 1 to 100 microbial electrochemical remediation devices / m². 2 .

[0018] Preferably, the conductive body is made of one or more of the following: metallic materials, carbon materials, and carbon-modified metallic materials.

[0019] Preferably, the conductive microbial carrier comprises one or more of the following: carbon materials, metal oxide-modified carbon materials, metal sulfide-modified carbon materials, conductive polymer-modified carbon materials, and amorphous carbon materials.

[0020] This invention provides a method for the simultaneous remediation of water bodies and sediments using a microbial electrochemical remediation device, comprising the following steps: vertically deploying the microbial electrochemical remediation device in the sediment and water body to remediate the sediment and water body; the remediation involves: pollutants in the sediment undergoing an oxidation reaction under the conditions of electroactive microorganisms in the sediment, releasing electrons, which are then transferred to the water body by the microbial electrochemical remediation device; oxidizing substances in the water body accept the electrons and undergo a reduction reaction in the presence of electroactive microorganisms; the microbial electrochemical remediation device includes a conductive body and a conductive microbial carrier disposed outside the conductive body; the number of microbial electrochemical remediation devices is ≥1. This invention combines a conductive body with a conductive microbial carrier. When used to remediate sediment and water bodies, the conductive microbial carrier enriches the electroactive microorganisms in the sediment, catalyzing the oxidation and degradation of pollutants in the sediment. Simultaneously, pollutants in the sediment release electrons, which are transferred to pollutants in the water body through the conductive body or carrier; pollutants in the water body accept the electrons and undergo a reduction reaction, completing the degradation of pollutants. The remediation device provided in this invention differs from traditional methods that enhance the transfer of electron acceptors such as oxygen or nitrates into sediment. Instead, it sequentially forms two reaction zones—aerobic and anaerobic—in a longitudinal section of the device. In the anaerobic zone (sediment), electrons from pollutants are directionally pumped out to the water body driven by the redox potential difference between the sediment and water phases. Therefore, pollutants in the sediment and water can undergo anaerobic oxidation and reductive degradation, respectively, achieving simultaneous remediation of the water and sediment. The microbial electrochemical remediation device provided by this invention has simple operation steps, requires no manual maintenance or equipment investment, greatly reducing construction and operating costs, and is suitable for the remediation of large areas of natural water bodies and sediments. Furthermore, once the sediment and water have been remediated to the required standards, the device with a mature electroactive biofilm can be recovered. The recovered device can be reintroduced into the ecological environment to be remediated without regeneration treatment, achieving good operational results without secondary acclimatization. Attached Figure Description

[0021] Figure 1 A schematic diagram and layout diagram of the microbial electrochemical remediation device provided by the present invention;

[0022] Figure 2 The present invention provides a schematic diagram and layout diagram of the microbial electrochemical repair device when voltage is applied, wherein 1-microbial electrochemical repair device, 2-microbial electrochemical repair device; 3-applied power source; I-oxidation zone; II-reduction zone; and arrows indicate the internal electric field between two microbial electrochemical repair devices.

[0023] Figure 3 A schematic diagram of the microbial electrochemical remediation device under applied voltage according to this invention;

[0024] Figure 4This is a schematic diagram of the microbial electrochemical remediation device provided in Example 1;

[0025] Figure 5 This is a schematic diagram of the microbial electrochemical remediation device provided in Example 2;

[0026] Figure 6 This is a schematic diagram of the microbial electrochemical remediation device provided in Example 3;

[0027] Figure 7 A graph showing the change in readily biodegradable organic carbon (ROOM) in sediment over time;

[0028] Figure 8 This is a graph showing the change of TN in the sediment over time in Example 3;

[0029] Figure 9 NH4 in the sediment of Example 3 + Graph showing the variation of -N over time;

[0030] Figure 10 This is a graph showing the variation of the redox potential (ORP) of the sediment in Example 3;

[0031] Figure 11 Electrochemical test diagram of the microbial electrochemical remediation device provided in Example 3;

[0032] Figure 12 This is a graph showing the COD concentration and removal rate of the upper water body in different cycles in Example 3;

[0033] Figure 13 This is a graph showing the TN concentration and removal rate of the upper water body in Example 3 during different cycles;

[0034] Figure 14 Example 3: NH4 in the upper water body at different periods + -N concentration and removal rate curve;

[0035] Figure 15 This is a graph showing the community abundance analysis of archaeal communities at the genus level in Examples 1, 2, and Comparative Example 1. Detailed Implementation

[0036] This invention provides a method for simultaneous remediation of water bodies and sediments using a microbial electrochemical remediation device, comprising the following steps:

[0037] The microbial electrochemical remediation device is vertically deployed in the sediment and water body to remediate the sediment and water body;

[0038] The remediation process involves the following: pollutants in the sediment undergo an oxidation reaction under the conditions of electroactive microorganisms in the sediment, releasing electrons. These electrons are then transferred to the water body by a microbial electrochemical remediation device. Oxidizing substances in the water body accept these electrons and undergo a reduction reaction in the presence of electroactive microorganisms.

[0039] The microbial electrochemical remediation device includes a conductive body and a conductive microbial carrier disposed on the outside of the conductive body;

[0040] The number of the microbial electrochemical remediation devices is ≥1.

[0041] The present invention vertically deploys the microbial electrochemical remediation device in the sediment and water body to remediate the sediment and water body.

[0042] In this invention, the microbial electrochemical remediation device includes a conductive body and a conductive microbial carrier disposed on the outside of the conductive body.

[0043] In this invention, the conductive substrate is preferably made of one or more of the following: metallic materials, carbon materials, and carbon-modified metallic materials. The metallic materials preferably include one or more of the following: stainless steel, titanium, nickel, titanium alloys, and nickel alloys, with titanium being more preferred. In this invention, the carbon material preferably includes carbon fiber materials or graphite. In this invention, the carbon-modified metallic materials include metallic materials supported on reduced graphene oxide.

[0044] In this invention, the conductive microbial carrier comprises one or more of the following: carbon materials, metal oxide-modified carbon materials, metal sulfide-modified carbon materials, conductive polymer-modified carbon materials, and amorphous carbon materials. Preferably, the carbon material comprises one or more of the following: carbon plates, carbon paper, carbon cloth, carbon rods, carbon felt strips, carbon fiber brushes, carbon fiber bundles, graphite rods, graphite plates, and graphite felt; more preferably, it is carbon paper, carbon cloth, or carbon felt. Preferably, the metal oxide comprises one or more of ferric oxide, magnetite, and manganese dioxide. Preferably, the metal sulfide comprises manganese disulfide and / or iron sulfide. The conductive polymer comprises one or more of polyaniline, polypyrrole, and polythiophene. The amorphous carbon material comprises activated carbon material bonded by a conductive polymer or activated carbon particles bound by metal wires / cages.

[0045] In this invention, the conductive body and the conductive microbial carrier can be made of the same material that has both microbial carrier function and conductive function, such as carbon fiber brush, carbon fiber bundle, carbon felt strip or carbon rod.

[0046] In this invention, during deployment, the bottom of the microbial electrochemical remediation device is preferably positioned 0.1–2 m below the sediment / water interface formed by the sediment and water body, more preferably 1 m below the interface. In this invention, the top of the microbial electrochemical remediation device is preferably located above the light-oxygen compensation depth, or, under sunlight irradiation, the dissolved oxygen in the water area where the top of the microbial electrochemical remediation device is located is ≥0.5 mg / L. In this invention, the deployment density is preferably 1–100 microbial electrochemical remediation devices / m². 2 More preferably, 20–80 microbial electrochemical remediation devices / m 2 In this invention, the preferred method of installation is to pre-drill columnar holes in the sediment and then vertically insert the microbial electrochemical remediation device.

[0047] In this invention, the remediation is as follows: pollutants in the sediment undergo an oxidation reaction under the conditions of electroactive microorganisms in the sediment, releasing electrons. These electrons are then transferred to the water body by a microbial electrochemical remediation device. Oxidizing substances in the water body accept these electrons and undergo a reduction reaction in the presence of electroactive microorganisms in the water body.

[0048] In this invention, the pollutants in the sediment preferably include ammonia, hydrogen sulfide, and organic matter. In this invention, the pollutants in the water preferably include nitrates, nitrites, and sulfates.

[0049] In this invention, the electroactivity in the sediment and water is not specifically limited. During the remediation process, the microbial electrochemical remediation device provided by this invention can cultivate one or more of the following archaea that promote methane oxidation metabolism, ammonia-oxidizing archaea, and denitrifying bacteria. Among these, the archaea use methane as an electron donor, providing electrons to the system while simultaneously inhibiting the release of greenhouse gases from the sediment.

[0050] Figure 1 The present invention provides a schematic diagram and layout diagram of a microbial electrochemical remediation device, wherein... Figure 1 (a) is a schematic diagram of the microbial electrochemical remediation device without a loaded resistor. Figure 1 (b) is a schematic diagram of the microbial electrochemical remediation device without a loaded resistor. Figure 1 (c) is a layout diagram of the microbial electrochemical remediation device without a load resistor. From Figure 1 It can be seen that the microbial electrochemical remediation device provided by the present invention is plug-and-play and easy to install.

[0051] In this invention, the microbial electrochemical remediation device further includes a load resistor. Preferably, the microbial electrochemical remediation device further includes a load resistor. This invention does not specifically limit the resistance value of the load; a constant resistance or a resistance of different values ​​can be used depending on the actual situation, and the device can be adjusted to operate under the condition of maximum current flowing through the load to obtain optimal remediation performance.

[0052] In this invention, the repair process preferably also includes an online monitoring device. When the repair process includes an online monitoring device, the online monitoring device is connected to a load resistor. Preferably, the online monitoring device is a voltage, current, or potential data acquisition device (such as a paperless recorder, potentiostat, electrochemical workstation, etc.).

[0053] Furthermore, in this invention, the online monitoring can adopt an online visual control mode, that is, using a data acquisition system to monitor the voltage across the load and monitor the current flow of the load in real time. The significance of online monitoring lies in its ability to provide feedback and adjustment for problems occurring in the remediation device, adjusting the load resistance to obtain the maximum current, and also judging the degree of sediment remediation based on monitoring data. When multiple remediation devices are used together, selecting a small number of load-type structured remediation devices can achieve the purpose of multi-point monitoring and remediation effectiveness evaluation.

[0054] In this invention, when the number of microbial electrochemical repair devices is greater than 1, the repair process further includes applying a voltage to the microbial electrochemical repair devices.

[0055] In this invention, the voltage applied between the microbial electrochemical remediation devices is preferably in the range of 0.01 to 10 V / cm. In this invention, the voltage is preferably supplied by a constant current power supply or a regulated voltage power supply. In this invention, the power supply includes dry cell batteries, storage batteries, lithium batteries, photovoltaic cells, wind power batteries, or commercial DC power supplies.

[0056] Figure 2 A schematic diagram and layout diagram of the microbial electrochemical remediation device when voltage is applied to it according to the present invention; Figure 3 A schematic diagram of the microbial electrochemical remediation device when a voltage is applied according to the present invention; from Figures 2-3 It is known that an internal electric field exists between the two microbial electrochemical repair devices due to the application of an electro-driven field, enabling repair to proceed. In this invention, when a voltage is applied between the microbial electrochemical repair devices, the voltage application dominates, therefore, the positive electrode portion of the battery is an oxidation region, and the negative electrode portion is a reduction region.

[0057] In this invention, by applying voltage and coupling it with the microbial electrochemical remediation device, pollutants in the sediment and water can be accelerated to approach the electrodes of the remediation device, promoting the rapid formation of electroactive biofilms on the electrode surface, increasing the remediation range of the electrodes, and accelerating the decomposition or transformation and removal of various pollutants. This electrodriven microbial electrochemical in-situ remediation device promotes the removal and mineralization of environmental pollutants through the coupling of physical, chemical, and biological processes. It can be applied to the in-situ remediation of water bodies and sediments, achieving efficient in-situ removal of environmental pollutants from water bodies and sediments.

[0058] In this invention, the repair process preferably also includes coupling with aquatic plants.

[0059] In this invention, the aquatic plants preferably include algae, emergent plants, floating-leaved plants, submerged plants, floating plants, or wetland plants. Specifically, the aquatic plants are preferably one or more of the following: Myriophyllum spicatum, Potamogeton malaianum, Vallisneria natans, Hydrilla verticillata, Trichoderma purpurea, Trichoderma purpurea, Ceratophyllum demersum, Bladderwort, Caesalpinia serratifolia, Cyperus rotundus, Ranunculus aquatilis, Potamogeton glabra, Myriophyllum spicatum, Elodea nuttallii, Potamogeton crispus, and Hydrilla verticillata.

[0060] In this invention, aquatic plants can compensate for dissolved oxygen in the aerobic zone (upper water layer). In particular, some algae can directly attach to the aerobic zone and form a symbiotic relationship with the biofilm enriched by the conductive microbial carrier in the remediation device, providing non-energy-consuming dissolved oxygen in situ and creating an oxygen-rich environment for aerobic microorganisms. Furthermore, the oxygen secretion function of the aquatic plant roots creates an anoxic microenvironment in the anaerobic zone (bottom sediment), compensating for the electron acceptors in the deep bottom sediment. On the other hand, the absorption of nutrients from the water and bottom sediment by aquatic plants can also promote the removal of pollutants by the remediation device. Therefore, when the remediation device provided by this invention is coupled with aquatic plants, efficient in-situ removal of pollutants from the water and bottom sediment can be achieved. In addition, while removing pollutants from the water and bottom sediment, the electrochemically active microorganisms can be domesticated, forming a mature electrochemically active biofilm.

[0061] The microbial electrochemical remediation device of this invention possesses the characteristics of large specific surface area, easy affinity and attachment of microorganisms, which are inherent in biofilm remediation technology and can accelerate the removal of pollutants in water. It also has an ectopic electron compensation function similar to that of cable bacteria, which reflects electrochemical performance and accelerates the transfer of electrons from the oxidation process of reducing pollutants in sediment to electron acceptors in water, thereby achieving ectopic electron compensation. Thus, a novel microbial electrochemical remediation device that mimics cable bacteria is constructed.

[0062] In summary, on the one hand, the microbial electrochemical remediation device provided by this invention is plug-and-play, requiring no separate installation of anodes and cathodes and external circuits, and eliminating issues of circuit corrosion and energy recovery. This greatly simplifies construction and installation procedures, reducing the cost of electrode system construction and operation. Simultaneously, it overcomes the current density reduction effect of large electrode arrays during scaling up; electrons are conducted through the device's own conductive body, significantly reducing current density loss during electron transfer and ensuring enhanced system remediation effects. On the other hand, the microbial electrochemical remediation device provided by this invention can also be used in conjunction with one or more of online devices, voltage, or aquatic plants to further improve remediation efficiency. It can be applied to water environment and simultaneous sediment remediation, fundamentally solving the industry-wide problems of slow removal of anaerobic substances and difficulty in controlling endogenous pollution in currently contaminated sediments. After remediation, the microbial electrochemical remediation device provided by this invention can be easily removed and recycled for continued use in the joint remediation of sediments in other water-polluted areas.

[0063] To further illustrate the present invention, the following detailed description of the embodiments is provided in conjunction with the present invention, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0064] Example 1

[0065] (1) Construction of the repair device

[0066] A transparent acrylic cylinder was used as the reaction vessel. The vessel dimensions were as follows: diameter d = 20 cm; height h = 65 cm; volume 20.5 L; effective volume 18.8 L. The sediment was collected from the black and odorous sediment of the outer ring river in Tianjin. The sediment (95% moisture content) was homogenized and passed through a 5 mm sieve to remove impurities. The sediment (screened sediment) was then mixed with sludge (95% moisture content) from the thickening tank of a wastewater treatment plant. 浓缩池污泥 :m 底泥 =1:7). The easily degradable organic matter in the sediment was 12.34%, the ammonia nitrogen in the sediment was 0.5 g / Kg, and the total nitrogen in the sediment was 3 g / Kg. Using natural lake water as the upper water body, the water quality indicators were analyzed and monitored in the laboratory. The water quality of this lake met the water quality standard of Class V or worse. The water quality of the lake body is shown in Table 1.

[0067] Table 1 Water quality indicators of natural lakes

[0068]

[0069]

[0070] Repair device: The conductive body is a 65cm long titanium wire, and the conductive microbial carrier is a carbon fiber filament. The two are twisted together to form a carbon fiber brush as the repair device.

[0071] The carbon fiber brush repair device is placed vertically in the sediment and water body to be treated, such as... Figure 4 As shown, the lower part of the device is the sediment zone, and the upper part is the water zone. The distance between the bottom of the remediation device and the sediment / water interface is 23cm, and the remaining part exists in the water.

[0072] (2) Operating parameters of the repair device

[0073] The monitoring indicators and sampling frequency are as follows: Temperature, pH, dissolved oxygen (DO), and conductivity of the upper water layer are monitored daily. Redox potential, ROOM, and NH4+ in the bottom sediment are monitored monthly. + -N, NO3 - -N, TN, TP sediment quality indicators. The upper water layer is replaced weekly, and its water quality is monitored. Methanogenesis and N2O levels in the environment surrounding the remediation unit are continuously monitored.

[0074] (3) Operational effect of the repair device

[0075] During the 105-day operation, the redox potential of the sediments showed a certain downward trend. The percentage of easily degradable organic matter in the sediments decreased from 12.34% to about 10.5%, the ammonia nitrogen in the sediments decreased from 0.48 g / kg to 0.40 g / kg, and the total nitrogen in the sediments decreased from 3.05 g / kg to 2.40 g / kg.

[0076] The electrochemical performance of the microbial electrochemical remediation device was tested. The oxidation peak current and reduction peak current of the device were 3.21 mA and 4.21 mA, respectively. The obvious oxidation-reduction peaks of the device confirmed that it differentiated functional biofilms with good electrochemical activity.

[0077] During 15 consecutive operating cycles, the COD concentration in the effluent was less than 30 mg / L, meeting the Class IV water quality standard of the "Surface Water Environmental Quality Standard" (GB 3838-2002). The total nitrogen concentration was less than 2 mg / L, meeting the Class V water quality standard, and the ammonia nitrogen concentration was less than 0.5 mg / L, meeting the Class II water quality standard.

[0078] The present invention also analyzed the biophase and emitted pollutants of the microbial electrochemical remediation device provided in Example 1. First, the abundance of microorganisms related to the methane oxidation process increased from 0.01% to over 90%, the methane metabolic pathways increased significantly, and greenhouse gas emissions from the remediation area decreased. When the headspace gas above the plexiglass cylinder containing the remediation device was collected as the reaction vessel, no methane emissions were detected using gas chromatography.

[0079] Second: No N2O was detected during the operation of this remediation device. The remediation device provided by this invention can quickly oxidize ammonia nitrogen in water and reduce it in situ into nitrogen gas, thereby reducing N2O leakage. This demonstrates that the novel microbial electrochemical remediation device of this invention has excellent remediation efficiency for both water bodies and sediments, and has significant value in controlling greenhouse gas emissions from wetlands.

[0080] Example 2

[0081] Repair device: The conductive body is a 65cm long titanium wire, and the conductive microbial carrier is a carbon fiber filament. The two are twisted together to form a carbon fiber brush as the repair device.

[0082] (1) Construction of the repair device

[0083] The carbon fiber brushes in the water zone are 35cm long and 4cm in diameter, while those in the sediment zone are 18cm long and 4cm in diameter. They are connected by a 2cm long, 3mm diameter hollow stainless steel tube. A fixed resistor of approximately 3Ω is embedded within the stainless steel tube for protection and sealing, resulting in the repair device. Figure 5 As shown, the voltage data of the fixed resistor can be acquired by a voltage data acquisition device, which can then be used to determine the reaction efficiency and repair effect.

[0084] (2) Operation of the repair device

[0085] The repair device from step (1) can be vertically inserted into the columnar hole on the surface of the sediment to complete the construction.

[0086] The monitoring indicators and sampling frequency are as follows: Temperature, pH, dissolved oxygen (DO), and conductivity of the upper water layer are monitored daily. Redox potential, ROOM, and NH4+ in the bottom sediment are monitored monthly. + -N, NO3 - -N, TN, TP sediment quality indicators. The upper water layer is replaced weekly, and its water quality is monitored. Methanogenesis and N2O levels in the environment surrounding the remediation unit are continuously monitored.

[0087] (3) Results of the repair device operation

[0088] During the 105-day operation, the redox potential of the sediments showed a certain downward trend. The percentage of readily degradable organic matter in the sediments decreased from 12.34% to approximately 9.7%, the ammonia nitrogen in the sediments decreased from 0.48 g / kg to 0.36 g / kg, and the total nitrogen in the sediments decreased from 3.05 g / kg to 2.15 g / kg.

[0089] The electrochemical performance of the remediation device in Example 2 was tested. The oxidation peak current and reduction peak current of the biofilm in the remediation device were 4.88 mA and 6.56 mA, respectively. The obvious oxidation-reduction peaks of the biofilm in the remediation device confirmed that functional biofilms with good electrochemical activity were differentiated in the aerobic zone (water body) and anaerobic zone (sediment) of the remediation device, and the electrochemical properties were good.

[0090] During 15 consecutive operating cycles, the COD of the effluent was consistently <30 mg / L, meeting the Class IV surface water standard. The total nitrogen concentration was <2 mg / L, meeting the Class V water quality standard, and the ammonia nitrogen concentration was <0.5 mg / L, meeting the Class II water quality standard.

[0091] Example 3

[0092] Repair device: The conductive body is a 65cm long titanium wire, and the conductive microbial carrier is a carbon fiber filament. The two are twisted together to form a carbon fiber brush as the repair device.

[0093] (1) Construction of the repair device

[0094] A 65cm long carbon fiber brush was used as the restoration device, and submerged Vallisneria natans was planted around it for aquatic plant regulation. The planting density of Vallisneria natans was 200 plants per square meter of water surface. The aquatic plants were planted around the restoration device and evenly distributed. Figure 7 As shown. The specifications of the reaction vessel, the source of the sediment and the supernatant, the pretreatment method of the sediment, and the depth of the sediment and the supernatant are the same as in Example 1. The lower 23 cm of the remediation device is buried in the sediment, and the remaining part exists in the water.

[0095] (2) Operation of the repair device

[0096] The novel microbial electrochemical remediation device regulated by aquatic plants was vertically inserted into columnar holes on the surface of the sediment to complete the remediation device construction. No other instrumentation or equipment operation is required during operation; only periodic sample collection and measurement of relevant indicators are needed. The monitoring indicators and sampling frequency for water and sediment are the same as in Example 1.

[0097] (3) Results of the repair device operation

[0098] Figure 8 The graph showing the change of total nitrogen (TN) in bottom sediment over time, from Figure 8 It can be seen that during the 105-day operation, the percentage of readily degradable organic matter in the sediment decreased from 12.34% to 9.1%.

[0099] Figure 9 NH4 in bottom sediment + The graph showing the variation of -N over time, from Figure 9It can be seen that during the 105-day operation, the ammonia nitrogen in the sediment decreased from 0.48 g / kg to 0.37 g / kg.

[0100] Figure 10 The graph showing the variation of redox potential (ORP) in sediment, from... Figure 10 It can be seen that during the 105-day operation, the redox potential gradually increased by 50-60mV.

[0101] Figure 11 Electrochemical test diagrams of the repair device provided in Example 3; from Figure 11 It can be seen that the oxidation peak current and reduction peak current of the biofilm in the repair device are 5.04 mA and 5.97 mA, respectively. The obvious oxidation-reduction peaks confirm the excellent electrochemical properties of the biofilm.

[0102] Figure 12 The graph shows the COD concentration and removal rate curves of the upper water body in different periods. Figure 12 It can be seen that the COD of the effluent can be reduced to below 30 mg / L in 15 consecutive operating cycles, meeting the standard of Class IV surface water.

[0103] Figure 13 The graph shows the TN concentration and removal rate curves of the upper water body in different periods. Figure 13 It can be seen that the total nitrogen in the effluent can be reduced to below 2 mg / L, meeting the Class V water quality standard.

[0104] Figure 14 NH4 in the upper water body at different cycles + -N concentration and removal rate curve. From Figure 14 It can be seen that the ammonia nitrogen in the effluent has dropped to below 0.5 mg / L, meeting the Class V water quality standard.

[0105] Comparative Example 1

[0106] The only difference from Example 1 is that no microbial electrochemical remediation device was added for water remediation, and the composition of the biological phase was analyzed.

[0107] The present invention also analyzed the community abundance of archaea communities at the genus level in Examples 1, 2, and Comparative Example 1. The analysis results are shown in […]. Figure 15 ,from Figure 15It can be seen that *Candidatus Methanoperedens* had an absolute dominance in abundance in the remediation devices provided in Example 1 and Example 2, at 95.1% and 94.15% respectively, while the abundance of *Candidatus Methanoperedens* in the control reactor was <0.01%. Therefore, it can be inferred that the remediation device provided by this invention has a significant selective and enrichment effect on the methane-oxidizing bacterium *Candidatus Methanoperedens*, and that this archaea plays an important role in this research system. The operation of this system can enrich a large amount of *Candidatus Methanoperedens* for effectively controlling and degrading the greenhouse gas methane produced in anaerobic sediments, thus inhibiting methane emissions into the atmosphere. Therefore, this system has positive significance for improving methane metabolism levels, inhibiting anaerobic sediment bulking, and preventing and suppressing greenhouse gas emissions from natural shallow water bodies.

[0108] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for simultaneous remediation of water bodies and sediments using a microbial electrochemical remediation device, comprising the following steps: The microbial electrochemical remediation device is vertically deployed in the sediment and water body to remediate the sediment and water body; The remediation process involves the following: pollutants in the sediment undergo an oxidation reaction under the conditions of electroactive microorganisms in the sediment, releasing electrons. These electrons are then transferred to the water body by a microbial electrochemical remediation device. Oxidizing substances in the water body accept these electrons and undergo a reduction reaction in the presence of electroactive microorganisms. The microbial electrochemical remediation device includes a conductive body and a conductive microbial carrier disposed on the outside of the conductive body; during deployment, the bottom end of the microbial electrochemical remediation device is placed 0.1~2.0m below the sediment / water interface formed by the sediment and water body; the top end of the microbial electrochemical remediation device is located above the light-oxygen compensation depth, or, under sunlight irradiation, the dissolved oxygen in the water area where the top of the microbial electrochemical remediation device is located is ≥0.5 mg / L; The number of the microbial electrochemical remediation devices is ≥1; The conductive body is made of one or more of the following materials: metallic materials, carbon materials, and carbon-modified metallic materials. The conductive microbial carrier includes one or more of the following: carbon materials, carbon materials modified with metal oxides, carbon materials modified with metal sulfides, carbon materials modified with conductive polymers, and amorphous carbon materials. The conductive substrate and the conductive microbial carrier are twisted together to obtain a microbial electrochemical repair device.

2. The method of claim 1, wherein, The microbial electrochemical remediation device also includes a load resistor.

3. The method of claim 2, wherein, The repair process also includes using an online monitoring device to indicate the repair progress.

4. The method according to any one of claims 1 to 3, characterized in that, When the number of microbial electrochemical repair devices is greater than 1, the method further includes applying voltage to the microbial electrochemical repair devices.

5. The method of claim 4, wherein, The voltage applied between the microbial electrochemical repair devices ranges from 0.01 to 10 V / cm.

6. The method according to any one of claims 1 to 3, characterized in that, The repair process also includes coupling with aquatic plants.

7. The method according to any one of claims 1 to 3, characterized in that, The density of the arrangement is 1-100 microbial electrochemical remediation devices / m 2 .

Images